JPS598367B2 - Expandable thermoplastic polymer particle composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition of expandable thermoplastic polymer particles, and more particularly, to a composition of expandable thermoplastic polymer particles, and more particularly to a composition of expandable thermoplastic polymer particles, and more particularly, when pre-expanding the expandable styrene polymer or styrene copolymer particles. The present invention relates to a foamable thermoplastic polymer particle composition that prevents blocking and also provides excellent interparticle fusion when formed into a foamed molded product.

The production of foamed molded articles has conventionally been carried out using the following process.

That is, a polymer is prepared by suspension polymerization or the like, and is impregnated with a blowing agent to form expandable polymer particles. Next, the particles are heated and foamed in a pre-foaming machine using steam or the like, and then the pre-foamed particles are cured in a silo and left to air dry for several days. After that, a large number of /''L for steam heating
The pre-expanded particles are filled into the inside of a molding machine mold equipped with a mold, and pressurized steam is injected through small holes to heat the pre-expanded particles above their softening point, and the expanded particles are fused together and integrated. A molded article is obtained by converting the molded article into a molded article. The properties required of thermoplastic particles used for such purposes, particularly expandable styrene polymer or styrene copolymer particles, are that they do not cause a blocking phenomenon in which the particles fuse together during the pre-foaming process. Also, when the pre-expanded particles are used for molding, the particles fuse together.

In other words, in order to obtain pre-expanded particles, foamable polymer particles are heated and foamed using steam or the like while stirring in a pre-expanding machine. Blocked particles adhere to the foam, and in extreme cases, this may cause problems such as stopping the stirring of the foaming machine.

In addition, the pre-expanded particles obtained in this way are temporarily stored in a silo for curing and air drying, but the transfer to the silo is carried out using a pipe or the like, and at this time, the blocked particles are not included. If it is, the pipe will become clogged and smooth transfer will not be possible. In addition, filling the molding machine with pre-expanded particles is carried out by air through the feeder 1, but if blocking particles are present at that time, they may clog the feeder 1 pipe, or they may enter the mold. Filling is also insufficient. Because of this inconvenience, it is necessary to prevent locking. Further, when molding using pre-expanded particles, it is required that the expanded particles are fused to each other, and this is required in order for the molded article to have sufficient mechanical strength. However, conventional means for preventing blocking have been insufficient in their ability to prevent blocking, or have adversely affected the fusion during molding.

Examples of various methods for preventing blocking include coating the surface of the expandable particles with metal salts of higher fatty acids, such as zinc stearate, calcium stearate, lithium stearate, sodium stearate, etc.; A method of adding them during polymerization is known. Also, coating higher fatty acid amides or esters, etc.
Alternatively, a method of adding it during polymerization is also known. Similarly, a method of coating the surface of expandable polymer particles with an inorganic substance has also been reported, and inorganic substances used for such purpose include calcium carbonate, magnesium carbonate, talc, hydrated calcium silicate, Silica etc. are known. However, since these inorganic substances have a particle size of several microns, and because they are inorganic substances, they have poor adhesion to expandable polymer particles, so that their anti-blocking effect is not sufficient. The present invention provides thermoplastic particles, particularly expandable styrene polymer particles or styrene copolymer particle compositions, which have an extremely small amount of blocking during pre-foaming and do not inhibit the fusion between pre-foamed particles during molding. It is something.

That is, the thermoplastic polymer particles contain 1 to 15% by weight of a blowing agent such as a saturated or unsaturated aliphatic hydrocarbon having a boiling point lower than the softening point of the polymer particles, such as propane, n-butane, isoptane, or pentane. On the surface of the expandable polymer particles, 0.01 to 0.5% by weight of an inorganic substance having an electric charge with an average particle size of 2 mμ to 10 μm and an amount of electric charge to cancel out the electric charge of the inorganic substance were added to the surface of the expandable polymer particles. By applying a dissociable organic compound, the above-mentioned expandable polymer particles are provided with the required performance. The fine particle size inorganic material used in the present invention may be in the form of a colloid, slurry, or powder, and is preferably in a colloidal state.

The colloidal inorganic material is not particularly limited, and includes, for example, a silica colloid liquid, an alumina colloid liquid, a lithium oxide colloid liquid, and a ferric oxide colloid liquid. Also,
There are no particular restrictions on the slurry, such as silica, calcium carbonate, alumina, titanium oxide, etc.
A slurry such as calcium phosphate is used. In addition, dissociable organic substances used in combination with inorganic substances, that is, organic substances that can ionically dissociate when made into a solution, include cationic surfactants,
Anionic surfactants, amphoteric surfactants, organic acid metal salts,
There are organic acids, etc. When selecting a dissociable organic substance, select it so that when the inorganic substance is a colloid or slurry, or when a powder is made into a slurry, the organic ionic part of the dissociative organic substance has a charge opposite to that of the inorganic substance. . (However, the organic ionic moiety is, for example, taking a typical monovalent dissociative organic substance as an example. Letting it be RX (where R is the organic moiety), the dissociated state is RX+:.R**+X**( however,*,*
*represents electric charge). R when deciding X
* indicates. ) For example, when an anionic colloid (e.g. silica colloid) is used as the inorganic substance, a cationic surfactant is selected, and when a cationic colloid (e.g. alumina colloid) is used, an anionic surfactant or an organic acid metal salt is selected. Further, the form of the dissociable organic substance is not particularly limited, but it is preferably in a solution state. Regarding the application ratio of the inorganic substance and the dissociable organic substance, when the inorganic substance is in the form of a colloid or slurry, it is necessary to minimize the blocking that occurs when the amount of the dissociable organic substance selected in the above method is changed relative to the inorganic substance. The point is
It is estimated that it corresponds to the isoelectric point. Therefore, it is particularly preferred that the quantitative ratio of inorganic matter to dissociable organic matter be selected so as to exhibit an isoelectric point. Of course, it is also possible to use the coating ratio in a region where the amount of blocking on both sides of the isoelectric point is reduced. Next, the cationic surfactants mentioned here are not particularly limited, and include, for example, alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamines, etc. Specifically, laurylamine acetate, lauryl trimethyl Commercially available cationic surfactants such as ammonium chloride, alkylbenzyldimethylammonium chloride, and polyoxyethylene alkylamine can be used.

Next, anionic surfactants are not particularly limited, and examples include fatty acid salts, alkyl sulfate salts,
Commercially available anionic surfactants such as alkylbenzenesulfonates, alkylnaphthalenesulfonates, dialkylsulfosuccinates, alkylphosphates, naphthalenesulfonic acid formalin condensates, and polyoxyethylene alkylsulfates can be used. It is possible. Further, the amphoteric surfactant is not particularly limited, and commercially available amphoteric surfactants such as lauryl betaine and stearyl betaine can be used. Next, the organic acid metal salts may be lower organic carboxylic acid metal salts, organic sulfonic acid metal salts, organic phosphate metal salts, etc. that do not belong to the class of surfactants, and are not particularly limited. Further, the organic acid is not particularly limited, and commercially available ones such as lower and higher organic carboxylic acids, organic sulfonic acids, and organic phosphoric acids can be used.
Next, regarding the coating method, there are no particular limitations, but one example is to apply a colloidal or slurry inorganic substance to the foamable polymer particles, and then apply a dissociable organic substance, preferably in a solution state, before drying. do.

2. A dissociable organic substance is applied in a solution state, and an inorganic substance in a colloidal or slurry form is applied before it dries.

3 A colloidal or slurry inorganic substance and a dissociable organic substance are mixed and applied to the surface of a polymer particle.

Or apply its dry powder. 4 Apply the surfactant solution, and before it dries, apply the inorganic fine powder.

There are other methods. By such a method, it is possible to obtain a material having much better anti-blocking ability than when an inorganic substance is used alone. For example, the dissociable organic substance acts as a mediator between the inorganic substance and the foamable polymer particles, thereby improving the adhesion of the inorganic substance to the foamed particles. Furthermore, when a colloidal inorganic substance and a dissociable organic substance are used, the inorganic substance can be attached to the surface of the expandable particles while maintaining the primary particle size. In this way, the ultrafine anti-blocking agent can be easily attached to the foamable polymer particles. Incidentally, it is of course possible to use the method according to the present invention in combination with conventional blocking prevention techniques.

This will be explained below using examples.

Example 1 Expandable styrene polymer particles "Kanepal GB" manufactured by Kanebuchi Chemical Co., Ltd., whose surface additives were washed away by washing with methanol, were used as expandable styrene polymer particles to obtain the blocking amount and mold fusion described below. I asked for degree.

A 2% solution of the cationic surfactant Sanizol C (manufactured by Kao Soap Co., Ltd.) was applied on the surface of expandable styrene polymer particles 1K9 with a particle size of 7.36 to 1000 μm in the following amounts based on the true nature of the cationic surfactant. Then, apply Snowtex-40 and methanol silica sol (both colloidal silica, manufactured by Nissan Chemical Co., Ltd.) on top of the mixture in the following amounts based on the silica content and blend well.

The obtained peas were air-dried and foamed to an apparent magnification of 50 times using a small pre-foaming machine, and the amount of blocking particles at this time was separated and measured using an 8-mesh sieve.
In addition, the pre-expanded particles thus obtained were heated to a vapor pressure of 0.6 kg/CrA using a BELMO-90 molding machine (manufactured by Kaken Kiko K.K.).
, and tertiary heating was performed for 2 J seconds, and the fusion during molding was evaluated.
However, mold fusion refers to the rate of fusion between foamed particles on the fractured surface of a molded body, and refers to the fusion rate between foamed particles on the fractured surface when the molded body is torn apart at the boundary between foamed particles. Rather, it refers to the percentage of particles torn inside the foamed particles relative to the total number of foamed particles. However, the volatile content of the raw particles was 7.0 wt%, and the methanol silica sol and other components were as follows.

Roasted Example 2 The expandable styrene polymer shown in Example 1
Average particle size 100 mμ (longer diameter) using “Kanepal GB”
×10 mμ (minor diameter) alumina sol-200 (alumina colloid: manufactured by Nissan Chemical Co., Ltd.), Liporan-1400
(Anionic surfactant: manufactured by Lion Yushi Co., Ltd.) 1.0%
A similar experiment was conducted using an aqueous solution and the following results were obtained.

However, the volatile content of the raw grain is 6.9%. Alumina sol 200, Riporan 1400 The composition is as follows.

Example 3 The expandable styrene polymer “Canepal G” shown in Example 1
A similar experiment was conducted using Alumina Sol-200 (alumina colloid: manufactured by Nissan Chemical Co., Ltd.) and a 10% aqueous solution of sodium p-pynylbenzenesulfonate.
I got the following results.

However, the volatile content of the raw grain is 6.7%. Alumina sol-200
See Example 2 for the composition.

Claims (1)

[Scope of Claims] 1. A foamable thermoplastic polymer containing 1 to 15% by weight of a saturated or unsaturated aliphatic hydrocarbon having a boiling point lower than the softening point of the polymer particles as a blowing agent in the thermoplastic polymer particles. The surface of the combined particles contains 0.01 to 0.5% by weight of a charged inorganic material with an average particle size of 2 mμ to 10 μm based on the polymer particles, and a dissociable organic material having an amount of charge that cancels out the charge of the inorganic material. 1. An expandable thermoplastic polymer particle composition, characterized in that the composition is coated with a compound. 2. The composition according to claim 1, wherein the inorganic substance is in the form of a colloid or slurry. 3. The composition according to claim 1, wherein the dissociable organic compound is in the form of a solution. 4. The composition according to claim 1, wherein the thermoplastic polymer particles are styrene polymer particles. 5 The inorganic substance is colloidal silica, colloidal silver iodide, colloidal alumina, colloidal ferric oxide, silica slurry,
The composition according to claim 1, which is one or more selected from the group consisting of calcium carbonate slurry, alumina slurry, titanium oxide slurry, and calcium phosphate slurry. 6. The composition according to claim 1 or 3, wherein the dissociative organic compound is an anionic surfactant, a cationic surfactant, or an organic acid metal salt.