JPH08198997A - Expandable vinyl resin particles - Google Patents

Abstract

(57) [Summary] [Structure] A polyethylene glycol (A) having a hydroxyl equivalent of 200 to 600 and a sorbitan fatty acid ester (B) having a hydroxyl equivalent of 55 to 500 are contained in the expandable vinyl resin particles. It relates to expandable vinyl resin particles. [Effect] According to the expandable vinyl-based resin particles of the present invention, the blocking property of the particles during pre-expansion is significantly reduced,
It can be smoothly filled into the molding die, the cooling time after heat molding can be shortened, the productivity can be remarkably improved, and the fusion property between particles in the molding step is also extremely excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel and useful expandable thermoplastic resin particle. More specifically, the surface of the resin particle is coated with a mixture of polyethylene glycol, sorbitan fatty acid ester and glycerin fatty acid ester. At least obtained, especially the fluidity of the expandable resin particles, the blocking property in the pre-expanding step, the antistatic property of the pre-expanding particles, the mold filling property in the molding step, the molding cycle property and the appearance of the obtained molded product. The present invention relates to dramatically improved resin particles.

[0002]

2. Description of the Related Art Foamable styrene in the form of a thermoplastic resin such as polystyrene containing 1 to 15 parts by weight of a hydrocarbon-based foaming agent or a halogenated hydrocarbon-based foaming agent based on 100 parts by weight of the thermoplastic resin. When the resin particles are heated above the softening point with water vapor or the like, so-called pre-expanded particles in the form of particles having closed cells inside can be obtained. When the pre-expanded particles are further heated with steam or the like in a closed mold capable of heating the inside with steam or the like through small holes or slits, the volume of these expanded particles expands and they are fused to each other to form the desired molded article. Becomes

The expandable thermoplastic resin particles used for such purposes have various drawbacks found in the respective molding steps as described above. Among them, the particles are blocked in the pre-foaming machine. Easy, and as a result the mold filling property in the molding process is poor, the pre-expanded particles put into the mold in the molding process are heat-fused, and the molded product is cooled in the mold when further cooled and taken out. It takes a long time, which results in a long molding cycle and poor molding productivity.

Various techniques have been conventionally proposed in order to improve these drawbacks. For example, Japanese Examined Japanese Patent Publication 58-5656
Japanese Patent Publication No. 8 discloses a technique of coating the surfaces of the expandable thermoplastic resin particles with triglycerin esters of higher fatty acids. Further, JP-A-52-33958 discloses a technique for adhering a partial ester of sorbitan to the surface of styrenic foamable resin particles, and in JP-B-60-23783, hydroxyl equivalent (hereinafter referred to as OH).
A technique in which a tetravalent ester of sorbitan having a V of 50 or less and a higher fatty acid is present on the surface of the expandable polystyrene resin is disclosed.

[0005]

However, the one in which the surface of the expandable thermoplastic resin particles is coated with the triglycerin ester of the higher fatty acid described in the above-mentioned Japanese Patent Publication No. 58-56568 is used at the time of pre-expansion. Although it has solved the problem of particle blocking and the problem of lengthening the molding cycle to some extent, it is still not sufficient.Furthermore, the fusion property between particles at the stage of integrally fusing the particles in the molding process. However, there is a problem in that, as a result, the desired mechanical strength of the molded product, other physical properties of the molded product, and required properties in the appearance of the molded product are deteriorated.

Further, in Japanese Patent Laid-Open No. 52-33958, a partial ester of foamable styrene resin and sorbitan is dispersed in water by using a surfactant to form a partial ester of sorbitan on the surface of foamable styrene resin. The technique of depositing is shown. Although this method can prevent the foamed particles from blocking during pre-expansion to some extent, its effect is not sufficient. Furthermore, since the partial ester of sorbitan is attached to the surface of the expandable styrene resin in water, the adhesion efficiency is poor and it is necessary to increase the addition amount to 0.2% to 2%, and the amount of static electricity generated by the pre-expanded particles is extremely large And has a problem with.

