JP2009113315A - Laminated product of sintered body layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated product of sintered body layers, in which a hydrophilic layer and a hydrophobic layer are laminated, while having both long-term durability of a water absorption function and a low elution property, without permeating water absorbed in one surface to the other surface, excellent in moldability, impact resistance, mechanical strength, and dimensional stability when water is absorbed, and having excellent gas permeability as a whole. <P>SOLUTION: A laminated product of polyolefin porous sintered body layers has at least the hydrophilic layer and the hydrophobic layer, respective layers are directly bonded and laminated, and ventilation resistance of a thickness direction is 300-2,000 mmAq. The hydrophilic layer is characterized by being a hydrophilic polyolefin sintered body which is grafted with a hydrophilic ethylenically unsaturated group-containing monomer having at least one functional group selected from a phosphorylcholine group, hydroxyl group, carboxyl group, amino group, amide group, sulfonic group, or a salt thereof. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sintered body layer laminate. More specifically, it is a laminate of a polyolefin porous sintered body layer in which a hydrophilic layer and a hydrophobic layer are laminated, and has both long-term water absorption function and low elution, and is opposite to water absorbed on one side. The present invention relates to a sintered body layer laminate having excellent moldability, impact resistance, mechanical strength and dimensional stability at the time of water absorption, and having good air permeability as a whole without being transmitted through the surface.

The porous sintered body of polyolefin resin particles with continuous pores has excellent characteristics such as fluid filtration function, permeation function, induction function, etc., and widely used as filters, diffuser tubes, liquid induction materials, etc. Has been. In particular, hydrophilic porous sintered bodies mainly composed of hydrophilized polyethylene are utilized for water absorption, diffusion, divergence, permeation, induction, etc. by utilizing the water absorption function. The polyolefin sintered compact of 1 is illustrated, etc.
By the way, as a porous body having a water absorption function, a synthetic fiber cloth or non-woven cloth which has been hydrophilized, an asbestos cloth or a natural fiber cloth, a fiber material such as paper, a hollow thermoplastic resin which has been hydrophilized. Examples include thread membranes, microporous membranes, sintered bodies of metals and ceramics, water-absorbing polymer materials, etc., but porous sintered bodies of polyolefin resin particles have a very small dimensional change due to swelling during water absorption. Since it has all the advantages of maintaining high strength as a body and being able to handle complex shapes, it is expected to be used in various applications.

On the other hand, if a hydrophilic porous sintered body is used for an application where a water absorption function is required only on one side, such as a condensed water absorber in a refrigerator vegetable room, the juice from the upper food is also absorbed and contaminated. easy. Thus, various composite materials having a hydrophilic layer and a hydrophobic layer have been studied. Examples of a simple method include a method of adhering a hydrophilic porous sintered body and a hydrophobic porous sintered body with heat or an adhesive, etc., but the air permeability that is a feature of the porous sintered body is exemplified. There is a risk of damage, which is not preferable. It is possible to use the hydrophilic porous sintered body and the hydrophobic porous sintered body in an overlapping manner, but in this case, a device for bringing the two layers into close contact is required. Patent Document 2 discloses a combination of a hydrophilic porous sintered body and a hydrophobic resin thin film. However, the resin thin film has to be reinforced from the viewpoint of strength, has small pores, and is hydrophilic. Since it is necessary to fuse with the porous porous sintered body, the air permeability is greatly impaired.
In addition to this, a method for integrating a specific hydrophilic layer and a hydrophobic layer has been proposed, as described in Patent Document 3, for example. However, the water absorption function of the sintered body layer laminate is not only to improve wettability but also to spontaneously supply water using the capillary phenomenon while maintaining the strength as a molded body and dimensional stability during water absorption. In order to satisfy these requirements, it has been necessary to approach from both the improvement of the water absorption function and the basic physical properties as a molded body.

Japanese Patent Publication No. 4-28021 JP-A-62-36143 Japanese Patent No. 2577462

The present invention has been made in view of the situation as described above, in which a hydrophilic layer and a hydrophobic layer are laminated, and the water absorption function has long-term sustainability and low elution, and water absorbed on one side is obtained. An object of the present invention is to provide a sintered body layer laminate having excellent moldability, impact resistance, mechanical strength and dimensional stability at the time of water absorption, and having good air permeability as a whole without being transmitted through the opposite surface. And

  As a result of intensive studies to solve the above problems, the inventor of the present invention specified a specific hydrophilic porous layer in a specific polyolefin porous sintered body laminate in which a hydrophilic layer and a hydrophobic layer were laminated. By using a hydrophilic polyolefin sintered body, it has both long-lasting water absorption function and low elution property, and without allowing the water absorbed on one side to permeate the opposite side, the moldability, impact resistance, mechanical strength and It has been found that a sintered body layer laminate having excellent dimensional stability at the time of water absorption and having good air permeability as a whole can be easily obtained, and the present invention has been made based on this finding.

That is, the present invention is as follows.
(1) A polyolefin porous sintered body laminate having at least a hydrophilic layer and a hydrophobic layer, wherein each layer is directly bonded and laminated, and the airflow resistance in the thickness direction is 300 to 2000 mmAq. The hydrophilic layer has a hydrophilic ethylenically unsaturated group-containing monomer having at least one functional group selected from a phosphorylcholine group, a hydroxyl group, a carboxyl group, an amino group, an amide group, a sulfonic acid group or a salt thereof. A sintered body layer laminate comprising a hydrophilic polyolefin sintered body to which is grafted.
(2) The sintered body layer laminate according to (1) above, wherein the graft ratio of the hydrophilic ethylenically unsaturated group-containing monomer is 0.01 to 50%.
(3) A hydrophilic ethylenically unsaturated group-containing monomer having a phosphorylcholine group is represented by the following general formula (1):

（上記一般式（１）中、Ｒ^１は水素原子又はメチル基、ｎは２〜１０の整数である。）
で示されるメタクリロイルオキシアルキルホスホリルコリン又はアクリロイルオキシアルキルホスホリルコリンから選ばれる少なくとも１種のモノマーであることを特徴とする、上記（１）又は（２）に記載の焼結体層積層物。

(In the general formula (1), R ¹ is a hydrogen atom or a methyl group, and n is an integer of 2 to 10.)
The sintered body layer laminate according to (1) or (2) above, which is at least one monomer selected from methacryloyloxyalkylphosphorylcholine or acryloyloxyalkylphosphorylcholine represented by formula (1).

(4) The sintered body according to any one of (1) to (3) above, wherein the hydrophilic ethylenically unsaturated group-containing monomer having a phosphorylcholine group is 2-methacryloyloxyethyl phosphorylcholine. Layer laminate.
(5) The sintered body layer laminate is composed of a sintered body of polyolefin resin particles, and the polyolefin resin particles are an ethylene homopolymer or a copolymer of ethylene and an olefin having 3 or more carbon atoms. The sintered body layer laminate according to any one of (1) to (4) above.

  According to the present invention, a hydrophilic layer and a hydrophobic layer are laminated, having both long-term sustainability and low elution of water absorption function, and without allowing water absorbed on one side to pass through to the opposite side, moldability, impact resistance, A sintered body laminate having excellent mechanical strength and dimensional stability at the time of water absorption and having good air permeability as a whole can be easily obtained.

Hereinafter, the present invention will be specifically described. In the present invention, the term “polymerization” may be used to mean not only homopolymerization but also copolymerization, and the term “polymer” includes not only homopolymers but also copolymers. In some cases.
The sintered body layer laminate in the present invention is a laminate of a polyolefin porous sintered body obtained by sintering and molding polyolefin resin particles, and has at least a hydrophilic layer and a hydrophobic layer, and each layer is directly bonded. Has been.
In the present invention, the state in which the layers are directly bonded means a state in which the layers are bonded without interposing any material other than the raw material powder. The joined laminate is in an integrated state.
In the present invention, graft means a reaction in which any ethylenically unsaturated group-containing monomer is chemically bonded to a molecular chain of a polyolefin as a trunk.

  The polyolefin resin particle used in the present invention is not particularly limited as long as it is a particulate polyolefin, but particles suitable for sintering molding can be easily obtained, sintering molding is easy and excellent in formability, moderately Soft, moderately rigid, excellent in chemical resistance, excellent in workability even after being formed into a sintered body, excellent in dimensional stability during water absorption due to low hygroscopicity and water absorption of the material, ethylenically unsaturated Homopolymers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, ethylene and propylene and other α-olefins for reasons such as excellent radical retention when grafting group-containing monomers It is preferably a copolymer, a copolymer of ethylene and vinyl acetate, a copolymer of ethylene and acrylic acid, methacrylic acid or an ester thereof. And particularly preferably a homopolymer or a copolymer of ethylene and a an olefin having 3 or more carbon atoms.

Examples of the olefin having 3 or more carbon atoms copolymerized with ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1- Examples include tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene and vinylcyclohexane, and propylene, 1-butene, 1-hexene and 1-octene are particularly preferable. Some of these can be combined and copolymerized with ethylene. In addition, it is possible to polymerize olefins in the presence of dienes such as butadiene and isoprene, and it is also possible to polymerize dienes.
As the polyolefin resin particles used in the present invention, resin particles obtained by polymerization may be used as they are, or classified and used. In addition, a product shaped into a shape other than particles may be pulverized by a known method such as mechanical pulverization, freeze pulverization, chemical pulverization, and the obtained resin particles may be used as they are or may be classified and used.

There is no restriction | limiting in particular about the shape of the polyolefin resin particle used for this invention. It may be spherical or indefinite, and may be composed of primary particles, secondary particles in which a plurality of primary particles are aggregated and integrated, or secondary particles that are further pulverized.
There are no particular limitations on the method for producing the polyolefin resin particles used in the present invention, and any of the commonly used solution methods, high pressure methods, high pressure bulk methods, slurry methods, and gas phase methods may be used. It is preferable to use a slurry method or a gas phase method in which polyolefin resin particles are directly obtained by polymerization using an olefin polymerization catalyst, and it is particularly preferable to use a slurry method. There is no restriction | limiting in particular about the superposition | polymerization pressure at the time of manufacture, Usually, it is 0.1MPa-300MPa as a gauge pressure, However In the case of a slurry method, normal pressure-10MPa are preferable. There is no restriction | limiting in particular about superposition | polymerization temperature, Usually, it is 25 to 300 degreeC, However, In the case of a slurry method, 25 to 120 degreeC is preferable and 50 to 100 degreeC is especially preferable. As the solvent for the slurry method, a conventionally used inert hydrocarbon solvent is used, for example, an aliphatic hydrocarbon such as isobutane, pentane, hexane, and heptane, an aromatic hydrocarbon such as benzene and toluene, or cyclohexane, And alicyclic hydrocarbons such as methylcyclohexane.

The average particle diameter of the polyolefin resin particles in the present invention is a particle diameter with a cumulative weight of 50%, that is, a median diameter, and is not particularly limited, but ensures air permeability as a sintered body layer laminate and absorbs water. In order to fully exhibit the function, it is preferably in the range of 10 to 1000 μm, particularly preferably in the range of 30 to 500 μm.
The bulk density of the polyolefin resin particles in the present invention is a value measured according to JIS K 6892 without adding an additive such as a lubricant to the polyolefin resin particles, and is not particularly limited. to ensure proper ventilation as objects, and to sufficiently exhibit the water-absorbing function, it is preferably in the range of 0.20~0.55g / cm ^3, a range of 0.22~0.50g / cm ³ It is particularly preferable that
The density of the polyolefin resin particles in the present invention is a value measured according to JIS K 7112 using a section cut out from a press sheet of polyolefin resin particles, and there is no particular limitation, but as a sintered body layer laminate, to secure the rigidity and chemical resistance without impairing the flexibility is preferably in the range of 0.850~0.970g / cm ^3, in the range of 0.920~0.960g / cm ³ Is particularly preferred.

The melting point of the polyolefin resin particles in the present invention was measured using a differential scanning calorimeter Pyris1 manufactured by PERKIN ELMER. After holding 8.4 mg of the sample at 50 ° C. for 1 minute, the temperature was raised to 200 ° C. at a rate of 10 ° C./min, and the temperature showing the maximum peak in the melting curve obtained at that time was taken as the melting point.
The viscosity average molecular weight of the polyolefin resin particles in the present invention is a value obtained by converting the intrinsic viscosity obtained from the specific viscosity of the polymer solution into a viscosity average molecular weight, and is not particularly limited, but inhibits the formation of pores during sintering molding. In order to reduce the flow of resin as a factor and to have excellent fusion properties between adjacent polyolefin resin particles, it is preferably in the range of 50,000 to 7 million, more preferably in the range of 100,000 to 5 million. , 200,000 to 4,000,000 is particularly preferable.

In the sintered body layer laminate according to the present invention, the layers are directly joined and integrated. For this reason, it is not necessary to perform secondary processing such as adhesion, and a laminate of a hydrophilic layer and a hydrophobic layer is obtained. Moreover, since each layer is integrated, the air permeability which is the original characteristic of a sintered compact is not impaired.
In the present invention, in order to directly bond and laminate the hydrophilic layer and the hydrophobic layer, the hydrophilic layer or the hydrophobic layer is preformed in advance, and the raw material of the other layer is sprayed thereon to sinter the whole. Examples thereof include a method of binding, a raw material of the hydrophilic layer or a raw material of the hydrophobic layer, and a method of sintering the whole by spraying the other raw material so that the lower layer is not disturbed. Note that three or more layers can be formed by a combination of the above methods.

  The sintered body according to the present invention is obtained by depositing polyolefin resin particles in a desired shape or filling a mold, and then heating to the melting point or higher in a non-pressurized or pressurized state while leaving a gap between the particles. It is done. Continuous pores can be easily formed by heat-sealing the surface layer of the polyolefin resin particles. As a method for filling the mold, for example, a vibrating filling device such as a vibrator repacker can be used. Although the influence of the vibration amplitude on the particles is relatively small, there is a possibility that the redistribution of the particles will be caused by a small particle size sinking under the vibration load for a long time. It is preferable to minimize the time required for the filling apparatus. There is no particular limitation on the material of the mold, and for example, iron, stainless steel, brass, aluminum or the like is used. Aluminum is preferable because it is durable, has a small heat capacity, is lightweight, and is easy to handle. The shape of the mold is not particularly limited as long as particles can be filled, such as a plate for two flat plates arranged in parallel, a cylinder for two different diameter cylinders, etc. Absent.

In the present invention, the heating method for performing the sintering molding is not particularly limited as long as the temperature can be controlled. For example, a method such as a hot air dryer, electric dielectric heating, or electric resistance heating can be used. The heating temperature is not particularly limited as long as it is a temperature at which the particles are sufficiently welded in the vicinity of the melting point of the polyolefin resin particles and the resin does not flow to fill the particle gap. For example, in the case of polyethylene, it is preferably in the range of 110 to 220 ° C, particularly preferably in the range of 120 to 180 ° C.
The surface or inside of the sintered body laminate in the present invention can be combined with cloth, woven fabric, knitted fabric, non-woven fabric, perforated film, microporous membrane, wire mesh, etc. that do not inhibit the water absorption function of the present invention. It is. It is also possible to provide a part with a non-moisture permeable or non-water permeable film, film or the like so that the influence of absorbed moisture is not exerted on the surroundings. Furthermore, it is possible to impart design properties by coloring, printing, or the like. If necessary, a heat stabilizer, a weathering agent, a surfactant, an antistatic agent, a deodorant, a deodorant, a fungicide, an antibacterial agent, a fragrance, a filler, etc. may be added and sintered. . When these additives are added, a spreading agent such as liquid paraffin can be used.

The continuous pores of the sintered body layer laminate in the present invention are pores that are continuous from one surface of the sintered body to the other surface. This hole may be linear or curved. Moreover, the whole dimension may be uniform, for example, the dimension of the pores may be changed between the surface layer and the inside, or one surface layer and the other surface layer.
The thicknesses of the hydrophilic layer and the hydrophobic layer in the present invention are each preferably 0.5 mm or more, and more preferably 1 mm or more. By satisfying this condition, the strength of the sintered body layer laminate can be ensured, and the water absorption of the hydrophilic layer and the water repellency of the hydrophobic layer can sufficiently function. Moreover, in this invention, it is preferable that the whole thickness by which the hydrophilic layer and the hydrophobic layer were laminated | stacked is 1-30 mm, and it is more preferable that it is 1-10 mm. By satisfying this condition, the air permeability as the sintered body layer laminate can be sufficiently ensured and the water absorbing function can be sufficiently exhibited.

The average porosity of the sintered body layer laminate in the present invention is a value calculated according to the following formula, and is not particularly limited, but ensures air permeability as the sintered body layer laminate and absorbs water. In order to fully exhibit the function, the content is preferably 20 to 60% by volume, particularly preferably 25 to 55% by volume.
Average porosity (volume%) = [(true density−apparent density) / true density] × 100
Here, the true density (g / cm ³ ) is the density of the polyolefin resin particles, and the apparent density (g / cm ³ ) is the weight of the sintered body layer laminate outside the sintered body layer laminate. It is the value divided by the volume calculated from the dimensions. Note that the pores of the sintered body layer laminate may be uniform throughout or non-uniform.

The average pore diameter of the sintered body layer laminate in the present invention is a value measured by a mercury intrusion method, and is not particularly limited, but ensures air permeability as a sintered body layer laminate and has a water absorption function. In order to fully exhibit, it is preferable that it is 1-150 micrometers, and it is especially preferable that it is 10-100 micrometers.
The hydrophilic ethylenically unsaturated group-containing monomer in the present invention is homogeneously dissolved when mixed with 25% by weight of pure water at 25 ° C. under atmospheric pressure, and has an ethylenically unsaturated group, that is, a graft reaction. It is a monomer having a polymerizable double bond to cause Moreover, what is necessary is just a compound which has at least 1 or more polymerizable double bond, and itself may superpose | polymerize and become a macromer.
The hydrophilic ethylenically unsaturated group-containing monomer in the present invention has at least one functional group selected from a phosphorylcholine group, a hydroxyl group, a carboxyl group, an amino group, an amide group, a sulfonic acid group or a salt thereof. It is said.
The hydrophilic ethylenically unsaturated group-containing monomer having a phosphorylcholine group in the present invention is

で示されるリン脂質類似構造を有し、かつ、エチレン性不飽和基、すなわちグラフト反応が生じるための重合性二重結合を有しているモノマーである。また、少なくとも１つ以上の重合性二重結合を有する化合物であれば良く、それ自身が重合してマクロマーとなるものであっても良い。ホスホリルコリン基は、細胞膜を構成する脂質の極性基と同様の化学構造を有していることから、親水性に優れるとともに、良好な生体親和性を示す。

And a monomer having an ethylenically unsaturated group, that is, a polymerizable double bond for causing a graft reaction. Moreover, what is necessary is just a compound which has at least 1 or more polymerizable double bond, and itself may superpose | polymerize and become a macromer. Since the phosphorylcholine group has a chemical structure similar to that of the polar group of the lipid constituting the cell membrane, the phosphorylcholine group has excellent hydrophilicity and good biocompatibility.

Examples of the hydrophilic ethylenically unsaturated group-containing monomer having a phosphorylcholine group in the present invention include 2-methacryloyloxyethyl phosphorylcholine, 2-acryloyloxyethyl phosphorylcholine, 3-methacryloyloxypropyl phosphorylcholine, 3-acryloyloxypropyl phosphorylcholine, 4-methacryloyloxybutylphosphorylcholine, 4-acryloyloxybutylphosphorylcholine, 5-methacryloyloxypentylphosphorylcholine, 5-acryloyloxypentylphosphorylcholine, 6-methacryloyloxyhexylphosphorylcholine, 6-acryloyloxyhexylphosphorylcholine, 7-methacryloyloxyheptylphosphorylcholine, 7 -Acryloyloxyheptyl phosphoryl Choline, 8-methacryloyloxyoctyl phosphorylcholine, 8-acryloyloxyoctyl phosphorylcholine, 9-methacryloyloxynonylphosphorylcholine, 9-acryloyloxynonylphosphorylcholine, 10-methacryloyloxydecylphosphorylcholine, 10-acryloyloxydecylphosphorylcholine, 2-methacryloyloxypropylphosphorylcholine Methacryloyloxyalkyl phosphorylcholine such as 2-acryloyloxypropyl phosphorylcholine or acryloyloxyalkyl phosphorylcholine, 2-methacryloyloxyethoxyethyl phosphorylcholine, 2-acryloyloxyethoxyethyl phosphorylcholine, 2-methacryloyloxydiethoxyethyl phosphorylcholine, 2-a Liloyloxydiethoxyethyl phosphorylcholine, 2-methacryloyloxytriethoxyethyl phosphorylcholine, 2-acryloyloxytriethoxyethyl phosphorylcholine, 2-methacryloyloxytetraethoxyethyl phosphorylcholine, 2-acryloyloxytetraethoxyethyl phosphorylcholine, 2-methacryloyloxypentaethoxy Ethyl phosphorylcholine, 2-acryloyloxypentaethoxyethyl phosphorylcholine, 2-methacryloyloxyhexaethoxyethyl phosphorylcholine, 2-acryloyloxyhexaethoxyethyl phosphorylcholine, 2-methacryloyloxyheptaethoxyethyl phosphorylcholine, 2-acryloyloxyheptaethoxyethyl phosphorylcholine, 2- Mekakuri Royloxyoctaethoxyethyl phosphorylcholine, 2-acryloyloxyoctaethoxyethyl phosphorylcholine, 2-methacryloyloxynonaethoxyethyl phosphorylcholine, 2-acryloyloxynonaethoxyethyl phosphorylcholine, vinylphosphorylcholine, allylphosphorylcholine, butenylphosphorylcholine, pentenylphosphorylcholine, hexenylphosphorylcholine, Heptenylphosphorylcholine, octenylphosphorylcholine, nonenylphosphorylcholine, decenylphosphorylcholine, ω-methacryloyloxyethylenephosphorylcholine, ω-acryloyloxyethylenephosphorylcholine, ω-methacryloylpolyoxyethylenephosphorylcholine, ω-acryloylpolyoxyethylenephosphorylcholine 2-acrylamidoethyl phosphorylcholine, 3-acrylamidopropyl phosphorylcholine, 4-acrylamidobutyl phosphorylcholine, 5-acrylamidopentylphosphorylcholine, 6-acrylamidehexylphosphorylcholine, 7-acrylamideheptylphosphorylcholine, 8-acrylamideoctylphosphorylcholine, 9-acrylamidooctylphosphorylcholine, 10- Acrylamide decyl phosphorylcholine, ω-methacrylamide polyoxyethylene phosphorylcholine, ω-acrylamide polyoxyethylene phosphorylcholine, 2- (p-styryloxy) ethyl phosphorylcholine, 4- (p-styryloxy) butylphosphorylcholine, 2- (p-styryl) Phosphorylcholine, 2- (p-styrylmethyl) phospho Horylcholine, 2- (p-vinylbenzyloxy) ethylphosphorylcholine, 2- (p-vinylbenzyl) ethylphosphorylcholine, 2- (p-vinylbenzoyloxy) ethylphosphorylcholine, 2- (vinyloxycarbonyl) ethylphosphorylcholine, 2- ( Allyloxycarbonyl) ethyl phosphorylcholine and the like.

（上記一般式（１）中、Ｒ^１は水素原子又はメチル基、ｎは２〜１０の整数である。）
で示されるメタクリロイルオキシアルキルホスホリルコリン又はアクリロイルオキシアルキルホスホリルコリンが好ましく、２−メタクリロイルオキシエチルホスホリルコリンが特に好ましい。これらのエチレン性不飽和基含有モノマーは１種単独で使用することもできるし、２種以上を組み合わせて使用することもできる。

(In the general formula (1), R ¹ is a hydrogen atom or a methyl group, and n is an integer of 2 to 10.)
And methacryloyloxyalkyl phosphorylcholine or acryloyloxyalkylphosphorylcholine represented by formula (2) is preferred, and 2-methacryloyloxyethyl phosphorylcholine is particularly preferred. These ethylenically unsaturated group-containing monomers can be used singly or in combination of two or more.

Examples of the hydrophilic ethylenically unsaturated group-containing monomer having at least one functional group selected from a hydroxyl group, a carboxyl group, an amino group, an amide group, a sulfonic acid group or a salt thereof in the present invention include hydroxyethyl acrylate. , Hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, glycerin monomethacrylate, glycerin dimethacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, various fatty acid-modified glycidyl methacrylates, polyethylene glycol monoacrylate , Polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, poly Lopylene glycol monomethacrylate, polyethylene glycol-polypropylene glycol monoacrylate, polyethylene glycol-polypropylene glycol monomethacrylate, poly (ethylene glycol-tetramethylene glycol) monoacrylate, poly (ethylene glycol-tetramethylene glycol) monomethacrylate, poly (propylene glycol- Monomers having hydroxyl groups such as tetramethylene glycol) monoacrylate, poly (propylene glycol-tetramethylene glycol) monomethacrylate, 3- (1,1,2,2-tetrafluoroethoxy) -2-hydroxypropyl methacrylate, allyl alcohol, etc. , Acrylic acid, Methacrylic acid, Maleic acid, Fumaric acid, Itaconic acid, Citra Monomers having a carboxyl group such as acid and mesaconic acid, 2-vinylpyridine, 4-vinylpyridine, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl acrylate, N , N-diethylaminoethyl methacrylate and other monomers having amino groups, acrylamide, methacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N-methylacrylamide, methylenebisacrylamide, diacetone acrylamide, N-vinylacetamide , N-methyl-N-vinylacetamide, monomers having an amide group such as N-vinylpyrrolidone, vinyl sulfonic acid, styrene sulfonic acid, sodium vinyl sulfonate, styrene sulfonic acid Examples thereof include monomers having a sulfonic acid group or a salt thereof such as sodium, lithium styrenesulfonate, ammonium styrenesulfonate, etc., and these ethylenically unsaturated group-containing monomers can be used alone or in combination of two types. A combination of the above can also be used. In addition, monomers having an epoxy group such as glycidyl acrylate, glycidyl methacrylate, glycidyl sorbate, glycidyl metataconate, ethyl glycidyl maleate, glycidyl vinyl sulfonate, fatty acid vinyl esters such as vinyl acetate and vinyl versatate, methyl acrylate, ethyl Acrylate, n-propyl acrylate, n-butyl acrylate, tert-butyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, n-stearyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, cyclopentyl Methacrylate, cyclohexyl methacrylate, n-stearyl methacrylate Acrylic or methacrylic acid esters such as acrylate, acrylic acid chloride, acrylic acid bromide, methacrylic acid chloride, methacrylic acid bromide and other acrylic acid or methacrylic acid halides, acrolein and other unsaturated aldehydes, etc. Then, the active functional group contained in these monomers may be substituted with a hydrophilic functional group.

The hydrophilic polyolefin sintered body in the present invention may be obtained by sintering and molding polyolefin resin particles, and then grafting a hydrophilic ethylenically unsaturated group-containing monomer to the polyolefin resin particles in advance. It may be obtained by grafting an unsaturated group-containing monomer and then sintering.
In the case of sintering molding after grafting a hydrophilic ethylenically unsaturated group-containing monomer to polyolefin resin particles in advance, a hydrophilic ethylenically unsaturated group-containing monomer is grafted to increase the welding power. Sinter molding may be performed after mixing non-polyolefin resin particles.
Mixing of polyolefin resin particles grafted with a hydrophilic ethylenically unsaturated group-containing monomer and non-grafted polyolefin resin particles is performed using a Henschel mixer, a tumbler mixer, a ladies mixer, a high-speed fluid mixer, or a V-type mixer. However, it is preferable to select an apparatus, mixing conditions, and the like so that particles are not charged during mixing. When the particles are charged, the particles tend to aggregate and uniform mixing may be difficult. It is preferable to neutralize static electricity during particle transportation using an earthing device or a blower-type static eliminator.

There is no particular limitation on the mixing ratio between the polyolefin resin particles grafted with the hydrophilic ethylenically unsaturated group-containing monomer and the non-grafted polyolefin resin particles, but the porous body constituting the sintered body layer laminate is not limited. In order to achieve both strength and water absorbing function, the former is preferably in the range of 10 to 70% by weight, and particularly preferably in the range of 30 to 60% by weight.
In the present invention, the method of grafting the hydrophilic ethylenically unsaturated group-containing monomer is not particularly limited as long as it is a method capable of introducing a hydrophilic ethylenically unsaturated group-containing monomer starting from a radical. Method using plasma generated by corona discharge or glow discharge, method using active gas such as ozone, method using photosensitizer such as benzophenone and acetophenone and actinic light such as ultraviolet ray, method using ionizing radiation, various radical initiation Although a method using an agent is mentioned, a method of generating radicals by irradiation with actinic rays or ionizing radiation is preferable because of excellent uniformity. The ionizing radiation in the present invention is a radiation capable of causing an ionization phenomenon by acting on a substance, and examples thereof include γ-ray, X-ray, β-ray, electron beam, α-ray, etc. Gamma rays that are particularly suitable for generating radicals uniformly are preferred.

The irradiation dose of the ionizing radiation in the present invention is economical because a radical generation amount sufficient to graft the hydrophilic ethylenically unsaturated group-containing monomer is obtained, and unnecessary crosslinking and partial decomposition do not occur. There is no particular limitation as long as it is an irradiation dose, but radicals are uniformly generated, and since there is little influence on the rigidity and chemical resistance of the porous body constituting the sintered body layer laminate, it is in the range of 1 kGy to 1000 kGy. Preferably, it is in the range of 5 kGy to 500 kGy, more preferably in the range of 10 kGy to 300 kGy.
In the present invention, as the method of irradiating with ionizing radiation, polyolefin resin particles or a sintered body thereof and a simultaneous irradiation method of irradiating ionizing radiation in the presence of a hydrophilic ethylenically unsaturated group-containing monomer, After irradiating the sintered body with ionizing radiation, it is broadly classified into a pre-irradiation method in which it is brought into contact with a hydrophilic ethylenically unsaturated group-containing monomer. The method is preferred.

In the pre-irradiation method of the present invention, the contact between the polyolefin resin particles generated with radicals or the sintered body thereof and the hydrophilic ethylenically unsaturated group-containing monomer may be performed in a gas phase or a liquid phase, Although there is no restriction | limiting in particular, The method performed in the liquid phase which can be made to graft more uniformly is preferable. Moreover, in order to improve uniformity, it is preferable to use the hydrophilic ethylenically unsaturated group-containing monomer after dissolving it in a solvent in advance.
In the present invention, the solvent for dissolving the hydrophilic ethylenically unsaturated group-containing monomer is not particularly limited as long as it can be uniformly dissolved, and it is preferable to use a solvent having a low degree of swelling of the polyolefin resin. Among them, a solvent having a degree of swelling of 10% or less is preferable. For example, alcohols such as methanol, ethanol, isopropanol, and tert-butanol, ethers such as diethyl ether and tetrahydrofuran, ketones such as acetone and 2-butanone, water, Or the mixture etc. are mentioned. The degree of swelling in the present invention is the difference between the average particle diameter of polyolefin resin particles immersed in a solvent for 1 hour and the average particle diameter of polyolefin resin particles before immersion, and the average particle diameter of polyolefin resin particles before immersion. The value divided by the diameter.

It is preferable to deaerate the sintered body of polyolefin resin particles that have generated radicals in the pre-irradiation method of the present invention in a reaction vessel before contacting with a hydrophilic ethylenically unsaturated group-containing monomer. By sucking and introducing a hydrophilic ethylenically unsaturated group-containing monomer into the degassed reaction vessel, it can be uniformly grafted into the pores of the sintered body. The degree of vacuum in the reaction vessel at the time of degassing is preferably in the range of 0 to 1340 Pa, more preferably in the range of 0 to 134 Pa, and particularly preferably in the range of 0 to 13.4 Pa.
Although there is no restriction | limiting in particular about the temperature at the time of irradiating ionizing radiation in this invention, In order to suppress the deactivation of the produced | generated radical, it is preferable to exist in the range of -150-0 degreeC, and -100--30 degreeC. It is especially preferable that it is in the range. In addition, after producing | generating a radical in the pre-irradiation method of this invention, it is preferable to keep at the low temperature of -10 degrees C or less until it makes it contact with a hydrophilic ethylenically unsaturated group containing monomer. When not kept at a low temperature, radicals decay rapidly, and for example, the number halves after 30 minutes at room temperature of 25 ° C. Furthermore, radicals may react with a small amount of adsorbed oxygen, which may impair the heat resistance and chemical resistance of the sintered body.

In the present invention, the temperature at which the hydrophilic ethylenically unsaturated group-containing monomer is grafted is not particularly limited as long as it is lower than the melting point of the polyolefin resin particles, but is preferably in the range of 0 to 100 ° C. It is more preferably in the range of 90 ° C, and particularly preferably in the range of 10 to 80 ° C. When the temperature at the time of grafting is lower than 0 ° C., the reaction rate is slow and the reaction may proceed non-uniformly. When the temperature at the time of grafting is higher than 100 ° C., a monomer thermal polymer may be formed, and the pores of the sintered body may be blocked, and further, they may flow out during use. .
In the present invention, when the polyolefin resin particles in which radicals are generated or the sintered body thereof and the hydrophilic ethylenically unsaturated group-containing monomer are brought into contact in the liquid phase, the liquid phase concentration of the hydrophilic ethylenically unsaturated group-containing monomer Although there is no particular limitation, in order to obtain sufficient hydrophilicity without blocking the pores of the hydrophilic polyolefin sintered body, it is preferably in the range of 0.3 to 30% by volume, and 1.0 to 20 volume. % Is more preferable, and 2.0 to 15% by volume is particularly preferable. Incidentally, there is no particular restriction as to the amount of liquid phase, is preferably used in an amount of ^{2 × 10 -6 ~5 × 10 -3} m 3 relative to the polyolefin resin particles from the viewpoint of industrial production or its sintered body 1g It is particularly preferable to use at a ratio of 3 × 10 ^{−6 to} 2 × 10 ⁻³ m ³ .

In the present invention, an ethylenically unsaturated group-containing monomer is grafted in an amount sufficient to develop the water absorption function while maintaining the practical permeability of the porous sintered body made of polyolefin resin particles. Accordingly, the graft ratio of the hydrophilic polyolefin sintered body is preferably in the range of 0.01 to 50%, more preferably in the range of 0.05 to 40%, and in the range of 0.10 to 30%. It is particularly preferred.
The graft ratio in the present invention is a value calculated according to the following formula.
Graft ratio (%) = [(weight after grafting−weight before grafting) / weight before grafting] × 100
In order to increase the welding force, when mixing polyolefin resin particles not grafted with a hydrophilic ethylenically unsaturated group-containing monomer and then sintering molding, the “weight before grafting” of the denominator in the above formula is set. The total weight of polyolefin resin particles including ungrafted polyolefin resin particles.
In the present invention, the water droplet absorption time means that a 35 μl water droplet is placed from the position of 20 mm in height to the center of a sintered body having a length of 50 mm, a width of 50 mm, and a thickness of 2 mm at 25 ° C. under atmospheric pressure. This is the time required for dripping and the entire amount to be absorbed inside the sintered body. The water droplet absorption time in the present invention is not particularly limited, but in order to sufficiently exhibit the water absorption function as the sintered body layer laminate, it is preferably 30 seconds or less, more preferably 10 seconds or less, and more preferably 5 seconds or less. Is particularly preferred.

Further, the water suction height in the present invention means that the lower 20 mm of a sintered body having a thickness of 2 mm, a width of 10 mm, and a height of 100 mm is vertically immersed in 25 ° C. water at 25 ° C. under atmospheric pressure. It is a value obtained by measuring the water uptake distance due to capillary action one minute after. There is no particular limitation on the water suction height in the present invention, but in order to sufficiently exhibit the water absorption function as a sintered body layer laminate, it is preferably 5 mm or more per minute, more preferably 10 mm or more, 15 mm or more is particularly preferable.
In order to confirm the durability of the water absorption function mentioned as a feature of the sintered body layer laminate in the present invention, for example, the water drop absorption time after removing the 60 ° C. hot water soluble component and the water suction height are measured. It ’s fine. Here, a method for removing the 60 ° C. warm water soluble component will be described. First, the sintered body layer laminate to be measured is immersed for 7 hours in a 60 ° C. hot water circulation tank equipped with a unit type thermostatic chamber. Thereafter, moisture remaining in the pores of the sintered body layer laminate is removed and dried. This operation is repeated three times in total to remove the 60 ° C. hot water soluble component. When the hydrophilic layer of the sintered body layer laminate is obtained by coating a 60 ° C. warm water soluble component such as a surfactant or a hydrophilic polymer, the water absorption function is lost by this removal method.

The water drop absorption time after removing the 60 ° C. hot water soluble component in the present invention is not particularly limited, but is preferably 30 seconds or less in order to sufficiently exhibit the water absorption function as the sintered body layer laminate. 10 seconds or less is more preferable, and 5 seconds or less is particularly preferable.
Although there is no restriction | limiting in particular about the sucking height of the water in this invention after removing the 60 degreeC warm water soluble component in this invention, In order to fully exhibit a water absorption function as a sintered compact layer laminated body, it is 1 minute Is preferably 5 mm or more, more preferably 10 mm or more, and particularly preferably 15 mm or more.
The water used in the present invention removes impurities, metal ions and the like by filtration, distillation, reverse osmosis, ion exchange, or a combination thereof, and pure water having a resistivity of 50,000 Ω · cm or more is used. It is desirable to use it.

The airflow resistance of the sintered body layer laminate in the present invention is a value of pressure loss measured based on the method described later, and is not particularly limited, but ensures air permeability as the sintered body layer laminate, and In order to sufficiently exhibit the water absorption function, the thickness is preferably 300 to 2000 mmAq, more preferably 400 to 1500 mmAq, and particularly preferably 500 to 1000 mmAq.
Next, although an example and a comparative example explain the present invention, the present invention is not limited to these examples.

[Measurement of average porosity]
The average porosity in Examples and Comparative Examples of the present invention was calculated according to the following formula.
Average porosity (volume%) = [(true density−apparent density) / true density] × 100
Here, the true density (g / cm ³ ) is the density of the polyolefin resin particles, and the apparent density (g / cm ³ ) is the volume calculated from the outer dimensions of the sintered body. Divided value.
[Measurement of average pore diameter]
The average pore diameter in Examples and Comparative Examples of the present invention was determined using an automatic porosimeter autopore IV9510 manufactured by Shimadzu Corporation. The measurement conditions were a low pressure part measurement range of 0.54 to 40 psia, a low pressure part measurement point of 46 points, a high pressure part measurement range of 50 to 6000 psia, and a high pressure part measurement point of 43 points.

[Removal of 60 ° C hot water soluble components]
The removal of the 60 ° C. hot water-soluble component in Examples and Comparative Examples of the present invention was performed by the following method. First, in a hot water circulating tank, 8000 cm ³ of water is set in a poly water tank having an internal volume of 335 mm in length, 190 mm in width, and 155 mm in depth, to which a thermominder SH-12 manufactured by Taitec Co., Ltd. is attached. The sintered body to be measured was immersed for 7 hours. Thereafter, moisture remaining in the pores of the sintered body was removed and dried. This operation was repeated a total of 3 times to remove 60 ° C. warm water soluble components. In addition, ion-exchanged water (manufactured by Okayama Kisui Kogyo Co., Ltd., having a resistivity at the time of sampling of 2 million Ω · cm or more) was used as water in Examples and Comparative Examples of the present invention.

[Measurement of water drop absorption time]
The water droplet absorption time in the examples and comparative examples of the present invention is the micrometer manufactured by Eppendorf Co., Ltd. in the center of a sintered body having a length of 50 mm, a width of 50 mm, and a thickness of 2 mm, which is placed horizontally at 25 ° C. under atmospheric pressure. Using a pipette, 35 μl of water droplets were dropped from a position with a height of 20 mm, and the time until the entire amount was absorbed inside the sintered body was measured.
[Measurement of water suction height]
In the examples of the present invention and comparative examples, the suction height of water was 25 ° C. under atmospheric pressure, and the lower 20 mm of the sintered body having a thickness of 2 mm, a width of 10 mm, and a height of 100 mm was vertically placed in 25 ° C. water. It was determined by dipping and measuring the water uptake distance by capillary action 1 minute after dipping.

[Measurement of average particle size]
The average particle diameter of the polyolefin resin particles in the present invention is a particle diameter at which the cumulative weight is 50%, that is, a median diameter.
The average particle diameter of the polyolefin resin particles in Examples and Comparative Examples of the present invention was determined by measuring with methanol as a dispersion medium using SALD-2100 manufactured by Shimadzu Corporation.
[Measurement of bulk density]
The bulk density of the polyolefin resin particles in Examples and Comparative Examples of the present invention was determined by measuring according to JIS K 6892 without adding additives such as a lubricant to the polyolefin resin particles.

[Density measurement]
The density of the polyolefin resin particles in Examples and Comparative Examples of the present invention was obtained by annealing a section cut out from a press sheet of polyolefin resin particles at 120 ° C. for 1 hour and then cooling at 25 ° C. for 1 hour as a sample for density measurement. Used, and determined by measuring according to JIS K 7112. The polyolefin resin particle press sheet was prepared in accordance with ASTM D 1928 Procedure C using a mold having a length of 60 mm, a width of 60 mm, and a thickness of 2 mm.

[Measurement of viscosity average molecular weight]
The viscosity average molecular weight of the polyolefin resin particles in Examples and Comparative Examples of the present invention was determined by the method shown below. First, 10 mg of polymer was added to 20 cm ³ of decalin (decahydronaphthalene) and stirred at 150 ° C. for 2 hours to dissolve the polymer. The drop time (t _s ) between the marked lines was measured using a Ubbelohde type viscometer for the solution in a thermostatic bath at 135 ° C. Similarly, the measurement was performed for a polymer of 5 mg. The falling time (t _b ) of only decalin without a polymer as a blank was measured. The specific viscosity (η _sp / C) of the polymer determined according to the following equation is plotted to derive a linear expression of the concentration (C) and the specific viscosity of the polymer (η _sp / C), and the intrinsic viscosity extrapolated to a concentration of 0 (Η) was determined.
_{η sp / C = (t s} / t b -1) /0.1
From this intrinsic viscosity (η), the viscosity average molecular weight (Mv) was determined according to the following formula.
Mv = 5.34 × 10 ⁴ η ^1.49

[Measurement of ventilation resistance]
The airflow resistance of the suction sheets in Examples and Comparative Examples of the present invention was determined by the following method. First, a PVC hose with an inner diameter of 6 mm was used, and a flow meter, a pressure gauge, and a rubber cup with an inner diameter of 20 mm were connected as shown in FIG. Compressed air of 1 kg / cm ² was flowed at a flow rate of 50 normal liters / minute at 25 ° C., and the entire surface of the edge of the rubber cup was closed so as to be in close contact with the sintered sheet, and the value indicated by the pressure gauge was measured. An average value was calculated by measuring a total of 6 points at an equal interval for one sintered sheet, and was used as a ventilation resistance.

[Example 1]
Using an aluminum plate having a thickness of 2 mm, a mold having an outer dimension of 6 mm thickness, a width of 112 mm, a height of 108 mm, an inner dimension of a thickness of 2 mm, a width of 100 mm, and a height of 100 mm was created. The aluminum plate serving as the upper lid of the mold was removed, and while vibrating with a vibrator for 30 seconds, the average particle size was 277 μm, the bulk density was 0.45 g / cm ³ , the density was 0.955 g / cm ³ , and the viscosity average molecular weight was 30 Ten thousand high density polyethylene powder (Sunfine ^TM SH821 manufactured by Asahi Kasei Chemicals Corporation) was filled. After returning the upper lid, the plate-shaped sintered body was prepared by heating in an oven at 150 ° C. for 25 minutes.

The above sintered body was immersed in a solution of 1 g of benzophenone (manufactured by Aldrich) in 1000 cm ³ of acetone for 1 minute under light shielding, and then the dried sintered body was dried under reduced pressure for 1 hour in the state of light shielding. A 0.25 mmol / cm ³ aqueous solution of 2-methacryloyloxyethyl phosphorylcholine (manufactured by Nippon Oil & Fats Co., Ltd.) was prepared, and dissolved oxygen was removed by nitrogen bubbling at 40 ° C. for 30 minutes. The above sintered body treated with an acetone solution of benzophenone was fixed in 1200 cm ^{3 of} this solution to 60 ° C., and irradiated with ultraviolet rays for 90 minutes using a high pressure mercury lamp UVL-400HA (manufactured by Riko Kagaku Sangyo Co., Ltd.). Thereafter, distilled water 1200 cm ³ and methanol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) after the 1200 cm ³ each was immersed for 8 hours at 25 ° C. and washed, this washing operation was repeated three times, followed by drying A hydrophilic porous sintered body having a graft rate of 0.40% was obtained.

Next, using an aluminum plate having a thickness of 2 mm, a mold having an outer dimension of 8 mm thickness, a width of 112 mm, a height of 108 mm, an inner dimension of a thickness of 4 mm, a width of 100 mm, and a height of 100 mm was created. After removing the aluminum plate serving as the upper lid of the mold and inserting the above hydrophilic porous sintered body, the mold is tilted 45 degrees in the thickness direction to create a space portion, and the average particle size is 277 μm in the space portion, A high density polyethylene powder (Sunfine ^TM SH821 manufactured by Asahi Kasei Chemicals Corporation) having a bulk density of 0.45 g / cm ³ , a density of 0.955 g / cm ³ , and a viscosity average molecular weight of 300,000 is vibrated with a vibrator for 30 seconds. While filling. After returning the upper lid, it was heated in an oven at 150 ° C. for 25 minutes to obtain a flat sintered body layer laminate.
When 35 μl of water droplets were dropped on the hydrophilic layer surface of the obtained sintered body layer laminate from a position having a height of 20 mm, the water droplets were absorbed. On the other hand, water droplets were similarly dropped on the hydrophobic layer surface, but water was not absorbed.

  The sintered body layer laminate obtained by the present invention has a hydrophilic layer and a hydrophobic layer laminated, has a long-lasting water absorption function and low elution, and allows water absorbed on one side to permeate the opposite side. Excellent formability, impact resistance, mechanical strength and dimensional stability at the time of water absorption, and overall good air permeability, for example, when used as a condensed water absorber in a refrigerator vegetable room The hydrophilic layer absorbs condensed water in the vegetable room and has the function of prolonging the stored vegetables without dropping water in the vegetable room. The hydrophobic layer is a layer in which the juice from the upper food is hydrophilic. So that the condensed water adhering to the refrigerator wall does not fall into the hydrophilic layer and is absorbed. Moreover, since the sintered body layer laminate has good air permeability, it can be expected that the water vapor in the vegetable compartment is prevented from being supersaturated, and further, the circulation of the cold air is improved and the cooling efficiency is increased.

It is a figure which shows the structure of the installation which measures ventilation resistance in this invention.

Claims (5)

  A polyolefin porous sintered body laminate having at least a hydrophilic layer and a hydrophobic layer, each layer being directly bonded and laminated, and a ventilation resistance in the thickness direction of 300 to 2000 mmAq, The hydrophilic layer is grafted with a hydrophilic ethylenically unsaturated group-containing monomer having at least one functional group selected from a phosphorylcholine group, a hydroxyl group, a carboxyl group, an amino group, an amide group, a sulfonic acid group or a salt thereof. A sintered body layer laminate comprising a hydrophilic polyolefin sintered body.   The sintered body layer laminate according to claim 1, wherein the graft ratio of the hydrophilic ethylenically unsaturated group-containing monomer is 0.01 to 50%. A hydrophilic ethylenically unsaturated group-containing monomer having a phosphorylcholine group is represented by the following general formula (1):

(In the general formula (1), R ¹ is a hydrogen atom or a methyl group, and n is an integer of 2 to 10.)
The sintered body layer laminate according to claim 1 or 2, which is at least one monomer selected from methacryloyloxyalkylphosphorylcholine or acryloyloxyalkylphosphorylcholine represented by formula (1).   The sintered body layer laminate according to any one of claims 1 to 3, wherein the hydrophilic ethylenically unsaturated group-containing monomer having a phosphorylcholine group is 2-methacryloyloxyethyl phosphorylcholine.   The sintered body layer laminate is composed of a sintered body of polyolefin resin particles, and the polyolefin resin particles are an ethylene homopolymer or a copolymer of ethylene and an olefin having 3 or more carbon atoms, The sintered body layer laminate according to any one of claims 1 to 4.

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