JPH10273550A - Foamable resin particle, its production, and molded foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide formable resin particles capable of giving a molded foam with a high heat resistance, a production process therefor, and a molded foam produced therefrom. SOLUTION: The objective foamable resin particles are produced by impregnating a volatile blowing agent into polymer particles which are produced by the suspension polymn. of a monomer mixture comprising 50-80 wt.% styrene, 5-45 wt.% tricyclo[5,2,1,0<2> ,<6> ]dec-8-yl methacrylate and/or tricyclo[5,2,1,0<2> ,<6> ]dec-8-yl acrylate, and 5-45 wt.% α-methylstyrene in the presence of a polyfunctional org. peroxide alone or together with a monofunctional org. peroxide as the polymn. initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to expandable resin particles from which a foamed article having high heat resistance can be obtained, a method for producing the same, and a foamed article.

[0002]

2. Description of the Related Art Conventionally, expandable styrene resin particles are often used as expandable plastics suitable for foam molding. However, foamed molded products made from expanded styrene resin particles have poor heat resistance, so heat resistance above the softening temperature of styrene resin, such as hot water insulation, metal roof insulation in buildings, bathroom insulation, and automobile roof insulation. It could not be used in application fields where high performance was required.

[0003] Many attempts have been made in the past to improve the heat resistance of foamed molded products, but many of them have been proposed to improve the heat resistance of the foamed molded article by improving the heat resistance of the resin itself. Therefore, the molding temperature and the heat-resistant temperature were close to each other, and it was difficult to impart high foaming properties. Further, each of the proposed heat resistant resins has an inherent problem due to the resin composition.

For example, Japanese Patent Application Laid-Open No. 47-39186 proposes a styrene-maleic anhydride copolymer, which requires a complicated suspension polymerization step and a resin component having poor adhesion to metal. Due to good properties, there was a problem in the releasability during molding.
Japanese Patent Publication No. 57-182334 proposes a copolymer of methyl methacrylate and α-methylstyrene. However, since the polymerizability of α-methylstyrene is inferior, a long-time polymerization process at a high temperature is required. JP-A-60-2068
Nos. 46, 206847 and 206848 propose copolymers containing α-methylstyrene and acrylonitrile as main components. However, copolymerization of acrylonitrile lowers the fluidity of the resin and consequently imparts high foaming properties. It was difficult. JP-A-60-115636 discloses styrene and tricyclo [5,2,1,0 ^2,6 ] methacrylate.
Although a copolymer of deca-8-yl has been proposed, a large amount of tricyclo [5,2,1,0 ^2,6 ] deca-8-yl methacrylate is required to impart sufficient heat resistance. For this reason, it has been difficult to say that the monomer is a more cost-effective method than being expensive.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a heat-resistant foamable resin particle which has high heat resistance when formed into a foamed product while maintaining high foamability, and which is excellent in economical efficiency. , A method for producing the same, and a foamed molded product using the same.

[0006] The heat resistance is determined by the monomer composition. In the present invention, the monomer component may be tricyclo [5,2,1,0 ^2,6 ] dec-8-yl methacrylate and / or tricyclo [5,2,1,0 ^2,6 ] decacrylate. Includes 8-yl, α-methylstyrene and styrene.

In the present invention, tricyclo [5,2,1,0 ^2,6 ] dec-8-yl methacrylate and / or tricyclo [5,2,1,0 ^2,6 ] dec-8-yl acrylate The production of heat-resistant foamable resin particles by improving heat resistance,
Although it has the characteristics of improved foam moldability and excellent polymerizability, it has the disadvantage of being expensive. Α-Methylstyrene is effective in improving heat resistance and is economically advantageous, but has disadvantages of difficulty in polymerization and adversely affecting foam moldability.

[0008] On the other hand, styrene is excellent in economy, polymerizability, and foam moldability, but has a disadvantage of poor heat resistance.
^0,6 ] dec-8-yl and / or tricyclo [5,2,1,0 ^2,6 ] dec-8-yl acrylate and α-methylstyrene in predetermined amounts, and a polyfunctional organic The present invention has been achieved by using a mixture of a peroxide or a polyfunctional organic peroxide and a monofunctional organic peroxide.

[0009]

The present invention has high heat resistance and excellent foam moldability without using a complicated polymerization step.
Moreover, it is intended to obtain heat-resistant foamable resin particles more economically. This feature is achieved by the constitution of the monomer and the organic peroxide used as the polymerization initiator.

