JPS58222121A - Production of expandable thermoplastic polymer particle - Google Patents

Abstract

PURPOSE:To obtain the titled particles having a shortened molding time, by polymerizing a mixture of a styrene monomer and a fatty acid bisamide, adding a blowing agent and a plasticizer to the produced polymer particles and, after heat-treatment, coating the particles with a surface etchant. CONSTITUTION:Styrene or a vinyl monomer mixture containing styrene is mixed with 0.01-0.5wt% fatty acid bisamide of the formula (wherein R and R' are each a 12-24C hydrocarbon, and n is 1-2), e.g., ethylenebisstearamide, and the resulting mixture is suspension-polymerized to form thermoplastic polymer particles. Then, these particles are impregnated with an easily volatile blowing agent (e.g., butane) and a plasticizer (e.g., n-hexane), and then heat-treated at a temperature of 60-100 deg.C. The produced expandable thermoplastic polymer particles are coated with a surface etchant (e.g., hardened tallow oil or hardened soybean oil) to obtain the purpose expandable thermoplastic polymer particles.

Description

[Detailed description of the invention]

The present invention relates to a method for producing expandable thermoplastic polymer particles. More specifically, the thermoplastic polymer particles containing fatty acid bisamide are all treated with a blowing agent and then heat treated at a temperature of 60°C to 100°C for 30 minutes to 4 hours to obtain a foamable thermoplastic. By applying a surface erosion agent to the polymer particles, the synergistic effect between the fatty acid bisamide and the surface erosion agent reduces the cooling time (water cooling, air cooling) during in-mold molding and reduces the amount of steam used during molding. The purpose is to reduce the amount of Expandable styrenic polymer particles in which styrenic polymer particles contain an easily volatile blowing agent 'ff: 1% by weight to % by weight, such as propane, butane, pentane, etc., are conventionally known. When the expandable styrenic polymer particles are heated above their softening point, a large number of small cells are generated therein to form pre-expanded particles. When the pre-expanded particles are filled into a closed mold and heated, the pre-expanded particles are fused to each other, and a foamed styrene thread molded article according to the mold is easily produced. In molding after pre-foaming, it is necessary to leave the molded product in the mold for a certain period of time after steam heating. When the molded object is removed from the mold, the molded object expands or becomes distorted, making it impossible to obtain the desired mold dimensions. It is necessary to provide a cooling process of water cooling and air cooling to keep the molded product inside the mold for the necessary time. Generally, this time is called the cooling time in the molding process. This cooling time is indispensable for molded product production, and many techniques have been reported in order to shorten this cooling time. There is. However, in these conventional methods, although the cooling time is shortened, the bending strength of the molded product decreases, and the moisture content of the molded product increases at tK during molding, so that the practical advantages are not so great. Additionally, Japanese Patent Application Laid-open No. 48-485811 filed by the present applicant
In the invention, fatty acid bisamide is added at the initial stage of polymerization to shorten the cooling time by 1 sMk. However, in the prior invention, the amount of fatty acid bisamide used is limited because as the amount of fatty acid bisamide added increases, the suspension state within the polymerization system becomes extremely unstable. Therefore, the cooling time is also limited. In addition, when a large amount of fatty acid bisamide is added to IC', the blowing agent becomes localized after production, and when these particles are foam-molded, cracks occur inside the particles, which significantly deteriorates the quality of the produced molded product. The inventors of the present invention have discovered that there are drawbacks. Also, as a simple method to shorten the cooling time from the perspective of the molding process, the longer the water cooling time is set, the shorter the cooling time will be and the molded product with the desired mold dimensions will be obtained, which will shorten the cooling time. is planned. However, on the other hand, there are drawbacks such as an increase in the moisture content of the molded body, an extremely low mold temperature, and an increase in the amount of steam used in the next molding cycle, so that there are no substantial advantages. In view of the above facts, the inventors of the present invention conducted extensive research and found that the above problems did not occur: the molding time was significantly shortened, and the mold temperature was even higher than the mold temperature at the time of ejecting the molded product, which was conventionally done with resin. However, it is possible to obtain a molded product according to ten mold methods in the same molding time as conventional products, which is useful for mold heating and fusion between pre-expanded particles (6
) We have found a method that can reduce the amount of steam required and have completed the present invention. That is, the present invention uses styrene or styrene at 50% in an aqueous medium.
In a method for producing thermoplastic polymer particles by suspension polymerization of a vinyl monomer mixture containing % by weight or more (hereinafter abbreviated as vinyl monomer), the general formula % formula for vinyl monomers is used. % to 24 hydrocarbon groups, R, R/ may be the same or different, n is 1 or 2. ) fatty acid bisamide represented by 0.01% by weight or more, 0.5 (1% by weight)
100 parts of thermoplastic polymer particles containing the following are absorbed at least 1% by weight of a readily volatile blowing agent and at least 0.1% of a plasticizer, and then heated to a temperature of 60°C or higher for 10
