JP6659389B2 - Polyolefin porous sintered compact - Google Patents

Description

  The present invention relates to a polyolefin porous sintered compact.

  One of the means for fixing or transporting thin-film, plate-like, or film-like objects such as glass sheets for liquid crystal or green sheets for multilayer ceramic capacitors. Alternatively, there is a method of carrying by suction. On the suction stage, a porous resin body having air permeability as a suction buffer material is mounted on the suction surface. Accordingly, it is possible to prevent scratches and contact marks from being generated on the member to be attracted. As such a resin porous sintered compact, a sintered compact obtained by sintering polyethylene powder may be used from the viewpoint of rigidity and cushioning properties.

  In recent years, miniaturization and high performance of liquid crystals and multilayer ceramic capacitors have been rapidly advancing, and the thickness of glass plates and ceramic green sheets, which are the raw materials thereof, has been advanced. For this reason, it is necessary to perform very precise suction fixing or suction conveyance. Therefore, it is desired that the suction buffer material to be mounted on the suction stage for suction under reduced pressure has a uniform surface height, hardness, and pressure applied by suction, in contact with the member to be sucked. Furthermore, from the economical point of view, there is a demand for a material having a small pressure loss and durability even when dust or the like is sucked.

  In response to such a requirement, for example, Patent Document 1 proposes an air cleaner filter made of ultrahigh molecular weight polyethylene as a porous sheet having a small pressure loss. In addition, for example, in Patent Document 2, a sheet for adsorption and fixing having a small surface roughness is obtained by a method of cutting a block-shaped porous sintered compact obtained by sintering fine ultra-high molecular weight polyethylene particles. Has been proposed.

  On the other hand, as a hydrophilic porous sintered compact mainly composed of hydrophilized polyolefin, utilizing its water absorption function, it is used for applications such as water absorption, diffusion, divergence, permeation, induction, and the like. Patent Literature 3 proposes uses of a dew-water absorbing material and a humidifier in a refrigerator, a humidifying element such as an air conditioner, an ink absorbing material of a printer, and the like in a vegetable room or a chilled room of a refrigerator.

  In recent years, porous sintered compacts have also been used in the electronics field, medical-related fields, and the like, and there is a demand for more precisely controlled porous sintered compacts. In the field of electronics, for example, Patent Document 4 proposes a clean, thin-walled uniaxially stretched ultrahigh molecular weight polyethylene having a defined porosity and average pore diameter. In the medical-related field, for example, Patent Document 5 proposes an ultra-high molecular weight polyethylene porous sintered compact having a pore size suitable for filtering a collected specimen.

JP 2006-257888 A JP 2006-26981 A Patent No. 1739911 JP 2000-317280 A JP 2015-14618 A

  However, with the techniques described in Patent Documents 1 to 3, although it is possible to make the porous sheet thinner, the mechanical strength and durability when the porous sheet is made thinner tend to be low. In addition, the effect of suppressing the ventilation rate and pressure loss is insufficient. Further, in the techniques described in Patent Documents 4 and 5, filtration of a solution using a porous sintered compact having hydrophilicity is described. However, there is a variation in performance in a sheet, and a ventilation performance and a water absorption function are provided. There is a need for improvements.

  The present invention has been made in view of the above-mentioned problems of the related art, and provides a polyolefin porous sintered body that can ensure high water absorption performance, has low pressure loss, and has excellent durability. The purpose is to do.

  The present inventors have conducted intensive studies to solve the above problems, and as a result, by controlling the pore size distribution, it is possible to secure a high level of ventilation performance and water absorption performance even in a thin film. The present inventors have found that a polyolefin porous sintered compact having low pressure loss and excellent mechanical strength and durability can be obtained, and the present invention has been completed.

That is, the present invention is as follows.
[1]
Including polyolefin particles composed of polyolefin,
The thickness is 0.05 to 1 mm,
A polyolefin having a median pore diameter distribution with a D10 / D90 ratio of 10 or less, where D10 and D90 are median pore diameters corresponding to 10% and 90%, respectively, from the larger diameter side of the cumulative pore distribution. Porous sintered compact.
[2]
The polyolefin according to [1], having a pore volume of 0.1 cm ³ / g or more and 2.0 cm ³ / g or less, a median pore diameter of 1 μm or more and 15 μm or less, and having continuous pores. Porous sintered compact.
[3]
The porous sintered polyolefin product according to [1] or [2], wherein the aluminum content is 1 ppm or more and 30 ppm or less.
[4]
The polyolefin porous sintered compact according to any one of [1] to [3], wherein the chlorine content is 10 ppm or less.
[5]
The porous polyolefin sintered compact according to any one of [1] to [4], wherein the thickness is 0.1 to 0.8 mm.
[6]
The polyolefin porous sintered compact according to any one of [1] to [5], wherein the polyolefin is a homopolymer of ethylene, or a copolymer of ethylene and an olefin having 3 or more carbon atoms. .
[7]
The porous sintered compact according to any one of [1] to [6], wherein the polyolefin has a viscosity average molecular weight of 500,000 to 10,000,000.
[8]
The polyolefin according to any one of [1] to [7], wherein the polyolefin is a polyolefin obtained by grafting at least one kind of molecular chain selected from a hydrophilic ethylenically unsaturated group-containing monomer or a polymer thereof. Porous sintered compact.
[9]
A method for producing a polyolefin porous sintered compact according to any one of [1] to [8],
A method for producing a polyolefin porous sintered compact, comprising a step of performing sinter molding by filling the polyolefin particles in a mold.
[10]
A method for producing a polyolefin porous sintered compact according to any one of [1] to [8],
A method for producing a porous polyolefin sintered compact, comprising a step of performing sinter molding by depositing the polyolefin particles.
[11]
A laminate comprising: the polyolefin porous sintered compact according to any one of [1] to [8]; and a substrate on which the polyolefin porous sintered compact is laminated.
[12]
A sheet for adsorption and fixing conveyance, comprising the polyolefin porous sintered compact according to any one of [1] to [8] or the laminate according to claim 11.
[13]
A sheet for a support of a rapid inspection kit by an immunochromatography method, comprising the polyolefin porous sintered compact according to any one of [1] to [8] or the laminate according to claim 11.

  ADVANTAGE OF THE INVENTION By this invention, a high water absorption performance can be ensured, a pressure loss is small, and the polyolefin porous sintered compact excellent in durability can be implement | achieved.

3 shows a chart of the median pore diameter distribution and the cumulative median pore diameter of the porous sintered polyolefin product of Example 1 obtained by mercury porosimetry.

  Hereinafter, a mode for carrying out the present invention (hereinafter, simply referred to as “the present embodiment”) will be described in detail. The following embodiment is an example for describing the present invention, and is not intended to limit the present invention to the following contents. The present invention can be implemented with various modifications within the scope of the invention.

  The polyolefin porous sintered compact of the present embodiment contains polyolefin particles composed of polyolefin, has a thickness of 0.05 to 1 mm, and has a 10% cumulative and 90% cumulative from the larger diameter side of the cumulative pore distribution. Assuming that the corresponding median pore diameters are D10 and D90, the median pore diameter distribution has a D10 / D90 ratio of 10 or less. With such a configuration, the polyolefin porous sintered compact of the present embodiment can ensure high air permeability and water absorption performance, has low pressure loss, and has excellent mechanical strength and durability.

  In general, a `` porous sintered compact '' is prepared by heating a powder of metal, ceramic, plastic, or the like under pressure or without pressure, and fusing the powder near the surface layer while leaving continuous pores inside. Includes the resulting porous sintered compact.

  The polyolefin porous sintered compact of the present embodiment may have continuous pores. In the present embodiment, the continuous pores mean pores that are continuous from one surface of the sintered body to another surface. The holes may be straight or curved. Further, the dimensions may be uniform over the entire surface, or may be, for example, those in which the size of pores is changed between the surface layer and the inside, or between one surface layer and the other surface layer. The fact that the polyolefin porous sintered compact of the present embodiment has the above-mentioned continuous pores can be confirmed, for example, by observing the cross section with a scanning electron microscope or the like.

  The thickness of the polyolefin porous sintered compact of the present embodiment is 0.05 mm or more and 1 mm or less. The thickness can be appropriately set according to the use or the like, but is preferably from 0.07 mm to 0.9 mm, more preferably from 0.1 mm to 0.8 mm. When the thickness is 0.05 mm or more, the mechanical strength is improved, and the film is not easily broken during use. Further, when the thickness is 1 mm or less, not only can air permeability in the thickness direction be improved, but also the polyolefin porous sintered compact can be wound into a roll, which is extremely effective in industry. . In addition, the thickness of the polyolefin porous sintered compact is obtained by cutting the porous sintered compact along the thickness direction, and using an optical microscope (“Microscope VH-Z100UR” manufactured by Keyence Corporation) using the cut surface. It can be measured by observation.

