JPS58109537A - Foamable thermoplastic resin composition and preparation thereof - Google Patents

Abstract

PURPOSE:To prepare the titled composition of which foaming capacity is not deteriorated with the elapse of time, by a method wherein a vinyl monomer is subjected to suspension polymerization in an aqueous medium containing a specific hydroxy fatty acid amide and a foaming agent is infiltrated in the latter half of the polymerization or after the polymerization is completed. CONSTITUTION:A vinyl monomer (e.g. styrene) is added in an aqueous medium containing a dispersant such as a hardly soluble phosphate, an anionic surfactant and a polymerization initiator to initiate suspension polymerization and, until the polymerization degree of the vinyl monomer reaches 50wt%, 0.005-0.5wt% (based on an obtained thermoplastic resin) hydroxy fatty acid amide shown by the formula (wherein R is a 10-22C divalent aliphatic hydrocarbon group) is added to succeed the polymerization. When a polymerization conversion degree reaches 50wt%, or after the polymerization is completed, 1-20wt% foaming agent (e.g. butane) having a b.p. lower than the softening point of the thermoplastic resin is infiltrated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a foamable thermoplastic resin composition and a method for producing the same.

Conventional foamable resins using a liquid or gas as a foaming agent under normal conditions have various drawbacks. That is, in general, foamable resins cannot be used unless they are aged for a considerable period of time after production.

Foams obtained by pre-foaming (-post-foaming) foamable thermoplastic resin immediately after production with steam at 100°C may have no internal cell structure or have a small number of cells. is very coarse and large. Regarding individual particles, the distribution of cells is different between the outer layer and the inside of the particle.

Therefore, the molded product obtained by heating and fusing such pre-expanded particles indoors has a significantly inferior product -□ value. Therefore, the produced expandable thermoplastic resin is usually aged under certain conditions for several days to one month before being shipped. After producing a foamable thermoplastic resin in this way, if it is left to mature for a while and then pre-foamed, the number of cells will be large and the cells will become fine. The cell distribution of individual particles is also uniform. The degree of this tendency varies depending on the expandable resin particle system used. For example, as the number of carbon atoms in the blowing agent becomes smaller, such as hexane, pentane, butane, or propane, this tendency becomes much greater. However, in any case, the foamable thermoplastic resin needs to be aged for a while after its production.

However, long-term aging should be avoided as much as possible. The reason for this is that when the aging period becomes long, the foaming agent dissipates and the foaming ability and power decreases. Furthermore, conventionally, the ripening temperature had to be 20°C or lower, making it necessary to install a cooling device for ripening in the summer.

Further, when a gaseous foaming agent is used at normal temperature and normal pressure, the foaming ability deteriorates significantly, and when a liquid foaming agent is used at normal temperature and normal pressure, the ripening period becomes longer.

A further drawback that both types have in common is that when aged resin is moved to a different environment, it returns to its original unaged state.

As mentioned above, general foamable thermoplastic resins have the following nine drawbacks.

(1) If the resin is foamed immediately after production, the cells in the cross section of the foam will be very rough.

(2) When the resin is exposed to high temperatures and then foamed, the cells in the cross section become rough.

(3) If the entire resin is stored until the foamed cells become fine (without foaming), then the resin is exposed to a high temperature similar to summer temperature again and then foamed, the cells will become coarse.

Also.

(4) Particles tend to block in the pre-foaming machine.

The present invention solves these problems.

That is, the first invention is a thermoplastic resin 9 blowing agent and general formula (1) % formula % (1) (However, in formula 9, R is a divalent aliphatic hydrocarbon group having 10 to 22 carbon atoms) The present invention relates to a foamable thermoplastic resin composition containing a hydroxy fatty acid amide represented by:

The above thermoplastic resin is not particularly limited.

Styrenic resins are particularly suitable. Styrenic resins include styrene or styrene derivatives such as α-methylstyrene, vinyltoluene, and parachlorostyrene, acrylic esters such as acrylonitrile, ethyl acrylate, and butyl acrylate, methyl methacrylate, Examples include methacrylic acid esters such as butyl methacrylate, methacrylate, and 5-cetyl fluoride, and copolymers of monomers such as vinylpyridine, vinylcarbazole, ethylene, propylene, butadiene, and styrene or styrene derivatives.

Further, as the second composition, one containing a styrene resin and another tree such as a styrene polymer containing rubber or the like is preferable.

Next, the blowing agent 9 is an easily volatile organic compound that is in a gaseous or liquid state under normal conditions. What is suitable?

aliphatic hydrocarbons) aliphatic halokenated hydrocarbons and alicyclic compounds whose boiling point is lower than the softening point of the thermoplastic resin. For example, propane, butane,
Isobutane, pentane, impentane, hexane, cyclohexane.

These include methyl chloride, ethyl chloride, Freon gas, etc., and can be used alone or in combination of two or more.

Of these, it is better to use a gaseous blowing agent under normal conditions.
This is more effective for the purpose of this invention.

It is sufficient that the blowing agent is contained in an amount of 1 to 20 tqb based on the thermoplastic resin, and may be 1.9.15% by weight or less.

