JPH01161079A - Adhesive for heat sealing - Google Patents

Abstract

PURPOSE:To obtain the subject adhesive which provides improved adhesion between metal and plastic and between plastics themselves, and has improved heat resistance, by incorporating a silane coupling agent into a polymer, such as polypropylene or polyethylene, grafted with maleic acid or acrylic acid in a specified ratio. CONSTITUTION:The subject adhesive is produced by incorporating 0.1-5 pts.wt. silane coupling agent into 100 pts.wt. one or more polymers selected from among polyethylene, polypropylene, an ethylene/vinyl acetate copolymer, and an ethylene/ethyl acrylate copolymer, grafted with 0.5-10wt.% maleic acid and/or acrylic acid. As the silane coupling agent, a compound of formula I (wherein X contains one or more carbon-to-carbon double bonds; Y1-Y3 each contains one or more methoxy or ethoxy groups) is used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a heat-sealing adhesive that provides good adhesion between metals and plastics, or between plastics.

(Technical background of the invention and its problems) Polyethylene,
Non-polar polymers such as polypropylene have many excellent properties such as moldability and electrical properties, and these plastics are used in a wide variety of applications due to the need to reduce the weight of products.0 Heat-sealing adhesives is a type of adhesive that is heated to a semi-molten state, and then adheres and hardens as the temperature of the hot water falls, and is used, for example, in vibration-damping steel plates for bonding metal and plastic, and in heat storage containers for air conditioners. . However, plastics generally have a drawback of poor adhesion, and adhesion between metals and plastics, or between plastics, has traditionally been a major problem.

For this reason, methods using polyurethane-based, polyester-based, or epoxy-based adhesives, methods using polyolefin grafted with maleic acid, etc. have been conventionally used. Furthermore, as seen in JP-A-56-194732, a method of providing a silane crosslinked polyolefin layer via an epoxy resin has also been proposed. however,
These conventional bonding methods have problems such as insufficient bonding strength, particularly low bonding strength at high temperatures, and lack of heat resistance.

(Objective of the Invention) The present invention focuses on the above points and provides a heat sealing adhesive that can be used in a wide range of applications by improving adhesiveness between metals and plastics, and between plastics, and improving heat resistance. The purpose is to

(Summary of the Invention) The present invention relates to a polyethylene grafted with 0.5 to 10% by weight of maleic acid and/or acrylic acid;
100 parts by weight of one or more of polypropylene, ethylene-vinyl acetate copolymer, and ethylene-ethyl acrylate copolymer, and 0.1 to 5 parts of a silane coupling agent.
The present invention relates to a heat-sealing adhesive formed by mixing parts by weight.

As the polyethylene in the present invention, any of low density polyethylene (including chain low density polyethylene), medium density polyethylene, and high density polyethylene can be used.

The amount of maleic acid and/or acrylic acid grafted onto polyethylene, polypropylene, ethylene-vinyl acetate copolymer, and ethylene-ethyl acrylate copolymer is preferably 0.5 to 10% by weight, and 0.5% by weight.
If it is less than t%, the adhesion will be poor, and if it exceeds 10% by weight, the heat resistance will be reduced (hereinafter, these grafted resins will be referred to as pace polymers).

The silane coupling agent of the present invention is Y.

Compounds having the structural formula X-8i-Y, having one or more carbon-carbon double bonds in X, and one or more methoxy or ethoxy groups in Y, -Y use.

Specifically, there are the following methacryloxysilanes and vinylsilanes.

C'H8 CjH* -OCj 0 0sHo S i (0O
Hs)a■ 0H.

CH2-0-00C5HaSi(00tHs)s0HM
-CH3i (00tHs)sCut -(!H8
i (00t H40CjHs )s Y
+These silane coupling agents are x-si-yt
Due to the carbon-carbon double bond of the X component represented by
It is thought that the adhesion between the resins forming the plastic is improved, and the X component reacts with the hydroxyl group on the metal surface, thereby improving the adhesion with the metal. The amount of the silane coupling agent added is preferably 0.1 to 5 parts by weight per 100 parts by weight of the base polymer. Addition amount is 0.
If it is less than 1 part by weight, heat resistance will be poor, and if it exceeds 5 parts by weight, no improvement in adhesion will be observed.

In addition, in the present invention, the temperature of 1 minute half-life is 100~
Adhesion is further improved by adding an organic peroxide within the range of 180°C.

