JP3192881B2 - Manufacturing method of polystyrene foam sheet - Google Patents

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 a polystyrene foam sheet. More specifically, the present invention relates to a method for producing a polystyrene foam sheet using water or an environmentally friendly foaming agent comprising water and nitrogen.

[0002]

BACKGROUND OF THE INVENTION Blowing agents such as lower aliphatic hydrocarbons and halogenated hydrocarbons have been used. Since these foaming agents are compatible with the styrene resin, the resin viscosity decreases. Therefore, the molten resin temperature can be sufficiently reduced. In addition, when foaming is performed by extruding into the atmosphere through a mold, the foaming agent dissolved in the styrene-based resin is vaporized, and at the same time, heat is removed from the styrene-based resin to solidify the cell membrane, thereby forming a uniform independent foam. Bubbles can be formed.

[0003] However, these blowing agents such as lower aliphatic hydrocarbons and halogenated hydrocarbons have problems in handling such as destroying the ozone layer of the earth and easily igniting. Therefore, as a foaming agent for producing a polystyrene-based resin foam, use a gas or water having low solubility in a polystyrene-based resin, such as nitrogen, which does not cause environmental problems and has no problem in terms of safety. A number of attempts have been reported.

However, when extruding nitrogen as a foaming agent, nitrogen has low compatibility with the polystyrene resin, so that the temperature of the molten resin cannot be sufficiently lowered, and the uniform dispersion of the foaming agent and the heat of vaporization can be prevented. There is a problem that there is a shortage of indispensable items for manufacturing a high-multiplied product in which a bubble film is solidified by utilizing the same. On the other hand, in the case of extrusion molding using water as a foaming agent, water is hardly soluble in a polystyrene-based resin as in the case of the above-mentioned nitrogen, and therefore, the same problem as in the case of nitrogen occurs. Further, there arises a problem that vaporized water is liquefied immediately after molding, and the foamed sheet shrinks and bubbles become coarse.

[0005] Therefore, it has been difficult to produce a beautiful sheet having an expansion ratio of about 10 times or more using nitrogen or water alone as a foaming agent. In addition, Japanese Patent Application Laid-Open No.
No. 33 discloses a method for producing a foaming substance using nitrogen and alcohol as blowing agents. However, a foaming agent containing an alcohol is known to have poor foamability, and it is difficult to increase the foaming ratio. In addition, there are still problems in safety, such as the alcohol odor remaining in the foam and the risk of fire.

[0006]

Thus, according to the present invention , water or a blowing agent composed of water and nitrogen is used in a polystyrene resin, and the polystyrene resin has an HLB of 12 to 18.
That a nonionic surfactant with respect to the polystyrene resin
The present invention provides a method for producing a polystyrene foam sheet, which is characterized by being subjected to extrusion foam molding using 0.1 to 5.0% by weight . The polystyrene resin that can be used in the present invention is not particularly limited as long as it can be foamed. For example, in addition to a homopolymer of styrene, styrene and butadiene (for example, HI resin), a copolymer of styrene and acrylonitrile, styrene and methyl methacrylate, and a terpolymer of acrylonitrile, butadiene, and styrene are exemplified. Mixtures of these can also be used. Further, those mixed with polyethylene, butyl rubber and the like can also be used.

The styrenic resin may contain a flame retardant, a coloring agent, an antistatic agent, a cell regulator and the like as long as the physical properties are not impaired. Examples of the flame retardant include tricresyl phosphate, paraffin chloride, antimony oxide, monoammonium phosphate, boric acid, and the like. Examples of the colorant include, for example, azo, anthraquinone, thioindigo, quinoline, and indanthrene. Dyes, phthalocyanine-based, quinacridone-based, benzidine-based organic pigments, various metal oxides, sulfides, sulfates, and other inorganic pigments.Examples of the antistatic agent include inorganic salts, polyhydric alcohols, and metals. Compounds, carbon and the like can be mentioned, and talc and the like can be mentioned as the bubble regulator.

In the present invention, water or a blowing agent comprising water and nitrogen is used. Here, when water is used as a foaming agent, water has a large heat of vaporization, so the vaporization removes heat from the styrene-based resin and solidifies the foam film,
Uniform closed cells can be formed. The amount of water required for foaming in the present invention is based on styrene resin.
0.10-5.0% by weight, preferably 0.10-2.0%
% By weight. When the content is less than 0.10% by weight, almost no foam is obtained. When the content is 5.0% by weight or more,
There is a problem that poor dispersion is caused, foaming is not performed, and bubbles are coarsened.

