JPH11322995A - Expandable thermoplastic resin particle and pre-expanded particle and expansion molded article using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an expansion molded article excellent in prevention of leaching of fatty matter and a surfactant aqueous solution to the outside and reduce expansion molding times by coating an expandable thermoplastic resin particle with a fluorine-containing block copolymer together with a fusion accelerator or making the expandable thermoplastic resin particle contain the fluorine-containing block copolymer together with the fusion accelerator. SOLUTION: A fluorine-containing block copolymer composed of a fluorine- containing vinyl-type polymer segment and a lipophilic vinyl-type polymer segment is used. The ratio of the fluorine-containing vinyl-type polymer segment to the lipophilic vinyl-type polymer segment is preferably 20/80-80/20 by weight. The fluorine-containing block copolymer is preferably coated or contained in an amount of 0.003-2 wt.% based on an expandable particle. A fusion accelerator includes, for example, fatty amides represented by R-CONH2 (wherein R is a 10-22C aliphatic hydrocarbon) or triglycerides of 7-22C fatty acids.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to expandable thermoplastic resin particles, and pre-expanded particles and foamed molded articles using the same. More specifically, the present invention relates to expandable thermoplastic resin particles obtained by coating or containing expandable thermoplastic resin particles with a specific fluorine-containing block copolymer and a fusion promoter, and pre-expanded particles using the same. The present invention relates to the foam molded article.

[0002] The expandable thermoplastic resin particles of the present invention are used as materials for various molded products. Foods and beverages containing fats and oils components, such as instant noodles, fried chicken, fat-containing foods, regular coffee, It is preferably used as a foam molding material for containers such as curries having high permeability to the foam molded article. In addition, it is also useful as a foam molding material such as a drain pan (dish) used for a home air conditioner, a container of a surfactant aqueous solution, or a portable ice box.

[0003]

2. Description of the Related Art Conventionally, foamable thermoplastic resin particles are obtained by impregnating, for example, polystyrene resin particles with a volatile aliphatic hydrocarbon, such as n-pentane, which slightly swells them in an aqueous suspension. Or, in an aqueous suspension containing a small amount of a solvent such as toluene or cyclohexane having solubility for polystyrene resin particles, produced by a method of impregnating a polystyrene resin particle with a blowing agent such as butane at a normal temperature and propane at room temperature. You.

The expandable thermoplastic resin particles thus obtained are pre-expanded to obtain pre-expanded particles. Next, after filling the pre-expanded particles into a mold of a molding machine,
If steam is injected and heated to a temperature equal to or higher than the softening point of the pre-expanded particles, the respective pre-expanded particles are fused and integrated to obtain a molded product according to a mold. However, since the particles in the obtained molded body are not completely fused and integrated, for example, when the molded body is used as a container, depending on the contents to be stored, the components of the contents may be the outer wall of the container or the inside of the molded body. May penetrate into To prevent this penetration,
In the past, methods for reducing the surface energy of the individual particles constituting the molded body, that is, methods for increasing the contact angle of the surface of the molded body with respect to permeating contents have been proposed.

For example, Japanese Patent Publication No. 4-53890 discloses a random, block or graft copolymer of a fluorine-containing vinyl type monomer and a hydrophilic vinyl type monomer. Surface coating of perfluoroalkylsulfonamide with ammonium phosphate. JP-A-3-190941 discloses that a fluorine-containing vinyl monomer containing a hydrophilic component (ethylene oxide group or propylene oxide group) and a lipophilic monomer are used. And the like, and surface coating with a random copolymer has been proposed. The surface modifiers described in these publications are all fluorine-based surface modifiers containing a hydrophilic component or a hydrophilic group.

[0006]

However, even if a hydrophilic component or a fluorine-based surface modifier containing a hydrophilic group is used, the ability to prevent permeation of the oil or fat component and the aqueous solution of the surfactant and the pre-foaming property are not improved. It was not always satisfactory in terms of stickiness generated during particle transport. First, the permeation prevention performance will be described. Containers molded from expandable thermoplastic resin particles have a wide range of uses as described above due to their economical efficiency, heat retention, etc., for example, containers containing oily foods such as instant noodles and fried chicken. in use. In this case, there is a problem in that the stored items in the distribution inventory are affected by the temperature and humidity, and the oil and the soup ooze out to the outer wall of the cup. Further, when a surfactant aqueous solution having a low surface tension is used as the content, there is a problem that the content permeates the container in a short time. Although the above-mentioned proposals have been made as a countermeasure for these measures, the shielding properties were not sufficient by any of the proposals.

Next, the problem of stickiness will be described.
The hydrophilic component or hydrophilic group is introduced to prevent oil leakage, but there is a problem that the hydrophilic component in the surface modifier absorbs water and makes the particle surface sticky. When such particles are pre-expanded, the particles after pre-expansion tend to be sticky and the fluidity tends to deteriorate. Therefore, there was a problem that particles stayed on a net used for removing coalesced particles at the time of prefoaming and did not pass, and a problem that it took time to transport particles in a particle transfer pipe.

