JPH09279114A - Saturated polyester adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject adhesive comprising a linear polyester resin having hydroxyl groups at both the molecular ends as a main component and an epoxy compound as a hydrogen ion-catching agent, capable of adhering in a short time at a low temperature and excellent in moisture-resistant adhesivity. SOLUTION: This saturated polyester adhesive comprises (A) a linear polyester resin having hydroxyl groups at both the molecular ends (preferably a polyester having a number-average mol.wt. of 5000-20000 and a Tg of -30 to 80 deg.C) and (B) an epoxy compound (preferably a glycidylamine or alicyclic type epoxy resin having a viscosity of <=50000cps at 25 deg.C). The component B is preferably added in an amount of 0.01-30 pts. based on the main component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear saturated polyester adhesive which adheres at a low temperature of less than 170 ° C. in a short time and has excellent moisture resistance.

[0002]

BACKGROUND OF THE INVENTION Saturated polyester adhesives are generally composed mainly of a thermoplastic high molecular weight linear polyester resin, and include polyester, polyvinyl chloride, polycarbonate, cellulose acetate, plastic materials such as ABS, aluminum, It has excellent adhesion and coating properties to metal materials such as copper, steel, stainless steel, and various fiber materials such as polyester fibers. Since it is a thermoplastic polyester, it has the advantages of being able to bond in a very short time and being excellent in flexibility, but on the other hand, when it is used under high temperature and high humidity, depolymerization reaction of ester bond occurs to improve the adhesive strength. There was a defect that the decrease was large and the adhesion reliability was lacking. Further, regarding the adhesive strength between the adherends, the image of being strong is not sufficient, and there is concern about long-term reliability.

Therefore, it has been proposed to cure the hydroxyl groups at both ends of the linear polyester (partially converted to carboxyl groups by thermal oxidation) with an appropriate curing agent to improve the adhesion reliability. (1) Peroxide / magnesium oxide crosslinks a saturated polyester with peroxide (JP-A-51-
No. 83640) (2) A resin which is added with an amino resin and is cured by a methylol etherification reaction with a hydroxyl group (JP-A-64-5727).
0, JP 3-8391 A, JP 6-99
(619) (3) A compound which is cured by addition reaction of isocyanate with a hydroxyl group (JP-A-63-295690).
JP-A-63-25470, JP-A-51-3718
No. 9, JP-A-4-292613, and JP-A-3-
(8391 gazette, Japanese Patent Publication No. 6-99619 gazette) (4) A compound having an electron beam functional unsaturated bond is added, and the compound is indirectly cured by being irradiated with an electron beam (Japanese Patent Laid-Open No. Sho 6-96
(1) JP-A-203331) (5) What is cured by a dealcohol reaction by adding a silane coupling agent (JP-B-63-36945, JP-A-3-64538, JP-A-6-2718)
34) (6) A compound which is added with an epoxy compound and is cured by an addition reaction with a hydroxyl group (Japanese Patent Publication No. Sho 57-57270 and Japanese Patent Publication No. Heisei 6-99619).

[0004]

However, in the above proposed technique, even if the hydroxyl groups at both terminals are crosslinked, the depolymerization of the ester bond cannot be fundamentally prevented. Further, in the case of (6), the reaction between the glycidyl group and the hydroxyl group requires a high temperature for a long time (180 ° C. or higher), and therefore cannot be used for a low temperature short time adhesion application. The present invention has been made in view of such circumstances, excellent moisture resistance adhesiveness, storage stability, etc.,
It is an object of the present invention to provide an adhesive that can maintain high adhesion reliability for a long period of time.

[0005]

According to the present invention, the above object is to achieve a saturated resin composition comprising, as a main component, a linear polyester resin having hydroxyl groups at both ends, to which an epoxy compound as a hydrogen ion scavenger is added. This is achieved with a polyester adhesive.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The linear polyester resin used in the present invention is a saturated polyester resin having hydroxyl groups at both ends of the polyester skeleton. The linear polyester resin as the main component is used alone or as a blend of two or more. The number average molecular weight (Mn) of the linear polyester resin is 5,000 to 200,0.
In the range of 00, Tg is preferably in the range of -30 to 80 ° C. If it is out of the range, the cohesive force of the adhesive itself is lowered or, on the contrary, becomes high, and high adhesive force cannot be obtained.
The epoxy compound as a hydrogen ion scavenger added to the polyester resin functions as a hydrogen ion scavenger described later, not as a curing agent found in the prior art. How to distinguish whether the added epoxy compound is functioning as a curing agent or a hydrogen ion trapping agent can be determined by, for example, measuring the gel fraction of the adhesive and measuring the gel fraction.

That is, if it functions as a curing agent,
The insoluble matter increases and the gel fraction increases. On the other hand, if it functions as a hydrogen ion trap, the gel fraction hardly changes. As an epoxy compound, the viscosity at 25 ° C is 50,000c
A glycidyl amine of ps or less or an alicyclic type is preferable. That is, the reason is based on the mobility of the epoxy compound for capturing hydrogen ions and the ease of nucleophilic reaction. Further, the addition amount of the epoxy compound is 0.01 to 30 parts with respect to the main component. 0.0
If it is less than 1 part, the expected hydrogen ion trapping effect cannot be obtained, and if it exceeds 30 parts, the adhesive strength is largely reduced.

The following materials can be used for the epoxy compound as the hydrogen ion scavenger used in the present invention. <Glycidylamine type> -Tetraglycidylaminodiphenylmethane-Triglycidyl-paraaminophenol-Triglycidyl-metaaminophenol-Diglycidylaniline-Diglycidyltoluidine-Tetraglycidyl metaxylenediamine-Diglycidyltribromoaniline-Tetraglycidylbisaminomethylcyclohexane <Alicyclic type> ・ Alicyclic diepoxy acetal ・ Alicyclic diepoxy adipate ・ Alicyclic diepoxy carboxyate ・ Vinyl cyclohexene dioxide

In the present invention, "number average molecular weight"
Is calculated using gel permeation chromatography and using a calibration curve of standard polystyrene. The "viscosity" is measured with a general cone type viscometer at a sample temperature of 25 ° C. As the adherend, plastic materials such as polyester, polyvinyl chloride, polycarbonate, cellulose acetate and ABS, metal materials such as aluminum, copper, steel and stainless steel, and various fiber materials such as polyester fibers are preferably used. Other materials such as polyethylene, polypropylene, polyolefins such as ethylene-vinyl acetate copolymers or copolymers containing olefin as a main component or a mixture thereof, thermoplastic materials such as polyvinyl alcohol and nylon, and further polyimide, polystyrene, engineering It can also be applied to plastics and the like.

In order to obtain higher adhesiveness, it is preferable to subject the surface of the adherend to general-purpose surface treatment such as corona treatment. If necessary, this adhesive contains brominated aromatic compounds and phosphorus compounds (flame retardants), glass fibers and carbon fibers (reinforcing materials), talc and calcium carbonate (fillers), oligostyrene and petroleum resins (viscosity modifiers). ), Phenol resin or xylene resin (tackifier), hindered phenol resin or phosphorus resin (antioxidant), benzophenone compound or tinuvin compound (ultraviolet absorber), silane coupling agent or titanate coupling agent (adhesion) You may use together various additives, such as a property modifier. The technical point regarding the adhesive of the present invention is that a special epoxy compound is added as a hydrogen ion scavenger. When the linear polyester resin is left under high temperature and high humidity, hydrogen ions (partially converted to carboxyl groups by oxidation of hydroxyl groups at both terminals, hydrogen ions corresponding to the acid dissociation constant of the molecule are dissociated and produced) to act as a catalyst, The ester depolymerization reaction takes precedence. As a result, the molecular weight of the polyester resin is reduced, and the adhesiveness is lowered. The epoxy compound is for capturing the hydrogen ions and for preventing the ester depolymerization reaction.

The adhesive of the present invention can be obtained by stirring and dissolving a predetermined amount of a saturated polyester resin and an epoxy compound in a general-purpose solvent such as toluene, ester or ketone. If the adhesion temperature exceeds 180 ° C., the epoxy compound acts as a curing agent and crosslinks. More preferable conditions are 100 ° C to 150 ° C. For the above reasons, the moisture-resistant adhesiveness of the linear polyester resin could be significantly improved.

[0012]

EXAMPLES The present invention will be described below based on examples, but the scope of the present invention is not limited to these examples. Example 1 <Adhesive formulation> -Linear polyester resin A (manufactured by Unitika Ltd., Elitel UE-3220: molecular weight Mn25000, Tg5)
℃, softening point 120 ℃ 100 parts ・ Epoxy compound (Mitsubishi Gas Chemical Co., Ltd. tetraglycidyl bisaminomethylcyclohexane: 25 ℃ viscosity 200
0 cps, glycidyl amine type) 3 parts Toluene / MEK = 8/2 solution (solid content 30%) of the above adhesive component is applied to a PET substrate that has been corona-treated on both sides so that the adhesive thickness after drying is 20 μm. did. The adhesive surfaces of the substrates coated with the adhesive were adhered to each other with a hot roll laminator. The bonding conditions are as follows: Roll temperature: 120 ° C. Roll speed: 0.5 m / min Pressure: 5 kgf / cm ² (Converted to pressure sensitive paper) Roll material: Made of silicone rubber. The room temperature adhesive strength, the adhesive strength after the high temperature and high humidity treatment, and the pot life were measured and shown in Table 1.

Example 2 <Adhesive Blending> Linear polyester resin B: 100 parts (Unitika Co., Ltd., Elitel UE-3500) Physical properties Resin B Molecular weight Mn 30000 Tg (° C) 35 Softening point (° C) 145 Special epoxy compound: 3 parts (Nippon Kayaku Co., Ltd. diglycidyl toluidine 25 ° C. viscosity 50 cp glycidyl amine type) Bonding was performed under the same conditions as in Example 1 except that the above adhesive was changed.

Example 3 <Adhesive Blending> Linear polyester resin C: 100 parts (manufactured by Toyobo Co., Ltd., Byron 500) Physical properties Resin C Molecular weight Mn 22500 Tg (° C) 4 Softening point (° C) 114 Special epoxy compound: 3 parts (Ciba-gaigi Alicyclic
diepoxy adipate 25 ° C. viscosity 700 cp alicyclic type) Bonding was performed under the same conditions as in Example 1 except that the above adhesive was changed.

Comparative Examples 1 and 2 <Adhesive Blend> Only the linear polyester resin A (Comparative Example 1) and the linear polyester resin B (Comparative Example 2) were dissolved in a solvent and the same conditions as in Example 1 were used. Glued The room temperature adhesive strength, the adhesive strength after the high temperature and high humidity treatment, and the pot life were measured and shown in Table 1. Comparative Example 3 The composition of Example 1 was heat-pressed (pressure 5 kgf / cm ² ) under the conditions of an adhesion temperature of 180 ° C. and a time of 60 minutes. Table 1 shows the results.

[0016]

[Table 1] <Test method> -Adhesive force after high-temperature and high-humidity treatment Two bonded base materials in a strip shape (width 10 mm, length 5 c
The sample cut into m) was treated at 85 ° C. and 85% RH in a thermo-hygrostat for 0, 200, and 500 hours. After the sample was taken out, it was left at room temperature for 30 minutes, and the adhesive strength was measured at room temperature with a tensile tester. -Pot life Two substrates coated with an adhesive were heat-treated at 65 ° C for 30 days and then taken out, and the adhesive surfaces were adhered to each other under the conditions shown in Example 1. The room temperature adhesive strength was measured under the following conditions.・ Adhesive strength measurement conditions Peeling speed: 50 mm / min Peeling angle: 90 degrees

[0017]

The saturated polyester adhesive of the present invention is
The main component is a linear polyester resin having hydroxyl groups at both ends of the main chain, and an epoxy compound is added to this as a hydrogen ion scavenger, and the epoxy compound is effective for depolymerization of ester bonds. Therefore, the present adhesive has excellent moisture-resistant adhesiveness, storage stability and the like, and can maintain high adhesive reliability for a long period of time.

Claims (4)

[Claims] 1. A saturated polyester adhesive comprising a linear polyester resin having hydroxyl groups at both ends and an epoxy compound as a hydrogen ion scavenger. 2. An epoxy compound having a viscosity of 50 at 25 ° C.,
A glycidyl amine having a viscosity of 000 cps or less or an alicyclic epoxy compound.
The saturated polyester-based adhesive described in. 3. The saturated polyester adhesive according to claim 2, wherein the amount of the epoxy compound added is 0.01 to 30 parts with respect to the main component. 4. A linear polyester resin having a number average molecular weight (Mn) of 5,000 to 200,000 and a Tg of -30 to 80 ° C. Item 5. The saturated polyester adhesive according to any one of Items 1 to 3.