JPH0867760A - Pre-expanded polypropylene resin particles and method for producing the same - Google Patents

Abstract

(57) [Summary] [Object] To provide pre-expanded particles of a polypropylene resin which can be molded in a mold at a lower temperature. [Structure] Polypropylene resin and β crystal nucleating agent (however,
Pre-expanded particles of polypropylene resin composed of a quinacridone-based β crystal nucleating agent).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to polypropylene resin pre-expanded particles and a method for producing the same.

[0002]

2. Description of the Related Art Foams of polypropylene resin are useful as packaging materials, heat insulating materials, cushioning materials, core materials and the like, and are widely used. Such polypropylene-based resin foam can be manufactured by various methods. One of them is a method in which pre-expanded particles are once produced, and the pre-expanded particles are put in a desired mold and re-expanded by steam (in-mold). There is a molding method). Various methods have been carried out as a method for producing pre-expanded particles used for in-mold molding, for example, by adding a volatile foaming agent to polypropylene resin particles,
A method of heating and foaming (Japanese Patent Laid-Open No. 58-65734), a method of cutting a strand obtained by adding a blowing agent to polypropylene resin pellets, heating and melting, and then extruding and foaming (Japanese Patent Laid-Open No. 58-76230). Issue)
Are known.

However, especially propylene homopolymers and block copolymers of α-olefins having 2 or 4 to 10 carbon atoms and propylene (α-olefin content of about 20).
The melting peak temperature (DS) of the resin itself
Melting peak temperature measured in C. (Details will be described later), which is as high as about 160 ° C., and the melting peak temperature of the pre-expanded particles obtained therefrom is also about 160 ° C. or higher.

A random copolymer of α-olefin having 2 or 4 to 10 carbon atoms and propylene (α-olefin content up to about 10% by weight) has a lower melting peak temperature (about 130 to about 10% by weight) than the above homopolymer. 155 ° C),
Nevertheless, the melting peak temperature of polyethylene resin (about 10
It is higher than 0 to 130 ° C). And the pre-expanded particles obtained therefrom also have the same or higher melting peak temperature.

When the melting peak temperature of the pre-expanded particles is high, the heating temperature at the time of re-expansion in the production of the foamed molded product is naturally high. For example, in the in-mold forming method, the steam temperature must be increased, and therefore, the steam pressure also needs to be increased, a large amount of energy is required, and the mold clamping force of the molding machine must be increased.

Therefore, various attempts have been made to lower the melting peak temperature of the pre-expanded particles. One of the methods is to form β crystals of polypropylene in the pre-expanded particles.

[0007] Polypropylene is crystalline and becomes α crystal by a usual molding method. The melting peak temperature of the polypropylene resin is the melting peak temperature of the α crystal. By the way, β-crystals are formed by selecting molding conditions and cooling (curing) conditions. This β-crystal has a melting point temperature higher than that of α-crystal by 10
It has a low melting peak temperature around ℃, and by mixing β crystals, the heating temperature during the production of the foamed molded article can be lowered. The β crystal is usually produced by heating and melting a polypropylene resin containing a β crystal nucleating agent and then gradually cooling it.

As an attempt to form β crystals in the pre-expanded particles, Japanese Unexamined Patent Publication (Kokai) No. 3-252429 discloses that a non-crosslinked polypropylene-based resin is used in an amount of 0.00001-0. There is described a foamed particle containing 1 part by weight of a quinacridone compound as a β crystal nucleating agent. However, with these pre-expanded particles, only an improvement of slightly widening the width of the melting peak has been achieved,
It is still insufficient for the purpose of lowering the melting peak temperature. Further, there is also a problem that the quinacridone-based compound is colored red.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to lower the melting peak temperature of pre-expanded polypropylene resin particles and lower the heating temperature during foam molding of the final foam.

[0010]

The present invention relates to pre-expanded particles comprising a polypropylene resin and a β crystal nucleating agent (excluding a quinacridone type β crystal nucleating agent).

The present invention also relates to a polypropylene resin containing β
The present invention relates to a method for producing pre-expanded particles of polypropylene resin in which a crystal nucleating agent (excluding a quinacridone type β crystal nucleating agent) is mixed and then expanded.

As the β crystal nucleating agent for polypropylene resin, the above-mentioned quinacridone compound (JP-A-3-25242) is used.
No. 9), anilide compounds and amide compounds are known. In the present invention, the quinacridone compound is not used for the above-mentioned reason, that is, the melting peak temperature lowering effect is insufficient and coloring occurs.

Preferred β crystal nucleating agents include, for example, the following compounds.

(1) Dianilide compound (JP-A-5-25
(See Japanese Patent No. 5551) Adipic acid dianilide, suberic acid dianilide, or two of them.

(2) Diamide compound (I)
No. 310665 gazette) General formula (I): R < ¹ > -NHCO-X-CONH-R < ² > (I) (In formula, X is

[0016]

[Chemical 5]

R ¹ and R ² are the same or different and each is a cycloalkyl group having 5 to 12 carbon atoms).

Specifically, naphthalenedicarboxylic acid or biphenyldicarboxylic acid and a cycloalkyl monoamine such as cyclopentylamine, cyclohexylamine, cycloheptylamine, cyclooctylamine,
Reaction products with cyclododecylamine and the like,
In particular, N, N'-dicyclopentyl-2,6-naphthalenedicarboxamide, N, N'-dicyclohexyl-
2,6-naphthalene dicarboxamide, N, N'-dicyclooctyl-2,6-naphthalene dicarboxamide, N, N'-dicyclododecyl-2,6-naphthalene dicarboxamide, N, N'- Dicyclohexyl-
2,7-naphthalene dicarboxamide, N, N'-dicyclopentyl-4,4'-biphenyldicarboxamide, N, N'-dicyclohexyl-4,4'-biphenyldicarboxamide, N, N'-di Cyclooctyl-4,4'-biphenyldicarboxamide, N, N '
-Dicyclododecyl-4,4'-biphenyldicarboxamide, N, N'-dicyclohexyl-2,2'-biphenyldicarboxamide and the like are preferable.

