JPH0151509B2 - - 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 molecular weight. Polyester has a high 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. Polyester has a lower melting point and moderate crystallinity. A copolymer is 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 degree of crystallinity, degree of polymerization, molecular structure, etc. of the adhesive resin. It is thought that crystallinity and copolymer composition are the main factors for properties, texture, etc., and the specific 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,
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 comprises dicarboxylic acid units consisting essentially of terephthalic acid residues and 99 to 50 mol% of 1,6
-hexanediol residues and 1 to 50 mol% of 2
This invention relates to an adhesive comprising as an active ingredient a polyester copolymer constituted by a glycol unit consisting of a -methyl-1,3-propanediol residue. Terephthalic acid is essential as the dicarboxylic acid component for producing the polyester copolymer used in the adhesive of the present invention, but as the glycol component, 99 to 50 mol% of 1,6-hexanediol and 1 to 50 mol% of the glycol component are required. % 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, resulting in lower melting points and crystallization. It is an extremely effective compound in reducing the degree of carbonation. 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 linked 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 present invention, the melting point and crystallinity of a polyester copolymer obtained by combining the two types of low molecular weight glycol components that exhibit contradictory tendencies as described above in terms of melting point and crystallinity can be adjusted to a desired level. A polyester copolymer which can be easily controlled within the above range and has extremely excellent adhesive strength can be obtained, and by using this as an active ingredient, it is possible to provide an excellent adhesive particularly as a hot melt adhesive. 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 it forms a coordinate bond between the atoms on the surface of the substrate to be bonded and It is thought that adhesion is improved because hydrogen bonds are easily formed. 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
~40 mol%, but if it is less than 1 mol%, 2-
The above-mentioned characteristics of methyl-1,3-propanediol cannot be exhibited, and the melting point and crystallinity of the resulting copolymer become too high. The crystallinity is extremely low, 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 a dicarboxylic acid is shown below.
A mixed diol of hexanediol and 2-methyl-1,3-propanediol was oxidized using a normal esterification catalyst under a nitrogen stream at normal pressure of about 150 to 240°C.
The transesterification reaction is carried out at a temperature of 200 to 200 mHg under reduced pressure of 5 mmHg or less.
Polycondensate at 280℃. A wide range of catalysts can be used as the above catalyst, but
Tetramethoxytitanium, Tetraethoxytitanium,
Titanium compounds such as tetra-n-propoxy titanium, tetra-iso-propoxy titanium, tetrabutoxy titanium, 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. The polyester copolymer used in the present invention is
It is produced using terephthalic acid, 2-methyl-1,3-propanediol, and 1,6-hexanediol as starting materials, but if necessary, adipic acid, azelaic acid, Polyvalent aliphatic carboxylic acids such as sebacic acid, polyvalent aromatic carboxylic acids such as isophthalic acid, trimellitic acid, pyromellitic acid, 2,6-naphthalene dicarboxylic acid, ethylene glycol, propylene glycol, neopentyl glycol,
Polyhydric alcohols such as 1,4-butanediol, 1,4-cyclohexanediol, cyclohexanedimethanol, trimethylolpropane, and pentaerythritol can also be used, and high molecular weight alkylene ether glycols such as polytetramethylene ether glycol can also be used. etc. can also be used. In addition, phosphorus-containing compounds such as phosphorous acid, triphenyl phosphate, tridecyl phosphite, and triphenyl phosphite are effective as coloring inhibitors, and are used in an amount of 0.001 to 0.3% by weight based on the total copolymer produced. It is preferable to use 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 for clothing, packaging, laminating, bookbinding, wood industry,
It can be used as an adhesive in a wide range of applications such as can making, shoe making, electrical work, crown making, etc. However, depending on the application, other types of thermoplastic resin adhesives, such as
It can also be used in combination with polyethylene, ethylene polymer 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 is determined by analyzing the nuclear magnetic resonance spectrum of the obtained copolymer, and the mole percentage of each diol residue constituting the resin is calculated based on the total diol residues.
It was shown in 2 Intrinsic viscosity is a value measured at 25°C in a mixed solvent of tetrachloroethane-phenol (3 parts: 2 parts). 3 The melting point and heat of fusion were measured by a differential scanning calorimeter, and Sn was used as a reference material for the heat of fusion. 4 Adhesive strength The tensile shear adhesive strength test method (JIS K6850) of the Japanese Industrial Standards "Adhesives" was followed. That is,
Between aluminum plates treated according to JIS K6848,
The tensile shear adhesive strength of a test piece thermocompressed to a thickness of 100 μm at 150°C was measured using a Tensilon UTM-500 universal testing machine manufactured by Toyo Baldwin. Example 1 69.9 parts of dimethyl terephthalate, 2-methyl-
14.6 parts of 1,3-propanediol and 44.7 parts of 1,6-hexanediol were charged into a reaction vessel equipped with a double helical ribbon stirrer together with 0.07 parts of tenabutoxytitanium catalyst, and the mixture was heated at normal pressure under a nitrogen stream.
Heat at 180℃ for 1 hour, then at 230℃ for 2.5 hours,
89% of the theoretical amount of methanol produced was distilled off. Tridecyl phosphite was then added to the reaction mixture.
After adding 0.08 parts, 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 intrinsic viscosity of the obtained polyester is 0.780
dl/g, the melting point was 122°C, and the heat of fusion was 5.07 cal/g. The copolymerized polyester was found to contain 29 mol% of 2-methyl-1,3-propanediol and 1,6-hexanediol by nuclear magnetic resonance spectroscopy.
It was revealed that it contained 71 mol% of diol residues. 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 polymer obtained.

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Claims (1)

[Claims] 1 A dicarboxylic acid unit consisting essentially of terephthalic acid residues, 99 to 50 mol% of 1,6-hexanediol residues, and 1 to 50 mol% of 2-methyl-1,3
- An adhesive whose active ingredient is a polyester copolymer composed of propanediol residues and glycol units.