Basic calcium-containing laminate

Abstract

To provide a laminate containing a resin material, and exhibiting mildew resistance.SOLUTION: The present invention relates to a laminate comprising a basic calcium-containing layer and a surface layer laminated on at least one main surface of the basic calcium-containing layer, wherein the basic calcium-containing layer contains a thermoplastic resin and basic calcium, the surface layer contains a water-soluble or water-dispersible polymer and a crosslinking agent, and the pH at the surface side of the surface layer is 8.5 or higher. The invention also relates to a laminate in which the basic calcium is calcium hydroxide, calcium oxide, or a mixture of calcium hydroxide and calcium oxide.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminate containing basic calcium. [Background technology]

[0002] Resin products such as resin films and sheets are used in a wide range of applications, such as labels and printing substrates. These resin products are required to have various hygiene-related properties, such as antibacterial and antiviral properties, depending on their applications. For example, resin products for food packaging, such as those disclosed in Patent Documents 1 and 2, are required to have antibacterial properties.

[0003] Patent Document 1 discloses a resin film (sheet) as a food packaging material, which has an antibacterial layer on its surface containing antibacterial powder with a specific average particle size, and which exhibits antibacterial activity. Patent Document 2 also discloses a film (sheet) substrate as an example of an antibacterial preservative material that uses baked shell powder as the antibacterial component. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-30842 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-151616 Summary of the Invention [Problem to be solved by the invention]

[0005] Resin products such as resin films are sometimes required to have not only antibacterial properties but also antifungal properties due to various requirements in the food, medical, and sanitary facilities industries. There is a particular need for materials that exhibit antifungal properties sustainably and safely. For example, conventional resin films have sometimes become less or completely antifungal after prolonged use. In contrast, if the pH is too high in an attempt to enhance antifungal properties, it becomes difficult to maintain safety for the skin.

[0006] In view of the above problems, the present invention provides a laminate containing a resin material, which exhibits antifungal properties. [Means for solving the problem]

[0007] As a result of extensive research aimed at solving the above-mentioned problems, the present inventors have arrived at the present invention having the following gist.

[0008] That is, the present invention is as follows. [1] A calcium-containing composite material comprising: a basic calcium-containing layer; and a surface layer laminated on at least one main surface of the basic calcium-containing layer; the basic calcium-containing layer contains a thermoplastic resin and basic calcium, the surface layer comprises a water-soluble or water-dispersible polymer and a crosslinking agent; The laminate has a pH of 8.5 or higher on the surface layer side of the surface layer. [2] The laminate according to [1], wherein the basic calcium is calcium hydroxide, calcium oxide, or a mixture of calcium hydroxide and calcium oxide. [3] The laminate according to [1] or [2], wherein the water-soluble or water-dispersible polymer is an ethyleneimine-based polymer. [4] The laminate according to any one of [1] to [3], wherein the crosslinking agent is a silane coupling agent. [5] The laminate according to any one of [1] to [4], wherein the content of the basic calcium in the basic calcium-containing layer is 5 to 40 mass %. [6] The surface layer has a basis weight of 3.0 g / m2 The laminate according to any one of [1] to [5] below: [7] The laminate according to any one of [1] to [6], wherein the basic calcium-containing layer contains an inorganic filler. [8] The laminate according to any one of [1] to [7], wherein the basic calcium-containing layer is a stretched layer. [9] The laminate according to any one of [1] to [8], wherein the basic calcium-containing layer has a substrate layer on the main surface opposite to the surface layer.

[10] The laminate according to any one of [1] to [9], wherein the content of the water-soluble or water-dispersible polymer in the surface layer is 50 to 90% by mass. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a laminate containing a resin material that exhibits antifungal properties. [Brief explanation of the drawings]

[0010]

Figure 1

Figure 2

Figure 3

[0011] The present invention will be described in detail below, but the embodiments described below are examples (typical examples) of the present invention and are not limited thereto.

[0012] (Laminate) Conventionally, as in Patent Document 2, laminates containing basic calcium such as calcium hydroxide or calcium oxide have been known as materials exhibiting antibacterial properties. The present inventors have focused on these laminates containing basic calcium as laminates that also have antifungal properties. However, when laminates containing basic calcium are produced, it has been found that it is difficult to produce laminates that exhibit sustained antifungal properties, and in some cases, the laminates lose their antifungal properties after long-term use. Against this background, the present inventors have conducted extensive research into laminates containing basic calcium and have come up with the laminate of the present embodiment having the following configuration. That is, the laminate of this embodiment has a basic calcium-containing layer containing basic calcium, and a surface layer laminated on at least one main surface of the basic calcium-containing layer.

[0013] Conventionally, a basic calcium-containing layer that exhibits antibacterial properties has typically been placed on the outermost surface of a laminate (the side closest to the printed surface during use, etc.) (or the basic calcium has been supported on a substrate so that it is located near the surface). In contrast, the laminate of this embodiment does not have a basic calcium-containing layer, but rather has a surface layer containing a water-soluble or water-dispersible polymer (described below) on the outermost surface. A laminate having such a surface layer is likely to exhibit sustained antifungal properties. The inventors believe that the reason why the laminate of this embodiment exhibits sustained antifungal properties is as follows. It is believed that a laminate having a basic calcium-containing layer exhibits antifungal properties by making the outermost surface of the laminate alkaline (basic) due to the basic calcium. In this regard, when a basic calcium-containing layer is located on the outermost surface of a conventional laminate, the basic calcium can undergo denaturation, such as reacting with external carbon dioxide to become calcium carbonate. The inventors believed that such denaturation would make it difficult to maintain the outermost surface of the laminate alkaline, making it difficult to exhibit antifungal properties. Therefore, the laminate of this embodiment has a specific surface layer located closer to the outermost surface than the basic calcium-containing layer. It is believed that the laminate of this embodiment exhibits sustained antifungal properties because the basic calcium is less likely to denature and the outermost surface of the laminate is more easily maintained alkaline.

[0014] An example of the laminate of this embodiment will be described below with reference to Figures 1 to 3. The laminate 10 has a basic calcium-containing layer 100 containing basic calcium 110, and a surface layer 200 laminated on at least one main surface of the basic calcium-containing layer 100. The laminate 10 may be a laminate of the basic calcium-containing layer 100 and the surface layer 200, and the order of lamination is not important.

[0015] The laminate 10 may have one or more layers other than the basic calcium-containing layer 100 and the surface layer 200. For example, as shown in Fig. 2, the laminate 10 may have a base layer 300 on the main surface opposite to the main surface on which the surface layer 200 of the basic calcium-containing layer 100 is laminated. The laminate 10 may have an intermediate layer between the basic calcium-containing layer 10 and the surface layer 200, as long as the intermediate layer does not impair the mildew resistance. The laminate 10 may have a plurality of basic calcium-containing layers 100 and a plurality of surface layers 200. For example, as shown in Fig. 3, a base layer 300 may have a basic calcium layer 100 on each of its two main surfaces, and a surface layer 200 may be laminated on each of the two basic calcium layers 100 on the main surface opposite to the base layer 300. As shown in FIGS. 1 to 3, in the laminate 10 of this embodiment, the surface layer 200 is preferably disposed on the outermost side (closest to the surface) of the basic calcium layer 100 when the laminate is used for each application.

[0016] <ph> The pH on the surface layer side (side closest to the outermost surface) of the surface layer of the laminate is 8.5 or higher. Many molds are said to be able to survive in environments ranging from strongly acidic to weakly alkaline with a pH of about 2.0 to 8.5, and if the surface layer side of the laminate is within the above pH range, it is likely to exhibit stable mold resistance. From the viewpoint of more easily and stably maintaining the antifungal properties, the pH is preferably 9.0 or more, and particularly preferably 10.0 or more. The upper limit of the pH is not particularly limited, but from the viewpoint of enabling the laminate to be used for various purposes and from the viewpoint of safety to the skin, the pH is preferably 12.0 or less, and particularly preferably 11.0 or less. The above pH values ​​can be measured using a pH pencil (Hydrion / Micro Essential Laboratory Inc.).

[0017] (Surface layer) The surface layer comprises a water-soluble or water-dispersible polymer and a crosslinking agent. The laminate of this embodiment has the surface layer, which allows the pH on the surface layer side to fall within the above range. This effect is believed to be due to the fact that the surface layer inhibits the denaturation of basic calcium, as described above. The surface layer is believed to function as a barrier layer, preventing carbon dioxide and other substances involved in the denaturation of basic calcium from coming into contact with the basic calcium-containing layer from outside the laminate. On the other hand, the surface layer may have other properties in addition to the properties of the barrier layer. For example, the surface layer may also have properties such as an ink-receiving layer for improving printability. Therefore, the surface layer may optionally contain components other than those described above in order to have properties according to the application. The surface layer will be described in detail below.

[0018] <Surface layer basis weight> The surface layer may be a coated layer (a layer formed by a coating method), and is preferably a coated layer formed in the following basis weight range. The basis weight of the surface layer is 0.01 g / m from the viewpoint of easily maintaining safety to the skin (easy to maintain a moderate alkaline range). 2 It is preferable that the content is 0.03 g / m or more. 2 More preferably, it is 0.05 g / m or more. 2 The basis weight of the surface layer is particularly preferably 3.0 g / m or more, from the viewpoint of easily maintaining the outermost surface of the laminate alkaline. 2 It is preferable that the content is 1.0 g / m or less. 2 It is more preferable that it is 0.5 g / m or less. 2 When the basis weight of the surface layer is within the above-mentioned preferred range, the pH of the surface layer on the surface side tends to be easily maintained within the above-mentioned range due to the basic calcium in the basic calcium-containing layer.

[0019] <Water-soluble or water-dispersible polymer> By including a water-soluble or water-dispersible polymer in the surface layer, it is possible to easily keep the pH of the surface layer within the above range and also improve printability, such as adhesion to ink. An aqueous resin emulsion can be used as the water-dispersible polymer. A water-soluble polymer is preferred as the water-soluble or water-dispersible polymer. The water-soluble or water-dispersible polymer may be an ionic polymer to improve adhesion to ink, and in this case, a cationic polymer is preferred. The surface layer may also include a polymer other than the water-soluble or water-dispersible polymer, as long as it does not impair the effect of keeping the pH within the above-mentioned predetermined range.

[0020] Examples of water-soluble or water-dispersible polymers include (meth)acrylic polymers or ethyleneimine polymers having an amino group or an ammonium salt structure, water-soluble or water-dispersible polymers having a phosphonium salt structure, and vinyl polymers obtained by cationizing water-soluble polymers such as polyvinylpyrrolidone and polyvinyl alcohol, and one of these can be used alone or two or more can be used in combination. Among these, ethyleneimine polymers are preferred from the viewpoint that they tend to exhibit stable antifungal properties.

[0021] When a (meth)acrylic polymer or ethyleneimine polymer having an amino group or an ammonium salt structure is used as the water-soluble or water-dispersible polymer, it preferably has a quaternary amino group or a quaternary ammonium salt structure from the viewpoint of ensuring moisture on the surface layer side and easily suppressing mold, and it preferably has a primary to tertiary amino group or a primary to tertiary ammonium salt structure from the viewpoint of safety.Furthermore, from the viewpoint of obtaining a highly crosslinked resin by reaction with a crosslinking agent (silane coupling agent) and obtaining high adhesion between the ink or toner and the resin coating, it is preferable that it has a primary to tertiary amino group or a primary to tertiary ammonium salt structure, more preferably a primary to secondary amino group or a primary to secondary ammonium salt structure, and even more preferably a primary amino group or a primary ammonium salt structure.

[0022] Among these, ethyleneimine-based polymers have high affinity with inks or toners used in various printing methods, particularly with ultraviolet-curable inks used in flexographic printing methods, and are therefore preferred when it is desired to improve printing characteristics, as they improve the adhesion between the surface layer and the ink. Examples of ethyleneimine-based polymers include polyethyleneimine, poly(ethyleneimine-urea), ethyleneimine adducts of polyamine polyamides, alkyl-modified products thereof, cycloalkyl-modified products thereof, benzyl-modified products thereof, hydroxides thereof, etc. Examples of modifiers for obtaining modified products include methyl chloride, benzyl chloride, etc.

[0023] Among these, ethyleneimine-based polymers represented by the following formula (I) are preferred from the viewpoint of transferability and adhesion of ink or toner used in printing, particularly ultraviolet-curable ink. [ka] [In the above formula (I), R 1 and R 2 R each independently represents a hydrogen atom; a linear or branched alkyl group having 1 to 12 carbon atoms; or an alkyl group or aryl group having an alicyclic structure having 6 to 12 carbon atoms. 3 represents a hydrogen atom; an alkyl group or aryl group having 1 to 18 carbon atoms which may contain a hydroxy group; or an alkyl group or aryl group having an alicyclic structure and having 6 to 12 carbon atoms which may contain a hydroxy group. m represents an integer of 2 to 6, and n represents an integer of 20 to 3000.

[0024] As the (meth)acrylic polymer or ethyleneimine polymer having an amino group or an ammonium salt structure, commercially available products can also be used. For example, commercially available ethyleneimine polymers include Epomin (manufactured by Nippon Shokubai Co., Ltd.) and Polymin SK (manufactured by BASF).

[0025] The weight-average molecular weight of the (meth)acrylic polymer or ethyleneimine polymer having an amino group or an ammonium salt structure is preferably 10,000 or more, more preferably 20,000 or more, from the viewpoint of improving adhesion to the substrate and to ink, etc. On the other hand, the weight-average molecular weight is preferably 1,000,000 or less, more preferably 500,000 or less. In the present invention, the weight average molecular weight and number average molecular weight of the resin can be obtained by converting values ​​measured by GPC (Gel Permeation Chromatography) into polystyrene equivalent values.

[0026] The content of the water-soluble or water-dispersible polymer in the surface layer is preferably 50 to 90% by mass, from the viewpoint of easily exhibiting antifungal properties. From the viewpoint of easily maintaining the pH within the above range, the content of the water-soluble or water-dispersible polymer is more preferably 55% by mass or more. From the viewpoint of less inhibiting the antifungal properties due to basic calcium, the content of the water-soluble or water-dispersible polymer is more preferably 80% by mass or less. The content of the water-soluble or water-dispersible polymer can be calculated from the basis weight (solid content) of the surface layer described above.

[0027] <Crosslinking agent> The surface layer contains a crosslinking agent together with the water-soluble or water-dispersible polymer, because a laminate having a surface layer containing a crosslinking agent together with the water-soluble or water-dispersible polymer tends to have a pH on the surface side of the surface layer within the above range. Examples of crosslinking agents include compounds that react with ethyleneimine-based resins to form crosslinks. Furthermore, for ease of process control, the crosslinking agent is preferably water-soluble. To impart flexibility to the surface layer, the crosslinking agent is preferably a bifunctional compound or a polymer-based compound. On the other hand, to impart water-resistant adhesion or abrasion resistance to the surface layer, the crosslinking agent is preferably a trifunctional or higher functional low-molecular substance. A bifunctional compound and a trifunctional or higher functional compound may be used in combination as the crosslinking agent.

[0028] Examples of the crosslinking agent include silane coupling agents and isocyanate resins, etc. Among these, silane coupling agents are particularly preferred from the viewpoint of improving adhesion to the basic calcium-containing layer.

[0029] As the silane coupling agent, a silane coupling agent having a group reactive with a water-soluble or water-dispersible polymer, for example, various functional groups such as a silanol group, can be used. The group reactive with a water-soluble or water-dispersible polymer refers to a group that reacts with an atom or atomic group possessed by the water-soluble or water-dispersible polymer to form a bond. The bond formed by the reaction may be any of a covalent bond, an ionic bond, a hydrogen bond, etc., and is not particularly limited. Specifically, a silane coupling agent can be used that has, in the molecule, an alkoxysilyl group or a silanol group formed by hydrolysis of an alkoxysilyl group, as well as at least one functional group other than a silanol group, such as an epoxy group, a vinyl group, a (meth)acrylic group, an amino group, or an isocyanate group.

[0030] Specific examples of the silane coupling agent include epoxy-based silane coupling agents, (meth)acrylic-based silane coupling agents, amino-based silane coupling agents, and isocyanate-based silane coupling agents.

[0031] Examples of epoxy-based silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc. Among these, 3-glycidoxypropyltrimethoxysilane is preferred from the viewpoint of adhesion to ink or toner.

[0032] Examples of amino-based silane coupling agents include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane.

[0033] An example of the isocyanate-based silane coupling agent is 3-isocyanatepropyltriethoxysilane. These silane coupling agents can be used alone or in combination of two or more.

[0034] (basic calcium-containing layer) The basic calcium-containing layer contains a thermoplastic resin and basic calcium. The basic calcium-containing layer may contain components other than those mentioned above, as long as they do not impair the mildew-proofing properties. The basic calcium-containing layer will be described in detail below.

[0035] <Basic calcium> Basic calcium is a compound that exhibits basicity (alkalinity) of more than pH 8.5 in an aqueous solution, and calcium salts that exhibit alkalinity are preferred. The pH of basic calcium in an aqueous solution is preferably 10.0 or higher, more preferably 12.0 or higher, from the viewpoint of ease of imparting alkalinity, and is preferably 13.0 or lower, more preferably 12.5 or lower, from the viewpoints of ease of handling and safety. The presence of basic calcium makes it easier to maintain the pH of the surface layer of the laminate at 8.5 or higher, making it easier for the laminate to exhibit sustained mildew resistance.

[0036] As the basic calcium, calcium hydroxide, calcium oxide, or a mixture of calcium hydroxide and calcium oxide is preferred from the viewpoint of easy antifungal properties. From the viewpoint of easy availability, calcium oxide or calcium hydroxide is more preferred as the basic calcium, and calcium hydroxide is particularly preferred from the viewpoint of easy raising of the pH. As calcium hydroxide, for example, scallop shells or chicken egg shells that have been calcined at high temperatures and hydrated can be used.

[0037] The content of basic calcium in the basic calcium-containing layer is preferably 5 to 40% by mass from the viewpoint of easily exhibiting antifungal properties. From the viewpoint of easily increasing the pH, the content of basic calcium is more preferably 8% by mass or more, particularly preferably 10% by mass or more. From the viewpoint of handleability, the content of basic calcium is more preferably 20% by mass or less, particularly preferably 15% by mass or less.

[0038] The basic calcium preferably has an average particle size of 0.1 to 10.0 μm, from the viewpoint of easily achieving the preferred layer thickness described below. The average particle size is more preferably 1.0 μm or more, and particularly preferably 2.0 μm or more, from the viewpoint of easily achieving a pH of more than 8.5 in the aqueous solution. The average particle size is more preferably 8.0 μm or less, and particularly preferably 5.0 μm or less, from the viewpoint of easily maintaining smoothness.

[0039] <Thermoplastic resin> The basic calcium-containing layer contains a thermoplastic resin. Examples of the thermoplastic resin include polyolefin resins, polystyrene resins, and acrylic resins, and polyolefin resins are preferred from the viewpoint of formability. As the polyolefin resin, a polypropylene resin is preferred from the viewpoint of moldability. Examples of polypropylene-based resins include isotactic homopolypropylene and syndiotactic homopolypropylene, which are homopolymerized from propylene, as well as polypropylene-based copolymers having various stereoregularities, which are copolymerized mainly with propylene and α-olefins such as ethylene, 1-butene, and 1-pentene. The propylene-based copolymers may be binary or ternary or higher multi-component systems, and may be random or block copolymers. From the viewpoint of moldability, the polyolefin resin is contained in the resin composition forming the basic calcium-containing layer in an amount of preferably 50 to 95% by mass, more preferably 60 to 90% by mass.

[0040] <Inorganic filler> The basic calcium-containing layer may contain an inorganic filler, which can increase the porosity of the basic calcium-containing layer and reduce the resin amount of the laminate. The inorganic filler is not particularly limited as long as it is different from basic calcium. Examples of inorganic fillers include heavy calcium carbonate, light calcium carbonate, calcined clay, talc, diatomaceous earth, titanium oxide, zinc oxide, barium sulfate, silicon oxide, magnesium oxide, and inorganic particles obtained by surface-treating these with a fatty acid, a polymer surfactant, an antistatic agent, etc. Among these, calcium carbonate such as heavy calcium carbonate and light calcium carbonate is preferred from the viewpoints of good pore formability and low cost. The inorganic filler may be selected from the above and used alone, or two or more types may be used in combination.

