Molded polychlorotrifluoroethylene object and production method therefor

Abstract

Provided is a molded object including polychlorotrifluoroethylene, wherein the polychlorotrifluoroethylene has a melting point of 211-216°C. The molded object has a projected area of 1,000 mm2 or greater. The molded object has a thickness of 25-50 mm. The molded object has a crystallinity of 65% or less.

Description

Polychlorotrifluoroethylene molded body and its manufacturing method

[0001] The present disclosure relates to a polychlorotrifluoroethylene molded article and a method for producing the same.

[0002] Patent Document 1 describes a thermoplastic copolymer consisting essentially of trifluorochloroethylene containing 0.5 to 6 mole percent of vinylidene fluoride.

[0003] U.S. Pat. No. 2,738,343

[0004] An object of the present disclosure is to provide a molded article that is less likely to crack even when tightened with a strong force. Another object of the present disclosure is to provide a method for manufacturing a molded article that is less likely to crack even when tightened with a strong force.

[0005] According to the present disclosure, there is provided a molded article containing polychlorotrifluoroethylene, wherein the melting point of the polychlorotrifluoroethylene is 211 to 216°C, and the projected area of ​​the molded article is 1000 mm ２ The present invention provides a molded article having the above structure, a thickness of 25 to 50 mm, and a crystallinity of 65% or less.

[0006] According to the present disclosure, it is possible to provide a molded body that is less likely to crack even when tightened with a strong force. Also, according to the present disclosure, it is possible to provide a method for manufacturing a molded body that can produce a molded body that is less likely to crack even when tightened with a strong force.

[0007] Figure 1 is a graph plotting heater temperatures and heating times in the manufacturing methods of molded bodies of Experimental Examples 1 to 6 and Comparative Examples 1 to 3. Figure 2 is a schematic diagram for explaining a method for conducting a crack resistance test. Figure 2(a) is a schematic front view of a sample sheet sandwiched between a bolt, a washer, and a nut. Figure 2(b) is a schematic top view of the sample sheet sandwiched between a bolt, a washer, and a nut.

[0008] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0009] Patent Document 1 describes that polychlorotrifluoroethylene containing 0.5 to 6 mole percent vinylidene fluoride exhibits the chemical and physical properties of a chlorotrifluoroethylene homopolymer, while the final film has high gloss, is smooth, and is less likely to become embrittlement.

[0010] Chlorotrifluoroethylene (CTFE) homopolymers have the advantage of being moldable with high dimensional accuracy compared to CTFE copolymers such as those described in Patent Document 1. However, it has been found that when molded into a thick molded article having a large projected area, the resulting molded article may crack under a large fastening force.

[0011] After intensively researching the means to solve the above-mentioned problems, it has now been found that by selecting the polychlorotrifluoroethylene (PCTFE) with specific melting point and adjusting the crystallinity of molding to a specific range, even when PCTFE contains the homopolymer of CTFE, it is possible to obtain the thick molding with large projected area, or the molding that is cut from this molding to be processed into a thin part, even when it is fastened with strong force, it is difficult to generate cracks.

[0012] That is, the molded article of the present disclosure is a molded article containing PCTFE, the melting point of PCTFE is 211 to 216°C, and the projected area of ​​the molded article is 1000 mm ２ The thickness of the molded body is 25 to 50 mm, and the crystallinity of the molded body is 65% or less.

[0013] Next, the molded article of the present disclosure will be described in detail.

[0014] (Molded Article) The molded article of the present disclosure is a thick-walled molded article having a large projected area.

[0015] The projected area of ​​the molded body is 1000 mm ２ or more, preferably 5000 mm ２ More preferably, 10,000 mm ２ More preferably, it is 50,000 mm ２ More preferably, it is 100,000 mm ２The upper limit of the projection area is, for example, 300,000 mm ２ If the projected area of ​​the molded body is too small, cracks are less likely to occur in the molded body, but it becomes difficult to use the molded body for some applications, such as a turntable for a semiconductor cleaning device on which a large wafer is placed.

