JPS62109835A - Production of carbon-containing styrene-modified expandable olefinic resin particle - Google Patents

Abstract

PURPOSE:To produce the titled particles, by using a specific polymerization initiator and organic foaming agent in polymerizing a styrene based monomer in the presence of polyolefin based resin particles containing carbon particles and a bisamide compound in an aqueous suspension system. CONSTITUTION:(A) Particles obtained by mixing and granulating 100pts.wt. polyolefin based resin, preferably low-density polyethylene and 1-50pts.wt. carbon particles, preferably Ketjenblank in an extruder, (B) 20-300pts.wt., based on 100pts.wt. component (A), styrene based monomer and (C) a bisamide compound expressed by the formula (R<1> and R<2> are 1-22C alkyl; R<3> and R<4> are H or 1-22C alkyl; n is an integer 1-4), preferably stearic acid ethylenebisamide in an amount of 0.05-5wt% based on the total of the components (A) and (B) are suspended in an aqueous medium to polymerize the component (B) in the presence of (D) a polymerization initiator capable of producing tertiary alkoxy radicals. (E) An organic foaming agent having a lower boiling point than the softening temperature of a styrene based resin is impregnated to afford the aimed particles.

Description

[Detailed Description of the Invention] (a) Purpose of the Invention The present invention facilitates the production of styrene-modified expandable olefin resin particles with small cell diameters that uniformly contain carbon particles (including spherical bodies and columnar bodies). Regarding the method.

(Field of Application of the Invention) The carbon particle-containing styrene-modified expandable olefin resin particles obtained by the production method of the present invention are expandable resin particles that uniformly contain carbon, so they are used to pre-foam. The resulting foamed resin particles are placed in a mold, heated with steam to expand and fuse the particles to each other, and then cooled.The resulting foamed molded product has a good appearance and fusion rate, and is uniform throughout the inside. It is a foamed resin molded product that is colored black and has good antistatic and conductive properties.

This foamed resin molded product is useful as an electromagnetic shielding wall material and an antistatic container.

(Prior art) Foamed polystyrene, foamed polyethylene, foamed polypropylene,
A synthetic resin foam molded product such as styrene-modified foamed polyethylene (Elenball ■ manufactured by Mitsubishi Yuka Hearties Co., Ltd.) is used. However, these synthetic resin foam moldings have the disadvantage of being easily charged with static electricity, and are used as packaging materials and returnable boxes for electrical products such as magnetic disks, floppy disks, microcomputers, and printers, as well as electrical components such as ICs. (a) Use foamable resin particles with an antistatic agent attached to their surfaces.

(b) 1. Applying an antistatic agent to the surface of the foamed molded product.

(c) A conductive sheet is attached to the surface of the 8-foam molded product.

9) Carbon particle-containing expandable resin particles are used as the expandable resin particles.

methods etc. are used.

However, in methods (a) and naka), the antistatic function has a surface resistivity value of IX10'' to lXl0''Ω
In addition, the method (b) increases the price of the foam molded product due to the coating process.

The method ρ→ produces a molded body with good conductivity, but it can only be attached on a flat surface and is subject to restrictions on the shape of the molded body. Furthermore, like the method (b), the pasting work leads to an increase in the price of the product.

The method (b) has the advantage that a foam molded product of any shape can be obtained, and the product has excellent electrical conductivity.

Methods for uniformly incorporating carbon into styrene-based foamable resin particles include: (1) heating and mixing polystyrene with carbon and a blowing agent (expansion agent) in an extruder, followed by rapid cooling to pelletize; (2) mixing polystyrene and carbon in an extruder After heating and mixing in a container to form pellets, the pellets and foaming agent are placed in a sealed container and heated to impregnate the foaming agent. ■ Suspension polymerization of styrene monomer in which carbon is dispersed in an aqueous medium. , a method of adding a blowing agent during or after the polymerization process to impregnate it has been known. However, methods ① and ③ generate fewer small particles and large particles, and can easily obtain particles of a desired size that are relatively uniform, but because the particles are pellet-like, The disadvantages are that the filling properties during molding are poor and the surface appearance of the foamed molded product is poor. Method (2) yields truly spherical foamable resin particles, but it is unavoidable that unnecessary small particles and large particles are generated, which must be screened out, and contamination between product grades can be prevented. Therefore, it is necessary to prepare a large amount of equipment such as a mixing and dispersing tank for monomers and carbon, a drying line for resin particles, a sieve, etc. for each product, which has the disadvantage of increasing equipment costs. Furthermore, a serious drawback of method (2) is that the carbon dispersed in the monomer migrates to the aqueous phase of the polymerization medium during polymerization, resulting in carbon loss.
Moreover, not only is wastewater treatment troublesome, but also the suspension polymerization system becomes unstable, resulting in delayed or incomplete polymerization (increase in the amount of unreacted monomers).

As an improvement method of method (2), by using a so-called polymer graft carbon, which is a material in which monomers such as styrene, acrylic acid ester, methacrylic acid ester, acrylonitrile, etc. are graft-polymerized on the surface of carbon, instead of carbon, the polymerization can be delayed. A method for preventing incomplete polymerization has been proposed (JP-A-59-217715, JP-A-60-31536). However, the method using such polymer-grafted carbon is industrially extremely disadvantageous in that it requires a special polymer-grafted carbon.

JP-A No. 60-31536 states that in the polymerization reaction in the presence of such polymer-grafted carbon, if an initiator having a benzene ring such as benzoyl peroxide is used as a polymerization initiator, polymerization may be delayed or the polymerization may not be completed. Although it is stated that this occurs, there may be some errors in this point. That is, according to the research of the present inventor,
Polymerization delay and incomplete polymerization in this type of suspension polymerization are not due to the presence of a benzene ring in the polymerization initiator, but due to the use of an initiator that does not generate tertiary alkoxy radicals, especially one that generates carboxy radicals. It is thought that this will occur.

On the other hand, polystyrene foam molded products are superior to foamed polyethylene and foamed polypropylene in terms of price and moldability, but are inferior to the latter olefin resin foams in compressive strain recovery, and foam molded products that deform due to compressive loads cannot be used repeatedly.

On the other hand, olefin resin foams are highly elastic and have excellent compressive strain recovery properties, but have the disadvantage of poor moldability.

Therefore, in order to improve moldability, olefin resin particles are dispersed in water, styrene in which a polymerization initiator is dissolved is supplied to this dispersion, and then heated to polymerize the styrene to form a styrene-modified olefin resin. It is conceivable to manufacture particles and use styrene-modified expandable olefin resin particles in which the modified resin contains a volatile swelling agent such as butane, pentane, dichlorodifluoroethane, etc. during or after the polymerization (Tokuko Sho et al. No. 53-32972, No. 58
-57453).

However, when these modified particles contain carbon black particles, there is a drawback that the presence of carbon black inhibits the polymerization of styrene, as in the case of producing carbon particle-containing expandable styrenic resin particles.

As a method to improve the drawback of polymerization inhibition, we previously proposed the use of a polymerization initiator that generates tertiary alkoxy radicals (%Gan Sho 60-1557).
No. 79). However, in this method, it has been found that when a large amount of carbon is used, the cells in the foam become coarse, and the molded product obtained using this method has a damaged appearance or shrinks.

(Problems to be Solved by the Invention) The present invention does not use special carbon such as polymer graft carbon, and moreover, it contains carbon uniformly without causing polymerization delay or incomplete polymerization. The object of the present invention is to provide a method for producing a whole product of styrene-modified expandable olefin resin particles in which the cells of the foam are fine and uniform.

(b) Structure of the invention (means for solving the problem) In order to solve the problem of preventing inhibition of styrene polymerization due to the presence of carbon, a polymerization initiator that generates a tertiary alkoxy 7 radical is used, as in the previous application, and A specific bisamide compound having a nucleating effect is present during suspension polymerization.

This bisamide compound may be uniformly contained in the carbon-containing olefin resin particles and added to the suspension system, or it may be added to the suspension system without being coated with the carbon-containing olefin resin before suspension polymerization of the styrene monomer. It may also be added to aqueous suspension systems.