[0041] The content of the inorganic filler is preferably 5% by mass or more, because this makes it easier to obtain a basic calcium-containing layer with an appropriate porosity. The content of the inorganic filler is preferably 10% by mass or more, and more preferably 15% by mass or more, from the viewpoint of making it easier to increase the porosity. From the viewpoint of maintaining strength and moldability, the content of the inorganic filler is preferably 40% by mass or less, and more preferably 35% by mass or less.

[0042] Average particle diameter of inorganic filler (D 50 The average particle diameter (D ) of the inorganic filler is preferably 0.5 to 10.0 μm. By including an inorganic filler having the above average particle diameter, the porosity of the basic calcium-containing layer is easily increased. 50 ) is preferably 1.0 μm or more from the viewpoint of easily forming voids in the stretched film. 50 ) is preferably 8.0 μm or less, particularly preferably 5.0 μm or less. The particle size and particle size distribution in this embodiment are based on volume and can be measured using a particle measuring device, for example, a laser diffraction particle measuring device "Microtrac" (product name, manufactured by Nikkiso Co., Ltd.).

[0043] <Porosity> The porosity of the basic calcium-containing layer is preferably 10% or more, more preferably 20% or more, from the viewpoint of reducing the amount of resin. The upper limit of the porosity of the stretched film is not particularly limited, but is preferably 60% or less, more preferably 45% or less, from the viewpoint of easily maintaining the strength of the layer. The porosity can be determined from the ratio of the area occupied by pores to a certain region of the cross section of a sample observed under an electron microscope.

[0044] <Stretch layer> The basic calcium-containing layer is preferably a stretched layer from the viewpoint of easily achieving the above-mentioned porosity. Whether a basic calcium-containing layer is a stretched layer can be confirmed, for example, from the storage modulus of the layer. Specifically, the storage modulus of the basic calcium-containing layer is measured in the MD (machine direction) and TD (transverse direction). For example, in the case of a basic calcium-containing layer containing a polypropylene resin, if the storage modulus in the MD (machine direction, the direction in which the resin flows) or TD (transverse direction, the direction perpendicular to the machine direction) exceeds 1500 MPa, the layer can be confirmed to be a stretched layer. (A stretch ratio of 2500 MPa or higher can be confirmed as 4 times or higher, and a stretch ratio of 5000 MPa or higher can be confirmed as 9 times or higher.)

[0045] <Thickness of basic calcium-containing layer> The thickness of the basic calcium-containing layer is preferably 1 μm or more, more preferably 3 μm or more, from the viewpoint of easily adjusting the pH of the surface layer side of the laminate to 8.5 or more, and is preferably 30 μm or less, more preferably 10 μm or less, from the viewpoint of handleability.

[0046] (base material layer) The laminate of this embodiment may further include a substrate layer. The substrate layer can be appropriately selected depending on the application and is not particularly limited.

[0047] The substrate layer preferably contains a polyolefin resin. As the polyolefin resin, a polypropylene resin is preferred from the viewpoint of moldability. Examples of polypropylene-based resins include isotactic homopolypropylene and syndiotactic homopolypropylene, which are homopolymerized from propylene, as well as polypropylene-based copolymers having various stereoregularities, which are copolymerized mainly with propylene and α-olefins such as ethylene, 1-butene, and 1-pentene. The propylene-based copolymers may be binary or ternary or higher multi-component systems, and may be random or block copolymers. From the viewpoint of moldability, the polyolefin resin is contained in the resin composition forming the base layer in an amount of preferably 50 to 95% by mass, more preferably 60 to 90% by mass.

[0048] The base layer preferably contains an inorganic filler, and the type and content of the inorganic filler may be the same as those of the basic calcium-containing layer. The porosity of the substrate layer is also preferably in the same range as the porosity of the basic calcium-containing layer.

[0049] <Base layer thickness> The thickness of the base layer is preferably 300 μm or less, more preferably 150 μm or less, from the viewpoint of improving handleability, and is preferably 20 μm or more, more preferably 40 μm or more, from the viewpoint of easily maintaining the strength of the laminate.

[0050] (Thickness of laminate) From the viewpoint of ease of handling, the total thickness of the laminate is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 150 μm or less. From the viewpoint of easily maintaining the strength of the laminate, the thickness of the laminate is more preferably 30 μm or more, and even more preferably 50 μm or more.

[0051] (Applications of laminates) The laminate of the present embodiment is suitably used in various applications requiring antifungal properties, including food applications, sanitary products, etc. The laminate of the present invention is widely used, for example, as a moisture-proof sheet used on the inside of a wall of a house, various labels for bathtub accessories, and display labels for air conditioners and outdoor units.

[0052] (Method of manufacturing laminate) The method for producing the laminate of this embodiment is not particularly limited, and it can be produced by any method. For example, the laminate of this embodiment is a lamination step of laminating a resin composition for forming a basic calcium-containing layer and a resin composition for forming a surface layer to form a laminate; and a stretching step of stretching the laminate. The method for producing the laminate of this embodiment will be described in detail below.

[0053] <Lamination process> The production method of this embodiment preferably includes a lamination step of laminating a resin composition for forming a surface layer onto a resin composition for forming a basic calcium-containing layer to form a laminate. When the laminate further includes a base layer, the resin composition for forming the basic calcium-containing layer and the surface layer may be laminated onto the base layer to form the laminate. The substrate layer may be uniaxially stretched before laminating the basic calcium-containing layer, or the basic calcium-containing layer may be laminated on an unstretched sheet-like substrate layer. The resin composition forming each layer of the laminate may contain additives such as inorganic fillers, pigments, heat stabilizers (antioxidants), light stabilizers, dispersants, lubricants, or nucleating agents, as needed.

[0054] <Stretching process> The stretching step is a step of stretching the laminate. In the stretching step, the basic calcium-containing layer is preferably stretched to a stretch ratio of 1.2 or more. The stretch ratio may be different for each layer of the laminate. The stretching ratio of the laminate may be determined appropriately. For example, when the laminate is stretched in one direction, the stretching ratio is usually about 1.2 times or more, preferably 2 times or more, and usually 12 times or less, preferably 10 times or less. When the laminate is stretched biaxially, the stretching ratio is usually 1.5 times or more, preferably 8 times or more, more preferably 15 times or more in terms of areal stretching ratio (area stretching ratio). On the other hand, from the viewpoints of strength and manufacturing difficulty, the areal stretching ratio is usually 40 times or less, preferably 20 times or less.

[0055] The stretching method in the stretching step (stretching method) is not particularly limited. Examples include longitudinal stretching using the difference in peripheral speed between rolls, transverse stretching using a tenter oven, sequential biaxial stretching combining these, rolling, simultaneous biaxial stretching using a tenter oven and a pantograph, and simultaneous biaxial stretching using a tenter oven and a linear motor. Also usable is simultaneous biaxial stretching (inflation molding) in which a molten resin is extruded into a tube using a circular die connected to a screw extruder, and then air is blown into the extruded tube.

[0056] The stretching temperature when stretching may be appropriately set. The stretching temperature is preferably set within a range equal to or lower than the melting point of the resin forming the basic calcium-containing layer. Specifically, the stretching temperature is preferably 2 to 60°C lower than the melting point of the resin forming the basic calcium-containing layer. From the viewpoints of easily increasing the porosity of the basic calcium-containing layer and easily preventing breakage, etc., the stretching temperature is more preferably 5 to 50°C lower, and further preferably 10 to 30°C lower, than the melting point of the resin forming the basic calcium-containing layer. The stretching speed is not particularly limited, but is preferably within the range of 20 to 350 m / min from the viewpoint of stable stretching. [Example]

[0057] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts", "%", and the like are based on mass unless otherwise specified.

[0058] (Preparation of Resin Composition) According to the following procedures, resin films (laminates) were produced in Examples 1 to 4 and Comparative Examples 1 to 8. Details of the materials used in each of the Examples and Comparative Examples are summarized in Table 1. The types of materials used in the production of the resin films of each Example and Comparative Example, their blending ratios (mass%), and their evaluations are summarized in Table 2. The material symbols shown in Table 2 correspond to the material symbols shown in Table 1.

[0059] [Table 1]

[0060] [Manufacturing Example 1] A reactor equipped with a reflux condenser, nitrogen inlet tube, stirrer, thermometer, dropping funnel, and heating jacket was charged with 40 parts by mass of isopropanol (Tokuyama Corporation, trade name: Tokuso IPA). While stirring, 12.6 parts by mass of N,N-dimethylaminoethyl methacrylate (Sanyo Chemical Industries, Ltd., trade name: Methacrylate DMA), 12.6 parts by mass of butyl methacrylate (Mitsubishi Rayon Co., Ltd., trade name: Acryester B), and 2.8 parts by mass of higher alcohol methacrylate ester (Mitsubishi Rayon Co., Ltd., trade name: Acryester SL, a mixture of lauryl methacrylate and tridecyl methacrylate) were charged. The system was purged with nitrogen and the internal temperature was raised to 80°C. Then, 0.3 parts by mass of 2,2'-azobisisobutyronitrile (Wako Pure Chemical Industries, Ltd., trade name: V-60 (AIBN)) was added as a polymerization initiator to initiate polymerization. The reaction temperature was maintained at 80°C and polymerization was carried out for 4 hours. The resulting copolymer was neutralized with 4.3 parts by mass of glacial acetic acid (Wako Pure Chemical Industries, Ltd.). While distilling off isopropanol from the reactor, 48.3 parts by mass of ion-exchanged water was added to replace the atmosphere in the system, yielding a viscous aqueous solution (solids concentration, i.e., tertiary amino group-containing methacrylic polymer concentration: 35% by mass) of a tertiary amino group-containing methacrylic polymer (weight average molecular weight: 40,000). The resulting aqueous solution was used in the examples and comparative examples as "water-soluble polymer (A)."

[0061] [Example 1] The resin composition forming the base layer was prepared by melt-kneading 84% by mass of h-PP, a polypropylene resin, and 16% by mass of heavy calcium carbonate particles (CaCO3), an inorganic filler, in an extruder set at 270°C. This resin composition was extruded into a sheet through a die and cooled to 70°C using a cooling roll to obtain a single-layer unstretched film. This unstretched film was reheated to 150°C and then stretched 4.8 times in the sheet flow direction (longitudinal direction) using the speed difference between multiple rolls to obtain a base layer (longitudinal uniaxially stretched layer).

[0062] Next, a resin composition for forming the basic calcium-containing layer was prepared by melt-kneading 90% by mass of h-PP, a polypropylene resin, and 10% by mass of calcium hydroxide (Ca(OH)2), a basic calcium, in an extruder set at 270°C. This resin composition was extruded into a sheet through a die and cooled to 70°C with a cooling roll to obtain a single-layer unstretched film. This unstretched film was laminated on one side of the above-mentioned base layer.

[0063] The obtained laminate was heated to 150°C using an oven, stretched 9 times in the transverse direction using a tenter stretching machine, and then heat-treated at 170°C to obtain a resin film consisting of a basic calcium-containing layer (uniaxially stretched layer) / base layer (biaxially stretched layer).

[0064] Next, as the resin composition for forming the surface layer, a water-soluble polymer, ST-3200, was used. 2 , AC-72 0.02g / m 2 0.01 g / m of the water-soluble polymer (A) obtained in Production Example 1 2 , cross-linking agent KBM-403 0.02g / m 2 , and 0.01 g / m of phosphoric acid as an anti-agglomerating agent 2 The resin composition was diluted with water to a solid content of 1000 ppm or less, and a resin film was prepared. The resin composition was applied to the surface side of the basic calcium-containing layer of the resin film and dried to obtain a resin film consisting of a surface layer (coating layer), a basic calcium-containing layer (uniaxially stretched layer), and a base layer (biaxially stretched layer).

[0065] The thickness of the resin film obtained as described above was 90 μm. Of these, the thickness of the basic calcium-containing layer was 4.5 μm, and the thickness of the base layer was 85.5 μm. The method for measuring the thickness of the resin film and each layer will be described later. The surface layer has a basis weight of 0.06 g / m 2 The content of the water-soluble polymer in the surface layer was 57% by mass.

[0066] [Example 2] In the resin composition forming the surface layer, ST-3200 was used at 0.03 g / m 2 , AC-72 at 0.07 g / m 2 , the water-soluble polymer (A) was 0.03 g / m 2 , KBM-403 at 0.07 g / m 2 A resin film was obtained in the same manner as in Example 1, except that the surface layer had a basis weight as shown in Table 2. [Example 3] As the water-soluble polymer, water-soluble polymer (A) 0.06 g / m 2 , KBM-403 0.03g / m as crosslinking agent 2 A resin film was obtained in the same manner as in Example 1, except that the resin composition for forming the surface layer was prepared using the above and no anti-agglomeration agent was used. The basis weight of the surface layer was as shown in Table 2.

[0067] [Example 4] Water-soluble polymer: AC-72 0.06g / m 2 WS4082 0.03g / m as crosslinker 2 A resin film was obtained in the same manner as in Example 1, except that the resin composition for forming the surface layer was prepared using the above and no anti-agglomeration agent was used. The basis weight of the surface layer was as shown in Table 2.

[0068] [Comparative Example 1] Water-soluble polymer: ST-3200 0.01g / m 2 A resin film was obtained in the same manner as in Example 1, except that a resin composition for forming a surface layer was prepared using the above-mentioned compound without adding a crosslinking agent and that no anti-agglomeration agent was used. The basis weight of the surface layer was as shown in Table 2.

[0069] Comparative Example 2 Water-soluble polymer: ST-3200 0.08g / m 2 A resin film was obtained in the same manner as in Example 1, except that a resin composition for forming a surface layer was prepared using the above-mentioned compound without adding a crosslinking agent and that no anti-agglomeration agent was used. The basis weight of the surface layer was as shown in Table 2.

[0070] Comparative Example 3 Water-soluble polymer: AC-72 0.02g / m 2 A resin film was obtained in the same manner as in Example 1, except that a resin composition for forming a surface layer was prepared using the above-mentioned compound without adding a crosslinking agent and that no anti-agglomeration agent was used. The basis weight of the surface layer was as shown in Table 2.

[0071] Comparative Example 4 Water-soluble polymer: AC-72 0.08g / m 2 A resin film was obtained in the same manner as in Example 1, except that a resin composition for forming a surface layer was prepared using the above-mentioned compound without adding a crosslinking agent and that no anti-agglomeration agent was used. The basis weight of the surface layer was as shown in Table 2.

[0072] Comparative Example 5 Crosslinking agent: KBM-403 0.02g / m 2 A resin film was obtained in the same manner as in Example 1, except that a resin composition for forming a surface layer was prepared using the above-mentioned compound without adding a water-soluble polymer and that no anti-agglomerating agent was used. The basis weight of the surface layer was as shown in Table 2.

[0073] Comparative Example 6 Crosslinking agent: KBM-403 0.08g / m 2 A resin film was obtained in the same manner as in Example 1, except that a resin composition for forming a surface layer was prepared using the above-mentioned compound without adding a water-soluble polymer and that no anti-agglomerating agent was used. The basis weight of the surface layer was as shown in Table 2.

[0074] Comparative Example 7 WS4082 0.08g / m as crosslinking agent 2 A resin film was obtained in the same manner as in Example 1, except that a resin composition for forming a surface layer was prepared using the above-mentioned compound without adding a water-soluble polymer and that no anti-agglomerating agent was used. The basis weight of the surface layer was as shown in Table 2.

[0075] [Comparative Example 8] A resin film having no surface layer and consisting of a basic calcium-containing layer (uniaxially stretched layer) and a substrate layer (biaxially stretched layer) was evaluated. The resin film was produced in the same manner as in Example 1.