(3) Diamide compound (II)
-107875 see JP) Formula ^{(II): R 4 -CONH-} R 3 -NHCO-R 5 (II) ( wherein, R ³ is an aliphatic diamine residue having 1 to 24 carbon atoms,
Alicyclic diamine residue having 6 to 21 carbon atoms or 6 to 12 carbon atoms
15 aromatic diamine residues, R ⁴ and R ⁵ are the same or different, and all are C 3-14 cycloalkyl groups, C 3-14 cycloalkenyl groups,

[0020]

[Chemical 6]

(Wherein R ⁶ and R ⁷ are each a hydrogen atom or a linear or branched alkyl or alkenyl group having 1 to 4 carbon atoms, and R ⁸ and R ⁹ are each 1 to 3 carbon atoms. Is a linear or branched alkylene group))).

Specific examples include reaction products of an aliphatic diamine, an alicyclic diamine or an aromatic diamine and a monocarboxylic acid.

Examples of the aliphatic diamine include compounds represented by the general formula: H ₂ N—R ¹⁰ —NH ₂ (wherein R ¹⁰ is a saturated or unsaturated alkylene group having 1 to 24 carbon atoms). Preferably, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,3-diaminopentane, 1,5-diaminopentane, 1,6-diaminohexane and the like are exemplified.

As the alicyclic diamine, for example, general formula: H ₂ N--R ¹¹ --NH ₂ [wherein R ¹¹ is

[0025]

[Chemical 7]

(However, R ¹² and R ¹³ are the same or different, each is an alkylene group having 1 to 3 carbon atoms, R ¹⁴ and R ¹⁵ are the same or different, and both are hydrogen atoms or 1 to 4 carbon atoms. An alkylene group)], preferably 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, 4,4 ′.
-Diaminodicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexylmethane, 1,
In addition to 3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane and the like, alicyclic diamines such as isophorone diamine and menthenediamine are exemplified.

As the aromatic diamine, for example, the general formula: H ₂ N--R ¹⁶ --NH ₂ [wherein R ¹⁶ is

[0028]

Embedded image

(However, Y is --CH _2- , --O--, --S
_{O 2 -, - S -,} - CO- or -C (CH _{3) 2} -)
And a compound represented by the formula:
-Phenylenediamine, m-phenylenediamine, p-
Phenylenediamine, 1,5-diaminonaphthalene,
4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone and the like can be mentioned.

Examples of the monocarboxylic acid include phenylacetic acid, cyclohexylacetic acid, cyclopropanecarboxylic acid, cyclobutanecarboxylic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, 2-methylcyclohexanecarboxylic acid, 3-methylcyclohexanecarboxylic acid and 4-methylcyclohexanecarboxylic acid. Methylcyclohexanecarboxylic acid, 4-ter
t-butylcyclohexanecarboxylic acid, benzoic acid, o-
Methylbenzoic acid, m-methylbenzoic acid, p-methylbenzoic acid, p-ethylbenzoic acid, p-butylbenzoic acid, p-
Examples include tert-butylbenzoic acid and the like.

Particularly preferred diamide compounds (II) are, for example, N, N'-dicyclohexanecarbonyl-p-phenylenediamine, N, N'-dibenzoyl-
Examples include 1,5-diaminonaphthalene, N, N'-dibenzoyl-1,4-diaminocyclohexane, N, N'-dicyclohexanecarbonyl-1,4-diaminocyclohexane and the like.

(4) Diamide compound (III) (see JP-A-5-262936) General formula (IIIa): R ¹⁸ -NHCO-R ¹⁷ -CONH-R ¹⁹ (IIIa) [wherein R ¹⁷ is carbon. C 1-28 saturated or unsaturated aliphatic, C 6-30 alicyclic or C 6-30
The aromatic dicarboxylic acid residue, R ¹⁸ and R ¹⁹ are the same or different, and are all C 3-18 cycloalkyl groups, cycloalkenyl groups,

[0033]

[Chemical 9]

(However, R ²⁰ and R ²¹ have 1 to 1 carbon atoms.
2 linear or branched alkyl, alkenyl, cycloalkyl or phenyl groups, R ²² and R
²³ is a linear or branched alkylene group having 1 to 4 carbon atoms]]
a), or general formula ^{(IIIb): R 25 -CONH-} R 24 in -CONH-R ²⁶ (IIIb) [wherein, R ²⁴ is an aliphatic saturated or unsaturated 1 to 28 carbon atoms, 6 carbon atoms 30 alicyclic or 6 to 30 carbon atoms
Aromatic amino acid residues of the, R ²⁵ and R ²⁶ the same or different and each is a cycloalkyl group having 3 to 18 carbon atoms, a cycloalkenyl group,

[0035]

[Chemical 10]

(However, R ²⁷ is a hydrogen atom and has 1 to 1 carbon atoms.
2 linear or branched alkyl group, alkenyl group, cycloalkyl group or phenyl group, R ²⁸ represents a linear or branched alkyl group having 1 to 12 carbon atoms, alkenyl group, cycloalkyl group or A phenyl group, R ²⁹ and R ³⁰ are each a linear or branched alkylene group having 1 to 4 carbon atoms] and a diamide compound (II
Ib).

