Laminated paper, package including the laminated paper, and processed paper product obtained by processing the laminated paper

Abstract

To provide laminated paper that is less prone to curling under severe conditions such as a high-temperature and high-humidity environment.SOLUTION: Laminated paper includes at least base paper A, an adhesion layer A and base paper B in the stated order. The constituent pulp of the base paper A has a length-weighted mean fiber length of 0.50 mm-2.00 mm, the constituent pulp of the base paper B has a length-weighted mean fiber length of 0.60 mm-2.40 mm, the base paper A has basis weight of 160 g / m2-650 g / m2, the base paper B has basis weight of 50 g / m2-280 g / m2, and the basis weight of the base paper A and the basis weight of the base paper B satisfy a relationship of the basis weight of the base paper A≥the basis weight of the base paper B.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an interleaf paper formed by bonding a plurality of papers together, and also to a packaging body including the interleaf paper, and a processed paper product obtained by processing the interleaf paper. [Background technology]

[0002] Interleaving paper is a thick paper made by pasting together multiple sheets of paper, and is mainly used for picture books, albums, etc. For example, Patent Document 1 discloses a braille interleaving bookbinding method that is resistant to warping, scratches, and stains, is durable and not easily broken, and can be mass-produced at low cost.

[0003] Meanwhile, in the field of food packaging, skin packs are used to maintain the freshness and extend the shelf life of food, in which the food is placed on a tray and the tray and food are vacuum-packed using a barrier film. Skin packs, particularly when used to package meat and other foods, can suppress dripping (water that escapes from food during storage), which can extend the expiration date and reduce food waste, and so are increasingly being used.

[0004] In this context, taking into consideration design aspects such as printability and reduced environmental impact, skin packs have been developed in which food is placed on a paper backing and then packed in film, instead of plastic trays made of polystyrene or polypropylene. For example, Patent Document 2 discloses a skin pack package in which a backing sheet has a base material, a release layer, and an adhesive layer, and a skin pack film is adhered to the base material via the adhesive layer, with the aim of providing a skin pack package that allows the packaged item to be easily removed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-98162 A [Patent Document 2] JP 2014-181075 A Summary of the Invention [Problem to be solved by the invention]

[0006] Skin pack mounts using a paper substrate have a laminated structure in which a resin layer is provided on the paper substrate from the viewpoints of preventing deterioration when in contact with food and adhesion to the skin pack film. However, due to the difference in properties between paper and resin, curling may occur, especially under harsh conditions such as high temperature and humidity or environments with rapid temperature changes. Curling can cause problems such as difficulty in packaging with a skin pack film, and even if packaging is possible, problems such as poor adhesion to the skin pack film and deterioration of design can occur. Therefore, an object of the present invention is to provide an interleaf paper that reduces the occurrence of curling even under harsh conditions such as a high-temperature and high-humidity environment. [Means for solving the problem]

[0007] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by using base papers that make up the interleaving paper, each of which has a specific length-weighted average fiber length and basis weight, and bonding these base papers together via an adhesive layer to form an interleaving paper. That is, the present invention provides the following: <1> ~ <11> Regarding. <1> An interleaving paper including at least a base paper A, an adhesive layer A, and a base paper B in this order, The length-weighted average fiber length of the pulp constituting the base paper A is 0.50 mm to 2.00 mm, and the length-weighted average fiber length of the pulp constituting the base paper B is 0.60 mm to 2.40 mm. can be, The basis weight of the base paper A is 160 g / m 2 ~650g / m 2 and the base paper B has a basis weight of 50 g / m 2 ~280g / m 2 and the basis weight of the base paper A and the basis weight of the base paper B satisfy the relationship of basis weight of base paper A≧basis weight of base paper B. <2> The amount (number) of ultrafine fibers having a fiber length of 0.2 mm or less in the pulp constituting the base paper A and the base paper B is 7.0% to 23.0%, respectively. <1> The interleaving paper described in. <3> The basis weight of the base paper A and the basis weight of the base paper B are such that the basis weight of the base paper A - the basis weight of the base paper B ≥ 50 g / m 2 , satisfy the relationship, <1> or <2> The interleaving paper described in. <4> The interleaf paper has a front surface and a back surface, and has a thermoplastic resin layer on at least one of the surfaces. <1> ~ <3> 2. The interleaving paper according to claim 1 . <5> The adhesive layer A contains a polyolefin resin. <1> ~ <4> 2. The interleaving paper according to claim 1 . <6> The slip sheet has an adhesive layer B between at least one of the surfaces and the thermoplastic resin layer. <4> The interleaving paper described in. <7> The adhesive layer B contains a water-based adhesive. <6> The interleaving paper described in. <8> The aqueous adhesive is at least one selected from the group consisting of an acrylic adhesive, a polyurethane adhesive, and an isocyanate adhesive. <7> The interleaving paper described in. <9> This is a backing for skin packs. <1> ~ <8> 2. The interleaving paper according to claim 1 . <10> <9> The present invention comprises the interleaf paper according to claim 1, a stored article, and a resin film, The package, in which the article is contained between the interleaf paper and the resin film. <11> <1> ~ <9> 2. A paper product obtained by processing the interleaf paper according to any one of claims 1 to 11. Effect of the Invention

[0008] According to the present invention, it is possible to provide an interleaf paper in which curling is reduced even under severe conditions such as a high-temperature and high-humidity environment. [Brief description of the drawings]

[0009] [Figure 1] 1 is an example of an embodiment of an interleaf paper including two paper base layers (base paper A and base paper B). [Diagram 2]FIG. 2 is a diagram showing, with broken lines, the four corners evaluated when evaluating curling of the slip sheets produced in the Examples and Comparative Examples. [Diagram 3] 1 is another example of an embodiment of an interleaf paper including two paper base layers (base paper A and base paper B). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In this specification, the description of "X or more and Y or less" or "X to Y" representing a numerical range means a numerical range including the lower and upper limits which are the endpoints, unless otherwise specified. When a numerical range is described in stages, the upper and lower limits of each numerical range can be arbitrarily combined.

