Note: Descriptions are shown in the official language in which they were submitted.
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[SPECIFICATION]
COCONDENSED UREA RESIN
[EIELD OF T~IE INVENTION ]
The present invention relates to an inexpensive
cocondensed condensation resin with advanced resistances
to water, weather and boiling water, and with high
workability. It is useful as an additive, binder,
coating, material and the like for organic and
inorganic materials including wood, fiber, paper and
glass fiber.
[DESCRIPTION OF THE PRIOR ART]
Hitherto, the urea resin used for adhering materials
including wood has a poor resistance to water, and a
cocondensed resin produced by cocondensing urea with a
comonomer including melamine and phenol to improve the
water resistance has been provided. Nevertheless, even
though the wa~er resistance of such a cocondnsed urea
resin has been improved, the resistances to boiling
water and weather are still insufficient. After the
above, although the cocondensation of urea with a
polyvalent phenol including resorcin has been
investigated, it is very difficult to cocondense urea
with a polyvalent phenol monomer because both the
reaction rates with aldehyde are much different from
each other. It has been considered so far, therefore,
that the cocondensation of urea with a polyvalent
phenol is practically impossible.
Accordingly, instead of a urea polyvalent phenol
~ '
2086~1~
cocondensed resin, a mixture of urea resin with a
polyvalent phenol monomer (e.g. Tokko Sho No. 57-9600)
and a mixture of urea resin with a polyvalen-t phenol
resin (e.g. Tokko Sho No. S8-23425) have been provided.
Although the resistances to water and boiling water of
the said mixture and the resin mixture are therefore
improved, additives including a modifier resin, organic
and inorganic fillers, a thickening agent and a curing
agent are not necessarily compatible with the said
mixtures, so the compounds are thickened and finally
become immiscible, and if the worst should happen, the
pot life of the said mixtures, after compounding is
shortened and the workability is lowered.
Further, a process for condensing the primary
condensation product of urea with a polyvalent phenol
and formaldehyde when required (Tokkai Sho No. 48-54148)
has been provided. In this process, nevertheless, the
addition of the polyvalent phenol is as low as 0.05 to
0.2 mol to 1 mol of the urea because the primary
condensation product of the urea is used. The effect of
the cocondensation with the said polyvalent phenol is,
therefore, not necessarily sufficient for improving the
resistances to boiling water and weather.
~DISCLOSURE OF THE INVENTION]
As a means to disclose the above-described problems in
the prior art, the present invention provides a
cocondensed urea resin which is produced by
cocondensing 1 mol of urea with 0.2 to 2.0 mol of a
polyvalent phenol and 0.1 to 2.0 mol of an aldehyde
donor by heating in a pH range from 4 to 9.
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[DETAILED DESCRIPTION OF THE INVENTION]
The present invention is described in detail hereafter.
[POLYVALENT PHENOL]
The polyvalent phenol in the present invention is a
mixture of one or two or more of the polyvalent phenols
including resorcin, alkyl resorcin, pyrogallol,
catéchol, alkyl catechol, hydroquinone, alkyl
hydroquinone, phloroglucinol, bisphenol and
dihydroxynaphthalene, preferably resorcin or alkyl
resorcin, particularly preferably alkyl resorcin, with
a higher reaction rate with aldehyde than resorcin.
The alkyl resorcin in the present invention is 5-methyl
resorcin, 5-ethyl resorcin, 5 propyl resorcin, 5-n-butyl
resorcin, 4,5-dimethyl resorcin, 2,5-dimethyl resorcin,
4,5-diethyl resorcin, 2,5-diethyl resorcin, 4,5-
dipropyl resorcin, 2,5-dipropyl resorcin, 4-methyl-5-
ethyl resorcin, 2-methyl-5-ethyl resorcin, 2-methyl-5-
propyl resorcin, 2,4,5-trimethyl resorcin and 2,4,5-
triethyl resorcin. Particularly, 5-methyl resorcin
cocondenses easily with the urea and produces a low-
temperature curable, water, weather and boiling water-
resistant cocondensed urea resin. Since mixed
polyvalent phenols produced by the dry distillation of
oil shale from Estonia are inexpensive and contain much
reactive alkyl resorcins as well as 5-methyl resorcin,
they are some of the most adequate polyvalent phenols
for the present invention.
[ALDEHYDE DONOR]
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The aldehyde donor used in the present invention i.s one
or two or more mixtures of compounds which have aldehyde
group(s) or liberate aldehyde group(s) by such a
treatment as heating including formalin, formaldehyde,
paraformaldehyde, trioxane, acetaldehyde,
propionaldehyde, polyoxymethylene, chloral,
hexamethylenetetramine, fulfural, glyoxal, n-butyl
aldehyde, capronaldehyde, benzaldehyde, acrolein,
tetraoxymethylene, phenyl acetaldehyde, o-tolylaldehyde
and salicylaldehyde.
~COMPLEXING AGENT]
In the present invention, a complexing agent may be used
for moderating the reaction because the reactivity of
the polyvalent phenol, particularly such an alkyl
resorcin as 5-methyl resorcin, with aldehyde is
extremely high. The complexing agent in the present
invention is a compound which has ketone or amide
group(s) capable of complexing the phenol group in the
polyvalent phenol including acetone and caprolactam,
preferably acetone. Although the addition of the
complexing agent is not specially limited, it is usually
preferable to add approximately 0.4 to 0.~ mol of the
complexing agent to 1 mol of the polyvalent phenol.
[THIRD COMPONENT]
In addition to urea, a polyvalent phenol, an aldehyde
donor and a complexing agent in the cocondensation
reaction for manufacturing the cocondensed resin in the
present invention, one or two or more of the
cocondensing or modifying agents including melamine,
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208~8
thiourea, phenol, alkyl phenol, benzoguanamine,
toluene, coumarone, cyclohexane, cashew nut oil,
tannins, dammar, shellac, a rosin or rosin derivative,
petroleum resin, methanol, ethanol, ethylene glycol,
diethylene glycol, polyethylene glycol, glycerin,
furfurl alcohol, linseed oil, tung oil, or castor oil
may be added.
[MANUFACTURING OF COCONDENSATION RESIN]
The process for manufacturing the cocondensed resin of
the present invention involves adding 0.2 to 2.0 mol,
preferably 0.4 to 2.0 mol, of a polyvalent phenol and
0.16 to 1.6 mol of a complexing agent as required to 1
mol of urea, ad~usting the pH to 4.0 to 9.0, preferably
to 8.0 to 8.5, with an acid or alkali, adding 0.1 to 2.0
mol of an aldehyde donor to the mixture and heating it
usually at a temperature of 75 to 80C . It is desirable
to cool -the reaction product down to room temperature
after the reaction and adjust the pH to approximately
8Ø
Since a large quantity of unreacted urea remains in the
product resin in the case of the addition of 0.2 mol or
more of a polyvalent phenol, the resistances to water
and boiling water of the resin are low and the stability
of low in the case of an addition of 2.0 mol or more of
said polyvalent phenl. The performance of the product
resin is sometimes deteriorated by adding 0.4 mol or
less of said polyvalent phenol depending upon the type
of it because the unreacted urea easily remains in the
cocondensation product. It is, therefore, usually
preferable to add 0.4 to 2.0 mol of said polyvalent
phenol.
208~41c~
In the present invention, a third component may be added
to the reaction system either before the condensation
reaction or after the reaction if the third component
does not participate in the cocondensation.
[ COMPO~NDI NG ]
The products including adllesive, binder and coating
material from the cocondensed resin of the present
invention are usually manufactured in such a way -that
15 to 80 parts by weight of the aldehyde donor is added
to 100 parts by weight of the cocondensed resin of the
present invention, and if necessary, a third component
including natural rubber and its derivatives, synthetic
rubber such as SBR, NBR and CR, synthetic resin such as
vinyl acetate resin, acrylic resin and urethane resin,
filler such as CMC, PVA, starch, glue, gelatin, powdered
blood, walnut powder, coconut shell flour, wheat flour,
calcium carbonate, talc and gypsum, pigment, dye, flame
retardant, insecticide or an antiseptic agent is added.
[APPLICATIONS]
The adhesives, binders and coating materials
manufactured using the cocondensation product of the
present invention are cured at normal temperature or by
heating. Since they are rapidly cured by heating at 100
C or higher, cured resins adhesive to woody and fibrous
materials are produced.
The cocondensed resin of the present invention is,
therefore, applicable to adhesives, binders and coa-ting
materials for organic and inorganic materials including
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wood such as plywood, laminated lumber and particle
board, paper such as corrugated board, fiber such as
felt and non-woven fabric, glass fiber, rock wool,
ceramic fiber and carbon fiber.
Since the acidic curing catalyst required for curing
conventional cocondensed resins is not used for curing
the cocondensed resin of the present invention, it is
kept neutral. Accordingly, even afer a long time, the
cured resin is not hydrolyzed by the remaining acid and
an adhered woody material does not deteriorate,
whereupon high durability can be expected. In a case
of necessity, nevertheless, an acidic catalyst may be
used.
Unlike the conventional cocondensed resin, the
resistances to water, boiling water and weather of the
cocondensed resin of the present invention produced by
cocondensation with a polyvalent phenol are equal to
those of polyvalent phenol-based resins including
resorcin and alkyl resorcin-based resins.
Since the curing rate of a resorcin-based resin using
paraformaldehyde as the curing agent is so high that its
pot life is short, hexamethylenetetramine must be used
as the curing agent. Meanwhile, the pot life of the
cocondensed resin of the present invention is as long
as two hours in a case using paraformaldehyde and it is
cured at normal temperature. Moreover, it is able to
be cured in a remarkably short time by heating at a
temperature as relatively low as 100 to 120C -
Consequently, the workability of the cocondensed resin
of the present invention is very high.
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The density of the crosslinkings between urea and
aldehyde produced by cocondensation with a polyvalent
phenol is so low in the cocondensed resin of the present
invention that the hardness of the resin is decreased,
thereby reducing the stress caused by cure shirinkage.
The layers in the cured resin product are hardly cracked
or deformed, as well as the resin being is durable.
[EXAMPLE 1]
60 parts by weight (1 mol) of urea 62 parts by weight
(0.5 mol) of 5-methyl resorcin and 14.5 parts by weight
(0.25 mol) of acetone as the complexing agent are put
into a reaction flask. The pH value of the mixture is
adjusted to 8.0 with a 40%-caustic soda solution.
Then, 40.5 parts by weight (0.5 mol) of 37~-formalin is
added drop by drop to the stirred solution at 50 to 55C
for 30 minutes and successively heated up to 75 to 85C
for 90 minutes to accelerate the reaction. After
cooling it down, the pH of the solution is adjusted to
8.0 again to produce the cocondensed resin (Sample 1)
which is stable at room temperature for two to three
months or longer.
An adhesive agent is prepared by adding 20 parts by
weight of coconut shell flour as the filler and 20 parts
by weight of paraformaldehyde as the curing agent to
100 parts by weight of Sample 1 and mixing them. A
sheet of plywood is manufactured using the adhesive
agent under the under-mentioned conditions and the
adhesive strength is measured. The results are shown
in Table 1.
Composition: 3-ply (1.5-3.0-1.5 mm) lauan
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Application: 35 g/300 x 300 mm2
Hot pressing: 10 kg/c~ at 105C for 4 mins.
[TABLE 1]
Adhesivity Wood failure
(kg/cm2) rate (%)
Ordinary adhesion 11.4 100
. Boiling for 72 hrs 8.3 98
:.
(Adhesion test: In compliance with the Test Method
! for Structural Plywood of JAS)
~EXAMPLE 2]
The cocondensed resin (Sample 2) is prepared using 55
parts by weight (0.5 mol) of resorcin instead of the 5-
methyl resorcin as used in Example 1, using the same
recipe and under the same reaction conditions as in
Example 1. A sheet of the same plywood as in Example 1
is manufactured and an adhesive strength test is carried
out. The results are shown in Table 2.
[TABLE 2]
_ Adhesivity Wood failure
. (kg/cm2) rate (~)
. Ordinary adhesion 11.0
Boiling for 72 hrs 8 0 95
[EXAMPLE 3]
20 parts by weight of paraformaldehyde is added to 100
_ g _
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parts each by weight of Samples 1 and 2 of the
cocondensed resin used in Examples 1 and 2,
respectively. 10 wt% of broadleaf-tree fibrillated
chips is added to each of the mixtures, and they are
respectively mixed. The mixtures are respectively
heated under pressure at 140C for 2 minutes to
fabricate fiberboards 3 mm thick with a specific gravity
of 0.8. The performance of the said fiberboards is
shown in Table 3.
[COMPARISON 1]
For comparison with Example 3, 0.6 parts by weight of
ammonium chloride as the curing agent is added to 100
parts by weight of urea resin corresponding to 50% of
the normal condition to manufacture an adhesive agent.
A sample of this is tested in the same way as in Example
3. The test results are shown in Table 3.
[TABLE 3]
sending strength Flexibility
_ ~kg/~ )
Sample 1 200 O
Sample 2 180
Comparison 1 170 X
Flexibility;
O : When a test piece 50 mm wide and 300 mm long is
bent in the center at 20 degrees, the
flexibility remains unchanged.
: The test piece is cracked by the bending though
it is not broken.
:,
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X : The test piece is broken by the bending.
[EXAMPLE 4]
parts by weight (1 mol) of urea, 74 parts by weight
(0.5 mol) of alkyl resorcin obtained by the dry
distillation of oil shale, and 14.5 parts by weight
(0.25 mol) oE acetone as the complexing agent are put
into a reaction flask. The pH value of the mixture is
adjusted to 8.0 with a 40~-aqueous solution of caustic
soda and 40.5 parts by weight (0.5 mol) of 37~-formalin
is added drop by drop to the stirred solution at a
temperature of 50 to 52C for 30 minutes. Then the
solution is heated at 80 to 85 C for 100 minutes to
accelerate the reaction. After cooling the solution
down to room temperature, the pH of the said solution
is adjusted to 8.5 to produce the cocondensed resin
(Sample 3). A sample of the said resin is stable for
three months or longer.
An adhesive agent is prepared by adding 15 parts by
weight each of walnut powder and paraformaldehyde to 100
parts by weight of the sample resin and mixing them. A
sheet of plywood is fabricated in the same way as in
Example 1. The pot life and adhesion tests for the test
piece are then carried out. The test results are shown
in Table 4.
[COMPARISON 2]
For comparison with Example 4, 15 parts by weight of
walnut powder and 3 parts by weight of paraformaldehyde
as the curing agent are added to a mixture of 80 parts
by weight of urea resin corresponding to 50% of the
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2086418
normal condition with 20 parts by weight of 50%-alkyl
resorcin to prepare an adhesive agent. The same tests
as in Example 4 are then carried out. The test results
are shown in Table 4.
[TABLE 4]
Sample 3 Comparison
Sample 2
Pot life (hrs) 3.8 1.0
Ordinary adhesion
Adhesivity (kg/cn~) 12.5 11.2
Wood failure rate (~) 100 80
Boiling for 72 hrs
Adhesivity (kg/cn~) 8.5 7.5
Wood failure rate (%) 100 70
(Pot life: In accordance with the JIS K6840 Test
Method)
The test results in ~xamples 1 to 3 indicate that the
adhesivity and the resistances to water and boiling
water of the cocondensed resin of the present invention
are high and that an alkyl resorcin gives higher
flexibility to the boards than resorcin from among the
polyvalent phenols. The results of Example 4 indicate
that the pot life and workability of the resin of
Sample 3 are superior to -those of a blend of urea resin
and a polyvalent phenol.
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