[0016] In the molded body of the present disclosure, the projected area is the projected area of ​​the molded body as viewed in the thickness direction of the molded body.

[0017] The thickness of the molded body is 25 to 50 mm, preferably 47 mm or less, and more preferably 44 mm or less. If the molded body is too thick, it becomes difficult to reduce the crystallinity of the molded body, and as a result, cracks are more likely to occur in the molded body. If the molded body is too thin, cracks are less likely to occur in the molded body, but it becomes difficult to use it for some applications, such as turntables in semiconductor cleaning devices for placing large wafers.

[0018] The crystallinity of the molded article is 65% or less, preferably 40% or more, and more preferably 52% or more.

[0019] The molded article of the present disclosure is the PCTFE molded article with relatively large projected area, so it is usually formed by compression molding.If the thick PCTFE molded article with such large projected area is manufactured by compression molding under conventional conditions, when the molded article obtained is clamped with strong force, cracks will occur.Surprisingly, it has been found that the molded article whose crystallinity is adjusted within the above range is less likely to crack even when clamped with strong force.

[0020] The crystallinity of the molded article can be calculated from the specific gravity of the molded article measured by the underwater displacement method using the following formula: Crystallinity (%)={(specific gravity−2.072) / (2.183−2.072)}×100

[0021] The molded article of the present disclosure contains PCTFE. The PCTFE may be a homopolymer of chlorotrifluoroethylene or a copolymer of CTFE and a monomer copolymerizable with CTFE.

[0022] Examples of monomers copolymerizable with CTFE include ethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, fluoro(alkyl vinyl ether), (perfluorobutyl)ethylene, (perfluorohexyl)ethylene, perfluoro(1,1,2-trihydro-1-hexene), and perfluoro(1,1,5-trihydro-1-pentene).

[0023] The content of CTFE units in PCTFE is preferably 90 to 100 mol%, more preferably 98 to 100 mol%, still more preferably 99 to 100 mol%, and particularly preferably 99.9 to 100 mol%. The higher the content of CTFE units in PCTFE, the more improved the properties of the molded article, such as mechanical properties, dimensional stability, chemical resistance, low chemical permeability, and low gas permeability.

[0024] The monomer composition of PCTFE is １９ It can be measured by F-NMR.

[0025] In one embodiment, the PCTFE is a CTFE homopolymer. The CTFE homopolymer is a polymer containing substantially only CTFE units, preferably a polymer containing 99.9 to 100 mol% CTFE units, and more preferably a polymer consisting of only CTFE units. The molded article of the present disclosure is less susceptible to cracking, even when it contains a CTFE homopolymer as PCTFE.

[0026] The melting point of PCTFE is 211 to 216° C. The melting point of PCTFE can be adjusted by adjusting the monomer composition of PCTFE. PCTFE homopolymers usually have a melting point within the above range.

[0027] The melting point of PCTFE can be measured using a differential scanning calorimeter (DSC).

[0028] The flow value of PCTFE measured at 230°C is preferably 2.0 x 10 －３ ml / sec or less, preferably 1.0 × 10 －４ ml / sec or more, and more preferably 1.0 × 10－３ ml / sec or more.

[0029] The flow value described above is the flow value of the PCTFE that forms the molded body.Therefore, the flow value described above may be different from the flow value of the PCTFE that is used as the raw material for producing the molded body that contains the PCTFE having the above size.

[0030] The flow value of PCTFE can be measured using a Koga type flow tester under the conditions of 230°C, a load of 980 N (100 kg), and a nozzle diameter of 1 mm. The flow value of PCTFE is the volume of PCTFE extruded from the nozzle per second.

[0031] The molded article of the present disclosure may be obtained by processing a compression molded article obtained by compression molding into a desired shape using a known method such as cutting.

[0032] The molded article of the present disclosure has excellent chemical resistance and mechanical properties, and is less likely to crack even when tightened with a strong force. Therefore, the molded article of the present disclosure can be suitably used as a component of a semiconductor manufacturing apparatus, particularly as a component fixed to the apparatus using threaded fasteners such as PCTFE bolts and nuts. The molded article of the present disclosure can be suitably used, for example, as a turntable for processing silicon wafers, peripheral components such as wafer guides, silicon wafer cleaning guides, chemical piping couplers, valves, joints; valve seats such as low-temperature valve seats for LNG transport ships; and the like. Examples of turntables include turntables for semiconductor cleaning apparatus.

[0033] The molded article of the present disclosure can be suitably produced by the production method of the present disclosure. Next, the production method of the present disclosure will be described in detail.

[0034] (Method of manufacturing a molded body) In the manufacturing method of the present disclosure, a molded body having a projected area of ​​1000 mm ２ A molded article having a thickness of 25 to 50 mm is produced. When a thick PCTFE molded article having such a large projected area is produced by compression molding under conventional conditions, there is a problem that cracks occur when the resulting molded article is clamped with a strong force.

[0035] In the manufacturing method of the present disclosure, a mold for obtaining a molded body having the above-mentioned size is heated with a heater, PCTFE is filled into the mold, and the PCTFE in the mold is compression-molded to obtain a molded body. In this process, by setting the heater temperature to 290 to 325°C and adjusting the heating time and heater temperature so as to satisfy the relational formula (X), an increase in the crystallinity of the obtained molded body is suppressed, and as a result, the occurrence of cracks can be suppressed. The steps of heating the mold with a heater and filling the mold with PCTFE can be performed in any order. That is, in the manufacturing method of the present disclosure, the mold may be heated with a heater and then PCTFE may be filled into the heated mold, or the mold filled with PCTFE may be filled with PCTFE and then heated with a heater.

[0036] The heater temperature is 290 to 325°C, preferably 292°C or higher, more preferably 294°C or higher, and preferably 323°C or lower, more preferably 321°C or lower. The heater temperature is the set temperature of a heater (preferably an electric heating wire) disposed inside or outside the mold. In one embodiment, the mold is heated using a hot air circulation oven whose heater temperature is set within the above range.

[0037] In the manufacturing method of the present disclosure, the heating time and the heater temperature are adjusted so as to satisfy the following relational expression (X): (heating time by heater (minutes)) < [1176 - 3.31 × (heater temperature (°C))]

[0038] In the manufacturing method of the present disclosure, it is preferable to adjust the heating time and heater temperature by the heater so as to satisfy the following relational expression (X): (heating time by heater (minutes)) < [1160 - 3.31 × (heater temperature (°C))]

[0039] The "heating time by heater" in the relational formula (X) specifically refers to the time from placing a compression molding die filled with PCTFE raw material into an oven that can be heated to a predetermined temperature by a heater, to heating for a predetermined time, to removing the die from the oven.When a hot plate press with a heater is used instead of an oven, it refers to the time from heating for a predetermined time by the hot plate press to moving to a press for cooling.

[0040] Compression molding of PCTFE can be performed by setting the heater temperature of an oven, such as a hot air circulation oven, to a predetermined temperature within the range of 290 to 325°C, placing a mold filled with PCTFE raw material in the oven, and heating it to melt the PCTFE raw material. After heating for a predetermined period of time, the mold is removed from the oven, and the PCTFE is cooled in the mold while being compressed using a separately prepared compression press. Cooling can be performed by air or water, but cooling under pressure is preferred because it can remove air bubbles, prevent the formation of air bubbles, and prevent deformation and cracking of the molded product. It is also possible to preheat the mold before adding the raw material, but from the perspective of preventing raw material contamination and operational safety, it is preferable to fill the raw material into a room-temperature mold in a clean environment.

[0041] In addition, instead of a hot air circulation oven, a hot plate press equipped with a heater can be used to heat and melt PCTFE, and after the PCTFE is heated and melted, the mold can be moved to a cooling press and cooled under pressure, but if the mold is large, it is more preferable to heat and melt in a hot air circulation oven, because it can be completely melted in a short time, and thermal deterioration such as an increase in flow value can be avoided.In addition, if a lot of flash occurs in the mold and the thickness of the molded body becomes thin, it can be adjusted by filling the raw material by several percent to 10% more than the calculated filling amount.

[0042] The heating time by the heater is, for example, 30 to 240 minutes, and preferably 40 minutes or more and 230 minutes or less.

[0043] The pressure applied to the PCTFE in the mold is, for example, 3 to 50 MPa. The pressure applied to the PCTFE in the mold may be gradually increased.

[0044] In one embodiment of the manufacturing method of the present disclosure, compression molding is carried out so that the rate of change in the flow value of PCTFE calculated by the following formula is 3.0 or less. Rate of change in flow value = (F １ -F ０ ) / F ０ F ０ F: Flow value of PCTFE before filling the mold (raw material flow value) １ : Flow value of PCTFE forming the molded body (molded body flow value)

[0045] The flow value of PCTFE before it is filled into a mold and the flow value of PCTFE that forms a molded article can both be measured by the method described above.

[0046] By carrying out compression molding while suppressing the increase in the rate of change of the flow value of PCTFE, the mechanical properties of the molded body can be easily adjusted within the above range, and as a result, the occurrence of cracks can be suppressed.The rate of change of the flow value of PCTFE can be suppressed low by appropriately adjusting the size of the molded body, the heating time by heater and the temperature of heater.

[0047] The flow value (raw material flow value) of PCTFE measured at 230°C before filling into the mold is preferably 1.0 x 10 －４ ml / sec or more, and more preferably 4.0 × 10 －４ ml / sec or more, preferably 1.0 × 10 －３ ml / sec or less, and more preferably 8.0 × 10 －４ ml / sec or less.

[0048] The form of the PCTFE filled into the mold is not particularly limited, and may be in the form of powder, granules, tablets, or pellets.

[0049] In the manufacturing method of the present disclosure, a molded body can be obtained by cooling the PCTFE together with the mold while compression molding the PCTFE, and then removing the molded PCTFE from the mold. By cooling the PCTFE together with the mold, the PCTFE in the mold is cooled and solidified, resulting in a molded body. Examples of cooling methods include known methods such as natural cooling in air at room temperature (air cooling), forced cooling with cold air (air cooling), and forced cooling with water (water cooling). As a cooling method, air cooling is preferred, and cooling with cold air is more preferred, because even thick molded bodies with large projected areas can be cooled while being compressed in a compression press and the occurrence of cracks can be suppressed. Water cooling is preferred from the viewpoint of easily reducing the crystallinity, but in the case of large molded bodies, caution is required because if the cooling timing is too early, the molded body may crack due to distortion caused by shrinkage stress due to solidification. To avoid the occurrence of cracks, for example, a method can be used in which the molded body is air-cooled to a temperature slightly below the melting point of PCTFE, and then rapidly cooled to 150°C or less by water cooling. Since PCTFE crystallizes rapidly in the temperature range of 160 to 190°C, crystallization can be further suppressed by quickly cooling within this temperature range. If water cooling is started when the temperature of the molded body reaches 190 to 200°C by air cooling, the degree of crystallization can be further suppressed, but it is preferable to select the timing to start water cooling taking into account the temperature distribution of the molded body.

[0050] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0051] <1> According to a first aspect of the present disclosure, there is provided a molded article containing polychlorotrifluoroethylene, wherein the melting point of the polychlorotrifluoroethylene is 211 to 216°C, and the projected area of ​​the molded article is 1000 mm ２or more, a thickness of the molded article is 25 to 50 mm, and a crystallinity of the molded article is 65% or less. <2> According to a second aspect of the present disclosure, there is provided the molded article according to the first aspect, in which the polychlorotrifluoroethylene is a homopolymer of chlorotrifluoroethylene. <3> According to a third aspect of the present disclosure, there is provided the molded article according to the first aspect, in which the flow value of the polychlorotrifluoroethylene measured at 230°C is 2.0 x 10 －３ <4> According to a fourth aspect of the present disclosure, there is provided a molded article according to any one of the first to third aspects, which is a turntable for a semiconductor cleaning device. <5> According to a fifth aspect of the present disclosure, there is provided a molded article having a projected area of ​​10,000 to 300,000 mm ２ the thickness of the molded body is 25 to 44 mm, the crystallinity of the molded body is 52 to 65%, and the flow value of the polychlorotrifluoroethylene measured at 230°C is 1.0 x 10 －３ ~2.0 x 10 －３ ml / sec. <6> According to a sixth aspect of the present disclosure, there is provided a method for producing a molded article according to any one of the first to fifth aspects, which comprises heating a mold with a heater, filling the mold with the polychlorotrifluoroethylene, and compression-molding the polychlorotrifluoroethylene in the mold to obtain the molded article, wherein the heater temperature is set to 290 to 325°C, and the heating time by the heater and the heater temperature are adjusted so as to satisfy the following relational formula (X): Formula (X): (heating time by heater (minutes))<[1176 - 3.31 × (heater temperature (°C))] <7> According to a seventh aspect of the present disclosure, there is provided a method according to the sixth aspect, in which the rate of change in flow value calculated by the following formula is 3.0 or less: Rate of change in flow value = (F １ -F ０ ) / F ０ F ０ F: Flow value of the polychlorotrifluoroethylene before filling the mold １: Flow value of the polychlorotrifluoroethylene forming the molded body

[0052] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0053] The values ​​of the experimental examples were measured by the following methods, and the experimental examples were evaluated by the following methods.

[0054] (Flow Value) Using a Koga type flow tester CFT-500D (manufactured by Shimadzu Corporation), the flow value (raw material flow value (F ０ )) and the flow value of the PCTFE forming the molded body (molded body flow value (F １ )) was requested.

[0055] (Rate of change in flow value) The raw material flow value (F ０ ) and molded body flow value (F １ ) was used to calculate the rate of change in flow value by the following formula: Rate of change in flow value = (F １ -F ０ ) / F ０

[0056] (Melting Point) The melting point was determined as the temperature corresponding to the maximum value on the heat of fusion curve when the temperature was raised at a rate of 10° C. / min using a differential scanning calorimeter (trade name: X-DSC7000, manufactured by Hitachi High-Tech Science Corporation).

[0057] (Crack Resistance Test) A 50 mm square plate was cut from a PCTFE molded body and scraped to a thickness of 1 mmt, after which a hole of 12 mmφ was made in the center to prepare a sample sheet 1.

[0058] As shown in Figure 2, a metal hex bolt 2 of size M10 (JIS B1175 (1988), outer diameter 10 mm) and metal flat washers (diameter 20 mm, hole diameter 12 mm, thickness 1 mm) 3a and 3b, and a metal hex nut 4 of size M10 were fixed in the holes of the sample sheet 1. The bolt 2 and nut 4 were tightened with a torque wrench to a maximum torque of 3.7 (N m). The sample sheet sandwiched between the bolt, washer, and nut was left in place for 24 hours, after which the bolt, washer, and nut were removed from the sample sheet. The surface of the sample sheet tightened by the washer was observed with a magnifying glass and evaluated according to the following criteria: N: No cracks were observed Y: Cracks were observed

[0059] The torsional breaking torque of commonly available PCTFE bolts is 3.7 (N m). Therefore, a PCTFE molded article that shows no cracks in the above crack resistance test means that no cracks will occur even if it is tightly fastened with a PCTFE bolt.

[0060] (Specific gravity) Measured by the underwater displacement method.

[0061] (Degree of Crystallinity) Using the specific gravity determined by the above method, the degree of crystallinity was calculated according to the following formula: Degree of crystallinity (%) = {(specific gravity - 2.072) / (2.183 - 2.072)} x 100

[0062] PCTFE having the following physical properties was used: PCTFE (1): Composition: 100 mol% CTFE Raw material flow value (F ０ ): 7.0 x 10 －４ ml / sec Melting point: 212°C PCTFE (2): Composition: CTFE 100 mol% Raw material flow value (F ０ ): 5.0 x 10 －４ ml / sec Melting point: 214°C

[0063] Experimental Example 1 A mold was prepared, which consisted of a cylindrical part with an inner diameter of 120 mm, an outer diameter of 160 mm, and a height of 60 mm, as well as bottom and top plates with an outer diameter of 118 mm and a thickness of 15 mm, made of carbon steel with hard chrome-plated resin contact surfaces.