[0011] <Interleaf paper> The interleaf paper according to this embodiment is an interleaf paper including at least base paper A, adhesive layer A, and base paper B in this order. The interleaf paper may be made of only base paper A, adhesive layer A, and base paper B, or may be an interleaf paper in which another base paper is laminated via an adhesive layer. The interleaf paper may have a thermoplastic resin layer on either or both of the front and back surfaces. The thermoplastic resin layer may be laminated on either or both of the front and back surfaces of the interleaf paper via adhesive layer B. FIG. 1 shows an embodiment in which the interleaf paper 10 has a thermoplastic resin layer 4 on both the front and back surfaces. In FIG. 1, the base paper 1 and the base paper 2 are laminated via an adhesive layer 3, and the outer surfaces of the base paper 1 and the base paper 2 have a thermoplastic resin layer 4. In addition, The oil layer 4 may be a film having a barrier function. Fig. 3 shows another embodiment in which an adhesive layer 5 and a thermoplastic resin layer 4 are provided on both the front and back surfaces of the interleaf paper 10. In Fig. 3, the base paper 1 and the base paper 2 are laminated via an adhesive layer 3, and a thermoplastic resin layer 4 is laminated on the outer surfaces of the base paper 1 and the base paper 2 via an adhesive layer 5. The thermoplastic resin layer 4 on the front and / or back surface of the interleaf paper 10 may be a film having a barrier function.

[0012] <Base paper A and base paper B> The base paper A and the base paper B (hereinafter sometimes referred to as the "paper base layer") are not particularly limited as long as they are commonly used papers, and are preferably papers whose main component is plant-derived pulp, and more preferably papers whose main component is wood pulp. Specifically, kraft paper, fine paper, (white) paperboard, base paper for paper containers, base paper for milk cartons, base paper for cups, liner paper, coated paper, one-sided glossy paper, glassine paper, graphene paper, etc. are mentioned, among which kraft paper, fine paper, (white) paperboard, base paper for paper containers, base paper for cups, and one-sided glossy paper are preferred, and among (white) paperboards, high-grade paperboard, special paperboard, base paper for cups, and kraft paper are more preferred in terms of rigidity. Examples of kraft paper include bleached kraft paper, unbleached kraft paper, and one-sided glossy bleached kraft paper, and from the standpoint of printability and hygiene, bleached kraft paper and one-sided glossy bleached kraft paper are preferred.

[0013] In this embodiment, the length-weighted average fiber length of the pulp constituting base paper A is 0.50 mm to 2.00 mm, and the length-weighted average fiber length of the pulp constituting base paper B is 0.60 mm to 2.40 mm. By setting the length-weighted average fiber lengths of the pulp constituting base paper A and base paper B within the above ranges, it is possible to suppress the occurrence of curling when stress is applied to the base paper due to temperature changes, etc.

[0014] It is presumed that when the length-weighted average fiber length of the pulp constituting the base paper is less than the lower limit, the stiffness of the base paper is weakened, making it more likely to curl, whereas when the length-weighted average fiber length of the pulp constituting the base paper is more than the upper limit, the fibers absorb moisture and bend due to temperature changes, etc., making it more likely to curl. The length-weighted average fiber length of the pulp constituting base paper A is more preferably 0.60 mm to 1.90 mm, even more preferably 0.70 mm to 1.50 mm, and particularly preferably 0.70 mm to 1.20 mm. The length-weighted average fiber length of the pulp constituting base paper B is more preferably 0.80 mm to 2.20 mm, even more preferably 0.90 mm to 1.80 mm, and particularly preferably 0.90 mm to 1.50 mm.

[0015] The length-weighted average fiber length of the pulp constituting base paper A and base paper B is measured in accordance with ISO 16065-2:2007. Specifically, the method is as follows. The base paper is cut into 40 cm squares, soaked in ion-exchanged water, and adjusted to a solids concentration of 2% by mass, and then soaked for 24 hours. After soaking for 24 hours, a standard disintegrator (manufactured by Kumagai Riki Kogyo Co., Ltd.) is used to disintegrate the pulp into fibers for 20 minutes. If undisintegrated pulp remains, disintegration is performed again for 20 minutes to disintegrate the pulp into fibers. If the base paper has a resin layer, the above disintegration is performed with the resin layer, and the slurry (dispersion of pulp fibers) is separated. If the resin layer can be removed, it is preferable to perform the disintegration with the resin layer removed. The disintegration is performed in accordance with JIS P8220-2:2012.

[0016] The obtained fiber samples are used to measure the "length-weighted average fiber length" using a fiber length measuring instrument (model FS-5 with UHD base unit, manufactured by Valmet) in accordance with ISO 16065-2:2007. In addition, the device can detect and measure each fiber using the attached camera, and meets ISO 9001. According to the 16505-2:2007 standard, the image is captured in a measurement cell with a depth of field of 0.5 mm. The instrument calculates the fiber content of different fiber lengths between 0.01 mm and 10.00 mm, so that the content of any range of fibers in terms of fiber length can be calculated based on the total content of fiber length. Therefore, the "ultra-small fiber content" described later is also measured by the same instrument. In the present invention, the ultra-small fiber described later means a fiber with a fiber length of 0.2 mm or less.

[0017] Of the pulp constituting base paper A and base paper B, the amount (number) of very small fibers with a fiber length of 0.2 mm or less is preferably 7.0% to 23.0%, more preferably 9.0% to 20.0%, and even more preferably 10.0% to 16.0%. It is presumed that by having the amount of ultrafine fibers within the above range, the ultrafine fibers penetrate into the gaps between the fibers in an appropriate amount, thereby increasing stiffness, and that the presence of an appropriate amount of ultrafine fibers relieves stress and suppresses curling.

[0018] In order to adjust the length-weighted average fiber length of the pulp constituting base paper A and base paper B to the above range, it is preferable to add ultrafine fibers obtained by pulverizing hardwood kraft pulp such as hardwood bleached kraft pulp with a known pulverizing device such as a cutter mill in the preparation of the pulp. Furthermore, by adding ultrafine fibers, the proportion of the ultrafine fibers becomes easier to control.

