JPS6328456B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel water-foamable thermoplastic resin compound and a method for producing the same, and more specifically to a thermoplastic resin compound that can be made into a foamed molded product using an aqueous medium as a blowing agent. and its manufacturing method.

Conventionally, methods for producing thermoplastic resin foams include melting a thermoplastic foam under pressure together with a thermoplastic resin and a thermally decomposed blowing agent that decomposes to generate nitrogen gas or carbon dioxide, or a low-boiling point liquid or liquefied gas. The method used is to lower the pressure after kneading and foaming. However, in the case of thermally decomposable foaming agents, coloring of the resin foam due to decomposition residues also causes a bad odor, and it is also difficult to control foaming. On the other hand, when a low-boiling liquid or liquefied gas is used as a blowing agent, there are risks such as flammability, explosiveness, and hygiene of the blowing agent during storage of expandable beads and foams or during the foaming process. , there are handling problems.

The present inventors have conducted intensive research on thermoplastic resin foams free from the above-mentioned drawbacks and methods for producing the same. As a result, we have developed a partially fused multi-optic resin foam made of resin powder coated with a hydrophilic solid fine powder. The present inventors have discovered that thermoplastic resin can be easily foamed with an aqueous medium by using a resin compound made of agglomerated particles, and have completed the present invention.

According to the present invention, the thermoplastic resin powder is coated with a hydrophilic solid fine powder, and the hydrophilic solid fine powder does not substantially melt at the melting temperature of the resin powder. Water vapor adsorption consisting of a porous mass formed by aggregation and mutual fusion of a large number of thermoplastic resin powder particles that are partially embedded in an exposed state on the surface of the resin powder particles. A water foaming resin compound having a percentage of 0.05% or more is provided.

According to the present invention, a mixture of 100 parts by weight of a thermoplastic resin and 30 to 250 parts by weight of a hydrophilic solid fine powder that does not substantially melt at the melting temperature of the resin is mixed in a high-speed rotating mixer. Mix at high speed while heating to a temperature higher than the melting temperature, and immediately cool when a partially fused porous aggregate of the thermoplastic resin powder coated with the hydrophilic solid fine powder is formed. Provided is a method for producing a water-foaming resin compound that solidifies and has a water vapor adsorption of 0.05% or more.

As described below, the above-mentioned resin compound provided by the present invention is treated with an aqueous medium and then melted in a non-vented extruder under pressurized conditions in which evaporation of the aqueous medium is substantially suppressed. A resin foam can be obtained by kneading, extruding, releasing from the pressurized state, and foaming and solidifying.

Since water is a liquid with a relatively low boiling point, it can theoretically be used as a blowing agent for thermoplastic resins.
In general, it is not compatible with hydrophobic resins, and the filler added to the resin is used after drying to remove moisture. Therefore, conventionally, it was completely unthinkable to use water as a foaming agent for resins. However, the fact that this has become possible through the use of the resin compound of the present invention is completely unexpected from the prior art and is groundbreaking.

Since the foaming resin compound of the present invention uses an aqueous medium as a foaming agent, it can be melt-extruded at relatively high temperatures and high speeds, unlike foaming that generates heat, such as with the thermally decomposed foaming agent described above. ,
High quality resin foam can be manufactured with high productivity. Furthermore, by using the water-foaming resin compound of the present invention, unlike resin foams using thermally decomposable blowing agents, there is no generation of decomposition residues that cause resin coloring or bad odors.
Furthermore, the aqueous medium used in the present invention is a blowing agent that is clean and easy to handle, and has no flammability, explosiveness, or sanitary hazards, unlike conventional low-boiling liquids and liquefied gases. Therefore, the resin compound of the present invention is industrially extremely advantageous for producing thermoplastic resin foams.

The present invention will be explained in more detail below.

The thermoplastic resin used in the present invention is not particularly limited, and any thermoplastic resin that has been conventionally used in various plastic moldings can be used.
For example, olefin resins such as high density polyethylene, low density polyethylene, polypropylene, polybutene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, petroleum resin; diene resins such as polybutadiene and polyisoprene; polyvinyl chloride , vinyl resins such as polyvinyl acetate, polyvinylidene chloride, and polyvinyl alcohol;
Acrylic resins such as polymethyl methacrylate;
Styrenic resins such as polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer; nylon-6,
Polyamide resins such as -66 and -12; polyester resins such as polyethylene terephthalate are included. Each of these can be used alone, or two or more kinds can be used in a blend.

