JPS6237665B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention has excellent mechanical properties and thermal properties, and is composed of a styrenic resin composition reinforced with glass fibers, more specifically, a modified styrenic resin modified with maleic anhydride and reinforced with glass fibers. The present invention provides a styrenic resin composition. BACKGROUND ART Conventionally, it has been known to blend glass fibers into a basic thermoplastic resin in order to improve the mechanical properties and dimensional stability of the thermoplastic resin. Most currently known glass fiber-reinforced thermoplastic resin compositions are made by blending glass fiber with a thermoplastic resin and kneading the mixture in an extruder to form pellets. When kneading a blend of glass fibers and a basic thermoplastic resin using an extruder, the glass fibers are blitzed, matted, etc.
In addition to problems such as separation of the thermoplastic resin and glass fibers resulting in non-uniform dispersion of the glass fibers, there are also disadvantages in that the glass fibers wear and damage the molding machine. In order to solve the above problems,
As described in Japanese Patent No. 51-37141, glass fiber chopped strands are present in a suspension polymerization system together with vinyl compound monomers, and the vinyl compound monomers are polymerized to form glass fiber chopped strands. A technique has been proposed in which a pud strand is coated with a vinyl compound polymer and the glass fiber-containing polymer thus obtained is blended with another resin to be reinforced. Although this technique solves the above-mentioned problems, there is still the problem that the thermal properties, particularly the heat deformation resistance, are not sufficiently improved. It has been found that in order to improve the thermal properties of a glass fiber-containing polymer, particularly its heat distortion temperature resistance, it is sufficient to use a thermoplastic resin having a high heat distortion temperature resistance as the base material. In the case of styrene resins, those with high heat deformation resistance include styrene-maleic anhydride copolymer, styrene-acrylonitrile-maleic anhydride terpolymer, and styrene-methyl methacrylate-maleic anhydride terpolymer. etc. became known, and compositions made of these resins and glass fibers were also published in the Special Publication Publication No. 49-19097.
It was described in Japanese Patent Publication No. 54-19906 and became well known. In the composition described in Japanese Patent Publication No. 49-19097, when glass fiber is blended with a basic resin containing maleic anhydride, the rigidity and heat deformation resistance are improved, but the impact resistance is poor due to poor adhesion between the resin and the glass fiber. However, since the properties are not improved, an improved composition has been proposed. The composition described in Japanese Patent Publication No. 54-19906 is
Glass fibers are blended into a base resin containing maleic anhydride produced by a bulk-suspension two-stage polymerization method, and this composition is characterized by the method of producing the base resin. In view of this situation, the present inventors have determined the rigidity,
With the aim of providing a glass fiber-reinforced styrenic resin composition with excellent heat deformation resistance and impact resistance, as a result of extensive research, we discovered that chopped glass fiber strands were coated with a polymer of a specific composition. The resin composition obtained by dry blending this with a modified styrenic resin modified with maleic anhydride has excellent rigidity and heat deformation resistance, and also has significantly improved impact resistance. It was discovered that a molded article could be obtained, and the present invention was completed based on this discovery. Therefore, the gist of the present invention is to combine one vinyl compound monomer or a mixture of two or more vinyl compound monomers copolymerizable with each other with a polymerizable monomer having a hydroxyl group or a conjugate monomer having a hydroxyl group. Contains 20 to 90% by weight of glass fiber chopped strands obtained by polymerization by suspension polymerization in the presence of a diene polymer and glass fiber chopped strands, and has a pellet-like appearance. Modified styrenic resin 95 modified by introducing 5 to 50% by weight of a glass fiber-containing polymer exhibiting
50% by weight of the glass fiber reinforced styrenic resin composition. The present invention will be explained in detail below. Vinyl compound monomers used in the present invention include styrene, α-
Vinyl aromatic compounds such as methylstyrene, vinyltoluene, chlorostyrene, acrylonitrile,
Examples include vinyl cyanide compounds such as methacrylonitrile, as well as vinyl chloride, acrylic acids, methacrylic acids, acrylic esters, and methacrylic esters. These monomers can be used either singly or in combination of two or more types that can be copolymerized with each other. When used in combination of two or more types, a combination of a monovinyl aromatic compound and a vinyl cyanide compound is particularly preferred. In the present invention, examples of the polymerizable monomer having a hydroxyl group include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, methylol acrylamide, and allyl alcohol. Examples of the conjugated diene polymer having a hydroxyl group include α,ω-polybutadiene glycol produced by a radical polymerization method or a living anion polymerization method. In the present invention, the amount of the polymerizable monomer having a hydroxyl group or the conjugated diene polymer having a hydroxyl group is determined based on 100 parts by weight of the total monomer mixture.
It is preferably in the range of 0.5 to 50 parts by weight. If it is less than the above range, the impact resistance of the final resin composition will not improve, which is undesirable, and if it exceeds the above range, the improvement rate of the impact resistance of the final resin composition will be small. Undesirable. Among the above ranges, 1.0 to 20 parts by weight is particularly preferred. The chopped glass fiber strand as used in the present invention is a strand in which tens to hundreds of microfibers with a diameter of 20 μm or less are bundled, and the length is 2 to 10 mm. Strand length is 2
If it is less than mm, the glass fiber exhibits properties only as a filler, making it impossible to improve the mechanical properties of the final molded product, which is not preferable. On the other hand, if the length is 10 mm or more, it is not preferable because the length is too long and it becomes difficult to mold a resin composition containing the same. The glass fiber-containing polymer referred to in the present invention is one in which one or more of the above monomers are suspended together with a polymerizable monomer having a hydroxyl group, a conjugated diene polymer having a hydroxyl group, or a chopped glass fiber strand. It is obtained by coexisting in a turbid polymerization system and polymerizing monomers. At this time, commercially available chopped glass fiber strands can be used as they are, but if the prepared chopped strands are soaked in the monomer used for polymerization in advance and then used. The resulting product is preferred because each of the microfibers making up the chopped strands is completely coated with polymer. When polymerizing vinyl compound monomers, the amount of glass fiber chopped strands to be present in the polymerization system can be from 5 to 800 parts by weight per 100 parts by weight of the monomer. A ratio of body to chopped glass fiber strands of 100 to 50 to 500 is particularly preferred. During suspension polymerization, the ratio of aqueous medium to monomer is 100 parts by weight to 100 parts by weight of monomer.
3000 parts by weight is preferred. Per 100 parts by weight of monomer
If less than 100 parts by weight of aqueous medium is used, as the polymerization progresses, the entire product mixture becomes extremely viscous, making it difficult to stir the product mixture, and also making heat transfer, temperature control, etc. difficult. Therefore, it is not preferable because it causes disadvantages such as not being able to obtain a polymer with uniform properties. If the amount of the aqueous medium is 3000 parts by weight or more, the amount of monomer charged will inevitably be limited and productivity will decrease, which is uneconomical. The polymerization of vinyl compound monomers is as described above.
Depending on the suspension polymerization method, the suspension stabilizer that can be used at this time is preferably one that is used when only the vinyl compound monomer is polymerized by the suspension polymerization method, such as polyvinyl acetate. Water-soluble polymer compounds such as various saponified substances (polyvinyl alcohol), styrene-maleic acid copolymers, polysodium methacrylate, and copolymers of 2-ethylhexyl acrylate and acrylic acid are listed; Two or more types can also be used in combination. Further, these suspending agents and a certain type of surfactant can be used in combination, and inorganic compounds such as calcium carbonate can also be used. In carrying out such a suspension polymerization reaction, a vertical reactor used for carrying out a conventional suspension polymerization reaction can be used without particular limitation. Preferably, the vertical reactor is equipped with a buffer. In addition, when polymerizing the vinyl compound monomer, it is preferable to use a polymerization initiator, and as such a polymerization initiator, a radical-generating polymerization initiator used in the polymerization of the vinyl compound is preferable, The amount used varies depending on the nature of the polymerization initiator and the polymerization temperature, but it can be used in a ratio of 0.005 to 3.0 parts by weight per 100 parts by weight of the monomer. The glass fiber-containing polymer obtained by the above method is
Surprisingly, a large number of chopped strands are arranged and assembled in a certain direction, and the surface is coated with a polymer while keeping the chopped strands focused, and its appearance looks just like that of extruded strands. It has a similar appearance to pellets produced in a machine. This glass fiber-containing polymer contains 30 to 90% by weight of chopped glass fiber strands, especially 40 to 85% by weight.
Preferably, it contains % by weight. It is preferable that the average particle size is in the range of 2.5 to 35 mesh using a Tyler standard sieve. If the average particle size is outside this range, the particle size is either too large or too small, resulting in particles of modified styrenic resin that have been modified by introducing maleic anhydride as a base. This is not preferable because a difference occurs between the sizes of the pellets and the glass fiber polymer is not uniformly dispersed in the base resin when dry blended. The resin composition according to the present invention is obtained by blending a modified styrenic resin modified by introducing maleic anhydride into the glass fiber-containing polymer. In order to produce a modified styrenic resin into which maleic anhydride has been introduced, styrene, maleic anhydride, and, if necessary, a vinyl compound copolymerizable with these are present and copolymerized. Examples of vinyl monomers copolymerizable with styrene and maleic anhydride include acrylonitrile, methacrylonitrile, acrylic acid and its esters, methacrylic acid and its esters, and the like. Modified styrenic resin contains 0.5 maleic anhydride.
It is preferable to contain up to 30% by weight. When the content of maleic anhydride is less than 0.5% by weight, it is not preferable because the heat deformation resistance and impact resistance of the final resin composition will not improve that much.
When the amount is more than % by weight, the impact resistance of the resin composition finally obtained is not improved very much, which is not preferable. The modified styrene resin preferably has a granular or pellet-like appearance. This is because if the appearance and shape are similar to those of the glass fiber-containing polymer, both can be maintained in a uniformly dispersed state when the two are dry blended. The blending ratio of the glass fiber-containing polymer and modified styrene resin is 5 to 50% by weight for the former and 5 to 50% by weight for the latter.
A range of 95-50% by weight is preferred. If the glass fiber-containing polymer is less than 5% by weight, the amount of glass fiber in the final resin composition will be too small, and the purpose of improving and improving various properties by adding glass fiber will not be achieved. . On the other hand, if it exceeds 50% by weight, the glass fiber addition efficiency will not improve much and it will be meaningless. A particularly preferred range is 15 to 45% by weight of the former, and about 10 to 35% by weight as glass fiber contained in the final resin composition. The composition of the present invention is obtained by dry blending a glass fiber-containing polymer exhibiting a pellet-like appearance with pellets or granules of a modified styrenic resin modified by introducing maleic anhydride. be. For blending the two, various conventional mixers can be used without any restriction. It goes without saying that commonly used substances may be added to the composition of the present invention for coloring, weight increase, modification, etc., to the extent that they do not adversely affect the modified styrenic resin. Such a dry blend composition can be subjected to various molding methods such as injection molding, extrusion molding, etc. in the form of a dry blend. Therefore,
The conventional process of dry blending glass fibers and a resin to be mixed therein and kneading this dry blend composition in an extruder to form glass fiber-containing pellets can be omitted. . Therefore, problems such as separation of the base resin and glass fibers, bridging and matting of the glass fibers are solved. Furthermore, the composition of the present invention
Since the surface of the chopped glass fiber strand is coated with a polymer, the glass fiber is difficult to break during molding. Each microfiber is also coated with a polymer and bonded to each other, so it is difficult to separate into microfibers due to shearing during molding, and there is less direct friction between the glass fiber and the molding machine. damage can be reduced. From the composition of the present invention, a molded article having excellent rigidity, heat deformation resistance, impact resistance, and appearance can be obtained. Therefore, the industrial utility value of the present invention is extremely large. Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. Example 1 First, chopped glass fiber strands (about 3 in length) were placed in a glass autoclave equipped with a stirrer, a condenser, a nitrogen gas inlet, a thermometer, etc.
mm) 504g styrene 133.2g acrylonitrile 72.0g 2-hydroxypropyl acrylate 10.8g Benzoyl peroxide 1.62g were charged, and the inside of the reaction vessel was replaced with nitrogen. Combined) 0.36g was charged. Then, while stirring in a nitrogen stream,
The internal temperature of the reaction vessel was raised to 80°C, and the polymerization reaction was continued at this temperature for 3 hours. Subsequently, the temperature inside the autoclave was raised to 90°C over 30 minutes, and the polymerization reaction was continued at this temperature for an additional 3 hours. Thereafter, unreacted monomers were removed by stripping. The product in which glass fibers were coated with a polymer (glass fiber-containing polymer) weighed 624 g, and the glass fiber content was 79.0% by weight. The glass fiber-containing polymer consists of 50 to 500 chopped strands tied together, with a diameter of about 1 to 3 mm and a length of about 3 mm, which is almost the same as the chopped glass fiber strands used. Both ends were aligned and had a pellet-like appearance. The product obtained in this example includes Dylark 238 (USA,
Styrene-maleic anhydride copolymer (manufactured by Alco Chemical Co., Ltd.) is dry blended, and the glass fiber content in the final resin composition is 20% by weight.
A dry blend product was obtained. Test pieces were prepared from this dry blend composition using a screw-type injection molding machine, and various physical properties were measured. The measurement results are shown in Table 1. The mechanical properties were measured according to the following method. The same applies to the following examples. Tensile strength, elongation JIS K6871 Bending strength ASTM D790 Bending modulus ASTM D790 Izod impact strength JIS K6871 Shapey impact strength JIS K6871 Heat distortion temperature JIS K6871 Example 2 In the example described in Example 1, the The polymerization operation was carried out in the same manner as described in the same example, except that the same amount of 2-hydroxypropyl methacrylate was used instead. The amount of glass fiber-containing polymer obtained was 631 g, and the glass fiber content of this product was 77.8% by weight. The product obtained in this example was dry blended with Dilarc 238 in the same manner as described in Example 1, a test piece was prepared, and various physical properties were measured. The results are shown in Table 1. Example 3 In the example described in Example 1, R-45HT (USA,
The polymerization operation was carried out in the same manner as described in the same example, except that the same amount of Alco Chemical Co., Ltd.) was used. The amount of glass fiber-containing polymer obtained was 631 g, and the glass fiber content of this product was 78.3% by weight. The product obtained in this example was dry blended with Dilarc 238 in the same manner as described in Example 1, a test piece was prepared, and various physical properties were measured. The results are shown in Table 1. Comparative Example Polymerization was carried out in the same manner as in Example 1, except that the entire amount of 2-hydroxypropyl acrylate was omitted. The resulting glass fiber-containing polymer weighed 621 g, and its glass fiber content was 79.2% by weight. The product obtained in this example was dry blended with Dilarc 238 in the same manner as described in Example 1, a test piece was prepared, and various physical properties were measured. The results are shown in Table 1.

【table】

[Table] The following becomes clear from Table 1. (1) The resin composition according to the present invention has high bending strength and bending modulus at high temperatures, and is excellent in rigidity, as compared to the comparative example. (2) The resin composition according to the present invention has higher Izod impact strength and Sharpie impact strength than those of comparative examples, and molded articles with excellent impact resistance can be obtained. (3) From the composition according to the present invention, a molded article having excellent rigidity and thermal deformability as well as excellent impact resistance can be obtained.

Claims (1)

[Claims] 1 One type of vinyl compound monomer or a mixture of two or more types of vinyl compound monomers that can be copolymerized with each other,
Glass fiber chopped strands obtained by polymerizing by a suspension polymerization method in the presence of a polymerizable monomer having a hydroxyl group or a conjugated diene polymer having a hydroxyl group, and a chopped glass fiber strand. 20~90
5-50% by weight of a glass fiber-containing polymer having a pellet-like appearance and 95-50% by weight of a modified styrenic resin modified by introducing maleic anhydride. A glass fiber-reinforced styrenic resin composition.