[0019] The basis weight of base paper A is 160 g / m 2 ~650g / m 2 and 200 g / m 2 ~600g / m 2 It is preferable that: From the viewpoint of moldability, the density of base paper A is set to 0.50 g / cm 3 ~1.20g / cm 3 and more preferably 0.70 g / cm 3 ~1.00g / cm 3 It is. The thickness of the base paper A is preferably 100 μm to 1000 μm, more preferably 200 μm to 800 μm, even more preferably 240 μm to 750 μm, still more preferably 240 μm to 700 μm, particularly preferably 400 μm to 750 μm, and most preferably 500 μm to 700 μm.

[0020] The base paper A may have a single layer or multiple layers, but is preferably multi-layered from the viewpoint of freely adjusting the raw material composition and basis weight of each layer, papermaking conditions, etc. In the case of paper having a multi-layer structure, the number of layers constituting the base paper A is usually 2 to 10, preferably 3 to 9, more preferably 4 to 8, and even more preferably 4 to 6.

[0021] The basis weight of base paper B is 50 g / m 2 ~280g / m 2 and 60 g / m2 ~240g / m 2 It is preferable that the thickness is 100 g / m 2 ~240g / m 2 More preferably, it is 150 g / m 2 ~240g / m 2 It is more preferable that the basis weight of base paper A and the basis weight of base paper B satisfy the relationship of "basis weight of base paper A ≧ basis weight of base paper B," and that the basis weight of base paper A > basis weight of base paper B is greater than or equal to 50 g / m. 2 It is more preferable that the relationship between the basis weight of base paper A and the basis weight of base paper B is satisfied, since it is possible to effectively suppress curling and also improve the punching processability, which is preferable. From the viewpoint of moldability, the density of base paper B is set to 0.50 g / cm 3 ~1.20g / cm 3 and more preferably 0.70 g / cm 3 ~1.00g / cm 3 and more preferably 0.75 g / cm 3 ~1.00g / cm 3 and particularly preferably 0.81 g / cm 3 ~1.00g / cm 3 It is. The thickness of the base paper B is preferably 50 μm to 500 μm, more preferably 60 μm to 300 μm, and further preferably 70 μm to 250 μm.

[0022] The base paper B may be a single-layered or multi-layered paper. It is preferable that the basis weight is set low, and from the viewpoint of productivity, it is preferable that the sheet has a single layer structure.

[0023] As described above, the raw material pulp constituting the base paper A and the base paper B is preferably wood pulp, and more preferably kraft pulp. As kraft pulp, hardwood kraft pulp (LKP) and softwood kraft pulp (NKP) can be mentioned based on the difference in raw materials. Also, bleached kraft pulp (BKP), unbleached kraft pulp (UKP) and oxygen bleached kraft pulp (OKP) can be mentioned based on the difference in processing state, and bleached kraft pulp (BKP) is preferred from the viewpoint of printability. Among these, the raw material pulp is preferably hardwood kraft pulp (LKP) or softwood kraft pulp (NKP), and more preferably a combination of hardwood kraft pulp (LKP) and softwood kraft pulp (NKP). When hardwood kraft pulp (LKP) and softwood kraft pulp (NKP) are used in combination, the mass ratio (LKP / NKP) is not particularly limited as long as it is a ratio used in general paper, and is preferably 1 / 99 to 99 / 1, more preferably 20 / 80 to 99 / 1, even more preferably 30 / 70 to 99 / 1, even more preferably 70 / 30 to 99 / 1, and even more preferably 80 / 20 to 95 / 5. Moreover, as the hardwood kraft pulp (LKP), hardwood bleached kraft pulp (LBKP) is preferable, and as the softwood kraft pulp (NKP), softwood bleached kraft pulp (NBKP) is preferable.

[0024] When preparing the raw pulp, internal additives may be added, such as sizing agents, fillers, paper strength agents, retention aids, pH adjusters, drainage improvers, water resistance agents, softeners, antistatic agents, defoamers, slime control agents, dyes and pigments, etc.

[0025] A known wet paper machine can be appropriately selected and used in making the base paper A and the base paper B. Examples of the paper machine include a Fourdrinier paper machine, a gap former type paper machine, a cylinder paper machine, and a short wire paper machine. The paper layer formed by the paper machine is preferably conveyed, for example, on a felt and dried in a dryer. A multi-stage cylinder dryer may be used as a pre-dryer before drying in the dryer.

[0026] The base paper obtained as described above may be surface-treated with a calendar to make the thickness and profile uniform. For the calendar treatment, a known calendaring machine can be appropriately selected and used.

[0027] The base paper A and the base paper B preferably have an Oken smoothness (JIS P 8155:2010) of 5 seconds or more, more preferably 10 to 1000 seconds. From the viewpoint of printability, the base paper A and the base paper B preferably have a 75° gloss of 5% or more, more preferably 10 to 70%.

[0028] The design of the resulting interleaf paper can be improved by directly printing on at least one, and preferably both, of the front and back surfaces (outermost surfaces) of base paper A and base paper B. Furthermore, by providing an additional printed layer on the surface of base paper A and base paper B, various printing methods can be selected without being affected by the quality of the base papers that make up the interleaf paper, and further design properties can be imparted to the interleaf paper.

[0029] <Adhesive layer A> Base paper A and base paper B are laminated via adhesive layer A. Adhesive layer A may be any layer made of a material having adhesive properties, but preferably contains a thermoplastic resin. By using a thermoplastic resin, it is possible to easily obtain an interleaving paper that is a laminate by coating at least one of the base papers with a heated and melted resin and pasting the other base paper onto it.

[0030] The thermoplastic resin preferably contains at least one selected from the group consisting of polyolefin-based resins, polyester-based resins, polylactic acid, styrene-based resins, and acrylic-based resins, and more preferably contains a polyolefin-based resin. Examples of polyolefin resins include polyethylene (LDPE, MDPE, HDPE, LLDPE, etc.), polypropylene, polymethylpentene, etc., of which polyethylene is preferred, as it has good extrusion lamination properties. From the viewpoint of ease of coating on base paper, LDPE (low density polyethylene) and MDPE (medium density polyethylene) are more preferred.

[0031] The adhesive layer A may be formed by laminating the base paper A and the base paper B using an adhesive described later. The adhesive is not particularly limited, and water-based, solvent-based, UV-based, and other types of adhesives can be used, among which water-based adhesives are preferred. Among the water-based adhesives, at least one selected from the group consisting of acrylic adhesives, polyurethane adhesives, and isocyanate adhesives is preferred, and acrylic adhesives are more preferred from the viewpoints of ease of control of adhesive strength and heat resistance.

[0032] When using an adhesive, the amount of adhesive layer A per unit area is 1 g / m 2 ~50g / m 2 is preferably 1 g / m 2 ~20g / m 2 When forming the adhesive layer A, it is preferable to coat the adhesive onto the base paper A or the base paper B so that the solid content is this amount.

[0033] The adhesive layer A may be formed as a single layer of a single resin, or may be formed as a single layer of a mixture of multiple resins, or may be formed as multiple layers made of the same or different types of resins. The thickness of the adhesive layer A is not particularly limited, but from the viewpoint of moldability, it is preferably 5 μm to 100 μm, and more preferably 10 μm to 50 μm.

[0034] <Thermoplastic resin layer> The interleaf paper according to the present embodiment has a front surface and a back surface, and may have a thermoplastic resin layer on at least one of the surfaces. The thermoplastic resin layer serves to protect the interleaf paper surface from stored items such as food, and to protect the stored items from external stimuli such as oxygen. In addition, for example, when the stored items are sandwiched between the interleaf paper and a resin film and stored, the thermoplastic resin layer serves to adhere to the resin film.

[0035] The thermoplastic resin layer may be a single layer of a thermoplastic resin or a laminate containing a thermoplastic resin, but is preferably a laminate containing a barrier layer, and is particularly preferably a laminate having a barrier layer intermediate thermoplastic resin layers, such as "thermoplastic resin layer / barrier layer / thermoplastic resin layer." The barrier layer may be any layer capable of blocking oxygen and water vapor. Specifically, it is preferably at least one selected from the group consisting of polyamide resins, polyvinyl alcohol, ethylene-vinyl alcohol copolymers, and polyvinylidene chloride resins, more preferably at least one selected from the group consisting of polyamide resins, polyvinyl alcohol, and ethylene-vinyl alcohol copolymers, and may be a multi-layer structure of two or more layers. The barrier layer may also be a metal foil.

[0036] As the polyamide-based resin, aromatic polyamide is preferable, and polyamide MXD6 is more preferable. When the thermoplastic resin layer is a laminate containing a thermoplastic resin, the thickness of the barrier layer included therein is preferably 3 μm to 100 μm, more preferably 4 μm to 50 μm, and even more preferably 5 μm to 30 μm. In addition to the above materials, biomass resin or biodegradable resin may be used as the resin. These resins may be used alone or in combination of two or more.

[0037] The thermoplastic resin layer may be a laminate layer, which will be described later.

[0038] The total thickness of the thermoplastic resin layer is preferably from 1 μm to 200 μm, more preferably from 5 μm to 100 μm, further preferably from 10 μm to 80 μm, and particularly preferably from 10 μm to 50 μm.

[0039] <Adhesive layer B> When the surface of the thermoplastic resin layer has adhesive properties, the thermoplastic resin layer may be directly adhered to the surface of the paper base layer. However, in order to prevent peeling during transportation and display, it is preferable to have an adhesive layer B between the paper base layer and the thermoplastic resin layer. The adhesive constituting the adhesive layer B is not particularly limited, but is preferably a resin-based adhesive suitable for dry lamination and wet lamination. Specifically, the adhesive constituting the adhesive layer B may be of a water-based, solvent-based, UV-based or other type, and among these, a water-based adhesive is preferred. Among the water-based adhesives, at least one selected from the group consisting of an acrylic adhesive, a polyurethane adhesive, and an isocyanate adhesive is preferred, and an acrylic adhesive is more preferred. The amount of adhesive layer B per unit area is 1 g / m 2 ~50g / m 2 is preferably 1 g / m 2 ~20g / m 2 When forming the adhesive layer B, it is preferable to coat the adhesive on the surface of the paper base layer or the surface of the thermoplastic resin layer so that the solid content is in this amount. For coating, it is preferable to use a coating liquid containing an adhesive, and it is more preferable to use a mixed coating liquid in which a curing agent is mixed into a coating liquid containing an adhesive.

[0040] <Method of manufacturing interleaf paper> The method for producing the interleaf paper of the present embodiment is not particularly limited, and any known method can be used. An example of the production method is shown below. First, base paper A and base paper B are prepared, one side of base paper A is melt-extrusion coated with a thermoplastic resin that will become adhesive layer A, and base paper B is laminated to this coated surface to obtain an interleaf paper. From the viewpoint of improving waterproofness and stain resistance, one or both sides of the obtained interleaf paper may be provided with a laminate layer as a thermoplastic resin layer. The thermoplastic resin layer may also be provided via adhesive layer B. A film may also be laminated to obtain a film-coated interleaf paper.

[0041] The thermoplastic resin used in the laminate layer is not particularly limited as long as it can be laminated to the slip sheet, and may be appropriately selected from known thermoplastic resins. Specific examples include polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polylactic acid, and polybutylene succinate; polyolefin-based resins such as polyvinyl chloride, polyvinylidene chloride, polybutene, polybutadiene, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, ethylene-propylene copolymer, and polymethylpentene; polycarbonate; polyurethane; polyamide; polyacrylonitrile; and poly(meth)acrylate.

[0042] Among these thermoplastic resins, polyethylene (PE) or polypropylene (PP) are preferred due to their excellent extrusion lamination properties and barrier properties. PE is classified into linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE), and low-density polyethylene (LDPE) is preferred due to its excellent extrusion lamination properties and foaming properties. The lamination method for the laminate layer is not particularly limited, and may be appropriately selected from known methods such as melt extrusion, melt casting, and calendaring.

[0043] The thermoplastic resin layer may be directly adhered to the surface of the paper base layer, or may be adhered to the surface of the paper base layer via an adhesive layer B. In the latter case, it is preferable to apply a coating liquid containing an adhesive onto the surface of the paper base layer, and then laminate the thermoplastic resin layer onto the surface of the paper base layer via the adhesive layer B.

[0044] When the thermoplastic resin layer includes a laminate having a barrier layer in the middle of the thermoplastic resin layers, such as "thermoplastic resin layer / barrier layer / thermoplastic resin layer", the thermoplastic resin may be melt-extrusion coated onto the surface of the paper base layer, a laminate film having a barrier layer in the middle of the thermoplastic resin layers is placed thereon, and the surface of the melt-extrusion coated thermoplastic resin and the surface of the thermoplastic resin layer of the laminate film are heated and fused to form the thermoplastic resin layer. By this method, a film can also be attached to an interleaf paper to produce a film-coated interleaf paper.

[0045] The slip sheet may have other layers as long as the effects of the present invention are not impaired. For example, a printed layer made of ink by offset printing may be provided on at least one of the front and back surfaces of base paper A and base paper B. When a printed layer is provided, it is preferable to provide a thermoplastic resin layer on the surface of the printed layer via adhesive layer B.

[0046] As described above, the interleaf paper contains two layers of base paper (for example, base paper A and base paper B), but it may contain three or more layers of base paper. When the interleaf paper contains three or more layers of base paper, it is preferable to use an adhesive layer similar to the adhesive layer A for bonding the base papers together.

[0047] Furthermore, the obtained interleaf paper may be cut to an appropriate size taking into consideration the size and shape of the contained items, and suitability for transportation and display. The cutting is preferably performed by punching, from the viewpoint of efficiently obtaining interleaf paper of the same shape. The punching process is preferably carried out using a high-speed automatic punching machine, a flat-bed punching machine, or a rotary punching machine, and more preferably a high-speed automatic punching machine. With the high-speed automatic punching machine or the flat-bed punching machine, interleaf sheets having a rectangular shape, a rounded rectangular shape, an oval shape, etc. can be easily and efficiently obtained.

[0048] <Skin pack mount and packaging> The interleaf paper is suitably used as a liner for a skin pack. A package using the liner for a skin pack includes an article to be contained, the liner for a skin pack, and a resin film, and the article to be contained is contained between the liner for a skin pack and the resin film, and preferably the article to be contained is sealed.

[0049] The resin film can be appropriately selected depending on the type and shape of the stored item, but preferably has excellent adhesiveness and is peelable when the stored item is removed, since it needs to be adhered to the thermoplastic resin layer of the skin pack mount to store the stored item. Therefore, the resin film is preferably made of the thermoplastic resin used in the above-mentioned thermoplastic resin layer, and more preferably has a barrier layer when the contents are food, etc. As the barrier layer, the barrier layer used in the above-mentioned thermoplastic resin layer is preferably used.

[0050] There are no restrictions on the items to be stored, and examples include food, daily necessities, etc., but preferably, since the items to be stored can be sealed, it is suitable for storing fresh foods such as vegetables, meat, fresh fish, and other processed foods.

[0051] <Paper processed products> The application of the interleaf paper is not limited to a backing paper for skin packs, and it may be used as a paper processed product by appropriately processing it. Examples of the paper processed product include paper containers such as cups and trays, paper spoons, etc. Examples of the paper cutlery include paper forks, paper knives, and other paper cutlery; paper hangers, paper hooks, and other paper clothes hangers. The processing method is not particularly limited, and known methods can be used. For example, the paper can be processed into a desired shape by press molding. EXAMPLES

[0052] The present invention will be described in detail below using examples, but the scope of the invention is not limited to the description of the examples. <Preparation of base paper A1> 85 parts by mass of hardwood bleached kraft pulp (LBKP) beaten to 480 mL of CSF, 5 parts by mass of softwood bleached kraft pulp (NBKP) beaten to 520 mL of CSF, and 10 parts by mass of ultrafine fibers were mixed and beaten to obtain a pulp slurry. The ultrafine fibers were obtained by mechanically crushing a dry sheet of LBKP with a cutter mill (manufactured by Horai Co., Ltd., model number: HA8 2542 30E, screen 0.24 mm) and separating pulp fibers with a length of 0.2 mm or less using a fiber classifier (manufactured by Aikawa Iron Works Co., Ltd., model number: MAX-F700). 0.35 parts by mass (solid content equivalent) of aluminum sulfate was added to 100 parts by mass of the obtained pulp slurry to prepare five layers of paper materials for the surface layer, the surface underlayer, the middle layer, the back underlayer, and the back layer. The Canadian Standard Freeness (CSF) of this paper stock was adjusted to 500 mL. Using this paper stock, a five-ply twin-wire paper machine was used to make paper with the same basis weight for all five plies. The basis weight was 400 g / m 2 Then, the paper was smoothed with a calendar to obtain base paper A1.

[0053] The basis weight of the base paper was measured in accordance with JIS P 8124:2011. The thickness of the base paper was measured in accordance with JIS P 8118: 2014. When a resin layer was present, the thickness was measured from an observation image of the cross section taken with a scanning electron microscope (SEM). Further, the density of the paper was calculated from the paper thickness and basis weight obtained by the above-mentioned measuring method.

[0054] <Preparation of base paper A2> Base paper A2 was obtained in the same manner as base paper A1, except that the raw materials for the pulp slurry were changed to 74 parts by mass of bleached hardwood kraft pulp (LBKP), 16 parts by mass of bleached softwood kraft pulp (NBKP), and 10 parts by mass of ultrafine fibers.