The present invention relates to foamable resin particles obtained by impregnating a polymer particle obtained by suspension polymerization with a volatile foaming agent, wherein a monomer component used for producing the particles is:
50% by weight or more and 80% by weight or less of styrene, tricyclo [5,2,1,0 ^2,6 ] dec-8-yl methacrylate and / or tricyclo [5,2,1,0 ^2,6 ] acrylate
Dec-8-yl is contained in an amount of from 5% by weight to 45% by weight and α
Foamable resin particles in which methylstyrene is 5% by weight or more and 45% by weight or less and the polymerization initiator is a polyfunctional organic peroxide or a mixture of a polyfunctional organic peroxide and a monofunctional organic peroxide; The present invention relates to a production method thereof and a foam molded article using the particles.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The particles used in the present invention are prepared by adding styrene to tricyclo [5,2,1,0 ^2,6 ] dec-8-yl methacrylate and / or tricyclo [5, acrylate].
A tertiary or quaternary copolymer obtained by copolymerizing 2,1,0 ^2,6 ] dec-8-yl and α-methylstyrene, wherein a polyfunctional organic peroxide or a polyfunctional copolymer is used as a polymerization initiator. It is obtained using a mixture of an organic peroxide and a monofunctional organic peroxide, and is further impregnated with a volatile foaming agent to form foamable resin particles.

In the present invention, if the amount of styrene is less than 50% by weight, the polymerization takes a long time, and if it exceeds 80% by weight, sufficient heat resistance cannot be imparted. If tricyclo [5,2,1,0 ^2,6 ] dec-8-yl methacrylate and / or tricyclo [5,2,1,0 ^2,6 ] dec-8-yl acrylate is less than 5% by weight, It is difficult to provide sufficient heat resistance, and if it exceeds 45% by weight, it is not economical. In the present invention, if α-methylstyrene is less than 5% by weight, it is difficult to impart sufficient heat resistance, and if it exceeds 45% by weight, a long time is required for polymerization.

In the present invention, the polyfunctional organic peroxide is
An organic peroxide having two or more functional groups in its structural formula and having a 10-hour decomposition half-life temperature of 60 to 120 ° C. is preferable. Examples of this are bis (t-butylperoxy) trimethylcyclohexane, bis (t-butylperoxy) cyclohexane, bis (t-butylperoxy) butane, bis (t-hexylperoxy) trimethylcyclohexane, bis (t -Hexylperoxy) cyclohexane, bis (di-t-butylperoxycyclohexyl) propane and the like.

The monofunctional organic peroxide used in the present invention includes benzoyl peroxide, t-butylperoxy benzoate, t-butylperoxy isopropyl carbonate and the like.

In the present invention, the polymerization of these monomers using a polyfunctional organic peroxide or a polyfunctional organic peroxide and a monofunctional organic peroxide is carried out by suspension polymerization. A conventionally known method can be applied to suspension polymerization of these monomers, and, similarly to suspension polymerization of styrene monomers, a styrene monomer obtained by dissolving an organic peroxide in an aqueous medium containing a dispersant. Is dispersed, and radicals are generated by heating to carry out polymerization.

The dispersant used in the suspension polymerization may be a method in which a sparingly soluble inorganic salt such as tricalcium phosphate or magnesium phosphate is used in combination with a surfactant, polyvinyl alcohol,
Alkyl cellulose, hydroxyalkyl sulfulose,
In the present invention to which conventionally known ones such as an organic dispersant such as polyvinylpyrrolidone can be applied, the average particle diameter of the heat-resistant resin particles obtained by stable suspension polymerization is 0.05 to 2.0.
mm.

In suspension polymerization, various known additives can be used in combination. For example, as a chain transfer agent added for the purpose of adjusting the degree of polymerization, conventionally known ones such as octyl mercaptan, dodecyl mercaptan, and α-methylstyrene dimer can be used. As a plasticizer, dioctyl adipate, dioctyl phthalate,
Dibutyl sebacate, butyl stearate, epoxidized soybean oil, vegetable oil and the like can be used.

The volatile volatile foaming agent used in the present invention is appropriately selected from aliphatic hydrocarbons such as propane, butane, isobutane, pentane, isopentane and cyclopentane, but propane, butane or pentane is preferred. As a foaming aid, an alicyclic hydrocarbon such as cyclohexane or an aromatic hydrocarbon can be used in addition to the aliphatic hydrocarbon. The impregnation of the polymer particles with the readily volatile blowing agent can be performed during the polymerization or after the polymerization is completed. The amount of the foaming agent contained is 3 from the viewpoint of foamability and economy.
It is preferable that the content be not less than 10% by weight and not more than 10% by weight.

The heat-resistant foamable resin particles according to the present invention are preferably impregnated with a foaming agent, dehydrated and dried, and then coated with a surface coating agent. As the coating agent, those applied to expandable polystyrene can be applied as they are. For example, zinc stearate, triglyceride stearate, monoglyceride stearate, hardened castor oil, amide compounds, silicones, surfactants used as antistatic agents, and the like. The coating of the heat-resistant foaming resin particles with the surface coating agent can be performed by a Henschel mixer, a Loedige mixer or the like.

The foamed article having heat resistance according to the present invention is produced by a molding method using foamable styrene particles which is usually adopted.

