JP2015189224A - Laminated sheet and method of producing laminated sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated sheet which has soft texture and smooth touch and is durable, with detachment between layers suppressed, and excellent in handleability and a method of producing a laminated sheet which connects individual layers strongly together.SOLUTION: A laminated sheet includes a contact layer composed of a nanofiber nonwoven fabric, a support layer composed of a fibrous porous material and a connection layer which connects both layers together and is composed of a nanofiber nonwoven fabric. The connection layer is formed with a thermoplastic resin, and the contact layer and the support layer are formed with a heat-infusible material or a thermoplastic resin having a melting point higher than that of the thermoplastic resin forming the connection layer as the main material. The laminated sheet is produced by laminating the connection layer and the contact layer, in order, on the support layer and heating the resultant body at such a temperature as to melt the thermoplastic resin forming the connecting layer but not to melt the main material of the support layer and the contact layer so as to connect the layers together.

Description

  The present invention relates to a laminated sheet having a soft texture of a nanofiber nonwoven fabric, strong and excellent in handleability during use, and a method for producing the laminated sheet.

  Conventionally, for example, a cosmetic sheet called a face mask sheet or an eye sheet for caring for skin such as the face has been used. Since such a cosmetic sheet is in direct contact with the skin and may be used by being affixed to the skin for a long time, the surface of the cosmetic sheet has a touch when applied to the skin. For example, a non-woven fabric having a high water retention capacity such as a lotion is used.

  In recent years, a technique for forming a nonwoven fabric using ultrafine fibers having a fiber diameter smaller than that of a general nonwoven fabric, called a “nanofiber”, having a nanometer diameter, into a sheet shape has been developed. A nanofiber nonwoven fabric formed into a sheet (hereinafter also simply referred to as a “nanofiber sheet”) is formed of fibers having a general thickness because the fibers constituting the sheet are formed of nanofibers. The surface becomes smoother and softer than non-woven fabrics. In addition, since a large number of nano-level voids are formed inside the nanofiber sheet, strong capillary force is generated and moisture can be retained for a long time.

  Therefore, when the nanofiber sheet is used as a cosmetic sheet, a soft texture is obtained, and the touch becomes smoother than a general nonwoven fabric. In addition, when impregnated with lotion or the like, there is an advantage that the lotion or the like can be held for a long time. Furthermore, since the fiber diameter is very small, it can be applied so that it adheres along the unevenness of the skin at the application site, and it is possible to spread active ingredients such as lotion evenly over the skin surface. .

  In recent years, various cosmetic sheets using nanofiber sheets having the functions as described above have been proposed (for example, Patent Document 1 and Patent Document 2).

JP 2010-168722 A JP 2007-70347 A JP 2011-89226 A

Patent Document 1 discloses a cosmetic sheet having a laminated structure of a base material layer and a nanofiber sheet layer. In this cosmetic sheet, a release surface is formed between the base material layer and the nanofiber sheet layer by a release member such as silicone. For this reason, at the time of use, after sticking the nanofiber sheet layer side of the cosmetic sheet to the skin, the base material layer can be peeled off to leave only the nanofiber sheet layer on the skin surface.
However, this nanofiber sheet layer is very thin and easy to tear, so when removing the nanofiber sheet layer affixed to the skin from the skin, it will break and become tattered, so it is not easy to handle after use. It was.

Further, Patent Document 2 discloses a cosmetic sheet having a laminated structure of a base material layer and a nanofiber sheet layer constituted by thick and strong fibers. An intertwined decorative sheet is disclosed. In such a cosmetic sheet, since the base material layer and the nanofiber sheet layer are difficult to peel off, only the nanofiber layer does not remain on the skin surface after use.
However, in the cosmetic sheet of Patent Document 2, since the base material layer and the nanofiber sheet layer are integrated by interlacing the fibers constituting these both layers, the thick fibers constituting the base material layer are In some cases, the surface of the nanofiber layer may protrude. For this reason, there exists a problem that the soft texture peculiar to a nanofiber sheet layer and smooth touch will be impaired.

Patent Document 3 discloses a filter having a multilayer structure in which two layers (an intermediate layer and an upper layer) of nanofiber nonwoven fabric layers are formed on a nonwoven fabric layer (lower layer) composed of strong fibers having a large fiber diameter. A fiber sheet suitable for the separator is disclosed.
However, the multilayer structure of Patent Document 3 is configured to protect an intermediate layer made of a nanofiber nonwoven fabric having an extremely small fiber diameter and easily damaged by an upper layer made of a relatively strong nanofiber nonwoven fabric having a slightly larger fiber diameter. ing. Therefore, the nanofiber nonwoven fabric of the upper layer is insufficient in soft texture and smoothness of the touch, and is unsuitable for uses such as a cosmetic sheet used by being attached to the skin.

  In view of the above circumstances, an object of the present invention is to provide a laminated sheet that has a soft texture and a smooth feel, is strong, is difficult to peel off between layers, and is easy to handle, and a method for producing such a laminated sheet.

  The laminated sheet of the first invention comprises a contact layer made of a nanofiber nonwoven fabric and brought into contact with an object, a support layer made of a fibrous porous material, and a nano-layer provided between the support layer and the contact layer and connected to both layers. A connecting layer made of a fiber nonwoven fabric, wherein the connecting layer is made of a thermoplastic resin, and the contact layer and the support layer are made of a thermally infusible material or the thermoplastic resin forming the connecting layer. A thermoplastic resin having a melting point higher than the melting point is formed as a main material.

  In the present invention, the “main material” is a material occupying about 90% by mass or more of the material forming the contact layer and a material occupying about 90% by mass or more of the material forming the support layer. .

  In the laminated sheet of the second invention, in the first invention, the contact layer is formed of a thermoplastic resin, and the thermoplastic resin is softened higher than a melting point of the thermoplastic resin forming the connection layer. It is characterized by having a point.

