JP2022049644A - Eraser - Google Patents

Abstract

To provide an eraser with a low environmental load and excellent productivity with erasing equal to or better than the conventional eraser using a phthalate ester plasticizer.SOLUTION: There is provided an eraser that uses a vinyl chloride resin as the base resin and does not virtually contain a phthalate ester plasticizer. As a plasticizer, polyester adipate, which is a non-phthalate ester plasticizer, and tributyl acetylcitrate are blended. The blending amount of these plasticizer components is in the range of polyester adipate: tributyl acetylcitrate equals 75:25 to 90:10 in terms of mass ratio.SELECTED DRAWING: None

Description

The present invention relates to a plastic eraser containing a vinyl chloride resin as a main component, and more particularly to a plastic eraser using a non-phthalate ester-based plasticizer.

"Eraser", which is used to erase characters and pictures written with a pencil, is also called "eraser". In the past, natural rubber was used as the main component, but in recent years, plastic has excellent erasability. The mainstream is the one whose main component is. Such a plastic eraser is manufactured by blending a base resin such as polyvinyl chloride with a plasticizer and various additives.

Phthalic acid-based plasticizers are generally used as plasticizers to be blended in plastic erasing, but in recent years, there has been an increasing movement to regulate the use of phthalates from the viewpoint of reducing the environmental burden. There is also a need to switch to non-phthalate plasticizers for erasing. Examples of the plastic erasing using a non-phthalic acid-based plasticizer include those using a sebacic acid diester (see Patent Document 1), those using a liquid acrylic polymer (see Patent Document 2), and cyclohexane-1,2. -There are those using a dicarboxylic acid ester (see Patent Document 3).

In addition, by using an alkylsulphonic acid phenyl ester and a cyclohexanedicarboxylic acid ester together as a plasticizer, in addition to reducing the environmental load, the original performance of the eraser such as eraser and migration resistance of the plasticizer has been improved. An attempted eraser has been proposed (see Patent Document 4). In the eraser described in Patent Document 4, a vinyl chloride resin is used as the base resin because of its excellent miscibility with the plasticizer and the eraser power.

Japanese Unexamined Patent Publication No. 2007-21768 Japanese Unexamined Patent Publication No. 2009-196119 Japanese Unexamined Patent Publication No. 2010-167717 Japanese Unexamined Patent Publication No. 2012-166483

However, the eraser described in Patent Documents 1 to 3 has "eraser", "plasticizer migration resistance" or "handleability" as compared with the conventional eraser using a phthalate ester-based plasticizer. There is a problem that it is inferior. On the other hand, the eraser described in Patent Document 4 solves these problems and uses a non-phthalate ester-based plasticizer to improve "eraserability" and "transfer resistance of the plasticizer". However, sufficient eraser performance has not yet been obtained.

Therefore, it is an object of the present invention to provide an eraser having a low environmental load, having an eraser equal to or higher than that of a conventional eraser using a phthalate ester plasticizer, and having excellent productivity. And.

The erasing according to the present invention contains at least a vinyl chloride resin and a plasticizer, and the plasticizer is polyester adipate and tributyl acetylcitrate, and the blending amount of these plasticizer components is a mass ratio. Polyester adipic acid: Tributyl acetylcitrate = 75:25 to 90:10.
In the eraser of the present invention, for example, 120 to 170 parts by mass of polyester adipate and tributyl acetylcitrate can be added to 100 parts by mass of the vinyl chloride resin.
In that case, polyester adipate and tributyl acetylcitrate may be blended in a total amount of 150 to 167 parts by mass with respect to 100 parts by mass of the vinyl chloride resin, or with respect to 100 parts by mass of the vinyl chloride resin. , Polyester adipate and tributyl acetylcitrate may be blended in a total amount of 129 to 157 parts by mass.
For the eraser of the present invention, for example, polyester adipic acid having a molecular weight of 800 to 1200 is used.

According to the present invention, polyester adipate and tributyl acetylcitrate are used as plasticizers instead of phthalate ester plasticizers, and these are blended in a specific ratio, so that the environmental load is low and phthalate is used. It has the same or better erasability as the conventional product using an acid ester-based plasticizer, and can realize erasure with excellent productivity.

Hereinafter, embodiments for carrying out the present invention will be described in detail. The present invention is not limited to the embodiments described below.

