Patent Application
20210276229
The present invention relates to a fluororesin molded article that is an integrally molded product including a first section and a second section, a function of the first section being different from a function of the second section. The present invention also relates to a medical diaphragm for use in production of a serum or vaccine, and a diaphragm for semiconductor for use in cleaning of a semiconductor product.
Fluororesins, such as polytetrafluoroethylene (hereinafter referred to as “PTFE”), have excellent heat resistance, chemical resistance, etc., and therefore, are suitably used as a material for diaphragms, bellows, etc.
As a molding method for fluororesin molded articles, compression molding is conventionally known. For example, there is a PTFE molded article obtained by compression-molding a PTFE powder having an average particle size of 200-1000 μm (see, for example, Patent Document 1). Patent Document 1 indicates that such a PTFE molded article has a small number of voids, and therefore, can be used as a diaphragm having excellent mechanical strength and sealing properties.
Patent Document 1: International Publication WO2008/069196
Incidentally, some diaphragm product has a membrane section which is subjected to repetitive deformation in use, and in addition, a valve section which is a non-deformation part, and the like, and thus the sections have respective functions different from each other. In such a diaphragm, for example, the membrane section is required to have bending resistance, and the valve section is required to have wear resistance, and the like, i.e. the sections require respective specifications different from each other. In order to meet such required specifications, product design depending on specifications required for each section is needed, such as changing the degree of crystallinity of a resin for each section.
However, in the PTFE molded article described in Patent Document 1, it is not assumed that the degree of crystallinity is changed for each section of the diaphragm. In conventional techniques including that described in Patent Document 1, sections such as the repetitive-deformation section and the non-deformation section are formed as separate fluororesin molded articles, which are joined together after molding to produce a diaphragm including sections having respective characteristics different from each other. However, in a diaphragm produced by such a production method, the joint portion is likely to have insufficient strength. In addition, the sections require respective quality managements different from each other, disadvantageously leading to an increase in manufacturing cost.
With the above problems in mind, the present invention has been made. It is an object of the present invention to provide a fluororesin molded article in which a plurality of sections having respective characteristics different from each other are integrally formed. It is another object of the present invention to provide a medical diaphragm for use in production of a serum or vaccine, using the fluororesin molded article, and a diaphragm for semiconductor that is used to clean a semiconductor product, using the fluororesin molded article.
A characteristic feature of a fluororesin molded article according to the present invention for achieving the above object is a fluororesin molded article that is an integrally molded product including a first section and a second section, a function of the first section being different from a function of the second section, wherein the first section and the second section are a sintered body of a fluororesin powder, the fluororesin powders contained in the first and second sections having respective average particle sizes from each other.
In the fluororesin molded article having this feature, the first section and the second section are a sintered body of a fluororesin powder, an average particle size of the fluororesin powder contained in the first section being different from an average particle size of the fluororesin powder contained in the second section, and therefore, in the fluororesin molded article, the sections have respective characteristics such as the degree of crystallinity different from each other. As a result, an integrally molded product can be formed in which the qualities of the first section and the second section having respective characteristics different from each other can be simultaneously managed, and therefore, the manufacturing cost can be reduced.
In the fluororesin molded article of the present invention, the first section is preferably a non-deformation section formed of a sintered body of a fluororesin powder having an average particle size of 300 μm or more, and the second section is preferably a repetitive-deformation section formed of a sintered body of a fluororesin powder having an average particle size of 100 μm or less.
According to the fluororesin molded article having this feature, the first section is formed of a sintered body of a fluororesin powder having an average particle size of 300 μm or more, and therefore, has excellent wear resistance characteristics required for a non-deformation section, and the second section is formed of a sintered body of a fluororesin powder having an average particle size of 100 μm or less, and therefore, has excellent bending resistance characteristics required for a repetitive-deformation section that is repetitively deformed in use.
In the fluororesin molded article of the present invention, the first section is preferably a non-deformation section formed of a fluororesin having a degree of crystallinity of 50-70%, and the second section is preferably a repetitive-deformation section formed of a fluororesin having a degree of crystallinity of not less than 30% and less than 50%.
According to the fluororesin molded article having this feature, the first section is formed of a fluororesin having a degree of crystallinity of 50-70%, and therefore, has excellent wear resistance characteristics required for a non-deformation section, and the second section is formed of a fluororesin having degree of crystallinity of not less than 30% and less than 50%, and therefore, has excellent bending resistance characteristics required for a repetitive-deformation section that is repetitively deformed in use.
In the fluororesin molded article of the present invention, the fluororesin is preferably polytetrafluoroethylene.
