JPH0361685B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a highly rigid polypropylene injection molded article. Polypropylene molded products are heat resistant, chemical resistant,
It has excellent electrical properties, and injection molded products also have good rigidity, tensile strength, and processability. However, depending on the specific use of the injection molded product, these properties may not be sufficient, which limits the expansion of specific uses. In particular, regarding rigidity, injection molded products using crystalline polypropylene (hereinafter referred to as polypropylene) are slightly lower than injection molded products using polystyrene or ABS resin, so this is important for expanding the specific applications of polypropylene in this field. It has become a bottleneck. If it were possible to further improve the rigidity of polypropylene injection molded products compared to conventional ones, in order to maintain the same strength of the molded product, it would be possible to make the molded product thinner by the amount corresponding to the increased rigidity. Become. This is not only desirable from the viewpoint of resource saving, but also allows the cooling time during molding to be shortened by making the wall thinner. Therefore, it is possible to improve the injection molding speed per unit time, contributing to labor saving and productivity improvement. Conventionally, the following two methods are known as methods for improving the rigidity of polypropylene molded articles using additives. One is the use of organic nucleating agents such as aluminum para-tertiary butyl benzoate or (1.3)(2.4) dibenzylidene sorbitol. However, since the use of these materials is expensive, it is not economical even when used in small quantities, and they also reduce the gloss of injection molded products.
It has the disadvantage that physical properties such as impact strength and tensile elongation are significantly reduced. Another is the use of inorganic fillers such as talc, calcium acid, barium sulfate, mica, asbestos or calcium silicate. However, since the amount of these substances added is a considerable proportion (for example, 10 to 50% by weight) to the polypropylene, the unique characteristics of polypropylene, such as light weight and transparency of injection molded products, are impaired. Moreover, as with organic nucleating agents, gloss,
Impact strength and elongation are also reduced. The present inventors have made extensive research into polypropylene injection molded products that do not have the drawbacks associated with the aforementioned methods for improving the rigidity of the molded products. As a result, the present invention was developed with the knowledge that by using polypropylene having an isotactic pentad fraction limited according to the present invention described below, a highly rigid injection molded product can be obtained without using any special additives. completed. Such polypropylene is covered by a patent application filed by the same applicant filed on the same date as the present application.
It can be produced by the method described in the specification of No. 56-204066. That is, in this method, an organoaluminum compound () or a reaction product () of an organoaluminum compound () and an ether is converted into titanium tetrachloride.
The solid product () obtained by reacting the solid product () with (C) is further reacted with ethers and titanium tetrachloride (C), and the solid product () obtained by reacting with dialkyl aluminum monohalide and aromatic carboxylic acid ester ( ), the molar ratio of the aromatic carboxylic acid ester and the solid product ()/=0.2 to
This is a method for producing polypropylene, which is characterized by polymerizing propylene in the presence of a catalyst with a concentration of 10.0%. As is clear from the above description, an object of the present invention is to provide a polypropylene injection molded product that has high rigidity and can be used for more specific applications or made thinner. Other objectives will become apparent from the description below. The present invention is characterized in that (1) the isotactic pentad fraction (P) and the melt flow index (MFR) have a relationship of 1.00P0.015logMFR+0.955...A, and boiling n-hexane and boiling n-heptane The isotactic pentad fraction (P) of the extracts extracted sequentially with
0.450 to 0.700 and 0.750 to 0.930, and (2) a molded product according to item (1) above, which is made by using an inorganic filler in combination. The structure and effects of the present invention will be explained in detail below. What is isotactic pentad fraction (P)?
It is the isotactic fraction of pentad units in the polypropylene molecular chain, macromolecules 8
687 (1975). In this measurement method, ¹³ C-NMR
use. The requirement of the above formula A is that the fraction P of polypropylene with a low MFR generally decreases, so the requirement for the polypropylene to be used limits its decreasing effect. Since P is a fraction, the upper limit is 1.00. The next boiling n-hexane extract is usually contained in polypropylene in a few percent, but this fraction can vary widely, for example from 0.10 to 0.70, depending on the propylene polymerization method. . This extract in the polypropylene used in the present invention has a P of 0.450.
Must be within the range ~0.700. If it is less than 0.450, the rigidity of the injection molded product of the present invention (hereinafter referred to as the product of the present invention) may be improved, but on the other hand, the effect of improving other physical properties of the product of the present invention, such as hardness and heat distortion temperature, is insufficient. It is. In fact, the fraction P of the boiling n-heptane continuous extract refers to the portion of the polypropylene used in the invention which has been further extracted with boiling n-hexane to remove the extraction residue. This extractable fraction in the polypropylene used in this invention must have a P in the range of 0.750 to 0.930.
If it is less than 0.750, the stiffness of the product of the present invention may be improved, but on the other hand, the same drawbacks as in the case of the boiling n-hexane extract described above arise in other physical properties of the product of the present invention. The total extraction amount of the sequential extractions with boiling n-hexane and boiling n-heptane is not limited.
However, the total amount in the raw polypropylene is actually in the range of 1.0 to 10.0% by weight in most cases, and polypropylenes within this range give more preferable results than those outside this range. The above-mentioned sequential extraction is performed as follows. That is, a granulated product made by mixing a small amount of heat stabilizer (Note, for example, 0.1% 2.6-di-tert-butyl-para-cresol) with polypropylene powder and granulating it with an extruder is pulverized with a pulverizer. The crushed product was passed through a 20-mesh (Tyler) sieve, and 3 g of the passed through was first boiled into 100 ml using a Soxhlet extractor.
-hexane and then with 100 ml of boiling n-heptane for 6 hours each, and each extracted fraction is precipitated, dried and weighed. Furthermore, MFR is measured at 230°C and a load of 2160g according to the method of JISK7210. The present invention can be widely applied to various polypropylene injection molded products, and can exhibit its high rigidity.
The injection molded product of the present invention can be made thinner than conventional equivalent products, or can be applied to specific fields where conventional injection molded products using polystyrene or ABS resin could not be replaced. The polypropylene resin used in the present invention can be further increased in rigidity by adding known additives (note: the above-mentioned organic nucleating agent or inorganic filler) for increasing rigidity. The present invention will be explained below with reference to Examples. The methods for measuring various physical properties in each Example and Comparative Example were as follows.

[Table] Examples 1 to 3, Comparative Examples 1 to 3 4 kg of polypropylene powder having each MFR and each isotactic pentad fraction shown in Table 1 below, 0.004 kg of phenolic heat stabilizer, and 0.004 kg of calcium stearate. and mix for 10 minutes at room temperature using a high-speed stirring mixer (Note: Henschel Mixer, trade name), and then pour the mixture into a screw with a diameter of 40 mm.
It was granulated using an extrusion granulator. Next, the granulated material was heated to 230°C and a mold temperature of 230°C and an injection molding machine, respectively.
A JIS type test piece was prepared at 50°C, and the test piece was conditioned for 72 hours in a room with a humidity of 50% and a room temperature of 23°C. Then, physical property values were measured as shown in Table 1 below.

【table】

[Table] As is clear from the above table, the product of the present invention obtained by injection molding using polypropylene whose isotactic pentad fraction P is within the range of the present invention is as follows:
Regarding the physical properties of molded products I to H in the same table, I.
17000, b. 460, c. 360 each Kgf/cm ² , d. 110
(R-scale) and E. The test pieces obtained using the polypropylenes of Comparative Examples 1 to 3, which have physical property values of 117°C or higher but have isotactic pentad fractions outside the range of the present invention, did not meet any of the above items I to E. It is also not as good as the product of the present invention. Since the polypropylenes of Comparative Examples 1 to 3 are equivalent to currently commercially available polypropylenes, it is clear that the highly rigid injection molded article of the present invention cannot be obtained with such commercially available products. Examples 4 and 5, Comparative Examples 4 to 7 Examples 1 to 3 were carried out in the same manner as in Examples 1 to 3, except that polypropylene powders having each MFR and each pentad fraction shown in Table 2 below were used. Quality of polypropylene used and injection obtained

[Table] Table 2 shows the physical properties of the molded product. As is clear from the table above, the products of the present invention obtained using polypropylene whose isotactic pentad fraction P is within the range of the present invention are as follows:
It has the physical property values of A to E in the same table at the same level as No. 3. On the other hand, for Comparative Examples 4 and 5, in which none of the three isotactic pentad fractions P satisfies the requirements of the present invention, the above-mentioned Comparative Example 1
Similarly to cases 3 to 3, none of the physical property values A to E above are at the level of Examples 1 to 5. On the other hand, Comparative Examples 6 and 7 have slightly different effects. That is, in these comparative examples, the isotactic pentad fraction P for all polymers is
Perhaps in order to satisfy the requirements of the present invention, physical property values A to C in Table 2, that is, flexural modulus and bending strength, can be maintained at the level of the present invention, but physical property value D, that is, hardness and HDT, can be maintained at the level of the present invention. Neither Comparative Examples 6 nor 7 could maintain the level of the present invention. Example 6, Comparative Example 8 Same polypropylene as Example 2 (Example 6) and same polypropylene as Comparative Example 2 (Comparative Example 8)
The same procedure as in Examples 1 to 3 was conducted except that 0.04 kg of finely powdered talc having an average particle size of 2 to 3 μm was added per 4 kg of polypropylene. The results are shown in Table 3 below. As is clear from the table, by adding a small amount of talc, the various strengths of injection molded products are significantly improved compared to the corresponding cases without additives (Example 2, Comparative Example 2). , indicating that the combined use of inorganic fillers is effective. However, none of the physical property values of Comparative Example 8 were as good as those of the corresponding Example 6, indicating that the requirements of the present invention (three types of isotactic pentad fractions P) for the polypropylene used are essential. ing. Example 7, Comparative Example 9 The same procedures were carried out in Example 6 and Comparative Example 8 except that 0.016 kg of tert-butylbenzoate aluminum salt was used in place of talc (the former was used in Example 7, the latter was used in Comparative Example 9), the results are shown in Table 3 below. As is clear from the table, by adding a small amount of talc, the various strengths of injection molded products are significantly improved compared to the corresponding cases without additives (Note, Example 2, Comparative Example 2). shows that the combined use of an organic nucleating agent is effective. However, none of the physical property values of Comparative Example 9 are as good as those of the corresponding Example 7, and the requirements of the present invention (three types of isotactic pentad fractions P) for the polypropylene used are within the predetermined range. This shows that it is essential.

[Table] Comparative Examples 10 to 13 Example 41 (Comparative Example 10), Example 42 (Comparative Example 11), Example 43 (Comparative Example 12), and Example of JP-A-56-120712
The same procedure as Examples 1 to 3 was carried out except that the polypropylene obtained in Comparative Example 13 was used. The results are shown in Table 4 below. As is clear from the table, Comparative Examples 10 to 10 have isotactic pentad fractions outside the range of the present invention.
The test piece obtained using polypropylene No. 13 was not as good as the product of the present invention in terms of flexural modulus shown in the same table. Therefore, it is clear that a highly rigid molded article equivalent to that of the present invention cannot be obtained by the manufacturing method described in JP-A-56-120712. In addition, the main points in Japanese Patent Publication No. 1-48922 (Japanese Patent Application No. 56-204066) concerning the method for producing an α-olefin polymer of JP-A-56-120712 and the method for producing high-rigidity polypropylene used in the present invention The difference in production method is that in the former method, a solid product () is used in combination with an organoaluminum compound, an α-olefin, and a reaction product of an organoaluminum compound and an electron donor to preactivate the catalyst. On the other hand, in the latter case, the solid product () is combined with a dialkyl aluminum monohalide and an aromatic carboxylic acid ester (), and the molar ratio of the aromatic carboxylic acid ester and the solid product () is V/=0.2~ There is a clear difference in the use of "catalysts with 10.0". The method for producing polypropylene used in Comparative Examples 10 to 13 is shown below. Examples 40 to 44 of JP-A-56-10712 Example 40 800 ml of n-hexane and diethyl aluminum monochloride were placed in a stainless steel reactor with inclined blades.
2880 mg, 540 mg of the solid product obtained in Example 1 ()
was added at 20℃, propylene partial pressure 1.5Kg/cm ² G
Propylene was reacted for 7 minutes at 20°C (14 g of propylene reacted per 1 g of solid product), and after purging unreacted propylene, 200 g of n-hexane was added.
419 mg of the reaction product (G) obtained by reacting 181 mg (1.59 mmol) of triethylaluminum and 238 mg (1.59 mmol) of methyl p-toluate ((G) molar ratio 1.0) at 20°C for 3 hours in was added to obtain a preactivated catalyst. Subsequently, 7200 ml of hydrogen was added, and a gas phase polymerization reaction was carried out at a propylene partial pressure of 22 Kg/cm ² G and a polymerization temperature of 70° C. for 2 hours. After the reaction was completed, 48 g of methanol was added and the reaction was carried out at 70°C for 1 hour, then cooled to room temperature (20°C) and dried to obtain a polymer. This polymer was pressed at 200℃ for 3 minutes at 10Kg/cm ² G, the resulting film was cooled with water, and then pressed at 120℃ at 135℃.
After annealing for a minute, Luongo's method (JP
Luongo, J. Appl. Polymer Sic., 3302 (1980)), the IR-τ was measured, and the flexural modulus was measured according to JIS K-7203. In addition, other measured values were obtained in the same manner as in Example 1. Examples 41-44 Example 40 was repeated except that the amount of methyl p-toluate used in the preparation of reaction product (G) was as follows for each example. Example 41 477 mg (3.18 mmol) ((G) molar ratio 2.0, (G) amount 658 mg) Example 42 119 mg, (0.79 mmol) ((G) molar ratio 0.50, (G) amount 300 mg) Example 43 60 mg ( 0.4 mmol) ((G) molar ratio 0.25, (G) amount 241 mg) Example 44 36 mg (0.24 mmol) ((G) molar ratio 0.15, (G) amount 217 mg)

【table】

Claims (1)

[Scope of Claims] 1. A solid product () obtained by reacting an organoaluminum compound () or a reaction product () of an organoaluminum compound () with an ether () with titanium tetrachloride (C), and further containing an ether. A solid product obtained by reacting titanium tetrachloride (C) with a dialkyl aluminum monohalide and an aromatic carboxylic acid ester (C) is combined with the aromatic carboxylic acid ester and the solid product (C). It is obtained by polymerizing propylene in the presence of a catalyst with a molar ratio of / = 0.2 to 10.0, and the isotactic pentad fraction (P) and melt flow index (MFR) are 1.00>P>0.015. There is a relationship of log MER + 0.955, and boiling point n-hexane and boiling n-hexane
- Isotactic pentad fraction (P) of extracts sequentially extracted with heptane is 0.450~
A highly rigid polypropylene injection molded product using crystalline polypropylene having a molecular weight of 0.70 and 0.750 to 0.930. 2. The molded product according to claim 1, which is formed by using an inorganic filler in combination.