Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~L201B44
PHENC)LIC RESIN C~:)MPOUNDS
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to internally plasticized phenolic resin
compositions. More particularly, this invention relates to a composition,
5 Q process for the preparation of, and the use of a phenolic resole resin
internally plasticized with a phenolic ester of ~ fatty acid.
Description of the Prior Art
Phenol-formsldehyde condensates of the resole type are used
extensively to treate cellulose compounds and particul~rly to impregnate
10 paper substrates. Upon curin~ to a ~ substantially insoluble and infusiMe
stage, the resinoais material imparts chemical resistance and structur~l
strengths to the substrates for use in a~ variety of applications. A
specific application for a phenolic resole in this manner is in the
m~nufacture of filter media for both air and oil filtering systems and
15 p~ticularly for both stationary and mobile internal combustion engines.
The fabrication of filter structures of the foregoing type involve
the following manufactur;ng operations. In the first or treating step,
a continuous roll of paper is eonYentionally impregnated with a phenolic
resole in the form of ~n alcohol solution of a condensate of phenol
20; wi~h formaldehyde. The saturated paper is heated to remove solvent
~nd the trested paper is then corrugated for the purpose of increRsing
surf~ce area. The corrugated sheet is subsequently conveyed through
An oven in order to advance the cure oî the resinous impregnate to
fusible intermediate or B stage, and then rolled again. B staging may
25 be immedi~te to or time removed from the s~turation step.
~;2iO 1134 ~
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The roll~ of the partially cured corrugated impregnated paper ar~
provided in this manner ~o the filter manufacturer for completion of
the rnEmufacturing sequence~ The latter initially involve~ appropriately
pleating the p~per and then heat-curing it to the final thermoset stage
5 in order to achieve a desired degree of chemis!at, oil and rnoisture
resistance for the filter medium.
The standard phenolic resins used to treat filter paper have a
disadvantage in that the number of folding or corrugating operations
involved in the manufacture causes the ~ilter material to be brittle and
10 crack. Numerous plasticizers which have been developed to eliminate
this difficulty haYe not been entirely satisfactory~ &enerally speaking,
plastieizers of low molecular weight have a disadvantage in that they
are eventually dissipated with the lapse of time &nd thus the compositions
are rendered brittle. This is especially true when there is some hiatus
15 in the manufactllring procedure. Plasticizers of high molecular weight
preclude such phenomenon, but compatibility problems with the base
resin can occur.
Additionally, thermosetting resins such as phenol-formaldehyde
resins have been used extensively as adhesives, laminates, molding
20 materials, paints and the like and improvements to improve flexibility
without decreasing tensile strength are desirable along with improved
moisture resistance for these purposes. Therefore, ~ need exists for an
economical and efficient plasticized phenol-formaldehyde resin
composition to overcome the shortcomings of ~he conventional plasticized
25 phenol-formaldehyde.
SUMMARY OF THE INVENTION
The present invention provides internally plasticized phenol-
aldehyde resin compositions, a process for preparing these compositions
~nd the use OI these compositions as impregnating and/or laminating
30 agents for various substrates but particularly for cellulosic materi~ls.
- In accordan~e with this invention there is provided a thermosetting
phenolic resin cornposition comprising a phenol-aldehyde resole resin in
the presénce of a plasticizing amount of a phenoi ester of a higher
f~tty acid containing from 8 to 22 carbon atoms.
In addition, the invenUon contemplates a process for preparing
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phenol-adehyde resole resin composition which comprises the steps of:
~) form~ng an aqueous alkaline mixture of phenol-aldehyde and
a plasticizing amount of a phenolic ester of a fatty acid containing 8
to 22 carbon aton-s; and
5b) reacting this mixture under alkaline conditions to provide
an internally plasticized phenol-aldehyde resole resin.
The phenolic ~;ter fatty aci~modified phenol-aldehyde resin
~ompositions of this invention are characterized by being internally
plastici~ed, having more linear chains, limited branching and a lowered
10 cross-linking index which results in increased resin flexibility in increased flex fstigue resistance and in moisture resistance. These resins can
readily be produced with very low (e.g., less than about 1%) free
formaldehyde.
The present inven$ion also' contemplates a cellulosic substrate
15 i'mpregnated with a dried and cured resin composition of the present
i~vention and, particularly, contemplates paper filter elements.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The ester employed in accordance with this invention is an es~er
of a phenol and a fatty acid. The phenol moiety can be phenol per
20 se, m-cresol, ~cresol, ~cresoi or aIkyl derivative of phenol, such a t-
butylphenol octylphenol, snd the likeO Among these) phenol itself is
preferred.
