JPH09136357A - Method for fusion of thermoplastic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently fuse a thermoplastic resin by using an element coated with a heat-resistant resin as a microwave heating element. SOLUTION: As a microwave heating element, iron (III) oxide and/or needle titanium oxide coated with a thermosetting heat-resistant resin are used. As a method for coating the heating element, the heat-resistant resin is dissolved in a solvent and after particles of the heating element are dispersed therein, they are filtered and dried and if necessary, cured by heating. As a method for dispersing this heating element coated with the heat-resistant resin in a thermoplastic resin, a powder of the thermoplastic resin and the heating element coated with the heat-resistant resin are melted by heating and mixed together. When the thermoplastic resin is fused, a dispersion wherein the heating element is dispersed in the thermoplastic resin is arranged in at least one side of the fused part. As only the part in which the heating element is arranged is heated by irradiation by microwave to melt the thermoplastic resin, only a part to be fused can be fused by arranging the heating element in only the part to be fused.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for fusing a thermoplastic resin. More specifically, the present invention relates to a method for fusing a thermoplastic resin, which comprises irradiating a thermoplastic resin molded product in which a specific heating element is dispersed with microwaves.

[0002]

2. Description of the Related Art Various methods have been proposed for connecting a molded article made of a thermoplastic resin such as a film, a plate, and a pipe, but the most effective method is to heat and fuse a molded article 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-2-261626, etc.) ) 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, but an effective heating element is not known, or microwaves are irradiated with high density, or the heating elements are dispersed in high concentration. If the fusion is to be carried out efficiently, an induced current is generated when the microwave is irradiated, and there is a problem that ignition may occur in some cases.

An object of the present invention is to provide a method for efficiently fusing a thermoplastic resin.

[0005]

[Means for Solving the Problems] The present inventors completed the present invention by intensively studying a method for solving the above problems and efficiently fusing a thermoplastic resin.

That is, the present invention relates to a method of fusing a thermoplastic resin by irradiating a molded product obtained by dispersing the microwave heating element in the thermoplastic resin with microwaves. The method for fusing a thermoplastic resin is characterized by using a material coated with.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The thermoplastic resin that can be fused in the present invention is not particularly limited, and any resin that can be heat-fused may be used. Specifically, polyvinyl alcohol, polyvinyl acetate, polyamide, polyethylene, polypropylene, or a polyolefin such as a copolymer of ethylene or propylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polymethylmethacrylate, or styrene, vinyl chloride. Examples thereof include copolymers such as methyl methacrylate and vinylidene chloride, and condensation-type engineering plastics such as polycarbonate, polyamide, polyester, polyimide, polyether, polyether ketone, and polyether ether ketone.

The shape of the thermoplastic resin to be fused and the molding method are not particularly limited, as is clear from the gist of the present invention.

In the present invention, various types of microwave heating elements can be used, and ferrite and acicular titanium oxide are exemplified as those effectively dispersed in a thermoplastic resin.

Ferrite tetroxide is preferred as the ferrite. Commercially available iron oxide black oxide can be used as it is, natural magnetite finely pulverized, iron calcined in air, iron (III) oxide reduced with hydrogen containing steam, Examples thereof include those obtained by finely pulverizing red hot iron with steam acting thereon, and the like. The particle size of such ferrosoferric oxide is 1000 μm
Below, those having a thickness of preferably about 0.01 to 100 μm are preferably used.

As the acicular titanium oxide, commercially available acicular titanium oxide is acicular titanium oxide having a minor axis length of 0.01 to 10 μm and an aspect ratio of 5 to 1000, such as magnesium and calcium. A metal oxide doped with a metal oxide, or a metal oxide doped with tin oxide, indium oxide, or the like to be made conductive, or a commercially available product can be used as it is. The crystal form of titanium oxide may be either rutile type or anatase type, but many are effective for anatase type, and it is necessary that the shape of the fine particles be acicular or columnar.

In the present invention, the heat-resistant resin used for coating the heating element cannot be specified as long as it does not fluidize when the thermoplastic resin used in dispersion is melted, but the coating is simple. A resin soluble in a solvent can be preferably used because it does not impair the performance of the heating element. It is particularly effective to use the thermosetting resin in the state of a prepolymer which can be used as a solvent. Specifically, the above-mentioned engineered plastic or the thermosetting resin described later is exemplified. Specifically, phenol resin, urea resin,
Melamine resin, unsaturated polyester resin, epoxy resin, silicon resin, polyurethane resin, diallyl phthalate resin, thermosetting polyimide, polycarbodiimide resin and the like can be used, and particularly preferably used as a solvent-soluble prepolymer.

The coating method is not particularly limited, but it is possible to dissolve the heat-resistant resin or its prepolymer in a solvent, disperse the particles of the heating element described above, filter, dry, and heat-cure if necessary. It is common. The solvent is not particularly limited as long as it can dissolve the heat resistant resin or its prepolymer. Examples thereof include water, alcohols, hydrocarbon compounds, halogenated hydrocarbons, esters, ethers and the like. The amount of coating is about 0.000001 to 0.1 g, preferably about 0.00001 to 0.01 g per 1 g of the heating element. It is also possible to mix and use a curing agent at the time of curing.

The method of dispersing the heating element coated with the heat resistant resin in the thermoplastic resin is not particularly limited, and any method can be used as long as it can be well mixed. For example, it is also possible to mix ferrosoferric oxide or acicular titanium oxide with a solution of a thermoplastic resin and mix them well by a known mixing method such as a ball mill or a homogenizer to disperse and then mold and dry. It is preferable to heat-melt and mix the resin powder and the heating element coated with the heat-resistant resin. Specifically, a heating element coated with a thermoplastic resin and a heat-resistant resin is mixed with a Henschel mixer or the like, and then heated and melted and mixed with an extruder, a Brabender, etc., and then pelletized to form a desired shape. It's easy.

Here, the ratio of the thermoplastic resin to the heating element is about 100: 1 to 100: 500 (weight ratio), preferably about 100: 5 to 100: 200 (weight ratio).

When fusing the thermoplastic resin, it is necessary to dispose at least one of the fusing parts in which the heating element is dispersed in the thermoplastic resin. Since only the portion including the heating element generates heat by irradiation with microwaves and melts the thermoplastic resin, by disposing the heating element only in the portion to be fused, only that portion can be fused. In some cases, it is also possible to dispose a heating element inside the thermoplastic resin molded body so that the heat from the heating element is conducted and melted on the surface.

The microwave used for irradiation can be heated to such an extent that the thermoplastic resin can be sufficiently fused with a wavelength and energy that is commercially available for household microwave ovens, and is several gigahertz (usually 2.45 gigahertz). The microwave of the frequency of is available, and the energy of several KW / 1 Kg is sufficient.

[0018]

The present invention will be further described with reference to examples.

Example 1 A solution prepared by dissolving 30 g of iron trioxide (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) and 1 g of a melamine resin precursor (adduct of melamine and formalin of about 1: 2) in 50 ml of tetrahydrofuran for 1 hour. After dispersion under stirring, filtration and drying, the coating was carried out at 200 ° C. for 10 minutes while flowing with heated nitrogen. 15 g of iron tetroxide coated with melamine on the surface thus obtained and 20 g of high density polyethylene (brand name: Staflen E792) manufactured by Nippon Petrochemical Co., Ltd. were used at Labo Plastomill R type (manufactured by Toyo Seiki Seisakusho Co., Ltd.) at 240 ° C.
Mixed well. This operation was repeated to obtain about 100 g of the mixture. The mixture is press molded at 220 ° C to a thickness of 1
I made a mm sheet. On the other hand, a high-density polyethylene manufactured by Nippon Petrochemical Co., Ltd. (brand name: Staphlen E801) was similarly press-molded to obtain a sheet having a thickness of 4 mm.

90 mm × 1 mixed with ferrosoferric oxide
The sheet was cut into a sheet of 60 mm, and the high-density polyethylene was cut into a piece of 100 mm × 170 mm, and the sheets were stacked at 230 ° C. and press-molded to form a composite sheet having a thickness of 3 mm. When a sheet made by the same operation was cut in the middle, the thickness of the polyethylene part and the ferrosoferric oxide-containing part was 2.4 mm and 0.8 m.
It was m thick.

The composite sheet thus obtained and a sheet of high-density polyethylene having a thickness of 4 mm were superposed so as to contact each other on the side containing triiron tetraoxide, and put in a commercially available microwave oven (Toshiba microwave oven ERT-540F manufactured by Toshiba). When it was irradiated with waves for 3 minutes and taken out, it was found to be sufficiently fused.

Example 2 The same procedure as in Example 1 was carried out except that the amount of the coated iron oxide tetroxide was 25 g, and it was sufficiently fused by irradiation for 2 minutes.

COMPARATIVE EXAMPLE 1 The same procedure as in Example 1 was carried out except that ferrosoferric oxide was used as it was without being coated with melamine, but fusion was not sufficient in 3 minutes and sufficient strength was obtained by irradiation for 5 minutes. .

Comparative Example 2 The same procedure as in Example 2 was carried out except that iron tetroxide was used as it was without being coated with melamine.

[0025]

EFFECT OF THE INVENTION By carrying out the method of the present invention, a thermoplastic resin can be easily fused and is industrially extremely valuable.

Claims (3)

[Claims] 1. A method of fusing a thermoplastic resin by irradiating a molded product obtained by dispersing a microwave heating element in a thermoplastic resin with microwaves, wherein the microwave heating element is coated with a heat-resistant resin. What is used is a method for fusing a thermoplastic resin. 2. The method according to claim 1, wherein the microwave heating element is ferric oxide and / or acicular titanium oxide. 3. The heat resistant resin is a thermosetting resin.
The method described in.