Resin-impregnated paper, laminate, lid, packaging container, and packaged article

Abstract

To provide resin-impregnated paper that exhibits high strength in the thickness direction and demonstrates resistance to deformation such as wrinkling due to dimensional changes during water absorption, as well as a laminate, a lid, a packaging container, and a packaged article comprising the same.SOLUTION: Resin-impregnated paper 100A comprises coating paper 3 having a coating layer 1 on one surface of a paper base material 2, and a cured resin composition 4a impregnated into the paper base material 2. The cured resin composition 4a fills the voids between fibers 2a forming the paper base material 2. The resin-impregnated paper has a peel strength of 5 N / 15 mm or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a resin-impregnated paper, a laminate, a lid, a packaging container, and a packaging article. [Background technology]

[0002] Laminates in which a heat seal layer is provided by coating a substrate with a heat seal varnish such as an aqueous emulsion are widely used as functional films including packaging films (see, for example, Patent Document 1, etc.). Generally, synthetic compounds derived from petroleum, such as plastics such as polyethylene, polypropylene, and polyethylene terephthalate, are used as the substrate for such functional films, but in order to reduce the burden on the environment, it is desirable to reduce the amount of synthetic compounds used. For this reason, there is an increasing demand for functional films that use paper, which is a renewable resource and has a small environmental impact, as the substrate.

[0003] Although paper has excellent mechanical strength in the in-plane direction, its strength in the film thickness direction (peel strength) is weaker than that of plastics. For this reason, when a lid made of a laminate including a paper base material is used as a lid to cover an opening of a container body having an opening, the paper base material is likely to break and peel off when the lid is peeled off. In addition, paper has a characteristic of being highly deformed by water absorption and drying. For this reason, there is also a problem that deformation such as wrinkles is likely to occur due to dimensional changes when humidity changes or when a water-based emulsion is applied to the paper base material to form a heat seal layer.

[0004] In addition to the above-mentioned properties of paper, some papers, such as beeswax paper and oil wax paper, are impregnated with wax to improve their strength and water resistance. However, such impregnated papers have low heat resistance and are not suitable for use in functional films, for example, those containing heat seal layers. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-27888 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to provide a resin-impregnated paper that has high strength in the thickness direction and is less likely to develop deformation such as wrinkles due to dimensional changes when absorbing water, as well as a laminate, a lid, a packaging container, and a packaging article that contain the same. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided a resin-impregnated paper comprising a coated paper having a coating layer on one side of a paper base material and a cured product of a resin composition impregnated into the paper base material, the cured product of the resin composition filling the voids between the fibers constituting the paper base material, and having a peel strength of 5 N / 15 mm or more.

[0008] According to another aspect of the present invention, the apparent density of the composition after storage for 24 hours in an environment having a temperature of 23° C. and a relative humidity of 50% is 1.25 to 1.5 g / cm. 3 The resin impregnated paper according to the above aspect is provided in the range of

[0009] According to yet another aspect of the present invention, there is provided a resin impregnated paper according to any of the above aspects, wherein the cured product of the resin composition contains one or more curable resins.

[0010] According to yet another aspect of the present invention, there is provided the resin-impregnated paper according to the above aspect, wherein the cured product of the resin composition contains an ionizing radiation curable resin as the curable resin.

[0011] According to yet another aspect of the present invention, there is provided a resin-impregnated paper according to the above aspect, wherein the resin composition contains a urethane (meth)acrylate oligomer having a mass average molecular weight of 1,500 or more and having two or more (meth)acryloyl groups, the urethane (meth)acrylate oligomer being one or more selected from a polyester-based urethane (meth)acrylate oligomer, a polyether-based urethane (meth)acrylate oligomer, and a polyol-based urethane (meth)acrylate oligomer.

[0012] According to yet another aspect of the present invention, there is provided a resin-impregnated paper according to the above aspect, wherein the resin composition has a molecular weight of less than 1500 and further contains a urethane (meth)acrylate monomer having two or more (meth)acryloyl groups.

[0013] According to yet another aspect of the present invention, there is provided a resin-impregnated paper according to any of the above aspects, in which the surface of the paper base opposite to the surface having the coating layer is coated with the resin composition.

[0014] According to yet another aspect of the present invention, there is provided a resin-impregnated paper according to any of the above aspects, having a resin coating layer made of a cured product of the resin composition on the side of the paper base opposite to the side having the coating layer.

[0015] According to yet another aspect of the present invention there is provided a resin impregnated paper according to any of the above aspects for use in adhesion.

[0016] According to yet another aspect of the present invention, there is provided a laminate comprising the resin-impregnated paper according to any one of the above aspects and an adhesive layer.

[0017] According to yet another aspect of the present invention, there is provided the laminate according to the above aspect, wherein the adhesive layer is a heat seal layer.

[0018] According to yet another aspect of the present invention, there is provided a laminate according to any of the above aspects, wherein the heat seal layer is a film derived from an aqueous emulsion or a heat seal varnish.

[0019] According to yet another aspect of the present invention there is provided a laminate according to any of the above aspects for use as a packaging material.

[0020] According to yet another aspect of the present invention, there is provided a laminate according to any one of the above aspects for use as a lid material.

[0021] According to yet another aspect of the present invention, there is provided a lid including a laminate according to any of the above aspects.

[0022] According to yet another aspect of the present invention, there is provided a packaging container comprising a container body having an opening, and a lid body attached to the side surface and covering the opening.

[0023] According to yet another aspect of the present invention, there is provided a packaging article comprising the packaging container according to the above aspect and an article contained in the packaging container. Effect of the Invention

[0024] According to the present invention, there are provided a resin-impregnated paper that has high strength in the thickness direction and is less susceptible to deformation such as wrinkles due to dimensional changes when absorbing water, as well as a laminate, a lid, a packaging container, and a packaging article that contain the same. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a partial cross-sectional view showing an example of resin-impregnated paper according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a partial cross-sectional view that shows a schematic diagram of a resin-impregnated paper according to one modified example. [Diagram 3] FIG. 3 is a partial cross-sectional view that illustrates an example of a laminate according to a second embodiment of the present invention. [Figure 4] FIG. 4 is a partial cross-sectional view that illustrates a laminate according to one modified example. [Diagram 5] FIG. 5 is a partial cross-sectional view that illustrates a schematic representation of a laminate according to another modified example. [Figure 6] FIG. 6 is a partial cross-sectional view that illustrates a schematic representation of a laminate according to another modified example. [Figure 7] FIG. 7 is a partial cross-sectional view that illustrates a laminate (for a covering material) according to a second embodiment of the present invention. [Figure 8] FIG. 8 is a partial cross-sectional view that illustrates a laminate (for a covering material) according to one modified example. [Figure 9] FIG. 9 is a partial cross-sectional view that illustrates a laminate (for a covering material) according to another modified example. [Figure 10] FIG. 10 is a cross-sectional view that illustrates a packaging container according to a fourth embodiment of the present invention. [Figure 11] FIG. 11 is an element mapping image of a cross section of the resin-impregnated paper according to Example 4 of the [Examples]. [Figure 12] FIG. 12 is an element mapping image of a cross section of the resin-impregnated paper according to Example 5 of the [Examples]. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are more specific embodiments of any of the above aspects. The following items can be incorporated into each of the above aspects alone or in combination.

[0027] The embodiments described below are merely examples of configurations for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention is not limited by the materials, shapes, structures, etc. of the components described below. Various modifications can be made to the technical idea of ​​the present invention within the technical scope defined by the claims.

[0028] In addition, elements having the same or similar functions are given the same reference numerals in the drawings referred to below, and duplicated explanations are omitted. In addition, the drawings are schematic, and the relationship between dimensions in one direction and dimensions in another direction, the relationship between the dimensions of one member and the dimensions of another member, etc. may differ from the actual ones.

[0029] <1> resin impregnated paper FIG. 1 is a partial cross-sectional view showing an example of a resin-impregnated paper according to the first embodiment of the present invention. The resin-impregnated paper 100A shown in FIG. 1 includes a coated paper 3 having a coating layer 1 on one side of a paper substrate 2, and a cured product 4a of a resin composition. The cured product 4a of the resin composition is a cured product of the resin composition impregnated into the coated paper 3, and is uniformly present throughout the paper substrate 2 in a form that fills the gaps between the fibers 2a that constitute the paper substrate 2. Since the cured product 4a of the resin composition is uniformly present throughout the paper substrate 2 in a form that fills the gaps between the fibers 2a, the resin-impregnated paper 100A has a high peel strength in the thickness direction. For this reason, the resin-impregnated paper 100A can be suitably used for applications requiring strength in the thickness direction, such as packaging materials such as lids, decorative paper, and credit cards.

[0030] The resin impregnated paper 100A has a peel strength in the film thickness direction of 5 N / 15 mm or more. In other embodiments, the resin impregnated paper 100A may have a peel strength in the film thickness direction of 10 N / mm or more. The peel strength in the film thickness direction is a 90° peel force (N / 15 mm) measured under the conditions described below by attaching cellophane tape to the coat layer 1 side of the coated paper 3. The resin impregnated paper 100A having a peel strength of 5 N / 15 mm or more and having a peel strength of 10 N / mm or more in other embodiments is suitable for use in adhesion. When used for adhesion, for example, a heat seal layer is laminated on the resin impregnated paper 100A as an adhesive layer. In this case, when the peel strength in the film thickness direction of the resin impregnated paper 100A is greater than the heat seal strength, the paper is less likely to peel off when the resin impregnated paper 100A is peeled off from the adherend. For example, when the peel strength of the resin-impregnated paper 100A is greater than 5 N / 15 mm, the resin-impregnated paper 100A can suppress the occurrence of paper peeling up to a heat seal strength of at least about 5 N / 15 mm. Here, "paper peeling" refers to the occurrence of cohesive failure within the resin-impregnated paper when the resin-impregnated paper 100A is peeled off from an adherend, with part of the paper remaining on the adherend.

[0031] Furthermore, in the resin-impregnated paper 100A, the presence of the cured resin composition 4a uniformly distributed over the entire paper base material 2 in a form that fills the gaps between the fibers 2a suppresses dimensional changes due to water absorption and drying of the resin-impregnated paper 100A, making it less likely to develop deformations such as wrinkles or curls. For this reason, for example, when the resin-impregnated paper 100A is placed in an environment with large changes in humidity, or when an aqueous composition such as an aqueous emulsion is applied onto the paper base material 2 of the resin-impregnated paper 100A to form a heat seal layer or the like, deformations such as wrinkles due to dimensional changes are less likely to develop.

[0032] The content of the cured product 4a of the resin composition contained in the resin-impregnated paper 100A is preferably 15% by mass or more, more preferably 19% by mass, based on the total mass of the resin-impregnated paper 100A. If the content of the cured product 4a of the resin composition is too low, it becomes difficult for the cured product 4a of the resin composition to uniformly fill the gaps between the fibers 2a of the paper base material 2 throughout the entire paper base material 2. Specifically, the cured product 4a may only coat the surfaces of the fibers 2a and not fill the gaps, or the concentration of the cured product 4a may decrease from the coated surface of the resin composition in the paper base material 2 toward the thickness direction, and the cured product 4a may not sufficiently fill the gaps between the fibers 2a near the coating layer 1. As mentioned later, the surface of the paper base material 2 opposite to the surface having the coating layer 1 is the coated surface of the resin composition.

[0033] The content of the cured resin composition 4a in the resin-impregnated paper 100A is preferably 30 mass % or less relative to the total mass of the resin-impregnated paper 100A. If the content of the cured resin composition 4a is too high, the amount of resin used will simply increase, and no more favorable effects can be expected.

[0034] Resin-impregnated paper 100A has an apparent density of 1.25 cm 3 It is preferable that the thickness is 1.3 cm or more. 3 More preferably, the resin-impregnated paper 100A has an apparent density of 1.5 g / cm3 or more. 3The apparent density is preferably equal to or less than 100 g / cm. The apparent density is determined by storing a sample of the resin-impregnated paper 100A for 24 hours under an environment of 23° C. and 50% relative humidity in order to keep the moisture content constant. 3 ) and the specific measurement conditions will be described later.

[0035] The present inventors have found that the apparent density of the resin-impregnated paper 100A correlates with the content of the cured resin composition 4a. That is, when the content of the cured resin composition 4a of the resin-impregnated paper 100A is 15 mass % or more, the apparent density is approximately 1.25 cm 3 When the content of the cured material 4a is 19 mass% or more, the apparent density is approximately 1.3 cm 3 When the content of the cured material 4a is 30 mass% or less, the apparent density is about 1.5 g / cm 3 The technical significance of the above-mentioned preferred range of the apparent density of the resin-impregnated paper 100A is therefore the same as that of the above-mentioned preferred range of the cured product 4a of the resin composition.

[0036] (Coated paper) The coated paper 3 is a single-sided coated paper having a paper base material 2 and a coating layer 1 on one side of the paper base material 2 .

[0037] (Paper base material) The paper base material 2 may be any material that is permeable to the applied resin composition and is mainly composed of plant-derived pulp. Examples of the paper base material 2 include fine paper, medium-quality paper, construction paper, one-sided glazed paper, bleached and unbleached kraft paper (acid paper or neutral paper), and the like.

[0038] The basis weight of the paper substrate 2, i.e. the mass per area, is, according to one example, between 20 and 500 g / m 2 and in another example, 40 to 100 g / m 2Increasing the basis weight of the paper base material 2 tends to make it harder, while decreasing the basis weight tends to decrease its strength. When the resin-impregnated paper 100A is used as the base material for a lid, for example, a high basis weight of the paper base material 2 may decrease the ease of opening, while a low basis weight may result in insufficient strength for the lid.

[0039] The density and thickness of the paper base material 2 can be appropriately selected depending on the desired quality, ease of handling, etc. The density of the paper base material 2 is, for example, 0.9 to 1.3 g / cm 3 and may be in the range of 1.0 to 1.2 g / cm 3 The thickness of the paper substrate 2 may be, for example, in the range of 40 to 80 μm, or in the range of 45 to 70 μm.

[0040] (Coat layer) The coating layer 1 plays a role of sealing when the resin composition is impregnated into the paper base material 2. That is, the coating layer 1 prevents the resin composition applied from the side opposite to the side having the coating layer 1 of the paper base material 2 from seeping out to the back side of the paper base material 2 when the resin composition is uniformly impregnated into the entire paper base material 2 while filling the gaps between the fibers 2a. This makes it easy for the cured product 4a of the resin composition impregnated into the paper base material 2 to fill the gaps between the fibers 2a throughout the entire paper base material 2. In addition, when the resin composition is applied to the paper base material 2 using an application device using a roll such as a bar coater, the coating layer 1 prevents the resin composition from penetrating the back side and contaminating the roll. In addition, the surface of the coated paper 3 on which the coating layer 1 is provided is smoother than the surface of the paper base material 2 on which the coating layer 1 is not provided. For this reason, the coating layer 1 contributes to improving the coatability of the layer to be applied thereon, such as a heat seal layer or a printing layer.

[0041] The coat layer 1 contains a resin. Examples of the resin contained in the coat layer 1 include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ethylene-α-olefin copolymers polymerized using a metallocene catalyst (single-site catalyst), polypropylene, ethylene-vinyl acetate copolymers, ionomer resins, ethylene-ethyl acrylate copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene-propylene copolymers, methylpentene polymers, acid-modified polyolefin resins obtained by modifying polyolefin resins such as polyethylene and polypropylene with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride, and fumaric acid, polyethylene terephthalate resins, polybutylene terephthalate resins, nylon resins, latex, thermoplastic resins such as polyvinyl alcohol and styrene-butadiene rubber, and natural polymers such as starch. Two or more of these resins may be used in combination, or two or more may be copolymerized for use. The coating layer may further contain additives such as fillers such as silica, layered silicate, clay, kaolin, calcium carbonate, talc, mica, and titanium oxide. The coating layer 1 may be glossified by calendering or the like to improve the surface smoothness.

[0042] The thickness of the coating layer 1 can be appropriately selected depending on the desired quality, ease of handling, etc. The average thickness of the coating layer 1 may be, for example, in the range of 2 to 10 μm. Furthermore, the mass ratio of the coating layer 1 to the coated paper 3 may be, for example, in the range of 8 to 35%.

[0043] (Cured product of resin composition) The cured product 4a of the resin composition contains one or more curable resins. The cured product 4a of the resin composition may contain a thermosetting resin or an ionizing radiation curable resin as the curable resin, or may contain both.

[0044] Thermosetting resins are resins that are hardened by heating, and examples of thermosetting resins include acrylic resins, urethane resins, phenolic resins, urea-melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins.

[0045] An ionizing radiation curable resin is a resin that is cured by ionizing radiation. Here, ionizing radiation means electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules, and typically ultraviolet rays (UV) or electron beams (EB) are used, but other types of radiation such as electromagnetic waves, such as X-rays and γ-rays, and charged particle beams, such as α-rays and ion beams, can also be used.

[0046] When the cured product 4a of the resin composition contains an ionizing radiation curable resin, the resin composition contains a compound having an ionizing radiation curable functional group (hereinafter, also referred to as an "ionizing radiation curable compound"). As the ionizing radiation curable compound, either a monomer or an oligomer can be used. Examples of the ionizing radiation curable functional group include ethylenically unsaturated bond groups such as (meth)acryloyl groups, vinyl groups, and allyl groups, epoxy groups, and oxetanyl groups.

[0047] The ionizing radiation curable compound contained in the resin composition is preferably a compound having an ethylenically unsaturated bond group, more preferably a compound having two or more ethylenically unsaturated bond groups. Among them, a urethane (meth)acrylate compound having two or more (meth)acryloyl groups is preferred, and a urethane (meth)acrylate compound having two or three (meth)acryloyl groups is more preferred. When the urethane (meth)acrylate compound has one (meth)acryloyl group in one molecule, there is a risk of insufficient curing. When the number of (meth)acryloyl groups in one molecule of the urethane (meth)acrylate compound increases, the stress increases and the elongation tends to decrease. The (meth)acryloyl group means an acryloyl group and a methacryloyl group, and the urethane (meth)acrylate means a urethane acrylate and a urethane methacrylate.

[0048] In one embodiment, the resin composition preferably contains a urethane (meth)acrylate oligomer having a mass average molecular weight of 1000 or more and having two or more (meth)acryloyl groups, the urethane (meth)acrylate oligomer being selected from polyester-based urethane (meth)acrylate oligomers, polyether-based urethane (meth)acrylate oligomers, and polyol-based urethane (meth)acrylate oligomers (hereinafter referred to as "urethane (meth)acrylate oligomer A" or "oligomer A"). When the ionizing radiation curable resin contains a structure derived from the urethane (meth)acrylate oligomer A, the extensibility and bending resistance are improved. In this case, for example, cracks and breaks are less likely to occur during cutting processing, and the secondary processability of the resin-impregnated paper 100A is improved.

[0049] The urethane (meth)acrylate oligomer A has a mass average molecular weight of more preferably 1500 to 25000, and further preferably 1500 to 20000. Here, the mass average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0050] Moreover, the urethane (meth)acrylate oligomer A more preferably has two or three (meth)acryloyl groups in one molecule.

[0051] As the urethane (meth)acrylate oligomer A, it is preferable to use a material that gives a photocured product having a maximum stress of 10 MPa or more in the tensile test described below and a tensile elongation represented by the following formula (I) of 30% or more.

[0052] <Tensile test> A coating solution consisting of urethane (meth)acrylate oligomer A and an ultraviolet polymerization initiator (i.e., a coating solution containing urethane (meth)acrylate oligomer A alone as the ionizing radiation curable compound) is used to prepare a photocured film with a thickness of 50 μm. A Shimadzu EZ-LX compact tabletop testing machine is used as the measuring device, and the prepared photocured film is cut into a size of MD×TD: 75×15 mm, pulled in the MD direction at a rate of 5 mm / min, and the maximum stress and tensile elongation (= maximum elongation at break) are measured. The tensile elongation is calculated using formula (I). Tensile elongation (%) = 100 × {(length at break) - (initial length before tensile test)} / initial length before tensile test (I)

[0053] The urethane (meth)acrylate oligomer A can be produced by a known method. For example, a urethane (meth)acrylate obtained by reacting a polyisocyanate such as a diisocyanate with a polyol to form a urethane bond, and then reacting the urethane bond with a hydroxy ester of (meth)acrylic acid or the like can be used.

[0054] As the polyol, for example, polyester polyol, polycarbonate polyol, polyether polyol, etc. can be used.

[0055] As the polyisocyanate, for example, hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate, etc. can be used.

[0056] The urethane (meth)acrylate oligomer A may be a commercially available product, and examples of such products that can be used include UV-2000B, UV-2750B, UV-3000B, UV-3200B, UV-3300B, UV-3310B, UV-3700B, UV-6640B, UV-7000B, UV-3500BA, UV-3210EA, UV-3520EA (all manufactured by Mitsubishi Chemical Corporation), UF-8001G (Kyoeisha Chemical Co., Ltd.), EBECRYL (registered trademark) 4491, and EBECRYL 8411 (all manufactured by Daicel-Allnex Corporation).

[0057] In another embodiment, the resin composition contains a urethane (meth)acrylate monomer having a molecular weight of less than 1500 and having two or more (meth)acryloyl groups (hereinafter referred to as "urethane (meth)acrylate monomer B" or "monomer B"). The ionizing radiation curable resin contains a structure derived from the urethane (meth)acrylate monomer B, thereby improving strength and hardness.

[0058] The urethane (meth)acrylate monomer B more preferably has a mass average molecular weight of 100 or more and less than 1,500, and further preferably has a mass average molecular weight of 300 or more and less than 1,500.

[0059] The urethane (meth)acrylate monomer B more preferably has two (meth)acryloyl groups. The urethane (meth)acrylate monomer B more preferably contains an alicyclic skeleton such as tricyclodecane or trimethylcyclohexyl (IPDI type) or an aromatic ring in the structure.

[0060] The urethane (meth)acrylate monomer B is preferably, for example, a urethane (meth)acrylate monomer that contains any one of the following cyclic structures and has two (meth)acryloyl groups. In the structural formula below, * represents the site of attachment to the remainder of the compound. [ka]

[0061] As the urethane (meth)acrylate monomer B, it is preferable to use a material that, when a photocured film with a thickness of 50 μm is formed using a coating liquid consisting of the urethane (meth)acrylate monomer B (i.e., a coating liquid containing only the urethane (meth)acrylate monomer B as the ionizing radiation curable compound), gives a photocured product with a maximum stress of 20 MPa or more and a tensile elongation of 15% or less in the tensile test described above.

[0062] The urethane (meth)acrylate monomer B may be produced by a known method, or a commercially available product may be used. Examples of commercially available products that can be used include A-DCP, ABE-300, A-BPE300, and A-BPE-10 (all from Shin-Nakamura Chemical Co., Ltd.), BP-4EAL, DCP-A, and DCP-4EL (all from Kyoeisha Chemical Co., Ltd.).

[0063] In another embodiment, the resin composition preferably contains a urethane (meth)acrylate oligomer A and a urethane (meth)acrylate monomer B. By combining these two urethane (meth)acrylate compounds with different mechanical properties, the balance between strength and elongation is improved, and it is possible to obtain a cured resin composition having properties suited to various applications.

[0064] The mass ratio of the urethane (meth)acrylate oligomer A to the urethane (meth)acrylate monomer B (oligomer A:monomer B) contained in the resin composition is preferably within a range of 30%:70% to 100%:0% in one example, and more preferably within a range of 70%:30% to 100%:0% in another example.

[0065] The solvent is not particularly limited as long as it dissolves the ionizing radiation curing compound and the photocuring initiator and has high permeability into paper. For example, ethers such as dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane, 1,3,5-trioxane, tetrahydrofuran, anisole, and phenetole, ketones such as acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and methylcyclohexanone, esters such as ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, n-pentyl acetate, and γ-butyrolactone, cellosolves such as methyl cellosolve, cellosolve, butyl cellosolve, and cellosolve acetate, and dimethyl carbonate can be used. These solvents can be used alone or in combination of two or more.

[0066] The ionizing radiation curable resin composition may contain a monofunctional (meth)acrylic monomer having an amide group (hereinafter referred to as an amide-based (meth)acrylic monomer) as another additive. Examples of the amide-based (meth)acrylic monomer that can be used include (meth)acryloylmorpholine (ACMO), N-(2-hydroxyethyl)(meth)acrylamide (HEAA), diacetone (meth)acrylamide (DAAM), N-isopropyl (meth)acrylamide (NIPAM), and N,N-diethylacrylamide (DEAA). The addition of these compounds generates hydrogen bonds between the fibers 2a constituting the paper base material 2 and the cured product 4a filling the gaps between the fibers 2a, thereby increasing the peel strength. By using an amide-based (meth)acrylic monomer as a diluent instead of a solvent, a low-viscosity non-solvent-based (solvent-free) composition can also be obtained.

[0067] [ka]

[0068] The solids concentration (Nv) and viscosity of the resin composition, as well as the amount applied to the paper substrate 2, are set so that the cured resin composition 4a fills the gaps between the fibers 2a and spreads uniformly over the entire paper substrate 2. When the solids concentration, viscosity, and amount applied are each within an appropriate range, a resin-impregnated paper 100A can be obtained in which the apparent density of the resin-impregnated paper 100A or the content of the cured resin composition 4a falls within the above-mentioned preferred range. In this case, the cured resin composition 4a is uniformly present over the entire paper substrate 2, improving the peel strength of the resin-impregnated paper 100A.

[0069] The solid content (Nv) of the resin composition is preferably in the range of 20 to 40% by mass, more preferably in the range of 25 to 35% by mass. The viscosity of the resin composition is preferably in the range of 3 to 40 mPa·s, more preferably in the range of 3 to 30 mPa·s, measured at room temperature (25°C) and 100 rpm using a B-type viscometer. The amount of the resin composition applied to the paper substrate 2 is preferably 25 to 100 g / cm. 2 It is preferable that the range is 25 to 80 g / cm 2 It is more preferable that the range is within the range.

[0070] The paper base material 2 can be impregnated with the resin composition using, for example, a gravure coater, a doctor blade, a bar coater, a curtain coater, a die slot coater, an impregnation coater, a knife coater, a comma coater, or the like.

[0071] After impregnation with the resin composition, the coated paper 3 can be dried by a known method, such as hot air, infrared rays, a heating cylinder, or a combination of these. The drying temperature may be within the range of, for example, 80°C to 120°C.

[0072] The resin composition impregnated into the paper base material 2 is cured by heating if the curable resin is a thermosetting resin, or by irradiating it with ionizing radiation such as ultraviolet light or an electron beam if the curable resin is an ionizing radiation curable resin.

[0073] <Modification> Resin-impregnated paper can be modified in various ways. Modified examples are described below with reference to Fig. 2. The matters described with reference to Fig. 1 can be applied to the resin-impregnated paper according to the modified examples described here, either alone or in combination.

[0074] FIG. 2 is a partial cross-sectional view showing a schematic diagram of a modified example of the resin-impregnated paper according to the first embodiment of the present invention. The resin-impregnated paper 100B shown in FIG. 2 has a resin coating layer 4 made of a cured product 4a of a resin composition on the surface opposite to the surface of the paper substrate 2 having the coating layer 1. The surface of the paper substrate 2 having the resin coating layer 4 is also the surface coated with the resin composition. The resin-impregnated paper 100B having the resin coating layer 4 can be formed, for example, by adjusting the viscosity of the resin composition to be high. By having the resin-impregnated paper 100B having the resin coating layer 4 made of the cured product 4a of the resin composition, it is possible to use the resin-impregnated paper 100B as a secondary protective layer, and it is also easy to smoothly form functional layers such as a printing layer or a heat seal layer on the resin coating layer 4.

[0075] The thickness of the resin coating layer 4 is preferably in the range of 3 to 30 μm, and more preferably in the range of 5 to 25 μm.

[0076] <2> Laminate Fig. 3 is a partial cross-sectional view showing an example of a laminate according to the second embodiment of the present invention, and shows an example in which the resin-impregnated paper according to the first embodiment of the present invention is used for pasting. The laminate 11A1 shown in Fig. 3 includes the resin-impregnated paper 100A shown in Fig. 1 and an adhesive layer 5, and is pasted together so that the coating layer 1 and the adhesive layer 5 included in the resin-impregnated paper 100A face each other. The matters described with reference to Fig. 1 can be applied to the laminate 11A1 described here, either alone or in combination.

[0077] The adhesive layer 5 is a layer that exhibits adhesiveness when attaching the resin-impregnated paper 100A to an adherend. The adhesive layer 5 is, for example, a heat seal layer that thermally seals the resin-impregnated paper 100A to the adherend.

[0078] When the adhesive layer 5 is a heat seal layer, it may contain, for example, ethylene copolymers such as ethylene-vinyl acetate (EVA), ethylene-aliphatic unsaturated carboxylic acid copolymers, and ethylene-aliphatic unsaturated carboxylic acid ester copolymers, ionomer resins, or other polyolefins. Examples of other polyolefins include linear low density polyethylene (LLDPE), very low density linear polyethylene (VLDPE), and polypropylene.

[0079] From the viewpoint of processability, the heat seal layer preferably contains an ethylene-vinyl acetate copolymer (EVA). The heat seal layer may contain other resins such as polyolefins and other components such as additives, within the range that does not impair the above-mentioned effect of containing the ethylene-vinyl acetate copolymer.

[0080] A sealant layer having an easy peel function (simple peeling function) can also be used as the heat seal layer. Easy peel property indicates excellent re-peelability and easy opening. Means for bonding the heat seal layer by lamination or the like include the dry lamination method using a solvent-based adhesive, the non-solvent lamination method using a solvent-free adhesive, and the sand lamination method using a molten resin as an adhesive. In addition, when the heat seal layer is extruded with molten resin, the extrusion lamination method can also be used.

[0081] The heat seal layer may be provided on the coating layer 1 by, for example, lamination, or may be a coating film obtained by applying a heat seal varnish or an aqueous emulsion onto the coating layer 1 and drying it. For example, the heel sheet layer may be a coating film obtained by applying a heat seal varnish obtained by dissolving an ethylene-vinyl acetate copolymer in a solvent, or an aqueous emulsion of an ethylene-vinyl acetate copolymer onto the coating layer 1 and drying it. A solid plasticizer or a tackifier may be added to the heat seal varnish and the aqueous emulsion.

[0082] The smoothness of the coating layer 1 makes it easier to form a uniform heat seal layer, and improves the adhesiveness of the laminate 11A1 to the adherend.

[0083] The method for applying the heat seal varnish or the aqueous emulsion is not particularly limited, and any commonly used coating device may be appropriately selected and used, such as an air knife coater, a blade coater, a gravure coater, a rod blade coater, a roll coater, a reverse roll coater, a bar coater, a curtain coater, a die slot coater, a champlex coater, a metering blade type size press coater, a short dwell coater, a spray coater, a gate roll coater, or a lip coater.

[0084] The mass per area of ​​the heat seal layer is 0.5 to 60 g / m 2 and preferably in the range of 1 to 30 g / m 2 For example, when the heat seal layer is a sealant layer, the mass per area of ​​the heat seal layer is preferably in the range of 10 to 60 g / m 2 and preferably in the range of 15 to 30 g / m 2 Alternatively, when the heat seal layer is a layer derived from a heat seal varnish or a water-based emulsion, the mass per area of ​​the heat seal layer is preferably in the range of 0.5 to 15 g / m 2 and preferably in the range of 1 to 10 g / m 2It is more preferable that the ratio is in the range of 1.

[0085] In the laminate 11A1, when the peel strength in the thickness direction of the resin-impregnated paper 100A is greater than the heat seal strength, the resin-impregnated paper 100A is less likely to peel off when peeled off from the adherend. For example, when the peel strength of the resin-impregnated paper 100A is greater than 5N / 15mm, the occurrence of peeling off can be suppressed until the heat seal strength is at least about 5N / 15mm. As described above, it is possible to further increase the peel strength in the thickness direction of the resin-impregnated paper 100A by adjusting the type of resin used in the resin composition, or the solid content concentration, viscosity, and application amount of the resin composition applied to the paper base material 2. For this reason, the laminate 11A1 can be suitably used for various applications requiring strength in the thickness direction, such as packaging materials such as lid materials, decorative paper, and credit cards.

[0086] In the laminate 11A1, the resin-impregnated paper 100A has excellent ability to suppress dimensional changes due to water absorption and drying, so that wrinkles due to dimensional changes are unlikely to occur when, for example, a water-based emulsion or the like is applied to the surface of the paper base material 2 opposite to the surface having the coating layer 1.

[0087] <Modification> The laminate can be modified in various ways. Modified examples are described below with reference to Fig. 4 to Fig. 6. The matters described with reference to Fig. 3 can be applied to the laminate according to the modified examples described herein, either alone or in combination.

[0088] Fig. 4 is a partial cross-sectional view showing a laminate according to one modified example. The laminate 11B1 shown in Fig. 4 is the same as the laminate 11A1 shown in Fig. 3 except that the resin-impregnated paper 100A of the laminate 11A1 shown in Fig. 3 is changed to a resin-impregnated paper 100B.

[0089] Fig. 5 is a partial cross-sectional view showing a laminate according to another modified example. The laminate 11A2 shown in Fig. 5 is the same as the laminate 11A1 shown in Fig. 3 except that the arrangement of the adhesive layer 5 is changed from that of the laminate 11A1 shown in Fig. 3.

[0090] In the laminate 11A2, the adhesive layer 5 is attached to the paper base material 2 on the side opposite to the side of the resin-impregnated paper 100A having the coating layer 1. As described above, the resin-impregnated paper 100A has excellent dimensional stability when absorbing water. Therefore, when a water-based emulsion is applied as the adhesive layer 5 to the side opposite to the side of the paper base material 2 having the coating layer 1, deformation such as wrinkles due to dimensional change is unlikely to occur.

[0091] Furthermore, due to the smoothness of the coating layer 1, when another layer is formed on the coating layer 1, the adhesion between the laminate 11A2 and the other layer is improved.

[0092] Fig. 6 is a partial cross-sectional view showing a laminate according to another modified example. The laminate 11B2 shown in Fig. 6 is similar to the laminate 11A2 shown in Fig. 5 except that the resin-impregnated paper 100A of the laminate 11A2 shown in Fig. 5 is changed to a resin-impregnated paper 100B.

[0093] <3> Laminated body for lid material FIG. 7 is a partial cross-sectional view that shows a laminate according to a second embodiment of the present invention. The laminate 12A shown in FIG. 7 is used as a lid in a packaging container (particularly a food packaging container) that has a container body with an opening and a lid that covers the opening. That is, the laminate 12A is a lid material that is used as a lid by itself or a portion cut out from it is used as a lid. The laminate 12A includes the resin-impregnated paper 100 according to the first embodiment of the present invention. The matters described with reference to FIGS. 1 to 6 can be applied to the laminate described here, either alone or in combination.

[0094] The laminate 12A includes a heat seal layer 5A, a resin-impregnated paper 100, a print layer 9, and a functional layer 10 having water resistance (hereinafter, simply referred to as functional layer 10) in this order. Since this laminate 12A does not include a gas barrier layer described later, it is suitable for applications that do not require high gas barrier properties. Each layer included in the laminate 12A will be described below.

[0095] (Resin-impregnated paper 100) The laminate 12A includes the resin-impregnated paper 100 according to the first embodiment of the present invention. In FIG. 7, the coating layer 1, the paper base material 2, and the cured product 4a of the resin composition contained in the resin-impregnated paper 100 are omitted, but the resin-impregnated paper 100 is the same as the resin-impregnated paper 100A and 100B described with reference to FIG. 1 and FIG. 2. In the laminate 12A, a heat seal layer 5A may be formed so as to face the coating layer 1 (not shown) contained in the resin-impregnated paper 100. In this case, the structure represented by the resin-impregnated paper 100 and the heat seal layer 5A is the same as the laminates 11A1 and 11B1 described with reference to FIG. 3 and FIG. 4. In the laminate 12A, a printing layer 9 may be formed on the coating layer 1 (not shown) contained in the resin-impregnated paper 100. In this case, the structure represented by the resin-impregnated paper 100 and the heat seal layer 5A is the same as the laminates 11A2 and 11B2 described with reference to FIG. 5 and FIG. 6.

[0096] The peel strength of the resin-impregnated paper 100 is preferably greater than the heat seal strength between the lid 21 and the container body 22 of the packaging container 20 shown in Fig. 10, which will be described later. In this case, when the lid 21, which is sealed with a predetermined strength in the packaging container 20, is peeled off, the paper is less likely to peel off, and it is possible to prevent the occurrence of a defect in which a part of the laminate 12A remains on the container body 22.

[0097] The heat seal strength is adjusted according to the use and purpose of the packaging container 22. For example, the heat seal strength may be reduced to provide easy opening. Therefore, the peel strength of the resin-impregnated paper 100 may be 5 N / 15 mm or more, and preferably 10 N / 15 mm or more.

[0098] The mass of the paper base material 2 is preferably greater than the mass of any other layer contained in the laminate 12A. The ratio of the mass of the paper base material 2 to the mass of the laminate 12A is preferably 40% or more, more preferably 45% or more, even more preferably 50% or more, even more preferably more than 50%, and particularly preferably 60% or more. In one example, this mass ratio is 80% or less, in another example, 70% or less, and in yet another example, 65% or less.

[0099] When the layers other than the paper base material 2 contained in the laminate 12A are classified into layers made of plastic and other layers, it is preferable that the mass of the paper base material 2 is larger than the total mass of the layers made of plastic and the total mass of the other layers. In this case, in Japan, the laminate 12A can be treated as paper under the Container and Packaging Recycling Law.

[0100] Here, the above classification follows the "Explanatory Materials for the Container and Packaging Recycling Law." In other words, "plastic" is a material that contains a polymer as an essential component and is shaped and manufactured using fluidity during processing. Paints and adhesives are not included in plastics because they are unrelated to the concept of "shaping." Therefore, in the example shown in FIG. 7, the heat seal layer 5A is a "layer made of plastic." Also, in the example shown in FIG. 7, the printing layer 9 formed from ink, the functional layer 10 formed by coating, and the adhesive layer (not shown) made of adhesive are "other layers."

[0101] (Heat seal layer) The heat seal layer 5A enables the lid 21 to be heat sealed to the container body 22 of the packaging container 20 shown in Fig. 10, which will be described later, and has a thermal melt adhesion function for sealing the container. The heat seal layer 5A is the same as that in the case where the adhesive layer 5 is a heat seal layer, as described with reference to Figs. 3 to 6.

[0102] (Printing layer) The printed layer 9 is a layer formed for putting the laminate 12A or the lid body into practical use as a commercial product. The printed layer 9 is a layer formed of ink in which additives such as various pigments, extender pigments, plasticizers, drying agents, and stabilizers are added to ink binder resins that have been used conventionally, such as urethane-based, acrylic-based, nitrocellulose-based, rubber-based, and vinyl chloride-based inks, and displays patterns such as characters and designs. The printed layer 9 can be formed, for example, by well-known printing methods such as offset printing, gravure printing, and silk screen printing, or by well-known coating methods such as roll coating, knife edge coating, and gravure coating.

[0103] The thickness of the printed layer 9 is not particularly limited, and may be, for example, in the range of 0.1 to 5 μm, or in the range of 0.2 to 1 μm.

[0104] (Water-resistant functional layer) The water-resistant functional layer (water-resistant layer) 10 is a layer that, in a packaged article described below, prevents liquid outside the container, such as moisture due to condensation or oil, from penetrating into the lid and prevents the liquid from reaching layers such as the printed layer 9 and the paper base material 2. By preventing liquid outside the container from reaching layers such as the printed layer 9 and the paper base material 2, the functional layer 10 prevents, for example, deterioration, destruction, or deterioration in adhesion of these layers.

[0105] According to one example, the functional layer 10 is formed on the printing layer 9 to control the water absorbency of the partial laminate sheet, which is the portion of the laminate 12A from the functional layer 10 to the paper base material 2. The functional layer 10 controls the water absorbency of the covering laminate by the Cobb method described below to 20 g / m 2 It is preferable that the material has the following water resistance.

[0106] The water absorbency here is the water absorbency obtained in the method specified in JIS P8140:1998 "Paper and paperboard - Water absorbency test method - Cobb method" when the measurement surface is the surface of the functional layer 10 and the contact time between the test piece and water is 300 seconds. This water absorbency is 20 g / m 2It is preferable that the thickness is less than 10 g / m 2 More preferably, it is 5 g / m or less. 2 The lower limit of the water absorbency is ideally 0 g / m 2 According to one example, this water absorption is 1 g / m 2 That's all.

[0107] The functional layer 10 is preferably an overprint varnish layer (hereinafter referred to as "OP varnish layer").

[0108] According to one example, the functional layer 10 contains a water-resistant resin. As the water-resistant resin, any resin capable of realizing the above-mentioned water absorbency can be used without limitation. As the water-resistant resin, for example, polyolefin-based resins such as polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, and vinyl chloride-vinyl acetate copolymers, silicone-based resins, acrylic-based resins, epoxy-based resins, polyester-based resins, cellulose-based resins, or urethane-based resins can be used. The functional layer 10 can be obtained, for example, by applying a paint containing a water-resistant resin to the paper substrate 2 on which the printing layer 9 is formed by a known method. In addition to the water-resistant resin, the paint can further contain additives such as pigments, dyes, hardeners, leveling agents, antiblocking agents, and lubricants, and solvents.

[0109] The functional layer 10 preferably has high abrasion resistance and scratch resistance so as to maintain sufficient water resistance. From this viewpoint, the thickness of the functional layer 10 and the coating amount of the paint that is its material are preferably greater than the thickness of a normal OP varnish layer and the coating amount of a normal OP varnish. Here, the "coating amount" refers to the solid mass per area.

[0110] For example, in the laminate 12A shown in FIG. 7, the coating amount of the coating material for forming the functional layer 10 is 0.2 g / m 2 It is preferable to coat the film so that the coating amount is 2.0 g / m or more. 2It is more preferable to coat the coating material so that the coating amount is, for example, 10 g / m or more. 2 The functional layer 10 is coated so as to have a thickness as described below. The thickness of the functional layer 10 is preferably 0.2 μm or more, and more preferably 2.0 μm or more. The thickness of the functional layer 10 is, for example, 10 μm or less. The functional layer 10 may be provided on the printing layer 9 by lamination.

[0111] (adhesive layer) The laminate 12A may further include one or more adhesive layers. For example, when a film-like heat seal layer 5A is laminated onto the coated paper 3, an adhesive layer may be included between the heat seal layer 5A and the coated paper 3 to bond them together.

[0112] The adhesive layer is made of an adhesive resin or adhesive that can provide the required adhesive strength depending on the material of the layer to be bonded thereto.

[0113] The adhesive resin may be one or more resins selected from polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and copolymers of ethylene and α-olefin polymerized using a metallocene catalyst; ethylene-unsaturated carboxylic acid copolymers such as ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, and ethylene-maleic acid copolymer; and ionomer resins.

[0114] The adhesive is, for example, an adhesive composition obtained by mixing a first composition containing a base agent and a solvent with a second composition containing a curing agent and a solvent. The adhesive layer obtained from this adhesive contains a cured product produced by the reaction of the base agent and the curing agent in the adhesive composition.

[0115] An example of the base agent is polyol. An example of the curing agent is isocyanate compound. An example of the adhesive is an ether-based two-liquid reactive adhesive or an ester-based two-liquid reactive adhesive.

[0116] The cured product of the ether-based two-liquid reactive adhesive is, for example, polyether polyurethane, which is produced by reacting a polyether polyol as a base agent with an isocyanate compound as a curing agent.

[0117] Examples of the cured product of the ester-based two-component reactive adhesive include polyester polyurethane and polyester. The polyester polyurethane is produced by reacting a polyester polyol as a base material with an isocyanate compound as a curing agent.

[0118] In the two-component reactive adhesive, an acrylic polyol may be used as a base agent. The adhesive composition may not contain a solvent as long as it melts or has a low viscosity when heated.

[0119] The laminate 12A has a mass per area of ​​50 to 160 g / m 2 and preferably in the range of 60 to 140 g / m 2 More preferably, the range is 70 to 130 g / m 2 It is more preferable that the value is within the range of 100%. If this value is reduced, the strength of the lid body is reduced. If this value is increased, the lid body becomes hard and the ease of opening is reduced. Furthermore, if this value is increased, not only will the cost increase, but the amount of carbon dioxide emissions associated with production and exhaust will also increase.

[0120] <Modification> The lid laminate can be modified in various ways. For example, as described below, the lid laminate may further include one or more of a support layer, a gas barrier layer, and an anchor coat layer in addition to the laminate 12A shown in FIG. 7. Modifications are described below with reference to FIG. 8 and FIG. 9. The matters described with reference to FIG. 7 can be applied alone or in combination to the lid laminate according to the modification described here.

[0121] FIG. 8 is a partial cross-sectional view that shows a schematic view of a covering material laminate according to one modified example. The laminate 12B shown in FIG. 8 is similar to the laminate 12A described with reference to FIG.

[0122] (Support layer) The support layer 7 improves the strength of the laminate 12B. Examples of the support layer 7 include ethylene-vinyl alcohol copolymer film, nylon film, PET (polyethylene terephthalate) film, PAN (polyacrylonitrile) film, PBT (polybutylene terephthalate) film, PMP (polymethylpentene) and other unstretched or biaxially stretched films, but are not limited thereto and may also be films using polyvinyl alcohol resin, olefin resin, unsaturated polyester resin, etc. The breaking strength can be adjusted by adding additives such as a curing agent or filler, or by a curing treatment using electron beam irradiation, etc.

[0123] The thickness of the support layer 7 is preferably in the range of 3 μm to 50 μm, and more preferably in the range of 10 μm to 30 μm. If the support layer 7 is too thick, the carbon dioxide emissions and costs associated with the manufacture of the support layer 7 and the disposal of the laminate 12B increase. If the support layer 7 is too thin, it is difficult to achieve high breaking strength.

[0124] The position of the support layer 7 is not limited to that shown in FIG. 8, as long as it is included between the coated paper 3 and the heat seal layer 5A.

[0125] (Gas barrier layer) The gas barrier layer 8 has gas barrier properties such as oxygen barrier property and water vapor barrier property. In a packaged article described below, the gas barrier layer 8 prevents gases such as oxygen, water vapor, and aroma components from outside the container from penetrating into the container. As a result, the gas barrier layer 8 prevents food deterioration in the packaged article when the content is, for example, food. Furthermore, when the content is, for example, food, the gas barrier layer 8 prevents odor components and the like of the content from diffusing to the outside of the container. According to one example, the gas barrier layer 8 has an oxygen transmission rate of 0.1 to 100 cc / m in an atmosphere at a temperature of 30° C. and a relative humidity of 70%. 2 / day / atm.

[0126] The gas barrier layer 8 is, for example, a metal layer, an inorganic oxide layer, a resin-containing layer, or a combination of two or more thereof. When microwave heating using a microwave oven is assumed, the gas barrier layer 8 is preferably an inorganic oxide layer, a resin-containing layer, or a combination thereof.

[0127] The gas barrier layer 8 may be formed by coating, by melt molding, or by vapor deposition of an inorganic oxide. Alternatively, the gas barrier layer 8 may be a metal foil such as an aluminum foil, or may be vapor deposited with a metal such as aluminum.

[0128] As the inorganic oxide, for example, silicon oxide, boron oxide, or metal oxides such as aluminum oxide, magnesium oxide, calcium oxide, potassium oxide, tin oxide, sodium oxide, titanium oxide, lead oxide, zirconium oxide, and yttrium oxide can be used.

[0129] The resin-containing layer can be formed, for example, by coating. In this case, a coating liquid containing a resin such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, polyvinylidene chloride, polyacrylonitrile, and epoxy resin can be used. Additives such as organic or inorganic particles, layered compounds, and curing agents may be added to the coating liquid.

[0130] When the resin-containing layer is formed by melt molding, the material may be, for example, the above-mentioned resin or a mixture of the above-mentioned resin and additives. For melt molding, for example, extrusion molding techniques such as T-die and inflation molding can be used.

[0131] The thickness of the gas barrier layer 8 is, for example, in the range of 0.01 to 30 μm, and for another example, in the range of 0.1 to 12 μm.

[0132] The position of the gas barrier layer 8 is not limited to that shown in FIG. 8, as long as it is between the print layer 9 and the heat seal layer 5A.

[0133] This laminate 12B exhibits the same effects as those described above for the laminate 12A. In addition, this laminate 12B has gas barrier properties.

[0134] FIG. 9 is a partial cross-sectional view that shows a schematic view of a covering material laminate according to another modified example. The laminate 12C shown in Fig. 9 is similar to the laminate 12B described with reference to Fig. 8, except that it further includes an anchor coat layer 6. The matters described with reference to Figs. 7 and 8 can be applied alone or in combination to the laminate for covering material according to the modified example described here.

[0135] (Anchor coat layer) The anchor coat layer 6 is interposed between the support layer 7 and the heat seal layer 5A to increase the adhesion between these layers. If the adhesion between the layers is low, delamination between the layers occurs when the package is opened, which makes it easier for fuzzing and stringiness to occur. Therefore, by interposing the anchor coat layer 6 between the support layer 7 and the heat seal layer 5A, the promotion of fuzzing and stringiness caused by delamination between the two layers when the package is opened is suppressed.

[0136] The anchor coating agent used in the anchor coating layer 6 is not particularly limited, and may be, for example, a known agent such as a water-based anchor coating agent or a solvent-based anchor coating agent. An example of the water-based anchor coating agent is polyethyleneimine. An example of the solvent-based anchor coating agent is a two-component curing anchor coating agent in which a base agent and a curing agent react to form a urethane bond, and for example, the base agent is a polyester resin, and the curing agent is polyisocyanate.

[0137] The mass per area of ​​the anchor coat layer 6 is, for example, 0.5 to 6.5 g / m 2 and in another example, 0.5 to 2.0 g / m 2 It is preferable that the ratio is in the range of 1:1.

[0138] The anchor coat layer 6 can be formed by known printing methods such as offset printing, gravure printing, and silk screen printing, or known coating methods such as roll coating, knife edge coating, and gravure coating.

[0139] The anchor coat layer 6 may be disposed between the coated paper 3 and the heat seal layer 5A so as to be adjacent to the heat seal layer 5A. Therefore, the layer adjacent to the surface of the anchor coat layer 6 opposite to the surface adjacent to the heat seal layer 5A is not limited to the support layer 7. For example, in the laminate 12A shown in Fig. 7, the anchor coat layer 6 may be interposed between the coated paper 3 and the heat seal layer 5A.

[0140] (adhesive layer) Laminate 12B and laminate 12C may further include one or more adhesive layers. For example, the laminates 12B and 12C may include an adhesive layer between the coated paper 3 and the gas barrier layer 8 to bond them together.

[0141] <4> Lid The lid according to the third embodiment of the present invention is a lid obtained from the lid material laminate according to the second embodiment or the modified example. An example of the lid according to the third embodiment is the lid 21 described later with reference to Fig. 10. As described in relation to the laminate, the lid according to this embodiment has excellent peel strength and is less likely to be deformed, such as wrinkled, due to dimensional changes when absorbing water.

[0142] <5> packaging container Fig. 10 is a cross-sectional view showing a packaging container (particularly a packaging container for food) according to a fourth embodiment of the present invention. The packaging container 20 shown in Fig. 10 includes a container body 22 having an opening, and a lid body 21 that covers the opening.

[0143] The container body 22 is, for example, a cylindrical shape with a bottom. Here, the container body 22 includes a bottom, a body (or a side wall), and a flange 22a. The flange 22a expands outward at the position of the upper opening of the body.

[0144] The container body 22 includes, for example, an olefin resin such as polypropylene (PP). The container body 22 may further include a component such as ethylene-vinyl alcohol copolymer (EVOH) in order to enhance its gas barrier properties. The container body 22 may further include an additive, for example, an additive for improving processability, designability, and chemical durability.

[0145] The container body 22 may have a single-layer structure or a multi-layer structure. This multi-layer structure may be a two-layer structure or may include three or more layers. In the latter case, the multi-layer structure may be a three-layer structure (PP / PP+EVOH / PP) including a gas barrier layer, for example, a layer containing a component such as the above-mentioned ethylene-vinyl alcohol copolymer, as an intermediate layer.

[0146] The container body 22 may be made of paper. When the contents include a liquid, the container body 22 may have a multi-layer structure including a paper base material and a layer of resin or the like provided on the surface of the container body 22 facing the contents to prevent the liquid from seeping into the paper base material. The container body 22 may be made of paper leaves, paper powder, pulp, or recycled paper. The container body 22 may be formed by folding or pasting a sheet including paper leaves, as in the manufacture of paper cartons, press molding of a sheet using a mold, or other general-purpose techniques such as pulp molding. By using paper for the container body 22, it is possible to reduce the amount of carbon dioxide emissions associated with the manufacture and disposal of the entire packaging container 20, and therefore the burden on the environment is reduced.

[0147] The lid body 21 is any one of the laminates 12A to 12C, or is a cut-out of any one of them. The lid body 21 is heat-sealed to the flange 22a via the heat seal layer 5A after the contents are placed in the container body 22. In this heat sealing, the sealing temperature, sealing pressure, and sealing time can be appropriately set.

[0148] <6> packaging goods The packaging article according to the fifth embodiment of the present invention is obtained by storing an article in the packaging container according to the fourth embodiment described above. The stored article is not particularly limited, but if it is a food, it is preferably a chilled food or a frozen food. Chilled foods and frozen foods are, for example, cooked or processed foods. Chilled foods and frozen foods are, for example, grilled fish, boiled fish, or prepared dishes.

[0149] As described above, in this packaged article, the heat seal strength between the lid 21 and the container body 22 is preferably smaller than the breaking strength of the support layer 2 included in the lid 21. Here, the heat seal strength is a value obtained by the method specified in JIS Z0238:1998 "Test methods for heat-sealed flexible packaging bags and semi-rigid containers."

[0150] In manufacturing this packaged article, before the lid body 21 is heat-sealed to the container body 22, for example, after the contents are placed in the container body 22 and before the lid body 21 is heat-sealed to the container body 22, the gas in the container body 22 may be replaced by a known method. For example, the container body 22 may be filled with an inert gas. When the contents are food, by appropriately changing the gas composition in the container, it is possible to suppress the growth of bacteria and extend the quality retention period, to prevent oxidation and thereby to maintain the flavor, color, etc. of the food for a long time, and to prevent the loss of vitamins. The replacement gas is appropriately selected depending on the type of food that is the contents. As the replacement gas, a mixed gas of oxygen gas, nitrogen gas, and carbon dioxide gas is preferably used.

[0151] The lid included in this package has high peel strength, and is unlikely to cause problems when the lid is broken upon opening, causing fraying or stringiness, and leaving part of the lid material behind in the container. In addition, the lid has excellent ability to suppress dimensional changes when absorbing water, and is therefore unlikely to cause problems due to deformation caused by humidity changes or the application of a water-based emulsion or the like. EXAMPLES

[0152] Tests carried out in relation to the present invention are described below. 1. Testing <Main Ingredients> In the following Examples 1 to 10 and Comparative Examples 1 to 6, the main components used in the preparation of the resin compositions are shown below.

[0153] · Urethane (meth)acrylate oligomer A1: UV-7000B (Mitsubishi Chemical Corporation, functional groups 2-3, Mw3500) · Urethane (meth)acrylate oligomer A2: UV-3520EA (Mitsubishi Chemical Corporation, functional group number 2, Mw 14000) Urethane (meth)acrylate monomer B1: Formula (1)

[0154] [ka]

[0155] The urethane (meth)acrylate monomer B was produced by the following method. In a reaction vessel equipped with a cooling tube, a stirrer, and a thermometer, 31.5 parts by mass of isophorone diisocyanate and 0.1 parts by mass of dibutyltin dilaurate were charged and heated to 50°C. 68.4 parts by mass of ε-caprolactone 1 mol modified 2-hydroxyethyl acrylate (PLACCEL FA1DDM, Daicel Chemical Industries, Ltd.) was added dropwise over 1 hour, and the reaction was carried out by stirring at 90°C for 10 hours. When the amount of residual isocyanate in this reaction liquid was measured using FT-IR, it was found that the urethane reaction had proceeded quantitatively, and the amount of isocyanate had finally become almost zero, and 99.9 parts by mass of urethane (meth)acrylate monomer B represented by the above structural formula was obtained.

[0156] <Example 1> <1> Preparation of Resin Composition 30 parts by mass of the above-mentioned urethane (meth)acrylate oligomer A1 (UV-7000B) and 70 parts by mass of the urethane (meth)acrylate monomer B1 were dissolved in methyl ethyl ketone (MEK) to obtain a resin composition with a total solids concentration (Nv) of 35% by mass. The viscosity of the obtained resin composition (25°C, B-type viscometer, 100 rpm) was 4.6 mPa s.

[0157] <2> Manufacture of resin-impregnated paper The resin-impregnated paper 100A shown in FIG. 1 was produced by the following method. First, as the coated paper 3, Tokukomo S (product name, thickness 49 μm, basis weight 52.3 g / m) manufactured by Fuji Kako Co., Ltd. was used. 2 The coated paper had a basis weight of 37.3 g / m 2 One side of the paper is coated with a 15g / m2 sheet of acrylic resin, the main components of which are polyvinyl alcohol (PVA) and styrene-butadiene rubber (SBR), with silica and layered silicate as additives. 2 The coating layer 1 is formed.

[0158] Coated paper 3 was placed on a coated mount so that the paper substrate 2 was on the upper side, and the resin composition prepared above was applied using a bar coater to the surface of the paper substrate 2 opposite to the surface having the coating layer 1. The amount of resin composition applied (wet mass per area) was 45 g / m 2 It was decided.

[0159] Next, the coated paper 3 impregnated with the resin composition was dried at 100° C. for 1 minute. Thereafter, the paper was irradiated with an electron beam as ionizing radiation at an acceleration voltage of 120 kV and a dose of 36 kGy to cure the resin composition impregnated in the paper substrate 2. In this manner, the resin-impregnated paper 100A shown in FIG. 1 was obtained.

[0160] <Example 2> Resin-impregnated paper 100A was produced in the same manner as in Example 1, except for the following points. In this example, the blending mass ratio (A1 / B1) of urethane (meth)acrylate oligomer A1 and urethane (meth)acrylate monomer B1 was changed from 30 / 70 to 50 / 50 while keeping the total solids concentration (Nv) the same. As a result, the viscosity of the resin composition changed from 4.6 mPa s to 4.5 mPa s.

[0161] <Example 3> Resin-impregnated paper 100A was produced in the same manner as in Example 1, except for the following points. In this example, the blending mass ratio (A1 / B1) of urethane (meth)acrylate oligomer A1 and urethane (meth)acrylate monomer B1 was changed from 30 / 70 to 70 / 30 while keeping the total solids concentration (Nv) the same. As a result, the viscosity of the resin composition changed from 4.6 mPa s to 5.4 mPa s.

[0162] <Example 4> Resin-impregnated paper 100A was produced in the same manner as in Example 1, except for the following points. In this example, the total solids concentration was kept the same, but the urethane (meth)acrylate monomer B1 was not used, and only the urethane (meth)acrylate oligomer A1 was used as the urethane (meth)acrylate compound. As a result, the viscosity of the resin composition changed from 4.6 mPa·s to 5.4 mPa·s.

[0163] <Example 5> The resin-impregnated paper 100B shown in FIG. 2 was produced by the following method. In this example, resin-impregnated paper 100B was produced in the same manner as in Example 1, except for the following points: In this example, the total solids concentration was kept the same, but instead of urethane (meth)acrylate oligomer A1 and urethane (meth)acrylate monomer B1, only urethane (meth)acrylate oligomer A2 was used as the urethane (meth)acrylate compound. As a result, the viscosity of the resin composition changed from 4.6 mPa s to 29.9 mPa s.

[0164] <Example 6> A resin-impregnated paper 100A was produced in the same manner as in Example 4, except for the following points: In this example, the solid content (Nv) was changed from 35% by mass to 30% by mass, and the coating amount was increased to 45 g / m 2 From 72 g / m 2 As a result, the viscosity of the resin composition changed from 5.4 mPa s to 3.9 mPa s.

[0165] <Example 7> A resin-impregnated paper 100A was produced in the same manner as in Example 4, except for the following points: In this example, the solid content (Nv) was changed from 35% by mass to 40% by mass, and the coating amount was increased to 45 g / m 2 From 28 g / m 2 As a result, the viscosity of the resin composition changed from 5.4 mPa s to 8.5 mPa s.

[0166] <Example 8> A resin-impregnated paper 100A was produced in the same manner as in Example 4, except for the following points. That is, in this example, Ryuo Coat (product name, thickness 58 μm, basis weight 65 g / m) manufactured by Daio Paper Corporation was used as the coated paper 3. 2 , with a clay coat layer) was used.

[0167] <Example 9> A resin-impregnated paper 100A was produced in the same manner as in Example 4, except for the following points. In this example, Cormorant (product name, thickness 56 μm, basis weight 60 g / m) manufactured by Fuji Kako Co., Ltd. was used as the coated paper 3. 2 , with a clay coat layer) was used.

[0168] <Example 10> A resin-impregnated paper 100A was produced in the same manner as in Example 4, except for the following points. In this example, Cormorant (product name, thickness 68 μm, basis weight 73.3 g / m) manufactured by Fuji Kako Co., Ltd. was used as the coated paper 3. 2 , with a clay coat layer) was used.

[0169] <Comparative Example 1> In this comparative example, the coated paper 3 was the same as the commercially available coated paper used in Examples 1 to 7 (Tokukomo S manufactured by Fuji Kako Co., Ltd., thickness 49 μm, basis weight 52.3 g / m 2 The substrate (with clay coating layer) was simply prepared, but was not impregnated with the resin composition.

[0170] <Comparative Example 2> Resin-impregnated paper was produced in the same manner as in Example 4, except for the following points: In this comparative example, the solid content (Nv) was changed from 35% by mass to 30% by mass, and the coating amount was increased to 45 g / m 2 From 16 g / m 2 As a result, the viscosity of the resin composition changed from 5.4 mPa s to 3.9 mPa s.

[0171] <Comparative Example 3> Resin-impregnated paper was produced in the same manner as in Example 4, except for the following points: In this comparative example, the solid content (Nv) was changed from 35% by mass to 30% by mass, and the coating amount was increased to 45 g / m 2 From 21 g / m 2 As a result, the viscosity of the resin composition changed from 5.4 mPa s to 3.9 mPa s.

[0172] <Comparative Example 4> In this comparative example, coated paper 3 was the same commercially available coated paper used in Example 8 (Ryuo Coat, manufactured by Daio Paper Corporation, thickness 58 μm, basis weight 65 g / m 2 The substrate (with clay coating layer) was simply prepared, but was not impregnated with the resin composition.

[0173] <Comparative Example 5> In this comparative example, the same commercially available coated paper as that used in Example 9 (Cormant, manufactured by Fuji Kako Co., Ltd., thickness 56 μm, basis weight 60 g / m) was used as the coated paper 3. 2 The substrate (with clay coating layer) was simply prepared, but was not impregnated with the resin composition.

[0174] <Comparative Example 6> In this comparative example, the coated paper 3 was the same as the commercially available coated paper used in Example 10 (Cormant, manufactured by Fuji Kako Co., Ltd., thickness 68 μm, basis weight 73.3 g / m 2 The substrate (with clay coating layer) was simply prepared, but was not impregnated with the resin composition.

[0175] 2. Evaluation <Measurement of apparent density> The apparent density was measured for each of the resin-impregnated papers according to Examples 1 to 10 and Comparative Examples 1 to 6. In order to keep the moisture content of each sample constant, the sample was stored for 24 hours in an environment with a temperature of 23°C and a relative humidity of 50%. After storage, the sample was cut into 20 test pieces measuring 5 cm x 5 cm, and the total mass of the 20 test pieces was measured and the apparent density (g / cm) was calculated according to the following formula: 3 ) was calculated. The thickness is the average value when the thickness of each test piece was measured with a micrometer. The results are shown in Table 1. Apparent density [g / cm 3 ]=total mass[g] / 25[cm 2 ] / Thickness [cm] / 20

[0176] <Measurement of the content of the cured product of the resin composition> The content of the cured resin composition for each of the resin-impregnated papers according to Examples 1 to 10 and Comparative Examples 1 to 6 was calculated using the following formula. Here, the mass of the resin-impregnated paper and the coated paper was measured using test pieces cut to a size of 200 mm x 250 mm. The results are shown in Table 1. Content of cured material (mass%) = [(mass of resin-impregnated paper - mass of coated paper) / mass of resin-impregnated paper] x 100

[0177] <Measurement of peel strength and evaluation of peeling state> (Peel strength measurement) The peel strength of each resin-impregnated paper according to Examples 1 to 10 and Comparative Examples 1 to 6 was measured by a 90° peel test using cellophane tape. Here, a high-speed peel tester (adhesive / film peel analysis device (VPA-2, manufactured by Kyowa Interface Science Co., Ltd.)) was used as the measuring device. Each sample was cut into a test piece of 15 mm x 200 mm in size, and the surface of the paper base material 2 opposite to the surface having the coating layer 1 was attached to an aluminum plate with double-sided tape (manufactured by Teraoka Seisakusho Co., Ltd.) so that the coating layer 1 was on the upper side. A 15 mm wide cellophane tape (manufactured by Nichiban Co., Ltd.) was attached on the coating layer 1 and peeled in the 90° direction at a peel speed of 30,000 mm / min. The average strength during peeling was taken between 20 mm and 200 mm, and this was taken as the peel strength. The results are shown in Table 1.

[0178] (Evaluation of peeling state) The peeling state in the above peeling test was evaluated according to the following criteria. The results are shown in Table 1. A: No paper peeling or fraying (peel occurred at the tape interface). B: Fuzzing (paper fibers have frayed on the surface, but have not caused any damage to the inside) C: Paper peeled off (cohesive failure occurred inside the resin-impregnated paper.)

[0179] (Ability to suppress dimensional changes when absorbing water) The resin-impregnated papers according to Examples 1 to 10 and Comparative Examples 1 to 6 were evaluated for their ability to suppress dimensional change during water absorption. Here, an aqueous emulsion with a solid content concentration of 30% by mass was prepared as the heat seal varnish, which contained ethylene-vinyl acetate copolymer as the main component and water and propanol as the solvent or dispersion medium. This aqueous emulsion was applied to the surface of the paper substrate 2 opposite to the surface having the coating layer 1 in each sample, with a dry mass per area of ​​3 g / m. 2 The coating was dried at 100° C. for 1 minute, and the shape of the coated surface of the paper base material 2 was then examined to evaluate the ability to inhibit dimensional change upon water absorption according to the following criteria. The results are shown in Table 1. A: No wrinkles or other deformations. B: There is slight deformation, but it is at a level that does not cause any problems as a base material. C: Wrinkles, curls, and other deformations are clearly visible.

[0180] (Cross-section of resin-impregnated paper) Fig. 11 is an image for explaining the cross-sectional state of the resin-impregnated paper 100A of Example 4, and shows an elemental mapping image of carbon, oxygen, and silicon by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX). From Fig. 11, it can be seen that the voids between the fibers constituting the paper base material 2 are filled with the cured product of the resin composition uniformly throughout the paper base material 2.

[0181] Fig. 12 is an image for explaining the cross-sectional state of the resin-impregnated paper 100B of Example 5, and shows elemental mapping images of carbon, oxygen, and silicon by SEM-EDX. From Fig. 12, it can be seen that the voids between the fibers constituting the paper base material 2 are filled with the cured product of the resin composition uniformly throughout the paper base material 2. Furthermore, it can be seen that in the resin-impregnated paper 100B, a resin coating layer 4 made of the cured product of the resin composition is formed on the paper base material 2.

[0182] (Set-off of resin composition) In the manufacturing process of the resin-impregnated paper in Examples 1 to 10 and Comparative Examples 2 to 3, each resin composition was coated on coated paper 3, and when it was dried, the presence or absence of bleeding of the resin composition onto the coated paper was confirmed. The results are shown in Table 1.

[0183] [Table 1] [Explanation of symbols]

[0184] Reference Signs List 1...coating layer, 2...paper base material, 2a...fiber, 3...coated paper, 4...resin coating layer, 4a...cured product of resin composition, 5...adhesive layer, 5A...heat seal layer, 6...anchor coat layer, 7...support layer, 8...gas barrier layer, 9...printed layer, 10...functional layer, 11A1...laminate, 11A2...laminate, 11B1...laminate, 11B2...laminate, 12A...laminate, 12B...laminate, 12C...laminate for lid material, 20...packaging container, 21...lid, 22...container body, 22a...flange 100...resin-impregnated paper, 100A...resin-impregnated paper, 100B...resin-impregnated paper

Claims

1. A resin-impregnated paper comprising a coated paper having a coating layer on one side of a paper base material and a cured product of a resin composition impregnated into the paper base material, the cured product of the resin composition filling the voids between the fibers constituting the paper base material, and having a peel strength of 5 N / 15 mm or more.

2. After storage for 24 hours in an environment of 23°C and 50% relative humidity, the apparent density is 1.25 to 1.5 g / cm ３ The resin-impregnated paper according to claim 1, wherein the resin-impregnated paper is in the range of

3. The resin-impregnated paper according to claim 1 , wherein the cured product of the resin composition contains one or more curable resins.

4. 4. The resin-impregnated paper according to claim 3, wherein the cured product of the resin composition contains an ionizing radiation curable resin as the curable resin.

5. The resin-impregnated paper according to claim 4, wherein the resin composition contains one or more urethane (meth)acrylate oligomers selected from polyester-based urethane (meth)acrylate oligomers, polyether-based urethane (meth)acrylate oligomers, and polyol-based urethane (meth)acrylate oligomers, which have a mass average molecular weight of 1,500 or more and have two or more (meth)acryloyl groups.

6. 6. The resin-impregnated paper according to claim 5, wherein the resin composition further contains a urethane (meth)acrylate monomer having a molecular weight of less than 1500 and having two or more (meth)acryloyl groups.

7. 2. The resin-impregnated paper according to claim 1, wherein the surface of the paper base opposite to the surface having the coating layer is coated with the resin composition.

8. The resin-impregnated paper according to claim 1 , further comprising a resin coating layer made of a cured product of the resin composition on the surface of the paper base opposite to the surface having the coating layer.

9. 2. The resin-impregnated paper according to claim 1, which is for application to adhesives.

10. A laminate comprising the resin-impregnated paper according to any one of claims 1 to 9 and an adhesive layer.

11. The laminate according to claim 10, wherein the adhesive layer is a heat seal layer.

12. The laminate according to claim 11, wherein the heat seal layer is a film derived from a water-based emulsion or a heat seal varnish.

13. The laminate according to claim 10, which is used as a packaging material.

14. The laminate according to claim 10, which is used as a lid material.

15. A lid comprising the laminate of claim 14.

16. A packaging container comprising a container body having an opening, and the lid body according to claim 15 that covers the opening.

17. A packaging article comprising the packaging container according to claim 16 and an article contained in the packaging container.

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