That is, the present invention involves suspension polymerizing a styrenic monomer containing styrene as a main component in an aqueous medium in the presence of olefin resin particles containing carbon particles using a polymerization initiator. During the reaction or after the polymerization reaction, an organic blowing agent having a boiling point lower than the softening temperature of the styrene resin is added to impregnate the produced styrene-modified olefin resin particles with the organic blowing agent to produce carbon-containing styrene-modified foamable material. In the method for producing olefin resin particles, a polymerization initiator that generates a tertiary alkoxy radical is used as a polymerization initiator, and suspension polymerization of a styrene monomer is carried out in the presence of a bisamide compound represented by the following formula. The present invention provides a method for producing carbon-containing styrene-modified expandable olefin resin particles characterized by the following.

[In the formula, ■<1 and R'' Fi is an alkyl group having 1 to 22 carbon atoms; R3 and R4 are hydrogen atoms or
is an alkyl group; n is an integer of 1 to 4. (Carbon-containing olefin resin) The carbon-containing olefin resin particles used in the present invention are particles obtained by heating and mixing carbon, olefin resin, and optionally a bisamide compound in an extruder to form pellets. Carbon particles are uniformly dispersed in olefin resin.

Examples of the carbon used in the production of the carbon-containing olefin resin used in the present invention include furnace black, channel black, summer black, acetylene black, graphite, and carbon fiber. In particular, Ketjenblack EC (trade name, Akzo Corporation), which is a type of furnace black, is preferable because it has good conductivity.

Examples of the olefin resin containing carbon include low density polyethylene, linear low density polyethylene, high density polyethylene, propylene in ethylene copolymer, ethylene propylene butene-1 copolymer, ethylene Φ butene copolymer, etc. Polymers, ethylene-based resins such as ethylene/acetate vinyl copolymer, ethylene/acrylic acid copolymer; propylene homopolymer, propylene/ethylene copolymer, propylene/butene-1 copolymer, propylene/ethylene medium Butene-1 copolymer, propylene @
The main component is propylene resin such as 4-methylpentene-1 copolymer, or a mixture of two or more of these, or these olefin resins, and polystyrene, polyamide, polyvinyl chloride, polyethylene terephthalate, etc.? Mixtures containing these substances can be used.

The content ratio of carbon in the carbon-containing olefin resin used in the present invention varies depending on the required thermochromicity and conductivity of the foamed molded product, and usually carbon is 1 to 50% by weight of the olefin resin. , preferably from a range of 2 to 30% by weight. Further, the size of the carbon-containing olefin resin particles used in the present invention is not particularly limited, but it is usually preferably about 0.1 to 5 η/piece.

(Styrenic Monomer) The styrene monomer used in the suspension polymerization of the present invention has styrene as its main component, and may be styrene alone or styrene and other vinyl thread monomers in a proportion of less than 501 t%. 1. α-methylstyrene, p-
There is no problem even if it is a monomer mixture containing methylstyrene, acrylonitrile, acrylic ester, methacrylic ester, butadiene divinylbenzene, etc.

The amount of styrene monomer is 100% of carbon-containing olefin resin particles! It is usually desirable to use the proportion of 20 to 300 parts by weight. If the amount of the styrene monomer used is less than 20 parts by weight, the foamability and moldability of the resulting styrene-modified expandable olefin resin particles will be difficult to satisfy.

In addition, the amount of styrene monomer used is such that the carbon content of the produced styrene-modified expandable olefin resin particles is o,
It is desirable that the amount is from i to 30% by weight, preferably from 1 to 15% by weight. If the carbon content in the styrene-modified expandable olefin resin particles is too low, the blackness of the foamed molded product and the imparting of conductivity and antistatic properties will be insufficient; if it is too high, the foamed molded product will target strength decreases.

(Bisamide compound) As the bisamide compound represented by the above formula, for example,
Ethylene bisamide stearate, methylene bisamide stearate, ethylene bisamide oleate, etc. are used. Among these, stearic acid ethylene bisamide is preferred from the viewpoint of cost.

