JPH08239525A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE: To obtain the subject composition excellent in transparency and mapping properties, having excellent formability improved in smell and bleeding during molding, and useful for sheet, film, etc., by compounding a crystalline polypropylene with a specific fluoropolymer and a sorbitol derivative. CONSTITUTION: This resin composition contains (A) 100 pts.wt. of a crystalline polypropylene, (B) 0.00001-1 pts.wt. of a fluoropolymer having a degree of crystallization of >=50% (e.g. an average primary-particle diameter of <=2μm, especially 0.01-1μm), (C) 0.01-0.5 pts.wt. of a compound of the formula (Rj and R. are each H, a halogen, a 1-8C alkyl or a 1-8C alkoxy), and optionally (D) 0.005-0.4 pts.wt. of talc having an average particle diameter of 0.1-10μm.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polypropylene resin composition containing a crystalline polypropylene, a fluorine-containing polymer having a crystallinity of at least 50%, and a small amount of a sorbitol derivative. A polypropylene resin composition containing a small amount of

[0002]

2. Description of the Related Art Polypropylene is a resin sheet having excellent mechanical properties, transparency, moldability and chemical stability.
It is widely used as a material for extrusion molded products such as films and blows, and injection molded products. However, transparency and image clarity are generally inferior to other highly transparent thermoplastic resins such as polystyrene and polyvinyl chloride due to the high crystallinity of polypropylene. Several proposals have been made so far in an attempt to improve the transparency of polypropylene. For example, by adding an organic nucleating agent such as a sorbitol derivative, an alkali metal salt of an aromatic carboxylic acid, or an aluminum salt to polypropylene, the spherulites of the molded product become smaller and uniform, and the transparency of the molded product is improved. It is known to be improved (JP-A-58)
-80392, JP-A-55-12460). In particular, the sorbitol derivative shows the effect of improving transparency, but when used alone, the compatibility of the sorbitol derivative with the polypropylene resin is small, and bleeding occurs during molding or in the molded body. Further, there is a problem that an odor is generated not only during the molding process but also from the molded body, and it is necessary to improve the transparency by adding as little amount as possible.

[0003]

In view of the above drawbacks, the present inventors have made extensive studies as to improvement of transparency, image clarity and moldability, and as a result, crystalline polypropylene has a crystallinity of at least 50% or more. By blending a fluoropolymer and a sorbitol derivative, and by further blending fine particle talc, the transparency, image clarity, and
The inventors have found that the workability is improved and have completed the present invention. That is, the present invention includes (A) 100 parts by weight of crystalline polypropylene, (B) 0.00001 to 1 part by weight of a fluoropolymer having a crystallinity of at least 50%, and (C) the following formula:

[0004]

Embedded image

(Wherein R ₁ and R ₂ are the same or different and each is a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 8 carbon atoms). A polypropylene resin composition containing 0.01 to 0.5 part by weight, and further,
(D) Talc with an average particle size of 0.1 to 10 μm 0.005
A polypropylene resin composition containing 0.4 parts by weight.

The crystalline polypropylene used in the present invention may be a homopolymer of propylene, a random copolymer of propylene and another α-olefin, or a mixture thereof. Examples of the other α-olefins include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-
Nonene, 1-decene, 4-methyl-1-pentene and the like can be mentioned. The content of these other α-olefins is preferably 10 mol% or less in order to maintain crystallinity.

The crystalline polypropylene used in the present invention is not particularly limited to the melt index, but when the moldability into various molded products is taken into consideration, the melt index is usually 0.01 to 100 g / 10 min. The range of 0.1 to 50 g / 10 minutes is more preferable. The polypropylene used in the present invention is crystalline, and the isotactic pentad fraction is usually 0.85 or more. The term "isotactic pentad fraction" as used in the present invention refers to A. Zambelli et al., Macromolecules, 6 , 925.
(1973), that is, the fraction in which 5 propylene units are continuously bonded to meso as measured by ¹³ C-NMR.

