JPH0250139B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a vinyl chloride resin composition for erasing. ``Prior Art'' Currently, erasers made of synthetic rubber and vinyl chloride resin are often used. However, depending on the type of paper, the former may contaminate the surface of the paper, and the shavings often stick to the eraser, and the biggest drawback in commercially available products is that it is opaque. This is not aesthetically pleasing. The latter is manufactured from vinyl chloride resin with an average degree of polymerization of 1000 or more, and it alone has little eraser effect, and the shavings after erasing are difficult to separate from the eraser, and calcium carbonate, glass powder, etc. Various fillers such as these are blended to improve the erasing effect (erasing effect) and the separation effect of shavings. This improved eraser is opaque because it contains a filler, and even if it is colored, it cannot be beautiful. "Problems to be Solved by the Invention" As a result of intensive study on the erasability of erasers made of vinyl chloride resin, the present inventors discovered that the main components were vinyl chloride resin with a low degree of polymerization and a small amount of epoxidized resin. If you create an eraser with a plasticizer containing soybean oil,
It was discovered that the eraser has excellent erasability even without the use of fillers, the shavings can be easily separated from the eraser, and since it is transparent, it can be easily colored, resulting in an extremely aesthetically pleasing eraser. . That is, an object of the present invention is to provide a vinyl chloride resin composition for erasing characters that exhibits the above-mentioned effects. ``Means to solve the problem'' The gist of this is that vinyl chloride resin with an average degree of polymerization of 800 or less is added as a plasticizer.
The present invention relates to a vinyl chloride resin composition for erasing, which contains dioctyl phthalate or dioctyl adipate and epoxidized soybean oil. To explain the present invention in detail, the vinyl chloride resin used in the present invention is not limited to a homopolymer of vinyl chloride, but mainly contains vinyl chloride, and comonomers copolymerizable with vinyl chloride, such as vinylidene chloride, Examples include copolymers with vinyl acetate, vinyl propionate, vinyl butyrate, methyl acrylate, methyl methacrylate, ethyl methacrylate, maleic acid, maleic anhydride, and the like. and,
The method for producing vinyl chloride resin is not particularly limited either, and it may be obtained by suspension polymerization or emulsion polymerization. However, from the viewpoint of transparency, vinyl chloride homopolymer is preferred. Therefore, the average degree of polymerization of vinyl chloride resin is
It is necessary that it is 800 or less, and it is preferably in the range of 100 to 600, particularly in the range of 200 to 500. Erasers obtained from compositions using vinyl chloride resins with an average degree of polymerization greater than 800 show that the shavings do not separate easily from the eraser;
Erasers obtained from compositions using polymers with a molecular weight of less than 100 tend to become brittle and have poor erasing effects as the average degree of polymerization decreases. The vinyl chloride resin composition of the present invention contains a plasticizer for vinyl chloride resin as one of its components. The plasticizer is a two-component or three-component combination of dioctyl phthalate or dioctyl adipate and a small amount of epoxidized soybean oil. By doing so, not only the erasability and transparency are excellent, but also the shavings are easily separated from the eraser. Of course, other plasticizers can also be added within a range that does not impair the eraser performance. Therefore, the blending ratio of the plasticizer is 30 to 150 parts by weight, preferably in the range of 50 to 100 parts by weight, per 100 parts by weight of the vinyl chloride resin.
The blending ratio of epoxidized soybean oil in the plasticizer is 0.5 to 8 parts by weight, preferably 1 to 5 parts by weight, and especially around 2 parts by weight per 100 parts by weight of vinyl chloride resin. preferable. Based on the composition of the plasticizer, it is approximately 0.2 to 43% by weight, preferably 1 to 43% by weight.
Preferably, about 15% by weight, especially from 1 to 10% by weight, is epoxidized soybean oil. The resin composition of the present invention may also contain a stabilizer commonly used for vinyl chloride resins. Stabilizers that do not cause the composition to lose transparency include barium stabilizers, calcium stabilizers, tin (Sn) stabilizers, and zinc stabilizers. It is desirable to have at least one selected type present. Of course, commercially available calcium-zinc (Ca-Zn) and barium-zinc (Ba
It is also possible to use composite stabilizers such as -Zn-based). Therefore, the amount of these stabilizers added is 0.1 parts by weight per 100 parts by weight of the total amount of vinyl chloride resin and plasticizer.
Preferably, it is used in a proportion of ~10 parts by weight. In addition, the composition of the present invention may contain lubricants such as stearic acid, fillers such as calcium carbonate and glass powder, and additives such as pigments and dyes within a range that does not impair eraser performance or aesthetic appearance. Can be done. To produce the composition of the present invention, vinyl chloride resin, plasticizers, stabilizers, and other additives are added,
Mixing is performed by a conventional known method, for example, using a general-purpose mixer such as a mixing roll, an extruder, a Banbury mixer, a Henschel mixer, or a kneader. In order to obtain an eraser from the composition of the present invention, the composition is heated to gel. Depending on the desired shape, various molding methods such as injection molding, extrusion molding, pressure molding, and cast molding can be used as appropriate. "Effects" The eraser obtained from the vinyl chloride resin composition of the present invention has extremely good transparency and exhibits an excellent erasing effect, and the shavings after erasing are easily separated from the eraser. It has no character erasing function. In addition, since the eraser is transparent, it can be colored as desired and is beautiful, making it extremely useful as a toy and eraser. "Examples" The present invention will be described in detail below with reference to Examples, but the present invention is not limited to the following Examples unless it deviates from the gist thereof. In addition, "parts" in the examples indicate "parts by weight." Examples 1 to 4 and Comparative Examples 1 to 3 2 parts of epoxidized soybean oil and 0.5 part of stearic acid were blended with 100 parts of vinyl chloride resin having various average degrees of polymerization shown in Table 1 and 76 parts of various plasticizers. , and were thoroughly mixed to obtain a vinyl chloride resin composition for erasing. The composition was heated to a diameter of 230 mmφ, a length of 350 mm, and a rotation speed.
The mixture was kneaded for 5 minutes using rolls heated to 120° C. at 17 rpm and a rotation ratio of front and rear rolls of 1:1.25 to obtain a composition sheet with a length of 2 mm. This sheet was heated to 150℃ for 2 hours.
The material was preheated for 1 minute, heated and pressed at the same temperature and under a pressure of 190 to 200 kg/cm ² , and then cooled to room temperature to obtain an eraser with a thickness of 7 mm, width of 20 mm, and length of 30 mm. The erasing effect was examined using the test machine shown in the drawing, and the transparency was observed, and the results are shown in Table 1. A commercially available eraser (containing vinyl chloride resin and filler) was also tested. To manufacture the erasability tester, as shown in the drawing, a clamp holder 4 having a weight of 2 kg is reciprocated on the base 1 by rotating a handle 3 via a base 1 and a column 2 attached to it. It consists of a crank device. 5 indicates a pencil or eraser. [Erasability test method] An HB pencil (Mitsubishi 9800) was fixed to the clamp holder 4,
Once on the paper surface on the base 1 by rotating the handle 3,
A line with a thickness of 2 mm and a length of 50 mm was drawn, and then the pencil was changed to an eraser, and the number of reciprocating movements (one time for each forward and back movement) until the line disappeared was measured to determine the erasability. . [Transparency observation test method] Place the same eraser as in the above examples and comparative examples on a 2 cm ² size letter written with an HB pencil on white paper, and observe the visibility of the letter with the naked eye. It was evaluated as follows. The thickness of the commercially available letter eraser was adjusted to 7 mm. ◎ Brightly visible 〇 Fully visible △ Difficult to see × Not visible at all

