JP6546143B2 - Method of manufacturing injection molded articles - Google Patents

Description

  In the present invention, cleaning is performed by supplying a treatment liquid or an inert gas to a semiconductor substrate, a glass substrate for a liquid crystal display device, a glass substrate for a photomask, a substrate for an optical disk, etc. (hereinafter may be simply referred to as “substrate”). The present invention relates to an injection-molded article (container-like article) used in a substrate processing apparatus for cleaning treatment, and in particular, a container-like product obtained by injection molding a composition containing tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer. It relates to an article.

  In the process of manufacturing electronic substrates such as semiconductor manufacturing equipment and liquid crystal manufacturing equipment, residues of photoresist, residues of organic solvents, synthetic waxes, organic residues such as fatty acids from the human body, sodium, potassium, gold, iron, copper, etc. Inorganic contaminants and other fine particles are generated, but it is necessary to remove them so as not to be introduced to the subsequent process. Therefore, as a technology to keep the substrate surface highly clean and effectively remove particles and contaminants, the cleaning and drying process consisting of chemical treatment with a chemical and rinse treatment with a rinse such as pure water is important. .

  The apparatus described in Patent Document 1 is a substrate cleaning apparatus for cleaning a substrate, and includes a substrate rotation holding unit that holds and rotates a substrate, and a cleaning liquid or a rinse liquid applied to the substrate held by the substrate rotation holding unit. And a member that comes in contact with the cleaning liquid splattering from the substrate rotated by the substrate rotating means. In Patent Document 1, while rotating the substrate holding unit and the atmosphere blocking plate, a chemical solution process with a chemical solution, a rinse process with pure water, and the like are performed on the substrate.

  In such an apparatus for cleaning a substrate, pure water, nitric acid water, hydrochloric acid water, hydrofluoric acid water, mixed hydrofluoric acid water (hydrogen peroxide water, hydrofluoric acid water, etc.) are directed to the substrate held by the substrate holder. Chemical solutions such as acidic solutions such as ammonia water, and alkaline solutions such as aqueous ammonia and SC-1 (mixture of ammonia water and hydrogen peroxide solution) (hereinafter collectively referred to as “chemical solution”) The contaminants attached to the substrate are removed by supplying pure water and a chemical solution generically and sometimes called “processing solution”. Therefore, it is known that the chemical solution adheres to the substrate holding portion and the inert gas flow path, and the corrosion of the chemical solution adhering portion causes the processing failure of the substrate.

  Therefore, in order to solve the processing defects of the substrate due to the corrosion of the chemical solution, it is proposed that the member of the processing apparatus to which the chemical solution adheres be formed of a resin having heat resistance and chemical resistance, and such resin Examples of the fluorocarbon resin include fluorine resins such as tetrafluoroethylene resin (PTFE) and tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer (PFA) (Patent Documents 1 and 2). In particular, bottles and tubes obtained by melt extrusion of PFA, which has melt formability and is also excellent in heat resistance and chemical resistance, are containers for high purity chemical solutions for semiconductor manufacturing, and transfer of chemical solutions and ultrapure water, respectively. It is utilized as piping for (patent document 3).

However, in recent years, in addition to the increase in size due to the increase in wafer size, the processing baths and the like in the substrate processing apparatus performed by receiving a plurality of process liquid supplies are complicated in shape due to complex cleaning and cleaning processing functions and the number of parts While there is an increase in the size, high dimensional accuracy is required.
In order to satisfy those requirements, the processing tank and the like are manufactured by cutting a large polytetrafluoroethylene (PTFE) material, but in order to obtain a processing tank finished product by this method, compression of the material block is performed. Since it is necessary to go through long processes such as molding, firing, cutting and annealing, there is a problem that the production efficiency is low and most of the material has to be cut waste.

  In order to reduce the cutting loss of this PTFE, it has been tried to obtain a material having a shape as close as possible to the final shape by using hydraulic forming (isostatic forming) or the like, but even if it is used, Several months are required for forming processes such as compression molding, firing, cutting and accompanying annealing, and cutting loss (amount of cutting waste) is more than 50%.

