JPH08224746A - Production of foamed composite having sections - Google Patents

Abstract

PURPOSE: To enhance the compression resistance, impact resistance and bending resistance of a foamed composite having a large number of sections by forming a skin from powder plastic in a process wherein powder plastic and foamable granules are charged in a mold to be heated while them mold is rotated and subsequently foaming the granules. CONSTITUTION: A foamable material, for example, 0.2PHR of dicumyl peroxide and 20 PHR of azodicarbonamide is kneaded with low density polyethylene and the kneaded matter is covered with high density polyethylene while extruded into a rod shape and the coated extrudate is compressed and cut to obtain foamable particles. A powder prepared by mixing 1PHR of azodicarbonamide with a high density polyethylene powder and the foamable particles are charged in a mold and heated by steam of about 150 deg.C while the mold is rotated to form a skin and, subsequently, steam of about 180 deg.C is introduced into the mold to heat and foam the foamable particles. By this method, a foamed composite wherein a skin foamed in low foaming magnification is provided to the surface thereof and foams high in foaming magnification are coated weight sections and a large number of the sections are arranged at an almost equal interval in the thickness direction thereof is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to produce a foamed composite having a skin and having a large number of compartments therein, which is used as a heat insulating material, a cushioning material, a buoyant material, and the like.

[0002]

2. Description of the Related Art A material having a plastic skin and a foam inside has excellent heat insulating properties, but if it is large, it has a drawback that it is difficult to use because its central portion has a weak compression resistance.

[0003]

SUMMARY OF THE INVENTION The inventors of the present invention have achieved various aspects of the present invention by variously studying a method for producing a compact having excellent heat insulation and having a compressive strength in the central portion of a large compact. is there.

[0004]

Means for Solving the Problems The inventors of the present invention put a powdered plastic and a granular material in which a foaming material is coated with plastic into a mold, and heat the powdered material from the outside while rotating it to make a skin first, and then When the temperature is raised and steam is put into the mold to foam, the powdered plastic becomes a skin, and then the granular body expands and expands into a foamed composite having a number of compartments in the thickness direction. It has been discovered that a foamed composite having excellent compression resistance, impact resistance, bending resistance, etc. can be obtained.

[0005]

[Operation] In the method of the present application, the powdered plastic and the granular material in which the foamable material is coated with the plastic are present in the mold. Then, when this mold is heated from the outside while rotating, the plastic powder is first melted to form a phase having a uniform thickness on the inner surface of the mold. Next, when the temperature is raised, steam enters the mold, and the particles in which the plastic is coated on the foamable material are heated and expand. When the size of this material expands greatly and fills the mold, since the mold is usually a rectangular parallelepiped, the upper and lower sides of one particle hit the mold and become smooth, and the side surface is integrated with the adjacent granular body, eventually the granular body. Has a shape close to a rectangular parallelepiped, and the coated material is stretched at the boundary to form a section where the two are united. Therefore, although the coating of the particle at the end which is in contact with the mold is thin, the surface of the mold is thick and the strength is sufficient because the method of the present invention forms a skin on the inner surface of the mold. As described above, in the method of the present application, since there are a large number of strength members that form the compartments in the thickness direction inside the molded body, and the whole is integrated, it is extremely durable.

The powder plastics of the present invention are polyethylene, polypropylene, EVA, nylon, ABS, polycarbonate, polyvinyl chloride, etc. used for rotational molding. In some cases, a powdered plastic is mixed with a foaming agent to foam the skin to make the molded body airtight or have a non-slip function.

The foamable material of the present invention may be any material as long as it can be foamed by heating, but preferred is a mixture of polyolefin with dicumyl peroxide and azodicarbonamide.

Any material may be used as a material for coating the foamable material of the present invention as long as it is a thermoplastic resin, but it is preferable to heat and bond the foamable material and the material of the skin well. A foaming agent may also be added to the material to be coated for foaming.

The coating of foamable material with plastic is
Use two extruders to extrude the foamed material with a rod,
It is usual that a material to be coated is coated on this, and this is compressed and cut in a state in which the two materials are melted to obtain a grain whose both ends are closed. The material to be coated may be extruded in the shape of a pipe, and a foaming agent or expandable particles may be put therein to close both ends. It is also possible to make and use a bun-like granular material with the foaming material and the covering material by two injection molding machines.

Since the expandable material usually expands 20 to 50 times, the ratio of the expandable material to the covering material is 1: 1 to 1:20 by volume, and the expandable material covered with the plastic is expandable. The particles have a diameter to length ratio of 1: 3 to 3: 1.
Is. When large expandable particles are used, they tend to form a rectangular parallelepiped section, and when the size is such that the mold can be inserted into the mold at a thickness of ½ or more of the mold, the particles do not overlap each other. It will be even more. It is preferable to make the section as thick as possible from the viewpoint of increasing the strength. A sheet of thermosetting resin that is not easily deformed by heat is made into a strip shape, cuts are made in this sheet and combined at right angles from the top and bottom, and this is put in a mold to create a number of chambers, one by one It is possible to put a foam material into the foam and foam it, and thereby it is possible to make sections in the thickness direction of the plate at equal distances. In this way the chamber can be divided into two or more tiers, and compartments can be created in two or more tiers.

The mold is rotated uniaxially or biaxially, and is rotated slowly so as not to give a centrifugal force to the material.

The heating in the present application is performed at a temperature at which the material melts and foams, and is performed at 150 to 250 ° C. Usually, latent heat is used for steam heating, and the heating time is 30 to 90 minutes. A two-stage heating method is used in which a valve is attached to a mold to externally heat it at a low temperature to form a skin, and then the temperature is raised to a high temperature and steam is put into the mold to heat and foam. This can shorten the heating time.

The mold is cooled by putting the mold in water or by showering.

[0014]

EXAMPLES Next, examples of the present application will be described. Example 1 Low-density polyethylene (density 0.92 MI 2) was kneaded with dicumyl peroxide 0.2PHR azodicarbonamide 20PHR and extruded into a 6 mm rod while high-density polyethylene (density 0.94 MI 2
5) was coated to a wall thickness of 6 mm, and this was compression cut to a length of 18 mm. Azodicarbonamide 1PH on the same high-density polyethylene powder in a 500 x 500 x 25 mm mold
0.5 kg of powder mixed with R and 1.5 kg of the foamed granules prepared above were put, and this was heated from outside with steam at 150 ° C. for 20 minutes while uniaxially rotating at a rotation speed of 1 rpm at an inclination angle of 15 degrees. The skin was made, and then steam at 180 ° C. was placed in a mold and heated and foamed for 20 minutes. The obtained molded body has a shape as a mold, and has a low-magnification foamed skin on the surface,
The interior is covered with high-magnification foam in sections, and the sections are arranged vertically and horizontally at approximately equal intervals in the thickness direction of the plate. It is a compression-resistant, impact-resistant, bend-resistant molded body, and is airtight. It was excellent as a flooring material because it was excellent in sound resistance and soundproofing, and no sound was produced even if an object was dropped. Example 2 Dicumyl peroxide 0.3P on low density polyethylene
HR and 20 PHR of azodicarbonamide were kneaded, extruded into a rod of 30 mm, and cut into a length of 30 mm. This was kneaded with low-density polyethylene and dicumyl peroxide 0.3 PHR azodicarbonamide 1.5 PHR, and this material was extruded into a pipe shape with an inner diameter of 90 mm and a wall thickness of 1 mm, and one of the above-mentioned foams was put into this. It was cut and sealed to a length of 90 mm. 500 x 500 x 500 mm
In the mold, length 500mm width 100mm thickness 0.5mm
1mm wide and 50mm long cuts made in the phenolic resin sheet of No. 2 at 100mm intervals from one end to the center 2
The pieces are combined from the top and bottom to form a cubic chamber 25 having a piece of 100 mm, which is put into a mold and 500 × 500 × 0.
A 5 mm sheet was placed and partitioned, and the same objects were stacked on it to form 5 levels, and a total of 125 chambers were created. Each of the foaming granules was placed in each chamber, and 1.5 kg of high-density polyethylene powder was placed at the same time. Inclination angle of this mold is 1
First, a skin was produced by externally heating steam of 160 ° C. for 15 minutes at a rotation speed of 0 rpm and 2 rpm, and then steam of 200 ° C. was put in a mold and heated for 25 minutes to foam. The obtained molded product had the same shape as the mold, had a smooth skin, had a well-expanded phase and a low-expansion expanded compartment, and had an apparent density of 0.1 g / cc and was extremely impact-resistant. Even if a part was broken, it did not spread to the whole, and it was an excellent levitating material. When the buoyant material was formed with concavities and convexities and bonded, it had a strong bonding force and was extremely difficult to come off.

[0015]

According to the present invention, the mold is made of powdered plastic,
Put a granular material coated with plastic in an expandable material, heat it while rotating it, first make a skin with powdered plastic, then raise the temperature to cause the granular material to foam inside it This is a foamed composite having compartments. This complex has an epidermis, a large number of strength member compartments, and an apparent density of 0.5 g /
From an extremely strong cc, an apparent density of 0.05g
Since the heat insulation property of / cc is even better, compressive strength,
It has excellent impact strength, bending strength, etc., it does not easily spread to the whole even if part of it breaks, and has a strong binding force when joined with screws or unevenness, heat insulating material, cushion material, buoyant material, automobile material, construction material, civil engineering Used as various materials for various purposes.

[Brief description of drawings]

1 is a cross-sectional view of a foamed composite having multiple compartments obtained with the present invention.

[Explanation of symbols]

 1 skin 2 foam 3 compartments

Claims (2)

[Claims] 1. A powdered plastic and a granular material in which a foaming material is coated with plastic are placed in a mold, and while rotating, this is heated from the outside to first form a skin with the powdered plastic, and then vapor in the mold. A method of producing a foamed composite having a large number of compartments therein, by charging the mixture with a mixture to raise the temperature to foam the granules. 2. A structure of a foamed composite body, comprising a plastic skin, and a plurality of compartments in the thickness direction of the plate being present therein.