As described above, even if a conventional hydrophilic component or a fluorine-based surface modifier containing a hydrophilic group is used, the anti-permeation property to oil and fat components and aqueous surfactant solution, the stickiness during pre-foaming, The molding time was not always satisfactory. Therefore, for example, it is known to coat or contain a fatty acid amide or a fatty acid triglyceride for the purpose of improving the fusion of particles (Japanese Patent Application Laid-Open No. SHO 53-53).
-64277, JP-B-42-7715, JP-B-47
In this method, although the molding time can be shortened, there is a tendency that the permeation-preventing performance for fats and oils components and aqueous surfactant solutions is rather deteriorated.

On the other hand, it is necessary to increase the amount of a fluorine-based surface modifier in order to improve the performance of preventing penetration of an oil component or an aqueous solution of a surfactant, but this makes it difficult for the particles to fuse during molding and shortens the molding time. There is a problem of prolonging. As described above, the shortening of the molding time and the improvement of the permeation preventing performance for the oil and fat component and the aqueous solution of the surfactant had a conflicting relationship.

[0010]

Means for Solving the Problems The inventors of the present invention provide:
A fluorinated block composed of a fluorinated vinyl type polymer segment derived from a fluorinated vinyl type monomer and a lipophilic vinyl type polymer segment derived from a lipophilic vinyl type monomer is added to the expandable thermoplastic resin particles. By coating or containing the polymer, the fluorinated vinyl polymer segment in the fluorinated block copolymer effectively prevents the penetration of oils and fats and aqueous surfactant solutions, and furthermore, the lipophilic vinyl polymer segment Has significantly reduced the stickiness of the particles and found that expandable thermoplastic resin particles which maintain stable performance for a long period of time can be obtained.

As a result of further studies, it was found that the foamable thermoplastic resin particles were coated or contained with the above-mentioned fluorinated block copolymer and a fusion promoter to prevent penetration into oil and fat components and aqueous surfactant solutions. The present inventors have found that the molding time can be reduced without deteriorating the performance, and that the tackiness at the time of preliminary foaming can be improved, and the present invention has been completed.

Thus, according to the present invention, the expandable thermoplastic resin particles are provided with the fluorinated vinyl polymer segment derived from the fluorinated vinyl monomer and the lipophilic vinyl type polymer derived from the lipophilic vinyl monomer. Provided are foamable thermoplastic resin particles obtained by coating or containing a fluorine-containing block copolymer composed of a united segment and a fusion promoter, and foamed particles and foamed molded articles obtained therefrom.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in more detail. The expandable thermoplastic resin particles of the present invention are coated or contain a fluorinated block copolymer composed of a fluorinated vinyl polymer segment and a lipophilic vinyl polymer segment and a fusion promoter.

In the present invention, the thermoplastic resin serving as the base material of the expandable thermoplastic resin particles is not particularly limited as long as it is a resin which can be foamed with an inorganic or organic foaming agent. Polystyrene, styrene- (meth) acrylic acid copolymer, styrene-methyl (meth) acrylate copolymer, styrene-maleic anhydride copolymer, aromatic vinyl resin such as AS resin, methacrylic ester resin, Olefin homopolymers and copolymer resins such as vinylidene chloride resin, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, etc., polyphenylene ether and a single resin such as a mixed resin of polyphenylene ether and polystyrene or a mixture thereof, or a polyolefin Vinyl monomer is graft copolymerized in part of If resins. Of these, aromatic vinyl resins and polyolefin resins are preferred, and polystyrene resins are particularly preferred.

The expandable thermoplastic resin particles are prepared by using the above-mentioned resin as a base material and a blowing agent such as an aliphatic hydrocarbon such as propane, n-butane, isobutane, n-pentane, isopentane or cyclopentane, or freon. 11, a freon compound such as Freon 12, carbon dioxide, a foaming agent which is a liquid or gas at room temperature such as an inorganic compound such as nitrogen,
One or more, two to two thermoplastic resin particles
It was impregnated with 20% by weight. Known methods can be used for impregnation of the foaming agent. For example, a method of impregnating the thermoplastic resin particles in an autoclave as an aqueous suspension of the foaming agent can be mentioned.

If desired, ordinary additives such as a flame retardant, a colorant, and a solvent (eg, toluene, cyclohexane, ethylbenzene, etc.) may be added to these expandable thermoplastic resin particles as long as the effects of the present invention are not impaired. You may. Examples of the fluorinated vinyl-type monomer constituting the fluorinated vinyl-type polymer segment of the present invention include those represented by the following general formulas (A) to (G). However, two or more kinds may be used in combination. General formula (A): General formula (B): General formula (C): General formula (D): General formula (E): General formula (F): General formula (G): (Wherein, Rf is a polyfluoroalkyl group or a polyfluoroalkenyl group having 3 to 21 carbon atoms, R ₁ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ₂ is a carbon atom having 1 to 1 carbon atoms.
0 alkylene group, R ₃ is hydrogen atom or methyl group, A
r is an arylene group which may have a substituent) In the above general formula, examples of the polyfluoroalkyl group for Rf include propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, Tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl,
A group in which a desired number of hydrogen atoms constituting icosyl, henicosyl, and the like are substituted with fluorine atoms. Usually, a perfluoroalkyl group is preferred.

