JP2011121120A - Projection material for blasting and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection material for blasting capable of mirror-finishing or smoothening, without producing satin finished surface-like irregularities, the surface of a workpiece in a very shorter time than in the case of conventional techniques such as polishing or the like by abrasive paper or abrasive cloth, and also provide a method of manufacturing the projection material for blasting. <P>SOLUTION: This projection material for blasting is formed by supporting an abrasive material 12 of 1-50 μm on the surfaces of vinyl chloride particles 11 of 10-3,000 μm in diameter. The projection material is manufactured by kneading, while heating, polyvinyl chloride particles, an abrasive material, a plasticizer, and a molding assistant 13. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a projection material for reducing the surface roughness of a processed surface and making the processed surface a mirror surface, a glossy surface, or the like in blast processing in which a projection material is sprayed onto the processed surface.

  Conventionally, as a polishing method for reducing the surface roughness of the processing surface and making the processing surface a mirror surface or a glossy surface, polishing with a polishing paper or a polishing cloth, polishing with a buff, lapping, etc. In addition, polishing by contact with rotating abrasive grains has been used. However, in any of the polishing methods, a considerable processing time is required until the processed surface is finished to a mirror surface or a glossy surface. Therefore, attempts have been made to reduce the processing time by applying blasting to the processing.

  Blasting is a method of processing a surface to be processed by injecting a projection material such as ceramics, metal, or resin onto the surface to be processed. Although the processed surface can be processed in a short time, a satin-like unevenness is likely to be formed on the processed surface due to the collision of the projection material, which is not suitable for making the processed surface into a mirror or glossy surface.

  In order to suppress the formation of textured irregularities and to make the surface to be processed mirror or glossy, for example, Patent Document 1 discloses a projection material in which gelatin is used as a core, and abrasive and water are contained therein. It has been proposed to use However, since the water in the projection material evaporates during blasting, a textured surface unevenness is formed on the surface to be processed, and therefore it is necessary to replenish the projection material with water regularly. Therefore, the blasting apparatus becomes complicated (for example, see Patent Document 2).

  In Patent Document 3, it is proposed to use a projection material obtained by mixing 10 to 90% by mass of an abrasive with rubber or a thermoplastic elastomer. However, when the content of the abrasive is small, the life as a projection material is short due to, for example, clogging, and it is necessary to frequently replace it with a new one from a blasting apparatus, resulting in poor efficiency. On the other hand, when the content of the abrasive is large, for example, when it is 70% by mass or more, the abrasive is easily removed from the rubber or elastomer, and the new surface appears, so that the above-mentioned clogging does not occur and the projection is performed. Although it has a long life as a material and has a good polishing ability continuously, the abrasive material is relatively expensive, which increases the price of the projection material.

JP 2001-207160 A JP 2009-190108 A JP 2006-159402 A

  The present invention has been made to solve the above-described problems, and suppresses the formation of matte-like irregularities on the processed surface, and the processed surface is mirror-finished or glossed. Therefore, it is possible to provide a low-cost projection material that does not require a special apparatus for maintaining the polishing ability and has a stable and stable polishing ability even when used for a long time.

  In order to solve the above-mentioned problem, in the invention according to claim 1, the spherical particles are formed by carrying a 1-50 μm abrasive on the surface of vinyl chloride particles having a diameter of 10-3,000 μm, The technical means is used.

  According to the first aspect of the present invention, it is possible to efficiently perform mirroring or smoothing of the work surface by blasting without forming a textured unevenness on the work surface.

  The invention according to claim 2 uses the technical means that the plasticizer is contained in the vinyl chloride particles in the blasting projection material according to claim 1 in an amount of 70% by mass or less.

  By including a plasticizer in the vinyl chloride particles, the vinyl chloride particles are softened. That is, the higher the plasticizer content, the lower the hardness of the vinyl chloride particles. In order to achieve a mirror surface or a glossy surface of the work surface, it is important to use a projection material having the optimum hardness for the material and shape of the work piece. Since the vinyl chloride particles contain 70% by mass or less of a plasticizer as in the invention described in claim 2, the vinyl chloride particles having a hardness matched to the material and shape of the workpiece, and thus projected. A material can be obtained.

  According to a third aspect of the invention, in the blasting projection material according to the first or second aspect, the hardness is continuously softened from the central portion of the vinyl chloride particle toward the surface portion. Use technical means.

  According to the third aspect of the present invention, since the internal hardness is harder than the outer peripheral surface of the projection material, the collision energy when the projection material collides with the surface to be processed increases, and a high polishing force can be obtained. .

  In invention of Claim 4, in the blasting projection material in any one of Claim 1 thru | or 3, the technique that the load of the said abrasive material is 1-50 volume% of the said projection material. Use appropriate means.

  According to the invention described in claim 4, the polishing force due to the dust or the like generated during blasting entering between the abrasives (clogging) when the carrying amount of the abrasive is 1 to 50% by volume of the projection material. Can be prevented and high polishing power can be maintained for a long time.

  According to a fifth aspect of the present invention, in the method for producing a blasting projection material according to any one of the first to fourth aspects, a vinyl chloride polymer and an abrasive, and further, if necessary, a plasticizer and / or While adding a molding aid, the technical means of producing by kneading while heating at 60 to 200 ° C. is used.

  According to the invention described in claim 5, the blasting projection material can be obtained by a very simple method.

  In the invention according to claim 6, in the method for producing the blasting projection material according to claim 5, a technical means of kneading while applying pressure at 0.1 to 0.8 MPa on an atmospheric pressure basis is used.

  According to the sixth aspect of the invention, a blasting projection material with more stable quality can be obtained in a short time by kneading while pressurizing at 0.1 to 0.8 MPa on the basis of atmospheric pressure.

  According to the present invention, compared to conventional techniques such as polishing paper or polishing cloth, the surface of the workpiece can be mirror-finished or flattened without generating textured irregularities in a very short time. In addition, it is possible to obtain a blasting projection material capable of maintaining a high polishing power for a long time.

  In particular, by appropriately selecting the amount of plasticizer contained in the vinyl chloride particles, it is possible to obtain a blasting projection material that matches the material and shape of the workpiece.

  In addition, a blasting projection material can be obtained by a very simple method without the need to form a pellet or the like from raw material particles such as polyvinyl chloride particles.

  Moreover, since not only the simple manufacturing process as described above but also the amount of abrasive used can be relatively reduced, a blasting projection material can be obtained at low cost.

It is a schematic diagram of the blasting projection material in the present invention. It is a schematic diagram which shows the support state of an abrasive.

  As raw materials, polyvinyl chloride particles (hereinafter, raw material particles) and abrasives are used. Moreover, the plasticizer and formation adjuvant to add are used as needed.

  Polyvinyl chloride particles are generally obtained by suspension polymerization from chlorinated ethylene (VCM). The suspension polymerization method of polyvinyl chloride generally proceeds by forming a VCM with micelles formed by the surfactant in the solvent in which the initiator and the surfactant are dispersed, and growing the VCM in the micelles. To do. As the initiator, peroxyester-based and dicarbonate-based water-soluble initiators are used. The raw material particles in this example were also obtained by suspension polymerization, but the present invention is not limited to suspension polymerization and may be obtained by other known techniques.

  By containing the plasticizer, the hardness of the vinyl chloride particles becomes soft. The hardness of the vinyl chloride particles is determined by the amount of plasticizer added. Depending on the material and shape of the work piece, the required hardness of the projection material, and thus the vinyl chloride particles, varies and is appropriately adjusted depending on the amount of plasticizer added. In the present invention, the addition amount of the plasticizer when used for the blasting projection material when it is necessary to add a plasticizer is 70% by mass or less, more preferably 20 to 60% by mass with respect to the vinyl chloride particles. Add as follows. When the content of the vinyl chloride plasticizer exceeds 70% by mass, the vinyl chloride particles become unnecessarily soft, and even if the abrasive is supported on the surface of the vinyl chloride particles, the hardness necessary for the projection material is sufficient. It cannot be obtained, and sufficient collision energy cannot be obtained for the surface to be processed. As a result, a sufficient polishing force cannot be obtained for the surface to be processed.

  As the plasticizer, phthalic acid ester compounds and the like, and compounds thereof are generally used, but the present invention is not limited thereto, and known materials such as tritometic acid esters, fatty acid esters, adipic acid, and the like are used. be able to.

  The forming aid is a substance added as necessary to form the vinyl chloride particles and the blasting projection material of the present invention. Specifically, in this embodiment, calcium carbonate necessary for impregnating the plasticizer in the raw material particles and various stabilizers necessary for stabilizing the shape and composition of the vinyl chloride particles (Pb-based, Sn-based). And composite metal soaps). In addition, articles and amounts can be appropriately selected and used as necessary.

  At least one type of abrasive is selected from a projection material used in general blasting, an abrasive used in a general polishing method, and the like. For example, ceramics such as white alundum, glass and diamond, metals such as iron and stainless steel, inorganics such as calcium carbonate and sulfide, walnuts and peaches, etc. And other resin systems such as PET, PP, etc. (however, those having higher hardness than vinyl chloride, which is the core of the projection material in the present invention). The particle diameter of the abrasive is selected from 1 to 50 μm, more preferably from 1 to 20 μm. If the particle diameter of the abrasive is less than 1 μm, the polishing ability necessary for mirroring or smoothing the work surface cannot be obtained, and if it exceeds 50 μm, the supporting force on the surface of the vinyl chloride particles is weak. The abrasive falls off more than necessary due to the collision with the work surface.

  The diameter of the vinyl chloride particles carrying the abrasive is selected from 10 to 3,000 μm, preferably 10 to 1,000 μm, more preferably 50 to 300 μm. When the thickness is less than 10 μm, not only the abrasive can not be sufficiently supported, but also when used for blasting as being supported, sufficient polishing ability cannot be obtained for the surface to be processed. Further, in the blast processing apparatus, the projection material injected toward the workpiece by the injection means (for example, the injection nozzle in the air blast processing apparatus) can be reused by the classification apparatus (for example, the cyclone classification apparatus) The projection material which can be divided and reused is sent again to the injection means and injected. When the vinyl chloride particles having a diameter of less than 1 μm are used as the projection material, it becomes difficult to separate the projection material that can be reused by the classifier as described above. On the other hand, when the thickness exceeds 3,000 μm, a satin-like unevenness is formed on the processed surface when the projection material collides with the processed surface during blasting. Moreover, although the said vinyl chloride particle | grain depends on a manufacturing method, a thing with a particle diameter of 1,000 micrometers or less is comparatively easy to manufacture.

  A predetermined amount of the raw material is weighed and put into a kneading apparatus. The kneading apparatus was equipped with a heating means, and kneading was performed using the heating means while heating the raw material at a temperature selected from 60 to 200 ° C.

  By performing stirring while heating, the abrasive is supported on the surface of the raw material particles. When a plasticizer is not used, the raw material particles are directly used as vinyl chloride particles in the present invention. The abrasive material is supported on the surface of the raw material particles by softening the surface of the raw material particles by heating. When the heating temperature is lower than 60 ° C., the raw material particle surfaces are not sufficiently softened, and the abrasive is not sufficiently supported on the raw material particle surfaces.

  When a plasticizer is added as a raw material, the plasticizer penetrates toward the center of the raw material particles by heating and kneading to form vinyl chloride particles in the present invention. On the other hand, substances necessary for production such as abrasives and forming aids do not penetrate to the center of the particles, but are supported on the surface of the particles and the periphery thereof. That is, impregnation of the plasticizer into the raw material particles and loading of the abrasive are performed in the same process. The “state where the abrasive is supported on the particle surface” in the present invention includes not only the abrasive but also a case where a substance necessary for production is supported as described above.

  Further, since the rate and amount of the plasticizer impregnated into the raw material particles differ depending on the heating temperature, the distribution of the plasticizer in the resulting vinyl chloride particles changes. That is, in the kneading at a low temperature, the progress of impregnation with the plasticizer is slow, and as a result, the resulting vinyl chloride particles are softly obtained step by step from the center toward the surface. When the heating temperature is 160 ° C. or higher, the plasticizer is impregnated to the center of the vinyl chloride particles. However, when the temperature exceeds 160 ° C., chlorine in the side chain of vinyl chloride starts to decompose as hydrogen chloride. Therefore, when heating at a temperature exceeding 160 ° C., a stabilizer is added as necessary. If the heating temperature is further raised and exceeds 200 ° C., the main chain of vinyl chloride begins to break and the physical properties change greatly.

  The kneading is performed by pressurizing to 0.1 to 0.8 MPa, more preferably 0.1 to 0.5 MPa on an atmospheric pressure basis. By applying a pressure of 0.1 MPa or more, when the abrasive material is carried or a plasticizer is added, the impregnation of the plasticizer into the raw material particles is further promoted. The shape of the vinyl chloride particles cannot be maintained, for example, the matching vinyl chloride particles aggregate.

  Also, the amount of plasticizer impregnated in the raw material particles varies depending on the kneading time. Therefore, by appropriately adjusting the heating temperature and kneading time at the time of kneading, particles having the optimum hardness and polishing power for the material and shape of the workpiece can be obtained. When the impregnated plasticizer is uniformly dispersed in the vinyl chloride particles, the particles have a uniform hardness at any part, but when not uniformly dispersed, the hardness varies depending on the part. In other words, since the plasticizer is impregnated from the outer peripheral portion toward the central portion, if the plasticizer does not reach the central portion of the particles sufficiently, there is a difference in the plasticizer content between the central portion and the outer peripheral portion of the particles. And the content rate is higher in the outer peripheral portion. As a result, the outer peripheral portion is softer than the central portion of the particles.

  By classifying the particles thus obtained as necessary, the surface of the vinyl chloride particles 11 carries the abrasive 12 and a substance necessary for production (in this embodiment, the forming aid 13) as shown in FIG. A blasting projection material was obtained. The classification can be performed by a known method such as sieving or air classification, and the method is not particularly limited. Further, the shape of the projection material is substantially spherical. Due to the spherical shape, the supported abrasive is supported evenly on the projection material surface without deviation.

  In the obtained blasting projection material, the abrasive is supported in an amount of 1 to 50% by volume, more preferably 5 to 30% by volume, relative to the vinyl chloride particles. If it is less than 1% by volume, the amount of the abrasive exposed to the surface of the projection material is small, and a sufficient polishing force cannot be obtained on the work surface. When the volume exceeds 50% by volume, the overall hardness increases due to an increase in the amount of abrasive in the projection material, and a matte surface unevenness is formed on the surface to be processed by blasting, or scratches are formed on the surface to be processed. Arise.

  In the present invention, the state in which the abrasive is supported on the surface of the vinyl chloride particles is not only supported on the surface, but is also supported near the surface (for example, the abrasive is stacked to form a layer). It is also included. Specifically, as shown in FIG. 2, it is sufficient that the abrasive is not carried within a range where the diameter is at least less than 70% with the central portion of the projection material as the center. That is, as shown in FIG. 2, the range of 0.7 × A μm or more in diameter is about the central portion of the blasting projection material 20 having a diameter of A μm as long as the region is only the vinyl chloride 21, and the remainder is vinyl chloride and abrasive. This is the region 22 where the materials coexist.

  The projection material thus obtained was put into a pneumatic blasting apparatus. There are two types of pneumatic blast devices: a suction type (gravity type) and a pressurization type (direct pressure type). In this embodiment, the suction type will be described as an example.

The suction-type blasting apparatus includes a blasting chamber, a blasting nozzle, a compressed air supply device, a classification device, and a dust collecting device. By supplying compressed air to the blasting nozzle set in the blasting chamber with a compressed air supply device, negative pressure (suction force) is generated inside the nozzle. By injecting the projection material into this negative pressure flow, the projection material is mixed into the compressed air and becomes a mixed air current, which is ejected from the ejection port of the nozzle.

The nozzle is set at a predetermined distance from the processing surface and inclined at 45 ° with respect to the processing surface. The projecting material ejected from the nozzle outlet collides with the work surface at high speed, and the work surface is polished. At the same time, some of the abrasive particles fall off due to the collision with the surface to be processed.

The ejected projection material, the cut surface of the work surface, dust such as abrasive particles that have fallen off the projection material, and the like are transferred to a classification device (for example, a cyclone classification device). Therefore, the reusable projection material is transferred to the projection material hopper, and again injected into the nozzle. On the other hand, dust and non-reusable projection material are collected by a dust collector.

In order to process the entire surface to be processed, the projection material was sprayed for a predetermined time while moving the nozzle or the workpiece. After spraying for a predetermined time, the injection of the projection material is stopped, the workpiece is taken out from the blast processing chamber, and the workpiece is washed by air blow, water washing or the like, and the mirror surface processing or gloss surface processing is completed.

(Example of change)
In the present embodiment, polyvinyl chloride particles are used as raw material particles, but a known polymer material that can be plasticized by a polyvinyl chloride copolymer, a polyvinylidene polymer or copolymer, and a plasticizer. Can be used.

  The stirring of the raw material may be performed under atmospheric pressure. Since the carrying speed of the abrasive and the impregnation speed of the plasticizer into the raw material particles when a plasticizer is added, the physical property value of the blasting projection material can be finely adjusted.

  The blasting is not limited to the pneumatic method, and a known method such as a centrifugal method in which the projection material collides with the workpiece by the rotation of the impeller can be selected.

  The angle formed by the nozzle and the surface to be processed can be arbitrarily set within a range of 0 to 180 ° including vertical.

(material)
Polyvinyl chloride particles (ZEST 1300Z: manufactured by Shin Daiichi Vinyl Co., Ltd.) are used as raw material particles, diisononyl phthalate (Vinizer 90: manufactured by Kao Corporation) is used as a plasticizer, and calcium carbonate (NS #) is used as a forming aid. 400: manufactured by Nitto Flour Chemical Co., Ltd.) and Carborundum (GC # 4000: manufactured by Shinto Kogyo Co., Ltd.) were used as the abrasive. These were used as raw materials, and the mixing ratio was 2: 3: 2: 3.

(Kneading conditions)
For the kneading, a pressure-type kneading apparatus (original work) was used. The heating temperature of the kneading apparatus was set to 120 ° C., and the pressure during kneading and the kneading time were changed. Specifically, a sample obtained by kneading for 20 minutes under atmospheric pressure is Example 1, a sample obtained by kneading for 60 minutes under atmospheric pressure is Example 2, and 20 minutes at 0.3 MPa (atmospheric pressure standard). A sample obtained by kneading was designated as Example 3.

(Blasting)
Using the resulting blast projection material, a blasting machine (MY-30: manufactured by Shinto Kogyo Co., Ltd.) has a processed surface of φ40 mm and has a hardness of HRC62 (JISG0202) SK-3C heat-treated product. Jetted. The injection conditions were as follows: the injection pressure was 0.3 MPa, the distance between the nozzle and the surface to be processed was 100 mm, the angle between the nozzle and the surface to be processed was 45 degrees, and the processing was performed for 5 minutes.

(Evaluation)
After blasting, the surface to be processed was cleaned by air blow, water washing, etc., and then the surface roughness and glossiness were evaluated. The surface roughness was measured with a surface roughness meter (SURFCOM 1500SD: manufactured by Tokyo Seimitsu Co., Ltd.) for arithmetic average roughness Ra, maximum height Ry, and ten-point average roughness Rz (JIS B0601-1994). The glossiness was visually evaluated, and it was evaluated as “◯” when the gloss increased compared to the unprocessed product, “Δ” when equal to the unprocessed product, and “X” when the gloss was less than the unprocessed product. Moreover, the evaluation which combined surface roughness and glossiness was made into comprehensive evaluation, and when it was better than an unprocessed product, it was set as ◯, when it was equal to an unprocessed product, and when it was worse than an unprocessed product, it was set as x.

(Comparative example)
Comparative Example 1 was the same as in Example 1 except that the plasticizer was added in excess, specifically, 80% with respect to the vinyl chloride particles. In Comparative Example 2, the abrasive material was excessively supported on the vinyl chloride particles in the previous example, and specifically, 60% by volume was supported in the blasting projection material, and other conditions were the same as in Example 1. did. In Comparative Example 3, the temperature of the kneading apparatus was set to 50 ° C. in the above Example, and other conditions were the same as in Example 1. Comparative Example 4 was the same as that in Example 1 in the previous example, except that the pressure applied was 0.9 MPa. The execution conditions of Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 1.

(result)
Samples obtained by kneading the raw materials in Examples 1 to 3 and Comparative Example 2 were substantially spherical samples in which an abrasive was supported on the surface of vinyl chloride particles. In Comparative Example 1 and Comparative Example 4, the particles were not substantially spherical but irregularly shaped, and the abrasive was not evenly supported on the particle surface, resulting in a coarse and dense distribution. Although the comparative example 3 was substantially spherical, the abrasive was hardly carried on the surface.

  In addition, in Example 1 and Comparative Example 2, the form (hardness) of the particles is continuously soft from the center of the vinyl chloride particles toward the outer peripheral surface. This is probably because the plasticizer was not sufficiently impregnated to the center of the raw material particles in the kneading stage. On the other hand, in Example 2 and Example 3, the vinyl chloride particles had a uniform hardness at any part. This is considered to be because in Example 2, the stirring time was sufficient for the plasticizer to be impregnated into the raw material particles, and in Example 3, the impregnation proceeded by applying pressure.

  Table 2 shows the results of blasting using samples (Examples 1 to 3 and Comparative Example 2) in which the surface of the vinyl chloride particles is abrasive. As for the surface roughness (Ra, Ry, Rz) of the processed surface after blasting, almost the same results were obtained in Example 2 and Example 3, but Example 1 was slightly higher in all numerical values. It was. However, the surface roughness was improved compared to before blasting (surface roughness Ra, Ry, Rz of the unprocessed product was 0.20 μm, 2.05 μm, and 1.51 μm, respectively). Moreover, since glossiness was ◯ in all of Examples 1 to 3, the overall evaluation was ◯. Therefore, even particles having the form as in Example 1 can be suitably used as a blasting projection material for the purpose of making the surface glossy or smooth, and Example 2 depends on the material and shape of the workpiece. It was suggested that the present invention can be used more favorably than the forms of 3 and 3. On the other hand, in the comparative example, the surface roughness and gloss were worse than those of the unprocessed product. This is considered to be because the projection material has a high hardness due to the large amount of abrasive material carried, and the matte surface unevenness is formed on the surface to be processed during blasting.

  According to the present invention, it is possible to make a mirror surface or a smooth surface without generating a textured surface unevenness in a very short time compared to conventional techniques such as polishing with polishing paper or polishing cloth. became. For example, it can be applied to mirror the cavity surface of a mold. The cavity surface of the mold requires a highly accurate surface. In addition, seizure of the molding material occurs as it is used. Therefore, for example, the cleaning of the molding material by image sticking or the like can be performed by a known method such as conventional shot blasting or a surface polishing method, and then can be mirror-finished according to the present invention. Of course, if the adhesion of the residue on the cavity surface is not so strong and can be sufficiently removed by spraying the projection material of the present invention, cleaning and mirroring may be performed simultaneously in the present invention.

As other applications, for example, it can be applied to various mirror surface or smooth surface applications, including pretreatment of a base material when a film such as DLC is applied.

11 Vinyl chloride particles 12 Abrasive material 13 Formation aid

Claims (6)

  A projection material for blasting, characterized in that it is a substantially spherical particle formed by supporting a 1-50 μm abrasive on the surface of vinyl chloride particles having a diameter of 10-3,000 μm.   The blasting projection material according to claim 1, wherein the vinyl chloride particles contain 70% by mass or less of a plasticizer.   3. The blasting projection material according to claim 1, wherein the vinyl chloride is continuously softened from a central portion toward a surface portion. 4.   The blasting projection material according to any one of claims 1 to 3, wherein the abrasive is supported by 1 to 50% by volume with respect to the vinyl chloride particles.   5. The method for producing a blasting projection material according to claim 1, wherein polyvinyl chloride particles and an abrasive, and further, if necessary, a plasticizer and / or a molding aid are added, and 60 to 200 A method for producing a blasting projection material, which is produced by kneading while heating at 0 ° C. 6. The method for producing a blasting projection material according to claim 5, wherein the blasting projection material is kneaded while being pressurized at 0.1 to 0.8 MPa on an atmospheric pressure basis.