JP2006057002A - Aqueous adhesive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop an aqueous adhesive having good balance in initial adhesive strength, heat resistance and contact property, because an aqueous contact type adhesive is strongly required from problems of toxicity, environmental contamination and disaster prevention involving solvents, though a chloroprene rubber-based adhesive has widely been used because of wide adhesion to various adherends and good heat resistance and initial adhesive strength. <P>SOLUTION: The aqueous adhesive composition is obtained by formulating polychloroprene latex with an adhesiveness-imparting resin emulsion having ≥100°C softening point and a dibasic acid dimethyl ester. The aqueous adhesive composition can improve performances such as initial adhesive strength, heat resistance and a contact property. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

（Ｒ１、Ｒ２は水素原子および炭素数１〜６の直鎖若しくは分岐のアルキル基であつて、Ｍは炭素数１〜１０のアルキレン基又はビニレン基を示す。） The present invention is an aqueous adhesive composition having excellent heat resistance and contact properties, and more specifically, heat resistance and contact properties obtained by blending polycloprene latex, tackifying resin emulsion, and dibasic acid dimethyl ester represented by the following formula (1). It is related with the water-based adhesive composition which is excellent in.

(R1 and R2 are a hydrogen atom and a linear or branched alkyl group having 1 to 6 carbon atoms, and M represents an alkylene group or vinylene group having 1 to 10 carbon atoms.)

Conventionally, adhesives based on polychloroprene have excellent adhesive strength due to high cohesion due to the crystallinity of polychloroprene, and a wide range of applications in conjunction with wide adherend suitability due to the combined effect of tackifying resins Has been used.
However, since an organic solvent is used, an aqueous contact type adhesive based on chloroprene latex has been studied because an aqueous type is strongly demanded due to anxiety of toxicity, environmental pollution, and disaster prevention management problems.

Regarding the water-based type, various studies have been made in the past with the aim of achieving a balance of initial adhesive strength, heat resistance, contactability, storage stability, adhesiveness and the like as practical performance.
For example, conventionally, increasing the molecular weight in order to improve heat resistance will cause gel content (toluene insoluble content), resulting in sacrificing contact properties. In the range without gel content (toluene insoluble content) In order to achieve both heat resistance and contact properties, such as inability to ensure heat resistance because it has not been made, there is a problem, so in JP-A-9-3423, polychloroprene latex that does not contain a gel component (toluene insoluble component) Attempts have been made to ensure a high degree of contact and adhesion by the cross-linking reaction between carboxyl groups and metal oxides while using the base as a base, but the cross-linking reaction proceeds during storage, making it virtually impossible to use. was there.
In JP-A-11-158326, the gel content (toluene insoluble content) and the weight average molecular weight are controlled to improve the initial adhesive strength, normal adhesive strength, heat resistance and the like. A surfactant such as a mold is used. Polychloroprene latex synthesized using a surfactant as an emulsifier in this way is more cohesive, compounding stability, composite adhesive strength, and heat resistance than polychloroprene latex synthesized using PVA as a protective colloid. It is inferior and cannot be applied to a building material application which is also an application of the aqueous adhesive composition according to the present invention.
In addition, in JP 2000-8012 A, in addition to the softening point of the added resin being 100 ° C. or less, the carboxyl group of the tackifying resin is blended while being neutralized and dissolved with an alkali, so that the heat resistance is insufficient, There were problems such as poor water resistance and a limited tackifying effect such as poor compatibility with polychloroprene latex.

  In terms of practical performance, when the gel content (toluene insoluble content) of the polychloroprene latex is 40% by weight or less, the adhesive strength, heat resistance, and shear strength decrease, and the gel content (toluene insoluble content) exceeds 60% by weight. There is a tendency for initial adhesive strength and contact strength to decrease. Because of this situation, it is necessary to control the gel content (toluene insoluble content) in a convenient range.

Japanese Patent Laid-Open No. 9-3423 JP-A-11-158326 JP 2000-8012 A

The present invention intends to realize an aqueous adhesive composition having a good balance of the above-described problems, that is, initial adhesive strength, heat resistance, contactability, storage stability, adhesiveness and the like.

（Ｒ１、Ｒ２は水素原子および炭素数１〜６の直鎖若しくは分岐のアルキル基であつて、Ｍは炭素数１〜１０のアルキレン基又はビニレン基を示す。） The present invention is intended to realize a contact-type aqueous adhesive composition having a good balance of initial adhesive strength, heat resistance, contactability, storage stability, adhesiveness, etc., and polychloroprene latex (hereinafter abbreviated as CR). The above problem could be solved by blending a tackifier resin emulsion having a softening point of 100 ° C. or higher and a dibasic acid dimethyl ester represented by the following formula (1).

(R1 and R2 are a hydrogen atom and a linear or branched alkyl group having 1 to 6 carbon atoms, and M represents an alkylene group or vinylene group having 1 to 10 carbon atoms.)

（Ｒ１、Ｒ２は水素原子および炭素数１〜６の直鎖若しくは分岐のアルキル基であつて、Ｍは炭素数１〜１０のアルキレン基又はビニレン基を示す。） Since the water-based adhesive composition according to the present invention contains CR, a tackifying resin emulsion having a softening point of 100 ° C. or higher, and a dibasic acid dimethyl ester represented by the following formula (1), the initial adhesive strength It has a good balance of heat resistance, contact properties, storage stability, adhesiveness, etc., and can be used for various applications.

(R1 and R2 are a hydrogen atom and a linear or branched alkyl group having 1 to 6 carbon atoms, and M represents an alkylene group or vinylene group having 1 to 10 carbon atoms.)

Hereinafter, the present invention will be described in detail.
The CR according to the present invention is obtained by emulsion polymerization of 2-chloro-1,3-butadiene or a monomer copolymerizable therewith. Dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, various (meth) acrylic esters, acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid And ethylenically unsaturated carboxylic acids such as gluconic acid, and two or more kinds of these copolymerizable monomers may be used.
In addition, CR copolymerized with ethylenically unsaturated carboxylic acid is convenient for high adhesion by reaction with hydroxyl groups present in wood or the like, or adhesion to polar adherends such as metals.

It is necessary to use a CR whose gel content (toluene insoluble content) is highly controlled, and it is preferably 40% by weight to 60% by weight.
The gel content (toluene insoluble content) can be controlled by controlling the use and use amount of the chain transfer agent, the polymerization temperature and the polymerization rate.
The gel content (toluene insoluble content) is measured by the following method.
[Gel content (toluene insoluble content)] A latex sample was freeze-dried and precisely weighed to A, dissolved in toluene (adjusted to 0.6%) at 23 ° C. for 20 hours, and then centrifuged. The gel (toluene insoluble matter) is separated using a 200 mesh wire net. The gel content (toluene insoluble content) is air-dried and then dried in an atmosphere at 110 ° C. for 1 hour and precisely weighed to give B. The gel content (toluene insoluble content) is calculated according to the following formula. Gel content (toluene insoluble content) = B / A × 100 (%)

In general, water-soluble polymers such as polyvinyl alcohol and hydroxymethyl cellulose, anionic, nonionic, and cationic surfactants are used as emulsifiers for emulsion polymerization. Emulsion polymerization in the presence of an alcohol and a copolymer thereof is preferable because it has various advantages such as wettability to paper / woody base material, high cohesive strength, heat resistance and blending stability.
It is also possible to use a water-soluble polymer having a protective colloid action together with polyvinyl alcohol, and examples thereof include polyvinyl ether and a copolymer thereof, polyvinyl pyrrolidone and a copolymer thereof, and a cellulose derivative. Moreover, you may use together with polyvinyl alcohol as needed, such as above-mentioned surfactant and fatty-acid alkanolamide.

The polyvinyl alcohol used in the present invention is not particularly limited, but preferably has a saponification degree of 60 to 98 mol% and a polymerization degree of 200 to 3000, more preferably 75 to 95 mol%. Those having a degree of 200 to 700 can carry out the polymerization operation stably, have good latex stability, and obtain a stable latex having a high concentration.
Moreover, the addition amount of polyvinyl alcohol is preferably 0.5 to 10 parts by weight per 100 parts by weight in total of chloroprene or chloroprene and other copolymers. When the amount is less than 0.5 part by weight, the emulsifying power is insufficient, and aggregates are generated in the polymerization reaction process. On the other hand, if the amount exceeds 10 parts by weight, viscosity is increased in the course of the polymerization reaction, and stirring is hindered. Moreover, there exists a tendency for water resistance to fall, and it is not preferable.

