JPH03157473A - Polyester-based hot-melt adhesive - Google Patents

Abstract

PURPOSE:To obtain the subject adhesive having excellent adhesivity and impact- resistant adhesivity to metal and suitable for the assembly of automobile, building material and electrical parts by compounding a specific crystalline polyester with an amorphous polyester at a specific ratio. CONSTITUTION:The objective adhesive is produced by compounding (A) a crystalline polyester containing terephthalic acid unit as >=30mol% (preferably >=40mol%) of the total acid component and having an intrinsic viscosity of >=0.55 (preferably >=0.59) measured in a 1/1 mixed solvent of phenol and tetrachloroethane at 20 deg.C and (B) an amorphous polyester having an intrinsic viscosity of <=0.45 (preferably <=0.4) measured by the method similar to the component A at a weight ratio (A:B) of 95:5 to 50:50.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a new polyester hot melt adhesive, particularly a polyester hot melt adhesive that has excellent adhesion to metals and impact-resistant adhesive strength. It relates to melt adhesives.

(Conventional technology) True melt adhesives can be used without solvent.

Adheres instantly. It has characteristics such as adhesion to a relatively wide range of adherends. As described above, hot melt adhesives are economically superior and have good adhesive performance and workability, so they have come to be used in large quantities in recent years, mainly in light adhesive fields such as packaging and bookbinding. .

However, conventional hot melt adhesives cannot be used for adhesion with metals that require high adhesion strength and impact-resistant adhesion9, for example, adhesion of metals to metals, metals to plastics, etc. . That is, hot melt adhesives usually have a coating temperature of 100 to 200℃ and a bonding temperature of 80℃.
Since it is applied at 160℃, the melting point, softening point, melt viscosity, etc. must be lowered, so the melting point and molecular weight of the polymer are lowered, and the cohesive force of the polymer is lowered. High crystallization is performed to compensate for this.

This is because sufficient adhesive strength and impact-resistant adhesive strength to metal could not be obtained.

Therefore, JP-A-51-132230 discloses a polyester adhesive containing a copolyester having a tertiary amine as an active ingredient, which has improved adhesion to metals. This adhesive.

Although the adhesion to metals has been considerably improved, there have been problems such as the interface between the adhesive and metal easily peeling off when subjected to a strong impact such as a collision.

(Problems to be Solved by the Invention) The present invention attempts to solve the problems of the prior art as described above, and its object is to provide a bonding agent having excellent adhesion and impact-resistant adhesive strength, particularly to metals. To provide a polyester hot melt adhesive.

(Means for Solving the Problem) As a result of intensive research aimed at providing a polyester-based hot melt adhesive having the above-mentioned excellent performance, the present inventors have found that crystalline polyester ( The present invention was based on the discovery that a polyester hot-melt adhesive consisting of A) and an amorphous polyester (B) exhibits particularly excellent adhesion to metals and forms a bonded portion with impact resistance.9 Reached.

The gist of the present invention is as follows.

The following crystalline polyester (A) and amorphous polyester (
B) in a ratio of 95:5 to 50:50 (weight ratio).

(A): Crystallinity in which 30 mol% or more of the acid component is terephthalic acid, and the intrinsic viscosity measured at 20°C in a mixed solvent of phenol/tetrachloroethane = 1/1 (weight ratio) is 0.55 or more. polyester.

(B); Intrinsic viscosity measured in the same manner as in (A) above is 0
．． Amorphous polyester having a molecular weight of 45 or less.

Hereinafter, nine aspects of the present invention will be described in detail.

The crystalline polyester (A) in the present invention is.

More than 30 mol% of the acid component is terephthalic acid.

It is also composed of one or more aromatic dicarboxylic acids and/or aliphatic dicarboxylic acids, one or more glycols, and in some cases one or more lactones, and the amount of terephthalic acid in the total acid component. If the terephthalic acid component is less than 30 mol%, sufficient cohesive force will not be obtained and the adhesive strength will decrease.
Must be mol% or more. In addition, if the intrinsic viscosity is less than 0.55, the impact-resistant adhesive strength will be poor, so the intrinsic viscosity should be set to 0.5.
5 or more, preferably 0.59 or more.

Examples of aromatic dicarboxylic acids other than terephthalic acid include isophthalic acid and 2,6-naphthalene dicarboxylic acid, and examples of aliphatic dicarboxylic acids include.

Malonic acid, succinic acid, glutaric acid, Acihi: /il? .

pimelic acid, speric acid, azelaic acid, sebacic acid,
Undecanniic acid, dodecanniic acid, cyclohexanedicarboxylic acid, dimer! , 1,2-polybutadiene dicarboxylic acid, and the like.

As a glycol, ethylene glycol l 113-
Propanediol, 1,4-butanediol.

1,5-bentanediol, 1,6-hexanediol, l,9-nonanediol, neopentylene gellicol, diethylene glycol, triethylene glycol, cyclohexane dimetatool, 1,2 polybutadiene glycol, polyolefin glycol, polyethylene glycol, poly Examples include tetramethylene ether glycol.

Examples of the lactone include δ-valerolactone and ε-caprolactone.

In addition, the intrinsic viscosity of the amorphous polyester (B) is 0.
．． If it exceeds 45, the melt viscosity becomes high and wetting to the adherend becomes poor, resulting in a low adhesive strength.

Therefore, the intrinsic viscosity is 0.45 or less, preferably 0.45 or less.
4 or less.

Examples of the polymerization components constituting the amorphous polyester (B) include those listed as the components of the crystalline polyester (A), and one or more types of polyhydric carboxylic acids may also be used if necessary.

Polyhydric carboxylic acids are compounds having three or more carboxyl groups in one compound or their anhydrides; examples include trimellitic acid, trimellitic anhydride, pyromellitic acid, and pyromellitic anhydride.

Examples include cyclopentane tetracarboxylic dianhydride and butane tetracarboxylic acid.

Note that the term "crystalline polyester" in the present invention refers to one that has a melting peak (endothermic peak) in differential thermal analysis (DTA) or scanning calorimetry (DSC), and amorphous polyester refers to one that has a melting peak (endothermic peak) in differential thermal analysis (DTA) or scanning calorimetry (DSC). It means something you don't have.

The polyester hot melt adhesive of the present invention is.

The crystalline polyester (A) and the amorphous polyester (
B) in a ratio of 95=5 to 50:50 (weight ratio). Amorphous polyester (
If the proportion of B) is less than 5% or more than 50%, the adhesion to metal will decrease and the impact-resistant adhesive strength will also decrease.

There are no particular restrictions on the method for producing the crystalline polyester (A) used in the present invention, and any known method can be employed. For example, a method can be adopted in which terephthalic acid, one or more dicarboxylic acids described above, and glycol and/or lactone are directly esterified or transesterified and then single-polycondensed. In addition, in the case of esterification, transesterification, and type 2 condensation, a known catalyst can be used as necessary.

There are no particular restrictions on the method for producing the amorphous polyester (B), and the method for producing the crystalline polyester (A>) described above can be adopted.
or under pressure with an inert gas such as nitrogen, 200~
It can also be produced by depolymerizing using a polycarboxylic acid or a polyhydric alcohol at 300°C.

There are no particular limitations on the method for preparing the polyester hot melt adhesive of the present invention, and known methods can be employed.

For example, 1. It is produced by melt-kneading in a Ni-Goo, Ni-Goo-Roo-Goo, extruder, etc. which are commonly used for mixing wires.

The polyester hot melt adhesive of the present invention is used for other purposes 1. For example, to increase heat-resistant adhesive strength, epoxy resins such as bisphenol A epoxy resin, novolac epoxy resin, resorcinol epoxy resin, and polyoxyalkylene epoxy resin are used. Also, amine compounds such as naphthalene diamine, aniline, adipic acid dihydrazide, etc. can be blended. Also, other thermoplastic resins, heat stabilizers, inorganic fillers, organic fillers, and flame retardants as required.

A curing accelerator and the like can be added.

The polyester hot melt adhesive of the present invention is.

Since it is stable even when melted, ordinary coating methods can be applied. For example, after applying it directly to the adherend using an extruder, hot melt applicator, roll coater, etc., it may be heat-pressed, formed into a film using an extruder, or formed into a nonwoven fabric using a spunbond method. Alternatively, after preparing it in powder form, it is used by sandwiching it between adherends and heat-pressing it. In some cases, the hot melt adhesive of the present invention may be dissolved in a solvent, applied to an adherend, dried, and then bonded by heat and pressure.

〔Example〕

The present invention will be explained in detail below by way of nine examples.

Note that "parts" in one example mean "parts by weight."

Further, the characteristic values in one example were measured by the first method.

(Measurement method) (1) Shear adhesive strength (kg/car) A shear adhesive test piece was prepared according to JIS K-6850.

Shear adhesive strength was measured at 25°C.

(2) Impact resistant adhesive strength Between two iron discs with a diameter of 92 mm and a thickness of 20 mm.

Sandwich the adhesive film and pour 16O into it.
They were heated for a minute and bonded together. This adhesive test piece was placed at a height of 1 m.
Sliding down a slope with an angle of 45 degrees.

The test piece was repeatedly made to collide with a steel plate provided at the lower end of the slope until the adhesive part of the test piece peeled off, and the number of times before it peeled off was defined as the impact-resistant adhesive strength.

(Preparation of polyester) (1) 40 mol of terephthalic acid, 30 mol of isophthalic acid.

