Note: Descriptions are shown in the official language in which they were submitted.
~WO 94/16143 1 ~ 1 5 3 3 ~ 5 PCT/US94/00551
PAPE~ PRODUCTS CONTAINING A
BIODEGRADABLE CHEMICAL SOFTENING COMPOSITION
FIELD OF THE INVENTION
This invention relates to tissue paper webs. More particularly, it relates to
soft, absorbent tissue paper webs which can be used in toweling, napkin, facial
tissue, and toilet tissue products.
BACKGROUND OF THE INVENTION
Paper webs or sheets, sometimes called tissue or paper tissue webs or
sheets, find ~xtensive use in modern society. Such items as paper towels,
napkins, facial and toilet tissues ars staple items of commerc~. It has lor~ been
recognized that three important physical attributes of these products are their
softness; their absorbency, particularly thsir absorbency for aqueous systems; and
their strength, particularly their strength when wet. Research and development
efforts have been directed to the improvement of each of thase attributes without
seriously affecting the others as well as to the improvement of two or three
attributes simultaneously.
Softness is the tactile sensation perceived by the consumer as he/she holds
a particular product, rubs it across his/her skin, or crumples it within hislher hand.
This tactile sensa~ion is a combination of several physical properties. One of the
more important physical properties related to soflness is generally c~nsidered by
~hose skilled Tn the art to be the stiffness of the paper web from which th~ product
is made. Stiffness, in turn, is usually considered to be directly dependent on tha
dry tensile strength of thc web and the stifln~ss of the fibers which make up the
web.
Strength is the ability of the product, and its constituent webs, to maintain
physical integrity and to resist tearing, bursting, and shredding under use
conditions, particularly when wet.
WO 94/16143 PCT/US94/0055~
~ ~;3~5 2 ~
Absorbency is the measure of the ability of a product, and its constitu~nt
webs, to absorb quantities of liquid, par~icularly aqueous solutions or dispersions.
Overall absorbency as perceived by the human consumer is generally considered
to be a combination of the total quantity of !iquid a given mass of tissue paper will
S absorb at saturation as well as the rate at which the mass absorbs the liquid.The use of wet strength resins to enhance the strength of a paper web is
widely known. For example, Westfelt described a number of such materials and
discussed their chemistry in Cellulose Chemistry and Technology, Volums 13, at
pages 813-825 (1979). Freimark ~t al. in U.S. Pat. No. 3,755,220 issued August
10 28, 1973 mention that certain chemical additives known as debonding a~ents
interfere with the natural fiber-to-fiber bonding that occurs during sh~et formation
in papermaking processes. This reduction in bonding leads to a softer, or less
harsh, sheet of paper. Freimarl< et al. go on te teach the use of wet strength resins
to enhance the wet strength of the sheet in conjunction with the use of debonding
15 agents to off-set undesirable effects of the wet strength resin. These debondin~
agents do reduce dry tensile strength, but there is also ~enerally a reduction in wet
tensile strength.
Shaw, in U.S. Pat. No. 3,821,068, issued June 28, 1974, also teaches that
chemical debonders can be used to reduce the stiffness, and thus anhance the
20 soflness, of a tissue paper web.
Chemical debonding agents have bean disclosed in various references
such as U.S. Pat. No. 3,554,862, issued to Hervey et al. on January 12, 1971.
These materials include quaternary ammonium salts such as
trimethylcocoammonium chloride, trimethyloleylammonium chloride,
25 di(hydrogenated) tallow dim~thyl ammonium chloride and trimethylstearyl
ammonium chloride.
Emanuelsson et al., in U.S. Pat. No. 4,144,122, issued March 13, 1979,
teach the use of complex quaternary ammonium compounds such as bis(alkoxy(2-
hydroxy)propylene) quatarnary ammonium chlorides to soflen webs. Thes~
30 authors also attempt to overcoms any decrease in absorbency c~use~ by the
debonders through ~he use of nonionic surfactants such as ethylene oxide and
propylene oxide adducts of fatty alcohols.
Arrnak Company, of Chicago, Illinois, in their bulletin 76-17 (1977) disclose
that tha us~ of dimethyl di(hydrogenated) tallow ammonium chloride in
35 combination with fa~ty acid esters of polyoxyethylene glycols may impart both softness and absorbency to tissue paper webs.
-
~ ~ 5 ~ 3 ~ 5 PCT/US94/00551
WO 94/16143
3
One exemplary result ot research directed toward improved paper webs is
described in U.S. Pat. No. 3,301,746, issued to Sanford and Sisson on January
31, 1967. Despite the high quality of paper webs made by the process descnbed inthis patent, and despite the commercial success of products formed from these
5 webs, research efforts directed to finding improved products have continued.
For example, Becker et al. in U.S. Pat. No. 4,158,594, issued January 19,
1979, describe a method they contend will ~orm a strong, soft, ~brous sheet. More
specifically, they teach that the strength of a tissue paper web (which may havebeen softened by the addition of chemical debonding agents) can be enhanced by
10 adhering, during processing, one surface of the web to a creping surface in a fine
patterned arrangement by a bonding material (such as an acrylic latex rubber
emulsion, a water soluble resin, or an elastomeric bonding material) which has
been adhered to one surface of the web and to the creping surface in the fine
pafferned arrangement, and creping the web from the creping surface lto form a
15 sheet material.
¢onventional quaternary ammonium compounds such as the well known
dialkyl dimethyl ammonium salts (e.~. ditallow dimQthyl ammonium chloride,
ditatlow dimethyl ammonium methyl sulfate, di(hydro~enated) tallow dimethyl
ammonium chloride etc ...) are effectiv~ chemical debondin~ agents.
20 Unfortunately, these ~uatemary ammonium compounds are not bioJe~r~ blQ
Applicant has discovered that biodegradabls mono- and di-ester variations of
these quaternsry ammonium salts also function effectively as chemical debonding
agents and enhance the softness of fibrous cellulose materials.
It is an object of this invention to provide a solt, absorbent toilet tissue paper
25 products
It is an object of this invention to provide a soft, absorbent facial tissu~
paper products,
It is an object of this invention to provide soft, absorbent towel paper
prod~cts.
n iS also a further object of this invention to provide a process for makin~
soft, absorbent tissue and towel paper products.
These and other objects are obtainsd using the present invention, as will
become readily apparent from a reaJing of the following ~sclosure.
WO 94/16143 Ç~ 3 i 4 PCT/US9410055~j~
SUMMARY OF THE INVENTION
The present invention provides so~, absorbent paper product. ~riefly, the
paper products comprise a sheet of cellulose material and from about 0.005% to
5 about 5% by weight of the fibrous cellulose material of a biodegradable chemical
softening composition comprising a mixture of:
(a) a quaternized ester-amine compound having the formula
~O O
R2 (~H2)2 - O - C - R3
Nl X~
/ \
R2 R1
or
R2 (CH2)2 - O - C - R3
N~ X-
R2 ~CH2)2 - O - C - R3
wherein each R2 substituent is a C1 - C6 alkyl or hydroxyalkyl
group, or mixture thereof; each R1 substituent is a C14 - C22
hydrocarbyl group, or mixture thereof; each t~3 subtituent is a
C12-C20 hydrocarbyl group, or mixture thereof; and X- is a
compP1ibl~ anion; and
(b) a polyhydroxy compound selected from the group consisting of
glycerol, and polyethylene glycols and polypropylene glycols
having a weight average molecular weight from about 200 to 4000;
~WO 94/16143 21 5 3 3 1~ PCT/US94/00551
wherein the weight ratio of the quaternized ester-amine compound to the
polyhydroxy compound ranges from about 1: 0.1 to 0.1: 1; and wherein said
polyhydroxy compound is miscible with the quaternized ester-amine compound at
5 a temperature of at least 50C.
Preferably, the mixture of the quaternized ester-amine and the
polyhydroxy compound is diluted with a liquid carrier to a concentration of fromabout 0.01% to about 25.0% by weight of the chemical softening composition
before beingaddedtothe fibrouscellulose material. Preferably,thetemperature
10 of the liquid carrier ranges from about 40 C to about 80 C and the pH is less than
about 4. Preferably, at least 20% ot the polyhydroxy compound and the
quaternized ester-amine compound added to the fibrous cellulose are retained.
Examples of preferred quaternized ester-amine compounds suitable for use
15 in the present invention include compounds having the formulas:
(CH3)2 - N+ - CH2CH2 - O - C - C16H33 X
C1gH37
and
O
(CH3)2 - N+ - (CH2CH2 - O - C - C16H33)2 X-
Thes~ compounds can be considered 2O be mono and diester variations of the
well-known dialkyldimethylammonium salts such as diester ditallow dimethyl
ammonium chloride, monoester ditallow dimethyl ammonium chlorid~, diester
30 di(hydrogenated)tallow dimethyl ammonium methylsulfate, diester
di(hydrogenated)tallow dimethyl ammonium chloride, monoester
di(hydrogenated)tallow dimethyl ammonium chloride, with the diester variations of
di(non hydrogenated)tallow dimethyl ammonium chloride, di(touch
hydrogenated)tallow dimethyl ammonium chloride and di(hydrogenated)tallow
35 dimethyl ammonium chloride being preferred. Depending upon the product
characteristic requirements, the saturation level of the ditallow can be tailored from
non hydrogenated (soft) to touch, partial or complete hydrogenation (hard).