As the polymerization initiator, organic peroxides such as potassium persulfate and tert-butyl hydroperoxide are used, or reducing substances such as sodium sulfite, sodium hydrogen sulfite, sodium hydrosulfite and Rongalite are used in combination. The emulsion polymerization can be advanced.
The polymerization temperature is preferably 30 to 50 ° C. in order to proceed smoothly and safely.
The type of chain transfer agent is not particularly limited, and those usually used for emulsion polymerization of chloroprene can be used, but xanthates or mercaptans are preferred.
The polymerization terminator is not particularly limited, and for example, 2,6-tertiarybutyl-4-methylphenol, phenothiazine, hydroxyamine and the like can be used. The final polymerization rate can be arbitrarily adjusted in order to control the properties of the target chloroprene copolymer.

Tackifying resin emulsions include modified rosin resin, polymerized rosin resin, α-pinene resin, β-pinene resin, terpene resin, terpene phenol resin, alkylphenol resin, styrene resin, xylene resin, coumarone resin, coumarone indene resin, petroleum Type hydrocarbon resins and the like, and these emulsions can be added alone or in combination. Among them, those having a softening point of 100 ° C. or higher are preferable in order to ensure the heat resistance of the adhesive layer, and those having a softening point of 100 ° C. or lower are not suitable because the heat resistance is lowered.
Moreover, 10-70 weight part is suitable for the mixture ratio of tackifying resin emulsion with respect to CR solid content of 100 weight part. If it is 10 parts by weight or less, the adhesion to the adherend cannot be secured, and the tackifying effect is not sufficient, which is not preferable. If it is 70 parts by weight or more, the adhesive force is lowered, which is not preferable.

  In order to emulsify the tackifying resin, a solution obtained by dissolving in a solvent such as toluene is emulsified and dispersed in water using an emulsifier, and then (i) a method in which the solvent is removed by volatilization while heating under reduced pressure. , (B) a method of emulsifying finely pulverized fine particles, (c) a method of emulsifying an emulsifier after heating in a pressure kettle above the softening point and adding hot water to remove the phase, and then phase inversion emulsification. The method (a) or (c) is preferable for finishing finer particles.

において、Ｒ１、Ｒ２は水素原子および炭素数１〜６の直鎖若しくは分岐のアルキル基であつて、例えばメチル基、エチル基、イソプロピル基、ブチル基、ターシャリブチル基、ヘキシル基、シクロヘキシル基等が挙げられる。Ｍは炭素数１〜１０のアルキレン基又はビニレン基である。このような構造の化合物としては、マロン酸、コハク酸、グルタル酸、アジピン酸、ピメノン酸、スベリン酸、アゼライン酸、セバシン酸、マレイン酸、フマル酸、イタコン酸、メサコン酸、ジヒドロムコン酸、グルタコン酸等の酸及びそれぞれの酸のモノエステル及びジエステルであってもよい。
具体例として、コハク酸ジメチル、アジピン酸ジメチル、グルタル酸ジメチル、アジピン酸ジブチル、アジピン酸ジメチル、アジピン酸ジブチル、アジピン酸ジシクロヘキシル、アゼライン酸ジブチル、イタコン酸ジメチル、アゼライン酸ジブチルなどがあり、好ましくは、コハク酸ジメチル、アジピン酸ジメチル、グルタル酸ジメチルが挙げられ、単独若しくは２種類以上の混合物として使用される。 なお、工業的にはアジピン酸ジメチル、コハク酸ジメチル、グルタル酸ジメチルの混合物であるＤＢＥ（組成範囲：アジピン酸ジメチル１０〜２５重量％、グルタル酸ジメチル５５〜６５重量％、コハク酸ジメチル１５〜２５重量％）がインベスタジャパン社から市販され、高溶解力、流動性、低環境負荷と低毒性、低臭、低揮発性などの特徴を持つことから、本発明の水性接着剤組成物への使用に適している。
これらは、ＣＲ及び粘着付与樹脂の軟化並びに被着体との接着性を向上するために配合されるもので、いずれか１種類若しくは２種類以上が配合される。これらは、ＣＲの固形分１００重量部当たり０．１〜５重量部の範囲で配合されることが好ましい。０．１重量部以下では接着層の軟化作用が得られないため好ましくない。一方、５重量部以上では軟化による耐熱性低下が観察されるため、ゲル分（トルエン不溶分）を制御されたＣＲを使用する効果が低下するため適さない。 Dibasic acid dimethyl ester is represented by the following formula (1):

