JPS6365106B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a reinforced polypropylene composition,
More specifically, the present invention relates to a reinforced polypropylene composition with a good balance of rigidity and impact resistance. The technology of filling glass fibers for reinforcing thermoplastic resins is already well known, but even if this glass fiber reinforcement technology is applied to crystalline polypropylene, the affinity between crystalline polypropylene and glass fibers is insufficient. Due to the lack of properties, sufficient strength improvements cannot be obtained in various molded products. In order to solve these problems, techniques to improve the strength by surface treatment of glass fibers or addition of surfactants, etc. are known, but the improvement in strength is insufficient or It cannot escape from drawbacks such as the scope of application of the technology being limited to only a specific laminated form. As an invention intended to solve the above-mentioned problems, Japanese Patent Publication No. 15813/1983 describes an invention entitled "Production method of glass fiber reinforced polypropylene composition". This publication describes modified polypropylene obtained by melting and heating a mixture of crystalline polypropylene, a silane treatment agent, and an organic peroxide instead of crystalline polypropylene in the production of a glass fiber-reinforced polypropylene composition. A technique has been disclosed in which a reinforced plastic composition is obtained by melt-mixing the glass fibers, using surface-treated glass fibers as the glass fibers. The publication also states that the plastic molded products obtained by this technology have significantly improved tensile strength, bending strength, etc. compared to molded products obtained by the conventional technology, and also describes the molding method. It is stated that there are no restrictions. Although the above technology has sufficiently achieved the purpose of obtaining reinforced polypropylene molded products, on the other hand,
Another drawback is that the resulting molded product has poor impact resistance. Therefore, it cannot be said that the molded product obtained by the above technique is necessarily sufficient for applications that require both rigidity and impact resistance. The present inventors completed this invention as a result of carrying out research from various angles on reinforced polypropylene compositions suitable for obtaining molded products that have high strength and have a good balance between rigidity and impact resistance. did. Therefore, the present invention provides a reinforced polypropylene composition suitable for obtaining molded products having high strength and a well-balanced combination of rigidity and impact resistance. Modified polypropylene obtained by melting and heating a mixture of a crystalline ethylene-propylene block copolymer with a melt flow index of 1.0 or less, an organic silane compound having an ethylenically unsaturated bond, and an organic peroxide, and glass fiber. The gist thereof is a reinforced polypropylene composition obtained by melt-mixing the present invention and an aminosilane compound for surface treatment of glass fibers. The crystalline ethylene-propylene block copolymer used in the present invention has an ethylene content of 20% by weight or less, preferably 2 to 15% by weight,
The melt flow index obtained according to the measuring method specified in ASTM D-1238 is 1.0 or less, preferably 0.1 to 0.8. The modified polypropylene is produced by melting and heating a mixture consisting of the crystalline ethylene-propylene block copolymer, an organic silane compound having an ethylenically unsaturated bond, and an organic peroxide. In this invention, by using the above-mentioned specific crystalline ethylene-propylene block copolymer, a reinforced polypropylene composition which has high strength and further provides a molded article with a well-balanced rigidity and impact resistance. You can get things.
If the ethylene content and melt flow index of the crystalline ethylene-propylene block copolymer used to produce modified polypropylene are outside the above ranges, the impact resistance of molded products obtained using the reinforced polypropylene composition will be impaired. decreases,
It is not possible to obtain a molded product with a good balance between rigidity and impact resistance. The simplest melt heat treatment method for producing modified polypropylene includes a processing method in which the above mixture is passed through an extruder to produce pellets of modified polypropylene. The crystalline ethylene-propylene block copolymer used at this time is
It is desirable that the material does not contain additives that are decomposed by organic peroxides and cause color development and bad odors. The organosilane compound used for modifying the crystalline ethylene-propylene block copolymer in the present invention is
An organic silane compound having an ethylenically unsaturated bond such as a vinyl group, allyl group, or methacryloxy group, such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, or γ-methacryloxypropyltrimethoxysilane. , etc. In the present invention, the blending ratio of the organosilane compound having an ethylenically unsaturated bond is preferably in the range of 0.1 to 3 parts by weight based on 100 parts by weight of the crystalline ethylene-propylene block copolymer, and the more preferable range is It is 0.3 to 1 part by weight. In the present invention, the organic peroxide used in combination with the above-mentioned organosilane compound to produce modified polypropylene is one whose half-life is around the melting temperature of the crystalline ethylene-propylene block copolymer of 1 minute; Examples include tert-butyl peroxyacetate, tert-butyl peroxybenzoate, dicumyl peroxide and the like. The melt heat treatment operation is preferably carried out in such a way that all the added organic peroxides are decomposed during the heat treatment in order to prevent decomposition of various additives added later. In addition, when melting and heating a mixture consisting of a crystalline ethylene-propylene block copolymer, an organic silane compound, and an organic peroxide, the resulting modified polypropylene has a melt flow index of 30.
(g/10 minutes). This is because the impact strength of molded articles obtained using modified polypropylene having a melt flow index greater than 30 (g/10 minutes) is low. The melt flow index of modified polypropylene is based on the melt flow index of crystalline ethylene-propylene block copolymer, the content of organic peroxide in the mixture containing the crystalline ethylene-propylene block copolymer, and the melting rate of the mixture. Although it is determined by the heat treatment conditions, the temperature of the melt heat treatment is determined depending on the properties of the crystalline ethylene-propylene block copolymer used. The melt flow index of the modified polypropylene is preferably controlled by the amount of organic peroxide used, since it is preferable to take the time until the organic peroxide is no longer contained in the polypropylene. The amount of organic peroxide to be added varies depending on the type of organic peroxide, the melt flow index of the crystalline ethylene-propylene block copolymer, the melt flow index of the desired modified polypropylene, etc., so it must be determined uniformly. I can't, but
Generally, from about 0.1 to about 0.5 parts by weight per 100 parts by weight of crystalline ethylene-propylene block copolymer is preferred. If the amount added is less than this lower limit, the reaction between the crystalline ethylene-propylene block copolymer and the organosilane compound will not take place sufficiently, and therefore the physical properties of the composition obtained by the method of the present invention will not be improved. If the amount added is not sufficient and is greater than the above upper limit, the melt flow index of the modified polypropylene tends to increase, making it impossible to further improve the physical properties of the composition. In the present invention, a reinforced polypropylene composition is obtained by melt-mixing the modified polypropylene produced as described above, glass fibers, and an aminosilane compound for surface treatment of the glass fibers. In the present invention, the surface of the glass fiber is treated with an aminosilane compound. Examples of the aminosilane compounds used include α-aminoethyltriethoxysilane, γ-aminopropyltrimethoxysilane, α-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane, α-aminobutyltriethoxysilane, N −
Examples include β-aminoethyl-γ-aminopropyltrimethoxysilane. The amount of aminosilane compound is 100 parts by weight of glass fiber,
Preferably it is within the range of 0.05-3 parts by weight. The step of surface treating the glass fibers with an aminosilane compound may be carried out in advance before melt-mixing with the modified polypropylene, but in practice, untreated glass fibers and the aminosilane compound are melt-mixed with the modified polypropylene. Therefore, it is preferable to perform surface treatment and melt mixing in one operation. Specific treatment steps include a pretreatment method in which a water or alcohol solution of an aminosilane compound is added to processed mineral fibers and then dried, or an integral method in which the aminosilane compound is directly added when melt-mixing glass fibers to modified polypropylene. An example is a blending method. In implementing this integral blending method, in order to prevent the glass fibers from agglomerating due to the aminosilane compound, the modified polypropylene and the glass fibers are first melt-mixed to a uniformly dispersed state, and then the aminosilane compound is mixed. It is preferable to adopt a method of adding and melt-mixing again. There are no particular restrictions on the melt-mixing method; for example, commonly used kneading machines such as a single-screw or twin-screw extruder, a Banbury mixer,
Melt mixing operations using a container mixer, rolls, etc. can be used. In the composition of the present invention, the blending ratio (weight ratio) of the resin component, that is, modified polypropylene, and the filler component, that is, glass fiber is 50:50 to 95:5 (preferably
70:30 to 90:10) as appropriate. Note that the above blending ratio is based on the state of the glass fiber after it has been surface-treated with an aminosilane compound. If the amount of glass fiber in the total composition is less than 5% by weight, a sufficient reinforcing effect cannot be obtained, and if it exceeds 50% by weight, the physical properties and processability of the resulting composition are rather deteriorated. Although modified polypropylene alone may be used as the resin component of the composition of the present invention, a mixture of modified polypropylene and unmodified crystalline ethylene-propylene block copolymer may also be used.
This unmodified crystalline ethylene-propylene block copolymer may be the same as the crystalline ethylene-propylene block copolymer used as the raw material for modified polypropylene, or may be a different crystalline ethylene-propylene block copolymer. good. This unmodified crystalline ethylene-propylene block copolymer has an ethylene content of 20% by weight or less, preferably 2 to 15% by weight, and a melt flow index of 0.8 to 30, preferably 1 to 9. . In addition, the proportion of unmodified crystalline ethylene-propylene block copolymer in the resin component is 90%.
It is necessary that the amount is within % by weight. That is, the modified polypropylene accounts for at least 10% by weight of the resin component.
If the proportion of modified polypropylene is less than 10% by weight, it will be difficult to produce a molded article with a good balance between rigidity and impact resistance, which is the object of the present invention. The unmodified crystalline ethylene-propylene block copolymer may be introduced into the composition by premixing with the modified polypropylene and then melt-mixing with the glass fibers, or it may be introduced into the composition by melt-mixing the unmodified polypropylene without pre-mixing with the modified polypropylene. They may also be introduced into the composition by separate addition. The composition of the present invention may contain various known additives, other reinforcing agents such as asbestos, wallasnite, fillers such as calcium carbonate, mica,
It goes without saying that barium sulfate, magnesium hydroxide, talc, coloring agents, etc. can be added as long as they do not depart from the objectives and effects of the present invention. The reinforced polypropylene composition of the present invention having the structure described above can be used by injection molding, extrusion molding, blow molding,
It can be made into a molded article by common processing methods such as compression molding, roll processing, lamination molding, vacuum forming, pressure forming, and stamping. The polypropylene composition of the present invention, which is made into a molded article by processing as described above, has high tensile strength, bending strength, and hardness, and has excellent Izot impact strength. Therefore, the reinforced polypropylene composition of the present invention is particularly suitable for applications requiring high strength and a balance between rigidity and impact resistance, such as silencers and air cleaners. Next, Examples showing the method for producing the reinforced polypropylene composition of the present invention and the physical properties of the obtained molded products will be shown together with examples of molded products according to the prior art (comparative examples). In each example, "parts" and "%" mean "parts by weight" and "% by weight," respectively. Example 1-4 The ethylene content was 6%, the melt flow index (MI) was 0.35 (g/10 min), and tetrakis-[methylene 3-(3',5'-di-tert-butyl-4' −
Hydroxyphenyl) propionate] methane (trade name: Irganox 1010) 0.1 part and 2,6
γ-methacryloxypropyltrimethoxysilane (A) and tert-butyl peroxybenzoate (B ) are added in the amounts shown in Table 1, thoroughly mixed in a Henschel mixer, and then melted and heated in an extruder at a temperature of 220°C at the front of the cylinder.
Modified polypropylene pellets having the melt flow index (MI) shown in Table 1 were prepared.
Add 80 parts of this pellet to short glass fibers [Nittobo Co., Ltd.]
Co., Ltd., trade name: CS-6PE-401] was added thereto and mixed in a tumbler. This mixture was melt-kneaded in an extruder at a temperature set at 250°C at the front of the cylinder to form pellets. This pellet was injection molded to prepare a test piece, and its physical properties were evaluated. Tensile strength, bending strength and Izotsu impact strength are respectively
Measured according to ASTM D638, ASTM D790, ASTM D256. The results are summarized in Table 1. Wall thickness of injection molded composition in Example 1
Drop impact test of 2.5mm plate (500g steel ball, -30℃)
I did this. As a result, it was 45cm.

[Table] Example 5, Comparative Examples 1 to 2 The same procedure as Example 2 was carried out except that powdered crystalline ethylene-propylene block copolymers having different melt flow indices were used. The results are summarized in Table 2.

[Table] Examples 6-7 The same procedure as in Example 3 was carried out except that the proportions of modified polypropylene and short glass fibers were changed. The results are summarized in Table 3.

[Table] Example 8 Melt flow index obtained in Example 3
12 modified polypropylene with an ethylene content of 6% and a melt flow index of 3,
Tetrakis-[methylene 3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate] 0.1 part of methane and 2,6-di-tert-butyl-p
- 50 parts of pelleted crystalline ethylene-propylene block copolymer containing 0.1 part of cresol are mixed in a tumbler, then melted and heated in an extruder set at 220°C at the front of the cylinder to form a polymer mixture. Pellets were produced. Pellets of a reinforced polypropylene composition were obtained in the same manner as in Example 1 except that these pellets were used. A test piece was made by injection molding this pellet, and its physical properties were evaluated, and the tensile strength was 637Kg/cm ² and the bending strength was 930.
Kg/cm ² , Izot impact strength (notched, 23
℃) was 13.8Kg・cm/cm. Comparative Example 3 The same procedure as in Example 1 was carried out except that homopolypropylene having an MI of 0.8 (g/10 min) was used in place of the crystalline ethylene-propylene block copolymer. The modified polypropylene has an MI (g/10 min) of 27, a tensile strength (Kg/cm ² ) of 830, and a bending strength (Kg/cm ² ) of
1180, Izot impact strength (with notch) (23℃)
(Kg・cm/cm) was 8. Furthermore, the drop impact strength (cm) of this product was 15 cm.

Claims (1)

[Scope of Claims] 1. A mixture consisting of a crystalline ethylene-propylene block copolymer with an ethylene content of 20% by weight or less and a melt flow index of 1.0 or less, an organosilane compound having an ethylenically unsaturated bond, and an organic peroxide. A modified polypropylene with a melt flow index of 30 or less obtained by melting and heat treatment, and a glass fiber and an aminosilane compound for surface treatment of the glass fiber are melt-mixed ^. ) is 600 or more, bending strength (Kg/cm ² ) is 900 or more, and Izod impact strength (Kg/cm 2 ) is more than 900.
A reinforced polypropylene composition having both rigidity and impact resistance (cm/cm) of 13 or more. 2. The reinforced polypropylene composition according to claim 1, which is made by melt-mixing glass fibers whose surface has been previously treated with an aminosilane compound and modified polypropylene. 3 Unmodified ethylene content within 9 parts by weight per 1 part by weight of modified polypropylene, 20% by weight or less,
It is characterized by being obtained by adding a crystalline ethylene-propylene block copolymer with a melt flow index of 0.8 to 30 and melt-mixing glass fibers and an aminosilane compound for surface treatment of the glass fibers. A reinforced polypropylene composition according to claim 1.