The isotactic pentad fraction is preferably in the range of 0.85-1 in the case of an injection molded product, and in the range of 0.85-0.94 in the case of a film. The molecular weight distribution of the crystalline polypropylene used in the present invention (the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (M
w / Mn)) is not particularly limited, but in order to improve fluidity during processing such as injection molding and prevent problems such as melt fracture, the molecular weight distribution is 2 to 20. Preferably there is. Further, considering the case of film formation, the molecular weight distribution is preferably 6 to 20 in order to increase the melt tension and improve the processability. The molecular weight distribution is a value measured by a gel permeation chromatography method (hereinafter, also referred to as GPC) using o-dichlorobenzene as a solvent, and a calibration curve calibrated with standard polystyrene is used. .

The fluorine-containing polymer used in the present invention must have a crystallinity of 50% or more. Crystallinity is 5
If it is less than 0%, the effect of making the fluoropolymer transparent and the effect of improving the image clarity are poor. The transparency-improving effect and the image-improving effect of the fluoropolymer in the present invention tend to be more effective as the crystallinity of the fluoropolymer is higher,
The crystallinity is preferably 50% or more, and further 7
It is more preferably 0% or more. The crystallinity of the fluoropolymer is determined by the J-ray X-ray diffractometer JDX3 manufactured by JEOL Ltd.
500, tube voltage-tube current 40KV-400mA
And monochromated Cu with a graphite monochromator
-Kα ray is used, the measurement condition is the reflection method, divergence slit 0.2 mm, light receiving slit 0.4 mm, diffraction angles 11 to 27.
°, step angle 0.04 °, counting time 1.0 seconds,
The peaks of the amorphous peaks observed at diffraction angles 2θ of 16 ° and 17.5 ° are totaled as S _A , and the peak area of the crystalline peak observed at 18 ° is calculated by separating the peaks of the diffraction intensity curve. When S _C, it is represented by the following formula S _C / (S _C + S _A ) × 100 (%).

The particle size of the fluoropolymer is not particularly limited, but in order to obtain a molded product having good transparency and image clarity,
The average primary particle diameter is preferably 2 μm or less, and more preferably 0.01 to 1 μm.

The fluorine-containing polymer that can be used in the present invention includes homopolymers of fluorine-containing monomers, copolymers of fluorine-containing monomers with each other, and copolymers of fluorine-containing monomers with hydrocarbon monomers, especially α-olefins. Etc. can be used. Examples of the fluoropolymer usable in the present invention include tetrafluoroethylene polymer, 1-fluoroethylene polymer, 1,1-difluoroethylene polymer, trifluoroethylene polymer, 1-chloro-2,2.
-Difluoroethylene polymer, chlorotrifluoroethylene polymer, hexafluoropropylene polymer, tetrafluoroethylene-methyl vinyl ether copolymer, tetrafluoroethylene-perfluorovinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene Examples thereof include copolymers.

The content of the fluoropolymer used in the present invention in crystalline polypropylene is crystalline polypropylene 1
The amount should be in the range of 0.0001 to 1 part by weight, preferably 0.000005 to 0.5 part by weight, and more preferably 0.0001 to 0.002 part by weight, based on 00 parts by weight. More preferable. When the content of the fluorinated polymer is less than 0.00011 parts by weight, the effect of improving transparency and image clarity is not observed. On the other hand, when the amount exceeds 1 part by weight, the elastic modulus of the molded product becomes too high, which causes problems such as an increase in the frequency of breakage of the molded product during extrusion molding, and the effects of the present invention on transparency and image clarity. No further improvement is seen and it is meaningless from an economic point of view. The sorbitol derivative used in the present invention is a compound represented by the following formula.

[0013]

[Chemical 4]

(Here, R ₁ and R ₂ are the same or different and each is a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms.)

Specific examples of R ₁ and R ₂ include an alkyl group such as a methyl group, an ethyl group, an n-propyl group and a t-butyl group, an alkoxy group such as a methoxy group, an ethoxy group and an n-propoxy group, or an alkoxy group such as an n-propoxy group. A halogen atom such as fluorine, chlorine or bromine, or a hydrogen atom is suitable.

