JPS58122932A - Foamable styrene resin particle - Google Patents

Abstract

PURPOSE:To provide foamable styrene resin particles with a low heat softening temp., moldable in a short period, contg. a foaming agent in a copolymer resin of a styrene monomer with a maleimide derivative. CONSTITUTION:A styrene resin obtained by copolymn. of a styrene monomer (e.g., styrene, alpha-methylstyrene) with a maleimide derivative of the formula (wherein R is a 5C or higher aliphatic hydrocarbon group), wherein said styrene resin contains about 0.1-10mol% maleimide derivative unit, is impregnated with about 1-20wt% foaming agent (e.g., propane, butane).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to expandable styrenic resin particles that can significantly shorten molding time.

A widely used method for producing styrene resin foam is to first heat expandable styrene resin particles with steam to expand them once (primary foaming), leave them for a certain period of time (ripening), and then form small pores. It is filled into a mold with a gap, heated with water vapor (secondary foaming), cooled the mold, waited for the foaming pressure inside the molded product to decrease, and then opened the mold and taken out the foamed molded product. be. during this process.

The length of mold heating and cooling time has the greatest impact on productivity.

Several methods have been attempted to shorten this cooling time. For example, US Pat. No. 2,989,782 discloses that (1) a liquid organic compound having a boiling point of 100° C. or more is added to the outer shell or surface of expandable styrenic resin particles; (9) an aromatic alkyl ester such as toluene or linseed oil; It is described that the molding time can be shortened by the presence of monoglycerides and the like. However, in this method, the liquid organic compound permeates inside during the storage of each particle, which is likely to cause blocking during foaming.

This method has disadvantages such as a marked reduction in the cooling time reduction effect.

In addition, West German Patent Publication No. 2133253 discloses that (1) the surface of expandable styrenic resin particles is coated with a lipophilic surfactant, specifically a mixture of glycerin and mono-, di-, and tri-esters of saturated fatty acids; Reduces cooling time during molding.

It is stated that good fusion between expanded particles can be achieved. However, in this method, since the surfactant has a hydrophilic group, it easily absorbs condensed water from steam during molding.
It has the disadvantage that the moisture content during molding is high.

The inventors of the present invention have - as a result of their earnest efforts to develop expandable styrenic resin particles that can overcome the above-mentioned drawbacks and can significantly shorten the heating and cooling times of molds, found that the thermal softening temperature of styrenic resin particles is It has been found that the molding time can be significantly shortened by lowering the temperature during molding.

That is, the present invention provides a foamable styrenic resin comprising a styrenic resin and a blowing agent, in which the styrenic resin has a styrenic monomer and a general formula (II CH=CH 1 (wherein, R is carbon The present invention relates to expandable styrenic resin particles having 5 or more substitutions.

In the present invention, the styrenic single body refers to styrene or substituted styrenic resins such as α-methylstyrene, vinyltoluene, and chlorostyrene.

It is contained in an amount of more than 6 mol in the general formula for copolymerizing with styrene monomers. If the compound represented by the general formula (11) is too small in the styrenic resin, the performance and molding performance will deteriorate.

In the general formula (11), the group R is an optionally substituted saturated or unsaturated aliphatic hydrocarbon group having 5 or more carbon atoms, such as hexyl and nonyl.

Saturated hydrocarbon groups such as dodecyl, hexadecyl, and eicosyl groups, unsaturated hydrocarbon groups such as pentenyl, valmityl, and linol, 1,2-dichlorohexyl, 1,2.3
These include halogen-substituted saturated or unsaturated hydrocarbon groups such as 4-lichlorooctadecenyl. When the number of carbon atoms in the base pores is less than 5, the thermosetting temperature does not decrease, which is not preferable.

Furthermore, if the number of carbon atoms in R becomes too large, the retention of the blowing agent may deteriorate, so it is preferable that the number of carbon atoms in R is 30 or less. %, the carbon number of R is preferably 5-10 to 20.

Styrenic resin can be obtained by copolymerizing a styrene monocap and a compound represented by the general formula (11).
At this time, other copolymerization components include acrylonitrile,
Vinyl cyanide compounds such as methacrylonitrile, methyl acrylate, ethyl acrylate, butyl acrylate.

Acrylic esters such as hydroxyethyl acrylate, methacrylic esters such as methyl methacrylate, ethyl methacrylate, and hydroxyethyl methacrylate, unsaturated dicarboxylic anhydrides such as maleic anhydride, and mono- or dialkyl esters thereof. Two or more types may be used in combination.

The above styrene resin is selected from the viewpoints of expansion ratio, fusion of molded products, surface appearance, manufacturing cycle, etc.

Its constituent components include 50% styrene monomer.

It is preferable to contain at least 1.

There are no restrictions on the method of copolymerization; suspension polymerization, bulk polymerization, solution polymerization, etc. are arbitrary.

6- Also, suitable polymerization initiators include benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, and di-tert-butyl peroxide.

2.5-1 (peroxybenzoate) hexyne-3,
1,3-bis(13butylperoxyisopropyl)benzene, lauroyl peroxide, tert-butylperacetate, 5-dimethyl-45-di(tert-butylperoxy)hexyne-3゜2.5-dimethyl-λ5 - modified peroxides such as di(tert-butylperoxy)hexane and tert-butylberbenzoate, methyl ethyl ketone peroxide, methyl cyclohexanone peroxide, organic peroxides such as azobis-isobutyronitrile and dimethyl azodiisobutyrate; There are azo compounds such as azobis-isobutyronitrile and dimethylazodiisobutyrate, and one or more of these can be used. The amount used is determined by the type of polymerization component and the desired molecular weight of the resulting polymer.
Preferably, it is used in an amount of 01 to 4.0% by weight based on the polymerization components.

When carrying out M turbidity polymerization, it can be polymerized in an aqueous medium, but in this case 9 a sparingly soluble phosphate as a dispersant.

Water-soluble polymeric protective colloids and the like can be added to the polymerization system. As a poorly soluble phosphate.

Examples include tricalcium phosphate and magnesium phosphate. Examples of polymeric protective colloids include polyvinyl alcohol, water-soluble cellulose derivatives such as alkyl cellulose, hydroxyalkyl cellulose, and carboxyargyl cellulose, and sodium polyacrylate. The amount of poorly soluble phosphate is 0.01% by weight based on the total amount of substances present in the polymerization system.
As mentioned above, it is preferable that the water-soluble polymeric protective colloid is used in a range of 1 to 0, OO, 1% by weight. In addition, anionic surfactants and water-soluble inorganic salts can be added to the polymerization system. When synthesizing a resin by solution polymerization, it is preferable to use xylene, toluene, or the like, which has a boiling point higher than that of the 9-polymerization component, as an organic solvent for ease of polymerization.

The polymer blowing agent that is one of the components of the present invention has a boiling point lower than the softening point of the styrenic resin used in combination, and has the property of not dissolving the styrenic resin or only slightly swelling it. Use one with Such blowing agents include aliphatic hydrocarbons such as propane, butane and pentane, cycloaliphatic hydrocarbons such as cyclobutane and cyclopentane, and methyl chloride.

Mention may be made of halogenated hydrocarbons such as dichlorodifluoromethane. The amount of blowing agent used is 1 to 20% by weight, preferably 3 to 15% by weight based on the styrene resin.
This is the percentage of

Among the above blowing agents, when propane and butane are used alone or in combination, it is preferable to use a small amount of a polystyrene or styrene copolymer solvent. Examples of such solvents include ethylene dichloride, trichloroethylene, tetrachloroethylene, benzene, toluene, xylene, ethylbenzene, and the like.

How to impregnate styrene resin with a blowing agent.

A method in which particles of the styrene resin (obtained by suspension polymerization) or pelletized products are suspended in an aqueous medium and a blowing agent is press-fitted into the suspension, and the above styrenic resin and blowing agent are kneaded. There are two methods: a method of soaking the styrene resin in a foaming agent (liquid), and the like. Further, when the above-mentioned styrene resin is obtained by suspension polymerization, a blowing agent can be press-injected during the polymerization, preferably at a point when the conversion rate of the block monomer is 50% by weight or more.

Note that the resin particles according to the present invention may contain known additives such as pigments, M fuel agents, antioxidants, and antistatic agents.

After foaming, steam foaming is further performed in a molding machine to obtain a molded product.

By using the expandable styrenic resin particles according to the present invention, the heating and cooling time of the mold can be significantly shortened and the productivity of molded product manufacturing can be improved.

The reason for this is that the thermal softening temperature of the resin particles is about 10 DEG C. lower, which lowers the molding mixture and allows molded products to be produced in less than 10 degrees. For example, in the case of foaming and molding polystyrene resin particles, the mold temperature must be kept at about 110°C, whereas the resin particles according to the present invention can be molded at about 100°C.

Next, examples of the present invention will be shown. In the examples, "part" means "part by weight".

Example 1 1 portion of ion-exchanged water was placed in a 4e autoclave with a rotary stirrer.
50OFF (100 parts), basic calcium phosphate2.
25Ff (0.15 parts) and sodium dodecylbenzenesulfonate 0.045 F (0.003 parts) were added and dispersed uniformly, followed by styrene 1425f (95 parts).
Dissolve 75p (sm) of N-laurylmaleimide in and then dissolve 3.75f (0.25 parts) of benzoyl peroxide.
Add a solution of 1.551' (0,1 part)
The temperature was raised to 0.degree. C., and one polymerization was started. Proceed with polymerization while maintaining the temperature at 90°C, measure the specific gravity of the particles using a specific gravity solution near the end of the temperature increase at 90°C, and when it is confirmed that the specific gravity exceeds 1.0, calcium phosphate 2.25F (0.15 copies)
, )” Sodium Decylbenzenesulfonate 0.045
p (0,003 copies) was added. Next, 15f (1.0 parts) of ethylbenzene was added, and after 20 minutes, 25f of butane gas was added.
0 ml was injected under pressure with nitrogen gas. After the butane gas injection was completed, the temperature started to rise again, and after 2 hours, the temperature was raised to 125°C, and the reaction was continued for 4 hours while maintaining this temperature. Then, the system was cooled to 30°C and the excess gas in the system was discharged. Thereafter, it was separately dried to obtain expandable styrene resin particles. The particles contained 8.5% by weight of butane, which is a blowing agent. These particles were sieved to obtain particles with a particle size of 1.68 to 0.841111, and 0.04 zinc stearate powder was added as an anti-blocking agent.
After adding % by weight and mixing thoroughly, the mixture was pre-foamed using steam to obtain pre-foamed particles with a bulk ratio of 60 times.

After leaving the foamed particles for 24 hours, a molding test was conducted to measure the time required for heating, the time required for cooling, and the degree of internal fusion.

The heating time required is 0.7 Kq of steam pressure when heating both sides of the mold.
f/ryr? The heating time was set as the heating time necessary to obtain a molded body with a good degree of internal fusion. After heating, water was passed to the outside of the mold, and when the mold surface temperature reached around 70°C, the cooling water was stopped, and after that, the molded product was left to cool so that the temperature was approximately 70°C when the molded product was taken out. . The mold used for molding has a thick part of 50x75x400mm and a thin part of 10x75x40mm.

If the cooling time is short and the cooling is insufficient, the wall thickness of 50~ will swell, but if sufficient cooling is done, the thickness of 49~
It will be 50 yen S. The cooling time is necessary so that the thickness of the molded body becomes 50% when the mold is opened.

It was measured as the total time required for water cooling and air cooling.

The degree of internal fusion is 100° when the bottom center of the molded product is folded and broken, and the degree of bonding of the pre-expanded particles at the cut surface is 100°, when all the foamed particles are broken at the middle. The degree of fusion is expressed with the case being O.

The above measurement method and measurement values are common to the following examples.

In this example, the heating time is 24 seconds, and the cooling time is 16 seconds.
The internal fusion degree was 80 degrees.

131 Example 2 Particles were produced in the same manner as in Example 1, except that 150p (10 parts) of N-2 urylmaleimide was dissolved in 1350190 parts of styrene as a monomer component when producing polystyrene resin particles.

Gas was added, molded, and evaluated. What are the evaluation results?

The heating time was 20 seconds, the cooling time was 150 seconds, and the degree of internal fusion was 90 degrees.

Example 3 Kijirole 180 (1) was heated to 100° C. with stirring through cine active gas in a 4 g four-bottle flask, and styrene 1425 P (95 parts) was added thereto.

A mixed solution of N-laurylmaleimide 75F (5 parts) and azobisisobutyronitrile 15P (1 part) was added dropwise over 2 hours. After the dropwise addition, the reaction temperature was raised to 120° C. and the reaction was continued for 5 hours, which was then determined as the end point.

The pheasant roll used as a solvent was then separated by heating and distillation.

After pelletizing the styrene resin produced in this way using a pellet molding machine, 150 ml of sulfur-exchanged water (
1009), basic calcium phosphate 3.0ff (O,
2 parts) and 0.1 sodium dodecylbenzenesulfonate
5? (0.01 parts), calcium carbonate 45Ff (0.3
1 part) and 1 asoy pellet (9 parts) were charged, and the temperature in the system was raised to 80° C. while stirring. After raising the temperature, 15y-(1 part) of ethylbenzene was added, and 240 ml of butane gas was further pressurized with nitrogen gas. Thirty minutes after the butane gas was pressurized, the temperature began to rise again, and after 2 hours, the temperature was raised to 115° C. Thereafter, stirring was continued for 3 hours while maintaining this temperature. Thereafter, the mixture was cooled to 30° C., excess gas in the system was discharged, and the mixture was filtered and dried to obtain expandable styrene resin particles. These particles were molded and evaluated according to Example 1. The evaluation results showed that the time required for heating was 24 seconds and the time required for cooling was 160 seconds.

The degree of internal fusion was 80%.

Example 4 In carrying out solution polymerization, 1 asoy of styrene (9 parts) and 150 parts of N-lauryl maleimide were used as monomer components.
Example 3 was followed except that 10 parts of F-(10 parts) was used.The evaluation result was that the heating time was 20 seconds.

The cooling time required was 150 seconds, and the degree of internal fusion was 90 degrees.

Comparative Example 1 Expandable styrene resin particles were produced as in Example 1 except that styrene 1500 fP (100 parts) was used as the monomer.
This was done in accordance with.

The time required for heating is determined by setting the vapor pressure to 1 or 0 when heating both sides of the mold.
The heating time was defined as the heating time required to obtain a molded body with a good degree of internal fusion when the temperature was 10n''.

The cooling method after heating, the required cooling time, and the measurement of the degree of internal fusion were in accordance with Example 1. The evaluation result is heating time 40
The cooling time was 270 seconds, and the degree of internal fusion was 60 seconds.

Comparative Example 2 Expandable styrenic resin particles were produced using monomers and SiCsf.
V-n1492.5t (99.5 parts), N-laurylmaleimide 7.5? (0.5 parts) was used.

It was carried out according to Example 1. The time required for heating was measured according to Comparative Example 1, and other evaluation methods were performed according to Example 1. The evaluation results show that the heating time is 38 seconds and the cooling time is 2.
70 seconds, the degree of internal fusion was 70%.

Table 1 summarizes the evaluation results of Examples 1 to 4 and Comparative Examples 1 and 2.
It was shown to.

Table 1 Evaluation Results The expandable styrenic resin particles according to the present invention lower the thermal softening temperature of the resin by using a 17-copolymer of a styrene monomer and a compound represented by the general formula By keeping the temperature low, heating and cooling times can be shortened.Furthermore, according to the present invention,
There is no need to add organic compounds (benzene, dimethyl phthalate, fatty acid monoglyceride, etc.) to the expandable styrenic resin particles to shorten the heating and cooling time during molding, and the temperature is low (around 100°C). Since it is possible to mold the product in a single step, it is possible to improve work efficiency and save energy. In addition, the appearance, strength, and fusion properties between pre-expanded particles of the resulting molded product do not fade compared to conventional foamed styrene resin molded products.

18-

Claims (1)

[Scope of Claims] 1. In a foamable styrenic resin containing a styrenic resin and a blowing agent, the styrenic resin contains a styrenic monomer and the general formula (11 (wherein R is the number of carbon atoms) 5
or more substituted fat particles. Expandable styrenic resin particles according to claim 1.