JPH0314866B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a propylene resin composition that has excellent light-shielding properties and is capable of producing white molded products having excellent physical properties such as rigidity and heat deformation resistance. In recent years, thermoplastic resins have come to be used as materials for cases of various optical indicators, including automobile meter boxes, lamp housings, and the like. In the above applications, the most important requirement is that the material has high light-shielding properties. For example, regarding the lamp housing, the inside of the housing is divided into multiple rooms by partitions made of the material, but if the material has poor light shielding properties, light from the display light source may Light leaks into neighboring sections, obscuring the display. Therefore, in the past, the thermoplastic resin used as the material was colored gray, black, light green, etc. in order to improve the light-shielding property. However, the colored thermoplastic resin has a drawback that the light reflectance is low and the display is dark. On the other hand, in order to improve the reflectance, it is possible to add a white pigment to the thermoplastic resin, but in this case, the light-shielding property is low, and in order to provide sufficient light-shielding property, it is necessary to thicken the molded body. Therefore, it is not necessarily an advantageous method from the standpoint of reducing the weight and cost of molded products. Alternatively, a method of painting white on the surface of the molded product that has been given light-shielding properties by coloring may be considered, but this method complicates the process and is industrially disadvantageous. Therefore, the development of a thermoplastic resin composition capable of producing a white molded product with high light-shielding properties has been a major challenge for a long time. The present inventor has already proposed a thermoplastic resin composition that can obtain white molded products with improved light-shielding properties by using titanium oxide together with talc containing a specific iron content (Japanese Patent Laid-Open No. 56-109235 issue). According to the above composition, the light-shielding properties of the resulting molded product are improved to some extent, but there is still room for further improvement. Also,
The molded product has poor physical properties such as rigidity and heat deformation resistance, and although it has good light-shielding properties, it has been limited in terms of strength from making the molded product thinner. Therefore, the development of a thermoplastic resin composition that can produce a white molded product that has high light-shielding properties, high rigidity, and high heat distortion temperature has become an important technical issue. As a result of intensive research into solving the above problems, the present inventors have found that a molded article using a propylene resin composition containing specific amounts of a titanium oxide glass filler and talc has excellent light shielding properties and high rigidity. The present inventors have discovered that the propylene resin composition has both a high heat distortion temperature and a high heat distortion temperature, and also has good fluidity during molding, and has completed and proposed the present invention. The present invention uses 2 to 100 parts by weight of titanium oxide and 0.1 to 100 parts by weight of glass filler to 100 parts by weight of propylene resin.
This propylene resin composition contains 160 parts by weight and 5 to 200 parts by weight of talc, and the proportion of talc in the total amount of glass filler and talc is within the range of 20 to 99.5% by weight. As the propylene resin used in the present invention, known propylene homopolymers and propylene-ethylene copolymers can be used, and propylene homopolymers and propylene-ethylene block copolymers are particularly preferably used. The titanium oxide is not particularly limited, and any commercially available titanium oxide may be used. The blending amount of titanium oxide is 2 to 100 parts by weight per 100 parts by weight of propylene resin.
parts by weight, preferably 3 to 50 parts by weight. When titanium oxide is used as a general pigment, the amount is usually 1 part by weight or less, which is sufficient. However, if it is used for the purpose of light-shielding properties in addition to whiteness, the above lower limit value or higher is required; below the lower limit value, sufficient light-shielding properties cannot be obtained due to the synergistic effect with the glass filler and talc described later. do not have. Furthermore, if the amount of titanium oxide is more than the above upper limit, kneading and pelletizing using an extruder becomes difficult when producing a propylene resin molded product, which is not industrially suitable. The glass filler is not particularly limited as long as it has a shape that can be filled into the thermoplastic resin, and examples include commercially available glass fibers, glass beads,
Glass powder, glass balloons, etc. are commonly used. In particular, glass fibers exhibit excellent light-shielding properties due to the synergistic effect with the titanium oxide described above and talc described below, and are also particularly effective in improving rigidity and heat deformation resistance, so they are preferably used. The glass fibers preferably have a diameter of 5 to 20 μm and a length of 1 to 10 mm, particularly those with an L/D of 100 or more. Generally, glass is transparent and does not have light blocking properties. In fact, even if the above-mentioned glass-based filler is added alone to a thermoplastic resin, no light-shielding property is observed at all. However, surprisingly, when this is used in combination with titanium oxide and talc, the light-shielding property is much improved compared to using the same amount of titanium oxide and talc. The reason for this is not clearly understood, but the incident light is refracted by the glass-based filler and scattered in various directions, increasing its effective transmission distance. It is interpreted that this is due to reflection and absorption. The blending amount of the glass filler is 0.1 to 160 parts by weight, preferably 0.5 to 130 parts by weight, and more preferably 3 to 120 parts by weight, based on 100 parts by weight of the propylene resin.
Parts by weight. If the amount of the glass filler is lower than the lower limit, sufficient light shielding properties, rigidity, and heat deformation resistance cannot be obtained. Furthermore, if the blending amount of the glass filler is more than the above upper limit, not only will it be difficult to knead and pelletize using an extruder when producing a thermoplastic resin molded product, but the impact strength of the molded product will also decrease. This is not preferable because it also has the disadvantage of doing so. In the present invention, talc works synergistically with the titanium oxide and the glass filler, and not only gives the resulting molded product excellent light-shielding properties, rigidity, and heat deformability, but also improves the composition of the glass filler. It prevents a decrease in fluidity when the propylene resin is melted, and is extremely effective in improving the moldability of the propylene resin composition. Commercially available talc can be used without any particular restrictions, but in order to improve the light-shielding properties, it is necessary to add iron.
0.4% by weight or more, especially 0.5 to 2.5% by weight in terms of Fe ₂ O ₃
Preferably, those containing The amount of talc to be blended is 5 to 200 parts by weight, preferably 10 to 160 parts by weight, and more preferably 10 to 160 parts by weight, based on 100 parts by weight of the propylene resin.
~120 parts by weight, and the proportion of talc in the total amount of the glass filler and talc is 20 to 99.5% by weight, preferably 30 to 80% by weight. If the amount of talc blended is less than the above range, or if the proportion of talc is less than the above range, it will not only be difficult to improve the fluidity of the resulting propylene resin composition, but also the effect of improving light shielding properties will not be sufficient. .
On the other hand, if the amount of talc added is greater than the above range, or the proportion of talc is greater than the above range, the stiffness and heat deformability will be significantly reduced. That is, the intended purpose of the present invention can be achieved by satisfying the above blending amounts and ratios. In addition, in the propylene resin composition of the present invention,
The total amount of titanium oxide, talc and glass filler is preferably 220 parts by weight or less, particularly 180 parts by weight or less, based on 100 parts by weight of the propylene resin. As is clear from the above description or from the Examples and Comparative Examples described later, the propylene resin composition of the present invention has high moldability, extremely excellent light shielding properties, high whiteness, and rigidity and A white molded product with high heat deformation resistance can be obtained. Therefore, the thickness of the molded body obtained can be reduced, and the weight and cost of the molded body can be reduced. Furthermore, as a white product, it can be used as is without any treatment such as painting, which brings great industrial benefits. The propylene resin composition in the present invention basically consists of the propylene resin, titanium oxide, talc, and glass filler, but in addition to these components, conventionally known stabilizers, colorants, antistatic agents, We add lubricants, nucleating agents, flame retardants, various other organic and inorganic fillers, and coupling agents between glass and propylene resin such as maleic acid, itaconic acid, acrylic acid, and chlorosulfonic acid. It's okay. EXAMPLES In order to explain the present invention more specifically, Examples and Comparative Examples will be described below, but the present invention is not limited to these Examples. The experimental results shown in the Examples and Comparative Examples were obtained using the following experimental method. () Preparation of test sample Resin is placed in a mold and heated and melted, then cooled under pressure to form a tapered shape from one end to the other end with a width of 80 mm, a length of 120 mm, and a maximum thickness of 10 mm in the length direction. A plate-like product is produced. The top view of the sample is
A cross-sectional view is shown in FIG. 1A, and FIG. 1B is a cross-sectional view. () Light-shielding test device A light-emitting device shown in FIG. 2 was used. That is, FIG. 2a is a plan view of the light emitting device, and FIG. 2b is a sectional view thereof. A slit 2 is provided in the upper part of a box 1 of the light emitting device, and a 12V, 3.5W light bulb 3 is provided inside the box 1, and the light bulb is connected to a 12V power source 4 via a switch 5. When the switch is turned on, the light bulb emits light and the light is emitted through the slit 2. () Light-shielding test method In a dark room, place the sample plate on the slit provided at the top of the box of the light-shielding test device, as shown in the cross-sectional view in Figure 3b, and move it from the A side to the B side in Figure 3. The plate-shaped object is moved towards the target. Figure 3a shows a plan view. With the switch on, move the plate while observing the presence or absence of light transmission from above, and with the light blocked, turn the switch on and off to make the light blink, and see if you can feel the blinking. We have carefully determined whether In this way, the minimum thickness with light-shielding properties was determined, and that thickness was measured with a micrometer, and this value was indicated as the light-shielding limit thickness. Further, the talc used in Examples and Comparative Examples is as follows. In other words, A grade has an iron content of 0.2% (whiteness 92) converted to Fe ₂ O ₃ , and B grade has an iron content of 0.5% (whiteness 92) converted to Fe ₂ O ₃ .
85) and C grade had an iron content of 1.5% (whiteness 79) calculated as Fe ₂ O ₃ . Furthermore, the brightness of the sample was measured using a color difference meter (Suga Test Instruments).
Co., Ltd.) to measure the L value and display the L value. () Flexural modulus Conforms to ASTM-D790. () Heat distortion temperature Compliant with ASTM-D648. The test was conducted at a load of 18.6 kg/cm ² . () Melt Index (MI) Conforms to ASTM-D1238. Example 1 Homopolypropylene with MI=9 (Tokuyama Soda Co., Ltd.)
Titanium oxide (DuPont R101) Glass fiber (Asahi Glass Fiber Co., Ltd. 03MA486A diameter 10-15μ, length approximately 3mm)
and talc (C grade) were mixed together with a heat stabilizer in a tumbler blender so that the proportions shown in Table 1 were obtained. The heat stabilizer is 2,6-di-
tert-butyl-4-methylphenol, dilaurithiopropionate, and calcium stearate, each based on 100 parts by weight of the polypropylene.
They were added in amounts of 0.1 parts by weight, 0.2 parts by weight, and 0.1 parts by weight. Next, the above mixture was melt-kneaded using a 40 m/m vented extruder to form pellets. This pellet was placed in a mold, melted by heating at 230°C for 15 minutes, and then cooled under pressure to prepare a test sample as shown in FIG. The light-shielding properties of this test sample were measured using the method described above. The results are also listed in Table 1. Also
Using an 80z injection molding machine, a colored plate for L value measurement and a test piece for bending test and heat distortion temperature measurement were created.
The L value, flexural modulus, heat distortion temperature, and melt index of these test samples were measured using the methods described above. The results are also listed in Table 1. Table 1 No. 9 shows that when the amount of titanium oxide blended in the propylene resin of the present invention is smaller than the amount specified in the present invention, the light shielding thickness is thick and the purpose is achieved. Show what you can't do. In contrast, Table 1 No. 3 and
No. 10 shows that even when the amount of titanium oxide mixed is varied, the light-shielding thickness is improved when the amounts of the three components mentioned above are the same. However, Table 1 No. 17 shows that melt-kneading cannot be performed if the amount of titanium oxide exceeds the range of the present invention. On the other hand, Table 1 No. 8 is a comparative example in which only titanium oxide was blended with the propylene resin of the present invention, and the results showed that the light shielding thickness was thick and the flexural modulus, heat distortion temperature, and melt index were each inferior. It shows. Table 1 No. 1 is a comparative example in which the glass fiber was removed from the propylene resin composition of the present invention, and the results show that the light shielding thickness is large and the heat distortion temperature is poor. Compared to this result, the propylene resin composition of the present invention has a thinner light-shielding thickness and less thermal deformation by using glass fiber in combination with titanium oxide and talc, as shown in Table 1 Nos. 2 to 6. It shows that the temperature is improved. Further, Table 1 No. 12 shows a comparative example in which the glass fiber component was removed from the propylene resin composition of the present invention and a large amount of titanium oxide and talc were blended. This result shows that titanium oxide,
The first one with the same total amount of glass fiber and talc
Compared to the results in Table No. 11, the light shielding properties were inferior, indicating that the heat distortion temperature was insufficient. and the first
Table No. 15 shows that when the amount of glass fiber exceeds the specified range of the present invention, the light-shielding thickness is improved, but the melt index becomes extremely small, that is, the flow characteristics are poor and the processability is poor. Further, Table 1 No. 7, No. 13, and No. 14 are all comparative examples in which talc is excluded from the above-mentioned ingredients, but the amount of talc is less than the specified amount of the present invention. These results show that although the light shielding thickness is improved, the melt index is small and the flow characteristics are poor, resulting in poor processability. Even if the blending ratio of talc is larger than the amount specified in the present invention, as shown in Table 1 No. 16, the flow of the resin composition is poor and melt-kneading is difficult. Furthermore, Table 1 No. 7 and Nos. 13 to 15 show that when the blending ratio of glass fiber and talc is smaller than the specified value of the present invention, the melt index is small and the processing characteristics are defective. 12 indicates that the heat distortion temperature cannot be improved when it is larger than the specific value. These results show that when titanium oxide, glass fiber, and talc are blended together, the light-shielding properties are relatively more effective than when one of these components is missing, and the blending ratio of these components is It is shown that if the value is outside a specific value, a problem arises in that it is not possible to improve the light shielding property, the heat distortion temperature, the workability, etc.

[Table] Example 2 Titanium oxide (R680 manufactured by Ishihara Sangyo Co., Ltd.), glass fiber (Japan Glass Fiber RES-06-TP37) and talc (B grade) were mixed and pelletized in the same manner as in Example 1, with the blending ratios shown in Table 2. Next, in the same manner as in Example 1, the light shielding property, L value, flexural modulus, heat distortion temperature, and melt index were measured. These results are also listed in Table 2.

[Table] Example 3 Titanium oxide (R680 manufactured by Ishihara Sangyo Co., Ltd.), talc (C
grade) and the filler shown in Table 2, propylene homopolymer (PN260, MI23 manufactured by Tokuyama Soda Co., Ltd.) 100
9.3 parts by weight of titanium oxide, talc
21.3 parts by weight and 2.7 parts by weight of various fillers were mixed, melt-kneaded and pelletized in the same manner as in Example 1. Next, using this pellet, the light shielding property, L value, flexural modulus, heat distortion temperature, and melt index were measured in the same manner as in Example 1. These values are listed in Table 3.

【table】

[Table] Example 4 Titanium oxide (Chiona 113 manufactured by LaPorte), talc (A grade) and glass fiber (06MA486A manufactured by Asahi Glass Fiber Co., Ltd. diameter 10 μ, length 3 mm) were added to the thermoplastic resin 100 shown in Table 4. After mixing 6 parts by weight of titanium oxide, glass fiber and talc in the proportions shown in Table 4, the mixture was melt-kneaded and pelletized in the same manner as in Example 1. Next, using this pellet, the light shielding property and L value were measured in the same manner as in Example 1. These values are also listed in Table 4.

【table】

【table】 [Brief explanation of drawings]

The accompanying drawings, FIG. 1, show the shape of a plate-like object used as a test sample, with FIG. 1a showing a plan view and FIG. 1b showing a cross-sectional view. In addition, Figure 2 shows a light-shielding test device.
FIG. 2a is a plan view of the light emitting device, and FIG. 2b is a sectional view thereof. Furthermore, FIG. 3 shows an embodiment of the light shielding test method, FIG. 3a is a plan view of the embodiment, and FIG. 3b is a sectional view thereof. The numbers in Figure 2 indicate the following. 1 is a box, 2 is a slit, 3 is a light bulb, 4 is a power source, and 5 is a switch.

Claims (1)

[Claims] 1. 2 to 100 parts by weight of titanium oxide, 0.1 to 160 parts by weight of a glass filler, and 5 to 200 parts by weight of talc are blended with 100 parts by weight of a propylene resin, and A propylene resin composition in which the proportion of talc in the total amount of talc is in the range of 20 to 99.5% by weight. 2. The composition according to claim 1, wherein the glass filler is glass fiber.