On the other hand, the hydrophilic solid fine powder used in combination with the resin is either hydrophilic itself or is made of an organic or inorganic substance that has been rendered hydrophilic by a hydrophilic treatment.

Further, the hydrophilic solid fine powder used in the present invention does not substantially dissolve at the melting temperature of the resin powder used in combination with the hydrophilic solid fine powder, and desirably is capable of being expanded and wetted by an aqueous medium. They are selected from those that do not dissolve easily, even if they exist. In other words, the solubility in water is generally 10g/at 25°C.
Hereinafter, preferably 5 g/or less is advantageously used.

Hydrophilic solid fine powders that can be suitably used in the present invention include, for example, grain flours such as starch and wheat flour; plant powders such as wood flour; hydrophilic solid powders such as urea resins, melamine resins, and phenolic resins. Examples include resin powder; metal powder such as iron and aluminum; inorganic powder such as talc, clay, calcium carbonate, silica, alumina, and glass powder.

These solid fine powders have sufficient hydrophilicity by themselves, but they may also contain substances (hereinafter referred to as surfactants) that make the surface of these fine powders more susceptible to water, such as fatty acids. Nonionic surfactants such as alkanolamides, fatty acid monoglyceroids, and polyethylene glycol fatty acid esters; anionic surfactants such as fatty acid amides, fatty acid metal salts, alkyl sulfate types, and alkyl phosphate types; cationic surfactants such as ammonium salts Hydrophilic properties can be further increased by surface treatment with agents; fatty acids; polyhydric alcohols such as polyethylene glycol, polypropylene glycol, and glycerin; ethers such as polyethylene glycol diethyl ether; polyvinyl alcohol, etc., or a mixture thereof. The affinity bond between the resin and the fine powder can be improved.

Furthermore, even if a substance is hydrophobic, it can be made hydrophilic by surface treatment with a surfactant such as those mentioned above, or a hydrophilic substance such as polyvinyl alcohol, fatty acids, polyhydric alcohols, or ethers. It can be used in the same manner as the hydrophilic substances described above.

The hydrophilic solid fine powders described above can be used alone or in combination of two or more. In the present invention, talc, calcium carbonate, clay, silica, and alumina having an average particle size of 1 to 15 microns are particularly preferably used.

A portion of the above-mentioned hydrophilic solid fine powder, generally up to 20% by weight, preferably 10% by weight or less of the total amount of the solid fine powder used, may be added to, for example, pulp, cotton, silk, etc.
It can also be replaced by organic short fibers such as hemp, wool, synthetic fibers, and recycled fibers, or inorganic short fibers such as glass fibers, carbon fibers, and asbestos.
By using these short fibers in combination, the mechanical strength of the foam can be significantly improved.

The particle size of the hydrophilic solid fine powder used in the present invention is not strictly limited, and can be varied widely depending on the desired degree of foaming, type of resin, physical properties required of the foam, etc. However, it is generally appropriate that the average particle size is 100 microns or less, preferably in the range of 0.1 to 50 microns, and more preferably in the range of 0.5 to 30 microns. In addition, when using short fibers as described above, the fiber length is generally 10 mm or less, preferably 5 mm or less, and
The fiber diameter is generally less than 100 microns, preferably 1
A range of ˜50 microns is preferred.

From the thermoplastic resin and the hydrophilic solid fine powder described above, a thermoplastic resin powder coated with the hydrophilic solid fine powder (hereinafter sometimes referred to as "composite resin powder") is prepared. When doing so, it is important that the solid fine powder is adhered and buried in an exposed state on the surface of the resin powder (however, of course, the resin powder also has the solid fine powder inside it). (may contain powder dispersed). The amount of solid fine powder adhering to and buried in the resin powder granule is that the surface of each resin powder granule is mostly covered with the exposed solid fine powder, and when observed with an electron microscope at 300x magnification, the resin powder is It is desirable that the amount be such that the base of the grains is hardly visible.

