JPS6018285B2 - Manufacturing method of vinyl chloride resin eraser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a vinyl chloride resin eraser.

Regarding erasers, various improvements have been made to their raw material compositions, molding methods, etc.
Particularly in recent years, not only practical aspects but also decorative and toy-like elements have come to be emphasized, leading to higher quality and diversification.

In order to satisfy these demands, for example, a casting method is used in which a base sol made by uniformly mixing an emulsion-polymerized pinyl chloride resin, a plasticizer, and an inorganic filler is poured into a desired mold and then heated and molded. Alternatively, the paste sol is first made into a semi-molten state (semi-gel) using an extruder.
A sol extrusion method is known in which the sol is solidified and then molded into a desired shape using an extruder again. However, the above-mentioned casting method has the problem that only a single color can be obtained due to the molding process, and since the shape of the method is also cut out from a block and manufactured into a product, it is easy to use due to the slow pace. There are many things and it is difficult to diversify,
It also has the disadvantage of extremely low productivity. In addition, the sol extrusion method described above is superior to the casting method in terms of shape and color, and allows for continuous molding, but the process of extruding the paste sol is complicated and the productivity is low. There are some difficulties. Furthermore, in the sol extrusion method, it is necessary to maintain the raw material mixture in a certain molten state, which has the disadvantage of being accompanied by various technical difficulties.

In other words, if the gelation of the raw material mixture progresses beyond the desired degree of gelation, the eraser obtained from this will have poor erasing performance; on the other hand, if the degree of gelation is too low, the eraser obtained will becomes brittle and its commercial value is significantly reduced. The present invention aims to provide a method for producing erasers made of vinyl chloride resin, which eliminates the disadvantages and drawbacks of the conventional methods as described above, and which is applicable to suspension polymerization or bulk polymerization vinyl chloride resin, plastic A standard vinyl chloride resin composition containing 20 parts by weight of a filler, 3 parts by weight of a stabilizer, and 20 parts by weight of a filler was added to a compound mainly consisting of a filler and an inorganic filler, and the conditions of nozzle cross-sectional area and compound temperature were adjusted. When injection molding was performed with various variations, the results shown in Table 1 below were obtained.
To do this, it is necessary to set the nozzle cross-sectional area to 1.0 to 5.0 squares and to set the compound temperature to 80 to 140 degrees. Otherwise, molding will be difficult, and even if molding is possible, The present invention was completed after confirming that the eraser obtained using this method is extremely brittle and cannot be used, or that the eraser effect is poor due to significant gelation.

It is characterized by injection molding under conditions of a nozzle cross-sectional area of 1.0 to 5.0 and a sulfur compound temperature of 80 to 140°C. According to this method, erasers of various shapes and in multiple colors can be produced. can be manufactured easily and economically, and has the effect of having extremely excellent performance as an eraser.

To explain this, the inventors of the present invention have studied various methods of manufacturing preforms made of vinyl chloride resin to solve the above-mentioned disadvantages, and have found that this requires appropriate adjustment of various conditions during injection molding. Judging that, vinyl chloride resin 10
Dioctyl phthalate, a typical plasticizer, is added to the weight part of
Weight of DOP) 20 *Table 1 The method of the present invention uses an injection molding machine having a specific nozzle cross-sectional area as described above, and except that the temperature of the compound is kept within the range described above, the method is generally used for molding vinyl chloride resin. Molding can be carried out using the injection molding machine and injection molding conditions used in Any type of arm-shaped screw injection molding machine can be used, and in the present invention, a molding machine with a strong mold clamping force is not required, and it is preferable to use a molding machine capable of molding.

The vinyl chloride resin used in the present invention must be polyvinyl chloride produced by suspension polymerization or bulk polymerization, or a copolymer mainly composed of polyvinyl chloride. Examples of comonomers used in the coalescence include vinylidene chloride, vinyl acetate, acrylic acid and its esters, acrylonitrile, maleic acid and its esters or anhydrides, fumaric acid and its esters, olefins such as ethylene and propylene, and vinyl esters. be done. These vinyl chloride resins desirably have a weave of 1000 to 350 and an average degree of polymerization of 1200 to 3500 in order to obtain a product with an excellent eraser effect. In the present invention, an acrylic resin may be used in combination with the vinyl chloride resin described above, and examples thereof include conventionally known acrylic resins, acrylonitrile-butadiene-styrene copolymer (A-Mo resin), methyl methacrylate-butadiene copolymer, Gen-styrene copolymer (M Shigeru resin)
, acrylonitrile-styrene copolymer (AS resin),
Examples include acrylonitrile-acrylic rubber styrene copolymer (AAS resin).

These acrylic resins are blended in order to appropriately suppress the rapid progress of gelation during heat molding of the compound, and in order to advantageously achieve the purpose of suppressing gelation. It is necessary to mix 3 to 10 parts by weight of this acrylic resin per 10 parts by weight of the above-mentioned vinyl chloride resin, and in particular, from the viewpoint of erasing effect and cost, the range of 5 to 2 parts by weight is required. It is desirable to do so.

The blending of this acrylic Z resin suppresses the progress of gelation during heat molding, and due to the unique action of this component, the resulting product has performance as an eraser, that is, it has a large frictional resistance and is easily rubbed. Become something. 2 In addition, the plasticizer used in the present invention is essential in order to impart appropriate frictional resistance to the product, and includes various types of plasticizers conventionally used in vinyl chloride resins, such as di-2-ethylhexyl. Phthalate ester plasticizers such as phthalate and dibutyl phthalate, adipic acid ester plasticizers such as di-2-ethylhexyl adibate, sebacic acid ester plasticizers such as di-2-ethylhexyl sepacate, polyesters, and polyurethanes. Examples include polymeric plasticizers such as These plasticizers are preferably used in an amount of usually 50 to 30 parts by weight based on 100 parts by weight of the vinyl chloride resin.

If it is less than 5 parts by weight, the resulting product will have low frictional resistance and will have poor eraser performance, while if it is more than 30 parts by weight, the product will be too soft and the surface will have plasticity. The agent begins to bleed. Furthermore, the inorganic filler used in the present invention is used for the purpose of imparting appropriate frictional resistance and abrasion resistance to the final product, and such fillers include carbonates such as calcium carbonate. Examples include silica, clay, talc, glass powder, silicates such as silica sand, and metal hydrates such as aluminum hydroxide.

When blending these fillers, if the proportion is too large, the rubber elasticity of the product will decrease and the product will break during use, so it should not exceed 60 parts by weight per 10 parts by weight of the vinyl chloride resin. It is preferable to do so. In carrying out the method of the present invention, the above-mentioned vinyl chloride resin, plasticizer, inorganic filler, and various additives such as stabilizers, thickeners, colorants, fragrances, etc., are mixed into a Hexshell mixer.・After charging the mixture into a Banbury mixer or ribbon blender and blending it uniformly while raising the temperature (approximately 100 to 12,000), this mixture is heated using an injection molding machine with a specific nozzle cross-sectional area as described above. 80
It is sufficient to perform molding at a temperature of ~14,000.

Next, examples of the present invention will be given, and all parts in the middle part of the examples are by weight.

However, the product names and abbreviations shown are as follows.

GB-1550 Manufactured by Saint-Gobain Bulky polymerized vinyl chloride resin Polymerization degree 1500 TK-2500 Manufactured by Shin-Etsu Chemical
Suspension polymerized vinyl chloride resin Polymerization degree 2500MC-180
0 Suspension polymerized vinyl chloride-vinyl acetate copolymer resin, manufactured by Shin-Etsu Chemical Co., Ltd. Degree of polymerization: 1800 E-15 Emulsion polymerized vinyl chloride resin, manufactured by Shin-Etsu Chemical Co., Ltd.
Polymerization degree 1450SH-300 Denki Kagaku Co., Ltd. Suspension polymerization vinyl chloride resin Polymerization degree 3500 Whiton SB
Heavy calcium carbonate DOP manufactured by Shiraishi Calcium Co., Ltd.
2-Diethylhexyl phthalate manufactured by Shin Nippon Chemical Co., Ltd. Example Experiments 1 to 5 A mixture having the composition shown in Table 1 below was placed in a henta shell mixer, and the temperature was raised to 120°C using steam.
The mixture was heated to 0.00C and stirred to obtain a powdery mixture.

This powder mixture was molded using an injection molding machine with a nozzle cross-sectional area of 3.0 mm (Nippon Steel Anchor 75 manufactured by Japan Steel Works, Ltd.) under the following conditions (however, the nozzle exit resin temperature and back pressure were Molded under the conditions shown in the table), 10 x 10 x 120 (skin)
I got the character eraser.

Molding conditions Cylinder part 1 temperature 10000 〃 2 temperature 〃 〃 3 temperature 12000 Nozzle part temperature 90qo Nozzle outlet resin temperature 128-1320 Injection molding time
5 seconds cooling time 1 Inkstone sand With the eraser obtained above, the slip resistance was measured according to JISAI407, and the wear loss was measured using a taper abrasion tester (wearing wheel H-22, 1000 rotations). The results are shown in Table 1 below.

The table also shows the erasing performance of letters written on commercially available report paper using a pencil with hardness HB using the eraser obtained above.

*Nezumi 8 Cedar Experiments 6 to 9 using the casting method A composition having the same composition as that used in Experiment 1 was injection molded under the conditions shown in Table 3 below to obtain erasers.

The character erasing performance was investigated and the results are shown in Table 3 below. Table 2 Table 3 *' Sub-temperature ← Garazura molding Taki Noh

Claims (1)

[Claims] 1. A composition mainly consisting of a suspension polymerized or bulk polymerized vinyl chloride resin, a plasticizer, and an inorganic filler,
Nozzle cross-sectional area 1.0-5.0mm^2 Compound temperature
A method for manufacturing a vinyl chloride resin eraser, which comprises injection molding at a temperature of 80 to 140°C.