JP5648914B2 - 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 polyamide nonwoven fabric 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 original 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 laminated body that has been conventionally bonded to each other by an adhesive or heat seal processing, such as a laminated body of polyolefin nonwoven fabric and polyamide nonwoven fabric, according to electron beam irradiation, no adhesive is used. However, it has been found that a covalent bond or a hydrogen bond is formed between an atom on the polyolefin nonwoven fabric side and an atom on the polyamide nonwoven fabric side, so that they can be firmly bonded to each other. 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 polyamide nonwoven fabric are bonded without using an adhesive, and foreign matter and residual solvent do not bleed out, and the original performance of the nonwoven fabric is reduced. It is providing the laminated body to which the nonwoven fabric of each other adhered firmly without making it.

The laminate according to the present invention is a laminate in which a polyolefin nonwoven fabric and a polyamide nonwoven fabric are laminated,
In at least a part of the polyolefin nonwoven fabric and the polyamide nonwoven fabric, a bond is formed between an atom in the polyolefin nonwoven fabric and an atom in the polyamide nonwoven fabric, and the polyolefin nonwoven fabric and the polyamide nonwoven fabric have an adhesive. It is characterized by being bonded without intervening.

  Further, as an aspect of the present invention, oxygen atoms or hydroxyl groups are bonded to atoms in the polyolefin nonwoven fabric and polyamide nonwoven fabric, and oxygen atoms and / or hydroxyl groups in the polyolefin nonwoven fabric and oxygen atoms or hydroxyl groups in the polyamide nonwoven fabric. It is preferable that a bond is formed between

  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.

  Further, as an aspect of the present invention, the polyamide nonwoven fabric is made of nylon 6, nylon 12, nylon 66, nylon 612, nylon 6/66 copolymer, nylon 6/12 copolymer fiber, or these resins as sheaths. It is preferable to consist of a composite fiber.

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 polyamide nonwoven fabric are laminated,
Irradiating at least one surface of the polyolefin nonwoven fabric and / or the polyamide nonwoven fabric with an electron beam,
The polyolefin non-woven fabric surface and / or the polyamide non-woven fabric 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 polyamide nonwoven fabric.

  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 polyamide nonwoven fabric are laminated, since the atoms in the polyolefin nonwoven fabric and the atoms in the polyamide nonwoven fabric are bonded directly or through oxygen atoms, Even if it is not bonded via an adhesive, a laminate in which the polyolefin nonwoven fabric and the polyamide nonwoven fabric are firmly bonded can be obtained. As a result, it is possible to realize a laminated body in which the non-woven fabrics are firmly bonded to each other without exuding foreign matters, residual solvents, and the like and without deteriorating the original performance of the non-woven fabric.

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 polyamide nonwoven fabric 2 without using an adhesive.

  The laminate according to the present invention has a polyolefin non-woven fabric by forming a bond between carbon atoms in the polyolefin non-woven fabric and atoms in the polyamide non-woven fabric on at least a part of the bonding surfaces of the polyolefin non-woven fabric 1 and the polyamide non-woven fabric 2. 1 and the polyamide nonwoven fabric 2 are firmly bonded. Usually, even if a polyamide nonwoven fabric is laminated on the surface of a polyolefin nonwoven fabric, hydrogen bonds and covalent bonds are not formed between the two, so that the two cannot be bonded unless an adhesive is used or heat sealed. In the present invention, as will be described later, the surface of the polyolefin nonwoven fabric 1 and / or the polyamide nonwoven fabric 2 is irradiated with an electron beam to generate radicals. As shown in FIG. A bond is formed between the two atoms on the surface, or a bond is formed between the carbon atom on the surface of the polyolefin nonwoven fabric 1 and the atom on the surface of the polyamide nonwoven fabric 2 via an oxygen atom. The polyolefin nonwoven fabric 1 and the polyamide nonwoven fabric 2 are firmly bonded to each other. In addition, radicals generated by electron beam irradiation and oxygen in the air are bonded to each other, and OH groups may be present on the surface of the polyolefin nonwoven fabric 1 and / or the polyamide nonwoven fabric 2. The OH group and the OH group on the polyamide nonwoven fabric 2 side or the oxygen atom or NH group of the amide group may form a bond. In addition, generation of radicals by electron beam irradiation is generated by identifying free radical species existing in fibers in the nonwoven fabric after electron beam irradiation using an electron spin resonance apparatus (hereinafter also referred to as ESR). Can be confirmed.