[0064] As a raw material, 606 g of PCTFE (1) was weighed and filled into a mold.

[0065] The temperature of the hot air circulation oven was raised to 320°C, and then the mold filled with the raw materials was placed in the oven. After heating for 40 minutes, the mold was removed, and the hydraulic gauge pressure was gradually increased to 3-20 MPa using a compression press to remove air bubbles. The pressure was increased to 20-50 MPa, and the mixture was air-cooled while maintaining the pressure to prevent the generation of vacuum bubbles during solidification. After cooling, the pressure was released, and the mold was removed from the compression press. A compact was extracted from the mold using a simple hand press. The projected area of ​​the obtained compact was 11,304 mm ２ The molded body was visually inspected for cracks, but no cracks were found.

[0066] Next, a part of the molded product was cut and the flow value was measured. －３ The flow rate was 1.4 ml / sec, and the rate of change from the raw material flow value was 1.4 ml / sec. The specific gravity of the molded body was 2.143 ml / sec, and the crystallinity was calculated to be 64%.

[0067] Experimental Examples 2 to 6 and Comparative Examples 1 to 3 Molded bodies were produced in the same manner as in Experimental Example 1, except that the type of PCTFE, the shape of the molded body and the molding conditions were changed as shown in Table 1.

[0068] The results are shown in Table 1. Figure 1 is a graph plotting heater temperatures and heating times in the manufacturing methods of molded articles in Experimental Examples 1 to 6 and Comparative Examples 1 to 3. In Figure 1, the dashed line represents the formula: (heating time by heater (minutes)) = [1176 - 3.31 x (heater temperature (°C))].

[0069]

Claims

1. A molded article containing polychlorotrifluoroethylene, The melting point of the aforementioned polychlorotrifluoroethylene is 211 to 216°C. The projected area of ​​the molded body is 1000 mm². ２ The above is true, and the thickness of the molded body is 25 to 50 mm. The degree of crystallinity of the molded article is 65% or less. Molded body.

2. The molded article according to claim 1, wherein the polychlorotrifluoroethylene is a homopolymer of chlorotrifluoroethylene.

3. The flow value of the aforementioned polychlorotrifluoroethylene measured at 230°C is 2.0 × 10⁻⁶. －３ The molded article according to claim 1 or 2, wherein the concentration is less than or equal to ml / sec.

4. The molded body according to claim 1 or 2, which is a turntable for a semiconductor cleaning apparatus.

5. The projected area of ​​the molded body is 10,000 to 300,000 mm². ２ The molded body has a thickness of 25 to 44 mm, a crystallinity of 52 to 65%, and a flow value of the polychlorotrifluoroethylene measured at 230°C is 1.0 × 10⁻⁶. －３ ~2.0 x 10 －３ A molded article according to claim 1 or 2, wherein the concentration is ml / sec.

6. A method for producing a molded article according to claim 1 or 2, comprising heating a mold with a heater, filling the mold with polychlorotrifluoroethylene, and compressing the polychlorotrifluoroethylene in the mold to obtain the molded article, The temperature of the heater is set to 290 to 325°C. The heating time by the heater and the temperature of the heater are adjusted to satisfy the following relationship (X). Manufacturing method. Equation (X): (Heating time by heater (minutes)) < [1176 - 3.31 × (Heater temperature (°C))]

7. The manufacturing method according to claim 6, wherein the rate of change of the flow value calculated by the following formula is 3.0 or less. Rate of change of flow value = (F １ -F ０ ) / F ０ F ０ : Flow value of the polychlorotrifluoroethylene before filling it into the mold F １ : Flow value of the polychlorotrifluoroethylene forming the molded body