JPH028231A - Flame-retardant heat-insulation or cushioning material - Google Patents

Abstract

PURPOSE:To obtain a cushioning material or a heat-insulation material effective in preventing the accumulation of electrostatic charge and having excellent flame-retardance and heat-insulation by treating foamed polystyrene with an agent such as fuming sulfuric acid, chlorosulfonic acid or fluorosulfonic acid and converting the treated product to an inorganic or organic salt. CONSTITUTION:A foamed polystyrene is treated with one or more kinds of acid selected from fuming sulfuric acid, chlorosulfonic acid, fluorosulfonic acid and sulfur trioxide and neutralizing the acid-treated product to a salt with an alkali or alkaline-earth metal hydroxide, etc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a flame-retardant insulation or cushioning material, and its purpose is to provide a polystyrene-based insulation or cushioning material that has electrical conductivity and flame retardancy. It is to be.

[Conventional technology]

In recent years, polystyrene has been widely used as a general-purpose synthetic resin for various purposes. In particular, the foam is lightweight, has excellent heat insulation, cushioning properties, and is relatively inexpensive, so it is widely used as a cushioning material for packaging, as an insulation material for buildings, and as a composite material. Widely used in the field of

However, polystyrene foams have the drawbacks of being easily charged with static electricity due to friction, easily burning with black smoke, and easily attacked by organic solvents.

On the other hand, there are an increasing number of products incorporating many integrated circuits, including so-called household electrical appliances such as televisions, videos, stereos, microwave ovens, and refrigerators, as well as various measuring instruments, medical devices, and the like. The packaging of these products during transportation includes:
Polystyrene foam is often used as a cushioning material.

However, these integrated circuits tend to be easily destroyed by static electricity, and there is a risk that they will be damaged by the effects of static electricity during transportation. Therefore, in order to prevent static electricity in cushioning materials, cushioning materials have been developed in which conductive films are attached to both sides of a foam sheet to give conductivity. Rather, it forms a capacitor due to the high insulation properties of the polystyrene foam that exists in the middle, and if this capacitor has no leakage path for the charged electric charge, damage from static electricity may occur. could be. Furthermore, although polystyrene foam has excellent heat insulating properties, it has the disadvantage that it belongs to the class of plastics that is easily flammable. Also,
Its surface is oleophilic, and once internal condensation occurs, its insulation properties are significantly reduced. To make polystyrene flame retardant,
A combination of halogenated flame retardants and antimony trioxide is said to be useful, but when these are added, not only do they tend to deteriorate the physical properties characteristic of polystyrene, but they also become expensive. .

Therefore, there has long been a desire to find a way to make use of the various excellent properties of polystyrene, especially its foam, while imparting conductivity to prevent static electricity build-up and flame retardancy to eliminate the drawback of being easily flammable. .

[Problems to be Solved by the Invention] The problems to be solved by the present invention are to solve each of the above-mentioned difficulties of conventional polystyrene foams, and more specifically, to prevent static electricity charging, and to create a material with excellent difficulties. The goal is to develop cushioning and heat insulating materials that are flammable and have significantly improved heat insulating properties.

[Means to solve the problem]

As a means to solve this problem, polystyrene foam is treated with any one of fuming sulfuric acid, chloro or fluorosulfonic acid, or sulfur trioxide, and then a foamed polystyrene derivative obtained by converting this into an inorganic or organic salt is used as a heat insulating material or as a foamed polystyrene derivative. This problem can be solved by using it as a buffer material.

The inventors of the present invention have conducted various studies in order to improve each of the drawbacks of the conventional polystyrene foam described above, and have found that the product obtained by subjecting the polystyrene foam to the above-mentioned treatment is insulated at high temperatures, for example, 90°C or higher. It has been found that not only the properties but also the conductivity and flame retardance are significantly improved.

It has been little known to date that polystyrene foam can be sulfonated by treating it with at least one of fuming sulfuric acid, chloro or fluorosulfonic acid, and sulfur trioxide (hereinafter referred to as sulfonating agents) as described above. It is only known that a polystyrene foam whose surface is sulfonated using a small amount of chlorosulfonic acid can be used as a soil improvement material. Originally, polystyrene foam is a foam consisting of almost closed pores, and it is a common belief in this type of industry that even if this foam is sulfonated, only the surface thereof will be sulfonated. Therefore, the conventional wisdom in this field has been that even if a polystyrene foam is sulfonated, only the surface thereof can be sulfonated.

However, according to the research of the present inventor, when polystyrene foam was actively sulfonated to the inside using a sulfonating agent, it was surprisingly found that most of the inside of the polystyrene foam was sulfonated without any damage to the individual cells of the polystyrene foam. It has also been discovered that polystyrene foams that are sulfonated to the inside have significantly improved heat insulation properties compared to those that are sulfonated only on the surface.

It has also been discovered that polystyrene foam, which has been actively sulfonated to the inside, has excellent conductivity and flame retardancy, and the present invention was completed based on these new facts. It is.

[Structure and operation of the invention]

The polystyrene used in the present invention is a homopolymer, and copolymers with butadiene, acrylonitrile, etc. can also be used, but the effects of the present invention are more likely to be exhibited as the polystyrene content is higher.