Furthermore, the laminated sheet of the third invention is characterized in that, in the first or second invention, the nanofiber nonwoven fabric constituting the coupling layer has a basis weight of 0.1 to 1 g / m ² .

  Moreover, the laminated sheet of 4th invention is the target object which this nanofiber nonwoven fabric which comprises the said contact layer in the said 1st, 2nd or 3rd invention is 50-280 nm, and makes this contact layer contact Is characterized by being skin.

  Next, the manufacturing method of the laminated sheet of the fifth invention is a method of manufacturing the laminated sheet of the first invention, wherein the connecting layer and the contact layer are sequentially laminated on at least one surface of the support layer. The thermoplastic resin forming the connection layer is melted, but the main materials forming the support layer and the contact layer are heated at a temperature that does not melt, thereby connecting the layers.

Here, “heating at a temperature that melts the thermoplastic resin forming the coupling layer but does not melt the main material forming the support layer and the contact layer” is more specifically described in (1) below. It is as illustrated in (3).
(1) When both the contact layer and the support layer are formed using a heat-insoluble material as a main material, the contact layer and the support layer are heated at a temperature equal to or higher than the melting point of the thermoplastic resin forming the connection layer.
(2) Either the contact layer or the support layer is formed mainly of a thermoplastic resin having a melting point higher than the melting point of the thermoplastic resin forming the coupling layer, and the other is a heat infusible material. When the material is formed as a main material, the temperature is equal to or higher than the melting point of the thermoplastic resin forming the connection layer, and the main material forming either the contact layer or the support layer is used. Heat at a temperature lower than the melting point of the thermoplastic resin.
(3) When both the contact layer and the support layer are formed using a thermoplastic resin having a melting point higher than the melting point of the thermoplastic resin forming the coupling layer as a main material, the coupling layer is The melting point of the thermoplastic resin as the main material for forming the contact layer and the thermoplastic resin as the main material for forming the support layer, which has a lower melting point than the melting point of the thermoplastic resin to be formed. Heat at a lower temperature.

  Moreover, the manufacturing method of the laminated sheet of the sixth invention is a method of manufacturing the laminated sheet of the second invention, wherein the connection layer and the contact layer are sequentially laminated on at least one side of the support layer, The thermoplastic resin forming the coupling layer is melted but the main material forming the support layer is not melted, and is heated at a temperature lower than the softening point of the thermoplastic resin forming the contact layer. The layers are connected to each other.

Here, “the temperature at which the thermoplastic resin forming the connecting layer is melted but the main material forming the support layer is not melted, and is lower than the softening point of the thermoplastic resin forming the contact layer” More specifically, “heating at temperature” is as exemplified in the following (1) and (2).
(1) The contact layer is formed of a thermoplastic resin having a softening point higher than the melting point of the thermoplastic resin forming the coupling layer as a main material, and the support layer is formed of a heat infusible material as a main material. Is formed at a temperature equal to or higher than the melting point of the thermoplastic resin forming the coupling layer and lower than the softening point of the thermoplastic resin as the main material forming the contact layer. .
(2) The contact layer is formed of a thermoplastic resin having a softening point higher than the melting point of the thermoplastic resin forming the connection layer, and the support layer is higher than the melting point of the thermoplastic resin forming the connection layer. If the thermoplastic resin having a higher melting point is formed as a main material, the temperature is equal to or higher than the melting point of the thermoplastic resin forming the coupling layer, and the thermoplastic resin forming the contact layer is softened. Heating is performed at a temperature lower than the point and lower than the melting point of the thermoplastic resin as the main material forming the support layer.

  According to the laminated sheet of the first invention, the contact layer made of a nanofiber nonwoven fabric having a soft texture but low tensile strength, and the support layer made of a fibrous porous material having a little hardness but high tensile strength. Since the layers are connected via the connecting layer, the entire laminated sheet is highly flexible and strong, and the surface of the contact layer can be a laminated sheet having a soft texture and a smooth touch. Therefore, for example, when used as a cosmetic sheet or a wound covering sheet, the touch can be felt smoothly and the adhesiveness is high, and it is difficult to break and the handleability is excellent.

  Further, according to the laminated sheet of the first invention, since the connecting layer is formed of a nanofiber nonwoven fabric having a very small fiber diameter and a soft texture, the contact layer is also formed of the nanofiber nonwoven fabric. Does not spoil the soft texture. Further, since the nanofiber nonwoven fabric forming the connecting layer has a narrow fiber gap, it covers and hides the irregularities on the surface of the fibrous porous layer forming the support layer, and the fibers constituting the fibrous porous layer are on the surface of the contact layer. Can be prevented from protruding. Therefore, the surface of the contact layer can be made soft and smooth.

  Furthermore, according to the laminated sheet of the first invention, since the connecting layer is formed of a nanofiber nonwoven fabric, for example, it is impregnated with skin lotion or disinfecting liquid as a cosmetic sheet or a wound covering sheet and applied to the skin. When used, a strong capillary force is generated not only in the contact layer but also in the connecting layer, so that a lotion, a disinfectant, and the like can be held for a long time. Therefore, active ingredients such as skin lotion and disinfectant can be sufficiently distributed to the necessary portions of the skin surface.

  Moreover, since the nanofiber nonwoven fabric of the said connection layer has the very small fiber diameter of the nanofiber which comprises it, a surface area is large, and when it laminates | stacks, a contact area with the nonwoven fabric of another layer can be enlarged. Therefore, the connection layer is very strongly connected to the support layer and the contact layer. Therefore, even when the contact layer and the support layer are formed of a heat infusible material or the like, which is generally considered to be hard and difficult to thermally weld, the connection layer formed of a thermoplastic resin is melted. Each layer can be strongly connected by heating at a temperature.