  In the polyolefin porous sintered compact of the present embodiment, the median pore distribution diameter range is narrow, and the pore diameters corresponding to the cumulative 10% diameter and the cumulative 90% diameter from the larger diameter side of the cumulative pore distribution are D10 and D10, respectively. When D90 is set, the D10 / D90 ratio is 10 or less, preferably 8 or less, and more preferably 6 or less. Note that, theoretically, the value of the D10 / D90 ratio does not become smaller than 1. When the D10 / D90 ratio is 10 or less, the pressure applied to the polyolefin porous sintered compact when gas or the like passes can be evenly dispersed, and not only deformation and breakage can be suppressed, but also durability can be improved. Can also be improved. Further, even if the polyolefin porous sintered compact is a thin film, effects such as improvement of mechanical strength and reduction of pressure loss at the time of pore closure are obtained. Furthermore, since the filtration performance is improved and the water absorption rate is also made uniform, the accuracy of the test using a rapid test kit by the immunochromatography method can be improved. The immunochromatography method is an immunoassay method utilizing the property (capillary phenomenon) that a sample slowly flows through a porous membrane while dissolving a reagent. The antigen in the sample moves through the porous membrane while forming an immune complex with the antibody (labeled antibody) prepared in advance at the sample dropping part, and the immune complex is trapped on the capture antibody prepared in advance on the porous membrane. This is a method of visually determining the color, which is applied to pregnancy diagnosis, influenza diagnosis and the like. The porous membrane is used for moving the developing solution containing the specimen by capillary action, and the polyolefin porous sintered compact of the present embodiment having a D10 / D90 ratio of 10 or less is used as the porous membrane. Thereby, unnecessary substances can be strictly removed, the necessary immune complex can be developed with a high probability, and even a small amount of antigen can be colored, thereby improving the test accuracy. it can. In addition, since the water absorption rate becomes uniform, the amount of the immune complex trapped on the capture antibody becomes the same in the width direction, and the degree of coloration becomes uniform, so that a determination error by a person can be prevented.

  The D10 / D90 ratio of the polyolefin porous sintered compact is controlled, for example, by controlling the average particle diameter and tap density of the raw material polyolefin particles in a preferable range described later in the sintering method described below. By adjusting the sintering temperature / time, the cooling temperature / time, and the like at the time of manufacturing, the temperature can be controlled within the above range. In particular, it is preferable to appropriately adjust the cooling temperature / time from the viewpoint of suppressing deformation due to shrinkage of the porous polyolefin sintered compact. As a specific example, it is preferable to sinter the polyolefin at a temperature equal to or higher than the melting point and then to place the polyolefin at a temperature equal to or lower than the melting point of 95 ° C. to 115 ° C. for 3 hours or more and then cool to room temperature. By employing such a cooling temperature / time, rapid shrinkage tends to be further suppressed. By such a method or the like, fluctuations due to shrinkage of the pore volume and the median pore diameter can be reduced and equalized, and as a result, the D10 / D90 ratio tends to be controlled to a desired value. Further, the difference in properties depending on each part of the polyolefin porous sintered compact (sheet) can be reduced, and not only can the warpage due to sheet distortion be suppressed, but also the production can be stabilized. The D10 / D90 ratio can be measured, for example, by a mercury porosi method described in Examples described later.

  The median pore diameter of the polyolefin porous sintered compact of the present embodiment is preferably 1 μm or more and 15 μm or less, more preferably 2 μm or more and 14 μm or less, and still more preferably 3 μm or more and 13 μm or less. A median pore diameter of 1 μm or more is preferable in that pores can be prevented from being prevented and a sufficient amount of gas permeation or water absorption can be secured for each pore. On the other hand, when the median pore diameter is 15 μm or less, the number of continuous pores per unit volume can be increased, and even if some pores are closed, pressure loss can be reduced, This is preferable because a sufficient flow rate can be secured over a long period of time and the mechanical strength is improved. Further, the water absorption function by the capillary phenomenon can be sufficiently exhibited, and the water absorption speed tends to be further improved. The median pore diameter of the polyolefin porous sintered compact can be controlled by the average particle size and tap density of the polyolefin particles, which are raw materials described below, and the firing temperature / time and compression temperature / pressure / time during production. The median pore diameter can be measured, for example, by the mercury porosi method described in Examples described later.

The pore volume of the polyolefin porous sintered compact in the present embodiment is preferably from 0.1 cm ³ / g to 2.0 cm ³ / g, more preferably from 0.2 cm ³ / g to 1.8 cm ^3. / G or less, and more preferably 0.3 cm ³ / g or more and 1.6 cm ³ / g or less. The pore volume of 0.1 cm ³ / g or more is preferable from the viewpoint that a space in the polyolefin porous sintered compact necessary for passing and holding gas and liquid can be secured. On the other hand, it is preferable that the pore volume is 2.0 cm ³ / g or less, since the strength of the porous polyolefin sintered compact becomes high. The pore volume of the polyolefin porous sintered compact can be controlled by the average particle size, tap density, firing temperature / time during production, and compression temperature / pressure / time of the polyolefin particles, which will be described later. The pore volume can be measured, for example, by the mercury porosi method described in Examples described later.

As described above, the porous sintered polyolefin product in the present embodiment has a pore volume of 0.1 cm ³ / g or more and 2.0 cm ³ / g or less from the viewpoint of the balance between the strength of the molded product and the securing of the flow path. It is particularly preferable that the median pore diameter be 1 μm or more and 15 μm or less and have continuous pores.

  The aluminum content of the polyolefin porous sintered compact in the present embodiment is preferably 1 ppm or more and 30 ppm or less, more preferably 1.5 ppm or more and 25 ppm or less, and still more preferably 2 ppm or more and 20 ppm or less. It is preferable that the aluminum content of the polyolefin porous sintered compact is 30 ppm or less, since low molecular weight components generated by thermal degradation of the polyolefin are reduced, and the polyolefin porous sintered compact tends to be less colored. In addition, aluminum is known to be aluminum hydroxide particles having higher hardness and higher heat resistance than polyolefin particles, and it is difficult to fuse with adjacent particles at the time of molding processing. In order to avoid problems such as clogging and increase in surface roughness, it is preferable to adjust to the above range. On the other hand, when the aluminum content is 1 ppm or more, it is preferable in that the growth of viable bacteria in the polyolefin porous sintered compact is suppressed, and components that interfere with coloration can be inactivated. The aluminum content of the polyolefin porous sintered compact can be controlled, for example, by the productivity of the ethylene polymer per unit catalyst. The productivity of the ethylene-based polymer can be controlled, for example, by the polymerization temperature, the polymerization pressure, and the slurry concentration of the reactor during the production. That is, in order to increase the productivity of the ethylene-based polymer according to the present embodiment, for example, the polymerization temperature is increased, the polymerization pressure is increased, and / or the slurry concentration is increased. Other methods include, for example, when polymerizing an ethylene-based polymer, selecting the type of co-catalyst component, reducing the concentration of the co-catalyst component, and washing the ethylene-based polymer with an acid or alkali. However, it is possible to control the aluminum content. The measurement of the amount of aluminum derived from the catalyst can be performed, for example, by the method described in Examples described later.

  The chlorine content of the polyolefin porous sintered compact in the present embodiment is preferably 10 ppm or less, more preferably 8 ppm or less, still more preferably 5 ppm or less, and the smaller the better. When the chlorine content of the polyolefin porous sintered compact is 10 ppm or less, when used as a suction conveyance sheet, corrosion of a suction fixing plate or a ceramic green sheet, which is easily affected by chlorine and hydrochloric acid, can be suppressed. Preferred from the point. In addition, when used for medical and pharmaceutical applications such as a support for a rapid test kit by immunochromatography, a filter for treatment of apheresis, a filter for artificial dialysis, various implants, and a pre-filter for a bioanalysis kit, an acid is used. It is extremely important to reduce the content of generated chlorine. The chlorine content of the polyolefin porous sintered compact can be controlled by appropriately adjusting polymerization conditions and the like using a catalyst described later. Further, the chlorine content of the polyolefin porous sintered compact can be measured, for example, by a method described in Examples described later.

  Examples of the polyolefin used as the material of the polyolefin porous sintered compact include, but are not limited to, homopolymers such as ethylene, propylene, 1-butene, and 4-methyl-pentene-1, and ethylene and propylene and other polymers. Examples thereof include a copolymer with an α-olefin, a copolymer of ethylene and vinyl acetate, a copolymer of ethylene with acrylic acid, methacrylic acid, and esters thereof. Among these polyolefins, powders suitable for sinter molding can be easily obtained, sinter molding can be easily performed, chemical resistance is excellent, relatively soft and has moderate rigidity, etc. From, ethylene homopolymer, ethylene copolymer which is a copolymer of ethylene and other α-olefin, homopolymer of propylene, and a copolymer of propylene and other α-olefin such as ethylene Certain propylene copolymers can be suitably applied. In the above, examples of the other α-olefin include, but are not limited to, α-olefins having 4 to 20 carbon atoms, specifically, 1-butene, 4-methyl-1-pentene, -Hexene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene and the like. In the present embodiment, from the viewpoint of stiffness and ease of sinter molding, it is particularly preferable that the polyolefin is a homopolymer of ethylene, or a copolymer of ethylene and an olefin having 3 or more carbon atoms. preferable.

The density of the polyolefin in the present embodiment is preferably 890 kg / m ³ or more and 970 kg / m ³ or less. From the viewpoint of imparting sufficient rigidity to polyolefin porous sintered compact, the lower limit of the density is preferably 890 kg / m ^3, more preferably 900 kg / m ^3, more preferably 910 kg / m ^3. From the viewpoint of handling ease, the upper limit of the density is preferably 970 kg / m ^3, more preferably 960 kg / m ^3. Here, the density of polyethylene can be obtained, for example, by measuring according to the density gradient tube method (23 ° C.) in accordance with JIS K 7112: 1999.