  A bond formed between atoms between the polyolefin nonwoven fabric and the polyamide nonwoven fabric is an X-ray photoelectron analyzer (hereinafter also referred to as XPS) or a Fourier transform infrared spectrometer (hereinafter also referred to as FTIR). Can be confirmed. For example, before bonding a polyolefin non-woven fabric and a polyamide non-woven fabric, the surface state of each non-woven fabric (fiber) is measured by XPS to confirm what atoms are present on the surface of each fiber before bonding. Then, after bonding the two together by electron beam irradiation to form a laminate, the laminate is forcibly separated to separate it into a polyolefin nonwoven fabric and a polyamide nonwoven fabric, and again how the surface state of both is measured by XPS. To see if there are any atoms. As a result, it can be confirmed whether or not a bond is formed between the two nonwoven fabrics by confirming that an atom derived from the other nonwoven fabric exists on the one nonwoven fabric side. Moreover, you may confirm whether the coupling | bonding derived from another nonwoven fabric exists in the fiber surface of the nonwoven fabric after peeling using FTIR.

  In addition, the laminate in which the polyolefin nonwoven fabric 1 and the polyamide nonwoven fabric 2 are bonded to each other by electron beam irradiation is formed with bonds such as the above-described covalent bonds and hydrogen bonds as shown in FIG. Even if it does not do, it can be set as the laminated body which does not produce peeling. 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 polyamide nonwoven fabric 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 or alcohol hydrogen atoms are destroyed. Or since an oxygen atom and a hydrogen bond are re-formed, both non-woven fabrics peel off because the adhesive force is lost. 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 polyamide nonwoven fabric constituting the laminate according to the present invention will be described.

<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.

  Further, 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 polyamide 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.

<Polyamide non-woven fabric>
The polyamide non-woven fabric constituting the laminate of the present invention is made of non-woven fabric made of a resin such as nylon 6, nylon 12, nylon 66, nylon 612, nylon 6/66 copolymer, nylon 6/12 copolymer. Is obtained.

  In addition, the polyamide 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 polyolefin resin or a polyester resin, and a sheath made of the above-described polyamide resin. A fiber etc. can also be used conveniently.

  Various conventionally known additives such as a light stabilizer, an ultraviolet absorber, an antioxidant, a filler, a lubricant and the like can be appropriately added to the polyamide nonwoven fabric 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, the short fiber or the long fiber made of the above-mentioned polyamide resin can be made into a non-woven fabric according to the above-described conventional method. As the polyamide nonwoven fabric, commercially available ones may be used. For example, Eltus series (Asahi Kasei Fibers Co., Ltd.), Niace series (Unitika Co., Ltd.) and the like can be suitably used.

  In the present invention, the laminated polyolefin nonwoven fabric and polyamide nonwoven fabric have a thickness of about 20 to 800 μm.

  A laminate in which a polyolefin nonwoven fabric and a polyamide nonwoven fabric as described above are laminated and bonded together does not exude foreign matter, residual solvent, etc. even when the laminate is used. Therefore, it can be suitably used for a package used in the medical field, for example, a syringe package bag or a package for filling and packaging a powder or granular pharmaceutical product, not to mention the food field. In addition, since the laminate resin processing and heat seal processing are not performed, the opening of the nonwoven fabric is not blocked by adhesion, and the original performance of the nonwoven fabric 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-mentioned polyolefin nonwoven fabric 1 and polyamide nonwoven fabric 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 polyamide nonwoven fabric 2 are bonded only to the portion irradiated with the electron beam.

  In the present invention, it is preferable to press the laminated nonwoven fabrics 1 and 2 using a roller 6 or the like as shown in FIG. 4 immediately after irradiating the nonwoven fabric with an electron beam. Since the surface of the nonwoven fabrics 1 and 2 (that is, the surface of the fibers) is uneven at the micro level as shown in FIG. 4, even if the nonwoven fabrics are overlapped with each other, the fibers are not in close contact with each other, The contact area at the contact interface between both nonwoven fabrics is small. In this invention, since the contact area in the adhesive surface of both nonwoven fabrics increases by pressing the nonwoven fabrics 1 and 2 with the roller 6 etc. immediately after irradiating an electron beam, adhesiveness improves.

  After the polyolefin nonwoven fabric 1 and the polyamide nonwoven fabric 2 are overlapped, when the both nonwoven fabrics 1 and 2 are pressed, it is preferable to press both nonwoven fabrics 1 and 2 while heating. By pressing while heating, the flexibility of the polyolefin nonwoven fabric 1 and the polyamide nonwoven fabric 2 is improved, and the contact area at the interface (adhesive surface) between the polyolefin nonwoven fabric 1 and the polyamide nonwoven fabric 2 can be further increased. More improved. The heating temperature may be any temperature at which the nonwoven fabric can be thermally deformed, although it depends on the type of nonwoven fabric used. For example, the heating temperature can be higher than the glass transition temperature of the resin constituting the nonwoven fabric. For example, when using the nonwoven fabric which consists of nylon 6 as a polyamide nonwoven fabric, heating temperature is 80-180 degreeC, Preferably it is 100-160 degreeC. 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 polyamide nonwoven fabric 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 may be placed at a position facing the heat roller 6 so that the overlapped nonwoven fabric can be pressed between the heat roller 6 and the support roller 7. . Thus, 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 nonwoven fabric 2) and the heat roller 6 is brought close to line contact, and the heat roller 6. It is possible to minimize the deformation that occurs in the laminated body due to the heat from the.

  FIG. 5 is a schematic view showing another embodiment of the manufacturing method according to the present invention. In the process of laminating and adhering the polyolefin nonwoven fabric 1 and the polyamide nonwoven fabric 2, both nonwoven fabrics 1 and 2 are each guided to an electron beam irradiation position 3 by a guide roller, and both nonwoven fabrics 1 and 2 are irradiated with a heat roller. 6, the process of pressing both nonwoven fabrics 1 and 2 is performed continuously. Each nonwoven fabric 1, 2 may be supplied in a roll form.

  When irradiating each non-woven fabric 1 and 2 with the electron beam 4 from the electron beam irradiation apparatus 3, it is preferable to irradiate the electron beam 4 from the non-woven fabric side having a smaller thickness. Since the electron beam has the property of increasing its transmission power as the acceleration voltage increases, depending on the thickness of the nonwoven fabric, the electron beam may reach the other nonwoven fabric when irradiated with an electron beam from either nonwoven fabric side. May not arrive. In that case, by increasing the acceleration voltage of the electron beam, the electron beam can reach the deep part of the other nonwoven fabric. However, as the electron beam energy increases, unnecessary irradiation is performed on the nonwoven fabric itself. It will deteriorate. Therefore, when a thick nonwoven fabric and a thin nonwoven fabric are laminated and bonded, it is preferable to irradiate an electron beam from the thin nonwoven fabric side without increasing the electron beam energy so much. For example, when the thickness of the polyolefin nonwoven fabric is 25 μm or less and the thickness of the polyamide nonwoven fabric is 50 μm or more, the electron beam is irradiated from the polyolefin nonwoven fabric side. By adopting such an electron beam irradiation method, deterioration of the nonwoven fabric can be minimized.

  When both the nonwoven fabrics 1 and 2 to be overlapped 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 nonwoven fabric sides as shown in FIG. A line irradiation device 3 ′ may be provided. According to this aspect, since the irradiation energy of an electron beam can be adjusted according to the thickness of a nonwoven fabric, both nonwoven fabrics can be adhere | attached, without degrading a nonwoven fabric.

  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 polyamide nonwoven fabric 2 are overlapped. First, a pair of supplied nonwoven fabrics (polyolefin nonwoven fabric 1 and polyamide nonwoven fabric 2) are transferred to nonwoven fabric 1 (2) by electron beam irradiation device 3 (3 ′) before both nonwoven fabrics 1 and 2 are overlapped. Line 4 (4 ') is irradiated. In the embodiment shown in FIG. 5, both the nonwoven fabrics 1 and 2 are overlapped so that the surfaces opposite to the electron beam irradiation side of the nonwoven fabrics 1 and 2 face each other, whereas in the embodiment shown in FIG. The difference is that the nonwoven fabrics 1 and 2 are overlapped so that the surfaces of the nonwoven fabrics 1 and 2 on the electron beam irradiation side face each other. Thus, by superimposing the other non-woven fabric 2 on the surface of the non-woven fabric 1 irradiated with the electron beam, the irradiation energy of the electron beam can be further reduced regardless of the thickness of the non-woven fabric. Degradation 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 electron beam 4 is fed to each of the polyolefin nonwoven fabric 1 and the polyamide nonwoven fabric 2 as in the embodiment shown in FIG. 5. , 4 ′ may be irradiated. By these combinations, the deterioration of the nonwoven fabric 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 non-woven fabric 1 and the polyamide non-woven fabric 2 are overlapped and pressed by the heat roller 6 and then irradiated with an electron beam. First, the pair of supplied materials 1 and 2 are led to a guide roller and overlapped. Subsequently, both the nonwoven fabrics 1 and 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 irradiating device 3 irradiates the surface of the polyolefin nonwoven fabric 1 and the polyamide nonwoven fabric 2 with the electron beam 4, and the bonding of both 1 and 2 is continuously performed. Also in the embodiment shown in FIG. 7, a pair of electron beam irradiation devices 3 and 3 ′ are provided, and the electron beams 4 and 4 are respectively applied to both materials 1 and 2 in the same manner as the embodiment shown in FIGS. 4 'may be irradiated. By these combinations, the deterioration of the nonwoven fabric can be further reduced and the adhesive strength can be improved.

  The irradiation energy of the electron beam needs to be appropriately adjusted according to the thickness of the nonwoven fabric 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 setting the irradiation energy to be low in this way, not only the deterioration of the nonwoven fabric can be suppressed, but also the radical generation on the surface of the nonwoven fabric can be performed more efficiently, so that a stronger bond can be realized. 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 polyamide nonwoven fabric 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 polyamide nonwoven fabric>
The following two types of nonwoven fabrics were prepared as polyolefin nonwoven fabrics.
A: Polyolefin nonwoven fabric with a thickness of 160 μm (Elves T0303WDO, manufactured by Unitika Ltd.)
B: Polyolefin non-woven fabric having a thickness of 250 μm (ELTAS P03030, manufactured by Asahi Kasei Fibers Co., Ltd.)
Moreover, the following two types of nonwoven fabrics were prepared as polyamide nonwoven fabrics.
C: Niace N0303WTO (manufactured by Unitika Ltd.) as a polyamide nonwoven fabric with a thickness of 160 μm
D: As a polyamide nonwoven fabric having a thickness of 140 μm, Niace N0203WTO (manufactured by Unitika Ltd.)

Example 1
<Production of laminate>
Samples prepared by cutting the polyolefin nonwoven fabric of A and the polyamide nonwoven fabric of C 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 Photonics) was prepared. Placed on a sample stand. 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 and immediately laminated so that the electron beam irradiation surface sides of both nonwoven fabrics were opposed to each other, and both nonwoven fabrics were bonded by a thermal laminating method to obtain a laminate.

Examples 2-3
A laminate was obtained in the same manner as in Example 1 except that the resin nonwoven fabric used was a combination shown in Table 1 below and the electron beam irradiation conditions shown in Table 1 were used.

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 bonded to the polyolefin nonwoven fabric and the polyamide nonwoven fabric.

Comparative Example 2
A laminate was obtained in the same manner as in Example 2 except that electron irradiation was not performed. However, the obtained laminate was not bonded to the polyolefin nonwoven fabric and the polyamide nonwoven fabric.

<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 Comparative Examples 1 and 2 did not adhere | attach the polyolefin nonwoven fabric and the polyamide nonwoven fabric, 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 laminates of Examples 1 to 3 is due to a covalent bond, the obtained laminate was stored in water, and then the adhesive strength of the laminate in the same manner as described above. Was measured. The evaluation results were as shown in Table 1 below.

  As is clear from the evaluation results in Table 1, the laminates of Examples 1 to 3 have the same adhesive strength as that measured in air even after storage in water. From this result, it can be seen that in the laminates of Examples 1 to 3, the polyolefin nonwoven fabric and the polyamide nonwoven fabric are not bonded only by hydrogen bonds or intermolecular forces. Therefore, although indirectly, it was inferred that a covalent bond was formed between the atoms of the polyolefin nonwoven fabric and the atoms in the polyamide nonwoven fabric.

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

Claims (7)

A laminate in which a polyolefin nonwoven fabric and a polyamide nonwoven fabric are laminated by being pressed at a temperature of 80 to 180 ° C. after being irradiated with an electron beam ,
In at least a part of the polyolefin nonwoven fabric and the polyamide nonwoven fabric, a covalent bond is formed between a carbon atom in the polyolefin nonwoven fabric and an atom in the polyamide nonwoven fabric, and the polyolefin nonwoven fabric and the polyamide nonwoven fabric are bonded. A laminated body, characterized in that it is bonded without interposing an agent.   An oxygen atom or a hydroxyl group is bonded to an atom in the polyolefin nonwoven fabric and the polyamide nonwoven fabric, and a bond is formed between the oxygen atom and / or hydroxyl group in the polyolefin nonwoven fabric and the oxygen atom or hydroxyl group in the polyamide nonwoven fabric. The laminate according to claim 1.   The laminate according to claim 1 or 2, wherein the polyolefin nonwoven fabric is composed of fibers made of polyethylene, polypropylene, or polymethylpentene, or composite fibers having these resins as sheaths.   The polyamide non-woven fabric is made of nylon 6, nylon 12, nylon 66, nylon 612, nylon 6/66 copolymer, nylon 6/12 copolymer fiber, or composite fiber with these resins as sheaths. Item 4. The laminate according to any one of Items 1 to 3. A method for producing a laminate in which a polyolefin nonwoven fabric and a polyamide nonwoven fabric are laminated according to any one of claims 1 to 4,
Irradiating at least one surface of the polyolefin nonwoven fabric and / or the polyamide nonwoven fabric with an electron beam,
The polyolefin nonwoven fabric surface and / or the polyamide nonwoven fabric surface irradiated with the electron beam is superimposed ,
A method comprising: adhering both nonwoven fabrics while pressing them at a temperature of 80 to 180 ° C.   The method of Claim 5 which performs electron beam irradiation before superimposing the said polyolefin nonwoven fabric and a polyamide nonwoven fabric, and / or after superimposing. The method according to claim 5 or 6, wherein the electron beam irradiation is performed in an atmosphere having an oxygen concentration of 100 ppm or less.

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