According to the fluororesin molded article having this feature, the fluororesin is polytetrafluoroethylene, and therefore, the fluororesin molded article has excellent heat resistance and chemical resistance.
In the fluororesin molded article of the present invention, the repetitive-deformation section is preferably formed as a membrane section of a diaphragm, the membrane section having a curved cross-sectional shape, the non-deformation section is preferably formed as a column-shaped linking section extending from the membrane section on a convex surface of the curved shape, and a valve section integrally provided at an end of the linking section and having a shape wider than the linking section in a direction perpendicular to an extension direction of the linking section, and a metal member having a first and a second end portion, the first end portion being wider than the second end portion, is preferably embedded by insert molding with the first end portion disposed inside the valve section, and the second end portion exposed from the membrane section on a concave surface of the curved shape.
According to the fluororesin molded article having this feature, the repetitive-deformation section is formed as a membrane section of a diaphragm, the membrane section having a curved cross-sectional shape, the non-deformation section is formed as a column-shaped linking section extending from the membrane section on a convex surface of the curved shape, and a valve section integrally provided at an end of the linking section and having a shape wider than the linking section, and a metal member having a first and a second end portion, the first end portion being wider than the second end portion, is embedded by insert molding with the wider end portion disposed inside the valve section, and the second end portion exposed from the membrane section on a concave surface of the curved shape. Therefore, even when the metal member is pulled toward the concave surface of the membrane section, the metal member can be reliably prevented from dropping from the fluororesin molded article. Therefore, a fluororesin molded article can be formed that has excellent durability when the diaphragm is repetitively driven with the metal member attached to a drive device.
A characteristic feature of a medical diaphragm according to the present invention for achieving the above object is a medical diaphragm for use in production of a serum or vaccine, the medical diaphragm including the fluororesin molded article of any one of the above features.
In conventional techniques, in a diaphragm obtained by forming a plurality of parts as separate fluororesin molded articles, and joining the parts together after molding, the joint portion is likely to be contaminated. If such a diaphragm is used in production of a serum or vaccine, the resultant serum or vaccine is likely to be mixed with bacteria, etc. The medical diaphragm having this feature is an integrally molded product including a first section and a second section, a function of the first section being different from a function of the second section, and therefore, a serum or vaccine is unlikely to be mixed with bacteria, etc., due to the joint portion contamination. In addition, in the medical diaphragm having this feature, the fluororesin provides an inactive interface, and therefore, mixing with bacteria, etc., from the surface of the medical diaphragm is inhibited, and therefore, a highly-safe serum or vaccine can be produced.
A characteristic feature of a medical diaphragm according to the present invention for achieving the above object is a medical diaphragm for use in production of a serum or vaccine, the medical diaphragm including the fluororesin molded article of any one of the above features, wherein the non-deformation section is formed as a valve section of the diaphragm, and the repetitive-deformation section is formed as a membrane section of the diaphragm.
According to the medical diaphragm having this feature, the medical diaphragm is an integrally molded product including a membrane section and a valve section having respective characteristics different from each other, and therefore, a serum or vaccine is unlikely to be mixed with bacteria, etc., due to the joint portion contamination. In addition, in the medical diaphragm having this feature, the fluororesin provides an inactive interface, and therefore, mixing with bacteria, etc., from the surface of the medical diaphragm is inhibited, and therefore, a highly-safe serum or vaccine can be produced.
A characteristic feature of a diaphragm for semiconductor according to the present invention for achieving the above object is a diaphragm for semiconductor for use in cleaning of a semiconductor product, the diaphragm including the fluororesin molded article of any one of the above features.
In conventional techniques, in a diaphragm obtained by forming a plurality of parts as separate fluororesin molded articles, and joining the parts together after molding, the joint portion is likely to be contaminated. If such a diaphragm is used in cleaning of a semiconductor product, the resultant semiconductor product is likely to be mixed with impurities, contamination, etc. The diaphragm for semiconductor having this feature is an integrally molded product including a first section and a second section, a function of the first section being different from a function of the second section, and therefore, a semiconductor product is unlikely to be mixed with impurities, contamination, etc., due to the joint portion contamination. In addition, in the diaphragm for semiconductor having this feature, the fluororesin provides an inactive interface, and therefore, mixing with impurities, contamination, etc., from the surface of the diaphragm for semiconductor is inhibited, and therefore, a semiconductor product can be highly cleaned.
