JPH10315336A - Method for fusion bonding of resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently fusion bond a thermoplastic resin molding without deformation by emitting a microwave to the molding obtained by molding thermoplastic resin composition containing microwave heating medium and colored to black by carbon black having specific surface area. SOLUTION: In the case of fusion bonding thermoplastic resin molding, microwave heating medium is contained in thermoplastic resin of at least one of adhered part in the molding. As the medium, ferrite effective by dispersing it in thermoplastic resin or needle titanium oxide is exemplified. Carbon black used in the case of coloring it to black has its specific surface area of 200 m<2> /g or less or particularly preferably 150 m<2> /g or less. Here, the specific surface area is measured by a nitrogen adsorption process. As the microwave, it sufficiently has a wavelength and energy of the degree used for domestic microwave oven, and it can heat it to 100% or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for fusing a resin molded product by microwaves. More specifically, the present invention relates to a method for fusing a resin molded product that irradiates a microwave to a resin molded product satisfying specific conditions.

[0002]

2. Description of the Related Art Various methods have been proposed for connecting molded products formed of a thermoplastic resin such as films, plates, pipes and the like, but the most effective method is to heat and fuse molded products made of the same material. How to As a heating method, in addition to a method in which a high-temperature substance is brought into contact with a portion to be fused, a non-contact method in which heat is generated by irradiating a microwave or the like (JP-A-3-186690, JP-A-2-186690).
No. 261626). In particular, the latter non-contact method is considered to be an effective method.

[0003]

The method of irradiating microwaves is considered to be excellent, and if a metal oxide is used as a heating element, it can be efficiently heated and fused. However, when colored black, there is a problem that, depending on the conditions, heat is generated partially during the irradiation, and foaming or fuming is observed, and the portion is largely deformed.

Accordingly, an object of the present invention is to provide a method for efficiently fusing a thermoplastic resin molded article without deformation.

[0005]

Means for Solving the Problems The present inventors have solved the above-mentioned problems and have intensively studied a method for efficiently fusing a thermoplastic resin molded article, and completed the present invention.

That is, in the method for fusing a resin molded article of the present invention, a molded article obtained by molding a thermoplastic resin composition containing a microwave heating element and colored black with carbon black is irradiated with microwaves. In the method for fusing a thermoplastic resin molded article, carbon black having a specific surface area of 200 m ² / g or less is used for coloring.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the thermoplastic resin is not particularly limited and may be any resin that can be heat-fused.
Specifically, polyvinyl alcohol, polyvinyl acetate,
Polyamide such as polyamide, polyethylene, polypropylene, or copolymer of ethylene, propylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polymethyl methacrylate, or styrene, vinyl chloride, methyl methacrylate, copolymer such as vinylidene chloride, Polycarbonate, polyamide, polyester, polyimide, polyether, polyetherketone,
Examples include condensed engineering plastics such as polyetheretherketone.

The shape of the thermoplastic resin molded article to be fused,
There is also no particular limitation on the molding method, as is clear from the gist of the present invention.

In the present invention, various types of microwave heating elements can be used. Ferrite and acicular titanium oxide are exemplified as those effective when dispersed in a thermoplastic resin. Ferrite is preferably ferric oxide. Commercially available iron tetroxide can be used as it is, and natural magnetite is finely pulverized, iron is calcined in air, iron (III) is reduced with hydrogen containing water vapor, Examples thereof include those synthesized by finely pulverizing, for example, a material obtained by applying steam to red-hot iron.
The particle diameter of the triiron tetroxide is preferably 1000 μm or less, preferably about 0.01 to 100 μm. As the acicular titanium oxide, a commercially available one can be used. The acicular titanium oxide has a minor axis length of 0.01 to 10 μm and an aspect ratio of 5 to 1000, and may include other metals such as magnesium and calcium. An oxide-doped one, or a conductive one doped with tin oxide, indium oxide, or the like, or a commercially available one can be used as it is. As the crystal form of titanium oxide, rutile type,
Either anatase type may be used, but many are effective for the anatase type, and the shape of the fine particles needs to be acicular or columnar.

Here, the ratio of the thermoplastic resin to the microwave heating element is determined according to the resin composition used for the portion to be heated.
The weight ratio is about 100: 1 to 100: 500, preferably about 100: 10 to 100: 200.

In the present invention, the method of incorporating the microwave heating element into the thermoplastic resin is not particularly limited, and any method may be used as long as it can be mixed well. For example, it is common to simultaneously perform dispersion and granulation using an ordinary extruder, and it is also possible to use a device such as a twin-screw extruder that is more efficient in dispersing as an extruder. It is also possible to use a Henschel mixer in advance, or use a device such as Brabender that performs melting and mixing more efficiently.

At the time of fusing a thermoplastic resin molded article, it is necessary to arrange a thermoplastic resin containing a heating element in at least one of the bonding portions in the molded article. Since only the portion including the heating element generates heat by microwave irradiation and melts the thermoplastic resin, only the portion where the heating element is desired to be bonded can be fused by disposing the heating element only.
In some cases, it is also possible to arrange a heating element inside the thermoplastic resin molded article so that heat from the heating element is conducted and melted on the surface.

What is important in the present invention is that the carbon black used for coloring black has a specific surface area of 200 m.
² / g or less, particularly preferably 150 m ² / g or less. Here, the specific surface area is measured by a nitrogen adsorption method. When carbon black having a specific surface area of more than 150 m ² / g is used, there is a problem that, when irradiated with microwaves, heat is partially generated and foams, or smoke is generated to greatly deform. As the carbon black satisfying such conditions, carbon blacks having various specific surface areas are commercially available, and among them, those having a small specific surface area and satisfying the above conditions may be selected. The addition amount of carbon black is preferably 0.01 to 10% by weight of the thermoplastic resin.

As microwaves, wavelengths and energies of the order used in microwave ovens for home use are sufficient for 100 microwaves.
It can be heated to a high temperature of ℃ or more. In general, a microwave having a frequency of several gigahertz can be used, and an energy of about several KW per kg of the molded product is sufficient. If the object to be heated is small, it can be heated to 100 ° C. or higher by placing it in a commercially available microwave oven and irradiating microwaves for several seconds to several minutes.

[0015]

The present invention will be described more specifically with reference to the following examples.

EXAMPLE 1 15 g of triiron tetroxide (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) and a high-density polyethylene manufactured by Nippon Petrochemical Co., Ltd. (brand name Staphrene E)
792) 20 g of carbon black (BP-460) manufactured by Cabot Specialty Chemicals, Inc.
6 g of Labo Plastomill R type (Toyo Seiki Seisakusho Co., Ltd.)
Was mixed well at 240 ° C. This operation was repeated to obtain about 100 g of the mixture. The mixture was pressed at 220 ° C. to make a 1 mm thick sheet. On the other hand, high-density polyethylene manufactured by Nippon Petrochemical Co., Ltd.
1) 20 g and 0.6 g of carbon black (BP-460) manufactured by Cabot Specialty Chemicals, Inc.
Were similarly mixed and press-molded to obtain a sheet having a thickness of 4 mm.

The sheet of 1 mm thickness mixed with triiron tetroxide is cut out to a size of 90 mm × 160 mm, and the sheet of 4 mm thickness mixed with carbon black to the high density polyethylene is cut out to a size of 100 mm × 170 mm. The sheets were stacked and pressed at 230 ° C. to form a composite sheet having a thickness of 3 mm. When the sheet made by the same operation was cut in the middle, the thickness of the polyethylene portion and the portion containing triiron tetroxide were 2.4 mm and 0.8 mm, respectively.

Immediately after molding using the composite sheet thus obtained, the above-mentioned sheet having a thickness of 4 mm is overlapped so as to be in contact with the ferric oxide containing portion, and placed on a commercially available microwave oven (Toshiba microwave oven ERT-540F manufactured by Toshiba). When microwaves were applied for 3 minutes and taken out, they were sufficiently fused and the surface of the sheet was not deformed at all. The specific surface area of this carbon black was 84 m ² / g.

Comparative Example 1 The procedure of Example 1 was repeated except that BP-1300 manufactured by Cabot Corporation was used as the carbon black. The sheet containing no ferric oxide was partially deformed. The specific surface area of this carbon black was 560 m ² / g.

Example 2 The procedure of Example 1 was repeated except that polypropylene homopolymer manufactured by Mitsui Toatsu Chemicals, Inc. was used as the resin and BP-1200 manufactured by Cabot Corporation was used as the carbon black. However, when the irradiation time was set to 4 minutes, the sheet was sufficiently bonded and the surface of the sheet was not deformed at all.
The specific surface area of this carbon black is 138 m ² / g
Met.

Comparative Example 2 The procedure of Example 1 was repeated, except that acetylene black was used as carbon black. One minute after the start of irradiation, smoke was emitted from at least one place. After a lapse of 2 minutes, the test was stopped because the part that ignited fired. The specific surface area of this carbon black was 285 m ² / g.

[0022]

According to the present invention, a thermoplastic resin molded article can be easily and efficiently fused without deformation, which is extremely valuable industrially.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C08L 101/00 C08L 101/00 // C08J 5/12 C08J 5/12 B29K 101: 12 507: 04 B29L 9:00 (72) Inventor Shinichi Kondo 5-14-31 Shodo, Sakae-ku, Yokohama-shi, Kanagawa

Claims (2)

[Claims] 1. A method for fusing a thermoplastic resin molded article by irradiating a microwave to a molded article obtained by molding a thermoplastic resin composition containing a microwave heating element and colored black with carbon black. A method of fusing a resin molded product, wherein the carbon black has a specific surface area of 200 m ² / g or less. 2. The method according to claim 1, wherein the microwave heating element is acicular titanium oxide and / or triiron tetroxide.