JP2842914B2 - Bonding method of polyolefin resin molding - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for bonding a polyolefin resin molded article. More specifically, the present invention relates to a bonding method using high-frequency dielectric heating that can be suitably used for bonding a thick polyolefin resin molded product.

[Conventional technology and its problems] The bonding method using high-frequency dielectric heating is widely used for thermal bonding of a soft vinyl chloride resin sheet. This method is based on the internal heating method of plastic in a high-frequency electric field,
It is a convenient bonding method that can be uniformly heat-sealed in a short time to plastics having an appropriate dielectric constant (ε) and dielectric loss (tan δ), such as soft vinyl chloride resin. However, this method cannot be applied to a polyolefin resin having a small ε or tan δ due to a small amount of heat generated in a high-frequency electric field, and a heat fusion method by external heating has been used exclusively. The external heating method is not satisfactory because the heating tends to be uneven and the required time is long, or the molded product is deformed. Attempts have been made to bond polyolefin resins by high-frequency dielectric heating. For example, a method is known in which a large amount of carbon black is blended into a polyolefin molded product, but the above blending deteriorates the fluidity at the time of molding, impairs the appearance of the molded product, and deteriorates the mechanical properties of the molded product. It could not be said to be a preferable method because properties and impact resistance were reduced. In order to improve this drawback, a method has been proposed in which a polyolefin resin containing carbon black is used as an adhesive for a polyolefin resin molded product (Japanese Patent Application Laid-Open No. 62-39221). This method is excellent in that it does not impair the inherent properties of the polyolefin-based resin molded product, but it is difficult to adhere the molded product with sufficient adhesive strength when the molded product becomes thick. There was a disadvantage that it is.

[Problems to be Solved by the Invention] The present inventors have overcome the above-mentioned drawbacks, and have high-frequency dielectric heating even with a thick molded product while maintaining the inherent characteristics of the polyolefin resin molded product. The method which can adhere more firmly was examined. As a result, a polyolefin resin blended with an effective amount of carbon black for heating and melting is used as the adhesive layer, and the polyolefin resin molded article itself, which is the adherend, is not melted and deformed when a high-frequency voltage is applied. It has been found that the purpose can be achieved by adding a small amount of carbon black. Therefore, an object of the present invention is to provide a method for uniformly joining a polyolefin resin molded article in a short time.

[Means for Solving the Problems] In the present invention, when bonding a polyolefin-based resin molded product, carbon black is added at a ratio of 10 to 25% by weight between the polyolefin-based resin molded product and the molded product to be bonded. The adhesive layer is heated by applying a high-frequency voltage while using a polyolefin-based resin molded article to be adhered with carbon black at a ratio of 1 to 8% by weight as a polyolefin-based resin molded article to be adhered. The present invention relates to a method for bonding a polyolefin-based resin molded product, which is melted and fused with the molded product.

The bonding method of the polyolefin resin molded article of the present invention,
It can be used for both bonding of polyolefin resin moldings and bonding of polyolefin resin moldings to moldings made of other materials, but is particularly suitable as a bonding method for polyolefin resin moldings. . As the other material to be bonded to the polyolefin resin, any method can be used as long as it can be laminated and integrated with a polyolefin resin adhesive layer containing carbon black by a method such as co-extrusion, and particularly, polyester, polyamide, And the like, a thermosetting resin such as a phenolic resin, and paper.

In the present invention, the polyolefin-based resin used as the adherend molded article and the adhesive layer refers to an olefin homopolymer, a copolymer of olefins, a copolymer of olefin and a small proportion of a vinyl monomer, or a copolymer thereof. It is a composition containing the polymer of. For example, homopolymers or copolymers of olefins such as ethylene, propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, butadiene, styrene, and the above-mentioned α-olefin and acrylic acid, methacrylic acid Carboxylic acid or anhydride thereof, such as maleic anhydride, maleic anhydride, monoethyl maleate, etc., metal salts of these unsaturated carboxylic acids, various esters of these unsaturated acids, vinyl acetate and the like. A copolymer with a monomer can be exemplified. These copolymers may be a random copolymer, a block copolymer or a graft copolymer.

Further, as a composition containing these polymers, there is a blend of other thermoplastic resins and elastomers, typical of which are crystalline polyolefin as a hard segment, olefin-based elastomer as a soft segment, for example, An olefinic thermoplastic elastomer made of a blend with a 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 resin selected from the above-mentioned examples as an adhesive layer. The polyolefin resin used as the adhesive layer contains 10 to 25% by weight of carbon black, preferably 12 to 20% by weight.
% By weight. If the amount of carbon black is less than the above range, the improvement of the electrical characteristics required for high-frequency dielectric heating is insufficient, and it is difficult to adhere strongly. On the other hand, if the compounding amount is increased too much, the volume resistivity of the adhesive layer becomes too small, and there is a risk that a spark that is energized during the welding operation by the high-frequency welder occurs and a stable operation cannot be obtained, and The disadvantage that the surface of the adhesive layer becomes hard and brittle also appears, so it is necessary to set the mixing ratio as described above.

In the present invention, carbon black is also blended in the polyolefin resin molded article to be bonded. In the case of bonding between polyolefin resin molded products,
Normally, carbon black must be blended into both molded products to be bonded, but when a polyolefin resin adhesive layer containing the carbon black is integrated into one of the molded products in advance by a method such as co-extrusion. It is only necessary to fuse the adhesive layer integrated with the molded article to the other molded article as the adherend, so that carbon black is contained in the molded article integrated with the adhesive layer. There is no need to mix the carbon black, and it is sufficient to mix the carbon black only in the other molded product to be adhered thereto. In this case, the polyolefin-based resin adhesive layer is interposed in a state in which the polyolefin-based resin adhesive layer is previously fused to one molded product.

In the case of bonding between a polyolefin-based resin molded article and a molded article made of another material, a polyolefin-based resin adhesive layer containing carbon black is integrated with a molded article made of another material, and this and carbon black are bonded together. The contained polyolefin resin molded article is fused.

In any case, the amount of carbon black to be incorporated into the polyolefin resin molded article as the adherend should not be so large that the molded article is substantially melt-deformed when a high-frequency voltage for adhesion is applied. In addition, since the amount should not be so large as to impair the mechanical properties and moldability of the polyolefin resin, it is usually required to be 8% by weight or less, preferably 6% by weight or less, but the amount is too small. It is difficult to adhere firmly by high-frequency dielectric heating in a molded product having a large thickness, so that it is necessary to be 1% by weight or more, preferably 2% by weight or more.

As the carbon black for the above-mentioned compounding, those produced 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, those having a particle size of about 10 to 50 mμ can be used. The method of blending the carbon black with the polyolefin resin can be arbitrarily determined. For example, a method of kneading carbon black powder directly into a polyolefin resin or a method of kneading carbon black powder into a polyolefin resin using a previously prepared carbon black masterbatch can be adopted.

Various additives may be blended in the molded product of the polyolefin resin or the adhesive layer. Such additives include antioxidants, weather stabilizers, ultraviolet absorbers, pigments, dyes, lubricants, nucleating agents, antistatic agents, flame retardants, flame retardant auxiliaries, tackifying resins, and the like. Is also good.

The bonding in the present invention is performed by interposing an adhesive layer between the molded product of the polyolefin-based resin and a molded part to be bonded thereto and applying a high-frequency voltage to heat-melt and fuse the adhesive layer. . The shape of the molded product is arbitrary, and an adhesive layer having a shape conforming to the surface to be adhered of the molded product is generally used. Normally, a method in which an adhesive layer is sandwiched between the molded products and heat fusion is adopted, but the other molded product to be bonded to the polyolefin resin molded product,
A method in which an adhesive layer is formed in advance by a method such as coextrusion or two-layer injection molding, and the surface of the adhesive layer and a polyolefin-based resin molded product are overlapped and heat-sealed may be adopted. As described above, in this case, even if the former molded product is a polyolefin-based resin molded product, it is not always necessary to mix carbon black therein. Incidentally, the adhesion of the present invention,
Since it is based on the fusion of the adhesive layer, it is necessary to select an olefin-based resin having good compatibility with the molded product and having good adhesion.

The fusion conditions vary depending on various factors such as the type of polyolefin resin, the amount of carbon black, and the thickness of the molded product, but are generally in the range of 10 to 10,000 MHz.
It can be performed in welding time of about 2 seconds, but 1,000 to 10,000
A frequency in the microwave region of 0 MHz is preferred, and is particularly allocated to Japan as a frequency for microwave heating,
A frequency around 2450 MHz used in microwave ovens is preferred.

[Effects of the Invention] Since the present invention is fusion using a high-frequency welder, it is possible to perform uniform fusion in a short time as compared with an external heating method that has been exclusively used in the conventional polyolefin resin. There is an advantage that it can be adhered neatly without major deformation of the attachment part. Further, according to the present invention, there is an advantage that even a thick product can be bonded with sufficient strength. Therefore, the present invention can be applied to the bonding of various molded products of an olefin polymer, for example, the bonding of industrial sheets and the terminal bonding of automotive exterior parts obtained by profile extrusion.

