JP2001261875A - Method for manufacturing styrene-based foamable resin particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a styrene-based foamable resin particle, which contains an organic bromide compound, has a narrow particle diameter distribution, and can give a foamed body having excellent appearance and an excellent cell shape in the inner part of the foamed item. SOLUTION: The styrene-based foamable resin particle is obtained by polymerizing a styrene-based monomer in a suspension state in the existence of 0.4 to 6 pts.wt. of an organic bromide compound and 0.0001 to 0.05 pts.wt. of an amide-based compound each based on 100 pts.wt. of the styrene-based monomer using a hardly water-soluble inorganic salt as a suspending agent and adding 1 to 20 pts.wt. of a foaming agent during or after suspension polymerization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension polymerization method for a monomer containing styrene as a main component, and the obtained styrene-based expandable resin particles have a narrow particle size distribution and an excellent appearance of a foam molded article. The present invention relates to a method for producing styrenic foamable resin particles containing an organic bromine compound.

[0002]

2. Description of the Related Art Styrene-based expandable resin particles are relatively inexpensive and can be foam-molded with low-pressure steam or the like without using a special method. It is a useful material. However, since it is an easily combustible material, self-extinguishing properties are required in the field of building materials and the like. Organic bromine compounds are generally used to develop self-extinguishing properties in resins such as styrene, but when organic bromine compounds are used in the production of styrene-based expandable resin particles, Since the size of the cells is too small, there is a problem that the resin on the surface of the foamed molded product is melted during molding and the appearance of the foamed molded product is significantly deteriorated.

[0003] Japanese Patent Publication No. 59-21340,
No. 305839 discloses a method in which the size of cells is improved by using an organic bromine compound and an amine compound in combination to obtain a foam molded article having uniform cells.

[0004]

However, since a water-soluble polymer is used as a suspending agent for dispersing a styrene-based monomer in an aqueous medium, the internal water content of the obtained styrene-based foamable resin particles is reduced. And it is difficult to control the morphology of the bubbles, and the problem that the water-soluble polymer is grafted and remains on the surface of the styrene-based expandable resin particles, resulting in reduced fusion and insufficient strength. there were. Also, by using a water-soluble polymer as a suspending agent,
There is also a problem that the obtained styrene-based expandable resin particles have a wide particle size distribution and a low product yield.

The present invention has been made in view of the above-mentioned conventional problems, and contains an organic bromine compound, and has a narrow particle size distribution of the obtained styrene-based expandable resin particles. It is an object of the present invention to provide a method for producing styrene-based expandable resin particles from which a foamed molded article having an excellent cell morphology can be obtained.

[0006]

According to the first aspect of the present invention, an organic bromine compound is used in an amount of from 0.4 to 100 parts by weight of a styrene monomer.
The styrene monomer is subjected to suspension polymerization using a poorly water-soluble inorganic salt as a suspending agent in the presence of 6 parts by weight and the amide compound in an amount of 0.0001 to 0.05 parts by weight. A method for producing styrene-based expandable resin particles, comprising adding 1 to 20 parts by weight of a foaming agent to 100 parts by weight of the styrene-based monomer after completion of the suspension polymerization.

It is important to note that the constituents of the present invention are characterized by using a poorly water-soluble inorganic salt as a suspending agent in the presence of an organic bromine compound and an amide compound in suspension polymerization of a styrene monomer. Suspension polymerization, and then adding a foaming agent.

Next, the operation of the present invention will be described. The present inventors have conducted intensive studies to solve such problems, and as a result, in the production of styrene-based expandable resin particles using an organic bromine compound, a water-insoluble inorganic salt was used as a suspending agent, and an amide-based resin was used. By the presence of the compound,
The particle size distribution of the obtained styrene-based expandable resin particles is narrow,
In addition, they have found that a foamed molded article having an excellent appearance and a good internal cell shape can be obtained, and the present invention has been completed.

By using a poorly water-soluble inorganic salt as a suspending agent, the resulting styrene-based foamable resin can be compared with the case of using a water-soluble polymer as described in JP-A-02-305839. The particle size distribution of the particles becomes narrow, and the yield as a product can be improved. Further, the effect of reducing the internal water content of the obtained styrene-based expandable resin particles and easily controlling the cell shape during foam molding can be obtained.