Furthermore, it was found that a large number of the resin particles coated with the exposed hydrophilic solid fine powder aggregated, and the individual particles partially fused to each other to form a porous mass. is important. When such a porous aggregate is treated with an aqueous medium, it must be capable of stably adhering and retaining the aqueous medium, and therefore, the porous aggregate must have a water vapor adsorption rate of at least 0.05%, preferably 0.3%. It is highly desirable that this is the case.
Here, "water vapor adsorption rate" means that a porous aggregate of 1 g of W after being kept in a constant temperature and humidity chamber at a temperature of 25 °C, a relative humidity of 30%, and a pressure of 1 atm for 24 hours is measured at a temperature of 105 °C,
After keeping it in a closed atmosphere with a water vapor pressure of 1.2 atm for 1 hour, take it out and leave it on paper for 3 minutes, then
When placed in a drying oven at 105°C for 3 minutes and immediately weighed, the amount is defined as W2g, this is the value calculated by the following formula.

Water vapor adsorption rate (%) = W ₂ − W ₁ /W ₁ ×100 The size of the above porous aggregate is not important and can be any size, but it is easy to handle and melt-knead as described below. From the perspective of
A particle size range of 0.1 to 20 mm, preferably 0.3 to 5 mm is suitable. Therefore, if the particle size is larger than this, it is preferable to use a pulverizer, mixer, etc. to reduce the particle size to the above range.

One effective method for preparing such a porous aggregate is to mix the above-mentioned thermoplastic resin and hydrophilic solid fine powder with a high-speed (vortex) mixer, such as a Henschel mixer (manufactured by Mitsui Miike Manufacturing Co., Ltd.), There is a method of high-speed mixing while heating the thermoplastic resin to a temperature higher than the melting temperature of the thermoplastic resin in a mixing tank such as a Super Mixer (manufactured by Kawada Seisakusho). Heating of the resin is carried out by circulating steam or oil through the jacket of the mixing tank, or by generating heat from mixing friction.

During heating and mixing at high speed rotation, when the resin reaches its melting temperature and begins to melt, the resistance to the mixing rotational force of the mixer rapidly increases, and the rotational resistance (or current) of the mixer motor fluctuates wildly. This high-speed mixing under turbulent fluctuations is generally carried out for about 50 to about 250 seconds, preferably about 70 to
Conveniently it lasts about 200 seconds.

The change in the shape of the resin at temperatures above the melting temperature of the resin in the mixing tank of the high-speed mixer is only caused by mutual fusion of the resins when only the resin is mixed by heating, but in the present invention. In this case, the solid fine powder adheres to the resin surface and the resin is deformed while preventing mutual fusion of the resins, so the situation is different from the above case. That is, (1) Until the resin starts to melt and deform and the electric current of the mixing rotary motor starts to increase in a fluctuating manner, the resins do not interact with each other, regardless of whether the resins are supplied in the form of pellets or powder. There is no fusion, the resin and solid fine powder are simply mixed and dispersed.

(2) However, the resin gradually melts and deforms, becomes flat flakes, and is successively torn off into fine flakes of powder. At the same time, the solid fine powder particles adhere to the surface of the powdery resin and are partially embedded.
The surface of the thin flaky resin powder is coated with fine powder.

(3) Further, the adhesion of the solid fine powder particles to the resin surface progresses, and the solid fine powder particles are attached to the resin surface by the molten resin exuding from between the solid fine powder coating the resin surface, and/or through the free resin pieces, and/or by the solid particles. The resin powder particles coated with the solid fine powder are partially fused to each other on the minute exposed surfaces to which the fine powder is not attached, forming a porous aggregate.

(4) At this point, the porous agglomerate is discharged outside the mixing tank, sprinkled with water and/or blown with air, and optionally rotated at low speed to cool and solidify. Alternatively, by passing cooling water through the jacket of the mixing tank and blowing air thereon, the mixture can be cooled and solidified within the mixing tank, thereby obtaining the resin compound made of the porous agglomerates of the present invention.

The mixing device used in the present invention is not limited to a high-speed mixer, but any mixer having the same functions as those described above may be used. Among the equipment that is easily available today, high-speed mixing mixers can be used as is and are often used, but other mixing machines such as ribbon blenders can be modified to have a strong high rotational force. It can be used for.