The erasing according to the embodiment of the present invention contains at least a vinyl chloride resin and a plasticizer, the plasticizer is polyester adipate and tributyl acetylcitrate, and substantially contains a phthalate ester plasticizer. It doesn't.

[Vinyl chloride resin]
The vinyl chloride-based resin is the main component of the erasing of the present embodiment, and in addition to the polyvinyl chloride homopolymer (polyvinyl chloride), the vinyl chloride-vinyl acetate copolymer and the vinyl chloride-methyl acrylate copolymer. Copolymers of vinyl chloride and other monomers such as combined, vinyl chloride-methyl methacrylate copolymer and vinylidene chloride-vinyl chloride copolymer can also be used, and these can be used alone or mixed. May be used.

The amount of the vinyl chloride resin blended in the eraser of the present embodiment is not particularly limited and can be appropriately set according to the required performance and physical properties, but generally all of the erasers are used. It is 25 to 40% by mass of the mass.

[Plasticizer]
The plasticizer is for maintaining the flexibility of the vinyl chloride resin, and in the erasing of the present embodiment, it is a non-phthalate ester-based plasticizer, and polyester adipate and acetylcitrate having excellent erasability. Use tributyl. However, when the blending amount of polyester adipic acid is less than 75% by mass of the total amount of the plasticizer, the heating temperature range (hereinafter referred to as "stable temperature range") in which the eraser of the desired performance can be stably produced becomes narrow. .. Further, when the blending amount of the polyester adipate exceeds 90% by mass of the total amount of the plasticizer, the viscosity becomes high when the raw material composition is mixed and stirred, and the workability of stirring and defoaming is lowered. Therefore, the blending amount of the polyester adipate and the tributyl acetylcitrate is set to polyester adipate: tributyl acetylcitrate = 75:25 to 90:10 in terms of mass ratio.

By blending polyester adipate and tributyl acetylcitrate as the plasticizer in the above-mentioned ratios, high erasability can be realized in a wide temperature range and the exudation (transferability) of the plasticizer can be reduced. Can be done. Further, when the raw material composition is mixed and stirred, the increase in viscosity can be suppressed and maintained in an appropriate range, so that stirring and defoaming become easy.

Further, the amount of the plasticizer to be blended in the eraser can be appropriately adjusted according to the type and amount of the vinyl chloride resin as the main component, but the polyester adipate with respect to 100 parts by mass of the vinyl chloride resin. And tributyl acetylcitrate is preferably 120 to 170 parts by mass in total. By setting the blending amount of the plasticizer within this range, the eraser performance and transfer resistance of the obtained eraser can be improved. From the viewpoint of expanding the stable temperature range, the total amount of polyester adipate and tributyl acetylcitrate to be blended is preferably 150 to 167 parts by mass, and from the viewpoint of improving migration resistance, polyester adipate and The total amount of tributyl acetylcitrate to be blended is preferably 129 to 157 parts by mass.

The blending amount of the plasticizer is not limited to the above-mentioned range, and can be appropriately set according to the application and the required performance. For example, in the application where hardness is required, polyester adipate and acetyl are used. The total amount of tributyl citrate may be less than 120 parts by mass with respect to 100 parts by mass of the vinyl chloride resin. Further, as the polyester adipate used as a plasticizer, it is preferable to use a polyester having a molecular weight of 800 to 1200 from the viewpoint of workability during production, particularly during mixing and stirring. As a result, the increase in viscosity can be suppressed and maintained within an appropriate range.

[filler]
A filler is added to the eraser of the present embodiment as needed. The filler has the effect of adjusting the hardness of the erasable, making it easier to generate erasable debris, and reducing the frictional resistance with the paper surface. For example, calcium carbonate, magnesium oxide, talc, silica, diatomaceous earth, quartz powder, and zeolite. Etc. can be used. The above-mentioned filler may be used alone, or may be used in combination of two or more.

[Other ingredients]
In addition to the above-mentioned components, a stabilizer, a colorant, a fragrance, or the like may be blended in the eraser of the present embodiment as long as the effect of the present invention is not affected.