When nitrogen is used as a foaming agent, gaseous nitrogen can be used as both a nucleating agent and a foaming agent, so that bubbles can be made fine. However, a sheet foamed with nitrogen alone has high brittleness, and the sheet itself is easily broken. Therefore, when used in combination with water, the brittleness is weakened and the flexibility can be improved. When used in combination, 0.10 to 5.0% by weight and 0.10 to 1.50% by weight, preferably 0.10 to 2.
It is added at 0% by weight and 0.10 to 0.65% by weight.

Furthermore, the present invention has surprisingly found that by adding a nonionic surfactant, a sheet having a high expansion ratio and a beautiful appearance can be obtained even when the above foaming agent is used. This means that nonionic surfactants
It has the function of increasing the affinity with water and the function of uniformly attaching water to the styrene-based resin, thus preventing water from separating from the styrene-based resin and stably extruding a sheet with fine bubbles. It is thought that it is possible.

The nonionic surfactants usable in the present invention include, for example, alkyl and alkyl allyl polyoxyethylene ethers (more specifically, single-chain polyoxyethylene alkyl ethers, polyoxyethylene secondary alcohol ethers, polyoxyethylene secondary alcohol ethers). Oxyethylene alkylphenyl ether, polyoxyethylene sterol ether, polyoxyethylene lanolin derivative, etc.), alkyl allyl formaldehyde condensed polyoxyethylene ether (more specifically, ethylene oxide derivative of alkyl phenol formalin condensate, etc.), polyoxyethylene poly Oxypropylene block polymer, ether type such as polyoxyethylene polyoxypropyl alkyl ether, and polyoxyethylene ether of glycerin ester (more specifically, polyoxyethylene ether) (E.g., xyethylene glycerin fatty acid ester, polyoxyethylene castor oil and hydrogenated castor oil), polyoxyethylene sorbitan fatty acid ester, etc., ether ester type such as polyoxyethylene sorbitol fatty acid ester, polyethylene glycol fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid ester And sorbitan fatty acid esters, propylene glycol fatty acid esters, and sucrose fatty acid esters, and nitrogen-containing types such as fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkylamines, and amine oxides. Among these, the nonionic surfactant is more preferably a single-chain polyoxyethylene alkyl ether, and particularly preferably polyoxyethylene lauryl ether or polyoxyethylene tridecyl ether.

Among the above nonionic surfactants, HLB
(Hydrophile-Lipophile Bal
It is particularly preferable to use a nonionic surfactant having an anth) of 12 to 18, particularly 14 to 17. HL
When B is 18 or more and 12 or less, it is not preferable because water of the foaming agent is separated from the styrene resin and cannot be extruded.

The mixing ratio of the nonionic surfactant is 0.1 to 5.0% by weight, preferably 0.2 to 2.0% by weight, based on the polystyrene resin. Within this range, a 2.5- to 20-fold sheet can be easily obtained, depending on the foaming conditions. Here, when the blending ratio is 0.1% by weight or less, water is separated from the styrene resin, and the foam cannot slide and extrude in the extruder, or water vaporized immediately after molding is liquefied and foamed. The sheet shrinks,
There is a problem that bubbles become coarse. Also,
When the content is 5.0% by weight or more, poor dispersion occurs, and bubbles become coarse.

As the extrusion foaming molding machine used in the production method of the present invention, any known apparatus can be used. In the extrusion, the temperature in the molding machine is 160-170 ° C and the pressure is about 250 kg.
/ Cm ² G. According to the method of the present invention, the thickness is 0.5 to 3.0 mm and the bubble diameter is 0.08 to 0.3.
mm, density 5.0 × 10 ^{-2 to} 2.6 × 10 ^-1 g / cm ³
Can be obtained.

[0015]

The method for producing a polystyrene foam sheet according to the present invention comprises extruding and foaming a polystyrene resin using a foaming agent comprising water or water and nitrogen in an amount necessary for foaming and a nonionic surfactant. Therefore, an environmentally friendly foaming agent can be used without impairing the properties of the sheet.

Further, the nonionic surfactant has an HLB of 12 to 18, and when the nonionic surfactant is used in an amount of 0.1 to 5.0% by weight based on the polystyrene resin, water is reduced to styrene. The polystyrene foam sheet is extruded and foamed without separation from the base resin.