The ratio of the hydrophilic solid fine powder to the thermoplastic resin when charged into the above-mentioned mixing mixer depends on the type of resin and solid fine powder, the water absorption rate and water vapor adsorption rate required for the resulting porous aggregate, etc. Although it can vary widely depending on the situation, in general, the solid fine powder is used in an amount of 30 to 250 parts by weight, preferably 60 to 150 parts by weight, and more preferably 80 to 120 parts by weight per 100 parts by weight of the thermoplastic resin. They can be used alone or in a mixture of two or more. As mentioned above, when a part of the solid fine powder is replaced with a fibrous substance, it is appropriate that the fibrous substance accounts for 20% by weight or less, preferably 10% by weight or less of the total solid fine powder. .

In addition, when preparing the above-mentioned porous aggregate, in addition to the resin and solid fine powder, resin additives such as antioxidants, surfactants, colorants, ultraviolet absorbers, flame retardants, etc. may be added as necessary. . Examples of antioxidants that can be used include thiopropionic acid ester antioxidants such as dilauryl thiodipropionate; phenolic antioxidants such as alkylphenols and alkylbisphenols; or mixtures thereof. Examples of the surfactant include those mentioned above. The antioxidant is usually used as a solid fine powder in an amount of 0.01 to 5 parts by weight per 100 parts by weight, and the surfactant is used as a solid fine powder in an amount of 0.01 to 5 parts by weight per 100 parts by weight.
Generally, it can be blended in a proportion of 0.1 to 10 parts by weight per part by weight. In addition, examples of colorants include dyes and pigments such as cadmium red, chrome orange, chrome yellow, chrome green, cobalt aluminate blue, titania, phthalocyanine blue, and azo dyes, and examples of ultraviolet absorbers include salicylic acid, Examples include benzophenone-based and benzotriazole-based ultraviolet absorbers, and examples of flame retardants include phosphate esters, halogenated hydrocarbons, and antimony oxide, which have been conventionally used as resin additives in normal amounts. Can be blended.

The porous aggregate thus prepared can be used as it is for film formation and molding as a water foaming resin compound. For example, the resin compound of the present invention is treated with an aqueous medium as a blowing agent, then melt-kneaded under pressurized conditions where evaporation of the aqueous medium is substantially suppressed, and then the melt-kneaded resin composition is added. It can be made into a resin foam by releasing it from the pressure conditions and allowing it to foam.

Water is generally used as the aqueous medium, and it is possible to adjust the boiling point and vapor pressure of the medium, increase the affinity for the porous aggregate, improve the dispersion stability of the aqueous medium during melt-kneading of the resin compound, For the purpose of improving the uniformity of bubbles, a surfactant, a water-soluble polymer, a polyhydric alcohol, a water-miscible organic solvent, etc. can be appropriately added to the water. As the surfactant, those mentioned above can be used, and these are generally used in an amount of 0.1 to 50 g/, preferably 1 to 10 g/to water.
It can be added at a concentration of Examples of water-soluble polymers and polyhydric alcohols include polyvinyl alcohol with a degree of polymerization of about 500 to about 2000 and a degree of saponification of 85% or more, mono- or polyethylene glycol with a number average molecular weight of up to 400, glycerin, etc. These are generally 1
It can be added at a concentration of ~100g/, preferably 10-50g/. Further, water-miscible organic solvents that can be used include, for example, alcohols such as methanol, ethanol, propanol, and cyclohexanol; esters such as ethyl acetate and butyl acetate; ethers such as diethyl ether, dioxane, and trioxane; acetone; Examples include ketones such as methyl ethyl ketone, which can be blended in a concentration of generally 1 to 100 g/, preferably 10 to 50 g/to water.

The amount of the aqueous medium mentioned above can be varied over a wide range depending on the desired expansion ratio of the foam, but is generally 1 to 15 parts by weight, preferably 1 to 15 parts by weight per 100 parts by weight of the porous aggregate. may be 2 to 5 parts by weight. Treatment of the resin compound with an aqueous medium can be carried out by combining the two and mixing in a mixer.

The resin compound treated with the aqueous medium as described above is then melt-kneaded under pressurized conditions in which evaporation of the aqueous medium is substantially suppressed. This melt-kneading can be carried out in the same manner as melt-kneading in the production of ordinary resin foams, and can be carried out using, for example, a non-vent extruder, an injection molding machine, or the like. Here, "pressurized conditions under which evaporation of the aqueous medium is substantially suppressed" refers to pressure conditions higher than the vapor pressure of the aqueous medium impregnated in the compound at the melt-kneading temperature. The operation of the extruder or injection molding machine is not special and can be carried out by a method known per se.

