JP2016010905A - Cover sheet material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cover sheet material usable as a cover sheet material for agriculture and stockbreeding, capable of suppressing power consumption in summer and securing an optimum temperature condition for cultivation or breeding.SOLUTION: The cover sheet material includes a sheet substrate and a light scattering layer provided on at least one surface of the sheet substrate. The sheet substrate is formed of a resin composition containing a polypropylene resin and at least one of an inorganic filler and an organic filler. The porosity of the sheet substrate is 35 to 60% inclusive, and the reflectance in the configuration of the cover sheet material is 90% or more.

Description

  The present invention relates to a cover sheet material used in the fields of agriculture and livestock.

  Conventionally, cover sheet materials such as polyethylene films have been used in greenhouses in all fields of agriculture and livestock. House cultivation is a typical use example of this greenhouse cover sheet material. This house cultivation is to cultivate vegetables, flowers, fruit trees, mushrooms, etc. in a simple greenhouse consisting of a space covered with a cover sheet material. This development of house cultivation has made it possible to ship out-of-season crops by forcing and restraint cultivation, and also brought about a revolutionary change in horticultural agriculture. Examples of such changes include hydroponics and plant factories. Hydroponic cultivation and plant factories do not use soil, but a cultivation method that uses a culture solution in which fertilizer is dissolved. Production can be enhanced. Therefore, with the development of house cultivation, an excellent cover sheet material is always required to keep the cultivation environment in the house under optimum conditions.

  A conventional house used for such house cultivation uses a vinyl chloride resin film, a polyethylene film or an ethylene-vinyl acetate copolymer film as a cover sheet material, while holding the cover sheet material in a certain shape. Steel aggregates, plastic pipes, or woods are used as aggregates for this purpose, and are known as pipe houses. Of course, the cover sheet material described above is also used other than a house. For example, in order to increase the ground surface temperature, the cover sheet material is directly used as a material covering the ground surface, or in a shading or lighting curtain in a livestock house. Used.

  One of the reasons why such a material is used as a cover sheet material used in the field of agriculture and livestock is that the space or the ground surface covered by the cover sheet material is transmitted by transmitting sunlight. The purpose is to keep the space and the ground surface covered with the cover sheet material warm so that the heat inside the warmed house and the ground surface does not escape while raising the temperature. In recent years, in addition to the above-described materials, cover sheet materials made of non-woven sheets (polypropylene fibers) that have not only heat retention but also air permeability have been developed.

For example, as a cover sheet material using the above-mentioned nonwoven fabric sheet, for example, Patent Document 1 is a laminated sheet in which a hydrophilic nonwoven fabric and a porous film are laminated, has air permeability and light shielding properties, and has a certain degree of heat retention. It is described that.
Nonwoven sheet refers to a cloth-like material in which natural or man-made fiber staples or continuous filaments are joined together by an adhesive, molten fiber or mechanical methods. Moreover, a nonwoven fabric sheet is classified by the manufacturing method, and a characteristic changes with the classification, respectively.

  For example, one manufacturing method starts with staple fibers, joins the fibers together with a joining material to form a fibrous web, and then bonds the webs together to obtain a nonwoven sheet having a web or mat-like structure. And the nonwoven fabric sheet used for the conventional agricultural and livestock cover sheet material is manufactured by such a method. Therefore, the conventional non-woven sheet cover sheet material generally has both heat retention and air permeability.

  Further, as disclosed in Patent Document 2, a cover sheet material of a moisture permeable waterproof film in which particles are blended with a polyurethane resin having light shielding properties and waterproof properties and moisture permeability has been proposed. However, conventional cover sheets for agricultural and livestock greenhouses made of plastic film or non-woven fabric are sufficient for the demand for improvement of cultivation or breeding environment not only in house cultivation but also in a wide range of agriculture and livestock fields such as poultry farming, pig farming and sericulture. It was not a response. For example, a conventional cover sheet material for agriculture and livestock has been developed and used only for the purpose of keeping warm by raising the temperature of the ground covered with a house and maintaining the elevated temperature. Accordingly, no agricultural cover sheet material suitable for the purpose of preventing temperature rise in the house due to sunlight or artificial light has been developed.

That is, for example,
(1) Cultivate crops that cannot be cultivated at high temperatures in summer;
(2) In livestock barns, the deterioration of the barn sanitary environment, which is a problem particularly at high temperatures in summer, and the suppression of breeding of bacteria, etc .;
(3) In sericulture, the reduction in appetite for potatoes at high temperatures and the improvement of diseases are centered on the use of electric appliances such as air conditioning units. Therefore, high power consumption in summer Caused an increase in production prices.

  Therefore, development of a new cover sheet material for agriculture and livestock that can reduce power consumption in summer and ensure optimum temperature conditions for cultivation or breeding, more specifically, light shielding properties, temperature drop Development of a novel agricultural and livestock cover sheet material made of a nonwoven fabric sheet having excellent properties, water resistance, moisture permeability and the like is required.

JP 2009-78477 A JP 2002-241518 A

  The present invention has been made in such a situation, and is a cover that can be used as a cover sheet material for agriculture and livestock, which can suppress power consumption in summer and can secure optimum temperature conditions for cultivation or breeding. It aims at providing a sheet material.

  The above object is achieved by the present invention described below. That is, a cover sheet material comprising a sheet base material and a light scattering layer provided on at least one surface of the sheet base material, wherein the sheet base material is a polypropylene resin and an inorganic filler or It is formed of a resin composition containing at least one of organic fillers, the porosity of the sheet base material is 35% or more and 60% or less, and the reflectance of the cover sheet material is 90% or more. It was set as the structure of the cover sheet material characterized by this.

  The sheet base material has a thickness of 50 μm or more and 90 μm or less, and the light scattering layer is a white ink layer of 0.5 μm or more and 4 μm or less.

  Further, the cover base material and the light scattering layer are stretched at least in a uniaxial direction.

The polypropylene resin contained in the sheet base material is an ethylene-α olefin copolymer.
Further, the white ink layer has a configuration of a cover sheet material containing a white pigment.

  According to the present invention, it has become possible to suppress power consumption in summer and to secure optimum temperature conditions for cultivation or breeding.

It is a schematic sectional drawing which shows one embodiment of the cover sheet material of this invention. It is the schematic explaining the usage method in the greenhouse of the cover sheet material which concerns on this invention.

Next, an embodiment of the invention will be described in detail.
FIG. 1 shows one embodiment which is a cover sheet material according to the present invention.
The cover sheet material of the present invention is used as a cover sheet material for agriculture and livestock, and as shown in FIG. 1, a light scattering layer 3 is provided on one surface of the sheet base material 2 having moisture permeability and waterproofness. It is the cover sheet material 1 of the structure.
In addition, this invention is not limited by the following embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements disclosed in the following embodiments can be appropriately combined.

[Sheet substrate]
The sheet base material 2 used in the present invention is formed of a polypropylene resin and a resin composition containing one or both of an inorganic filler and an organic filler, and is composed of a thermoplastic resin. The sheet base material of the present invention contains fine voids, and has a porosity of 35% or more and 60% or less, and is made of a material that does not allow rainwater to pass but allows water vapor and gas to pass therethrough.
Polypropylene resins can be preferably used from the viewpoints of heat resistance, water resistance, chemical resistance and cost.

  Examples of such polypropylene resins include propylene homopolymers which are mainly composed of polypropylene and propylene which are isotactic or syndiotactic and various degrees of stereoregularity, and ethylene, butene-1, and hexene-1. A copolymer with α-olefin such as heptene-1,4-methylpentene-1 is preferably used. These copolymers may be binary, ternary or quaternary, and may be random copolymers or block copolymers.

In the present invention, it is preferable that the thickness of the sheet base material 2 is in the range of 50 μm or more and 150 μm or less because it has flexibility to handle as a cover sheet material and also maintains strength. The thickness of the sheet substrate 2 is more preferably in the range of 50 μm to 90 μm. If it is thinner than 50 μm, it is not preferable because it does not have rigidity as a cover sheet material and lacks strength. On the other hand, if the thickness exceeds 150 μm, the cover sheet material is heavy, so that the handling property is poor, and a burden is imposed on the work performed by the agricultural worker on the ground. In general-purpose vinyl chloride houses, the base material is usually 50 to 100 μm, and the lighter the work efficiency, the better.
On the other hand, if the thickness exceeds 150 μm, the amount of resin used in the sheet base material 2 is increased, which is not preferable because the cost becomes expensive.
Further, in order to increase the strength of the sheet base material 2, it is preferable to longitudinally stretch the sheet base material 2, and then apply the same resin layer to perform lateral stretching.

(Inorganic filler, organic filler)
The inorganic filler and organic filler used for the sheet base material of the cover sheet material of the present invention are used for the purpose of generating voids in the film by stretching, and the type of filler is not particularly limited.
Examples of inorganic fillers include heavy calcium carbonate, light calcium carbonate, calcined clay, talc, silicon oxide, diatomaceous earth, titanium oxide, magnesium oxide, zinc oxide, barium sulfate, and the like. It may be surface-treated. Among these, heavy calcium carbonate, light calcium carbonate, calcined clay, and talc are preferable because they are inexpensive and have good moldability. The inorganic filler having a particle size of usually 0.01 μm to 15 μm, preferably 0.01 μm to 8 μm can be used.
In the present invention, “A to B” in defining the numerical range means “A or more and B or less”.

  As the organic filler, it is preferable to select a different type of resin from the thermoplastic resin that is the main component. For example, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyamide, polyethylene naphthalate, polystyrene, melamine, polyethylene sulfite, polyimide, polyethyl ether ketone, polyether ether ketone, polyphenylene sulfite, poly-4-methyl-1-pentene, Examples thereof include polymethyl methacrylate, a cyclic olefin homopolymer, a copolymer of cyclic olefin and ethylene, and the like having a melting point of 120 ° C. to 300 ° C. or a glass transition temperature of 120 ° C. to 280 ° C.

One of these inorganic fillers or organic fillers may be selected and used alone or in combination of two or more. Moreover, the content is preferably 1% by mass to 65% by mass, and more preferably 2% by mass to 55% by mass.
If the content exceeds 65% by mass, the stretched film tends to break during transverse stretching after longitudinal stretching, which is not preferable.

  The sheet base material 2 of the present invention includes a nonionic surfactant (eg, glycerin fatty acid ester, pentaerythritol fatty acid ester, polyoxypropylene / polyoxyethylene block polymer), anion in order to prevent condensation as necessary. One or more kinds of surfactants (for example, sulfonate <Na, K, ammonium>, alkylbenzene sulfonate, etc.) or amphoteric surfactants can be added and mixed.

  In addition, a lubricant such as an aliphatic hydrocarbon such as liquid paraffin, synthetic paraffin, and microcrystalline wax, a stearic acid ester of a linear alcohol, and a higher fatty acid amide is appropriately selected and added as a lubricant to the sheet base material 2. be able to.

(Production method)
It does not specifically limit regarding the manufacturing method of the sheet | seat base material 2, A well-known manufacturing method is used.
For example, a resin melted by a plurality of extruders by co-extrusion can be produced by a single die using a feed block or a multi-manifold.

(Stretching)
For stretching, various known methods can be used. For example, the film is stretched in a uniaxial or biaxial direction by longitudinal uniaxial stretching, longitudinal uniaxial multistage stretching, transverse uniaxial stretching, longitudinal and transverse sequential biaxial stretching, longitudinal and transverse simultaneous biaxial stretching, or a combination thereof. These are usually stretched at a temperature lower than the melting point of the thermoplastic resin, and peeling occurs at the interface between the inorganic filler or organic filler and the thermoplastic resin, which propagates and expands due to stretching to form fine voids. It is formed. These stretching and lamination may be performed in any combination. In particular, paper is divided into an outer layer and an inner layer, and the inner layer base material layer is longitudinally stretched, and then the outer layer of the same resin is laminated on the inner layer surface layer and then laterally stretched to produce a sheet base material that is a laminate. You may give it a texture.

なお、上式中、ρｏは、シート基材の真密度を示し、ρはシート基材の密度＜ＪＩＳ Ｐ ８１１８に準拠＞を示すが、延伸前の材料が多量の空気を含有するものでない限り、真密度は延伸前の密度にほぼ等しい。 (Porosity)
The sheet base material 2 of the present invention has a porosity of 35% or more and 60% or less. Here, the porosity indicates the ratio of voids in the sheet base material and can be calculated by the following formula 1.

In the above formula, ρo represents the true density of the sheet base material, and ρ represents the density of the sheet base material (according to JIS P 8118), but unless the material before stretching contains a large amount of air. The true density is approximately equal to the density before stretching.

  The true density can be obtained by measuring and calculating by a dry density measuring method by a constant volume expansion method. For example, the true density can be measured using, for example, a dry automatic density meter “Acpic 1330” manufactured by Shimadzu Corporation, a multi-volume density meter “Acpic 1330 type” manufactured by Micromeritex Corporation, and the like.

In the agricultural and livestock fields, the sheet base material 2 used in the present invention has a porosity calculated by the above formula of 35% or more, but does not pass bacteria such as pathogenic bacteria, but permeates water vapor and gas. It is preferable for expressing the function as the cover sheet material used in the above, and 60% or less is preferable for maintaining the strength as the cover sheet material. If the porosity is less than 35%, the moisture permeability becomes poor, so that it cannot be used as a cover sheet material. If it exceeds 60%, the strength as the cover sheet material tends to be insufficient, which is not preferable.
The porosity is more preferably 40% to 58%.

The sheet base material 2 of the present invention preferably has an opacity of 70% to 100% (based on JIS Z 8722). If it is less than 70%, the cover sheet-like appearance of the sheet substrate cannot be visually recognized. It is preferable density of the sheet substrate 2 is ^{0.50g / cm 3 ~0.90g / cm 3} .
In the present invention, unless otherwise specified, those describing porosity and opacity are measured under the above-described measurement conditions.

(Antistatic agent)
If necessary, the resin forming the sheet base material of the present invention may be kneaded with an antistatic agent or applied to the surface of the sheet base material. As these antistatic agents, for example, cationic antistatic agents such as amines, imidazolines, amine oxide ethylene adducts, quaternary ammonium salts, anionic antistatic agents such as phosphates, alkylallylphosphonic acids, adipic acid, glutamic acid, Nonionic antistatic agents such as polyhydric alcohols, polyhydric alcohol esters, higher alcohol ethylene oxide adducts, polyethers, alkylphenol ethylene oxide adducts, glycerin esters of fatty acids, fatty acid amides and their ethylene oxide adducts, and cationic groups For example, a guanidine salt having both an anionic group and maleic anhydride on an alkylamine, and an amphoteric antistatic agent such as a sulfonic acid derived from polyethyleneimine can be used. Ruamin, hydroxyalkyl monoethanolamine, glycerin fatty acid esters, polyglycerol fatty acid esters, alkyl sulfonic acid sodium, sodium alkylbenzenesulfonate, a perchlorate tetraalkylammonium salt. One of these may be selected depending on the glass transition point of the thermoplastic resin and the processing conditions such as extrusion stretching, and these may be used alone, or two or more may be used in combination. Further, kneading and coating may be performed simultaneously.

  In the sheet base material, a white ink layer is used as the light scattering layer 3. The sheet base material has high whiteness, and exhibits excellent light scattering performance when the thickness is 90 μm or more. However, as described above, if the thickness is 150 μm or more, there is a weight for winding the sheet, and the operator also burdens the work of laying on each pipe of the pipe house, so the sheet base material is set at 50 μm to 90 μm. It is preferable. In addition, with the sheet base material alone, the reflectance is reduced to 50 to 90%, and a sufficient photosynthesis function cannot be given to plants. For this reason, by providing a light-scattering layer on a sheet | seat base material, the reflectance of a visible region is improved to 100%, and it functions also as an overcoat material which protects a sheet | seat base material from a crack.

A light-scattering layer can be comprised with a white ink layer, and the white ink layer is comprised from the white ink component shown below.
<White ink component>
(Resin component)
The resin component of the white ink component is not particularly limited as long as it is a resin having performance as a light scattering layer, such as a polyurethane resin and a polyester resin, and preferably a polyurethane resin. Examples of the polyurethane resin include polyurethane resins such as polyester polyurethane, polyether polyurethane, polyether polyester polyurethane, polycarbonate polyurethane, and polycaprolactam polyurethane, and mixtures thereof. Among these, when used as a resin component (binder) of the light-scattering layer of the cover sheet material of the present invention, the polyurethane-based resin has a low adverse effect on moisture permeability and is preferably selected.

  In the above resin component, at least one selected from polyurethane resins having a glass transition temperature H (° C.) of −60 ° C. ≦ H ≦ 0 ° C. and a weight average molecular weight Mw of 10,000 ≦ Mw ≦ 80,000. Are preferably used. If the above glass transition temperature is too high, the breaking strength and Young's modulus of the sheet base material on which the white ink layer is formed increase, and accordingly, the brittleness becomes poor and the tearability decreases, Practicality is reduced. On the other hand, when the glass transition temperature is too low, the toughness of the coating as the white ink layer is lowered.

  Moreover, when the weight average molecular weight of said polyurethane-type resin exceeds said upper limit, the film intensity | strength of the white ink layer obtained will become large, and brittleness will fall in connection with it, and tearability will fall. On the other hand, when the weight average molecular weight is less than the lower limit, blocking occurs in the resulting white ink layer coating.

  The polyurethane-based resin is a polyurethane obtained by reacting a polyisocyanate compound and a polymer polyol by a known method such as solution polymerization, and using a chain extender and a reaction terminator in a urethane prepolymer as necessary. Resin. Any polyurethane-based resin can be used as long as it satisfies the characteristic values of the resin component. The characteristic value is determined by various factors. For example, the characteristic value can be obtained by setting the amount of urethane groups constituting the polyurethane resin, the type and amount of polar groups, and the like.

  As said polyisocyanate compound, what is used for manufacture of the conventional polyurethane-type resin should just be used, for example, 1, 6- hexamethylene diisocyanate, methylene diisocyanate, trimethylene diisocyanate, 2,2,4- or 2 , 4,4-trimethylhexamethylene diisocyanate, tetramethylene diisocyanate, 1,2-propylene diisocyanate, isopropylene diisocyanate, 1,3-butylene diisocyanate, etc .; 1,3- or 1,4-cyclohexane diisocyanate, isophorone Alicyclic isocyanates such as diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, methyl-2,6-cyclohexanediisocyanate; m- or p-phenyle Diisocyanate, 4,4-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, and aromatic isocyanates such as naphthylene diisocyanate and the like.

  Moreover, as a polymer polyol made to react with said polyisocyanate compound, polyester polyols, such as saturated hydrocarbon type polyester polyol, polyether polyol, polyether ester polyol, etc. are mentioned.

  Examples of the polyester polyol include a polyester polyol composed of a polyvalent carboxylic acid and a polyhydric alcohol, and a polyester polyol obtained by ring-opening polymerization of a lactone ring. Examples of the polyvalent carboxylic acid include aliphatic polyvalent carboxylic acids such as linear saturated hydrocarbons such as adipic acid, azelaic acid, succinic acid, and sebacic acid; unsaturated fatty acids such as fumaric acid and maleic acid. Aliphatic polyvalent carboxylic acids; Alicyclic polyvalent carboxylic acids such as 1,4-cyclohexanedicarboxylic acid having a cyclohexyl group; Aromatic polyvalent carboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid.

  Examples of the polyhydric alcohol that reacts with the polycarboxylic acid include ethylene glycol, diethylene glycol, 1,3-propylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, xylylene glycol, polyethylene glycol, 1,2- Or aliphatic and alicyclic polyhydric alcohols such as 1,3-propanediol, 1,2-, 1,3- and 1,4-butanediol, 1,5-pentanediol, and aromatic polyhydric alcohols Etc.

  The polyether polyol is a polyether polyol obtained by polymerizing an oxirane compound such as ethylene oxide or propylene oxide using a polyhydric alcohol such as ethylene glycol, 1,2-propanediol or glycerin as a polymerization initiator. Can be mentioned. Moreover, as a polyetherester polyol, the polyetherester polyol obtained by making said polyhydric carboxylic acid react with said polyether polyol is mentioned.

  In addition to the polyisocyanate compound and the polymer polyol, the polyurethane-based resin may include ethylene glycol, diethylene glycol, and the like, as necessary, for adjustment of molecular weight, glass transition temperature, characteristic values of the resin component, and the like. The chain length in the resin is increased using chain extenders such as alcohols such as 1,2-propanediol, amines such as ethylenediamine and propylenediamine, and chain length terminators such as known lower alcohols and amines. It is preferable to adjust.

  The above resin component can be used alone or in combination of several kinds, but in order to further improve the tearability of the sheet substrate on which the white ink layer is coated, the resin component A curing agent can be added to the. Examples of the curing agent include the above-mentioned aliphatic, alicyclic or aromatic polyisocyanate compounds having a plurality of isocyanate groups, and other polyisocyanate compounds such as tolylene diisocyanate, hexamethylene diisocyanate, and triphenylmethane tris. Multimers such as isocyanate, diphenylmethane diisocyanate, o-toluidine diisocyanate, isophorone diisocyanate, 1,3,5-triisocyanate methylbenzene, lysine ester triisocyanate, and dimers and trimers derived from these isocyanate compounds And polyisocyanates obtained by reacting an isocyanate compound with a polyol compound such as 3,3,3-trimethylolpropane.

  Preferred examples of the curing agent include, for example, a trimer of hexamethylene diisocyanate, a reaction product of 3,3,3-trimethylolpropane and hexamethylene diisocyanate, 3,3,3-trimethylolpropane and tolylene diene. A reaction product with isocyanate is mentioned. As said hardening | curing agent, it can obtain with the brand name of Takenate D-110N from Mitsui Takeda Chemical Co., Ltd., and can use it by this invention.

  When using said hardening | curing agent, it is preferable that the usage-amount is mix | blended 0.8-10 mass% with respect to the said resin component. When there are too many compounding ratios of said hardening | curing agent, the film of the obtained white ink layer will become weak.

  Although the said resin component can be used independently, it is preferable to contain in the quantity which occupies 90 mass%-100 mass% in the binder (binder) whole quantity of the white ink component which comprises a white ink layer. When the blending ratio of the resin component is less than the lower limit, the tearability of the sheet base material on which the resulting white ink layer film is formed is not preferable.

  In the blending of the above resin components, cellulose derivatives such as nitrocellulose, cellulose propionate, cellulose acetate butyrate, cellulose diacetate, and cellulose triacetate, alkyd resin, acrylonitrile-butadiene copolymer, as long as the object of the present invention is not hindered. Resin components that are compatible with the above resin components, such as coalescence, polyvinyl butyral, styrene-butadiene copolymer, polyester resin, and epoxy resin, can be used in combination.

  The white ink for forming the white ink layer of the present invention comprises the above resin component and white powder, an organic solvent such as alcohols such as isopropyl alcohol and normal propyl alcohol, methyl acetate, ethyl acetate, butyl acetate, acetic acid. Esters such as propyl, ethyl lactate and ethylene glycol acetate, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ethers such as diethylene glycol methyl ether, tetrahydrofuran and dioxane, aromatics such as toluene and xylene, halogenated hydrocarbons It is obtained by uniformly dispersing and kneading in a known method and a mixed solvent thereof in a known method, and if necessary, additives such as a plasticizer and a dispersant do not interfere with the purpose of the present invention. Add and use in the range Door can be.

  As the white powder, known white pigments can be used, such as anatase-type titanium oxide, rutile-type titanium oxide, and titanium oxide whose surface is treated with a metal oxide such as Al or Si, and the like, and Examples include extender pigments such as calcium carbonate and barium sulfate, and other white pigments that can be used within the range not impairing the object of the present invention. The titanium oxide preferably has an average particle size of 0.1 μm to 0.5 μm. The blending ratio of the white powder is preferably 10% by mass to 50% by mass in the coating of the white ink layer.

The coating of the white ink layer of the present invention is formed by coating on the surface of the above-mentioned sheet base material by a coating method such as a known printing method. Examples of the coating method include a gravure coater, a reverse roll coater, a spray coater, a knife coater, a wire bar coater, an air knife coater, a doctor blade coater, a dipping coater, and a die coater, preferably a printing method using a gravure printing machine. The solid ink is printed at 0.2 to 0.7 g / m ² (dry thickness) and dried to form a white ink layer. The drying condition of the white ink layer is not particularly limited as long as the binder such as the sheet base material and the resin component is not deteriorated, but is preferably dried at 70 ° C to 80 ° C. The thickness of the white ink layer is 0.5 to 4 μm, preferably 1 to 2.5 μm, which improves the reflectance and does not affect the moisture permeability.

  It is preferable that both the sheet base material and the light scattering layer described above are stretched in at least a uniaxial direction. That is, it is preferable to manufacture the sheet base material and the light scattering layer by coextrusion and stretching in at least a uniaxial direction. Thereby, a uniform cover sheet material is obtained by integrating the sheet base material and the light scattering layer.

In the above, a white ink layer has been described as one embodiment of the light scattering layer. However, the light scattering layer is not limited to the white ink layer, and the light scattering layer has light reflectivity, moisture permeability, air permeability, and the like. Other layers that are not white ink layers can be used as long as they have a function.
Since the cover sheet material of the present invention has a structure in which a porosity of 35% to 60% and a light scattering layer is provided on the surface of the sheet substrate, light is diffusely reflected by the light scattering layer. By this, it is excellent in reflectivity, shows a high light-shielding effect as a result, and has further excellent air permeability and moisture permeability. The cover sheet material of the present invention has not only the heat retaining property and air permeability of the conventional cover sheet material, but also the reflective material, unlike the conventional cover sheet material that contains carbon particles and has light shielding properties. An excellent light scattering layer was provided to provide light shielding properties. Therefore, it became possible to ensure the optimal temperature conditions for cultivation or breeding without the temperature or the ground temperature covered with the cover sheet material of the present invention or the ground temperature rising excessively. Moreover, it can suppress that the air temperature or ground temperature of the space or ground covered with said cover sheet material rises, and can suppress the power consumption of air-conditioning equipment, such as cooling for suppressing the temperature rise.

The cover sheet material of the present invention has a reflectance of 90% or more in a configuration in which a light scattering layer is provided on a sheet base material, is excellent in reflectivity, and has a high light shielding effect as a result. If the reflectivity is less than 90%, sufficient reflectivity cannot be obtained, the light shielding property is lowered, and the temperature or the ground temperature of the space covered with the cover sheet material or the ground is increased.
In addition, what has described the reflectance by this invention is measured by the reflectance (total reflectance) in visible region 450-750 nm based on JISZ8722 unless there is particular notice.

(How to use as greenhouse cover sheet material)
The cover sheet material of the present invention is cultivated or bred such as use of a cover sheet material for greenhouses for cultivating vegetables, flower buds, fruit trees, mushrooms, etc. The sheet material is not limited as long as it is a sheet material that can be used to secure the optimum temperature condition.
Hereinafter, although the usage method as a greenhouse cover sheet material which is an example of the cover sheet material of this invention is demonstrated, it is not limited to this usage method.

  The cover sheet material 1 is cut into a sheet of an appropriate size (for example, a square of 2 m × 2 m) with a generally used paper cutting machine, and a plurality of sheets obtained are shown in FIG. Then, the hood-like cover sheet material 1 is formed by pasting the pipes of the greenhouse 4 with adhesive tape. FIG. 2A (covering only the roof portion) shows a state in which the side surface of the greenhouse (pipe house) 4 is not covered with the cover sheet material 1, that is, a state in which a side lighting portion is formed. In FIG. 2B (covering the roof and side portions), the roof portion and side surfaces of the greenhouse 4 are covered with the cover sheet material 1, that is, the side lighting portion is not formed (that is, the entire greenhouse is shielded from light). State).

(Example 1)
(Manufacture of sheet base material)
As a resin composition constituting the sheet substrate, 65.5% by mass of propylene homopolymer (manufactured by Nippon Polychem Co., Ltd., trade name Novatec PP, MA-8, melting point 164 ° C.), high density polyethylene (Nippon Polychem ( Co., Ltd., trade name Novatec HD, HJ580, melting point 134 ° C., density 0.960 g / cm ³ ) 6.5% by mass, and a resin composition comprising calcium carbonate powder 28% by mass with an average particle size of 1.5 μm An unstretched sheet was obtained using an extruder. Next, this unstretched sheet was stretched 4 times in the longitudinal direction to obtain a uniaxially stretched sheet.

On the other hand, as the resin composition for the surface layer constituting the laminate, the propylene homopolymer 51.5% by mass, the high-density polyethylene 3.5% by mass, and the average particle size 1.5 μm A composition comprising 42% by mass of calcium carbonate powder and 3% by mass of titanium oxide powder having an average particle diameter of 0.8 μm was melt-kneaded using another extruder, and both sides of the surface of the uniaxially stretched sheet substrate obtained above were mixed. The laminate was extruded from a die and laminated to obtain a laminate comprising a surface layer / base material layer / surface layer.
Next, this laminate was stretched 7 times in the transverse direction, the ears were slit, and the surface layer (15 μm) / base layer (40 μm) / surface layer (15 μm) total thickness contained 70 μm. The sheet base material 2 to be obtained was obtained. Under these conditions, the porosity of the entire sheet base material was 55% and the opacity was 93%.

The following components were uniformly kneaded and dispersed to prepare a white ink for forming a light scattering layer.
(Composition of light scattering layer)
・ Polyurethane resin [Yuriano 2466 manufactured by Arakawa Chemical Co., Ltd.] 40.0 parts ・ 2.0 parts of nitrified cotton ・ 39.0 parts of titanium oxide ・ Hardening agent (Takenate D-110N manufactured by Mitsui Takeda Chemical Co., Ltd.) ) 4.0 parts / solvent (isopropyl alcohol 5.0 parts, methyl ethyl ketone 6.0 parts, ethyl acetate 4.0 parts)

  This white ink was solid-printed to 3 μm (dry thickness) at a drying temperature of 80 ° C. with a gravure printing machine, dried to form a light scattering layer, and a cover sheet material of Example 1 was produced.

(Example 2)
A sheet base material (surface layer (10 μm) / base material layer (30 μm) / surface layer (10 μm)) having the same resin configuration as in Example 1 and a total thickness of 50 μm was manufactured. A light scattering layer having a thickness of 2 μm (dry thickness) was formed to produce a cover sheet material of Example 2.

(Example 3)
A sheet base material (surface layer (20 μm) / base material layer (50 μm) / surface layer (20 μm)) having the same resin configuration as in Example 1 and a total thickness of 90 μm was produced, and similarly 2 μm (dried) with a gravure printing machine. (Thickness) light scattering layer was formed to produce a cover sheet material of Example 3.

(Comparative example)
A sheet base material (surface layer (15 μm) / base material layer (40 μm) / surface layer (15 μm)) having the same resin configuration as in Example 1 and a total thickness of 70 μm was produced, but no light scattering layer was formed. . Thereby, the cover sheet material of the comparative example was produced.

(Measurement of reflectance of visible cover sheet material)
Shimadzu Corporation UV-3600 UV / visible / near-infrared spectrophotometer was used to measure the reflectance (total reflectance) in the visible region of 450 to 750 nm at an incident angle of 8 degrees using the integrating sphere accessory device ISR-3100. .
The determination for evaluating the reflectance was performed according to the following criteria.
A: The reflectance is 100% in the entire visible region.
A: The minimum reflectance is 90% or more in the visible region.
Δ: Some have a minimum reflectance of less than 90% in the visible region.

The results are summarized in Table 1.
Thereby, it turns out that visible light reflectance was able to be improved by provision of a light-scattering layer. In addition, the cover sheet material of the present invention shown in the examples has a configuration in which a porosity of 35% to 60% and a light scattering layer is provided on the surface of the sheet substrate, and the reflectance is 90%. Since it is the above, it is excellent in reflectivity by irregularly reflecting light with the light-scattering layer, and shows a high light-shielding effect as a result. Thereby, it is possible to suppress an increase in the temperature of the space or the ground covered with the cover sheet material of the embodiment or the ground temperature, and it is possible to ensure the optimum temperature condition for cultivation or breeding. And the power consumption of the air-conditioning equipment which suppresses the temperature rise can be suppressed.
On the other hand, the cover sheet material of the comparative example has a reflectivity lower than 90% and low reflectivity, resulting in inferior shading effect, suppressing power consumption in summer, and ensuring optimum temperature conditions for cultivation or breeding Indicates that it is impossible.

1 Cover sheet material 2 Sheet base material 3 Light scattering layer 4 Greenhouse

Claims (5)

A cover sheet material comprising: a sheet base material; and a light scattering layer provided on at least one surface of the sheet base material,
The sheet base material is formed of a polypropylene resin and a resin composition containing at least one of an inorganic filler or an organic filler,
The porosity of the sheet base material is 35% or more and 60% or less,
A cover sheet material having a reflectance of 90% or more in the configuration of the cover sheet material.   The cover sheet material according to claim 1, wherein the sheet base material has a thickness of 50 µm or more and 90 µm or less, and the light scattering layer is a white ink layer of 0.5 µm or more and 4 µm or less.   The cover sheet material according to claim 1, wherein the sheet base material and the light scattering layer are stretched in at least a uniaxial direction.   The cover sheet material according to any one of claims 1 to 3, wherein the polypropylene-based resin contained in the sheet base material is an ethylene-α-olefin copolymer.   The said white ink layer contains a white pigment and a polyurethane-type resin, The cover sheet material as described in any one of Claims 1-4 characterized by the above-mentioned.

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