In addition, PFA has chemical resistance and heat resistance equivalent to PTFE, and is melt-moldable PFA, for example, a molecular weight distribution as described in JP-A-2002-53620 in order to improve the durability of the obtained molded article. And PFA with the melt flow rate (MFR) at 372 ° C. measured according to ASTM D-3307 as a specific range (35 to 60 g / 10 min), or as described in JP-A-10-86205. When trying to obtain a large processing tank as described above by injection molding using PFA having a specific volumetric flow rate, the injection pressure can not be maintained up to the end of the molding die, so a large molded product can be obtained by injection molding. It was difficult to get
In addition, since a large injection pressure and mold clamping pressure are required due to its high melt viscosity as compared with other engineering plastics, there is a problem that a very large injection molding machine is required. Therefore, it is difficult to obtain articles of practical size, in addition to the fact that initial introduction costs and product costs are high and as a result, it is difficult to put them on profitability.

  Parts such as the above-mentioned large processing tank were subdivided into sizes that can be molded with the existing PFA injection molding machine, and this was molded with an injection machine, and then products were obtained by welding or welding In the case, there has been a problem that thermal expansion when the product is used in a high temperature atmosphere causes deformation due to stress concentration on the weld or the weld.

  Furthermore, although other melt forming methods such as transfer molding, rotational molding, blow molding, etc. have been tried, for example, when it is intended to obtain a processing tank as described above by rotational molding, the required high dimensions The accuracy can not be satisfied, and as a result, a lot of additional work is required, and there is a problem that the cost reduction effect is scarce and the production efficiency is low.

JP-A-11-297652 Patent No. 4703944 Patent No. 3559062 gazette JP 2002-53620 A JP 10-86205 A

The present invention, in view of the above-mentioned facts, provides a large-sized injection-molded article obtained by injection-molding a composition containing a heat-meltable fluororesin.
The present invention can be molded with a lower injection pressure than conventional PFA and can be obtained by molding a composition having excellent releasability from a mold, particularly heat resistance and chemical resistance for a substrate processing apparatus. The present invention provides a large-sized injection-molded article which is excellent in size and dimensional accuracy.
The present invention also provides large injection molded articles having complex shapes by injection molding a composition containing PFA.

The present invention relates to a composition comprising a heat-meltable fluororesin which is a tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer, and polytetrafluoroethylene at an injection pressure of 400 kg / cm ² or more and 800 kg / cm ² or less. to provide a method for producing an injection direction of the projected area 1100 cm ² or more injection molded article by.

  The method for producing the above-mentioned injection molded article wherein the melt flow rate (MFR) of the composition is more than 60 g / 10 min and not more than 68 g / 10 min is a preferred embodiment of the present invention.

  The method for producing an injection molded article according to claim 1 or 2, wherein the polytetrafluoroethylene content in the composition is 0.05 to 10% by weight based on the composition.

  The method for producing the above-mentioned injection molded article wherein the polytetrafluoroethylene has a crystallization temperature of 305 ° C. or more and a heat of crystallization of 50 J / g or more is a preferable embodiment of the present invention.

  The method for producing the above-mentioned injection molded article in which the tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer is a tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer is a preferred embodiment of the present invention.

The present invention also provides an injection area diffusion ratio of 3000 or more in a direction perpendicular to the injection direction of a composition containing a heat-meltable fluororesin which is a tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer and polytetrafluoroethylene. And providing a method for producing an injection-molded article having a projected area of 2800 cm ² or more in the injection direction by injection molding.

