KR102290206B1 - Porous sintered sheet and manufacturing method thereof - Google Patents

Abstract

A porous sintered sheet containing a resin and having continuous pores, wherein the minimum value of the cross-sectional porosity of the porous sintered sheet is 10% or more, and the position where the minimum value of the cross-sectional porosity exists is the thickness from one side of the sintered sheet A porous sintered sheet within 20% of the depth of the direction.

Description

Porous sintered sheet and manufacturing method thereof

The present invention relates to a porous sintered sheet and a method for manufacturing the same.

As one of the means for fixing or transporting a thin film, plate-like, or film-like thing such as a glass plate for liquid crystal or a green sheet for a multilayer ceramic capacitor, there is a method of adsorption fixing or adsorption transport in an adsorption stage in vacuum suction. In this adsorption stage, in order to prevent the occurrence of scratches or contact marks on the member to be adsorbed, a porous resin body having air permeability is attached to the adsorption surface as an adsorption buffer material. As such a porous resin body, a sintered molded body obtained by sintering polyethylene powder is sometimes used from the viewpoints of rigidity and cushioning properties.

In recent years, miniaturization and high performance of liquid crystal and multilayer ceramic capacitors have been rapidly progressing, and glass plates and ceramic green sheets, which are raw materials thereof, have been made thinner. For this reason, it is necessary to perform very precise adsorption|suction fixing or adsorption|suction conveyance. Therefore, excellent surface smoothness, strength rigidity, etc. are calculated|required also as an adsorption|suction buffer material attached to the adsorption|suction stage in vacuum suction.

As a porous sintered sheet having a dense structure excellent in surface smoothness, a sheet having a high air permeability in the overall thickness direction, a small surface porosity, and a small surface roughness has been proposed (see, for example, Patent Document 1).

Further, as a porous composite excellent in filtration accuracy, high rigidity, and excellent in handling, a porous composite in which a resin porous body forming continuous pores and a microporous membrane are substantially integrated with each other has been proposed (for example, Patent Document 2) Reference).

Further, a molding method capable of forming a porous body with continuous pores by depositing a raw material resin on an endless belt and heating it is disclosed (for example, refer to Patent Document 3).

Japanese Patent Laid-Open No. 2001-28390 Japanese Patent Laid-Open No. 2000-177040 Japanese Patent Laid-Open No. 3-143821

However, in Patent Document 1, in order to improve the surface smoothness of the sheet, a PET sheet or the like having a high surface smoothness is brought into contact with the surface in contact with the member to be adsorbed, and heat treatment is performed in a state where a predetermined or higher pressure is applied. When it compresses strongly in order to improve surface smoothness, the porosity of the whole thickness direction will become small. For this reason, there arises a problem that the thickness of the sheet must be thin in order to obtain a high air permeability. In this case, in order to reinforce the thinned sheet, there arises a problem that another high-permeability sheet must be laminated on the side opposite to the surface in contact with the adsorbed member.

Also in Patent Document 2, in order to obtain a sheet having excellent filtration accuracy, it is necessary to prepare two types of sheets, a thin sheet having a small porosity and poor permeability, and a thick sheet having a large porosity and excellent permeability, and then bonding them. have. Furthermore, when heat-pressing in order to butt each sheet|seat, the problem that a porosity falls or the hole of a butt surface is crushed arises.

In Patent Document 3, neither disclosure nor suggestion is made about the structural control of the continuous pores in the thickness direction.

Therefore, in the present invention, in view of the problems of the prior art described above, although the porosity near at least one surface (for example, the surface and/or the surface opposite to the surface) is small, the gas or liquid permeability is An object of the present invention is to provide a porous sintered sheet excellent in durability over a long period of time due to excellent, high mechanical strength and small pressure loss, and a method for manufacturing the same.

The inventors of the present invention, as a result of intensive studies in order to solve the above problems, as a porous sintered sheet containing a resin and having continuous pores, the minimum value of the porosity of the porous sintered sheet is greater than or equal to a specific value, and the minimum value of the porosity is When the existing position was made into the specific range of the thickness direction from one surface of a sintering sheet|seat, it discovered that said objective was achieved, and it led to this invention.

That is, the present invention is as follows.

(One)

A porous sintered sheet containing a resin and having continuous pores, comprising:

The minimum value of the cross-sectional porosity of the porous sintered sheet is 10% or more, and the position where the minimum value of the cross-sectional porosity exists is within 20% of a depth in the thickness direction from one surface of the sintered sheet.

(2)

The porous sintered sheet according to (1), wherein a difference between an average porosity of the entire porous sintered sheet and a minimum value of a cross-sectional porosity of the porous sintered sheet is 10% or more and 50% or less.

(3)

The porous sintered sheet according to (1) or (2), wherein the product of the air permeability of the porous sintered sheet and the thickness of the porous sintered sheet is 0.2 cm ^{3 /cm/sec or more.}

(4)

The porous sintered sheet according to any one of (1) to (3), wherein an average porosity of the entire porous sintered sheet is 20% or more and 80% or less.