~Çi PCT/US94/0055~_
WO 94/16143 ~,~33 6 ~
Wlthout being bound by theory, it is belie~ed that the ester moiety(ies) lends
biodegradability to thes~ compounds. Importantly, the quaternized ester-amine
compounds used herein biodegrade more rapidly than conventional dialkyl
dimethyl ammonium chemical softeners.
Examples of polyhydroxy compounds useful in the present invention include
glycerol and polyethylene glycols having a weight average molecular weight of
from about 200 to about 4000, with polyethylene glycols having a weight average
molecular weight of from about 200 to about 600 bein~ prefe-red.
A particularly preferred tissue paper embodiment of the present invention
comprises from about 0.03% to about 0.5% by weight of the mixture of quaternizedester-amine compound and the polyhydroxy compound.
Briefly, the process for making the tissue webs o} the present invention
comprises the steps of formation is a papermaking furnish from the
aforementioned components, deposition of the papermaking furnish onto a
foraminous surfacc such as a l:ourdrinier wire, and removal of the water from the
deposited furnish.
All percentages, ratios and proportions her~in are by wei3ht unless
oth~rwiss specified.
BRIEF DESCRiPTlON OF THE DRAWINGS
While the Specification concludes with claims pa~ticularly pointing out and
and distinctly claiming the present invention. it is believed the invention is better
undcrstood from the following description taken in conjunction with the ~ssoci~ted
drawings, in which:
Figura 1 is a phas~ diagram of DODMAMS and DHTDMAMS.
Figure 2 is a phase diagram of DODMAMS and PEG-400 system.
Figure 3 is a phase diagrarn of PEG-400/methyl oclanoal~ system.
Figure 4 is a phase diagram of DEDTDMAC and PEG-400 system.
Figure 5 is a phase diagram of DEDHTDMAC and PEG-400 system.
Figure 6 is a cryo-transmission micro-photograph taken at X 63,000 of the
vesicle dispersion of a 1: 1 by weight ratio of a diester ditallow dimsthyl
ammonium chloride and PEG-400 system.
Figure 7 is a cryo-transmission micro-photograph taken at X 63,000 of the
vesicle dispersion o~ a 1: 1 by weight ratio of a diester ditallow dimethyl
ammonium chlorids and glycerol system.
Figure 8 is a cryo-transmission micro-photograph taken at X 66,000 of the
,
~WO 94/16143 21~ ~ 3 1~ PCTIUS94/OOS51
ve~icle d~spcrsion ol a 1: 1 by weight ratio of a diester di(hydrogenated)
tallow dimethyl ammonium chloride and PEG-400 system.
The present invention is described in more detail below.
DETAILED DESCRIPTION OF THE INVENTION
While this specification concludes with claims particularly pointing out and
distinctly claiming the subject matter regarded as the invention, it is believed that
the invention can be better understood from a reading of the following detailed
description and of the appended examples.
As used herein, the terms tissue paper web, paper web, web, paper sheat
and paper product all refer to sheets oS paper made by a process comprising the
steps of forming an aqueous papermaking furnish, depositing this furnish on a
foraminous surface, such as a Fourdrinier wire, and removing the water from the
furnish as by gravity or vacuum-assisted drainage, with or without pressing, and by
evaporation.
As used herein, an aqueous papermaking furnish is an a~ueous slurry of
papermaking tibers and the chemicals describ~d hereinafter.
The first step in the proc~ss of this invention is the forming of an aqueous
papermaking furnish. Th~ furnish comprises papermaking fibers (hereinafter
sometimes re1erred to as wood pulp), and a mixture of at least one quaternized
ester-amine compound and at least one polyhydroxy compound, all of which will
be hersinafler descfibed.
It is anticipated that wood pulp in all its varieties will normally compfise thepapermaking fibers used in this invention. However, oth~r cellulose fibrous pulps,
such as cotton liners, b~ sse, rayon, etc., can be used and none are disclaimed.Wood pulps useful herein include chemical pulps such as Kraft, sulfite and sulfate
pulps as well as mechanical pulps including for exampb, ~round wood,
thsrmomechanical pulps and chemically modified therrnomechanical pulp (CTMP).
Pulps defived from both deciduous and coniferous trees can b~ used. Also
applicable to the present invention are fibers derived from recycled paper, which
may contain any or all of the above cate~ories as well as other non-fibrous
materials such as fillers and adhesives used to facilitate the original papermaking.
Preferably, the papermaking fibers used in this invention comprise Kraft pulp
derived from northem softwoods.
WO 9~116143 PCT/US94/0055~
~J~ ~33~ 8 ~
Blode~radable Chemlcal Sottener Composltlon~
The present invention contains as an essential component from about
0.005% to about 5%, more preferably from about 0.03% to 0.5% by weight, on a
dry fiber basis of a mixture of a quaternized ester-amine compound and a
5 polyhydroxy compound. The ratio of the quaternized ester-amine compound to thepolyhydroxy compound ranges from about 1: 0.1 to 0.1: 1; preferably, the weight
ratio of the quaternized ester-amine compound to the polyhydroxy compound is
about 1: 0.3 to 0.3: 1; more preferably, the weight ratio of the quaternized ester-
amine compound to the polyhydroxy compound is about 1: 0.7 to 0.7: 1,
10 although this ratio will vary dependins upon the molecular weight of the particular
polyhdroxy compound and/or quaternized ester-amine compound used.
Each of these types of compounds will be described in detail below.
A. Quaternized Ester-Amine Compound
The chemical softening composition contains as an essential component a
15 quaternized sster-arnine compound having the formula:
R2 ~ (CH2)2 - O - C R3
N~ X-
R2 R
or
o
R2 / (CH2)2 - O - C - R3
Nl X-
/ \
R2 (CH2)2 - O - C - R3
In tha structures named abov~ each R1 is a C14-C22 hydrocarbyl group, preferably35 tallow C16 - C18 alkyl; R2 is a C1 - C6 alkyl or hydroxyalkyl group, preSerably C1-C3
alkyl; R3 is C12-C20 hydrocarbyl group, preferably C14-C16 alkyl, X~ is a compatibls
anion, such as an halide (e.g. chloride or bromide) or methyl sulfate. As discussed
~WO 94/16143 9 21 S ~ 31~ PCT/US94/00551
in Swern, Ed. in Bailey's Industrial Oil and Fat Products, Third Edition, John Wiley
and Sons (New York 1964), tallow is a naturally occurring material having a
variable composition. Table 6.13 in the above-identified reference edited by Swern
indicates that typically 78% or more of the ~atty acids of tallow contain 16 or 18
carbon atoms. Typically, half of the ~atty acids present in tallow are unsaturated,
primarily in the form of oleic acid. Synthetic as well as natural ~allows~ fall within
the scope of the present invention. It is also known that depending upon the
product characteristic requirements, th~ saturation level ot the ditallow can betailored from non hydrogenated (sofl) to touch, partial or complete hydrogenation
1 0 (hard).
It will be understood that substituents R1, R2, R3 may optionally be
substituted with various groups such as alkoxyl, hydroxyl, or can b~ branched, but
such materials are not preferred herein. Preferably, each R1 is C16-C1s alkyl, most
preferably each R1 is straight-chain C1s alkyl. Preferably, each R2 is methyl.
15 Preferably R3 is C14-C16 alkyl, most preferably R3 is straight chain C16 alkyl and
X- is chloride or methyl sulfate.
Specific examples of quaternized ester-amine compounds having the
stnuctures named above and suitable for use in the present invention include thswell-known diester dialkyl dimethyl ammonium salts such as diester ditallow
20 dim~thyl ammonium chloride, monoester ditallow dimethyl ammoniun~ chloride,
diester ditallow dimethyl ammonium msthyl sulfate, diester di(hydrogenated)tallow
dimethyl ammonium methyl sulfate, diester di(hydrogenated)tallow dimethyl
ammonium chloride. Diester ditallow dimethyl ammonium chloride and diester
di~hydrogenated)tallow dimethyl ammonium chloride are particularly preferred.
25 These particular materials are available commercially from Sherex Chemical
Company Inc. of Dublin, Ohio under the tradename ~ADOGEN DDMC R ~,
Di-quat variations of the quaternized ester-amine compound can also be
used, and are meant to ~all within the scope of the present invention. These
compounds have the ~ormula:
3~
O (R~ 2)2 ( ~R2)2
R3 - C - O- (CH2k- N+ - (CH2)2- N~ - (CH2)2 - O - C - R3 2 X
In the structure named above each R2 is a C1 - C6 alkyl or hydroalkyl group, R3 is
C12-C20 hydrocarbyl group, X is a compatible anion, such as an halide ~e.g.,
WO 94/16143 PCT/US94/005~
,~3~ 10
chlorid~ or br~ tde) or me~hyl sulfate. Preferably, each R3 is C14-C16 alkyl, most
preferably each R3 is straight~hain C16 a1kyl, and R2 is a methyl.
B. Polyhydroxy Compound
The chemical softening composition contains as an essential component a
5 polyhydroxy compound.
Examples of polyhydroxy compounds usetul in the present invention include
glycerol, and poiyethylene glycols and polypropylene ~Iycols having a weight
average molecular weight of from about 200 to about 4000, preferably from about
200 to about 1000, most preferably from about 200 to about 600. Polyethylene
10 glycols having an weight average molecular weight of from about 200 to about 600
are especially preferred.