Specifically, the diamide compound (IIIa)
Examples of the compound include a compound obtained by amidating an aliphatic, alicyclic or aromatic dicarboxylic acid with an alicyclic or aromatic monoamine.

Examples of the aliphatic dicarboxylic acid include malonic acid, diphenylmalonic acid, succinic acid, phenylsuccinic acid, diphenylsuccinic acid, glutaric acid, 3,3-dimethylglutaric acid, adipic acid, pimelic acid, suberic acid and azelaine. Examples thereof include acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid and 1,18-octadecanedioic acid.

Examples of the alicyclic dicarboxylic acid include 1,2-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and 1,4-cyclohexanediacetic acid.

Examples of the aromatic dicarboxylic acid include p
-Phenylenediacetic acid, p-phenylenediethanoic acid, phthalic acid, 4-tert-butylphthalic acid, isophthalic acid,
5-tert-butylisophthalic acid, terephthalic acid,
1,8-naphthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenic acid, 3,3′-biphenyldicarboxylic acid, 4,4′-biphenyldicarboxylic acid acid,
4,4'-binaphthyldicarboxylic acid, bis (3-carboxyphenyl) methane, bis (4-carboxyphenyl) methane, 2,2-bis (3-carboxyphenyl)
Propane, 2,2-bis (4-carbonoxyphenyl)
Propane, 3,3'-sulfonyldibenzoic acid, 4,4 '
-Sulfonyldibenzoic acid, 3,3'-oxydibenzoic acid, 4,4'-oxydibenzoic acid, 3,3'-carbonyldibenzoic acid, 4,4'-carbonyldibenzoic acid, 3,
3'-thiodibenzoic acid, 4,4'-thiodibenzoic acid,
4,4 '-(p-phenylenedioxy) dibenzoic acid,
Examples thereof include aromatic dibasic acids such as 4,4′-isophthaloyldibenzoic acid, 4,4′-terephthaloyldibenzoic acid, and dithiosalicylic acid.

As the alicyclic monoamine, for example, cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine, 2-methylcyclohexylamine, 3-methylcyclohexylamine, 4-
Methylcyclohexylamine, 2-ethylcyclohexylamine, 4-ethylcyclohexylamine, 2-propylcyclohexylamine, 2-isopropylcyclohexylamine, 4-propylcyclohexylamine, 4
-Isopropylcyclohexylamine, 2-tert-
Butylcyclohexylamine, 4-n-butylcyclohexylamine, 4-isobutylcyclohexylamine,
4-sec-butylcyclohexylamine, 4-ter
t-butylcyclohexylamine, 4-n-amylcyclohexylamine, 4-isoamylcyclohexylamine, 4-sec-amylcyclohexylamine, 4-t
ert-amylcyclohexylamine, 4-hexylcyclohexylamine, 4-heptylcyclohexylamine, 4-octylcyclohexylamine, 4-nonylcyclohexylamine, 4-decylcyclohexylamine, 4-undecylcyclohexylamine, 4-dodecylcyclohexylamine, 4 -Cyclohexylcyclohexylamine, 4-phenylcyclohexylamine, cycloheptylamine, cyclododecylamine, cyclohexylmethylamine, α-cyclohexylethylamine, β-cyclohexylethylamine, α-cyclohexylpropylamine, β-cyclohexylpropylamine, γ-cyclohexylpropylamine Are exemplified.

Examples of aromatic monoamines include aniline, o-toluidine, m-toluidine, p-toluidine, o-ethylaniline, p-ethylaniline, o-propylaniline, m-propylaniline, p-propylaniline and o. -Cumidine, m-cumidine, p-cumidine, o-tert-butylaniline, pn-butylaniline, p-isobutylaniline, p-sec-butylaniline, p-tert-butylaniline, pn-amylaniline , P-isoamylaniline, p-sec-
Amylaniline, p-tert-amylaniline, p-
Hexylaniline, p-heptylaniline, p-octylaniline, p-nonylaniline, p-decylaniline, p-undecylaniline, p-dodecylaniline,
p-cyclohexylaniline, o-aminodiphenyl,
Examples thereof include m-aminodiphenyl, p-aminodiphenyl, p-aminostyrene, benzinamine, α-phenylethylamine, β-phenylethylamine, α-phenylpropylamine, β-phenylpropylamine and γ-phenylpropylamine.

Examples of the diamide compound (IIIb) include compounds obtained by amidating an aliphatic, alicyclic or aromatic amino acid with a monocarboxylic acid or monoamine.

Examples of the aliphatic amino acids include aminoacetic acid, α-aminopropionic acid, β-aminopropionic acid, α-aminoacrylic acid, α-aminobutyric acid, β-aminobutyric acid, γ-aminobutyric acid, α-amino- α-methylbutyric acid, γ-amino-α-methylenebutyric acid, α-aminoisobutyric acid, β-aminoisobutyric acid, α-amino-n-valeric acid, δ
-Amino-n-valeric acid, β-aminocrotonic acid, α-amino-β-methylvaleric acid, α-aminoisovaleric acid, 2-
Amino-4-pentenoic acid, α-amino-n-caproic acid, 6-aminocaproic acid, α-aminoisocaproic acid, 7-aminoheptanoic acid, α-amino-n-caprylic acid, 8-aminocaprylic acid, 9 -Aminononanoic acid, 1
Examples include 1-aminoundecanoic acid and 12-aminododecanoic acid.

Examples of the alicyclic amino acid include 1-aminocyclohexanecarboxylic acid, 2-aminocyclohexanecarboxylic acid, 3-aminocyclohexanecarboxylic acid, 4-aminocyclohexanecarboxylic acid, p-aminomethylcyclohexanecarboxylic acid and 2-amino. Examples include 2-norbornanecarboxylic acid.

Examples of aromatic amino acids include α-aminophenylacetic acid, α-amino-β-phenylpropionic acid, 2-amino-2-phenylpropionic acid, 3-amino-3-phenylpropionic acid and α-aminocinnamic acid. acid,
2-amino-4-phenylbutyric acid, 4-amino-3-phenylbutyric acid, anthranilic acid, m-aminobenzoic acid, p-
Aminobenzoic acid, 2-amino-4-methylbenzoic acid, 2
-Amino-6-methylbenzoic acid, 3-amino-4-methylbenzoic acid, 2-amino-3-methylbenzoic acid, 2-amino-5-methylbenzoic acid, 4-amino-2-methylbenzoic acid, 4 -Amino-3-methylbenzoic acid, 2-amino-3-methoxybenzoic acid, 3-amino-4-methoxybenzoic acid, 4-amino-2-methoxybenzoic acid, 4-amino-3-methoxybenzoic acid, 2 -Amino-4,5-dimethoxybenzoic acid, o-aminophenylacetic acid, m-aminophenylacetic acid, p-aminophenylacetic acid, 4- (4-aminophenyl) butyric acid, 4-aminomethylbenzoic acid, 4-
Aminomethylphenylacetic acid, o-aminocinnamic acid, m-aminocinnamic acid, p-aminocinnamic acid, p-aminohippuric acid, 2
-Amino-1-naphthoic acid, 3-amino-1-naphthoic acid, 4-amino-1-naphthoic acid, 5-amino-1-naphthoic acid, 6-amino-1-naphthoic acid, 7-amino-
1-naphthoic acid, 8-amino-1-naphthoic acid, 1-amino-2-naphthoic acid, 3-amino-2-naphthoic acid,
4-amino-2-naphthoic acid, 5-amino-2-naphthoic acid, 6-amino-2-naphthoic acid, 7-amino-2-
Examples thereof include naphthoic acid and 8-amino-2-naphthoic acid.

Examples of the alicyclic monocarboxylic acid include cyclopropanecarboxylic acid, cyclobutanecarboxylic acid,
Cyclopentanecarboxylic acid, 1-methylcyclopentanecarboxylic acid, 2-methylcyclopentanecarboxylic acid, 3
-Methylcyclopentanecarboxylic acid, 1-phenylcyclopentanecarboxylic acid, cyclopentenecarboxylic acid, cyclohexanecarboxylic acid, 1-methylcyclohexanecarboxylic acid, 2-methylcyclohexanecarboxylic acid, 3-
Methylcyclohexanecarboxylic acid, 4-methylcyclohexanecarboxylic acid, 4-propylcyclohexanecarboxylic acid, 4-butylcyclohexanecarboxylic acid, 4-pentylcyclohexanecarboxylic acid, 4-hexylcyclohexanecarboxylic acid, 4-phenylcyclohexanecarboxylic acid, 1-phenyl Cyclohexanecarboxylic acid, cyclohexenecarboxylic acid, 4-butylcyclohexenecarboxylic acid, cycloheptanecarboxylic acid, 1-cycloheptenecarboxylic acid, 1-methylcycloheptanecarboxylic acid, 4
-Methylcycloheptanecarboxylic acid, cyclohexylacetic acid and the like are exemplified.

Examples of the aromatic monocarboxylic acid include benzoic acid, o-methyl-benzoic acid, m-methyl-benzoic acid, p-methyl-benzoic acid, p-ethyl-benzoic acid and p.
-Propyl-benzoic acid, p-butylbenzoic acid, p-te
Examples include rt-butylbenzoic acid, p-pentylbenzoic acid, p-hexylbenzoic acid, o-phenylbenzoic acid, p-phenylbenzoic acid, p-cyclohexylbenzoic acid, phenylacetic acid, phenylpropionic acid and phenylbutyric acid. .

Examples of the monoamine include the monoamines usable in the diamide compound (IIIa).

Particularly preferred examples of the diamide compound (IIIa) include N, N'-dicyclohexyl terephthalamide and N, N'-dicyclohexyl-1,4.
-Cyclohexanedicarboxamide, N, N'-dicyclohexyl-2,6-naphthalene dicarboxamide, N, N'-dicyclohexyl-4,4'-biphenyldicarboxamide and the like.

Particularly preferred examples of the diamide compound (IIIb) are, for example, N, N'-bis (p-methylphenyl) hexanediamide, N, N'-bis (p-ethylphenyl) hexanediamide, N, N '. -Bis (4-
Cyclohexylphenyl) hexanediamide, p- (N
-Cyclohexanecarbonylamino) benzoic acid cyclohexylamide, δ- (N-benzoylamino) -n-valeric acid anilide and the like can be mentioned.

Examples of the polypropylene resin used in the present invention include propylene homopolymers and copolymers and crystalline polymers. The propylene copolymer preferably contains propylene in an amount of 75% by weight, particularly 90% by weight or more. The copolymerization form may be a block copolymer or a random copolymer. Examples of copolymerizable monomers include ethylene, butene-1, isobutene, pentene-1, 3-methyl-butene-1, hexene-1, 4-methyl-pentene-1,3,4-dimethyl-butene-1, heptene. -1,3-methyl-hexene-
1, 2 or 4 carbon atoms such as octene-1, decene-1
Α-olefin of 10; vinyl chloride, vinylidene chloride, vinyl acetate, ethyl acrylate, methyl methacrylate, maleic anhydride, styrene and other vinyl monomers; 5-ethylidene-2-norbornene, 5-methylene-2-norbornene And one or more diene monomers such as 1,4-hexadiene. Of these, ethylene and butene-1 are preferable in that the rigidity, heat resistance, and the like, which are characteristics of the polypropylene resin, are retained.

If necessary, another resin may be added in an amount that does not impair the effects of the present invention. Other resins include, for example, polyethylene; ethylene / vinyl copolymers of ethylene with vinyl-based monomers such as vinyl acetate, vinyl chloride, vinylidene chloride, ethyl acrylate, methyl methacrylate, maleic anhydride or styrene; Less than 75% by weight ethylene / propylene copolymer;
Ethylene / propylene / diene terpolymer having a propylene content of less than 75% by weight; (hydrogenated) styrene / butadiene random copolymer; (hydrogenated) styrene / butadiene / styrene block copolymer; polybutene; polypentene; Examples include ionomers; polymethylpentene; ethylene / cyclic olefin copolymers; polyisobutene; polybutadiene; polyisoprene.

The β-crystal nucleating agent was added to the polypropylene resin pre-expanded particles in an amount of 0.
It is preferably contained in an amount of 0001 to 10 parts, particularly 0.001 to 1 part. If the amount of the β crystal nucleating agent is too small, the β crystal is less generated and the melting peak on the low temperature side becomes small. On the other hand, 10
Even if the content exceeds the above range, no significant difference is observed in the amount of β crystals formed, and the size of the melting peak on the low temperature side does not change so much, which is economically disadvantageous.

The pre-expanded particles of the present invention can be obtained by mixing a β crystal nucleating agent with a polypropylene resin, adding a foaming agent, and then expanding the mixture.

As a method of mixing the β-crystal nucleating agent with the polypropylene resin, for example, a method of blending the β-crystal nucleating agent during the production (polymerization) of the polypropylene resin, or a method of melt-blending the polypropylene-based resin and the β-crystal nucleating agent And so on.

The composition of the polypropylene resin and the β crystal nucleating agent may further contain a nucleating agent, a stabilizer, an antioxidant, an ultraviolet absorber, a lubricant, an antiblocking agent, a filler, a coloring agent, if necessary. You may mix | blend additives, such as a neutralizer, an antistatic agent, an antacid, a fluorescent whitening agent, and an antibacterial agent. The amount is an amount that does not impair the effects of the present invention.

The resin composition of the polypropylene resin and the β crystal nucleating agent is usually in the form of particles or pellets and is subjected to the step of prefoaming. In the prefoaming, first, a volatile foaming agent is contained in the particles or pellets of the resin composition. A conventionally known method is adopted as a method of incorporating the same. For example, a method of impregnating particles or pellets of a resin composition with a foaming agent in a liquid state in a liquid phase, a method of impregnating particles or pellets with a foaming agent in a gas state in a gas phase, particles or pellets Method of impregnating a foaming agent in a state of being dispersed in water by an aqueous dispersion system, method of impregnating a foaming agent in a state of melting particles or pellets in an extruder using an extruder However, the present invention is not limited to these.

Preferred volatile blowing agents include aliphatic hydrocarbons such as butane, pentane, hexane, propane and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane and cyclobutane; dichlorodifluoromethane and dichlorofluoro. One or more kinds of halogenated hydrocarbons such as methane, trichlorofluoromethane, chloromethane, dichloromethane, chloroethane, dichlorotetrafluoroethane, trichlorotrifluoroethane, perfluorocyclobutane and the like can be mentioned. The content of the foaming agent is selected according to the type of the foaming agent and the target expansion ratio, but usually the resin composition 1
1 to 50 parts is preferable to 00 parts.

As the prefoaming method, a conventionally known method can be adopted. For example, a method of foaming particles or pellets impregnated with a foaming agent under pressure in a pressure vessel, extruding a polypropylene resin in a molten state impregnated with a foaming agent in an extruder to foam and obtain a strand, which is Examples thereof include a method of cutting, a method of dispersing particles or pellets impregnated with a foaming agent in water under pressure, and releasing this under atmospheric pressure to foam. In either method, the particles or pellets of the resin composition are heated to near the melting peak temperature of the polypropylene resin to become pre-expanded particles,
In order to increase the production of β crystals, it is preferable to gradually cool the high temperature pre-expanded particles. The cooling rate may be appropriately set according to the prefoaming method, but it is about 1 to 200.
C./min., Especially 5 to 100.degree. C./min. Examples of the slow cooling method include a method in which the atmosphere during foaming is kept at room temperature or higher with heated air, water, steam or the like. Alternatively, the pre-expanded particles that have been once cooled may be reheated until the α crystal of the polypropylene resin is partially melted, and then gradually cooled under the same conditions as described above.

The pre-expanded particles of the present invention can be obtained, for example, as particles obtained by directly expanding particles or pellets, or as particles obtained by cutting a strand obtained by an extrusion method.

The pre-expanded particles of the present invention include the α-crystal melting peak of the polypropylene resin as well as its low temperature side (about 1%).
(0 ° C lower) has a melting peak of β crystal. The formation of β crystals varies depending on the type, amount, blending method, blending conditions and prefoaming conditions (cooling, curing) of the β crystal nucleating agent as described above, but the prefoamed particles of the present invention have different degrees, Clear β
It has a melting peak of crystal. Further, the coloring unlike the quinacridone β crystal nucleating agent does not occur.

In the present invention, the "melting peak" means a differential scanning calorimeter (DSC. DSC manufactured by Perkin Elmer Co., Ltd.
-10) and 10 mg of the sample in a nitrogen atmosphere at 10 ° C.
The peak obtained when the temperature is raised in / min is called the "melting peak temperature".

The pre-expanded particles of the present invention have a melting peak of α crystal and a melting peak of β crystal on the low temperature side. Therefore,
When re-foaming to produce a foamed molded product, if the β-crystal polypropylene resin is heated to a temperature at which it melts, a foamed molded product with good fusion bonding can be obtained. This indicates that the heating temperature at the time of foam molding can be lowered, and the effect of lowering the steam pressure is exerted in the in-mold molding method. For example, for polypropylene homopolymers and ethylene / propylene block copolymers, the conventional heating temperature of about 160 ° C can be reduced to about 145-155 ° C. Further, in the case of the ethylene / propylene random copolymer, the heating temperature which was about 145 ° C. was changed to about 13
It can be lowered to 0 to 140 ° C.

As a foam molding method using the prefoamed particles of the present invention, a conventionally known in-mold molding method, that is, a mold which can be closed but not closed is filled with the prefoamed particles, and steam-heated to prefoam. A method of expanding the particles to form the particles can be adopted, but the heating temperature condition can be significantly reduced. Examples of such an in-mold molding method include a method in which pre-expanded particles are filled in a mold and then compressed and heat-molded, a method in which pre-expanded particles are filled in a mold in a pressurized state and heat-molded, and pre-expanded particles are used. Examples of the method include a method of filling the mold with the subsequent foaming ability and then heat-molding, and a method of filling the mold with no internal pressure and heat-molding.

Next, the present invention will be explained based on examples and comparative examples, but the present invention is not limited to such examples.

Example 1 Propylene homopolymer (MI = 0.5 g / 10 min, DS
C melting peak is one at 161 ° C. as shown in FIG. 1) 100 parts, β crystal nucleating agent (N, N′-dicyclohexyl-2,6-naphthalene dicarboxamide, manufactured by Shin Nippon Rika Co., Ltd.) 0.5 part of Ngester NU100) and 13 parts of hexane were kneaded by a single-screw extruder, extruded from a circular die at 170 ° C. into the atmosphere at room temperature, pre-foamed in a strand shape, and then allowed to cool. The pre-expanded strand was cut to obtain pre-expanded particles.

The pre-expanded polypropylene resin particles thus obtained had two DSC melting peaks at 150 ° C. and 161 ° C. as shown in FIG.

Further, these pre-expanded particles were treated at 80 ° C. for 8 hours.
Pressurize with kg / cm ² of air for 3 hours, then
It was filled in a molding die and molded at 154 ° C. Fusion of pre-expanded particles in the in-mold molded product is good,
And there was no coloring.

Comparative Example 1 Propylene homopolymer (MI = 0.5 g / 10 min, DS
C melting peak is 1 at 161 ° C) 100 parts, hexane 1
3 parts were kneaded with a single-screw extruder, extruded from a 170 ° C. circular die into the atmosphere at room temperature, and pre-expanded into a strand. The pre-expanded strand was cut to obtain pre-expanded particles.

The pre-expanded polypropylene resin particles thus obtained had one DSC melting peak at 161 ° C.

Further, these pre-expanded particles were heated at 80 ° C. for 8 hours.
Pressurize with kg / cm ² of air for 3 hours, then
It was filled in a molding die and molded at 154 ° C. The molded product in the mold was not colored, but the fusion of the pre-expanded particles was not good. Further, when the molding temperature was raised to 160 ° C., the fusion was not good.

Example 2 Ethylene / propylene random copolymer (ethylene content 3%, MI = 6 g / 10 min, DSC melting peak 143)
100 parts of C), 0.5 part of β crystal nucleating agent (Nippon Rika Co., Ltd., Ngester NU100), and 13 parts of hexane are kneaded with a single screw extruder, and a circular die at 150 ° C. is used to cool the air to room temperature. It was extruded downward and pre-expanded in a strand shape. The pre-expanded strand was cut to obtain pre-expanded particles.

The DSC melting peaks of the polypropylene resin pre-expanded particles thus obtained are 130 ° C. and 143.
The temperature was 2 ° C.

Further, these pre-expanded particles were heated at 80 ° C. for 8 hours.
Pressurize with kg / cm ² of air for 3 hours, then
It was filled in a molding die and molded at 134 ° C. Fusion of pre-expanded particles in the in-mold molded product is good,
And there was no coloring.

Comparative Example 2 Ethylene / propylene random copolymer (ethylene content 3%, MI = 6 g / 10 minutes, DSC melting peak 143)
100 parts of 1 ° C.) and 13 parts of hexane were kneaded by a single screw extruder, extruded from a circular die at 150 ° C. into the atmosphere at room temperature, and pre-expanded in a strand form. The pre-expanded strand was cut to obtain pre-expanded particles.

The pre-expanded polypropylene resin particles thus obtained had a single DSC melting peak at 143 ° C.

Further, these pre-expanded particles were heated at 80 ° C. for 8 hours.
Pressurize with kg / cm ² of air for 3 hours, then
It was filled in a molding die and molded at 134 ° C. The molded product in the mold was not colored, but the fusion of the pre-expanded particles was not good. Further, when the molding temperature was raised to 143 ° C., the fusion was not good.

Example 3 Propylene homopolymer (MI = 0.5 g / 10 min, DS
C melting peak is one at 161 ° C.) 100 parts, β crystal nucleating agent (Nippon Rika Co., Ltd., Ngester NU100) 0.
After dry blending with 5 parts, 2 using a single screw extruder
Pelletized at 00 ° C. 100 parts of the obtained propylene-based resin particles, 9 parts of butane, and 2nd calcium phosphate 3
Parts, sodium dodecylbenzene sulfonate 0.05
Parts and 300 parts of water were placed in a closed container, and these were dispersed in water, heated to 161 ° C. with stirring and held for 0.5 hours, and then the pressure in the container was maintained at 20 kg / cm ^2. On the other hand, one end of the container was opened to simultaneously release the resin particles and water into the atmosphere to obtain pre-expanded particles. The obtained pre-expanded particles were heated and dried in an oven at 165 ° C. for 1.5 hours, and then allowed to cool at room temperature.

The DSC melting peaks of the pre-expanded particles of the polypropylene resin thus obtained are 152 ° C. and 177.
The temperature was 2 ° C.

The melting peak at 152 ° C. is based on β crystal, and the melting peak at 177 ° C. is based on α crystal. The reason why the melting peak temperature of α crystal is high is presumed to be as follows. That is, when the resin particles are pre-expanded,
When heated to 61 ° C., the α crystal does not melt completely but remains partially unmelted. Therefore, if the β crystal nucleating agent is not added, the α crystal that has not melted grows into a large crystal by part of the melted portion, while the rest of the melted portion becomes a small crystal during crystallization during cooling. (Α crystal).
Due to the size of this crystal, two melting peaks appear even for the same α crystal. In this respect, the following Comparative Example 3
Is shown in.

These pre-expanded particles were added at 80 ° C. and 8 kg /
Pressurization with air of cm ² was carried out for 3 hours, and subsequently, the molding die was filled and molding was carried out at 154 ° C. The fusion of the pre-expanded particles in the in-mold molded product was good, and there was no coloring.

Comparative Example 3 Propylene homopolymer (MI = 0.5 g / 10 min, DS
Only the C melting peak (one at 161 ° C.) was pelletized at 200 ° C. using a single screw extruder. 100 parts of the obtained propylene-based resin composition particles, 9 parts of butane, 2 parts of tricalcium phosphate, 0.05 part of sodium dodecylbenzenesulfonate and 300 parts of water were placed in a closed container, and these were dispersed in water. After heating to 161 ° C. with stirring and holding for 0.5 hour, the pressure in the container is 20 kg / cm 2.
While holding at ² , one end of the container was opened to simultaneously release the resin composition particles and water into the atmosphere, and dried to obtain pre-expanded particles.

The pre-expanded particles of the polypropylene resin thus obtained had two DSC melting peaks at 161 ° C. and 177 ° C. (both are α crystal peaks).

Further, these pre-expanded particles were treated at 80 ° C. for 8 hours.
Pressurization was carried out with air of kg / cm ² for 3 hours, and subsequently, the mold was filled and molded at 154 ° C. The molded product in the mold was not colored, but the fusion of the pre-expanded particles was not good. Also, the molding temperature was raised to 160 ° C,
The fusion was poor.

Example 4 Ethylene / propylene random copolymer (ethylene content 3%, MI = 6 g / 10 min, DSC melting peak 143)
After dry-blending with 100 parts of 1 ° C.) and 0.5 part of β crystal nucleating agent (Nippon Rika Co., Ltd., Ngester NU100), pelletization was performed at 180 ° C. using a single screw extruder. 100 parts of the obtained polypropylene-based resin particles, 9 parts of butane, 2 parts of tricalcium phosphate, 0.05 part of sodium dodecylbenzenesulfonate and 300 parts of water are placed in a closed container, dispersed in water, and stirred. While raising the temperature to 146 ° C. and holding it for 0.5 hour, one end of the container was opened and the resin particles and water were simultaneously released into the atmosphere while the pressure inside the container was kept at 18 kg / cm ^2. , Pre-expanded particles were obtained. 1 the obtained pre-expanded particles in the oven
After heating and drying at 48 ° C. for 1.5 hours, the mixture was allowed to cool at room temperature.

The pre-expanded polypropylene resin particles thus obtained have DSC melting peaks of 130 ° C. and 160 ° C.
The temperature was 2 ° C.

Further, these pre-expanded particles were heated at 80 ° C. for 8 hours.
Pressurize with kg / cm ² of air for 3 hours, then
It was filled in a molding die and molded at 134 ° C. Fusion of pre-expanded particles in the in-mold molded product is good,
And there was no coloring.

Comparative Example 4 Ethylene / propylene random copolymer (ethylene content 3%, MI = 6 g / 10 minutes, DSC melting peak 143
Only one (° C.) was pelletized at 180 ° C. using a single screw extruder. Obtained polypropylene resin particles 100
Parts, butane 9 parts, tricalcium phosphate 2 parts, sodium dodecylbenzene sulfonate 0.05 parts, water 300
Parts in a closed container, these are dispersed in water, the temperature is raised to 146 ° C. with stirring and held for 0.5 hours, and then the pressure in the container is maintained at 18 kg / cm ² . The resin composition particles and water were simultaneously released into the atmosphere by opening one end, and dried to obtain pre-expanded particles.

The pre-expanded particles of the polypropylene resin thus obtained had two DSC melting peaks at 138 ° C. and 160 ° C. (both α-crystal peaks).

Further, these pre-expanded particles were heated at 80 ° C. for 8 hours.
Pressurize with kg / cm ² of air for 1 hour, then
It was filled in a molding die and molded at 134 ° C. The molded product in the mold was not colored, but the fusion of the pre-expanded particles was not good. Further, when the molding temperature was raised to 143 ° C., the fusion was not good.