  The viscosity average molecular weight (Mv) of the polyolefin in the present embodiment is preferably 500,000 to 10,000,000, more preferably 750,000 to 9,000,000, and still more preferably 1,000,000 to 8,000,000. When the viscosity average molecular weight (Mv) is 500,000 or more, the flow of the resin, which is a factor that inhibits the formation of pores at the time of sintering, becomes smaller, and the control of the porosity and the like becomes easier. On the other hand, when the viscosity average molecular weight (Mv) is 10,000,000 or less, the fusion property between adjacent particles is excellent, the strength of the polyolefin porous sintered compact is improved, and the processability tends to be improved. The viscosity average molecular weight (Mv) of the polyolefin can be adjusted, for example, by appropriately adjusting polymerization conditions and the like using a catalyst described below. Specifically, the viscosity average molecular weight (Mv) can be adjusted by causing hydrogen to exist in the polymerization system as a chain transfer agent, or by changing the polymerization temperature.

The viscosity average molecular weight (Mv) of the polyolefin of the present embodiment is obtained by preparing solutions in which polyolefins are dissolved in decalin at different concentrations, and measuring the solution viscosity at 135 ° C. of the solutions. The reduced viscosity calculated from the solution viscosity thus measured is extrapolated to a concentration of 0, the intrinsic viscosity is obtained, and the intrinsic viscosity [η] (dL / g) is calculated by the following equation (A). be able to. More specifically, for example, it can be measured by the method described in Examples.
Mv = (5.34 × 10 ⁴ ) × [η] ^1.49 (A)

  The average particle size of the polyolefin particles in the present embodiment is preferably from 20 μm to 100 μm, more preferably from 25 μm to 90 μm, even more preferably from 30 μm to 80 μm. When the average particle size of the polyolefin particles is 20 μm or more, it is easy to form pores in the polyolefin porous sintered compact, and it tends to be easier to secure a sufficient air permeability and water absorption. . On the other hand, when the average particle diameter is 100 μm or less, the surface roughness (Ra) and the surface pore diameter are reduced, and the air-permeable sheet is prevented from being bent by being sucked into the polyolefin porous sintered body. Tend to be able to. The average particle size of the polyolefin particles can be adjusted, for example, by appropriately adjusting polymerization conditions and the like using a catalyst described below. Specifically, it is possible to generate the polyolefin particles using a catalyst having a size within the above range after the polymerization, or to adjust the average particle size by controlling the amount of the generated polyolefin particles according to the polymerization conditions. it can. In addition, polyolefin particles falling within the above range may be selected by classification or the like. The average particle size of the polyolefin is a particle size at which the cumulative weight becomes 50%. For example, methanol is dispersed using a laser diffraction type particle size distribution analyzer (“SALD-2100” manufactured by Shimadzu Corporation). It can be measured as a medium.

  In the present embodiment, the ratio of particles having a size of 106 μm or more (hereinafter also referred to as “coarse particles”) of the polyolefin particles is preferably 1.0% or less, more preferably 0.8% or less, and 0% or less. 0.5% or less is more preferable. When the proportion of the polyolefin particles having a particle diameter of 106 μm or more is 1.0% or less, the surface opening diameter and median pore diameter of the polyolefin porous sintered compact become more uniform, and are used as a suction conveyance sheet. In such a case, there is a tendency that deformation of the suction-adsorbed body due to local ventilation pressure hardly occurs. Further, when used as a chromatograph, there is a tendency that the water flow rate becomes uniform and separation can be performed with higher accuracy. The method for reducing the proportion of particles having a particle diameter of 106 μm or more to 1.0% or less is not particularly limited, and may be obtained directly by polymerization, or the powder obtained by polymerization may be classified into the above range by classification. . Further, the product once shaped into a shape other than powder may be subjected to mechanical pulverization at room temperature or low temperature to obtain a product in the above range, or may be obtained by classifying the mechanically pulverized product. Further, after dissolving in a solvent, a poor solvent may be added to precipitate and powdered one may be used. The ratio of particles having a particle diameter of 106 μm or more is calculated, for example, as the ratio of the total particle mass before classification of the particle mass on the sieve when passing through a 106 μm sieve described in JIS Z8801. Can be.

The tap density of the polyolefin particles in the present embodiment is preferably 0.30 g / cm ³ or more and 0.55 g / cm ³ or less, more preferably 0.32 g / cm ³ or more and 0.50 g / cm ³ or less. , further preferably 0.35 g / cm ³ or more 0.45 g / cm ³ or less. The tap density tends to increase as the number of aggregates and irregularly shaped particles is small, the shape is close to a spherical shape, and the material has a regular surface configuration. When the tap density is 0.30 g / cm ³ or more, the fluidity of the particles tends to be high, and the filling into a mold or the like for sintering tends to be easier. On the other hand, when the tap density is 0.55 g / cm ³ or less, the particles are prevented from being packed too densely, and an appropriate pore volume and a median pore diameter tend to be maintained. As a result, there is a tendency that sufficient air permeability and water absorption are secured as the polyolefin porous sintered compact.

  The tap density of the polyolefin particles in the present embodiment is controlled, for example, by introducing a slurry after polymerization into a flash tank whose internal temperature has been adjusted to 30 ° C. or more and 40 ° C. or less, and blowing a humidified inert gas into the liquid. can do. Examples of the inert gas include, but are not limited to, nitrogen, helium, neon, and argon. Further, the content of water in the inert gas is preferably from 1% by volume to 10% by volume, more preferably from 2% by volume to 8% by volume, and still more preferably from 3% by volume to 5% by volume. The residence time of the slurry when blowing the humidified inert gas is preferably 0.1 to 2 hours, more preferably 0.3 to 1.5 hours, and even more preferably 0.5 to 1.0 hour. Further, the tap density can also be controlled by suppressing the amount of heat generated by the rapid polymerization reaction generated when producing polyolefin particles. Specifically, for example, a continuous polymerization in which ethylene gas, a solvent, a catalyst, and the like are continuously supplied into the polymerization system and are continuously discharged together with the produced ethylene polymer, and the catalyst introduction line outlet is provided with ethylene. The rapid polymerization reaction and deposits on the reaction tank wall tend to be reduced by positioning the catalyst at a position as far as possible from the introduction line outlet and reducing the catalyst feed concentration. Agglomerates of polyolefin particles tend to be reduced. The tap density of the polyolefin particles can be measured, for example, by the method described in Examples described later.

  In the present embodiment, the polymerization method in the method for producing polyethylene particles is not limited to the following. For example, ethylene or a monomer containing ethylene is copolymerized by a slurry polymerization method, a gas phase polymerization method, or a solution polymerization method. ) Polymerization method. Among them, a slurry polymerization method capable of efficiently removing the heat of polymerization is preferable. In the slurry polymerization method, an inert hydrocarbon medium can be used as a medium, and olefin itself can be used as a medium.

  The inert hydrocarbon medium is not particularly limited, but specific examples thereof include aliphatic hydrocarbons such as propane, butane, isobutane, pentane, isopentane, hexane, heptane, octane, decane, dodecane, and kerosene; cyclopentane; Alicyclic hydrocarbons such as cyclohexane and methylcyclopentane; aromatic hydrocarbons such as benzene, toluene and xylene; halogenated hydrocarbons such as ethyl chloride, chlorobenzene and dichloromethane, and mixtures thereof.

  In the present embodiment, it is preferable to use a hydrocarbon medium having 6 to 10 carbon atoms. When the number of carbon atoms is 6 or more, a low-molecular-weight component generated by a side reaction during polyolefin polymerization or deterioration of the polyolefin is relatively easily dissolved, and is easily removed in a step of separating the polyolefin and the polymerization medium. By reducing the low molecular weight component in the polyolefin particles, it is possible to suppress the flow of the resin due to heating at the time of forming the porous polyolefin sintered compact, so that the pore volume, median pore diameter, D10 / The D90 ratio tends to be easily controlled. On the other hand, if the number of carbon atoms is 10 or less, the amount of low molecular weight components (medium) remaining in the polyolefin decreases, adhesion of polyethylene particles to the reaction tank and the like are suppressed, and industrially stable operation can be performed. It is in.

  Generally, the polymerization temperature in the method for producing a polyolefin of the present embodiment is preferably from 30 ° C to 100 ° C, more preferably from 35 ° C to 95 ° C, and still more preferably from 40 ° C to 90 ° C. When the polymerization temperature is 30 ° C. or higher, industrially efficient production tends to be performed. On the other hand, when the polymerization temperature is 100 ° C. or lower, there is a tendency that stable operation can be continuously performed.

  In the present embodiment, the polymerization pressure in the method for producing a polyolefin is usually preferably from normal pressure to 2 MPa, more preferably from 0.1 MPa to 1.5 MPa, and still more preferably from 0.1 MPa to 1.0 MPa.

  The polymerization reaction can be carried out by any of a batch system, a semi-continuous system, and a continuous system, but it is preferable to carry out the polymerization in a continuous system. By continuously supplying ethylene gas, solvent, catalyst, etc. into the polymerization system and continuously discharging it together with the generated polyolefin, it is possible to suppress the partial high temperature state due to rapid ethylene reaction, The system tends to be more stable. When ethylene reacts in a uniform state in the system, the generation of branches, double bonds, and the like in the polymer chain tends to be suppressed. This makes it easy to obtain a polyolefin having a low molecular weight component and having a tap density within the range of the present embodiment. Therefore, a continuous type in which the inside of the polymerization system becomes more uniform is preferable. In the method for producing polyolefin particles according to this embodiment, it is preferable to carry out the polymerization in two or more stages under different reaction conditions.

  The molecular weight of the polyolefin particles can be adjusted, for example, by the presence of hydrogen in the polymerization system or by changing the polymerization temperature, as described in DE-A-3127133. it can. By adding hydrogen as a chain transfer agent into the polymerization system, it becomes easier to control the molecular weight within an appropriate range. When adding hydrogen in the polymerization system, the molar fraction of hydrogen is preferably 0 mol% or more and 30 mol% or less, more preferably 0 mol% or more and 25 mol% or less, and 0 mol% or more and 20 mol% or less. Is more preferred.

  The solvent separation method in the method for producing polyolefin particles can be performed, for example, by a decantation method, a centrifugation method, a filter filtration method, or the like, and a centrifugation method having a high efficiency in separating polyethylene and the solvent is more preferable. The amount of the solvent contained in the polyolefin after the solvent separation is not particularly limited, but is preferably 70% by mass or less, more preferably 60% by mass or less, and still more preferably 50% by mass or less based on the mass of the polyolefin. . By drying and removing the solvent in a small amount of the solvent contained in the polyolefin, metal components such as aluminum contained in the solvent and chlorine tend to hardly remain in the polyolefin. Since these components do not remain, the denatured aluminum is dropped off, fine pores are clogged, the surface roughness is increased, and corrosion of the suction fixing plate, the ceramic green sheet, and the like are suppressed. There is a tendency.

  In the present embodiment, the catalyst component used for producing the polyolefin particles is not particularly limited, and can be produced using, for example, a Ziegler-Natta catalyst, a metallocene catalyst, a Phillips catalyst, or the like. As the Ziegler-Natta catalyst, those described in Japanese Patent No. 5767202 can be suitably used. Examples of the metallocene catalyst include, but are not limited to, those described in JP-A-2006-273977. Can be suitably used.

  In the present embodiment, the average particle size of the catalyst is preferably from 0.1 to 10 μm, more preferably from 0.2 to 9 μm, and still more preferably from 0.5 to 8 μm. When the average particle size is 0.1 μm or more, problems such as scattering and adhesion of the obtained polyolefin particles tend to be prevented. On the other hand, if it is 10 μm or less, the polyolefin particles tend to be too large and settle in the polymerization system, and problems such as line blockage in the post-treatment step of the polyolefin particles tend to be prevented. The particle size distribution of the catalyst is preferably as narrow as possible. Fine particles and coarse particles can be removed by a sieve, centrifugation, or cyclone.

  The method for deactivating the catalyst used for synthesizing the polyolefin particles is not particularly limited, but is preferably performed after separating the polyolefin and the solvent. By introducing an agent for deactivating the catalyst after separation from the solvent, precipitation of the catalyst component and the like dissolved in the solvent can be suppressed, and aluminum and chlorine derived from the catalyst component can be reduced. it can. Examples of the agent that deactivates the catalyst system include, but are not limited to, oxygen, water, alcohols, glycols, phenols, carbon monoxide, carbon dioxide, ethers, carbonyl compounds, alkynes, and the like. Can be.

  In general, the drying temperature in the method for producing polyolefin particles is preferably from 50 ° C to 150 ° C, more preferably from 50 ° C to 140 ° C, and still more preferably from 50 ° C to 130 ° C. When the drying temperature is 50 ° C. or higher, efficient drying is possible. On the other hand, when the drying temperature is 150 ° C. or less, it is possible to dry the polyolefin particles while suppressing aggregation and thermal deterioration. In the present embodiment, other known components useful for the production of polyethylene can be included in addition to the above components.

  In order to obtain a polyolefin porous sintered compact using the polyolefin particles, a sinter molding technique is suitably used. Sinter molding can be obtained, for example, by uniformly spreading the polyolefin particles on a flat plate of a material such as metal and heating / cooling, or by uniformly spreading the polyolefin particles on a flat plate of a material such as metal. There is also a method in which a flat plate made of a material such as a metal is further superimposed thereon during or after heating and cooled, and the surface of the flat plate made of a material such as a metal is transferred. Alternatively, for example, there is a method in which the particles are uniformly spread on a continuous belt of a material such as a metal, and then cooled by being sandwiched between rolls or belts made of a material such as a metal during or after heating. Further, the particles may be filled into a mold having a desired space and heated together with the mold, or hot air or a melt of the particles may be placed in a mold having the desired space containing the particles. Heating may be performed by passing a heat medium that does not hinder the adhesion. Further, a method of slicing or skiving a polyolefin porous sintered compact formed by the above-mentioned molding method is preferably used.

  In the skiving process, from a molded product shaped into a desired shape such as a columnar shape or a cylindrical shape, the film is peeled spirally in the circumferential direction of the sintered body toward the core, as in "peeling of radish". By cutting (cutting), a cutting sheet of a polyolefin porous sintered compact can be obtained, but in a thick compact such as a columnar or cylindrical shape, the median pore diameter, the D10 / D90 ratio, and the like vary depending on the location. There is a tendency, in the present embodiment, among these molding methods, a polyolefin particle is filled in a mold, a mold method of heating and cooling the same, and the polyolefin particles are uniformly dispersed on a belt. The continuous sintering method (deposition method) of continuously heating and cooling is particularly preferable.

  As described above, the method for producing a polyolefin porous sintered compact according to the present embodiment includes a step of performing sinter molding by filling polyolefin particles in a mold (mold method). In addition, another method for producing a porous sintered polyolefin article according to this embodiment includes a step of performing sinter molding by depositing polyolefin particles (deposition method).

  In the case of performing sinter molding using a mold, a method of heating the entire mold is preferably used in consideration of post-treatment after molding and the like. As a method for heating the entire mold, the mold may be charged into a furnace provided with a hot blast stove or a heater, or a flow path may be provided in the mold to pass a heat medium.

  The continuous sintering method can be carried out using, for example, a device including a rotary steel belt, a powder supply hopper with a low-speed rotating roller, a sliding section, a heating section, and a rolling roller. That is, the obtained polyethylene particles are continuously deposited on a movable steel belt from a hopper, and are passed through a frayed portion provided with a clearance from the belt (the deposition portion is on the steel belt) to have an arbitrary thickness. It can be deposited uniformly. Next, continuously put into a heating furnace, after passing through a rolling roller heated to 100 ℃ or more provided with a clearance of any thickness from the top of the belt, and then cooled to room temperature, pores of any thickness A polyolefin polyolefin porous sintered compact having a controlled volume, median pore diameter, and pore distribution can be obtained.

  In any case, the surface temperature of the material to be heated, such as a mold or a belt, is preferably maintained in the range of (the melting point of the used polyolefin + 20 ° C.) to (the melting point of the used polyethylene + 100 ° C.). By setting the surface temperature of a material such as a mold or a belt to (melting point of polyethylene to be used + 20 ° C.) or more, the material is firmly fused, the strength is improved, and the surface roughness of the polyolefin porous sintered compact is reduced. There is a tendency. In addition, by setting the surface temperature of the material such as a mold or a belt to (the melting point of the polyethylene used + 100 ° C.) or less, it is possible to prevent the polyethylene from being deteriorated due to overheating and to suppress the violent flow, and as a result, the appropriate pore There is a tendency that the volume, the median pore diameter, and the pore distribution can be secured.

  The material of a material such as a mold or a belt used for sinter molding is not particularly limited as long as it can withstand the temperature during heating and withstand the thermal expansion of polyethylene generated during heating. Usually, a metal mold is suitably used. Among metals, aluminum and brass are preferably used because of their relatively light weight and good thermal conductivity. These metals may be used as they are, or their surfaces may be plated with chromium, nickel, or the like. At this time, it is preferable that at least one surface of the surface of the material such as a mold or a belt to be contacted with the polyolefin has a maximum surface roughness (Ry) of 10 μm or less, more preferably 5 μm or less. It is as follows. By setting the surface roughness of the surface of a material such as a mold or a belt, which is in contact with polyethylene, to a maximum height (Ry) of 10 μm or less, the surface can be prevented from being transferred to a polyolefin during sintering molding. There is a tendency that the surface roughness of the porous sintered compact can be controlled to a desired range. Here, the maximum height (Ry) of the surface roughness is a value measured according to JIS B0601-1994 by a contact method using a probe having a tip of 0.1 mmR.

  In the present embodiment, the polyolefin porous sintered compact is preferably hydrophilized. The method for hydrophilization treatment in the present embodiment is not limited to the following, and examples thereof include a method using a surfactant and a method using a graft polymerization treatment. In the present embodiment, the polyolefin is preferably a polyolefin in which at least one kind of molecular chain selected from a hydrophilic ethylenically unsaturated group-containing monomer or a polymer thereof is grafted.

  Examples of the surfactant include, but are not limited to, a sulfonic acid type anionic surfactant (A), and polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene fatty acid ester, and polyoxyethylene sorbitol fatty acid ester. One or a mixture (B) of two or more nonionic surfactants selected from the group consisting of glycerin fatty acid esters, glycerin fatty acid esters, and sorbitan fatty acid esters. Each of (A) and (B) is in the range of 0 to 3.0 parts by mass and 0.05 ≦ (A) + (B) ≦ 3.0 (100 parts by mass) with respect to 100 parts by mass of polyolefin particles. (Part). When the sulfonic acid type anionic surfactant (A) and the nonionic surfactant (B) are added within the above ranges, sufficient strength tends to be obtained in the sintered molded article of polyolefin particles.

  Examples of the sulfonic acid type anionic surfactant (A) include, but are not limited to, an alkyl sulfonate, an alkyl naphthalene sulfonate, an alkyl benzene sulfonate, a succinate sulfonate, and an alkyl diphenyl ether disulfonic acid. And the like.

  Among the nonionic surfactants (B), examples of the polyoxyethylene sorbitan fatty acid ester include, but are not limited to, polyoxyethylene sorbitan monolaurate. Examples of the polyoxyethylene sorbitol fatty acid ester include, but are not limited to, polyoxyethylene sorbitol tetraolate and the like. Examples of the polyoxyethylene fatty acid ester include, but are not limited to, polyethylene glycol monolaurate and the like. Examples of the polyglycerin fatty acid ester include, but are not limited to, polyglycerin monoisostearate and the like. Examples of the glycerin fatty acid ester include, but are not limited to, glycerin monostearate and glycerin monooleate. Examples of the sorbitan fatty acid ester-based nonionic surfactant include, but are not limited to, sorbitan monolaurate and the like. These nonionic surfactants may be used alone or in combination of two or more.

  It is preferable that the above-mentioned surfactant is uniformly dispersed and attached to the above-mentioned polyolefin particles. For the treatment for imparting hydrophilicity to the surfactant, specifically, dry mixing is preferable. For example, using a known blender such as a high-speed mixer, the above-mentioned polyolefin particles, a surfactant, and preferably a small amount of water are coexisted and mixed. At this time, predetermined additives such as a heat stabilizer and a release agent may be added. When the hydrophilicity imparting treatment with a surfactant is performed, the treatment may be performed in the state of polyolefin particles as described above, or may be performed after the polyolefin porous sintered compact forming step.

  As a method for hydrophilizing the polyolefin particles constituting the polyolefin porous sintered body, a method of performing a graft polymerization treatment in addition to the method of using a surfactant as described above can be applied. In the case of performing the graft polymerization treatment, after forming the polyolefin porous sintered compact, at least one kind of molecular chain selected from an ethylenically unsaturated group-containing monomer having predetermined hydrophilicity or a polymer thereof is grafted. Alternatively, it may be formed after grafting at least one kind of molecular chain selected from an ethylenically unsaturated group-containing monomer having a predetermined hydrophilicity or a polymer thereof onto polyolefin particles in advance. In the present embodiment, when polyolefin particles are previously grafted with at least one kind of molecular chain selected from an ethylenically unsaturated group-containing monomer having a predetermined hydrophilicity or a polymer thereof, and then performing sinter molding. In order to increase the fusion force, it is preferable to perform sinter molding in a state where polyolefin particles not subjected to the graft polymerization treatment are also mixed.

  The hydrophilic ethylenically unsaturated group-containing monomer used in the graft polymerization is an ethylenically unsaturated group, that is, a monomer having a polymerizable double bond for causing a graft reaction. Also, any compound having at least one or more polymerizable double bonds may be used, and it may be a compound that itself polymerizes to form a macromer, or a compound that does not itself form a homopolymer. You may. These ethylenically unsaturated group-containing monomers may be used alone or in combination of two or more.

  Since the hydrophilicity of the ethylenically unsaturated group-containing monomer is a physical property derived from the hydrophilic functional group, the ethylenically unsaturated group-containing monomer may be a phosphorylcholine group, a hydroxyl group, a carboxyl group, an amino group, an amide group, or an alkoxy group. It is preferable that the compound has at least one functional group selected from a group, a sulfo group, and a salt thereof.

  Examples of other hydrophilic ethylenically unsaturated group-containing monomers include, but are not limited to, monomers having a hydroxyl group such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl acrylate; Monomers having a carboxyl group such as acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and mesaconic acid; monomers having an amino group such as 2-vinylpyridine and 4-vinylpyridine; acrylamide; methacrylamide; Monomers having an amide group such as N, N-dimethylacrylamide, N, N-diethylacrylamide, monomers having an alkoxy group such as methoxymethyl acrylate, methoxyethyl acrylate and methoxypropyl acrylate; Rusuruhon acid, styrene sulfonic acid, sodium vinyl sulfonate, sodium styrene sulfonate, lithium styrene sulfonate, monomers having a sulfo group or a salt such as ammonium styrenesulfonic acid.

  As a method of grafting at least one kind of molecular chain selected from an ethylenically unsaturated group-containing monomer having hydrophilicity or a polymer thereof to a polymer constituting polyolefin particles, a radical generated in a polyolefin is used as a starting point. The method is not particularly limited as long as the method can introduce a hydrophilic ethylenically unsaturated group-containing monomer. For example, a method using plasma generated by corona discharge or glow discharge, a method using an active gas represented by ozone, a method using a photosensitizer such as benzophenone or acetophenone and an active light such as ultraviolet light, a method using ionizing radiation, various methods. Examples include a method using a radical initiator. A method in which radicals are generated by irradiation with actinic rays or ionizing radiation is preferred because of its excellent uniformity. The ionizing radiation is radiation that can act on a substance to cause ionization. For example, γ-rays, X-rays, β-rays, electron beams, α-rays and the like can be mentioned, but γ-rays suitable for industrial production and capable of uniformly generating radicals are particularly preferable.

  The contact between the radical-generated polyolefin particles or the molded article thereof and the ethylenically unsaturated group-containing monomer having hydrophilicity may be performed in a gas phase or in a liquid phase, and is not particularly limited. It is preferable to carry out the method in a liquid phase that can more uniformly graft. Further, in order to enhance the uniformity of the graft polymerization, it is preferable that the ethylenically unsaturated group-containing monomer having hydrophilicity is dissolved in a solvent before use. Further, these liquid phases are preferably liquid phases from which dissolved oxygen has been removed. By removing dissolved oxygen from the liquid phase, it is possible to effectively utilize radical polymerization activity without inadvertently depriving the polymerization activity, and the hydrophilicity of the molded article tends to progress more uniformly.

  The hydrophilic polyolefin porous sintered compact produced by the grafting process in the present embodiment has a hydrophilic functional group bonded to the polyolefin through a covalent bond, so that the water absorbing function is not lost, and impurities such as a surfactant are eliminated. Since there is no elution of a compound that can be used, it can be suitably used for precision industrial use or medical use where cleanliness is required.

  The polyolefin porous sintered compact of the present embodiment can be used by being laminated on another sheet. That is, the laminate of the present embodiment includes the polyolefin porous sintered compact of the present embodiment and a base material on which the polyolefin porous sintered compact is laminated. In order to laminate the polyolefin porous sintered compact and another sheet, they may be bonded using an adhesive or the like, or may be fused by heat. The substrate in the present embodiment is not limited to the following, but includes, for example, an organic sintered body such as a polyolefin porous sintered body, an inorganic sintered body such as a ceramic, and a metal sintered body.

  In order to ensure air permeability, it is preferable that the polyolefin porous sintered compact and the sheet be partially bonded and / or fused by heat. Such a lamination method is not particularly limited. For example, a spray-type adhesive, a method of forming an adhesive surface such as a dot-like or fibrous surface using an adhesive, a gravure coater, a roll coater, a screen printing machine, etc. Method of forming an adhesive surface in the form of dots, meshes, streaks, etc. by using the method, a method of fusing by heating under pressure through a particle-shaped or net-shaped thermoplastic resin, an ultrasonic welder machine, an ultrasonic sewing machine And the like, and a method in which the surface of the polyolefin porous sintered compact in contact with the sheet is slightly melted to be fused. Among them, a method of forming a point-like or fibrous bonding surface using a spray-type adhesive is preferable because it is simple.

  The spray adhesive and the adhesive are not particularly limited, but include, for example, polyester resins, acrylic resins, polyamide resins, polyimide resins, α-olefin resins, polyolefin resins, urethane resins, ether cellulose. , Nitrocellulose, polyvinyl acetate resin, polystyrene resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, polyvinyl butyral resin, polybenzimidazole resin, polymethacrylate resin, melamine resin, urea resin, Resorcinol resin, ethylene vinyl acetate resin, vinyl acetate resin, epoxy resin, vinyl chloride resin, chloroprene rubber resin, styrene butadiene rubber resin, nitrile rubber resin, cyanoacrylate resin, aqueous polymer, isocyanate Existing melts such as acrylate resins, silicone resins, modified silicone resins, phenolic resins, fluorine resins, or ethylene vinyl acetate resin hot melts, reactive hot melts, polyamide resin hot melts, polyurethane hot melts, polyolefin hot melts, etc. Things can be adopted.

  When laminating the polyolefin porous sintered compact and the substrate, a woven fabric with an adhesive can also be used. A known method of providing an adhesive layer only on a linear portion of a woven fabric (for example, described in JP-A-2009-167275) can also be used.

  The polyolefin porous sintered compact obtained by the present embodiment can be used as general industrial members such as a sheet for adsorption and fixing, a sheet for a support of a rapid inspection kit by immunochromatography, a filter for apheresis treatment, an artificial Filters for dialysis, various implants, pre-filters for biological analysis kits, supports such as low-rigidity filters, support for ion exchange resins, etc., life science fields, ink absorbers for printer heads, support for solid electrolytes It can also be used in the field of electronics such as a body, a member for a fuel cell, a separator for a lithium ion secondary battery or a lead storage battery. That is, the sheet for adsorption and fixing according to the present embodiment includes the polyolefin porous sintered compact of the present embodiment or the laminate of the present embodiment. Further, the support sheet of the rapid test kit by the immunochromatography method according to the present embodiment includes the porous sintered polyolefin article of the present embodiment or the laminate of the present embodiment.

Hereinafter, the present embodiment will be described in more detail with reference to Examples and Comparative Examples, but the present embodiment is not limited to the following Examples.
The measurement of each physical property was performed as follows.

(1) Pore volume, median pore diameter, and D10 / D90 ratio A polyolefin porous sintered compact having a thickness of less than 0.5 mm is sintered into a polyolefin porous sintered body having a width of 20 mm x a length of 150 mm and a thickness of 0.5 mm or more. Each of the compacts was cut out to a width of 20 mm and a length of 50 mm, and two pieces of each were overlaid to form a test piece. The pore volume and the median pore diameter of this test piece were measured under the following measurement conditions in accordance with JIS R1655.
≪Measurement conditions≫
Equipment used: Autopore IV9500 (manufactured by Shimadzu Corporation)
Mercury used: Regenerated mercury mercury Surface tension: 485 dynes / cm
Mercury contact angle: 130 °
Maximum measurement pressure: 44,500 psia

  The calculation method will be described with reference to FIG. FIG. 1 is a chart showing the measurement results of the pore volume of the polyolefin porous sintered compact of Example 1, in which the horizontal axis shows the median pore diameter, and the right side of the vertical axis shows the pore volume of the diameter on the horizontal axis ( Unit pore volume), and the left side of the vertical axis shows the ratio of the cumulative pore volume from the large diameter side.

  From FIG. 1, when the pore diameters corresponding to the cumulative 10% diameter and the cumulative 90% diameter are D10 and D90, respectively, D10 in Example 1 was 13.83 μm, and D90 was 5.07 μm. That is, the D10 / D90 ratio of Example 1 was 2.73.

(2) Aluminum content and chlorine content A sample obtained by cutting a polyolefin porous sintered compact into a width of 1 mm and a length of 1 mm was subjected to pressure decomposition using a microwave decomposition apparatus (model ETHOS TC, manufactured by Milestone General). Then, the aluminum element concentration in the polyolefin porous sintered compact was measured by an ICP-MS (inductively coupled plasma mass spectrometer, model X series X7, manufactured by Thermo Fisher Scientific) using an internal standard method.
For the chlorine content, a sample cut out in the same manner was burned by an automatic sample burner (AQF-100 manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and then absorbed in an absorbing solution (a mixed solution of Na ₂ CO ₃ and NaHCO ₃ ). The absorption liquid was injected into an ion chromatograph (ICS 1500, manufactured by Dionex, column (separation column: AS12A, guard column: AG12A) suppressor ASRS300), and the chlorine content was measured.

(3) Thickness of polyolefin porous sintered compact The thickness of the polyolefin porous sintered compact is determined by cutting the polyolefin porous sintered compact along the thickness direction, and cutting the cut surface with an optical microscope (Keyence Corporation). Manufactured by "Microscope VH-Z100UR"), and the average of the obtained values was obtained.

(4) Viscosity average molecular weight (Mv)
20 mg of polyolefin was added to 20 mL of decalin (decahydronaphthalene) and stirred at 150 ° C. for 2 hours to dissolve the polymer. Using a Ubbelohde type viscometer, the drop time (ts) between the marked lines was measured using a 135 ° C. thermostat. Similarly, three solutions were prepared by changing the weight of the polyolefin, and the falling time was measured. The fall time (tb) of only decalin without polyolefin as a blank was measured. The reduced viscosity (ηsp / C) of the polymer determined according to the following formula is plotted, and a linear equation of the concentration (C) (unit: g / dL) and the reduced viscosity of the polymer (ηsp / C) is derived. The extrapolated intrinsic viscosity ([η]) was determined.
ηsp / C = (ts / tb−1) / C (unit: dL / g)
Next, using the value of the intrinsic viscosity ([η]), the viscosity average molecular weight (Mv) was calculated using the following equation (A).
Mv = (5.34 × 10 ⁴ ) × [η] ^1.49 (A)

(5) Average Particle Size The average particle size of the polyolefin particles was measured using SALD-2100 manufactured by Shimadzu Corporation with methanol as a dispersion medium, and the particle size at which the cumulative weight became 50% was defined as the average particle size. Further, the cumulative weight in the range of 1 to 500 μm was calculated, and it was confirmed that the cumulative weight was 90% by weight or more of the whole measured particles.

(6) Ratio of particles having a particle diameter of 106 μm or more The ratio of particles having a particle diameter of 106 μm or more is determined by using a sieve having a mesh size of 106 μm specified by JIS Z8801 and classifying 100 g of particles into particles remaining on the sieve when classifying 100 g of particles. The mass was measured. The value obtained by dividing the mass of the polyethylene particles remaining on the sieve by the total mass of the polyethylene used was defined as the ratio of particles having a particle size of 106 μm or more.

(7) Tap Density The tap density of the polyolefin particles was measured by putting polyethylene particles in a 100-mL glass measuring cylinder, tapping 500 times, and measuring the volume. The value obtained by dividing the mass of the polyethylene particles by the volume was defined as the tap density.

(8) Evaluation of water wicking time and uniformity The water wicking time and uniformity were measured at 25 ° C. under atmospheric pressure by vertically placing the lower 20 mm of a porous polyolefin sintered compact having a width of 30 mm and a height of 100 mm in water at 25 ° C. And the time until the first water reaches 70 mm in height (50 mm sucked up) after immersion, and the last water in the width direction after the first water reaches 70 mm in height It was determined by measuring the time lag before doing so.
：: The siphoning time is 20 seconds or less, and the time difference is less than 1 second.
Δ: The siphoning time is 20 seconds or less, but the time difference is 1 second or more and less than 4 seconds, or the siphoning time is 20 seconds to 30 seconds and the time difference is less than 1 second.
X: The siphoning time is 30 seconds or more and the time difference is 4 seconds or more.

(9) Evaluation of Low Pressure Loss Pressure loss was measured by the method described in JIS B 9927 at a wind speed of 5.3 cm / sec, and the pressure loss difference ΔP before and after the test was compared and evaluated as follows.
：: The pressure loss difference ΔP is less than 0.1 mmH ₂ O.
×: A pressure loss difference ΔP of 0.1 mmH ₂ O or more.

(10) Variations in pore volume, median pore diameter, and D90 / D10 ratio Ten points were randomly selected from the test pieces described in (1) above, which were obtained from a plurality of polyolefin porous sintered compact sheets. The pore volume, the median pore diameter, and the D90 / D10 ratio were measured at 10 points according to the method described above, and the following evaluation was made based on the variation in the values.
：: Among the pore volume, the median pore diameter, and the D90 / D10 ratio, the maximum value or the minimum value is less than 10% from the average value of 10 points.
×: A maximum value or a minimum value of at least one of 10 points out of the pore volume, the median pore diameter, and the D90 / D10 ratio is 10% or more.

(11) Rust test Four stainless steel plates (SUS316) each having a width of 5 cm, a length of 5 cm, and a thickness of 2 mm are placed on a metal frame having an inner diameter of 20 cm, a length of 20 cm, and a thickness of 5 mm. Four sintered compacted sheets were stacked, pressed for 22 minutes at 200 ° C. and 15 MPa, and cooled for 10 minutes at 25 ° C. and 15 MPa. After the sample was allowed to stand in a thermo-hygrostat at a temperature of 60 ° C. and a humidity of 90% for 2 hours, the polyolefin porous sintered compact sheet was peeled off, and the rust on the stainless steel plate was evaluated.
A: No rust was observed.
：: Very little rust was generated, and only a part was observed.
Δ: Rust was observed on the entire surface, though little rust was generated.
×: Rust on the entire surface.

[Reference Example] Catalyst Synthesis [Reference Example 1: Preparation of Ziegler-Natta Catalyst Component [A]]
Hexane (2,000 mL) was added to an 8 L stainless steel autoclave sufficiently purged with nitrogen. 800 mL of a 1 mol / L hexane solution of titanium tetrachloride and 1 mol / L of an organomagnesium compound represented by the composition formula AlMg ₅ (C ₄ H ₉ ) ₁₁ (OSiH) ₂ at 0 ° C. while stirring the two paddle blades at 400 rpm. And a hexane solution (800 mL) were simultaneously added in the same amount over 6 hours. After the addition, the temperature was raised to 10 ° C., and the reaction was continued for 3 hours. After completion of the reaction, stirring was stopped and the mixture was allowed to stand. Then, 2,000 mL of the supernatant was removed, and the solid catalyst component [A] was prepared by washing five times with 1,600 mL of hexane. The amount of titanium contained in 1 g of this solid catalyst component [A] was 3.05 mmol.

[Reference Example 2: Preparation of Ziegler-Natta catalyst component [B]]
(1) Synthesis of (B-1) Support A 1000 mol of 2 mol / L hexane solution of hydroxytrichlorosilane was charged into a sufficiently nitrogen-purged 8 L stainless steel autoclave, and the composition formula AlMg ₅ (C ₄ H) was stirred at 65 ° C. ₉ ) 2550 mL (equivalent to 2.68 mol of magnesium) of a hexane solution of an organomagnesium compound represented by ₁₁ (OC ₄ H ₉ ) ₂ was added dropwise over 4 hours, and the reaction was continued while stirring at 65 ° C. for 1 hour. . After the completion of the reaction, the supernatant was removed and washed four times with 1800 mL of hexane. As a result of analyzing this solid ((B-1) carrier), magnesium contained per gram of the solid was 8.31 mmol.

(2) Preparation of solid catalyst component [B] 110 mL of a 1 mol / L hexane solution of titanium tetrachloride and 1 mol / L of a composition formula AlMg were added to 1970 mL of a hexane slurry containing 110 g of the carrier (B-1) while stirring at 10 ° C. 110 mL of a hexane solution of an organomagnesium compound represented by ₅ (C ₄ H ₉ ) ₁₁ (OSiH) ₂ was simultaneously added over 1 hour. After the addition, the reaction was continued at 10 ° C. for 1 hour. After completion of the reaction, 1100 mL of the supernatant was removed, and the solid catalyst component [B] was prepared by washing twice with 1100 mL of hexane. The amount of titanium contained in 1 g of the solid catalyst component [B] was 0.75 mmol.

[Reference Example 3: Preparation of supported metallocene catalyst component [C]]
Spherical silica having an average particle diameter of 1 μm, a surface area of 900 m ² / g, and a pore volume in the particles of 2.2 mL / g was calcined at 500 ° C. for 5 hours in a nitrogen atmosphere and dehydrated. The amount of surface hydroxyl groups of the dehydrated silica was 1.85 mmol / g per 1 g of SiO ₂ . Under a nitrogen atmosphere, in a 1.8 L autoclave, 40 g of the dehydrated silica was dispersed in 800 mL of hexane to obtain a slurry. 80 mL of a hexane solution of triethylaluminum (concentration: 1 mol / L) was added to the obtained slurry while maintaining the temperature at 50 ° C. with stirring, and then the mixture was stirred for 2 hours to react triethylaluminum with the surface hydroxyl groups of the silica to be treated with triethylaluminum. A component [a] containing silica and a supernatant, wherein the surface hydroxyl groups of the silica treated with triethylaluminum were capped with triethylaluminum was obtained. Thereafter, unreacted triethylaluminum in the supernatant was removed by removing the supernatant in the obtained reaction mixture by decantation. Thereafter, an appropriate amount of hexane was added to obtain 880 mL of a hexane slurry of silica treated with triethylaluminum.
On the other hand, 200 mmol of [(Nt-butylamide) (tetramethyl-η5-cyclopentadienyl) dimethylsilane] titanium-1,3-pentadiene (hereinafter, referred to as “titanium complex”) is charged with Isopar E [Exxon Chemical]. company was dissolved in trade name] 1000 mL of (USA) hydrocarbon mixture, previously triethylaluminum and formula were synthesized from dibutyl magnesium _{AlMg 6 (C 2 H 5)} 3 (n-C 4 H 9) y of 1 mol / L 20 mL of a hexane solution was added, and hexane was further added to adjust the titanium complex concentration to 0.1 mol / L, thereby obtaining a component [b].
In addition, 5.7 g of bis (hydrogenated tallowalkyl) methylammonium-tris (pentafluorophenyl) (4-hydroxyphenyl) borate (hereinafter, referred to as “borate”) is added to 50 mL of toluene and dissolved, and the borate is dissolved. A 100 mmol / L toluene solution of was obtained. 5 mL of a 1 mol / L hexane solution of ethoxydiethyl aluminum was added to this toluene solution of borate at room temperature, and hexane was further added so that the borate concentration in the solution was 70 mmol / L. Thereafter, the mixture was stirred at room temperature for 1 hour to obtain a reaction mixture containing borate.
46 mL of this reaction mixture containing borate was added to 800 mL of the slurry of the component [a] obtained above at 15 to 20 ° C. with stirring to support the borate on silica. Thus, a slurry of borate-supported silica was obtained. Further, 32 mL of the component [b] obtained above was added, and the mixture was stirred for 3 hours to react the titanium complex with borate. Thus, a supported metallocene catalyst [C] containing silica and a supernatant and having catalytically active species formed on the silica was obtained.
Thereafter, unreacted triethylaluminum in the supernatant was removed by removing the supernatant in the obtained reaction mixture by decantation.

[Example 1]
(Polyolefin polymerization process)
Hexane, ethylene, hydrogen, and a catalyst were continuously supplied to a 300-L polymerization reactor equipped with a stirrer. The polymerization pressure was 0.5 MPa. The polymerization temperature was kept at 85 ° C. by cooling the jacket. Hexane was fed from the bottom of the polymerization vessel at 40 L / hr. Solid catalyst component [A] and triisobutylaluminum as co-catalyst were used. The solid catalyst component [A] was added at a rate of 0.2 g / hr from the middle between the liquid level and the bottom of the polymerization vessel, and triisobutylaluminum was added at a rate of 10 mmol / hr from the middle between the liquid level and the bottom of the polymerization vessel. . The production rate of the ethylene polymer was 10 kg / hr. Hydrogen was continuously supplied by a pump so that the hydrogen concentration relative to ethylene in the gas phase was 14 mol%. Note that hydrogen was supplied from a catalyst introduction line in advance so as to make contact with the catalyst, and ethylene was supplied from the bottom of the polymerization reactor. The catalyst activity was 80,000 g-PE / g-solid catalyst component [A]. The polymerization slurry was continuously discharged into a flash drum at a pressure of 0.05 MPa and a temperature of 70 ° C. so as to keep the level of the polymerization reactor constant, thereby separating unreacted ethylene and hydrogen.
Next, the polymerization slurry was continuously sent to a centrifugal separator so that the level of the polymerization reactor was kept constant, and the polymer and other solvents were separated. At that time, the content of the solvent and the like with respect to the polymer was 40%.
The separated polyethylene particles were dried at 85 ° C. while blowing with nitrogen. In this drying step, the polyethylene particles after polymerization were sprayed with steam to deactivate the catalyst and the cocatalyst. 0.3 parts by weight of polyoxysorbitan monolaurate was added to the obtained polyethylene particles, and uniformly mixed using a Henschel mixer.
The obtained polyethylene particles were removed using a sieve having a mesh size of 106 μm, and those not passing through the sieve were removed to obtain polyethylene particles. Table 1 shows the measurement results of the obtained polyethylene particles (PE1).

(Continuous sintering method)
As a method for producing the porous polyolefin sintered compact, a continuous sintering apparatus including a rotary steel belt, a powder supply hopper with a low-speed rotating roller, a sliding section, a heating section, and a rolling roller was used. The obtained polyethylene particles are continuously deposited from a hopper on a movable steel belt at a thickness of 0.15 mm or more, and are passed from a belt (deposited portion is a flat plate) through a frayed portion provided with a clearance of 0.15 mm. As a result, a uniform thickness of 0.15 mm was deposited. Next, it is continuously put into a heating furnace set at 180 ° C., heated for 10 minutes, passed through a 115 mm rolling roller provided with a 0.15 mm clearance from the belt, and left at 105 ° C. for 3 hours. After that, the resultant was cooled at room temperature to obtain a 0.15 mm-thick polyolefin porous sintered compact. Table 1 shows the characteristics of the sintered body.

[Example 2]
In the polymerization step, polyethylene particles of Example 2 were obtained by the same operation as in Example 1 except that the polymerization temperature was 78 ° C and the hydrogen concentration was 6 mol%.
As a method for producing a porous polyolefin sintered compact, the polyolefin of Example 2 was prepared in the same manner as in Example 1 except that 0.5 mm or more was deposited and the clearance between the sliding portion and the rolling roller was 0.5 mm. A porous sintered compact was obtained. Table 1 shows the characteristics of the polyethylene particles and the polyolefin porous sintered compact.

[Example 3]
Using the polyethylene particles obtained in Example 2, a polyolefin porous sintered compact was molded.
A mold method was used as a method for producing a porous polyolefin sintered compact. Using an aluminum plate having a thickness of 4.52 mm, a mold having an outer dimension of 4.52 mm in thickness, a width of 112 mm, a height of 108 mm, and an inner dimension of 0.52 mm in thickness, 100 mm in width, and 100 mm in height was produced. The aluminum plate serving as the upper lid of the mold was removed, and the particles were filled with polyethylene particles while applying vibration with a vibrator for 30 seconds. After returning the upper lid to its original position, it was heated in an oven at 150 ° C. for 25 minutes, left standing at 105 ° C. for 3 hours, and then cooled at room temperature to obtain a sintered body having a thickness of 0.5 mm. Table 1 shows the characteristics of the polyethylene particles and the polyolefin porous sintered compact.

[Example 4]
In the polymerization step, polyethylene particles of Example 4 were obtained in the same manner as in Example 2, except that the polymerization temperature was 58 ° C and no hydrogenation was performed.
As a method for producing a polyolefin porous sintered compact, a polyolefin porous sintered compact was obtained in the same manner as in Example 2. Table 1 shows the characteristics of the polyethylene particles and the polyolefin porous sintered compact.

[Example 5]
Using the polyethylene particles obtained in Example 4, a polyolefin porous sintered compact was molded in the same manner as in Example 3. Table 1 shows the characteristics of the polyethylene particles and the polyolefin porous sintered compact.

[Example 6]
In the polymerization step, the polyethylene of Example 6 was prepared in the same manner as in Example 1, except that the polymerization temperature was 80 ° C., the polymerization pressure was 0.3 MPa, and the solid catalyst component was 1.2 g / Hr of the solid catalyst component [B]. Particles were obtained.
The method for producing the polyolefin porous sintered compact was the same as that of Example 1 except that 0.15 mm or more was deposited and the clearance between the sliding section and the rolling roller was 0.15 mm. A porous sintered compact was obtained. Table 1 shows the characteristics of the polyethylene particles and the polyolefin porous sintered compact.

[Example 7]
In the polymerization step, polyethylene particles of Example 7 were obtained by the same operation as in Example 6, except that the polymerization temperature was 78 ° C and the polymerization pressure was 0.2 MPa.
As a method for producing a polyolefin porous sintered compact, the same operation as in Example 1 was carried out except that the deposit was 0.85 mm or more, the clearance between the sliding section and the rolling roller was 0.85 mm, and the heating time was 15 minutes. As a result, a polyolefin porous sintered compact of Example 7 was obtained. Table 1 shows the characteristics of the polyethylene particles and the polyolefin porous sintered compact.

Example 8
The polyolefin porous sintered compact of Example 1 was placed in a polyethylene bag on which aluminum was deposited, sealed with nitrogen gas, and irradiated with 200 kGy γ-rays while cooling to −60 ° C. with dry ice. A 14% by volume monomer solution was prepared by mixing a 25% by volume aqueous solution of tert-butanol (manufactured by Junsei Chemical Co., Ltd., special grade reagent) and hydroxypropyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd., special grade reagent). Dissolved oxygen was removed by bubbling nitrogen for a minute. The sintered body after γ-ray irradiation was placed in a reaction vessel, and allowed to stand at a reduced pressure of 13.4 MPa or less for 15 minutes. Then, 1200 cm ³ of the above monomer solution was introduced and reacted at 40 ° C. for 20 minutes. Thereafter, it is washed by immersing it in 1200 cm ³ of a 50% by volume aqueous solution of 2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.) at 25 ° C. for 20 minutes, and this washing operation is repeated three times in total, followed by drying. Thereby, a hydrophilic polyolefin porous sintered compact was obtained. Table 1 shows the properties of the obtained polyolefin porous sintered compact.
The obtained polyethylene polyolefin porous sintered compacts of Example 1 and Example 8 were immersed in a hot water circulation tank set at 60 ° C. for 7 hours. Thereafter, the water remaining in the pores of the porous polyolefin sintered compact was removed and dried. This operation was repeated a total of three times to remove the 60 ° C. hot water soluble component, and then the water absorption was evaluated. In Example 1, the water absorption rate was extremely slow. The water absorption rate did not change even after the removal.

[Comparative Example 1]
In the polymerization step, polyethylene particles of Comparative Example 1 were obtained by the same operation as in Example 1 except that the hydrogen concentration was changed to 20 mol%.
The same operation as in Example 1 was carried out as a method for producing a porous polyolefin sintered compact, but the heating temperature was changed to 160 ° C. because the melted polyethylene particles were partially fused to the steel belt. A polyolefin porous sintered compact was obtained. Table 1 shows the characteristics of the polyethylene particles and the polyolefin porous sintered compact.

[Comparative Example 2]
Comparative Example 2 was prepared in the same manner as in Example 1 except that the polymerization temperature was 78 ° C., the polymerization pressure was 0.3 MPa, and the solid catalyst component was Ziegler-Natta catalyst component [B] 1.2 g / Hr. Polyethylene particles were obtained.
As a method for producing a polyolefin porous sintered compact, a polyolefin porous sintered compact was molded in the same manner as in Example 2. Table 1 shows the characteristics of the polyethylene particles and the polyolefin porous sintered compact.

[Comparative Example 3]
In the polymerization step, polyethylene particles of Comparative Example 3 were obtained by the same operation as in Example 2, except that classification was not performed with a sieve having an opening of 106 µm.
As a method for producing a polyolefin porous sintered compact, a polyolefin porous sintered compact was molded in the same manner as in Example 2. Table 1 shows the characteristics of the polyethylene particles and the polyolefin porous sintered compact.

[Comparative Example 4]
Using the polyethylene particles obtained in Example 2, a polyolefin porous sintered compact was molded.
A mold method was used as a method for producing a porous polyolefin sintered compact. Using an aluminum plate having a thickness of 7.15 mm, a mold having an outer dimension of a thickness of 9.15 mm, a width of 112 mm, a height of 108 mm, and an inner dimension of a thickness of 5.15 mm, a width of 100 mm, and a height of 100 mm was produced. The aluminum plate serving as the upper lid of the mold was removed, and the particles were filled with polyethylene particles while applying vibration with a vibrator for 30 seconds. After returning the upper lid to its original position, it was heated in an oven at 150 ° C. for 25 minutes, allowed to stand at 105 ° C. for 3 hours, and then cooled at room temperature to obtain a sintered body having a thickness of 5 mm. Table 1 shows the characteristics of the polyethylene particles and the polyolefin porous sintered compact.

[Comparative Example 5]
10 kg of the porous sintered polyolefin product of Example 2 was charged into a mesh-shaped cylindrical mold (inner diameter 250 mm, height 500 mm), and polyethylene particles were charged while vibrating with a vibrator for 30 seconds. This was put in a pressure vessel, steam (160 ° C., 8 atm) was introduced, heat-sintered for 10 hours, and then left standing at 25 ° C. for cooling. By cutting the obtained cylindrical polyolefin porous sintered compact, a sheet-shaped polyolefin porous sintered compact having a thickness of 500 μm was obtained. Table 1 shows the characteristics of the polyethylene particles and the polyolefin porous sintered compact.

[Comparative Example 6]
In the polymerization step, polyethylene particles of Comparative Example 6 were obtained in the same manner as in Example 2, except that the polymerization temperature was 35 ° C and no hydrogenation was performed.
As a method for producing a polyolefin porous sintered compact, a polyolefin porous sintered compact was obtained in the same manner as in Example 2. Table 1 shows the characteristics of the polyethylene particles and the polyolefin porous sintered compact.

[Comparative Example 7]
Using the polyethylene particles obtained in Example 1, a polyolefin porous sintered compact was molded.
In the method for producing a polyolefin porous sintered compact, a polyolefin porous sintered compact was obtained in the same manner as in Example 1 except that the polyolefin porous sintered compact was cooled at room temperature without passing at 105 ° C. for 3 hours after passing through a rolling roller. Was. Table 1 shows the characteristics of the polyethylene particles and the polyolefin porous sintered compact.

Claims (12)

Including polyolefin particles composed of polyolefin,
The thickness is 0.05 to 1 mm,
10% cumulative from the large diameter side of the cumulative pore distribution, respectively median pore diameter corresponding to cumulative 90%, when the D10, D90, D10 / D90 ratio have a median pore diameter distribution of 10 or less,
A polyolefin porous sintered compact having a pore volume of 0.1 cm ³ / g or more and 2.0 cm ³ / g or less, a median pore diameter of 1 μm or more and 15 μm or less, and having continuous pores . The polyolefin porous sintered compact according to claim 1 , wherein the aluminum content is 1 ppm or more and 30 ppm or less. The polyolefin porous sintered compact according to claim 1 or 2 , wherein the chlorine content is 10 ppm or less. The polyolefin porous sintered compact according to any one of claims 1 to 3 , wherein the thickness is 0.1 to 0.8 mm. The polyolefin porous sinter according to any one of claims 1 to 4 , wherein the polyolefin is a homopolymer of ethylene or a copolymer of ethylene and an olefin having 3 or more carbon atoms. . The polyolefin porous sintered compact according to any one of claims 1 to 5 , wherein the polyolefin has a viscosity average molecular weight of 500,000 to 10,000,000. The polyolefin according to any one of claims 1 to 6 , wherein the polyolefin is a polyolefin obtained by grafting at least one kind of molecular chain selected from a hydrophilic ethylenically unsaturated group-containing monomer or a polymer thereof. Porous sintered compact. It is a manufacturing method of the polyolefin porous sintered compact according to any one of claims 1 to 7 ,
A method for producing a polyolefin porous sintered compact, comprising a step of performing sinter molding by filling the polyolefin particles in a mold. It is a manufacturing method of the polyolefin porous sintered compact according to any one of claims 1 to 7 ,
A method for producing a porous sintered polyolefin article, comprising a step of performing sinter molding by depositing the polyolefin particles. A laminate comprising: the polyolefin porous sintered compact according to any one of claims 1 to 7 ; and a substrate on which the polyolefin porous sintered compact is laminated. An adsorption-fixing / conveying sheet, comprising the polyolefin porous sintered compact according to any one of claims 1 to 7 or the laminate according to claim 10. A sheet for a support of a rapid inspection kit by an immunochromatography method, comprising the polyolefin porous sintered compact according to any one of claims 1 to 7 or the laminate according to claim 10.