(5)

In the depth in the thickness direction from the one surface, there is no depth position having a cross-sectional porosity that is deeper than the depth position reaching the average porosity of the entire porous sintered sheet and is 20% or more larger than the average porosity, (1) The porous sintered sheet of any one of (4).

(6)

The porous sintered sheet according to any one of (1) to (5), wherein each section obtained by dividing the porous sintered sheet of 1 m ^{2 or more into 100 cm 2 or less satisfies the following condition A.}

(Condition A)

X≤Y×0.2

X: the difference between the depth position where the minimum value of the cross-sectional porosity exists and the depth position where the maximum value of the cross-sectional porosity exists

Y: thickness of the compartment

(7)

The porous sintered sheet according to any one of (1) to (6), wherein the porous sintered sheet has a thickness of 0.05 mm or more and 5.0 mm or less.

(8)

A method for producing a sheet-like porous sintered sheet according to any one of (1) to (7) by supplying a resin on an endless conveyor belt, forming a sheet-like molded body, and heating and pressing the molded body.

(9)

The method for producing a porous sintered sheet according to (8), wherein after heating the molded body, the heated molded body is compressed by a pressing means within a temperature range of ±30° C. of the melting point of the resin.

(10)

The manufacturing method of the porous sintered sheet|seat of (9) whose compression ratio compressed by the said press means is 0.5 % or more and 2 % or less.

(11)

The sheet for adsorption|suction fixed conveyance which has the porous sintered sheet|seat in any one of (1)-(7).

(12)

A sheet for a support for a rapid test kit by immunochromatographic method, comprising the porous sintered sheet according to any one of (1) to (7).

According to the present invention, since the porosity near at least one surface (for example, the surface and/or the surface opposite to the surface) is small and has a compact structure, gas or liquid permeability is excellent, mechanical strength is large, and pressure It is possible to provide a porous sintered sheet excellent in durability over a long period of time and a method for manufacturing the same due to a small loss. The porous sintered sheet of the present invention has a small porosity near at least one surface and excellent permeability.

1 shows an X-ray CT measurement chart of a porous sintered sheet of Example 1. FIG.
Fig. 2 shows an X-ray CT measurement chart of the porous sintered sheet of Comparative Example 1.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail. In addition, this invention is not limited to the following this embodiment, It can variously deform and implement within the range of the summary.

[Porous Sintered Sheet]

The porous sintered sheet of this embodiment is a porous sintered sheet containing a resin and having continuous pores, wherein the minimum value of the cross-sectional porosity of the porous sintered sheet is 10% or more, and the position where the minimum value of the cross-sectional porosity exists is It is within 20% of the depth in the thickness direction from one surface (for example, the surface or the surface opposite to the surface) of a sintered sheet|seat. Thereby, the porous sintered sheet of this embodiment is excellent in gas or liquid permeability, mechanical strength is large, and it is excellent in durability over a long period of time because a pressure loss is small.

The resin constituting the porous sintered sheet (eg, porous sheet) may be either a thermoplastic resin or a thermosetting resin. Examples of the thermoplastic resin include polyolefin resin, polyester resin, polyarylate, liquid crystal polyester, polyvinyl chloride, polyvinyl alcohol, polystyrene, acrylonitrile-butadiene-styrene copolymer resin, and acrylonitrile-styrene copolymer resin. , polymethyl methacrylate, polyamide-based resin, polyacetal, polycarbonate, fluorine-based resin, polyetheretherketone, polyethersulfone, polyphenylenesulfide, and the like. Moreover, as a thermosetting resin, a phenol resin, a urea resin, a melamine resin, an allyl resin, an epoxy resin, etc. are mentioned. These resins can be used individually by 1 type or in combination of 2 or more type.

Among these, a thermoplastic resin is preferable from a viewpoint of being excellent in shaping property and secondary workability. Among the thermoplastic resins, polyolefin-based resins such as polyethylene and polypropylene are preferable from the viewpoint of being inexpensive and excellent in chemical resistance and workability, and low hygroscopicity and low water absorption of the material. Examples of the polyolefin-based resin include a homopolymer of ethylene or an ethylene-based copolymer of ethylene and one or more α-olefin-based monomers such as propylene, butene-1, hexene-1, and octene-1, ethylene, and vinyl acetate and acrylic acid. , ethylenic copolymer with non-α-olefin monomers such as methacrylic acid, acrylic acid ester, and methacrylic acid ester, propylene homopolymer, or propylene with one or more α-olefinic monomers such as ethylene and butene-1 of propylene-based copolymers, and the like.

Among the polyolefin resin particles, polyethylene particles are most preferable from the viewpoints of being inexpensive, easy to sinter and molded, excellent in processability and chemical resistance after molding, and low hygroscopicity and water absorption of the material itself.

It is preferable that the density of resin (for example, a thermoplastic resin, especially polyethylene) is 890-970 kg/m<^3>. When the density is 890 kg/m ³ or more, there exists a tendency that still more sufficient rigidity can be provided to a porous sintered sheet (for example, a porous sheet). In view of the same, the density, it is more preferred, and 940kg / m ³ or more or more preferably, 930kg / m ³ more preferably greater than 920kg / m ^3. Moreover, when a density is 970 kg/m<^3> or less, there exists a tendency which is excellent in handling easiness further. From a similar viewpoint, it is more preferable that a density is 960 kg/m<^{3> or less.}

The density of resin can be adjusted by adjusting the quantity of each copolymer component of a different kind, adjusting molecular weight, or mixing two or more types of copolymer components from which it is the same kind but different in density. For example, when the resin is polyethylene, the density of the polyethylene may be adjusted by controlling the amount of another monomer copolymerized with ethylene (eg, α-olefinic monomer), controlling the molecular weight, or two or more polyethylenes having different densities. It can be adjusted by mixing. In addition, the density of polyethylene can be measured by the density gradient pipe method (23 degreeC) based on JISK7112:1999.

In addition, the resin (for example, a thermoplastic resin, particularly polyethylene) has little flow of the resin, which is a factor that inhibits the formation of voids during sintering molding, and is excellent in fusion properties of adjacent resin particles, from the viewpoint of viscosity, It is preferable that average molecular weights are 10-10 million, It is more preferable that it is 10,000 or more, More preferably, it is 100,000 or more.

The viscosity average molecular weight (Mv) of the resin particles (eg, thermoplastic resin particles, particularly polyethylene particles) can be controlled by appropriately adjusting polymerization conditions and the like. Specifically, the viscosity average molecular weight can be adjusted by adding hydrogen to the polymerization system or changing the polymerization temperature.

A viscosity average molecular weight can be calculated|required by the method shown below, for example. First, a resin (for example, polyethylene) is dissolved in decalin (decahydronaphthalene) to prepare a plurality of solutions having different concentrations. The reduced viscosity (ηsp/C) of each of these solutions is determined in a constant temperature bath at 135°C using an Uvelode type viscometer. A linear expression between the concentration (C) and the reduced viscosity (ηsp/C) of the polymer is derived, and the intrinsic viscosity ([η]) extrapolated to the concentration 0 is obtained. From this intrinsic viscosity ([η]), the viscosity average molecular weight (Mv) can be calculated according to the following formula.

Mv=5.34×10 ⁴ ×[η] ^1.49

The porous sintered sheet (eg, porous sheet) may be a mixed raw material of the same type of resin (eg, polyethylene) in which the resin as a raw material differs in density and/or viscosity average molecular weight, or may be mixed with a different type of resin. It may be a raw material.

These resins (for example, polyolefin resin) may be made hydrophilic by copolymerizing with the monomer which has a hydrophilic group, graft copolymerizing with the monomer which has a hydrophilic group, or adding surfactant. In addition, the hydrophilicization may be carried out by molding a hydrophilic product in the form of a powder into a porous body to obtain a hydrophilic porous sintered sheet, or may be hydrophilicized by a known method in a previously molded porous sintered body. The "hydrophilicization" as used in the present invention refers to a state in which, for example, when about 50 microliters of water droplets are dropped on a molded article, the water droplets are absorbed into the molded article within 30 seconds.

[Method for producing porous sintered sheet]

As a method of manufacturing the porous sintered sheet of this embodiment, a well-known method is used. As a known method, for example, a method such as a sintering molding method is mainly used, but in other cases, for example, a molded body is molded with a resin melted together with an extractable component, and then the extractable component is extracted to form a porous mass with open pores. A method of forming a sintered sheet is also used. As a specific example of the sintering molding method, a mold is filled with a raw material (for example, a powdery resin), put into a heating furnace maintained at a temperature above the melting point, and sintered, and then cooled, even if the molded body is taken out from the mold, continuous pores are formed. A porous sintered sheet can be formed.

The method for producing the sheet-like porous sintered body is not particularly limited, and the sintering molding method in a mold, the extrusion molding method, or the porous sintered body molded using the above-described molding method is sliced or skived to form a sheet. The method and the like are suitably used.

In particular, it is preferable from the viewpoint of excellent continuous productivity and flexibility in thickness to supply (deposit) a raw material resin on an endless conveyor belt, mold (shape) into a sheet, and then heat to produce a sheet-like porous sintered body. do.

In addition, "continuous pores" as used herein means that pores are continuous from one surface to the other surface of the molded article. These pores may be linear or curved. Further, the size of the pores may be changed, for example, between the surface layer and the inside, or between one surface layer and the other surface layer.

The porous sintered sheet obtained by the above-described various forming methods may be further compressed by a pressing means. In more detail, a porous sintered sheet may be pinched|interposed on a press plate, and you may press-compress, and you may press-compress with a press roller, the pressurization apparatus of an endless conveyor belt, etc. It is preferable that the temperature at the time of pressurization exists in the temperature range of melting|fusing point +/-30 degreeC. When the melting point is higher than 30°C than the melting point, curing of the resin particles has already started and the effect of pressure compression is not obtained. There is a possibility that the pore may become damaged, and there is a possibility that the pores on one side (for example, the surface) may become broken. 0.5 % or more and 2 % or less are preferable with respect to the thickness before compression, and, as for the compressibility in the case of press-compressing a porous sintered sheet, 0.7 % or more and 1 % or less are still more preferable. When the compressibility is less than 0.5%, the surface powder fallability and abrasion resistance are inferior, and when it is 2% or less, the porous sintered sheet of the present embodiment tends to have further excellent transmittance (eg, air permeability). The compression ratio here refers to the ratio obtained by dividing the value obtained by subtracting the final thickness from the original thickness by the original thickness.

When a porous sintered sheet is obtained by sintering molding, the raw material resin is suitably used in a powdery form. In this case, in the porous sintered sheet, in order to obtain sufficient mechanical strength and appropriate rigidity while having sufficient permeability (eg, air permeability), the average particle diameter of the raw resin is preferably 10 to 300 µm, and 20 to 250 It is more preferable that it is micrometer, It is still more preferable that it is 30-200 micrometers, It is 50-180 micrometers especially. The average particle diameter of the raw material resin is the particle diameter at which the cumulative weight becomes 50%, that is, the median diameter. Using a laser diffraction particle size distribution analyzer (“SALD-2100” manufactured by Shimadzu Corporation), methanol was It can be obtained by measuring as a dispersion medium.

"Cross-section porosity" means the porosity of a cross-section parallel to the surface of a porous sintered sheet. The cross-sectional porosity can be measured using an X-ray CT apparatus. From one surface of the porous sintered sheet, a cross-sectional image is obtained for each step in the thickness direction, and can be obtained by binarizing the void image of each layer. By this method, a profile of the cross-sectional porosity in the thickness direction of the porous sintered sheet can be obtained.

The average porosity is an average value of the cross-sectional porosity of all layers, and the thickness of the porous sintered sheet is directed to the opposite side from the first measurement point at which the porosity is 100% (state not in contact with the porous sintered sheet) or less in X-ray CT measurement. It refers to the distance to the last measurement point before exceeding 100%.

The position where the minimum value of the cross-sectional porosity of the porous sintered sheet in this embodiment exists is within 20% of the depth in the thickness direction from one side of the sintered sheet, Preferably it is within 18%, More preferably, it is 16% is within Usually, in a porous sintered sheet, the porosity gradually decreases as it deepens in the thickness direction from one surface, and after it becomes a substantially constant porosity at a certain depth, near the center of the thickness (depth 50% in the thickness direction from one surface) ) tends to have the smallest porosity. On the other hand, in the porous sintered sheet of the present embodiment, the porosity gradually decreases as it deepens in the thickness direction from one surface, and the porosity becomes the minimum within 20% of the depth in the thickness direction from the one surface, and as it becomes deeper, , the porosity increases, and after that, it becomes a substantially constant porosity. When the minimum value of the porosity exists within 20% of the depth in the thickness direction from one surface, for example, powdery resin (eg, powder, etc.) lacking in the porous sintered sheet tends to be difficult to be released to the outside. Moreover, when using the porous sintered sheet of this embodiment as a filter or a suction conveyance board, even if an object passing through the hole of the porous sintered sheet becomes clogged by the hole, the pressure loss can be made small. Moreover, the mechanical strength of one side of the porous sintered sheet is excellent, and the one side is hard to be chipped, crushed, or deformed with respect to an external stress. For this reason, over a long period of time, permeability (for example, air permeability) and filtration ability can be maintained, and there exists a tendency for scum to be hard to generate|occur|produce.

In general, in the mold method in which the raw material powder is filled in a mold, put into a heating furnace maintained at a temperature above the melting point, and sintered, the raw resin (for example, powdery resin) expands during heating, but due to the presence of the mold become compressed. In the die method, the porous sintered sheet is gradually cooled by air cooling after heating.

On the other hand, it does not specifically limit as a method of producing the porous sintered sheet|seat in which the minimum value of a porosity exists within 20% of depth in the thickness direction from one surface of this embodiment. After depositing the raw material resin on the endless conveyor belt, it is preferable to heat and sinter it, and to press it by pinching|inserting after that on a press plate. Thickness from one side of the porous sintered sheet by a method such as adjusting the resin temperature at the time of heat sintering to 180°C to 230°C, and setting the temperature at the time of compression to ±30°C with respect to the melting point of the resin It can be adjusted so that a minimum value of porosity exists within 20% of the depth of the direction.

In the porous sintered sheet of the present embodiment, the minimum value of the cross-sectional porosity is, for example, 10% or more and 40% or less, preferably 12% or more and 38% or less, and more preferably 15% or more and 36% or less. When the minimum value of the cross-sectional porosity is 10% or more, sufficient permeability (for example, air permeability and water permeability) can be provided. On the other hand, when the minimum value of a cross-sectional porosity is 40 % or less, it is excellent in mechanical strength and can obtain the porous sintered sheet excellent in filtration precision.

