JP3438792B2 - Polyester hot melt adhesive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester hot melt adhesive. More specifically, it shows good wettability to an adherend when bonding plastic such as polyethylene terephthalate (PET) or polyvinyl chloride to metal or glass, has excellent initial adhesive strength, and can be pressed for a short time. The present invention relates to a polyester hot-melt adhesive having high adhesiveness under pressure and pressure at low temperatures. 2. Description of the Related Art Hot melt adhesives have characteristics such as no pollution, labor saving, bonding in a short time, and excellent productivity, and are used in a wide range of fields. The thermoplastic resin used in the hot melt adhesive must (1) be easily melted by heating and exhibit excellent wettability to an adherend.
(2) Deterioration such as oxidation, decomposition, and alteration during heating and melting should not occur. (3) The adhesive strength is excellent. (4) Excellent heat resistance, hydrolysis resistance, cold resistance, weather resistance, solvent resistance, etc. Performance is required. [0003] Among these required properties, polyester-based hot-melt adhesives exhibit good adhesion to plastics such as PET and PVC, and have heat resistance, weather resistance and solvent resistance. It is widely used in fields that take advantage of its features. However, although the conventional polyester hot-melt adhesive has the above-mentioned excellent performance, the adhesive strength to metal and glass is insufficient, and at present, it is used for limited applications. Therefore,
In order to improve such disadvantages, there have been proposed some techniques for compensating for these disadvantages by blending an epoxy resin with a polyester-based hot melt adhesive. For example, as described in JP-A-50-63025, column 1, lines 5 to 10, an epoxy resin is added to a copolymerized polyester obtained by glycol-exchanging polyethylene terephthalate with a glycol other than ethylene glycol. Have been proposed. However, this technique is limited to certain copolymerizations as described above,
A sufficiently high T-type peel strength under normal conditions is obtained,
When aged at ℃, the adhesive strength decreases over time, and as in the examples, hot-press bonding requires 200 ° C. for 10 minutes, which is a characteristic of the hot-melt adhesive in that the productivity is poor and the bonding is completed in a short time. Is not utilized. On the other hand, Japanese Patent Application Laid-Open No. Sho.
As described in column 12-18, it has been proposed to specify polyester resins and epoxy resins to enable bonding in seconds. According to this technique, although a sufficiently high T-type peel strength can be obtained with respect to metal in a short time of 5 to 20 seconds, as in the example, the surface temperature of the adherend is 180 to 2 at the time of thermocompression.
The temperature must be as high as 50 ° C., which is not suitable when the adherend to metal is a plastic having low heat resistance. The method of improving metal adhesion by adding an epoxy resin in this way requires a long time or a high temperature for heat compression, and the glycidyl group in the epoxy resin reacts in some way before the adhesive strength is developed. It seems to be. DISCLOSURE OF THE INVENTION [0006] The present invention provides excellent initial adhesive strength by exhibiting good wettability to an adherend when bonding a plastic such as PET or PVC to a metal or glass. The present invention also provides a polyester-based hot melt adhesive having high adhesiveness by heat compression bonding in a short time and pressure compression bonding at a low temperature. SUMMARY OF THE INVENTION In view of the above problems, the inventors of the present invention have shown a polyester having excellent adhesive strength and having high adhesiveness by heat-pressing in a short time or pressure-pressing at a low temperature. As a result of intensive studies on a hot melt adhesive, the present invention has been achieved. That is, in the present invention, (A) 20 to 80 mol% of the polyvalent carboxylic acid component is an alicyclic dicarboxylic acid;
The number average molecular weight is that the remainder is an aromatic dicarboxylic acid, 2 to 20 mol% of the polyhydric alcohol component is a polyalkylene glycol having a molecular weight of 250 or more and 3,000 or less, and 80 to 98 mol% is a glycol having a molecular weight of less than 250. Is 1
Copolyester 70 to 95 in the range of 10,000 to 100,000
5% by weight and (B) a polyhydroxy polyether resin having a number average molecular weight in the range of 4,000 to 30,000 and a hydroxyl equivalent of 1,500 to 4,000 equivalent / 10 ⁶ g.
