JPS623867B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a reinforced thermoplastic resin composition that has excellent moldability and can produce molded articles with excellent uniformity, appearance, and dimensional stability. Polyethylene terephthalate (hereinafter abbreviated as PET) is a thermoplastic polymer with excellent heat resistance, chemical resistance, and water resistance, but due to its slow crystallization rate, there is a limit to the degree of crystallinity that can be achieved using normal molding methods. It has difficulties in moldability and physical properties, which limits its application as a molding material. In order to improve this point, attempts have been made to improve moldability and physical properties by adding fibrous fillers such as galai fibers (hereinafter abbreviated as GF) to increase rigidity, but none of them has been fully satisfactory. Kimono has not been obtained. In other words, when using such a method, there is a certain degree of moldability,
Although the physical properties of the molded product are improved, the physical properties and appearance of the molded product are highly dependent on the mold temperature, and at the mold temperature of 100°C or less, which is usually used, crystallization is insufficient and the product becomes crystallized, resulting in an opaque interior and an almost amorphous shape. It has the disadvantage that only molded articles with a transparent exterior and non-uniform appearance and physical properties can be obtained. Furthermore, the addition of fibrous fillers causes anisotropy in the physical properties such as strength and shrinkage rate of the resulting molded product, and also has the drawback that dimensional stability decreases. On the other hand, polymethyl methacrylate (hereinafter referred to as PMMA)
) is a thermoplastic material with good weather resistance and moldability, but because it is a so-called amorphous polymer, the reinforcing effect of fibrous fillers is low, such as
Even if filled with GF, only a product with low heat resistance can be obtained. By the way, a method of blending an amorphous polymer in order to improve the anisotropy of the crystalline polymer in a reinforced thermoplastic resin is known, but in this case, while improving the anisotropy of the molded product, it does not improve the strength properties or heat resistance. It has the disadvantage that the value decreases significantly. In view of the above-mentioned current situation, the present inventors have conducted intensive studies to obtain a resin composition that can produce molded products with excellent molding processability and excellent appearance, uniformity, and dimensional stability. PMMA blends have a uniquely smaller rate of decline in physical properties per blend amount than other amorphous polymers, and also avoid the above-mentioned drawbacks by combining PET, PMMA, and glass fibers in specific proportions. The resin composition can be made without
Furthermore, it was discovered that by blending talc or glass foil with this resin composition, a resin composition can be obtained which can further improve physical properties such as dimensional stability, heat resistance, and rigidity of molded products without inhibiting the reinforcing effect of GF. completed. That is, the gist of the present invention is the first invention, which is a reinforced thermoplastic resin composition comprising 10 to 90% by weight of polyethylene terephthalate, 5 to 70% by weight of polymethyl methacrylate, and 5 to 50% by weight of glass fiber. Polyethylene terephthalate 10~90
5-70% by weight of polymethyl methacrylate, 5-50% by weight of glass fiber, and 30% by weight of talc or glass foil, and the total amount of glass fiber and talc or glass foil is 5-60% by weight. % by weight of the reinforced thermoplastic resin composition. The present invention improves the moldability, appearance, and dimensional stability of PET by uniformly kneading PET and PMMA in various ratios in a molten state, and further blending GF, and improves the strength properties and heat resistance of PMMA. The purpose of the present invention is to provide a new reinforced thermoplastic resin composition with improved properties, and the molded products obtained from the resin composition of the present invention are white, opaque, and have uniform appearance and physical properties, and their mold temperature dependence is Extremely small. Furthermore, the anisotropy of strength and shrinkage rate is small, the dimensional stability is excellent, and the strength and physical properties and heat resistance are well balanced. The PET used in the present invention is a linear polyethylene terephthalate polymer having ethylene terephthalate units as a constituent unit, and a polymer obtained by copolymerizing this with a small amount of other copolymerizable components. Generally, thermoplastic resins containing GF are GF
The sizing agent causes heat coloring during formation.
Because the molding temperature of PET is relatively high, thermal coloring is even more pronounced, and in order to achieve white coloring, it is necessary to incorporate a large amount of pigment such as titanium dioxide, which results in a decrease in the physical properties of the molded product. However,
Products blended with PMMA have extremely high whiteness, and the rate of decline in physical properties per blend amount is uniquely small. Such a blending effect of PMMA is unique and cannot be obtained by blending other amorphous polymers such as polystyrene, polyacrylonitrile, and polycarbonate, or even by blending crystalline polymers such as polyolefin and polyamide.
Furthermore, molded products obtained by blending PMMA are
The major disadvantages of GF-reinforced PET, such as internal and external transparency non-uniformity, molding burrs, and smoothness, have been improved.