[0076] [Various measurements and evaluations] The resin films of Examples 1 to 4 and Comparative Examples 1 to 8 obtained above were evaluated in various ways by the following methods.

[0077] <Thickness (μm)> The thickness (μm) of the basic calcium-containing layer and the resin film was measured in accordance with JIS K7130:1999 using a constant pressure thickness measuring instrument (manufactured by Teclock Corporation, trade name: PG-01J).

[0078] <ph> The pH of the surface of the resin film was measured using a pH pencil (Hydrion / Micro Essential Laboratory Inc.) according to the following procedure. Specifically, a drop of distilled water was placed on the surface of the resin film using a dropper and allowed to stand for 15 seconds. The tip of a pH pencil was then immersed in the water on the surface of the resin film, and a line was drawn by moving the tip of the pencil sideways for approximately 2 cm. The line drawn with the pH pencil immediately developed color, and the color was compared with a color chart to visually determine the pH.

[0079] The evaluation results for the resin films of Examples 1 to 4 and Comparative Examples 1 to 8 are shown in Table 2. [Table 2]

[0080] In the resin films of Examples 1 to 4, in which the surface layer contained a water-soluble or water-dispersible polymer and a crosslinking agent, the pH on the surface layer side of the surface layer was 8.5 or higher. In contrast, the pH of the surface layer on the surface side of the resin films of Comparative Examples 1 to 7, which contained only a water-soluble or water-dispersible polymer or a crosslinking agent as the surface layer, was less than 8.5. Also, the pH of the surface layer on the surface side of the resin film of Example 8, which did not have a surface layer laminated thereon, was less than 8.5.

[0081] <Anti-mold test> For the resin films of Examples 1 and 2, which had a pH of 8.5 or higher in the above evaluations, and the resin film of Comparative Example 8, an antifungal test was carried out on the surface of the surface layer (the surface of the basic calcium-containing layer in Comparative Example 8) by the following method.

[0082] First, two samples were cut out from each of the resin films obtained in each example and comparative example, and one of the samples was subjected to a light resistance test of Category 1 (irradiation intensity 60 W / m) in accordance with the "Durability (Water Resistance and Light Resistance) Test Category (Guideline) for Voluntary Registration" of the Antibacterial Product Technology Council. 2 The sample was then exposed to xenon lamp light for 10 hours at 400 K. A mildew resistance test was conducted on samples that had undergone a light resistance test ("Light resistance 1") and samples that had not ("Water resistance 0"). Anti-mold testing was conducted in accordance with JIS Z 2911:2018 Appendix A (regulations) for testing plastic products using a mixed spore suspension containing spores of the following five types of mold. · Aspergillus niger NBRC 105649 · Penicillium pinophilum NBRC 100533 · Paecilomyces variotii NBRC 107725 · Trichoderma virens NBRC 6355 · Chaetomium globosum NBRC 6347

[0083] The antifungal test was evaluated on the following six-point scale. The results are shown in Table 3. 0 No mold growth was observed by both visual and microscopic observation. 1. No mold growth was observed with the naked eye, but mold growth was clearly confirmed under a microscope. 2 Mold growth was observed with the naked eye, and the area of ​​the growth was less than 25% of the total area of ​​the sample. 3 Mold growth was observed by visual observation, and the area of ​​the grown part was 25% or more but less than 50% of the total area of ​​the sample. 4 The mycelium was well developed, and the area of ​​the developed part was more than 50% of the total area of ​​the sample. 5. The mycelium grew vigorously and covered the entire surface of the sample.

[0084] [Table 3] As a result of the anti-fungal test, the results of the above evaluation for the resin films of Examples 1 and 2 were all "0", even when the anti-fungal test was conducted on samples that had also been subjected to the light resistance test, and no mold growth was observed both visually and under a microscope.< / ph> < / ph>

Claims

1. a basic calcium-containing layer and a surface layer laminated on at least one main surface of the basic calcium-containing layer, the basic calcium-containing layer contains a thermoplastic resin and basic calcium, the surface layer comprises a water-soluble or water-dispersible polymer and a crosslinking agent; The laminate has a pH of 8.5 or higher on the surface layer side of the surface layer.

2. 2. The laminate according to claim 1, wherein the basic calcium is calcium hydroxide, calcium oxide, or a mixture of calcium hydroxide and calcium oxide.

3. 3. The laminate according to claim 1, wherein the water-soluble or water-dispersible polymer is an ethyleneimine-based polymer.

4. 3. The laminate according to claim 1, wherein the crosslinking agent is a silane coupling agent.

5. 3. The laminate according to claim 1, wherein the content of the basic calcium in the basic calcium-containing layer is 5 to 40% by mass.

6. The surface layer has a basis weight of 3.0 g / m ２ The laminate according to claim 1 or 2, wherein:

7. The laminate according to claim 1 or 2, wherein the basic calcium-containing layer contains an inorganic filler.

8. 3. The laminate according to claim 1, wherein the basic calcium-containing layer is a stretched layer.

9. 3. The laminate according to claim 1, further comprising a substrate layer on a main surface of the basic calcium-containing layer opposite to the surface layer.

10. 3. The laminate according to claim 1, wherein the content of the water-soluble or water-dispersible polymer in the surface layer is 50 to 90% by mass.

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