R1 and R2 are a hydrogen atom and a linear or branched alkyl group having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, an isopropyl group, a butyl group, a tertiary butyl group, a hexyl group, a cyclohexyl group, etc. Is mentioned. M is a C1-C10 alkylene group or vinylene group. Examples of such compounds include malonic acid, succinic acid, glutaric acid, adipic acid, pimenonic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, itaconic acid, mesaconic acid, dihydromuconic acid, glutaconic acid. Etc. and monoesters and diesters of the respective acids.
Specific examples include dimethyl succinate, dimethyl adipate, dimethyl glutarate, dibutyl adipate, dimethyl adipate, dibutyl adipate, dicyclohexyl adipate, dibutyl azelate, dimethyl itaconate, dibutyl azelate, preferably Examples thereof include dimethyl succinate, dimethyl adipate, and dimethyl glutarate, and are used alone or as a mixture of two or more. Industrially, DBE (composition range: dimethyl adipate 10 to 25% by weight, dimethyl glutarate 55 to 65% by weight, dimethyl succinate 15 to 25%) is a mixture of dimethyl adipate, dimethyl succinate and dimethyl glutarate. % By weight) is commercially available from Investa Japan, and has characteristics such as high solubility, fluidity, low environmental load and low toxicity, low odor, and low volatility. Suitable for use.
These are blended to soften the CR and tackifying resin and to improve the adhesion to the adherend, and any one or two or more are blended. These are preferably blended in the range of 0.1 to 5 parts by weight per 100 parts by weight of CR solids. The amount of 0.1 parts by weight or less is not preferable because the softening action of the adhesive layer cannot be obtained. On the other hand, if the amount is 5 parts by weight or more, a heat resistance decrease due to softening is observed, so that the effect of using CR with controlled gel content (toluene insoluble content) decreases, which is not suitable.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.
In addition, a weight part is described as a part.
Examples 1-4
OL-0453 which is CR having a gel content (toluene insoluble content) of 54% by weight (manufactured by Denki Kagaku Kogyo Co., Ltd., solid content 55%, pH 7), OL-0460 which is CR having a gel content (toluene insoluble content) of 43% by weight. (Electrochemical Industry Co., Ltd., solid content 55%, pH 7), gel content (toluene insoluble content) 47 wt% CR, OL-0460-2 (Electrochemical Industry Co., Ltd., solid content 55%, pH 7) OL-0524 (manufactured by Denki Kagaku Kogyo Co., Ltd., solid content 55%, pH 7) having a gel content (toluene insoluble content) of 57% by weight, a polymerized rosin ester-based tackifier resin emulsion KNS120 (softening point 120 ° C.) Arakawa Chemical Industries, Ltd., solid content 55%, pH 5) and DBE (manufactured by Invest Japan) were blended as shown in Table 1 to prepare aqueous adhesive compositions of Examples 1-4.
Table 1 shows the contact ratio and heat resistance of the water-based adhesive composition of each example.

Comparative Examples 1-8
OL-0442 (CR, having a gel content (toluene insoluble content) of 10% by weight, CR, OL-0478 (manufactured by Denki Kagaku Kogyo Co., Ltd., solid content 55%, pH 7), and CR content having a gel content (toluene insoluble content) of 17% by weight. (Electrochemical Industry Co., Ltd., solid content 55%, pH 7), gel content (toluene insoluble content) 28 wt% CR, OL-0413 (Electrochemical Industry Co., Ltd., solid content 55%, pH 7), gel content (Toluene insoluble content) OL-0460-1 which is CR of 37% by weight (manufactured by Denki Kagaku Kogyo Co., Ltd., solid content 55%, pH 7), gel content (toluene insoluble content) OL-0525 which is CR of 66% by weight (Electrochemical Industry Co., Ltd., solid content 55%, pH 7), gel content (toluene insoluble content) 54 wt% CR, OL-0453 (Electrochemical Industry Co., Ltd., solid content 55%, pH 7), softening point Polymerized rosin ester tackifier resin emulsion KNS120 (Arakawa Chemical Industries, solid content 50%, pH 5) at 120 ° C., rosin ester tackifier resin emulsion KNS75 (Arakawa Chemical Industries, Ltd.) with a softening point of 75 ° C. , Solid content 50%, pH 5), DBE (manufactured by Investa Japan) and plasticizer CS-12 (manufactured by Chisso Corporation, 2,2,4-trimethylpentanediol-1,3-monoisobutyrate) Were mixed as shown in Table 2 to prepare aqueous adhesive compositions of Comparative Examples 1-8. Table 2 shows the contact ratio and heat resistance of the aqueous adhesive compositions of the comparative examples.

試験・評価方法
１．コンタクト性：被着体としてラワン合板（タイプΙ、１２ｍｍ厚）同士を使用し、実施例、比較例の水性着剤組成物を両面均一に１００ｇ／ｍ^２塗布したのち、５℃・湿度９０％の環境下において、２時間乾燥後に０．２ＭＰａの圧力で貼り合わせたときのコンタクト率を測定する。 ○：５０％以上、△：３０〜５０％、×：３０％以下
２．耐熱性：被着体としてラワン合板（タイプＩ、５．５ｍｍ厚）とメラミン樹脂化粧板（１ｍｍ厚）とを使用し、実施例、比較例の水性接着剤組成物を両面に１００ｇ／ｍ^２塗布したのち、２３℃で３０分間乾燥後に０．２ＭＰａの圧力で接着し、２３℃で２４時間養生後、５０℃雰囲気下で５００ｇ荷重を掛け落下するまでの時間（分）を測定する。

Test / Evaluation Method Contactability: Lauan plywood (type Ι, 12 mm thickness) is used as adherends, and 100 g / m ² of aqueous adhesive compositions of Examples and Comparative Examples are uniformly applied on both sides, and then 5 ° C. and 90% humidity. In this environment, the contact rate is measured when bonded at a pressure of 0.2 MPa after drying for 2 hours. ○: 50% or more, Δ: 30 to 50%, ×: 30% or less Heat resistance: Lauan plywood (type I, 5.5 mm thickness) and melamine resin decorative board (1 mm thickness) were used as adherends, and 100 g / m ² of the aqueous adhesive compositions of Examples and Comparative Examples on both sides. After coating, drying at 23 ° C. for 30 minutes and then bonding at a pressure of 0.2 MPa, curing at 23 ° C. for 24 hours, and then measuring the time (minutes) until dropping by applying a 500 g load in a 50 ° C. atmosphere.

The water-based adhesive composition according to the present invention has a good balance of initial adhesive strength, heat resistance, contactability, storage stability, adhesiveness, etc., so that it can be used for building materials such as furniture, long sheet adhesive construction, automobile interior materials. It can be used for various applications such as the bonding field and the bonding field of composite materials with metals and plastics.

Claims (4)

A water-based adhesive composition comprising polychloroprene latex, a tackifying resin emulsion having a softening point of 100 ° C. or higher, and one or more dibasic acid dimethyl esters represented by the following formula (1): object.

(R1 and R2 are a hydrogen atom and a linear or branched alkyl group having 1 to 6 carbon atoms, and M represents an alkylene group or vinylene group having 1 to 10 carbon atoms.) The aqueous adhesive composition according to claim 1, wherein the polychloroprene latex has a gel content (toluene insoluble content) of 40 wt% to 60 wt%. 10 to 70 parts by weight of the tackifier resin emulsion solids and one or more dibasic acid dimethyl esters represented by the following formula (1) are 0.1 to 5 parts per 100 parts by weight of the polycloprene latex solids. The water-based adhesive composition according to claim 1 or 2, wherein a part by weight is blended.

(R1 and R2 are a hydrogen atom and a linear or branched alkyl group having 1 to 6 carbon atoms, and M represents an alkylene group or vinylene group having 1 to 10 carbon atoms.) 4. The aqueous adhesive composition according to claim 1, wherein the dibasic acid dimethyl ester comprises a mixture of dimethyl adipate, dimethyl succinate, and dimethyl glutarate.