The polyfluoroalkenyl group for Rf includes propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl, nonadecenyl A group in which a desired number of hydrogen atoms constituting henicosenyl or the like are substituted with fluorine atoms is exemplified. Usually, a perfluoroalkenyl group is preferred.

The above-mentioned polyfluoroalkyl group or polyfluoroalkenyl group preferably has 6 to 10 carbon atoms. When a monomer having 2 or less carbon atoms is used, the fluorinated block copolymer obtained therefrom is difficult to exhibit permeation-preventing properties for oils and fats and aqueous surfactant solutions, and when the number of carbon atoms exceeds 22, the chain is considerably long. Therefore, the polymerization conversion rate to the fluorine-containing block copolymer decreases, which is not preferable.

In the above general formula, the alkyl group for R ₁ includes methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl,
Isopropyl, isobutyl, isopentyl, isohexyl, isooctyl, isononyl and the like. Among these alkyl groups, an alkyl group having 1 to 4 carbon atoms is preferable. If the number of carbon atoms exceeds 10, it is not preferable because the chain becomes long and the polymerization conversion rate decreases.

In the above general formula, the alkylene group for R ₂ includes methylene, ethylene, trimethylene, 2-
Examples include methyltrimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene and the like. Among these alkylene groups, an alkylene group having 1 to 4 carbon atoms is preferable. If the number of carbon atoms exceeds 10, the chain becomes long and the polymerization conversion rate is undesirably reduced.

In the above general formula, examples of the arylene group of Ar include phenylene and naphthylene. These arylene groups may have a substituent, and examples of such a substituent include a hydroxy group. Preferred arylene groups include phenylene, hydroxyphenylene and the like. Specific examples of the fluorine-containing vinyl-type monomer represented by the general formulas (A) to (G) include the following. 1) a group of the general formula _{(A): F (CF 2} ) 6 (CH 2) 2 OCOCH = CH 2 (a-1) F (CF 2) 8 (CH 2) 2 OCOCH = CH 2 (a-2) _{F (CF 2) 10 (CH} 2) 2 OCOCH = CH 2 (a-3) H (CF 2) 8 CH 2 OCOCH = CH 2 (a-4) (CF 3) 2 CF (CF 2) 6 (CH _{2) 2 OCOCH = CH 2 (} a-5) (CF 3) 2 CF (CF 2) 8 (CH 2) 2 OCOCH = CH 2 (a-6) F (CF 2) 6 (CH 2) 2 OCOC ( _{CH 3) = CH 2 (a} -7) F (CF 2) 8 (CH 2) 2 OCOC (CH 3) = CH 2 (a-8) F (CF 2) 10 (CH 2) 2 OCOC (CH 3 _{) = CH 2 (a-9} ) H (CF 2) 8 CH 2 OCOC (CH 3) = CH 2 (a-10) (CF 3) 2 CF (CF 2) 6 (CH 2) 2 OCOC _{CH 3) = CH 2 (a} -11) (CF 3) 2 CF (CF 2) 8 (CH 2) 2 OCOC (CH 3) = CH 2 (a-12) 2) a group of the general formula (B): _{F (CF 2) 8 SO 2} N (CH 3) CH 2 CH 2 OCOCH = CH 2 (b-1) F (CF 2) 8 SO 2 N (CH 3) (CH 2) 4 OCOCH = CH 2 (b _{-2) F (CF 2) 8} SO 2 N (CH 3) (CH 2) 10 OCOCH = CH 2 (b-3) F (CF 2) 3 SO 2 N (C 2 H 5) C - (*) _{(*) - (CH 2 CH} 3) HCH 2 OCOCH = CH 2 (b-4) F (CF 2) 8 SO 2 N (CH 3) CH 2 CH 2 OCOC (CH 3) = CH 2 (b-5 _{) F (CF 2) 3 SO} 2 N (C 2 H 5) CH 2 CH 2 OCOC (CH 3) = CH 2 (b-6) F (CF 2) 3 SO 2 N (C 3 H 7) CH 2 CH ₂ OCO _{(CH 3) = CH 2 (} b-7) 3) group of the general formula _{(C): F (CF 2} ) 2 CON (C 2 H 5) CH 2 OCOCH = CH 2 (c-1) F (CF 2 ) ₃ CON (CH ₃ ) CH (CH ₃ ) CH ₂ OCOCH ＝ CH ₂ (c-2) F (CF ₂ ) ₈ CON (CH ₂ CH ₂ CH ₃ )-(*) (*)-CH ₂ CH _{2 OCOC (CH 3) = CH 2} (c-3) F (CF 2) 8 CON (C 2 H 5) CH 2 OCOC (CH 3) = CH 2 (c-4) 4) general formula group (D) _{: F (CF 2) 8 CH} 2 CH (OH) CH 2 OCOCH = CH 2 (d-1) (CF 3) 2 CF (CF 2) 2 CH 2 -CH (OH) CH 2 OCOCH = CH 2 (d _{-2) F (CF 2) 8} CH 2 CH (OH) CH 2 OCOC (CH 3) = CH 2 (d-3) (CF 3) 2 CF (CF 2) 2 CH 2 - (* (*) - group of _{CH (OH) CH 2 OCOC (} CH 3) = CH 2 (d-4) 5) the general formula _{(E): (CF 3)} 2 CF (CH 2) 6 CH 2 - (*) _{(*) - CH (OCOCH 3} ) CH 2 OCOCH = CH 2 (e-1) (CF 3) 2 CF (CH 2) 6 CH 2 - (*) (*) - CH (OCOCH 3) CH 3 OCOC ( CH ₃ ) = CH ₂ (e-2) 6) Group of general formula (F):