Even when molded in a low-temperature mold of 100°C or less, a sufficiently satisfactory product can be obtained. In the present invention, the above-mentioned excellent blending effect of PET and PMMA is achieved when PET is 10 to 90% by weight,
It can only be obtained by blending PMMA in a range of 5 to 70% by weight, and if the blending amount of PMMA is less than 5% by weight, it will be insufficient, and PMMA
If the amount is less than 10% by weight, the strength and heat resistance of the molded product will be significantly reduced, which is undesirable. From the balance of overall physical properties, appearance, and moldability
A PET/PMMA weight ratio in the range of 80/20 to 40/60 gives particularly favorable results. Note that it is also possible to further blend a third component polymer for the purpose of improving some physical properties such as heat resistance and strength within a range that does not impede the properties of the resin composition of the present invention. Strength and heat resistance are improved by blending nylon 66 and polybutylene terephthalate as polymers. The type of the third component polymer is not particularly limited, but the amount added is preferably 15% by weight or less based on the total composition. Examples of the GF used in the present invention include glass lobes or glass chopped strands that are commonly used in reinforced thermoplastic resins, but powdered milled fibers with a fiber length of 0.5 mm or less have low reinforcing properties. Excluded. The blending amount of GF is 5 to 50% by weight; if it is less than 5% by weight, the reinforcing effect will be insufficient, and if it exceeds 50% by weight, the moldability will deteriorate, which is not preferred. 10-35
A range of % by weight is particularly preferable from the viewpoint of physical properties and moldability. Furthermore, in the present invention, by using talc or glass foil in combination with the above-mentioned GF, kneading and molding processability are further improved without inhibiting the reinforcing effect of GF, and the dimensional stability and heat resistance of the resulting molded product are improved. , it has an excellent feature of being able to further improve physical properties such as rigidity. Conventionally, it is known that in reinforced thermoplastic resins, large amounts of inexpensive inorganic powder fillers are blended or used in combination with GF to reduce costs and improve dimensional stability, but powder fillers have poor reinforcing properties. is low
When used in combination with GF, it generally tends to reduce the reinforcing effect of GF, and the specific gravity increases, which is a fatal disadvantage of inhibiting the lightness that is the inherent advantage of plastics. In the present invention, since PMMA having a low specific gravity is used, the increase in specific gravity caused by the powdered filler is offset, and overall, the above-mentioned lightness is not inhibited. The talc or glass foil used in the present invention is
It is important to use it in combination with GF, and the use of talc or glass foil alone will not produce the excellent effects described above. When GF and talc or glass foil are used together, the improvement in heat resistance in addition to strength and rigidity is remarkable. Such an effect is unique and cannot be obtained with other powder fillers. That is, even if commonly used calcium carbonate, calcium sulfate, wallasnite, milled fiber, etc. are used in combination, the heat resistance does not particularly improve, and physical properties such as tensile strength and impact strength tend to deteriorate slightly. On the other hand, various metal salts, oxides, benzoates, carbon powder, etc. are known as nucleating agents for PET, but these have the disadvantage of uniformly lowering the strength and physical properties when added in large amounts. The talc used in the present invention is preferably in powder form with an average particle size of 0.01 to 10 microns. Moreover, as the glass foil, a flake-like glass foil with an average particle size of 500 μm or less is preferably used. The amount of these talc or glass foils is 30% by weight.
If it exceeds 30% by weight, the specific gravity increases and is also unfavorable from the viewpoint of moldability. In addition, when glass fiber and talc or glass foil are used together, the total amount of these inorganic fillers in the entire resin composition must be in the range of 5 to 60% by weight. If the total blending amount of these inorganic fillers deviates from the above range, the resin composition targeted by the present invention cannot be obtained. An example of an embodiment of the present invention is to directly injection mold a predetermined amount of polymer raw materials mixed in a tumbler or the like, or to melt and knead the mixture in an appropriate kneading machine such as an extruder to form pellets, and then inject or A molded article is obtained by subjecting it to pressure molding. The present invention will be specifically explained below using Examples. Examples 1 to 14, Comparative Examples 1 to 18 Predetermined amounts of polymers and fillers shown in Table 1 and
After mixing 0.1 parts by weight of sodium benzoate in a tumbler for 5 minutes, the mixture was melt-kneaded at 280°C using a 40 mm diameter vented extruder and extruded into pellets.
These pellets were molded into 5 ounces using a 36 mmφ screw in-line injection molding machine at a cylinder temperature of 280.
℃, mold temperature 80℃ or 140℃, 3.2 thickness 1 part dumbbell specimen, 6.4mm thickness heat deformation temperature measurement specimen and 110
A flat plate of mm x 110 mm x 3 mm was molded. Using these specimens, the tensile strength was determined from the No. 1 dumbbell specimen by ASTM.
D638 was used to measure the Izot impact strength using a 2.5 mm notch using a heat distortion temperature measurement sample. ASTM D256 was used to measure the heat distortion temperature using a heat distortion temperature measurement sample.
Measured according to ASTM D648. The appearance of the molded products was visually compared using a flat plate. Uniformity is compared by the transparency of the inside and outside of the molded product, and the presence or absence of warpage is determined by 25
The plate was examined after being left in a constant temperature room at ℃ for 48 hours. For molding burrs, shot shot pressure +
A flat plate molded at 5 kg/cm ² was used for comparison. Table 1 shows these evaluation results. The polymers and fillers used are as follows. Polyethylene terephthalate (PET): 25% in a mixed solvent of equal amounts of tetrachloroethane and phenol
Polymethyl methacrylate (PMMA): Acrypet VH manufactured by Mitsubishi Rayon Co., Ltd. Polystyrene (PST): Styron manufactured by Asahi Dow Co., Ltd.
666 Polystyrene-acrylonitrile copolymer (PAS): Ryowa Kasei Co., Ltd. APH High-density polyethylene (HDPE): Mitsui Petrochemical Co., Ltd. HIZEX 2100GP Nylon 66: Ube Industries, Ltd. 2020B Polybutylene terephthalate (PBT): Toyobo Co., Ltd. N1100 Glass fiber (GF): Manufactured by Asahi Fiberglass Co., Ltd.
3mm chopped strand glass foil: CF-150 manufactured by Nippon Glass Co., Ltd. Talc: Hayashi Kasei Micron White 5000A Evaluation results of physical properties and appearance, and evaluation of comparative examples studied using the same method for the purpose of clarifying the effects of the present invention The results are shown in Table 2. All parts in Tables 1 and 2 are parts by weight. As is clear from Example 2 and Comparative Examples 1 to 5, PET
A blend system of PMMA and PMMA can be obtained with good physical properties and appearance. Blends of amorphous polymers PST and PAS instead of PMMA have no difference in warpage and molding burrs, but are inferior in terms of whiteness and uniformity. Blends of crystalline polymers such as HDPE, nylon 66, and PBT are not suitable for use, as they have poor whiteness and uniformity, and are particularly prone to warping and molding burrs. Next, from Examples 1 to 4 and Comparative Examples 6 to 9, PET and
It can be seen that there is an appropriate range for the blended amount of PMMA. That is, PMMA is 5% by weight.
If it is less than that (Comparative Example 8), the improvement effect on whiteness, uniformity, warpage, and molding burr is small, and only a product similar to that of a PET-only system (Comparative Example 6) can be obtained. on the other hand
When PET is less than 10% by weight (Comparative Example 9), the appearance is good, but the strength and especially the heat resistance are low.
It is at the same level as the PMMA-only system (Comparative Example 7), which is inappropriate. PET/PMMA weight ratio is 80/20 ~
A range of 40/60 is particularly preferred, as in Example 4.
When the PET/PMMA weight ratio is 29/71, which is a large amount of PMMA, the appearance is good, but the heat resistance tends to decrease. In addition, even in such cases, nylon
It is possible to improve heat resistance by substituting a portion of PMMA with a crystalline polymer such as 66 or PBT (Examples 5-7). However, if the amount of the third component polymer added exceeds 15% by weight, the effect of the present invention will be inhibited in terms of appearance, which is inappropriate (Comparative Example 10). Example 8 is a type containing 10% by weight of GF, and although the physical properties are generally lower than that of Example 2 containing 30% by weight of GF, the appearance is uniformly good.
When talc and glass foil are used together with GF, the physical properties, especially the heat resistance, are significantly improved without impairing the appearance (Examples 9 to 12). This effect is specific to talc and glass foil, and as is clear from Comparative Examples 12 to 16, no improvement in strength or heat resistance is observed even when other commonly used inorganic fillers are optionally used in combination. figure,
This value is lower than that of the GF alone system (Comparative Example 11). It should be noted that if talc is 30% by weight or more (Comparative Example 17), extrusion workability will deteriorate and impact strength will also decrease, which is not preferable. Examples 13 and 14 were molded at a mold temperature of 140° C., and when talc and GF were used in combination, the dependence of the heat distortion temperature on mold temperature was smaller than when GF was used alone. Comparative Example 18 is the result of molding PET containing 10% by weight of GF in a mold at 140°C.
Compared to the 80°C mold of Comparative Example 11, the strength properties are lower and the heat resistance is improved. The mold temperature dependence of strength properties is greater than that of PMMA blend systems.
Even when molded in a 140°C mold, the resulting product is inferior in appearance, such as whiteness, warpage, and molding burrs, in addition to uniformity.

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Claims (1)

[Claims] 1. 10 to 90% by weight of polyethylene terephthalate,
A reinforced thermoplastic resin composition comprising 5 to 70% by weight of polymethyl methacrylate and 5 to 50% by weight of glass fiber. 2 Polyethylene terephthalate 10-90% by weight,
5-70% by weight of polymethyl methacrylate, 5-50% by weight of glass fiber and talc or glass foil
Contains 30% by weight or less, and the total amount of glass fiber and talc or glass foil is 5% by weight or less.
Reinforced thermoplastic resin composition that is ~60% by weight.