JPH03218813A - Bonding method for polyolefin resin molded material - Google Patents

Abstract

PURPOSE:To bond uniformly a polyolefin resin molded material in a short time by interposing a polyolefin resin bonded layer containing the specified quantity of carbon black, using a polyolefin resin molded material to be bonded containing the specified quantity of carbon black, applying high frequency voltage, melting the bonded layer and fusion welding the same with the molded material. CONSTITUTION:When a polyolefin resin molded material is bonded, a polyolefin resin bonded layer containing 10-25wt.% of carbon black is interposed between the polyolefin resin molded material and a material to be bonded with the same. As the polyolefin resin molded material to be bonded, a material containing 1-8wt.% of carbon black is used. The bonded layer is heat melted by applying high frequency voltage and fusion welded with the molded material. The fusion welding condition is different in different kinds of polyolefin resin, blending quantity of carbon black, thickness of the molded material and the like, and generally speaking, can be performed in the range of 10-10000MHz and for approximately 1-10 second fusion welding time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for adhering polyolefin resin molded articles. More specifically, the present invention relates to a bonding method using high-frequency dielectric heating that can be suitably used for bonding thick polyolefin-based fat-breakable molded products.

[Prior art and its problems] Bonding methods using high-frequency dielectric heating are widely used for thermal bonding of soft vinyl chloride resin sheets. This method uses a high-frequency electric field to heat the plastic internally, so it can uniformly heat plastics with appropriate dielectric constant (ε) and dielectric loss (tanδ), such as soft PVC resin, in a short time. This is a convenient adhesive method that can be fused. However, this method cannot be applied to polyolefin resins with small ε and tan δ because the amount of heat generated in a high-frequency electric field is small, and a thermal fusion method based on external heating has been used exclusively. The external heating method was not a satisfactory method because heating tends to be uneven, the time required is long, and the molded product is deformed. Therefore, attempts have been made to bond polyolefin resins using high-frequency dielectric heating. For example, a method is known in which a polyolefin molded product is blended with a large amount of carbon black. This method could not be said to be preferable as it caused deterioration in properties, impact resistance, etc. In order to improve this drawback, a method has been proposed in which a polyolefin resin blended with carbon black is used as an adhesive for polyolefin resin moldings (Japanese Patent Laid-Open No. 62-39221).
. This method is an excellent method in that it does not impair the inherent properties of the polyolefin resin molded product, but when the molded product becomes thick, it is difficult to bond it with sufficient adhesive strength. There was a problem with that.

[Problems to be Solved by the Invention] The present inventors have overcome these difficulties and have achieved high-frequency dielectric heating, even for thick molded products, while maintaining the inherent properties of polyolefin resin molded products. We investigated methods that would allow for stronger adhesion. As a result, a polyolefin resin containing an effective amount of carbon black for heat melting is used as the adhesive layer, and the polyolefin resin molding itself, which is the adherend, is made to a level that does not melt and deform the molded body when high frequency voltage is applied. It has been discovered that this objective can be achieved by blending a small amount of carbon black. Therefore, an object of the present invention is to provide a method for uniformly joining polyolefin resin molded articles in a short time.

[Means for Solving the Problems] When bonding polyolefin resin molded products, the present invention provides 10 to 25% by weight of carbon black between the polyolefin resin molded product and the molded product to be bonded thereto.
A polyolefin resin adhesive layer containing carbon black in a proportion of 1 to 8% by weight is interposed, and a polyolefin resin molded article containing carbon black in a proportion of 1 to 8% by weight is used, and bonding is performed by applying a high frequency voltage. The present invention relates to a method for adhering polyolefin resin molded articles, characterized by heating and melting a layer and fusing the layer to the molded article.

The method for adhering polyolefin resin molded products of the present invention can be used both for adhesion between polyolefin resin molded products and for adhesion between polyolefin resin molded products and molded products made of other materials. It is particularly suitable as a method for adhering polyolefin resin molded products together. As other materials to be bonded to the polyolefin resin, any material that can be laminated and integrated with the carbon black-containing polyolefin resin adhesive layer by a method such as coextrusion can be used, but in particular, polyester, polyamide,
Examples include thermoplastic resins such as , thermosetting resins such as phenolic resins, and paper.

In the present invention, the polyolefin resin used as the adherend molding and the adhesive layer refers to a homopolymer of olefin, a copolymer of olefins, a copolymer of olefin and a small proportion of vinyl monomer, or a copolymer of these. This is a composition containing a polymer of For example, ethylene, brobylene,
Homopolymers or copolymers of olefins such as 1-butene, 1-hexene, 1-octene, 4-methyl-1-bentene, butadiene, styrene, the above α-olefins and acrylic acid, methacrylic acid, maleic anhydride. Acids, unsaturated carboxylic acids such as monoethyl maleate or their anhydrides, metal salts of these unsaturated carboxylic acids, various esters of these unsaturated acids, and at least one vinyl monomer selected from vinyl acetate, etc. Examples include polymers. These copolymers may be random copolymers, block copolymers, or graft copolymers.

In addition, there are compositions containing these polymers that are blended with other thermoplastic resins and elastomers, and typical examples include crystalline polyolefin as a hard segment and olefin elastomer as a soft segment, such as This is an olefin thermoplastic elastomer made of a blend with partially crosslinked ethylene copolymer rubber.

In the present invention, a molded article of a polyolefin resin selected from the above-mentioned examples is bonded using a polyolefin-based resin selected from the above-mentioned examples as an adhesive layer. The polyolefin resin used as the adhesive layer contains carbon black in an amount of 10 to 25% by weight, preferably 12% by weight.
Contains ~20% by weight. If the amount of carbon plaque blended is less than the above range, the electrical properties required for high frequency dielectric heating will not be sufficiently improved and it will be difficult to achieve strong adhesion. On the other hand, if the blending amount is increased too much, the volume resistivity of the adhesive layer will become too small, and there is a risk that sparks will occur during fusion work using a high-frequency welder due to energization, making it impossible to obtain stable work. Since the layer surface becomes hard and brittle, it is necessary to use the above-mentioned blending ratio.

In the present invention, carbon black is also blended into the polyolefin resin molded product to be bonded. In the case of adhering polyolefin resin moldings together, carbon black must normally be added to both moldings to be bonded, but one of the moldings must contain the carbon black in advance by a method such as coextrusion. When the polyolefin resin adhesive layer is integrated, it is sufficient to fuse the adhesive layer that is integrated with the molded article with the other molded article, which is the adherend. There is no need to mix carbon black into the molded product, and it is only necessary to mix carbon black into the other molded product that is to be bonded to the molded product. In this case, the polyolefin resin adhesive layer is interposed in a state in which it is fused to one of the molded articles in advance. When adhering a polyolefin resin molded product to a molded product made of another material, a polyolefin resin adhesive layer containing carbon black is integrated with the molded product made of the other material, and this and carbon Fusion with a polyolefin resin molded product containing black. In any case, the amount of carbon plaque blended into the polyolefin resin molded article that is the adherend must not be so large as to substantially melt and deform the molded article when applying a high frequency voltage for adhesion. Also, since the amount should not be so large as to impair the mechanical properties and moldability of the polyolefin resin, it should usually be 8% by weight or less, preferably 6% by weight or less, but if the amount is too small. Since it is difficult to firmly bond a thick molded product by high-frequency dielectric heating, the content needs to be 1% by weight or more, preferably 2% by weight or more.

As the carbon black for the above-mentioned compounding, those manufactured by various methods such as furnace black, thermal black, acetylene black, and channel black can be used. Although the particle size and surface area are arbitrary, for example, particles with a particle size of about 10 to 50 mμ can be used. Carbon black can be blended into the polyolefin resin in any manner desired. For example, a method of directly kneading carbon black powder into a polyolefin resin, or a method of kneading a carbon black masterbatch prepared in advance into a polyolefin resin can be adopted.

Various additives may be added to the polyolefin resin molded product or adhesive layer. Such additives include antioxidants, weathering stabilizers, ultraviolet absorbers, pigments,
Dyes, lubricants, nucleating agents, antistatic agents, flame retardants, flame retardant aids, tackifying resins, etc. may be blended. Adhesion in the present invention is performed by interposing an adhesive layer between the molded article of the polyolefin resin and the molded article to be adhered, and heating and melting the adhesive layer by applying a high frequency voltage to fuse the adhesive layer. ．． The shape of the molded product is arbitrary, and the adhesive layer generally has a shape that matches the surface of the molded product to be adhered. Normally, a method is adopted in which an adhesive layer is sandwiched between these molded products and heat-sealed, but an adhesive layer is placed in advance on the other molded product that is in contact with the polyolefin resin molded product by coextrusion or double-layer injection. Alternatively, the adhesive layer may be formed by a method such as molding, and then the adhesive layer surface and the polyolefin resin molded product are overlapped and heat-sealed. As mentioned above, in this case, even if the former molded product is a polyolefin resin molded product, it is not necessarily necessary to incorporate carbon black into it. Note that since the adhesion of the present invention is based on the fusion of the adhesive layer, it is necessary to select an olefin resin that has good adhesion and compatibility with the molded article as the adhesive layer.

Welding conditions vary depending on various factors such as the type of polyolefin resin, the amount of carbon black blended, and the thickness of the molded product, but generally the welding time is about 1 to 10 seconds within the range of IO to 10,000 MHz. It can be done, but 1
,000 to 10,000 M}Iz is suitable, and in particular, the frequency around 2450 MHz, which is allocated in Japan as a frequency for microwave heating and is used in microwave ovens, is suitable. preferable.