11. Expandable thermoplastic polymer particles are provided by performing a treatment at 0° C. or lower for 30 minutes or more and further applying a surface erosion agent to the obtained expandable thermoplastic polymer particles. In this case, known aqueous suspension polymerization is used for polymerization. Hereinafter, the treatment carried out at temperatures between 60°C and J-100°C will be referred to as the heat treatment temperature, and the time will be referred to as the heat treatment time. It is obtained by suspension polymerization of a monomer mixture, and the vinyl monomer mixture is
It is a mixture of styrene monomer or a monomer copolymerizable with styrene and styrene, and one containing 50% by weight or more of styrene is preferably used. Monomers capable of cocharging include methyl mectallate, α-
Examples include methylstyrene, n-phthyl acrylate, and azirylonitrile. As the blowing agent, lower aliphatic tetrahydrogen such as propane, butane, impuka kung, pentane, and other known blowing agents are used. It is desirable to use n-hexane, cyclohexane, and n-hebutane alone or in combination as plasticizers,
Further, there is no problem when toluene and ethylbenzene are used in combination as a solvent. Examples of fatty acid bisamides include methylene bis-carroamide, ethylene bis-stearoamide, hexamethylene bis-palmitic acid amide, and ethylene bis-oleic acid amide, and the amount used thereof is 0% relative to the vinyl monomer.
．． 01% by weight or more. The effect of reducing the cooling time is small in the case of 0.0 and 1% O by weight, and the effect of reducing the cooling time in the 0.5% by weight & O2 dumping basin is large, but the blowing agent localizes after production and the particles are foamed. When molded, cracks occur inside the particles, which significantly deteriorates the quality of the resulting molded product. Therefore, the amount used is 0.01% by weight or more, 0.5% by weight
The content is preferably 0.05% by weight or more and 0.35% by weight or less. The heat treatment is carried out at least when the foaming agent is contained in the polymer in an amount of 1% by weight or more. Heat treatment temperature is 6J℃ or higher, 10
It is below 0°C. At temperatures below 60°C or above 100°C, the effect of shortening the cooling time is small, and the heat treatment time must be 30 minutes or more. If the cooling time is less than 30 minutes, the effect of shortening the cooling time is small.The upper limit of the cooling time is 4 hours, so the effect will not change even if the cooling time is longer than 4 hours. The surface erosion agent is applied to the expandable thermoplastic polymer particles. The amount used is preferably from 1 to 0.5% by weight, more preferably from 0.05% to 0.35% by weight. If it is less than 0.01% by weight, the effect of shortening the cooling time is small, and if it is more than 0.50% by weight, the effect of shortening the molding time is large, but there will be disadvantages such as an increase in the moisture content of the molded product and a decrease in the mechanical strength of the molded product. As surface erosion agents, hydrogenated oils and fats and partial esters of fatty acids and polyhydric alcohols are effective, such as hydrogenated oil 11
Examples of φ include hydrogenated tallow oil, hydrogenated soybean oil, and hydrogenated palm oil. Partial esterification products of fatty acids and polyhydric alcohols include sorbicun monostearate, flobylene glycol monostearate, chrycerin monooleate, saturated fatty acid esters of fatty alcohols, sorbitanomonopalmitate, monoglyceride, etc. be. Although this surface erosion agent exhibits the effect of shortening the cooling time even if it is added alone to the expandable thermoplastic polymer particles, the present inventors added the surface erosion agent to yarn that has been subjected to addition of fatty acid bisamide and heat treatment. The present invention was completed after confirming that the effect can be significantly improved by adding it. The present invention will be explained below with reference to Examples. [All parts are parts by weight. ] Example 1 Styrene monomer 10081S1 Hensoil peroxide 0.
18 parts, l-1 bis(t-butylperoxy) 3.55
) 0.20 parts of 7-ene, 0.25 parts of bisstearamide, tertiary phosphoric acid/'7
/l' 0.20 parts of sodium dodecylbenzenesulfonate, 0.0025 parts of sodium dodecylbenzenesulfonate, 0.1 part of sodium chloride, and 1°θ of toluene were polymerized at 90°C in a pressure-resistant autoclave to obtain thermoplastic polymer particles. Ta. Then, 0.0% tribasic calcium phosphate. '05 Immediately after adding 21.3 parts of n-hexane and 9 parts of butane, 10
The temperature was raised to 0°C. After maintaining this temperature for lθ hours, it was cooled to 85° C. and heat treated for 4 hours. Then, it is supercooled to 40"C, dehydrated, and dried to form expandable thermoplastic polymer particles (hereinafter referred to as preliminary particles).
I got it. Next, 0.35% of hardened tallow oil was added as a surface erosion agent to 100 resin particles having a particle size of 1056 to 71M on the backside of the resin particles.
Resin particles [1] were obtained by coating the resin particles. Example 2 Resin particles 1] were obtained in the same manner as in Example 1, except that heat treatment was performed at 60° C. for 4 hours. Example 3 Example 1 except that glycerin monooleate 0.35% was applied instead of hydrogenated soybean oil 0.35% as a surface erosion agent.
Resin particles [3] were obtained in the same manner as above. Example 4 Resin particles [4] were prepared in the same manner as in Example 1 except that 0.8 cyclohexane was used instead of 0.8 cyclohexane.
I got it. Example 5 Resin particles [5] were prepared in the same manner as in Example 1, except that 0.8 n-hebutane was used instead of 0.8 n-hekinane.
I got it. Example . Ethylene bisstearamide o, 25 @ wo1),
Resin particles [
6] was obtained. Comparative Example Comparative Example 1 Example 1 except that heat treatment was performed slowly at 85"C for 4 hours.
Resin particles [7] were obtained in the same manner as above. Comparative Example 2 Example 1 except that 0.35% hydrogenated tallow oil was not applied.
Resin particles [8] were obtained in the same manner as above. Comparative Example 3 Example 1 except that 0.8% n-hexane was not added.
resin particles in a similar manner to

