JPH0155310B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an adhesive comprising a novel polyester copolymer as an active ingredient. More specifically, the present invention relates to an adhesive composition containing as an active ingredient a polyester copolymer which has a lower melting point and an appropriate degree of crystallinity than conventional polyester copolymers. Conventionally, linear polyester copolymers have been used in a wide range of applications such as films, molded products, and fibers, but generally, polyester copolymers of this type with a moderate degree of crystallinity have a high molecular weight and a high It has a melting point and is not necessarily suitable as an active ingredient for adhesives, especially hot melt adhesives that do not use solvents, due to the balance between melting point and crystallinity. Polymers are required. A polyester copolymer is composed of a glycol component and a dicarboxylic acid component, and by combining these two components in various ways, the crystallinity, melting point, etc. of the copolymer can be varied over a wide range. It is said that the adhesive strength of a hot melt adhesive is determined by the crystallinity, degree of polymerization, molecular structure, etc. of the adhesive resin, and low temperature adhesion is determined by the melting point, as well as water washing resistance and dry cleaning resistance. The degree of crystallinity and copolymer composition are thought to be the main factors for texture, texture, etc. Specifically, the properties of polyester resin required for hot melt adhesives are crystalline melting point of 70°C to 140°C, intrinsic viscosity of 0.4 or more, The degree of crystallinity is such that the heat of fusion is 1 to 10 calories per gram, but it has been difficult to satisfy these requirements with the polyester adhesives proposed so far. As a result of intensive research, the present inventors have found that the above-mentioned conditions are met, the melting point is low, and the degree of crystallinity is moderate.
They discovered an adhesive containing a polyester copolymer as an active ingredient that has extremely excellent adhesive properties, leading to the present invention. That is, the present invention provides (A) 50 to 99 mol% of terephthalic acid residues and 50 to 99 mol% of terephthalic acid residues;
A dicarboxylic acid unit consisting of 1 mol% isophthalic acid group and (B) a glycol unit consisting of 50 to 99 mol% 1.6-hexanediol residue and 50 to 1 mol% 2-methyl-1.3-propanediol residue. and (C) one or more high molecular weight diol units selected from polyalkylene ether glycol residues and polycaprolactone glycol residues (provided that the proportion of the high molecular weight diol component in the copolymer is 0 to 60% by weight) % of the polyester copolymer as an active ingredient. The dicarboxylic acid component for making the polyester copolymer used in the adhesive of the present invention is as follows:
It is a mixture of terephthalic acid and isophthalic acid, with 50-99 mol% of the dicarboxylic acid component being terephthalic acid and 50-1 mol% being the isophthalic acid component. The reason why the ratio of terephthalic acid to isophthalic acid is limited to this range is to satisfy the softening temperature and elastic properties of the resulting polymer. That is, terephthalic acid is 50-99 mol%, preferably 70-90 mol%
If it is less than 50 mol%, the softening temperature of the obtained polymer will be too low, which is not preferable. On the other hand, the amount of isophthalic acid is 50 to 1 mol %, preferably 30 to 10 mol %, and if it is 50 mol % or more, the polymer is similarly reduced too much, which is not preferable. The glycol component for making the polyester copolymer used in the adhesive of the present invention is 99 to
50 mol% 1.6-hexanediol and 1-50
A mixture of mol% 2-methyl-1,3-propanediol is used. 2-Methyl-1,3-propanediol has one methyl group in its side chain and is an asymmetric diol in terms of its chemical structure.It irregularizes the structure of polyester copolymers containing it as a copolymerization component, and increases the melting point and It is a very effective compound in reducing crystallinity. Moreover, since both of the two hydroxyl groups are primary, they are highly reactive and easily react with compounds having carboxyl groups such as terephthalic acid to form ester bonds. On the other hand, 1.6-hexanediol is a diol in which six methylene groups are bonded in a linear chain and each has a primary hydroxyl group at both ends, and it easily reacts with a compound having a carboxyl group to form an ester bond. However, the polyester obtained by reacting with dicarboxylic acid exhibits high crystallinity. According to the invention,
The melting point and crystallinity of the polyester copolymer obtained by combining the above two types of low molecular weight glycol components, which exhibit contradictory tendencies in terms of melting point and crystallinity as described above, can be easily controlled within the desired range. A polyester copolymer which can be produced and has extremely excellent adhesive strength can be obtained, and by using this as an active ingredient, an adhesive particularly excellent as a hot melt adhesive can be provided. The mechanism by which such excellent adhesive strength is obtained is not clearly understood, but one hypothesis is that 2-methyl-
Due to the electron donating property of the methyl group at the 2-position of 1.3-propanediol, the electron density of the carbonyl oxygen of terephthalic acid is increased, and the electron density of the carbonyl oxygen of terephthalic acid is increased, and the coordinate bond between the atoms on the surface of the substrate to be bonded and the hydrogen It is believed that adhesion is improved due to the ease of bond formation. The proportion of 2-methyl-1,3-propanediol used in the production of the polyester copolymer in the glycol component is 1 to 50 mol%, preferably 15 to 50 mol%.