To 30 mol of adipic acid and 150 mol of 1,4-butanediol were added 0.02 mol of n-butyl titanium as a catalyst, and an esterification reaction was carried out at 150 to 245°C while water was distilled off. Next, n-butyl titanate) 0.01
mol was added thereto, and polycondensation was performed at 245° C. for 4 hours under reduced pressure to obtain a crystalline polyester (1) having an intrinsic viscosity of 0.74.

(2) 50 moles of terephthalic acid, 40 moles of isophthalic acid.

10 moles of icoic acid diacid, 100 moles of ethylene glycol, 60 moles of neopentyl glycol, and n- as a catalyst.
Add 0.02 mol of 150-2
The esterification reaction was carried out while distilling off water at 45°C. Then, 0.01 mol of n-butyl titanate was added,
After polycondensation was carried out at 245° C. for 4 hours under reduced pressure.

4 mol of icoic acid diacid was added and depolymerization was carried out under normal pressure for 2 hours. As a result, an amorphous polyester resin (II) having an intrinsic viscosity of 0.40 was obtained.

(3) After obtaining a polyester in the same manner as in (2) from 50 moles of terephthalic acid, 50 moles of cyclohexanedicarboxylic acid, and 160 moles of neopentyl glycol.

Depolymerization was carried out at 200°C for 4 hours with 5 moles of Trimets IJ) acid to obtain an amorphous polyester with an intrinsic viscosity of 0.24 ([[
) was obtained.

(4) A polyester is obtained from 100 moles of terephthalic acid, 100 moles of 1.6-hexanediol, and 60 moles of ethylene glycol in the same manner as in (2) above, and then depolymerized to obtain an amorphous material with an intrinsic viscosity of 0.15. polyester (rV
) was obtained.

(5) 40 moles of terephthalic acid, 30 moles of isophthalic acid.

A crystalline polyester (V) having an intrinsic viscosity of 0.74 was obtained in the same manner as in (1) from 30 moles of adipic acid and 150 moles of 1,4-butanediol.

(6) Esterification and polycondensation were carried out in the same manner as in (1) using 20 moles of terephthalic acid, 80 moles of adipic acid, and 150 moles of 1°4-butanediol to obtain an intrinsic viscosity of 0.65.
A crystalline polyester (Vl) was obtained.

(7) 25 moles of terephthalic acid, 25 moles of isophthalic acid.

Esterification and polycondensation were carried out in the same manner as in (1) using 50 moles of adipic acid and 150 moles of l,4-butanediol.

An amorphous polyester (■) having an intrinsic viscosity of 0.55 was obtained.

Example 1 60 parts of crystalline polyester (1) and 40 parts of amorphous polyester (II) were kneaded at about 180°C in a plastomill [manufactured by Toyo Seiki ■], and then hot pressed at 180°C to a thickness of about 100 μm. A film was formed, and the film was sandwiched between steel plates and heated at 160° C. for 5 minutes to perform a shear adhesive strength test. Similarly, the film was heated for 30 minutes and an impact adhesive strength test was performed. The results are shown in Table 1.

Examples 2-3. Comparative Examples 1 to 5 Polyester hot melt adhesives were produced and tested in the same manner as in Example 1 using the formulations shown in Table 1. The results are also listed in Table 1.

As is clear from Table 1, Examples 1 to 3.

It can be seen that it satisfies the requirements of the present invention and is excellent in shear adhesive strength and 1f impact adhesive strength.

On the other hand, Comparative Example 1 did not contain any amorphous polyester.

Comparative Example 2 contains too much amorphous polyester.

In Comparative Example 3, the intrinsic viscosity of the crystalline polyester was too small,
In Comparative Example 4, the amount of terephthalic acid in the acid component of the crystalline polyester was less than 30 mol%.

In Comparative Example 5, the intrinsic viscosity of the amorphous polyester is too large. Thus, it can be seen that Comparative Examples 1 to 5 do not satisfy the requirements of the present invention, and both shear adhesive strength and impact resistant adhesive strength are low.

(Effects of the Invention) Since it has the above structure, the polyester hot melt adhesive of the present invention has excellent adhesion to metals and impact-resistant adhesive strength.

Therefore, the polyester hot melt adhesive of the present invention can be suitably used in various applications including automobiles, building materials, assembly of electrical parts, and the like.

Claims (1)

[Claims] (1) A polyester hot-melt adhesive prepared by blending the following crystalline polyester (A) and amorphous polyester (B) in a ratio of 95:5 to 50:50 (weight ratio). (A); 30 mol% or more of the acid component is terephthalic acid, phenol/tetrachloroethane = 1/1 (weight ratio)
A crystalline polyester having an intrinsic viscosity of 0.55 or more as measured at 20° C. in a mixed solvent. (B); Intrinsic viscosity measured in the same manner as in (A) above is 0
．． Amorphous polyester having a molecular weight of 45 or less.