Note: Descriptions are shown in the official language in which they were submitted.
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_MPROVED DRYER SHEET FABRIC CONDITIONER CONTAINING FLUORESCENT
WHITENING AGENT AND A METHOD FOR ITS PREPARATION
BACKGROUND OF THE INVENTION
The instant invention relates generally to application
of adjuvants to fabrics in tumbler-type automatic dryers. More
part_cularly to articles, methods of preparation and n,ethods of
use for applying these adjuvants.
It has been customary for many years to include various
adjuvants in detergents and rinse or wash-cycle additives.
;~ 10 Fabric softeners and fluorescent whitening agents (FWA) which
also have been called optical brighteners or fluorescent dyes are
i
among the most common adjuvants used.
~`~ In the wash or rinse cycles, the primary objective is to
remove soil, etc. from the cloth being washed by means of
detergents, water and emulsifying agents. The presence of deter-
gents and emulsifying agents effective to remove soil from the
cloth manifestly renders difficult and less efficient the concur-
rent application of fabric softeners or other adjuvants to the
same piece of material. Since the conditions characteristic of
~0 the rinsing and washing cycles, leading to inefficient applica-
tion of the fabric adjuvants are not present in the drying cycle,
there is the potentlal for the much more efficient utilization
and application of such adjuvants.
-- 1--
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U.S. Patent 4,238,531 and several other .issued patents /-
based on and related to this patent disclose application of FWA
and softeners, as well as many other adjuvants to fabrics in the
- dryer by use of a flexible substrate carrying the adjuvant. Some
commercial dryer softener sheets also employ low amounts of
FWA's, for example, 7-diethylamino-4-methylcoumarin (Aclarat
8678, a trademark for a product ox Sandoz Chemical) at a level of
about 0.1%.
Due to the heat, mechanical action, and residual water
on the fabrics in the dryer, it might be expected that fabric
adjuvants could be easily and uniformly applied in the dryer.
Experience demonstrates, however, that this does not readily
occur and in the case of FWA's, it is particularly difficult.
Many patents over the last twenty or so years have dealt with
;~ 15 varlous aspects of treating fabrics in the dryer or in both the
washer and dryer, and these will be well known to the artisan.
;~ Fairly extensive listings of patents dealing with compositions,
substrates and with methods of treating fabrics may be found in
: U.S. Patents 3,442,692; 3,895,128; 4,022,938; 4,085,052;
4,113,630, 4,177,151 and 4,199,465. Patents dealing with FWA's
or optical brighteners and optical brighteners with fabrics are
numerous. Several~of these are U.S. 2,784,183 on monotriazoles
and U.S. 2,612,501 concerned with triazines; U.S. 3,904,533 and
4,460,485 on liquid fabric conditioning agents incorporating
--2--
.
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brighteners and European Patent Application 0 006 271 dealing
with washing and softening compositions containing a nonionic
brightener. None of the art, however, has provided completely
satisfactory whitening.
In its widest aspect, the invention provides a fabric
conditioning composition containing an effective amount of a
distyrylbiphenyl type of FWA in combination with a selected fab-
ric softener or mixture of fabric softener and distributing
agent. In some instances, selected carboxylic acids which have
softening properties may be employed. The inventive process pro-
vides a mixed solvent system balancing water and compatible
hydroxylic solvents, such as glycols or glycerine, particularly
glycerine, capable of substantially dissolving the optical
brightener and solubilizing it to mix with the other components
of the composition to facilitate coating of the substrate and
distribution of the actives.
; The fabric conditioning composition according to the
present invention includes compounds generally classified as fab-
ric softeners that are employed during the drying cycle of the
home iaundering operation. Such fabric softeners are inorganic
clays or water-soiuble or water-dispersible organic, waxy materi-
als having a preferred melting (or softening) point between about
25C and 150C. Softener materials of this type may also be fab-
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C 6068 O
ric substantive in the sense that they are readily deposited onto
the surfaces of fabrics treated therewith Many fabric softeners
of this type also impart some degree of static control Jo k
fabrics being treated therewith.
