JP2000096030A - adhesive - Google Patents

Abstract

(57) [Problem] To provide an adhesive for bonding polyolefin materials to each other or between a polyolefin and another material. SOLUTION: A graft type polyester polyol obtained by ester-bonding a polyester polyol with a polyfunctional carboxylic acid having three or more functional groups is mainly used, and a curing agent mainly containing a polyisocyanate compound is mixed as an essential component. Polyurethane-based adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solvent-based two-component curing type polyurethane adhesive in which two components comprising a main component and a curing agent are mixed immediately before use.

[0002]

2. Description of the Related Art Polyurethane adhesives include rubber, metal,
It has good adhesiveness to a wide range of materials such as wood and glass, and can be freely designed for adhesives by selecting the type and combination of polyol and isocyanate as raw materials. It is used in a wide range of fields, such as film lamination, binders such as magnetic tape, adhesives for shoes and footwear, and wood. Further, in recent years, demands for fields such as automobile parts and decorative sheets for building materials, which require tough adhesion and long-term durability, are increasing.

On the other hand, polyolefins such as polyethylene and polypropylene have been studied for their suitability as materials due to recent environmental problems such as dechlorination, workability, and low cost. It has been put to practical use in decorative sheets.

[0004]

The adhesives used for automobile interior materials and decorative sheets for building materials generally need to maintain reliable durability for a long period of time.
Bond durability when exposed to various environments is important. For example, a decorative sheet for building materials needs to maintain durability against environmental changes such as direct sunlight, temperature differences, and humidity differences for a long period of several decades. Until now, base materials made of vinyl chloride have been mainly used as decorative sheets for building materials. However, due to the recent trend of dechlorination due to environmental issues, decorative sheets for building materials using base materials made of polyolefin have been developed. It has been developed and demand is rapidly expanding.

Here, as an adhesive for bonding polyolefin materials to each other or between a polyolefin and another material, a solvent-based two-part curing type using a polyester polyol having a hydroxyl group at a terminal as a main component and a polyisocyanate compound as a curing agent. Polyurethane adhesives are known, but conventional polyurethane adhesives are often insufficient in terms of adhesion to polyolefin materials, weather resistance, and the like, and further improvements are required.

[0006]

In order to solve the above-mentioned problems, the present inventors have conducted various studies on polyurethane adhesives applicable to polyolefin materials. And a polyurethane-based adhesive having a graft-type polyester polyol as a main component obtained by ester-bonding a polyfunctional carboxylic acid having three or more functional groups with a polyfunctional carboxylic acid. It has been found that it can be used as an adhesive having excellent adhesion and weather resistance.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester polyol having a hydroxyl group at the terminal in the present invention can be prepared by a conventionally known method, that is, a method in which one or more polybasic acids and one or more polyhydric alcohols are reacted in a reaction vessel in 200 to 200. It is obtained by condensation polymerization at 250 ° C.

The polybasic acids used herein include aromatic polybasic acids such as phthalic acid, isophthalic acid and terephthalic acid; saturated aliphatic polybasic acids such as succinic acid, adipic acid and sebacic acid; maleic acid; Examples thereof include unsaturated aliphatic polybasic acids such as fumaric acid, and the above-mentioned acid anhydrides and lower esters.
Further, as the polyhydric alcohol, ethylene glycol,
Diethylene glycol, triethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexane Diol, cyclohexanediol, cyclohexane dimethanol, bisphenol A and the like can be mentioned.

At least 70 mol% of the polybasic acid component constituting the polyester polyol having a hydroxyl group at the terminal,
More preferably, 80 mol% or more is desirably an aromatic polybasic acid, more specifically, isophthalic acid. Similarly, it is desirable that 50 mol% or more, more preferably 60 mol% or more, of the alcohol component is a straight-chain alkyl diol having 5 or more carbon atoms, more specifically 1,6-hexanediol. Here, the content of the aromatic polybasic acid in the polybasic acid component is 70 mol% or more, or the content of the linear alkyl diol in the alcohol component is 50% or more.
By setting the molar% or more, the initial adhesive strength is increased and the weather resistance is also excellent.

[0010] The graft type polyester polyol in the present invention is obtained by ester-bonding the polyester polyol condensed and polymerized by the above-mentioned method and a polyfunctional carboxylic acid having three or more functional groups at 200 to 250 ° C. As the polyfunctional carboxylic acid used here,
Examples thereof include aromatic polyfunctional carboxylic acids such as trimellitic acid, pyromellitic acid and benzophenone tetracarboxylic acid, aliphatic polyfunctional carboxylic acids such as butanetetracarboxylic acid, and the above-mentioned acid anhydrides.