According to the present invention, it becomes possible to mold a composition (composition containing PFA) having excellent releasability from a mold at a molding pressure lower than that of a conventional PFA. It is possible to provide a large-sized injection molded product which is excellent in chemical resistance and also in dimensional accuracy.
Further, according to the present invention, since large-sized molded articles having complicated shapes can be injection-molded, it is possible to increase production efficiency by shortening the manufacturing process of the products, in addition to reducing the amount of cutting waste. it can.
The large-sized injection-molded articles of the present invention are excellent in heat resistance and chemical resistance, and the production cost is suppressed. Therefore, including members for semiconductor manufacturing devices, chemical corrosion protection applications, OA applications, sliding materials applications, automotive applications, And it can be widely applied to building material applications.

It is sectional drawing which shows one example of the metal mold | die for obtaining the injection molded article of this invention. FIG. 2 is a schematic perspective view showing an injection-molded article obtained from the mold of FIG. It is sectional drawing of the injection molded article of FIG. It is sectional drawing which shows the other example of the metal mold | die which obtains the injection molded article of this invention. FIG. 5 is a schematic perspective view showing an injection-molded article obtained from the mold of FIG. 4; It is sectional drawing of the injection molded product of FIG. It is sectional drawing of the bowl-shaped shape molded article of this invention.

Embodiments of the present invention will be described in detail below.
The heat-meltable fluororesin in the present invention is a melt-moldable fluororesin. Preferred examples thereof include at least one selected from tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer, ethylene / chlorotrifluoroethylene copolymer, and polyvinylidene fluoride. Among these, tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer is mentioned as a more preferable one.

The tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer in the present invention has a fluoroalkoxytrifluoroethylene content of 1 to 10% by weight in the copolymer. Examples of fluoroalkoxytrifluoroethylenes that can be used as comonomers include perfluoroalkenes having 3 or more carbon atoms, preferably 3 to 6 carbon atoms, perfluoro (alkyl vinyl ether) s having 1 to 6 carbon atoms, and the like. And perfluoro (methyl vinyl ether) (hereinafter abbreviated as PMVE), perfluoro (ethyl vinyl ether) (hereinafter abbreviated as PEVE), perfluoro (propyl vinyl ether) (hereinafter abbreviated as PPVE) and the like.
The tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer (hereinafter abbreviated as PFA) in the present invention is preferably a tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer.

The tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer of the present invention is capable of melt molding such as melt extrusion molding and injection molding, and has a melt flow rate (MFR) of 60 g / 10 at 372 ° C. ± 1 ° C. Preferably, the melt flow rate (MFR) is more than 100 minutes and not more than 100 g / 10 minutes, and more preferably 70 to 80 g / 10 minutes. When the MFR is 60 g / 10 min or less, the injection pressure tends to be difficult to maintain up to the molding die end, so a molded article with a projected area of 1100 cm ² or more as in the present invention is obtained by injection molding. It becomes difficult. When the MFR exceeds 100 g / 10 min, it becomes difficult to maintain the shape of the molded article. The copolymer can be produced by known methods such as solution polymerization, emulsion polymerization and suspension polymerization, and it is desirable to select one having a flex life value of at least 1,000 or more.

Further, the tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer of the present invention is more than 60 g / 10 min and not more than 100 g / 10 min at 372 ° C. ± 1 ° C. It can also be mixed and used so that it may become a melt flow rate (MFR) preferably of 70 to 80 g / 10 min. For example, MFR
It is also possible to use a mixture of PFA with less than 60 g / 10 min and PFA with more than 60 g / 10 min to adjust the MFR of the PFA mixture within the above range.

  In the present invention, the composition containing a melt-moldable tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer having an MFR of more than 60 g / 10 min may contain PTFE. The PTFE to be mixed is a homopolymer of tetrafluoroethylene and / or a modified PTFE containing 1 wt% or less of a minor amount of comonomer (hereinafter sometimes collectively referred to as “PTFE” including modified PTFE). As a trace amount comonomer, carbon number 3 or more, preferably C3-C6 perfluoroalkene, C1-C6 perfluoro (alkyl vinyl ether), chlorotrifluoroethylene, etc. are mentioned. Specific examples of the fluorine-containing monomer include hexafluoropropylene (HFP), perfluoro (methyl vinyl ether) (PMVE), perfluoro (ethyl vinyl ether) (PEVE), perfluoro (propyl vinyl ether) (PPVE), and perfluorinated monomers. Preferred are fluoro (butyl vinyl ether) (PBVE) and chlorotrifluoroethylene. Among them, hexafluoropropylene (HFP), perfluoro (ethyl vinyl ether) (PEVE) and perfluoro (propyl vinyl ether) (PPVE) are preferable, and hexafluoropropylene (HFP) is particularly mentioned.

As such PTFE, for example, PTFE having an MFR of 0.01 to 1.0 g / 10 min, which is referred to as "PTFE micro powder" or "PTFE wax", is preferable.
If the MFR of PTFE is less than 0.01 g / 10 min, there may be an extreme decrease in the MFR of the PFA composition, and if it exceeds 1.0 g / 10 min, crystals of PFA by the addition of PTFE may occur. In addition to the decrease in the effect on the plasticity and the deterioration of the resulting injection molded product, the surface may become non-smooth.

  In addition, PTFE mixed in the present invention satisfies two conditions of a crystallization temperature of 305 ° C. or more and a heat of crystallization of 50 J / g or more, which are measured by a differential scanning calorimeter (DSC) by a method described later. Is preferred. The crystallization temperature of PTFE is desirably 305 ° C. or more, preferably 310 ° C. or more, and more preferably 312 ° C. or more. If the PTFE crystallization temperature is less than 305 ° C., the crystallization promoting effect of PFA may be reduced. In addition, when the heat of crystallization is less than 50 J / g, the effect of promoting the crystallization of PFA may be reduced. Therefore, in order to achieve the object of the present invention, it is preferable to use a PFA composition containing PTFE with a heat of crystallization of 50 J / g or more for injection molding.

Such PTFE can be obtained directly by decomposing non-melt-flowing high molecular weight PTFE called "molding powder" or "fine powder" by radiation or heat, or by polymerizing tetrafluoroethylene in the presence of a chain transfer agent. Can.
Specific manufacturing methods are, for example, JP-B-47-19609 or JP-B-52-38870 for the radiolysis method, and US Pat. No. 3,067,262 for the direct polymerization method, for example, US Pat. Or JP-A-7-90024 can be referred to.

The composition containing the tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer of the present invention is capable of melt molding such as melt extrusion molding and injection molding, and has a MFR of 60 g / 10 min at 372 ° C. ± 1 ° C. It is preferable to have an MFR of more than 100 g / 10 min or less, more preferably 70 to 80 g / 10 min. When the MFR is 60 g / 10 min or less, the injection pressure tends to be difficult to maintain up to the molding die end, so a molded article with a projected area of 1100 cm ² or more as in the present invention is obtained by injection molding. It becomes difficult. When the MFR exceeds 100 g / 10 min, it becomes difficult to maintain the shape of the molded article.

  In order to improve the moldability of a composition containing a melt-moldable tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer of the present invention having a MFR of more than 60 g / 10 min, the mixing of PTFE is minimized Although it is desirable, the upper limit of the addition amount of PTFE is not limited. Generally, the injection moldability tends to decrease with the increase of the PTFE content, and when the content of PTFE exceeds 10% by weight, the chemical resistance of the injection molded product obtained with the increase of the content is improved. , Mechanical strength (flex life reduction), separation of PTFE and PFA, aggregation of PTFE, and delamination may occur.

  On the other hand, the crystallinity of the composition tends to increase as the content of PTFE increases, so the content of PTFE varies depending on the MFR of tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer, but the content of PTFE is different. The amount is 0.01 to 50% by weight, preferably 0.01 to 30% by weight, more preferably 0.01 to 10% by weight, and still more preferably 0.05 to 5% by weight. When the addition amount of PTFE is less than 0.01% by weight, it becomes difficult for the injection molded product to protrude from the mold (hard to release).

  Since the PTFE mixed in the present invention has extremely high compatibility with the tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer in the molten state, it is easily dispersed in the copolymer at the time of melt kneading or melt extrusion. Give a very homogeneous composition. Therefore, the shape of the PTFE to be mixed is not particularly limited, but in consideration of workability, it is preferable to be a dispersion of fine particles having an average particle diameter of 0.05 to 1.0 micron or a powder of several microns to several tens microns. .

As a method of mixing PTFE in the present invention, a melt-kneading method, a dry blending method of a pellet or powder of tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer and PTFE powder, a dispersion of the copolymer, and PTFE Any of the known methods such as wet blending with powder and / or PTFE dispersion can be used.
Alternatively, particles of PTFE may be dispersed in advance in a polymerization medium in a PFA polymerization tank to initiate PFA polymerization, and a composition may be obtained as PFA particles containing PTFE.

  For example, as described in JP-A-2007-320267, at least one layer having a multilayer structure made of PTFE and PFA having different melting points and having a melting point higher than that of the outermost layer fluorocarbon resin A fluororesin particle having a multilayer structure having a layer may be used. The fluorine resin having a multilayer structure of at least two kinds of fluorine resins having different melting points preferably comprises 90 to 5% by weight of the outermost layer fluorine resin and 10 to 95% by weight of the high melting point fluorine resin of the inner layer. The ratio of the outermost layer to the inner layer can be selected in consideration of desired chemical resistance and gas permeability, linear expansion coefficient, maximum strength, elongation and the like. From the viewpoint of maintaining the crystallinity of the fluorocarbon resin injection molded article, the high melting point fluorocarbon resin is preferably 10% by weight or more. Further, from the viewpoint of mechanical strength (maximum strength, elongation, etc.) of the obtained fluororesin injection molded article, the low melting point fluororesin is preferably 5% by weight or more.

  The MFR of the composition containing the melt-moldable tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer of the present invention is more than 60 g / 10 min and not more than 100 g / 10 min, more preferably 70 g / 10 min to 100 g / 10 min. It is below. The smaller the MFR, the better the durability of the composition, but if the MFR of the composition is 60 g / 10 min or less, when molding a product with a complicated shape and deep depth, In addition to the fact that mold separation is difficult due to the holding of the injection molded product, etc., many problems such as breakage of the thin-walled part by an ejector occur, which may make it difficult to melt-mold. Further, the upper limit of the MFR of the composition capable of maintaining good durability is 100 g / 10 min, and when it exceeds this, a decrease in flex life is observed, and the durability of the obtained injection molded article may be deteriorated. .

  The composition containing the melt-moldable tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer having an MFR of more than 60 g / 10 min according to the present invention can be molded at a lower injection pressure than conventional PFA, and a mold The composition is used for injection molding of a large-sized injection-molded article having a complicated shape which is particularly excellent in heat resistance, chemical resistance, and dimensional accuracy for a substrate processing apparatus using the composition. Can be molded. For example, an injection-molded article having a wall thickness of 4 mmt and an injection area diffusion ratio of 3000 or more can be obtained by an injection molding machine with a clamping pressure of 800 ton class.

When performing injection molding, it is desirable to suppress the injection pressure to approximately 400 kg / cm ² or more and 800 kg / cm ² or less. When the injection pressure exceeds 800 kg / cm ² , the possibility of burring and overpacking increases. In addition, when the injection pressure is less than 400 kg / cm ² , there is a possibility that the short circuit and the dimensional variation may become large.

The projected area of the injection molded article of the present invention is preferably 1100 cm ² or more. The projected area in the present invention is the area seen when the injection molded article is viewed from the nozzle direction of the injection molding machine, that is, the projected area in the nozzle direction. The projected area of a conventionally known fluoroplastic melt injection molded article is a molded article of less than 1100 cm ² , and no fluoroplastic melt injection molded article having a projected area of 1100 cm ² or more is known. The injection-molded article of the present invention having a projected area of 1100 cm ² or more is a large-sized injection-molded article which is resistant to cracking and excellent in dimensional stability and protrusion.

  The injection molded article of the present invention preferably further has an injection area diffusion ratio of 3000 or more. The injection area diffusion ratio in the present invention is the injection area diffusion ratio in the direction orthogonal to the injection direction, that is, the ratio of the opening area of the tip of the nozzle portion to the projection area of the injection molded product. If the injection area diffusion ratio is less than 3000, the stability of the weight of the injection molded article is poor, that is, the dimensional variation is large, which is not preferable.

The opening area of the tip of the nozzle and the projected area of the injection-molded product used to obtain the injection area diffusion ratio in the present invention will be described below with reference to the drawings.
FIG. 1 shows an example of a mold for obtaining the injection-molded article of the present invention, and shows a cross-sectional view of the mold in a closed state. FIG. 1 also shows the nozzle 1 which is an injection nozzle attached to the tip of the heating cylinder of the injection molding machine. The opening of the nozzle tip is the tip a of the nozzle 1, and the opening area of the nozzle tip refers to the area of the inner opening of the tip a. The molten fluorocarbon resin composition injected from the nozzle 1 passes through the sprue 6, passes through the gate 2, and is filled into the cavity 5 in the mold 4. Xy in FIG. 1 is a center line.

FIG. 2 shows a schematic view of a perspective view of a molded product obtained by opening the mold 4 after injection molding.
FIG. 3 is a cross-sectional view of the obtained molded article 8. In FIG. 3, there is a resin solidified by sprue and gate. Usually, the resin solidified by sprue and gate is also called sprue and gate respectively, so in FIG. 3, the sprue of solidified resin is indicated by 9 and the gate is indicated by 10. The sprue 9 and the gate 10 are eliminated when the final molded product is made, and becomes a molded product as shown in FIG. In FIG. 3, since the nozzle direction of the injection molding machine is in the direction of arrow c, the projection surface of the molded article seen when viewed from the direction of arrow c is formed by the portion shown by 3 in FIG. In FIG. 2, in order to clarify the part shown by 3, the peripheral part is colored black. The projection plane is in the range of A-B. The area occupied by the projection plane is the injection projection area, and the ratio of the injection projection area to the opening area of the tip portion a of the nozzle 1 is calculated as the injection area diffusion ratio.

  FIG. 4 shows another example of a mold for obtaining the injection-molded article of the present invention, and is a cross-sectional view of the mold in a closed state. In FIG. 4, the molten fluorocarbon resin composition injected from the nozzle 1 passes through the two gates 2 from the sprue 6 through the runner 7 and is filled in the cavity 5 in the mold 4. Xy in FIG. 4 is a center line.

FIG. 5 shows a perspective view of a molded product obtained by the injection molding method of FIG. 4 and FIG. 6 shows a cross-sectional view of the molded product 8 obtained. In FIGS. 5 and 6, the sprue 9 of the solidified resin, the runner 11 and the gate 10 are present, but they are deleted when the final molded product is made.
Even in the case where there are two gates, the injection area diffusion ratio is obtained from the projection area which is the area of the projection plane and the opening area of the nozzle tip. In the molded article of FIG. Also in FIG. 6, the projection plane is in the range of AB. The injection area diffusion ratio is calculated for the opening area of the nozzle tip regardless of the number of gates.
The tip portion b of the solidified resin sprue 9 in FIGS. 3 and 6 is a portion corresponding to the nozzle tip opening.

Examples of the shape of the large injection molded article having a projected area of 1100 cm ² or more according to the present invention include a container shape such as a cylindrical shape, a square tank shape, and a bowl shape, a box shape, and a bowl shape. It is possible to replace a product manufactured by cutting of a conventional PTFE injection molded product, and is excellent in economical efficiency such as cost reduction.

  The injection molded article of the present invention has a high degree of crystallinity and is excellent in resistance to chemical solution, so it is extremely advantageous in a product used in an environment where a chemical solution is used other than the treatment tank. It can be used as a member for a substrate cleaning processing apparatus, or their housing.