[0021]

Next, the present invention will be described in more detail by way of examples, which should not be construed as limiting the present invention. Example 1 <Polymerization reaction> In a 16-liter autoclave attached to a stirrer, 6000 g of pure water, 9 g of tricalcium phosphate, 0.24 g of sodium dodecylbenzenesulfonate, 0.24 g of sodium sulfate.
2 g was charged and charged while stirring at 200 rpm.
Then, while stirring similarly, styrene 4200
g, tricyclo [5,2,1,0 ^2,6 ] tecca-8-yl methacrylate (manufactured by Hitachi Chemical Co., Ltd .: trade name FA-513M), 900 g, α-methylstyrene 900 g, 1,1-bis (t-butylperoxy) ) 3,3,5 trimethyl cyclohexane (Nippon Oil & Fats, Perhexa 3M) 30.0 g,
t-butyl peroxy isopropyl carbonate
3.0 g and 3.0 g of ethylenebisamide were mixed and dissolved. After completion of the charging, the temperature was raised to 93 ° C. 3 hours and 4 hours after the completion of the temperature rise, 3 g and 6 g of tricalcium phosphate, respectively.
Added. Subsequently, the temperature was kept at 93 ° C for 3 hours, and the polymerization rate was about 9
At the time when the reaction reached 0%, 6 g of tricalcium phosphate was added, and then the temperature was raised to 110 ° C., and the temperature was further kept for 4 hours to complete the polymerization reaction. <Impregnation of foaming agent> After completion of the polymerization, 120 g of pentane and 450 g of butane were used as the foaming agent while keeping the temperature at 110 ° C.
After pressurizing and keeping the temperature for 8 hours, the mixture was cooled to room temperature and taken out of the autoclave. <Post-treatment> The taken-out slurry was washed, dehydrated and dried, passed through 14 mesh and classified with 22 mesh remaining, further containing zinc stearate 0.08% by weight, castor hardened oil 0.05% by weight, and dimethyl silicone 0 0.02% by weight of the surface to obtain heat-resistant foamable resin particles. <Evaluation of Molding> The obtained heat-resistant foamable styrene-based resin particles were pre-foamed to a bulk density of 0.025 g / ml using steam as a heat medium, aged, and foamed to obtain a molded product. Table 1 shows the residual monomer content, foamability, and shrinkage resistance of the molded product.

Comparative Examples 1, 2, and 3 Except for the items shown in Table 1, suspension polymerization and impregnation with a blowing agent were carried out in the same manner as in Example 1. The test results are shown in Table 1. The measuring method of the evaluation in Table 1 is as follows. Residual monomer amount: Measured by gas chromatography. Foaming agent amount: At the time of the foam molding test, the heating loss value at 200 ° C. was defined as the foaming agent amount. Foaming degree: Expressed as a foaming multiple (ml / g) when the foamable resin particles were held in boiling water for 2 minutes. Dimensional shrinkage: foamed particles are foamed 40 times (ml / g) and cured at 60 ° C. for 1 day and room temperature for 6 days.
It was cut into × 100 × 25 (mm) to obtain a test piece. The test piece was placed in a 100 ° C. atmosphere for 168 hours, and the dimensional shrinkage was calculated as dimensional shrinkage (%) = ((dimension before heating−dimension after heating))
/ Dimension before heating) × 100.

[0023]

[Table 1] Note 1) FA-513M: tricyclo [5,2, methacrylate]
1,0 ^2,6 ] dec-8-yl 2) para-hexa 3M: 1,1 bis (t-butylperoxy) 3,3,5 trimethylcyclohexane (trifunctional organic peroxide) 3) BPO: benzoylper Oxide (monofunctional organic peroxide)

[0024]

According to the present invention, foamable resin particles from which a foamed product having high heat resistance can be obtained, an economical production method thereof, and a foamed molded product having high heat resistance are provided.

Claims (4)

[Claims] In a foamable resin particle obtained by impregnating a polymer particle obtained by suspension polymerization with a volatile foaming agent, a monomer component used in the production of the particle is styrene containing 50%. % To 80% by weight of tricyclo [5,2,1,0 ^2,6 ] dec-8-yl methacrylate and / or
Or tricyclo [5,2,1,0 ^2,6 ] dec-8-yl acrylate is 5 to 45% by weight and α-methylstyrene is 5 to 45% by weight, and polymerization is initiated. Expandable resin particles wherein the agent is a polyfunctional organic peroxide or a mixture of a polyfunctional organic peroxide and a monofunctional organic peroxide. 2. The expandable resin particles according to claim 1, wherein the readily volatile blowing agent is propane, butane or pentane. 3. The process for producing expandable resin particles according to claim 1, wherein an easily volatile foaming agent is impregnated during or after suspension polymerization. 4. An expanded molded article using the expandable resin particles according to claim 1.