JPH0588757B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an adhesive with excellent adhesive properties, chemical and physical properties, which is composed of a polyester polyurethane and a compound having three or more isocyanate groups in the molecule. In particular, the present invention relates to an adhesive having extremely excellent performance when the adherend is a vinyl chloride resin. Prior Art Soft PVC contains a large amount of plasticizer. Therefore, during adhesion, the plasticizer migrates to the adhesive surface, so sufficient consideration must be taken when selecting the adhesive. Adhesives (hereinafter referred to as polyurethane adhesives) whose main component is polyurethane (hereinafter referred to as polyester polyethylene) obtained from a polymer polyol such as polybutylene adipate glycol or polyhexamethylene adipate glycol and an organic polyisocyanate. ) exhibits excellent performance as a soft vinyl chloride adhesive because the crystallization of the polyurethane prevents plasticizer migration. Therefore, these polyurethane adhesives can be used to bond semi-rigid or rigid PVC to these materials and acrylic resin,
Films such as ABS resin, non-woven fabrics made of chemical fibers such as polyamide and polyester, fabrics such as knitted and woven fabrics,
Furthermore, it is widely used for adhesive processing of polyethylene, polypropylene, urethane foam, artificial leather, synthetic leather, footwear, bags, etc. Problems to be Solved by the Invention However, the crystallization speed of the polyurethane adhesive is still slow, and therefore there are still wrinkles in the initial adhesive strength. Therefore, for example, when vinyl chloride resin is bonded, the adhesive strength is sufficiently satisfactory. Further, these polyurethane adhesives have drawbacks such as insufficient hydrolysis resistance, particularly hot water resistance, and a decrease in adhesive strength over time, causing various problems. An object of the present invention is to provide a polyurethane adhesive that has excellent initial adhesive strength, can be bonded at high speed, has excellent heat resistance and hot water resistance, and has excellent durability with little performance deterioration over time. Another object of the present invention is to provide a polyurethane adhesive suitable for bonding vinyl chloride resin. Means for Solving the Problems According to the present invention, the above-mentioned object consists of an α,ω-alkanediol having 8 to 12 carbon atoms alone or consisting of the diol and another diol, and the α,ω-alkanediol A polyester system with a number average molecular weight of 10,000 to 70,000 and hydroxyl groups at both ends obtained by reacting a polyester polyol with an average molecular weight of 1,000 to 10,000 synthesized from a mixed glycol containing at least 50% by weight of dicarboxylic acid and a dicarboxylic acid with an organic diisocyanate. Polyurethane (A) (base ingredient) and 3 in the molecule
This is achieved by using an adhesive consisting of a compound (B) (curing agent) having at least 3 isocyanate groups. The polyester polyurethane used as the main ingredient in the adhesive of the present invention usually consists of an α,ω-alkanediol having 8 to 12 carbon atoms alone or a polyester polyol made from a mixed glycol and dicarboxylic acid mainly composed of this diol and an organic diisocyanate. It can be obtained by reacting according to the method. Here, examples of α,ω-alkanediol include 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol and 1,12-
Examples include dodecanediol. Among them, 1 and 9
-nonanediol is preferred. α during the synthesis of the polyester polyol,
It is most preferable to use the ω-alkanediol alone in terms of effectiveness, but when used in combination with a low-molecular diol having 7 or less carbon atoms, it is generally 50% by weight or more, although it varies depending on the type of low-molecular diol. It is important that Polyester polyols obtained using α,ω-alkanediols have extremely high crystallinity, and a characteristic feature is that even when copolymerized with a low-molecular-weight diol in an amount not exceeding 50% by weight, the crystallinity decreases by 1%. , 4-butanediol and 1,
This is smaller than that from polyester polyol containing 6-hexanediol as a main component. In addition, examples of diols having 7 or less carbon atoms that can be used together in an amount not exceeding 50% by weight include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, diethylene glycol, neopentyl. Examples include glycol, 3-methyl-1,5-pentanediol, and the like. In some cases, a small amount of polyol having three or more hydroxyl groups, such as tril such as trimethylolpropane and glycerin, may be used. The dicarboxylic acid for sewing the polyester polyol is preferably an aliphatic or aromatic dicarboxylic acid having 6 to 12 carbon atoms. Among them, azelaic acid and acipic acid are particularly preferred. When heat resistance is required, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and phthalic acid are preferably used. These dicarboxylic acids may be used alone or in combination of two or more. The above polyester polyols include polyethylene terephthalate, polybutylene terephthalate,
It can be produced by methods similar to known methods used in the production of polybutylene adipate or polyhexamethylene adipate, ie, transesterification or direct esterification followed by melt polycondensation reaction. The above polyester polyol has hydroxyl groups at both ends of the molecule, and the total number of hydroxyl groups in the polyester polyol is 2 or more, preferably 2 to 2.
4, preferably 2. The number of hydroxyl groups can be appropriately controlled by selecting the polyol used. The molecular weight of the above polyester polyol is 1000~
A range of 10,000, preferably 2,000 to 9,000 is desirable.
If it is outside this range, the initial adhesive strength or final adhesive strength will be significantly reduced, which is not preferable. Suitable organic diisocyanates used to produce the polyester polyurethane used in the present invention are known aliphatic, alicyclic or aromatic organic diisocyanates having two isocyanate groups in the molecule. , Particularly preferably used examples include 2,4-tolylene diisocyanate, 2,
6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate,
Examples include 4,4'-dicyclohexylmethane diisocyanate. The polyester polyurethane is produced by reacting the polyester polyol with an organic diisocyanate in a conventional manner. At that time, if necessary, a chain extender having a molecular weight of 500 or less may be used. The molecular weight of the above polyester polyurethane is
Ranges from 10000 to 70000, preferably 15000 to
The range is 40000. If the molecular weight is outside these ranges, either the initial adhesive strength, final adhesive strength, or heat resistance will be poor. The compound having three or more isocyanate groups in the molecule used as a curing agent in the adhesive of the present invention is a polyisocyanate of triisocyanate or higher. Preferably used examples include compounds in which all of the hydroxyl groups of polyols such as trimethylolpropane, glycerin, and pentaerythritol are urethanized with tolylene diisocyanate, xylylene diisocyanate, or hexamethylene diisocyanate. In the present invention, polyester polyurethane
(A) That is, the compound having three or more isocyanate groups in the molecule, that is, the curing agent, is blended in an amount of 5 to 50 parts by weight, preferably 8 to 40 parts by weight, based on 100 parts by weight of the base resin. desirable. If the blending ratio is within this range, an adhesive with significantly improved adhesive strength, heat resistance, and solvent resistance can be obtained. The adhesive of the present invention may be dissolved in an organic solvent before use. Organic solvents include ethyl acetate, methyl ethyl ketone, tetrahydrofuran,
Toluene is preferred. Further, the base agent may be used in the form of an aqueous dispersion by a conventional method. In addition, fillers, extenders, and thickeners commonly used in adhesives,
Examples of combinations of dyes, pigments, deterioration inhibitors, etc. may also be added. The adhesive can be prepared by usually mixing the polyester polyurethane (A) and the compound (B) having three or more isocyanate groups in the molecule. The adhesive of the present invention is similar to conventional polyester adhesives, including vinyl chloride resin, acrylic resin,
Used for adhesion or adhesion processing of plastics such as ABS resin, polyolefin, and polyurethane, fabrics, plastic foam, leather, footwear, bags, etc. In particular, when at least one of the adherends is a vinyl chloride resin, the adhesive has excellent initial adhesive strength, can be bonded at high speed, has excellent heat resistance, hot water resistance, and durability. Examples Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. The polyols, polyisocyanates, and chain extenders used as raw materials for polyurethane used in the examples are indicated using abbreviations, and the relationship between the abbreviations and the compounds is as follows.

