JPH0645719B2 - Method for producing flame-retardant styrenic resin plate foam - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a flame-retardant styrene resin plate-shaped foam.

(Prior Art) Generally, a flame retardant resin is produced by mixing a flame retardant with a synthetic resin. Various flame retardants are known. The flame retardant includes an inorganic compound and an organic compound. As the inorganic compound, antimony oxide, phosphate or the like is used, and as the organic compound, various halogen compounds are exclusively used.

There is no particular difficulty in using a styrene-based resin as a flame-retardant resin and using it as a non-foamed resin. This is because when the non-foamed product is used, it is sufficient to simply mix the flame retardant with the styrene resin. However,
When trying to make a flame-retardant styrene resin into a foam,
Does not clean up as easily as non-foamed. This is because the flame retardant may hinder the foamability of the resin. Therefore, it is necessary to specially select and use the flame retardant or to consider the usage method. In particular, since the organic flame retardant is prone to be decomposed, it is necessary to add a stabilizer to the organic flame retardant, so that the stabilizer causes a new problem of affecting the function of the foaming agent.

Until now, aliphatic hydrocarbons such as propane and butane have been often used as a blowing agent for styrene resins. Since aliphatic hydrocarbons are generally poor in reactivity, as long as they are used, the relationship with the foaming agent and the stabilizer does not become a serious problem. However, aliphatic hydrocarbons are flammable and therefore there is a fire hazard with them.
Moreover, since it is difficult to control the bubbles themselves, the method using an aliphatic hydrocarbon cannot be said to be excellent.

Therefore, halogenated aliphatic hydrocarbons have come to be used as a foaming agent. However, among the halogenated aliphatic hydrocarbons that are used to safely obtain good foams, perchlorofluorocarbons (e.g. dichlorodifluoromethane, trichloromonofluoromethane) are in the stratosphere and are harmful to UV-B (wavelength range). It is known to destroy the ozone tank that absorbs (290-320 nm) to prevent it from reaching the surface of the earth and maintains the atmospheric temperature, and its use is regulated.

The present inventor has developed a monochlorodifluoroethane (hereinafter referred to as F142b) as a foaming agent to replace perchlorofluorocarbons.
And / or difluoroethane (hereinafter referred to as F152a) and a halogenated hydrocarbon as a flame retardant were used to obtain a foam. However, since both F142b and F152a contain a large number of hydrogen atoms, they are flammable to a lesser degree than aliphatic hydrocarbons, and a good flame-retardant foam could not be obtained.

On the other hand, the present inventor has used hexabromocyclododecane, 2,2′-bis- (4-allyloxy-3,5-dibromophenyl) as a flame retardant for producing a flame-retardant styrene resin plate-like foam. )
It was found that propane and / or 2,4,6-tribromophenylallyl ether is suitable, and a method of adding the flame retardant to a polystyrene resin and performing extrusion foaming was previously proposed (Japanese Patent Publication No. 60- (See 29743). Therefore, by combining the above two methods, using F142b and methyl chloride as a foaming agent, adding the above mixed flame retardant as a flame retardant, it was tried to obtain a flame-retardant styrene resin foam However, a good flame-retardant foam could not be obtained.

(Problems to be Solved by the Invention) In order to improve the above-mentioned points, the present inventor is known to destroy the ozone layer as a foaming agent, and a foaming agent replacing perchlorofluorocarbons whose use is restricted. As monochlorodifluoroethane (hereinafter referred to as F142b)
And / or a mixture of difluoroethane (hereinafter referred to as F152a) and another halogenated aliphatic hydrocarbon is used, and a halogen element-containing multi-membered cyclic alkane and / or phenyl aryl ether derivative and / or polymer is used as a flame retardant, When these were contained in a styrene-based resin and foamed, it was found that a good flame-retardant styrene-based resin plate-shaped foam was obtained, which led to the completion of the present invention. Monochlorodifluoroethane with low destructive power
(Hereinafter referred to as F142b) and / or difluoroethane (hereinafter referred to as F142b)
152a) and other halogenated aliphatic hydrocarbons as a blowing agent to provide a flame-retardant styrenic resin foam.

(Means for Solving the Problems) The gist of the present invention is to use F142b and / or 152a as a foaming agent.
And mixtures of other halogen-aliphatic hydrocarbons and mixtures with hexabromocyclododecane and 1,2,5,6-tetrabromocyclooctane and / or poly (pentabromobenzyl) acrylate as flame retardants A method for producing a flame-retardant styrenic resin plate-shaped foam, which comprises extruding a mixture of these foaming agent, flame retardant and styrene resin in a molten state from an extruder to form a foam.

That is, the present invention, as a foaming agent, F142b and / or 1
Using a mixture of 52a and other halogenated aliphatic hydrocarbons, hexabromocyclododecane and
1,2,5,6-tetrabromocyclooctane and / or poly
Since a mixture with (pentabromobenzyl) acrylate is used, the risk of causing ozone depletion is less than when the blowing agent is a perchlorofluorocarbon.
A good foamed plate with no cavities inside, which can be uniformly foamed up to a high expansion ratio by appropriately selecting the mixing ratio of F142b and / or 152a and another halogenated aliphatic hydrocarbon. You can get the body. Further, since the above flame retardant is used as the flame retardant, it dissolves more uniformly in the styrene resin compared to the case where the inorganic flame retardant is used, so that the styrene resin plate-like material having a large flame retardance is used. A foam can be obtained.

Next, the present invention will be described in detail. The styrene-based resin that can be used in the method of the present invention is not limited to a styrene-based homopolymer, but includes a copolymer. The styrene-based monomer contains styrene and styrene derivatives such as methylstyrene and ethylstyrene. Further, the copolymer contains 50% by weight or more of a styrene-based monomer, and the balance thereof includes a monomer. Examples of other monomers include methyl methacrylate, acrylonitrile, maleic anhydride and the like. In addition, the styrene-based resin also includes a blend obtained by mixing the homopolymer or copolymer with another resin. Other resins include
Examples thereof include polyethylene and synthetic rubber. The blend contains 50% by weight or more of styrene.

As mentioned above, a mixture of monochlorodifluoroethane and / or difluoroethane and another halogenated aliphatic hydrocarbon is used as the blowing agent. Other halogenated aliphatic hydrocarbons include methyl chloride, ethyl chloride, methylene chloride, monochlorodifluoromethane (F22), dichloromonofluoromethane (F21), and the like.
Monochlorodifluoromethane (F12), which is said to have a large ozone depletion ability, also has good properties as a foaming agent for styrene resin foams, so within the regulation range, F142b and / or F152a and other halogenated fats It can be mixed with the mixture with the group hydrocarbon in any proportion.

The mixing ratio of F142b and / or F152a and other halogenated aliphatic hydrocarbon and / or F12 can be appropriately determined depending on the properties of the desired foam. Generally, the amount of the mixed foaming agent added is 5 to 20% by weight based on the styrene resin. If the addition amount of this mixture is 5% by weight or less, it is not possible to foam at a high magnification, and if it is 20% by weight or more, the foaming agent bumps from the resin and it becomes difficult to foam uniformly and finely. Is.

These mixed foaming agents may be added to the resin separately, or may be premixed before being added to the resin. Further, the addition may be carried out in the extruder or may be added to the resin before being put into the extruder.

In the present invention, a mixture of tetrabromocyclododecane and 1,2,5,6-tetrabromocyclooctane and / or poly (pentabromobenzyl) acrylate is used as a flame retardant. The amount of the anti-twisting agent added is 0.5 to 10% by weight based on the styrene resin. The reason is that if the amount is 0.5% by weight or less, the effect of the flame retardant is not sufficiently exerted. This is because the sex becomes worse.

In the present invention, the order of adding the foaming agent and the flame retardant to the styrene resin is not particularly limited. However, a desirable method is to dry-blend the flame retardant with the styrenic resin, put the mixture in an extruder, and press the foaming agent in the extruder.

In addition, in the method of the present invention, in addition to the above-mentioned foaming agent and flame retardant, a foam control agent such as a stabilizer or talc, a coloring agent such as a pigment dye, or a surface active agent such as a nonionic surfactant. Agents can be added.

(Example) Below, an Example and a comparative example are described and the method of this invention is demonstrated concretely. Hereinafter, simply, “part” means “part by weight”. The flame retardancy of the foam is expressed by SE time.SE time is the self-extinguishing time performed according to the method of JIS A-9511. SE time of 3 seconds or less is good flame retardancy. And

Examples 1 to 7 and Comparative Examples 1 to 3 Table 1 shows 0.7 parts of fine powder talc as a cell regulator, 100 parts of polystyrene (Nippon Steel Chemical KK Estyrene G-10), a flame retardant and a stabilizer. Mixed in different proportions,
Approximately 15 kg / h to an extruder that combines 40 mm diameter and 50 mm diameter
It was supplied at a rate of.

As the foaming agent, a mixture of F142b and / or F152a and another halogenated aliphatic hydrocarbon in a ratio shown in Table 1 was press-mixed into the resin from near the tip of an extruder having a diameter of 40 mm. As a mouthpiece, the tip has a thickness of 0.6 mm, a width of 60 mm, and a length of 5
Use the one that has a rectangular resin discharge port of mm, the inlet size is substantially equal to the resin discharge size at the tip of the die, the outlet size is 12 mm thick and 120 mm wide, and from the vicinity of the inlet to the outlet A molding tool was used in which the resin passage wall provided with a resin passage having a length of 50 mm that was gradually expanded toward the surface was coated with a fluororesin.

The resin supplied to the extruder with a caliber of 40 mm is heated to 220 ° C and melted and kneaded.
The temperature was adjusted to 110 to 130 ° C and the solution was supplied to the base. The resin discharged from the mouthpiece is largely foamed, with a thickness of 15-23 mm and a width of 150-200 mm.
The extrusion stability and the moldability were good.

(Effect of the Invention) As described in detail above, according to the present invention, since a mixture of monochlorodifluoroethane and / or difluoroethane and another halogenated aliphatic hydrocarbon is used as a foaming agent, a styrenic resin having a high expansion ratio is used. By the way, since it is possible to uniformly and finely foam and hexabromocyclododecane and 1,2,5,6-tetrabromocyclooctane and / or poly (pentabromobenzyl) acrylate are used as flame retardants, this is Sufficient flame retardancy is obtained because it has a great affinity for styrene resins. Thus, a foam having excellent flame retardancy can be easily obtained.

Claims (1)

[Claims] 1. A mixture of monochlorodifluoroethane and / or difluoroethane and another halogenated aliphatic hydrocarbon is used as a blowing agent, and hexabromocyclododecane and 1,2,5,6-tetrabromo are used as flame retardants. A mixture of cyclooctane and / or poly (pentabromobenzyl) acrylate is used, and a mixture of these foaming agent, flame retardant and styrene resin is extruded from the extruder in a molten state to form a foam. A method for producing a flame-retardant styrene resin plate-like foam.