For example, t-butylperoxyisobrobyl carb *-)
(158°C), benzoyl peroxide (130″C)
), 1,1-bis(t-butylperoxy)3,3,5
-) Limethylcyclohexane (148°C), 2,2-bis(t-butylperoxy)butane (160,5°C)
, dicumyl peroxide (171°C), etc. can be used (
(The temperature in parentheses is the temperature with a half-life of 1 minute) 0 The amount of organic peroxide added is preferably 0.05 to 3% by weight, and 0.05% by weight, based on the mixture of the pace polymer and the silane coupling agent. If it is less than % by weight, it is struck.

There is almost no effect of improving layer properties, and if it exceeds 3% by weight,
The resulting heat-sealing adhesive is cured and is extremely inflexible.

(Example of the invention) Examples of the present invention will be described in detail.

Example 1 Low density polyethylene 120 with melt index 1.0
Pellets were obtained by extrusion molding at ~170°C.

Triethoxyvinylsila 22 main part was mixed with the obtained pellets and extrusion molded again using an extruder to obtain a heat-sealing adhesive. This was molded into a film with a thickness of 30μ111 to prepare a test piece with a size of 2 cm×Bam.

Examples 2 to 7 and 9 are the formulations shown in Table 1, and Example 1.
Created in the same way. In Examples 8 and 10, test pieces were prepared in the same manner as in Example 1 using the formulations shown in Table 1, and then impregnated with the organic peroxides shown in Table 1.

Comparative Examples 1 and 3 to 6 were prepared in the same manner as in Example 1, and Comparative Example 2 was prepared in the same manner as in Example 8, with the respective formulations shown in Table 1.

For evaluation of adhesive strength, a test piece was sandwiched between a 1.5-thickness copper plate and a 2-thickness polypropylene plate, and the specimen was bonded at 150°C for 5 minutes at a pressure of 5 kg/ctl, then at 90° from room temperature.
A shear peeling test was conducted on each of C.
To evaluate the adhesive strength between plastics, a similar test was conducted by sandwiching a test piece between two polypropylene plates and adhering them in the same manner.

Examples 1-10 show good adhesive strength and heat resistance. In Examples 8 and 10, an organic peroxide was added to the formulation of Example 2.9, and the adhesion was even more excellent.

Comparative Example 1 uses carbon carbon 2 as a silane coupling agent.
Comparative Example 2 when using aminosilane that does not contain heavy bonds
, 3.6 is when no silane coupling agent is added.
Comparative Example 4 shows the case where an excessive amount of the silane coupling agent was added, and in both cases, the adhesive strength was significantly reduced.

Comparative Example 5 is a case in which the amount of grafted maleic acid is too small, and the adhesive strength is also significantly reduced in this case as well.

FIGS. 1 and 2 are graphs showing the adhesion strength of Examples and Comparative Examples over a wide temperature range. FIG. 1 shows the adhesion between copper and plastic, and FIG. 2 shows the adhesion between plastics. In the figure, "*" indicates the composition of Example 10, "0" indicates the composition of Example 9, and "X" indicates the composition of Comparative Example 6, and the test piece preparation method and test method were the same as described above.

Below margin *L: Manufactured by Shin-Etsu Chemical Co., Ltd. Product name: Silane-based cupa ring agent.

*2...Same as above, CH2-CH8i (OO2Hs)
s*3...Same as above, OR.

0Ht-0-00GjsHaSI(OCHs)s*4・
・・Same as above + H2N 02 H4NU Cs I (6
S! (QC! H3)! *5: Manufactured by Nippon Oil & Fats Co., Ltd.
Trade name: t-butylperoxyisopropyl carbonate (1 minute half-life, humidity 158°C) *6... Same as above, dicumyl peroxide (1 minute half-life, humidity 171°C) (Effects of the invention) Heat-sealing adhesives have excellent odor resistance and adhesive properties, and can be used in a wide range of humidity.

[Brief explanation of the drawing]

FIGS. 1 and 2 are graphs showing the relationship between humidity and adhesive strength in Examples and Comparative Examples of the present invention. °discharge °2'

Claims (1)

[Claims] 1. Maleic acid and/or acrylic acid from 0.5 to 1
0.1 to 5 parts by weight of a silane coupling agent to 100 parts by weight of one or more of 0% by weight grafted polyethylene, polypropylene, ethylene-vinyl acetate copolymer, and ethylene-ethyl acrylate copolymer. Heat sealing adhesive made by mixing. 2. The adhesive for heat sealing according to claim 1, which contains 0.05 to 3% by weight of an organic peroxide having a 1-minute half-life temperature of 100 to 180°C.