The fabric softeners can be used singly or, in admixture
with one or more compatible fabric softeners. They can be
selected from the following broadly denoted classes of compounds
which contain at least one long chain group:
(1) cationic quaternary ammonium salts including
quaternary imidazolinium salts;
(2) nonionic compounds, such as sorbitan esters, terti-
ary amine oxides and ethyoxylated alcohols and
I; alkylphenols;
(3) anionic soaps, sulfates and sulfonates, e.g. fatty
acid soaps, ethoxylated alcohol sulfates and sodium
alkyl sulfates, alkyl sulfonates, sodium
alkylbenzene sulfonates, and sodium or potassium
alkylglycerylethersulfonates;
:
(4) zwitterlonic quaternary ammonium `compounds;
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(5) ampholytic tertiary ammonium compounds;
(6) smectite type inorganic clays and
(7~ selected fatty acids.
These softeners are more definitively described in U.S. Patent
4,134,838 incorporated herein by reference. Distributing agents ,-
such as those disclosed in U.S. 4,238,531 and 4,327,133 herein
: incorporated by reference may also be used, for example, polyeth-
ylene glycol monostearate or long chain carboxylic acids such as
commercial stearic acid and the like. The amount of distributing
l.0 agent should be at least 5% of the composition and should be suf-
ficient to substantially distribute the composition in use.
)2Z~9
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Fluorescent Whitening Agent
In addition to the fabric conditioning materials and
distributing agents, a fluorescent whitening agent is required.
The FWA of the invention is the distyrylbiphenyl compound of
Formula I. Formula I is an ionic formula but it will be realized
that the FWA is available as the sodium salt. Formula I is as
follows:
FORI~:ULA I
CH=CH CH=CH ~3
SO3
; 503
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The optical brightener must be present in an amount of at least
1% by weight of the formulation as coated on the substrate and
not more than about 5%, preferably at least 1.3%. This type of
brightener, together with a softener on a foam dryer substrate,
is disclosed in Example 1 of U.S. Patent 4,526,694. The
brightener is also disclosed in an article by 0. I. Neiditch in
the Journal of the A:nerican Oil Chemists Society, Vol. 58, No. 2,
February 1981, pages 162 to 165A and in British Patent 2,028,365.
Preparation and Use of Impregnated
Substrate Fabric Conditioning Articles
The fabric conditioning compositions are provided as an
article of manufacture in combination with a dispensing means
which effectively releases the softening compositions in a tumble
dryer. Such dispensing means can be designed for single usage or
for multiple uses.
One such article comprises a sponge material releasably
enclosing enough of the conditioning composition to effectively
impart fabric softness and brightness during several drying
cycles. This multi-use article can be made by filling a hollow
sponge with the composition. In use, the composition melts and
I; leaches out through the pores of the sponge to soften and
brighten fabrics. Such a filled sponge can be used to treat sev-
f~OZ2~L~
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eral loads of fabrics .in conventional dryers, and has the advan-
tage that it can remain in the dryer after use and is not likely
to be misplaced or lost.
Another article comprises a cloth or paper bag
releasably enclosing the composition and sealed with a hardened
plug of the mixture. The action and heat of the dryer opens the
bag and releases the composition to perform its softening and
delivery of deodorant perfume function.
A highly preferred article comprises the compositions
containing the softener and whitener releasably affixed to a
sheet of paper or woven or nonwoven cloth substrate. When such
an article is placed in an automatic laundry dryer, the heat,
moisture, distribution forces and tumbling action of the dryer
removes the composition from the substrate and deposits it on the
fabrics.
The sheet conformation has several advantages. For
example, effective amounts of the compositions for use in conven-
tional dryers can be easily sorbed onto and into the sheet
substrate by a simple dipping or padding process. Thus, the user
need not measure the amount of the composition necessary to
obtain fabric brightness. Additionaily, the flat configuration
of the sheet provides a large surface area which results in effi-
cient release of the materials onto fabrics by the tumbling
action of the dryer.
2CP~22~9
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The water-insoluble paper, or woven or non-wo~en
substrates used in the articles can have a dense, or more
preferably, open or porous structure. Examples of suitably at
rials which can be used as substrates herein include paper, woven
cloth, and non-woven cloth. The term "cloth" herein means a
woven or non-woven substrate for the articles of manufacture, as
distinguished from the term "fabric" which encompasses the
clothing fabrics being dried in an automatic dryer.
; It is known that most substances are able to absorb a
liquid substance to some degree; however, the term "absorbent",
as used herein, is intended to mean a non-woven textile substrate
with an absorbent capacity (i.e., a parameter representing a
substrate's ability to take up and retain a liquid) from 4 to 12,
preferably 5 to 7, times its weight of water.
If the substrate is a foamed plastics material, the
absorbent capacity is preferably in the range of 15 to 22, but
some special foams, for example reticulated foams, can have an
absorbent capacity in the range from 4 to 12.
Determination of absorbent capacity values is made by
using the capacity testing procedures described in U.S. Federal
Specifications (UU-T-595b), modified as follows:
1. tap water is used instead of distilled water;
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2. the specimen is immersed for 30 seconds instead of 3
minutes;
3. draining time is 15 seconds instead of 1 minute; and
4. the specimen is immediately weighed on a torsion
balance having a pan with turned-up edges.
Absorbent capacity values are than calculated in
; accordance with the formula given in said
Specification. Based on this test, one-ply, dense
bleached paper (e.g., Kraft or bond having a basls
weight of about 32 pounds per 3,000 square feet) has
; an absorbent capacity of 3.5 to 4; commercially
available house-hold one-ply toweling paper has a
value of 5 to 6; and commercially available two-ply
household toweling paper has a value of 7 to about
l 9.5.
Suitable materials which can be used as a substrate in
the invention~herein include, among others, sponges, paper, and
woven and non-woven cloth, all having the necessary absorbency
requirements defined above.
The preferred non-woven cloth substrates can generally
be defined as adhesively bonded fibrous or filamentous products
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having a web or carded fiber structure (where the iber strength
is suitable to allow carding), or comprising fibrous mats in
which the fibers or filaments are distributed haphazardly or in
random array (i.e. an array of fibers in a carded web wherein
partial orientation of the fibers is frequently present, as well
as a completely haphazard distributional orientation), or sub-
stantially aligned. The fibers or filaments can be natural (e.g.
wool, silk, jute, hemp, cotton, linen, sisal, o:^ ramie) or syn-
thetic (e.g. rayon, cellulose ester, polyvinyl derivatives,
polyolefins, polyamides, or polyesters).
The preferred absorbent properties are particularly easy
to obtain with non-woven cloths and are provided merely by build-
ing up the thickness of the cloth, i e., by superimposing a plu-
rality of carded webs or mats to a thickness adequate to obtain
the necessary absorbent properties, or by allowing a sufficient
thickness of the fibers to deposit on the screen. Any diameter
or denier of the fiber (generally up to about 10 denier) can be
used, inasmuch as it is the free space between each fiber that
makes the thickness of t-he cloth directly related to the absorb-
ent capacity of the cloth, and which, further, makes the non-
woven cloth especially suitable for impregnation with a
composition by means of intersectional or capillary action.
Thus, any thickness necessary to obtain the required absorbent
capacity can be used.
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When the substrate for the composition is a non-woven
cloth made from fibers deposited haphazardly or in random array
on the screen, the articles exhibit excellent strength in all
directions and are not prone to tear or separate when used in the
automatic clothes dryer.
Preferably, the non-woven cloth is water-laid or air-
laid and is made from cellulosic fibers, particularly from regen-
erated cellulose or rayon. Such non-woven cloth can be
lubricated with any standard textile lubricant. Preferably, the
fibers are from 5mm to 50mm in length and are from 1.5 to 5
denier. Preferably, the fibers are at least partially oriented
haphazardly, and are adhesively bonded together with a hydropho-
bic or substantially hydrophobic binder-resin, particularly with
a nonLonic self-crosslinking acrylic polymer or polymers.
Preferably, the cloth comprises about 70% fiber and 30% binder-
resin polymer by weight and has a basis weight of from about 18
to 45g per square meter.
In applying the composition to the absorbent substrate,
the amount impregnated into and/or coated onto the absorbent sub-
strate is conveniently in the weight ratio range of from about
.
10:1 to 0.5:1 based on the ratio of total softening compositionto dry, untreated substrate (fiber plus binder). Preferably, the
amount of the softening composition ranges from about 5:1 to
::
200Z21 9
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about l:l, most preferably from about 3:1 to 1:1, by weight of
the dry, untreated substrate.
Following application of the liquified composition, the
articles are held at room temperature until the composition
substantially solidifies. The resulting dry articles, prepared
at the composition substrate ratios set forth above, remain
flexible; the sheet articles are suitable for packaging in rolls.
The sheet articles can optionally be slitted or punched to pro-
vide a non-blocking aspect at any convenient time if desired dur-
ing the manufacturing process.
'
::
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The composition of the invention is preferably as
follows.
Softener Base
About 70% dimethyl, ditallow ammonium methyl sulfate.
About 30% Polyethylene glycol 200 monostearate (having a
molec-:lar weight of about 460).
Fluorescent whitening agent
:
The sodium salt of the distyryl biphenyl compound of
FORMULA I.
I:
Fatty carboxylic acids may be substituted for the poly-
ethylene glycol monostearate. Examples of these carboxylic acids
are commercial grades of stearic acid and the like which may con-
tain small amounts of other acids.
The solvent system of preference is glycerine/water and
preferably the optlcal brightener is disso,lved in the
glycerine/water to form a premix prior to addition to the sof-
tener base. The premix may also be propylene glycol or include
propylene glycol but this is not preferred. The ratio of
glycerine to water is about 4:1 but may vary between about two
parts glycerine to 1 part water to six parts glycerine to 1 part
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water. The total amount of the solvent system is not critical
and usually is about four -to five percent of the composition, but
it may be less or more depending on solubility and final coatlng
requirements.
After addition of the premix to the softener base, the
mixture is coated on a substrate in known manner.
The composition of the invention is preferably prepared
as follows:
; The glycerin/water mixture is heated to about 180F to
200F and then the FWA is added slowly while stirring. In the
case of the FWA of Formula I, the color of the premix solution is
a bright yellow/green. The premix is added slowly to the sof-
tener base (which is preheated to 170-180F). Once the premix is
added and dissolved, perfume is added and mixed for several
minutes.
Once the coating composition is prepared, the substrate
is then coated by dipping or padding in known manner.
~ZZ~9
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The following Examples will more fully illustrate the
embodiments of this invention. All parts, percentages and pro-
portions referred to herein and in the appended claims are by
weight unless otherwise indicated.
Example I
This example is an initial comparison of various fluo-
rescent whitening agents added both with and without
solubilization. The agent of the invention is shown above in
Formula I.
Experimental
The fluorescent whitening agents (FWA) evaluated are listed in
Table 1 along with their chemical type.
:
Table 1
Types of Fluorescent Whitening Agents
"F" Dye Chemical Type
I Distyrylbiphenyl
II 7 Diethylamino 4-methyl coumarin
III Oxazole
IV Morpholino disulfonated stilbene triazole
V Phenyl stilbene triazole
VI Methyl ethanolamine stilbene triazine
disulfonate
VII Diethanolamlne disulfonated stilbene triazine
-16-
2~Z2~9
c 6068 ca
FORMULA 1 1
CH 3
0
C2 H 5
7- diethylamino - 4 -methyl coumarin
;~:
- 1 7 -
22~9
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FORl'lULA I I I
1,2-BI S (5-METHYLBENZoXAYoL -2-YL) ETHYLENE
--] 8--
2;~9
c 6068 ca
FORMULA I V
NH NH
N NH CH=CH ~3 I`IH
SO 3 SO N--\
I?
: -19-
.
22~19
c 6068 ca
FORMULA V
N I) CH = Of N
SO 3 SO 6
I;
,
: : -20-
:
:
2~ZZ~
c 6068 ca
FORMULA V I
^
NH NH
No CH=CH I'IH
N--CH3 SO 3 SO 3 N~--CH3
C~12C1120H CH2C~ O~C
; '
-21-
Z2~L9
C 6068 Ca
FORMULA VII
'
NH NH
N \~ HN CH = CH NH I/ N
>=N _ --
No CH2CH2OH SO3 SO3 N--CH2C11
CH 2 C H 2 OH CH ;I CH2 OHI
I:
,
: -22-
:
~12~L9
C 6068 Ca
Each fluorescent whitening agent was dissolved in the
softener base at a level of 1.3% for the initial evaluation.
Several FWAs were difficult to dissolve, especially the agents of
Formulas I, IV and VI. The FWA of Formula II was easy to dis-
solve even at the relatively high level of 1.3%.
The sheets were coated as follows:
A pre-weighed amount of a combination of 70% dimethyl
ditallow ammonium methyl sulfate and 30% polyethylene glycol 200
monostearate was heated to about 160F and slowly mixed. The FWA
and the perfume were then added and stirred for varying amounts
of time up to two hours for Formula I. The mixture was then
transferred to a coater pan and the substrate sheets coated and
dried. The coated sheets were then evaluated in the dryer.
Several fabric types were used for the evaluation - cotton, cot-
ton terry, nylon, Dacron and Orlon. These fabrics were prewashedwith an FWA free detergent and a 3 pound ballast load and then
dried in combination with the dryer sheets on the cotton/sturdy
cycle for 30 minutes. Three pieces of each fabric were removed
.
after the first dryer cycle. The remainder were re-washed and
again treated with the dryer sheet a total of 4 times.
After the fabrics were washed, they were evaluated both
visually and instrumentally for whitening potential.
Instrumental "F" values were compiled for each fabric after 1 and
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4 washes. The higher the "F" value, the greater the whitening
potential. The results of initial screening of the FWA's are
listed in Table 2.
-24-
~;iiZ2~9
C 6068 Ca
o o us
t-- o d' d'
o x
In ED ED
Q X
o a
K
a Z Ian o r
:~
O o
I: X
a) o a
Q . I: I
X . . . . .
~0
O
I: o ~o~ o o
l
3 I .~ dt Ln
_ V X
I : S-l H1--1 ::> H l
O l >
I:
~Q s e
' I: I Z t`
-25-
:
~22~9
C 6068 Ca
Based on the above preliminary screening, 1.3% of
Formula I appeared to be the best choice; the sheets jade with
Formula IV and Formula VI were not white when coated and the
presence of the FWA produced a yellow sheet. Fqrmulas VII and V
gave slightly lower results on 100% cotton. Formula III was poor
on cotton; its only advantage was a slight effect ox Dacron after
four (4) washes. Formula II was inf-rior to Formula I on all
fabrics.
The next evaluation was to determine if the use of 1.3%
of Formula I in a dryer sheet could be seen under realistic con-
ditions of consumer usage. The same kind of fabrics were washed
in the same manner as above but with a different commercial
detergent and bleach and subsequently treated with either no
sheet or a dryer sheet with 1.3% of Formula I. The instrumental
results, which were also visually apparent, are listed in Table 3
below
,
-26-
~02`2~L9
C 6068 Ca
X ¦ . .
o x
Jo
I
d~l
I
x
I
X ¦, -
S~~ dl
z l
l '
l
: u,
: 3 X
I)
xl o o
I:
:
I:: O
. o
C ) l
-27-
;
C 6068 Ca
Lower levels of the dye of Formula I were also
evaluated. It was found that there was a small difference in "F"
values between 1.3% Formula I and 0.75% Formula X. When both
levels were evaluated vs. a commercial detergent wash with
bleach, it was found that a level of 1.3% Formula I was needed to
give a visual difference. These results are reported in Table 4.
:;
I'
I: :
:
-2~-
~r\22~L9
C 6068 Ca
ED
~0 OX
o xl
a
E~H d
o O d' Ll~
So So
En I us
5~ o a X¦ Ln Ln Jo
: Jo
d'
Us Us
q h I> ¦d~
:~ h l I (`1 I d'
xl 0 o
- 3 O I d' r-l
I: _ V xl O O N
: H
. :~
h
O
O
O
:~ V O
:
-29-
I:
Z21~
C 6068 Ca
There was a slight difference between the control and
0.75% Formula I instrumentally, although visually the di~fer~
was hard to see. Formula I at l.3% showed an improvement ov2r
the control.
It was desirable to improve the solubility of Formula I
in the softener base. It was found that the compound of Formula
I could be rendered more soluble by preparing a premix in propyl-
ene glycol and then adding it to the melted active. In this way
- FWA addition times in the laboratory were reduced from about 2
hrs. to less than five minutes via the inclusion of 4% propylene
glycol (basis active). Table 5 gives results of the evaluation
of 0.75% Formula I with and without propylene glycol. These lev-
e1s =re also compared to 1.3% Formula I.
I: .
-30-
206:)22~9 c 6068 Ca
I I`
a
o
X
I:
I o a
so u, x
a
us
a) I o f
rl X
:` t` ED
o
' Z I o ED O
: 3
; ~~
= I)
O ` o
:;~, + O
V
h 0
O o_
o lY
O o
--31--
02 Zl9 C 6068 Ca
Although the propylene glycol solvent greatly aids solubility, it
was still desirable to achieve solubility with a less volatile
solvent.