The weight average molecular weight of the polyester polyol having a hydroxyl group at the terminal is desirably 8,000 to 30,000, and more desirably 10,000 to 25,000. By setting the weight average molecular weight to 8,000 to 30,000, the viscosity of the graft type polyester polyol obtained by ester bonding with the polyfunctional carboxylic acid does not significantly increase, and the handling at the time of coating is easy and the weather resistance is improved. Will also be excellent.

The graft-type polyester polyol as the main component is a suitable organic solvent, for example, an ester solvent such as ethyl acetate or butyl acetate, a ketone solvent such as methyl ethyl ketone or cyclohexanone, or an aromatic solvent such as toluene or xylene. Use it in a solution that has been dissolved. In addition, if necessary,
Additives such as a flame retardant, an antioxidant, an ultraviolet absorber, a light stabilizer, an antifoaming agent, and a curing accelerator can be added.

In particular, it is more effective to add a radical scavenger and / or an ultraviolet absorber as a light stabilizer for the purpose of preventing deterioration due to ultraviolet rays and improving weather resistance due to outdoor use and the like. As this radical scavenger, a hindered amine radical scavenger is preferable. The reason for this is that hindered amine radical scavengers have a tetraalkylpiperidine as a mother nucleus, have a radical scavenging action of scavenging radicals generated by ultraviolet rays, and have various actions such as an inactive action of hydroperoxide (ROOH). It is presumed that the mechanism exerts its effect, and excellent performance can be obtained as a multifunctional stabilizer. Specific examples of the hindered amine radical scavenger include bis- (2,2,6,6-tetramethyl-4-piperidyl) sebacate and bis- (N-methyl-2,2,6,6).
-Tetramethyl-4-piperidyl) sebacate, bis-
(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1,2,2,6,6-pentamethyl-
4-piperidyl-tridecyl-1,2,3,4-butanetetracarboxylate, tetragis- (2,2,6,
6-tetramethyl-4-piperidyl) -1,2,3,4
In addition to -butanetetracarboxylate and the like, a hindered amine-based radical scavenger such as a compound disclosed in Japanese Patent Publication No. 4-82625 can be exemplified. The amount of the hindered amine radical scavenger to be added is 0.1-1.
It is appropriate to add 0 parts by weight.

[0014] Examples of the ultraviolet absorber include:
2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'
-Hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-tert-amyl-5'-isobutylphenyl) -5-chlorobenzotriazole , 2- (2'-hydroxy-3'-isobutyl-5'-methylphenyl) -5
-Chlorobenzotriazole, 2- (2'-hydroxy-
2'-hydroxyphenyl-5- such as 3'-isobutyl-5'-propylphenyl) -5-chlorobenzotriazole
Chlorobenzotriazole UV absorbers, 2- (2 ′
-Hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-5'-
2′-hydroxyphenylbenzotriazole-based ultraviolet absorbers such as methylphenyl) benzotriazole;
2'-dihydroxy-4-methoxybenzophenone, 2,
2,2′-dihydroxybenzophenone-based ultraviolet absorbers such as 2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone,
2-hydroxybenzophenone UV absorbers such as 2,4-dihydroxybenzophenone; salicylate UV absorbers such as phenyl salicylate and 4-tert-butyl-phenyl-salicylate; 2-ethyl-
Use of cyanoacrylate ultraviolet absorbers such as hexyl-2-cyano-3,3-diphenylacrylate, ethyl-2-cyano-3,3-diphenylacrylate, octyl-2-cyano-3,3-diphenylacrylate and the like. be able to. The amount of these UV absorbers added is
It is appropriate to add 0.1 to 1.0 part by weight based on 100 parts by weight of the adhesive main agent. When used in combination with a radical scavenger, a chlorine-free benzotriazole is preferred as the ultraviolet absorber, particularly from the viewpoint of compatibility between weather resistance and hot water resistance, and considering environmental friendliness.

As the curing agent in the present invention, a polyisocyanate compound having at least two, preferably three or more isocyanate groups in a molecule can be used. For example, hexamethylene diisocyanate, dimer acid diisocyanate, aliphatic polyisocyanate such as norbornene diisocyanate, isophorone diisocyanate, hydrogenated dicyclohexylmethane diisocyanate, alicyclic polyisocyanate such as hydrogenated xylylene diisocyanate, methylene diphenyl diisocyanate,
Aromatic polyisocyanates such as tolylene diisocyanate and xylylene diisocyanate, and burette-modified, allophanate-modified, isocyanurate-modified and carbodiimide-modified polyisocyanates.