[0022]

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7) Group of general formula (G): F (CF ₂ ) ₈ (CH ₂ ) ₂ OCOCH ₂ | F (CF ₂ ) ₈ (CH ₂ ) ₂ OCOC = CH ₂ (g-1) (A) As the monomers other than the fluorine-containing vinyl monomers of (G) to (G), for example, the following fluorine-containing vinyl monomers are also used. F (CF ₂ ) ₆ CH ₂ OCHＣＨCH ₂ F (CF ₂ ) ₈ CH ₂ OCH ＝ CH ₂ F (CF ₂ ) ₁₀ CH ₂ OCH ＝ CH ₂ F (CF ₂ ) ₆ CH ₂ OCF = CF ₂ F ( _{CF 2) 8 CH 2 OCF =} CF 2 F (CF 2) 10 CH 2 OCF = CF 2 F (CF 2) 6 CH = CH 2 F (CF 2) 8 CH = CH 2 F (CF 2) 10 CH = CH ₂ F (CF ₂ ) ₆ CF = CF ₂ F (CF ₂ ) ₈ CF = CF ₂ F (CF ₂ ) ₁₀ CF = CF ₂ CH ₂ = CF ₂ CF ₂ = CF ₂ These fluorine-containing vinyl single units The body may be used alone or in combination.

Of all the above-mentioned fluorine-containing vinyl monomers, the monomer represented by the general formula (A) is preferred because of its high polymerization conversion. In the monomers of the general formulas (B), (C) and (D), a hydrophilic component (for example, a sulfonamide group in the general formula (B), an amide group in the general formula (C), Since a hydroxy group is present in the formula (D),
The obtained expandable thermoplastic resin particles may be slightly sticky. Further, the polymerization conversion rate is higher for the monomer represented by the general formula (A) than for other monomers, and particularly preferable monomers are (a-2), (a-8), and (a). -11) and (a-12).

Further, monomers other than the fluorine-containing vinyl-type monomers represented by the general formulas (A) to (G) (for example, HEMA : 2-hydroxyethyl methacrylate,
MMA: methyl methacrylate, SMA: stearyl methacrylate, etc.) and the fluorinated vinyl monomers represented by the above (A) to (G) may be copolymerized. In this case, the amount of the monomer other than (A) to (G) is suitably 3% by weight or less in the fluorinated vinyl polymer segment.

The lipophilic vinyl polymer segment of the present invention is obtained from a lipophilic vinyl monomer. The lipophilic vinyl-type monomer means a lipophilic vinyl-type monomer containing no fluorine atom, and specifically has the following general formula (H): R ₄ —OCOCR ₅ ＣＨCH ₂ (R ₄ is C8-C22 alkyl group, C6-C15
Which may have a substituent, and R ₅ is a hydrogen atom or a methyl group). These monomers may be used alone or in combination.

In the above formula, examples of the alkyl group for R ₄ include octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, henicosyl, docosyl and the like. . Examples of the cycloalkyl group include cyclohexyl, cycloheptyl, cyclooctyl and the like.

The alkyl group, cycloalkyl group and phenyl group of R ₄ may each have a substituent,
Examples of such a substituent include a lower alkyl group having 1 to 3 carbon atoms and an aryl group such as phenyl. Specific examples of the monomer represented by the general formula (H) (hereinafter, acrylate and methacrylate are collectively abbreviated as (meth) acrylate) include:
2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate,
Decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, dodecyl (meth) acrylate, (meth)
Tridecyl acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, stearyl (meth) acrylate,
Behenyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate and the like.

Among the above-mentioned lipophilic vinyl-type monomers, those which do not particularly cause stickiness of the particles and which do not lower the water / oil leakage preventing performance of the fluorine-containing vinyl polymer segment include (meth) Lauryl acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate,
Examples include stearyl (meth) acrylate and behenyl (meth) acrylate.

In the present invention, it is preferable to form a fluorine-containing block copolymer by using a lipophilic vinyl polymer segment obtained from these lipophilic vinyl monomers. Further, a lipophilic vinyl polymer segment can be obtained using a monomer other than the lipophilic vinyl monomer. Such monomers include those represented by the general formula (I) Wherein R ₆ is an alkylene group having 1 to 4 carbon atoms which may have a substituent, and R ₇ is a hydrogen atom or a methyl group.