The proportion of styrene and other monomers in the above copolymer is usually about 75 mol%, preferably about 50 mol%. There are no particular limitations on the form of the copolymer, including block copolymerization, graft copolymerization, and other random copolymerization.

In the present invention, it is essential to use foamed polystyrene. Various polystyrene foams can be used as long as they are foamed, and it is particularly preferable to use the polystyrene foam itself, and it is preferable to avoid pulverized polystyrene foams. Polystyrene foam can be used in packaging materials that are cheap and easily available, such as cushioning materials such as sheets, ribbons, and lumps, as well as molded objects such as plates for insulation, cases, objects, containers, etc. It is also possible to utilize already finished polystyrene foam.

In the present invention, the object to be acid-treated is a polystyrene foam, and even if the styrene monomer is subjected to acid treatment and then polymerized (including copolymerization), the intended purpose will not be achieved. Further, even if polystyrene is sulfonated and then foamed, a sufficient foam cannot be obtained. For example, styrene monomer is treated with chlorosulfonic acid to form a sodium salt, which is then polymerized and is water-soluble.

In particular, since the present invention uses polystyrene foam, conventional waste materials that have been used as heat insulating materials and cushioning materials can also be used, which is significant in that it has developed a new use for waste materials.

The fuming sulfuric acid used in the present invention is 20 to 30% oleum, and a commercially available product can be used as is.

Although chlorosulfonic acid is commonly used, fluorosulfonic acid can also be used. Although liquid sulfur trioxide is used as the sulfur trioxide, it is also possible to react in a gaseous state. Conditions for the reaction between the polystyrene foam and these acids are such that the inside of the foam can be positively sulfonated.

There is no particular limitation as long as the inside can be sulfonated, but
For example, usually 90-100°C, preferably 95-100°C
When the reaction is carried out for about 3 to 8 hours at 00°C, and for more than 72 hours, preferably for about 72 to 240 hours at room temperature, the sulfur content of the product will be 16 to 21 for any sulfonating agent.
% and reach a sulfonated range almost to the inside.

Polystyrene foam treated with a sulfonating agent is washed with water until sulfate ions are no longer detected, neutralized, and converted into a salt.
The flame retardant heat insulating material of the present invention is obtained by drying at 0 to 80°C.

As the alkali used for neutralization, general alkali and alkaline earth metal hydroxides, ammonia, and organic amines such as alkyl amines such as ethanolamine are preferably used. However, in order to impart other properties to the heat insulating material of the present invention, it is desirable to use a metal salt that is optimal for the properties. For example, lithium salts and sodium salts are more effective for imparting conductivity, calcium salts and barium salts are more effective for flame retardancy, and sodium salts and organic amine salts are more effective for moisture absorption and desorption properties. Are suitable.

The material thus obtained exhibits extremely excellent thermal insulation properties, not only significantly superior to polystyrene foam at high temperatures, e.g., over 90°C, but also superior to surface-sulfonated polystyrene foam. It's also excellent.

Therefore, it is extremely suitable as a heat insulating material.

Furthermore, the conductivity and flame retardance are significantly improved compared to polystyrene foam, and the drawbacks of conventional polystyrene foam can be greatly improved, making it extremely suitable as a cushioning material.

The heat insulating or cushioning material of the present invention can be used by cutting or crushing it into an appropriate shape.

(Examples) The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples. However, parts indicate parts by weight.

[Example 1] 40 parts of expanded polystyrene and 2 parts of expanded polystyrene were placed in a flask equipped with a cooling tube.
Add 800 d of 5% oleum and react at 95-100''C for 8 hours while stirring occasionally to wet the surface of the polystyrene.The solid content was separated and washed with water. Wash for 60~80
Dry at °C.

The sulfur content of this was 19.02%. This was neutralized with lithium hydroxide and dried again at 70-80°C.

This product was sulfonated to the inside due to the above-mentioned sulfur content, and when its cross section was examined, it was found that most of the cells of the polystyrene foam remained intact.

The insulation properties of this material were equivalent to ordinary polystyrene foam in the temperature range from 0 to 90°C, but
The thermal insulation properties in the range up to 0°C were significantly improved.

The conductivity was 1 x 10'Ω/mouth, and the flammability was 30 seconds in the flame of a gas burner with a length of about 3 cm without burning. In addition, expanded polystyrene (not sulfonated) gave off graphite and burned.

[Example 2] 500rn of chlorosulfonic acid in 30 parts of expanded polystyrene
1 was added, the condenser was turned off, and the mixture was reacted at 95 to 100°C for 8 hours. It was thoroughly washed with warm water, neutralized with an aqueous solution of caustic soda, and dried at 60 to 80°C. The sulfur content of this was 16.38%.

[Example 3] 100 parts of liquid sulfur trioxide was added to 25 parts of polystyrene foam, and the mixture was reacted at room temperature for IO days. It was neutralized with a caustic soda aqueous solution and dried at 70-80°C.

The sulfur content of this product was 19.6%, and it was sulfonated almost to the inside. In addition, the results of measuring the heat insulation properties, conductivity, and flame retardance of each are shown in Table 1 below.

Claims (1)

[Claims] (1) A flame-retardant heat insulating material whose main component is a polystyrene derivative obtained by treating a polystyrene foam with at least one of fuming sulfuric acid, chloro or fluorosulfonic acid, and sulfur trioxide, and then converting the foam into a salt. Buffer material.