[0055] <Preparation of base paper A3> Base paper A3 was obtained in the same manner as base paper A1, except that the raw materials for the pulp slurry were changed to 56 parts by mass of bleached hardwood kraft pulp (LBKP), 34 parts by mass of bleached softwood kraft pulp (NBKP), and 10 parts by mass of ultrafine fibers.

[0056] <Preparation of A4 base paper> Base paper A4 was obtained in the same manner as base paper A1, except that the raw materials for the pulp slurry were changed to 90 parts by mass of bleached softwood kraft pulp (NBKP) and 10 parts by mass of very small fibers.

[0057] <Preparation of base paper A5> Base paper A5 was obtained in the same manner as base paper A1, except that the raw materials for the pulp slurry were changed to 78 parts by mass of hardwood bleached kraft pulp (LBKP), 14 parts by mass of softwood bleached kraft pulp (NBKP), and 8 parts by mass of very small fibers.

[0058] <Preparation of base paper A6> Base paper A6 was obtained in the same manner as base paper A1, except that the raw materials for the pulp slurry were changed to 66 parts by mass of bleached hardwood kraft pulp (LBKP), 16 parts by mass of bleached softwood kraft pulp (NBKP), and 18 parts by mass of very small fibers.

[0059] <Preparation of base paper A7> Base paper A7 was obtained in the same manner as base paper A1, except that the raw materials for the pulp slurry were changed to 82 parts by mass of hardwood bleached kraft pulp (LBKP), 13 parts by mass of softwood bleached kraft pulp (NBKP), and 5 parts by mass of very small fibers.

[0060] <Preparation of base paper A8> Base paper A8 was obtained in the same manner as base paper A1, except that the raw materials for the pulp slurry were changed to 60 parts by mass of bleached hardwood kraft pulp (LBKP), 17 parts by mass of bleached softwood kraft pulp (NBKP), and 23 parts by mass of ultrafine fibers.

[0061] <Preparation of base paper A9> Basis weight: 200g / m 2 Base paper A9 was obtained in the same manner as base paper A2, except for changing the above.

[0062] <Preparation of base paper A10> Basis weight 600g / m 2 Base paper A10 was obtained in the same manner as base paper A2, except for changing the above.

[0063] <Preparation of base paper A11> Base paper A11 was obtained in the same manner as base paper A1, except that the raw materials for the pulp slurry were changed to 90 parts by mass of bleached hardwood kraft pulp (LBKP) and 10 parts by mass of very small fibers.

[0064] <Preparation of base paper A12> Base paper A12 was obtained in the same manner as base paper A1, except that the raw materials for the pulp slurry were changed to 80 parts by mass of bleached softwood kraft pulp (NBKP), 10 parts by mass of hemp pulp, and 10 parts by mass of very small fibers.

[0065] <Preparation of base paper A13> Basis weight: 150m 2 Base paper A13 was obtained in the same manner as base paper A1, except that the raw materials for the pulp slurry were changed to 90 parts by mass of bleached hardwood kraft pulp (LBKP) and 10 parts by mass of very small fibers.

[0066] <Preparation of base paper A14> Basis weight: 150m 2 Base paper A14 was obtained in the same manner as base paper A1, except that the raw materials for the pulp slurry were changed to 80 parts by mass of bleached softwood kraft pulp (NBKP), 10 parts by mass of hemp pulp, and 10 parts by mass of very small fibers.

[0067] <Preparation of base paper B1> 68 parts by mass of hardwood bleached kraft pulp (LBKP) beaten into 520 mL of CSF, 18 parts by mass of softwood bleached kraft pulp (NBKP) beaten into 550 mL of CSF, and 14 parts by mass of ultrafine fibers were mixed and beaten to obtain a pulp slurry. Note that the ultrafine fibers were prepared by mechanically crushing a dry sheet of LBKP with a cutter mill (manufactured by Horai Co., Ltd., model number: HA8 2542 30E, screen 0.24 mm) and separating pulp fibers with a length of 0.2 mm or less using a fiber classifier (manufactured by Aikawa Iron Works Co., Ltd., model number: MAX-F700). To 100 parts by mass of the obtained pulp slurry, 0.80 parts by mass (solid content equivalent) of cationic starch (P-3T, manufactured by PIRAAB STARCH), 1.20 parts by mass of rosin emulsion (SPN, manufactured by Arakawa Chemical Industries, Ltd.), and 0.40 parts of anion-modified polyacrylamide (Polystron, manufactured by Arakawa Chemical Industries, Ltd.) were added, and paper was made using a Fourdrinier papermaking machine equipped with a Yankee dryer to obtain a paper with a basis weight of 120 g / m. 2 As a result, base paper B1 was obtained.

[0068] <Preparation of base paper B2> The raw materials for the pulp slurry were changed to 60 parts by mass of hardwood bleached kraft pulp (LBKP), 26 parts by mass of softwood bleached kraft pulp (NBKP), and 14 parts by mass of very small fibers. Base paper B2 was obtained in the same manner as base paper B1.

[0069] <Preparation of base paper B3> Base paper B3 was obtained in the same manner as base paper B1, except that the raw materials for the pulp slurry were changed to 40 parts by mass of bleached hardwood kraft pulp (LBKP), 46 parts by mass of bleached softwood kraft pulp (NBKP), and 14 parts by mass of very small fibers.

[0070] <Preparation of base paper B4> Base paper B4 was obtained in the same manner as base paper B1, except that the raw materials for the pulp slurry were changed to 76 parts by mass of bleached softwood kraft pulp (NBKP), 10 parts by mass of hemp pulp, and 14 parts by mass of very small fibers.

[0071] <Preparation of base paper B5> Base paper B5 was obtained in the same manner as base paper B1, except that the raw materials for the pulp slurry were changed to 70 parts by mass of hardwood bleached kraft pulp (LBKP), 23 parts by mass of softwood bleached kraft pulp (NBKP), and 7 parts by mass of very small fibers.