Further, Japanese Patent Publication No. 60-23783 discloses that sorbitan having an OHV of 50 or less and a tetravalent ester of a higher fatty acid are allowed to exist on the surface of an expandable polystyrene resin. Although the problem of particle blocking in the above has been solved to some extent, a situation in which the amount of static electricity generated in the pre-expanded particles is increased and the fusion between particles at the stage of integrally fusing the particles in the molding process is significantly reduced. In addition, there is a problem that the particles are not sufficiently fused on the surface of the molded product and the appearance is significantly impaired.

The problem to be solved by the present invention is that the blocking resistance of particles at the time of pre-expansion and the antistatic property of the obtained pre-expanded particles are remarkably excellent, and the cooling time after heat molding is shortened. It is to provide expandable thermoplastic resin particles which can remarkably improve the productivity of the foamed molded product, which is also excellent in the fusion property between particles in the molding step, and which is remarkably excellent in the appearance of the obtained molded product. .

[0009]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that by using pre-expanded particles to which a mixture containing polyethylene glycol, sorbitan fatty acid ester, and glycerin fatty acid ester as essential components is added. It has been found that the expandable thermoplastic resin particles capable of solving the above-mentioned problems can eventually provide an expandable thermoplastic resin molded product having excellent physical properties of the molded product, and completed the present invention.

That is, the present invention relates to expandable thermoplastic resin particles characterized by having polyethylene glycol (A) and sorbitan fatty acid ester (B) in an expandable vinyl resin, preferably sorbitan fatty acid ester. The present invention relates to the one using a combination with glycerin fatty acid ester (C).

The polyethylene glycol (A), the sorbitan fatty acid ester (B) and the glycerin fatty acid ester (C) used in the present invention are each alone, or among these, the sorbitan fatty acid ester (B) and the glycerin fatty acid ester (C) can be used. The above problems cannot be sufficiently solved by a combination or a combination of polyethylene glycol (A) and glycerin fatty acid ester (C).

The present invention relates to polyethylene glycol (A)
And a sorbitan fatty acid ester (B) in the expandable vinyl resin particles, the blocking resistance and antistatic property of the particles at the time of pre-expansion can be significantly improved as compared with the case where they are used alone, and in the molding process. This has the effect of significantly improving the fusion between particles. In addition to this, glycerin fatty acid ester (C)
By using together, it is possible to significantly improve the productivity of the foamed molded product with the shortening of the cooling time after heat molding,
Moreover, it is possible to obtain the expandable thermoplastic resin particles which are excellent in the fusion property between particles in the molding step and have a remarkably excellent appearance of the obtained molded product.

The mixture containing polyethylene glycol (A), sorbitan fatty acid ester (B), and glycerin fatty acid ester (C) as essential components used in the present invention is contained in the expandable thermoplastic resin particles. Or may be present on the surface of the expandable thermoplastic resin particles. In order to bring out the effect of the present invention remarkably with a small amount of addition, it is preferable that the mixture is contained in the expandable thermoplastic resin particles and not on the surface of the particles. Even when the mixture is contained in the expandable thermoplastic resin particles, it is preferable that a part of the mixture is present on the surface of the particles.

The above mixture may be added to the expandable thermoplastic resin particles by, for example, polymerizing a monomer in the presence of the mixture to form resin particles, or suspension polymerization to form thermoplastic resin particles. Then, a method of adding the mixture in the state of an aqueous suspension and heating it to a temperature above the softening point of the thermoplastic resin particles, and a method of simply mixing by a known conventional method using a drum blender, a ribbon mixer, etc. To be In these methods, it is preferable that as much of the mixture as possible comes to the surface of the particles, and from this point, a method of simply mixing by a known conventional method using a drum blender, a ribbon mixer or the like is preferable.

The polyethylene glycol used in the present invention is mainly used for improving the spreadability of the glycerin fatty acid ester or a mixture of the glycerin fatty acid ester and the sorbitan fatty acid ester on the surface of the expandable resin particles. is there. Polyethylene glycol also has the effect of reducing the static electricity generation amount and blocking generation amount of the pre-expanded particles by using together with glycerin fatty acid ester and sorbitan fatty acid ester as compared with the case where they are used alone.