  Next, in the laminated sheet of the second invention, the contact layer is formed of a thermoplastic resin having a softening point higher than the melting point of the thermoplastic resin forming the connection layer. Therefore, at the time of manufacturing such a laminated sheet, after each layer is laminated, the temperature is equal to or higher than the melting point of the thermoplastic resin forming the connection layer, and is lower than the softening point of the thermoplastic resin forming the contact layer. By heating at a temperature, the nanofiber nonwoven fabric of the connection layer can be melted and the layers can be heat-welded without softening the nanofiber nonwoven fabric of the contact layer. Therefore, according to the laminated sheet of the second invention, the nanofiber nonwoven fabric of the contact layer that is easily thermally deformed because the fiber diameter is extremely small, without causing thermal deformation, without damaging the soft texture or smooth touch of the surface. Each layer can be strongly connected.

Next, according to the laminated sheet of the third invention, the support layer and the contact layer can be strongly connected by setting the basis weight of the nanofiber nonwoven fabric constituting the connection layer to 0.1 to 1 g / m ^2. At the same time, the flexibility of the entire laminated sheet can be increased.

  Next, according to the laminated sheet of the fourth invention, the surface of the contact layer has a particularly soft texture and a smooth touch by setting the average fiber diameter of the nanofiber nonwoven fabric constituting the contact layer to 50 to 280 nm. . Therefore, for example, when used as a face mask sheet or eye sheet by impregnating lotion or the like and affixing to the skin, the adhesion to the skin is good, and the inconvenience of dropping off from the skin during use is unlikely to occur. Furthermore, it is possible to obtain a laminated sheet that is less irritating to the skin and hardly causes rough skin. Therefore, such a laminated sheet can be suitably used as a cosmetic sheet or a wound-covering sheet that is used in contact with the skin.

Next, according to the method for producing a laminated sheet of the fifth invention, when producing the laminated sheet of the first invention, the thermoplastic resin forming the connecting layer is melted, but the support layer and the contact layer are melted. Since the main material forming the layer is heated at a temperature that does not melt, only the connecting layer can be melted to function as an adhesive, and the layers can be connected.
Here, since the said connection layer is formed with the nanofiber nonwoven fabric with a very small fiber diameter, a surface area is large, and when it laminates | stacks, it can enlarge a contact area with the nonwoven fabric of another layer. Therefore, the connection layer can be very strongly connected to the support layer and the contact layer.

  Next, according to the manufacturing method of the laminated sheet of the sixth invention, when the laminated sheet of the second invention is manufactured, the thermoplastic resin that forms the connection layer is melted, but the main layer that forms the support layer is formed. Since it is heated at a temperature that does not melt the material and is lower than the softening point of the thermoplastic resin that forms the contact layer, only the connecting layer is melted to function as an adhesive, and the layers are connected. Can be made.

  Further, the nanofiber nonwoven fabric of the contact layer is easily deformed by heat because the diameter of the nanofibers constituting the contact layer is extremely small, and if it is thermally deformed, the soft texture and smooth touch may be impaired. There is. However, according to the sixth aspect of the invention, since the connection between the layers is performed at a temperature lower than the softening point of the thermoplastic resin forming the nanofiber nonwoven fabric of the contact layer, thermal deformation of the nanofiber nonwoven fabric of the contact layer is performed. Can be reliably prevented, and the soft texture and smooth touch of the surface can be maintained in a good state.

The laminated sheet of the present invention is a laminated sheet used in contact with an object such as skin, such as a cosmetic sheet such as a face mask sheet or eye sheet, a wound covering sheet used to cover a wound, It has a soft texture and a smooth feel derived from the nanofiber nonwoven fabric of the contact layer disposed on the surface, is strong, is difficult to peel off between layers, and has excellent handleability.
In addition, as an object to be contacted when using the laminated sheet of the present invention, human or animal skin is suitable, but is not limited thereto, and in the case of skin, the site is not limited, It can be used for various parts such as the face and limbs.

  The nanofiber nonwoven fabric used for the contact layer and the connection layer of the laminated sheet of the present invention is a nanofiber entangled or mutually bonded. The nanofiber is, for example, a very thin fiber having a fiber diameter of about 1 to 500 nm. The nanofiber nonwoven fabric formed by such nanofibers has a unique texture such that the surface has a soft texture and has a number of nano-level microscopic voids, so that strong capillary force is generated and liquid such as water can be retained for a long time. Have properties. In addition, since the nanofiber nonwoven fabric has a very large surface area, when it is laminated, the contact area with the nonwoven fabric of the other layer can be increased, so that it is generally possible to strongly weld even resins that are not compatible with heat welding. It has the property.

  Next, the support layer, the coupling layer, and the contact layer constituting the laminated sheet of the present invention will be described in order.

(A) Support layer The support layer of the laminated sheet of the present invention is made of a fibrous porous material, and has a melting point higher than the melting point of the "thermoinsoluble material" or the thermoplastic resin forming the nanofiber nonwoven fabric of the linking layer. One of the “thermoplastic resin having” or a combination of both is formed as a main material. The main material is a material that occupies about 90% by mass or more of the entire material.

  Such a support layer is a combination of one or both of “a heat infusible material” and “a thermoplastic resin having a melting point higher than that of the thermoplastic resin forming the nanofiber nonwoven fabric of the coupling layer”. Although it is most preferable that the material is formed only from a material, even if a material that does not satisfy such a requirement is included, if the proportion is less than about 10% by mass, that is, the proportion of the material that satisfies the requirement is If it is about 90% by mass or more, it sufficiently functions as a support layer, and the effects unique to the present invention are not impaired.

  Here, as the fibrous porous material, needle punched nonwoven fabric or spunlace nonwoven fabric formed by entanglement of pre-spun long fibers or short fibers, spunbond nonwoven fabric or melt blown nonwoven fabric formed by long-fiber spun together. Nonwoven fabrics produced by any method such as wet nonwoven fabrics formed by rolling short fibers, woven fabrics such as woven fabrics and gauze, and paper can be used, but the laminated sheet of the present invention has moderate flexibility. In order to give, it is preferable to use a needle punch nonwoven fabric or a spunlace nonwoven fabric.

In the present invention, the support layer is provided mainly for the purpose of imparting strength to the laminated sheet of the present invention and making it difficult to break. For that purpose, the average fiber diameter of the fibrous porous material of the support layer is determined by the connection layer. Or larger than the average fiber diameter of the nanofiber nonwoven fabric of the contact layer, preferably 1 to 50 μm, more preferably 10 to 30 μm.
Here, in the present invention, the average fiber diameter is an average value of the diameter when the cross-sectional shape of the fiber is circular, and when the cross-sectional shape of the fiber is other than the circular shape, the cross-sectional shape is virtually circular with the same area. It is the average value of the diameters obtained when converted to.

Further, fibrous porous support layer preferably has a basis weight is 10 to 100 g / ^{m 2,} more preferably 40 and 80 g / ^{m 2.} When the basis weight is less than 10 g / m ² , the breaking strength of the laminated sheet of the present invention tends to decrease, and when it exceeds 100 g / m ² , the flexibility of the entire laminated sheet tends to decrease.

In the present invention, the fibrous porous material of the support layer can be formed using a heat infusible material as a main material. Here, the heat infusible material does not melt even when heated, and is excessive. When heated at a high temperature, it is a material that undergoes carbonization.
Examples of such heat infusible materials include rayon, cotton, hemp, aromatic polyamide resin (aramid resin), phenol resin, chitin, chitosan, collagen, gelatin, silk and the like. Or can be used in combination.

Further, the fibrous porous material of the support layer can be formed using a thermoplastic resin as a main material. For example, polyolefin resins such as polypropylene (PP) and polyethylene (PE), polyethylene terephthalate (PET), and polybutylene terephthalate. Polyester resins such as (PBT), polycarbonate resins such as polycarbonate (PC), polystyrene resins such as polystyrene (PS), vinyl chloride resins such as polyvinyl chloride (PVC), polyamide resins such as nylon 6 and nylon, Polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyethersulfone (PES), and the like can be used, and these can be used alone or in combination.
When the main material of the support layer is formed of a thermoplastic resin, it is necessary to select a thermoplastic resin having a melting point higher than the melting point of the thermoplastic resin forming the coupling layer.

(B) Connection layer The connection layer of the laminated sheet of the present invention is made of a nanofiber nonwoven fabric and is formed of a thermoplastic resin.
Here, as the nanofiber nonwoven fabric, a nanofiber nonwoven fabric produced by electrospinning, a nanofiber nonwoven fabric obtained by dissolving and removing the sea part from a nonwoven fabric composed of polymer alloy fibers having a sea-island structure, and the like are used. However, a nanofiber nonwoven fabric obtained by an electrospinning method is preferable because the coupling layer and the contact layer can be laminated on the same production line, which enables efficient production.

  In the present invention, the nanofiber nonwoven fabric of the linking layer preferably has an average fiber diameter of 50 to 300 nm, more preferably 80 to 200 nm. If the average fiber diameter is less than 50 nm, the fiber diameter is excessively small, and it takes a long time to form a nanofiber nonwoven fabric for the basis weight necessary for the connection layer, and the production efficiency tends to decrease. On the other hand, when the average fiber diameter exceeds 300 nm, the softness of the texture of the nanofiber nonwoven fabric of the contact layer laminated on the surface of the linking layer tends to decrease, and the flexibility of the entire laminated sheet of the present invention Tend to decrease.

Also, nanofiber nonwoven fabric of the tie layer preferably has a basis weight is 0.1 to 1 g / ^{m 2,} more preferably from 0.2 to 0.8 g / ^{m 2.} When the basis weight is less than 0.1 g / m ² , the peel strength between the connecting layer and the support layer tends to be lowered and tends to be peeled off. On the other hand, when the basis weight exceeds 1 g / m ² , the laminated sheet of the present invention. There is a tendency for the overall flexibility to decrease.

  In addition, the nanofiber nonwoven fabric of the connecting layer is made of thermoplastic resin, and the nanofiber nonwoven fabric is heated and melted to function as an adhesive, and the connecting layer and the support layer, and the connecting layer and the contact layer are connected to each other. And the laminated sheet of the present invention is formed.

Examples of the thermoplastic resin that forms such a nanofiber nonwoven fabric of the connecting layer include low melting point nylon, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyethylene oxide (PEO), and the like. These can be used alone or in combination.
In the laminated sheet of the present invention, when the support layer or the contact layer is formed of a thermoplastic resin, the melting point of the thermoplastic resin that forms the support layer or the contact layer is the thermoplastic resin that forms the connection layer. It is necessary to select a thermoplastic resin having a melting point lower than the melting point.

(C) Contact layer The contact layer of the laminated sheet of the present invention is composed of a nanofiber nonwoven fabric, and has a melting point higher than the melting point of the “thermoinsoluble material” or the thermoplastic resin forming the nanofiber nonwoven fabric of the linking layer. Either or both of the thermoplastic resins having a thermoplastic resin are formed as a main material. The main material is a material that occupies about 90% by mass or more of the entire material.

  The contact layer is a combination of one or both of “a heat infusible material” and “a thermoplastic resin having a melting point higher than that of the thermoplastic resin forming the nanofiber nonwoven fabric of the coupling layer”. Although it is most preferable that the material is formed only from a material, even if a material that does not satisfy such a requirement is included, if the proportion is less than about 10% by mass, that is, the proportion of the material that satisfies the requirement is If it is about 90 mass% or more, it will function sufficiently as a contact layer, and the effects unique to the present invention will not be impaired.