However, if it is less than 1 mol%, the above characteristics of 2-methyl-1,3-propanediol cannot be exhibited, and the melting point and crystallinity of the resulting copolymer become too high. If it exceeds mol%, the melting point and crystallinity of the resulting polyester copolymer will drop too much, which is not preferable. Furthermore, in the present invention, one or more high molecular weight diols selected from polyalkylene ether glycol and polycaprolactone glycol are used as polymerization reaction components. These polymeric diols impart properties such as abrasion resistance, impact resistance, flexibility, or elastic recovery to the resulting copolymer. The above-mentioned polyalkylene ether glycols include diethylene glycol, triethylene glycol, or polyethylene glycol with a higher degree of polymerization, poly(1.2- and 1.3-propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide). Examples include glycols and copolymers thereof, and a mixture of these may also be used. The number average molecular weight of these polyalkylene ether glycols is from 100 to 3,000, preferably from 100 to 2,000. In addition, the above polycaprolactone glycol is obtained by ring-opening polymerization of lactone using a suitable catalyst in the presence of a low molecular weight glycol such as ethylene glycol, and its number average molecular weight is 500 to 4000.
Preferably it is 800-3000. The most preferable such lactone is ε-caprolactone, and others include enantholactone, β-propiolactone, dimethylpropiolactone, butyrolactone, and γ-caprolactone.
Valerolactone, γ-caprolactone, γ-caprylolactone, crotolactone, δ-valerolactone, δ-caprolactone, etc. are also used,
Two or more of these lactones can also be used simultaneously. In the reaction of the present invention, the proportion of the high molecular weight diol component used in the resulting polymer is 0 to 0.
The amount is 60% by weight, preferably 0 to 40% by weight. If it exceeds 60%, the resulting copolymer becomes too soft, which is not preferable. Conventionally known methods for producing polyester can be applied as they are to producing the above-mentioned polyester copolymer used in the present invention. That is, it can be produced by either a method of directly polycondensing a dicarboxylic acid compound and a diol compound, or a method of reacting an ester-forming derivative such as a lower alkyl ester of a dicarboxylic acid or a halogen derivative with a diol compound. An example of a polycondensation method by the so-called transesterification method using a lower alkyl ester of dicarboxylic acid is to use 1.6-hexane in an excess number of moles relative to a mixture of dimethyl terephthalate and dimethyl isophthalate, that is, a total of 1.1 to 2.0 times the mole amount. Diol and a mixed diol of 2-methyl-1,3-propanediol and high molecular weight diol were heated using a conventional esterification catalyst under a nitrogen stream under normal pressure.
Perform the transesterification reaction at a temperature of 150-240℃,
After distilling off methanol and adding a catalyst, color inhibitor, etc. as necessary, polycondensation is carried out at about 200 to 280°C under reduced pressure of 5 mmHg or less. A wide range of catalysts can be used as the catalyst, but
Tetramethoxytitanium, Tetraethoxytitanium,
Titanium compounds such as tetra-n-propoxytitanium, tetra-iso-propoxytitanium, tetrabutoxytitanium, di-n-butyl-tin-dilaurate, di-n-butyl-tin-oxide, dibutyl-tin-
Examples include combinations of tin compounds such as diacetate, acetates of magnesium, calcium, zinc, etc., and antimony oxide or the above-mentioned titanium compounds. These catalysts are preferably used in an amount of 0.002 to 0.8% by weight based on the total copolymer produced. In addition, phosphorus-containing compounds such as phosphorous acid, triphenyl phosphate, tridecyl phosphite, and triphenyl phosphite are effective as coloring inhibitors, and are 0.001 to 0.3% by weight based on the total copolymer produced.
