JP3134033B2 - Polypropylene composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polypropylene composition, and more particularly to a polypropylene composition having improved color tone and transparency.

[0002]

2. Description of the Related Art Polypropylene is used in a wide variety of fields, and is particularly effectively used for daily parts, food containers, disposable syringes and infusion container materials. When used in these applications, polypropylene has a drawback that the crystallization rate after heat-melt molding is low, so that the molding cycle is reduced, and large crystals are formed, resulting in poor transparency. It has been known to add a nucleating agent or the like in order to solve these disadvantages. Conventionally, dibenzylidene sorbitol compounds such as dibenzylidene sorbitol, di ( P-methylbenzylidene ) sorbitol,
Metal salts of benzoic acid such as aluminum pt-butyl benzoate and sodium benzoate; metal salts of organic phosphates such as sodium-2,2'-methylenebis (4,6-di-t-butylphenyl) phosphate; Various compounds such as inorganic compounds such as talc have been used.

[0003]

However, the effect of improving the transparency by the addition of these nucleating agents is not sufficient, and therefore, in addition to the above-mentioned nucleating agents, other compounds are used in combination. Attempts have been made to improve the transparency by blending them. For example, a method in which dibenzylidene sorbitol is used in combination with hydrotalcite (JP-A-58-1)
No. 57841), a method of using a metal salt of a carboxylic acid in combination (Japanese Patent Publication No. 60-50217, Japanese Patent Application Laid-Open No. 58-1983).
JP-A-104933), and a method in which an aliphatic metal salt is used in combination (JP-A-58-12936). However, even with these methods, the effect of improving the transparency cannot be satisfied at one step, and it has been desired to further improve the transparency.

When a nucleating agent or various compounds are added to polypropylene to improve the transparency, the resin may turn yellow and its color tone may deteriorate. Therefore, it has been an important issue to improve the transparency while improving the color tone.

[0005] In view of the above background, an object of the present invention is to provide a polypropylene composition having good transparency and color tone.

[0006]

Means for Solving the Problems In view of the above problems, the present inventors have intensively studied. As a result, they have found that the above problems can be solved by blending a dibenzylidene sorbitol compound and a specific lithium aluminum salt with polypropylene, and have led to the present invention.

That is, the present invention relates to (a) 100 parts by weight of polypropylene, (b) 0.01 to 1 part by weight of a dibenzylidene sorbitol compound, and (c) the following general formula [LiAl ₂ (OH) ₆ ] ₂ X A polypropylene composition comprising 0.01 to 1 part by weight of a lithium aluminum salt represented by mH ₂ 0 (wherein X represents CO ₃ , SO ₄ or HPO ₄ , and m is a number of 0 to 3) It is.

As the polypropylene applied to the present invention, a homopolymer of propylene or a copolymer of propylene with another α-olefin such as ethylene and 1-butene is used. Here, the amount of the α-olefin is within a range that does not impair the effects of the present invention, and is 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. further,
Other α-olefin polymers, for example, other α-olefin homopolymers such as ethylene and 1-butene, or a blend of a copolymer of these other α-olefins with polypropylene may be used. The mixing amount is within a range that does not impair the effects of the present invention.
The amount of the other α-olefin polymer to be blended is preferably 20 parts by weight or less based on 0 part by weight. In addition, these polypropylenes may be either a polymerization type or a depolymerization type using an organic peroxide. In addition, when this composition is obtained, the desired melt flow rate can be obtained by blending the additive component and an organic peroxide.

In the present invention, the dibenzylidene sorbitol compound is 1,3,2,4-dibenzylidene sorbitol or a derivative thereof. Such a dibenzylidene sorbitol compound is conventionally known as a nucleating agent for improving the transparency of polypropylene, and specifically has the following general formula:

[0010]

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The compound having the structure represented by the formula is used without any particular limitation. As the groups represented by R _{1 to} R ₁₀ in the formula, hydrogen and known alkyl groups, halogens, methoxy groups and the like can be used. Here, the alkyl group is a known alkyl group having 1 to 18 carbon atoms, such as a methyl group, an ethyl group,
-Butyl group, stearyl group and the like. Halogen is fluorine, chlorine, bromine, iodine. Specifically, in addition to dibenzylidene sorbitol, for example, di (P-methylbenzylidene) sorbitol, di (P-ethylbenzylidene) sorbitol, di (dimethyldibenzylidene) sorbitol, mono (P-methyl) dibenzylidene sorbitol, mono (P-methyl) dibenzylidene sorbitol (Dimethyl) dibenzylidene sorbitol,
1.3-P-chlorobenzylidene 2.4-P-methylbenzylidene sorbitol and the like are preferably used.

The compounding amount of these dibenzylidene sorbitol compounds is 0.01 to 1 part by weight, preferably 0.03 to 0.5 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 cannot be obtained, and if the amount exceeds 1 part by weight, the transparency may be impaired.

Next, in the present invention, in addition to the dibenzylidene sorbitol compound, a lithium aluminum salt represented by the following formula [LiAl ₂ (OH) ₆ ] ₂ X · mH ₂₀ is mixed with polypropylene. Thereby, the obtained polypropylene composition becomes more excellent in transparency, yellowing and the like are prevented, and the color tone is also improved. In the above formula of the lithium aluminum salt, X is CO ₃ , SO ₄ or HPO ₄ , and m is a number from 0 to 3. Among these lithium aluminum salts, those which can be suitably used are exemplified by, for example, [LiAl ₂ (OH) ₆ ] ₂ CO ₃ .1.6H ₂₀ , [LiAl ₂ (OH) ₆ ] ₂ SO ₄ .1. 2H ₂ 0, and the like _{[LiAl 2 (OH) 6]} 2 HPO 4 · 1.4H 2 0.

The amount of these lithium aluminum salts is 0.01 to 1 with respect to 100 parts by weight of polypropylene.
Parts by weight, preferably 0.03 to 0.5 parts by weight. In this amount, the effect of the present invention for improving transparency and color tone is remarkably exhibited.

In the present invention, it is preferable to add a metal salt of a fatty acid in addition to the above-mentioned components. Thereby, the effect of improving the color tone is further improved. Here, the fatty acid of the metal salt is not particularly limited, but stearic acid, lauric acid, montanic acid,
It is preferable to use one having 8 to 40 carbon atoms such as behenic acid. Examples of the metal include sodium, potassium, lithium, calcium, magnesium, zinc and the like. Among them, it is preferable to use a metal of Group I of the periodic table, particularly sodium. Specific examples of the metal salts of the above fatty acids most preferably used include, for example, sodium stearate, sodium laurate and sodium montanate.

The amount of the metal salt of the fatty acid is not particularly limited, but is usually 0.001 to 0.3 parts by weight with respect to 100 parts by weight of the polypropylene in consideration of the color tone improving effect. , Preferably 0.005-
0.2 parts by weight is preferred.

The composition of the present invention may further contain, if necessary, other additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a lubricant, a neutralizer, a dispersant, and a crystallization agent. Accelerators, flame retardants, metal deactivators, fillers, pigments, and other heat stabilizers may be included.

In the present invention, the above-mentioned components can be blended by any ordinary method which is carried out by mixing resins without any limitation. For example, a dibenzylidene sorbitol-based compound component and a lithium aluminum salt component are added to a powdery or pelletized polypropylene component,
It is preferable to use a tumbler or a Henschel mixer, etc., and then melt-knead with an extruder to form pellets. The order of addition of each component is not particularly limited, and each component may be mixed in a different order from the above method. further,
A masterbatch in which each component is concentrated and mixed at a high concentration can be prepared and mixed and used.

[0019]

According to the present invention, a polypropylene composition having excellent color tone and transparency can be obtained by blending a dibenzylidene sorbitol compound and a lithium aluminum salt with polypropylene. This polypropylene composition is usefully used for various daily parts, food containers, medical parts and the like.

[0020]

EXAMPLES Hereinafter, the present invention will be described in more detail 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 component A: ethylene-propylene random copolymer (ethylene content: 2% by weight, melt flow rate: 20 g / 1
0 min) 2. 2. Dibenzylidene sorbitol-based compound component B1: Dibenzylidene sorbitol: Denone YK1 (manufactured by Marubishi Yuka) B2: Di (P-methylbenzylidene) sorbitol: Gerol MD (manufactured by Shin Nippon Rika) Lithium aluminum salt component C1: [LiAl ₂ (OH) ₆ ] ₂ CO ₃ .1.6H ₂
0: MIZUKALAC (manufactured by Mizusawa Chemical Industries) C2: [LiAl ₂ (OH) ₆ ] ₂ SO ₄ .1.2H ₂
0 C3: [LiAl ₂ (OH) ₆ ] ₂ HPO ₄ • 1.4H
₂₀ 4. Other components B3: aluminum pt-butyl benzoate: AL-PTBBA (manufactured by Shell Chemical) B4: sodium-2,2'-methylenebis (4,6-
Di -t- butyl phenyl) phosphate: NA-11 (manufactured by Asahi Denka) C4: hydrotalcite compound _{Mg 4.5 Al 2 (OH) 13} CO 3 · 3.5H 2 O: DHT-4A ( Kyowa Chemical Industry Co., Ltd. D1) Sodium stearate
(Nippon Yushi) D2: Calcium distearate
(Manufactured by NOF CORPORATION) Examples 1 to 10, Comparative Examples 1 to 4 Preparation of a polypropylene composition, preparation of a test sample, and a test method of the effect using the test sample were performed as follows. Table 1 shows the obtained color tone and transparency measurement results.

(1) Pre-mixing Tris (2, 4) was added to 100 parts by weight of polypropylene.
-Di-t-butylphenyl) phosphite: 0.08 parts by weight, tetrakis [methylene- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane: 0.03 parts by weight, and first Various components shown in the table were blended and premixed with a Henschel mixer.

(2) Pelletization 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).

(3) Effect test (b) Transparency Injection molding (cylinder temperature: 230 ° C., mold temperature: 40)
C)), the haze of the test sample (thickness 1 mmt) was measured by JI
It was measured according to SK7105.

(A) Measurement of color tone A test sample (thickness: 3) injection-molded (the conditions are the same as described above)
mmt) according to JIS
It was measured according to K7103.

[0026]

[Table 1]

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Claims (1)

(57) [Claims] 1. (a) 100 parts by weight of polypropylene, (b) 0.01 to 1 part by weight of a dibenzylidene sorbitol compound, and (c) the following general formula [LiAl ₂ (OH) ₆ ] ₂ X · mH _20. (Where X represents CO ₃ , SO ₄ or HPO ₄ , and m is a number from 0 to 3). A polypropylene composition comprising from 0.01 to 1 part by weight of a lithium aluminum salt represented by the following formula: