JPS58222122A - Production of expandable styrene polymer particle - Google Patents

Abstract

PURPOSE:To shorten a cooling time in effecting in-mold molding and thereby to reduce steam consumption, by coating the surfaces of pre-expanded particles with a surface etchant in effecting foaming and in-mold molding of expandable styrene polymer particles impregnated with a fatty acid bisamide. CONSTITUTION:Styrene or a vinyl monomer containing styrene is mixed with 0.01-0.5wt% fatty acid bisamide of the formula (wherein R and R' are each an 8-32C hydrocarbon), e.g., ethylenebisstearamide, and the resulting mixture is suspension-polymerized to obtain styrene polymer particles with a relative viscosity, at 30 deg.C of 0.95-2. Then, these particles are impregnated with a blowing agent (e.g., propane) and a blowing aid (e.g., n-hexane) and heat-treated at a temperature of 60-100 deg.C in the stage in which at least 1wt% blowing agent and at least 0.1wt% blowing aid have been absorbed. Then, the produced expandable polymer particles are coated with a surface etchant (e.g., hardened soybean oil) to obtain the titled polymer particles.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing expandable styrenic polymer particles, and more specifically, the present invention relates to a method for producing expandable styrenic polymer particles, and more specifically, particles containing fatty acid bisamide and having a specific viscosity (external) of 0.95 to 2°O at 30°C. To shorten the cooling time during in-mold molding, reduce the amount of steam used, and prevent a decrease in the mechanical strength of the obtained molded product when foaming and in-mold molding certain expandable styrenic polymer particles. This is the purpose.

Conventionally, styrenic polymer particles containing 1% to 1% by weight of a blowing agent such as propane, butane, or pentane are known as expandable styrenic polymer particles.

When these expandable styrene yarn polymer particles are heated above their softening point, they become pre-expanded particles in which a large number of small cells are formed. When the pre-expanded particles are filled into a mold and heated with steam, the pre-expanded particles are fused to each other, and a foam molded article according to the mold can be easily produced. For molding after pre-foaming, a molding machine is used after steam heating is completed. It is necessary to leave the molded body in the mold for a certain period of time.

If the molded object is removed from the molding machine or mold too quickly, the molded object will expand or become distorted, making it impossible to obtain the desired dimensions.
In order to obtain a molded product having the desired dimensions, it is necessary to perform water cooling and cooling steps for the necessary time and leave the molded product inside the mold. Generally, this time is called cooling time.

Shortening the cooling time is very important in improving the productivity of molded bodies. Many technologies related to shortening cooling time have been reported in the past.

For example, in the invention of JP-A No. 48-48588 filed by the present applicant, a fatty acid bisamide was added at the initial stage of polymerization to shorten the cooling time. However, in the above-mentioned prior invention, as the amount of fatty acid bisamide added increases, the suspension stability is extremely reduced, so the amount of fatty acid bisamide used is limited.

Therefore, the problem of the cooling time being limited and being small arose.As a result of further investigation, the inventors of the present invention determined that the specific viscosity of the styrenic polymer particles could be adjusted to shrink the particles. The present inventors have discovered that it is possible to obtain a foamed molded article with good performance without reducing mechanical strength, and have completed the present invention.

That is, the present invention provides a method for producing expandable styrenic polymer particles by suspension polymerizing styrene or a vinyl monomer mixture containing styrene (hereinafter referred to as vinyl monomer) in an aqueous medium. General formula RC for the system monomer! 0IHCH20H2NHOOR' (R here,
R/ is a hydrocarbon stem having 8 to 32 carbon atoms, and R and R' may be the same or different. At the stage where 100% by weight of styrenic polymer particles having γ4 of 0.95 to 2°0 at 30°C are impregnated with at least 1% by weight or more of a blowing agent and at least 0o10% by weight or more of a foaming aid, the heat treatment temperature is increased to 60°C. The present invention provides a method for producing expandable styrenic polymer particles, which comprises adjusting the particles to ~lO'0''C, heat-treating them for 30 minutes or more, and applying a surface erosion agent to the resulting expandable styrenic polymer particles. be.

In this case, known aqueous suspension polymerization is employed. The vinyl yarn monomer mixture in the present invention is a styrene monomer or a mixture of iJi ff1, which can be copolymerized with styrene, and styrene, preferably styrene. It contains 50% by weight or more of.