Polyester hot melt adhesive containing about 30% by weight. The aromatic dicarboxylic acid of the copolymerized polyester in the present invention includes terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, -Lithium sulfoisophthalic acid, sodium sulfoterephthalic acid, 4,4'-diphenylmethanedicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-biphenyldicarboxylic acid,
Aromatic dicarboxylic acids such as 4,4'-stilbene dicarboxylic acid are exemplified. Further, if necessary, an aromatic polycarboxylic acid having three or more functional groups such as trimellitic acid, trimesic acid, and pyromellitic acid can be used. Examples of the alicyclic dicarboxylic acid include hexahydrophthalic anhydride, hexahydroisophthalic acid, hexahydroterephthalic acid, and tricyclodecanedicarboxylic acid. Examples of the glycol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-
Pentanediol, 3-methylpentanediol, 1,
6-hexanediol, 1,9-nonanediol, 2,
2,4-trimethyl-1,3-pentanediol, 2-
Examples thereof include butyl-2-ethyl-1,3-propanediol, diethylene glycol, triethylene glycol, neopentyl glycol, cyclohexane dimethanol, tricyclodecane dimethanol, and ethylene oxide or / and propylene oxide adducts of bisphenol A. Further, if necessary, trifunctional or higher-functional polyhydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol can be used. In this case, trifunctional or higher-functional polycarboxylic acids or polyhydric alcohols are all carboxylic acid components or Suitably, it is at most 10 mol% with respect to all alcohol components. Also,
Examples of the polyalkylene glycol include polyethylene glycol, polytetramethylene glycol, and polypropylene glycol. In the polyester used in the present invention, 20 to 80 mol%, preferably 30 to 70 mol%, of the polyvalent carboxylic acid component is an alicyclic dicarboxylic acid, and the remainder is an aromatic dicarboxylic acid. . When the amount of the alicyclic dicarboxylic acid is less than 20 mol%, the compatibility with the polyhydroxypolyether resin is deteriorated, and an adhesive having excellent adhesiveness to metal by short-time heat compression or low-temperature pressure compression is required. You can't get it. On the other hand, if the amount of the alicyclic dicarboxylic acid is more than 80 mol%, the cohesive strength of the polyester is reduced, so that a high pressure adhesion cannot be obtained. 2-20 mol% of the polyhydric alcohol,
Preferably, 3 to 15 mol% has a molecular weight of 250 or more,
It is a polyalkylene glycol of 00 or less. If the molecular weight of the polyalkylene glycol is less than 250 or less than 2 mol%, the compatibility with the polyhydroxypolyether resin is deteriorated, and the adhesiveness to metal is excellent by short-time heat compression or low temperature pressure compression. When the molecular weight is more than 3,000 or more than 20 mol%, the cohesive strength is reduced and an adhesive having excellent initial adhesive strength cannot be obtained. The number average molecular weight of the polyester used in the present invention is 10,000 to 100,000. If the number average molecular weight is less than 10,000, the physical properties of the adhesive are reduced, and an adhesive having excellent initial adhesive strength cannot be obtained. On the other hand, if it is higher than 100,000, the compatibility with the polyhydroxypolyether is reduced, so that it is impossible to obtain a high adhesive strength to a metal. The polyhydroxy polyether resin used in the present invention has 1,500 to 4,4 hydroxyl groups in the molecule.