The average porosity of the entire porous sintered sheet of the present embodiment is preferably 20% or more and 80% or less, more preferably 25% or more and 75% or less, and still more preferably 30% or more and 70% or less. When the average porosity is 20% or more, the porous sintered sheet of the present embodiment can further secure the space in the porous sintered sheet required for gas or liquid to pass through or hold, and the mechanical strength is further excellent, Durability tends to be more excellent. On the other hand, when the average porosity is 80% or less, the porous sintered sheet of the present embodiment tends to have further excellent mechanical strength. As a method of adjusting the average porosity to 20% or more and 80% or less, it can be controlled by adjusting the average particle diameter of the resin particles, the firing temperature at the time of producing the molded article, the firing time, the compression temperature, the compression pressure, the compression time, and the like. The "average porosity" as used herein means the average value of the cross-sectional porosity of all the layers measured by X-ray CT.

The porous sintered sheet of the present embodiment is characterized in that a porous sintered sheet having a different pore structure in the depth direction is obtained without bonding or the like. When the sheet|seat of a different structure is bonded together with an adhesive etc., the porosity of an adhesion layer is extremely different, and the position with a porosity extremely lower than the overall average porosity exists in the depth direction.

In the depth of the porous sintered sheet of this embodiment in the thickness direction from one surface, it is deeper than the depth position reaching the average porosity of the entire porous sintered sheet, and there is a depth position having a cross-sectional porosity 20% or more larger than the average porosity. It is preferable not to Thereby, the porous sintered sheet|seat which has a structure with a dense surface layer part without interposing the adhesive layer which becomes a cause of peeling is obtained.

The porous sintered sheet of this embodiment WHEREIN: It is preferable that each division obtained by dividing the ^{said porous sintered sheet of 1 m<2>} or more into 100 cm<^{2> or less satisfy|fills the following condition A.}

(Condition A)

X≤Y×0.2

X: the difference between the depth position where the minimum value of the cross-sectional porosity exists and the depth position where the maximum value of the cross-sectional porosity exists

Y: thickness of the compartment

By satisfying the condition A, the porous sintered sheet becomes a more uniform sheet, and problems such as different liquid and gas permeability depending on the location and the inability to perform uniform suction chuck or filtration are further reduced. From a similar viewpoint, it is more preferable that X is Yx0.1 or less, and it is still more preferable that it is Yx0.05 or less.

The difference between the average porosity of the entire porous sintered sheet in the present embodiment and the minimum value of the cross-sectional porosity of the porous sintered sheet is, for example, 10% or more and 50% or less, preferably 12% or more and 40% or less, more Preferably it is 15 % or more and 30 % or less. When the difference between the minimum value of the average porosity and the cross-sectional porosity is 10% or more, a porous sintered sheet having excellent mechanical strength and excellent filtration accuracy can be obtained. On the other hand, when the difference between the minimum value of the average porosity and the cross-sectional porosity is 50% or less, the gas or liquid permeability is excellent and the pressure loss tends to be small.

As a method of making the difference between the minimum value of the average porosity and the cross-sectional porosity 10% or more, the minimum value of the porosity within 20% of the depth in the thickness direction from one surface of the porous sintered sheet can be adjusted by the same method as the method. .

The product of the air permeability and the thickness of the porous sintered sheet in the present embodiment is 0.2 cm ³ /cm/sec or more, preferably 0.3 cm ³ /cm/sec or more (for example, 0.3 to 1.0 cm ³ /cm/sec) ), and more preferably 0.4 cm ³ /cm/sec or more. When the product of the air permeability and the thickness is 0.2 cm ³ /cm/sec or more, the porous sintered sheet of the present embodiment is further excellent in permeability (for example, air permeability and water permeability), and excellent in durability due to excellent mechanical strength. tends to In addition, the air permeability can be measured using the air permeability measuring instrument ("FX3360PORTAIR" by TEXTEST company) ^{under the conditions of a measurement range of 20 cm<2>} , and the measurement differential pressure|voltage of 125 Pa.

The thickness of the porous sintered sheet of this embodiment becomes like this. Preferably they are 0.05 mm or more and 5 mm or less, More preferably, they are 0.1 mm - 3 mm, More preferably, they are 0.2 mm - 2 mm. When the thickness is within the above range, the porous sintered sheet of the present embodiment is further excellent in self-support and handleability, is further excellent in permeability (for example, air permeability and water permeability), and further excellent in filtration accuracy. tends to

The surface roughness Ra of the porous sintered sheet of the present embodiment is preferably 0.1 µm or more and 20 µm or less, more preferably 0.1 µm or more and 10 µm or less, and still more preferably 0.1 µm or more and 5 µm or less. When the surface roughness is within the above range, when the porous sintered sheet of the present embodiment is used as an adsorption cushioning material, it is possible to further prevent the occurrence of scratches and contact marks on the member to be adsorbed. The method for adjusting the surface roughness (Ra) of the porous sintered sheet within the above range is not particularly limited, and a method for producing a porous sintered sheet by a deposition method, a method for press-molding the obtained porous sintered sheet, and the obtained porous sintered sheet cutting method, etc. are mentioned. Further, when the minimum value of the cross-sectional porosity exists within 20% of the depth in the thickness direction from the surface of the porous sintered sheet, the surface has a dense structure and the surface roughness tends to decrease. In addition, the surface roughness (Ra) was measured using a stylus type surface roughness meter ("Handy Surf E-35B" manufactured by Tokyo Seimitsu Co., Ltd.), tip diameter R: 5 µm, speed: 0.6 mm/s, measurement length: Measurement can be performed under the conditions of 12.5 mm, cut-off value λc: 2.5 mm, and number of measurements: n=5.

[purpose]

The porous sintered sheet of the present embodiment has excellent air permeability and, for example, has a dense structure near the surface and has a small surface roughness, so it can be suitably used as an adsorption buffer material. The adsorption buffer material is a means for fixing or transporting a thin film, plate, or film, such as a sheet for adsorption and fixed transport, a sheet for a support of a rapid test kit by immunochromatographic method, a glass plate for liquid crystal or a sheet for a multilayer ceramic capacitor. As one method, there is a method of adsorption fixing or adsorption conveyance in the adsorption stage in the reduced pressure suction, but it is attached to the adsorption surface of this adsorption stage.

A ceramic green sheet is mentioned as a thin film. Ceramic green sheets are usually prepared by mixing ceramic powder, binders (acrylic resins, butyral resins, etc.), plasticizers (phthalic acid esters, glycols, adipic acid, phosphoric acid esters) and organic solvents (toluene, MEK, acetone, etc.). A ceramic coating material is prepared, and the ceramic coating material is applied on a carrier sheet by a doctor blade method or the like, and dried by heating.

Moreover, it can be used as a filter medium with high filtration efficiency at the point which has a dense structure in the vicinity of one surface and air permeability as a whole is high.

Example

Next, although an Example and a comparative example are given and this embodiment is demonstrated more concretely, this embodiment is not limited to the following example, unless the summary is exceeded.

The measurement of each physical property of each material was performed as follows.

(1) section porosity

Using an X-ray CT device (micro-focus X-ray CT system HPCinpeXioSMX-225CT: manufactured by Shimadzu Corporation), the X-ray conditions were 160 kV/40 μA, no metal filter, and the imaging conditions were 1200 sheets/360 at an exposure time equivalent to 0.33 seconds. A three-dimensional structure of a porous sintered sheet was obtained with a spatial resolution of 5 µm/pix at an image size of 1024×1024 pix by ° rotation. From one surface of the porous sheet, cross-sectional images were obtained for each step in the thickness direction, and the voids in each layer were binarized by Otsu's method of the image to determine the cross-sectional porosity. By this method, a profile of the porosity in the thickness direction of the porous sintered sheet (for example, FIG. 1 ) can be obtained, and the average of the cross-sectional porosity of all layers becomes the average porosity of the entire porous sintered sheet.

(2) Surface roughness (Ra)

Surface roughness (Ra) was measured using a stylus type surface roughness meter ("Handy Surf E-35B" manufactured by Tokyo Seimitsu Co., Ltd.), tip diameter R: 5 µm, speed: 0.6 mm/s, measurement length: It measured under the conditions of 12.5 mm and cut-off value (lambda)c: 2.5 mm. As for the measurement position, when the center of the surface of the object to be measured was divided into 4 equal parts, and the surface was divided into equal parts, a total of 5 points were measured at each center of the quartered surface.

(3) air permeability

The measurement of the air permeability was measured using the air permeability measuring device ("FX3360PORTAIR" manufactured by TEXTEST) ^{under the conditions of a measurement range of 20 cm 2} and a measurement differential pressure of 125 Pa.

(4) thickness

In the measurement of the thickness of the porous sintered sheet, the distance from the first measurement point at which the porosity becomes 100% or less in the X-ray CT measurement to the last measurement point before exceeding 100% toward the opposite side was defined as the thickness.

(5) Powder fallability evaluation

For evaluation of the powder fallability of the polyolefin porous sintered sheet, one polyolefin porous sintered sheet having a size of 200 mm x 200 mm was applied to a paper of a color opposite to the color of the raw material particles of the polyolefin porous sintered sheet by applying a vibrator (“Vibe” manufactured by Shingo Denki Co., Ltd.). After applying vibration for 2 minutes using "Ray Repica VP-15D"), it was visually confirmed whether or not raw material particles were present on the paper of the opposite color, and evaluation was performed based on the following criteria.

(circle): There was almost no drop-off|omission of raw material powder.

x: There were many drop-off|omission of raw material powder.

(6) Pressure loss evaluation

The pressure loss was measured by the filtration rate and the silica content in the filtrate when the silica dispersion was suction-filtered using the porous sintered sheet as a filter filter. Using a glass filter folder KG-47 (manufactured by Tokyo Glass Kikai Co., Ltd.), the porous sintered sheet was cut out according to the folder size, attached to the folder, and clamped. The pressure was reduced to -40 kPa with an aspirator, 1 L of silica dispersion Snowtex MP-4540M (manufactured by Nissan Chemical Industry Co., Ltd.) was poured, and the time required for water to pass was measured. Next, content of silica in the filtrate was calculated|required by measuring dry weight, and it evaluated based on the following criteria.

(double-circle): It passed in less than 20 seconds.

○: passed in 20 seconds or more and less than 40 seconds.

x: It passed in 40 second or more. Or even if it passed in less than 40 second, silica content had become 50% or more of content before filtration.

(7) Evaluation of the scratch resistance of the surface of the porous sintered sheet

Using #0000 steel wool, the surface of the porous sintered sheet was rubbed 50 reciprocally under a load of 100 g, the occurrence of cutting chips was observed, and evaluation was performed based on the following criteria.

(circle): There was little generation|occurrence|production of cutting debris, and the long diameter of cutting debris was 1 mm or less.

x: There was a large amount of chips generated, and there were chips having a long diameter of 1 mm or more.

[Example 1]

0.3 parts by weight of polyoxysorbitan monolaurate was added to 100 parts by weight of ultra-high molecular weight polyethylene having a viscosity average molecular weight (Mv) of 400,000, an average particle diameter of 95 μm, a bulk density of 0.53 g/cc, and a melting point of 136° C. , and mixed with a blender. The ultra-high molecular weight polyethylene composition was put into a hopper and supplied. The supplied resin was deposited to a thickness of 0.505 mm on a metal endless conveyor belt rotating at a moving speed of 10 cm/min. It was then passed through a heating zone set at 200° C. over 10 minutes. The resin temperature at the outlet of the heating zone was 190°C. After passing through the heating zone, it peeled off from the endless conveyor belt 15 seconds later, air-cooled from both sides, and wound up on a roll to obtain the original fabric of a porous sintered sheet. Next, the original fabric of the porous sintered sheet was cut to an appropriate size, and press-pressed at 140° C. with a mold frame thickness of 0.500 mm for 90 seconds under the conditions of 1 MPa to obtain a porous sintered sheet with a thickness of 0.501 mm. Table 1 shows the properties of the porous sintered sheet. Also, the profile of the cross-sectional porosity is shown in FIG. 1 .

In addition, 100 sheets cut in a 10 cm square were prepared, and the positions in the depth direction showing each minimum porosity were measured. The maximum value was 0.075 mm and the minimum value was 0.055 mm, and the difference was 4% of the total thickness became a uniform sheet throughout.

[Example 2]

The thickness was the same as in Example 1, except that the supplied resin was deposited to a thickness of 0.121 mm on a metal endless conveyor belt rotating at a moving speed of 9 cm/min and pressurized to a mold frame thickness of 0.120 mm. A porous sintered sheet of 0.120 mm was obtained. Table 1 shows the properties of the porous sintered sheet.

[Example 3]

A porous sintered compact having a thickness of 0.501 mm was carried out in the same manner as in Example 1, except that ultra-high molecular weight polyethylene having a viscosity average molecular weight (Mv) of 1 million, an average particle diameter of 50 µm, a bulk density of 0.50 g/cc, and a melting point of 136°C was used. got Table 1 shows the properties of the porous sintered sheet.

[Example 4]

A porous sinter of 0.500 mm in thickness was carried out in the same manner as in Example 1, except that ultra-high molecular weight polyethylene having a viscosity average molecular weight (Mv) of 3 million, an average particle diameter of 50 µm, a bulk density of 0.33 g/cc, and a melting point of 136°C was used. got a sheet Table 1 shows the properties of the porous sintered sheet.

[Example 5]

Example 1 except that ultra-high molecular weight polyethylene having a viscosity average molecular weight (Mv) of 5 million, an average particle diameter of 80 µm, a bulk density of 0.49 g/cc, and a melting point of 136°C was used, and deposited to a thickness of 0.101 mm A porous sintered sheet having a thickness of 0.100 mm was obtained in the same manner as described above. Table 1 shows the characteristics of the porous sintered body.

[Comparative Example 1]

Using the resin used in Example 1, the aluminum mold adjusted to a clearance of 0.510 mm was filled with the resin while vibration was applied with a vibrator for 30 seconds, heated and cooled until the mold temperature reached 180 ° C., and then released. A porous sintered sheet having a thickness of 0.506 mm was obtained. Table 1 shows the properties of the porous sintered sheet. Also, the profile of the cross-sectional porosity is shown in FIG. 2 .

[Comparative Example 2]

Using the resin used in Example 5, a mesh-shaped cylindrical mold (inner diameter 250 mm, height 500 mm) was filled, and the resin was filled while applying vibration with a vibrator for 30 seconds. This was put in a pressure-resistant container, water vapor (160 degreeC, 8 atmospheres) was introduce|transduced, it heat-sintered for 10 hours, and left it to stand at room temperature of 25 degreeC after that, and it cooled. A porous sintered sheet having a thickness of 0.101 mm was obtained by cutting the obtained cylindrical porous sintered compact block. Table 1 shows the properties of the porous sintered sheet.

[Comparative Example 3]

Using the resin used in Example 1, it was deposited on a metal endless conveyor belt so as to have a thickness of 0.140 mm, and was subjected to pressurization to a mold frame thickness of 0.120 mm, except that it was carried out in the same manner as in Example 1, and porous sintered to a thickness of 0.120 mm. got a sheet Table 1 shows the properties of the porous sintered sheet.

[Comparative Example 4]

Using the resin used in Example 1, except having adjusted the pressure press temperature to 180 degreeC, it carried out similarly to Example 1, and obtained the porous sintered sheet|seat. Table 1 shows the properties of the porous sintered sheet.

[Comparative Example 5]

A porous sintered sheet having a thickness of 0.503 mm was obtained by press-pressing the porous body obtained in Comparative Example 1 at 95°C with a die frame thickness of 0.500 mm under the conditions of 1 MP for 90 seconds. Table 1 shows the properties of the porous sintered sheet.

[Comparative Example 6]

A porous sintered sheet having a thickness of 0.505 mm was obtained in the same manner as in Example 1 except that the resin used in Example 1 was used and press-pressed to a mold frame thickness of 0.505 mm. Table 1 shows the properties of the porous sintered sheet.

[Comparative Example 7]

A porous sintered sheet having a thickness of 0.505 mm was obtained in the same manner as in Example 1 except that the resin used in Example 1 was used and pressure pressing was not performed. Table 1 shows the properties of the porous sintered sheet.

[Comparative Example 8]

The porous sintered sheet obtained in Comparative Example 4 was adhered to the porous sintered sheet obtained in Comparative Example 3 with a spray adhesive (spray adhesive 55 manufactured by 3M) so that the adhesive layer had a thickness of 0.001 mm, and had an average porosity of 30% and a thickness of 0.621 mm. A laminated porous sheet was obtained. The depth at which the average porosity of the laminated porous sheet is reached is at a position of 8% of the total thickness (depth of 0.05 mm) from the sheet side on which Comparative Example 3 is laminated, and at a position of 20% of the total thickness (depth of 0.125 mm) ), the porosity was 69.3%. The laminated porous sheet could not be evaluated because the pressure-sensitive adhesive layer was peeled off during pressure loss evaluation.

The porous sintered sheet of the present invention has industrial applicability as a filter, an adsorption buffer material, an adsorption fixed transport material, an air diffuser, a liquid guide and holding material, a support material, and the like in the field of electronics and medical related fields.

This application is based on the Japanese patent application (Japanese Patent Application No. 2017-093107) for which it applied on May 9, 2017, The content is taken in here as a reference.

Claims (12)

A porous sintered sheet containing a polyethylene resin having a viscosity average molecular weight (Mv) of 100,000 to 10 million and having continuous pores, the porous sintered sheet comprising:
The minimum value of the cross-sectional porosity of the porous sintered sheet is 15% or more, and the position where the minimum value of the cross-sectional porosity exists is within 20% of a depth in the thickness direction from one surface of the sintered sheet. The porous sintered sheet according to claim 1, wherein the difference between the average porosity of the entire porous sintered sheet and the minimum value of the cross-sectional porosity of the porous sintered sheet is 10% or more and 50% or less. The porous sintered sheet according to claim 1, wherein the product of the ventilation amount of the porous sintered sheet and the thickness of the porous sintered sheet is 0.2 cm ³ /cm/sec or more. The porous sintered sheet according to claim 1, wherein an average porosity of the entire porous sintered sheet is 20% or more and 80% or less. The depth position according to claim 1, wherein, at a depth in the thickness direction from the one surface, a depth position having a cross-sectional porosity that is deeper than the average porosity of the entire porous sintered sheet and 20% or more larger than the average porosity exists. Not a porous sintered sheet. The porous sintered sheet according to claim 1, wherein each section obtained by dividing the porous sintered sheet of ^{1 m 2 or more into 100 cm 2} or less satisfies the following condition A.
(Condition A)
X≤Y×0.2
X: the difference between the depth position where the minimum value of the cross-sectional porosity exists and the depth position where the maximum value of the cross-sectional porosity exists
Y: thickness of the compartment The porous sintered sheet according to claim 1, wherein the porous sintered sheet has a thickness of 0.05 mm or more and 5.0 mm or less. A method for producing a sheet-like porous sintered sheet according to any one of claims 1 to 7, by supplying a resin onto an endless conveyor belt, forming a sheet-like molded body, and then heating and pressurizing the molded body. The method for producing a porous sintered sheet according to claim 8, wherein after heating the molded body, the heated molded body is compressed by a pressing means within a temperature range of ±30°C of the melting point of the resin. The method for producing a porous sintered sheet according to claim 9, wherein the compression ratio compressed by the pressing means is 0.5% or more and 2% or less. The sheet for adsorption|suction fixed conveyance which has the porous sintered sheet|seat in any one of Claims 1-7. A sheet for a support for a rapid test kit by immunochromatographic method, comprising the porous sintered sheet according to any one of claims 1 to 7.

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