Manufacturing method for rubber stamp material for laser processing and rubber stamp body

Abstract

To provide rubber stamp materials for laser processing that ensure strength and excel in laser processability and, in addition to them, to provide rubber stamp materials for laser processing that can suppress odor generated during laser processing.SOLUTION: A rubber stamp material for laser processing according to the present invention, which is obtained by kneading and vulcanizing at least rubber, a vulcanizing agent, and a filler, is characterized in that the filler comprises magnesium carbonate. More preferably, the filler comprises at least calcium carbonate or a composite of calcium carbonate and magnesium carbonate.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber stamp material for laser processing. [Background technology]

[0002] Conventionally, rubber stamp materials in which the stamp surface is formed by laser processing have been known. Patent Document 1 describes a rubber stamp material in which calcium carbonate is blended into the base rubber, thereby improving the processability with laser light. However, such a rubber stamp material has room for improvement in tensile strength.

[0003] Various types of fillers are known as reinforcing agents used to increase the strength of rubber stamp materials. Patent Document 2 lists calcium carbonate, colloidal clay, silicon dioxide (silica), carbon black, barium sulfate, magnesium carbonate, and other such fillers. While adding these fillers can increase the strength of rubber stamp materials, depending on the type of filler used, it can also reduce laser processability. For example, substances with high melting points, such as silica, may remain unmelted during laser processing, making the stamp surface difficult to carve.

[0004] Furthermore, when laser processing is performed on rubber stamp materials, there is a problem in that a strong rubber odor is generated as the rubber melts due to heat. Patent Document 3 describes that the rubber odor generated during laser processing can be reduced by using silicone rubber (reactive organopolysiloxane) as a raw material. However, silicone rubber is expensive and requires a long processing time. Another drawback is that it has low tensile strength, which may result in poor reproducibility of small characters, etc. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-42842 [Patent Document 2] Japanese Patent Application Publication No. 7-149032 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-280788 Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to solve the above-mentioned conventional problems and to provide a rubber stamp material for laser processing that ensures strength and is excellent in laser processability, and further to provide a rubber stamp material for laser processing that can also suppress odors generated during laser processing. [Means for solving the problem]

[0007] The inventors have conducted research to solve the above-mentioned problems, and as a result have discovered that by incorporating magnesium carbonate as a filler into the raw materials of rubber stamp materials for laser processing, it is possible to not only increase the strength of the rubber but also to achieve excellent laser processability.

[0008] Furthermore, the inventors have discovered that by incorporating a composite of calcium carbonate and magnesium carbonate into the filler, in addition to the above-mentioned effects, it is also possible to suppress odors generated during laser processing.

[0009] In other words, the rubber stamp material for laser processing of the present invention is a rubber stamp material for laser processing obtained by kneading and vulcanizing at least rubber, a vulcanizing agent, and a filler, and the filler contains a composite of calcium carbonate and magnesium carbonate in an amount of 30 parts by mass to 80 parts by mass per 100 parts by mass of the rubber, and at least a portion of the magnesium carbonate in the composite is decomposed by the laser light used to engrave the stamp surface.

[0010] Preferably, the rubber comprises at least one selected from the group consisting of natural rubber, styrene-butadiene rubber, isoprene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, and ethylene-propylene-diene rubber, and the content of the calcium carbonate and magnesium carbonate composite is 30 to 80 parts by mass per 100 parts by mass of the rubber, thereby suppressing odors generated during laser processing. Preferably, the magnesium carbonate in the composite is decomposed by laser light to form micropores, and the composite's increased surface area captures odors generated during laser processing, thereby suppressing the odors.