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples, but the present invention is not limited to these examples.
In addition, the measuring method of the physical property of this invention, and the raw material used in the Example and the comparative example are as follows.

A. Measurement of physical properties (1) Melt flow rate (MFR):
Using a Toyo Seiki melt indexer equipped with a corrosion resistant cylinder, die and piston in accordance with ASTM D-1238-95, a 5 g sample is filled in a 9.53 mm inner diameter cylinder maintained at 372 ° C. ± 1 ° C. After holding for 5 minutes, the sample was extruded through an orifice having an inner diameter of 2.1 mm and a length of 8 mm under a load of 5 kg (piston and weight), and the extrusion speed (g / 10 min) was determined as MFR.

(2) Crystallization temperature (Tc) and heat of crystallization (Hc):
Using a differential scanning calorimeter, increase the temperature of the sample from 200 ° C to 380 ° C at 10 ° C / min, hold at 380 ° C for 1 minute, and then lower the temperature to 200 ° C at 10 ° C / min to obtain a crystallization curve The crystallization peak temperature in is taken as the crystallization temperature.
The heat of crystallization is determined from a peak area defined by connecting a point at which the curve leaves the baseline and a point at which the curve returns to the baseline by a straight line before and after the crystallization peak in the crystallization curve.

(3) Melting point (appended with MDF)
A differential scanning calorimeter (Pyris type 1 DSC, manufactured by Perkin Elmer) was used. 10 mg of the sample powder is weighed and placed in a dedicated aluminum pan, crimped by a dedicated crimper, and then housed in a DSC body, and heated from 150 ° C. to 360 ° C. at a rate of 10 ° C./min. The melting peak temperature (Tm) was determined from the melting curve obtained at this time. )

(4) Protruding (release property)
The product is ejected (released) using an ejector pin of a molding die and an air ejector (air pressure of 0.35 MPa or more) in combination. At that time, the presence or absence of mold release is visually judged as mold release according to the following criteria.
:: The injection molded product can be released while maintaining the normal shape from the mold.
X: A part of the injection molded product was attached to the mold, and the injection molded product could not be released, or the shape of the injection molded product was deformed or broken.

(5) Crackability Using a polarized light microscope, the surface (1 cm × 1 cm) and the cross section of three injection molded articles are observed at a magnification of 100 times and 500 times within 5 cm from the center of the gate, and judged according to the following criteria. .
○: no cracks (cracks or tears) have occurred on any of the three surfaces and the cross section.
X: A crack has occurred on any of the surface and the cross section at three locations.

(6) Dimensional stability Using a three-dimensional measuring instrument BRT-A 710 manufactured by Mitutoyo Corp., the top surface is measured at eight points, and the difference between the maximum and minimum heights is compared to obtain dimensional stability. The dimensional stability is judged according to the following criteria.
Good: The difference between the maximum and the minimum height is 1 mm or less.
X: The difference between the maximum and the minimum height exceeds 1 mm.

(7) Roundness A molded article having an outer diameter of about 400 to 600 is formed by injection molding, and the maximum value and the minimum value of the diameter are measured. The difference between the maximum value and the minimum value of the diameter is determined as roundness according to the following criteria.
○: The difference between the maximum value and the minimum value of the diameter is 1 mm or less.
×: The difference between the maximum value and the minimum value of the diameter exceeds 1 mm.