【table】

[Table] From the above results, the eraser obtained from the composition of the present invention has extremely excellent erasability and transparency, and the shavings after erasing can be separated from the eraser very easily. An eraser obtained from a vinyl chloride resin having a high average degree of polymerization has an erasability that is not as good as an eraser obtained from the composition of the present invention, and is also inferior in terms of transparency. And the shavings do not separate from the eraser. Commercially available erasers contain a filler, so they have erasability comparable to that of the present invention, but they roughen the paper surface. It is also opaque. Furthermore, the shavings get stuck in the eraser. Examples 5 to 7 Erases were molded in the same manner as in Example 4, except that some of the stabilizers shown in Table 2 were added to the composition of Example 4, and eraseability and transparency were examined. .

[Table] By using a specific stabilizer, the composition of the present invention can be obtained without losing its transparency.

[Brief explanation of drawings]

The drawing is a front view of the erasability tester. In the figure, 1 is the base, 2 is the support, 3 is the handle, 4
5 indicates a clamp, and 5 indicates a pencil or eraser.

Claims (1)

[Claims] 1. A vinyl chloride resin composition for erasing, which is prepared by adding dioctyl phthalate or dioctyl adipate as a plasticizer and epoxidized soybean oil to a vinyl chloride resin having an average degree of polymerization of 800 or less. 2 The average degree of polymerization of the vinyl chloride resin is 100 to 600.
A vinyl chloride resin composition for erasing according to claim 1. 3. The eraser resin composition according to claim 1, wherein the plasticizer is contained in an amount of 30 to 150 parts by weight based on 100 parts by weight of the vinyl chloride resin. 4 Claim 1 containing at least one stabilizer selected from barium stabilizers, calcium stabilizers, tin stabilizers, and zinc stabilizers
The vinyl chloride resin composition for erasing characters as described in .