Example 1 Example 1 37.5 parts by weight of carbon black masterbatch (carbon black concentration 40%, base polymer low density polyethylene) and 62.5 parts by weight of Nucrel 1108C (manufactured by Mitsui-Dupont Polychemical Co., Ltd., ethylene-methacrylic acid) The polymer, methacrylic acid content 11% by weight, MFR 8g / 10min) was kneaded with a single screw extruder (die temperature 180 ° C) to prepare a polyolefin resin compound containing 15% by weight of carbon black. The sheet was further hot-pressed to form an adhesive layer sheet having a thickness of 1 mm. This adhesive layer had electrical characteristics of ε62 and tan δ2.4 at 1 MHz. Separately, Himilan 1554BK (manufactured by DuPont-Mitsui Polychemicals Co., Ltd., zinc type ionomer containing 3.6% carbon black, MFR
2g / 10min) 2mm thick sheet (ε2.4 at 1MHz, tanδ 0.0
1) High frequency welder (KV-3000T silver 6mm width, 40.4mm, manufactured by Seidensha Electronics Co., Ltd.)
6MHz) using tuning dial 70, pressurization 3kg / cm ² , oscillation 5
Fused in seconds. After cooling, the fusion strength was evaluated by a shear peel test (peel rate: 50 mm / min) using a tensile tester. Cohesive failure of the adhesive layer was observed at a shear peel strength of 52 kg / cm ² .

Example 2 The same adhesive layer sheet as in Example 1 was used. As an adherend sheet, instead of Himilan 1554bk, Nuclell 403 (ethylene-methacrylic acid copolymer, methacrylic acid content, manufactured by Mitsui / DuPont Polychemical Co., Ltd.) was used. 9% by weight, MFR3g / 10
Composition) (A) consisting of 57% by weight, 38% by weight of Mirastomer 8032N (olefin thermoplastic elastomer manufactured by Mitsui Petrochemical Industries, Ltd.) and 5% by weight of carbon black (2 mm thick sheet (ε2. 8, tan δ 0.006), except that three press sheets were heat-sealed in the same manner as in Example 1. The shear peel strength of this fused surface was 37 kg / cm ² , which was also the cohesive peel of the adhesive layer.

Comparative Example 1 12.5% by weight of the carbon master batch used in Example 1
And 57.5% by weight of carbon black prepared by kneading 87.5% by weight of Nucrel 1108C with a hot press having a thickness of 1 mm. This sheet was used as an adhesive layer sheet (ε3.7 at 1 MHz, tan δ 0.003), sandwiched between sheets having the same thickness of 2 mm as used in Example 1, and a high-frequency welder (tuned dial 80) was used in the same manner as in Example 1. Attempted thermal fusion at an oscillation of 10 seconds), but no fusion was achieved.

Comparative Example 2 In Example 2, only two sheets of the composition (A) were laminated without using the adhesive layer sheet, and heat-sealed with a high-frequency welder (tuning dial 80 oscillation 8 seconds), but no fusion was performed. Was.

Comparative Example 3 In Example 2, a composition (B) (60% by weight of an ethylene / methacrylic acid copolymer containing no carbon black and 40% by weight of a milastomer 8032N) instead of the composition (A) was used as the adherend. Three press sheets were heat-sealed with a high-frequency welder (tuning dial 80 oscillation 10 seconds) in the same manner as in Example 2 except that ε1.8 and tanδ 0.0004 at 1 MHz were used, but no fusion was performed. Was.

Comparative Example 4 A sheet was formed by a 1 mm-thick hot press containing 5% by weight of carbon black used in Comparative Example 1. This sheet was used as an adhesive layer sheet (ε3.7 at 1 MHz, tanδ 0.003), and the thickness of the same composition (A) as used in Example 2 was used.
Heat fusing was performed with a high-frequency welder (tuning dial 80 oscillation 10 seconds) as in Example 2, but no fusing occurred.

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Claims (1)

(57) [Claims] 1. A method for bonding a polyolefin-based resin molded article to a polyolefin-based resin molded article and a polyolefin-based resin-containing article containing 10 to 25% by weight of carbon black between the polyolefin-based resin molded article and the molded article to be bonded. The adhesive layer is heated and melted by applying a high-frequency voltage, using a polyolefin-based resin molded article of the adherend containing 1 to 8% by weight of carbon black as an adherend. A method for bonding a polyolefin-based resin molded product, characterized by fusing with a resin.