[0072] <Preparation of base paper B6> Base paper B6 was obtained in the same manner as base paper B1, except that the raw materials for the pulp slurry were changed to 52 parts by mass of bleached hardwood kraft pulp (LBKP), 28 parts by mass of bleached softwood kraft pulp (NBKP), and 20 parts by mass of very small fibers.

[0073] <Preparation of base paper B7> Base paper B7 was obtained in the same manner as base paper B1, except that the raw materials for the pulp slurry were changed to 74 parts by mass of bleached hardwood kraft pulp (LBKP), 22 parts by mass of bleached softwood kraft pulp (NBKP), and 4 parts by mass of very small fibers.

[0074] <Preparation of base paper B8> Base paper B8 was obtained in the same manner as base paper B1, except that the raw materials for the pulp slurry were changed to 44 parts by mass of bleached hardwood kraft pulp (LBKP), 30 parts by mass of bleached softwood kraft pulp (NBKP), and 26 parts by mass of very small fibers.

[0075] <Preparation of base paper B9> Basis weight 60g / m 2 Base paper B9 was obtained in the same manner as base paper B2, except that the above was changed to:

[0076] <Preparation of base paper B10> Basis weight 150g / m 2 Base paper B10 was obtained in the same manner as base paper B2, except for changing the above.

[0077] <Preparation of base paper B11> Basis weight: 200g / m 2 Base paper B11 was obtained in the same manner as base paper B2, except for changing the above.

[0078] <Preparation of base paper B12> Base paper B12 was obtained in the same manner as base paper B1, except that the raw materials for the pulp slurry were changed to 86 parts by mass of bleached hardwood kraft pulp (LBKP) and 14 parts by mass of very small fibers.

[0079] <Preparation of base paper B13> Base paper B13 was obtained in the same manner as base paper B1, except that the raw materials for the pulp slurry were changed to 56 parts by mass of bleached softwood kraft pulp (NBKP), 30 parts by mass of hemp pulp, and 14 parts by mass of very small fibers.

[0080] <Preparation of base paper B14> Basis weight 40m 2 Base paper B14 was obtained in the same manner as base paper B1, except that the raw materials for the pulp slurry were changed to 86 parts by mass of bleached hardwood kraft pulp (LBKP) and 14 parts by mass of very small fibers.

[0081] <Preparation of base paper B15> Basis weight 40m 2 Base paper B15 was obtained in the same manner as base paper B1, except that the raw materials for the pulp slurry were changed to 56 parts by mass of bleached softwood kraft pulp (NBKP), 30 parts by mass of hemp pulp, and 14 parts by mass of very small fibers.

[0082] <Example 1> One side of base paper A1 was coated with LDPE (Japan Polyethylene Corporation, LC522) by melt extrusion coating to a dry thickness of 20 μm, and base paper B1 was laminated to the coated side to obtain a two-layered interleaf paper.

[0083] <Examples 2 to 21> As shown in Table 1, a two-ply interleaf paper was obtained in the same manner as in Example 1 by using a combination of base paper A and base paper B.

[0084] <Example 22> One side of base paper A2 was melt-extrusion coated with LDPE (Japan Polyethylene Corporation, LC522) to a dry thickness of 10 μm, and base paper B2 was laminated to the coated surface to obtain a two-layered interleaf paper.

[0085] <Example 23> One side of base paper A2 was melt-extrusion coated with MDPE (NUC Corporation, 8010) to a dry film thickness of 20 μm, and base paper B2 was laminated to the coated surface to obtain a two-layer interleaf paper.

[0086] <Example 24> One side of base paper A2 was melt-extrusion coated with LDPE to a dry film thickness of 20 μm, and base paper B2 was laminated to the coated side to obtain a two-layer interleaf paper. After that, LDPE was melt-extrusion coated on the outermost surface of base paper A2 to a dry film thickness of 20 μm, to obtain a coated interleaf paper.

[0087] <Example 25> One side of base paper A2 was melt-extrusion coated with LDPE to a dry film thickness of 20 μm, and base paper B2 was laminated to the coated side to obtain a two-layer interleaf paper. After that, LDPE was melt-extrusion coated on the outermost surface of base paper A2 to a dry film thickness of 40 μm, to obtain a coated interleaf paper.

[0088] <Example 26> One side of base paper A2 was melt-extrusion coated with LDPE to a dry film thickness of 20 μm, and base paper B2 was laminated to the coated side to obtain a two-layered interleaf paper. After that, LDPE was melt-extrusion coated on both outermost surfaces of the interleaf paper to a dry film thickness of 20 μm, to obtain a coated interleaf paper.

[0089] <Example 27> One side of base paper A2 is coated with PP (PHA03A, manufactured by Japan Polyethylene Co., Ltd.) by melt extrusion coating to a dry film thickness of 20 μm, and base paper B2 is laminated to the coated surface. After obtaining two layers of interleaf paper, the outermost surface of the base paper A2 side was melt-extrusion coated with PP to a dry thickness of 20 μm to obtain a coated interleaf paper.

[0090] <Example 28> One side of base paper A2 was melt-extrusion coated with LDPE to a dry thickness of 20 μm, and base paper B2 was laminated to the coated surface to obtain a two-layered interleaf paper, after which PP was melt-extrusion coated on the outermost surface of base paper A2 to a dry thickness of 20 μm. Immediately after that, film A (Mitsubishi Chemical Corporation, Diamiron F001, thickness 40 μm) with a three-layer structure of PP / EVOH / PP was laminated onto the PP layer obtained by melt-extrusion coating, and the surface of the PP layer of film A was heat-fused to obtain a film-attached interleaf paper.

[0091] <Example 29> One side of base paper A2 was melt-extrusion coated with LDPE to a dry film thickness of 20 μm, and base paper B2 was laminated to the coated surface to obtain a two-layered interleaf paper. After that, LDPE was melt-extrusion coated on the outermost surface of base paper A2 to a dry film thickness of 20 μm. Immediately after that, film B (Mitsubishi Chemical Corporation, Diamiron YF1966, thickness 40 μm) with a three-layer structure of PE / EVOH / PP was laminated so that the PE layer faced the LDPE layer obtained by melt-extrusion coating, and the PE layer surface and the LDPE layer surface of film B were heat-fused to obtain a film-attached interleaf paper.

[0092] <Example 30> One side of base paper A2 is coated with LDPE by melt extrusion coating so that the dry thickness is 20 μm, and base paper B2 is laminated to the coated surface to obtain a two-layered laminate. After that, the outermost surface of the base paper A2 side is coated with LDPE in an amount of 10 g / m2 after heat drying. 2 An adhesive layer was formed by applying a coating liquid (water-based adhesive) made by mixing 100 parts by mass of water-based acrylic adhesive (EA-G34, manufactured by Toyo-Morton Co., Ltd.) with 3 parts by mass of hardener (CAT-EP8, manufactured by Toyo-Morton Co., Ltd.), and then laminating a film A (Diamiron F001, manufactured by Mitsubishi Chemical Corporation, thickness 40 μm) having a three-layer structure of PP / EVOH / PP to obtain a film-attached interleaf paper.

[0093] <Example 31> One side of base paper A2 is coated with LDPE by melt extrusion coating so that the dry thickness is 20 μm, and base paper B2 is laminated to the coated surface to obtain a two-layered laminate. After that, the outermost surface of the base paper A2 side is coated with LDPE in an amount of 10 g / m2 after heat drying. 2 An adhesive layer was formed by applying a coating liquid (water-based adhesive) made by mixing 100 parts by mass of water-based acrylic adhesive (EA-G34, manufactured by Toyo-Morton Co., Ltd.) with 3 parts by mass of hardener (CAT-EP8, manufactured by Toyo-Morton Co., Ltd.), and then laminating a film B having a three-layer structure of PE / EVOH / PP (Diamiron YF1966, manufactured by Mitsubishi Chemical Corporation, thickness 40 μm) with the PE layer on the outside, to obtain a film-attached interleaf paper.

[0094] <Comparative Examples 1 to 9> As shown in Table 2, a two-ply interleaf paper was obtained in the same manner as in Example 1 by using a combination of base paper A and base paper B.

[0095] <Curl evaluation> The obtained interleaf papers of Examples 1 to 31 and Comparative Examples 1 to 9 were subjected to curl evaluation as follows. The interleaving papers obtained in Examples 1 to 31 and Comparative Examples 1 to 9 were punched at 6,000 sheets / hour using an automatic flat-bed punching machine (Carton Master AP-1300-TSG-8, manufactured by Asahi Machinery Co., Ltd.) to obtain rectangular backing sheets measuring 200 mm in length (MD) × 100 mm in width (CD). Next, the slip sheets (rectangles of 200 mm length x 100 mm width) manufactured in each of the examples and comparative examples were placed in a thermostatic chamber adjusted to the conditions shown in (1) below for 24 hours. After 24 hours, the slip sheets were removed from the thermostatic chamber, and the curl state of the mount was confirmed after 5 minutes. The mount sheets were laid flat on a horizontal hard surface, and the lifting was measured at each of the four places on the mount sheets indicated by the broken lines in FIG. 2, and the average value was adopted and evaluated according to the following evaluation criteria. When laying the mount sheets flat on a horizontal hard surface, the base paper B side was laid flat on the hard surface and the lifting was measured. If no lifting occurred, the base paper A side was laid flat on the hard surface and the lifting was measured, and the result was adopted. A rating of 3 or more was considered to be good, and a rating of 2 or less was considered to be poor. (1) 40℃, 90%RH (high temperature and humidity conditions, constant temperature and humidity tester (Espec Corporation, PR-3KP)) <Evaluation criteria> 4: The backing paper was floating less than 10 mm. 3: The floating of the backing paper was more than 10 mm but less than 15 mm. 2: The floating of the backing paper was more than 15 mm but less than 20 mm. 1: The backing paper was floating by more than 20 mm.

[0096] [Table 1]

[0097] [Table 2] [Explanation of symbols]

[0098] 1, 2 Original paper 3, 5 Adhesive layer 4 Thermoplastic resin layer 10 slip paper

Claims

1. An interleaf paper including at least a base paper A, an adhesive layer A, and a base paper B in this order, the length-weighted average fiber length of the pulp constituting the base paper A is 0.50 mm to 2.00 mm, and the length-weighted average fiber length of the pulp constituting the base paper B is 0.60 mm to 2.40 mm, The basis weight of the base paper A is 160 g / m ２ ~650g / m ２ and the basis weight of the base paper B is 50 g / m ２ ~280g / m ２ and the basis weight of the base paper A and the basis weight of the base paper B satisfy the relationship of basis weight of base paper A ≧ basis weight of base paper B, The amount (number) of ultrafine fibers having a fiber length of 0.2 mm or less in the pulp constituting the base paper A and the base paper B is 7.0% to 23.0%, respectively; Interleaf paper, which is a backing for skin packs.

2. The laminated paper described in Claim 1, wherein the thickness of the base paper A is 240 μm or more.

3. The basis weight of the base paper A and the basis weight of the base paper B are such that (basis weight of base paper A - basis weight of base paper B) ≥ 50 g / m ２ The interleaf paper according to claim 1 , wherein the relationship of (a) is satisfied.

4. The interleaf paper according to claim 1 , wherein the interleaf paper has a front surface and a back surface, and a thermoplastic resin layer is provided on at least one of the surfaces.

5. The interleaf paper according to claim 1 , wherein the adhesive layer A contains a polyolefin resin.

6. The interleaf paper according to claim 4 , further comprising an adhesive layer B between the at least one surface and the thermoplastic resin layer.

7. The interleaf paper according to claim 6 , wherein the adhesive layer B contains a water-based adhesive.

8. The interleaf paper according to claim 7 , wherein the water-based adhesive is at least one selected from the group consisting of an acrylic adhesive, a polyurethane adhesive, and an isocyanate adhesive.

9. A packaging device comprising the interleaf paper according to any one of claims 1 to 8, a contained article, and a resin film, The package, in which the article is contained between the interleaf paper and the resin film.

Images