[Effects of the Invention] Since the present invention uses a high-frequency welder for fusion, it is possible to achieve uniform fusion in a shorter time than with the external heating method that has conventionally been used exclusively for polyolefin resins. It has the advantage that it can be bonded neatly without causing large deformation of the attachment part. Furthermore, the present invention has the advantage that even thick products can be bonded with sufficient strength. Therefore, it can be applied to bonding various molded products of olefin polymers, such as bonding industrial sheets and bonding the ends of automobile exterior parts obtained by profile extrusion molding.

[Example] L example. 37.5 parts by weight carbon black masterbatch (carbon black concentration 40%, base polymer low density polyethylene) and 62.5 parts by weight Nucrel 1108c (
Manufactured by Mitsui DuPont Polychemical ■, ethylene-methacrylic acid copolymer, methacrylic acid content 11% by weight, M F
R 8 g/10 minutes) in a single-screw extruder (dice temperature 18
A polyolefin resin compound containing 15% by weight of carbon black was prepared by kneading at 0° C.), and this was further hot pressed to prepare an adhesive layer sheet having a thickness of 1 mm. This adhesive layer has an ε62. It had electrical characteristics of tan δ 2.4. Himilan 15548 K (manufactured by Mitsui DuPont Polychemical Co., Ltd.,
Zinc type ionomer MFR 2 g/10 minutes containing 3.6% carbon black
The above adhesive layer sheet was sandwiched between 2.4 MHz, tan δ 0.01) and a high frequency welder (KV-3000T silver 6 mm width, 40.4
6MHz), tuning dial 70, pressurization 3 kg/
cm", and oscillation was performed for 5 seconds. After cooling, the adhesive strength was evaluated by a shear peel test (peel speed 50 mm/min) using a tensile tester. Adhesion was performed with a shear peel strength of 52 kg/cm". It was a cohesive failure of the layer.

The same adhesive layer sheet as in Example 1 was used, and Nucrel 4 was used instead of Himilan 1554BK as the adherend sheet.
03 (ethylene/methacrylic copolymer manufactured by Mitsui DuPont Polychemical ■, methacrylic acid content 9% by weight, MF
R3g/10min) 57% by weight, Milastomer-8032N
A 2 mm thick sheet of composition (A) (ε2.8 at I MHz, tan δ 0.006) consisting of 38% by weight of olefinic thermoplastic elastomer (manufactured by Mitsui Petrochemical Industries, Ltd.) and 5% by weight of carbon black was used. Except for the above, three press sheets were thermally fused in the same manner as in Example 1. The shear peel strength of the fused surface was 37 kg/cm'', which again was due to cohesive peeling of the adhesive layer. .

Thickness 1 containing 5% by weight of carbon black created by mixing 12.5% by weight of the carbon masterbatch used in Example 1 and 87.5% by weight of Nucrel 1108C
A sheet was produced using a heat press with a diameter of mm. This sheet was used as an adhesive layer sheet (ε3.7 at I MHz, tan δ0.
003) was sandwiched between the same 2 mm thick sheets used in Example 1, and heat fusion was attempted using a high frequency welder (tuned dial 80 oscillations for 10 seconds) in the same manner as in Example 1, but no results were obtained. 《It did not fuse.

Composition (A) without using an adhesive layer sheet in Example 2
I tried to heat-seal the two sheets together using a high-frequency welder (tuned dial: 80 oscillations for 8 seconds), but no welding occurred.

In Example 2, 60% by weight of ethylene/methacrylic acid copolymer containing no carbon black and Milastomer-8032N40 were used instead of composition (A) as adherends.
Composition (B) (ε1.8 at I MHz) using wt%
, tan δ0. An attempt was made to heat-seal three press sheets using a high-frequency welder (tuned dial: 80 oscillations for 10 seconds) in the same manner as in Example 2, except that 0004) was used, but no welding occurred.

t Koudama A A sheet containing 5% by weight of carbon black used in Comparative Example 1 and having a thickness of 1 mm was prepared using a hot press. This sheet was used as an adhesive layer sheet (c3.7 at I MHz, tan δ
0. 003), sandwiched between 2 mm thick sheets of the same composition (A) as used in Example 2, and heated in the same manner as in Example 2 using a high frequency welder (tuning dial 80
I tried thermal fusion using a 10 second oscillation, but no fusion was achieved.

Claims (1)

[Claims] (1) When bonding polyolefin resin moldings, add 10 to 25% by weight of carbon black between the polyolefin resin molding and the molding to be bonded.
A polyolefin resin adhesive layer containing carbon black in a proportion of 1 to 8% by weight is interposed, and a polyolefin resin molded article containing carbon black in a proportion of 1 to 8% by weight is used, and bonding is performed by applying a high frequency voltage. A method for adhering a polyolefin resin molded article, the method comprising heating and melting a layer to fuse the layer to the molded article.