JPH04255331A - Manufacture of vinyl chloride foam - Google Patents

Abstract

PURPOSE:To attempt to shorten manufacturing time of a vinyl chloride foam with a thick thickness and a uniform cell structure by performing heating process for foaming by means of a microwave. CONSTITUTION:This foam consists of a polyvinyl chloride resin, a crosslinking agent, a plasticizer, a stabilizer, a foaming agent, etc., and covers a wide range from a hard type to a soft type. For example, a foaming compsn. such as a polyvinyl chloride resin 1, a foaming agent 2 and a solvent 3 are simultaneously fed in a closed kneader 4. Then, this compsn. is fed in an extruder 5. Thereafter, it is fed into a specified mold 6 and is molded while it is heated. In this case, the mold 6 has a structure irradiated with a microwave and the outer peripheral face and then, the central part of the foaming compsn. are irradiated with the microwave. The foaming time is made a half or shorter by this method and a foam with a thickness of 20-30mm and a uniform cell structure is obtd.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing vinyl chloride foams, particularly thick-walled products, in a short time.

0002

[Prior Art] Conventional methods for producing vinyl chloride foam are disclosed in Japanese Patent Publication No. 46-2184 and Japanese Patent Publication No. 63-757.
4, Japanese Patent Publication No. 53-7944, etc. are known.

0003

[Problems to be Solved by the Invention] However, the thickness of the foam produced by this type of method can only be about 10 mm due to poor heat conduction and scorch generation, and the production time is about 10 mm. It took a long time and the equipment was huge.

0004

[Means for Solving the Problem] In order to eliminate such drawbacks, the present invention uses ultrasonic waves to quickly and uniformly heat the inside of the mold not only on the surface but also on the center of the foam. Thick material with uniform cells, e.g. thickness of about 20-5
We propose a method that can produce foams of 0 mm in a short time, about 1/2 to 1/5 of the time required by conventional methods.

[0005]

EXAMPLE Hereinafter, an example of the method for producing a vinyl chloride foam according to the present invention will be described in detail with reference to the drawings. That is, FIG. 1 is a block diagram showing the manufacturing process, which is a method in which a crosslinked polyvinyl chloride foam is heated in a mold using microwaves to form a foam to a predetermined magnification.

To explain further, the polyvinyl chloride foam of the present invention mainly consists of a polyvinyl chloride resin, a crosslinking agent, a plasticizer, a stabilizer, a foaming agent, etc., and has adhesive properties during crosslinking heat treatment to other surface materials. In addition to directly gluing them together, 10 to 6
This is a foam that is approximately 0 times larger. To explain further, the polyvinyl chloride resin is composed of a polymer of vinyl chloride alone and a copolymer of vinyl chloride with vinyl acetate, acrylic ester, vinyl ether, vinyl ester, ethylene, etc. Note that the viscosity of the polyvinyl chloride resin can be reduced by changing the molecular weight.

The crosslinking catalyst is a quaternary ammonium salt or the like, and the amount added is 0.01 to 5 parts by weight per 100 parts by weight of the vinyl chloride resin. Further, as a crosslinking catalyst, it is preferable to use only a quaternary ammonium salt and other crosslinking aids. Examples of crosslinking aids include metal salts of polycarboxylic acids having two or more carboxyl groups, and epoxy resins. is preferred.

100 as a blowing agent for vinyl chloride foam
Compounds that decompose at ~250°C and generate gas, such as azodicarbonamide, are preferred for closed cell structures, while aluminum hydroxide (250~350°C) and zinc borate (330°C) are preferred for open cell foam structures. used to form

[0009] As the polyvalent epoxy compound that functions as the crosslinking agent and adhesive described above, a compound having two or more epoxy groups in one molecule is used. For example, epoxidized soybean oil, epoxidized linseed oil, commonly known as epoxy resin obtained by condensing epichlorohydrin and bisphenol A, etc., which are compounds that have a certain degree of compatibility with vinyl chloride resins or their plasticizers. be. The amount of the polyvalent epoxy compound is in the range of 1 to 50 parts by weight based on 100 parts by weight of the vinyl chloride resin.

The above-mentioned epoxy curing agent is a common epoxy resin curing agent. Specific examples thereof include one of amine compounds, diamine compounds, polyamine compounds, polyamides, amino acids, polybasic acids having two or more carboxyl groups, and acid anhydrides thereof. Since the reaction between the amine curing agent and the epoxy compound is extremely fast, it is often unsuitable for the usage conditions of general vinyl chloride resins, but it is useful for paints. Also,
Suitable curing agents for the general reaction conditions are amino acids, such as epsilon-aminocaproic acid, dibasic acids, such as adipic acid, etc.
Acid anhydrides, such as succinic anhydride, maleic anhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride,
Methylhexahydrophthalic anhydride and the like, and condensates of these polybasic acids and glycol are useful, and can be used alone or in combination. In addition, the amount of epoxy curing agent is
0.2 to 20 per 100 parts by weight of vinyl chloride resin
Parts by weight range.

