JPS6211740A - Production of expandable styrene resin particle - Google Patents

Abstract

PURPOSE:To obtain the titled particles giving a formed product containing completely fused foamed particles and narrow particle gap, by coating the surface of an expandable styrene resin particle with a specific nonionic surfactant, and decreasing the surface water-content below a specific level. CONSTITUTION:The surface of an expandable styrene resin particle containing one or more kinds of foaming agents in a styrene resin particle is coated with 0.01-0.3 wt% (based on the resin particle) nonionic surfactant having an HLB of >=7, preferably ether-type polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, etc., and the water attached to the surface is dried to a surface water content of <=0.5wt% to obtain the objective particle. The polyoxyethylene alkyl ether is pferably polyoxyethylene lauryl ether.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing expandable styrenic resin particles. In more detail, C. Manufacturing a molded product having a cellular structure. During the molding process, the foamed particles are completely fused together at their interfaces, and the gap between the particles is reduced as much as possible. Regarding the method.

[Conventional technology]

Expandable styrenic resin particles are prepared by impregnating a foaming agent such as a polystyrene resin particle with an easily volatile aliphatic hydrocarbon, such as n-pentane, which causes the particles to swell slightly, in an aqueous suspension; Alternatively, it can be produced by a method such as 6, in which a small amount of a solvent such as toluene or cyclohexane that is soluble in polystyrene resin particles is impregnated in an aqueous suspension together with a blowing agent such as butane or propane, which is constantly in the gaseous state.

The expandable styrenic resin particles produced in this way are used as a raw material for manufacturing expanded styrene resin molded articles. In order to industrially and economically produce foamed styrene resin shaped bodies, the foamable styrene resin particles are made into pre-expanded particles by steam, etc., and the pre-expanded particles are formed into a wall surface having a desired shape with a large number of small holes. The particles are filled into a closed mold with a hole in them, and a heating medium such as steam is ejected from the small holes in the mold to heat the particles to a temperature higher than the softening point of the pre-expanded particles and fuse them together. The foamed styrene resin molded article having the desired shape is produced by taking it out from the inside of the mold.

[Problem that the invention seeks to solve]

Since the expandable styrenic resin particles produced as described above coalesce and become agglomerated during the pre-foaming process,
It blocks the particle transfer pipe or the mold cavity filling hole and becomes an obstacle in the molding process.

Therefore, there is a need for expandable styrenic ballast particles that do not agglomerate when pre-foamed. For this purpose, the surface of the expandable styrenic resin particles is coated in advance with, for example, metal soap, talc powder, or wax. It is difficult for the particles to completely fill the gaps between the particles in the special molding station, and foaming is suppressed due to the accumulation of steam drainage generated during heating, and the resulting molded product does not fuse well with each other, resulting in failure immediately after molding. It has a large amount of water,
Furthermore, the filling condition of the pre-expanded particles near the mold surface is poor, resulting in a high porosity, leading to increased drainage in this area, leading to problems such as particle gaps occurring on the surface of the molded product.
゜When the molded product thus obtained is used, for example, as a packaging material for electrical products, it must be thoroughly dried. When used for heat insulating materials, containers, etc., even if sufficiently dried, moisture permeates during use, resulting in disadvantages such as reduced heat insulation and water leakage.

Furthermore, since the molded product is not sufficiently foamed, the product has a poor appearance, which spoils the image of the product as a packaging material.

[Means for Solving the Problem] The present inventors aimed to improve the drawbacks of the above-mentioned prior art, and the inventors of the present invention aimed to improve the drawbacks of the above-mentioned prior art. As a result of intensive research to obtain a molded product having a cell structure with as few cells as possible, the present invention was completed.

That is, the present invention applies HLB (hydrophile-1i
After coating 0.01 to 0.3 parts by weight of a nonionic surfactant with a Phophile Balance value of 7 or more in an aqueous solution or water dispersion state, dry the moisture attached to the surface to reduce the surface moisture to 0.s% or less. The present invention provides a method for producing expandable styrenic resin particles characterized by the following.

