JP5915922B2 - Laminated body and method for producing the same - Google Patents

Description

  The present invention relates to a laminate, and more particularly to a laminate in which a polyolefin nonwoven fabric and a polyethersulfone resin porous membrane are bonded without using an adhesive and a method for producing the same.

  Nonwoven fabrics that have been formed into a web-like shape obtained by fiberizing various polymer materials such as polyolefin resins, polyester resins, and polyamide resins are widely used. These non-woven fabrics are used for applications that exhibit various functions depending on the characteristics of the polymer material used and the characteristics of the fibers, and can exhibit these functions.

  In addition, various non-woven fabrics may be used alone, but non-woven fabrics made of different polymer materials can be layered to form a laminate of non-woven fabrics, or non-woven fabrics and films can be bonded together to express higher functionality. Processing into such a form is also performed. When forming such a laminated body, two types of non-woven fabrics are superposed using an adhesive (laminate resin), or a non-woven fabric and a film are superposed and bonded. Further, depending on the material of the nonwoven fabric or the film, heat sealing, that is, applying heat, softening and melting one or both fibers or films and bonding the materials to each other is performed.

  However, when a nonwoven fabric or film made of different materials is bonded via a laminate resin to form a laminate, the laminate resin may block the opening of the nonwoven fabric, and the inherent performance of the nonwoven fabric may deteriorate. In addition, the laminate resin component may gradually elute or volatilize from the laminate to the outside. Especially in the medical field where safety and cleanliness are important, depending on the laminate resin used, the laminate resin component may be packaged in a nonwoven fabric laminate. In some cases, the contents may be contaminated. Furthermore, depending on the field of use of the nonwoven fabric laminate, the laminate resin itself may deteriorate due to long-term use, and particularly in exterior applications used outdoors, the weather resistance of the laminated laminate may become a problem. there were. On the other hand, when a laminated body is formed by bonding non-woven fabrics or a non-woven fabric and a film to form a laminate, the above-mentioned problems do not occur because the laminate resin is not used. In some cases, it could not be sealed, or the adhesive strength was weak and it could not withstand practical use.

  By the way, surface modification of a material using radiation or an electron beam has been conventionally performed. For example, Japanese Patent Application Laid-Open No. 2003-119293 (Patent Document 1) proposes that a crosslinked composite fluororesin can be obtained by irradiating the fluororesin with radiation. In Journal of Photopolymer Science and Technology Vol.19, No. 1 (2006), pp123-127 (Non-patent Document 1), a polytetrafluoroethylene film and a polyimide film are laminated and an electron beam ( In the following, it has been proposed to bond each other by irradiating EB. In Material Transactions Vol.50, No.7 (2009), pp1859-1863 (Non-patent Document 2), the surface of the polycarbonate resin is covered with a nylon film, and an electron beam (hereinafter abbreviated as EB) may be applied from above. A technique for adhering a nylon film to a polycarbonate resin surface has been proposed. Furthermore, the Journal of the Japan Institute of Metals, Vol. 72, No. 7 (2008), pp 526-531 (Non-patent Document 3) can be bonded to each other by irradiating EB from a nylon film placed on silicone rubber. Is described.

JP 2003-119293 A

Journal of Photopolymer Science and Technology Vol.19, No. 1 (2006), pp123-127 Material Transactions Vol.50, No. 7 (2009), pp1859-1863 Journal of the Japan Institute of Metals, Vol. 72, No. 7 (2008), pp 526-531

  The present inventors have now found that even when dissimilar materials are bonded to each other, by irradiating the surface of the material to be bonded with an electron beam, they can be firmly bonded to each other without using a laminate resin or the like. It was. And even if it is a laminate that has been conventionally bonded to each other by an adhesive or heat seal processing, such as a laminate of polyolefin nonwoven fabric and polyethersulfone resin porous membrane, Acquired knowledge that a covalent bond or a hydrogen bond is formed between an atom on the polyolefin nonwoven fabric side and an atom on the polyethersulfone resin porous membrane side, so that they can be firmly bonded to each other without using an agent. It was. The present invention is based on this finding.

  Accordingly, an object of the present invention is a laminate in which a polyolefin nonwoven fabric and a polyethersulfone resin porous membrane are bonded without using an adhesive, and no foreign matter or residual solvent is leached, and the nonwoven fabric Another object of the present invention is to provide a laminate in which a nonwoven fabric and a porous membrane are firmly bonded without deteriorating the original performance of the porous membrane.

The laminate according to the present invention is a laminate in which a polyolefin nonwoven fabric and a polyethersulfone resin porous membrane are laminated,
In at least a part of the polyolefin nonwoven fabric and the polyethersulfone resin porous membrane, a bond is formed between an atom in the polyolefin nonwoven fabric and an atom in the polyethersulfone resin porous membrane, and the polyolefin The nonwoven fabric and the polyethersulfone resin porous membrane are bonded without using an adhesive.

  Further, as an aspect of the present invention, an oxygen atom or a hydroxyl group is bonded to an atom in the polyolefin nonwoven fabric and the polyethersulfone resin porous membrane, and the oxygen atom and / or hydroxyl group in the polyolefin nonwoven fabric and the polyethersulfone It is preferable that a bond is formed between an oxygen atom or a hydroxyl group in the resin porous membrane.

  Moreover, as an aspect of the present invention, the polyolefin nonwoven fabric is preferably composed of fibers made of polyethylene, polypropylene, or polymethylpentene, or composite fibers having these resins as sheaths.

Moreover, the production method as another aspect of the present invention is a method for producing a laminate in which a polyolefin nonwoven fabric and a polyethersulfone resin porous membrane are laminated,
Irradiating at least one surface of the polyolefin nonwoven fabric and / or the polyethersulfone resin porous membrane with an electron beam,
The polyolefin non-woven fabric surface and / or the polyethersulfone resin porous membrane surface irradiated with the electron beam are superposed and bonded together.

  Moreover, it is preferable to perform electron beam irradiation before and / or after superimposing the polyolefin nonwoven fabric and the polyethersulfone resin porous membrane.

  Moreover, as another aspect of the present invention, the bonding is preferably performed by applying pressure, and the bonding is preferably performed by heating.

  According to the present invention, in the laminate in which the polyolefin nonwoven fabric and the polyethersulfone resin porous membrane are laminated, the atoms in the polyolefin nonwoven fabric and the atoms in the polyethersulfone resin porous membrane are directly or via oxygen atoms. In addition, since the bond is formed, a laminate in which the polyolefin nonwoven fabric and the polyethersulfone resin porous film are firmly bonded can be obtained even if they are not bonded via an adhesive. As a result, it is possible to realize a laminated body in which the nonwoven fabric and the porous membrane are firmly bonded without exuding foreign matter or residual solvent and without deteriorating the original performance of the nonwoven fabric and the porous membrane. it can.

It is the schematic sectional drawing which showed one Embodiment of the laminated body of this invention. It is the schematic cross section which expanded the interface (adhesion surface) of the laminated body. It is the schematic diagram which showed one Embodiment of the manufacturing method of the laminated body by this invention. It is the schematic schematic diagram which expanded a part of manufacturing process. It is the schematic diagram which showed another embodiment of the manufacturing method of the laminated body by this invention. It is the schematic diagram which showed another embodiment of the manufacturing method of the laminated body by this invention. It is the schematic diagram which showed another embodiment of the manufacturing method of the laminated body by this invention.

  Hereinafter, the laminated body by this invention is demonstrated, referring drawings. As shown in FIG. 1, the laminate according to the present invention has a structure in which a polyolefin nonwoven fabric 1 is laminated on at least one surface of a polyethersulfone resin porous membrane 2 without an adhesive.

  The laminate according to the present invention is at least part of the adhesion surface of the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2 and between the carbon atoms in the polyolefin nonwoven fabric and the atoms in the polyethersulfone resin porous membrane. By forming the bond, the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2 are firmly bonded. Usually, even if a polyester non-woven fabric is laminated on the surface of a polyolefin non-woven fabric, hydrogen bonds and covalent bonds are not formed between the two, so that the two cannot be bonded without using an adhesive or heat sealing. In the present invention, as will be described later, the surface of the polyolefin nonwoven fabric 1 and / or the polyethersulfone resin porous membrane 2 is irradiated with an electron beam to generate radicals. As shown in FIG. Between the carbon atoms on the surface of the polyolefin non-woven fabric 1 and the atoms on the surface of the polyether sulfone resin porous membrane 2. By forming a bond through atoms, the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2 are firmly bonded without using an adhesive. Further, radicals generated by electron beam irradiation and oxygen in the air are combined, and there may be OH groups on the surface of the polyolefin nonwoven fabric 1 and / or the polyethersulfone resin porous membrane 2, In some cases, the OH group on the polyolefin nonwoven fabric 1 side and the OH group or sulfonyl group on the polyether sulfone resin porous membrane 2 side or oxygen atoms in the ether portion form a bond. The generation of radicals by electron beam irradiation is determined by identifying the free radical species present in the nonwoven fabric and porous film after electron beam irradiation using an electron spin resonance apparatus (hereinafter also referred to as ESR). Occurrence can be confirmed.

  The fact that a bond is formed between atoms between the polyolefin nonwoven fabric and the polyethersulfone resin porous membrane means that an X-ray photoelectron analyzer (hereinafter also referred to as XPS) or a Fourier transform infrared spectrometer (hereinafter referred to as XPS). (Also referred to as FTIR). For example, before bonding a polyolefin nonwoven fabric and a polyethersulfone resin porous membrane, by measuring the surface state of each nonwoven fabric (fiber) and the porous membrane by XPS, Confirm that there are atoms, bond them together by electron beam irradiation to make a laminate, then forcibly peel the laminate and separate it into a polyolefin nonwoven fabric and a polyethersulfone resin porous membrane, The surface state of both is measured by XPS to confirm what atoms are present. As a result, by confirming that there are atoms derived from the porous membrane on the surface of the nonwoven fabric, or whether there are atoms derived from the nonwoven fabric on the surface of the porous membrane, it is confirmed whether a bond is formed between them. Can do. Moreover, you may confirm whether the coupling | bonding derived from another base material exists in the surface of the base material after peeling using FTIR.

  Moreover, since the laminated body which adhere | attached the polyolefin nonwoven fabric 1 and the polyether sulfone resin porous membrane 2 by electron beam irradiation as shown in FIG. 2, bonds, such as a covalent bond mentioned above and a hydrogen bond, are formed, Even if an adhesive is not used at all, a laminate that does not peel off can be obtained. The presence of hydrogen bonds can be confirmed by immersing the laminate in water or an alcohol solution and confirming the presence or absence of peeling. When the polyolefin nonwoven fabric and the polyethersulfone resin porous membrane are bonded only by hydrogen bonds, when the laminate is immersed in water or an alcohol solution, the hydrogen bonds formed between the two are broken and water is lost. Alternatively, hydrogen bonds with alcohol hydrogen atoms or oxygen atoms are re-formed, so that the adhesive force is lost and peeling occurs. Therefore, it can be confirmed whether the adhesion is due to a covalent bond and a hydrogen bond or only due to a hydrogen bond.

  Hereinafter, the polyolefin nonwoven fabric and the polyethersulfone resin porous film which comprise the laminated body by this invention are demonstrated.

<Polyolefin non-woven fabric>
The polyolefin nonwoven fabric constituting the laminate of the present invention can be obtained by making a fiber made of polyolefin resin into a nonwoven fabric. The polyolefin resin may be a simple substance such as low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, or a mixture of polypropylene and low density polyethylene, or a mixture of polypropylene and high density polyethylene. Can be used.

  In addition, the polyolefin nonwoven fabric used in the present invention may be a nonwoven fabric composed of a composite fiber having a core-sheath structure. For example, a composite composed of a core made of a polyester resin or a polyamide resin, and a sheath made of the above-described polyolefin resin. A fiber etc. can also be used conveniently.

  Conventionally known various additives such as a light stabilizer, an ultraviolet absorber, an antioxidant, a filler, a lubricant and the like can be appropriately added to the above-described polyolefin resin as necessary. Conventionally known light stabilizers and ultraviolet absorbers can be used. For example, phenol-based, phosphorus-based, hindered amine-based light absorbers, benzotriazole-based, benzophenone-based, and salicylic acid ester-based ultraviolet absorbers are used. it can.

  In order to make the fiber made of the above-mentioned resin into a non-woven fabric, a web is prepared by a conventional method using a card machine such as a roller card or a flat card that is usually used. The production of the nonwoven fabric from the web may be carried out by appropriately selecting a conventionally known method such as a heat fusion method, a spunbond method, a melt blow method, or a solvent-based flash spinning method according to the intended use of the nonwoven fabric. . Further, the entangled fibers may be heat-sealed to form a nonwoven fabric. As the polyolefin nonwoven fabric, commercially available ones may be used. For example, Eltus series (manufactured by Asahi Kasei Fibers Co., Ltd.), Elves (manufactured by Unitika Ltd.) and the like can be suitably used.

  In the present invention, the laminated nonwoven fabric has a thickness of about 20 to 800 μm.

<Polyethersulfone resin porous membrane>
The polyethersulfone resin porous membrane constituting the laminate of the present invention is a polyethersulfone resin made into a porous membrane by a known method, and is described in, for example, JP-A-60-41503. Thus, it can produce by the phase-separation method from the film forming solution which melt | dissolved polyether sulfone in the solvent.

  As a film forming solution, a polyethersulfone resin is dissolved in a polar solvent such as dimethyl acetate, N, N′-dimethylformamide, N, N′-dimethylacetamide, N-methyl-2-pyrrolidone, or pyridine. . After this film-forming solution is coated on a support such as a polyester film and dried, the coated film is immersed in a coagulating liquid and dried to obtain a porous film. The above solvents used for the film-forming solution include methanol, ethanol, propyl alcohol, ethylene glycol, diethylene glycol and polyethylene glycol, in order to adjust the solidification rate at the time of forming the porous film and adjust the pore size and pore size distribution, Alcohols such as polypropylene glycol and ketones such as acetone and methyl ethyl ketone may be added.

  Water is generally used as the coagulation liquid, but an organic solvent that does not dissolve the polyethersulfone may be used. These organic solvents only need to be miscible with water in order to adjust the coagulation rate, the pore size of the porous membrane and its distribution. For example, methanol, ethanol, propyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, polyethylene Examples thereof include alcohols such as glycol, ketones such as acetone and methyl ethyl ketone, and amide solvents such as N, N′-dimethylformamide, N, N′-dimethylacetamide and N-methyl-2-pyrrolidone. Among these, glycols such as ethylene glycol and polyethylene glycol, N-methyl-2-pyrrolidone, N, N′-dimethylacetamide, N, N′-dimethylformamide and the like from the viewpoint of uniformity in the porous film having a pore size The amide solvent is preferred.

  Further, in the present invention, the adhesive surface with the polyolefin nonwoven fabric described above may be a polyethersulfone resin porous membrane, and therefore, the polyethersulfone resin porous membrane and other functional membranes, substrate films, etc. You may use the laminated film which laminated | stacked.

  The thickness of the polyethersulfone resin porous membrane is generally about 1 μm to 5 mm, and particularly preferably about 10 to 300 μm, although it depends on the application used.

  The laminated body in which the polyolefin nonwoven fabric and the polyethersulfone resin porous film as described above are laminated and adhered does not exude foreign matter, residual solvent, etc. even when the laminated body is used. Therefore, it can be suitably used for packaging bodies used in the medical field, such as syringe packaging bags, packaging bodies for filling and packaging powdered or granular pharmaceuticals, various filters, etc., not to mention the food field. it can. Further, since the laminate resin processing and the heat seal processing are not performed, the opening portions of the nonwoven fabric and the porous membrane are not blocked by the adhesion, so that the original performance of the nonwoven fabric and the porous membrane is not deteriorated.

<Method for producing laminate>
Next, a method for producing the laminate as described above will be described with reference to the drawings. First, the above-described polyolefin nonwoven fabric 1 and polyethersulfone resin porous membrane 2 are prepared (FIG. 3 (1)), and either or both of the nonwoven fabrics are irradiated with an electron beam ( FIG. 3 (2)). As a result, as shown in FIG. 3 (3), the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2 are bonded only to the portion irradiated with the electron beam.

  In the present invention, it is preferable to press the overlapped nonwoven fabric 1 and porous membrane 2 using a roller 6 or the like as shown in FIG. The surface of the nonwoven fabric 1 (that is, the surface of the fiber) and the surface of the porous membrane 2 are uneven at the micro level as shown in FIG. The contact area at the contact interface between the two is small. In the present invention, immediately after irradiating the electron beam, pressing the nonwoven fabric 1 and the porous membrane 2 with the roller 6 or the like increases the contact area on the bonding surface between them, so that the adhesion is improved.

  After the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2 are overlaid, when pressing both 1, 2, it is preferable to press the nonwoven fabric 1 and the porous membrane 2 while heating. By pressing while heating, the flexibility of the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2 is improved, and the contact area at the interface (adhesive surface) between the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2 is improved. Can be further increased, and the adhesion is further improved. The heating temperature may be any temperature at which the nonwoven fabric and the porous membrane can be thermally deformed, depending on the type of the nonwoven fabric and the porous membrane to be used. For example, the heating temperature is higher than the glass transition temperature of the polyolefin resin constituting the nonwoven fabric. be able to. For example, when a polypropylene nonwoven fabric is used as the polyolefin nonwoven fabric, the heating temperature is 80 to 180 ° C, preferably 100 to 160 ° C. If the heating temperature is too high, the generated radicals are deactivated, and a strong bond cannot be realized. The pressing force (contact pressure) may be increased, and the heating temperature can be lowered by increasing the contact pressure.

  In order to overlap and press the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2, the heat roller 6 or the like can be suitably used as described above. Further, as shown in FIG. 4, the support roller 7 is placed at a position facing the heat roller 6 so that the laminated nonwoven fabric and the porous film can be pressed against each other between the heat roller 6 and the support roller 7. May be. In this way, by placing the support roller 7 at a position facing the heat roller 6, the contact between the laminate (a laminate of the nonwoven fabric 1 and the porous film 2) and the heat roller 6 is brought close to line contact, and heat is applied. Deformation that occurs in the laminate due to heat from the roller 6 can be minimized.

  FIG. 5 is a schematic view showing another embodiment of the manufacturing method according to the present invention. In the process of laminating and bonding the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2, both 1 and 2 are respectively guided to the electron beam irradiation position 3 by the guide roller, and both 1 and 2 are irradiated with the electron beam 4. The process of pressing both 1 and 2 by the heat roller 6 is continuously performed later. The nonwoven fabric 1 and the porous membrane 2 may be supplied in a roll form.

  When irradiating the electron beam 4 from the electron beam irradiation apparatus 3 to the nonwoven fabric 1 and the porous film 2, it is preferable to irradiate the electron beam 4 from the side where the thickness is smaller. Since the electron beam has the property that the transmission power increases as the acceleration voltage increases, depending on the thickness of the nonwoven fabric and the porous membrane when the electron beam is irradiated from either side of the nonwoven fabric or the porous membrane. May not reach the other nonwoven fabric (or porous membrane). In that case, the electron beam can reach the deep part of the other nonwoven fabric (porous membrane) by increasing the acceleration voltage of the electron beam, but the nonwoven fabric (porous) increases as the electron beam energy increases. The film) itself is subjected to unnecessary irradiation and deteriorates. Therefore, when the thick porous film and the thin nonwoven fabric are overlapped and bonded, it is preferable to irradiate the electron beam from the thin nonwoven fabric side without significantly increasing the electron beam energy. For example, when the thickness of the polyolefin nonwoven fabric is 25 μm or less and the thickness of the polyethersulfone resin porous membrane is 50 μm or more, an electron beam is irradiated from the polyolefin nonwoven fabric side. By adopting such an electron beam irradiation method, deterioration of the nonwoven fabric and the porous film can be minimized.

  When both the nonwoven fabric 1 and the porous membrane 2 to be stacked are thick, another electron is placed at a position facing the electron beam irradiation device 3 so that an electron beam can be irradiated from both sides as shown in FIG. A line irradiation device 3 ′ may be provided. According to this aspect, since the irradiation energy of the electron beam can be adjusted according to the thickness of the nonwoven fabric and the porous membrane, the nonwoven fabric and the porous membrane can be bonded without deteriorating the nonwoven fabric and the porous membrane. it can.

  FIG. 6 is a schematic view showing an embodiment of another manufacturing method according to the present invention. In this embodiment, the electron beam irradiation is performed before the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2 are overlapped. First, the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2 that have been supplied are transferred to the nonwoven fabric 1 (porous membrane 2) by means of an electron beam irradiation device 3 (3 ′) before both 1 and 2 are superimposed. The electron beam 4 (4 ′) is irradiated. In the embodiment shown in FIG. 5, both the layers 1 and 2 are overlapped so that the surfaces opposite to the electron beam irradiation side of the nonwoven fabric 1 (porous membrane 2) face each other, whereas the embodiment shown in FIG. In an aspect, the point which superimposes both 1 and 2 is different so that the surface by the side of the electron beam irradiation of the nonwoven fabric 1 and the porous membrane 2 may oppose. In this way, by superposing the other porous membrane 2 on the surface of the nonwoven fabric 1 irradiated with the electron beam, the irradiation energy of the electron beam can be made smaller regardless of the thickness of the nonwoven fabric and the porous membrane. As a result, the deterioration of the nonwoven fabric and the porous membrane due to electron beam irradiation can be further reduced.

  Also in the embodiment shown in FIG. 6, a pair of electron beam irradiation devices 3 and 3 ′ are provided, and the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2 are formed as in the embodiment shown in FIG. 5. Each may be irradiated with electron beams 4, 4 ′. By these combinations, the deterioration of the nonwoven fabric and the porous membrane can be further reduced and the adhesive strength can be improved.

  FIG. 7 is a schematic view showing another embodiment of the manufacturing method according to the present invention. In this embodiment, the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2 are superposed and pressed by the heat roller 6 and then irradiated with an electron beam. First, the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2 that have been supplied are led to a guide roller and superimposed. Subsequently, the nonwoven fabric 1 and the porous film 2 are pressed by the heat roller 6 and the support roller 7, and heating is performed by the heat roller 6. Thereafter, the electron beam irradiation device 3 irradiates the surfaces of the polyolefin nonwoven fabric 1 and the polyethersulfone resin porous membrane 2 with the electron beam 4 so that the bonding of the two is continued. Also in the embodiment shown in FIG. 7, a pair of electron beam irradiation devices 3 and 3 ′ are provided, and both the electron beams 4 and 4 ′ are respectively supplied to both 1 and 2 similarly to the embodiment shown in FIGS. May be irradiated. By these combinations, the deterioration of the nonwoven fabric and the porous membrane can be further reduced and the adhesive strength can be improved.

  The irradiation energy of the electron beam needs to be adjusted as appropriate according to the thickness of the nonwoven fabric and the porous film as described above. In the present invention, the electron beam is irradiated in an irradiation energy range of about 20 to 750 kV, preferably 25 to 400 kV, and more preferably about 30 to 300 kV. However, the irradiation energy is preferably lower, and 40 to 200 kV. Can do. By using low irradiation energy in this way, not only can the deterioration of the nonwoven fabric and porous membrane be suppressed, but also the generation of radicals on the surface of the nonwoven fabric and porous membrane will be more efficient, realizing a stronger bond. Can do. The absorbed dose of the electron beam is 10 to 800 kGy, preferably 25 to 600 kGy.

  As such an electron beam irradiation apparatus, conventionally known ones can be used. For example, a curtain type electron irradiation apparatus (LB1023, manufactured by I. Electron Beam Co., Ltd.) or a line irradiation type low energy electron beam irradiation apparatus (EB-ENGINE). , Manufactured by Hamamatsu Photonics Co., Ltd.) can be preferably used.

  When irradiating with an electron beam, the oxygen concentration is preferably 100 ppm or less. This is because irradiation with an electron beam in the presence of oxygen generates ozone and may adversely affect the environment. In order to set the oxygen concentration to 100 ppm or less, the nonwoven fabric may be irradiated with an electron beam under vacuum or an inert gas atmosphere such as nitrogen or argon. For example, by filling the electron beam irradiation apparatus with nitrogen, A concentration of 100 ppm or less can be achieved.

  The laminate obtained by laminating the polyolefin nonwoven fabric and the polyethersulfone resin porous film obtained by the above-described adhesion method can realize an adhesive strength equal to or higher than that obtained by using a conventional laminate resin. In addition, since no laminate resin or the like is used, foreign matter, residual solvent, and the like do not ooze out when the laminate is used, and light shielding properties and gas non-permeability are excellent.

<Preparation of polyolefin nonwoven fabric and polyethersulfone resin porous membrane>
A polyolefin nonwoven fabric (Elves T0303WDO, manufactured by Unitika Ltd.) having a thickness of 160 μm was prepared as a polyolefin nonwoven fabric, and a polyethersulfone resin porous membrane having a thickness of 100 μm was prepared according to the method described in JP-A-60-41503. Prepared.

Example 1
<Production of laminate>
Samples obtained by cutting the polyolefin nonwoven fabric and the polyethersulfone resin porous membrane into a size of 150 mm × 75 mm were prepared, and an electron beam irradiation device (line irradiation type low energy electron beam irradiation device EES-L-DP01, Hamamatsu) was prepared. It was placed side by side on a sample stand of Photonics Co., Ltd. At this time, in order to provide a portion where the sample is not irradiated with the electron beam, masking is performed on one end portion of both samples of about 5 to 10 mm.

Next, after purging with nitrogen gas so that the oxygen concentration in the chamber of the electron irradiation apparatus becomes 100 ppm or less, the surface of the sample was irradiated with an electron beam under the following electron beam irradiation conditions.
Voltage: 40 kV
Absorbed dose: 200kGy
In-device oxygen concentration: 100 ppm or less

  After irradiating the electron beam, the sample was taken out from the apparatus, immediately overlapped so that both electron beam irradiation surface sides faced each other, and both were bonded by a thermal laminating method to obtain a laminate.

Comparative Example 1
A laminate was obtained in the same manner as in Example 1 except that electron irradiation was not performed. However, the obtained laminate was not adhered to the polyolefin nonwoven fabric and the polyethersulfone resin porous membrane.

<Evaluation of adhesive strength of laminate>
The obtained laminate was cut into a strip shape with a width of 15 mm, and a 90 ° peel test was performed at a rate of 50 mm / min using a tensile tester (Tensilon Universal Material Tester RTC-1310A, manufactured by ORIENTEC). went. In addition, as above-mentioned, the laminated body of the comparative example 1 did not adhere | attach the polyolefin nonwoven fabric and the polyether sulfone resin porous membrane, and could not measure the adhesive strength of a laminated body. The evaluation results were as shown in Table 1 below.

  In addition, in order to indirectly check whether the adhesion of the laminate of Example 1 is due to a covalent bond, the obtained laminate was stored in water, and then the adhesion strength of the laminate was measured in the same manner as described above. did. The evaluation results were as shown in Table 1 below.

  As is clear from the evaluation results in Table 1, the laminate of Example 1 has the same adhesive strength as that measured in air even after storage in water. From this result, it can be seen that in the laminate of Example 1, the polyolefin nonwoven fabric and the polyethersulfone resin porous membrane are not bonded only by hydrogen bonds or intermolecular forces. Therefore, although it was indirectly, it was inferred that a covalent bond was formed between the atoms of the polyolefin nonwoven fabric and the atoms in the porous polyethersulfone resin film.

DESCRIPTION OF SYMBOLS 1 Polyolefin nonwoven fabric 2 Polyether sulfone resin porous membrane 3, 3 'Electron beam irradiation apparatus 4, 4' Electron beam 5 Nonwoven fabric base material contact interface 6 Heat roller 7 Support roller

Claims (3)

A method for producing a laminate in which a polyolefin nonwoven fabric and a polyethersulfone resin porous membrane are laminated,
Irradiating at least one surface of the polyolefin nonwoven fabric and / or the polyethersulfone resin porous membrane with an electron beam,
The polyolefin nonwoven fabric surface irradiated with the electron beam and / or the polyethersulfone resin porous membrane surface are superimposed,
The polyolefin non-woven fabric and the polyether sulfone resin porous membrane are pressed at a temperature of 80 to 180 ° C., and at least part of the polyolefin non-woven fabric and the polyether sulfone resin porous membrane A covalent bond is formed between a carbon atom and an atom in the polyethersulfone resin porous membrane,
A method comprising adhering a polyolefin nonwoven fabric and a polyethersulfone resin porous membrane without using an adhesive.   The method according to claim 1, wherein electron beam irradiation is performed before and / or after superposing the polyolefin nonwoven fabric and the polyethersulfone resin porous membrane.   The method according to claim 1 or 2, wherein the electron beam irradiation is performed in an atmosphere having an oxygen concentration of 100 ppm or less.

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