A characteristic feature of a diaphragm for semiconductor according to the present invention for achieving the above object is a diaphragm for semiconductor for use in cleaning of a semiconductor product, the diaphragm including the fluororesin molded article of any one of the above features, wherein the non-deformation section is formed as a valve section of the diaphragm, and the repetitive-deformation section is formed as a membrane section of the diaphragm.
According to the diaphragm for semiconductor having this feature, the diaphragm for semiconductor is an integrally molded product including a membrane section and a valve section having respective characteristics different from each other, and therefore, a semiconductor product is unlikely to be mixed with impurities, contamination, etc., due to the joint portion contamination. In addition, in the diaphragm for semiconductor having this feature, the fluororesin provides an inactive interface, and therefore, mixing with impurities, contamination, etc., from the surface of the diaphragm for semiconductor is inhibited, and therefore, a semiconductor product can be highly cleaned.
A fluororesin molded article according to the present invention will now be described. Note that the present invention is not intended to be limited to embodiments and drawings described below.
The valve section 51a and the linking section 51b are preferably a sintered body of a fluororesin powder having an average particle size of 300 μm or more. The valve section 51a and the linking section 51b preferably have a degree of crystallinity of 50-70%. In the case where the valve section 51a and the linking section 51b are a sintered body of a fluororesin powder having an average particle size of 300 μm or more, and have a degree of crystallinity of 50-70, the valve section 51a and the linking section 51b have wear resistance characteristics suitable for a non-deformation section. In
The membrane section 52 is preferably a sintered body of a fluororesin powder having an average particle size of 100 μm or less. The membrane section 52 preferably has a degree of crystallinity of not less than 30% and less than 50%. In the case where the membrane section 52 is a sintered body of a fluororesin powder having an average particle size of 100 μm or less, and has a degree of crystallinity of not less than 30% and less than 50%, the membrane section 52 has bending resistance suitable for a repetitive-deformation section. In
Examples of the fluororesin powder that is a starting material for the diaphragm 50 include powders of polytetrafluoroethylene (hereinafter referred to as “PTFE”), tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkylvinyl ether copolymer, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, ethylene-tetrafluoroethylene copolymer, and ethylene-chlorotrifluoroethylene copolymer. A powder of PTFE is particularly preferable.
The diaphragm 50 can be suitably used as a medical diaphragm for use in production of a serum or vaccine. In such a medical diaphragm, sections thereof such as a membrane section and a valve section need to have respective characteristics different from each other, depending on the functions thereof. However, in conventional techniques, a membrane section, a valve section, etc., that have respective characteristics different from each other are formed as separate fluororesin molded articles, which are joined together after molding to produce a diaphragm, and therefore, the joint portion is likely to be contaminated during production. If such a diaphragm is used in production of a serum or vaccine, the resultant serum or vaccine is likely to be mixed with bacteria, etc., from the contaminated joint portion. In contrast to this, in the diaphragm 50 of the present invention, the valve section 51a having excellent wear resistance and the membrane section 52 having excellent bending resistance are formed as an integrally molded product, and therefore, is unlikely to be mixed with bacteria, etc., due to the joint portion contamination that is a problem with conventional techniques. In addition, the fluororesin molded article has an inactive interface, and therefore, by use of the diaphragm 50, mixing with bacteria, etc., from the surface of the medical diaphragm can be inhibited. As a result, a highly-safe serum or vaccine can be produced.
The diaphragm 50 can also be suitably used as a diaphragm for semiconductor for use in production of a semiconductor product. In the diaphragm 50 of the present invention, the valve section 51a having excellent wear resistance and the membrane section 52 having excellent bending resistance are formed as an integrally molded product, and therefore, is unlikely to be mixed with impurities, contamination, etc., due to the joint portion contamination that is a problem with conventional techniques. In addition, the fluororesin molded article has an inactive interface, and therefore, by use of the diaphragm 50, mixing with impurities, contamination, etc., from the surface of the diaphragm for semiconductor can be inhibited. As a result, a semiconductor product can be highly cleaned.
Next, a molding method for obtaining the fluororesin molded article of the present invention will be described. The fluororesin molded article of the present invention is obtained by performing the following steps A-D using at least two kinds of fluororesin powders which have respective average particle sizes different from each other, as a starting material. Specifically, the molding method for obtaining the fluororesin molded article of the present invention includes step A of preparing a layered product by layering at least two kinds of fluororesin powders having respective average particle sizes different from each other, step B of loading the layered product into a primary mold, and pressing the layered product to form a preliminary molded article, step C of sintering the preliminary molded article to obtain a sintered article, and step D of loading the sintered article into a secondary mold, and cooling the sintered article while pressing the sintered article.
In step A, a fluororesin powder having an average particle size of 300 μm or more is deposited in the lower mold of the primary mold 100 including the molds 101, 102, and 103, to form a first layer 10a. A fluororesin powder having an average particle size of 100 μm or less is deposited on the first layer 10a to form a second layer 10b. Thus, the layered product 10 including a stack of the first layer 10a and the second layer 10b is formed. The wear resistance of a fluororesin molded article increases with an increase in the average particle size of a fluororesin powder as the starting material. The bending resistance of a fluororesin molded article increases with a decrease in the average particle size of a fluororesin powder as the starting material. Therefore, in the layered product 10, a layer that is to serve as a non-deformation section which is brought into contact with another member without being deformed in use after molding, such as the valve section of a diaphragm, is preferably formed of a fluororesin powder having a greater average particle size, and a layer that is to serve as a repetitive-deformation section which is repetitively deformed in use after molding, such as the membrane section of a diaphragm, is preferably formed of a fluororesin powder having a smaller average particle size. For example, two kinds of fluororesin powders are successively deposited in the lower mold while the powders are sieved over the lower mold of the primary mold 100. As a result, as shown in
In step B, a metal member 20 that is an insert for the diaphragm of
In step C, the preliminary molded article 30 is removed from the primary mold 100, and is sintered in a heating furnace at a temperature that is higher than or equal to the melting point of the fluororesin powder. In the case where a powder of PTFE (melting point: 327° C.) is used as the fluororesin powder, the sintering temperature is preferably set to 360-380° C. When the fluororesin powder is sintered, the internal stress of the preliminary molded article 30 is removed, so that fluororesin powder particles are fused together to form a sintered article.
In step D, the sintered article 40 is set in the mold 204 as the upper mold with the jig 20A attached to the metal member 20 of
The volume of the cavity 205 formed in the secondary mold 200 is preferably set to be 0.80-0.95 times as great as the volume of the cavity 105 formed in the primary mold 100. The preliminary molded article 30, which is the prototype of the diaphragm 50, is formed by pressing using the primary mold 100, and thereafter, is pressed using the secondary mold 200, whose cavity has a slightly smaller volume than that of the cavity of the primary mold 100, whereby the diaphragm 50 can be precisely formed only by compression molding. Therefore, it is not necessary to perform cutting or the like using a milling machine or the like after molding, and therefore, the yield can be improved.
The degree of crystallinity of the fluororesin can be controlled based on the cooling rate in step D. In addition, the degree of crystallinity of the fluororesin correlates with the friction coefficient of the fluororesin, i.e. as the degree of crystallinity decreases, the friction coefficient increases. For example, by increasing the cooling rate in step D, the degree of crystallinity of the fluororesin is reduced, so that the friction coefficient of the surface of the diaphragm 50 can be increased. Conversely, by reducing the cooling rate in step D, the degree of crystallinity of the fluororesin is increased, so that the friction coefficient of the surface of the diaphragm 50 can be reduced.
Thus, in the diaphragm 50 formed using the molding method described above, the valve section 51a and the linking section 51b, which are a sintered body of the fluororesin powder having an average particle size of 300 μm or more derived from in the first layer 10a of the layered product 10, and the membrane section 52, which is a sintered body of the fluororesin powder having an average particle size of 100 μm or less derived from the second layer 10b of the layered product 10, are integrally formed.
Next, the fluororesin molded article of the present invention will further be described on the basis of a specific example.
In step A, in the iron primary mold 100 of
The degree of crystallinity of the diaphragm 50 of the example was measured using wide-angle X-ray diffractometry at the valve section 51a, the linking section 51b, and the membrane section 52. The valve section 51a and the linking section 51b had a degree of crystallinity of 30%, i.e. high wear resistance. Such characteristics at the valve section 51a and the linking section 51b met specifications required for the non-deformation section. In addition, the membrane section 52 had a degree of crystallinity of 70%, i.e. excellent bending resistance. Such characteristics at the membrane section 52 met specifications required for the repetitive-deformation section.
The fluororesin molded article of the present invention is preferably applicable, particularly, as a diaphragm for medical use or semiconductor, and is also applicable as diaphragms for other applications, such as industry, agriculture, research, food, and semiconductor.
50 DIAPHRAGM (FLUORORESIN MOLDED ARTICLE)
51
a VALVE SECTION (FIRST SECTON)
51
b LINKING SECTION (FIRST SECTION)
52 MEMBRANE SECTION (SECOND SECTION)
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-136882 | Jul 2018 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/014516 | 4/1/2019 | WO | 00 |