Example 1 of 6 or more obtained [9]
~6, The expandable thermoplastic polymer particles obtained in Comparative Examples 1 to 3 were pre-foamed to a size of 55 times, and after curing at room temperature for 24 hours,
A molding test was conducted using a Baarsf-180 molding machine (manufactured by Toyo Kikai Kinzoku Co., Ltd.). During molding, the mold temperature at the time of removing the molded product is 60°C and 8°C.
The temperature was set to 5°C. The molded products were molded at different cooling times for each temperature, and the molded products were cured for one day at 40'C, and the dimensions of the molded products were measured. The point at which the molded body dimensions reached the mold design values was considered to be the molding time of the resin. Also, the amount of steam used during molding was measured using a steam flow meter. The results are shown in Table-1.

Claims (1)

[Claims] 1. Styrene or a vinyl monomer mixture containing styrene in an aqueous medium (hereinafter abbreviated as vinyl monomer).
In the method for producing thermoplastic polymer particles by suspension polymerization of vinyl monomer, the general formula RC0NH (CH2
) nHNoCR' (here, R and R' have 12 to 12 carbon atoms
In the 24 hydrocarbon groups, R and R' may be the same or different and are nHl or 2. ) is impregnated into thermoplastic polymer particles containing from 0.01% to 0.50% by weight of a fatty acid bisamide represented by 0.01 to 0.50% by weight with the addition of an easily volatile blowing agent and a plasticizer, and then at a temperature of 60°C to 100°C. 1. A method for producing expandable thermoplastic polymer particles, which comprises performing heat treatment and further coating the entire surface of the expandable thermoplastic polymer particles obtained with a surface erosion agent. 2. The method for producing expandable thermoplastic polymer particles according to claim 1, which is a fatty tyrene bislaurylamide represented by the general formula R-(OONH)2(0H2)2R'. 3. The method for producing expandable thermoplastic polymer particles according to claim 1 or 2, wherein the easily volatile blowing agent is butane. 4. The expandable thermoplastic polymer particles according to claim 1, 2, or 3, wherein the nT plasticizer is a hydrocarbon that is liquid at room temperature, such as n-hexane, n-hebutane, or cyclohexane. Production method. 5. Claim 1, wherein the surface erosion agent is hydrogenated oil-fat or/and partial esters of fatty acid and polyhydric alcohol.
5. The method for producing expandable thermoplastic polymer particles according to claim 5, which is the following. 7 Claims in which the partial esters of fatty acids and polyhydric alcohols are sorbicun monostearate, propylene glycol monostearate, chrycerin monooleate, saturated fatty acid esters of fatty alcohols, or sorbitan monopalmitate monoglyceride Method for producing expandable thermoplastic, )!1 polymer particles according to item 6''. 8. The amount of surface erosion agent used is 0.01% by weight or more - 1: o
, Claims 1 and 2, which are 5% by weight or less,
The method for producing expandable thermoplastic polymer particles according to item 3, 4, 5, 6, or 7.