[Table] Examples 1 to 4 and Comparative Examples 1 to 2 The polyester diols, diisocyanates, and chain extenders shown in Table 2 were mixed in a mixed solvent of toluene/methyl ethyl ketone (mixed weight ratio 1/1).
Add to a solid content of 50% by weight, react,
A solution of polyester polyurethane having a hydroxyl group at the molecular end and having a number average molecular weight shown in Table 2 was obtained. For 100 parts by weight of the obtained polyester solution
Blend 15 parts by weight of TMP-TDI adduct (Coronate L), then dilute with ethyl acetate to 20% by weight.
It was made into a solution. Remove the dirt on the surface of the soft PVC sheet, make it into small strips, apply the solution to the small pieces at a coating amount of 12 g/m ² , and after an open time of 10 minutes,
This small piece was overlapped with a small piece to which no solution was applied, and then pressed with a hand roller to obtain a test sheet. Even if this sheet was attempted to be removed by hand, it did not come off easily, suggesting that high-speed adhesion is possible. Also, heat this sheet at 20℃ and 65%
It was left in an RH atmosphere, and the 180 degree peel strength was measured after a predetermined time (measurement conditions: tensile speed 20cm/
minute, width 2.5cm). Furthermore, the test sheet after adhesion was heated to 90°C.
The adhesive strength after immersion in hot water for 10 days was measured under the same measurement conditions as above. The results are shown in Table 3. Although the test sheet was left indoors for one year, there was only a small decrease in adhesiveness and hydrolysis resistance.

【table】

[Table] Effects of the Invention The adhesive of the present invention has excellent initial adhesive strength, can be bonded at high speed, and has excellent hydrolysis resistance, heat resistance, hot water resistance, and durability.

Claims (1)

[Scope of Claims] 1 An α,ω-alkanediol having 8 to 12 carbon atoms alone or consisting of this diol and another diol, and containing at least 50 α,ω-alkanediols
A polyester polyurethane (A ) and an adhesive comprising a compound (B) having three or more isocyanate groups in the molecule. 2. The adhesive according to claim 1, wherein the α,ω-alkanediol is 1,9-nonanediol. 3. The adhesive according to claim 1, wherein the dicarboxylic acid is azelaic acid or adipic acid. 4. The compounding ratio of the compound (B) having three or more isocyanate groups in the molecule is 5 to 50 parts by weight with respect to 100 parts by weight of the polyester polyurethane (A),
The adhesive according to claim 1, wherein at least one of the adherends is a vinyl chloride resin.