The OHV of polyethylene glycol used in the present invention is 200 to 6 from the viewpoint of excellent adhesion of glycerin fatty acid ester or sorbitan fatty acid ester.
It is preferably 00.

Further, the amount of polyethylene glycol used in the present invention added to the expandable resin particles is 50 because it is excellent in spreading property of glycerin fatty acid ester or sorbitan fatty acid ester and antistatic property of pre-expanded particles.
It is preferably ˜2000 ppm. 200 added
If it exceeds 0 ppm, the fluidity of the resin particles is remarkably impaired, and the transfer and measurement of the resin particles in the pre-foaming step is hindered, which is not preferable.

The sorbitan fatty acid ester used in the present invention preferably has an OHV of 55 to 500.
The range of 5 to 300 is more preferable. OHV is 55
If it is less than the above range, the anti-blocking effect will be obtained to some extent, but the amount of static electricity generated by the pre-expanded particles will remarkably increase, and the fusion property at the time of molding and the appearance of the obtained molded product will be deteriorated, which is not preferable. If the OHV is 500 or more, the amount of static electricity generated by the pre-expanded particles is reduced, but the blocking prevention effect is significantly reduced. Therefore, sorbitan fatty acid ester having an OHV in the range of 55 to 500 is preferable because it has a high antiblocking effect, a small amount of static electricity is generated, and is excellent in fusion property during molding and appearance of a molded product.

Further, when the sorbitan fatty acid ester used in the present invention is added to the surface of the resin, if the melting point is less than 40 ° C., the fluidity of the resin particles will be significantly impaired when the addition amount exceeds 2000 ppm, and the preliminary Since it hinders the transfer and measurement of the resin particles in the foaming step, the addition amount may not be increased and a sufficient effect may not be obtained. Further, when the melting point is 80 ° C. or higher, the fusion property during molding is slightly inferior, which is not preferable. Therefore, the melting point of the sorbitan fatty acid ester can be increased sufficiently, the blocking effect is high, and the amount of static electricity generated is small.
40 ° C to 8 in terms of excellent fusion property and appearance of molded product during molding
The range of 0 ° C is preferred.

The sorbitan part of the sorbitan fatty acid ester used in the present invention is a mixture of sorbide, sorbitan and sorbitol, and its composition is not particularly limited, but it is preferable that the sorbitan content is 50% or more. Is preferable because it is less.

Specific examples of such sorbitan fatty acid ester include sorbitan monopalmitate, sorbitan dipalmitate, sorbitan tripalmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monobehenate. , Sorbitan dibehenate, sorbitan tribehenate and the like. These may be used alone or in combination of two or more.

Specific examples of naturally occurring sorbitan esters of higher fatty acids include sorbitan-hardened beef fatty acid monoester, sorbitan-hardened beef fatty acid diester, and sorbitan-hardened beef fatty acid triester.

Among these sorbitan fatty acid esters, sorbitan higher fatty acid esters obtained by reacting sorbitan with higher fatty acids are preferable because they are remarkably excellent in shortening the cooling time after heat molding.

Examples of the higher fatty acid glycerin ester used in the present invention include glycerin having a fatty acid ester structure obtained by reacting glycerin with a higher fatty acid, or naturally occurring higher fatty acid glycerin ester. When a product obtained by reacting glycerin with a higher fatty acid is used, the type of the fatty acid residue is not particularly limited, but those having 8 to 22 carbon atoms are preferred because of the excellent effect of shortening the cooling time after heat molding. Among them, those having 12 to 20 carbon atoms are more preferable because the effect of shortening the cooling time is the highest.

Examples of the higher fatty acid glycerin ester obtained by reacting glycerin with higher fatty acid include oleic acid monoglyceride, stearic acid monoglyceride, lauric acid monoglyceride, behenic acid monoglyceride, oleic acid diglyceride, stearic acid diglyceride, and lauric acid. Diglyceride, behenic acid diglyceride, oleic acid triglyceride,
Examples thereof include stearic acid triglyceride, lauric acid triglyceride, and behenic acid triglyceride.
These may be used alone or in combination of two or more.

Specific examples of naturally occurring higher fatty acid glycerin esters include hardened beef fatty acid monoglyceride, hardened beef fatty acid diglyceride, hardened beef fatty acid triglyceride, glycerin ester extracted from palm oil or palm oil, and the like. .

Of these, higher fatty acid glycerin esters obtained by reacting glycerin with higher fatty acids are preferable because they are remarkably excellent in the effect of shortening the cooling time after heat molding.

Further, the higher fatty acid glycerin ester used in the present invention does not need to have all the hydroxyl groups on glycerin esterified as in the above-mentioned specific examples, and even if the hydroxyl groups remain in the molecular structure, the present invention can be sufficiently used. Although effective, 2 substitution is preferable to 1 substitution, and 3 substitution is preferable to 2 substitution from the viewpoint that the cooling time after thermoforming becomes shorter. The amount of static electricity generated in the pre-expanded particles is smaller in the case of 2-substitution than 3-substitution and 1-substitution rather than 2-substitution, and they can be arbitrarily mixed depending on the application.

The addition amount of the glycerin fatty acid ester used in the present invention is excellent in terms of antiblocking property, antistatic property of pre-expanded granules, molding cycle property, fusion property during molding and appearance of molded product. The range of 200 ppm to 5000 ppm is preferable with respect to the expandable resin particles. If the addition amount is less than 200 ppm, the blocking prevention effect, the static electricity generation preventive effect of pre-expanded granules and the molding cycle shortening effect are remarkably reduced, and if it exceeds 5000 ppm, the fusion property at the time of molding and the appearance of the molded product are remarkably deteriorated.

The mixture used in the present invention contains the above-mentioned polyethylene glycol, sorbitan fatty acid ester and preferably glycerin fatty acid ester as essential components. Other components include higher fatty acid amides and higher fatty acid polyglycerin ester. Inorganic compound powders such as compounds, metal soaps, talc, calcium carbonate or silica, and commonly known coating agents such as silicone oil may be used in combination, and the effect of the present invention can be further improved by such combination.

The amount of the above mixture used depends on the method of addition to the resin particles and is not particularly limited, but when the mixture is simply mixed with the expandable resin particles and the mixture is present on the surface of the particles, a small amount is used. The remarkable effect appears.

In this case, specifically, the amount of the mixture used when it is present on the surface of the resin particles is 10 parts by weight or less, in particular, from the viewpoint of excellent internal fusion of the molded product with respect to 100 parts by weight of the resin particles. The range of 0.005 to 1.0 part by weight is more preferable from the viewpoint of excellent blocking preventing effect of the pre-expanded particles.

A method of polymerizing monomers in the presence of the mixture to form resin particles, suspension polymerization to form thermoplastic resin particles, and then adding the mixture in the form of an aqueous suspension to form the thermoplastic resin particles. When the method of heating to a temperature above the softening point of the resin particles is used, the amount of the mixture present near the surface of the obtained resin particles decreases, so the addition amount is 20 for each 100 parts of the monomer or resin particles. Weight part or less, especially from the viewpoint of excellent blocking preventing effect of pre-expanded particles, 0.01 to
A range of 3.0 parts by weight is preferable.

The thermoplastic resin which forms the pre-expanded particles used in the present invention is not particularly limited, but a styrene resin is preferable, and examples thereof include a styrene homopolymer (polystyrene) and an alkylstyrene homopolymer such as methylstyrene. , A copolymer of styrene and alkyl styrene,
A copolymer of styrene and acrylic acid or methacrylic acid, a copolymer of styrene and acrylic ester or methacrylic acid ester, a copolymer of styrene and acrylonitrile, a blend of the above styrene-based polymer and polyolefin, etc. Among them, a styrene homopolymer in which the effect of shortening the cooling time during molding is remarkably exhibited is preferable.

The expandable thermoplastic resin particles used in the present invention are obtained by suspension polymerization of a monomer, which is a raw material of the thermoplastic resin, in an aqueous medium, or by pelletizing the thermoplastic resin by an extrusion method. Among them, the method of suspension-polymerizing a monomer in an aqueous medium is preferable because the obtained particles are spherical.

A polymerization initiator is preferably used in the suspension polymerization. Examples of the polymerization initiator include benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 2,5-di (peroxybenzoate) hexyne-3,1,3-bis (t
-Butylperoxyisopropyl) benzene, lauroyl peroxide, t-butylperacetate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-
3,2,5-dimethyl-2,5-di (t-butylperoxy) hexane, and t-butylperbenzoate,
Examples thereof include organic peroxides such as methyl ethyl ketone peroxide and methyl cyclohexanone peroxide; and azo compounds such as azobis-isobutyronitrile and dimethylazodiisobutyrate. These can be used alone or in combination of two or more.

The amount of the polymerization initiator to be used is appropriately determined depending on the desired molecular weight of the monomer and the thermoplastic resin particles to be obtained, but 0.1 to 4 parts by weight is used with respect to 100 parts by weight of the monomer. It is preferable.

The method of impregnating the thermoplastic resin particles with the foaming agent is not particularly limited, and during the suspension polymerization,
The particles can be impregnated at the end of the suspension polymerization or after drying the particles after the suspension polymerization. For example, in an autoclave, thermoplastic resin particles having a considerable degree of polymerization, preferably 80% or more, or thermoplastic resin particles that have been previously polymerized and have been prepared and a hydrocarbon foaming agent are in the state of an aqueous suspension. It is preferable to heat the thermoplastic resin particles to a temperature equal to or higher than the softening point of the particles.

The blowing agent means an easily volatile hydrocarbon chain having a softening point lower than that of the resin particles used.
Typical examples of the foaming agent include propane, butane, pentane, hexane, heptane and chain hydrocarbons such as isomers thereof, cyclic hydrocarbons such as cyclohexane and cyclopentane, monochloroethane, dichloroethane and Examples thereof include halogenated hydrocarbon chains such as dichlorofluoromethane. The content of the foaming agent is 1 to 100 parts by weight of the thermoplastic resin or monomer.
A range of 15 parts by weight is suitable, and the foaming agent may be mixed and used.

When propane, butane, pentane, cyclohexane or the like is used alone or in combination,
A small amount of a known and commonly used solvent such as an aromatic hydrocarbon such as toluene, xylene or ethylbenzene or an ester such as ethyl acetate or butyl acetate may be used together. Further, a nucleating agent such as clay or an amide with ethylenebisamine aliphatic carboxylic acid may be added.

The particle size of the expandable thermoplastic resin particles thus obtained varies depending on the intended use of the molded product, but is usually 0.5 to 1.5 mm.

The process from the expandable thermoplastic resin particles of the present invention to a molded article may be a conventional method,
Although not particularly limited, for example, the prediction 85-
Pre-expanded particles are formed by pre-expanding by blowing steam at 110 ° C. to a bulk ratio of 20 to 100 times (pre-expanding step), exposing the pre-expanded particles to the atmosphere, allowing air to penetrate into the particles and removing moisture adhering to the particles. Individual particles are obtained by removing (aging step) and then filling the pre-expanded particles that have undergone this aging step into the mold of a closed mold having small holes and slits and re-expanding by heating with steam. Examples of the method include forming a fusion-bonded molded body.

The foamed molded product thus produced is useful for various cushioning materials, heat insulating materials, packaging containers and the like.

[0044]

EXAMPLES Next, the present invention will be specifically described with reference to production examples, examples and comparative examples.

Examples 1 to 13 Immediately after suspension polymerization using a styrene monomer, a blowing agent containing propane and butane as a main component was impregnated at a ratio of 6 parts by weight to 100 parts by weight of polystyrene particles,
Polystyrene beads having an average particle size of 0.8 to 1.00 mm were obtained. 50 kg of the polystyrene and various mixtures shown in Table 1 were charged into a ribbon mixer according to the blending ratio of Table 1,
The expandable polystyrene particles were obtained by stirring and mixing for 5 minutes.