2,000 equivalents / 10 ⁶ g, bisphenol A, bisphenol F, tetrabromobisphenol A
Alternatively, an epoxy resin and a phenoxy resin derived from hydrogenated bisphenol A and epichlorohydrin or methyl epichlorohydrin may be used. The hydroxyl group of the polyhydroxy polyether resin is 1,500 equivalent / 10
If it is less than ⁶ g, the initial adhesion to metal is poor, and
If it is more than 0 equivalent / 10 ⁶ g, the adhesive strength to plastic is reduced. The polyhydroxy polyether resin used in the present invention may have a glycidyl group in the molecule depending on the raw materials and the production method. The number average molecular weight of the polyhydroxy polyether used in the present invention is 4,000 or more, 30,
000 or less. If the number average molecular weight is less than 4,000, the initial adhesive strength to metal is poor, and if it is more than 30,000, the adhesive strength to plastic decreases. The method for producing the polyester resin in the present invention is not particularly limited, and may be a direct esterification method of a polycarboxylic acid and a polyhydric alcohol or a transesterification method of an alkyl ester of a polycarboxylic acid with a polyhydric alcohol. As a result, a polyhydric alcohol ester of a polycarboxylic acid is obtained, and thereafter, the composition can be obtained by polymerization under normal pressure or reduced pressure. At this time, if necessary, an esterification catalyst or a polycondensation catalyst can be used. Depending on the purpose of use and various required properties, various additives, stabilizers and other thermoplastic resins may be added to such an extent that the original properties are not impaired. The amount of the polyester and the polyhydroxy polyether resin in the present invention is 70 to 95% by weight based on the total weight of the polyester component, and the remaining 3
0 to 5% by weight is the polyhydroxypolyether component. If the polyester component is less than 70% by weight, PE
Adhesion to plastics such as T and PVC is impaired, and if it exceeds 95% by weight, adhesion to metal is impaired. The method of mixing the polyester and the polyhydroxypolyether is not particularly limited, and for example, a melting pot, a kneader, a mixing roll, an extruder, an internal mixer, or the like can be used. When using the polyester hot melt adhesive of the present invention, the polyester hot melt adhesive is molded into a powdery, chip-like, tape-like, string-like, film-like or non-woven fabric-like form, and the polyester is sandwiched between adherends. A method of heating and melting at a temperature higher than the softening point, a method of applying a molten polyester composition onto an adherend using an adhesive applicator, cooling and solidifying the composition, and the like can be employed. As the bonding conditions, the surface temperature of the adherend is at a temperature of not less than the softening point of the polyester adhesive and not more than 180 ° C., particularly preferably at the temperature of not less than the softening point of the polyester adhesive + 10 ° C. and not more than 160 ° C. for 3 to 10 seconds. After crimping, it may be left to cool or quench. The use of the polyester hot melt adhesive in the present invention is not particularly limited,
Metal materials and glass materials such as iron, aluminum, copper and tin and PE
It can be used for bonding with plastics such as T and PVC. EXAMPLES The present invention will be described in detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the examples, "parts" means "parts by weight". Table 1 shows the composition of the saturated copolymerized polyester used in the examples. The synthesis of the saturated copolymerized polyester was performed according to a conventional method. Various characteristic values were measured by the following methods. 1. Number average molecular weight The number average molecular weight was determined by GPC as follows.
Polyester 0.0 in 10 ml of tetrahydrofuran solvent
Dissolve 3 g to prepare a polymer solution. The carrier-solvent is tetrahydrofuran, the flow rate is 1.0 ml / min, and the column is Shodex KF-806, manufactured by Showa Denko KK
The measurement was carried out at a column temperature of 30 ° C. using a No. 04,802. The number average molecular weight was determined by standard polystyrene conversion. 2. Melting point (° C.) Measured at a heating rate of 20 ° C./min using 5 mg of a sample with a DSC200 type differential scanning calorimeter manufactured by Seiko Co., Ltd. 3. 180 ° peel adhesive strength 50 μm thick Adhesive film having a width of 10 mm was applied to a 50 μm thick adhesive film.