[0011] As the above-mentioned plasticizer, for example, dioctyl phthalate can be used as desired. Therefore, the present invention provides a wide range of crosslinked vinyl chloride resin foams ranging from hard to soft.

Since the above-mentioned stabilizer acts directly on the crosslinking reaction of the vinyl chloride resin, care must be taken regarding its type and amount. For example, dibasic lead phthalate, tribasic lead sulfate, zinc laurate, etc. are added in an amount of 0.5 to 5 parts by weight per 100 parts by weight of the vinyl chloride resin.

[0013] The lightweight aggregate used in the present invention is composed of one of pearlite grains, vermiculite, calcium carbonate, shirasu balloons, aluminum hydroxide, and calcium silicate, and improves the mechanical strength and fire retardant properties of the foam core material. Or it can serve as a blowing agent.

[0014] The above-mentioned foam stabilizer is silicone and helps to make the cells of the foam structure into a uniform shape, which increases the strength of the entire foam, improves the heat insulation performance, and reduces the amount of resin, which also contributes to cost reduction. be.

In the present invention, the microwave used is for heating the center layer of the foam in the process of crosslinking, foaming, or foaming the raw material of the vinyl chloride foam. The frequency is 2450MHz, the output is about 0.5~5KW, the space to be heated is about 1~5mm, and the width is 30~9mm.
00 mm, and the spatial height is about 5 to 100 mm. Of course, in the case of a space in which an object to be heated is conveyed by a roller or the like in a cover (not shown), the length is not limited to the above.

[0016] On one side or both sides of the vinyl chloride foam A produced according to the present invention, a facing material B is provided as shown in Fig. 2.
Paper, asphalt felt, kraft paper, asbestos paper, etc. are used as materials.

The method for producing a vinyl chloride foam according to the present invention will be explained using FIG. 1. A foam composition including a vinyl chloride resin 1, a blowing agent 2, a solvent 3, etc. is simultaneously sprayed into a closed kneader 4, and then This composition is supplied to an extruder 5, and then fed to a predetermined mold 6 and molded while being heated. At this time, the inside of the mold is structured to be irradiated with microwaves, and the outer circumferential surface of the composition that is being foamed and then the center of the composition that is being foamed are heated by microwaves, cooled, and removed from the mold. With this method, the foaming time is reduced to less than half of the conventional foaming time, and the wall thickness is 20~
The 30 mm center portion also had the same cell structure as the surface layer.

What has been described above is only one embodiment of the method for producing a vinyl chloride foam according to the present invention, and the above foam can also be produced by the method shown in FIG. 3. That is, the mixer 7 discharged the mixed foam composition (platinum sol) onto the continuous belt upper die 8 to a thickness of 3 mm, and then fed it to the crosslinking and foaming furnace 9 to obtain a foam 50 times larger. In this furnace 9, the upper and lower mold nonwoven fabrics are belts, and above the upper mold there is a microwave irradiator and a hot air blower, so that the surface heating and the central layer of the foam can be heated during movement. .

[0019] As a blending example of the above foam, the blending ratio: polyvinyl chloride
100 parts by weight dioctyl adipate
20 parts by weight Butylbenzyl phthalate (plasticizer) 20 parts by weight
Epoxidized linseed oil
5 parts by weight Anhydrous Trimet (crosslinking aid)
2 parts by weight tribasic lead sulfate (stabilizer)
10 parts by weight Silicone (foam stabilizer)
1 part by weight azodicarbonamide
10 parts by weight polyethylene oxide (lubricant)
2 parts by weight Zinc oxide (foaming aid)
1 part by weight
Tetrapropylammonium bromide
1 part by weight Perlite grains (filler, aggregate) 50 parts by weight.

[0020]

As described above, according to the method for producing vinyl chloride foam according to the present invention, (1) vinyl chloride foam can be produced at a rate more than twice that of the conventional method. ■Thick-walled items, e.g. 20
50 mm can be easily manufactured with a foamed structure of uniform cells, the yield is improved, and the manufacturing time is significantly shortened. It has the following characteristics.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a method for producing a vinyl chloride foam according to the present invention.

FIG. 2 is an explanatory diagram showing an example of a cross section of a vinyl chloride foam obtained by the manufacturing method according to the present invention.

FIG. 3 is an explanatory diagram showing another example of the method for producing a vinyl chloride foam according to the present invention.

[Explanation of symbols]

A Vinyl chloride foam 4 Closed kneader 6 type 7 Mixer 8 Continuous belt upper mold 9 Crosslinking foaming furnace

Claims (1)

[Claims] 1. A method for producing a vinyl chloride foam, characterized in that the heating step during foaming in producing the vinyl chloride foam is performed using microwaves.