The resin composition sufficiently melted and kneaded in this way is
It is extruded in a molten state through dies of various shapes, injected into suitable molds, or applied to a press molding machine, released from the above-mentioned pressurized state, and foamed and solidified.

As a result, the resin compound of the present invention can be extruded into foams of various shapes such as a covered foam sheet, a flat foam sheet, a stretched foam sheet, a modified foam molded product, a foam blow molded product, and a foam pipe. Alternatively, it can be processed into injection foam molded products, press foam molded products, etc.

As described above, by using the resin compound of the present invention, it is possible to perform foam molding even on plastic molded articles for which foam molding has conventionally been difficult or impossible, which is extremely useful industrially.

The method of the present invention will now be further illustrated by examples.

Example 1 Blending amount Kg g Resin: Polypropylene (Noblen manufactured by Mitsubishi Yuka Co., Ltd.
MA-8A; M1 = 0.7, density = 0.9) 10000 Fine powder: Talc (MS manufactured by Nippon Talc Co., Ltd.: average particle size 9μ) 10000 Surfactant: Fatty acid alkanolamide (Amizole LDE manufactured by Kawaken Fine Chemical Co., Ltd.) 100 Fatty acid Monoglyceroid (Rikemar S-100, manufactured by Riken Vitamin Co., Ltd.) 50 Fatty acid amide (Alflo-P-10, manufactured by Nihon Yushi Co., Ltd.)
50 Colorant: Titanium oxide (anatase type, A100 manufactured by Ishihara Sangyo Co., Ltd.) 500 Antioxidant: Dilaurylthiodipropionate 30 1,1,3-Tris(2-methyl-4-hydroxy-5-t-butylphenyl) Butane 10 A high-speed mixing mixer (Super Mixer SMG100 manufactured by Kawada Seisakusho, mixing electric motor 22KW, 4P/8P) was used to heat the mixing tank (tank capacity 100) by circulating heated oil at 140° to 150°C through the jacket. . The entire mixture was put into the mixing tank of the mixer and mixed at high speed.

After about 20 minutes, the current in the mixing motor started to fluctuate and suddenly increase (mixture temperature: 195°C). After 80 seconds, it suddenly increased and reached 80A (mixture temperature: 210°C) in 40 seconds (total of 120 seconds). The outlet was opened to release the mixture.

The discharged mixture is rapidly cooled and coarsely crushed by a low-speed rotating mixer with strong air cooling, and water vapor is adsorbed by partially fused porous aggregates of resin powder coated with fine powder. A resin compound with a percentage of 0.11% was obtained.

A water-foamed sheet is manufactured using this resin compound. The maximum particle size of the resin compound is 5 mm.
Grind and transfer to a mixer, add 500 c.c. of tap water (approximately 2.5 parts by weight based on 100 parts by weight of resin compound) containing 1% alkylbenzene sulfonate (Nitsun Yurex H manufactured by Nippon Oil & Fats Co., Ltd.). An aqueous medium was added and mixed for 5 minutes or more to obtain a resin compound impregnated with an aqueous medium.

A circular die is attached to the 70 mm extruder, and air rings are installed inside and outside the die lip to cool the tip of the die lip and the produced sheet.The blow ratio of the circular die/mandrel is set to 1.8 times, and the mandrel circulates cooling hot water to cool the outer periphery. This is a device that cools the sheet with a ring, pulls it up while stretching it, cuts it, and obtains a sheet using a puller/winder.The maximum temperature of the extruder cylinder is 225℃, the die temperature is 195℃ (resin temperature 198℃),
The resin compound impregnated with the above aqueous medium at a die lip of 190°C and a mandrel warm water of 90°C was foamed and extruded to form a film.

Resin foam made from this aqueous medium has a thin skin layer on the surface, has a closed cell structure with no bubble breakage, and is a homogeneous foam with a foam diameter of 0.5 mm or less, often 0.1 to 0.3 mm, and the foaming ratio (volume, magnification) is It was 9.8 times higher.

This foamed sheet is preferably vacuum-formed or pressure-formed for use in food packaging containers such as trays, and is also used in the fields of cushioning materials and white paperboard.

Example 2 Amount Kg g Resin: Low density polyethylene (Mitsubishi Yuka Co., Ltd. Novatec L F101A; MI = 0.45, Density = 0.922) 10000 Fine powder: Heavy calcium carbonate (Shiraishi Calcium Co., Ltd. Whiten SSB: Average particle size 1.5μ) 3000 Heavy calcium carbonate (Shiraishi Calcium Co., Ltd. Whiten B: average particle size 3.6μ) 7000 Surfactant: Fatty acid alkanolamide (Kawaken Fine Chemical Co. product Amizole CDE) 120 Polyethylene glycol (Sanyo Chemical Co., Ltd. product)
PEG6000) 60 Colorant: Titanium oxide (anatase type, A100 manufactured by Ishihara Sangyo Co., Ltd.) 300 Cobalt aluminate boule (manufactured by Dainichiseika Chemical Co., Ltd.)
0.1 Antioxidants: dilauryl thiodipropionate 10 22'-methylenebis(4-methyl-6-tert-butylphenol) 20 nonylphenyl phosphite 10 All formulations were prepared using the same high speed mixer as in Example 1. was added and mixed at high speed. After about 16 minutes, the current of the mixing motor started to fluctuate and increase slightly (mixture temperature: 190℃), and after 120 seconds, it suddenly increased and reached 50A (mixture temperature: 200℃) in 5 to 10 seconds (total of 125 to 130 seconds). So I opened the outlet and released the mixture.

The discharged mixture is rapidly cooled and coarsely crushed by a low-speed rotary mixer with strong air cooling, and water vapor is adsorbed by porous aggregates of resin powder coated with fine powder and partially adsorbed with a catalyst. A resin compound with a percentage of 0.24% was obtained.

Example 3 Blend amount Kg g Resin: Ethylene-vinyl acetate copolymer (Mitsubishi Yuka Co., Ltd. Yucalon Eva EVA20F; MI = 2; Density = 0.93) 10000 Fine powder: Heavy calcium carbonate (Shiraishi Calcium Co., Ltd. Whiten SB: Average Particle size: 1.8μ) 12000 Pulp powder (Sanyo Kokusaku Pulp Co., Ltd. KC Flot; W200; particle size: 200M/S pass) 500 Surfactant: Fatty acid alkanolamide (Amizole CDE, product of Kawaken Fine Chemical Co., Ltd.) 150 Fatty acid molyglyceroid ( Rikemar S-100 (manufactured by Riken Vitamin Co., Ltd.) 50 Calcium stearate (manufactured by Toa Rika Co., Ltd.) 100 Colorant: Titanium oxide (anatase type, A100 manufactured by Ishihara Sangyo Co., Ltd.) 500 Antioxidant: Pentaerythol tetrakis (β-laurylthiopropio) 10 Hindered Phenol Antioxidant 10 Using the same high-speed mixer as in Example 1, ingredients other than the resin were added, the mixer was rotated at high speed, and after about 8 minutes, the resin was added. After 2 minutes from the beginning, the current of the mixing motor fluctuated wildly and started to increase slightly (mixture temperature
185℃), then rapidly increased after 160 seconds for 20~25 seconds (total 180~
When the temperature reached 50A (mixture temperature: 195°C), the outlet was opened and the mixture was discharged.

The discharged mixture is rapidly cooled and coarsely crushed by a slow-rotation mixer with strong air cooling, and then steam is formed by porous agglomerates of resin powder coated with fine powder and partially adsorbed with catalyst. A resin compound with an adsorption rate of 0.58% was obtained.

A water-foamed sheet is manufactured using this resin compound.

The resin compound was pulverized to a maximum particle size of 5 mm or less, and an aqueous medium of 2% polyvinyl alcohol (manufactured by Kuraray Co., Ltd.) heated and melted tap water of 675 c.c. (approximately 3 parts by weight based on 100 parts by weight of the resin compound) was added. The mixture was mixed for 5 minutes to obtain a resin compound impregnated with an aqueous medium.

A T-die is attached to a 50mm extruder, and air knives are installed on both sides of the die lip to cool the tip of the die lip and the produced sheet, and then the sheet is rolled up while being stretched.The maximum temperature of the extruder cylinder is 200℃, and the die temperature is 170℃.
(resin temperature: 170°C), die lip at 165°C, rapidly cooled with an air knife, stretched and taken off, and the resin compound impregnated with the aqueous medium was foamed and extruded to form a corrugated foamed film.