Specific examples of the monomer represented by the general formula (I) include monomers represented by the following formulas (i-1) to (i-6). The amount of such a monomer other than the lipophilic vinyl-type monomer is suitably 3% by weight or less in the lipophilic vinyl-type polymer segment.

By using a monomer obtained by copolymerizing the monomer of the general formula (I) with a lipophilic vinyl type monomer, it is possible to prevent corrosion occurring in a mold at the time of foam molding. The monomer of I) is considered to contribute to the metal corrosion preventing effect of the obtained fluorinated block copolymer. The ratio of the fluorinated vinyl polymer segment to the lipophilic vinyl polymer segment in the fluorinated block copolymer in the present invention is from 20/80 to 80 / by weight.
It is preferably 20 and more preferably 50/50 to 70/30. When the content of the fluorine-containing vinyl polymer segment is less than 20% by weight, the arrangement of the alkyl group substituted with the fluorine atom on the surface of the resin particles is insufficient, and the leakage prevention of the oil and fat component and the aqueous solution of the surfactant tends to be insufficient. It is not preferable. On the other hand, if the content of the fluorine-containing vinyl polymer segment exceeds 80% by weight, it becomes difficult to uniformly coat the surface of the expandable thermoplastic resin particles with the fluorine-containing block copolymer. In the process, the fluorine-containing block copolymer does not reach the whole molded product, and it is difficult to sufficiently exert the effect of the present invention, which is not preferable.

The molecular weight range of the fluorinated block copolymer is determined by using a gel permeation chromatography (GPC) apparatus HLC-8020 manufactured by Tosoh Corporation and using tetrahydrofuran (THF) as a solvent in terms of polystyrene. Molecular weight 3000 to 30000
0 is suitable, usually 10,000 to 50,000
Are used. Weight average molecular weight 3000
If it is less than 3, sufficient oil repellency is not exhibited, and conversely, 300
If it exceeds 000, the viscosity is increased, and the film forming property and impregnation property on the surface of the expandable thermoplastic resin particles are undesirably reduced.

Next, a method for producing a fluorine-containing block copolymer will be described. Fluorine-containing block copolymer, for example,
One or two or more types of lipophilic vinyl monomers are polymerized using a polymeric peroxide as a polymerization initiator to obtain a peroxy bond-containing polymer. The obtained peroxy bond-containing polymer is used as a polymerization initiator to polymerize a fluorine-containing vinyl monomer mixture containing one or more fluorine-containing vinyl monomers. As such a polymerization method, a known production method (for example, described in Japanese Patent Publication No. 5-41668 and Japanese Patent Publication No. 5-59942) can be applied.

The polymeric peroxide used in producing the above-mentioned fluorine-containing block copolymer is a compound having two or more peroxy bonds in one molecule. As the polymeric peroxide, Japanese Patent Publication No. 5-59942
Various polymeric peroxides described in Japanese Patent Application Laid-Open No. H10-208 can be similarly used in the present invention. Also,
Polymeric peroxides may be used alone or in combination of two or more.

As the polymeric peroxide, for example, those represented by the following general formulas (1) to (3) can be used. General formula (1): General formula (2): General formula (3): (Wherein, n is an integer of 2 to 20) The fluorinated block copolymer is easily prepared by a solution polymerization method, a bulk polymerization method, a suspension polymerization method, or an emulsion polymerization method using the above-mentioned polymeric peroxide. can get.

In the case of the solution polymerization method, a case where a lipophilic vinyl polymer segment is formed in the first step and a fluorine-containing vinyl polymer segment is formed in the second step as the fluorine-containing block copolymer in the present invention is exemplified. Then, the following can be explained. That is, first, a polymeric peroxide is used as a polymerization initiator, and the lipophilic vinyl-type monomer forming the lipophilic vinyl-type polymer segment is polymerized in a solution (organic solvent or the like), whereby a peroxy bond is formed in the chain. A lipophilic vinyl-type polymer containing a peroxy bond is obtained. Next, in the second step,
When the polymerization is carried out by adding the fluorinated vinyl type monomer to the solution produced in the first step, the fluorinated block copolymer is efficiently cleaved at the peroxy bond in the peroxy bond-containing lipophilic vinyl type polymer. Can be

In the above two-stage polymerization,
The lipophilic vinyl-type monomer of the first step may be used in the second step, and the fluorinated vinyl-type monomer of the second step may be used in the first step. The amount of the polymeric peroxide used in the first step of the production of the fluorinated block copolymer in the present invention is usually 0.5 to 20 parts by weight based on 100 parts by weight of the lipophilic vinyl type monomer or the fluorinated vinyl type monomer. And the polymerization temperature at that time is 40 to 130 ° C., and the polymerization time is about 2 to 12 hours. Further, the polymerization temperature in the second step is usually 40 to 140 ° C., and the polymerization time is about 3 to 15 hours.