The expandable polystyrene resin particles thus obtained were pre-expanded by a continuous foaming machine so as to have a ratio of about 60 times. The pre-expanded particles were passed through a sieve having an opening of 10 mm, and the ratio of coagulated particles remaining on the sieve to the pre-expanded particles was calculated. Table 1 shows the results. At this time, 2 liters of the pre-expanded particles were placed in a bag of 5 liter polyethylene net and shaken 10 times, and then the ratio of the pre-expanded particles attached to the net due to static electricity to the entire net area (electrostatic generation rate) was determined. . Table 1 shows the results. Then, after leaving the pre-expanded particles for 24 hours, a fully-automatic molding machine was used to fill the incompletely sealed mold with product dimensions of 450 mm × 300 mm × 150 mm with compressed air, and immediately after that the mold was closed. , 0.5 kg / cm ² (gauge pressure) with steam, and take out the product with various cooling time after heat molding, measure the molded product size, and measure the molded product size to the mold size ±
The shortest cooling time within 2% was determined. Further, the product was broken at the central part and broken, and the ratio of the broken expanded particles (degree of fusion) was determined. The results are shown in Table 1.

Examples 14 to 17 In a 25 l autoclave equipped with a rotary stirrer, ion-exchanged water 12000 g, styrene 12000 g, epoxidized fatty acid ester "Eposizer W-121" (manufactured by Dainippon Ink and Chemicals, Inc.) 48 g and Table 1 Of the various mixtures, sorbitan fatty acid ester and / or glycerin fatty acid ester were added at the mixing ratio shown in Table 1, and after the stirring was started, 20.0 g of basic phosphate and 0.018 g of potassium persulfate were added, and benzoyl was further added. 36.0 g of peroxide and 1 of t-butyl perbenzoate
After adding 2.0 g, a suspension polymerization reaction was performed at 90 ° C. for 6 hours to form polystyrene particles. Then toluene 1
80 g was added, and after 15 minutes, 780 g of butane gas was injected, the temperature was raised to 120 ° C. at 15 ° C./hour, and the reaction was continued at this temperature for 2 hours. After the reaction is complete, cool to 25 ° C, extract the contents, dry and screen,
Expandable polystyrene particles having a particle size of 0.8 to 1.0 mm were obtained. 50 kg of the polystyrene and polyethylene glycol alone of the various mixtures shown in Table 1, or this polyethylene glycol and sorbitan fatty acid ester and / or glycerin fatty acid ester were charged into a ribbon mixer according to the blending ratio of Table 1, and mixed by stirring for 5 minutes. Expandable polystyrene particles were obtained. After that, the measurement was performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 Foamable thermoplastic resin particles were obtained in the same manner as in Example 1 except that the mixture of polyethylene glycol, sorbitan fatty acid ester and glycerin fatty acid ester was not added, and the same measurement was carried out. Table 1 shows the results.

Comparative Example 2 Expandable thermoplastic resin particles were obtained in the same manner as in Example 1 except that only 50 g of triglyceride stearate was added.
Then, the same measurement was performed. Table 1 shows the results. From this result, it is clear that the coagulation of pre-expanded particles, the generation of static electricity and the deterioration of the fusion rate of the molded product are remarkable only with triglyceride stearate.

Comparative Example 3 Expandable thermoplastic resin particles were obtained in the same manner as in Example 1 except that only 50 g of sorbitan tristearate was added, and then the same measurement was performed. Table 1 shows the results. From this result, it is clear that the sorbitan tristearate alone improves the fusion degree of the molded product, but has almost no effect of preventing static electricity of the pre-expanded particles and shortening the cooling time.

