JPS6354034B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a hot melt adhesive containing a thermoplastic copolymerized polyester resin as an active ingredient and having excellent softness and flexibility. More specifically, the present invention relates to a copolyester resin having excellent adhesiveness and durable adhesiveness to soft vinyl chloride resins such as vinyl chloride resins. In recent years, hot melt adhesives have been recognized for their non-polluting, high-speed adhesion, and ease of bonding operation, and have been used in a variety of applications. Polyester resins, represented by polyethylene terephthalate and polybutylene terephthalate, are widely used in various fields as fibers, films, molding materials, etc. due to their excellent mechanical strength, thermal stability, water resistance, and chemical resistance. These polyesters are highly crystalline, rigid, and have a high melting point, and cannot be used as hot melt adhesives. However, by introducing other components to their constituent dicarboxylic acid and diol components, resins with various characteristics can be created. Numerous reports and proposals have been made regarding the possibility of obtaining Such so-called copolymerized polyester resins are generally known to have excellent adhesion to plastics such as polyester, polycarbonate, and polyvinyl chloride resins, and to metal foils such as aluminum and copper. However, the so-called durable adhesiveness, which has high initial adhesion to these adhesive bodies and maintains its performance over a long period of time, is influenced by the resin properties of the copolyester. In particular, when soft vinyl chloride resin containing a large amount of low molecular weight plasticizer (low molecular weight esters such as dioctyl phthalate) is bonded with a hot melt adhesive, the plasticizer contained in the vinyl chloride resin will reach the adhesive interface after bonding. There is a problem in that this migration causes a decrease in adhesive strength over time. This decrease in adhesive strength is noticeable in crystalline copolyester resins, and is slow in amorphous copolyester resins. However, amorphous polyester resins lack heat resistance and are prone to blocking, so they cannot be used as hot melt adhesives with excellent flexibility and heat resistance. Taking these various problems into consideration, the present inventors have obtained a hot melt adhesive that has excellent flexibility and flexibility, as well as excellent initial adhesion and durable adhesion to soft vinyl chloride resin, and heat resistance. As a result of intensive study, we have arrived at the present invention. That is, the present invention provides a polyester resin consisting of a dicarboxylic acid component, a low molecular weight glycol component, and a polytetramethylene glycol component, in which the dicarboxylic acid component consists of 90 to 50 mol% of terephthalic acid and 10 to 50 mol% of a dicarboxylic acid other than terephthalic acid, Low molecular weight glycol component is 30-75 mol% 1,4-butanediol and diethylene glycol
Polytetramethylene glycol with a molecular weight of 500 to 6000 and 0.1 to 5 mol% based on the total dicarboxylic acid, with a melting point of 80 to 160°C.
This is a hot melt adhesive mainly made of polyester resin. The dicarboxylic acid component used in the present invention consists of 90 to 50% by weight of terephthalic acid and 10 to 50% by mole of dicarboxylic acids other than terephthalic acid. However, if the content of terephthalic acid exceeds 90% by mole, the flexibility of the polyester resin will decrease. It becomes defective. Conversely, terephthalic acid is 50
If it is less than mol%, the crystallinity of the polyester resin will become poor and the heat resistance will decrease, which is not preferable. Examples of dicarboxylic acid components other than terephthalic acid include succinic acid, adipic acid, azelaic acid, sebacic acid, orthophthalic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid. These copolymerizable dicarboxylic acid components can be used alone or in combination, but it is necessary to consider the melting point, crystallinity, and flexibility of the polyester resin. As dicarboxylic acids other than terephthalic acid, it is preferable to mainly use adipic acid and isophthalic acid. The preferable range of terephthalic acid and dicarboxylic acid other than terephthalic acid is 80 to 55 mol% of terephthalic acid and 20 to 45 mol% of dicarboxylic acid other than terephthalic acid. On the other hand, the low molecular weight glycol component consists of 30-75 mol% 1,4-butanediol and 70-25 mol% diethylene glycol. If the content of 1,4-butanediol is less than 30 mol%, the crystallinity of the polyester resin will be poor and the heat resistance will be insufficient. On the contrary, 1,4
- If the content of butanediol exceeds 75 mol%, the resin will lack flexibility and its durable adhesive properties will be poor. As low molecular weight glycols, small amounts of ethylene glycol,
1,6-hexanediol and 1,4-hexane dimethanol may be contained. The polytetramethylene glycol with a molecular weight of 500 to 6000 to be copolymerized with the polyester resin of the present invention is
0.1 to 5 mol% based on the total acid components, preferably 0.5 to 5 mol%
It is 2.0 mol%. Together with diethylene glycol, polytetramethylene glycol has a great effect on imparting flexibility to resins, and is a major factor in imparting adhesive durability. If polytetramethylene glycol is less than 0.1 mol, adhesive durability is poor, and if it exceeds 10 mol%, heat resistance becomes poor. In the present invention, it is necessary to select a composition from the above copolymer composition so that the melting point of the polyester resin is 80 to 160°C. If the melting point is less than 80°C, heat resistance is insufficient and the resin tends to develop stickiness, causing problems during storage and use. On the other hand, the melting point
If the temperature exceeds 160°C, the temperature used for adhesion becomes too high, which may cause shrinkage or damage to the adherend, which is undesirable. A desirable melting point is 90 to 140°C. The method for producing the hot melt adhesive of the present invention is not particularly limited, and can be carried out in accordance with a conventional method. For example, after directly esterifying or transesterifying terephthalic acid and other dicarboxylic acids or their ester-forming derivatives with the aforementioned glycols simultaneously or stepwise,
Carry out the polycondensation reaction under vacuum. Any of the various conventional catalysts, stabilizers and additives may be used. The hot melt adhesive used in the present invention can be formed into various shapes such as pellets, powder, film, or non-woven fabric, and can be sandwiched between adherends and bonded by heating, or after being applied to the adherend using a melt applicator. Various methods can be adopted, such as a method of gluing together, a method of coating an adherend in the form of a film or tube using an extruder, and then gluing it together. The hot melt adhesive of the present invention may optionally include:
Stabilizers, fillers, pigments, and other thermoplastic resins may be mixed as appropriate. The hot melt adhesive of the present invention has moderate crystallinity and extremely excellent flexibility. Particularly when used to bond soft vinyl chloride resins, it exhibits excellent heat resistance and durable adhesive properties, with little decrease in adhesive strength over time. The reason for this is not clear, but it is thought that it has good compatibility with vinyl chloride resin and also with plasticizer.When bonded, the low molecular plasticizer contained in soft vinyl chloride resin passes through the adhesive interface. It is presumed that this is because it dissolves in the hot melt adhesive. The hot melt adhesive of the present invention can also be used as a flexibility modifier for vinyl chloride resins.
When mixed with vinyl chloride resin in combination with a small amount of low-molecular-weight plasticizers or alone, problems such as surface migration of plasticizers (such as contamination, tackiness,
It has the characteristics of a polymeric plasticizer that reduces hygiene (hygiene, etc.) and has durability. Furthermore, by mixing the hot melt adhesive of the present invention into vinyl chloride resin, it is possible to improve the adhesiveness of vinyl chloride resin, especially to impart adhesiveness to polyester. The hot melt adhesive of the present invention has excellent adhesion to fibers, plastics, metal foil, leather, rubber, etc., and can also be used as adhesives for these materials that require flexibility. Hereinafter, the present invention will be explained in more detail with reference to Examples. In the examples, parts indicate parts by weight. The reduced viscosity of the copolymerized polyester was measured at 30°C in a mixed solvent of phenol/tetrachloroethane = 60/40 (weight ratio). The melting point was measured using a fully automatic melting point measuring device (Model FP-1, manufactured by Mettler). T-peel adhesive strength was measured using Tensilon at a stretching speed of 200 mm/min. Flexibility was determined from the texture of the 50μ film. Example 1 In a reaction vessel equipped with a stirrer, a thermometer, and a cooling tube,
Dimethyl terephthalate 973 parts, 1,4-butanediol 566 parts, diethylene glycol 546 parts, polytetramethylene glycol (molecular weight 1050) 42
After charging 0.75 parts of potassium titanate oxalate, and 1.9 parts of antimony trioxide, and carrying out a transesterification reaction at 160 to 220°C for 3 hours, 1.3 parts of triphenyl phosphite and 409 parts of adipic acid were added and heated to 220 to 250°C. in
The esterification reaction was carried out for 1.5 hours. Next, the mixture was slowly heated to 250°C and the pressure was reduced, and a polycondensation reaction was carried out for 3.5 hours under a reduced pressure of 0.1 to 0.3 mmHg. The reduced viscosity of the obtained copolymerized polyester (A) is
0.95, and the melting point was 108°C. As a result of compositional analysis by NMR, the composition of the copolymerized polyester (A) was 64 mol% of terephthalic acid, 36 mol% of adipic acid, 1,4-
Butanediol 60 mol%, diethylene glycol
It was 40 mol%. A 50μ film prepared by dissolving this copolymerized polyester (A) in chloroform was sandwiched between soft vinyl chloride resin sheets (95μ) at 130℃, 2.5Kg/cm ²
Heat bonded for 15 seconds. (The bonding temperature is 20° below the melting point.)
The temperature was raised. ) Next, a 25mm x 150mm test piece was cut from this adhesive piece and tested at room temperature (230℃), hot (60℃ and 80℃),
The T-peel adhesion strength after being left at 80℃ for one month was 14.5Kg/25mm, 2.5Kg/25mm, respectively.
They were 0.8Kg/25mm and 11.3Kg/25mm. Examples 2 to 3, Comparative Examples 1 to 6 Copolymerized polyester (B) in the same manner as in Example 1
~(I) was obtained. Table 1 shows the composition, melting point, reduced viscosity, and flexibility of each copolyester. Further, the results of an adhesion test conducted in the same manner as in Example 1 are shown in Table 2.

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Claims (1)

[Claims] 1 In a polyester resin consisting of a dicarboxylic acid component, a low molecular weight glycol component and a polytetramethylene glycol component, the dicarboxylic acid component consists of 90 to 50 mol% of terephthalic acid and 10 to 50 mol% of a dicarboxylic acid other than terephthalic acid, and the dicarboxylic acid component consists of a low molecular weight glycol component. Ingredients: 1,4-butanediol 30
~75 mol% and diethylene glycol 70-25 mol%, based on total dicarboxylic acids.
A hot melt adhesive mainly composed of a polyester resin having a melting point of 80 to 160°C and consisting of 0.1 to 5 mol% of polytetramethylene glycol with a molecular weight of 500 to 6,000.