Examples of monomers copolymerizable with styrene include α-methylstyrene, acrylonitrile, methyl meccrylate, n-butyl acrylate, tort-butylstyrene, etc.Blowing agents include propane, butane, isobutane, pentane, etc. Alternatively, lower aliphatic hydrocarbons or other known blowing agents may be used.

Foaming aids include n-hexene, n-hbutane, cyclohexane, toluene, ethylbenzene, etc.
Examples include methylene bisamide and oleic acid bisamide.

The amount of fatty acid bisamide used is 0.01 to 0.5% by weight based on the polymer mixture. If the amount is less than 0,001% by weight, the effect of shortening the cooling time is small, and if it exceeds 5% by weight, the effect of shortening the cooling time is large, but localization of the foaming agent occurs, and when the particles are foam-molded, Cracks occur inside, significantly deteriorating the quality of the obtained molded product.

Therefore, it is necessary to use an amount of 0.01% by weight or more and 0.5% by weight or less, preferably 0.1% by weight or less.
% 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. The heat treatment temperature is 60°C or higher and 100°C or lower. Below 60℃, 1
When the temperature exceeds 00°C, the effect of shortening the cooling time is small, and the heat treatment time 1-j is 30 minutes or more.

If the cooling time is less than 30 minutes, the effect of shortening the cooling time is small.The surface erosion agent is added to the expanded styrene polymer particles in an amount of 0°O1□ to Oo5% by weight, preferably 0.05 to 0.35% by weight.
use. If it is less than 0.01% by weight, the effect of shortening the cooling time is small, and if it exceeds 0.5% by weight, the effect of shortening the cooling time is large, but the moisture content of the obtained molded product increases, There are drawbacks such as shrinkage of the material, making it impossible to obtain the desired dimensions, and a significant decrease in mechanical strength.

If the bitterness at 30℃ is less than 0.95, the above method will cause a large shrinkage of the molded product, making it difficult to obtain a molded product with the desired dimensions, the appearance of the molded product will be poor, and the mechanical strength will decrease, so it is not practical. Not on point.

Furthermore, if the 3o"ci7 value is 2.0 or more, the cooling time will be longer and the desired reduction in vapor atmosphere during molding cannot be measured.

Therefore, by adjusting the temperature of the styrene polymer particles at 30°C to 0.095 to 2°O, preferably 1.0 to 1.5, it is possible to reduce the cooling time without reducing the mechanical strength. ” Discovered that the amount of steam could be reduced by 17
This led to the completion of this invention.

The specific viscosity I→ of the present invention is determined as follows.

0.150 fl (T) using an Ostsold viscometer
1) Add styrene to toluene 15% in a test tube with a stopper.
ml at 30°C, put 10ml of this solution into a viscometer, and put it in a constant temperature bath set at 30°CVc for a falling number of seconds (1
), and use the same viscometer to measure pure toluene for 10 seconds.
(to) is measured.

The relative viscosity %' can be determined from the ratio of falling seconds to/l, ignoring density changes between pure solvent and dilute solution, and 1 to φ is calculated by the following formula.

a formula: Here, Y: Viscosity of the solution Each: viscosity of pure solvent t: Number of seconds for solution to fall to: number of seconds for pure solvent to fall It is.

The present invention will be explained below with reference to Examples.

[The capitals all indicate the capital of heavy eyes.]

Example 1 100 parts of styrene, 120 parts of pure water, 0 parts of penzoyl peroxide
゜18 capital, 1.1 bis (t-butylpero; toshi) 3.
5.5 0.20 parts of trimethylcyclohexane, 0.20 parts of ethylene bisstearylamide, tertiary phosphoric acid, Q. 20 parts of α-olefin sulfonic acid sorghum, 0.0025 parts of α-olefin sulfonic acid, 0.35 parts of sodium chloride, and 2.5 parts of toluene were placed in a polymerization reactor, and polymerization was carried out at 90''C under a nitrogen atmosphere.

After the polymerization was completed, 0.20 parts of tertiary phosphoric acid, 9 parts of butane, and 1.5 parts of n-hebutane were added, the temperature was raised to 115°C, and the foaming agent was impregnated at this temperature for 6 hours. ,90°
It was cooled to C and heat treated for 5 hours.

The mixture was then cooled to 50°C, dehydrated, dried and sieved to obtain expandable styrenic polymer particles having a particle size of 710 to 1056 microns. To 100 of the polymer particles, 0.10 of hardened soybean oil, which is a surface erosion agent, was applied to expandable styrene thread polymer particles (hereinafter referred to as 1 Example 2. 0.26 of benzoyl peroxide in Example 1). Resin particles [■] were obtained in the same manner except that the resin particles (II) had a value of 1.0.