[Production method]
In the eraser of the present embodiment, for example, a raw material composition obtained by blending each of the above-mentioned components in a predetermined amount is mixed, stirred, defoamed, heat-molded into a predetermined shape, and cooled. Obtained by

As described in detail above, the erasing of the present embodiment uses polyester adipate, which is a non-phthalate ester plasticizer, and tributyl acetylcitrate, which are non-phthalate plasticizers, and substantially uses a phthalate ester plasticizer. Since it is not contained, it is possible to reduce the environmental load while maintaining the erasing performance equal to or higher than that of the conventional erasing. Further, in the erasing of the present embodiment, since the blending ratio of the polyester adipate and the tributyl acetylcitrate is within a specific range, the plasticizer has excellent migration resistance, and the stable temperature range is wide, and the mixture is mixed. Since the viscosity at the time of stirring is low, it is also excellent in productivity.

Hereinafter, the effects of the present invention will be specifically described with reference to Examples and Comparative Examples.

(First Example)
First, as the first embodiment of the present invention, two kinds of polyvinyl chlorides (PVC-1 and PVC-2) having different molecular weights are used as the base resin, and the plasticizers polyester adipate and tributyl acetylcitrate are used. Erasers were created by changing the compounding ratio, and the performance was evaluated. In addition, as a reference example, an eraser was prepared using a phthalate ester as a plasticizer and evaluated in the same manner.

<Preparation of evaluation sample>
A raw material composition containing the raw materials having the composition shown in Table 1 below was stirred and defoamed, and then heat-molded to prepare a substantially square columnar eraser. In addition, "PVC-1" shown in Table 1 below is polyvinyl chloride having a K value of 72, "PVC-2" is polyvinyl chloride having a K value of 66, and "PVC-1" has a larger molecular weight. .. Among the plasticizers, "polyester adipic acid A" is polyester adipic acid having a molecular weight of 800, and "polyester adipic acid B" is polyester adipic acid having a molecular weight of 1200, and the blending ratio of each plasticizer component is% by mass. .. Further, calcium carbonate was used as the filler.

<Evaluation>
Each of the erasers of Examples and Comparative Examples produced by the above-mentioned method was evaluated for "eraser rate", "production stability", "viscosity", and "plasticizer migration" by the methods and criteria shown below. ..

[Character erasure rate]
The erasure rate was calculated based on the "erasure ability test" specified by the Japan Erasing Industry Association. Specifically, a plate-shaped evaluation sample having a thickness of 5.0 ± 0.2 mm was cut out from the eraser of Examples and Comparative Examples, and the contact portion with the test paper (JIS S 6050) had a radius of 6 ± 1 mm. The test piece was finished so as to form an arc of. The test piece is brought into contact with the colored paper so as to be perpendicular to the colored paper and perpendicular to the colored line, and the weight is placed so that the sum of the masses of the weight and the holder is 0.5 kg. Was set to 150 ± 10 cm / min and reciprocated 4 times to perform abrasion.

With a densitometer, the density of the non-colored portion of the colored paper was set to 0, the density C of the colored portion and the density M of the erasable portion were measured, respectively, and the erasing rate E (%) was calculated from the following formula 1. In this example, the erasure and the erasure portion concentration were measured 5 times for one sample, and the average value of the erasure rate was obtained.

Judgment was ◎ (excellent) when the erasure rate (average value of 5 times) was higher than 97.5%, ○ (good) when it was 94.5% to 97.5%. Those that were less than 5% were marked as Δ (possible).

[Production stability]
For the production stability, the erasers of Examples and Comparative Examples were prepared by changing the heating temperature at the time of production, and the stable temperature region was obtained from the heating temperature dependence of the eraser rate and evaluated by the value. Judgment is that the temperature range where the erasure rate (average value of 5 times) is 90% or more is 20 ° C or higher is ◎ (excellent), and the temperature range where the erasure rate is 90% or more is less than 20 ° C. ○ (good) if the temperature range of 80% or more was 15 ° C or higher, △ (possible) if the temperature range of 80% or more was 10 ° C or higher and lower than 15 ° C, and the erasure rate was 80. Those in which the temperature range of% or more was less than 10 ° C. were marked with x (impossible).

〔viscosity〕
The viscosity of the composition before molding was measured with a B-type viscometer in a temperature environment of 23 ° C. In the judgment, those having a viscosity of less than 2800 mPa · s were evaluated as ◯ (pass), and those having a viscosity of 2800 mPa · s or more were evaluated as × (fail).