Examples of the hydroxy fatty acid amide represented by the general formula (11) include hydroxylauric acid amide, hydroxypalmitic acid amide, hydroxymyristic acid amide, hydroxystearic acid amide, hydroxyoleic acid amide, etc. These may be used alone or in combination. Can be used in combination with seeds or more.The leaves have a thermoplastic resin content of 0.0
The amount is preferably 0.05% by weight or more. When the amount is less than 0.005% by weight, the effects of the present invention tend to decrease. Furthermore, even if the amount exceeds 0.5 weight Mongolia, no significant increase in the effect can be expected, so it is sufficient to use 0.5 weight 11% or less.

The desired resin is manufactured by a conventional method. For example, when the base resin is produced by aqueous suspension polymerization (including suspension polymerization using monomers partially subjected to bulk polymerization and using monomers in which the polymer is dissolved).

The hydroxy fatty acid amide is added to the polymerization system.

The timing of addition is arbitrary, but in order to ensure uniform distribution in the resin, it is preferable to add it to the monomer before the start of polymerization or when the polymerization rate is 50% by weight or less. At this time, it is dissolved in monomer or solvent.

Alternatively, it is preferable to disperse it.

In the case of suspension polymerization, methods for adding a blowing agent include:
Although it is possible to adopt a method in which the foaming agent is added midway and the polymerization and impregnation are performed simultaneously, it is also possible to perform the nine blowing agent impregnation steps once the polymerization step is completed. When using a method other than the suspension method, the latter method should be used. When added during suspension polymerization, it is generally not preferable to add it in the first half of the polymerization step from the viewpoint of particle dispersion.

Therefore, the second invention relates to a preferable manufacturing method capable of obtaining the above-mentioned foamable thermoplastic resin composition in the form of particles.

That is, in the second invention, when a vinyl monomer is subjected to aqueous suspension polymerization, a hydroxy fatty acid amide represented by the above general formula (I) is present in the polymerization system and polymerized.
The present invention relates to a method for producing a foamable thermoplastic resin composition, which comprises impregnating a foaming agent in the latter half of polymerization or after the completion of polymerization.

It is preferable to

Here, the above-mentioned vinyl monomer can be a monomer that is a raw material for the thermoplastic resin in the first invention, of which 500% by weight of styrene or styrene derivatives can be used.
It is best to use it on top. The blowing agent and the hydroxy fatty acid amide represented by the general formula fl) are the same as in the first invention.

The hydroxy fatty acid amide represented by general formula (I) is
When the polymerization conversion rate of the vinyl monomer is 50 times or above, a sparingly soluble 9-phosphate, a water-soluble polymeric protective colloid, etc. can be added to the polymerization system as a dispersant in the above-mentioned turbid polymerization.

Tricalcium phosphate is a poorly soluble phosphate.

Examples include magnesium phosphate. Examples of polymeric protective colloids include polyvinyl alcohol, water-soluble cellulose derivatives such as alkyl cellulose, hydroxyalkyl cellulose, and carboxyalkyl cellulose, and sodium polyacrylate. It is preferable that the sparingly soluble phosphate is used in an amount of 0.1% by weight or more based on the total amount of substances present in the polymerization system, and the water-soluble polymer protective colloid is used in an amount of 1 to 0.001% by weight.

In addition, anionic surfactants and water-soluble inorganic salts can be added to the polymerization system.

Polymerization initiators suitable for use in the process of the invention include benzoyl peroxide, dichlorobenzoyl peroxide,
Dicumyl peroxide, di-tert-butyl peroxide, 2,5-di(peroxybenzoate) hexyne-3
,1,3-bis(tertiary-butylperoxyisopropyl)
Pen 10-zene, lauroyl peroxide, tert-butylberacetate, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3,2,5-dimethyl-2,5-di(tert-butylperoxy) 3-butylperoxy)hexane and organic peroxides such as tert-butylberbenzoate, methyl ethyl ketone peroxide, methyl cyclohexanone peroxide,
azo compounds such as azobis-isobutyronitrile and dimethylazodiisobutyrate;

One or more of these can be used. The amount used is determined depending on the type of vinyl monomer and the desired molecular weight of the resulting polymer, but it is preferably used in an amount of 0.1 to 4.0% by weight based on the vinyl monomer. Ru. The polymerization initiator can be added by being dissolved in the vinyl monomer.

The blowing agent used in the present invention is one that has a boiling point lower than the softening point of the resin to be produced, and has the property of dissolving vinyl resin particles and causing no or slight swelling of the vinyl resin particles. is. Such blowing agents include propane, butane,
Examples include aliphatic hydrocarbons such as pentane, cyclic aliphatic hydrocarbons such as cyclobutane and cyclopentane, and halogenated hydrocarbons such as methyl chloride and dichlorodifluoromethane. Thus, the amount of blowing agent is in a proportion of 1 to 20 parts by weight based on the weight of the thermoplastic resin. Among the above blowing agents, when propane and butane are used alone or in combination, it is preferable to use a small amount of an organic solvent that dissolves the vinyl polymer during impregnation with the two blowing agents. Examples of such solvents are ethylene dichloride, trichlorethylene, tetrachloroethylene, benzene, toluene, xylene.