Further, since the suspension polymerization is carried out in the presence of an amide compound, it is possible to prevent the water-soluble polymer from being grafted and remaining on the surface of the styrene-based expandable resin particles, thereby improving the fusion. Sufficient strength can be obtained.

As described above, according to the present invention, a foamed molded article containing an organic bromine compound, having a narrow particle size distribution of the obtained styrene-based foamable resin particles, and having excellent appearance and internal cell morphology after foam molding. Can be provided for producing styrene-based expandable resin particles.

Further, since the styrene-based expandable resin particles obtained by the production method according to the present invention contain an organic bromine compound, a foamed molded article made from the resin particles has excellent self-extinguishing properties and is useful for building materials and the like. Can be used in the field.

(Styrene monomer) Examples of the styrene monomer usable in the present invention include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene and p-methylstyrene. Ethylstyrene, 2,4-dimethylstyrene, p-methoxystyrene, p-phenylstyrene, o-chlorostyrene,
m-chlorostyrene, p-chlorostyrene, 2,4-dichlorostyrene, pn-butylstyrene, pt-butylstyrene, pn-hexylstyrene, p-octylstyrene, styrenesulfonic acid, styrenesulfonic acid Sodium and the like.

Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylic acid-2
-Alkyl acrylates having 1 to 10 carbon atoms, such as ethylhexyl. Methyl methacrylate,
Examples thereof include alkyl esters of methacrylic acid having 1 to 10 carbon atoms such as ethyl methacrylate, propyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate.

Unsaturated compounds having a hydroxyl group such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, and hydroxybutyl methacrylate. Examples thereof include nitrile group-containing unsaturated compounds such as acrylonitrile and methacrylonitrile.

Organic acid vinyl compounds such as vinyl acetate and vinyl propionate; ethylene, propylene, 1-butene,
And unsaturated monoolefins such as 2-butene and isobutene. And diene compounds such as butadiene, isoprene, and chloroprene.

Examples include vinyl halide such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride. Examples thereof include vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, and vinyl hexyl ketone. And vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether. N-vinylpyrrolidone, N-vinylindole, N
And N-vinyl compounds such as -vinylcarbazole and N-vinylpyrrole.

Acrylamine, methacrylamine, N-
Unsaturated compounds having an amine group, such as methylolacrylamine and N-methylolmethacrylamine. And unsaturated carboxylic acids such as acrylic acid, methacrylic acid and itaconic acid. N-phenylmaleimide,
N- (methyl) phenylmaleimide, N- (hydroxy) phenylmaleimide, N- (methoxy) phenylmaleimide, N-benzoic maleimide, N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropyl Maleimide compounds such as maleimide, Nn-butylmaleimide, N-isobutylmaleimide, Nt-butylmaleimide and the like can be mentioned.

Crosslinkable polyfunctional vinyl compounds such as divinylbenzene, ethylene glycol dimethacrylate and the like can be mentioned. Further, various vinyl compounds such as unsaturated compounds having an epoxy group such as glycidyl acrylate and glycidyl methacrylate may be used in combination.

(Organic bromine compound) The range of the amount of the organic bromine compound added is 0.4 to 6 parts by weight based on 100 parts by weight of the styrene monomer. If the amount is less than 0.4 parts by weight, self-extinguishing properties may not be easily exhibited. Further, even if it exceeds 6 parts by weight, it is difficult to enhance the self-extinguishing performance, which may be disadvantageous in terms of cost. Specific types of the organic bromine compound will be described later.

(Amide Compound) The amount of the amide compound is 0.0001 to 0.05 parts by weight based on 100 parts by weight of the styrene monomer. If the amount is less than 0.0001 part by weight, it is difficult to obtain a foamed molded article having an excellent appearance, and if the amount is more than 0.05 part by weight, deformation of the styrene-based expandable resin particles and the entire suspension during the suspension polymerization are performed. There is a possibility that a problem such as agglomeration of the resin may occur.

The amide compound may be added either before or during suspension polymerization, or may be added in two or more portions. In addition, one kind of the amide compound can be used alone, or two or more kinds can be used. Specific types of amide compounds will be described later.

(Suspension) Suspensions which can be used in the present invention will be described in detail later, and examples thereof include finely divided water-insoluble inorganic salts such as tricalcium phosphate and sodium pyrophosphate. Further, an anionic surfactant such as sodium alkylsulfonate and sodium alkylbenzenesulfonate may be used in combination with the above suspending agent. The use of an anionic surfactant is preferred because the particle size distribution of the resulting styrene-based expandable resin particles is further narrowed.

In the present invention, Japanese Patent Application Laid-Open No. 8-253
A slurry containing a finely divided water-insoluble inorganic salt obtained by subjecting a poorly water-soluble inorganic salt to a grinding treatment in an aqueous medium to which a dispersion stabilizer is added as shown in No. 510 is used. It can also be used. In this case, the particle size distribution of the obtained styrene-based expandable resin particles becomes narrow,
preferable.

(Blowing agent) Examples of the blowing agent usable in the present invention include propane, normal butane, isobutane, normal pentane, isopentane, neopentane, and the like.
Examples thereof include aliphatic hydrocarbons such as hexane. Alicyclic hydrocarbons such as cyclobutane and cyclopentane; Examples include halogenated hydrocarbons such as methyl chloride, dichlorofluoromethane, and perfluorocarbon. Examples include physical foaming agents such as fluorinated hydrocarbon ethers such as hydrofluoroether and perfluorobutylethyl ether. One of these foaming agents can be used alone, or two or more can be used in combination.

The foaming agent is added in an amount of 1 to 20 parts by weight based on 100 parts by weight of the styrene monomer. If the amount is less than 1 part by weight, an appropriate expansion ratio may not be obtained. If the amount exceeds 20 parts by weight, the production cost may increase.

In the manufacturing method according to the present invention,
After the styrene monomer is dispersed in an aqueous medium in the presence of a polymerization initiator and a suspending agent and a surfactant, the polymerization reaction is started, and a foaming agent is added during suspension polymerization or the suspension is added. After completion of the polymerization, a blowing agent can be impregnated. When dispersing the styrene-based monomer in the aqueous medium, the styrene-based monomer may be charged all at once or may be added gradually.

(Other Additives) If necessary, at the start of suspension polymerization or during suspension polymerization, electrolytes such as lithium chloride, potassium chloride, sodium chloride, magnesium chloride, calcium chloride, sodium sulfate and sodium nitrate , Sodium carbonate, sodium bicarbonate, and the like, and organic salts such as sodium acetate, disodium succinate, sodium behemate, and sodium benzoate.

The polymerization initiator usable in the present invention includes, for example, azo compounds such as azobisisobutyronitrile, cumene hydroperoxide, dicumyl peroxide, t-butylperoxy-2-ethylhexano. Ethate, t-butyl peroxybenzoate, benzoyl peroxide, t-butyl peroxyisopropyl carbonate, t-butyl peroxy 2-ethylhexyl monocarbonate, 2-methyl-2-butylperoxy 2-ethylhexyl monocarbonate, pentyl peroxy 2 -Ethylhexyl monocarbonate, hexylperoxy 2-ethylhexyl monocarbonate,
Soluble in styrene monomers such as lauroyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane and 1,1-di-tert-butylperoxy-2-methylcyclohexane Suitable initiators.

The above polymerization initiators can be used singly or as a mixture of two or more. The amount of the polymerization initiator used is preferably 0.01 to 3 parts by weight based on 100 parts by weight of the styrene monomer. If the amount is less than 0.01 part by weight, the polymerization rate becomes too slow, and if it is more than 3 parts by weight, the production cost may increase.

The styrene-based monomer includes a methyl methacrylate-based copolymer as a foam-forming agent, polyethylene wax, talc, ethylenebisstearylamide, methylenebisstearylamide, ethylene-vinyl acetate copolymer resin and the like. Can be added.

If necessary, in order to adjust the molecular weight of the suspension polymerization reaction system, an alkyl mercaptan such as dodecyl mercaptan and a chain transfer agent such as α-methylstyrene dimer may be added during suspension polymerization. it can. The amount of the chain transfer agent is preferably 0.01 to 3 parts by weight based on 100 parts by weight of the styrene monomer to be polymerized.

In the present invention, if necessary, a plasticizer of a polymer (styrene-based expandable resin particles) formed by a suspension polymerization reaction can be added. Examples of the plasticizer include phthalic acid esters such as dioctyl phthalate, fatty acid esters such as glycerin tristearate and dioctyl adipate, acetylated monoglycerides such as glycerin diacetmonolaurate, and organic compounds such as toluene, xylene, cyclohexane, and liquid paraffin. And the like.

Further, additives generally used in the production of styrene-based expandable resin particles, such as a flame retardant aid, an antistatic agent, a conductive agent, a cell nucleating agent, and a particle size distribution modifier, may be appropriately added. , Butadiene rubber, and styrene / butadiene rubber.

Next, as in the second aspect of the present invention, the addition amount of the poorly water-soluble inorganic salt is preferably 0.01 to 10.0 parts by weight based on 100 parts by weight of the styrene monomer. . Thereby, the effect according to the present invention can be reliably obtained. If the amount of the suspending agent is less than 0.01 part by weight, the particle size of the resulting styrene-based expandable resin particles may be extremely large, or the whole may be solidified during suspension polymerization. If the amount is more than 10.0 parts by weight, not only the particle size of the obtained styrene-based expandable resin particles becomes extremely small, but also the production cost may be high. A more preferred range is from 0.05 to. 3.0
Parts by weight.

Next, as in the third aspect of the present invention, the poorly water-soluble inorganic salt is selected from tricalcium phosphate, hydroxyapatite, magnesium phosphate, aluminum hydroxide, calcium sulfate, talc, kaolin, and bentonite. It is preferable that one or more kinds of the hardly water-soluble inorganic salts in the form of fine particles are used. By using these, it is possible to control the particle size of the styrene foamable resin particles.

Next, an alkali metal salt of persulfuric acid or an alkali metal salt of sulfurous acid is used as in the present invention.
0.00 parts by weight based on 100 parts by weight of the styrene monomer
It is preferable to add 005 to 0.003 parts by weight while the polymerization conversion during suspension polymerization is 0 to 30%. Thereby, the particle size distribution of the obtained styrene-based expandable resin particles can be narrowed. If the addition amount is less than 0.00005 parts by weight or exceeds 0.003 parts by weight, there is a possibility that styrene-based foamable resin particles having an excellent appearance of the foamed molded article and an excellent cell morphology inside the foamed article cannot be obtained.

When added after the polymerization conversion exceeds 30%, the polymerization particle size may be increased. The polymerization conversion is the mole fraction of styrene monomer consumed in the polymerization.

As the alkali metal salt of persulfuric acid,
Lithium persulfate, sodium persulfate, potassium persulfate and the like can be used. As the alkali metal salt of sulfurous acid, lithium sulfite, sodium sulfite, potassium sulfite and the like can be used.

Next, as in the invention of claim 5, the amide compound is preferably an amide according to the following (1) or (2) represented by the general formula R1CONR2R3. (1) R2 and R3 are both hydrogen and R1 is 6 to
Amide compound (R1CONH2) which is an alkyl group or a cycloalkyl group having 20 carbon atoms. (2) R2 and R3 are not hydrogen at the same time;
An amide compound wherein 3 is hydrogen or an alkyl group, cycloalkyl group or oxyalkyl group having 1 to 15 carbon atoms, and R1 is an alkyl group or cycloalkyl group having 4 to 20 carbon atoms ( R1
CONR2H, R1CONR2R3).

By using these amide compounds,
A sufficient strength can be obtained by improving the fusion. Specific examples of the amide compounds (1) and (2) include n-decylamide, n-dodecylamide, tetradecylamide, dihexylamide, cyclohexylamide, dicyclohexylamide, and the like.

In the amide compound according to (1), R1 is an alkyl or cycloalkyl group having 6 to 20 carbon atoms. If the number of carbon atoms is less than 6, or if it exceeds 20, the effect of improving fusion and obtaining sufficient strength may be difficult to obtain.

In the same manner, in (2), R2 and R
3 is an alkyl group having 1 to 15 carbon atoms, a cycloalkyl group or an oxyalkyl group. 15 carbon atoms
If the number exceeds the number, there is a possibility that the effect of improving the fusion and obtaining sufficient strength may be difficult to obtain. In (2), R1
Is an alkyl or cycloalkyl group having 4 to 20 carbon atoms. If the number of carbon atoms is less than 4, 2
If the number exceeds 0, the effect of improving the fusion and obtaining sufficient strength may be difficult to obtain.

As described in claim 7, among the above amide compounds, R1 is represented by the general formula R1CONR2R3, wherein R1 is an alkyl or cycloalkyl group having 6 to 20 carbon atoms, and R2 and R3 are It is more preferable to use an amide-based compound that is an oxyalkyl group. By adding this compound in a small amount, styrene-based expandable resin particles capable of producing a foamed molded article having an excellent appearance can be obtained. R1 is an alkyl group or a cycloalkyl group. When the number of carbon atoms is less than 6 or more than 20, the effect of improving fusion and obtaining sufficient strength may be difficult to obtain. . In addition, coconut oil fatty acid diethanolamide etc. can be mentioned as an example of this compound.

Other preferred amide compounds include, for example, oxyalkylated products of substituted or disubstituted amides or ammonia having at least one alkyl or cycloalkyl group having 1 to 20 carbon atoms. Can be Specific examples include monoalkanolamides such as lauric acid ethanolamide, tallow fatty acid ethanolamide, and oleic acid ethanolamide, and dialkanolamides such as lauric acid diethanolamide, tallow fatty acid diethanolamide, and oleic acid diethanolamide. Can be The use of these amide-based compounds is preferable because the surface appearance of the foam molded article is excellent.

Next, as in the present invention, the organic bromine compound has at least two bromine atoms in one molecule, and is at least 40% by weight based on the molecular weight of the organic bromine compound. It is preferable to contain the above bromine.

As a result, styrene-based foamable resin particles having self-extinguishing properties can be obtained. For example, it is possible to obtain styrene-based foamable resin particles that are optimal as a raw material of a foamed molded article usable for building materials and the like. it can. If the molecule contains only one bromine atom in one molecule, it may be difficult to develop self-extinguishing properties for the styrene-based expandable resin particles. The same applies to organic bromine compounds having a bromine content of less than 40% by weight.

As the organic bromine compound, for example, 1,
2,3,4-tetrabromobutane, 1,2,4-tribromobutane, tetrabromopentane, tetrabromobisphenol A, 2,2-bis (4-allyloxy-3,
5-dibromophenyl) propane, 2,2-bis (4-
Hydroxyethoxy-3,5-dibromophenyl) propane, 2,2-bis (4- (2,3-dibromo) propyloxy-3,5-dibromophenyl) propane, pentabromodiphenyl ether, hexabromodiphenyl ether, octabromodiphenyl ether, Decabromodiphenyl ether, tribromophenol, dibromoethylbenzene, 1,2,3,4,5,6-hexabromocyclohexane, 1,2,5,6,9,10-hexabromocyclododecane, octabromocyclohexadecane And bromine-substituted cycloalkanes such as 1,1-chloro-2,3,4,5,6-pentabromocyclohexane.

Further, dibromopropanol ester such as tris- (2,3-dibromopropyl) -phosphate or acetal, tribromophenol, tribromophenol allyl ether, tribromostyrene and the like can be mentioned.

Among them, hexabromocyclododecane,
2,2-bis (4-hydroxyethoxy-3,5-dibromophenyl) propane, 2,2-bis (4- (2,3
-Dibromo) propyloxy-3,5-dibromophenyl) propane and tribromophenol allyl ether are preferred because they can exhibit self-extinguishing properties with a small amount of addition.

[0051]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments The expandable styrene resin particles obtained by the production method according to the present invention will be described in detail with reference to Examples and Comparative Examples. The present invention is not limited to these examples.

The production method according to the present invention will be briefly described. The organic bromine compound is 0.4 to 6 parts by weight and the amide compound is 0.0001 to 100 parts by weight based on 100 parts by weight of the styrene monomer.
The styrene monomer is subjected to suspension polymerization using a poorly water-soluble inorganic salt as a suspending agent in the presence of 0.05 part by weight. During or after completion of the suspension polymerization, 1 to 20 parts by weight of a foaming agent is added.

Example 1 In a 50 liter autoclave equipped with a stirrer, 18 liters of ion-exchanged water, 63 g of tricalcium phosphate (manufactured by Taihei Chemical Industry Co., Ltd.) as a suspending agent composed of a poorly water-soluble inorganic salt, a surfactant 0.540 g of sodium dodecylbenzenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.).

Then, under stirring, benzoyl peroxide (manufactured by NOF CORPORATION, purity: 75%) was used as a polymerization initiator.
%), 54 g (40.5 g in terms of pure product), 27 g of t-butyl peroxybenzoate, 180 g of 1,2,5,6,9,10-hexabromocyclododecane as an organic bromine compound, and palm as an amide compound. A solution prepared by dissolving 0.36 g of oil fatty acid diethanolamide in 18 kg of a styrene monomer as a styrene monomer was charged.

After leaving at room temperature for 30 minutes under stirring,
The temperature was raised to 90 ° C. over one and a half hours. The temperature was raised to 100 ° C. over a period of 6 and a half hours, but 1.7 kg of butane as a blowing agent was injected into the autoclave 5 hours on the way. Thereafter, the temperature was further raised to 110 ° C. over one and a half hours, and maintained at 110 ° C. for two hours.
Cooled to ° C.

Dehydration was performed by a centrifugal separator, and acid washing was performed to remove tricalcium phosphate from the surface of the styrene-based expandable resin particles. After that, the water adhering to the upper surface is removed with a fluidized drying device,
Styrene-based expandable resin particles were obtained.

Subsequently, an expanded molded article is prepared from the styrene-based expandable resin particles. The obtained styrene-based expandable resin particles are pre-expanded (DYH-85 manufactured by Daisen Industries Co., Ltd.).
In 0), foaming was performed to a bulk density of 20 g / liter by a conventional method. After the thus obtained pre-expanded particles were left (aged) at room temperature for one day, they were filled in a 28 × 35 × 15 cm box-shaped mold and heated at 80 kPa steam blowing pressure for 20 seconds to be molded. Thus, a foam molded article was obtained.

(Example 2) Coconut oil fatty acid diethanolamide was used as an amide compound, and the input amount was 1.80 g.
The procedure was the same as in Example 1 except for the above. (Example 3) 0.36 g of coconut oil fatty acid diethanolamide was added as an amide compound, and when the polymerization conversion reached 5%, 5.4 g of a 1% aqueous solution of potassium persulfate as an alkali metal salt of persulfate was added. Was added. All other steps were the same as in Example 1 above.

Example 4 1.80 g of coconut oil fatty acid diethanolamide was added as an amide compound, and when the polymerization conversion reached 5%, a 1% aqueous solution of potassium persulfate as an alkali metal salt of persulfate was added. 0.4 g was added. All other steps were the same as in Example 1 above. (Example 5) 9.0 g of coconut oil fatty acid diethanolamide was added as an amide compound, and when the polymerization conversion reached 5%, 5.4 g of a 1% aqueous solution of potassium persulfate as an alkali metal salt of persulfate was added. Was added. All other steps were the same as in Example 1 above.

Example 6 1.8 g of coconut oil fatty acid diethanolamide was charged as an amide compound, and when the polymerization conversion reached 5%, 9 g of a 1% aqueous solution of potassium persulfate was used as an alkali metal salt of persulfate. Was added. All other steps were the same as in Example 1 above. Example 7 1.8 g of coconut oil fatty acid diethanolamide was added as an amide compound, and when the polymerization conversion reached 5%, 18 g of a 1% aqueous solution of potassium persulfate was added as an alkali metal salt of persulfate. . All other steps were the same as in Example 1 above. (Example 8) 1.8 g of coconut oil fatty acid diethanolamide was charged as an amide compound, and when the polymerization conversion reached 60%, 5.4 g of a 1% aqueous solution of potassium persulfate as an alkali metal salt of persulfate was added. Was added. All other steps were the same as in Example 1 above.

Comparative Example 1 Into a 50-liter autoclave equipped with a stirrer, 18 liters of ion-exchanged water and 15.4 g of sodium acetate as a suspending aid were charged. Then, under stirring, 54 g (40.5 g in terms of pure product) of benzoyl peroxide (manufactured by NOF CORPORATION, purity: 75%) as a polymerization initiator and t-butyl peroxybenzoate 27 were used.
g, 1,2,5,6,9,10-
A solution obtained by dissolving 180 g of hexabromocyclododecane and 0.360 g of N, N-bis (2-hydroxyethyl) dodecylamine as an amine compound in 18 kg of a styrene monomer was charged.

After leaving at room temperature for 30 minutes under stirring,
The temperature was raised to 90 ° C. over one and a half hours. The temperature was raised to 100 ° C. over a period of 6 and a half hours, and 10% of polyvinylpyrrolidone having a K value of 85 to 90 in the second hour.
At 650 g of the aqueous solution, 1.7 kg of butane was injected into the autoclave 5 hours later.

Thereafter, the temperature was further raised to 110 ° C. over one and a half hours, maintained at 110 ° C. for 2 hours, and then cooled to 30 ° C. over 4 hours. All subsequent processes are performed in the first embodiment.
The same was done.

Comparative Example 2 The same procedure as in Example 1 was performed except that the amount of coconut oil fatty acid diethanolamide added was 0. Comparative Example 3 The same procedure as in Example 1 was performed except that 0.009 g of coconut oil fatty acid diethanolamide was added as an amide compound. (Comparative Example 4) The same operation as in Example 1 was performed except that 1.08 g of coconut oil fatty acid diethanolamide was added as an amide compound.

COMPARATIVE EXAMPLE 5 The amount of coconut oil fatty acid diethanolamide was set to 0, and when the polymerization conversion reached 5%, 5.4 g of a 1% aqueous solution of potassium persulfate was added as an alkali metal salt of persulfate. In all other respects,
The same was done. (Comparative Example 6) 0.009 g of coconut oil fatty acid diethanolamide was added as an amide compound, and the polymerization conversion was 5%.
Was performed in the same manner as in Example 1 except that 5.4 g of a 1% aqueous solution of potassium persulfate was added as an alkali metal salt of persulfate. (Comparative Example 7) 1.08 g of coconut oil fatty acid diethanolamide was added as an amide compound, and when the polymerization conversion reached 5%, 5.4 g of a 1% aqueous solution of potassium persulfate as an alkali metal salt of persulfate was added. The procedure was the same as in Example 1 except for the addition.

The styrene-based expandable resin particles obtained as described above were evaluated for the 50% average particle diameter, the degree of dispersion of the particle diameter, and the internal water content by the following methods. In addition, the surface appearance and foam morphology of the foamed molded article were also evaluated by the following methods.

(Evaluation method) (a) 50% average particle diameter (b) Dispersion degree of particle diameter After the polymerization reaction, after cooling to room temperature, a small amount of slurry containing styrene foamable resin particles was collected under stirring. . Hydrochloric acid was added to dissolve the suspending agent particles, and d8 was measured using a laser diffraction type particle size distribution analyzer (manufactured by SYMPATEC, Germany).
5, d50 and d15 (representing the particle size values when the weight cumulative particle size value from the minimum particle size reaches 85%, 50%, and 15%, respectively) were calculated. From these values, the 50% average particle diameter and the degree of dispersion of the particle diameter were calculated using the following equations. 50% average particle size = d50 Particle size dispersion = (d85−d15) / d50 (c) Internal water content The internal water content of the styrene-based foamable resin particles from which water adhered to the upper surface has been removed by a fluidized drying apparatus is determined by the Karl Fischer method. Was measured.

(D) Surface Appearance The surface appearance of the foamed molded article was visually observed and evaluated according to the following criteria. ：: Good appearance without molten particles. ×: Molten particles are present on the surface and the appearance is extremely poor. Or a foamed molded product cannot be obtained. (E) Bubble morphology The foamed molded product was sliced, and the sliced pieces were visually observed. A sample in which uniform air bubbles were observed was evaluated as ○, and a sample in which air bubbles were non-uniform was evaluated as ×.

In each of the above Examples and Comparative Examples, the 50% average particle size, the degree of dispersion of the particle size, the internal moisture content, the surface appearance of the foamed molded product, and the foam shape of the foamed styrenic resin particles were as follows. Examples are shown in Table 1 and each comparative example is shown in Table 2.

From Table 1, it can be seen that according to the production method of the present invention, since a suspending agent composed of a poorly water-soluble inorganic salt is used in the presence of an amide compound, the average particle diameter and the degree of dispersion of the particle diameter are large. In addition, it is possible to obtain styrene-based expandable resin particles having an appropriate internal moisture content, and that the foamed molded article made from the resin particles is excellent in both appearance and uniformity of the internal cell morphology. Do you get it. Further, from Examples 3 to 8, the addition of potassium persulfate at an appropriate polymerization conversion rate narrows the particle size distribution of the obtained styrene-based expandable resin particles, and also improves the appearance and internal bubbles of the foamed molded article. It was found that styrene-based expandable resin particles having excellent morphology were obtained.

Table 2 shows the following. In Comparative Example 1, a poorly water-soluble inorganic salt was not used as a suspending agent, an amide compound was not used, and an amine compound was used instead. For this reason, the foam morphology of the foamed molded article was not uniform. Comparative Example 2 and Comparative Example 5
As the suspending agent, a poorly water-soluble inorganic salt similar to that of the present invention is used, but no amide compound is used.
The appearance of the melted particles was poor, and only foamed foams having non-uniform cell shapes were obtained.

In Comparative Examples 3 and 6, the amount of the amide compound was too small, and in Comparative Examples 4 and 7, on the contrary, the amount of the amide compound was too large. Only a foamed molded article having a bad shape was obtained.

As described above, according to the present example, a foamed molded article containing an organic bromine compound, having a narrow particle size distribution of the obtained styrene-based foamable resin particles, and having excellent appearance and internal cell morphology after foam molding. Can be provided for producing styrene-based expandable resin particles.

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[Table 1]

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[Table 2]

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As described above, according to the present invention, an organic bromine compound is contained, the particle size distribution of the obtained styrene-based expandable resin particles is narrow, and after foam molding, the appearance and the internal cell morphology are excellent. A method for producing styrene-based expandable resin particles from which a foamed molded article can be obtained.

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Claims (7)

[Claims] 1. A method according to claim 1, wherein 100 parts by weight of the styrene monomer is
0.4 to 6 parts by weight of an organic bromine compound, 0.
The styrene monomer is subjected to suspension polymerization using a poorly water-soluble inorganic salt as a suspending agent in the presence of 0001 to 0.05 parts by weight. A method for producing styrene-based expandable resin particles, comprising adding 1 to 20 parts by weight of a foaming agent to 100 parts by weight of a monomer. 2. The method according to claim 1, wherein the poorly water-soluble inorganic salt is added in an amount of 0.01 to 100 parts by weight of the styrene monomer.
A method for producing styrene-based expandable resin particles, which comprises adding 10.0 parts by weight to carry out suspension polymerization. 3. The method according to claim 1, wherein the water-insoluble inorganic salt is at least one selected from the group consisting of tricalcium phosphate, hydroxyapatite, magnesium phosphate, aluminum hydroxide, calcium sulfate, talc, kaolin, and bentonite. Styrene-based expandable resin particles, characterized in that they are finely divided water-insoluble inorganic salts. 4. The method according to claim 1, wherein:
The alkali metal salt of persulfuric acid or sulfurous acid is added in an amount of 0.00
A method for producing styrene-based expandable resin particles, which comprises adding 005 to 0.003 parts by weight and a polymerization conversion during suspension polymerization of 0 to 30%. 5. The method according to claim 1, wherein:
The method for producing styrene-based expandable resin particles, wherein the amide-based compound is an amide according to the following (1) or (2) represented by the general formula R1CONR2R3. (1) R2 and R3 are both hydrogen and R1 is 6 to
Amide compound (R1CONH2) which is an alkyl group or a cycloalkyl group having 20 carbon atoms. (2) R2 and R3 are not hydrogen at the same time;
An amide compound wherein 3 is hydrogen or an alkyl group, cycloalkyl group or oxyalkyl group having 1 to 15 carbon atoms, and R1 is an alkyl group or cycloalkyl group having 4 to 20 carbon atoms ( R1
CONR2H, R1CONR2R3). 6. The method according to claim 1, wherein:
The organic bromine compound has at least two bromine atoms in one molecule, and contains at least 40% by weight or more of bromine relative to the molecular weight of the organic bromine compound. A method for producing expandable resin particles. 7. The amide compound according to claim 5, wherein the amide compound is an amide represented by the general formula R1CONR2R3, and R1 is an alkyl or cycloalkyl group having 6 to 20 carbon atoms, and R2 and R3 are A method for producing styrene-based expandable resin particles, wherein both are oxyalkyl groups.