[Migration of plasticizer]
In the transferability test, a pencil (a hexagonal pencil coated with the coating film specified in JIS S 6006) is cut into a length of 40 mm, and this is cut from each eraser of Examples and Comparative Examples to a length of 40 mm. Two pieces were arranged so as to be parallel to the long side of the test piece on the test piece cut out to have a width of 35 mm, a width of 15 mm or more and a thickness of 5 mm or more, and a weight of 20 g was placed on the test piece. In that state, the test piece was placed in an incubator at 60 ± 2 ° C. and allowed to stand for 1 hour, and then the test piece was taken out and the state of adhesion of the pencil paint to the test piece was visually confirmed.

The transferability of the plasticizer was evaluated in the following five stages, and those with an evaluation score of 5 were evaluated as ◎ (excellent), those with an evaluation score of 4 were evaluated as ○ (good), and those with an evaluation score of 3 were evaluated as △ (possible). Those that were 2 and 1 were marked as x (impossible).
5: No paint adhesion (paint adhesion area is 0%)
4: Almost no paint adhesion (paint adhesion area is approximately 5% or less)
3: The paint was slightly adhered (the paint adhered area was approximately 10% or less).
2: Paint adhered to a wide area (paint adhesion area is approximately 80% or less)
1: Paint adhered to almost all areas (paint adhesion area exceeds approximately 80%)

〔Comprehensive judgment〕
In the comprehensive judgment, if there is at least one x in the above-mentioned evaluation items, there is no x (impossible), if there is no x but there is at least one △, there is ◎ or ○, but there is no △ (possible), × or △. If there is even one ○, even if there is ◎, it is judged as ○ (good). The above results are summarized in Table 2 below.

As shown in Table 2 above, the eraser of Comparative Example 1 in which tributyl acetylcitrate is not blended (the blending amount of polyester adipate is more than 90% by mass of the total plasticizer) has a high viscosity and is suitable for production. It was not suitable. On the other hand, in the erasers of Comparative Examples 2 to 4 in which the blending amount of the polyester adipate was less than 75% by mass of the total amount of the plasticizer, the eraser rate was equal to or higher than that of the reference example, but the transferability was inferior. ..

On the other hand, the erasers of Examples 1 to 6 in which polyester adipate and tributyl acetylcitrate were blended within the scope of the present invention were found in all items of eraser rate, temperature stable region, viscosity and transferability. It had the same or better performance as the eraser using the phthalate ester shown in the reference example.

(Second Example)
Next, as a second embodiment of the present invention, an eraser was produced by changing the blending ratio of the base resin and the plasticizer, and the performance was evaluated by the same method and conditions as in the first embodiment. The composition of the samples evaluated in this example is shown in Table 3 below, and the evaluation results of each sample are shown in Table 4 below.

As shown in Tables 3 and 4, polyester adipate and tributyl acetylcitrate were blended in a total range of 150 to 167 parts by mass with respect to 100 parts by mass of the vinyl chloride resin. The erasers E to I were excellent in dependence on the heating temperature. In addition, No. 1 in which polyester adipate and tributyl acetylcitrate were blended in a total range of 129 to 167 parts by mass. The erasers A to G had excellent migration resistance. No. 1 shown in Tables 3 and 4 above. Since the erasing of A to J contains polyester adipate and tributyl acetylcitrate within the scope of the present invention, it is comparable to the erasing using the phthalate ester shown in Table 2. ..

From the above results, according to the present invention, an eraser having a low environmental load, having an eraser equal to or higher than that of a conventional eraser using a phthalate ester plasticizer, and having excellent productivity can be obtained. It was confirmed that it could be realized.

Claims (5)

With vinyl chloride resin,
With a plasticizer,
Contains at least
The plasticizer is polyester adipate and tributyl acetylcitrate, and the blending amount of these plasticizer components is polyester adipate: tributyl acetylcitrate = 75: 25 to 90:10 in terms of mass ratio. The eraser according to claim 1, which contains 120 to 170 parts by mass of polyester adipate and tributyl acetylcitrate in total with respect to 100 parts by mass of the vinyl chloride resin. The eraser according to claim 2, wherein the polyester adipate and tributyl acetylcitrate are contained in a total amount of 150 to 167 parts by mass with respect to 100 parts by mass of the vinyl chloride resin. The eraser according to claim 2, wherein the polyester adipate and tributyl acetylcitrate are contained in a total amount of 129 to 157 parts by mass with respect to 100 parts by mass of the vinyl chloride resin. The eraser according to any one of claims 1 to 4, wherein the polyester adipic acid has a molecular weight of 800 to 1200.