Inorganic fillers such as Merck and silica, and metal soaps such as zinc stearate and aluminum stearate are known as nucleating agents for foamed resins, and although they have a certain degree of fine cell effect, their use is limited to olefins. It can only be used by melt-kneading an olefin resin and these nucleating agents (1% by weight or less of the olefin resin) using an extruder, and then granulating or directly extruding and foaming the mixture. This is because when these nucleating agents are added to a styrene suspension polymerization system, the nucleating agent effect is lost.

On the other hand, a bisamide compound is dissolved in a styrene monomer, impregnated into carbon-containing olefin resin particles, and then subjected to suspension polymerization to be incorporated into carbon-containing styrene-modified olefin resin particles to act as a nucleating agent. Therefore, it is possible to produce grades of carbon-containing styrene-modified olefin particles of each cell size using the same granulated carbon-containing olefin resin particles, by extruding the olefin resin, carbon, and nucleating agent in advance. The mixture is melt-kneaded in a machine, granulated to form carbon-containing olefin resin particles, and then the granulated particles and styrene monomer are suspended in water to polymerize styrene to produce carbon-containing styrene-modified olefin particles. This method is very favorable in terms of operation.

In addition, with conventional nucleating agents of inorganic fillers such as silica and Merck, and aliphatic metal salts such as aluminum stearate and zinc stearate, even if the amount added is 1 weight factor or more, if a large amount of carbon is present, the Even if the cells in the foam are fine, bisamide compounds contain a lot of carbon.
It has the effect of making the cells in the foam fine and uniform. Since bubbles (cells) become finer as the amount added increases, it is preferable to use up to about 5% by weight of the olefin resin.

Of course, the bisamide compound does not lose its nucleating effect even when carbon, bisamide compound, and olefin resin particles are granulated into pellets using an extruder, and the pellets are dispersed in water using a dryer to suspension polymerize styrene. The resulting carbon-containing expandable styrene-modified olefin resin has fine cells.

This bisamide compound may be used in combination with other nucleating agents such as silica, Merck, and metal soaps.

The amount of this bisamide compound is 0.01 to 5 parts by weight per 100 parts by weight of the onfin resin particles and the tostyrene monomer.
Parts by weight. If it is less than 0.01 part by weight, the resulting foam will have too large cells, while if it is added in excess beyond the Si placement area, the effect will not increase much.

(Polymerization initiator) The polymerization initiator used in the suspension polymerization of the present invention is an initiator that generates a tertiary alkoxy radical (-)Co.), preferably an initiator that generates a tertiary alkoxy radical (-)Co. This is an initiator whose main component is an initiator that does not produce RCOO.

This is because an initiator that generates tertiary alkoxy radicals does not cause polymerization retardation or polymerization incompleteness, whereas use of an initiator that generates only carboxy radicals causes polymerization retardation or polymerization incompleteness.

Examples of initiators for generating tertiary alkoxy radicals used in the present invention include t-butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyhexahydroterephthalate, n-Butyl-4,4-bis(t-butylperoxy)valerate, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, dicumyl peroxide, di-t-butyl peroxybutane,
Examples include t-butylperoxyisopropyl carbonate.

Among these initiators, dicumyl peroxide, n
-Butyl-4,4-bis(t-butylperoxy)valerate, l,1-bis(t-7'' tylperoxy) -
3,3,5-trimethylcyclohexane is particularly preferred since it does not generate carboxy radicals.

Examples of polymerization initiators include benzoyl peroxide,
There are initiators that mainly generate carboxy radicals, such as lauroyl peroxide, but as mentioned above, initiators that mainly generate carboxy radicals delay the polymerization reaction and increase the amount of unreacted monomer. , is not preferred as an initiator for use in the present invention. However, initiators that mainly generate carboxy radicals and azo initiators such as azobisisobutyronitrile can be used in relatively small amounts as initiators that generate the tertiary alkoxy radicals used in the present invention. It can be used in combination with other agents.

In the practice of the present invention, the olefinic resin has a melting point of 10
In the case of ethylene-based resins such as low-density polyethylene, ethylene-vinyl acetate copolymers, and ethylene-acrylic acid copolymers with a temperature of 0 to 123°C, the decomposition temperature is 50°C to obtain a half-life of 10 hours as a polymerization initiator. A polymerization initiator mainly used for styrene polymerization at ~105°C, and a polymerization initiator mainly used for crosslinking ethylene resins whose decomposition temperature is 105°C to 140°C to obtain a half-life of 10 hours, such as dicumyl peroxide, di-1-butyl peroxide,
When t-butyl cumyl peroxide or the like is used in combination, the resulting styrene-modified expandable ethylene resin particles are crosslinked, so the steam foam moldability is further improved.

The number of polymerization initiators used in the present invention is 1 to 4 parts by weight, preferably 0.5 to 3 parts by weight, per 100 parts by weight of the styrene monomer. When a polymerization initiator that mainly generates carboxy radicals is used, the amount used is desirably 1% by weight or less based on the styrene monomer. If the amount of polymerization initiator used is too small, the polymerization will not be completed and the amount of unreacted monomer will increase, while if it is too large, resin particles will be obtained that will give a brittle foam.

The polymerization temperature in the present invention is determined in consideration of the decomposition temperature of the polymerization initiator used, the degree of polymerization of the polymer to be produced, the absorption rate of the monomer, etc., and is usually appropriately selected from the range of 50 to 150°C.

In the present invention, the polymerization initiator may be added to the polymerization system before adding the styrene monomer, or may be dissolved in the monomer and added together with the chemical compound.

A solvent such as toluene, xylene, cyclohexane, or a small amount of a polymerization inhibitor or chain transfer agent may be added to the styrene monomer.

(!@turbidity polymerization) The polymerization reaction of the present invention is carried out in an aqueous medium.

Into the aqueous medium, water-soluble polymers such as polyvinyl alcohol and polyvinylpyrrolidone, and poorly water-soluble inorganic dispersants such as tribasic calcium phosphate, magnesium birophosphate, and calcium carbonate may be added as dispersion stabilizers. can. When adding the inorganic dispersant 'f, it is desirable to use a surfactant such as sodium dodecylbenzenesulfonate together. The amount of dispersant i used is preferably 0.1% by weight or more based on water. However, although it is not inconvenient to use a large amount of 4% by weight or more, it is rather disadvantageous from an economical point of view because it is difficult to expect an improvement in the effect commensurate with the use of a large amount.

In the present invention, during or after the polymerization reaction step of the suspension polymerization, the organic blowing agent is completely added according to a conventional technique, and the organic blowing agent is impregnated into the produced carbon-containing styrene-modified expandable olefin resin particles. let As the organic blowing agent, those having a softening point lower than the softening point of styrene resin, which is a polymer of styrene monomers, such as hexane, pentane, butane, fluoropane, trichloromonofluoromethane, dichlorodifluoromethane, etc. are used. be done.

In the present invention, when adding the organic blowing agent during the polymerization process, it is preferable to add it after 70% by weight of the monomer has been polymerized, and when the polymerization has completed at least 99%, Subsequently, impregnation with a blowing agent may be carried out.Furthermore, an aqueous medium is newly added to the carbon-containing styrene-modified expandable olefin resin particles obtained after the polymerization reaction is completed, and the blowing agent is added thereto. C that may be added to perform the impregnation treatment with a blowing agent (Examples, etc.) The following will further explain in detail with reference to Examples and Comparative Examples.

Example 1 Pure water at 900 V and 271 g of tribasic calcium phosphate and 0.0272 g of sodium dodecylbenzenesulfonate as dispersants were added to an autoclave with content fi3J to prepare an aqueous medium.

Next, Ketjenblack EC (manufactured by Akzo, Netherlands) as carbon particles and low-density polyethylene "Yukalon HE-60" (manufactured by Mitsubishi Yuka, trade name) with a melting point of 105°C were kneaded in an extruder in the proportions shown in Table 1. carbon-containing polyethylene particles 24, which are extruded into strands and granulated.
A polymerization initiator prepared by dissolving 01, 3.0 y of terjabutyl baroxy 2-ethylhexanoate, 2.49 y of terjabutyl baroxy 2-ethylhexanoate, and 1.82 y of dicumyl peroxide in styrene 3602. The solution, Kinren 122, and ethylene bisamide stearate shown in Table 1 were suspended in the aqueous medium, heated to 74°C in 1 hour, maintained at the same temperature for 3 hours, and then
After the temperature was raised to 0°C and maintained for 8 hours to polymerize styrene, the temperature was raised to 125°C over 2 hours and maintained at the same temperature for 2 hours to complete cross-linking of the resin particles.