[0011] Also provided is a method for manufacturing a rubber stamp body, which includes a step of blending, kneading, and vulcanizing raw materials containing at least rubber, a vulcanizing agent, and a filler to manufacture a rubber stamp material for laser processing, and a step of irradiating laser light onto the surface of the rubber stamp material for laser processing to engrave a stamp surface, wherein the filler contains a composite of calcium carbonate and magnesium carbonate, the blending amount of the composite is 30 to 80 parts by mass per 100 parts by mass of the rubber, and the stamp surface is engraving at a processing temperature at which at least a portion of the magnesium carbonate in the composite is decomposed by the laser light, thereby suppressing odors generated during laser processing. [Effects of the Invention]

[0012] The present invention can provide a rubber stamp material for laser processing that ensures strength and has excellent laser processability, and can also provide a rubber stamp material for laser processing that can suppress odors generated during laser processing. DETAILED DESCRIPTION OF THE INVENTION

[0013] A preferred embodiment of the present invention will be described below. The rubber stamp material for laser processing of the present invention is obtained by kneading and vulcanizing at least rubber, a vulcanizing agent, and a filler.

[0014] (rubber component) The rubber component of the rubber stamp material for laser processing of the present invention may be any of the known natural rubbers, styrene-butadiene rubbers, isoprene rubbers, acrylonitrile-butadiene rubbers, chloroprene rubbers, polyurethane rubbers, acrylic rubbers, ethylene-propylene-diene rubbers, dimethyl silicone rubbers, methylphenyl silicone rubbers, methylvinyl silicone rubbers, etc.

[0015] (vulcanizing agent) Examples of vulcanizing agents (crosslinking agents) that can be used include known sulfur-based vulcanizing agents such as precipitated sulfur, sulfur, selenium, tellurium, and sulfur chloride, and peroxides such as t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane, and 1,3-bis(t-butylperoxy-i-propyl)benzene. These can be used alone or in combination of two or more.

[0016] (filler) The rubber stamp material for laser processing of the present invention contains magnesium carbonate as a filler. The magnesium carbonate content is preferably 5 to 50 parts by mass, and more preferably 10 to 30 parts by mass, per 100 parts by mass of the rubber component. The inclusion of magnesium carbonate as a filler improves the physical properties of the rubber, such as tensile strength, and also improves laser processability, making it easier to achieve laser processing depth. The mechanism by which the inclusion of magnesium carbonate as a filler improves laser processability is unclear, but it may be due to the fact that the decomposition temperature of magnesium carbonate is approximately 350°C, which is roughly the same as the processing temperature using laser light.

[0017] Furthermore, the rubber stamp material for laser processing of the present invention preferably contains calcium carbonate as a filler in addition to the above-mentioned magnesium carbonate. The content of calcium carbonate is preferably 10 to 70 parts by mass, more preferably 30 to 50 parts by mass, per 100 parts by mass of the rubber component. By including magnesium carbonate and calcium carbonate as a filler, the tensile strength and rubber hardness of the rubber can be further increased compared to when magnesium carbonate is added alone.

[0018] Furthermore, it is further preferred that the filler of the rubber stamp material for laser processing of the present invention contains at least a composite of calcium carbonate and magnesium carbonate. In an embodiment, the composite of calcium carbonate and magnesium carbonate is calcium-magnesium carbonate (product name: Haku) which is made by calcining dolomite ore, hydrating it, and carbonating it to form fine particles. gloss Hana AA or White gloss Hana A, manufactured by Shiraishi Kogyo Co., Ltd.) is used. The content of the composite of calcium carbonate and magnesium carbonate is preferably 10 to 100 parts by mass, and more preferably 30 to 80 parts by mass, per 100 parts by mass of the rubber component. However, if the content of the composite of calcium carbonate and magnesium carbonate is 100 parts by mass or more, the rubber becomes too hard, which is not preferable.

[0019] By including a composite of calcium carbonate and magnesium carbonate in the filler, it is possible to suppress odors generated during laser processing. The mechanism of odor suppression is unclear, but it is believed to occur as follows: (1) The magnesium carbonate in the composite of calcium carbonate and magnesium carbonate is decomposed by laser light. (2) The areas where the magnesium carbonate is decomposed become micropores, increasing the surface area of ​​the composite. (3) The composite with its increased surface area captures odors generated during laser processing.

[0020] In addition to the above, the filler may also contain clay, talc, mica, magnesium silicate, calcium silicate, metal oxide-coated mica in which mica is coated with silicon oxide, antimony oxide, tin oxide, black iron oxide, red iron oxide, etc. These may be used alone or in combination of two or more.

[0021] (Additives) Furthermore, various additives can be added to the laser-processed rubber stamp material of the present invention as needed. For example, effective amounts of amine-based antioxidants, softeners such as petrolatum and plasticizers, vulcanization aids such as zinc oxide, and guanidine-based vulcanization accelerators can be added. These can also be used alone or in combination of two or more.

[0022] (Manufacturing method) The method for producing the rubber stamp material for laser processing of the present invention is not particularly limited, and it can be obtained by blending, kneading, and vulcanizing the raw materials by a known method.

[0023] (laser processing) The stamp face of the laser-processable rubber stamp material of the present invention is produced by engraving with a laser beam. Laser beam engraving is performed using a laser processing machine. The laser processing machine used in the present invention can be any known laser processing machine, including various lasers such as carbon dioxide lasers and YAG lasers, and various drive systems such as XY table systems and rotary table systems. After engraving, the laser-processable rubber stamp material is removed from the laser processing machine, and the surface and interior are cleaned in a cleaning machine to remove rubber and carbon debris, and then dried in a dryer. [Example]

[0024] According to the formulation shown in Table 1, rubber, vulcanizing agent, filler, etc. were kneaded and vulcanized to prepare samples of rubber stamp materials for laser processing of Examples 1 to 3 and Comparative Example 1.

[0025] [Table 1]

[0026] <Evaluation> (Laser processing depth and laser processability) After preparation, each sample was stored at 25°C for one week, and then a certain area (approximately 50mm x 20mm) of the stamp was engraved using a carbon dioxide laser (processing conditions: output 80W, processing speed 250mm / sec, same processing character used), followed by washing and drying. The processing depth of the sample was measured immediately after drying, and the processed stamp was evaluated as follows. ◯: The portion not irradiated with the laser beam was not melted, and a print surface with sharp edges was formed. ×: The portion not irradiated with the laser beam was melted, forming an uneven print surface.

[0027] (Other characteristics) After laser processing, each sample was evaluated for bottom discoloration (◯: no discoloration, ×: discoloration), cleanability (◯: good, ×: poor), and stickiness (◯: no stickiness, ×: stickiness).

[0028] (hardness) Hardness was measured by placing the test piece of rubber stamp material for laser processing on a hard, rigid, flat surface, holding an A-type hardness tester so that the indenter was perpendicular to the measurement surface of the rubber stamp material for laser processing, and then pressing the test piece against the measurement surface as quickly as possible without applying impact to the pressurized surface, and reading the scale. This measurement method conforms to JIS K6253. It is recommended that the hardness of the rubber stamp material be approximately 60±3 as measured with an A-type hardness tester. A hardness of approximately 60 to 63 is even more preferable.

[0029] (tensile strength) The tensile strength was measured in accordance with the tensile test method for vulcanized rubber JIS6251, and the test specimens were dumbbell-shaped No. 2.

[0030] (Odor immediately after laser processing) The rubber odor emitted from the samples immediately after drying was evaluated by a sensory test conducted by three judges. The evaluation criteria for the sensory test were as follows. The evaluations by the three judges for each sample were the same. Good: When you bring your nose close to the sample (about 5 cm), you can detect a weak odor. △: When you bring your nose close to the sample (about 5 cm), you can smell a strong odor. ×: A strong odor can be detected even without bringing your nose close to the sample (about 30 cm).

[0031] (result) As shown in Table 1, the laser processability and laser processing depth were both good in each of the Examples and Comparative Example 1. Other properties were also good, and the hardness values ​​were almost the same in all of the Examples, all of which were within the suitable range. The tensile strength showed a significant difference between each of the Examples and Comparative Example 1. Examples 1 to 3, which contained basic magnesium carbonate as a filler, showed a higher tensile strength than Comparative Example 1, which did not contain basic magnesium carbonate.

[0032] Furthermore, as mentioned above, in terms of laser processability and laser processing depth, although Example 1 did not contain calcium carbonate, which improves laser processability, it showed results as good as those of Comparative Example 1. This demonstrates that the inclusion of magnesium carbonate in the filler has the effect of improving not only tensile strength but also laser processability.

[0033] Furthermore, comparing Example 1 and Comparative Example 1 in terms of the amount added, Example 1 exhibited a greater tensile strength than Comparative Example 1, even though the amount of calcium carbonate added in Comparative Example 1 was 50 parts by mass, while the amount of basic magnesium carbonate added in Example 1 was only 13 parts by mass. In other words, basic magnesium carbonate can increase the strength of rubber in a smaller amount than calcium carbonate. Similarly, it can be said that basic magnesium carbonate can improve laser processability in a smaller amount than calcium carbonate.

[0034] Next, the tensile strengths of the respective Examples will be compared. First, comparing Example 1 with Example 2, it can be seen that the tensile strength is further increased by adding calcium carbonate in addition to basic magnesium carbonate. Furthermore, comparing Example 2 with Example 3, it can be seen that the tensile strength of the rubber is further increased when basic magnesium carbonate and calcium carbonate are contained as a composite, as in Example 3, compared to when these are contained alone, as in Example 2.

[0035] Next, when comparing the odor immediately after laser processing between each example and comparative example 1, it was found that example 3, which contains a calcium carbonate / basic magnesium carbonate composite, had a significant effect in suppressing odor.

[0036] The present invention has been described above using examples of embodiments that are currently considered to be the most preferred, but the present invention is not limited to the above embodiments and can be modified as appropriate within the scope of the claims and the gist or concept of the invention as can be read from the entire specification.

Claims

1. A rubber stamp material for laser processing obtained by kneading and vulcanizing at least rubber, a vulcanizing agent, and a filler, The filler contains a composite of calcium carbonate and magnesium carbonate in an amount of 30 parts by mass or more and 80 parts by mass or less per 100 parts by mass of the rubber, A rubber stamp material for laser processing, characterized in that at least a part of the magnesium carbonate in the composite is decomposed by the laser beam used to engrave the stamp face.

2. The rubber comprises at least one selected from the group consisting of natural rubber, styrene-butadiene rubber, isoprene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, and ethylene-propylene-diene rubber; A rubber stamp material for laser processing as described in claim 1, characterized in that the content of the calcium carbonate and magnesium carbonate composite is 30 parts by mass or more and 80 parts by mass or less per 100 parts by mass of the rubber, thereby suppressing the odor generated during laser processing.

3. A rubber stamp material for laser processing as described in claim 1 or 2, characterized in that the magnesium carbonate in the compound is decomposed by laser light to form micropores, and the compound with an increased surface area suppresses odors generated during laser processing by capturing the odors.

4. A process for producing a rubber stamp material for laser processing by compounding, kneading, and vulcanizing raw materials containing at least rubber, a vulcanizing agent, and a filler; a step of irradiating a surface of the rubber stamp material for laser processing with laser light to engrave a stamp surface, the filler contains a composite of calcium carbonate and magnesium carbonate, and the blending amount of the composite is 30 parts by mass or more and 80 parts by mass or less per 100 parts by mass of the rubber, A method for manufacturing a rubber stamp body, characterized in that the stamp surface is engraved at a processing temperature at which at least a portion of the magnesium carbonate in the compound is decomposed by the laser light, thereby suppressing odors generated during laser processing.

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