Comparative Example 5 Ethylene / propylene random copolymer (ethylene content 3%, MI = 6 g / 10 min, DSC melting peak 143)
After dry-blending 100 parts of 1) at 0.5 ° C. and 0.5 part of γ-quinacridone, pelletization was performed at 180 ° C. using a single screw extruder. Obtained polypropylene resin particles 100
Parts, butane 9 parts, tricalcium phosphate 2 parts, sodium dodecylbenzene sulfonate 0.05 parts, water 300
Parts in a closed container, these are dispersed in water, the temperature is raised to 146 ° C. with stirring and held for 0.5 hours, and then the pressure in the container is maintained at 18 kg / cm ² . One end was opened and resin particles and water were simultaneously released into the atmosphere to obtain pre-expanded particles. The obtained pre-expanded particles were heated and dried in an oven at 148 ° C. for 1.5 hours, and then allowed to cool at room temperature.

The DSC melting peaks of the pre-expanded polypropylene resin particles thus obtained were 138 ° C. and 160.
The temperature was 2 ° C (both are presumed to be α crystals).

Further, these pre-expanded particles were heated at 80 ° C. for 8 hours.
Pressurize with kg / cm ² of air for 3 hours, then
It was filled in a molding die and molded at 134 ° C. The fusion of the pre-expanded particles in the in-mold molded product is poor,
And it was colored red.

[0095]

EFFECT OF THE INVENTION The pre-expanded particles of the polyolefin resin of the present invention have a melting peak on the low temperature side, so that they can be formed in the mold at a lower temperature, which is economically advantageous. The in-mold molded product obtained from the pre-expanded polypropylene resin particles of the present invention retains the characteristics of polypropylene resin such as rigidity and heat resistance.

[Brief description of drawings]

1 is a DS of the propylene homopolymer used in Example 1. FIG.
It is a C chart.

2 is a DSC chart of pre-expanded particles of the propylene homopolymer produced in Example 1. FIG.

Claims (7)

[Claims] 1. Pre-expanded particles comprising a polypropylene resin and a β crystal nucleating agent (excluding a quinacridone type β crystal nucleating agent). 2. The pre-expanded particles according to claim 1, wherein the β crystal nucleating agent is dianilide adipic acid, dianilide suberic acid or a mixture thereof. 3. The β-crystal nucleating agent has the general formula (I): R ¹ —NHCO—X—CONH—R ² (I) (wherein, X is The pre-expanded particles according to claim 1, wherein R ¹ and R ² are the same or different and each is a cycloalkyl group having 5 to 12 carbon atoms). 4. The β crystal nucleating agent is represented by the general formula (II): R ⁴ —CONH—R ³ —NHCO—R ⁵ (II) (wherein R ³ is an aliphatic diamine residue having 1 to 24 carbon atoms). ,
Alicyclic diamine residue having 6 to 21 carbon atoms or 6 to 12 carbon atoms
15 aromatic diamine residues, R ⁴ and R ⁵ are the same or different, and are all C 3-14 cycloalkyl groups, C 3-14 cycloalkenyl groups, (However, each of R ⁶ and R ⁷ is a hydrogen atom or a linear or branched alkyl or alkenyl group having 1 to 4 carbon atoms, and R ⁸ and R ⁹ are each 1 to 1 carbon atoms.
The pre-expanded particles according to claim 1, which is a diamide compound represented by 3) which is a linear or branched alkylene group of 3)). 5. The β crystal nucleating agent is represented by the general formula (IIIa): R ¹⁸ —NHCO—R ¹⁷ —CONH—R ¹⁹ (IIIa) [wherein R ¹⁷ is a saturated or unsaturated group having 1 to 28 carbon atoms]. Aliphatic, alicyclic having 6 to 30 carbon atoms or 6 to 30 carbon atoms
The aromatic dicarboxylic acid residue of R ¹⁸ and R ¹⁹ are the same or different, and are each a cycloalkyl group having 3 to 18 carbon atoms, a cycloalkenyl group, or (However, R ²⁰ and R ²¹ are linear or branched alkyl groups having 1 to 12 carbon atoms, alkenyl groups, cycloalkyl groups or phenyl groups, and R ²² and R ²³ are those having 1 carbon atoms.
Is a linear or branched alkylene group of 4).
Or a diamide compound represented by the general formula (III
^{b): R 25 -CONH-R} 24 -CONH-R 26 (IIIb) wherein, R ²⁴ is an aliphatic saturated or unsaturated 1 to 28 carbon atoms, alicyclic or carbon having 6 to 30 carbon atoms Number 6 to 30
R ²⁵ and R ²⁶ are the same or different, and all have a C 3-18 cycloalkyl group, a cycloalkenyl group, or (Wherein R ²⁷ is a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, an alkenyl group, a cycloalkyl group or a phenyl group, and R ²⁸ is a linear or branched chain having 1 to 12 carbon atoms. A chain alkyl group, an alkenyl group, a cycloalkyl group or a phenyl group, and R ²⁹ and R ³⁰ are each a linear or branched alkylene group having 1 to 4 carbon atoms]. Item 1. Pre-expanded particles according to item 1. 6. Pre-expanded particles of a polypropylene resin, wherein a polypropylene crystal resin is mixed with a β crystal nucleating agent (excluding a quinacridone type β crystal nucleating agent), and then a volatile foaming agent is added to the polypropylene resin and foamed by heating. Manufacturing method. 7. The β-crystal nucleating agent according to claim 2, 3, 4 or 5.
The method according to claim 6, wherein the compound is one or more of the compounds described.