The obtained fluorinated block copolymer is used by dissolving or dispersing it in the following organic solvent or by adding a surfactant or the like and dispersing it in water to form an emulsion solution. And can also be used in finely divided form. The organic solvent is not particularly limited as long as it is an organic solvent capable of dissolving or dispersing the fluorinated block copolymer. For example, methanol, ethanol, propanol, 2-propyl alcohol, 1-butyl alcohol, 2-butyl alcohol, 2-methyl-1
-Propanol, 2-methyl-2-propanol, 1-
Pentanol, 2-pentanol, 3-pentanol,
Cyclopentanol, 2-hexanol, 3-hexanol, cyclohexanol, methyl cellosolve, ethyl cellosolve, acetone, 2-butanone, 3-methyl-2
-Butanone, 2-pentanone, 3-pentanone, 2-methyl-3-pentanone, 3-methyl-2-pentanone,
4-methyl-2-pentanone, 2,4-dimethyl-3-
Pentanone, 4,4-dimethyl-2-pentanone, 2-
Hexanone, 3-hexanone, cyclopentanone, cyclohexanone, 2-heptanone, 3-heptanone, 4-
Heptanone, 2-methyl-3-hexanone, 5-methyl-2-hexanone, 5-methyl-3-hexanone, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, trimethyl methyl acetate, isobutyl acetate, acetic acid sec -Butyl, pentyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, isobutyl propionate, tert-butyl propionate, isobutyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, isopropyl butyrate , Methyl isobutyrate, ethyl isobutyrate, methyl 2-methyl-butyrate, methyl caproate, benzene, toluene, ethylbenzene, xylene, cyclohexane, hexane, isohexane, isohexene, heptane, octane, iso Octane, nonane, isononanoic,
Decane, undecane, dodecane, tridecane, isoparaffin-based solvent (manufactured by NOF Corporation: NAS-3, NAS-
4, NAS-5H), formamide, acetamide, dimethylformamide, dimethylacetamide, acetonitrile, tetrahydrofuran, 1,1,2, -trifluoro-1,2,2-trichloroethane, tetrachlorodifluoroethane, methylchloroform, hexafluoroisopropanol, (Meth) para-xylene hexafluoride, perfluorohexane, perfluoroheptane and the like can be mentioned. These organic solvents can be used alone or in combination of two or more.

Among these organic solvents, particularly preferred solvents for dissolving or dispersing the fluorine-containing block copolymer include hexane, isohexane, isohexene, heptane, octane, isooctane, nonane, isononane, decane and undecane. , Dodecane, tridecane, isoparaffin-based solvents (NAS-3, manufactured by NOF Corporation) and the like.

The fluorine-containing block copolymer according to the present invention is diluted with the above-mentioned organic solvent or the like, and is coated or contained in the expandable thermoplastic resin particles. As a method,
For example, a method of coating the resin particle surface by sufficiently mixing with a mixer such as a ribbon blender, a V blender, a Hensiel mixer, a Reedige mixer or the like, or a method of impregnating a resin particle with a fluorine-containing block when impregnating a foaming agent. There is a method in which a polymer is added and contained in the surface layer of the resin particles.

When the fluorinated block copolymer is used as a powder, liquid polyethylene glycol,
A spreading agent such as liquid polybutene may be previously coated on the surface of the expandable thermoplastic resin particles, and then a powdery fluorine-containing block polymer may be coated. In the present invention,
The fluorinated block copolymer is preferably coated in an amount of 0.003 to 2% by weight based on the expandable thermoplastic resin particles, or is contained in the resin particles, and more preferably 0.003 to 2% by weight.
5 to 0.5% by weight. If the amount to be coated or contained is less than 0.003% by weight, it is difficult to obtain a sufficient effect for preventing the penetration of oils and fats or an aqueous solution of a surfactant. It is not preferred because it tends to inhibit.

In this coating, a conventionally known coating component may be used in addition to the fluorine-containing block copolymer. Examples of such a coating component include zinc, magnesium, calcium, and aluminum salts of higher fatty acids such as stearic acid, lauric acid, and myristic acid. Of these, zinc stearate is particularly preferable. . The higher fatty acid metal salt exhibits the effect of preventing agglomeration during prefoaming, releasing from the molding die, improving the slipperiness of the molded product, and preventing the penetration of contents in food containers and the like.

When the fluorinated block copolymer and the higher fatty acid metal salt are used in combination, the amount of the higher fatty acid metal salt to be used is 0.05 to 0.5 with respect to the expandable thermoplastic resin particles.
%, Preferably 0.05 to 0.35% by weight.
A feature of the present invention is that the foam molded from the expandable thermoplastic resin particles exhibits an anti-permeation property for an oil or fat component or an aqueous solution of a surfactant, and does not hinder fusion during molding of the resin particles. This effect is due to the arrangement of perfluoroalkyl groups in the fluorinated block copolymer, particularly the uniform arrangement of the CF ₃ groups on the surface of the expandable resin particles, which results in a remarkable decrease in surface energy and imparts water and oil repellency. It is thought to be.

Examples of the fusion promoter used in the present invention include, for example, a compound represented by the general formula R-CONH ₂ (R has 10 to 10 carbon atoms).
Fatty acid amides represented by 22 saturated or unsaturated aliphatic hydrocarbons) or triglycerides of fatty acids having 7 to 22 carbon atoms. In the above general formula, examples of the aliphatic hydrocarbon represented by R include lauryl and stearyl.

Specific examples of the fatty acid amide represented by the above general formula include lauric amide, oleic amide, erucic amide, palmitic amide, and stearic amide. Also, amidated natural fatty acids such as rice bran oil amide and hardened beef oil amide are included. These fatty acid amides may be used alone or in combination of two or more.

As the triglyceride of a fatty acid having 7 to 22 carbon atoms, a triglyceride of a fatty acid synthesized by an esterification reaction of glycerin and various fatty acids, a natural triglyceride, and the like can be used. For example, triglyceride stearate, triglyceride palmitate, triglyceride myristic, triglyceride behenate,
Lauric triglyceride, hydroxystearic triglyceride and the like. Examples of natural triglycerides include hardened soybean oil, hardened tallow oil, hardened rapeseed oil, hardened coconut oil, hardened castor oil, and the like.

These triglycerides may be used alone or in combination of two or more. Further, a fatty acid amide and a fatty acid triglyceride as a fusion promoter may be used in combination. The amount of the fusion promoter of the present invention is:
Depending on the type, for example, in the case of fatty acid amide, 0.002 to 0.
It is used in an amount of 2% by weight, preferably 0.005 to 0.1% by weight. If it is less than 0.002% by weight, the effect of promoting fusion is hardly obtained, and if it exceeds 0.2% by weight, the amount of the fluorinated block copolymer increases, which is not preferable because the cost increases.

The proportion of the fatty acid triglyceride used is 0.002 to 0.5 with respect to the expandable thermoplastic resin particles.
It is 5% by weight, preferably 0.05 to 0.1% by weight.
If it is less than 0.002% by weight, it is difficult to obtain a fusion promoting effect,
If the amount exceeds 0.5% by weight, the amount of the fluorinated block copolymer increases, which is not preferable because the cost increases. In the present invention, the ratio of the fluorine-containing block copolymer and the fatty acid amide or fatty acid triglyceride used as a fusion promoter preferably satisfies the following expression.

15b ≧ a ≧ b 5c ≧ a ≧ c (a is a fluorine-containing block copolymer, b is a fatty acid amide,
c means the weight of the fatty acid triglyceride, respectively) When a exceeds 15b or 5c, the fusion inhibiting effect is larger than the fusion promoting effect, which is not preferable. A is b
If it is less than c, it is difficult to obtain a sufficient effect for preventing penetration of oils and fats and aqueous surfactant solution.

The expandable thermoplastic resin particles can be prepared by a known method,
For example, pre-expanded particles can be obtained by heating using steam in a rotary stirring type pre-expansion apparatus. The pre-expanded particles can be formed into a foamed molded article by filling the foamable thermoplastic resin particles into a mold having a desired shape in a known manner, and heating the steamed particles using steam or the like.

The foamed molded articles such as food containers and food containers formed from the foamable thermoplastic resin particles of the present invention include vegetable oils such as beef tallow, soybean oil and rapeseed oil, lard and instant noodles. , Stew, mayonnaise, dressing sauce, curry roux, butter, margarine, white sauce, yogurt, ice cream, donut, hamburger, fried chicken, etc. Even so, it is possible to suppress permeation of oils, fats, aqueous solutions, dyes, or the like from the space between the foamed particles to the outside for a long time. Therefore, the range of use can be expanded to applications that could not be used conventionally.

Similarly, the commercial value of surfactant containers, household air conditioner drain pans, portable simple ice boxes, fresh fish boxes and the like can be improved.
Further, the foamed molded article of the present invention is manufactured in a short heating time, and the productivity is also improved. Hereinafter, the present invention will be described in more detail with reference to examples.

[0054]

EXAMPLES Example 1 [Synthesis Example of Fluorine-Containing Block Copolymer] 5 equipped with a thermometer, a drop float, a nitrogen gas inlet tube and a stirrer
After introducing nitrogen gas into a 00 ml four-necked flask, 175 ml of isoparaffin (NAS-3, manufactured by NOF Corporation) was added.
g and heated to 70 ° C. Thereafter, a mixture of 39 g of stearyl methacrylate as a lipophilic vinyl-type monomer, 5 g of a polymeric peroxide represented by the general formula (1), and 50 g of isoparaffin was dropped over 2 hours. Thereafter, the reaction was continued at 70 ° C. for 4 hours. Then, the formula (a-
58.5 g of the fluorinated vinyl monomer of 2) was added dropwise over 1 hour. Thereafter, the reaction was performed at 70 ° C. for 5 hours.

30% by weight of the isoparaffin solution is a fluorinated block copolymer, and the obtained fluorinated block copolymer has 6 fluorinated vinyl polymer segments.
At 0% by weight, the lipophilic vinyl polymer segment consisted of 40% by weight.