Comparative Example 4 Expandable thermoplastic resin particles were obtained in the same manner as in Example 1 except that only 50 g of polyethylene glycol having a molecular weight of 300 was added, and then the same measurement was performed. Table 1 shows the results. From these results, polyethylene glycol alone improves the fusion degree of the molded product, but deteriorates the coagulation of the pre-expanded particles,
It is clear that there is almost no effect of reducing the cooling time.

Comparative Example 5 Expandable thermoplastic resin particles were obtained in the same manner as in Example 1 except that 25 g of polyethylene glycol having a molecular weight of 300 and 25 g of triglyceride stearate were added, and the same measurement was carried out. Table 1 shows the results. From this result, it is clear that the polyethylene glycol and the triglyceride stearate alone slightly reduce the amount of static electricity generated in the pre-expanded particles, but deteriorate the coagulation of the pre-expanded particles and significantly deteriorate the fusion rate of the molded product.

Comparative Example 6 Expandable thermoplastic resin particles were obtained in the same manner as in Example 1 except that 25 g of sorbitan tristearate and 25 g of triglyceride stearate were added, and then the same measurement was performed. Table 1 shows the results. From this result, it is clear that only sorbitan tristearate and triglyceride stearate slightly reduce the static electricity generation amount of the pre-expanded granules, but the coagulation of the pre-expanded granules is deteriorated and the fusion rate of the molded product is significantly deteriorated.

[0054]

[Table 1]

Note 1: Polyethylene glycol having a molecular weight of 300 (OHV = 300). Numbers are addition amount (g) Only in Example 13 polyethylene glycol having a molecular weight of 500 (OHV = 500).

Note 2: The symbols in the table are: M: sorbitan monostearate (OHV = 270, melting point = 48 ° C.), T: sorbitan tristearate (OHV = 77, melting point = 56)
° C).

The numbers are addition amounts (g). Note 3: Symbols in the table are M: glycerin monostearate, D: glycerin distearate, T: glycerin tristearate. The numbers are the added amount (g).

Note 4: The sorbitan fatty acid ester of Examples 14, 15 and 17 and the glycerin fatty acid ester of Examples 16 and 17 were added at the start of polymerization.

[0059]

EFFECTS OF THE INVENTION According to the expandable vinyl resin particles of the present invention, the blocking property of the particles during the pre-expansion is remarkably reduced, the filling into the molding die can be carried out smoothly, and the heating is performed. The cooling time after molding can be shortened, the productivity can be remarkably improved, and the fusion property between particles in the molding process is also extremely excellent. Therefore, the resin particles of the present invention are useful as a container for containing fish and agricultural products, as a cushioning material for storing and transporting electric parts and appliances, or as a heat insulating material for construction.

Claims (10)

[Claims] 1. Expandable vinyl-based resin particles comprising polyethylene glycol (A) and sorbitan fatty acid ester (B) in expandable vinyl-based resin particles. 2. The resin particles according to claim 1, wherein the polyethylene glycol (A) and the ester (B) are present on the surface of the expandable vinyl resin particles. 3. The resin particles according to claim 1, wherein the polyethylene glycol (A) has a hydroxyl group equivalent of 200 to 600. 4. The resin particle according to claim 1, wherein the sorbitan fatty acid ester has a hydroxyl group equivalent of 55 to 500. 5. The resin particles according to claim 1, wherein glycerin fatty acid ester (C) is used in combination with sorbitan fatty acid ester. 6. The resin particles according to claim 5, wherein the glycerin fatty acid ester (C) is one or more selected from the group consisting of monoglycerides, diglycerides and triglycerides of fatty acids having 8 to 22 carbon atoms. 7. The resin particles according to any one of claims 1 to 6, wherein the added amount of polyethylene glycol (A) is 50 to 2000 ppm with respect to the entire resin particles. 8. The amount of ester (B) added is 50 to 500.
It is 0 ppm, The resin particle of any one of Claims 1-7. 9. The resin particles according to claim 5, wherein the added amount of glycerin fatty acid ester (C) is 50 to 5000 ppm. 10. The melting point of the ester (B) is 40 to 80 ° C.
The resin particles according to claim 1, which is