A particularly preferred polyhydroxy compound is polyethylene glycol having
an weight average molecular weight of about 400. This material is availabl~
commercially from the Union Carbide Company of Danbury, Connecticut under the
15 tradename~PEG-400~.
The chemical softening composition described abov~ i.e. mixture of a
quaternized es~er-amine compounds and a polyhydroxy compound are preferably
added to the aqueous slurry of papermahng fibers, or furnish, in the wet end of the
20 papermaking machins at some suitable point ahead of the Fourdrini~r wire or
sheet forming stage. However, applications of the above described chemical
chemical soflening composition subsequent to formation of a wet tissuQ web and
prior to drying of the web to completion will also provide significant softness,absorbency, and wet strength Ibenefits and are expressly included within the scope
25 of the present invention.
It has b~en discovered that the chemical soflening composition is more
effectivc when the quaternized ester-amine compound and the polyhydroxy
compound are first pre-mixed to~ether before bein~ added to the papermaking
furnish. A preferred ~ thod, as will be described in ~reatar detall her~inafler in
30 Example 1, consists of first heating the polyhydroxy compound to a temperature of
about 66 C (1 50F), and then adding ths quaternized ester-amin~ compound to
the hot polyhydroxy compound to form a fluidized ~melt~. The wei~ht ratio of thequaternized ester-amine compound to the polyhydroxy compound ranges from
about 1: 0.1 to 0.1: 1; preferably, the weight ratio of the quatemized ester-amine
35 compound to ths compound is about 1: 0.3 to 0.3: 1; more preferably, the weight
ratio of the quaternized estsr-amine compound to the compound is about 1: 0.7
to 0.7: 1, although this ratio will vary depending upon the molecular weight of the
~WO 94/16143 21 S 3 ~ 15 PCT/US94/00551
particu~ar compound and/or qua~ernized es~er-amine compound used. The
qua~ernized ester-amine compound and polyhydroxy compound melt is then
diluted to the desired concentration, and mixed to lorm an aqueous solution
containing a vesicle dispersion of the quaternized ester-amins compound /
polyhydroxy compound mixture which is then added to the papermaking furnish.
Preferably, the mixture of the quaternized ester-amine compound and polyhdroxy
compound is diluted with a liquid carrier such as water to a concentration of from
about 0.01% to about 25% by weight of the softening composition before being
added to the papermaking furnish. The pH of the liquid carrier preferably rangesfrom 2 to 4. The temperature of the liquid carrier preferably ranges from about 40
C to about 80 C. The mixture of the quaternized ester-amine compound and the
polyhdroxy compound are present as particles dispersed in the liquid carrier. The
average particle size preferably ranges from about 0.01 to 10 microns, most
preferably from about 0.1 to about 1.0 micron. As shown in Figures 6 - 8, the
dispersed particles are in the form of vesicle particles.
The quaternized ester-a~nine compound and the polyhdroxy compound are
mixed at an elevated temperature of at least 50 C, more preferably from about
50 C to about 100 C. Without wishing to be bound by theory, it is believed at ~he
preferred temperature range, that both Diester Ditallow Dimethyl Ammonium
Chloride (DEDTDMAC) and Diester Di(hydrogenated)tallow Dimethyl Ammonium
Chloride. (DEDHTDMAC.) are in a liquid phase and are miscible with tha
polyhdroxy compound. The physical states of Di(hydrogenated) tallow Dimethyl
Ammonium Methyl sulfate (DHTDMAMS) will be discussed in greater detail
hereinafter.
The papermaking furnish can be readily formed or prepared by mixing
techniques and equipment well known to those skilled in the pape-~"akin~ art.
It has unexpectedly been found that the adsorption of the polyhydroxy
compound onto paper is significantly enhanced when it is premixed with the
quaternized ester-amine compound betore bein~ added to the paper. In iact, at
least 20% of the polyhydroxy compound and the quaternized estar-amine
compound aWed to the fibrous cellulose are retaine-J; and preferably, the retention
level of quatemized ester-amine compound and the polyhydroxy compound is from
about 50% to about 90% by weight of the dry fibers.
Importantly, adsorption occurs at a concentration and within a tirne frame
that are practical for use during paper making. In an effort to better understand the
surprisingly high retention rate of polyhydroxy compound onto the paper, the
physical science of the melted solution and the aqueous dispersion of a
PCTIUS94/0055~
WO 94/16143 ~ 3~ 12 ~
di(hydrog~nat~d) tallow dimethyl ammonium methyl sulfate and polyethylene
glycol 400 were studied.
Without wishing to be bound by theory, or to othenvise limit th~ present
invention, the followin~ discussion is offered for explaining how the quaternary5 ammonium compound promotes the adsorp!ion of the polyhydroxy compound onto
paper.
InSormation on the physical state of DHTDMAMS Di(hydrogenated)Tallow
dimethyl Ammonium Methyl Sulfate, (C17H3s)2N+(CH3)2,C~13OSO~~
DODMAMS (DiOctadecyl Dimethyl Ammonium Methyl Sulfate,
10 (C18H37)2N+(CH3)2.CH3OSO3-J; DEDTDMAC ((Diester Ditallow Dimethyl
Ammonium Chloride, (CH3)2N+(CH2CH20COC16H33)2,CI-) and DEDHTDMAC
(Diester Di(hydrogenated) Tallow Dimethyl Ammonium Chloride) is provided by X-
ray and NMR data on the commercial mixture. DODMAMS is a major component
of DHTDMAMS, and serves as a model compound for tha commercial mixture. I~
15 is useful to consid~r first the simpler DODMAMS system, and then She more
complex commercial DHTDMAMS mixture.
Depending on the temperature, DODMAMS may exist in any of four phase
states (Figurs 1): two polymorphic crystals (X~ and Xa), a lamellar (Lam) liquid-
crystal, or a liquid phase. The X~ crystal exists from below room tsmpsraturQ to20 47 C. At this tsmperature it is transfo~ed into the polymorphic X crystal, which
at 72 C is transformed into the Lam liquid crystal phase. This phase, in turn, is
transformed into an isotropic liquid a~ 150 C. A lamellar (Lam) liquid-crystal
phase does also exist in both DEDTDMAC and DEDHTDMAC compounds.
DHTDMAMS is expected to resemble DO~IAMS in its physical behavior, excapt
25 that the temperatures of the phase ~ran~iohs will be lowered and broaden~d. For
example, the transition from ~he X~ 1O the xa crystal occurs at 27 C in
DHTDMAMS instead ot 47 C as in DODMAMS. Also, calorimetric data indicate
that several clystal --->Lam phase transitions occur in DHTDMAMS rather than
one as in DODMAMS. The onset t~ p~r~ture of the high~st of these transitions
30 is 56 C, in good agreement with the X-ray data, but calorirnetly displays two
peaks with onset temparatures ot 59 and 63 C.
DODMAC (DiOctad~.,yl Dimethyl Ammonium Chlorids) displays qualitativeb
different behavior from DODMAMS and in that ths Lam liquTd crystal phase does
not exist in this compound. This difference, howevsr, is believed not to be
35 important to the ùse of this compound (or its commercial analog DHTDMAC) in ths
treatment of paper. (Laughlin et al., Journal of Physical Chemistry, Physlcal
Sclence of the DloctadecyldTme~hylammonlum Chlorlde-Water System. 1.
~WO 94/16143 ~ 15 3 3 1 5 PCT/US94100551
13
Equlllbr~um ~has~ Behavlor, 1990, volume 94, pages 2546-2552, incorporated
herein by referenc~.
Mixtures ot DHTDMA~S wlth PEG 400.
A 1:1 weight ratio mixture o~ these two materials is studied, and a plausible
5 model ~or the phase behavior of this system is suggested in Figure 2. In this
diagram DODMAMS and PEG are shown to be immiscible at high temperatures,
where they coexist as two liquid phases. As mixtures of the two liquids wi~hin this
region are c~oled, a Lam phase separates from the mixture. This study therefore
shows that these two materials while immiscible at high temperatures do become
10 miscible at lower temperatures within the Lam liquid crystal phase. At still lower
temperatures c~stal phases are expected to separate from the Lam phase, and
the compounds are again immiscible.
These studies therefore suggest that in order to form good dispersions of
DHTDMAMS and PEG -400 in water, the premix that is diluted with water should
15 be held within the intermediate temperature range where the two compounds are miscible.
Mlxtures of DHTDMAC wlth PEG 400.
Phase studies of these two materials using the st~p-wise dilution mathod
demonstrate that their physical behavior is considerably different from that of
20 DHTDMAMS. No liquid crystal phases arc found. Th~se compounds arc miscibb
over a wide rangs of temperatures, which indicates that dispersions may b~
prepared from these mixtures over a comparable range of temperatures. No upper
temperatur~ limit of miscibility exists.
Mlxtures ot DEDTDMAC wlth PEG 400.
25 Phase studies (Flgure 4) of these two materials usin~ the step-wise dilution
method demonstrate that their physical behavior is similar from that of
DHTDMAC. These compounds are misdble over a wide range of temperatures (>
50 C), which indicates that dispersions may bs prepared from these mixtures
over a comparablc range of temperatures. No uppertemperature limit of ",isc;bility
30 ~xists.
Mlxtures of DEDHTDMAC wlth PEG 400,
Phase studies (Figure 5) of these two materials using the step-wise dilution
method demonstrate that their physical behavior is similar from that ot
DHTDMAC. These compounds are miscible over a wide range of temperatures (>
35 67 C), which indicates that dispersions may be prepared from these mixtures
overa comparable range of temperatures. No uppertemperature limit of Illiscibility
exists.