The expandable styrenic resin particles in the present invention are resin particles obtained by adding a blowing agent during polymerization, or impregnating it after polymerization, such as a polymer of styrene alone or other polymers containing styrene as the main component. These are polymer particles that can be foamed by heating a copolymer with a vinyl monomer, etc., by impregnating the polymerization core with a liquid or gaseous foaming agent in a regular bath or by impregnating it after polymerization. Additives may also be included.

As the blowing agent, an easily volatile hydrocarbon having a boiling point lower than the softening point of the resin particles is used.

It is preferable to use one that does not dissolve the resin particles or slightly swells the resin particles, and may be one type or a mixture of two or more types.

For example, it is propane, butane, pentane, or a substance containing these as the main component, and a portion thereof may be substituted with hexane, heptane, cyclohexane, methyl chloride, freon, etc.

In the world of foaming agents, the amount is 1 to 20 parts by weight.

The nonionic surfactant used as a coating material in the present invention has an HLB value of 7 or more, preferably 9 to +, and
Nonionic surfactants with a LB of less than 7 tend to be oil-soluble and cannot be used for the purpose of the present invention. For example, water-soluble polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, polyoxyethylene alkyl ether, Examples of nonionic surfactants that belong to these include HLB value! Polyoxyethylene lauryl ether of 2.1 to 17.3, HLB value 11.9
~17.5 polyoxyethylene cetyl ether, HL
Polyoxyethylene oleyl ether with B value of 13.3 to 16.6, polyoxyethylene stearyl ether with HLB value of 12.7 to 16.5, polyoxyethylene finger ±1 fatty acid ether with HLB value of 13.0, HLB value of 13 Polyoxyethylene octylphenol ether of ゜6-17.9, HLB
Polyoxyethylene nonylphenol ether with a value of 13.3 to +8.7, HLB value 13. Polyoxyethylene laurate with lN 17.7, HLB value 13.8-18.
1 polyoxyethylene palmy? -t, HLB value 13.
6-18.2 polyoxyethylene stearate, HL
Polyoxyethele 7 with B value 13.5-17.2, t
f-t, polyoxyethylene sorbitan monolaurate with an HLB value of 16.7, polyoxyethylene rubitan monopalmitate with an HLB value of 15.6, and HLB value of 14.
9 polyquine ethylene sorbitan monostearate,
There is polyoxyethylene norbitane monooleate with an HLB value of 15.0.

The coating material is 0.01% based on the expandable styrenic resin particles.
~0.3 parts by weight are used. It can be measured by the 0.01 part by weight method.

The nonionic surfactant is coated on the foamable styrenic resin or resin particles in an aqueous solution or in a water-dispersed state, and then the moisture is dried. Coating with a liquid nonionic surfactant that does not contain water causes uneven coating and does not have any effect on smoothing the surface of the molded article, whereas an aqueous solution or dispersion coats the molded article uniformly and surprisingly. The present inventors have found that by drying the surface moisture after coating to less than 0.5% by weight, preferably less than 0.1% by weight, the surface of the molded product has no particle gaps and has an excellent appearance. discovered by. If the surface moisture exceeds 0.5 weight factor, particle gaps will appear on the surface of the molded product, resulting in poor appearance and reduced product value.

There are various coating methods.

For example, the coating agent can be attached to the surface of the resin particles by sufficiently mixing the expandable styrenic resin particles and an aqueous solution or dispersion of a nonionic surfactant using a blender or the like.

In this case, it is okay to impregnate and coat the expandable styrenic resin particles with an antistatic agent, an anti-agglomeration agent during pre-foaming such as zinc stearate, Merck, calcium carbonate, water repellent, etc. after the coating treatment. do not have. Furthermore, as a coating method, expandable styrene resin particles impregnated with a blowing agent in an aqueous suspension are dehydrated using, for example, a centrifugal dehydrator, and then a nonionic surfactant or its aqueous solution or aqueous dispersion is added to the resin using a blender or the like. It is advantageous to apply the coating or agent to the surface of the particles.

In this case, since the nonionic surfactant also has antistatic efficiency, it may be mixed with other antistatic agents for coating, if necessary.

There are various drying methods, and it is possible to dry the moisture adhering to the expandable styrenic resin particles together with the nonionic surfactant. Moisture on the surface of resin particles can be measured using a Karl Fischer moisture meter using a methanol dehydrated solvent.

〔Example〕

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

Example 1 In a pressure-resistant reactor equipped with a stirrer and a temperature detection tube, 100 parts by weight of styrene monomer, 110 parts by weight of water, 0.15 parts by weight of tricalcium phosphate, and parts by weight of dodecylbenzenesulfonate and oosit were placed. , irperoxide 0.
25 parts by weight and 0.1 part by weight of tert-butyl perbenzoate were added, and while stirring, the mixture was heated under a pressure of 0.5 kg/d of nitrogen.
The temperature was raised to 0°C and polymerization was carried out for 5 hours.

Next, 1.8 parts by weight of cyclohexane and 8.5 parts by weight of butane were added, the temperature was raised to 105°C, and impregnation with the blowing agent was carried out for 6 hours. This was cooled to room temperature to obtain true spherical expandable polystyrene resin particles. After drying, the particles were sieved to obtain particles of 14 to 20 meshes, and then 0.09 parts by weight of zinc stearate was added, stirred with a ribbon blender, and then taken out.

Expandable polystyrene resin particles 100 obtained by the above method
5% polyoxyethylene oleyl ether (H
LB value 15.4, 1 part by weight of the aqueous solution (made by NOF Corporation) was stirred in a container so as to uniformly coat the surface, and after drying the water in a flash dryer,
Expandable polystyrene resin particles coated with ylether were obtained.

The expandable polystyrene resin particles were heated with steam in a batch pre-expanding machine to obtain pre-expanded particles with an apparent volume of about 60 times.

After curing and drying the pre-expanded particles in the air for 24 hours, they were molded using a Pearl Star 90 automatic molding machine (manufactured by Toyo Kikai Kinzoku KK) with a cavity size of 3.00 mm x 450 mm x 20 mm.
I made sure to mold it using rI's mold.

Table 1 shows the internal melting rate, internal state, surface state, and internal moisture content of the obtained molded body.

(The marks ◎, ○, and △ for the internal condition in the table indicate the center part of the molded body.
00 plate x 450 rrrn
○ means that there is a slight gap, △ means that there is a gap, and the marks of ◎, ○, and △ in the surface condition indicate the surface smoothness and the state of interparticles, where ◎ is excellent, ○ is good, and △ is It means somewhat poor. In addition, the internal melting rate indicates the rate of fusion between foamed particles on the fractured surface of a molded body. It is expressed as the ratio of particles torn inside to the total number of particles. Also, the internal moisture is 2 at 40℃ and the molded weight immediately after molding.
The weight difference after drying for 4 hours was divided by the weight after drying. ) Example 2 5% polyoxyethylene steryl ether (HLB value +5.3, NOF K) was added to 100 parts by weight of the expandable polystyrene resin particles obtained in Example 1 in the same manner as in Example 1.
1 part by weight of an aqueous solution (manufactured by K. K.) was coated and dried. Pre-foaming and molding were carried out in the same manner as in the actual PIs. The results are shown in Table 1. Example 3 To 100 parts by weight of the expandable polystyrene resin particles obtained in Example 1, 5-thipolyoxyethylene lauryl ether (HLB value 16.2% NOF KK) was added in the same manner as in Example 1. Coated with 0.2 parts by weight and 3.2 parts by weight of an aqueous solution (manufactured by Manufacturer, Inc.) and transferred to another university.

Pre-foaming and molding were performed in the same manner as in Example 1.

The results are shown in Table 1.

Example 4 To 100 parts by weight of the expandable polystyrene resin particles obtained in Example 1, 1 part of a 5-th polyoxyethylene octyl phenol ether (HLB value + 6.2, manufactured by NOF KK) aqueous solution was added in the same manner as in Example 1. Cover by weight and dry. Pre-foaming and molding were performed in the same manner as in Example 1. The results are shown in Table 1.

Example 5 Example! 100 parts by weight of the expandable polystyrene resin particles obtained in Example 1 were coated with 1 part by weight of a 5% aqueous solution of polyoxyethylene nonylphenol ether (HLB value 17.1, manufactured by NOF KK) and dried. Pre-foaming and molding were performed in the same manner as in Example 1. The results are shown in Table 1.

Example 6 Expandable polystyrene resin particles obtained in Example 1, Child 10
0 parts by weight of 5-thipolyoxyethylene stearate (HLB value +3.6, NOF KK
1 part by weight of an aqueous solution (manufactured by ) was coated and dried. Pre-foaming and molding are examples! I went the same way. The results are shown in Table 1.

Comparative Example 1 The expandable polystyrene resin particles obtained in Example 1 were pre-foamed in the same manner as in Example 1 without using a nonionic surfactant.The results are shown in Table 1. HLB value 16.2) 0.5 parts by weight, 0.3 parts by weight, and 0.25 parts by weight of the aqueous solutions were coated and dried poorly. Pre-foam molding was performed in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 100 parts by weight of the expandable polystyrene resin particles obtained in Example 1 were coated with 0.5 parts by weight of a 10% aqueous solution of polyoxyethylene lauryl ether (HLB value 16.2) in the same manner as in Example 1. and pre-foaming without drying the moisture.
Example of molding! I did the same thing. The results are shown in Table 1.

Comparative Example 3 Liquid polyoxyether 7 nonylphenol ether/' (HLB value + 5.0
．． , manufactured by NOF KK) was coated in an amount of 0.08 parts by weight.

Pre-foaming and molding were performed in the same manner as in Example 1.

The results are shown in Table 1.

Comparative Example 4 To 100 parts by weight of the expandable polystyrene resin particles obtained in Example 1, an aqueous dispersion of polyoxyethylene nonylphenol ether (HLB value 5.7, manufactured by NOF KK) having a coefficient of 5 was added to 100 parts by weight of the expandable polystyrene resin particles obtained in Example + J. 1 part by weight was coated and dried.

Pre-foaming and molding were carried out in the same manner as in Example 〇 The results are shown in the first example.
Shown in the table.

〔Effect of the invention) The effects of the present invention are summarized as follows.

In the present invention, coalescence and agglomeration of particles during the pre-foaming process are extremely rare, and there is almost no problem in the molding process.

・Furthermore, the foamed terene-based resin molded product obtained by the present invention has excellent surface smoothness and an excellent appearance with significantly fewer particle gaps, and even on the flat plate surface cut out thinly in the center, there are no particle gaps. This method provides a molded product with almost no oxidation, so the moisture content immediately after molding is low, the water absorption rate of the molded product is extremely low, and the molded product has significant advantages such as a lower amount of electrical charge than conventional products.

Claims (1)

[Scope of Claims] 1. The surface of expandable styrenic resin particles containing one or more blowing agents in the styrenic resin particles has an HLB (hydr
ophile-lipophile balance)]
After coating with 0.01 to 0.3 parts by weight of a nonionic surfactant having a value of 7 or more as a coating agent, moisture adhering to the surface is dried to reduce the surface moisture to 0.5% by weight or less. A method for producing expandable styrenic resin particles. 2. Claim 1, wherein the nonionic surfactant is an ether type nonionic surfactant, and the nonionic surfactant is polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, or a mixture thereof. The method for manufacturing the expandable styrenic resin particles described above. 3. Polyoxyethylene alkyl ether is polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene tallow fatty acid ether, and polyoxyethylene alkyl phenol ether is polyoxyethylene The method for producing expandable styrenic resin particles according to claim 2, which is octylphenol ether or polyoxyethylene nonylphenol ether. 4. Claim 1, wherein the nonionic surfactant is an ester type nonionic surfactant, and the nonionic surfactant is polyoxyethylene alkyl ester, polyoxyethylene sorbitan alkyl ester, or a mixture thereof. The method for manufacturing the expandable styrenic resin particles described above. 5. The polyoxyethylene alkyl ester is polyoxyethylene laurate, polyoxyethylene palmitate, polyoxyethylene stearate, or polyoxyethylene oleate, and the polyoxyethylene sorbitan alkyl ester is polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monolaurate, or polyoxyethylene sorbitan monolaurate. The method for producing expandable styrenic resin particles according to claim 4, which is oxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, or polyoxyethylene sorbitan monooleate. 6. After dissolving or dispersing a nonionic surfactant used as a coating material in water and coating the surface of expandable styrenic resin particles in an aqueous solution or water dispersion state, drying the moisture adhering to the surface of the resin particles, The method for producing expandable styrenic resin particles according to claim 1, characterized in that the surface moisture content is 0.5% by weight or less.