JPS5852341A - Polypropylene composition - Google Patents

Abstract

PURPOSE:To provide a polypropylene composition with high stiffness and small warpage, by mixing an ethylene/propylene block copolymer, having a melt flow index below a specific value with a fibrous material. CONSTITUTION:Thermal decomposition or oxidative destruction with an organic peroxide (e.g., benzoyl peroxide) of an ethlene/propylene block copolymer gives an ethylene/propylene block copolymer, melt flow index rate, of the equation <=15, wherein MFIR stands for melt flow index rate and MFI2160 and MFI375 represent melt flow indexes when 7g of a sample is subjected to a load of 2,160g and 375g, respectively. Then, the resulting copolymer is mixed with a fibrous material such as glass fiber or carbon fiber to yield the purpose polypropylene composition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides high rigidity and small glue during molding.
The present invention relates to a polypropylene composition containing laminated substances.

In recent years, polypropylene has been used in electrical products and building materials.

It has been widely used in automobile parts and various mechanical parts.

In addition, for applications that require high rigidity, polypropylene containing various fillers is used, and when particularly high rigidity is required, polypropylene containing fibrous substances such as glass fiber or carbon fiber is used. be done.

However, the biggest drawback of such fibrous material-containing polypropylene is that it generates a large amount of glue during molding.

That is, polypropylene alone causes some degree of sagging, but when fibrous substances are included, the sagging becomes even greater.

This is because during molding, the fibrous material is oriented in various directions depending on the mold shape, molding conditions, etc.

For this reason, the shrinkage rate of the molded product is greatly influenced by the orientation of the fibrous material, and as a result of non-uniform shrinkage with respect to the mold, large glue is generated.

Although polypropylene containing fibrous substances has the feature of extremely high rigidity, its use in fields where dimensional accuracy is required is severely limited due to the drawback of generating large glue. There is.

As a result of various studies aimed at obtaining a polypropylene composition containing a fibrous material that has high rigidity and less warpage, the present inventors unexpectedly found that ethylene having an MFIR of 15 or less, which correlates with molecular weight distribution, - The intended purpose was achieved by using a propylene block copolymer. That is, polypropylene in the present invention is preferably used as ethylene topropylene.

In order to impart high stiffness in the polypropylene composition of the present invention, the la fibrous material content in the total composition is generally 3 to 60 x 1 by weight, preferably 5 to 50 x by weight. That is, if the content of the fibrous material is less than 6 parts by weight, sufficient rigidity cannot be imparted, and if it exceeds 600 parts by weight, the kneading operation becomes difficult and is not suitable for industrial use.

The main features of the present invention are 1. In order to suppress the generation of glue during molding of a polypropylene composition containing such a SaWa substance, an ethylene-propylene block copolymer having an MFIR of 15 or less, particularly 14 or less is used. Therefore, in order to obtain the polypropylene composition of the present invention, an ethylene-propylene block copolymer having an MFIR of 15 or less may be selectively used, or an ethylene-propylene block copolymer having an MFIR greater than 15 may be adjusted to 15 or less. It is necessary to use the Further, if a composition using an ethylene-propylene block copolymer having an MFIR of 15 or less causes stickiness during molding, the effect of suppressing warpage can be obtained by further reducing the MFIR of the skeleton copolymer.

In addition, the MFIR value of polypropylene in the present invention is determined by using a melt flow indexer (equipment).
2600 (preheating time 5 minutes) and load 2 respectively.
Melt flow index of 160f (MFI 216
0) and the melt flow index (MF
57s) and substituted it into the following equation.

MFI 375 Such an ethylene-brobylene block copolymer having an MFIR of 15 or less can be obtained not only by selecting a polymerization method, but also by a simple method, ethylene-brobylene block copolymer can be obtained by thermal decomposition or shear force. It is preferably obtained by a molecular cutting method, particularly a method of oxidative decomposition treatment using an organic peroxide. Particularly preferred is a method in which the ethylene-brobylene block copolymer is mixed with an organic peroxide and then melt-kneaded using an extruder. The organic peroxide used is, for example, benzoyl peroxide.

lauroyl peroxide, azobisinobutyronitrile, dicumyl peroxide.

