WO2015105040A1 - ポリテトラフルオロエチレン多孔質膜の製造方法、防水通気部材の製造方法及びエアフィルタ濾材の製造方法 - Google Patents
ポリテトラフルオロエチレン多孔質膜の製造方法、防水通気部材の製造方法及びエアフィルタ濾材の製造方法 Download PDFInfo
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- polytetrafluoroethylene
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
- B01D67/0023—Organic membrane manufacture by inducing porosity into non porous precursor membranes
- B01D67/0025—Organic membrane manufacture by inducing porosity into non porous precursor membranes by mechanical treatment, e.g. pore-stretching
- B01D67/0027—Organic membrane manufacture by inducing porosity into non porous precursor membranes by mechanical treatment, e.g. pore-stretching by stretching
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/30—Polyalkenyl halides
- B01D71/32—Polyalkenyl halides containing fluorine atoms
- B01D71/36—Polytetrafluoroethene
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D39/00—Filtering material for liquid or gaseous fluids
- B01D39/14—Other self-supporting filtering material ; Other filtering material
- B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
- B01D39/1607—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous
- B01D39/1623—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous of synthetic origin
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
- B01D46/54—Particle separators, e.g. dust precipitators, using ultra-fine filter sheets or diaphragms
- B01D46/543—Particle separators, e.g. dust precipitators, using ultra-fine filter sheets or diaphragms using membranes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/001—Combinations of extrusion moulding with other shaping operations
- B29C48/0018—Combinations of extrusion moulding with other shaping operations combined with shaping by orienting, stretching or shrinking, e.g. film blowing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
- B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
- B29C55/10—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial
- B29C55/12—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial
- B29C55/14—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial successively
- B29C55/146—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial successively firstly transversely to the direction of feed and then parallel thereto
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/04—Hydrophobization
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/38—Hydrophobic membranes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
- B29K2027/12—Use of polyvinylhalogenides or derivatives thereof as moulding material containing fluorine
- B29K2027/18—PTFE, i.e. polytetrafluorethene, e.g. ePTFE, i.e. expanded polytetrafluorethene
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
- B29K2105/0005—Condition, form or state of moulded material or of the material to be shaped containing compounding ingredients
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/755—Membranes, diaphragms
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
- C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
- C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
- C08J2327/18—Homopolymers or copolymers of tetrafluoroethylene
Definitions
- the present invention relates to a method for producing a polytetrafluoroethylene (PTFE) porous membrane, a method for producing a waterproof ventilation member using the PTFE porous membrane, and a method for producing an air filter medium in which the PTFE porous membrane is used for a collection layer.
- PTFE polytetrafluoroethylene
- a porous PTFE membrane is obtained by extruding and molding a mixture obtained by mixing PTFE fine powder and a liquid lubricant as an extrusion aid, and rolling the resulting molded body into a sheet and rolling it.
- the liquid lubricant is removed from the PTFE sheet, and the PTFE sheet from which the liquid lubricant has been removed is stretched to make it porous.
- Openings may be provided in the housings of electronic devices and lighting devices.
- an electronic device acoustic energy propagates between an acoustic transducer such as a microphone or a speaker housed inside the housing and the outside of the housing through the opening.
- an acoustic transducer such as a microphone or a speaker housed inside the housing and the outside of the housing through the opening.
- air that expands due to heat generated by the light emitter is discharged to the outside through the opening.
- a small electronic device typified by a mobile phone and a vehicle lighting device typified by a headlamp of an automobile may be required to have high waterproof properties, so that it is necessary to prevent water from entering from the opening. For this reason, the waterproof ventilation member which has both water resistance and air permeability is arrange
- Patent Document 1 includes a step of extruding a mixture containing PTFE fine powder having a standard specific gravity of 2.19 or less and a liquid lubricant into a sheet shape using a flat die to obtain a PTFE sheet, and the PTFE sheet in its longitudinal direction.
- a method for producing a PTFE porous membrane comprising a step of stretching a PTFE sheet in each of the longitudinal direction and the width direction to make it porous. According to this production method, it is possible to obtain a PTFE porous membrane with improved both water resistance and air permeability.
- an object of the present invention is to provide a method for producing a PTFE porous membrane suitable for suppressing stretching unevenness of the PTFE porous membrane. Moreover, the objective of this invention is providing the manufacturing method of the waterproof ventilation member provided with the PTFE porous membrane by which the stretching nonuniformity was suppressed, and the manufacturing method of an air filter medium.
- suppression of stretching unevenness can be achieved by adjusting the temperature of the PTFE sheet to 19 ° C. or higher when stretching the PTFE sheet from which the liquid lubricant has been removed in the width direction.
- the present invention A process A for obtaining a PTFE sheet by extruding a mixture containing PTFE fine powder and a liquid lubricant into a sheet; and Step B, rolling the PTFE sheet through a pair of rolls along the longitudinal direction of the sheet, which is the extrusion direction in Step A; Heating the PTFE sheet at a temperature of less than 19 ° C. to a temperature of 19 ° C. or higher; Step D for stretching the rolled PTFE sheet at a temperature of 19 ° C.
- Step E for removing the liquid lubricant from the PTFE sheet stretched in Step D;
- a step F in which the PTFE sheet from which the liquid lubricant has been removed in the step E is stretched in each of the longitudinal direction and the width direction of the sheet to obtain a PTFE porous membrane;
- a method for producing a PTFE porous membrane comprising:
- a method for manufacturing a waterproof ventilation member comprising a step of connecting a fixing member to a connection region surrounding the ventilation region of the PTFE porous membrane.
- a method for manufacturing a waterproof ventilation member which further includes a manufacturing method as a step of preparing the PTFE porous membrane.
- Another aspect of the present invention is a method for producing an air filter medium comprising a step of joining a PTFE porous membrane and a breathable support material, the method for producing a PTFE porous membrane according to the present invention, Provided is a method for producing an air filter medium, which is further included as a step of preparing a PTFE porous membrane.
- the present invention uneven stretching of the PTFE porous membrane can be suppressed. According to the present invention, it is possible to stably mass-produce a PTFE porous membrane having improved water resistance and air permeability.
- a mixture containing PTFE fine powder and a liquid lubricant is extruded into a sheet shape using a flat die (T die) (step A).
- the PTFE sheet extruded from the die is rolled by passing between a pair of rolls along the longitudinal direction (MD, machine flow direction, same as the extrusion direction in step A) (step B).
- Process B is preferably performed while maintaining the length of the PTFE sheet in the width direction.
- the PTFE sheet is stretched only in the longitudinal direction.
- this rolling is performed by passing the PTFE sheet between the pair of rolling rolls while pulling the PTFE sheet with a pulling roll disposed downstream of the pair of rolling rolls in the sheet flow direction.
- the rotational speed of the pulling roll is set slightly higher than the rotational speed of the rolling roll, the PTFE sheet is rolled in the longitudinal direction while keeping the length in the width direction constant.
- the temperature of the rolled PTFE sheet is affected by the temperature of the roll and the atmosphere, it may be lower than 19 ° C., which is the phase transition point of PTFE.
- the temperature of the PTFE sheet is so low, the film thickness distribution in the width direction of the obtained PTFE porous film becomes large.
- the PTFE sheet at a temperature of less than 19 ° C. is heated to a temperature of 19 ° C. or more (step C). That is, in Step C, the PTFE sheet at a temperature lower than the phase transition point of PTFE is heated so as to have a temperature equal to or higher than the phase transition point of PTFE. However, it is preferable to heat the PTFE sheet so as to be less than the boiling point of the liquid lubricant to be used, for example, less than 200 ° C.
- the step C is preferably performed immediately before the step D. However, as long as the temperature of the PTFE sheet drawn in the process D is 19 ° C. or higher, the process C may be performed at any stage after the process A. Step C may be performed before step B, for example.
- a PTFE sheet at a temperature of 19 ° C. or higher is stretched in the width direction (step D).
- the PTFE sheet is sequentially stretched in a state containing the liquid lubricant in the longitudinal direction and the width direction.
- the temperature of the PTFE sheet may be 19 ° C. or higher while stretching is started.
- the subsequent steps E and F are basically performed in the same manner as in the past. Specifically, first, the liquid lubricant is removed by heating the PTFE sheet (step E). Subsequently, the PTFE sheet is stretched in the longitudinal direction and the width direction to produce a PTFE porous membrane (step F). It is preferable to implement the process F at the temperature below the melting point of PTFE. Thereafter, the porous PTFE membrane may be heated to a temperature equal to or higher than the melting point of PTFE and baked (step G).
- the draw ratio is appropriately adjusted so as to obtain desired characteristics.
- the stretched surface ratio calculated by the product of the stretch ratio in the longitudinal direction and the stretch ratio in the width direction is appropriately adjusted according to the use of the PTFE porous membrane.
- the stretched surface magnification is suitably 4 times or more and less than 500 times, for example.
- the stretched surface magnification is 16 times or more and 140 times or less, particularly 30 times or more and 140 times or less, and in some cases 50 times or more and 140 times or less.
- the stretched surface magnification may be 16 times or more and less than 30 times.
- the stretch ratio is 150 to 700 times.
- Standard specific gravity is also referred to as SSG, and is a specific gravity defined by the measurement method stipulated in Japanese Industrial Standard (JIS) K6892, and is known to have a negative correlation with the average molecular weight.
- JIS Japanese Industrial Standard
- Asahi Fluoropolymers' full-on CD-123 has a standard specific gravity of 2.155 and an average molecular weight of 12 million.
- the company's full-on CD-145 has a standard specific gravity of 2.165 and an average molecular weight of 8 million.
- the standard specific gravity is 2.20 and the average molecular weight is 2 million.
- the mixing ratio of the PTFE fine powder and the liquid lubricant in the step A is preferably 5 to 50 parts by mass, particularly 5 to 30 parts by mass with respect to 100 parts by mass of the PTFE fine powder.
- the liquid lubricant conventionally used hydrocarbon oils such as liquid paraffin and naphtha may be used. In the present invention, it is not necessary to add a large amount of liquid lubricant.
- a flat die is used to extrude the mixture containing PTFE fine powder.
- the flat die examples include a straight manifold type T die, a coat hanger type T die, and a fish tail type T die. Since the extrusion molding in step A is not a melt extrusion molding but an extrusion molding of a paste mixed with an auxiliary agent, the viscosity of the mixture to be extruded is high. For this reason, use of a fishtail type T die (fishtail die) is suitable among the above dies.
- the thickness of the PTFE sheet extruded in step A is suitably 0.5 to 5.0 mm, particularly 1.2 to 2.0 mm.
- step B the PTFE sheet is rolled in a state containing a liquid lubricant, and the PTFE sheet is stretched thinner than during extrusion to make the thickness uniform.
- This rolling can be performed, for example, as a process in which the length in the width direction of the PTFE sheet does not change.
- the rolling in the process B is a process of stretching the PTFE sheet only in the longitudinal direction.
- the rolling in the process B is performed by passing the PTFE sheet between the pair of rolling rolls while pulling the PTFE sheet with a pulling roll disposed downstream of the pair of rolling rolls in the sheet flow direction. It is preferable to carry out by rolling. At this time, if the rotational speed of the pulling roll is set slightly higher than the rotational speed of the rolling roll, the PTFE sheet is stretched in the longitudinal direction while keeping the length in the width direction constant.
- the rolling of the PTFE sheet in step B is preferably performed so that the length in the width direction after rolling relative to the length in the width direction before rolling is in the range of 90 to 110%, preferably 95 to 105%. .
- the sheet is rolled “while maintaining the length in the width direction”.
- the thickness of the PTFE sheet after rolling is 50 to 2000 ⁇ m, particularly 100 to 900 ⁇ m.
- the thickness of the PTFE sheet is preferably 70% or less, for example, 5 to 60%, compared with the thickness before rolling.
- the thickness of the PTFE sheet in step B may be 30% or less, for example, 10 to 15%, compared with the thickness before rolling.
- the rolling in the process B needs to be performed in a state where the liquid lubricant is held on the PTFE sheet. For this reason, it implements, keeping the temperature of a PTFE sheet below the boiling point (200 degreeC) of a liquid lubricant.
- the liquid lubricant may cause the temperature of the PTFE sheet to be lower than the ambient temperature due to heat of vaporization.
- the temperature of the PTFE sheet that has been rolled and expanded in surface area it is not uncommon for the temperature of the PTFE sheet that has been rolled and expanded in surface area to be less than 19 ° C.
- step C the temperature of the rolled PTFE sheet is heated to 19 ° C. or higher, preferably 25 ° C. or higher, more preferably 30 ° C. or higher. However, it is preferable to heat the PTFE sheet so that the temperature is less than 200 ° C, preferably less than 150 ° C, more preferably less than 100 ° C. There is no restriction
- the PTFE sheet may be heated using a heater such as an infrared heater, or may be heated in a thermostatic chamber or a processing chamber maintained at a predetermined temperature.
- step D the PTFE sheet is stretched in the width direction in a state containing the liquid lubricant.
- This stretching may be performed using a tenter that has been conventionally used for stretching in the width direction.
- the stretching ratio in step D is suitably 1.2 to 10 times, particularly 2.0 to 8.0 times, and in some cases 5.0 to 8.0 times. If the draw ratio is too low, it is difficult to sufficiently change the film structure. On the other hand, when this draw ratio is too high, strength reduction in the longitudinal direction and film thickness nonuniformity may occur.
- step D since it is necessary to carry out in a state where the liquid lubricant is held on the PTFE sheet, it is carried out while keeping the temperature of the PTFE sheet below the boiling point (200 ° C.) of the liquid lubricant. For example, it is preferable to carry out while keeping the temperature of the PTFE sheet at 100 ° C. or lower, preferably 60 ° C. or lower, and in some cases 40 ° C. or lower.
- step E the liquid lubricant is removed from the PTFE sheet stretched in the width direction.
- This step may be performed as usual by drying the PTFE sheet, specifically by maintaining the PTFE sheet containing the liquid lubricant at a temperature suitable for removing the liquid lubricant.
- the temperature suitable for drying is about 100 to 300 ° C.
- step F the PTFE sheet from which the liquid lubricant has been removed is successively stretched in the longitudinal direction and the width direction to become porous.
- the stretching in the longitudinal direction and the width direction may be carried out by a roll stretching method using a difference in the rotation speed of a roll and a tenter stretching method using a tenter, respectively, as usual. Either stretching in the longitudinal direction or stretching in the width direction may be performed first.
- step F has a great influence on the membrane structure and membrane properties of the obtained PTFE porous membrane. What is necessary is just to set the draw ratio in the process F suitably suitably according to a desired film
- the stretching ratio in the longitudinal direction is usually 2 to 50 times, particularly 4 to 20 times, and the stretching ratio in the width direction is usually 3 to 70 times, particularly 4 to 30 times. Is preferred.
- the stretching ratio in the longitudinal direction is usually 5 to 30 times, particularly 10 to 20 times, and the stretching ratio in the width direction is 10 to 40 times, particularly A ratio of 20 to 30 times is preferable.
- the stretched plane magnification is preferably 250 times or more, particularly preferably 300 times or more in order to reduce the pressure loss, and 700 times or less in order to prevent a significant reduction in the collection efficiency. In particular, 600 times or less is preferable.
- the preferred stretched plane magnification for the PTFE porous membrane for the air filter medium is 300 times or more and 700 times or less.
- the stretching in step F is preferably performed at a temperature lower than the melting point (327 ° C.) of PTFE, for example, 60 to 300 ° C., particularly 110 to 150 ° C. Formation of fine fibrils is promoted by stretching in step F.
- step G the porous PTFE membrane is heated to a temperature equal to or higher than the melting point of PTFE.
- This heating step is generally referred to as “firing” and brings about an improvement in the strength of the PTFE porous sheet.
- the firing temperature is suitably 327 to 460 ° C.
- the film thickness of the PTFE porous membrane according to the present invention is not particularly limited, but is preferably 1 ⁇ m to 300 ⁇ m, more preferably 2 ⁇ m to 50 ⁇ m.
- the thickness of the PTFE porous membrane is preferably 5 to 15 ⁇ m, more preferably 7 to 13 ⁇ m, for example, 8 to 12 ⁇ m.
- the PTFE porous membrane according to the present invention may have characteristics suitable as a waterproof breathable membrane.
- a waterproof ventilation member according to the present invention will be described with reference to the drawings.
- the 1A and 1B includes a PTFE porous membrane 1 and a fixing member 2 for fixing the PTFE porous membrane 1 to a casing that should ensure ventilation.
- the fixing member 2 is connected to the PTFE porous membrane 1 in a connection region 4 surrounding the ventilation region 3 of the PTFE porous membrane 1.
- the surface of the fixing member 2 opposite to the surface connected to the PTFE porous membrane 1 is joined to the surface of the housing so as to surround the opening provided in the housing, and the PTFE porous membrane 1 is attached to the housing. To fix. In this state, the air permeability of the housing is ensured by the air passing through the opening of the housing and the membrane 1 in the ventilation region 3, and the water resistance of the PTFE porous membrane 1 prevents water from entering the housing.
- the ring-shaped fixing member 2 is used, but the shape of the fixing member 2 is not limited to the ring shape.
- 1A and 1B is a double-sided tape, but the shape of the fixing member 2 is not limited to the tape shape.
- the fixing member 2 a resin member molded so as to be fitted into the opening of the housing may be used.
- the waterproof ventilation member shown in FIG. 2 includes a plurality of fixing members 2 a and 2 b together with the PTFE porous membrane 1.
- the fixing members 2a and 2b have a ring shape when observed from a direction orthogonal to the membrane surface, as with the fixing member 2 (see FIGS. 1A and B), and both main surfaces of the PTFE porous membrane 1 In FIG.
- This waterproof ventilation member is suitable for use inside a housing of an electronic device, for example.
- the fixing member 2a is joined to a device (for example, a speaker) disposed inside the casing
- the fixing member 2b is joined to the inner surface of the casing so as to surround the opening of the casing.
- the PTFE porous membrane according to the present invention may have characteristics suitable as a collection layer for an air filter. According to the present invention, it is also possible to provide a PTFE porous membrane having an improved PF value while preventing a large decrease in the average fibril diameter (average fiber diameter). That is, according to the present invention, the average fiber diameter is 55 nm or more, further 57 nm or more, particularly 58 nm or more, and in some cases 60 nm or more, for example 55 to 83 nm, particularly 55 to 80 nm, while maintaining a PF value of 36 or more, Can provide a porous PTFE membrane that is improved to 37 or more, particularly 38 or more, and in some cases 40 or more. A PTFE porous membrane having a large average fiber diameter is advantageous in maintaining strength.
- CE is a collection efficiency, and is determined by a value measured using dioctyl phthalate having a particle diameter of 0.10 to 0.20 ⁇ m under a condition of a permeation flow rate of 5.3 cm / sec.
- PL is a pressure loss, and is determined by a value measured under the condition of a permeation flow rate of 5.3 cm / sec.
- the present invention 99.999% or more (displayed in a form using a continuous number of 9 and 5N or more), 99.9999% (6N) or more, especially 99.99999% (7N) or more.
- 6N 99.9999%
- 7N 99.99999%
- This laminating step may be performed by joining the PTFE porous membrane and the breathable support material according to a conventionally performed method.
- the fiber constituting the breathable support material is a thermoplastic resin, specifically, polyolefin (for example, polyethylene (PE), polypropylene (PP)), polyester (for example, polyethylene terephthalate (PET)), polyamide, or a composite material thereof. What was comprised is preferable.
- breathable support material woven fabric, non-woven fabric, felt or the like can be used, but non-woven fabric is frequently used.
- a typical nonwoven fabric known as a preferable breathable support material is composed of a composite fiber having a core-sheath structure, and the melting point of the core component (for example, PET) is higher than the melting point of the sheath component (for example, PE).
- This nonwoven fabric is suitable for thermal lamination in which the sheath component is melted and joined to the PTFE porous membrane.
- the lamination of the PTFE porous membrane and the breathable support material can be carried out by an adhesive laminate or the like in addition to the above-mentioned thermal lamination.
- an adhesive laminate for example, use of a hot melt type adhesive is appropriate.
- the laminated structure of the PTFE porous membrane and the air-permeable support material is not particularly limited, but has a configuration in which at least one layer of air-permeable support material is disposed on both sides of the PTFE porous membrane (typically, the air-permeable material). It is preferable to use a three-layer structure of porous support material / PTFE porous membrane / breathable support material). However, if necessary, a configuration using two layers of PTFE porous membrane (for example, a five-layer configuration of breathable support material / PTFE porous membrane / breathable support material / PTFE porous membrane / breathable support material), etc. It is good.
- a configuration in which a breathable support material having a small diameter is used as a prefilter (for example, from the upstream side of the airflow, the breathable support material (prefilter) / breathable support material / PTFE porous membrane / breathable support). It is also possible to employ a four-layer construction of materials.
- the air filter medium is also pleated by a known method.
- the pleating process is performed by, for example, using a reciprocating processing machine to fold the filter medium into a continuous W shape with mountain fold lines and valley fold lines set alternately and in parallel on the surface of the filter medium.
- the pleated air filter medium may be referred to as an air filter pack.
- a spacer may be disposed to maintain a pleated shape.
- a resin string called a bead is often used.
- the bead is moved along a direction orthogonal to the mountain fold (valley fold) line (a direction that goes over the valley and crosses the valley), and preferably a plurality of beads move along this direction while maintaining a predetermined interval.
- the beads are preferably arranged on both the front and back surfaces of the filter medium.
- the bead is typically formed by melting and applying a resin such as polyamide or polyolefin.
- the pleated air filter medium (air filter pack) is processed into an air filter unit by supporting the peripheral edge with a frame (support frame) as necessary.
- a frame a metal or resin member is used depending on the use of the air filter.
- the filter medium may be fixed to the frame at the same time as the frame is molded by an injection molding method.
- FIG. 4 shows an example of the air filter unit.
- the air filter unit 30 includes a pleated air filter medium 10 and a frame 20 that fixes an outer edge of the air filter medium 10.
- Example 1 A mixture was obtained by uniformly mixing 19 parts by weight of a liquid lubricant (Isopar) with 100 parts by weight of PTFE fine powder ("Polyflon F-104" manufactured by Daikin, SSG 2.171). The mixture was then extruded into a sheet using an extruder equipped with a fishtail die. The extruded PTFE sheet had a thickness of 1.5 mm and a width of 20 cm.
- a liquid lubricant Isopar
- PTFE fine powder Polyflon F-104" manufactured by Daikin, SSG 2.171
- the PTFE sheet was rolled by passing between a pair of metal rolling rolls. This rolling was carried out while pulling the PTFE sheet in the longitudinal direction using a roll disposed on the downstream side of the rolling roll so that the length in the width direction of the PTFE sheet was maintained before and after rolling.
- the thickness of the PTFE sheet obtained by rolling was 200 ⁇ m.
- the temperature of the rolled PTFE sheet was 5 to 10 ° C.
- the rolled PTFE sheet was heated to a temperature of 19 ° C. or higher. Specifically, the rolled PTFE sheet was heated at a speed of 7 m / min through an apparatus set at 100 ° C. so that the sheet temperature was 50 ° C.
- the PTFE sheet at 40 ° C. was stretched 4 times in the width direction while containing the liquid lubricant. Thereafter, the stretched PTFE sheet was maintained at 150 ° C. to remove the liquid lubricant.
- the PTFE sheet from which the liquid lubricant has been removed is stretched 12 times in the longitudinal direction at a stretching temperature of 280 ° C. by a roll stretching method, and further 30 times in the width direction at a stretching temperature of 110 ° C. by a tenter stretching method. Stretched to obtain an unsintered PTFE porous membrane.
- the drawing surface magnification of the drawing carried out after removing the liquid lubricant is 360 times.
- the unsintered PTFE porous membrane was fired at 400 ° C. using a hot air generating furnace to obtain a band-like PTFE porous membrane.
- the PTFE porous membrane was made of two core-sheathed non-woven fabrics (weight per unit area 30 g / m 2 , core component PET, sheath component PE, apparent density 0.158 g / cm 2 , embossed area ratio 15%, thickness 0. 19 mm) and heat-laminated by passing between a pair of rolls heated to 180 ° C. to obtain a three-layer air filter medium (long filter medium having a width of 780 mm and a length of 200 m). It was.
- the obtained air filter medium was subjected to pleating (mountain height (pleat width) 50 mm, number of peaks 186).
- the pleated air filter medium was cut, and the periphery thereof was joined to a metal support frame using an adhesive to obtain an air filter unit (size: 610 mm ⁇ 610 mm, thickness 65 mm).
- Example 1 Comparative Example 1 Except that the rolled PTFE sheet was heated to a temperature of 19 ° C. or higher, and the PTFE porous material was the same as in Example 1 except that the rolled PTFE sheet was stretched in the width direction at a temperature of 5 to 10 ° C. A membrane was prepared.
- Comparative Example 2 A porous PTFE membrane was produced in the same manner as in Comparative Example 1 except that the blending amount of the liquid lubricant (Isopar) was 17 parts by weight.
- the thickness of the obtained PTFE porous membrane was examined. Specifically, using a dial gauge with a scale of 0.001 mm and a probe outer diameter of 10 mm, the PTFE porous membrane at the left end, the center and the right end in the longitudinal direction of the PTFE porous membrane is shown. The thickness was examined. The results of measuring the thickness of the porous PTFE membranes of Example 1 and Comparative Examples 1 and 2 are shown in FIG.
- Example 1 when the PTFE sheet from which the liquid lubricant was removed was stretched in the width direction, the thickness of the obtained PTFE porous film was almost the same depending on the position in the width direction, and stretching unevenness did not occur.
- Comparative Examples 1 and 2 when the PTFE sheet from which the liquid lubricant was removed was stretched in the width direction, the thickness at the center of the obtained PTFE porous membrane was such that the left end and the right end of the PTFE porous membrane were Stretching unevenness occurred, which was thicker than the thickness at the part.
- the PTFE porous membrane according to the present invention is useful as a waterproof permeation member, an air filter medium, and also as a material that improves the level of selective permeation in other applications.
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- Medicinal Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Materials Engineering (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
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- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
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Abstract
Description
PTFEファインパウダーと液状潤滑剤とを含む混合物をシート状に押し出し、PTFEシートを得る工程Aと、
前記PTFEシートを、前記工程Aにおける押し出し方向である前記シートの長手方向に沿って1対のロールの間を通過させて圧延する工程Bと、
19℃未満の温度にある前記PTFEシートを、19℃以上の温度になるように加熱する工程Cと、
19℃以上の温度にある圧延された前記PTFEシートを、前記シートの長手方向に直交する幅方向に延伸する工程Dと、
前記工程Dにおいて延伸されたPTFEシートから前記液状潤滑剤を除去する工程Eと、
前記工程Eにおいて前記液状潤滑剤が除去されたPTFEシートを、当該シートの長手方向及び幅方向のそれぞれについて延伸して、PTFE多孔質膜を得る工程Fと、
を具備するPTFE多孔質膜の製造方法、を提供する。
PF値={-log(PT(%)/100)/(PL(Pa)/9.8)}×100
で与えられる値である。この式におけるPTは、透過率であって、PT(%)=100-CE(%)により定められる。CEは、捕集効率であって、粒子径0.10~0.20μmのジオクチルフタレートを用いて透過流速5.3cm/秒の条件で測定したときの値により定められる。PLは、圧力損失であって、透過流速5.3cm/秒の条件で測定したときの値により定められる。
PTFEファインパウダー(ダイキン社製「ポリフロンF-104」、SSG2.171)100重量部に液状潤滑剤(アイソパー)19重量部を均一に混合して混合物を得た。次いで、この混合物を、フィッシュテールダイを装着した押出機を用いてシート状に押し出した。押し出したPTFEシートの厚みは1.5mm、幅は20cmであった。
圧延したPTFEシートを19℃以上の温度になるように加熱せず、圧延したPTFEシートの温度が5~10℃の状態で幅方向に延伸した以外は実施例1と同様にして、PTFE多孔質膜を作製した。
液状潤滑剤(アイソパー)の配合量を17重量部とした以外は比較例1と同様にして、PTFE多孔質膜を作製した。
Claims (9)
- ポリテトラフルオロエチレンファインパウダーと液状潤滑剤とを含む混合物をシート状に押し出し、ポリテトラフルオロエチレンシートを得る工程Aと、
前記ポリテトラフルオロエチレンシートを、前記工程Aにおける押し出し方向である前記シートの長手方向に沿って1対のロールの間を通過させて圧延する工程Bと、
19℃未満の温度にある前記ポリテトラフルオロエチレンシートを、19℃以上の温度になるように加熱する工程Cと、
19℃以上の温度にある圧延された前記ポリテトラフルオロエチレンシートを、前記シートの長手方向に直交する幅方向に延伸する工程Dと、
前記工程Dにおいて延伸されたポリテトラフルオロエチレンシートから前記液状潤滑剤を除去する工程Eと、
前記工程Eにおいて前記液状潤滑剤が除去されたポリテトラフルオロエチレンシートを、当該シートの長手方向及び幅方向のそれぞれについて延伸して、ポリテトラフルオロエチレン多孔質膜を得る工程Fと、
を具備するポリテトラフルオロエチレン多孔質膜の製造方法。 - 前記ポリテトラフルオロエチレン多孔質膜をポリテトラフルオロエチレンの融点以上の温度で焼成する工程Gをさらに具備する、請求項1に記載のポリテトラフルオロエチレン多孔質膜の製造方法。
- 前記工程Bにおいて、前記ポリテトラフルオロエチレンシートの前記幅方向についての長さを維持しながら前記ポリテトラフルオロエチレンシートを圧延する、請求項1に記載のポリテトラフルオロエチレン多孔質膜の製造方法。
- 前記ポリテトラフルオロエチレンファインパウダーの標準比重が2.19以下である、請求項1に記載のポリテトラフルオロエチレン多孔質膜の製造方法。
- 前記混合物における前記ポリテトラフルオロエチレンファインパウダーと前記液状潤滑剤との混合比を、前記ポリテトラフルオロエチレンファインパウダー100質量部に対し、前記液状潤滑剤5~50質量部の範囲とする、請求項1に記載のポリテトラフルオロエチレン多孔質膜の製造方法。
- 前記工程Aにおいて、前記混合物をフィッシュテールダイを用いてシート状に押し出し、前記ポリテトラフルオロエチレンシートを得る、請求項1に記載のポリテトラフルオロエチレン多孔質膜の製造方法。
- 前記工程Eにおいて、前記長手方向の延伸倍率と前記幅方向の延伸倍率との積を4倍以上500倍以下とする、請求項1に記載のポリテトラフルオロエチレン多孔質膜の製造方法。
- ポリテトラフルオロエチレン多孔質膜の通気領域を囲む接続領域に固定用部材を接続する工程を具備する防水通気部材の製造方法であって、
請求項1に記載の製造方法を、前記ポリテトラフルオロエチレン多孔質膜を準備する工程としてさらに含む、防水通気部材の製造方法。 - ポリテトラフルオロエチレン多孔質膜と通気性支持材とを接合する工程を具備するエアフィルタ濾材の製造方法であって、
請求項1に記載の製造方法を、前記ポリテトラフルオロエチレン多孔質膜を準備する工程としてさらに含む、エアフィルタ濾材の製造方法。
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US15/110,633 US20160325235A1 (en) | 2014-01-10 | 2015-01-06 | Method for producing porous polytetrafluoroethylene membrane, method for producing waterproof gas-permeable member, and method for producing air filter medium |
CN201580004101.9A CN105899285A (zh) | 2014-01-10 | 2015-01-06 | 聚四氟乙烯多孔膜的制造方法、防水透气构件的制造方法和空气过滤器过滤介质的制造方法 |
KR1020167021147A KR20160104714A (ko) | 2014-01-10 | 2015-01-06 | 폴리테트라플루오로에틸렌 다공질막의 제조 방법, 방수 통기 부재의 제조 방법 및 에어 필터 여과재의 제조 방법 |
EP15735234.5A EP3093065A1 (en) | 2014-01-10 | 2015-01-06 | Production method for polytetrafluoroethylene porous film, production method for waterproof air-permeable member, and production method for air filter filtering medium |
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JP6920042B2 (ja) * | 2016-09-30 | 2021-08-18 | 日東電工株式会社 | エアフィルタ濾材、エアフィルタパック及びエアフィルタユニット |
KR20190062168A (ko) * | 2017-11-28 | 2019-06-05 | 주식회사 엘지화학 | 불소계 수지 다공성 막의 제조방법 |
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US20220105452A1 (en) | 2018-12-28 | 2022-04-07 | Nitto Denko Corporation | Filter pleat pack and air filter unit |
CN115230131B (zh) * | 2022-09-19 | 2022-11-29 | 四川省众望科希盟科技有限公司 | 提高膨体聚四氟乙烯薄膜均匀度的双向拉伸装置及方法 |
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