The f~tty acids contemplated for use in this invention are saturated
or unsaturated fatty acids containing 8 to 22 csrbon atoms. Such fatty
25 acids may be obtained from oils including drying oils and semi-drying
oils. Specific represent~tive oils include soyabean oil, linseed oil, coconut
oil, tall oil, safflower oil' and the like. Soyabean oil and tall oil are
preferred due to economical advan$ages. Of course, fatty acids obtained
from other sources and purified fatty acids can slso be used~ The fatty
30 acids include,_ter ~, capric, lauric, linoleic, linolenic, myristic, oleic
ond palmitic acids.
The phenolic ester plasticizer can be produced by the use of acid
catalysts and by carrying out the esterîication reaction under moderately
elevated ' reaction conditions. Accordingly, the reaction can be
35 ~ccomplished efficiently by refluxing A mixture of the higher fatty acid
~LZ018~
and phenol in the presence of a small amount of a minerQI acid as
caSalyst. The process involved is an equilibrium reaction and the
attainment of equilibrium is greatly enhanced by a trace of hydrogen
ion. ~hese reacUons can take place at reflux temperatures from about
5 110 to about 200C. There is nothing particularly critical in carrying
out the reaction in this temperature renge and, indeed, if longer reaction
times can be tolerated, lower temperatures can be used including the
use of vacuum for refluxing purposes. At the end of ~he reaction, the
lly~l~ogen ion in the mixture is desireably neutralized (e.g., as by ~dding
10 a base such as sodium hydroxide). Other methods of producing the
ester are known in the art.
The esters are not soluble in water but they are soluble in a
basic aqueous solutiQn of phenol and aldehyde such as that conventionally
used in the manufacture of a phenol formaldehyde resole resin.
Commercial fatty acids obtained from refined tall oil may contain
small amounts of rosin acids as impurities. If rosin acids are present,
neutralization after esterification with sodium hydro~ide can result in
the formation of undesireable lumps in the ester solution. This can be
avoided by the use of a basic amine (e.g., diethyl or triethylamine~ for
20 the final neutralization.
According to the present invention, the phenol and aldehyde are
reacted t~ form a resole in the presence of a plasticizing amount of
the phenolic ester. Such reac~on generally follows the reaction
conditions normally observed for preparing converltional resole
25 condensates, namely, the use of a basic catalyst and carrying out the
condensation under moderately elevated reaction condition. This invention
broadly contemplates the use of resole versus resins which are well
known in the art.
In a resole, the phenol, which may be phenol itself or a substituted
30 phenol such as described above, is often reacted on the basis of one
mole ~tnth rom about 1 to about 1.8 moles of the aldehyde. ~lore
preferably, from about I to about 1.4 moles of aidehyde are employed
per mole of the phenol. Aldehydes which can be used inelude7
formaldehyde, acetaldehyde, propionaldehyde, ben~aldehyde, furfural, or
35 the like. Formaldehyde is preferred îor the practice of this invention
~2~18~4
~nd can be supplied to the re~ction mixture, for example, as formalin
or paraformaldehyde.
As in the preparation oi conventional resoles, 1I basic cat~lyst is
used. Representa~ive catalysts are the hydroxides of alkali metals with
S sodium hydrox;de most often chosen for use. Conventionally, the pH
of the medium is maintained above 7 a~d often from about 7 to about
9.
The amount of e~;ter added to the reaction mixture will vary
depending upon the particular properties desired for the end product.
10 The amoun$s suitable for any given application readily can be determined
by one of ordinary skill in the art. Generally, however, the ester will
be ~dded in amounts ranging from about S to about 20% by weight
based on the total weight of the phenol-formaldehyde resin and ester
solids. However, in some applications, such as coatings, the ester may
15 be present in amounts of up to about 50% or more.
The condensation reaction is generally carried out until the resole
contains less than about 1% frèe ~ormaldehyde. Such resin is capable
of curin~ to a thermoset condition in from about lûO to about 150 sec.
in accordance with the Stroke cure test. This is a standard test
20 procedure prevalently used in preparing a phenolic resin in order to
determine an end point of a cook. In accordance with the test, a one-
half gram sample of the reaction mixture is spread upon the surface
of a cure plate maintained at 150C ~o coYer an area of approximately
2 square cm. The time in seconds is then noted when the film sets
25 up to a hard infusible stage.
Upon obtaining an end point as noted, the reaction mixture
cormentionally is cooled to a temperature in the range of from about
40~ - 60 C and vacuum dehydrated. The~ dehydration is carried out
until the free water or moisture content is not in excess of about 5
30 weight percent. The Karl Fischer moisture determination method (ASTM
Method E203) is the procedure conventionally used ior this purpose.
After the requisite degree OI dehydration is realized the deHydrated
product is cut back Mth ~ polar solvent to provide a solution usually
containing from 50 ~ 65 percent solids. The lower alcohols represent
35 the preferred solvents although ketones and the like can be used.
8~4
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The improved properties, and especially the improved foldability
resistnnce, flexibility and moisture resistance characl:eristics exhibited
by the phenolic fatty acid ester-plasticized pheno}formaldehyde resole
resin compositions of this invention make them emimntly suitable for
5 a wide variety of en~uses such ~s adhesives, impregnating agents,
insulating materials, laminating resins, molding and reinforcing materiRls,
p~ints, coating resins and the like. The resins of this invention ars
useful for imparting the improved characteristics to any porous sheet
material (organicJ inorganic or mixtures thereof) having pores extending
lO from surface to surface. Two or more layers of the same or varying
porosity can be employed in close juxtaposition, or even bonded together,
but also spaced apart by suitable spacing sheets.
The invention is applicable to papers and like sheet materials
formed of any type of fiber including not only cellulose fibers, but also
15 synthetic thermoplastic and nonthermoplastic resin fibers, glass fibers
and fibers of other cellulose derivatives. Also useful, in addition to
papers, are textile fabrics and woven and nonwoven fibrous layers such
as felts, mats and bats made of fibrous materials of any of the types
listed above. Such materials can also contain pigments and other
20 particulate matter.
Typicslly, an impregnated sheet member will contain from about
5 to about 20 weight percent (based on total impregnated sheet member
weight? of solids derived from the phenolic resin of this invention.
Preferably, this impregnated sheet member has such solids substantially
25 uniformly distributed throughout such member. As noted earlier, the
resin composition of this invention is particularly suitable for filters
including oil filters for automobiles and the like.
The internally pl cticized phenolic resins of this invention can also
be used alone or as a mixt~e with conventional phenolic resins for
30 preparing varnishes, coRtings or ~he like. Luminfltes can ~lso be produced
by molding materials impregnated with the resin OI this rnaterial. Such
laminates, coatings ~nd the like ha-/e excellent flexibility char~cteristics
and moisture resistance.
Further detsils regarding the preparation of the phenolic resins
35 of this invention are given in the following working example which is
included for illustrative purposes and is not intended to limit the scope
of the invention. All parts and percentages noted therein are by weight
~less otherwise indicated.
EXAMPLE I
5 Part A
A suitable mixing vessel equipped with an agitator and a heating
means was charged with 70.23 parts of soyabean fatty acid (Proctor and
Gamble product S-210). To this, 24.82 parts of phenol ~99.8%) w~;
added. This mixture was agitated and heated to 50 C. At 50 C, 2.61
10 parts of sulfuric aeid (9~.4%) was charged to the fatty aeid -- phenol
mixture over 8 2 minute period. The contents of the vessel were
agitated and heated over a period of 4 hours to 204 C. The contents
were reacted for 15 minutes at 204 C and allowed to cool to 135 C,
at which point 2.34 parts of sodium hydroxide (50%) was added to
15 neutraiize the material. The materi~ was discharged into a clean dry
container. The properties OI the resultant ester were as shown in Table
L
Table I
pH: 6.5
20 Specific Gravity: 0.986
% Free Phenol: 11.5
Solid Content: no cure unless crosslinked with resin
Viscosity: 800 cps
Part B
To a suitable mixing vessel equipped with an agitator,
thermometer, a heating means and a condenser, 1835.6 parts of phenol
~99.8%) was added. To t.his, 1196.0 parts of formaldel)yde ~50%) was
added (to provide 1.02:1 ratio) and 383.8 parts of the ester described in
Part A was added and ~gitated.
To this mixture 39.2 parts of sodium hydroxide ~25%) was added.
- 8 -
This ~git~ted rnixture was heated to 60 C and allowled to exotherm to
~5 C. The mixture was reacted at 95 C while monitor;ng the pH.
During this reaction 17.12 p~rts additional sodium-hydroxide was added
to maintain a pH of 7.0 - ~.5. The mixture was reacted ~t 95 C to
5 ~ percent Free Formaldehyde of 1.0% or less (as determined by G.P.A.M.
203.3) and a 150 C hot plate Stroke cure (~s deterrnined by G.P.A.M.
207.1) of 1~0 secondc;. The resin was then cooled to 60 C and the
reaction vessel set up for vacuum distillation.
The resin was then distilled at 60 - 65 C under 23-24 inches of
10 vacuum until 607 parts water had been removed into a distillation flask.
The mixture was cooled to 40 C and 633.85 parts methyl alcohol as
well as 58.75 parts methyl ethyl ketone were added. The physical
properties were as shown in Table 2.
Table 2
l 5 ViscositY~ ~30 cps
Specific Gravity: 1.100
pH: 7.7
Refractive Index 1.5250
150 C Stroke cure: 121
% Free Phenol: 11.34
% ~ree Formaldehyde: 1.00
Solids Content: 65.00
% Water: 4,30
Apparent average
Molecular Weight: a4s4
EXAMPLE II
The ester modified phenolic resin produced in Example I was eYaluated
as a filter paper impregnant noting the relevant physical properties
" :
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parti~ularly with regard to fold fatigue characteristics imparted to the
filter paper both before and after curing the treated pl~per. The latter
properties were determined in accordance with standardixed test methods.
For comp~rision purposes several commercial phenolic resins
5 conventionally used were included and referred to hereinbelow as
exemplary of the prior art.
In conducting these tests 6" x 8" size sheets of standard filter
paper were impregnated with the respective resin solutions (diluted with
methanol) to provide about 28% ~ 0.3% resîn solids pick-up. The
10 procedure for treating the impregnated paper in order to advance the
resin component to a B stage involved air drying and then heating in
a forced air oven at 150 C for 2 minutes. The paper was conditioned
at 60% Relative Humidity for 10 minutes. Strips 1/2" x 4" were cut
and then placed in a Tinius-Olsen fold tester. The number of folds
15 were counted at 0.25 kg tension until the paper breaks. Three
commercial phenol formaldehyde resoles resins, GP 5157 (Resin A); GP
5165 (Resin B); and GP 5135 (Resin (~) (all available from Georgia-Pacific)
... .
were used for comparison. All three GP resins are NaO~catalyzed
resole resins. GP 5157 has a formaldehyde phenol mole ra~io of 1.1:1, a
20 pH of 7.2-7.8, a solids content of 60-62%, a specific gravity of 1.124-
10138 ~nd a 135 C Stroke cure of 2-4 minutes. GP 5165 has a
formaldehyde:phenol mole ratio of 1:1, a pH of 7.6-8.2, a solids content
of 62-66%, a specific gravity of 1.110-1.160; a H20 content of 4-5% and
150 C Stroke cure of 90-120 sec. GP 5135 has a formaldehydP:phenol
2~ mole ratio of 1.16:1, a pH of 7.8-8.2, a solids content of 62-66%, a
specific gravity of 1.116-1.124, a ~2 content of 3-5%, ~nd a IS0 C
stroke cure of 60-80 sec.
The results of all tests are set forth in Table 3.
Table 3
30 TestInvention Resin A Resin B Resin C
1. 63 2 10 5
a. 48 1 9 4
3. 71 2 8 5
4. 39 a ~ 5
5, 47 2 7 5
6. 58 2 8 4
l344
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7. ~l 3 6 5
8. ~2 2 1~ 4
9. 63 2 9 4
lO. 59 l 8 5
The fold test results clearly indicate that the este~modified
phenolic resin imparted superior flexibility and flex fatigue resistence,
on B staged paper than the other conventional resins so treated. This
data also indicates that the ester provided intern~l plasticization for
the phenol aldehyde resin. Furthermore, liquid chromatographic analysis
OI $he conventional phenolic resin compared with the ester-modified
phenolic resin indicates that incorporation of the ester ties up some of
the reactive sites on the phenol component of the phenol formaldehyde
resin and in turn methylation and condensation are somewhat retarded.
Chromatograms generally show lower apparent molecular weight fractions
with the incorporation of the ester. The tying up of reactive sites on
the phenol allows a more linear chein polymer with limited branching
and lower crosclinking indexes.
Since modifications will be apparent to those skilled in the art,
it is intended that this invention be limited only by the scope of the
20 appended claims.
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