JPH083079B2 - Adhesive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an adhesive composition.

More specifically, the present invention relates to an adhesive composition which is excellent in adhesiveness to wood containing tar, has a short hot pressing time, and has excellent durability, particularly as an adhesive for laminated wood.

[Conventional technology and its problems]

Conventionally, a formalin-based condensation resin adhesive is obtained by condensing one or more amino compounds such as urea, melamine and besozoguanamine and one or more phenol compounds such as phenol and resorcinol with formaldehyde.

When these adhesives are used as adhesives for plywood, for example, the initial adhesive strength (temporary adhesive strength) is poor, and after cold pressure bonding,
Peeling of the plywood occurs, which greatly hinders the subsequent hot-pressing process, resulting in poor productivity and causing defective plywood.

As a method of improving such initial adhesive strength, conventionally, polyvinyl alcohol (PVA) and carboxymethyl cellulose have been blended during the synthesis of the formalin-based condensate resin.

However, carboxymethyl cellulose only exerts a thickening effect and lacks initial adhesive strength, and
Polyvinyl alcohol has a poor storability that it gels when left standing.

The method of adding polyvinyl alcohol at the time of sizing is that the viscosity of the sizing solution is high and the workability is poor because of the thickening effect similar to carboxymethyl cellulose, and that the water resistance decreases by increasing the PVA amount. There are drawbacks.

Currently, regarding amino compounds of formalin-based condensation resin,
The shortening of the hot pressing time that can improve the productivity in the production of plywood is performed by using the following method. That is, hydrochloric acid, aluminum chloride, formic acid, paratoluene sulfonic acid, which are strong acid catalysts, are used to cure the amino compound of the formalin-based condensation resin, or ammonium salts such as ammonium chloride that react with formaldehyde to release an acidic substance. , The method of increasing the amount of ammonium phosphate, ammonium acid, etc. and simply lowering the pH to cure.

However, the method of increasing the amount of substances that release acidic substances by reacting with strong acid or formaldehyde that lowers and hardens the pH is such that the viscosity of the paste solution changes drastically, and in the spreader roll and flow coater of the coating method of the current plywood factory production line. , Workability is poor, and when the amount of substances that release acidic substances by reacting with strong acids and formaldehyde is increased and the pH is lowered, the adhesive deteriorates quickly and has poor durability. It is not used at present because the adhesive strength of the material structure deteriorates due to acid deterioration.

Currently, as a method for improving the durability of formalin-based condensation resin adhesives, a method of adding acids such as citric acid, lactic acid, phthalic acid, and succinic acid and a method of copolymerizing epoxies, isocyanates, and phenols are available. It is considered.
However, the method of adding acids causes the pot life to become short, and the method of copolymerizing with epoxies, isocyanates, and phenols leads to an increase in the price of the paste solution, resulting in a long hot pressing time, Poor adhesion, leaving problems in workability.

The present invention is intended to eliminate the drawbacks of the prior art.

[Means for solving problems]

The present invention for achieving the above object relates to an adhesive composition comprising a formalin-based condensation resin and an acidified aminoethylated vinyl interpolymer.

The formalin-based condensation resin used in the present invention is a condensation resin of formalin and an amino compound, for example, a condensation resin of one or more kinds of amino compounds such as urea, melamine, and guanamine with folimarin, or formalin and phenol. Condensation resins with compounds, such as phenols,
A condensation resin of formalin and one or more of resorcinol and the like.

Also included are modified resins obtained by partially modifying these resins with acetals, alcohols, polyvinyl alcohol and the like.

Of these, a condensation resin of an amino compound and folimarin is particularly preferable, and the molar ratio of the formaldehyde / amino compound is 1.1 to 3.0 and the solid content is 35 to 100%.
Formaldehyde / amino compound = 1.5 to
A solids content of 2.8 and a solid content of 40 to 75% is suitable.

The acidified aminoethylated vinyl interpolymer used in the present invention has the formula The polymer is acidified by reacting the polymer with an acid.

(Wherein R and R ′ are the same or different hydrogen atoms or alkyl groups having 1 to 4 carbon atoms, the average value of n is 1.0 to 2.5, and the polymer before aminoethylation is 3 wt% or more. , Preferably having 5% by weight or more of —COOH group side chains).

The aminoethylated interpolymer is prepared from a carboxyl-containing side chain vinyl interpolymer produced by solution polymerization of a monomer mixture, one of which is a vinylcarboxylic acid monomer. The monomer mixture uses a catalyst and usually polymerizes at a constant elevated temperature, and the polymerization is stirred until its completion.

Certain refinement operations used in solution polymerization are carried out, such as stepwise charging of the monomer mixture, addition of catalyst, reaction under inert atmosphere or batch or continuous polymerization.

Vinylcarboxylic acid monomers include α, β-ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, cinnamic acid and crotonic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid, and half of the above dicarboxylic acids. Includes esters and mixtures thereof. Preferred vinylcarboxylic acids are unsaturated monocarboxylic acids, particularly preferably acrylic acid and methacrylic acid.

Vinyl copolymers are vinyl carboxylic acids and one or more copolymerizable monomers (eg, vinyl aromatic monomers, unsaturated monocarboxylic acid alkyl esters, unsaturated dicarboxylic acid dialkyl esters, vinyl chloride, vinylidene chloride, vinyl fluoride). And N-vinylpyrrolidone and the like).

Suitable vinyl aromatic monomers include styrene, alpha-methylstyrene, vinyltoluene, various alkyl substituted styrenes, various halogen substituted styrenes. Particularly preferred vinyl aromatic monomers are styrene, α-methylstyrene and vinyltoluene. Suitable alkyl esters of unsaturated mono- and dicarboxylic acids include the esters obtained by esterifying the above vinylcarboxylic acids with aliphatic alcohols having 1 to 12 carbon atoms.
Acrylic acid and methacrylic acid esters are preferred,
Particularly preferred esters are methanol, ethanol, isopropanol, butanol, 2-ethylhexanol esters of acrylic acid and methacrylic acid. Small amounts of acrylonitrile (up to 10%) may also be used to improve the properties of the adhesive.

Preferred copolymers are prepared from styrene, one or more acrylic or methacrylic acid ester monomers and vinyl carboxylic acid. As an example, styrene can copolymerize up to 60% with acrylate monomers and carboxylic acids. Also, acrylic monomers can be used up to 90 wt%.

The vinyl copolymer is preferably the weight of the carboxylic acid (-
COOH) is 3% or more, more preferably 7.5 to 12.5 wt
Manufactured using sufficient vinyl carboxylic acid to be 100%. And the balance is the preferred comonomers mentioned above.

Suitable solvents for the polymerization include alcohols, ketones, aromatic hydrocarbons and mixtures thereof. Polymerization temperature is 60 ℃
~ 140 ° C, preferably in the range 80 ° C to 100 ° C, although the optimum temperature depends on the monomer, catalyst and other conditions.

The aminoethylated interpolymer used in the present invention is a vinylcarboxylic acid interpolymer in a suitable solvent,
It is prepared by an amination reaction with an excess of alkyleneimine or N- (aminoalkyl) -substituted alkyleneimine. Suitable alkyleneimines are ethyleneimines such as ethyleneimine, propyleneimine and butyleneimine and mixtures thereof such as 1.
Includes 2-alkenylimine. Ethyleneimine is commercially available and is a preferred raw material.

A particularly useful raw material is N-, which has the same degree of reactivity as alkyleneimines and is less volatile than alkyleneimines.
(Aminoalkyl) substituted alkyleneimine. Typical examples thereof are N- (2-aminoethyl) aziridine, N-
There are (3-aminopropyl) aziridine, N- (2-aminopropyl) propyleneimine and N- (2-aminobutyl) butyleneimine. Particularly preferred are N- (2-aminoethyl) aziridine, and N- (2-aminopropyl) propyleneimine.

A plurality of amino groups are bonded to each carboxyl group in the interpolymer (that is, n value 1.
For 0 or more), a vinylcarboxylic acid interpolymer is reacted with 2 moles or more of an alkyleneimine based on the carboxyl equivalent in an organic solvent. The preferable range of the number of moles of alkyleneimine is 2 to 5, and the average n value is 1.5 to 2.5. In the case of N- (aminoalkyl) alkyleneimine, the amount of carboxylic acid is 1 mol or more, preferably 1 to 1.
Used 5 moles.

The temperature of the amination reaction is 50 ° C or higher, preferably 50-100.
° C. Higher temperature and pressure conditions can of course be implemented. Different from this temperature range, some documents describe a method of mixing at room temperature, maintaining the temperature for a certain period of time, and then heating. The products obtained by that process, however, differ substantially from those of the present invention in their thermal stability and in the content of amide nitrogen or unreacted acid.

The aminoethylated interpolymer can also be obtained by a method in which 1 to 2 mol of alkyleneimine is added to an interpolymer having a carboxyl group side chain and reacted at room temperature. The average n value of the resulting aminoethylated interpolymer is 1 to 1.3. The interpolymers aminoethylated in this way are considerably less stable, but are not a problem if the adhesive is used for a short period of time.

The reaction of alkyleneamine or N- (aminoalkyl) alkylene with a carboxylic acid group is carried out by using methyl ethyl ketone,
It is preferably aprotic such as a ketone such as xylene, toluene, ethylbenzene or an aromatic hydrocarbon, but a part or the whole thereof may be replaced with an alcohol. Suitable alcohols are aliphatic alcohols having 2 to 5 carbon atoms, alkylene glycols having 1 to 6 carbon atoms,
Includes alkyl monoethers of ethylene glycol and propylene glycol and diacetone alcohol.

The amination reaction is carried out in a solvent consisting of 20 wt% or less alcohol and the remaining aromatic hydrocarbon. After completion of the amination reaction, the solvent composition is stripped, and the composition of the solvent is adjusted to 30 to 100 wt% of alcohol and 70 to 0 wt% of ketone or ether. Particularly preferred solvents are ethanol, propanol, isopropyl alcohol, and isoptyl alcohol. , N-butyl alcohol, n-butyl alcohol and monomethyl ether of propylene glycol. The polymer concentration in the final product is 1-60 wt% depending on the solubility of the polymer and the application.

The aminoethylated copolymer is acidified by mixing the acid with the copolymer in a suitable water-miscible solvent or solvent mixture. Suitable solvents are lower alkyl ethers of ethylene glycol, propylene glycol and dipropylene glycol, of which representative examples are butyl ether of propylene glycol, ethyl ether of ethylene glycol, propyl ether of diethylene glycol, isoptyl ether of mixed propylene glycol and the like. There is.

Preferred acids are those that form an acid salt with the amino side chains of the interpolymer. The acid is also desirably volatile. Therefore, formic acid or acetic acid is desirable. Less volatile acids such as glycolic acid, propionic acid, butyric acid may also be used. Inorganic acids such as phosphoric acid may also be used.

The amount of acid used is usually equal to the amount of amino groups, but may be in excess or deficiency. The minimum amount required is that amount of acidic aminoethylated copolymer to provide water dispersibility.

The mixing ratio of the formalin-based condensation resin and the acidified aminoethylated interpolymer in the present invention (weight ratio,
The same applies hereinafter) in terms of solid content is formalin-based condensation resin / polymer = 100 / 0.05-50, preferably 100 / 0.5-20.

To the adhesive of the present invention, an aqueous emulsion conventionally used as an adhesive for wood materials and synthetic rubber latex can be added and used.

Examples of the aqueous emulsion include a homoemulsion resin such as a vinyl acetate emulsion resin, an acrylic emulsion resin and a vinyl chloride resin, an emulsion resin obtained by copolymerizing two or more kinds, and a resin obtained by copolymerizing ethylene and styrene.

Examples of synthetic rubber latex include butadiene,
Examples thereof include butadiene latex, chloroprene latex, isoprene latex having a conjugated diene compound such as isoprene, and monomers copolymerizable with these, such as acrylonitrile, styrene, and methyl methacrylate. Further, as this reactive monomer which also includes a latex obtained by modifying these synthetic rubber latex with a reactive monomer exemplified below,
For example, monomers having a carboxy group such as maleic acid, monomers having an acid anhydride such as maleic anhydride, monomers having an N-methylol group such as N-methylolacrylamide, monomers having an amino group such as vinylpyridine, acrylamide Examples thereof include monomers having an amide group.

Further, the adhesive composition of the present invention may further contain a filler. This extender not only increases the amount, but also has a function of complexly reacting with other components of the adhesive, formalin and acidified aminoethylated vinyl interpolymer, to impart durability and initial adhesiveness. is there.

As the bulking agent, for example, wheat flour, starches, defatted soybean flour, blood meal, etc., which are mixed with the conventional adhesive for plywood production, can be used.

Further, the adhesive composition of the present invention may further contain a filler. This filler not only acts to prevent excessive penetration of the adhesive into the wood, but it also reacts complexly with other components of the adhesive, especially formalin and acidic aminoethylated vinyl interpolymers, for durability, It also acts to impart initial adhesiveness.

As the filler, neutral to acidic inorganic substances such as clay, kaolin, zeolite, silicic acid powder, and gypsum, and organic substances such as wood flour, walnut shells and coconut flour can be used.

The blending ratio of these fillers and / or fillers is 10 to 100% by weight based on the formalin-based condensation resin, and the blending ratio of the adhesive for plywood is preferably 15 to 50% by weight. These extenders and fillers may be used alone or in combination of several kinds.

Furthermore, the adhesive composition of the present invention generally contains an acidic substance as a catalyst for curing a formalin-based condensation resin, or an ammonium salt which reacts with formaldehyde to release an acidic substance, such as hydrochloric acid or paratoluenesulphonic acid. Aluminum chloride, ammonium chloride, ammonium phosphate, ammonium acid and the like can also be added.

In addition, an aqueous polymer thickener such as polyvinyl alcohol, methyl cellulose polyethylene oxide, carboxymethyl cellulose, hydroxyethyl cellulose, and alkynic acids can be added to the composition of the present invention.

The adhesive composition of the present invention is particularly suitable for plywood or as an adhesive for secondary processing thereof, for woodworking,
It is useful as an adhesive for laminated wood, particle board, paper, and fiber processing.

[Examples] Next, the present invention will be further described with reference to Examples, but the present invention is not limited thereto.

Example 1. Formalin-urea resin (molar ratio: formaldehyde /
Urea = 2.3, solid content 50%, viscosity 2.0P / 25 ° C) 100 parts and acidified aminoethyl vinylated interpolymer 5 parts (Nippon Shokubai "Polyment NK-100PM", wheat flour 17 parts, water 13 parts and ammonium chloride 0.5 parts were mixed to obtain an adhesive composition having a viscosity of 100 P / 25 ° C.

Example 2 Formalin-urea-PVA resin (molar ratio: formaldehyde / urea = 2.5, polymerization degree 1.700, saponification degree 99 mol% PV
3.6 parts of A to urea, 100 parts of solid content 50%, condensate of viscosity 1.5P / 25 ° C) and 5 parts of acidified aminoethylated vinyl interpolymer (Nippon Shokubai "Polyment NK-100PM", wheat flour 17) Part, 13 parts of water and 0.5 part of ammonium chloride are mixed,
An adhesive composition having a viscosity of 120 P / 25 ° C. was obtained.

Example 3. Formalin-melamine-urea copolymer resin (molar ratio: formaldehyde / urea-melamine = 2/1, solid content 55%,
Viscosity 0.9P / 25 ° C) 100 parts acidified aminoethylated vinyl interpolymer (Nippon Shokubai "Polyment NK-100P"
M ”5 parts, wheat flour 17 parts, water 10 parts and ammonium chloride 0.5 parts were mixed to obtain an adhesive composition having a viscosity of 105 P / 25 ° C.

Example 4. Formalin-melamine-urea-PVA (polyvinyl alcohol) resin (molar ratio: formaldehyde / urea-melamine = 2.7 / 1, PVA having a degree of polymerization of 1700 and a degree of saponification of 99 mol% is 6.8 parts of solid with respect to urea. Min 54%, viscosity 1.0P / 25 ℃ condensate)
100 parts and acidified aminoethylated vinyl interpolymer (5 parts by Nippon Shokubai "Polyment NK-100PM", flour 17
Parts, water 10 parts and ammonium chloride 0.5 parts are mixed to obtain a viscosity of 130
An adhesive composition at P / 25 ° C was obtained.

Comparative Example 1 100 parts of formalin-urea resin used in Example 1 and 17 parts of wheat flour, 13 parts of water and 0.5 part of ammonium chloride were mixed,
An adhesive composition having a viscosity of 25 P / 25 ° C. was obtained.

Comparative Example 2. 100 parts of formalin-urea-PVA resin used in Example 2 and 17 parts of wheat flour, 13 parts of water and 0.5 part of ammonium chloride were mixed to obtain an adhesive composition having a viscosity of 25P / 25 ° C.

Comparative Example 3. 100 parts of the formalin-melamine-urea copolymer resin used in Example 3 was mixed with 17 parts of flour, 10 parts of water and ammonium chloride.
0.5 parts were mixed to obtain an adhesive composition having a viscosity of 25P / 25 ° C.

Comparative Example 4. Formalin-melamine-urea-PV used in Example 4
A resin 100 parts and flour 17 parts, water 10 parts and ammonium chloride 0.
5 parts were mixed to obtain an adhesive composition having a viscosity of 23P / 25 ° C.

Examples 1 to 4 and Comparative Examples 1 to 4 thus obtained
Using the adhesive composition, adhesion was performed under the following working conditions to prepare plywood, and durability was evaluated.

Type and composition of veneer: Red lauan 1.7mm + 1.7m / m + 1.7m / m Coating weight: 155g / m ² (-adhesive layer) Cold pressure: 20 ℃ × 10kg / cm ² × 30 minutes Heat pressure: 115 ℃ × 10kg / cm ² × 100 seconds The plywood bonded under the above conditions was subjected to the JAS “standard plywood Japanese agricultural and forestry standard” normal adhesion test, hot and cold water immersion adhesion test, boiling repeated adhesion test and dry water repeated adhesion test. The durability was evaluated.

 The results are shown in Table-1 and Table-2.

1. Adhesion test under normal conditions Adhesion test is performed on the test piece under normal conditions at 20 ± 2 ° C and 65 ± 10% RH, and the shear strength and the average rupture rate of wood are obtained.

2. Adhesion test for hot and cold water immersion After soaking the test piece in hot water of 60 ℃ ± 3 ℃ for 3 hours,
Immerse it in room temperature water until it is immersed in water, and perform an adhesive strength test in the normal condition while it is wet to determine the shear strength and the average xylem fracture rate.

3. Repeated boiling test for adhesive strength After soaking the test piece in boiling water for 4 hours, 60 ℃ ± 3 ℃
At 20 ° C for 20 hours, further soak in boiling water for 4 hours, soak it in water at room temperature until it dries, and conduct an adhesive strength test under normal wet conditions. Ask for.

4. Repetition of dry water After dipping the test piece in warm water of 60 ℃ ± 3 ℃ for 8 hours,
The process of leaving for 40 hours in a dryer at ℃ ± 3 ℃ for 1 cycle is treated as 11 cycles, and this is left at room temperature for 8 hours to perform an adhesive strength test, and the shear strength and the average wood fracture rate are obtained.

Example 5. Formalin-urea resin (molar ratio: formaldehyde /
Urea = 1.9, solid content 73%, viscosity 25P / 25 ℃) 100 parts acidified aminoethylated interpolymer (NK-100 manufactured by Nippon Shokubai)
PM) 2 parts, flour 8 parts, ammonium chloride 1.5 parts, water 6
The parts were mixed to obtain an adhesive composition having a viscosity of 32 P / 25 ° C.

Example 6. Formalin-urea resin (molar ratio: formaldehyde /
Urea = 1.9, solid content 73%, viscosity 25P / 25 ° C) 100 parts vinyl acetate emulsion resin (Shinko Pond No. 26 (Oshika Kogyo solid content 35%, viscosity 800P / 30 ° C) 20 parts, acidified aminoethylation Interpolymer (Nippon Shokubai NK-100PM) 2
Parts, flour 8 parts, ammonium chloride 1.5 parts, and water 6 parts were mixed to obtain an adhesive composition having a viscosity of 33 P / 25 ° C.

Comparative Example 5. 100 parts of formalin-urea resin used in Example 5, 8 parts of wheat flour, 1.5 parts of ammonium chloride and 6 parts of water were mixed to obtain an adhesive composition having a viscosity of 32 P / 25 ° C.

Comparative Example 6. 100 parts of formalin-urea resin used in Example 6, 20 parts of vinyl acetate emulsion resin, 8 parts of wheat flour, 1.5 parts of ammonium chloride, 4 parts of water were mixed, and an adhesive composition having a viscosity of 33P / 25 ° C. Got

Thus obtained Examples 5-6 and Comparative Examples 5-6
Using an adhesive composition, using a Kometsuga material with a tar content,
Adhesion of test pieces adhered under the following working conditions
Evaluation was carried out by a soaking and peeling test of "Japanese Agricultural Standard for laminated wood".

1. Adhering material and structure: 4 to 6 m / m thickness 20 mm width 98 shown in FIG.
Three plies of Kometsuga material with m / m tarnish 2. Coating amount: 230g / m ² 3. Deposition: within 15 minutes / 20 ℃ 4. Pressing: 7kg / cm ² × 12 hours / 25 ℃ 5. Curing: 25 ℃ x 7 hours [Advantages of the Invention] According to the present invention as described above, an adhesive composition that eliminates the conventional drawbacks when a formalin-based condensation resin adhesive is used as an adhesive for plywood, shortens the heat-pressing time, and excels in durability. I was able to provide things.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-32183 (JP, A) JP-A-2-3481 (JP, A) JP-A-49-93460 (JP, A) JP-B-62- 35437 (JP, B2)

Claims (1)

[Claims] 1. A formula for formalin-based condensation resin (Wherein R and R'are the same or different hydrogen atoms or lower alkyl groups having 1 to 4 carbon atoms, and the average value of n is 1.0 to 2.5), and is an interpolymer having a side chain aminoethyl group. The interpolymer before being aminoethylated comprises an interpolymer having at least 3% by weight of side chain-COOH groups and an acidified aminoethylated vinyl interpolymer obtained by reacting an acid. Adhesive composition.