  Here, as the nanofiber nonwoven fabric, the sea part is dissolved from the nanofiber nonwoven fabric manufactured by the electrospinning method and the nonwoven fabric composed of polymer alloy fibers having a sea-island structure, as in the nanofiber nonwoven fabric of the connecting layer described above. Nanofiber nonwoven fabric obtained by removing can be used, but if nanofiber nonwoven fabric by electrospinning method, the connection layer and contact layer can be laminated on the same production line, so efficient production is possible It is preferable.

  In the present invention, the nanofiber nonwoven fabric of the contact layer preferably has an average fiber diameter of 50 to 280 nm, more preferably 100 to 200 nm. When the average fiber diameter is less than 50 nm, the fiber diameter is excessively small, and it takes a long time to form a nanofiber nonwoven fabric for the basis weight necessary for the contact layer, and the production efficiency tends to decrease. On the other hand, when the average fiber diameter exceeds 280 nm, the softness of the texture on the surface of the contact layer and the smoothness of the touch tend to decrease.

The nanofiber nonwoven fabric of the contact layer preferably has a basis weight of 0.1 to ² g / m ² , more preferably 0.3 to 1 g / m ² . When the basis weight is less than 0.1 g / m ² , the contact layer becomes thin, and the smoothness of the touch and the adhesion to the skin tend to decrease. On the other hand, when the basis weight exceeds ² g / m ² , the flexibility of the entire laminated sheet of the present invention tends to decrease.

  In the present invention, the nanofiber nonwoven fabric of the contact layer can be formed using a heat infusible material as a main material, such as rayon, aromatic polyamide resin (aramid resin), phenol resin, chitin, chitosan, collagen, gelatin, Silk etc. can be mentioned, These can be used individually or in mixture.

  In addition, the nanofiber nonwoven fabric of the contact layer can be formed using a thermoplastic resin as a main material, for example, a polyolefin resin such as polypropylene (PP) or polyethylene (PE), or a polyester resin such as polyethylene terephthalate (PET). Polycarbonate resins such as polycarbonate (PC), polystyrene resins such as polystyrene (PS), polyvinyl chloride resins such as polyvinyl chloride (PVC), polyamide resins such as nylon 6 and nylon, polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyethersulfone (PES), polyethylene oxide (PEO), and the like can be used, and these can be used alone or in combination.

When the contact layer is formed using a thermoplastic resin as a main material, it is necessary to select a thermoplastic resin having a melting point higher than that of the thermoplastic resin forming the coupling layer. Furthermore, it is preferable to select a thermoplastic resin having a softening point higher than the melting point of the thermoplastic resin forming the coupling layer.
Here, in the present invention, the “softening point” of the thermoplastic resin means a “deflection temperature under load” (JIS K7191 B method), and is a temperature at which the thermoplastic resin begins to soften and deform by heating.

  In the present invention, when the contact layer is formed of a thermoplastic resin having a softening point higher than the melting point of the thermoplastic resin forming the connection layer, the connection layer is formed when the layers of the laminated sheet of the present invention are connected by heat treatment. By heating at a temperature higher than the melting point of the thermoplastic resin to be formed and lower than the softening point of the thermoplastic resin forming the contact layer, the nanofiber nonwoven fabric of the linking layer is melted as an adhesive. While functioning, it is possible to reliably prevent thermal deformation of the nanofiber nonwoven fabric of the contact layer. Therefore, each layer of the laminated sheet can be strongly connected, and the soft texture and smooth feel of the surface of the contact layer can be reliably maintained.

  The laminated sheet of the present invention comprises at least three layers (A) supporting layer, (B) connecting layer, and (C) contact layer, and these layers are connected and integrated by heat welding. It is formed by.

Next, the manufacturing method of the lamination sheet of this invention is demonstrated.
In the laminated sheet of the present invention, the connection layer and the contact layer made of nanofiber nonwoven fabric are sequentially laminated on the surface of the support layer made of fibrous porous material, and then the thermoplastic resin forming the connection layer is melted. And it can manufacture by heating at the temperature which does not melt the main material which forms a contact layer, and connecting each layer.

  Here, the fibrous porous material is composed of a nonwoven fabric, a woven fabric, or paper. When the fibrous porous material is a nonwoven fabric, it is formed by entangled long fibers or short fibers spun in advance by a needle punch method or a spunlace method. It can be produced by a method, a method in which long fibers are spun together by a spunbond method or a melt blow method, and a method in which short fibers are formed by a wet method. In particular, it is preferable to produce the laminated sheet of the present invention by a needle punch method or a spunlace method in order to impart appropriate flexibility.

  Next, a connecting layer and a contact layer made of a nanofiber nonwoven fabric are sequentially laminated on the surface of the fibrous porous material. The nanofiber nonwoven fabric can be formed by an electrospinning method or has a sea-island structure. It can also be formed by forming a nonwoven fabric composed of polymer alloy fibers and then dissolving and removing the sea part. However, the electrospinning method is preferable because the coupling layer and the contact layer can be laminated and formed on the same production line, which contributes to high production efficiency and low cost.

  As an apparatus for forming a nanofiber nonwoven fabric by electrospinning, for example, a device having a mechanism for spinning a nanofiber by discharging a polymer solution from a nozzle to which a high voltage is applied into an ultrafine thread shape, It is known that the polymer solution is attached to the formed rotating electrode and has a mechanism for spinning nanofibers by applying a high voltage to discharge from the protrusions of the rotating electrode into ultrafine threads. Can be used with any type of device. However, an apparatus of a type that uses a rotating electrode is preferable because nanofiber nonwoven fabrics can be produced in large quantities, and thus the production efficiency is high and the cost is reduced.