The conditions for curing the adhesive constituted as described above are such that the molar ratio of the graft type polyester polyol as the main component to the polyisocyanate as the curing agent is 5: 1 to 20: 1, and Preferably, 1
0: 1 to 15: 1. Molar ratio of 5:
When the ratio is 1 to 20: 1, an adhesive having good adhesive strength and weather resistance can be obtained.

The adhesive constituted according to the present invention can be used for bonding to various plastic substrates, but particularly preferable objects to be used are that at least one is a polyolefin substrate and the other is a material of the other substrate. Is plastic, rubber, metal, glass,
It is possible to correspond to a combination of paper and the like.

[0018]

The present invention will be described in more detail with reference to the following specific examples. (Example 1) 89.6 g (0.54 mol) of isophthalic acid, 8.8 g (0.06 mol) of adipic acid, 55.2 g (0.47 mol) of 1,6-hexanediol, 26.7 g (0.25 mol) of diethylene glycol, [Isophthalic acid: adipic acid = 9: 1 (molar ratio) 1,6-hexanediol: diethylene glycol = 6.5: 3.5 (molar ratio)] As a catalyst, 90 mg of tetra-n-butyl titanate and 180 mg of monobutyltin oxide Was charged into a 500 ml four-necked flask, heated to 200 ° C. while stirring under a nitrogen stream, and subjected to a condensation polymerization reaction for 3 hours to give a weight average molecular weight of about 100.
00 polyester polyol was obtained. To this polyester polyol, 3.8 g (0.02 mol) of trimellitic acid, 20 mg of tetra-n-butyl titanate and 40 mg of monobutyltin oxide were added, and the mixture was stirred again under a nitrogen gas stream.
The mixture was heated to 00 ° C., and an esterification reaction was carried out for 3 hours while distilling off water to obtain a graft type polyester polyol having a weight average molecular weight of about 30,000. This graft type polyester polyol is dissolved in ethyl acetate to form a solution having a nonvolatile content of 60%.
0.5 parts of 2- [2-hydroxy-3,5-bis (α, α′-dimethylbenzyl) phenyl] -2H-benzotriazole and 0.5 parts of bis (2,2,6,6-tetra Methyl-4-piperidyl) sebacate was added to obtain an adhesive base.

Example 2 89.6 g (0.54 mol) of isophthalic acid, 8.8 g (0.06 mol) of adipic acid, 53.8 g (0.46 mol) of 1,6-hexanediol, 26.1 g (0.25 m) of diethylene glycol ol), [isophthalic acid: adipic acid = 9: 1 (molar ratio) 1,6-hexanediol: diethylene glycol = 6.5: 3.5 (molar ratio)] As a catalyst, tetra-n-butyl titanate 90 mg, monobutyl 180 mg of tin oxide was charged into a 500 ml four-necked flask, heated to 200 ° C. while stirring under a nitrogen stream, and a condensation polymerization reaction was carried out for 3 hours to give a weight average molecular weight of about 200.
00 polyester polyol was obtained. To this polyester polyol, 3.8 g (0.02 mol) of trimellitic acid, 20 mg of tetra-n-butyl titanate and 40 mg of monobutyltin oxide were added, and the mixture was stirred again under a nitrogen stream while stirring.
The mixture was heated to 00 ° C., and an esterification reaction was carried out for 3 hours while distilling off water to obtain a graft type polyester polyol having a weight average molecular weight of about 60000. This graft type polyester polyol is dissolved in ethyl acetate to form a solution having a nonvolatile content of 60%.
0.5 parts of 2- [2-hydroxy-3,5-bis (α, α′-dimethylbenzyl) phenyl] -2H-benzotriazole and 0.5 parts of bis (2,2,6,6-tetra Methyl-4-piperidyl) sebacate was added to obtain an adhesive base.

Example 3 89.6 g (0.54 mol) of isophthalic acid, 8.8 g (0.06 mol) of adipic acid, 57.5 g (0.49 mol) of 1,6-hexanediol, 27.8 g (0.26 m) of diethylene glycol ol), [isophthalic acid: adipic acid = 9: 1 (molar ratio) 1,6-hexanediol: diethylene glycol = 6.5: 3.5 (molar ratio)] As a catalyst, tetra-n-butyl titanate 90 mg, monobutyl 180 mg of tin oxide was charged into a 500 ml four-necked flask, heated to 200 ° C. while stirring under a nitrogen stream, and subjected to a polycondensation reaction for 3 hours to give a weight average molecular weight of about 600.
0 polyester polyol was obtained. To this polyester polyol, 3.8 g (0.02 mol) of trimellitic acid, 20 mg of tetra-n-butyl titanate and 40 mg of monobutyltin oxide were added, and the mixture was stirred again under a nitrogen stream.
The mixture was heated to 0 ° C. and subjected to an esterification reaction for 3 hours while distilling off water to obtain a graft type polyester polyol having a weight average molecular weight of about 18,000. This graft type polyester polyol is dissolved in ethyl acetate to form a solution having a nonvolatile content of 60%.
0.5 parts of 2- [2-hydroxy-3,5-bis (α, α′-dimethylbenzyl) phenyl] -2H-benzotriazole and 0.5 parts of bis (2,2,6,6-tetra Methyl-4-piperidyl) sebacate was added to obtain an adhesive base.

Example 4 49.8 g (0.30 mol) of isophthalic acid, 43.8 g (0.30 mol) of adipic acid, 34.0 g (0.29 mol) of 1,6-hexanediol, 45.8 g (0.43 mol) of diethylene glycol [Isophthalic acid: adipic acid = 5: 5 (molar ratio) 1,6-hexanediol: diethylene glycol = 4: 6 (molar ratio)] As a catalyst, 90 mg of tetra-n-butyl titanate and 180 mg of monobutyltin oxide were mixed in 500 ml. The mixture was charged in a four-necked flask, heated to 200 ° C. while stirring under a stream of nitrogen, and subjected to a condensation polymerization reaction for 3 hours to give a weight average molecular weight of about 100.
00 polyester polyol was obtained. To this polyester polyol, 3.8 g (0.02 mol) of trimellitic acid, 20 mg of tetra-n-butyl titanate and 40 mg of monobutyltin oxide were added, and the mixture was stirred again under a nitrogen stream while stirring.
The mixture was heated to 00 ° C., and an esterification reaction was performed for 3 hours while distilling off water to obtain a graft type polyester polyol having a weight average molecular weight of about 30,000. This graft type polyester polyol is dissolved in ethyl acetate to form a solution having a nonvolatile content of 60%.
0.5 parts of 2- [2-hydroxy-3,5-bis (α, α′-dimethylbenzyl) phenyl] -2H-benzotriazole and 0.5 parts of bis (2,2,6,6-tetra Methyl-4-piperidyl) sebacate was added to obtain an adhesive base.

Example 5 89.6 g (0.54 mol) of isophthalic acid, 8.8 g (0.06 mol) of adipic acid, 55.2 g (0.47 mol) of 1,6-hexanediol, 26.7 g (0.25 m) of diethylene glycol ol), [isophthalic acid: adipic acid = 9: 1 (molar ratio) 1,6-hexanediol: diethylene glycol = 6.5: 3.5 (molar ratio)] As a catalyst, tetra-n-butyl titanate 90 mg, monobutyl 180 mg of tin oxide was charged into a 500 ml four-necked flask, heated to 200 ° C. while stirring under a nitrogen stream, and subjected to a condensation polymerization reaction for 3 hours to give a weight average molecular weight of about 100.
00 polyester polyol was obtained. To this polyester polyol, 3.8 g (0.02 mol) of trimellitic acid, 20 mg of tetra-n-butyl titanate and 40 mg of monobutyltin oxide were added, and the mixture was stirred again under a nitrogen stream while stirring.
The mixture was heated to 00 ° C., and an esterification reaction was performed for 3 hours while distilling off water to obtain a graft type polyester polyol having a weight average molecular weight of about 30,000. This graft type polyester polyol is dissolved in ethyl acetate to form a solution having a nonvolatile content of 60%.
0.5 parts of 2- [2-hydroxy-3,5-bis (α, α′-dimethylbenzyl) phenyl] -2H-benzotriazole and 0.5 parts of bis (2,2,6,6-tetra Methyl-4-piperidyl) sebacate was added to obtain an adhesive base.

Comparative Example 1 89.6 g (0.54 mol) of isophthalic acid, 8.8 g (0.06 mol) of adipic acid, 55.2 g (0.47 mol) of 1,6-hexanediol, 26.7 g (0.25 m) of diethylene glycol ol), [isophthalic acid: adipic acid = 9: 1 (molar ratio) 1,6-hexanediol: diethylene glycol = 6.5: 3.5 (molar ratio)] As a catalyst, tetra-n-butyl titanate 90 mg, monobutyl 180 mg of tin oxide was charged into a 500 ml four-necked flask, heated to 200 ° C. while stirring under a nitrogen stream, and subjected to a condensation polymerization reaction for 3 hours to give a weight average molecular weight of about 100.
00 polyester polyol was obtained. This polyester polyol was dissolved in ethyl acetate without graft polymerization to form a solution having a nonvolatile content of 60%, and 0.5 part of 2- [2-hydroxy-3,5-bis ( [α, α′-dimethylbenzyl) phenyl] -2H-benzotriazole and 0.5 part of bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate were added to obtain an adhesive base material.

The base agent 100 of Examples 1 to 4 and Comparative Example 1
Parts by weight are an isocyanurate-modified hexamethylene diisocyanate (NCO content 21.2%) as a curing agent.
%), And the mixture was diluted with ethyl acetate to a nonvolatile content of 30% to obtain an adhesive compounding liquid. The main agent 1 of Example 5
Is a isocyanurate-modified hexamethylene diisocyanate (NCO content 2
1.2%) was added and 4 parts by weight of ethyl acetate was added.
% To give an adhesive formulation.

An adhesive compound solution was applied to a polypropylene film having a corona-treated adhesive surface at a wire bar amount of 15 g / m ² and dried at 80 ° C. for 1 minute.
The printed surface of the decorative sheet printed with the urethane-based ink is laminated on the adhesive-coated surface, and pressed at a pressure of 1 kg / cm ² for 10 seconds. What was cured at 60 ° C. for 12 hours was used as an evaluation sample.

The initial adhesive strength and weather resistance of this evaluation sample were measured under the following conditions. Initial adhesion strength: Peel strength measurement of evaluation sample (25 mm piece) Weather resistance: Super UV test (temperature test: 63 ° C., cycle test of UV 20 hours + rain 4 hours, UV light 295 to 400 n)
m, 100 ± 5 mW / cm ² ) at 150 and 200
The peeled surface of the evaluation sample after time was visually observed.

[0027]

[Table 1] Peeling surface A: Peeling of the acrylic-urethane-based ink from the printing layer. Maintain adhesion between polypropylene film and adhesive layer. Peeling surface B: Peeling from the polypropylene film and the adhesive layer.

[0028]

According to the present invention, a graft type polyester polyol obtained by graft-polymerizing a polyfunctional carboxylic acid having three or more functional groups onto a polyester polyol having a hydroxyl group at a terminal is used as a main component, and a polyisocyanate compound is used as a curing agent. By providing a solvent-based two-component curable polyurethane adhesive, the adhesive strength and the plastic material, especially the adhesion between polyolefin materials or between a polyolefin and other materials, are superior to conventional polyurethane adhesives. Because it has weather resistance, it can be used not only for conventional applications such as laminating packaging films and magnetic tape binders,
It can be sufficiently used as an adhesive in applications such as automotive interior materials requiring long-term durability and decorative sheets for building materials.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J040 EF111 GA05 HB31 HB33 HC16 HC22 HC25 JA13 KA10 KA16 KA20 KA28 LA01 LA07 LA10 MA02 MA05 MA08 MA10 MA11 MA12 NA05 NA06 NA12 NA16 NA21

Claims (8)

[Claims] 1. A main component mainly comprising a graft type polyester polyol obtained by ester-bonding a polyester polyol having a hydroxyl group at a terminal with a polyfunctional carboxylic acid having three or more functional groups, and a polyisocyanate compound as a main component. An adhesive obtained by mixing a hardening agent to be used as an essential component. 2. The polyester component having a hydroxyl group at a terminal thereof, in which at least 70 mol% of the acid component is an aromatic polybasic acid, and at least 50 mol% of the alcohol component is a linear alkyl diol having 5 or more carbon atoms. The adhesive according to claim 1, wherein: 3. The adhesive according to claim 2, wherein the aromatic polybasic acid is isophthalic acid. 4. The adhesive according to claim 2, wherein the linear alkyl diol is 1,6-hexanediol. 5. The adhesive according to claim 1, wherein the polyester polyol having a terminal hydroxyl group has a weight average molecular weight of 8,000 to 30,000. 6. The adhesive according to claim 1, wherein the molar ratio of the graft type polyester polyol to the polyisocyanate compound is 5: 1 to 20: 1. 7. The adhesive according to claim 1, wherein the adhesive comprises an ultraviolet absorber and / or a radical scavenger. 8. The ultraviolet absorber and the radical scavenger are each composed of a benzotriazole-based compound and a hindered amine-based compound, and each contains 0.1 to 1.0 part by weight based on 100 parts by weight of the adhesive main agent. The adhesive according to claim 7, wherein the adhesive is applied.