JPS6351127A - Method for bonding metal to polyolefin - Google Patents

Abstract

PURPOSE:To make it possible to easily and strongly bond metal to polyolefin by a method wherein the surface of the metal to be bonded is polished and, on the other hand, the surface of the polyolefin is polished and, after that, treated by heating heavily and the bonding between both the surfaces is done with the adhesive, which is selected from epoxy-based, urethane-based, silicone-based and cyanoacrylate-based adhesives. CONSTITUTION:The surface of metal to be bonded is polished in advance. On the other hand, the surface of polyolefin to be bonded is also polished and, after that, treated by heating heavily in advance, the treatment is done at a temperature as high as possible and for a period of time as short as possible for preventing the deformation of the materials to be bonded due to heat from occurring. The preferable temperature and period of time for said treatment are 500 deg.C or higher and about 0.5-10 seconds. After that, bonding is done at normal temperature by the ordinary bonding practice with at least one kind of adhesive, which is selected from the group consisting of epoxy-based, urethane-based, silicone-based and cyanoacrylate-based adhesives. The above-mentioned method may be applied to various metals as bonding object. Especially favorable adhesion is shown when iron, aluminum, copper, lead, titanium and alloys, main component of each of which is a metal element, and the like are adopted as the bonding object.

Description

[Detailed Description of the Invention] The present invention relates to a method for adhering metals and polyolefins. Recently, there has been an especially increasing demand for coating the outer and inner walls of products with a polyolefin layer that has excellent chemical resistance and corrosion resistance. For this coating, it is necessary to firmly bond the metal wall and the polyolefin, but as is well known, polyolefin is a material that is extremely difficult to bond, so there is a problem that it cannot be bonded with ordinary adhesives.

Conventionally, as a bonding method between metal and polyolefin, (1
1. Roughening the surface of the metal and polyolefin to be bonded, increasing the bonding area and increasing the anchoring effect, or (2)
Methods such as using a special real-melt adhesive have been proposed.

Solution Points to be solved: The method (1) above may provide a certain degree of adhesive strength if the surface treatment is done properly and sufficiently, but there are problems such as the need for a long time to perform sufficient surface treatment. There is a problem with workability. Regarding method (2) above, recently improved adhesives have been developed, but in any case, when using a hot melt adhesive, the adhesive is sandwiched between the metal and the polyolefin during bonding. In this state, it is necessary to maintain both in a state heated to a high temperature higher than the melting point of the adhesive for a certain period of time, and this heating may be difficult depending on the objects to be bonded.

In view of the above-mentioned conventional circumstances, there is a strong demand for the development of a method for easily and firmly adhering metals and polyolefins at room temperature, requiring only a light pretreatment.

In order to meet the above-mentioned needs, the present invention aims to meet the above-mentioned needs by polishing the surface of the metal to be bonded, and polishing the surface of the polyolefin and then subjecting it to intense heat treatment. , and then bonding the two surfaces together using at least one adhesive selected from the group consisting of epoxy, urethane, silicone, and cyanoacrylate adhesives. This is what we are trying to provide.

■ The surface of the metal to be bonded is polished, while the surface of the polyolefin to be bonded is polished and then subjected to intense heat treatment. and cyanoacrylate adhesives, and can be bonded at room temperature in a conventional bonding manner.

In the present invention, various metals can be bonded, but iron, aluminum, copper, lead, titanium, or alloys containing these metal elements as main components exhibit particularly good adhesion.

Polyolefins to be bonded include homopolymers and copolymers of α-olefins such as ethylene, propylene, and butene-1, such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, very low-density polyethylene, and linear Polyethylenes such as low-density polyethylene,
Various copolymers of ethylene and various copolymerizing agents other than α-olefins, such as polypropylene, polybutene-1, poly-4-methylpentene-1, ethylene-propylene copolymer, ethylene-butene-1 copolymer, Examples include ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, and ethylene-ethyl acrylate copolymer. The polyolefin referred to in the present invention may be crosslinked or non-crosslinked.

The crosslinked polyolefin has a gel fraction of 10% or more,
More preferably, a crosslinked polyolefin having a gel fraction of 50% or more is suitable. As such crosslinked polyolefins, a wide variety of conventionally known ones can be used. More specifically, an organic peroxide is added to the above polyolefin and crosslinked by heat treatment, a crosslinked polyolefin is obtained by irradiating the above polyolefin with an electron beam, or a water crosslinkable polyolefin is crosslinked. etc. can be exemplified.

In the present invention, the form of the metal and polyolefin to be bonded is not particularly limited, and may be in any form such as a film, sheet, or pipe.

In the present invention, the metal and polyolefin surfaces are first pretreated prior to adhesion.

Polishing of the metal surface is performed for the purpose of removing rust from the surface layer and adding irregularities to increase the effective bonding area. Any polishing method may be used as long as this objective is achieved, and it is preferable to uniformly polish the metal surface using, for example, an abrasive or polishing means with a grain size of No. 30 to No. 400 specified in JIS-R6001. As an abrasive material, abrasive cloth (JIS
-R6521), abrasive paper (JIS-R6252), abrasive belt (JIS-R6252), abrasive disc (JIS-R6252), abrasive disc (JIS-R6252), abrasive belt (JIS-R6252),
S-R6255) etc. can be used. If the abrasive grain size is finer than No. 400, the workability will be poor and it will be difficult to polish uniformly, and a sufficient effect may not be expected.
If it is rougher than No. 0, the metal may be damaged and workability may be poor, so be careful.

The surface of polyolefin is first polished, but the method can be the same as polishing metal surfaces, and in this case also JIS
It is preferable to uniformly polish the surface of the polyolefin using an abrasive material or a polishing means having a particle size of #30 to #400 based on -R6001.

Next, the polished polyolefin surface is subjected to ignition treatment. A wide range of known methods such as flame treatment and hot air treatment can be applied to this ignition treatment. Gas burners can be used for flame treatment, and hot jets can be used for hot air treatment.

When carrying out the ignition treatment, it is preferable to uniformly apply flame or hot air of at least 250° C. or higher to the surface of the polyolefin for at least 0.1 seconds or more to the extent that the surface of the polyolefin to be bonded is not burnt. This ignition treatment depends on the thickness, shape, etc. of the adherend, but in order to prevent deformation of the adherend due to heat, it is best to perform it at as high a temperature as possible and in a short time from the viewpoint of workability. It is practical, therefore, treatment with a heat source of 500° C. or higher for about 0.5 to 10 seconds is more preferable.

When the ignition temperature is lower than 250°C or the stress treatment time is 0.
If the time is less than 1 second, it is not preferable because it is difficult to expect the desired effect of the present invention.

In the present invention, the pretreated metal and polyolefin are then bonded together using the following adhesive. As an adhesive,
Epoxy adhesives, urethane adhesives, silicone adhesives, or cyanoacrylate adhesives may be used alone or in combination of two or more.

As the epoxy adhesive, a wide variety of conventionally known adhesives can be used, such as those containing a bisphenol A type epoxy resin, an amine curing agent, a polyamide resin or a polysulfide resin curing agent, etc. The bisphenol A type epoxy resin preferably has an epoxy equivalent of 140 to 300 and is liquid at room temperature.

In addition, as amine-based curing agents, aliphatic amines (primary,
(secondary and tertiary), aromatic amines, polyamide amines, and modified products thereof, among which those that are liquid at room temperature are preferred. Conventional fillers, colorants, reactive diluents, etc. can also be added to such epoxy adhesives. The epoxy adhesive is usually used by mixing Evokin resin and a curing agent immediately before bonding, and after bonding at room temperature, it may be heated at a relatively low temperature of 50 to 60° C. if necessary.

As the urethane adhesive, a wide variety of conventionally known adhesives can be used, such as those blended with polyisocyanate and polyol. The polyisocyanate is preferably one that is liquid at room temperature, and the polyol is preferably a polyol or polyurethane polyol that is liquid at room temperature. Conventional fillers, colorants, curing catalysts, etc. can also be added to such urethane adhesives. Like the epoxy adhesive, the urethane adhesive is used by mixing it with polyisocyanate toboriol immediately before bonding.

As the silicone adhesive, a wide range of conventionally known ones can be used, such as room temperature curing silicone adhesives,
It can be roughly divided into two-component type and one-component type.

The two-component type is a mixture of polysiloxane with rounded ends (reactive polysiloxane at the end) and a crosslinking agent such as tetraalconesilane or tetraalkyl titanate. ~ The molding is mainly made of tafolysiloxane containing acetoxy groups (acetic acid generating type), polysiloxane containing alkoxy groups (alcohol generating type), etc., and curing catalysts, fillers, etc. are added as appropriate. You can.

As the cyanoacrylate adhesive, a wide variety of conventionally known adhesives can be used, such as those containing α-cyanoacrylate as a main component. Examples of the α-cyanoacrylate ester include methyl α-cyanoacrylate, ethyl α-cyanoacrylate, and the like.

When bonding metal and polyolefin to each other using the above adhesive, it is sufficient to apply the above adhesive to one or both of the metal and polyolefin to be bonded at room temperature and bring them into contact. Pressure or heating may be applied as appropriate. The amount of adhesive that should be applied varies depending on the type of adhesive used, the form of the metal and polyolefin to be bonded, etc., but it cannot be generalized, but it is necessary to apply 0.01 to the surface to be bonded.
It is sufficient to apply the adhesive to a thickness of about 1@N. There is no particular restriction on the method of applying the adhesive, and a wide range of commonly used means can be employed.

According to the present invention, articles made of various metals, particularly iron, aluminum, copper, lead, titanium, or alloys containing these metal elements as main components, which are particularly frequently used in industry, and polyolefin are used. Since it can be easily and firmly bonded, the bonding method of the present invention can be used to protect the inner and outer walls of liquid transport pipes and liquid storage containers with polyolefin, to prevent rust in various industrial equipment, to manufacture metal-polyolefin composite materials, etc. It can be applied to

EXAMPLES The present invention will now be described in more detail with reference to Examples and Comparative Examples. In the following, unless otherwise specified, parts and percentages are
They each mean parts by weight and % by weight.

Examples 1 to 15, Comparative Examples 1 to 5 A metal sheet having the t, ti, and thickness shown in Table 1 and a polyolefin sheet having a thickness of 2 mm (each having a size of 1
1 Q, nx 1301m) was used as the object to be bonded.

For metal sheets, the surface is polished with 150 grit abrasive paper, while for polyolefin sheets, the surface is polished with 150 grit abrasive paper and then flame treated with a gas burner for about 5 seconds, so that both of the two sheets are coated. The two sheets were adhered by applying the adhesive shown in Table 1 and using the adhesion method shown in Table 1.

Note that in the comparative example, both sheets were not surface-treated.

After standing for 168 hours, the 2.11 peel adhesion strength of the resulting sheet laminate was determined by a T-peel test according to JIS K6854 (
However, the tensile speed was 2001 m/min), and the results are also shown in Table 1.

The materials used and the terms shown in Table 1 are as follows.

Polyolefin-1: 0.15 parts of dicumyl peroxide, 2.0 parts of vinyltrimethoxysilane, and 0.0 parts of dibutyl-tin-dilaurate per 100 parts of high-density polyethylene with a density of 0.945 and a melt index of 0.2.
05 parts, graft modified for about 2 minutes in an extruder temperature-controlled at 200°C, and then molded and crosslinked to obtain a crosslinking degree of 70%.
cross-linked polyethylene.

Polyolefin-2: polyethylene with a density of 0.945 and a melt index of 0.2.

Polyolefin-3: 170 per composition obtained by mixing 2.0 parts of dicumyl peroxide and 0.3 parts of antioxidant with 100 parts of low-density polyethylene having a density of 0.920 and a melt index of 1.0. Crosslinked polyethylene with a degree of crosslinking of 85% obtained by press molding and crosslinking at °C for 30 minutes.

Epoxy-1: Product name Arteco 35 manufactured by Alpha Giken Co., Ltd.
00° Urethane: Product name: Unibon 8000° Anno 7 Acrylate, manufactured by Sanyo Chemical Co., Ltd. Product name: Aron Alpha 232°, manufactured by Toagosei Co., Ltd. Silicone: Product name: KE67RTV, manufactured by Shin-Etsu Chemical Co., Ltd.

Epoxy-2 Product name Epicote 82 manufactured by Niji Engineering Chemical Co., Ltd.
8 and Asahi Kasei's product name AER Bar Toner L-220
A 100:58 mixture of

EVA: Ethylene-vinyl acetate copolymer with a melt index of 20 and a vinyl acetate content of 28%.

EEA: Ethylene-ethyl acrylate copolymer with a melt index of 18 and 20% ethyl acrylic acid.

EAA: Melt index 5, acrylic 8% ethylene-acrylic acid copolymer.

Hot press method: A film adhesive having a thickness of 0.4 mm is sandwiched between both adherends, and the adhesive is bonded by real pressing at 180° C. for 5 minutes.

Room temperature method: Adhesive is applied at room temperature and bonded by curing at room temperature.

Peeling condition: Excellent when the polyolefin adherend is broken.
Good for cohesive failure, interface! ll AI was shown as acceptable.

Claims (1)

[Claims] 1. When bonding metal and polyolefin, the surface of the metal to be bonded is polished, while the surface of the polyolefin is polished and then subjected to intense heat treatment, and then epoxy, urethane, silicone, and A method for adhering metal and polyolefin, which comprises adhering the two surfaces together using at least one adhesive selected from the group consisting of cyanoacrylate adhesives. 2. The bonding method according to claim 1, wherein the metal is at least one selected from the group consisting of iron, aluminum, copper, lead, titanium, or alloys containing these metal elements as main components.