It is preferable to use the range. In addition to the coloring inhibitor, additives such as a crystallization accelerator, a polymerization accelerator, a whitening agent, and a light stabilizer can be added as necessary. The polyester copolymer used in the present invention can be used not only as a hot melt adhesive but also as a solvent adhesive. The adhesive of the present invention can be used as an adhesive in a wide range of applications such as clothing, packaging, laminating, bookbinding, wood industry, can manufacturing, shoe manufacturing, electrical work, crowns, etc. Depending on the situation, it may also be used in combination with other types of thermoplastic resin adhesives, such as polyethylene and ethylene copolymers, polyamide resins, polypropylene resins, polyurethane resins, and the like. Examples of the production of the polyester copolymer used in the present invention, physical properties of the resin, and performance when used as a hot melt adhesive are shown below as examples, but the present invention is not limited thereto. . In addition, parts in the examples mean parts by weight, and the measured values were obtained by the following measuring method. (1) The copolymer composition was determined by analyzing the nuclear magnetic resonance spectrum of the obtained copolymer. Each diol residue constituting the resin is expressed as mol% based on the total diol residues, and for high molecular weight diols, the residue is expressed as weight% based on the copolymer. (2) Intrinsic viscosity is a value measured at 25°C in a mixed solvent of tetrachloroethane-phenol (3 parts: 2 parts). (3) Melting point and heat of fusion were measured using a differential scanning calorimeter, and Sn was used as a reference material for the heat of fusion. (4) Adhesive strength (1) Tensile shear adhesive strength The tensile shear adhesive strength test method (JIS K6850) of the Japanese Industrial Standards ``Adhesives'' was followed. That is, the tensile shear adhesive strength of a test piece thermocompressed to a thickness of 100 μm at 150° C. between aluminum plates treated in accordance with JIS K6848 was measured using a universal testing machine Tensilon UTM-500 manufactured by Toyo Baldwin. (2) Peel adhesion to Tetoron Broad Polyester resin powder with a particle size of 60 to 80 mesh was spread at a rate of 25 g/cm ³ between the broads, and the pressure was 2 Kg/cm ² , the temperature was 150°C, and the time was 20 seconds. A test piece with a width of 25 mm was cut out from the material, and the T-Beer peel adhesion strength was measured using Tensilon UTM--500 manufactured by Toyo Baldwin Co., Ltd.
Measured using a mold universal testing machine. Example 1 62.9 parts of dimethyl terephthalate, 7.0 parts of dimethyl isophthalate, 2-methyl 1.3-propanediol
9.7 parts of 1.6-hexanediol and 0.07 parts of tetrabutoxytitanium catalyst were charged into a reaction vessel equipped with a butane helical ribbon stirrer, and the mixture was heated at normal pressure.
The mixture was heated at 180°C for 1 hour under a nitrogen stream and then at 230°C for 2.5 hours to distill out 89% of the theoretical amount of methanol. Next, 0.08 part of tridecyl phosphite was added to the reaction mixture, the temperature was raised to 250°C, the pressure in the system was reduced to 0.2 mmHg over 40 minutes, and polymerization was carried out under these conditions for 3.5 hours. The obtained polyester has an intrinsic viscosity of 0.820 d/g and a melting point of 125
℃, and the heat of fusion was 5.75 cal/g. Furthermore, it was revealed by nuclear magnetic resonance spectroscopy that the copolymerized polyester contained diol residues of 21 mol% of 2-methyl-1,3-propanediol and 79 mol% of 1,6-hexanediol. Furthermore, the tensile shear strength of this polyester is 65.4Kg/
It was warm in ^cm2 . In addition, the T-peel peel strength is 830g/
It was 25mm. Examples 2 to 3 and Comparative Examples 1 to 2 Polymerization was carried out under exactly the same polymerization conditions as in Example 1 using the charged amounts shown in Table 1. Table 1 shows the measured values for each of the obtained polymers.

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Claims (1)

[Scope of Claims] 1 (A) 50 to 99 mol% of terephthalic acid residues and
A dicarboxylic acid unit consisting of 50 to 1 mol% of isophthalic acid groups and (B) 50 to 99 mol% of 1.6-hexanediol residues and 50 to 1 mol% of 2-methyl-1.3-propanediol residues. and (C) one or more high molecular weight diol units selected from polyalkylene ether glycol residues and polycaprolactone glycol residues (provided that the proportion of the high molecular weight diol component in the copolymer is 0). A polyester adhesive whose active ingredient is a polyester copolymer composed of (up to 60% by weight)