JPS6139338B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyolefin resin composition,
In particular, the present invention relates to a highly rigid polyolefin resin composition in which talc powder and calcium sulfate fine fibers containing no crystal water are blended into a polyolefin resin. By blending inorganic filler powder such as calcium carbonate and talc with polyolefin resin,
It is well known that heat deformation resistance, rigidity, etc. can be improved. However, although the above properties can be improved, there is a problem in that the static strength such as tensile strength and bending strength, fatigue strength, and creep strength are reduced. Further, as a method for improving the strength and rigidity of polyolefin resin, a method of blending glass fiber is well known. However, in this method, the glass fibers are arranged in one direction during molding, resulting in anisotropy in strength and elastic modulus. In the direction perpendicular to the alignment, the strength does not improve much. Further, if such anisotropy exists, cracks are more likely to occur in the drop impact test in the direction in which the glass fibers are arranged. On the other hand, when glass fiber is mixed, the glass fiber is damaged during kneading during molding.
In addition to reducing the reinforcing effect, the molding machine becomes more abrasive. Further, even when inorganic filler powder and glass fiber are blended, the glass fiber still causes a large amount of wear on the machine, and the breakage of the glass fiber during molding is further accelerated by the blend of the inorganic filler. The purpose of the present invention is to improve the drawbacks of the prior art as described above, and to provide a polyolefin resin composition that has good heat deformation resistance, rigidity, and strength, and has less fiber breakage during molding and less wear on molding machines. There is a particular thing. The polyolefin resin composition of the present invention includes 100 parts by weight of polyolefin resin and 5 to 70 parts by weight of talc powder.
It is characterized by consisting of 5 to 70 parts by weight of crystallized water-free calcium sulfate fine fibers having a diameter of 0.5 to 5 μm and a length of 10 to 300 μm. The reason for using a polyolefin resin is that this resin is a ductile material and is less susceptible to embrittlement when inorganic filler powder and fibrous filler are blended.
Polyolefin resins include polypropylene, polyethylene, copolymers of ethylene and propylene,
Or it refers to a blend of two or more of these.
In particular, polypropylene has high rigidity among polyolefin resins, and by blending inorganic filler powder and fibrous filler, it is easy to obtain practically appropriate ductility and rigidity. Further, polypropylene is crystalline, and crystallization progresses along the fibers, resulting in a large reinforcing effect. The reason for using talc is that it has good affinity with polypropylene, and the rate of improvement in rigidity is higher than when other inorganic filler powders are used. In particular, the stiffness improvement rate is high for those containing 80% or more of particles with a diameter of 0.05 to 0.5 μ. Note that the ratio here is based on the total number of particles. And diameter 0.05~
Among those containing 80% or more of particles with a diameter of 0.5μ, those containing 10% or more of particles with a diameter of 1μ or more inhibit the reinforcing effect of the calcium sulfate fine fibers described later, and the improvement in strength is somewhat reduced. However, the strength is significantly improved compared to the case where only talc powder is blended without completely impairing the reinforcing effect. Furthermore, the reason why the blending amount is set to 5 to 70 parts by weight per 100 parts by weight of the polyolefin resin is that if the amount is less than 5 parts by weight, the effect of improving the stiffness will hardly be obtained and the objective of the present invention cannot be achieved. This is because if it exceeds 70 parts by weight, the strength decreases significantly and the object of the present invention cannot be achieved. The reason for blending calcium sulfate fine fibers is to prevent a decrease in strength due to blending of talc powder. However, if the purpose is simply to prevent a decrease in strength, glass fiber may be added, but this has the drawbacks mentioned above. diameter
If calcium sulfate fine fibers with a size of 0.5 to 5 μm and a length of 10 to 300 μm are used, there will be less damage due to kneading during molding compared to glass fibers, and since the hardness is lower than that of glass, there will be less wear on the molding machine. Furthermore, if the diameter is 5 μm or more and the length is 300 μm or more, the fibers will be significantly damaged during molding, and strong anisotropy will appear in the molded product. On the other hand, if the diameter is 0.5 μm or less and the length is less than 10 μm, the reinforcing effect is inhibited by the talc powder, so it is not very useful for improving the strength, and it is also likely to cause secondary aggregation, resulting in poor dispersibility in the resin. The reason for using calcium sulfate fine fibers that do not contain water of crystallization is that if water of crystallization is contained, the water of crystallization will separate at temperatures below 200°C, which is undesirable as it will cause silver streaks on the surface of the molded product. be. The reason why the amount of calcium sulfate fine fibers is set to 5 to 70 parts by weight per 100 parts by weight of the polyolefin resin is that if it is less than 5 parts by weight, there is little improvement in strength and the purpose of the present invention cannot be achieved. This is because if 70 parts by weight or more is added, the anisotropy becomes strong and the object of the present invention cannot be achieved. In addition, the strength effect of calcium sulfate fine fibers is 0.5 to 1 mm in diameter.
μ, a length of 10 to 100 μ is best. In the above, the effects of talcum powder and calcium sulfate fine fibers were separately described. However, the feature of the present invention lies in the combined use of both. When talc powder and calcium sulfate fine fibers are used together,
In order to disperse the talc powder between the fine fibers and suppress the slippage between the fibers, compared to the case where the talc powder and the calcium sulfate fine fibers were individually blended in the same amount as the sum of the amounts of both, Increased rigidity. Furthermore, since talc powder disturbs the flow of resin during molding, it suppresses the unidirectional alignment of calcium sulfate fine fibers, thereby reducing the anisotropy inside the molded product. The above effects are extremely small when the amounts of talc powder and calcium sulfate fine fibers are each less than 5 parts by weight, and the object of the present invention cannot be achieved. On the other hand, if the blending amount of both is 70 parts by weight or more, the impact strength is significantly reduced, and the object of the present invention cannot be achieved. In addition, the improvement in rigidity and relaxation of anisotropy due to the synergistic effect of the talc powder and calcium sulfate fine fibers mentioned above is due to the size of the calcium sulfate fine fibers.
Even if the talc powder particles are too large, or conversely, the calcium sulfate fine fibers are too large compared to the size of the talc powder, they will become smaller. Regarding the particle size of both, talc powder contains more than 80% of particles with a diameter of 0.05 to 0.5μ, and 10% of particles with a diameter of 1μ or more.
If calcium sulfate fine fibers with a diameter of 0.5 to 1 μm and a length of 10 to 100 μm are used, the rigidity and strength will be greatly improved and the anisotropy will be reduced. This is because extremely fine talc powder is uniformly dispersed between the fibers, improving the apparent elastic modulus of the resin matrix and making it difficult for the polymers to slip between each other. The entire structure, including talc powder and calcium sulfate fine fibers, is covered with crystals, resulting in particularly high rigidity and strength. In addition, the direction of crystal growth is not only uniform because the molecular orientation and fiber arrangement during molding are disturbed by the presence of talc powder, but also because the direction of crystal growth around the talc powder becomes random. The anisotropy of the molded product is almost eliminated. As mentioned above, when talcum powder and calcium sulfate are used together, different effects can be obtained than when each is used alone. The composition of the present invention has a greater effect of improving rigidity, strength, and heat deformation resistance than when using equal amounts of each of talc powder and calcium sulfate fine fibers alone, and the composition has a greater effect on improving the stiffness, strength, and heat deformation resistance, and the inner structure of the molded product differs due to the fiber arrangement. There is almost no directionality. That is, the rigidity and heat deformation temperature are higher than when talc is used alone, and the decrease in strength that occurs when talc is used alone is prevented. Furthermore, the rigidity and heat deformation temperature are higher than when calcium sulfate fine fibers are used alone, the strength is the same, and anisotropy is hardly observed. Furthermore, when calcium sulfate fine fibers are used, unlike glass fibers, they are less likely to break during molding, so the reinforcing effect can be predicted in advance. There is also less wear on the machine. Calcium sulfate is a byproduct of anti-pollution measures that is often obtained when removing sulfur dioxide gas produced during oil combustion, and is currently in excess supply. Therefore, this can be effectively utilized. In addition, when the material is disposed of by incineration after use, the calorific value and soot are small, there is little damage to the incinerator, and the incineration residue can be used again as a filler. As described above, the composition of the present invention has superior properties compared to conventional polyolefin resin compositions containing inorganic fillers. This composition will be explained in detail in the following examples. Example 1 100 parts by weight of polypropylene, 50 parts by weight of talc powder with an average diameter of 1μ, an average diameter of 0.5μ, and a length of 10~
50 parts by weight of calcium sulfate fine fibers containing no crystal water of 50 μm were kneaded at 190° C. for 15 minutes using a mixing roll (Sakurai electric heating roll), and then pulverized. Then, a test piece was molded in accordance with JISK6871 using a 4.5-ounce injection molding machine manufactured by Toyo Kikai Kinzoku, and a tensile test was conducted in accordance with JISK9871.
In addition, an Izot impact test was conducted in accordance with JISK6911. The results are shown in Table 2. Examples 2 to 22 The compositions are shown in Table 1, and the properties are shown in Table 2. The production of the material and the measurement of material properties were carried out in the same manner as in Example 1. Comparative Examples 1 to 22 Material production and measurement of material properties were carried out in Example 1.
The same method was used as in the case of . The composition of the comparative example is shown in Table 3, and the characteristics are shown in Table 4. Comparative Examples 23 to 27 Comparative Examples 23 to 27 are cases where glass fiber and talc powder were combined, and the compositions are shown in Table 5 and the characteristics are shown in Table 6. A comparison between Tables 2 and 4 shows that the compositions of the present invention have superior properties compared to conventional compositions.

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[Table] Note that the actual kneading and production of materials is carried out using a crunching mixer, mixing roll, kneader, extruder, etc., but is not limited thereto.

Claims (1)

[Claims] 1 Polyolefin resin (A) 100 parts by weight, talc powder (B) 5-70 parts by weight, diameter 0.5-5μ, length 10-
A polyolefin resin composition comprising 5 to 70 parts by weight of calcium sulfate fine fibers (C) that do not contain 300 μm of water of crystallization.