Specific examples of the sorbitol derivative preferably used in the present invention include, for example, 1,3,2
・ 4-Dibenzylidene sorbitol, 1,3,2,4-
Di (p-methylbenzylidene) sorbitol, 1.3,
2,4-di (p-chlorobenzylidene) sorbitol,
Examples include 1,3,2,4-di (p-methoxybenzylidene) sorbitol and the like. The amount of the sorbitol derivative added should be in the range of 0.01 to 0.5 parts by weight with respect to 100 parts by weight of the crystalline polypropylene resin,
It is preferably 0.05 to 0.4 parts by weight, and most preferably 0.05 to 0.3 parts by weight.

The average particle size of talc used in the present invention must be in the range of 0.1 to 10 μm, and 0.5 to 8.
It is preferably 0 μm, and further 1.0 to 7.0 μm
Is more preferable. The average particle size of talc is 0.1
If it is less than μm, talc causes secondary aggregation and the aggregated particles become large, which is not preferable because it decreases the transparency of the molded body and causes fish eyes when molded into a sheet or film to deteriorate the appearance. On the other hand, when the average particle size exceeds 10 μm, voids are often generated when the film is formed and the transparency is deteriorated, which is not preferable. The method for measuring the average particle size of talc used in the present invention is not particularly limited, but a method using a Coulter counter, an electron microscope or the like is exemplified. As the talc used in the present invention, known products such as crushed products of natural products or synthetic products are used without limitation, and talc having high crystallinity and high crystallinity for polypropylene is preferred.

The content of talc in the crystalline polypropylene used in the present invention must be in the range of 0.005 to 0.4 part by weight, preferably 0.008 to 0.2 part by weight. And more preferably 0.01 to 0.1 part by weight. When the content of talc is less than 0.005 part by weight, the sufficient nucleating effect of talc cannot be obtained, and for example, edge roughening and spots are observed during sheet molding. vice versa,
If the amount exceeds 0.4 parts by weight, the transparency of the film is lowered and a defective appearance occurs due to the generation of voids.

There is no particular limitation on the method of incorporating the fluoropolymer, the sorbitol derivative and the talc into the crystalline polypropylene. Specifically, a fluorine-containing polymer, a sorbitol derivative, and further talc are added to crystalline polypropylene and mixed using various kneaders such as a uniaxial kneader, a biaxial kneader, rolls, and Brabender Plastograph. The method is common. In the above mixture, an additive for polypropylene usually used in the range where the effects of the present invention are not impaired, for example, an antioxidant, a dispersant, a lubricant, an antistatic agent, an antiblocking agent, a colorant, etc. are blended. Good.

As the molding method in the present invention, any molding method may be used as long as the effects of the present invention are not impaired, and specific examples thereof include injection molding, press molding, extrusion molding, stampable molding, blow molding and the like. . Usually, injection molding is generally used. This injection molding may be carried out by any method such as single axis injection, multi-axis injection, high pressure injection, low pressure injection, gas assist injection, melt core molding, insert molding, core back molding, two-color molding, foam molding and the like. Also, a sheet or a film that is not stretched can be manufactured by extrusion molding or rolling. It is also possible to obtain a stretched film by stretching in at least one axial direction by successive stretching.

[0021]

INDUSTRIAL APPLICABILITY The present invention has improved transparency and image clarity,
Provided is a polypropylene resin composition having improved moldability with improved odor and bleeding during molding. Therefore, the molded body obtained by using the polypropylene resin composition of the present invention,
It has excellent transparency and image clarity.

[0022]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. The polypropylene moldings obtained in the following examples and comparative examples were evaluated by the following methods. (1) Haze It was measured according to JIS K 6714. (2) Image value Using a Suga Test Instruments Co. image clarity measuring machine, an optical comb of 0.12
The image value of the molded body was measured using 5 mm. (3) Sorbitol derivative Sorbitol A; 1,3,2,4-di (p-methylbenzylidene) sorbitol Sorbitol B; 1,3,2
・ 4-Dibenzylidene sorbitol

Example 1 To 100 parts by weight of the homopolypropylene powder shown in Table 1, 0.1 parts by weight of 2,6-di-t-butylhydroxytoluene as an antioxidant and 0 of calcium stearate as a chlorine scavenger were added. .1 part by weight, tetrafluoroethylene polymer (trade name "Fluon Lubricant L-171J: crystallinity 78.7%, average primary particle size 0.2 μm, manufactured by Asahi ICI Co., Ltd.) 0.01 part by weight and sorbitol A0.
After adding 05 parts by weight and mixing with a Henschel mixer for 5 minutes, the mixture was extruded at 230 ° C. using an extrusion granulator having a screw diameter of 65 mmφ, and pellets were granulated to obtain raw material pellets.

Using the obtained pellets, a biaxially stretched film was prepared by the following method. Using a T-die sheet extruder with a screw diameter of 90 mmφ, feed the raw material pellets to 280
Extruded at 0 ° C., and formed into a sheet having a thickness of 2 mm with a cooling roll at 30 ° C. Then, this raw sheet was subjected to a longitudinal biaxial stretching device of a tenter system at 150 ° C. in the longitudinal direction to 4.6.
The film is stretched twice, and subsequently stretched in the tenter at 165 ° C. in the transverse direction by a mechanical ratio of 10 times, and then heat-treated with a relaxation of 8% to give a polypropylene biaxially stretched film having a thickness of 50 μm at a speed of 16 m / min. It was molded in. Haze was measured by stacking 5 sheets of this film. The mapping value was measured for this one sheet. The results are shown in Table 1.

Examples 2 to 6 The same procedures as in Example 1 were carried out except that the same homopolypropylene as in Example 1 was used and the fluorine-containing polymer and sorbitol A were used in the amounts shown in Table 1. The results are shown in Table 1.

Comparative Examples 1 to 4 The same operations as in Example 1 were carried out with the formulations shown in Table 1. The results are shown in Table 1.

[0027]

[Table 1]

Examples 7 to 9 The same procedure as in Example 1 was carried out except that the resin shown in Table 2 was used as the crystalline polypropylene used as the raw material, and the fluorine-containing polymer and sorbitol B were used and the composition shown in Table 2 was used. The results are shown in Table 2.

Comparative Examples 5 and 6 The same operation as in Example 7 was carried out except that the crystalline polypropylene used in Example 7 was used and the composition shown in Table 2 was used. The results are shown in Table 2.

[0030]

[Table 2]

Examples 10 to 12 Tetrafluoroethylene and sorbitol A were used as fluoropolymers using the crystalline polypropylene resins shown in Table 3.
Was carried out in the same manner as in Example 1, except that the talc having the particle size and the compounding amount shown in Table 3 was added. Here, the state of the original sheet of the film was also observed. The results are shown in Table 3.

Comparative Examples 7 to 10 Table 3 shows the results obtained in the same manner as in Example 10 except that the crystalline polypropylene used in Example 10 was blended with tetrafluoroethylene, sorbitol A and talc shown in Table 3. It was

[0033]

[Table 3]

[0034]

Claims (2)

[Claims] 1. (A) 100 parts by weight of crystalline polypropylene (B) 0.00001 to 1 part by weight of a fluoropolymer having a crystallinity of at least 50%, and (C) the following formula: (Here, R ₁ and R ₂ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, or
A polypropylene resin composition comprising 0.01 to 0.5 part by weight of a sorbitol derivative represented by the formula 1) which is an alkoxy group having 1 to 8 carbon atoms. 2. (A) 100 parts by weight of crystalline polypropylene (B) 0.0001 to 1 part by weight of a fluoropolymer having a crystallinity of at least 50% (C) The following formula: (Here, R ₁ and R ₂ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, or
0.01 to 0.5 part by weight of a sorbitol derivative represented by), which is an alkoxy group having 1 to 8 carbon atoms, and (D) 0.005 to 0.4 part by weight of talc having an average particle size of 0.1 to 10 μm. A polypropylene resin composition comprising: