Sheet and method for producing sheet

Abstract

To provide a sheet that enables an increased exposure of calcium hydroxide on the sheet surface, demonstrating superior antibacterial, antiviral, or virus inactivation effects.SOLUTION: The present invention provides a sheet molded from a mixture containing granular calcium hydroxide mixed in resin, where the granular calcium hydroxide has a particle size distribution such that the total amount pass through a 600 μm sieve and at most 5 wt.% of the total amount passes through a 150 μm sieve.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sheet and a method for producing the sheet, in particular to a sheet containing calcium hydroxide and a method for producing the sheet. [Background technology]

[0002] Calcium hydroxide, also known as slaked lime, has been used for various purposes since ancient times. In recent years, resin molded products, such as sheets and films, obtained by molding resin compositions such as polypropylene and polyethylene containing calcium hydroxide are said to have antibacterial and antiviral properties on the surface, and sheets, films, etc. containing calcium hydroxide have been proposed. For example, Patent Document 1 proposes a technology of molding a resin composition in which calcium hydroxide and low-density polyethylene are mixed to form a film imparted with antibacterial properties, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-123071 A Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 describes that the formed film is completely free of lumps due to poor dispersion of calcium hydroxide, is white, and has good gloss and transparency. In order to obtain a sheet having excellent antibacterial, antiviral, or virus inactivation properties, it is preferable to expose more calcium hydroxide on the sheet surface. However, when calcium hydroxide is mixed with a resin and kneaded, it is uniformly dispersed throughout, including inside the resin, and it is difficult to expose it on the sheet surface without causing poor dispersion. Therefore, there is a demand for a sheet that can exhibit excellent antibacterial and virus inactivation effects by exposing more calcium hydroxide mixed with a resin on the sheet surface. [Means for solving the problem]

[0005] According to one embodiment of the present invention, there is provided a sheet formed from a mixture of granular calcium hydroxide and resin, the granular calcium hydroxide having a particle size such that the total amount passes through a 600 μm sieve and the amount passing through a 150 μm sieve is 5% by weight or less of the total amount.

[0006] According to one embodiment of the present invention, there is provided a sheet formed from a mixture of granular calcium hydroxide and resin. The mixture is formed by passing a resin through at least a pair of rolls, crushing a part of the calcium hydroxide with the pair of rolls, and forming the mixture into a sheet shape. The mixture is formed by passing a resin through at least a pair of rolls, and crushing a part of the calcium hydroxide with the pair of rolls.

[0007] According to one embodiment of the present invention, there is provided a method for producing a sheet. The method for producing a sheet includes mixing granular calcium hydroxide with a resin to produce a mixture. The method for producing a sheet includes forming the mixture into a sheet. The granular calcium hydroxide has a particle size such that the entire amount passes through a 600 μm sieve and the amount passing through a 150 μm sieve is 5% by weight or less of the total amount. Effect of the Invention

[0008] According to the above-described sheet and sheet manufacturing method, the particle size of the calcium hydroxide contained is in the range of 150 μm to 600 μm, and 95% or more of the particles are in the range of 150 μm to 600 μm. Since the particle size is larger than that of general calcium hydroxide, it is difficult to achieve uniform dispersion when added to a resin. Therefore, when the resin composition is molded, the calcium hydroxide particles can be unevenly distributed on the front and back surfaces of the resin, and a sheet or film that can effectively exhibit antibacterial or antiviral properties or inactivate viruses can be obtained. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 shows a sheet according to a first embodiment, specifically a sheet 1 containing calcium hydroxide. [Diagram 2] FIG. 2 is a diagram showing a calender molding machine used in the production of the sheet according to the first embodiment. [Diagram 3] 4 is a flowchart relating to a sheet manufacturing method according to the first embodiment. [Figure 4] 5 is a flowchart relating to another method for producing the sheet according to the first embodiment. [Diagram 5] FIG. 11 is a diagram showing a sheet according to a second embodiment. [Figure 6] FIG. 11 is a diagram showing a calender molding machine used in the production of a sheet according to a second embodiment. [Figure 7] FIG. 1 is a diagram showing a test roll used when creating an evaluation sheet. [Figure 8] Microscopic photographs of the surfaces of the sheets of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 [Figure 9] Cross-sectional photographs of the sheets of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 taken with a microscope [Figure 10] 1A is a microscopic photograph of the surface of the colored sheet of Comparative Example 1, and 1B is a microscopic photograph of the surface of the colored sheet of Example 1. [Figure 11]1A is a microscopic photograph of the surface of the colored sheet of Comparative Example 2, and 1B is a microscopic photograph of the surface of the colored sheet of Example 2. [Figure 12] 1A is a microscopic photograph of a cross section of the sheet of Example 3, and FIG. 1B is a microscopic photograph of a cross section of the sheet of Comparative Example 3. [Figure 13] 1A is a microscopic photograph of the surface of another colored sheet of Comparative Example 3, and 1B is a microscopic photograph of the surface of the colored sheet of Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The following description of the embodiments refers to the attached drawings, but the present invention is not limited to the disclosed embodiments. In addition, in the drawings, some parts are omitted in order to easily explain the embodiments. Furthermore, some parts are enlarged or emphasized, and the scale is appropriately changed, and the size and shape may differ from the actual product. In the following figures, the directions in the figures may be explained using an XYZ orthogonal coordinate system. In this XYZ orthogonal coordinate system, a plane parallel to the horizontal plane is the XY plane. One direction parallel to this XY plane is denoted as the X direction, and a direction perpendicular to the X direction is denoted as the Y direction. In addition, a direction perpendicular to the XY plane is denoted as the Z direction (height direction). The X direction, Y direction, and Z direction are explained assuming that the direction indicated by the arrow in the figure is the + direction, and the direction opposite to the direction indicated by the arrow is the - direction.

[0011] In the JIS "Packaging Terminology" standard, "sheet" refers to a thin plastic plate with a thickness of 250 μm or more, and "film" refers to a plastic membrane with a thickness of less than 250 μm. However, in this specification, the term "sheet" is used without making a strict distinction between sheet and film. The hardness of the sheet is not limited to soft, semi-hard, or hard. In addition, in this specification, a mixture or kneaded product of a resin and another substance (e.g., calcium hydroxide, other resins, etc.) may be referred to as a "resin composition."

[0012] As the novel coronavirus disease (COVID-19) has become a social issue, the present inventors conducted a test using feline coronavirus as a substitute for the novel coronavirus and confirmed that the virus was inactivated on the surface of a sheet molded using a resin composition containing calcium hydroxide, and the infectivity (TCID50 / mL) decreased after 5 minutes and then after 10 minutes. Therefore, the inventors have been studying sheets or films obtained by molding such resin compositions.

[0013] [First embodiment] FIG. 1 is a diagram showing a sheet in the first embodiment, specifically a sheet 1 containing calcium hydroxide. In FIG. 1, the sheet 1 contains calcium hydroxide C and a resin R1. The thickness of the sheet 1 is preferably 150 μm to 600 μm. The shape of the calcium hydroxide C is preferably granular. The particle size of the calcium hydroxide C is such that the entire amount passes through a 600 μm sieve and the amount passing through a 150 μm sieve is 5% by weight or less of the total amount. More specifically, when the calcium hydroxide C is sorted by an inspection conforming to the fineness test method of JIS R 9011 using a 600 μm sieve and a 150 μm sieve as specified in JIS Z 8801-1, the entire amount passes through the 600 μm sieve and 5% by weight or less of the total amount passes through the 150 μm sieve.

[0014] More specifically, approximately 50 g of calcium hydroxide sample is accurately weighed to the nearest 0.1 g and placed on a 600 μm standard mesh sieve stacked on top of a 150 μm standard mesh sieve. The sieve frame is lightly tapped 25 times per 10 seconds while moving horizontally, rotating the sieve approximately 1 / 6 of a turn every 25 taps. Any agglomerates of powder are crushed by gently rubbing them against the frame with a finger. In this way, the residue on the sieve is accurately weighed to the nearest 0.1 g, with the limit being the amount passing through the sieve in 1 minute falling to 0.1 g or less. The particle size (weight %) was calculated using the following formula: Particle size (weight%) = mass of residue on sieve after test (g) ÷ mass of sample placed on sieve (g) × 100

[0015] The particle size of calcium hydroxide C in the sheet 1 in this embodiment is mainly in the range of 150 μm to 600 μm, and accounts for 95% or more by weight. This is larger than the particle size of general calcium hydroxide. By using calcium hydroxide of this particle size, it is possible to overcome the problem that calcium hydroxide of a smaller particle size is more uniformly dispersed in the resin during molding and is less likely to be exposed on the sheet surface.

[0016] By making the thickness of the sheet 1 600 μm or less, the thickness of the sheet 1 becomes equal to or smaller than the particle size of calcium hydroxide C. Therefore, by making the thickness of the sheet 1 600 μm or less, the particles of calcium hydroxide C are easily exposed on the surface of the sheet 1. The sheet 1 with the particles of calcium hydroxide C exposed on the surface can effectively obtain antibacterial, antiviral and virus inactivation effects on its surface.

[0017] The calcium hydroxide C is preferably contained in a range of 30% to 80% by weight, more preferably in a range of 40% to 60% by weight, based on the total weight of the mixture of the resin R1 and the calcium hydroxide C. By highly loading the calcium hydroxide C at 30% to 80% by weight based on the total weight of the resin, a larger amount of calcium hydroxide C can be present on the surface of the sheet 1. Therefore, a sheet can be obtained that can effectively exhibit antibacterial or antiviral properties or inactivate viruses.

[0018] When the amount of calcium hydroxide C is 30% by weight or more, antibacterial, antiviral and virus inactivation effects can be exerted on the surface of the sheet 1. When the amount is 80% by weight or less, the mechanical properties such as tensile strength of the molded sheet 1 can be maintained. By setting the content of calcium hydroxide C high at 40% by weight or more and increasing the amount of calcium hydroxide exposed on the resin surface, antibacterial, antiviral and virus inactivation effects can be effectively exerted. On the other hand, the reason why 60% by weight or less is more preferable is that the mechanical properties such as tensile strength can be secured at a higher level for the sheet 1 obtained by molding and processing the resin composition.

[0019] Resin R1 is broadly classified into synthetic resin, natural resin, thermoplastic resin, thermosetting resin, etc., and in recent years, many biodegradable resins have been developed, but is not limited to any of these. A preferable resin R1 is a thermoplastic resin. For example, materials such as polyvinyl chloride (PVC), polypropylene (PP), polyethylene, chlorinated polyethylene, polyvinylidene chloride, ethylene vinyl acetate, and polybutylene succinate are used as the resin R1. Among these, PVC and polypropylene are preferable, and PVC is more preferable. Since PVC is non-crystalline, it has a wide temperature range for molding and is excellent in molding processability. In addition, since PVC is a polar resin, it has excellent compatibility with various additives that also have polarity. That is, various additives can be added to the sheet 1 to give it functionality without deteriorating its mechanical properties. The average polymerization degree of PVC is not particularly limited.

[0020] FIG. 2 is a diagram showing a calendar molding machine 10A used when manufacturing the sheet 1 according to this embodiment. The molding method for making the sheet 1 includes a calendar molding method, a T-die extrusion molding method, an inflation molding method, and the like, but is not limited to a specific method. However, the calendar molding method using a calendar molding machine is a more preferable method. In general, a calendar molding machine is a molding machine in which at least a pair of metal rolls are arranged so that their faces are adjacent to each other, and resin, etc. is molded by passing through the gap between the faces of each metal roll. By adjusting the size of this gap, sheets of various thicknesses can be obtained. In addition, the rotation speeds of each metal roll are generally set to different values, which allows shear force to be applied to the resin composition. The device for manufacturing the sheet 1 is not limited to a calendar molding machine, and may be a T-die extrusion molding machine, an inflation molding machine, or the like.

[0021] The calendar molding method using a calendar molding machine generally tends to obtain a larger discharge amount than the T-die extrusion molding method using a T-die extrusion molding machine or the inflation molding method using an inflation molding machine. Therefore, the calendar molding method using a calendar molding machine is superior in that it can efficiently produce wide sheets. The general configuration of the calendar molding method is provided with a kneader or Banbury mixer, which is a facility for pre-kneading a mixture containing a resin, followed by a calendar molding machine, and further with a cooling facility and a winding facility.

[0022] The sheet 1 of this embodiment uses a mixture of calcium hydroxide C mixed with a resin. This mixture is gelled and pre-kneaded in a Banbury mixer, and then fed into a calendar molding machine 10A. It is then passed along a cooling roll and cooled to a temperature close to room temperature to obtain the sheet.

[0023] The calendar molding machine 10A for manufacturing the sheet 1 in this embodiment includes four rolls, namely, roll 11a, roll 11b, roll 11c, and roll 11d, and a preliminary kneading device 12. The material of the rolls is preferably metal, but is not limited to metal as long as it has a certain strength and heat resistance. The sizes of the rolls 11a, roll 11b, roll 11c, and roll 11d can be appropriately set according to the size of the sheet to be manufactured. The rolls 11a, roll 11b, roll 11c, and roll 11d are rotated at a rotation speed set in the direction of the arrow shown in the figure by a driving device not shown. The rolls 11a and 11b are arranged so that their surfaces are adjacent to each other with a predetermined distance (gap) d1 in the X direction (horizontal direction). The roll distance d1 between the rolls 11a and 11b can be set to any distance depending on the thickness of the sheet 1 to be molded. The rolls 11a and 11b each include a driving device not shown, and the roll distance d1 can be set to any distance.

[0024] The rolls 11b, 11c, and 11d are arranged so that their surfaces are adjacent to each other with a predetermined distance (gap) d2, d3 in the Z direction (height direction). The inter-roll distance d2 between the rolls 11b and 11c, and the inter-roll distance d3 between the rolls 11c and 11d can be set to any distance depending on the thickness of the sheet 1 to be formed. The rolls 11b and 11c each have a driving device (not shown), and the inter-roll distance d2 can be set to any distance. The rolls 11c and 11d each have a driving device (not shown), and the inter-roll distance d3 can be set to any distance. The inter-roll distances d1 to d3 can be appropriately set to obtain a desired thickness of the sheet 1. The calendar forming machine 10A may be composed of four rolls, two rolls, three rolls, or five or more rolls. In addition, FIG. 2 shows an example in which four rolls are arranged in an inverted L shape, but the present invention is not limited to this.

[0025] The roll surface temperatures of the rolls 11a, 11b, 11c, and 11d can be set to a predetermined temperature using a heating device. The molding temperature differs depending on the type of resin R1, and generally, a temperature above the glass transition temperature is suitable for a resin that does not have a melting point, such as PVC, and a temperature above the melting point is suitable for a resin that has a melting point.

[0026] The calendar molding machine 10A can manufacture the sheet 1 by forming the kneaded material 13 kneaded in the preliminary kneading device 12 into a sheet shape. Specifically, the kneaded material 13 is sent to a gap formed between the rolls 11a and 11b with a roll distance d1, and is squeezed by the rolls 11a and 11b to be formed into a sheet-like material having a predetermined thickness. Thereafter, the formed sheet-like material is sent to a gap formed between the rolls 11b and 11c with a roll distance d2. The sheet-like material is squeezed by the rolls 11b and 11c to be further formed into a thinner formed sheet-like material, and is sent to a gap formed between the rolls 11c and 11d with a roll distance d3.

[0027] Here, in this embodiment, the rotation speeds of the roll 11c and the roll 11d are set to be different. Specifically, the rotation speed of the roll 11c is slower than the rotation speed of the roll 11d. As a result, a shear force can be applied to the sheet-like material sent to the gap between the rolls 11c and 11d at a roll-to-roll distance d3. Therefore, the calcium hydroxide C contained in the sheet-like material is crushed by the shear force. As a result, the sheet-like material in which the calcium hydroxide C is exposed on the surface is transported by the roll 11d, and the sheet 1 is manufactured. The sheet 1 is transported by the roll 11d, passed along a cooling roll (a part of a cooling facility not shown), and cooled to a temperature close to room temperature. Then, it is taken up by a winding roller (a part of a winding facility not shown). Even if the rotation speeds of the rolls 11c and 11d are the same, it is possible to crush the calcium hydroxide C by sandwiching it in the gap by adjusting the roll-to-roll distance d3.

[0028] The kneaded material 13 is a mixture of granular calcium hydroxide C and resin R1, which is gelled and pre-kneaded in a pre-kneading device 12. During kneading, the mixture may be heated and melt-kneaded depending on the resin R1 used. The kneaded material 13 is a mixture of calcium hydroxide C and resin R1, and it is preferable that the resin R1 contains an additive. The additive is a substance that is mixed and kneaded with calcium hydroxide and resin R1 when producing the sheet 1, and is an agent that contributes to improving the productivity and quality of the sheet.

[0029] Examples of additives include plasticizers and stabilizers. Although not particularly limited, examples of plasticizers include fatty acid-based plasticizers, phthalic acid-based plasticizers, trimethylolate-based plasticizers, ester-based plasticizers, and epoxy-based plasticizers. Examples of phthalic acid-based plasticizers include bis(2-ethylhexyl)phthalate (common name: dioctyl phthalate) and diisononyl phthalate (common name: diisononyl phthalate) (hereinafter sometimes referred to as "DINP"), and examples of trimethylolate-based plasticizers include tris(2-ethylhexyl) trimellitate (common name: TOTM). Examples of ester-based plasticizers include adipic acid-based polyester plasticizers, and examples of epoxy-based plasticizers include epoxidized soybean oil. Examples of stabilizers include barium zinc-based compounds, hydrotalcite-based compounds, and zeolites. Other additives include antioxidants, lubricants, fillers, processing aids, pigments, weather resistance aids, etc. Known agents can be used for each of these.

[0030] By varying the amount of the plasticizers and the like added, the hardness of the sheet 1, which is the molded product, can be adjusted. By adjusting the amount of additives such as stabilizers, antioxidants, lubricants, fillers, processing aids, pigments, and weather resistance aids, the color can be varied from transparent to dark, and various processing characteristics and physical properties can be imparted. As a result, the sheet 1 is excellent in that it can be provided as a sheet suitable for a variety of situations, from indoor use to outdoor use.

[0031] The amount of plasticizer to be added is not particularly limited, but for example, an amount of 40 parts by weight or more and 80 parts by weight or less per 100 parts by weight of PVC is preferred, and an amount of 50 parts by weight or more is particularly preferred. The fluidity of the resin compound is improved during molding of the sheet 1, so that the bank circulation is improved during molding such as calendar molding. This allows the sheet 1 obtained by molding to have a smoother, higher quality appearance.

[0032] Examples of the preliminary kneading device 12 include a Banbury mixer and a kneader, but there is no particular restriction and a known kneading device can be used. In addition, a mixer such as a tumbler, a mixer (e.g., a Henschel mixer), or a ribbon blender may be provided in front of the preliminary kneading device 12. By providing such a mixer, the calcium hydroxide C having a large particle size used in this embodiment has a low tendency to scatter dust, so that the working environment for workers can be kept good, and there is also the advantage of being excellent in terms of safety and hygiene.

[0033] [Manufacturing method MM1 for sheet 1] A method for manufacturing the sheet 1 according to the first embodiment will be described with reference to Figs. 2 to 4. Fig. 3 is a flow chart for a method MM1 for manufacturing the sheet 1 according to the first embodiment (hereinafter, referred to as "manufacturing method MM1"). First, calcium hydroxide C of a predetermined particle size is mixed with resin R1 to generate a mixture (S1). At this time, additives and the like may be added. The calcium hydroxide C has a particle size in which, when sorted by an inspection conforming to JIS R 9011 fineness test method using 600 μm and 150 μm sieves as specified in JIS Z 8801-1, the entire amount passes through the 600 μm sieve, and 5% by weight or less of the total amount passes through the 150 μm sieve, as specified in JIS Z 8801-1. This is larger than the particle size of general calcium hydroxide. By using calcium hydroxide of this particle size, it is possible to overcome the problem that calcium hydroxide of a smaller particle size is uniformly dispersed in the resin during molding and is difficult to be exposed on the sheet surface.

[0034] Next, the produced mixture is fed into a preliminary kneading device 12 to produce a kneaded material 13 (S2). The kneaded material 13 is then fed into a calendar molding machine 10A (S3). Before feeding the kneaded material 13 into the calendar molding machine 10A, four rolls, 11a, 11b, 11c, and 11d, are heated to a predetermined temperature. The kneaded material 13 is passed between the rolls 11a, 11b, 11c, and 11d to be formed into a sheet containing calcium hydroxide C, and the sheet 1 is produced (S4). Thereafter, the sheet 1 is cooled to a temperature close to room temperature along a cooling roll (not shown) and wound up on a winding roller (S5).

[0035] [Manufacturing method MM2 for sheet 1] FIG. 4 is a flow chart of another method for manufacturing the sheet 1 according to the first embodiment. Regarding the manufacturing method MM2 for the sheet 1 (hereinafter referred to as "manufacturing method MM2"), differences from the manufacturing method MM1 will be described, and similarities will not be described. The manufacturing method MM2 differs from the manufacturing method MM1 in S41. In the manufacturing method MM2, a part of the calcium hydroxide C is crushed and formed into a sheet to manufacture the sheet 1 (S41). In this embodiment, a part of the calcium hydroxide C is crushed in the gap between the roll 11c and the roll 11d at a roll distance d3 in S41. At this time, the rotation speeds of the roll 11c and the roll 11d are different, and the rotation speed of the roll 11c is set slower than the rotation speed of the roll 11d. The difference in the rotation speeds of the roll 11c and the roll 11d generates a shear force, which can crush a part of the calcium hydroxide C. The place where a part of the calcium hydroxide C is crushed is not limited to between the roll 11c and the roll 11d. The crushing may be performed between the rolls 11a and 11b, between the rolls 11b and 11c, or between the rolls 11c and 11d. The calcium hydroxide C may be crushed not only at one location but also at multiple locations. The number of rolls is not particularly limited as long as there is at least one pair of rolls, and the calcium hydroxide C is formed into a sheet shape while being crushed by passing it between the rolls.

[0036] [Second embodiment] FIG. 5 is a diagram showing a laminate sheet 3 according to the second embodiment. In FIG. 5, the laminate sheet 3 is a laminate obtained by laminating a sheet 1 and another sheet 2. That is, the laminate sheet 3 is a laminate sheet in which two layers are integrated by further disposing a sheet 2 on one side of the sheet 1 obtained in the first embodiment, laminating the two sheets, and then heat-welding them. The sheet 2 is attached to the lower surface side of the sheet 1, but it may be attached to the upper surface side. In this embodiment, the sheet 2 does not contain calcium hydroxide C, but sheets 1 containing calcium hydroxide C may be laminated together. In this embodiment, the sheet 2 is two-layered, but this is not limited thereto. It is sufficient that the sheet 1 is disposed on the surface.

[0037] There are no particular restrictions on the method of bonding sheets 1 and 2. Any known machine or method can be used. For example, a thermal welding method using a thermal laminator can be used. Sheet 2 contains resin R2. Resin R2 may be the same as or different from resin R1. Resin R2 may be a single type of resin or a combination of two or more types.

[0038] Resin R2 may be a copolymer. For example, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-(meth)acrylic acid ester copolymer, vinylidene chloride-acrylonitrile copolymer, vinylidene chloride-vinyl acetate copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-vinyl acetate copolymer, etc. In this specification, "(meth)acrylic acid" refers to acrylic acid and / or methacrylic acid, and for example, "(meth)acrylic acid ester" means acrylic acid ester and / or methacrylic acid ester.

[0039] (Seat 2 Production) FIG. 6 is a diagram showing a calendering machine 10B used when manufacturing the sheet 2 of the laminate sheet 3 according to the second embodiment. This calendering machine 10B is a so-called two-roll type having a pair of rolls, a roll 11e and a roll 11f. The rolls 11e and 11f are arranged side by side in the X direction (horizontal direction). The rolls 11e and 11f rotate in opposite directions to each other by a driving device (not shown). The rolls 11e and 11f each have a driving device (not shown) and can set the inter-roll distance d4 to an arbitrary distance. The rolls 11e and 11f can set the roll surface temperature to a predetermined temperature by a heating device (not shown). The size of the rolls 11e and 11f can be appropriately set depending on the size of the sheet to be molded.

[0040] The calendar molding machine 10B can produce the sheet 2 by forming the kneaded material 14, which is fed into the rolls 11e and 11f, into a sheet shape. The kneaded material 14 is produced by the preliminary kneading device 12. The kneaded material 14 is produced by mixing the resin R2 with additives such as a plasticizer and kneading them in the preliminary kneading device 12. The additives used at this time can be appropriately selected and used depending on the required quality of the sheet 2. The additives to be mixed with the resin R1 described above may be appropriately selected and used. When kneading the resin R2 and the additives, the preliminary kneading device 12 may be heated to melt and knead them.

[0041] The calendar molding machine for producing the sheet 2 is not limited to the calendar molding machine 10B. For example, the calendar molding machine 10B may include three rolls or may include four or more rolls. The calendar molding machine 10B may use rolls of any diameter. The calendar molding machine 10B may include a preliminary kneading device 12 for kneading the resin R2. The calendar molding machine 10B may include a pulverizing device for the resin R2. The calendar molding machine 10B may include a cooling device such as a cooling roll for cooling the molded sheet.

[0042] (Production of laminate sheet 3: Lamination of sheet 1 and sheet 2) The laminate sheet 3 can be manufactured by using a known machine such as a thermal laminator and a processing method based on heat welding. Alternatively, the laminate sheet 3 may be manufactured by, for example, laminating the sheet 1 formed into a sheet shape using a calendar molding machine with the sheet 2 formed in advance while still at a high temperature before cooling. The heat welding processing method can be appropriately selected.

[0043] By combining sheet 1 with high-strength sheet 2, laminate sheet 3 can be made into a sheet with excellent properties such as tensile strength even if it contains a high concentration of calcium hydroxide C. Therefore, when antibacterial, antiviral, or virus inactivation effects are required, the surface containing calcium hydroxide C can be placed on the front side, while the surface with high mechanical properties can be placed on the back side, making it suitable for a variety of uses. In addition, even more sheet rolls, such as three or four layers, can be bonded together depending on the purpose.

[0044] For the heat welding process, a temperature equal to or higher than the glass transition temperature is suitable for resins such as PVC that do not generally have a melting point. For resins that have a melting point, a temperature close to or higher than the melting point is suitable. If pressure is applied at the same time, the applied pressure is preferably higher than atmospheric pressure and 30 MPa or less. EXAMPLES

[0045] The present invention will be described in more detail below with reference to specific examples and comparative examples. However, it should be understood that the present invention is not limited to these examples.

[0046] For Example 1, Example 2, Comparative Example 1, and Comparative Example 2, each mixture (resin composition) in the formulation shown in Table 1 was kneaded in a preliminary kneading device at 160°C for 5 minutes to obtain a kneaded product. The kneaded product was then heated to 160°C using a laboratory test roll consisting of a pair of rolls, roll 11g and roll 11h, having a predetermined gap as shown in Figure 7, and molded while crushing the calcium hydroxide to produce an evaluation sheet. The evaluation sheet was obtained by cutting the kneaded product wound around roll 11h in the axial direction (Y direction) of roll 11h with a cutter or the like and taking it out as a sheet. For Example 1, Example 2, Comparative Example 1, and Comparative Example 2, two types of evaluation sheets, 300 μm and 500 μm, were prepared.

[0047] [Table 1]

[0048] [Example 1] The resin used was polyvinyl chloride (PVC) with an average degree of polymerization of 1050 (product name: Kanevinyl S1001, manufactured by Kaneka Corporation), the plasticizer used was diisononyl phthalate (product name: Sanso Cizer DINP, manufactured by New Japan Chemical Industry Co., Ltd.), and the stabilizer was a barium zinc-based stabilizer (product name: MW-614, manufactured by Daikyo Kasei Co., Ltd.). The coarse calcium hydroxide used was Chichibu Sekki Kogyo Co., Ltd. (product name: hydrated lime SA149), and its particle size was inspected according to JIS R 9011, with the entire amount passing through a 600 μm sieve and the weight percentage passing through a 150 μm sieve being 5% or less by weight.

[0049] [Example 2] Example 2 differs from Example 1 in the amount of diisononyl phthalate, barium zinc stabilizer, coarse calcium hydroxide used, and the weight percentage of calcium hydroxide.

[0050] [Comparative Example 1] Comparative Example 1 differs from Example 1 in the type of calcium hydroxide used. In Comparative Example 1, finely powdered calcium hydroxide is used, which is manufactured by Natural Japan Co., Ltd. (product name: Okhotsk Calcium OH-1-004), and its particle size is such that it passes entirely through a 600 μm sieve and entirely through a 150 μm sieve when tested according to JIS R 9011. Therefore, the finely powdered calcium hydroxide of Comparative Example 1 has a smaller particle size than the coarse calcium hydroxide of Example 1, and therefore the proportion of calcium hydroxide crushed by rolls 11g and 11h is smaller than that of the coarse calcium hydroxide.

[0051] [Comparative Example 2] Comparative Example 2 differs from Example 2 in the calcium hydroxide used. The calcium hydroxide used is the same as that used in Comparative Example 1.

[0052] The state of calcium hydroxide in each evaluation sheet of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 was observed and evaluated under a microscope. A photograph of the sheet surface observed under a microscope is shown in Fig. 8, and a photograph of the sheet cross section is shown in Fig. 9. In both Figs. 8 and 9, the magnification during observation was 100 times, and the viewing angle was 1350 µm × 1800 µm. The evaluation was performed by visually checking the area of ​​calcium hydroxide particles exposed on the surface of each evaluation sheet through a microscope. There was no difference in the evaluation between the front and back sides.

[0053] As shown in Figures 8 and 9, coarse calcium hydroxide is observed as white lumps on the surface of the evaluation sheets of Examples 1 and 2, and the area of ​​the calcium hydroxide particles is not uniform depending on the position inside the sheet or on the surface. On the other hand, on the surface of the evaluation sheets of Comparative Examples 1 and 2, fine calcium hydroxide can be seen as white dots, and the particles are dispersed neatly throughout the sheet, and are present on the sheet surface, but are not particularly unevenly distributed. In addition, as shown in Figures 8 and 9, the distribution state of calcium hydroxide particles showed the same tendency in both the 300 μm thick sheet and the 500 μm thick sheet in each Example and Comparative Example.

[0054] In the evaluation sheets of Examples 1 and 2, the coarse calcium hydroxide particles are unevenly distributed in the sheet resin. As a result, it can be seen that the area of ​​the coarse calcium hydroxide particles located and exposed on the front and back surfaces of the sheet is increased compared to the evaluation sheets of Comparative Examples 1 and 2. In the evaluation sheets of Examples 1 and 2, calcium hydroxide is abundantly present on the sheet surface, so that the effects of calcium hydroxide, such as antibacterial properties, antiviral properties, and virus inactivation, can be more efficiently exhibited. This effect is also observed on the back surface of the sheet. In addition, when 0.1 ml of water was dropped on the surface of the evaluation sheets of Examples 1 and 2, the pH of the surface was measured, and the pH value was between 11 and 12. As described above, since the sheet surface exhibits strong alkalinity, it can be seen that a large amount of calcium hydroxide is exposed on the sheet surface.

[0055] FIG. 10(A) is a microscope photograph (50x) of the surface of the colored evaluation sheet (300 μm thick) of Comparative Example 1. FIG. 10(B) is a microscope photograph (50x) of the surface of the colored evaluation sheet (300 μm thick) of Example 1. The white parts are calcium hydroxide, and it can be seen that more calcium hydroxide is exposed on the surface of the evaluation sheet of Example 1, which has a larger particle size, than on the surface of the evaluation sheet of Comparative Example 1. As shown in FIG. 10(B), the surface exposure of the crushed calcium hydroxide is non-uniform, and it may be difficult to identify the amount of exposure per unit area. Therefore, since it may not be possible to identify the sheet, the sheet may be identified by its manufacturing method.

[0056] FIG. 11(A) is a microscope photograph (50x) of the surface of the colored evaluation sheet (300 μm thick) of Comparative Example 2. FIG. 11(B) is a microscope photograph (50x) of the surface of the colored evaluation sheet (300 μm thick) of Example 2. The white parts are calcium hydroxide, and it can be seen that more calcium hydroxide is exposed on the surface of the evaluation sheet of Example 2, which has a larger particle size, than on the surface of the evaluation sheet of Comparative Example 2. As shown in FIG. 11(B), the surface exposure of the crushed calcium hydroxide is non-uniform, and it may be difficult to identify the amount of exposure per unit area. Therefore, since it may not be possible to identify the sheet, the sheet may be identified by its manufacturing method.

[0057] For Example 3 and Comparative Example 3, in the formulations shown in Table 2, evaluation sheets were prepared for each mixture (resin composition) in the same manner as in Example 1.

[0058] [Table 2]

[0059] [Example 3] The resins used were PP (polypropylene) elastomer (product name: Vistamaxx6102, manufactured by ExxonMobil Corporation), methacrylic resin (product name: Parapet SA-C1000P, manufactured by Kuraray Co., Ltd.), antioxidant (manufactured by ADEKA Co., Ltd.), and coarse calcium hydroxide, which were the same as those in Example 1. [Comparative Example 3] The calcium hydroxide used in Comparative Example 3 is different from that used in Example 3. The same calcium hydroxide as in Comparative Example 1 was used in Comparative Example 3. The fine calcium hydroxide in Comparative Example 3 has a smaller particle size than the coarse calcium hydroxide in Example 3, so the proportion of calcium hydroxide crushed by the rolls 11g and 11h is smaller than that of the coarse calcium hydroxide.

[0060] The state of calcium hydroxide was observed and evaluated for each evaluation sheet of Example 3 and Comparative Example 3 under a microscope. A photograph of the cross section of the sheet observed under a microscope is shown in Fig. 12. The magnification of Fig. 12 was 100 times, and the viewing angle was 1350 µm x 1800 µm. Fig. 12(A) is a cross section of the evaluation sheet of Example 3, and Fig. 12(B) is a cross section of the evaluation sheet of Comparative Example 3. The evaluation was performed by visually checking the area of ​​calcium hydroxide particles exposed on the surface of each evaluation sheet through a microscope. There was no difference in the evaluation between the front and back sides.

[0061] As shown in Fig. 12(A), in Example 3, coarse calcium hydroxide was observed as white lumps, and the area of ​​calcium hydroxide particles relative to the area of ​​the evaluation sheet was not uniform in different regions of the sheet, such as the inner part and the surface, while in Comparative Example 3, as shown in Fig. 12(B), the fine calcium hydroxide powder was visible as white dots, and the particles were neatly dispersed throughout the sheet, and were also present on the sheet surface, but were not particularly unevenly distributed.

[0062] FIG. 13(A) is a microscope photograph (50x) of the surface of the colored evaluation sheet (300 μm thick) of Comparative Example 3. FIG. 13(B) is a microscope photograph (50x) of the surface of the colored evaluation sheet (300 μm thick) of Example 3. The white parts are calcium hydroxide, and it can be seen that more calcium hydroxide is exposed on the surface of the evaluation sheet of Example 3, which has a larger particle size, than on the surface of the evaluation sheet of Comparative Example 3. As shown in FIG. 13(B), the surface exposure of the crushed calcium hydroxide is non-uniform, and it may be difficult to identify the amount of exposure per unit area. Therefore, since it may not be possible to identify the sheet, the sheet may be identified by its manufacturing method.

[0063] [Example 4 (Laminate Sheet)] In Example 4, each mixture (resin composition) was kneaded in a preliminary kneading device according to the composition shown in Table 3 to obtain a kneaded mixture. Each kneaded mixture was fed to a calendar molding machine to obtain roll-shaped original sheets of a calcium hydroxide-containing sheet (sheet A) and a calcium hydroxide-free sheet (sheet B). Then, sheet B was attached to one side of sheet A, i.e., the two were laminated to obtain a laminate sheet. The details are explained below.

[0064] [Table 3]

[0065] (Production of Seat A) To 100 parts by weight of PVC with an average degree of polymerization of 1050 (trade name: Kanevinyl S1001, manufactured by Kaneka Corporation), 60 parts by weight of a plasticizer diisononyl phthalate (trade name: Sanso Cizer DINP, manufactured by New Japan Chemical Co., Ltd.), 4.3 parts by weight of a barium zinc-based stabilizer (trade name: MW-614, manufactured by Daikyo Kasei Co., Ltd.), 5.4 parts by weight of an antioxidant (trade name: Adeka STAB 1500, manufactured by Adeka Corporation), 0.3 part by weight of a titanium pigment, 0.5 part by weight of a bluing agent, and 110 parts by weight of coarse calcium hydroxide (trade name: SA149, manufactured by Chichibu Sekiryo Kogyo Co., Ltd.) were added to a Henschel mixer.

[0066] The material was transported from the Henschel mixer to the Banbury mixer, and the kneaded compound was fed to the relay roll. After that, it was fed from the relay roll to a preheated calendar molding machine (temperature: 160 to 170°C) and sheeting (sheet formation) was performed. After forming into a sheet shape in the calendar molding machine, it was transported to a cooling roll and further to a winding machine to obtain a roll of the original sheet A.

[0067] (Manufacture of Seat B) 50 parts by weight of plasticizer diisononyl phthalate (product name: Sanso Cizer DINP, manufactured by New Japan Chemical Industry Co., Ltd.) and 1.5 parts by weight of barium zinc stabilizer (product name: MW-614, manufactured by Daikyo Kasei Co., Ltd.) were added to 100 parts by weight of PVC (product name: Kanevinyl S1001, manufactured by Kaneka Corporation) and mixed in a Henschel mixer. After that, a roll of the original sheet B was obtained using the same procedure as in the manufacture of sheet A described above. Sheet B is a base sheet, and since it does not contain a filler, it has excellent flexibility and tensile strength.

[0068] (Manufacture of laminated sheets) The original rolls of Sheet A and Sheet B were set in a thermal laminator and laminated while being continuously unwound. After lamination, the sheets were softened on a heated drum preheated to about 140 to 150°C, and then sandwiched between a pair of rolls and fused together by applying a pressure of about 3 to 5 MPa to obtain a single laminate sheet.

[0069] The laminate sheet is composed of a soft polyvinyl chloride (PVC) sheet (Sheet A) in one layer, with calcium hydroxide mainly exposed on the surface. The surface of this sheet exhibits antibacterial, antiviral, and virus inactivation properties. The other layer is a soft polyvinyl chloride (PVC) sheet (Sheet B) that does not contain fillers, is highly flexible, and has high tensile strength properties, so the flexibility and tensile strength of the entire sheet can be ensured.

[0070] The calcium hydroxide-containing sheet or laminate sheet obtained by the above-mentioned method has a large amount of calcium hydroxide arranged on its surface, so when 0.1 ml of water is dropped onto the sheet surface, the pH of the water becomes 11 or higher, and the virus can be inactivated.

[0071] The calcium hydroxide-containing sheet or laminate sheet obtained by the above-mentioned method can be used, for example, as a curtain to change the pH and inactivate the virus when droplets from a virus-infected person adhere to the curtain. In addition, when used as a tablecloth, the virus can be inactivated by wiping with water. Furthermore, it can be used for various purposes such as tents and mats for poultry farms.

[0072] The calcium hydroxide-containing sheet or laminate sheet obtained by the above-mentioned method has a thickness of 150 μm to 600 μm, so the thickness of the sheet and the particle size of calcium hydroxide are similar. Therefore, the calcium hydroxide particles are easily exposed on the sheet surface, and the effect of pH change and virus inactivation due to adhesion of moisture can be obtained more effectively. In addition, antibacterial and antiviral effects can be obtained.

[0073] The laminate sheet obtained by the above-mentioned method is produced by laminating another sheet on one side of the sheet and heat welding it. Therefore, for example, by bonding a high-strength base sheet with a small amount of filler to one side of a sheet highly filled with calcium hydroxide by heat welding, a sheet having high mechanical strength while obtaining antibacterial, antiviral and virus inactivation effects on the surface can be provided. When rigidity is required, a sheet having sufficient rigidity can be used as the base sheet, and a sheet suitable for various uses can be provided.

[0074] The calcium hydroxide-containing sheet or laminate sheet obtained by the above-mentioned method is molded by a calendar molding machine, and therefore has a large discharge amount compared to T-die extrusion molding, inflation molding, etc., and therefore has a cost advantage. In addition, it can be produced in various widths within the range of the face length of the calendar molding machine, and can be produced in various thicknesses by adjusting the gap of the calendar molding machine, so that it is excellent in mass production of a wide variety of products. In addition, the roll gap in the calendar molding machine is generally adjusted slightly narrower than the target sheet thickness in consideration of the die swell of the material. In this case, calcium hydroxide with a particle size close to the thickness of the sheet is actually formed into a sheet by passing through a gap narrower than the sheet thickness, so that some calcium hydroxide is crushed by the shear generated in the resin composition between the calendar rolls and formed into a sheet. As a result, the active surface whose surface is not naturally stabilized by moisture in the air is exposed, and a higher virus inactivation effect is obtained.

[0075] The above embodiments and examples are provided for the purpose of explanation, but the technical scope of the present invention is not limited to the above embodiments and examples. One or more of the requirements described in the above embodiments may be omitted. The requirements described in the above embodiments may be combined as appropriate. It is clear to those skilled in the art that various modifications or improvements can be made to the above embodiments. For example, PVC was used for the resin in the examples, but the same effect can be obtained even if it is changed to a known thermoplastic resin. In addition, such modifications or improvements are also included in the technical scope of the present invention. In addition, the execution order of the processes shown in the claims, specification, and drawings can be realized in any order, as long as the result of the previous process is not used in the subsequent process. Even if the operation flow in the claims, specification, and drawings is explained using "first", "continue", etc. for convenience, it does not mean that it is essential to carry out the processes in this order. [Explanation of symbols]

[0076] 1. Calcium hydroxide-containing sheet 2... sheets 3. Laminated sheet 10A, 10B...Calendar molding machine 11a, 11b, 11c, 11d, 11e, 11f, 11g, 11h...Roll 12 Pre-mixing device 13, 14...Kneaded material C: Calcium hydroxide R1, R2, R3...Resin

Claims

1. A sheet formed from a mixture of granular calcium hydroxide and resin, The granular calcium hydroxide has a particle size such that the entire amount passes through a 600 μm sieve and the amount passing through a 150 μm sieve is 5% by weight or less of the total amount.

2. The sheet according to claim 1, wherein the granular calcium hydroxide is present in an amount of 30% to 80% by weight based on the total amount of the mixture.

3. The sheet of claim 1 having a thickness of from 150 μm to 600 μm.

4. 2. The sheet according to claim 1, having physical properties such that when 0.1 ml of water is dropped onto the surface, the pH value of the water is 11 or more.

5. The sheet according to claim 1 , which is a laminate having a sheet-like substrate attached to the front or back surface.

6. The sheet according to claim 1 , wherein the resin is a thermoplastic resin.

7. 7. The sheet of claim 6, wherein the thermoplastic resin is polyvinyl chloride or polypropylene.

8. The sheet of claim 1 , wherein the mixture includes an additive.

9. A sheet formed from a mixture of granular calcium hydroxide and resin, The calcium hydroxide having a particle size in which the entire amount passes through a 600 μm sieve and the amount passing through a 150 μm sieve is 5% by weight or less of the total amount is mixed with the resin, and the mixture is passed between at least a pair of rolls to form a sheet while a portion of the calcium hydroxide is crushed by the pair of rolls.

10. mixing granular calcium hydroxide with a resin to form a mixture; and forming the mixture into a sheet. The method for producing a sheet, wherein the granular calcium hydroxide has a particle size such that the entire amount of the granular calcium hydroxide passes through a 600 μm sieve and the amount passing through a 150 μm sieve is 5% by weight or less of the total amount.

11. The method for producing a sheet according to claim 10, further comprising passing the mixture between at least a pair of rolls to form a sheet while crushing a portion of the calcium hydroxide with the pair of rolls.

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