JP2000038484A - Polypropylene composition - Google Patents

Abstract

(57) [Summary] (Problem corrected) [PROBLEMS] In a composition in which a dibenzylidene sorbitol compound and a complex salt of lithium and aluminum are blended with polypropylene, a dibenzylidene sorbitol compound component is added to a mold at the time of molding. Provided is an improved polypropylene composition which prevents adhesion and suppresses a decrease in transparency. (A) Polypropylene
100 parts by weight (b) dibenzylidene sorbitol compound
0.01 to 0.5 parts by weight (c) lithium and aluminum complex salt
0.01 to 0.3 parts by weight (d) liquid paraffin
A polypropylene composition comprising 0.1 to 5 parts by weight, and further preferably containing 0.05 to 0.5 part by weight of (e) a diphenyl ether compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a polypropylene composition. More specifically, the present invention provides a polypropylene composition which is excellent in mold adhesion prevention during injection molding and is suitable for use in daily necessities, food containers, medical parts and the like.

[0002]

2. Description of the Related Art Polypropylene is used in a wide variety of fields, and is particularly effectively used for daily necessities, food containers and medical parts. Polypropylene is generally blended with a dibenzylidene sorbitol-based compound as a nucleating agent in a field where transparency of a molded product is required. As a method for further improving the transparency effect of the nucleating agent, it is known to blend a composite salt of lithium and aluminum with polypropylene (Japanese Patent Application Laid-Open No. 7-1995).
224195).

[0003]

As a result, the transparency of the molded article is considerably improved. However, when the composite salt of lithium and aluminum is used in combination as described above, there has been a problem that the adhesion of the dibenzylidene sorbitol compound to the mold becomes particularly severe during injection molding. And, if the amount of adhesion to the mold is increased by continuing the molding, the surface of the injection molded product becomes rough due to unevenness,
This peeled off and adhered to the surface side of the injection-molded article, thereby deteriorating the appearance of the molded article.

[0004] Therefore, in the above-mentioned polypropylene composition, it has been an important problem to suppress the adhesion of the dibenzylidene sorbitol-based compound component to the mold during molding.

[0005]

Means for Solving the Problems In view of the above problems, the present inventors have intensively studied. As a result, it has been found that the above problems can be solved by blending a specific amount of liquid paraffin, and the present invention has been proposed.

That is, the present invention relates to (a) 100 parts by weight of polypropylene (b) 0.01 to 0.5 parts by weight of a dibenzylidene sorbitol compound (c) 0.01 to 0.3 parts by weight of a complex salt of lithium and aluminum Part (d) Liquid paraffin is a polypropylene composition comprising 0.1 to 5 parts by weight.

As the polypropylene applied to the present invention, known polypropylenes polymerized using a Ziegler type catalyst or a metallocene catalyst can be used without limitation. In particular,
Propylene homopolymer, or propylene and other α-
A copolymer with an olefin is used. Where the other α
Examples of the olefin include those having 2 to 8 carbon atoms such as ethylene and 1-butene. The amount is within a range that does not impair the effects of the present invention, and is usually preferably 50% by weight or less. Further, the copolymer of propylene and another α-olefin may be any of a random copolymer, a block copolymer, and a graft polymer.

Furthermore, homopolymers of other α-olefins such as ethylene and 1-butene, or other α-olefins
-A copolymer of olefins and polypropylene may be used as a mixture. The mixing amount is within a range that does not impair the effect of the present invention, and it is generally preferable that the other α-olefin polymer to be mixed is 20 parts by weight or less based on 100 parts by weight of polypropylene.

These polypropylenes may be decomposed using an organic peroxide to adjust the molecular weight and the melt flow rate.

The polypropylene composition of the present invention contains a dibenzylidene sorbitol compound. A dibenzylidene sorbitol compound is conventionally known as a nucleating agent for improving the transparency of polypropylene, and specifically, has the following general formula (I):

[0011]

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The compound having the structure represented by the formula is used without any particular limitation. The groups represented by R ₁ and R ₂ in the formula represent an organic group, and are preferably an alkyl group, a halogen, or an alkoxy group. The alkyl group preferably has 1 to 5 carbon atoms, such as a methyl group, an ethyl group, and a t-butyl group. Halogen is fluorine, chlorine, bromine, iodine or the like. The alkoxy group preferably has 1 to 5 carbon atoms,
For example, a methoxy group, an ethoxy group, etc. Further, m and n are integers of 0 to 3.

More specifically, dibenzylidene sorbitol, di (P-methylbenzylidene) sorbitol, di (P-ethylbenzylidene) sorbitol, di (dimethylbenzylidene) sorbitol, 1.3-P-chlorobenzylidene2.4-P -Methylbenzylidene sorbitol, di (Pt-butylbenzylidene) sorbitol,
Di (4-propylbenzylidene) sorbitol, 1.3
-P-methylbenzylidene 2.4 benzylidene sorbitol, di (P-methoxybenzylidene) sorbitol and the like.

The amount of these nucleating agents is 0.01 to 0.5 part by weight, preferably 0.05 to 0.3 part by weight, per 100 parts by weight of polypropylene. That is, if the amount is less than 0.01 part by weight, sufficient transparency and rigidity cannot be obtained, and if the amount exceeds 0.5 part by weight,
This is not preferable because the transparency effect reaches a peak.

In the polypropylene composition of the present invention, a composite salt of lithium and aluminum is blended. The composite salt of lithium and aluminum has an action of preventing the dibenzylidene sorbitol-based compound from deteriorating due to chlorine and the like remaining in the catalyst, and the transparency of the polypropylene composition is further improved.

As the composite salt of lithium and aluminum, one represented by the following general formula [LiAl ₂ (OH) ₆ ] ₂ X · mH ₂ O is usually used. In the formula, X is CO ₃ or SO ₄ , and m is 0 to 3. Among them, [LiAl ₂ (OH) ₆ ] ₂ CO ₃ .1.6H ₂ O [LiAl ₂ (OH) ₆ ] ₂ SO ₄ .1.2H ₂ O is preferably used.

The compounding amount of the composite salt of lithium and aluminum is 0.1 to 100 parts by weight of polypropylene.
The amount is from 0.01 to 0.3 part by weight, preferably from 0.02 to 0.2 part by weight. That is, if the amount is less than 0.01 part by weight, the effect of sufficiently suppressing the deterioration of the dibenzylidene sorbitol-based compound cannot be obtained, and if the amount exceeds 0.3 part by weight, the above-mentioned effect reaches a peak. Is not preferred.

As described above, in the polypropylene composition containing the dibenzylidene sorbitol compound and the composite salt of lithium and aluminum in combination as described above, the dibenzylidene sorbitol compound is added to the surface of the mold during injection molding. If the mold is not washed frequently, the appearance of the molded article is deteriorated. The greatest feature of the present invention is that, by further blending liquid paraffin with this polypropylene composition,
The problem is that the problem of mold adhesion of the dibenzylidene sorbitol compound has been successfully improved.

Here, liquid paraffin is known as a liquid saturated hydrocarbon, and its main component is a mixture of alkyl naphthenic hydrocarbons. Liquid paraffin is 37.8
Those having a viscosity of 8 to 90 centistokes measured at 0 ° C. are preferable, and those having a viscosity of 9 to 80 centistokes are particularly preferable.
It is preferable because of good compatibility with polyolefin.

The amount of the liquid paraffin is 0.1 to 5 parts by weight, preferably 0.2 to 3 parts by weight, based on 100 parts by weight of the polypropylene. That is, if the amount is less than 0.1 part by weight, the effect of sufficiently suppressing the adhesion of the dibenzylidene sorbitol-based compound to the mold cannot be obtained, and if the amount exceeds 5 parts by weight, the rigidity of the polypropylene is reduced. In addition, the physical properties such as transparency and the like are reduced, and the effect of suppressing the adhesion to the mold also reaches a peak, which is not preferable.

The polypropylene composition of the present invention preferably further contains a diphenyl ether compound. Thereby, the effect of preventing the dibenzylidene sorbitol compound from adhering to the mold is further improved. These diphenyl ether compounds are specifically represented by the following general formula (II)

[0022]

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(Where R ₃ is a hydrogen atom, an alkyl group or a phenoxy group, and the phenoxy group may be substituted with an alkyl group; and R ₄ is a hydrogen atom, an alkyl group, a phenyl group or a phenoxy group. Wherein the phenyl group may be substituted with an alkyl group, and the phenoxy group may be substituted with an alkyl group, a phenyl group or a phenoxy group (provided that R ₃ and R ₄ are simultaneously a hydrogen atom). ), And k and l are each an integer of 1 to 4.). These diphenyl ether compounds are compounds known as compounds that impart radiation resistance to molded products when polypropylene is molded into medical parts such as syringes, but in the present invention,
By blending these diphenyl ether compounds, not only the radiation resistance described above, but also a particularly excellent effect is obtained in the effect of preventing the dibenzylidene sorbitol-based compound from adhering to the mold. In addition, the effect of the radiation resistance,
Very high due to the synergistic effect with liquid paraffin.

In the diphenyl ether compound represented by the above general formula (II), the number of carbon atoms of the alkyl group represented by R ₃ is not particularly limited. Preferably, there is. Further, the number of carbon atoms of the alkyl group which is a substituent of the phenoxy group represented by R ₃ is 1 to 1 for the same reason as described above.
It is preferably 4. Furthermore, the number of carbon atoms in the alkyl group represented by R ₄ is preferably 10 to 30 as well as R _3, carbon atoms in the alkyl group is a substituent of a phenyl group and a phenoxy group represented by R ₄ is 1 -4 is preferred.

Specific examples of the diphenyl ether compound preferably used are as follows.

[0026]

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(However, R ₅ is an alkyl group having 1 to 4 carbon atoms, and R ₆ is an alkyl group having 10 to 30 carbon atoms.) The compounding amount of these diphenyl ether compounds is 100 parts by weight of polypropylene. Thus, it is used in the range of 0.05 to 5 parts by weight, and preferably in the range of 0.1 to 4 parts by weight.

The composition of the present invention may further contain, if necessary, other additives such as a phosphorus antioxidant, a phenol antioxidant, a sulfur antioxidant, an ultraviolet absorber, a light stabilizer, An antistatic agent, a lubricant, a neutralizing agent, a dispersant, a nucleating agent, a crystallization accelerator, a flame retardant, a metal deactivator, a filler, a pigment, and the like may be blended.

The above components can be blended by any ordinary method used for mixing resins without any limitation. For example, a dibenzylidene sorbitol compound, a complex salt of lithium and aluminum, and liquid paraffin are added to a powdery or pelletized polypropylene component, mixed with a tumbler or a Henschel mixer, and then melt-kneaded with an extruder to form a pellet. Is preferred. The order of addition of each component is not particularly limited,
Each component may be mixed in a different order from the above method. Furthermore, a masterbatch in which each component is concentrated and blended at a high concentration can be prepared and mixed and used.

[0030]

According to the present invention, since a dibenzylidene sorbitol compound and a complex salt of lithium and aluminum are mixed with polypropylene, the decomposition of the dibenzylidene sorbitol compound is suppressed, and the transparency is extremely excellent. A molded article is obtained.

In a polypropylene composition containing a dibenzylidene sorbitol compound and a complex salt of lithium and aluminum, the adhesion of the dibenzylidene sorbitol compound to the mold surface during injection molding, which occurs violently, is caused by liquid paraffin. Is significantly suppressed by the addition of Therefore, even if the molding is continued for a long period of time, the appearance of the molded product is unlikely to be deteriorated, and a long run of the injection molding becomes possible, and the workability is improved.

Therefore, the polypropylene composition of the present invention having such properties is usefully used for daily necessities, food containers, medical parts and the like.

[0033]

EXAMPLES Hereinafter, the present invention will be described more clearly with reference to the following Examples.
Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The polypropylenes, additives and their symbols used in the examples are as follows.

1. Polypropylene A1: Homopolymer (melt flow rate: 20 g / 1
A2: ethylene-propylene random copolymer (ethylene content: 3% by weight, melt flow rate: 20 g /
10 minutes) Nucleating agent B1: Di (4-methylbenzylidene) sorbitol: Gerol MD (manufactured by Shin Nippon Rika) B2: Dibenzylidene sorbitol: Denone YK-1
B3: 1-P-methylbenzylidene 2.4 benzylidene sorbitol B4: Di (4-methoxybenzylidene) sorbitol Complex salt of lithium and aluminum C1: Complex salt of lithium and aluminum [LiAl ₂ (OH) ₆ ] ₂ CO ₃ .1.6H ₂ O: MIZ
3. UKALAC (manufactured by Mizusawa Chemical) C2: Complex salt of lithium and aluminum [LiAl ₂ (OH) ₆ ] ₂ SO ₄ .1.2H ₂ O Liquid paraffin D1: Moresco White P-80 (Matsumura Oil Laboratories) Viscosity = 16.2 cSt (37.8 ° C.) D2: Moresco White P-60 (Matsumura Oil Laboratories) Viscosity = 10.6 cSt (37.8 ° C.) D3: Moresco White P-250 (Matsumura Oil Laboratories) Viscosity = 54.0 cSt (37.8 ° C) Diphenyl ether compound E1: monoalkyl diphenyl ether alkyl group: carbon number 12 (50%), carbon number 14 (50
%): Moresco Hyrad RA-15 (manufactured by Matsumura Oil Research Institute) Examples 1 to 16, Comparative Examples 1 to 5 Preparation of polypropylene composition, preparation of test sample, and test of effect using test sample The method was performed as follows. The measurement results of the obtained mold adhesion, transparency and radiation resistance tests are shown in Table 1.

(1) Premixing Tris (2, 4) was added to 100 parts by weight of polypropylene.
-Di-t-butylphenyl) phosphite: 0.05 parts by weight and various components shown in Table 1 were blended and premixed with a Henschel mixer.

(2) Effect test (a) Mold adhesion The above mixture was pelletized at a resin temperature of 230 ° C using a 50 mmφ extruder (full flight type screw, cylinder: L / D = 28, with vent).

Using the pellets, a test syringe (cylindrical: thickness 1 mmt) was continuously injection-molded (cylinder temperature: 230 ° C., mold temperature: 20 ° C.), and the nucleating agent component was placed on the surface of the mold. The number of shots when they adhered so that they could be visually confirmed was measured.

(B) Transparency Using the above pellets, test specimens (thickness: 1 mmt) were injection molded (cylinder temperature: 230 ° C, mold temperature: 40).
° C), and the haze value was measured. The smaller the haze value, the better the transparency.

(C) Radiation resistance (change in mechanical strength) Using the above pellets, injection molding (cylinder temperature: 23)
A test sample (Izod specimen) subjected to 0 ° C. and a mold temperature of 40 ° C.) was subjected to γ-ray sterilization (irradiation dose: 20 KGy), and the Izod impact strength was measured according to JIS K7110.

[0040]

[Table 1]

Claims (2)

[Claims] (A) 100 parts by weight of polypropylene (b) 0.01 to 0.5 parts by weight of a dibenzylidene sorbitol compound (c) 0.01 to 0.3 parts by weight of a complex salt of lithium and aluminum (d) A polypropylene composition comprising 0.1 to 5 parts by weight of liquid paraffin. 2. The diphenyl ether compound (e) is used in an amount of 0.05 to 0.
2. The polypropylene composition according to claim 1, comprising 5 parts by weight.