:
'
;::
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- ~0~2Zl9 C 6068 Ca
Example II
A second series of experiments were run to attempt to
improve the solubility of the fluorescent whitening agent of
Formula I. Three separate formulations were prepared utilizing
three separate procedures as follows:
1 2 _ 3
Softener base 95.7 91.7 90.72
[dimethyl ditallow
ammonium methyl
sulfate 70%
Polyethylene Glycol
200 monostearate 30%]
-- Premix
Optical Brightener 1.3 1.3 1.3
of Formula I
: Glycerine -- 4.0 4.0
Deionized Water -- -- 0.98
Perfume 3.0 3.0 3.0
100.O 100.O 100.O
.
2~9 C 6068 Ca
Process parameters for the coating formulations were as follows:
Formulation # 1 2 3
Softener Base
Temperature, F
Heating 220
Cooling 175 -- --
Time,hours 8 -- --
Premix Temperature, F -- 215-250 190
Final Coating Batch175 175 180
Temperature, F
Viscosity, cps
Softener base 105 110 105
Softener base with100 90 80
Formula I (no perfume)
Final 85 70 55
The first test batch (Formulation 1) contained about
1800 pounds and required approximately 8 hours for heating, addi-
tion of the fluorescent whitening agent and cooling down to below
180F for perfume addition. The coating formulation contained
very fine particles of optical brightener and was translucent
after 2 hours of mixing at 220F. After then cooling the batch
to 175F, it was noted that discoloration and odor degradation of
:~,
the softener base had occurred.
The glycerine/FWA premix solution presented several dif-
ficulties during processing of the Formulation 2 test batch.
Initially the glycerine was heated to 210F and the fluorescent
dye was slowly added, however, after addition of approximately
50% of the required weight of FWA, the premix became a thick,
;`
; -34-
Z ~Z Z 9 C 6068 Ca
lumpy viscous mass. The temperature of the glycerine was
increased from 210F to 245-250F and addition of the FW~ way
resumed. Moderate-to-heavy smoking from glycerine vaporization
was noted at the elevated temperatures. The final premix was a
thick, lumpy, viscous slurry that will cause slurry transfer and
handling problems.
The third test batch, Formulation 3, was the best of the
three proposed methods for dispersion and dissolution of the flu-
; orescent whitening agent. A small amount of deionized water
(0.98% of the final formula) was added to the glycerine during
the heating step. The mixture was heated to 190F and the FWA
; was slowly added. The final premix was a low viscosity,
transparent, green fluorescent premix solution that was easily
pourable into the softener base. Viscosity values of the sof-
tener base, the softener base with dye, and the final coating
solution containing perfume were measured for each of the 3 test
batches. These vàlues were best for Formulation #3.
Each of the formulations were used to coat substrate
sheets. A small guantity of these coated dryer sheets were then
I; 20 evaluated as follows:
: .
A set of coated dryer sheets from each test batch were
selected and tested in the same manner as in Example I. The
sheets contained similar coating weights to eliminate any bias
-35-
219 C 6068 Ca
from active and fluorescent dye concentrations on whitening
properties.
Several different types of test cloths, as listed, were
selected and six samples of each were washed with a commercial
detergent powder containing a fluorescent whitening agent
together with a three-pound ballast load. The wash was bleached
and then dried with one of the test dryer sheets. Three of each
of the test cloths were then evaluated (lx). The remaining three
test cloths and ballast load were then washed, bleached and dried
: 10 with a fresh test dryer sheet three more times and again evalu-
ated (4x). The results were as follows:
:
-
.
-36-
Z~2219 C 6068 Ca
I o
O X
_~ I o
o x I
I
C v O Xl
on o I d1 o co
a) X
En O
I
X
O Q)
v Z; K
,4
Q) X o Jo o
O ~~ K
IQ O
Q) O
~0 I ED O
Xl
_
f
,
so
rl
.,,
v
a o a) o o o
o . .
Ed Us
o
h So
En
O O O O
37--
~i[)2~19
C 6068 O
This evaluation shows the improvement in brightening
over commercial sheets. The two formulations with 4% glycerine
; are directionally superior to the other one without glycerino bUt
the third test batch (glycerine/water premix) delivered direc-
tionally better brightening than the other two batches. Visual
evaluation agrees with the instrumental data.
This invention has been described with respect to cer-
tain preferred embodiments and various modifications whereof will
occur to persons skilled in the art in the light of the instant
specification and are to be included within the spirit and pur-
view of this application and the scope of the appended claims.
'I
: ,
-38-