α, α′-bis(1-butylperoxydiynpropyl)benzene 2,5-dimethyl-2,5-di(1-butylperoxy)hexane, 2,5-dimethyl-2,5-di(1 -butyl peroxide) hexyne-6, di-t-butyl peroxide, cumene hydroperoxide, 1-butyl hydroperoxide, and the like. Generally M
By adding 0.001 to 5.0 parts by weight, preferably 0.005 to 3.0 parts by weight, of the above organic peroxide to 100 parts by weight of polypropylene having an FIR of 15 or more, MFIR#f15 or less can be obtained. (7) Ethylene-propylene block copolymer can be obtained. However, if the amount of organic peroxide added is less than 0.001 part by weight, the MFIR of the ethylene-propylene block copolymer cannot be reduced to 15 or less, and if it is more than 5.0 parts by weight, the MFIR of the ethylene-propylene block copolymer cannot be reduced to 15 or less. It is difficult to handle because of the large rise in the mechanical strength, which is undesirable.

According to the present invention, high tensile strength and bending strength are imparted together by incorporating modified polypropylene grafted with unsaturated carmenic acids together with a fibrous substance into the above-mentioned ethylene-propylene block copolymer having an MFIR of 15 or less. A polypropylene composition is provided.

The modified polypropylene used is generally a propylene homopolymer, a copolymer such as a random or hive block copolymer of ethylene or the like and propylene, acrylic acid, methacrylic acid, maleic acid, or derivatives thereof. In addition, the blending ratio of modified propylene is generally 5 to 20 (by weight) in order to obtain the desired tensile strength and bending strength.
X, especially 1 to 15 (by weight)X. Other conventionally known stabilizers.

Flame retardant 1 Colorant, antistatic agent, lubricant, nucleating agent.

Or talc, calcium carbonate, or silica.

Kaolin, magnesium hydroxide, magnesium silicate,
@Barium acid, activated clay, mica.

Various fillers such as zeolite may be added as appropriate.

The method for obtaining the polypropylene composition of the present invention is not particularly limited, and may be an ethylene-propylene copolymer or fibrous material having an MPIR of 15 or less.

If necessary, it can be obtained by mixing with modified polypropylene. The ingredients may be mixed at the same time, or several types may be mixed in advance and the remaining components may be mixed later. Then, when pelletizing with an extruder, the extruder and screw shape are not particularly limited, and may be a single screw extruder, a twin screw extruder,
An extruder with a kneader is used.

Further, as the screw shape, a full flight type screw, a dalmage type screw, a high kneading type screw, etc. are used.

In particular, when high tensile strength, bending strength, and bending strength ratio are required, a single-screw extruder with a full-flight type screw is preferably used, which causes less cutting of the II fiber material. As a device for mixing the ingredients, commonly used devices such as a tumbler blender, a VG blender, a Henschel mixer, a ribbon mixer, etc. are used. Further, the desired product may be obtained by mixing an ethylene-propylene copolymer having an MFIR of 15 or more, a fibrous material, modified polypropylene if necessary, and an organic peroxide, and then pelletizing the mixture.

The polypropylene composition of the present invention maintains high rigidity and generates little glue during molding, but this is due to the small MFIR, that is, the small shrinkage rate of the ethylene-propylene block copolymer with a narrow molecular weight distribution. Although this is one of the factors that reduces the occurrence of warpage, it cannot be explained by this alone.It significantly suppresses the occurrence of warpage. Therefore, although the exact reason for this is not clear, it is presumed that, in addition to the low shrinkage rate, it has flow characteristics that orient the fibrous material to reduce warping.

EXAMPLES In order to explain the present invention more specifically, 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 warpage test for the polypropylene compositions shown in Examples and Comparative Examples was conducted at a diameter of 150 cm.

A 2-thick disk was injection molded under the following conditions (1) and heated to 26°C.
, after being left at a temperature of 50 years for 48 hours, as shown in Figure 1, the maximum left and right glue heights with respect to the plane are a1 + a2 h I! L51
a4 and the circle diameter t1 from the front (rotation). Each t2 was measured and these values were substituted into the following formula J) to determine the value of the glue.

Injection conditions (1) Injection type used: 8 copper 13oz injection machine Resin IL setting:
230°C Injection pressure: 400m4/- Injection speed f: 40m/sec Mold temperature = 40°C In the present example and comparative example, the number of measurements was 10 each, and the average value was entered.

Example 1 and Comparative Example 1 Using polypropylene blocked with ethylene (manufactured by Tokuyama Ittasha, hereinafter abbreviated as block PP) with a content of 2.5 to 2.9 (by weight) X shown in Table 1. , after mixing with the specified organic peroxide, one 65% extrusion machine (resin temperature 22
0° C.) to obtain pellets with MFIR of 15 or less.

Table 1 Note 1) Kayahexam D400 in Table 1 is a trade name manufactured by Kayaku Nouri Co., Ltd. and is made of 40% 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and 60% silica. A mixture of 1! Examples and comparative examples of the present invention are shown in which s-fibrous material was added to the ethylene-propylene block PP having an MFIR of 15 or less obtained in Table c1 and the following ethylene-propylene block PP having an MFIR of 15 or more.

As shown in Table 2, ethylene-bu-a-pyrene copolymers having various MFIR values are combined with glass fibers (manufactured by Nippon Glass Co., Ltd., product number Rgs-03-
Tp37).

Carmen fiber (manufactured by Toho Bethlon Co., Ltd., product number HT
Mu-06-8) and rock wool fiber (Nippon Steel Chemical Industry Co., Ltd., Varnish Fiber FF) were added in predetermined proportions (% by weight) and mixed in a tumbler blender. The mixture was then melted and kneaded using a 40-inch vent extruder (using a full-flight screw) to form pellets.

Each of the above pellets was molded into a test scissor piece using a 130Z injection molding machine according to 187MD-790, and the flexural modulus (k/cd) was measured. The tensile strength (h/-) and bending strength (Kt/j
) are jk8TM D65B, , D790 (
: Measured according to the following. The results are shown in Table 2.

Example 2 and Comparative Example 2 As shown in the HS table, a predetermined proportion (weight x ), and the same measurements as in Example 1 were performed. In addition, as the modified polypropylene, maleic acid-modified polypropylene (0.21 mol% maleic acid grafted to ethylene-propylene propylene copolymer) and acrylic acid-modified polypropylene (
It is a propylene homopolymer grafted with 5 moles of acrylic acid). The results are shown in Table 3.

[Brief explanation of drawings]

FIG. 1 shows a disk for measuring warpage in the present invention. The figure and figure U are front views of the front and back surfaces of the injection molded disc, respectively, with respect to the plane. al, a2
．． a3 and a4 are heights above the plane. Also, No. 9 is a plan view of a disk, where tl is the longest diameter and t2 is the length of the shortest diameter. Patent Applicant: Tokuyama Soda Co., Ltd. Nippon Steel Chemical Industry Co., Ltd. ￥1 Figure Procedure: Written by Masaru Nezu November 9, 1980 Director General of the Patent Office Shima 1) Tono Haruki t Indication of Case Patent Application No. 149760 of 1983 2. Title of the invention: Polypropylene composition 5 Relationship with the case of the person making the amendment Patent applicant (representative applicant) Address: 1-1-5, Mikage-cho, Tokuyama-shi, Yamaguchi Prefecture Number of inventions to be increased by the amendment: None 6 [Detailed description of the invention J column and "Drawings"] of the specification to be amended l Contents of the amendment (1) Detailed description of the invention column "Kayahexa AD400J""KayahexaAD40C!"
Correct to J. (ii) Page 12, line 8 from the bottom [Kayahexa ap4ooJ r Kayahexam D40CJ
Correct. [Phase] Page 13, line 14, “Correct 1 sozJ to r13ogj.” ■ Correct column 7 in Table 3, page 16, [Correct 2,9J to r 6.5 J. (2) Figure 1 is corrected as shown in the attached sheet.

Claims (1)

[Scope of Claims] 1) A polypropylene composition comprising an ethylene-propylene block copolymer having an MP R of 15 or less and an m composition; 2) An ethylene-propylene block copolymer having an MF R of 15 or less which is an organic The polypropylene composition according to claim WX1, which is obtained by treatment with peroxide 3) am! ! 4) The composition according to claim 1, wherein the fall material is glass fiber or Karl Jl #i fiber; Polypropylene composition comprising modified polypropylene grafted with saturated carboxylic acids 5) The polypropylene composition according to claim 4, wherein the unsaturated carboxylic acid is maleic acid or acrylic acid.