JPH1025330A - Compounded composition and adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition comprising a specific modified polyvinyl alcohol, an aqueous emulsion, etc., excellent in adhesive strength and water resistance and capable of giving adhesion products good in initial adhesivity. SOLUTION: This composition comprises (A) a modified polyvinyl alcohol having structural units of the formula [(n) is 1-20], (B) an aqueous emulsion and (C) a polyvalent isocyanate compound (e.g. polymethylenepolyphenylisocyanate). The component A is preferably obtained e.g. by saponifying the copolymer of a vinyl ester with a monomer such as 2-methyl-2-propen-1-ol. The component B is preferably obtained e.g. by emulsion- polymerizing a radically polymerizable ethylenic unsaturated monomer with a dienic monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to compositions and adhesives. More specifically, the present invention relates to a composition useful for various applications, particularly as an adhesive, and an adhesive comprising the composition and having excellent initial adhesiveness, adhesive strength, water resistance and the like.

[0002]

2. Description of the Related Art Unlike a conventional aminoplast adhesive, an adhesive containing a water-soluble polymer, an aqueous emulsion and an isocyanate compound as main components does not generate formalin and is compacted at room temperature for a relatively short time. Alone, extremely high adhesive strength and water resistance can be obtained, so that it has been awarded as an adhesive for wood (for example, JP-A-48-947).
No. 39, 50-69139). Further, as a similar adhesive, an aqueous adhesive composition comprising a copolymer emulsion of a hydroxyl group-containing monomer such as allyl alcohol, 2-hydroxyethyl acrylate, N-methylolated acrylamide and vinyl acetate, and a divalent isocyanate compound (JP-A-49-26346), a polyvinyl acetate emulsion using polyvinyl alcohol as a dispersant (protective colloid) and a water-resistant adhesive composition comprising a polyvalent isocyanate compound (JP-A-3-33178)
Publication). Additionally, the emulsion polymer comprises an emulsion polymer stabilized with polyvinyl alcohol, the first step producing a vinyl acetate copolymer having a glass transition temperature in the range of 10 to 40 ° C, and the second step comprising 50 to 120 ° C. Adhesives produced by a two-stage polymerization process comprising producing a methyl methacrylate copolymer having a glass transition temperature of 0 ° C., wherein the ratio of vinyl acetate copolymer to methyl methacrylate copolymer ranges from 10: 1 to 10: 6. (JP-A-2-302485). Under these circumstances, JIS has recently been established for wood adhesives comprising an aqueous polymer and an isocyanate compound.

However, with the expansion of the objects to be bonded,
In some cases, there is a need to further improve the current level of adhesive performance. Specifically, there is a case where a higher degree of durability is required as a structural adhesive, and a further improvement in initial adhesiveness is also required for individual applications. In the latter case, polyvinyl alcohol (hereinafter referred to as PVA)
When a water-based emulsion of a vinyl acetate-based resin having a dispersant (which may be abbreviated as above) is frequently used, the initial adhesion is improved, but the water resistance is not sufficient. In addition, polyvinyl alcohol, which is an aqueous polymer blended in this type of adhesive, also greatly contributes to the performance of the adhesive. Specifically, when PVA having completely saponified or acetoacetyl groups is used, although the water-resistant adhesiveness is improved, the low-temperature viscosity stability of the base agent composed of the aqueous emulsion and PVA and the low-temperature viscosity stability as compared with the case of using partially saponified PVA are improved. There was a problem that storage stability deteriorated. In addition, although the conventional adhesives as described above can exhibit a certain level of performance, initial adhesiveness, adhesive strength, and those having satisfactory performance in all respects of water resistance have not yet been developed. is the current situation.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art and to provide an adhesive having excellent adhesive strength and water resistance and good initial adhesiveness. It is.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the above-mentioned objects, and as a result, (A) modified polyvinyl alcohol having a structural unit represented by the following chemical formula 2,
The present inventors have found a composition comprising (B) an aqueous emulsion and (C) a polyvalent isocyanate compound, and have completed the present invention.

[0006]

Embedded image (N: integer of 1 to 20)

[0007] The present invention also provides an adhesive comprising the above composition. Further, the present invention also provides a wood product obtained by bonding with the above-mentioned adhesive.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION It is essential that a modified PVA used as a dispersant for an aqueous emulsion constituting the composition of the present invention has the structural unit of the above formula (2). N in the above structural unit is an integer of 1 to 20, preferably 1 to 5, and more preferably 1 or 2. Examples of the above structural units include 2-methyl-2-propen-1-ol, 3
And a structural unit derived from a monomer such as -methyl-3-buten-1-ol. The content of the structural unit of Chemical Formula 2 is preferably 0.1 to 20 mol%,
~ 15 mol% is more preferred. The modified PVA constituting the composition of the present invention is obtained by saponifying a copolymer of a vinyl ester and the above monomer. Examples of the vinyl ester include vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate and the like, with vinyl acetate being preferred.

The modified PVA of the present invention may be a copolymer of an ethylenically unsaturated monomer as long as the effects of the present invention are not impaired. Such ethylenically unsaturated monomers include, for example, ethylene, propylene, isobutene, acrylic acid, methacrylic acid, (phthalic anhydride),
Maleic acid, (anhydrous) itaconic acid, acrylonitrile,
Methacrylonitrile, acrylamide, methacrylamide, trimethyl- (3-acrylamido-3-dimethylpropyl) -ammonium chloride, acrylamide-
2-methylpropanesulfonic acid and its sodium salt,
Ethyl vinyl ether, butyl vinyl ether, N-vinyl pyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, tetrafluoroethylene, sodium vinyl sulfonate, sodium allyl sulfonate, and the like. Further, in the presence of a thiol compound such as thiolacetic acid and mercaptopropionic acid, a vinyl ester-based monomer such as vinyl acetate and a monomer giving the structural unit represented by the above formula 2 are copolymerized,
A terminal-modified PVA obtained by saponifying it can also be used. The modified PVA of the present invention is most preferably modified only by the structural unit of the above formula (2). Modified PV
When the modified PVA of the present invention is further modified with a comonomer giving a structural unit other than the structural unit represented by Chemical Formula 2 in view of the water solubility or dispersibility of A, the content of the comonomer is less than 5.0 mol%. Is preferably less than 3.0 mol%, and more preferably less than 2.0 mol%. The saponification degree of the modified PVA is preferably 50 mol% or more, more preferably 60 mol% or more, and further preferably 70 mol% or more. The degree of polymerization of the PVA is 10
The range is preferably from 0 to 8000, and more preferably from 200 to 2,000.

The aqueous emulsion constituting the composition of the present invention may be a water-soluble polymer such as anionic, cationic, amphoteric or nonionic low-molecular surfactant known as a dispersant, or various polyvinyl alcohols or hydroxyethyl cellulose. (Emulsion polymerization type aqueous emulsions and polyurethane emulsions obtained by emulsion polymerization of radically polymerizable ethylenically unsaturated monomers and diene-based monomers in an aqueous solution containing one or more protective colloids) The aqueous emulsion obtained by the post-emulsification method of the polymer to be used is used alone or in combination of two or more.

The ethylenically unsaturated monomers constituting the emulsion polymerization type aqueous emulsion dispersoid of the present invention include olefins such as ethylene, propylene and isobutene, vinyl chloride, vinylidene chloride, vinyl fluoride and vinylidene fluoride. Halogenated olefins, vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate, vinyl esters such as vinyl pivalate, acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-acrylate Acrylates such as propyl, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, hydroxypropyltrimethylammonium acrylate, and methacrylic acid , Methyl methacrylate, ethyl methacrylate, n- propyl methacrylate i- propyl, n- butyl methacrylate, i- butyl methacrylate, t- butyl methacrylate, 2
Methacrylates such as ethylhexyl, dodecyl methacrylate, octadecyl methacrylate, hydroxypropyltrimethylammonium methacrylate, acrylamide, methacrylamide, N-methylolacrylamide, N, N-dimethylacrylamide, acrylamide-2-methylpropanesulfonic acid And its sodium salt acrylamide, trimethyl-
(3-acrylamido-3-dimethylpropyl) -ammonium chloride, 3-acrylamidopropyltrimethylammonium chloride, 3-methacrylamidopropyltrimethylammonium chloride, N-methylacrylamide, N-ethylacrylamide, diacetoneacrylamide, acrylonitrile, methacrylonitrile Allyl compounds such as allyl acetate, allyl chloride, etc., styrene monomers such as styrene, α-methylstyrene, P-methylstyrenesulfonic acid and its sodium and potassium salts, and others such as N-vinylpyrrolidone Monomers. Examples of the diene-based monomer include butadiene, isoprene, and chloroprene.

In carrying out emulsion polymerization for obtaining the aqueous emulsion of the present invention, the above-mentioned monomer is added temporarily or continuously in the presence of water, the above-mentioned dispersant, and a polymerization initiator. A usual emulsion polymerization method such as heating and stirring can be performed, and a method in which a monomer is previously mixed and emulsified with a dispersant aqueous solution can be continuously added. The amount of the dispersant used in the present invention is not particularly limited, but is usually 0.2 to 5 based on 100 parts by weight of the monomer.
0 parts by weight, preferably 0.5 to 20 parts by weight. When the amount of the dispersant is less than 0.2 part by weight, the polymerization stability is reduced, and when the amount is more than 50 parts by weight, the viscosity becomes too high.

The polymerization initiator is not particularly restricted but includes, for example, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, 2,2′-azobis (2-amidinopropane) dihydrochloride, Redox system in which cumene hydroperoxide, benzoyl peroxide, isopropylbenzene peroxide or the like is used alone or in combination with a reducing agent such as sodium bisulfite, tartaric acid, L-ascorbic acid, sodium formaldehyde sulfoxylate, and ferrous sulfate. .

The composition of the present invention comprises (A) a modified PVA,
It comprises (B) an aqueous emulsion and a polyvalent isocyanate compound as the component (C). Here, (C) the polyvalent isocyanate compound has two or more isocyanate groups in the molecule, and is, for example, tolylene diisocyanate (TDI); hydrogenated TDI; Triphenylmethane triisocyanate; methylenebisdiphenyl isocyanate (MDI); hydrogenated MDI; polymerized MDI; hexamethylene diisocyanate; xylylene diisocyanate;
4,4-dicyclohexylmethane diisocyanate; isophorone diisocyanate, and the like. In addition, a prepolymer having a terminal group having an isocyanate group, which is previously polymerized with an excess of polyisocyanate in a polyol, may be used.

The composition of the present invention comprises (A) a modified PVA and (B) a main ingredient mainly composed of an aqueous emulsion, and (C)
It comprises a polyvalent isocyanate compound. Here, the mixing ratio of the (A) modified PVA and the (B) aqueous emulsion in the main agent is (A) / (B) = 99/1 to 5 / in solid content ratio.
95 (weight ratio), preferably 95/5
The range of 10/90 is more preferred. The blending of the polyvalent isocyanate compound (C) with respect to the main component consisting of (A) and (B) may be appropriately selected according to various situations. However, the preferred mixing ratios are (A) and (B)
(C) 1 to 200 parts by weight, particularly preferably 5 to 100 parts by weight, per 100 parts by weight (in terms of solid content) of the blend of the above. If the amount of the polyvalent isocyanate compound is less than this range, the adhesive strength and water resistance will be low, and if it exceeds this range, the pot life after blending the polyvalent isocyanate will be short and not practical.

In the composition of the present invention, if necessary, starch, modified starch, oxidized starch, sodium alginate, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, maleic anhydride-
Water-soluble polymer compounds such as isobutene copolymer, maleic anhydride-styrene copolymer, maleic anhydride-methyl vinyl ether copolymer, urea-formalin resin, urea-
Thermosetting resins generally used as adhesives, such as melamine-formalin resin and phenol-formalin resin, can also be used as appropriate. Further, the composition of the present invention includes clay, kaolin, talc, calcium carbonate, fillers such as wood flour, fillers such as flour, boric acid, reaction accelerators such as aluminum sulfate, pigments such as titanium oxide or other Various additives such as a preservative and a rust inhibitor can be appropriately added as necessary.

The adhesive of the present invention is used for bonding various adherends, and is particularly suitable for bonding wood. The application amount may be appropriately selected according to various situations. Examples of the coating method include coating with a brush and coating with a roll. Drying after applying the adhesive is carried out from room temperature to 20
Heat drying at 0 ° C. may be used, but the adhesive of the present invention exhibits sufficient adhesive strength even when dried at room temperature. The feature of the adhesive of the present invention is that the storage stability of the main agent is excellent,
This is because both the initial adhesion and the water resistance in boiling water are excellent. The drying time after applying the adhesive is preferably about 30 minutes to 5 hours. The drying of the adhesive is preferably performed in a pressed state. The pressure at the time of pressing is selected in the range of 5 to ²⁰ kg / cm ^{2. When} hard wood is used as the adherend, the pressure is preferably higher, and soft wood is used as the adherend. In such a case, a pressure high enough not to break the wood is preferable.

The wood product of the present invention is a wood product bonded by the above-mentioned adhesive, and includes glued laminated wood, furniture and the like. The type of wood in the wood product is not particularly limited, and examples include hippo, hemlock, cedar, lauan, zelkova, perpoch, rubber, oak, and the like.

[0019]

The present invention will be described more specifically below with reference to examples and comparative examples. In Examples and Comparative Examples,
“Parts” and “%” are based on weight unless otherwise specified. Example 1 Content of 3-methyl-3-buten-1-ol unit
0 mol% of modified PVA (PVA-1: polymerization degree 1200,
35 parts of a 15% aqueous solution having a saponification degree of 98.0 mol%) and 65 parts of calcium carbonate were mixed, and 100 parts of an ethylene-vinyl acetate copolymer emulsion (OM-4200, solid content concentration 55%, manufactured by Kuraray) was added thereto. In addition, a main ingredient was prepared. In addition, polymethylene polyphenyl isocyanate (manufactured by Nippon Polyurethane Co., trade name: Millionate MR-10)
0) was added in an amount of 30 parts to prepare a composition. Using this, a test was performed under the following conditions. The results are shown in Tables 1 and 2.

[Test conditions] Adhesion test An adhesion test was performed using the above composition under the following conditions. Substrate: birch / birch (masa) water content 8% Application amount: 250 g / m ² (both sides coated) Deposition time: 1 minute Pressing conditions: 20 ° C., 24 hours, pressure 10 kg / cm
² (Normal strength, repeated boiling test specimens only) Measure compression shear adhesive strength according to JIS K-6852 Normal strength: Measured as it is after curing for 7 days at 20 ° C Repeated boiling: Test specimen after curing for 7 days at 20 ° C Was immersed in boiling water for 4 hours, dried in air at 60 ° C. for 20 hours, further immersed in boiling water for 4 hours, immersed in water at room temperature until cooled, and subjected to a test in a wet state. . Initial adhesion: 10 kg / cm ² at 20 ° C after bonding
Pressure for 10 minutes and immediately measure the compression shear adhesive strength

Example 2 Content of 3-methyl-3-buten-1-ol unit
35 parts of a 15% aqueous solution of 0 mol% of modified PVA (PVA-2: polymerization degree 500, saponification degree 98.0 mol%) and 65 parts of calcium carbonate were mixed, and the mixture was mixed with styrene-butadiene copolymer emulsion (DL- 612, solid content concentration 50
%, Manufactured by Asahi Kasei). Then, 30 parts of polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., Ltd., trade name: Millionate MR-100) was added thereto to prepare a composition. Using this, Example 1
The test was performed in the same manner as in the above. The results are shown in Tables 1 and 2.

Example 3 In a glass polymerization vessel equipped with a stirrer, a nitrogen inlet, and a thermometer, PVA having a mercapto group at a terminal (polymerization degree: 5
00, degree of saponification 88.2 mol%, content of mercapto group 4.5
× 10 ^-5 mol / g-PVA) 5 parts and ion-exchanged water 100
The mixture was heated and dissolved. After cooling, the pH was adjusted to 3.0 with sulfuric acid, and then the temperature was raised to 70 ° C. while performing nitrogen bubbling. With stirring at 150 rpm, 10 parts of methyl methacrylate and 10 parts of n-butyl acrylate were added, and 10 parts of a 1% aqueous solution of potassium persulfate was further added to initiate polymerization. One hour after the start of the polymerization, methyl methacrylate 40
Parts, 38 parts of n-butyl acrylate and 2 parts of hydroxyethyl methacrylate were uniformly dropped over 2 hours. After completion of the dropwise addition, the temperature was raised to 80 ° C., and the mixture was left for 1 hour. Methyl methacrylate-n-acrylic acid having a solid content of 48.5%
A butyl-hydroxyethyl methacrylate copolymer emulsion (acrylic Em) was obtained. 3-methyl-3-
Modified P having a butene-1-ol unit content of 1.0 mol%
35 parts of a 15% aqueous solution of VA (PVA-3: polymerization degree 1400, saponification degree 92.0 mol%) and 65 parts of calcium carbonate were mixed, and the above-mentioned acryl Em was added thereto to prepare a main ingredient. In addition, polymethylene polyphenyl isocyanate (manufactured by Nippon Polyurethane Co., trade name: Millionate MR-
100) was added to prepare a composition. Using this, a test was performed in the same manner as in Example 1. Table 1 shows the results
And Table 2.

Comparative Example 1 In Example 1, unmodified PVA was used instead of PVA-1.
(PVA-4: polymerization degree 1700, saponification degree 98.5 mol%) It tested like Example 1 except using 15% aqueous solution. The results are shown in Tables 1 and 2.

Comparative Example 2 In Example 1, unmodified PVA was used instead of PVA-1.
The test was conducted in the same manner as in Example 1 except that a 15% aqueous solution (PVA-5: polymerization degree 1700, saponification degree 88.2 mol%) was used. The results are shown in Tables 1 and 2.

[0025]

[Table 1]

PVA-1: 3-methyl-3-butene-1
-Contents of all units 3.0 mol% Degree of polymerization 1200, Degree of saponification 98.0 mol% PVA-2: Content of 3-methyl-3-buten-1-ol units 6.0 mol% Degree of polymerization 500, Degree of saponification 98.0 mol% PVA-3: content of 3-methyl-3-buten-1-ol unit 1.0 mol% Degree of polymerization 1400, degree of saponification 92.0 mol% PVA-4: unmodified PVA ( PVA-5: unmodified PVA (polymerization degree: 1700, saponification degree: 88.2 mol%) OM-4200: ethylene-vinyl acetate copolymer emulsion (solid content: 55%) DL- 612: Styrene butadiene copolymer emulsion (50% solid content) Acrylic Em: Methyl methacrylate / n-acrylic acid
Butyl / hydroxyethyl methacrylate copolymer emulsion (solid content 48.5%)

[0027]

[Table 2]

[0028]

The composition of the present invention is used for various applications including adhesives. In particular, when used as an adhesive, the initial adhesive strength is excellent, and the adhesive strength and water resistance are dramatically improved. The adhesive of the present invention can be applied to a case where various kinds of materials are adhered to each other, and can be particularly suitably used as an adhesive for wood. In addition to the adhesion between woods, it can be used for adhesion between wood and paper, textiles, inorganic plates, films and the like. Furthermore, the composition of the present invention can be effectively used as an inorganic binder, an inorganic plate, or a base paint such as a wood panel by utilizing a film having excellent water resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location C09J 175/04 JFC C09J 175/04 JFC

Claims (3)

[Claims] 1. A composition comprising (A) a modified polyvinyl alcohol having a structural unit represented by the following chemical formula 1, (B) an aqueous emulsion, and (C) a polyvalent isocyanate compound. Embedded image (N: integer of 1 to 20) 2. An adhesive comprising the composition according to claim 1. 3. A wood product obtained by bonding with the adhesive according to claim 2.