WO 94/16143 2~33~5 PCT/US94/0055~
Preparatlon of dlsperslons.
Dispersions of either of these materials may be prepared by diluting a
mixture, that is held at a temperature at which the polyhydroxy compound and thequaternary ammonium salt are miscible, with water. It does not matter ~reatly
whether they are miscible within a liquid crystalline phase (as in the case of
DHTDMAMS), or in a liquid phase (as in the case of DHTDMAC). Neither
DHTDMAMS nor DHTDMAC are soluble in water, so the dilution of either dry
phase with water will precipitate the qua~ernary ammonium compound as small
panicles. Both quaternary ammonium compounds will precipitate at elevated
temperatures as a liquid-crystal phase in dilute aqueous solutions, regardless of
whether the dry solution was liquid or liquid crystalline. The polyhydroxy
compound is soluble with water in all proportions, so it is not precipitated.
Cryoelectron microscopy demonstrates that the particles present are about
0.1 to 1.0 micrometers in size, and highly varied in structure. Some are sheets
(curved or flat), while others are closed vesicles. The membranes of all these
particles are bilayers of molecular dimensions in which the head groups ars
exposed to water, the tails are together. The PEG is presumed to be ~ssociated
with these particles. The application of dispersions prepared in this manner to
paper results in attachment of the quaternary amn onium ion to the paper, strongiy
promotes th3 adsorption of the polyhydroxy compound onto papsr, and pro~uces
the desired modification of softness and retention of wettability.
StatQ of the dlsperslons.
When the abov~ described dispersions are cooled, the partial cryst~ fion
of the material within the colloidal particles may occur. However, it is likely that the
attainment of the equilibrium state will require a long time (perhaps months), so
that a disordered particle whose membranes are eiSher a liquid crystal or a
disordered crysta1 phase is interacting with the paper. Preferably, the chemicalsoftening compositions described herein are used before the equilibrium state has
been attained.
It is believed that the vesicles containing DHTDMAMS and PEG break apar~
upon drying of the fibrous cellulosic material. Once the vesicle is broken, the
majority of the PEG ¢omponent penetrates into the interior of the oellulose fibars
where it enhances the fiber flexibility. Importantly, some of the PEG Is retained on
the surface of the fiber where it acts to enhance the absorbency rate of th~
celluiose fibers. Due to ionic interaction, the cationic portion of the DHTDMAMScomponent stays on the surface of the cellulose fiber where it enhances the
surface feel and softness of the paper product.
~WO 94/16143 215 3 ~15 PCT/US94/00551
The second step in the process of this invention is the deposi~ing of the
papermaking furnish using the above described chemical softener composition as
an additive on a foraminous surface and the third step is the removing of the water
from the furnish so deposited. Techniques and equipment which can be used to
accomplish these two processing steps will b~ readily apparent to those skilled in
the papermaking art. Prefered tissue paper embodiments of the present invention
contain from about 0.005% to a~out 5.0æ, more preferabl~r from about 0.03% to
0.5% by weight, on a dry fiber basis of the chemical softening composition
described herein.
The present invention is applicable to tissue paper in general, including but
not limited to conventionally felt-pressed tissue paper; pattern densified tissue
paper such as exemplified in the aforementioned U.S. Patent by Sanford-Sisson
and its progeny; and high bulk, uncompacted tissue paper such as exemplified by
U.S. Patent 3,812,000, Salvucci, Jr., issued May 21, 1974. The tissue papsr may
be of a homogenous or multilayered construction; and tissue paper products made
therefrom may be ot a single-ply or multi-ply construction. Tissus structures
formed ~rom layered paper webs are described in U.S. Pat~nt 3,994,771, Morgan,
Jr. et al. issued November 30, 1976, and incorporated herein by reference. In
~eneral, a wet-laid composite, soft, bulky and absorbent paper structurs is
prepared from two or more layers of furnish which are preferably comprised of
different fiber types. The layers are preferably formed from the deposition of
separate streams of dilute fiber slurries, ths fibers typically being relatively long
soRwood and relatively short hardwood nbers as used in tissue papermaking, upon
one or more endless foraminous screens. Th~ layers are subse~uently combined
to form a layered composite web. The layer web is subsequently c~used to
conforrn to the surface of an open mesh dryingfilmprinting fabric by ths application
of a fluid to force to the web and thereafter thermally predried on said fabric as pan
of a low density papermaking process. The layered web may be stratified with
respect to fiber type or the tiber content of the respectiva layers may be assentially
the sarne. The tissue paper preferably has a basts weight of between 10 9/m2 andabout 65 g/m2, and density of about 0.60 g/cc or less. Preferably, basis weight will
be below about 35 9/m2 or less; and density will b~ about 0.30 g/cc or less. Most
preferably, density will be between 0.04 g/cc and about 0.20 g/cc.
Conventionally pressed tissue paper and methods for making such paper
are known in the art. Such paper is typically made by depositing papermahng
turnish on a foraminous forming wire. This forming wire is often referred to in the
WO 94/16143 2 ~ 3 3 ~ 16 PCT/US94/0055
art as a Fourdrinier wire. Once the furnish is deposited on the forming wire, it is
referred to as a web. The web is dewatered by pressing the web and drying at
elevated temperature. The particular techniques and typical equipment for makingwebs according to the process just described are well known to those skilled in the
art. In a typical process, a low consistency pulp furnish is provided in a pressurized
headbox. The headbox has an opening ~or delivering a thin deposit of pulp furnish
onto the Fourdrinier wire to form a wet web. The web is then typically dewatered to
a fiber consistency of between about 7% and about 25% (~otal web weight basis~
by vacuum dewatering and further dried by pressing operations wherein the web issubjected to pressure developed by opposing mechanical members, for example,
cylindrical rolls.
The dewatered web is then further pressed and dried by a stream drum
apparatus known in the art as a Yanke~ dryer. Pressure can be developed at the
Yankee d~er by mechanical means such as an opposing cylindrical dn~m pressing
against the web. Vacuum may also be applied to the web as it is pressed against
the Yankee surface. Multiple Yankee dryer drums may be ~mployed, whereby
additional pressing is optionally incurred between the drums. The tissue paper
structures which are formed ar~ referred to hereinaRer as conventional, pressed,tissu~ paper structures. Such sheets are considered to be compacted since the
web is subjected to substantial overall mechanical compressional forces while th~
fibars are mois~ and are then d~ied (and optionally creped) whils in a compressed
stat~.
Pattern densifi~d tissue paper is characterizsd by havin~ a relative~ high
bulk field of relatively low fiber density and an array of densified zones of relatiY~ly
high iiber density. The high b~llk field is alternatively charactariz~d as a field of
pillow regions. The densified zones are alternatively referred to as knuckle r~;ons.
The densified zones may b2 discretely sp~ced within the high bulk field or may be
interconnected, either fully or partially, within the high bulk field. Preferradprocesses for makin~ pattern densified tissue webs are ~J;cclQse~J in U.S. Patant
No. 3,301,746, issued to Sanford and Sisson on January 31, 1967, U.S. Patent
Ho. 3,974,025, issued to P~ter G. Ayers on August 10,1976, and U.S. Patent No.
4,191,609, issued to Paul D. Trokhan on March 4, 1980, and tJ.S. Pat~nt
4,637,859, issued to Paul D. Trokhan on January 20, 1987; all of which are
incorporated herein by reference.
In general, pattern densif;ed webs are preferably prepared by depositing a
papermaking furnish on a foraminous forming wire such as a Fourdrinier wire to
form a wet web and then juxtaposing the web against an array of supports. The
~WO 94/16143 ~ 1 ~i 3 3 1 ~ PCT/US94/00551
17
web is Fresse~ against the array of supports, thereby resulting in densified zones
in the web at the locations geographically corresponding to the poin~s of contact
between th~ array of supports and the wet web. The remainder of the web not
compressed during this operation is referred to as the high bulk field. This high
bulk field can be further dedensified by application of fluid pressure, such as with a
vacuum type device or a blow-through dryer, or by mechanically pressing the web
against the array of supports. The web is dewatered, and optionally predried, insuch a manner so as to substantially avoid compression of the high bulk field. This
is preferably accomplished by fluid pressure, such as with a vacuum type device or
blow-through dryer, or alternately by mechanically pressing the web against an
array of supports wherein the high bulk field is not compressed. The operations of
dewatering, optional predrying and formation of the densified zones may be
integrated or partially integrated to reduce the total number of processing steps
performed. Subsequent to formation of the densifled zones, dewatering, and
optional predrying, the web is dried to completion, preferably still avoiding
mechanical pressing. Preferably, from about 8% to about 55% of the tissue paper
surface comprises densified knuckles having a relative density of at least 125% of
the density of the high bulk field.
The array of supports is preferably an imprinting carrier fabric havin~ a
patterned displacement of knuckles which operate as the array of supports which
facilitate the formation of ths densified zones upon application of pressure. Ths
pattern of knuckles constitutes the array of supports previously reterred to.