Then, after cooling to 70°C, 75v of butane was added to the aqueous medium and held for 3 hours to impregnate the butane into the resin particles.

After cooling the suspension to room temperature, the contents were separated from water and taken out, and after dissolving and removing the tricalcium phosphate with nitric acid,
The particles were washed with water to produce styrene-modified expandable polyethylene particles containing carbon particles.

The expandable resin particles were heated to 97 to 100° C. using steam in a 301 batch pre-expander to obtain pre-expanded particles of 2 sy/l.

After aging these pre-expanded particles for one day,
The steam pressure was 0.8 +/CI+!
- The pre-expanded particles were heated for 20 seconds with G steam to expand and fuse with each other, and then cooled to obtain a molded foamed product. As shown in Table 1, this molded product has moldability, appearance, fusion bonding,
The conductivity was good.

Examples 2 to 3 Using n-butyl-4,4-bis(t-butylperoxy)valerate 2.4F instead of tert-butyl peroxy/benzoate 2.4V, and Touchen Black EC A foam molded article was obtained in the same manner as in Example 1 except that the amount of ethylene bisamide stearate was changed as shown in Table 1. The obtained molded product was in good condition as shown in Table 1.

Example 4 A molded foam molded product was obtained in the same manner as in Example 1 except that t-butyl peroxyisoglobyl carbonate 2.4 F was used instead of tert-butyl peroxybenzoate 2.42. . The molded product was in good condition as shown in Table 1.

Example 5 A foam molded article was obtained in the same manner as in Example 2 except that the amount of styrene was changed from 360f to 2402. The obtained molded product was in good condition as shown in Table 1.

Comparative Example 1 A foam molded article was obtained in the same manner as in Example 1 except that ethylene bisamide stearate was not added. As shown in Table 1, this product was a foam molded product with rough cells and poor appearance.

Comparative Example 2 Except for adding ethylene bisamide stearate,
A molded foam molded product was obtained in the same manner as in Example 2. As shown in Table 1, this molded product had rough cells and poor appearance.

Example 6 In an autoclave with an internal volume of 31, pure water 9002 and tricalcium phosphate 187 as a dispersant and dodecylbenzenesulfonate 0.027? was added to form an aqueous medium, and then Ketjenblack (
Carbon-containing ethylene-propylene random copolymer "Mitsubishi Noblen FX4" (trade name manufactured by Mitsubishi Yuka) was kneaded in an extruder at the ratio shown in Table 1 and granulated. 300 tons of copolymer resin particles, n-butyl 4,4-bis(t-butylperoxy)valeryl dissolved in styrene 3002, and 1.21 t of ethylene bisamide stearate were suspended in the aqueous medium. , this suspension was heated to 9 in 1 hour.
The temperature was raised to 0°C, then maintained at the same temperature for 3 hours, and further heated for 1 hour.
The temperature was raised to 105°C in 1 hour, maintained at the same temperature for 1 hour, further raised to 125°C in 1.5 hours and maintained at the same temperature for 4 hours, then butane 1207 was injected and maintained for another 1 hour. Afterwards, the valve at the bottom of the autoclave is opened and the slurry is released into a wire mesh container at room temperature and pressure.
Pre-expanded particles of 2y/l were obtained.

After pickling and washing the pre-expanded particles with water, drying and leaving for one day, they were filled into a mold with a mold cavity measuring 400 m+ in length, 400 m in width, and 50 m in thickness, and having vapor permeation holes. The pre-expanded particles were heated with steam at a pressure of 3 kq/c-.G for 20 seconds to fuse them together, and then cooled to obtain a molded foam molded article f: with the physical properties shown in Table 1.

Comparative Example 3 Styrene-modified propylene copolymer particles were obtained in the same manner as in Example 4 except that ethylene bisamide stearate' + 1 il- was not added, and this was foam-molded, but a molded product with coarse cells and poor appearance was obtained. I could only get it.

(Left below) Example 7 In an autoclave with an internal volume of 31, 900 ml of pure water was placed. An aqueous medium was prepared by adding tertiary phosphate 275' and sodium decylbenzenesulfonate 0.0272 as a dispersant.

Next, as carbon particles, Ketjenblack (manufactured by Akzo, Netherlands), stearic acid ethylene bisamide, and low-density i't "J" Yucalon 1 (E
-60'' (manufactured by Mitsubishi Yuka, trade name) in an extruder in the proportions shown in Table 1, extruded into strands, and granulated to form carbon-containing polyethylene particles 2402 and ter/yabutyl-oxy-2- Ethylhexanoate 3.0
? , tert-butylperoxybenzony) 2.4
A polymerization initiator solution in which r and dicumyl peroxide 1.8f are dissolved in styrene 3602 and xylene 12y
was suspended in the aqueous medium, heated to 74°C in 1 hour, maintained at the same temperature for 3 hours, heated to 80°C and maintained for 8 hours to polymerize styrene, and then heated to 125°C for 2 hours. The temperature was raised over a period of time and maintained at the same temperature for 2 hours to crosslink the resin particles.

Then, after cooling to 70° C., butane 752 was added to the aqueous medium and held for 3 hours to impregnate the butane into the resin particles.

After cooling the suspension to room temperature, the contents were separated from water and taken out, and after dissolving and removing the tribasic calcium phosphate with nitric acid,
The particles were washed with water to produce styrene-modified expandable polyethylene particles containing carbon particles.

The expandable resin particles were heated to 97 to 100°C with steam in a 301 batch pre-expander to obtain pre-expanded particles of 259/l.

After aging these pre-expanded particles for one day,
0 m, a mold cavity with a wall thickness of 50!01 and a vapor permeation hole is filled, and the steam pressure is o, skg/-.
- The pre-expanded particles were heated for 20 seconds with G steam to expand and fuse with each other, and then cooled to obtain a molded foamed product. As shown in Table 2, this molded product has moldability, appearance, fusion bonding,
The conductivity was good.

Examples 8-9 Using n-butyl-4,4-bis(t-butylperoxy)valeret) 2.49 instead of tert-butyl peroxydipenzoate 2.42 and Ketjenblack EC and stearic acid ethylene bisamide it
A foam molded article was obtained in the same manner as in Example 7 except that the procedure was changed to the one shown in Table 1. The obtained molded product had good penetration as shown in Table 2.

Example 10 A molded foam molded product was obtained in the same manner as in Example 7 except that t-butylperoxyisobrobyl carbonate 2.41 was used instead of tert-butylperoxybenzoate 2.42. . The molded product was in good condition as shown in Table 2.

Example 11 A foam molded article was obtained in the same manner as in Example 8 except that the amount of styrene monomer was changed from 360y to 2402y. The obtained molded product was good as shown in Table 2.Example 12 In an autoclave with an internal volume of 31, pure water 9002 and 1B of tribasic calcium phosphate were added as a dispersant. and 0.0272 of sodium dodecylbenzenesulfonate to make an aqueous medium, then Ketjen black (
Carbon is made by kneading ethylene bisamide stearate (manufactured by Akzo of the Netherlands), ethylene Φ propylene random copolymer "Mitsubishi Noblen FX4" (trade name manufactured by Mitsubishi Yuka) in an extruder at the ratio shown in Table 2, and granulating it. Contains ethylene/
Propylene random copolymer resin particles 3002 and n-
Butyl 4,4-bis(t-butylperoxy)valerate 2ri styrene 300yVc soluble MI.

was suspended in the aqueous medium, and this suspension was
The temperature was raised to 90"C"i in 1 hour, then maintained at the same temperature for 3 hours, further raised to 105℃ in 1 hour, maintained at the same temperature for 1 hour, and further increased to 125℃ in 1.5 hours. After raising the temperature and maintaining it at the same temperature for 4 hours, butane 1202 was injected, and after maintaining it for another 1 hour, the pulp at the bottom of the autoclave was opened and the slurry in the wire mesh container at room temperature and pressure was discharged. Pre-expanded particles of J were obtained.

The pre-expanded particles were pickled, washed with water, dried and left for one day, and then filled into a mold having a mold cavity measuring 400 wm long, 400 m wide and 50 cm thick, and having vapor permeation holes. The pre-expanded particles were heated with steam at a steam pressure of 3 kg/d-Q for 20 seconds to fuse them together, and then cooled to obtain a molded foam molded article having the physical properties shown in Table 2.

(Margin below) (C) Effect of the invention The present invention has the following effects.

(1) Highly expandable styrene-modified olefin resin particles uniformly containing carbon can be easily obtained, and the resin particles have fine bubbles and have excellent moldability during foam molding. The foamed molded product produced is uniformly colored black throughout, has excellent conductivity and antistatic properties, and has a good surface appearance.

Claims (12)

[Claims] (1) A styrenic monomer containing styrene as a main component is subjected to suspension polymerization using a polymerization initiator in the presence of olefin resin particles containing carbon particles in an aqueous medium, and the polymerization reaction is carried out using a polymerization initiator. During or after the polymerization reaction, an organic blowing agent having a boiling point lower than the softening temperature of the styrene resin is added to impregnate the produced styrene-modified olefin resin particles with the organic blowing agent to produce a carbon-containing styrene-modified foamable olefin resin. In the method of manufacturing resin particles,
Carbon-containing styrene-modified foaming characterized by using a polymerization initiator that generates tertiary alkoxy radicals as a polymerization initiator, and carrying out suspension polymerization of a styrenic monomer in the presence of a bisamide compound represented by the following formula: A method for producing polyolefin resin particles. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R^1 and R^2 are alkyl groups having 1 to 22 carbon atoms; R^3 and R^4 are hydrogen atoms or carbon atoms 1 to 2
2 alkyl group; n is an integer of 1 to 4; ] (2) The production method according to claim 1, wherein an initiator that generates tertiary alkoxy radicals but does not generate carboxy radicals is used as the polymerization initiator. (3) The polymerization initiator is dicumyl peroxide, n-
Butyl-4,4-bis(t-butylperoxy)valerate, 1,1-bis(t-butylperoxy)-3,3
, 5-trimethylcyclohexane, and t-butylperoxyisopropyl carbonate.
The manufacturing method according to claim 1, which is a seed. (4) The carbon-containing olefin resin particles are particles obtained by mixing the olefin resin and carbon in an extruder and granulating the mixture, claim 1, 2, or 3. Manufacturing method described. (5) A polymerization initiator in which the olefin resin particles are low density polyethylene and the decomposition temperature for the polymerization initiator to obtain its half-life in 10 hours is 50 to 105°C;
Decomposition temperature to obtain half-life in hours is 105-140
The manufacturing method according to claim 1, characterized in that it is a mixture with a polymerization initiator having a temperature of .degree. (6) The manufacturing method according to claim 1, wherein the carbon particles are contained in a proportion of 1 to 50 parts by weight per 100 parts by weight of the olefin resin. (7), carbon particle-containing olefin resin particles 100
2. The method according to claim 1, wherein the styrene monomer is used in an amount of 20 to 300 parts by weight. (8) The manufacturing method according to claim 1, characterized in that the carbon particles are Ketchen black. (9) The manufacturing method according to claim 1, wherein the bisamide compound is ethylene bisamide stearate. (10) The manufacturing method according to claim 1, wherein the bisamide compound is used in an amount of 0.05 to 5% by weight of the sum of the olefin resin and the styrene monomer. (11) The manufacturing method according to claim 1, wherein the bisamide compound is present in a uniformly dispersed manner in the olefin resin particles. (12) The production method according to claim 1, wherein the suspension polymerization is carried out by suspending the carbon-containing olefin resin particles, the styrene monomer, and the bisamide compound in water.