Therefore, in the following, a method for forming a nanofiber nonwoven fabric by an apparatus of a type using a rotating electrode will be described.
First, a resin or the like that is a raw material for nanofibers is dissolved in a predetermined solvent to prepare a polymer solution, and this polymer solution is placed in a tub having a rotating electrode on which a large number of protrusions are formed. Then, by applying a predetermined high voltage to the rotating electrode, nanofibers are spun and laminated on the surface of the support layer made of a fibrous porous disposed at a predetermined integration distance. At that time, the fiber diameter and basis weight of the obtained nanofibers can be adjusted by appropriately changing conditions such as applied voltage, solution concentration or accumulation distance.

Here, the solvent for dissolving the raw material of the nanofiber may be appropriately selected according to the raw material. For example, when using a low melting point nylon as the raw material of the nanofiber, the acetic acid solution and the formic acid solution are mixed at a predetermined mixing ratio. A polymer solution is prepared by dissolving in a mixed solvent so that the concentration of the low-melting nylon is about 5 to 15% by mass.
And a connection layer which consists of nanofiber nonwoven fabrics of a low melting point nylon with a soft texture can be formed by spinning with an applied voltage of about 60 to 80 kV and an accumulation distance of about 10 to 20 cm.

  Moreover, the contact layer which consists of a nanofiber nonwoven fabric can be formed in the surface of the said connection layer by changing a raw material and a solvent and adjusting spinning conditions suitably using the same apparatus.

Next, a sheet obtained by laminating the support layer, the coupling layer and the contact layer (hereinafter also referred to as “laminated sheet before coupling”) obtained by the above-described method is used with a heating device such as a constant temperature continuous bonding device. Are heated and connected to integrate the layers.
In such heat treatment, it is necessary to “heat at a temperature that melts the thermoplastic resin forming the coupling layer but does not melt the main material forming the support layer and the contact layer”. Specifically, it may be heated as exemplified in the following (1) to (3).
(1) When both the contact layer and the support layer are formed using a heat infusible material as a main material, the contact layer and the support layer may be heated at a temperature equal to or higher than the melting point of the thermoplastic resin forming the coupling layer.
(2) Either the contact layer or the support layer is formed mainly of a thermoplastic resin having a melting point higher than the melting point of the thermoplastic resin forming the coupling layer, and the other is formed of a heat infusible material. When formed as the main material, the temperature is equal to or higher than the melting point of the thermoplastic resin forming the connecting layer, and the melting point of the thermoplastic resin as the main material forming either the contact layer or the support layer. May be heated at a lower temperature.
(3) When both the contact layer and the support layer are formed mainly of a thermoplastic resin having a melting point higher than the melting point of the thermoplastic resin that forms the coupling layer, the thermoplastic that forms the coupling layer Heating at a temperature lower than the melting point of the thermoplastic resin of the main material forming the contact layer and the thermoplastic resin of the main material forming the support layer that has a lower melting point than the melting point of the resin do it.

Further, in such heat treatment, “the temperature at which the thermoplastic resin forming the coupling layer is melted but the main material forming the support layer is not melted, and from the softening point of the thermoplastic resin forming the contact layer” It is preferable to “heat at a low temperature”. Specifically, it may be heated as exemplified in the following (1) and (2).
(1) The contact layer is formed of a thermoplastic resin having a softening point higher than the melting point of the thermoplastic resin forming the coupling layer, and the support layer is formed using a heat infusible material as a main material. May be heated at a temperature equal to or higher than the melting point of the thermoplastic resin forming the connecting layer and lower than the softening point of the thermoplastic resin forming the contact layer.
(2) The contact layer is formed of a thermoplastic resin having a softening point higher than the melting point of the thermoplastic resin forming the connection layer, and the support layer has a melting point higher than the melting point of the thermoplastic resin forming the connection layer. In the case where the thermoplastic resin is formed as a main material, the temperature is equal to or higher than the melting point of the thermoplastic resin forming the connection layer and lower than the softening point of the thermoplastic resin forming the contact layer. In addition, it may be heated at a temperature lower than the melting point of the thermoplastic resin as the main material forming the support layer.

  Thus, the time which heat-processes with respect to the lamination sheet before a connection is preferable so that the nanofiber nonwoven fabric which comprises a connection layer may not be melt | dissolved completely, Usually, it is about 10 to 30 seconds.

In addition, it is preferable to press the laminated sheet before connection using a calendar roll or the like during the heat treatment or immediately after the heat treatment. By pressing, the connection state of each layer can be made stronger and uniform.
The strength of the pressing force applied to the laminated sheet during the pressing treatment may be appropriately adjusted according to the material forming each layer of the laminated sheet, the conditions of the heat treatment, etc., but usually 0.1 to 1 MPa. Degree.

  The laminated sheet of the present invention produced by the above method has the following characteristics.

  The laminated sheet of the present invention has a contact layer made of a nanofiber nonwoven fabric having a soft texture but low tensile strength, and a support layer made of a fibrous porous material having a high tensile strength but having a little hardness through a connecting layer. Since they are connected, the entire laminated sheet is highly flexible and durable, and the surface of the adhesive layer has a soft texture and a smooth touch. Therefore, for example, when it is used as a cosmetic sheet or a wound covering sheet, the touch is felt smoothly and the adhesiveness is high, and it is difficult to break and the handleability is excellent.

  Further, in the laminated sheet of the present invention, since the connecting layer is formed of a nanofiber nonwoven fabric having a very small fiber diameter and a soft texture, the soft texture of the contact layer also formed of the nanofiber nonwoven fabric may be impaired. Absent. Furthermore, since the nanofiber nonwoven fabric forming the connection layer has a narrow fiber gap, it covers and hides the irregularities on the surface of the fibrous porous layer that forms the support layer, and the fibers constituting the fibrous porous layer reach the surface of the contact layer. Protruding can be prevented. Therefore, the surface of the contact layer can be felt soft and smooth.