Imprinting carrier fabrics are disclosed in U.S. Patent No. 3,301,746, Sanford and
Sisson, issued January 31, 1967, U.S. Patent No. 3,821,068, Salvucci, Jr. et al .,
issued May 21,1974, U.S. Patent No. 3,974,025, Ayers, issued August 10,1976,
U.S. Patent No. 3,573,164, Friedberg et al ., issued March 30, 1971, U.S. PatentNo. 3,473,576, Amneus, issued October 21, 1969, U.S. Patent No. 4,239,065,
Trokhan, issued Decei"ber 16, 19~0, and U.S. Patent Ho. 4,528,239, Trokhan,
issued July 9,1985, all of which are incorporated herein by reference.
Preferably, the furnish is nrst formed into a wet web on a foraminous
lforming carrier, such as a Fourdrinier wire. The web is dewatered and transferred
to an imprinting fabric. The furnish may alternately be initially deposited on aforaminous supporling carrier which also operates as an imprinting fabric. Once
formed, the wet web is dewatered and, preferably, thermally predried to a selected
fiber consistency of between about 40% and about 80%. Dewatering can be
performed with suction boxes or other vacuum devices or with blow-through
dryers. The knuckle imprint of the imprinting fabric is impressed in the web as
WO 94/16143 PCT/US94/0055a~,
3~ 1 8
discussed above, prior to drying the web to completion. One method tor
accomplishing this is through application of mechanical pressurs. This can be
done, for example, by pressing a nip roll which supports the imprinting fabric
against the face of a drying drum, such as a Yankee dryer, wherein the web is
5 disposed beh~een the nip roll and drying drum. Also, preferably, the web is molded
against the imprinting fabric prior to cornpletion of drying by application of fluid
pressure with a vacuum device such as a suction box, or with a blow-through
dryar. Fluid pressure may be applied to induce impression of densified zones
during initial dewatering, in a separate, subsequent process stage, or a
10 combinalion thereof.
Uncompacted, nonpattern-densified tissue paper stn~ctures are described in
U.S. Patent No. 3,812,000 issued to Joseph L. Salvucci, Jr. and Peter N. Yiannoson May 21, 1974 and U.S. Patent No. 4,208,459, issued to Henry E. Becker, Alben
L. McConnell, and Richard Schutte on June 17, 1980, both of which are
15 incorporated herein by reference. In general, uncompacted, non panern densified
tissue paper structures are prepared by depositing a papermakin~ furnish on a
foraminous forming wire such as a Fourdrinisr wire to form a wet web, drainin~ th~
web and removing additional water without mechanical compression until ths web
has a fiber consistency ot at least 80%, and creping the web. Water is removed
20 from the web by vacuum dewatering and thermal drying. The resulting stn~tur~ is
a soft but weak high bulk sheet of relatively uncomp~cte~ fibers. Bonding material
is preferably appaed to portions of the web prior to creping.
Compacted non-pattern-densified tissue structures are commonly known in
thc art as conventional tissua structures. In general, compacted, non-pattarn-
25 densified tissue paper structures are prepared by depositing a papermakingfumish on a foraminous wire such as a Fourdlin-er wire to form a wet web, ~l~ainir~the web and removing additional water with ths aid of a uniform machanical
compaction (pressing) until the web has a consistency of 25-50%, transfsrring tha
web to a thermal dryer such as a Yankee and crepin~ the web. Overall, water is
30 removed from the web by vacuum, mechanical pressing and thermal means. Th~
resulting structure is strong and generally o? singular density, but very low in bulk,
absorbency and in so~lness.
The tissue paper web of this invention can be used in any ~a, r l-c~tion whera
soft, absorbent tissue paper webs are required. Particularly advantageous uses of
35 the tissue paper web of this invention are in paper towel, toilet tissue and facial
tissue products. For exampla, two tissue paper webs of this invention can be
embossed and adhesively secured together in face to face relation as taught by
,~WO 94/16143 PCT/US94/00551
~ 19 21~3~
U.S. Pat. No.-3,414,459, which issued to Wells on December 3, 1968 and which is
incorporated herein by reference, to form 2-ply paper lowels.
Molecular Welght Determination
A. Introduction
The essential distinguishing characteristic ot polymeric materials is their
molecular size. The properties which have enabled polym~rs to be used in a
diversity of applications derive almost entirely from their macro-molecular nature.
In order to characterize fully these materials it is essential to have some means of
defining and determining their molecular weights and molecular weight
distributions. It is more correct to use the term relative molecular mass rather the
molecular weight, but the latter is used more generally in polymer technology. It is
not always practical to determine molecular weight distributions. However, this is
becoming more common practice using chromatographic techniques. Rather,
recourse is made to expressing molecular size in terms of molecular weight
averages.
B. Molecular welght averages
If we consider a simple molecular weight distribution which represents the
weigh~ fraction (wj) of mc'Qcules having relative molecular mass (Mj), it is possible
to define several useful average values. Averaging carried out on the basis of the
number of molecules (Nj) of a particular size (Mj) gives the Number Average
Molecular Weight
~n = ~ Ni M
~: Ni
An important consequencs of this definition is that the Number Average
Molecular Weight in grams contains Avogadro's Number of moleaJl~s
This definition of molecular weight is consistent with that of monodisperse
30 molecular species, i.e. molecules havinQ the same mQlecular weight. Of more
significance is the recognition that if the number of molecules in a given mass of a
polydisperse polymer can be determined in some way then l~n, can be c~lcu'~te~
readily. This is the b~sis of colligative property measurements.
Averaging on the basis of the weight fractions (Wj) of molecules of a given
35 mass (Mj) leads to the definition of Weight Average Molecular Weights.
PCT/US94/OOS5
WO 94/16143
2~3~ 20
Mw ~ ~: Wi Ni - ~: Ni Mj2
Wj ~:NjMj
Mw is a more useful means for expressing polymer molecular weights than Mn
5 since it reflects more accurately such properties as melt viscosity and mechanical
properties of polymers and is therefor used in the present invention.
Analyticsl and Testlng Procedures
Analysis of the amount of biodegradable treatment chemicals used herein
or retained on tissue paper webs can be perlormed by any method accepted in the
applicable art.
A. Quantitative analysls for quaternlzed ester-amTne and polyhydroxy
compounds
For example, the level of the quaternized ester-amine compound, such as
diester di(hydrogenated)tallow dimethyl ammonium chloride (DEDHTDMAC) (i.e.,
ADOGEN DDMC R), retained by the tissue paper can be datermined by solvent
extraction of the DEDHTDMAC by an or~anic solvent followed by an
anioniclca~ionic titration using Dimidium Bromide as indicator; ths Isvel of the20 polyhydroxy compound, such 2S PEG-400, can be determined by extraction in an
aqueous solvent such as water followed by gas chromatography or colorimetry
techniques to determine the level of PEG^400 in the extract. These methods are
exemplary, and are not meant to exclude other methods which may be useful for
determining levels of particular components retained by th~ tissue paper.
B. Hydrophlllclty (absorbency)
Hydrophilicity ot tissue paper refers, in ~eneral, to ths propensity of the
tissue paper to be wetted with water. Hydrophilicity of tissue papsr may be
somewhat quantified by determining th~ period ot tim~ required for dry tissue
paper to become completely wetted with water. This period of time is referred to as
3~ ~wetting time~. In order to provide a consistent and repeatabla test for wetting time,
the following procedura may be used for wetting timc detern inations: first, a
conditioned sample unit sheet (the environmental conditions for testin~ of papersamples are 23+1C and 5012% R.H. as specified in TAPPI Mcthod T 402),
approximately 4-3/8 inch x 4-3/4 inch (about 11.1 cm x 12 cm) of tissue paper
structure is provided; second, the sheet is folded into four (4) juxtaposed quarters,
and then crumpled into a ball approximately 0.75 inches (about 1.9 cm) to about 1
inch (about 2.5 cm) in diameter; third, the balled sheet is placed on the surface of
_WO 94/16143 PCTIUS94/00551
21 ~1~3~ ~
a body of disti~led water at 23 + 1C and a timer is simultaneously s~arted; four~h,
the timer is stopped and read when wetting of th~ balled sheet is completed.
Complete we~ting is observed visually.
Hydrophilicity characters of tissue paper embodiments of ~he present
5 invention may, of course, be determined immediately after manufacture. However,
substantial increases in hydrophobicity may occur during tha first two weeks after
the tissue paper is made: i.e., aRer the paper has aged two (2) weeks following its
manufacture. Thus, the wetting times arë preferably measured at the end of such
two week period. Accordingly, wetting times measured at the end of a two week
10 aging period at room temperature are referred to as Utwo week wetting times.
C. Denslty
The density of tissue paper, as that term is used herein, is the average
density calculated as the basis weight of that paper divided by the caliper, with the
appropriate unit conversions incorporated therein. Caliper of the tissue paper, as
15 used herein, is the thickness of the paper when subjected to a compressive load of
95 g/ln2 (15.5 ~/cm2).
Optional In~redlents
Other chemicals commonly used in papermakin~ can be added to the
biodegradabl~ chemical softening composition describad herein, or to the
papermaking furnish so long as they do not significantly and adversely affect the
softening, absorbency of the fibrous material, and enhancing actions of the
chemical softening composition.
For example, surfactants may be used to treat the tissu~ pap~r webs of the
present invention. The level of surfactant, if used, is preferably from about 0.01%
to about 2.0% by weight, based on the dry fiber weight of the tissue paper. The
surfactants preferably have alkyl chains with ei~ht or more carbon atoms.
