JP2022053913A - Method for manufacturing alloy resin and method for manufacturing molded article - Google Patents

Abstract

To provide a method for manufacturing an alloy resin and a method for manufacturing a molded article which enable manufacture of a molded article that is excellent in transparency and scratch resistance.SOLUTION: Manufacture of an alloy resin using a twin screw extruder 10 feeds a methyl methacrylate-based resin from a main hopper 14 on the upstream side of a cylinder 12, side feeds a powdery vinyl chloride-based resin from a side feeder 16, adds the vinyl chloride-based resin to the methyl methacrylate-based resin in a molten state, and melt-kneads the mixture. A molded article is obtained by molding an alloy resin melt-kneaded by the method.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing an alloy resin and a method for producing a molded product.

Rigid vinyl chloride resins are generally excellent in flame retardancy and chemical resistance, and are therefore widely used in pipes, general building materials, and the like. Further, for the purpose of improving the characteristics of the rigid vinyl chloride resin, it is known that an acrylic resin, an ABS resin or the like is added as an alloy to the vinyl chloride resin and molded by injection molding or the like (for example, Patent Document 1). ).

Japanese Unexamined Patent Publication No. 61-014246

However, it is difficult to produce a molded product having excellent transparency and scratch resistance by a conventional method such as Patent Document 1.

An object of the present invention is to provide a method for producing an alloy resin capable of producing a molded product having excellent transparency and excellent scratch resistance, and a method for producing a molded product.

The present invention has the following aspects.
[1] A method for producing an alloy resin, wherein a powdery vinyl chloride resin is added to a molten methyl methacrylate resin and melt-kneaded to obtain an alloy resin.
[2] Using a twin-screw extruder, the methyl methacrylate-based resin is fed from the main hopper on the upstream side of the cylinder, and the powder-like vinyl chloride-based resin is side-fed to be melted with the methyl methacrylate-based resin in a molten state. The method for producing an alloy resin according to [1], which is kneaded.
[3] The method for producing an alloy resin according to [2], wherein the temperature of the portion of the cylinder of the twin-screw extruder that side-feeds the vinyl chloride resin is 160 ° C. or higher and 190 ° C. or lower.
[4] A method for producing a molded product, which comprises molding the alloy resin produced by the method for producing an alloy resin according to any one of [1] to [3] to obtain a molded product.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for producing an alloy resin capable of producing a molded product having excellent transparency and excellent scratch resistance, and a method for producing a molded product.

It is a schematic block diagram which showed an example of the twin-screw extruder used in the manufacturing method of this invention.

[Manufacturing method of alloy resin]
In the method for producing an alloy resin of the present invention, a powdered vinyl chloride resin (hereinafter referred to as "PVC resin") is added to a molten methyl methacrylate resin (hereinafter referred to as "MMA resin"). In addition, it is a method of obtaining an alloy resin by melt-kneading.

By melt-kneading a powdery PVC-based resin with a melted MMA-based resin, the PVC-based resin can be efficiently kneaded. As a result, the thermal history of the PVC-based resin can be shortened, so that yellowing of the PVC-based resin can be suppressed. Therefore, by using the alloy resin produced by the production method of the present invention for molding, a molded product having excellent transparency can be obtained. Further, since the MMA-based resin and the PVC-based resin are sufficiently melt-kneaded, a molded product having excellent scratch resistance can be obtained.

A twin-screw extruder can be used for melt-kneading the MMA-based resin and the PVC-based resin.
For example, a method using the twin-screw extruder 10 illustrated in FIG. 1 can be exemplified. It should be noted that the dimensions and the like of the figures exemplified in the following description are examples, and the present invention is not necessarily limited to them, and the present invention can be appropriately modified without changing the gist thereof. ..

The twin-screw extruder 10 includes a cylinder 12 having a screw (not shown) inside, a main hopper 14 provided on the upstream side of the cylinder 12, and a side feeder 16 provided in the middle of the cylinder 12 in the axial direction. Is equipped with.

In the method using the twin-screw extruder 10, the MMA resin is fed from the main hopper 14 to the upstream portion of the cylinder 12. The fed MMA-based resin is heated in the cylinder 12 and is in a molten state by the time it reaches the portion where the side feeder 16 is provided. Further, the powdery PVC resin is side-fed from the side feeder 16 to the middle portion of the cylinder 12. As a result, the powdery PVC resin is added to the molten MMA resin. On the downstream side of the side feeder 16 of the cylinder 12, the molten MMA resin and the powdery PVC resin are melt-kneaded by a screw, and the alloy resin is extruded from the tip of the cylinder 12.

It is preferable to provide a high temperature region for sufficiently melting the MMA-based resin in the portion of the cylinder 12 on the upstream side of the side feeder 16. The temperature in the high temperature region on the upstream side of the side feeder 16 of the cylinder 12 is preferably 190 ° C. or higher, more preferably 190 ° C. or higher and 210 ° C. or lower. When the temperature in the high temperature region is equal to or higher than the lower limit of the range, the MMA resin can be sufficiently melted. When the temperature in the high temperature region is not more than the upper limit of the range, it is easy to suppress the thermal deterioration of the MMA-based resin.

The temperature of the side feed portion of the cylinder 12 provided with the side feeder 16, that is, the portion for side feeding the PVC resin is preferably 160 ° C. or higher and 190 ° C. or lower, and more preferably 170 ° C. or higher and 180 ° C. or lower. When the temperature of the side feed portion of the cylinder 12 is equal to or higher than the lower limit of the above range, melt-kneading of the MMA-based resin and the PVC-based resin becomes easy. When the temperature of the side feed portion of the cylinder 12 is not more than the upper limit of the above range, it is easy to suppress the thermal deterioration of the PVC resin.

The temperature of the portion of the cylinder 12 on the tip side of the side feed portion is preferably 160 ° C. or higher and 190 ° C. or lower, and more preferably 170 ° C. or higher and 180 ° C. or lower, as in the side feed portion. When the temperature on the tip side of the side feed portion of the cylinder 12 is equal to or higher than the lower limit of the above range, the MMA-based resin and the PVC-based resin can be easily melt-kneaded, and the dispersibility is good and transparency can be obtained. When the temperature at the tip of the side feed portion of the cylinder 12 is equal to or less than the upper limit of the above range, heat generation of the alloy resin can be suppressed and thermal deterioration of the PVC resin can be suppressed.

The position where the side feeder 16 is provided in the cylinder 12 of the twin-screw extruder 10 is a distance from the rear end of the cylinder 12 when the length from the rear end (upstream end) to the tip of the cylinder 12 is 1. The position where it becomes / 2 or more, that is, the tip side is preferable to half. As a result, the thermal history of the PVC-based resin can be shortened, so that yellowing of the PVC-based resin can be easily suppressed, and a molded product having excellent transparency can be easily obtained.

In terms of sufficient melt-kneading of the MMA-based resin and the PVC-based resin, the position where the side feeder 16 is provided in the cylinder 12 of the twin-screw extruder 10 is set to 1 in the length from the rear end to the tip of the cylinder 12. When, the distance from the rear end of the cylinder 12 is preferably in the range of 1 / 2.5 to 1/3.

The PVC-based resin is a polymer in which the ratio of the repeating unit derived from vinyl chloride (hereinafter, also referred to as “vinyl chloride unit”) is more than 50% by mass with respect to all the repeating units. The PVC-based resin may be a homopolymer of vinyl chloride, or may be a copolymer of vinyl chloride and a vinyl-based monomer copolymerizable with vinyl chloride. When the PVC-based resin is a copolymer, it may be a random copolymer, a block copolymer, or a graft copolymer. The PVC-based resin contained in the alloy resin may be one kind or two or more kinds.

The ratio of the vinyl chloride unit in the PVC resin is preferably 75% by mass or more, more preferably 80% by mass or more, further preferably 85% by mass or more, and particularly preferably 98% by mass or more with respect to all the repeating units.

The vinyl-based monomer copolymerizable with vinyl chloride is not particularly limited, and for example, fatty acid vinyl ester, acrylate, methacrylate, vinyl cyanide, vinyl ether, α-olefin, unsaturated carboxylic acid or an acid anhydride thereof. Examples thereof include vinylidene chloride, vinyl bromide, and various types of urethane.

Examples of the fatty acid vinyl ester include vinyl acetate, vinyl propionate, and vinyl laurate. Examples of the acrylate include methyl acrylate, ethyl acrylate, and butyl acrylate. Examples of the methacrylate include methyl methacrylate and ethyl methacrylate. Examples of vinyl cyanide include acrylonitrile and methacrylonitrile. Examples of the vinyl ether include vinyl methyl ether, vinyl butyl ether, and vinyl octyl ether. Examples of the α-olefin include ethylene, propylene and butylene. Examples of unsaturated carboxylic acids or acid anhydrides thereof include acrylic acid, methacrylic acid, and maleic anhydride. As the vinyl-based monomer copolymerizable with vinyl chloride, one type may be used alone, or two or more types may be used in combination.

The average degree of polymerization of the PVC resin is preferably 400 or more and 1200 or less, more preferably 500 or more and 800 or less, and further preferably 550 or more and 700 or less. When the average degree of polymerization of the PVC resin is at least the lower limit of the above range, the pencil hardness is improved. When the average degree of polymerization of the PVC resin is not more than the upper limit of the above range, the molding processability is improved.
The average degree of polymerization is measured by JIS K 6720-2.

The PVC-based resin may be a hard vinyl chloride resin or a soft vinyl chloride resin, but the hard vinyl chloride-based resin is preferable because the surface hardness of the molded product is high and the scratch resistance is excellent. ..

The MMA-based resin is a polymer in which the ratio of repeating units derived from methyl methacrylate (MMA) (hereinafter, also referred to as “MMA units”) is 80% by mass or more with respect to all repeating units. The MMA-based resin may be a homopolymer of MMA, or may be a copolymer of MMA and a (meth) acrylate other than MMA. In addition, (meth) acrylate is a general term for methacrylate and acrylate. When the MMA-based resin is a copolymer, it may be a random copolymer or a block copolymer. The MMA-based resin contained in the alloy resin may be one kind or two or more kinds.

The ratio of the MMA unit in the MMA-based resin is preferably 80% by mass or more, more preferably 90% by mass or more, based on all the repeating units. When the ratio of MMA units is equal to or higher than the lower limit of the above range, the moldability is improved.

Examples of (meth) acrylates other than MMA include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and 2-ethylhexyl methacrylate. The (meth) acrylate other than MMA used for the MMA-based resin may be one kind or two or more kinds.

The weight average molecular weight of the MMA resin is preferably 10,000 or more and 600,000 or less, and more preferably 20,000 or more and 400,000 or less. When the weight average molecular weight of the MMA resin is at least the lower limit of the above range, the pencil hardness is improved. When the weight average molecular weight of the MMA resin is not more than the upper limit of the above range, the strength is improved.

The number average molecular weight of the MMA resin is preferably 5,000 or more and 300,000 or less, and more preferably 10,000 or more and 200,000 or less. When the number average molecular weight of the MMA resin is at least the lower limit of the above range, the pencil hardness is improved. When the number average molecular weight of the MMA resin is not more than the upper limit of the above range, the strength is improved.
The weight average molecular weight and the number average molecular weight are polystyrene-equivalent average molecular weights measured by gel permeation chromatography.

The melt flow rate (MFR) of the MMA resin is preferably 1.0 g / 10 minutes or more and 20 g / 10 minutes or less, and more preferably 2.0 g / 10 minutes or more and 15 g / 10 minutes or less. When the MFR of the MMA-based resin is at least the lower limit of the above range, the workability is good. When the MFR of the MMA resin is not more than the upper limit of the above range, the pencil hardness is improved.
The MFR is measured in accordance with JIS K 7210 under the conditions of a load of 37.3 N and a temperature of 230 ° C.

The total ratio of the PVC-based resin and the MMA-based resin in the alloy resin is preferably 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, based on the total mass of the alloy resin.

The mass ratio of the PVC-based resin to the MMA-based resin to be melt-kneaded is preferably 20:80 to 90:10, more preferably 50:50 to 80:20. The higher the proportion of the PVC resin, the better the solvent resistance. The higher the proportion of MMA-based resin, the better the scratch resistance.

Additives such as a heat stabilizer, a light stabilizer, a lubricant, and a filler may be added to the alloy resin produced by the present invention, if necessary, as long as the effects of the present invention are not impaired.
The form of the alloy resin to be produced is not particularly limited, and pellets can be exemplified. For example, the alloy resin can be extruded into a strand shape from the tip of the twin-screw extruder 10 and cut into pellets while being cooled by pouring water on it.

[Manufacturing method of molded products]
The method for producing a molded product of the present invention is a method for obtaining a molded product by molding an alloy resin produced by the method for producing an alloy resin of the present invention. As the method for producing the molded product of the present invention, known embodiments can be adopted except that the alloy resin produced by the method for producing the alloy resin of the present invention is used. In the present invention, the pellet-shaped alloy resin produced by the method for producing the alloy resin of the present invention may be used, or a die may be provided downstream of the twin-screw extruder and continuous molding may be performed after melt-kneading.

The pencil hardness on the surface of the molded product is preferably F or higher, more preferably H or higher. When the pencil hardness is at least the above lower limit value, the scratch resistance is excellent. The pencil hardness on the surface of the molded product is measured according to JIS K5600-5-4.

As described above, in the present invention, a powdery PVC resin is added to the melted MMA resin and melt-kneaded. As a result, the PVC-based resin can be sufficiently melt-kneaded into the MMA-based resin while suppressing the yellowing of the PVC-based resin with a short heat history. Therefore, it is possible to manufacture a molded product having excellent transparency and scratch resistance.
The use of the molded product of the present invention is not particularly limited, and examples thereof include vehicles, building materials, and home appliances.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following description.

[transparency]
The molded products prepared in each example were visually confirmed and evaluated according to the following criteria.
◯: No yellowish discoloration was observed on the molded product.
X: Yellowish discoloration was observed on the molded product.

[Pencil hardness]
Pencil hardness was measured according to JIS K5600-5-4.

[Example 1]
A die was provided on the downstream side of the twin-screw extruder 10 illustrated in FIG. 1, and the resin was extruded into a strand shape and cut into pellets while being cooled by pouring water on it. The molded pellets were put into an injection molding machine to produce a plate-shaped molded product. When the length from the rear end to the tip of the cylinder 12 is 1, the position of the main hopper 14 is 1/4 from the rear end of the cylinder 12, and the position of the side feeder 16 is 1/4 from the rear end of the cylinder 12. The position was set to 2.7.
Acrylic pellet VH-001 as MMA resin (trade name, manufactured by Mitsubishi Chemical Co., Ltd., MMA unit ratio: 90% by mass, weight average molecular weight: 90,000, number average molecular weight: 50,000, MFR: 2.0 g / 10 Minutes) is fed from the main hopper 14, and powdered TJZ-2310 (trade name, manufactured by Shinetsu Polymer Co., Ltd., ratio of vinyl chloride unit: 87% by mass, average degree of polymerization: 700) is fed from the side feeder to the side as a PVC resin. Feeded. The mass ratio of the PVC resin and the MMA resin was 70:30.
The temperature in the high temperature region on the upstream side of the side feeder 16 of the cylinder 12 was set to 190 to 200 ° C. The temperature of the side feed portion of the cylinder 12 provided with the side feeder 16 was set to 170 to 180 ° C. The temperature of the portion of the cylinder 12 on the tip side of the side feed portion was 170 to 180 ° C.

[Example 2]
A molded product was produced in the same manner as in Example 1 except that the mass ratio of the PVC-based resin and the MMA-based resin was changed as shown in Table 1.

[Comparative Example 1]
A molded product was produced in the same manner as in Example 1 except that the mass ratio of the PVC-based resin and the MMA-based resin was changed as shown in Table 1 and both the PVC-based resin and the MMA-based resin were fed from the main hopper 14. bottom.

Table 1 shows the manufacturing conditions and evaluation results of each example.

As shown in Table 1, the molded products of Examples 1 and 2 in which a powdery PVC resin is side-fed to a molten MMA resin have excellent transparency, pencil hardness, and scratch resistance. rice field.
On the other hand, the molded product of Comparative Example 1 in which both the PVC-based resin and the MMA-based resin were fed from the main hopper had poor transparency, low pencil hardness, and poor scratch resistance.

10 ... twin-screw extruder, 12 ... cylinder, 14 ... main hopper, 16 ... side feeder.

Claims (4)

A method for producing an alloy resin, in which a powdered vinyl chloride resin is added to a molten methyl methacrylate resin and melt-kneaded to obtain an alloy resin. Using a twin-screw extruder, the methyl methacrylate-based resin is fed from the main hopper on the upstream side of the cylinder, and the powder-like vinyl chloride-based resin is side-fed to be melt-kneaded with the methyl methacrylate-based resin in a molten state. The method for producing an alloy resin according to claim 1. The method for producing an alloy resin according to claim 2, wherein the temperature of the portion of the cylinder of the twin-screw extruder that side-feeds the vinyl chloride resin is 160 ° C. or higher and 190 ° C. or lower. A method for producing a molded product, which comprises molding the alloy resin produced by the method for producing an alloy resin according to any one of claims 1 to 3 to obtain a molded product.

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