[0017]

【Example】

Example 1 Polystyrene resin (manufactured by Denki Kagaku KK, trade name: HRM)
-3-200, melt index: 0.7) 80 parts by weight, HI resin (Nippon Steel Chemical Co., Ltd., trade name: Estyrene S-61, melt index: 2.5) 20 parts by weight,
1.0 part by weight of talc and 16 parts of HLB as a cell regulator
Of polyoxyethylene lauryl ether of 0.2 parts by weight, and the obtained mixture is supplied from a hopper of a tandem type extruder (manufactured by Mitsubishi Heavy Industries, Ltd.) having a diameter of φ50-φ65, and 50 g of water (liquid) is supplied. / Hr from the tip of φ50 and discharge rate 20 kg / hr (extrusion pressure 300 kg / cm
³ G) When extruded at a temperature of 165 ° C. in the extruder, the expansion ratio is about 4.0 times, the thickness is 1.0 mm, and the cell diameter is 0.1.
A sheet having a smooth appearance of 6 mm was obtained.

Example 2 The amount of polyoxyethylene lauryl ether having an HLB of 16 was changed to 0.4 parts by weight, and the injection amount of water was set to 100 g / h.
Extrusion was carried out under the same conditions as in Example 1 except that r was used.
The obtained sheet has a thickness 1.
The sheet had a smooth appearance of 2 mm and a bubble diameter of 0.20 mm.

Example 3 The amount of polyoxyethylene lauryl ether having an HLB of 16 was changed to 0.6 parts by weight, and the injection amount of water was set to 200 g / h.
Extrusion was carried out under the same conditions as in Example 1 except that r was used.
The obtained sheet has a thickness of 1.6 with an expansion ratio of about 12 times.
mm, and had a smooth appearance with a bubble diameter of 0.25 mm.

Example 4 Extrusion was performed under the same conditions as in Example 3 except that nitrogen was further injected at 50 g / hr. The resulting sheet had a smooth appearance with a foaming ratio of about 16 times and a thickness of 2.5 mm and a bubble diameter of 0.26 mm. Example 5 Extrusion was carried out under the same conditions as in Example 3, except that nitrogen was further injected at 100 g / hr. The obtained sheet has a foaming ratio of about 20 times, a thickness of 3.8 mm, and a bubble diameter of 0.28 mm.
Was a sheet having a smooth appearance.

Example 6 Extrusion was carried out under the same conditions as in Example 1 except that 0.2 parts by weight of polyoxyethylene tridecyl ether having an HLB of 12.6 was used. The obtained sheet has an expansion ratio of 3.
The sheet was about eight times as thick as 0.9 mm thick and had a bubble diameter of 0.18 mm and had a smooth appearance.

Example 7 Extrusion was carried out under the same conditions as in Example 5 except that 0.6 parts by weight of polyoxyethylene tridecyl ether having an HLB of 12.6 was used. The obtained sheet had an expansion ratio of 14
The sheet had a smooth appearance with a thickness of about 1.8 times and a bubble diameter of 0.30 mm.

Comparative Example 1 Extrusion was carried out under the same conditions as in Example 1 except that polyoxyethylene lauryl ether was not used. However, since water separated from styrene in the cylinder of the extruder, the styrene resin slipped and could not be extruded. Comparative Example 2 Extrusion was performed under the same conditions as in Example 1 except that polyoxyethylene nonylphenyl ether having an HLB of 19 was used. However, since water separated from styrene in the cylinder of the extruder, the styrene resin slipped and could not be extruded.

Comparative Example 3 Extrusion was performed under the same conditions as in Example 1 except that polyoxyethylene octyl phenyl ether having an HLB of 9.0 was used. However, since water separated from styrene in the cylinder of the extruder, the styrene resin slipped and could not be extruded.

[0025]

The method for producing a polystyrene foam sheet according to the present invention is an extrusion foam molding method using a polystyrene resin and a foaming agent comprising water or water and nitrogen in an amount necessary for foaming and a nonionic surfactant. Therefore, an environmentally friendly foaming agent can be used without impairing the properties of the sheet.

Further, the nonionic surfactant has an HLB of 12 to 18, and by using the nonionic surfactant in an amount of 0.1 to 5.0% by weight based on the polystyrene resin, water is reduced to styrene. The polystyrene foam sheet can be extruded and foamed without being separated from the base resin.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08J 9/12

Claims (1)

(57) [Claims] 1. A polystyrene resin containing water or a foaming agent comprising water and nitrogen , and having a H of 12-18.
Nonionic surfactant having LB is converted to polystyrene resin
A method for producing a polystyrene foam sheet, characterized in that the foam is extruded and foamed using 0.1 to 5.0% by weight of fat .