Example 3 Resin particles [11] were obtained in the same manner as in Example 1 except that 0.15 parts of benzoyl peroxide was used. Resin particle CDI]
of? 4 td 1.5”'Cara fc.

Example 4 0.05 part of hardened soybean oil was applied to expandable styrenic polymer particles obtained in the same manner as in Example 1 to form resin particles [■].
I got it. The Y4 value was 1.3.

Example 5 0.25% of hardened soybean oil was applied to expandable styrenic polymer particles obtained in the same manner as in Example 1 to form resin particles (V,
] was obtained. It was 1.3.

Example 6 Resin particles (Vl,
I got 1. The nq of the resin particles (W) was 1.3.

The obtained resin particles (I) ~ [■] are heated with steam at a magnification of 5.
After pre-foaming 5 times and curing at room temperature for 24 hours, molding was performed using a Pearl Star 90 molding machine manufactured by Toyo Kikai Kinzoku Co., Ltd.

The evaluation of the molding results is shown in Section 3.

Comparative Example 1 Resin particles [■] were obtained in the same manner as in Example 1 except that 0.30 parts of benzoyl peroxide was used.

Comparative Example 2 Resin particles [■] were obtained in the same manner as in Example 1, except that the amount of benzoyl peroxide was changed to 0.11.

The at fat particles obtained in the comparative example were pre-foamed and molded in the same manner as in the example. Evaluation of molding results in %/
& shown.

Claims (1)

[Claims] 1. Expandable styrene is obtained by suspension polymerizing styrene or a vinyl monomer mixture containing styrene and copolymerizable with styrene (hereinafter abbreviated as vinyl monomer) in an aqueous medium. In the method for producing polymer particles of the general formula RCONHOH2CH2N HCOR for vinyl monomers,
0.01% to 0.50% by weight of fatty acid bisamide represented by ' (herein, R1R' is a hydrocarbon group having 8 to 32 carbon atoms, and R and R' may be the same or different) Specific viscosity (ripe) at 30°C is 0.95-
・Add a foaming agent and a foaming aid to styrene-based polymer particles of 2.0 and impregnate them to make 100% V by weight of styrene-based polymer.
At the stage where 1% by weight or more of the blowing agent and 0.1% by weight or more of the foaming aid have been absorbed by CS, heat treatment is performed at a temperature of 60 to 1 GG°C, and the resulting expandable styrenic polymer particles have a surface A method for producing expandable styrenic polymer particles, which comprises applying an erosive agent. 2 General formula RCONHC! H20H2NHC! OR',
The method for producing expandable styrene thread polymer particles according to claim 1, wherein the fatty acid bisamide represented by (R, R' are 0-8 to 32 hydrocarbon groups) is ethylene bissoallylamide. . 3. The method for producing expandable styrenic polymer particles according to claims 1 and 2, wherein the amount of ethyl bisstearylamide used is 0.01 to 0.50 parts by weight based on the vinyl yarn monomer. . 4. The method for producing expandable styrenic polymer particles according to claim 1, 2, or 3, wherein the blowing agent is butane or isobutane. 5. The blowing agent is n-hexane, n-hexane, or A method for producing expandable styrenic polymer particles according to claim 1, 2, 3, or 4, which is a mixture of butane, cyclohexane, toluene, and ethylbenzene. 6. Heat treatment. The method for producing expandable styrenic polymer particles according to claim 1, 2, 3, 4 or 5, wherein the time is 30 minutes or more.7 The surface erosion agent is a hardened oil or fat. or Claims 1 and 2 consisting of an ester of a higher fatty acid and a higher alcohol;
The method for producing expandable styrenic polymer particles according to item 3, 4, 5, or 6. 8. The method for producing expandable styrenic polymer particles according to claim 7, wherein the surface erosion agent is hydrogenated soybean oil, hydrogenated beef tallow oil, or hydrogenated palm oil. 9 Special F where the ester of higher fatty acid and higher alcohol is composed of laflic acid lubitan ester, palminic acid p/sorbicun ester, stearic acid 4-sorbitan ester, or oleic acid sorbitan ester! f. A method for producing expandable styrenic polymer particles according to claim 7. Items 1, 2, 3, 4, 5, and 5, wherein the amount of the IO surface erosion agent used is 0.01 to 0.5% by weight based on the expandable styrenic polymer particles. Section 6, Section 7, Section 8,
Item 9. A method for producing expandable styrenic polymer particles as described in item 9.