B. Raw Materials The raw materials used in Examples of the present invention and Comparative Examples are as follows.
(1) PFA1
95% by weight PFA powder (average particle size 300 μm, melting point 305 ° C., melt flow rate 70 g / 10 min), and 0.5% by weight PTFE powder (average particle size 10 μm, melting point 327 ° C., melt flow rate 0.15 g / m A composition consisting of 50 J / g of crystallization heat for 10 minutes is charged into the hopper of an extruder (RA Giken Co., Ltd., 40 mm diameter twin screw extruder) heated to 380 ° C., φ 2 mm × length It was processed into 2 mm pellets. The obtained pellet was named PFA1 (melting point 311 ° C., melt flow rate 68 g / 10 min).
(2) PFA 2
Tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer (PFA).
(Melting point 308 ° C, melt flow rate 61 g / 10 min, pellet shape of φ 2 mm × 2 mm in length)
(3) PFA 3
Tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer (PFA)
Mitsui-Dupont Fluorochemicals PFA 420 HPJ (melting point 307 ° C., melt flow rate 26 g / 10 min, mm 2 mm × 2 mm long pellet)
(4) PFA 4
Tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer (PFA)
Mitsui-Dupont Fluorochemicals PFA 440 HPJ (melting point 308 ° C, melt flow rate 14 g / 10 min, φ2 mm × 3 mm long pellet)

C. Molding method Using the resin shown in the following examples and comparative examples, using an injection molding machine with a clamping pressure of 850 t and 1300 t, cylinder temperature 375 to 400 ° C., mold temperature 160 to 220 ° C., injection speed 15 to 25 mm / sec Then, injection molding was carried out under the conditions shown in Table 1 below, and a wedge-shaped injection molded article having an external size of about 400 to 600 as shown in FIG. 7 was obtained, and the injection area diffusion ratio was calculated.

(Examples 1 and 2, Comparative Examples 1 and 2)
Injection molded articles were obtained under the molding conditions described in Table 2 with the resin and mixing ratio shown in Table 2.
The injection moldability, extrusion property (removal property), crackability and dimensional stability of the obtained injection molded product were measured. The results are shown in Table 2.

  The present invention makes it possible to provide, by injection molding, a large-sized injection-molded article having a complicated shape which is particularly excellent in heat resistance and chemical resistance and is also excellent in dimensional accuracy for a substrate processing apparatus.

  The large-sized injection molded product provided by the present invention is obtained by cutting a large-sized PTFE material, such as a processing tank, in a semiconductor processing apparatus that performs processing by receiving a plurality of types of processing solutions. The product can be obtained by injection molding, and the steps taken to obtain the injection molded product can be significantly shortened, and waste can be significantly reduced, compared with the conventional product. It is possible to significantly reduce product costs.

  In addition, the injection molding method of the large-sized injection molded product according to the present invention enables molding at a low injection pressure, which makes it possible to reduce the size of the molding machine and the size of the mold, further reducing the product cost. Can be

1. Nozzle a. Nozzle tip opening 2. Gate 3. Surface of molded article Mold 5. Cavity 6. Sprue 7. Runner 8. Molded product 9. Sprue 10. Gate 11. Runner b. The tip portion of sprue 9 c. Nozzle direction AB. Projection plane

Claims (5)

Injection of the melt processible fluoropolymer is a tetrafluoroethylene / fluoroalkoxy trifluoroethylene copolymer, injection area diffusion ratio in the direction orthogonal to the emission direction a composition comprising a polytetrafluoroethylene is injection molded at least 3000 Including the molding process
The melt flow rate of the polytetrafluoroethylene is 0.01 to 1.0 g / 10 minutes,
The melt flow rate of the composition is more than 60 g / 10 minutes and not more than 100 g / 10 minutes,
A method of producing an injection-molded article having a projected area of 1100 cm ² or more in the injection direction, wherein the injection molding is performed at an injection pressure of 400 kg / cm ² or more and 800 kg / cm ² or less . Wherein said melt flow rate of the tetrafluoroethylene / fluoroalkoxy trifluoroethylene copolymer, to produce an injection molded article according to claim 1 or less 100 g / 10 min exceeded 60 g / 10 min. The method for producing an injection-molded article according to claim 1 or 2 , wherein the polytetrafluoroethylene content in the composition is 0.05 to 10% by weight based on the composition. The method for producing an injection-molded article according to any one of claims 1 to 3 , wherein the polytetrafluoroethylene has a crystallization temperature of 305 ° C or more and a crystallization heat of 50 J / g or more. The method for producing an injection-molded article according to any one of claims 1 to 4 , wherein the tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer is a tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer.