JPH10310755A - adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive using a thermosetting resin made of formaldehyde as a raw material, the adhesive having a reduced formaldehyde emission amount without impairing its adhesive performance. SOLUTION: The liquid I containing a thermosetting resin (A) using formaldehyde as a raw material, and a formula (1) A maleic anhydride unit represented by the formula (2): And a maleimide unit represented by the following formula (3): (Wherein, R ¹ , R ² and R ³ each represent a hydrogen atom, an alkyl group or a cycloalkyl group) containing a neutralized product (B) of a copolymer comprising a structural unit represented by the following formula: An adhesive consisting of liquid II.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive, and more particularly, to an adhesive comprising a thermosetting resin made of formaldehyde as one of its components. The adhesive provided by the present invention has low formaldehyde emission,
Particularly useful as an adhesive for wood.

[0002]

2. Description of the Related Art Conventionally, phenol resins obtained by the reaction of various phenols with formaldehyde, urea resins obtained by the reaction of urea and formaldehyde,
Thermosetting resins such as melamine resins obtained by the reaction of melamine and formaldehyde are widely used as base polymers for wood adhesives used in the manufacture of plywood and furniture. However, adhesives using these resins made from formalin contain unreacted formaldehyde, which has the problem that this formaldehyde is released into the atmosphere, which deteriorates the working environment during use. I have. In addition, when an adhesive using the above-mentioned resin made from formaldehyde as a raw material is used in the production of plywood and furniture for housing, since the hermeticity of the house has been increasing in recent years, it has been released from these plywood and furniture. It has been pointed out that the filled formaldehyde may fill the room and cause harm to humans. In order to solve the problems associated with the release of formaldehyde, an adhesive using a thermosetting resin made of formaldehyde as a raw material contains a formaldehyde inhibitor such as ammonium carbonate, ammonium bicarbonate or guanidine carbonate as an additive. Has been proposed (see JP-A-5-287253).

[0003]

However, in the method using a formaldehyde inhibitor as an additive as described above, the amount of formaldehyde contained in the adhesive is reduced by increasing the amount of the formaldehyde inhibitor. However, on the contrary, there is a problem that the adhesive strength is reduced, the original plate is turned or shifted in the production of plywood or the like, and the water resistance of the obtained plywood is reduced.

On the other hand, as an adhesive containing no formaldehyde, an adhesive containing a neutralized product of a copolymer of isobutylene and maleic anhydride with a basic substance (Japanese Patent Publication No. 49-49)
-4792, JP-A-49-93447, etc.), an adhesive containing aqueous vinyl urethane,
Adhesives containing polyvinyl acetate have been proposed and are commercially available.However, compared to adhesives using thermosetting resin made from formaldehyde, the price, adhesion performance, workability during adhesion, etc. I am not satisfied with the point.

The present invention has been made in view of the above-mentioned problems of the prior art, and is an adhesive using a thermosetting resin made of formaldehyde as a raw material, which impairs the adhesive performance. It is another object of the present invention to provide an adhesive with reduced formaldehyde emission.

[0006]

According to the present invention, an object of the present invention is to provide a liquid I containing a thermosetting resin (A) using formaldehyde as a raw material;

[0007]

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A maleic anhydride unit represented by the formula (2)

[0009]

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And a maleimide unit represented by the formula (3)

[0011]

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(Wherein R ¹ , R ² and R ³ each represent a hydrogen atom, an alkyl group or a cycloalkyl group)
To provide an adhesive comprising a liquid II containing a neutralized product (B) of a copolymer comprising a structural unit represented by the formula (hereinafter abbreviated as maleic anhydride copolymer) with a basic substance: Solved by

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The thermosetting resin (A) using formaldehyde as a raw material constituting the adhesive of the present invention includes:
Conventionally, adhesives, particularly those used in wood adhesives, can be used, for example, phenols such as phenol and resorcinol and phenolic resins obtained by the reaction of formaldehyde, and urea obtained by the reaction of urea and formaldehyde. Resins, melamine resins obtained by the reaction of melamine and formaldehyde, and the like.

Further, in the neutralized product (B) of the maleic anhydride copolymer constituting the adhesive of the present invention with a basic substance, the formula (3) constituting the maleic anhydride copolymer as a raw material thereof is used. The structural unit represented is derived from a monomer represented by the following formula (4).

[0015]

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In the above formulas (3) and (4), R
Examples of the alkyl group represented by ¹ , R ² and R ³ include a methyl group, an ethyl group, a propyl group, an isopropyl group,
Examples thereof include -butyl group and n-octyl group, and those having 1 to 8 carbon atoms are preferable. Examples of the cycloalkyl group represented by R ¹ , R ² and R ³ include a cyclopropyl group and a cyclohexyl group, but those having 3 to 12 carbon atoms are preferred.

Here, examples of the monomer represented by the formula (4) include a linear or branched α-olefin. Examples of the monomer represented by the formula (4) include ethylene, propylene, 1-butene, isobutylene, 1-
Pentene, 2-methyl-1-butene, 1-hexene, 2
-Methyl-1-pentene, 3-methyl-1-pentene,
4-methyl-1-pentene, 2-ethyl-1-butene,
Examples thereof include diisobutylene, and among these, isobutylene is preferable. The monomer represented by the formula (4) is
They may be used alone or in combination of two or more.

The above maleic anhydride copolymer has various characteristics by changing the composition molar ratio of the maleic anhydride unit, the maleimide unit and the structural unit represented by the formula (3). Although the composition molar ratio of each structural unit is not necessarily limited, it is usually ([maleic anhydride unit] + [maleimide unit]): [structural unit represented by formula (3)] = 1: 1. It is. The molar ratio between the maleic anhydride unit and the maleimide unit is usually [maleic anhydride unit] / [maleimide unit] = 10/90 to 9
Although it is 0/10, in order to keep the amount of formaldehyde released from the obtained adhesive at a low level and to have excellent workability at the time of bonding, [maleic anhydride unit] /
[Maleimide unit] = 80/20 to 40/60 is preferable. The molar ratio between the maleic anhydride unit and the maleimide unit can be calculated from the infrared absorption spectrum, the measured value of the acid value, and the like.

The number average molecular weight of the maleic anhydride copolymer is usually from 1,000 to 500,000, but from the viewpoints of workability at the time of bonding and the strength of the cured product, it is 5,000. Preferably it is ~ 100,000. Incidentally, the above maleic anhydride copolymer, methyl vinyl ether, vinyl chloride, vinyl acetate, styrene, styrene sulfonic acid, within a range that does not impair the gist of the present invention,
(Meth) acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, methyl (meth) acrylate,
Other components such as ethyl (meth) acrylate, propyl (meth) acrylate, and butyl (meth) acrylate may be copolymerized.

The above maleic anhydride copolymer can be produced from maleic anhydride, maleimide and a monomer represented by the formula (4) (hereinafter, these will be abbreviated as raw material monomers) according to a conventional method. it can. For example, a raw material monomer is charged into a reaction vessel, and in a solvent such as acetone, benzene, or ethyl acetate, a solution polymerization method or the like is performed using a radical polymerization initiator such as benzoyl peroxide or 2,2′-azobisisobutyronitrile. It can be produced by copolymerization.

The maleic anhydride copolymer used in the present invention is a copolymer of maleic anhydride and a monomer represented by the formula (4), wherein a desired amount of the maleic anhydride unit is a maleimide unit. It can also be manufactured by converting to As a method of converting a maleic anhydride unit into a maleimide unit, for example, a maleimide anhydride unit is reacted with ammonia to obtain a monoamide unit of maleic acid, and then the ring is closed by heating to about 120 ° C. or more, thereby closing the maleimide unit. And the like.

Examples of the basic substance constituting the neutralized product (B) of the maleic anhydride copolymer with a basic substance include, for example, alkali metals such as sodium hydroxide, potassium hydroxide and lithium hydroxide or alkaline earth metals. Metal hydroxides; ammonia; amines such as methylamine, ethylamine, propylamine, dimethylamine, diethylamine, triethylamine, monoethanolamine, diethanolamine; alkali metal carbonates such as sodium carbonate and potassium carbonate; sodium acetate, acetic acid Acetates of alkali metals such as potassium; ammonium acetate; phosphates of alkali metals such as trisodium phosphate and the like. Among them, sodium hydroxide, potassium hydroxide or ammonia is preferred. These basic substances may be used alone or in combination of two or more.

The basic substance is used in such an amount that the degree of neutralization with respect to the maleic anhydride copolymer is preferably in the range of 0.1 to 0.9, more preferably 0.2 to 0.7. Here, the degree of neutralization indicates the ratio between the acid groups in the maleic anhydride copolymer and the basic substance, and the number of moles of the carboxyl groups in the maleic anhydride copolymer is x (mol); It is given by y / x when the amount of basic substance used is y (gram equivalent). The acid maleic anhydride unit in the maleic anhydride copolymer is calculated as corresponding to two carboxyl groups.

The reaction between the maleic anhydride copolymer and the basic substance can be carried out according to a conventional method, but is carried out in the presence of water to obtain a neutralized product (B) of the maleic anhydride copolymer as an aqueous solution. Is simple. In the adhesive of the present invention,
The amount of the neutralized product of maleic anhydride copolymer (B) is not particularly limited, but is usually 0.1 to 100 parts by weight based on 100 parts by weight of thermosetting resin (A) using formaldehyde as a raw material. 1000 parts by weight, preferably 1 to 100 parts by weight.
Parts by weight.

In the adhesive of the present invention, a curing agent for the curable resin (A) used in a conventional adhesive using the thermosetting resin (A) made of formaldehyde as a raw material is added. Is preferred. Examples of such a curing agent include ammonium chloride.

In the adhesive of the present invention, an adhesive using a copolymer of isobutylene and maleic anhydride is used for the purpose of improving the adhesive performance such as initial adhesive strength and normal adhesive strength and water resistance. Conventionally used polyvalent metal salts, polyvalent metal oxides and crosslinking agents may be added.
In addition, the metal mentioned here also includes a class of metals such as boron and silicon. As polyvalent metal salts, for example, calcium, magnesium, zinc, barium, aluminum,
Salts such as sulfates, nitrates, acetates, carbonates, chlorides, and silicates of divalent or higher-valent metals such as iron and nickel are exemplified.

As the polyvalent metal oxide, for example,
Magnesium, calcium, barium, zinc, aluminum, titanium, boron, silicon, bismuth, manganese,
Bentonite, silica, zeolite, clay, talc, satin white and the like, which are oxides of iron or nickel or their oxides,
Of these, oxides of silicon, calcium or aluminum are preferred. One of these polyvalent metal salts and polyvalent metal oxides may be used, or two or more thereof may be used in combination. The amount of the polyvalent metal salt and / or polyvalent metal oxide to be used is generally 10 to 2000 parts by weight, preferably 10 to 400 parts by weight, per 100 parts by weight of the neutralized product of maleic anhydride copolymer (B). Range of parts.

As the cross-linking agent, compounds having two or more epoxy groups in the molecule can be used. For example, glycerin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether Diglycidyl ethers of polyhydric alcohols such as glycidyl ether and polypropylene glycol diglycidyl ether;
Triglycidyl ethers of polyhydric alcohols such as glycerin triglycidyl ether; polyglycidyl ethers such as sorbitol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether; carboxyl groups such as diglycidyl succinate in the molecule An epoxy resin such as a glycidyl ester of a compound containing two or more compounds such as diglycidyl ether of bisphenol A, etc., which is uniformly dispersed in the liquid I or liquid II constituting the adhesive of the present invention is used. The amount of the crosslinking agent to be used is generally 0.1 to 500 parts by weight, preferably 10 to 200 parts by weight, based on 100 parts by weight of the neutralized maleic anhydride copolymer (B).

Further, the adhesive of the present invention can be added with an aqueous latex, if necessary, to improve adhesive properties such as normal adhesive strength and water resistant adhesive strength. Here, the aqueous latex means an aqueous emulsion of a natural or synthetic polymer. Specifically, styrene, styrene derivative, butadiene, acrylonitrile, chloroprene, isoprene, isobutene, acrylate, methacrylate, vinyl acetate, ethylene, vinyl chloride,
An aqueous emulsion of a polymer comprising one or more copolymerizable unsaturated monomers selected from vinylidene chloride or the like or a modified product thereof (for example, an aqueous emulsion of polyvinyl acetate, a styrene-butadiene copolymer) Latex, styrene-isoprene copolymer latex, ethylene-vinyl acetate copolymer latex), natural rubber latex, and the like. The amount of the aqueous latex used is such that the weight of the polymer in the aqueous latex is usually 1 per 100 parts by weight of the neutralized product of maleic anhydride copolymer (B).
000 parts by weight or less, preferably 10 to 500 parts by weight.

The adhesive of the present invention may be used, if necessary,
By adding fillers and extenders such as wood flour, flour, and barley glue, it is possible to adjust the viscosity and solid content of the adhesive. The adhesive of the present invention may further contain another formaldehyde-suppressing substance for the purpose of further reducing the amount of formaldehyde released. As such a formaldehyde-suppressing substance, those conventionally used as a formalin catcher in wood adhesives can be used, and examples thereof include urea, ammonium carbonate, ammonium bicarbonate, and guanidine carbonate. The amount of the formaldehyde-suppressing substance is usually 0.1 to 10 parts by weight based on 100 parts by weight of the thermosetting resin (A) using formaldehyde as a raw material.

The adhesive of the present invention comprises a liquid I containing a thermosetting resin (A) made from formaldehyde and a liquid II containing a neutralized maleic anhydride copolymer (B) with a basic substance. It is necessary to be composed of
Other components such as a curing agent, a polyvalent metal salt, a polyvalent metal oxide, a crosslinking agent, and a formaldehyde inhibitor for the thermosetting resin (A) may be added to either the liquid I or the liquid II. Alternatively, it may be added to both solution I and solution II. Further, these other components are prepared as a solution different from the solution I and the solution II, and the solution I and / or
Or you may mix with liquid II. In the present invention, as the liquid I, a thermosetting resin (A) using formaldehyde as a raw material and a conventional adhesive containing a curing agent for the thermosetting resin (A) as a constituent may be used. The adhesive of the present invention is usually prepared in the form of solution I or solution II by dissolving in a solvent such as water, and the solid content concentration at that time is generally 10 to 70% by weight of the entire adhesive, Preferably 20 to
60% by weight.

The adhesive of the present invention is usually used in a form in which one adhesive surface is coated with liquid I and the other adhesive surface is coated with liquid II. The adherends are bonded by pressing each other. In the above, when other components such as a polyvalent metal salt and a cross-linking agent are prepared as a solution different from the solution I and the solution II, before or after the application of the solution I and / or the solution II, Another solution can be separately applied to the adhesive surface.

The adhesive of the present invention is particularly suitable as an adhesive for wood for plywood, flash panels, particle boards, attached boards, fittings, furniture, sports equipment and other woodwork products. It can also be applied to the case of bonding cardboard, paper, cloth, and the like. Furthermore, the adhesive of the present invention not only bonds the same material among the adherends,
It is also effective when bonding two or more materials.

[0034]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. In Examples and Comparative Examples, various properties of the adhesive were evaluated by the following methods.

Initial adhesive strength (tensile shear strength) "5.5.9 Adhesive rising strength" specified in "α-olefin-maleic anhydride resin wood adhesive" of Japan Adhesive Industry Association Standard (JAI-5). According to the test method
The amount of the adhesive applied to the bonding surface of the Lauan plywood was adjusted so that the total amount of the liquid I and liquid II was 200 g / m ^2, and the pressing time was 10 minutes.
The tensile shear strength was measured for the test pieces prepared for minutes, 30 minutes, and 50 minutes.

Normal adhesive strength (compression shear strength) "5.5.1 Compressive shear strength" specified in "α-olefin-maleic anhydride resin wood adhesive" of the Japan Adhesive Industry Association Standard (JAI-5). The amount of adhesive applied to the bonding surface of birch was measured using liquid I and II
The compressive shear strength of a test piece prepared with a total of 250 g / m ² of the liquid was measured.

Water-resistant adhesive strength (compressive shear strength) "5.5.2 compressive shear adhesive strength" specified in "α-olefin-maleic anhydride resin wood adhesive" of the Japan Adhesive Industry Association Standard (JAI-5). (Water resistance) "
The compressive shear strength was measured for test pieces prepared with the adhesive amount applied to the bonding surface of the birch material being 250 g / m ² for liquid I and liquid II in total.

Warm water-resistant adhesive strength (compression shear strength) "5.5.3 compression shear adhesion" specified in "α-olefin-maleic anhydride resin wood adhesive" of Japan Adhesive Industry Association Standard (JAI-5). Strength (warm water resistance) ", the compressive shear strength was measured for a test piece prepared by setting the amount of the adhesive applied to the bonding surface of the birch wood to a total of 250 g / m ² of the liquid I and liquid II.

Preparation of Formaldehyde Emission Rate Test Specimen Two thick paper sheets of 15 cm long × 15 cm wide × 1 mm thick are prepared, and the combined surface of the thick paper is combined with liquid I and liquid II to give 250 g / m ^2. After applying uniformly at a predetermined ratio, two coated paper sheets are stuck together with their coated surfaces facing each other, then sandwiched with a press machine, and pressed under a condition of 20 to 25 ° C. and 10 kgf / cm ² for 10 minutes. And Quantitative determination of the amount of released formaldehyde A desiccator having the size specified in JIS R3503 and having a diameter of 12 c in which 300 cc of distilled water is placed at the bottom.
m, a crystal dish with a height of 6 cm is placed, a wire mesh is laid thereon, the test piece prepared above is placed thereon, the glass lid is completely closed with a glass cover, and then left at 20 to 25 ° C. for 24 hours. Formaldehyde released from the test piece is absorbed in distilled water to form a sample solution. The test solution obtained above was analyzed by colorimetry at a wavelength of 415 nm by the acetylacetone method, and the amount of formaldehyde released was calculated.

Reference Example 1 Copolymer of isobutylene and maleic anhydride [isobutylene unit: maleic anhydride unit = 1: 1 (molar ratio), number average molecular weight: about 60000, Isoban 04 (trade name),
[Kuraray Co., Ltd.] 10.0 g and 11 g of ammonia were charged into an autoclave having an internal volume of 300 cc, and 15 g was sealed.
By heating and stirring at 0 ° C. for 4 hours, a part of the maleic anhydride units in the above copolymer of isobutylene and maleic anhydride was converted to maleimide units. 100 ℃
After cooling, the pressure in the autoclave is returned to normal pressure,
Unreacted ammonia was removed by introducing nitrogen gas into the autoclave, and maleic anhydride copolymer 1 [isobutylene unit: maleic anhydride unit: maleimide unit = 1: 0.
55: 0.45 (molar ratio)].

Reference Example 2 The same operation as in Reference Example 1 was carried out except that the amount of ammonia gas used was changed to 5.5 g in Reference Example 1, to obtain a maleic anhydride copolymer 2 [isobutylene unit: maleic anhydride unit]. : Maleimide unit = 1: 0.8: 0.2 (molar ratio)].

Example 1 An aqueous solution of a urea / melamine resin [Oka Shinko Co., Ltd .: P
WP-513 (trade name), solid content concentration: 55% by weight] 1
40 g of flour and 1 g of ammonium chloride were added to 00 g, and the mixture was uniformly stirred to obtain a liquid I. Next, 10 g of the maleic anhydride copolymer 1 obtained in Reference Example 1 was added to an aqueous solution 2 containing 0.7 g of ammonia (an amount at which the degree of neutralization becomes 0.6).
The resultant was dissolved by heating in 5.7 g to obtain an aqueous solution (solid content concentration: 30% by weight) of a neutralized product of maleic anhydride copolymer 1 with ammonia. After cooling to room temperature, 20 g of an aqueous solution of the neutralized product of the maleic anhydride copolymer 1 was added with calcium carbonate 9
g and SBR latex (modified carboxylic acid: solid content concentration: 48%) were added and mixed uniformly, and then 2.4 g of glycerin triglycidyl ether was added and uniformly stirred to obtain a liquid II. Then immediately, liquid I and liquid II
The liquid was used as an adhesive in such a ratio that the ratio of the two became the liquid I / II = 1/1 (weight ratio), and various performances were evaluated according to the above methods. Table 1 shows the results.

Example 2 An adhesive was prepared in the same manner as in Example 1 except that the amount of glycerin triglycidyl ether used in the preparation of Solution II was changed to 4.8 g. The adhesion performance was evaluated. Table 1 shows the results.

Example 3 In Example 1, the ratio of solution I to solution II was changed to solution I / solution = 1.
An adhesive was prepared in the same manner as in Example 1 except that the adhesive was changed to / 2 (weight ratio), and various performances were evaluated. Table 1 shows the results.

Example 4 In Example 1, an adhesive was prepared in the same manner as in Example 1 except that 4.2 g of ammonium bicarbonate was added when preparing the solution I, and various performances were evaluated. Was. Table 1 shows the results.

Example 5 An aqueous solution of urea / melamine resin [P, manufactured by Oshika Shinko Co., Ltd .:
WP-513 (trade name)], 40 g of flour and 1 g of ammonium chloride were added to 100 g, and the mixture was uniformly stirred to obtain a liquid I. Next, 10 g of the maleic anhydride copolymer 2 obtained in Reference Example 2 was added to 0.45 g of ammonia (neutralization degree was 0.6%).
Is heated and dissolved in 24.5 g of an aqueous solution containing
An aqueous solution (solid content concentration: 30% by weight) of a neutralized product of maleic anhydride copolymer 2 with ammonia was obtained. After cooling to room temperature, 9 g of calcium carbonate and 18.8 g of SBR latex (modified carboxylic acid: solid content concentration: 48%) were added to 20 g of the aqueous solution of the neutralized product of maleic anhydride copolymer 2.
Was added and mixed uniformly, then 2.4 g of glycerin triglycidyl ether was added, and the mixture was stirred uniformly to obtain a liquid II. Immediately thereafter, the ratio of solution I and solution II was changed to solution I / II.
The liquid was used as an adhesive at a ratio of 1/1 (weight ratio), and various performances were evaluated according to the above methods. Table 1 shows the results.

Comparative Example 1 Using only the liquid I in Example 1, the adhesive surface (both sides) of the adherend was adjusted so that the coating amount was the same as the total amount of the liquids I and II specified in the above evaluation method. To perform adhesion, and various performances were evaluated according to the above methods. Table 1 shows the results.

Comparative Example 2 Using only the solution I in Example 4, the adhesive surface (both surfaces) of the adherend was adjusted so that the coating amount was the same as the total amount of the solution I and the solution II specified in the above evaluation method. To perform adhesion, and various performances were evaluated according to the above methods. Table 1 shows the results.

[0049]

[Table 1]

[0050]

According to the present invention, there is provided an adhesive which emits a small amount of formaldehyde and has good adhesive performance, while being an adhesive composed of a thermosetting resin using formaldehyde as a raw material. .

Claims (1)

[Claims] 1. A liquid I containing a thermosetting resin (A) using formaldehyde as a raw material, and a liquid of the formula (1): A maleic anhydride unit represented by the formula (2): And a maleimide unit represented by the following formula (3): (Wherein, R ¹ , R ² and R ³ each represent a hydrogen atom, an alkyl group or a cycloalkyl group) containing a neutralized product (B) of a copolymer comprising a structural unit represented by the following formula: An adhesive consisting of liquid II.