Exemplary anionic surfactants are linear alkyl sulfonates, and alkylbenzene
sulfonates. Exemplary nonionic surfactants are alkylglycosides includin~
alkylglycoside esters such as Crodesta SL-40 which is available from Croda, Inc.(New York, NY); alkylglycosid~ ethers as described in U.S. Patent 4.011,389,
issued to W. K. Langdon, et al. on March 8, 1977; and alkylpolyethoxylated esters
such as pegosperse 200 ML available from Glyco Chemicals, Inc (Greenwich, CT)
and IGEPAL RC-520 available from Rhone Poulenc Corporation (Cranbury, N.J.).
Other types of chemicals which may be added, include dry strength
additives to increase the tensile strength of the tissue webs. Examples of dry
WO 94/16143 ?,1~33~-5 22 PCTIUS94/005~
strengSh additives inciude carboxymethyl cellulose, and ca~ionic polymers from the
ACCO chemical family such as ACCO 711 and ACCO 514, wi~h ACCO chemical
family being preferred. These materials are available commercially from the
American Cyanamid Company of Wayne, New Jersey. The level of dry strength
5 additive, if used, is preferably from about 0.01% to about 1.0%, by weight, based
on the dry fiber weight of the tissue paper.
Other types of chemicals which may be added, include wet strength
additives to increase the wet burst of the tissue webs. The present invention may
contain as an optional component from about 0.01% to about 3.0%, more
10 preferably from about 0.3% to about 1.5% by weight, on a dry fiber weight basis, of
a water-soluble permanent wet strength resin.
Permanent wet strength resins useful herein can be of several types.
Generally, those resins which have previously found and which will hereafter find
utility in the papermaking art are useful herein. Numerous examples are shown in15 the aforementioned paper by Westfelt, incorporated herein by reference.
In the usual case, the wet strength resins are water-soluble, cationic
materials. That is to say, the resins are water-soluble at th~ time they are added to
the papermaking furnish. It is quite possiblQ~ and even to be expected, that
subsequent events such as cross-linking will render the resins insoluble in water.
20 Further, some resins are soluble only under specific conditions, such as ov~r a
limited pH range.
Wet strength resins are generally believed to undergo a cross-linking or
other curing reactions after they have been deposited on, within, or among the
papermaking fibers. Cross-linking or curing does not normally occur so long as
25 subst~ntial amounts of water are present.
Of particular utility are the various polyamide-epichlorohydrin resins. These
materials are low molecular weight polymers provided with reactivs functional
~roups such as amino, epoxy, and azetidinium groups. The patent literature is
replete with descriptions of processes for makin~ such rnaterials. U.S. Pat. No.30 3,700,623, issued to Keim on October 24, 1972 and U.S. Pat. No. 3,772,076,
issued to Keim on November 13, 1973 are examples of such patents and both are
incorporated herein by reference.
Polyamida-epichlorohyd~in resins sold under the trademarks Kymene 557H
and Kymene 2064 by Hercules Incorporated of Wilmington, Delaware, are
35 particularly useful in this invention. These resins are generally described in the
aforementioned patents to Keim.
WO 94/16143 PCT/US94/00551
2~Z~ 5 3 3 1 ~;
Base-activated polyamide-epichlorohydrin resins useful in lhe present
invention are sold under the Santo Res trademark, such as Santo Res 31, by
Monsanto Company of St. Louis, Missouri. These types of materials are generally
described in U.S. Pat. Nos. 3,855,158 issued to Petrovich on December 17, 1974;
5 3,899,388 issued to Petrovich on August 12, 1975; 4,129,528 issued to Petrovich
on December 12, 1978; 4,147,586 issued to Petrovich on April 3, 1979; and
4,222,921 issued to Van Eenam on September 16, 1980, all incorporated herein
by reference.
Other water-soluble cationic resins usefùl herein are the polyacrylamide
10 resins such as those sold under the Parez trademark, such as Parez 631NC, by
American Cyanamid Company. of Stanford, Connecticut. These materials are
generally described in U.S. Pat. Nos. 3,556,932 issued to Coscia et al . on January
19, 1971; and 3,556,933 issued to Williams et al . on January 19, 1971, all
incorporated herein by reference.
Other types of water-solubls resins useful in the present invention include
acrylic emulsions and anionic styrena-butadiene latexes. Numerous exarnples of
these types of resins are provided in U.S. Patent 3,844,880, Meisel, Jr. et al .,
issued October 29, 1974, incorporated herein by reference.
Still other water-soluble cationic resins finding utility in this invention are the
20 urea formaldehyde and melamina formaldehyde resins. These polyfunctional,
reactive polymers have molecular weights on the order of a few thousand. The
more common functional groups include nitrogen containing groups such as amino
~roups and methylol groups attached to nitrogen.
Although less preferred, polyethylenimine type resins find utility in the
25 present invention.
More complete descriptions of the aforementioned water-soluble resins,
including their manufacture, can be found in TAPPI Monograph Sefies No. 29, Wet
Strength In Paper and Paperboard, Technical Assoc;~tion of the Pulp and Paper
Industry (New York; 1965), incorporated herein by referencQ. As used herein, ths30 term ~permanent wet strength resin~ refers to a resin which allows the paper sheet,
when placed in an aqueous medium, to keep a majority of its initial wet sl~ngt~, for
a period of time greater than at 1east two minutes.
The above-mentioned wet strength additives typically result in paper
products with permanent wet strength, I.e., paper which when placed in an
35 aqueous medium retains a substantial portion of its initial wet strength over time.
However, permanent wet strength in some types of paper products can be an
unnecessary and undesirable property. Paper products such as toilet tissues, etc.,
WO 94/16143 2~ ~33 .24 PCT/US94/0055
are generally disposed of after brief periods of use into septic systems and tho like
Clogging of these systems can result if the paper product permanently retains its
hydrolysis-resistant strength properties.More recently, manufacturers have addedtemporary wet strength additives to paper products for which we~ strength is
sufficient for the intended use, but which then decays upon soaking in water
Decay of the wet strength facilitates flow of the paper product through septic
systems.
Examples of suitable temporary wet-s~renyll)-resins Include modified starch
temporary wet strength agents, such as National Starch 78-0080, marketed by the
National Starch and Chemical Corporation (New York, New York). This type of wet
strength agent can be made by reacting dimethoxyethyl-N-methyl-ch10roacetamide
with cationic starch polymers. Modified starch tempora~ wet strength agents are
also described in U.S. Pat. No. 4,675,394, Solarek, et al ., issued June 23,1987,
and incorporated herein by reference. Preferred temporary wet strength resins
include those described in U.S. Pat. No. 4,981,557, Bjorlcquist, issued January 1,
1991, and incorporated herein by referenc~.
With respect to the cl~sses and specific examples of both permansnt and
temporary wet strength resins listed above, it should be understood that the resins
listed are exemplary in nature and are not meant to limit the scope of this
invention.
Mixtures of compatible wet strength resins can also be used in the practice
of this inYention.
The above listings of optional chemical additives is intended to be merely
exemplary in nature, and are not meant to limit the scope of the invention.
The following examples illustrate the practice of the present invention but
are not intended to be limiting thereof.
EXAMPLE 1
The purpose of this example is to illustrate a method that can be used to
make-up a biodegradable chemical sottener composition comprising a mixture of
Diester Ditallow Dimethyl Ammonium Chloride (DEDTDMAC) and Polyethylene
Glycol 400 (PEG-400).
A 1 % solution of th~ biodegradable chemical softener is prepared according
to the tollowing procedure: 1. An equivalent weight of DEDTDMAC and PEG-
400 is weighed separately; 2. PEG is heated up to about 66 C (150 F); 3.
DEDTDMAC is dissolved in PE(3 to torm a melted solution at 66 C (150 F); 4.
~WO 94/16143 ~ I 5 3 3 I 5 PCT/US94/00551
Shear stressis applied to form a homogeneous mixture of DEDTDMAC in PEG;
5. The pH of the dilution water is adjusted to about 3 by adding a solution of HCI at
0.1% concentra~ion. 6. The dilution wate! is heated up to about 66 C (150 F);
7. The melted mixture of DEDTDMAC and PEG is diluted to a 1% solution; and
5 8. Shear stress is applied to form an aqueous solution containing a vesicle
dispersion or suspension of the DEDTDMAC and PEG mixture; 9. The particle
size of the vesicle dispersion is determined using an optical microscopic
techniquc. The particle size range is from about 0.1 to 1.0 micron.
Figure 6 illustrates a cryo-transmission micro-photograph taken at X
10 63,000 of a vesicle dispersion of a 1: 1 by weight ratio of a DEDTDMAC and PEG-
400 system. From figure 6, it indica2es that particles having membranes one or
two bilayers thick, whose geometry ranges from closed/open vesicles, to disc-like
structures and sheets.
EXAMPLE 2
The purpose of this example is to illustrate a method that can be usad to
make-up a biodegradable chemical softener composition which comprises a
mixture of Diester Ditallow Dimethyl Ammonium Chloride (DEDTDMAC) and
20 Glycerol.
A 1% solution of the biodegradable chemical softener is prepared according
to the following procedure: 1. An equivalent weight of DEDTDMAC and Glyc~rol
is separately weighed; 2. Glycerol is heated up to about 66 C (t50 F~; 3.
DEDTDMAC is dissolved in Glycerol to form a melted solution at 66 C (150 F);
25 4. Shear stress is applied to form a homogeneous mixture of DEDTDMAC in
Glycerol; 5. The pH of the dilution water is adjusted to about 3 by adding a
solution of HCI at 0.1% concentration. 6. The dilution water is heated up to about
66 C (150 F); 7. The melted mixture is diluted to a 1% solution; and 8. Shear
stress is applied to form an aqueous solution containin~ a vesicl~ dispersion or30 suspension of DEDTDMAC and Glycerol mixture; 9. The particle size of the
vesicla dispersion is determined using an optical microscopic technique. Tha
particle size ranga is from about 0.1 to 1.0 micron.
Figure 7 illustrates a cryo-trans,n;ssion micro-photograph taken at X 63,000
of a vesicle dispersion of a 1: 1 by weight ratio of a DEDTDMAC and Glycerol
35 system. From figure 7, it indicates that particles having membranes one or two
bilayers thick, whose geometry ranges from closed vesicles, to disc-like structures.
WO 94/16143 PCT/US94/0055~
~ 3~ ~ 26
EXAMPLE 3
The purpose of this example is to illustrate a method that can be used to
make-up a biodegradable chemical softener composition comprising a mixture of
Diester Di(hydrogenated) Tallow Dimethyl Ammonium Chloride (DEDHTDMAC)
(i.e., ADOGEN DDMC R from Sherex company) and Polyethylene glycol 400
(PEG-400).
A 1% solution of the biodegradable chemical sof~ener is prepared according
to the following procedure: 1. An equivalent weight of DEDHTDMAC and PEG-
400 is separately weighed; 2. PEG is heated up to about 90 C (194 F); 3.
DEDHTDMAC is dissolved in PEG to form a melted solution at 90 C (194 F); 4.
Shear stress is applied to form a homogeneous mixture of DEDHTDMAC in PEG;
5. The pH of the dilution water is adjusted to about 3 by adding a solution of HCI at
0.1% concentration. 6. The dilution water is heated up to about 70 C (158 F);
7. The melted mixture is diluted to a 1% solution; and 8. Shear stress is a,oplied
to form an aqueous solution. containing a vesicls dispersion or suspension of
DEDHTDMAC and PEG mixture; 9. The particle siz~ of DEDHTDMAC and PEG
vesicle dispersion is determined using an optical microscopic techniqus. The
particle size rang~ is from about 0.1 to 1.0 micron.
Figure 8 illustrates a cryo-transmission micro-pho1Ograph taken at X 66,000
of a vesicle dispersion of a 1: 1 by weight ratio ot a DEDHTDMAC and PEG-400
system. From figure 8, it indicates that particles having membranes one or two
bilayers thick, whose geometry ranges from closed vesicles, to disc-like structures.
EXAMPLE 4
The purpose of this example is to illustrate a method using a blow throu~h
dryin~ papermakin~ techniqu~ to mak~ sofl and absorb~nt papar towel she~ts
treated with a biodegradabl~ ch~mical soflener co"~pGsiUon comprisin~ a ntixtur~30 of Diester Ditallow Dimethyl Ammonium Chloride (DEDTDMAC), a Polyethylene
glycol 400 (PEG-400), and a permanent wet strength resin .
A pilot scal3 IFourdrinier papermaking machine is used in the practic~ of the
present invention. First, a 1% solution of the biodegr~d~bl~ chamical softener is
prepared according to the procedure in Example 1. Second, a 3% by weight
35 aqueous slurry of NSK is made up in a conventional re-pulper. The NSK sluny is
refined gently and a 2% solution of a permanent wet strength resin (i.a. Kymene
557H marketed by Hercules incorporated of Wilmlngton, DE) is added to th~ NSK
WO 94/16143 PCT/US94/00551
27 2l~3ii
stock pipe at a rate of 1% by weight of the dry fibers. The adsorption of Kymene557H to NSK is enhanced by an in-line mixer. A 1% solution of Carboxy Methyl
Cellulose (CMC) is added after the in-line mixer at a rate of 0.2% by weight of the
dry fibers to enhance the dry strength ot the fibrous substrate. The adsorption ot
5 CMC to NSK can be enhanced by an in-line mixer. Then, a 1% solution of the
chemical softener mixture (DEDTDMAC/ PEG) is added to the NSK slurry at a rate
of 0.1% by weight of the dry fibers. The adsorption of the chemical softener
mixture to NSK can also enhanced via an in-line mixer. The NSK slurry is dilutedto 0.2% by the fan pump. Third, a 3% by weight aqueous slurry of CTMP is made
10 up in a conventional re-pulper. A non-ionic surfactant (Pegosperse) is added to
the re-pulper at a rate of 0.2% by weight of dry fibers. A 1% solution of the
chemical softener mixture is added to the CTMP stock pipe before the stock pump
at a rate of 0.1% by weight of the dry fibers. The adsorption of the chemical
softener mixture to CTMP can be enhanced by an in-line mixer. The CTMP slurry
15 is diluted to 0.2% by the fan pump. The treated furnish mixture (NSK / CTMP) is
blended in the head box and deposited onto a Foudrinier wire to form an
embryonic web. Dewatering occurs through the Foudrinier wire and is assisted by
a deflector and vacuum boxes. The Fourdrinier wire is of a 5-shed, satin weave
configuration having 84 machine-direction and 76 cross-machin~-direction
20 monofilaments per inch, respectively. The embryonic wet web is transferred from
the Fourdrinier wire, at a fiber consistency of about 22% at the point of transfer,
to a photo-polymer fabric having 240 Linear Idaho cells per square inch, 34
percen~ knuckle areas and 14 mils of photo-polymer depth. Further de-watenng
is accomplished by vacuum assisted drainage until the web has a fiber
25 consistency of about 28%. The pafferned web is pre~ried by air blow-through to a
fiber consistency of about 65% by weight. The web is thcn adhered to the surfaceof a Yankee dryer with a sprayed creping adhesive comprising 0.25% aqueous
solution of Polyvinyl Alcohol (PVA). The fiber consistency is increased to an
estimated 96% befors the dry creping the web with a doctor blade. The doctor
30 blade has a bevel angle of about 25 degrees and is positioned with respect to the
Yankee dryer to provide an impact angle of about 81 degrees; the Yankeo dryer isoperated at about 800 fpm (feet per minute) (about 244 meters per minute). The
dry web is fommed into roll at a speed of 700 fpm ( 214 meters per minutes).
Two plies of the web are formed into paper towel products by embossing
35 and laminating them together using PVA adhesive. The papsr towel has about 26#/3M Sq Ft basis weight, contains about 0.2% of the biodegradable chemical
PCT/US94/00551~
W0 94,l6l43 2l~ 28 ~
softener mixturs and about t.0% of the permanent wet strength resin. The
resulting paper towel is soft, absorbent, and very strong when wetted.
Table 1 below summarizes the retention levels and the average particle size
of the DED~DMAC/PEG-400 vesicle dispersion compared to adding PEG-400 only
to the furnish slurry.
Table 1:
DEDTDMAC / PEG
PEG IO slurry vesicle dispcrsion
R~l~ntion lcvcl of PEG 5 80
in p~duct (%)
Rclention lcvcl of DEDTDMAC NA 85
~n product (%)
Average paniclc sizc (microns) NA 0.4
EXAMPLE 5
The purpose of this example is to illustrate a method using a blow through
dryin~ and layered papermaking techniques to mak~ soft and absorb~nt toil~t
tissue paper treated with a biodegradable chemical softener composition
15 comprisin~ a mixture of Diester Ditallow Dimethyl Ammonium Methyl Chlorid~
(DEDTDMAC) and a Polyethylene glycol 400 (PEG-400) and a temporary wet
strength resin.
A pilot scale Fourdrinier papermaking machin~ is used in the practice of th~
present invention. First, a 1% solution of the b-cdegradable chemical softener is
20 prepared according to the procedure in Exampls 1. Second, a 3% by weight
aqueous slurry of NSK is made up in a conventional re-pulp~r. The NSK slurry is
refined ~ently and a 2% solution of the temporary wet slren~ resin (i.~. National
starch 78-0080 marketed by National Starch and Chemical corporation of New-
York, NY) is added to th~ NSK stock pipe at a rate of 0.75% by weight of the dry25 fibers. Th~ adsorption of the temporary wet stren~th resin onto NSK fibers isenhanced by an in-line mixer. The NSK slurry is diluted to about 0.2% consistency
at the fan pump. Third, a 3% by weight aqueous slurry of Eucalyptus fibers is
made up in a conventional re-pulper. A 1% solution of the chemical softener
mixture is added to the Eucalyptus stock pipe befors the stock pump at a rate of30 0.2% by weight of the dry fibers. The adsorption of the biodegradable chemical
~VO 94/16143 29 215 3 31 5 PCT/US94/00551
softener mixture to Eucalyptus fibers can be enhanced by an in-line mixer. The
Eucalyptus slurry is diluted to about 0.2% consistency at the fan pump.
The treated furnish mixture (30% of NSK / 70% of Eucalyptus) is blended in
th~ head box and deposited onto a Foudrinier wire to form an embryonic web.
5 Dewatering occurs through the Foudrinier wire and is assisted by a deflector and
vacuum boxes. The Fourdrinier wire is of a 5-shed, satin weave configuration
having 84 machine-direction and 76 cross-machine-direction rnonofilaments per
inch, respectively. The embryonic wet web is transferred from the photo-polymer
wire, at a fiber consistency of about 15% at the point of transfer, to a photo-
10 polymer fabric having 562 Linear Idaho cells per square inch, 40 percent knucklearea and 9 mils of photo-polymer depth. Further de-watering is accomplished by
vacuum assisted drainage until the web has a fiber consistency of about 28%.
The patterned web is pre-dried by air blow-through to a fiber consistency of about
65% by weight. The web is then adhered to the sur~ace of a Yankee dryer with a
15 sprayed creping adhesive comprising 0.25% aqueous solution of Polyvinyl Alcohol
(PVA). The fiber consistency is increased to an estimated 96% befor~ the dry
creping the web with a doctor blade. The doctor blade has a bevel angle of about25 degrees and is positioned with respect to the Yankee dryer to provide an
impact angle of about 81 degrees; the Yankee dryer is operated at about 800 fpm
20 (feet per minute) (about 244 meters per minute). The dry web is formed into roll at
a speed of 700 fpm (214 meters per minutes).
The web is converted into a one ply tissue paper product. The tissue paper
has about 18 #13M Sq Ft basis weight, contains about 0.1% of the biodsgradable
chemical softener mixture and about 0.2% of the temporary wet strength resin.
25 Importantly, the resulting tissue paper is soft, absorbent and is suitable for use as
facial and/or toilet tissues.
Tabls 2 below summarizes the retention levels and the average par~icle size
of the DEDTDMAC / PEG vesicle dispersion compared to adding PEG-400 only 10
the furnish slurry.
PCTIUS94/0055
WO 9~/161~3
Table 2 :
DEDTDMAC /PEG
PEG ~o slurr~Vcsiclc dispcrsion
Rc~enlion levcl of PEG 5 75
in producl (%)
~elention levcl of DEDTDMACNA 85
in p~dua (%)
Avcragc paniclc sizc (microns) NA 0.4
EXAMPLE 6
The purpose of ~his example is to illustrate a method using a blow throu~h
drying papermaking techniqu~ to make soft and absorbent toilet tissue papsr
10 treated with a biodegradable chemical softener composition comprisin~ a mixture
of Diester Ditallow Dim~thyl Ammonium Chloride (DEDTDMAC), a Polyethylans
glycol 400 (PEG-400) and a dry strength additiv~ resin.
A pilot scale Fourdrinier papermaking machine is used in the practics of the
present invention. hrst, a 1% solution of the biodegradable chemical soflaner is15 prepared according to the procedure in Example 1. Second, a 3% by weight
aqueous slurry of NSK is mad~ up in a conventional re pulper. The NSK slurry is
refined gently and a 2% solution of the dry strength resin (i.e. Acco 514, Acco 711
marketed by American Cyanamid company of Fairfield, OH) is added to the NSK
stock pipe at a rate ot 0.2% by weight of the dry fibers. Th~ adsorption of the d~y
20 strength resin onto NSK fibers is enhanced by an in-line mixer. The NSK slurry is
diluted to about 0.2% consist~ncy at the ~n pump. Third, a 3% by wei~ht
aqueous slurry of Eucalyptus fibers is madc up in a conventional re-pulper. A 1%solution of the chemical soflener mixture is added to ths Eucalyptus stock pipe
before the stock pump at a rate of 0.2% by weight of the dry fibers. The
25 adsorption of the biod~r~dable chemical softener mix~uro to Eucalyptus fibers can
ba enhanced by an in-line mixer. The Eucalyptus slurry is diluted to about 0.2%
consistency at the fan pump.
The treated furnish mixture (30% of NSK / 70% of Eucalyptus) is blend~d in
the head box and deposited onto a Foudrinier wire to form an embryonic wQb.
30 Dewatering occurs through the Foudrinier wire and is assisted by a deflector and
~WO 94/16143 21 5 3 3 15 PCT/US94/00551
31
vacuum boxes. The Fourdrinisr wir~ is of a 5-shed, satin weave configuration
having 84 machine-direction and 76 cross-machine-direction monofilaments per
inch, respectively. The embryonic wet web is transferred from the photo-polymer
wire, at a fiber consistency of about 15% at the point of transfer, to a photo-
5 polymer fabric having 562 Linear Idaho cells per square inch, 40 percent knucklearea and 9 mils of photo-polymer depth. Funher de-watering is accomplished by
vacuum assisted drainag~ until the web has a fiber consistency of about 28%.
The patterned web is pre-dried by air blow-through to a fiber consistency of about
65% by weight. The web is then adhered to the surface ot a Yankee dryer with a
10 sprayed creping adhesive comprising 0.25% aqueous solution of Polyvinyl Alcohol
(PVA). The fiber consistency is increased to an estimated 96% before the dry
creping the web with a doctor blade. The doctor blade has a bevel angle of about25 degrees and is positioned with respect to the Yanke~ dryer to provide an
impact angle of about 81 degrees; the Yankee dryer is operated at about 800 fpm
15 (feet per minute) (about 244 meters per minute). The dry web is formed into roll at
a speed of 700 fpm ( 214 meters per minutes).
Two plies of the web are formed into tissue paper products and laminating
them toge~her using ply bonded techniqu~. The tissue paper has about 23 #/3M
Sq Ft basis weight, contains about 0.1% of the biodegradable ch~mical softener
20 mixture and about 0.1% of the dry strength resin. I".p~ ntly, ths resulting tissue
paper is soft, absorbent and is suitabl~ for use as fadal and/or toilet tissues.Table 3 below summarizes the ret~ntion levels and the average particle size
of the DEDTDMAC / PEG-400 vesicle dispersion compared to adding PEG-400
only to the furnish slurry.
Tablo 3:
DEDTDM~C / PEG
PEG to slurr~ Vcsiclc
RCtcntion lcvcl of PEG
in product (%) 5 75
RCt~ntio~ Icvcl of DEDTDMACNA 80
Averagc paniclc sizc tmicrons) NA 0.4
WO 9~/16143 PCT/US94/005511~
~33~5 EXAMPLE 7
The purpose of this example is to illustrate a me~hod using a conventional
drying papermaking technique to make soft and absorbent toilet tissue paper
5 treated with a biodegradable chemical soflener composition comprising a mixture
of Diester Di(hydrogenated) Tallow Dimethyl Ammonium Chloride (DEDHTDMAC),
a Polyethylene giycol 400 (PEG-400) and a dry strength additive resin .
A pilot scale Fourdrinier papermaking machine is used in the practice of the
present invention. First, a 1% solution of the biodegradabls chemical softener is
10 prepared according to the procedure in example 3. Second, a 3% by weight
aqueous slurry of NSK is made. up in a conventional re-pulper. The NSK slurry isrefined gently and a 2% solution of the dry strength resin (i.e. Acco 514, Acco 711
marketed by American Cyanamid company of Wayne, New Jersey) is added to the
NSK stock pipe at a rate of 0.2% by weight of the dry fibers. The adsorption of the
15 dry strength resin onto NSK fibers is enhanced by an in-line mixer. The NSK
slurry is diluted to about 0.2% consistency at the fan pump. Third, a 3% by
weight aqueous sluny of Eucalyptus tibers is made up in a conventional re-pulper.
A 1% solution of the chemical softener mixture is added to the Eucalyptus stock
pipe before the stock pump at a rate of 0.2% by w~ight of the dry fibers. The
20 adsorption of the chemical softener mixture to Eucalyptus fibers can be enhanced
by an in-line mixer. Ths Eucalyptus slurry is diluted to about 0.2% consistency at
the fan pump.
The treated fumish mixture (30% of NSK / 70% of Eucalyptus) is blended in
the head box and deposited onto a Foudrinier wire to form an embryonic web.
25 Dewatering oc~urs through the Foudrinier wire and is assisted by a deflector and
vacuum boxes. The Foudrinier wire is of a 5-shed, satin weave configuration
having 84 machine-direction and 76 cross-machine-direction monofilaments per
inch, respectively. llle embryonic wet web is transferred from the Foudrinier wire,
at a fiber consis~ency of about 15% at the point of transfer, to a conventional f~lt.
30 F~rther de-waterin~ is accomplished by vacuum assisted drainage until the webhas a fiber consistency of about 35%. The web is then adhered to the surface of
a Yankee dryer. The fiber consistency is increased to an estimated 96% befor~
the dry crepin~ the web with a doctor blade. ThQ doctor blad~ has a bevel an~le of
about 25 degrees and is positioned with respect to the Yankee dryer to provide an
35 impact angle of about 81 degrees; the Yankee d~er is operated at about 800 fpm
(feet per minute) (about 244 meters per minute). The dr~r web is formed into roll at
a speed of 700 fpm (214 meters per minutes).
WO 94/16143 3~ 3 3 ~ ~ PCT/US94/00551
Two plies of the web are ~ormed into tissu~ paper products and laminatin~
~hem together using ply bonded technique. The tissue paper has about 23 #/3M
Sq Ft basis weight, contains about 0.1% of the biodegradabl~ chemical softener
mixture and about 0.1% ot the dry strength resin. Importantly, the resulting tissue
S paper is soft, absorbent and is suitable for use as a facial and/or toilet tissues.
Table 4 below summarizes the retention levels and the average parlicle size
of the DEDHTDMAC and PEG-400 vesicle dispersion compared to adding PEG-
400 only to the fumish slurry.
Table 4:
DEDHTDM~C/ PEG
PEG to sluny Vcsicle Ji"~
nlion Icvcl of PEG
il~ product (%) 70
Rclrnlion Icvcl of DEDHTDM~C
in p~duct (9O) NA 75
Averagc particlc sizc (microns)NA 0.5
1s