The resin foam made from this aqueous medium is a wavy foam sheet that is stretched and has a directional closed-cell structure, and the foam diameter is homogeneous with a large diameter of 0.7 mm or less, often around 0.5 mm, and a foaming ratio ( Volume magnification) is 125
It was twice as hot.

This foam sheet is flexible and elastic and is suitable as a cushioning material.

Example 4 Blending amount Kg g Resin: High impact polyethylene (Mitsubishi Monsanto Diafflex HT-516: MI
= 2.2, density = 1.05) 10000 Fine powder: Talc (Nippon Talc Co., Ltd. MS: average particle size 9μ) 3000 Starch (Aito Co., Ltd. Cornstarch) 500 Surfactant: Monoethylene glycol 50 Alkylbenzene sulfonate (Nippon Oil Co., Ltd.) (Manufactured by Nitsusan Niurex H) 10 Coloring agent: Titanium oxide [anatase type, A100 manufactured by Ishihara Sangyo Co., Ltd.] 500 Antioxidant: Dilauryl thiodipropionate 10 2,6-di-t-butyl p-cresol 10 Same as Example 1 Using a high-speed mixing mixer, ingredients other than the resin were added, the mixer was rotated at high speed, and after 6 minutes, the resin was added. After 21 minutes from the beginning, the current of the mixing motor fluctuated wildly and started to increase slightly (mixture temperature 205
°C), after 120 seconds, the temperature rises rapidly for 5 to 10 seconds (total 125 to 130
When the temperature reached 50A (mixture temperature 210°C), the outlet was opened and the mixture was discharged.

The discharged mixture is rapidly cooled and coarsely crushed by a low-speed rotary mixer with strong air cooling, resulting in a water vapor adsorption rate consisting of partially fused porous aggregates of resin powder coated with fine powder. A 0.76% resin compound was obtained.

Example 5 Blending amount Kg g Resin: Acrylonitrile-butadiene-styrene copolymer (JSR manufactured by Japan Synthetic Rubber Co., Ltd.)
ABS85: Specific gravity = 1.05, MI = 1.7) 10000 Fine powder: Heavy calcium carbonate (Whiten SB manufactured by Shiraishi Calcium Co., Ltd.: average particle size 1.8μ) 8000 Wood flour (dried fine powder, particle size 100M/S pass) 500 Surfactant : Fatty acid alkanolamide (Amizole LDE manufactured by Kawaken Fine Chemical Co., Ltd.) Fatty acid amide (Alflo P-10 manufactured by NOF Corporation)
50 Glycerin 100 Colorant: Ceramic Yellow 100 Antioxidant: Distearylthiopropionate 10 2,6-di-t-butyl p-cresol 10 Using the same high-speed mixer as in Example 1, all the formulations were added. Mixed at high speed.

After about 18 minutes, the current of the mixing motor started to fluctuate and increase slightly (mixture temperature 20℃). After 160 seconds, it suddenly increased and reached 50A (mixture temperature 240℃) in 20-25 seconds (total 180-185 seconds). So I opened the outlet and released the mixture.

The discharged mixture is rapidly cooled and coarsely crushed by a low-speed rotating mixer with strong air cooling, and water vapor is adsorbed by partially fused porous aggregates of resin powder coated with fine powder. A resin compound with a percentage of 0.62% was obtained.

Claims (1)

[Claims] 1. Consisting of a thermoplastic resin powder coated with a hydrophilic solid fine powder, in which case the hydrophilic solid fine powder does not substantially melt at the melting temperature of the resin powder. The adsorption rate of water vapor is made up of a porous mass formed by a large number of thermoplastic resin powder particles that are partially embedded in an exposed state on the surface of the resin powder particles and are fused together. Resin compound for water foaming with 0.05% or more. 2 100 parts by weight of a thermoplastic resin and 30 to 30 parts by weight of a hydrophilic solid fine powder that does not substantially melt at the melting temperature of the resin
A mixture consisting of 250 parts by weight is mixed at high speed in a high-speed rotating mixer while being heated to a temperature higher than the melting temperature of the resin to form the thermoplastic resin powder coated with the hydrophilic solid fine powder. A method for producing a water foaming resin compound having a water vapor adsorption rate of 0.05% or more, which is characterized by immediately cooling and solidifying a partially fused porous aggregate when it is formed.