  Further, in the laminated sheet of the present invention, since the connecting layer is formed of a nanofiber nonwoven fabric, for example, when used as a cosmetic sheet or a wound covering sheet by being impregnated with skin lotion or disinfecting liquid and sticking to the skin In this case, a strong capillary force is generated not only in the contact layer but also in the connecting layer, so that a lotion, a disinfectant, and the like can be held for a long time. Therefore, active ingredients such as skin lotion and disinfectant can be sufficiently distributed to the necessary portions of the skin surface.

  Moreover, since the nanofiber nonwoven fabric of a connection layer has the very small fiber diameter of the nanofiber which comprises it, a surface area is large, and when it laminates | stacks, a contact area with the nonwoven fabric of another layer can be enlarged. Accordingly, the tie layer is very strongly connected to the support layer and the contact layer. Therefore, even when the contact layer and the support layer are formed of a heat infusible material or the like, which is generally considered to be difficult to thermally weld, heating is performed at a temperature at which the connection layer formed of the thermoplastic resin melts. By doing so, each layer can be strongly connected.

  Furthermore, in the laminated sheet of the present invention, when the contact layer is formed of a thermoplastic resin having a softening point higher than the melting point of the thermoplastic resin forming the coupling layer, each layer is produced during the production of the laminated sheet. After being laminated, the nanofibers of the connecting layer are heated by heating at a temperature higher than the melting point of the thermoplastic resin forming the connecting layer and lower than the softening point of the thermoplastic resin forming the contact layer. Each layer can be thermally welded without melting the nonwoven fabric and softening the nanofiber nonwoven fabric of the contact layer. Therefore, the nanofiber nonwoven fabric of the contact layer that is easily thermally deformed because the fiber diameter is extremely small can be strongly connected between the layers without deteriorating the soft texture and smooth texture of the surface without causing thermal deformation.

Moreover, in the laminated sheet of the present invention, the support layer and the contact layer can be strongly connected by setting the basis weight of the nanofiber nonwoven fabric constituting the connecting layer to 0.1 to 1 g / m ² , and the flexibility of the entire laminated sheet. Can be increased.

  Furthermore, in the laminated sheet of the present invention, when the average fiber diameter of the nanofiber nonwoven fabric constituting the contact layer is 50 to 280 nm, the surface of the adhesive layer has a particularly soft texture and a smooth touch. Therefore, for example, when used as a face mask sheet or eye sheet by impregnating lotion or the like and affixing to the skin, the adhesion to the skin is good, and the inconvenience of dropping off from the skin during use is unlikely to occur. Furthermore, it is possible to obtain a laminated sheet that is less irritating to the skin and hardly causes rough skin. Therefore, such a laminated sheet can be suitably used as a cosmetic sheet or a wound-covering sheet that is used in contact with the skin.

  Next, the manufacturing method of the lamination sheet of this invention has the following characteristics.

According to the method for producing a laminated sheet of the present invention, when the laminated sheet of the present invention is produced, the thermoplastic resin forming the connection layer is melted, but the main material forming the support layer and the contact layer is not melted. Since it heats, only a connection layer can be melt | dissolved and it can function as an adhesive agent, and can connect each layer.
Here, since the connection layer is formed of a nanofiber nonwoven fabric with a very small fiber diameter, the surface area is large, and when laminated, the contact area with the nonwoven fabric of the other layer can be increased. And can be very strongly coupled with the contact layer.

  Further, in the method for producing a laminated sheet of the present invention, when the laminated sheet of the present invention is produced, the temperature of the thermoplastic resin that forms the connecting layer and the temperature of the thermoplastic resin that forms the contact layer If heating is performed at a temperature lower than the softening point, only the connecting layer can be melted to function as an adhesive, and the layers can be connected, and the contact diameter of the contact layer easily deformed due to the extremely small fiber diameter. Thermal deformation of the nanofiber nonwoven fabric can be reliably prevented. Therefore, the soft texture and smooth touch of the contact layer surface can be maintained in a good state.

<Example>
The laminated sheet of this invention was manufactured and the performance was evaluated.

(1) Production of laminated sheet (1-1) Formation of base material layer Rayon fiber and PET fiber are mixed at a mass ratio of 65:35 and entangled by a spunlace method to form a fibrous porous support layer. did. The obtained fibrous porous had an average fiber diameter of 13 μm and a basis weight of 50 g / m ² .

(1-2) Continuous Formation of Connecting Layer and Contact Layer “Low Melting Point Nylon” (melting point: 138 ° C.) which is a raw material of the connecting layer is a mass ratio of an acetic acid solution having a concentration of 99% by mass and a formic acid solution having a concentration of 99% by mass. A low-melting nylon solution was prepared by dissolving in a solvent obtained by mixing 2: 1 so that the concentration of the low-melting nylon was 10% by mass.

Next, the low-melting-point nylon solution was poured into a solution tank in which the rotating electrode was installed in an electrospun nonwoven fabric manufacturing apparatus (manufactured by El Marco Co.) equipped with a rotating electrode.
Thereafter, the fibrous porous material of the support layer was placed at a nanofiber accumulation position 18 cm away from the rotating electrode of the nonwoven fabric manufacturing apparatus, and then a voltage of 80 kV was applied to the rotating electrode, and the low melting point nylon solution in the solution tank The nanofiber nonwoven fabric of the linking layer was formed by releasing the fiber into a large number of yarns and accumulating the nanofibers on the fibrous porous surface of the support layer while spinning.

Next, “nylon 6” (melting point: 220 ° C., softening point: 190 ° C.), which is a raw material of the contact layer, is mixed with a 99% by mass acetic acid solution and a 99% by mass formic acid solution in a mass ratio of 2: 1. A nylon 6 solution is prepared by dissolving the nylon 6 in the obtained solvent so that the concentration of nylon 6 is 10% by mass, and the nylon 6 solution is placed in a solution tank in which the rotating electrode of the electrospun nonwoven fabric manufacturing apparatus is installed. Infused into.
After that, the fibrous porous material in which the nanofiber nonwoven fabric of the connection layer is laminated is installed at a nanofiber accumulation position that is 18 cm away from the rotating electrode of the nonwoven fabric manufacturing apparatus, and then a voltage of 80 kV is applied to the rotating electrode, The nylon 6 solution inside was released into a number of yarns, and the nanofiber nonwoven fabric of the contact layer was formed by spinning and collecting the nanofibers on the surface of the nanofiber nonwoven fabric of the connecting layer.

The average fiber diameter of the nanofiber nonwoven fabric of the obtained coupling layer was 100 nm, and the basis weight was 0.3 g / m ² . The average fiber diameter of the nanofiber nonwoven fabric of the contact layer is 150 nm, the basis weight was 0.5 g / ^{m 2.}

(1-3) Connection of each layer Next, the pre-connection laminated sheet made of the three layers produced by the above method is heated at 140 ° C. for 30 seconds using a constant temperature continuous bonding apparatus (Asahi Textile Machinery Co., Ltd.) Then, using a calender roll having a smooth surface, pressing was performed with a pressing force of 0.3 MPa to connect the layers to produce a laminated sheet.

(2) Evaluation of Laminated Sheet The laminated sheet produced by the method (1) was highly flexible and durable, and the surface of the contact layer had a soft texture and a smooth touch. Moreover, the peeling strength between a support layer and a connection layer is 10 gf, and it connected with the intensity | strength which does not peel in the normal use aspect of a lamination sheet.
Furthermore, when this laminated sheet was impregnated with lotion and affixed to the skin of the back of the hand, the adhesiveness was good, and even after about 30 minutes in that state, it maintained a sufficiently wet state, It did not fall off the skin.

<Test example>
In the laminated sheet of “Example”, only the basis weight of the connecting layer was changed as shown in the following “Table 1 Connecting basis weight” column, and the other samples were prepared using the same raw materials and methods. did. Here, the basis weight of the connection layer was changed by adjusting the formation time of the nanofiber nonwoven fabric of the connection layer. Note that sample e is equivalent to the above example.
The test was performed for each item of “peel strength”, “flexibility of laminated sheet”, and “flexibility of laminated sheet”, and the results are shown in Table 1.

The test methods and evaluation criteria are described below.
(1) Peel strength test The laminate sheet of each sample was sandwiched between the thumb and forefinger, and the finger was moved in a horizontal direction to examine the difficulty of peeling between the support layer and the connecting layer.
The evaluation criteria were “A” when the support layer and the connecting layer were extremely difficult to peel, “B” when hard to peel, and “C” when peeled slightly easily, and extremely easy peeling. The case was designated as “D”.

(2) Measurement of bending resistance of laminated sheet A test piece of 20 × 150 mm was cut out from the laminated sheet of each sample, and the bending resistance of each sample was measured using a 45 degree cantilever testing machine.

(3) Test of flexibility of laminated sheet From each laminated sheet of each sample, a test piece of 20 × 40 mm is cut out, impregnated with water, and applied to the skin of the back of the hand, so that its adhesion (easy to follow the skin) )).
The evaluation criteria were “A” when the sample was extremely soft and very close to the skin, “B” when the sample was soft and highly adhesive, and “C” when the sample was slightly low. .

From Table 1, when the basis weight of the nanofiber nonwoven fabric of the connection layer is 0.1 g / m ² or more, the peel strength between the support layer and the connection layer is high, and the basis weight is 0.2 g / m ² or more. It can be understood that the peel strength is extremely high.
Moreover, when the fabric weight of the nanofiber nonwoven fabric of a connection layer is 1.0 g / m < ² > or less, it can understand that a laminated sheet becomes flexible and the bending softness of the laminated sheet in that case will be 122 mm or less. Further, if the basis weight is 0.8 g / m ² or less, it can be understood that the laminated sheet becomes extremely flexible, and the bending resistance of the laminated sheet at that time is 99 mm or less.

  The laminate sheet and the laminate sheet manufacturing method according to the present invention are used in the field of manufacturing laminate sheets that can be used for cosmetic sheets such as face mask sheets and eye sheets, wound covering sheets used to cover wounds, and the like. Is.

Claims (6)

A contact layer made of a nanofiber nonwoven fabric and brought into contact with an object, a support layer made of a fibrous porous material, and a connection layer made of a nanofiber nonwoven fabric provided between the support layer and the contact layer and connected to both layers Prepared
The connection layer is formed of a thermoplastic resin,
The contact layer and the support layer are formed of a thermo-insoluble material or a thermoplastic resin having a melting point higher than that of the thermoplastic resin forming the coupling layer as a main material. Sheet.   The contact layer is formed of a thermoplastic resin, and the thermoplastic resin has a softening point higher than a melting point of the thermoplastic resin forming the connection layer. Laminated sheet. Laminated sheet according to claim 1 or 2, wherein the basis weight of the nanofiber nonwoven fabric constituting the connecting layer is 0.1 to 1 g / m ^2.   4. The laminated sheet according to claim 1, wherein the nanofiber nonwoven fabric constituting the contact layer has an average fiber diameter of 50 to 280 nm, and the object to be contacted with the contact layer is skin. It is a manufacturing method of the lamination sheet according to claim 1,
After sequentially laminating the connection layer and the contact layer on at least one side of the support layer,
A method for producing a laminated sheet, characterized in that the thermoplastic resin forming the connection layer is melted but the main materials forming the support layer and the contact layer are heated at a temperature that does not melt, thereby connecting the layers. It is a manufacturing method of the lamination sheet according to claim 2,
After sequentially laminating the connection layer and the contact layer on at least one side of the support layer,
The thermoplastic resin forming the coupling layer is melted but the main material forming the support layer is not melted, and is heated at a temperature lower than the softening point of the thermoplastic resin forming the contact layer. A method for producing a laminated sheet, wherein the layers are connected together.