-Side corona-treated biaxially stretched PET film with a thickness of 100
μ rolled copper foil or 100μ thick electrolytic tin plated copper foil or 100μ thick biaxially stretched PET film, using a single-sided heat sealer, so that the corona-treated surface of the biaxially stretched PET film becomes the adhesive surface PE with a thickness of 50μ
Heat from T film side, 140 ℃ × 8sec × 3kg / c
Bonding was performed at m ² . The peel adhesive strength was measured at 20 ° C. × 67% by 180 ° peeling according to the peel adhesive strength test method of JIS K 6854 adhesive using a Tensilon tensile tester.
Measured under RH. Example 1 26.6 parts (0.16 mol) of terephthalic acid, 27.5 parts (0.16 mol) of 1,4-hexahydroterephthalic acid,
28.8 parts (0.32 mol) of 1,4-butanediol and 0.034 parts (0.000 parts) of tetrabutyl titanate
10 mol) into a reaction vessel, and the mixture is heated to 150 ° C. to 220 ° C. under nitrogen.
After the esterification reaction was performed at 32 ° C., 32 parts (0.032 mol) of polytetramethylene glycol (molecular weight 1,000) and 0.1 part of a stabilizer were added, and the mixture was stirred for 15 minutes. Then gradually reduce the pressure while heating to 250 ° C,
The pressure was reduced to 0.1 mmHg for 30 minutes, and condensation was performed for 1 hour at this temperature and under reduced pressure conditions to obtain a polyester A. Table 1 shows the characteristic values of the obtained polyester. To 90 parts of the obtained polyester A, an epoxy resin composed of bisphenol A and epichlorohydrin (Epototo YD-020, manufactured by Toto Kasei Co., Ltd., hydroxyl equivalent: 3,500 equivalent / 10 ⁶ g, number average molecular weight: 7) ,
700) Melting and kneading at 200 ° C. using a Ikegai PCM-30 twin-screw kneader at a ratio of 10 parts to obtain a pellet-like composition,
This was rolled at 200 ° C. for 1 minute using a heat press to obtain a hot-melt adhesive film having a thickness of 50 μm. Examples 2 to 8 Polyesters B to E were obtained in the same manner as in Example 1 except that various monomers shown in Table 1 were used instead of the monomers used in Example 1. Table 1 shows the characteristic values of the obtained polyester. Compositions and films were obtained in the same manner as in Example 1 using various polyhydroxy polyethers shown in Table 3. [Table 1] Comparative Examples 1 to 8 Polyesters F to H were obtained in the same manner as in Example 1 except that various monomers shown in Table 2 were used instead of the monomers used in Example 1. Table 2 shows the characteristic values of the obtained polyester. Compositions and films were obtained in the same manner as in Example 1 using various polyhydroxy polyethers shown in Table 4. Tables 3 and 4 show the adhesive property values of each resin.
It was shown to. [Table 2] [Table 3] [Table 4] As is clear from the above, the polyester-based hot melt adhesive of the present invention can be used to bond plastics such as PET and PVC to metal and glass, as compared with conventional polyester hot-melt adhesives. In this case, it shows good wettability to the adherend, shows excellent initial adhesive strength, and shows high adhesiveness by heat compression bonding in a short time or pressure compression at a low temperature.

Claims (1)

(57) [Claim 1] (A) 20-80 of the polycarboxylic acid component
Mole% is an alicyclic dicarboxylic acid, the remainder is an aromatic dicarboxylic acid, 2 to 20 mole% of the polyhydric alcohol component is a polyalkylene glycol having a molecular weight of 250 to 3,000, and 80 to 98 mole% is a molecular weight. A glycol having a number average molecular weight in the range of 10,000 to 100,000 and (B) a number average molecular weight in the range of 4,000 to 30,000; A polyester hot-melt adhesive containing 5 to 30% by weight of a polyhydroxy polyether resin having 1,500 to 4,000 equivalents / 10 ⁶ g.