[Production Example of Foam Molded Article]
0.3 mm diameter containing 5% by weight n-pentane
1000 g of 0.5 mm expandable polystyrene resin particles
And 0.8 g of an isoparaffin solution of the above-mentioned fluorinated block copolymer (0.24 g of pure content, 0.024% by weight based on expandable polystyrene resin particles) and a fatty acid amide as a fusion promoter: trade name: fatty acid amide T 0.05 g (manufactured by Kao Corporation) (0.005% by weight based on expandable polystyrene resin particles) and 0.2 g of polyethylene glycol
And 2.3 g of zinc stearate were added to a Henschel mixer and stirred to obtain expandable polystyrene resin particles whose surface was coated with the copolymer and the fatty acid amide. The whole was uniformly heated in a normal atmosphere saturated steam at about 90 ° C. by a rotary stirring type prefoaming apparatus, and foamed for 5 minutes so that the bulk volume became 100 g / l, to obtain prefoamed particles. A stickiness test was performed on the pre-expanded particles immediately after the expansion.

After aging and drying the pre-expanded particles in a thermostatic chamber at 30 ° C. for 6 hours, the pre-expanded particles are filled in a cup-shaped mold having an inner volume of 500 cc and a thickness of 2 mm, and steam of 2.0 kg / cm ^2. After heating for 4 seconds, 5 seconds or 6 seconds and cooling, a polystyrene resin foam molded article molded by a mold was obtained. A fusion test, a fat and oil penetration test and a surfactant aqueous solution penetration test were performed on the foamed molded article. Table 5 shows the results.

[Fusion Test] The cup-shaped foamed product was cracked by hand, and the fusion status of the fractured surface was visually judged. That is,
When the expanded particles themselves are broken, it is considered to be fused,
When the foamed particles were peeled off on the surface, it was judged that they were not fused. Table 1 shows the evaluation criteria.

[0059]

[Table 1]

The interface fusion ratio is represented by the following equation.

[Oil Permeation Test] A seasoning containing curry powder used for instant noodles and oysters are put into a cup for about 8 minutes, and then the whole cup is wrapped with a stretched polypropylene resin film and sealed. After being left in the oven for 48 hours, the oil and fat content of the curry powder and the state of leakage of the yellow pigment to the outside of the cup were evaluated. Table 2 shows the evaluation criteria.

[0062]

[Table 2]

[Permeation test of surfactant aqueous solution] Nonionic surfactant (Kao Emulgen 810) was added to 1 liter of water.
A colored liquid in which 0 g and 0.05 g of eriochrome black T were dissolved and dispersed was put in a cup, allowed to stand at room temperature for 1 hour, and the state of leakage of the surfactant to the outer surface of the cup was visually evaluated. Table 3 shows the evaluation criteria.

[0064]

[Table 3]

[Stickness Test] The pre-expanded particles immediately after pre-expansion were placed in a cylindrical container having a diameter of 80 mm and a height of 70 mm, and the diameter D of a mountain formed when the container was raised was measured and evaluated. Table 4 shows the evaluation criteria.

[0066]

[Table 4]

[0067]

Examples 2 to 5 and Comparative Examples 1 to 3 The same procedures as in Example 1 were carried out except that the composition and amount of the fluorine-containing block copolymer and the fusion promoter were changed as shown in Table 5. Table 5 shows the results.

[0068]

[Table 5]

As shown in Table 5, when the expandable resin particles of the present invention are used, a foam molded article can be produced in a heating time of only 4 seconds. In addition, good effects can be obtained on the permeation prevention properties and tackiness of the oil / fat / surfactant aqueous solution.

[0070]

The expandable thermoplastic resin particles of the present invention are:
The expandable thermoplastic resin particles contain a fluorovinyl polymer segment formed from a fluorovinyl monomer and a lipophilic vinyl polymer segment formed from a lipophilic vinyl monomer. By coating or containing the fluorine block copolymer and the fusion promoter, it is possible to obtain a foamed molded article excellent in preventing leaching of oils and fats and an aqueous surfactant solution to the outside, and to mold the foamed molded article. Time can be shortened, and productivity is improved.

Further, when the expandable thermoplastic resin particles are pre-expanded to an arbitrary density, the stickiness of the pre-expanded particles is suppressed, and the transport time of the pre-expanded particles and the drying time of the pre-expanded particles can be reduced. And improve productivity.

Claims (5)

[Claims] 1. An expandable thermoplastic resin particle comprising a fluorovinyl polymer segment derived from a fluorovinyl monomer and a lipophilic vinyl polymer segment derived from a lipophilic vinyl monomer. Foamable thermoplastic resin particles, characterized by being coated or contained with a fluorine-containing block copolymer and a fusion promoter. 2. The fusion promoter of the general formula R-CONH
The expandable thermoplastic resin particles according to claim 1, wherein 2 is a fatty acid amide represented by ₂ (R is a saturated or unsaturated aliphatic hydrocarbon having 10 to 22 carbon atoms). 3. The expandable thermoplastic resin particles according to claim 1, wherein the fusion promoter is a triglyceride of a fatty acid having 7 to 22 carbon atoms. 4. Pre-expanded particles obtained by pre-expanding the expandable thermoplastic resin particles according to claim 1. 5. A foam molded article obtained by foam molding the pre-expanded particles according to claim 4.