Examples include ethylbenzene.

Impregnation with the blowing agent can be carried out by adding the blowing agent to the aqueous medium during the first polymerization, or by adding the blowing agent to the polymer particles suspended in the aqueous medium after the second polymerization. If a blowing agent is to be added during the polymerization, it is preferable to do so after the conversion of the vinyl monomer reaches 50% by weight or more, from the viewpoint of stability of the polymerization system.

Next, two examples of the present invention will be shown. In addition, below.

Parts are parts by weight.

Example 1 In an autoclave equipped with a stirrer, 0% tribasic calcium phosphate was added.
．． 1 part, 0.5 part of a 1% aqueous solution of sodium dodecylbenzenesulfonate was dispersed or dissolved in 100 parts of distilled water. To this, 0.25 part of benzoyl peroxide and 0.1 part of hydroxystearamide.

100 parts of styrene in which 0.05 part of t-butyl perbenzoate was dissolved or dispersed was added with stirring.

Polymerization was initiated at 90° C. under nitrogen. After adding 0.05 part of tribasic calcium phosphate at 2 hours and 30 minutes, and further adding 0.3 part of tribasic calcium phosphate at 7 hours, 2 parts of cyclohexane and 7 parts of butane were introduced over a period of 1 hour. After that, the temperature was raised to 120℃ over 2 hours, and the temperature was increased to 5℃.
After keeping the mixture for a certain period of time, it was cooled to room temperature and the target expandable thermoplastic resin was taken out as spherical particles. Immediately after drying, pre-foaming was performed, but no blocking of foamed particles occurred.

13- Also, the cells in the cross section were very fine. Further, although this resin was exposed to 35° C. and then foamed five times, the cells in the cross section of the pre-expanded particles were fine.

Comparative Example 1 A foamable thermoplastic resin 9 was obtained in the same manner as in Example 1 except that hydroxystearamide was not added. The cells that were pre-foamed immediately after drying were so coarse that they could not be used as commercial products.

Example 2 Polymerization rate of 0.1 part of hydroxystearic acid amide 604
A foamable thermoplastic resin 1 was obtained in the same manner as in Example 1 except that it was added at the time of . The cells that were pre-foamed immediately after drying were coarse.

Example 3 In the same manner as in Example 1, 100 parts of styrene was added to a 106 flask.
Catalyst, oxystearamide 0.05 part9 Dispersant,
Add 100 parts of water and heat at 90°C for 7 hours.

It was kept at 120°C for 2 hours. 100 parts of the resulting resin.

200 parts of water, 0.4 parts of polyvinyl alcohol, 14 parts of pork
- 710 parts were impregnated in an autoclave at 100° C. for 4 hours. Even when the obtained particles were immediately pre-foamed with steam at 100°C, the cells remained fine.

Comparative Example 2 Example 2 except that oxystearamide was not added.
A foamable thermoplastic resin was obtained in the same manner as above. When pre-foaming was carried out immediately after, the cells were extremely rough and unusable.

Table 1 shows the results of testing the expandable thermoplastic resins obtained in Examples 1 and 2 and Comparative Examples 1 and 2.

Below is white 15- 16 one The expandable thermoplastic resin of the present invention has the following advantages.

(1) Even if the particles are pre-foamed immediately after production, the cells in the cross section are fine, so they can be immediately used for molding, and therefore the management and storage of manufactured products can be streamlined.

(2) Cell roughness does not occur even when exposed to high temperatures.

Does not require refrigeration for storage.

(3) The blocking phenomenon of the pre-foamed product can be significantly reduced.

(4) The cell cross section of the pre-expanded particles is uniform and very fine.

-low

Claims (1)

[Claims] 1. Thermoplastic resin 1 Blowing agent and general formula (1) % formula % (wherein R is a divalent aliphatic hydrocarbon group having 10 to 22 carbon atoms) A foamable thermoplastic resin composition containing a hydroxy fatty acid amide represented by the following: 2. A foamable thermoplastic resin composition containing a hydroxy fatty acid amide represented by the general formula +11 at 0.0 O5 weight J1 or more based on the thermoplastic resin. The foamable thermoplastic resin composition according to item 1. 3. When carrying out suspension polymerization of the vinyl monomer in an aqueous medium, the general formula fll HOR-CONH2 (11 (wherein R has 10 to 22 carbon atoms) A method for producing a foamable thermoplastic resin composition, characterized in that a hydroxy fatty acid amide represented by (a divalent aliphatic hydrocarbon group) is present in the polymerization system, and a foaming agent is impregnated in the latter half of the polymerization or after the completion of the polymerization. 4. The foamable thermoplastic resin composition according to claim 1, wherein the hydroxy fatty acid amide represented by the general formula (1) is present in the polymerization system until the polymerization rate of the vinyl monomer reaches 50% by weight. manufacturing method.