JP6235250B2 - Agricultural sunscreen - Google Patents

Description

  The present invention relates to an agricultural shading agent.

  When a plant cultivated by thermal insulation using solar thermal energy such as house cultivation or tunnel cultivation is exposed to strong light rays such as strong sunlight in the summer, a phenomenon such as leaf burning is caused to the plant. The fear increases. Such a phenomenon may adversely affect plant growth. Therefore, as a method of suppressing the adverse effects on plants due to strong light, a method of covering a light shielding net on the outer surface of a sheet material such as a vinyl sheet constituting a house for tunnel cultivation and a house for house cultivation ( The outer surface side of the sheet material is formed by forming a light shielding structure such as a coating structure that can block light to some extent by spreading agricultural light shielding agent on the outer surface of the sheet material. A method of forming a light shielding surface (referred to as a light shielding surface forming method) has been implemented.

  In heat insulation cultivation, the light-shielding net covering method and the light-shielding surface forming method are usually carried out aiming at a specific time when strong sunlight falls on the ground surface. And it is not implemented other than such time. Rather, it is important to take in light efficiently in order to actively utilize the thermal energy of solar rays at times other than the time when strong sunlight falls on the surface of the earth.

  In this respect, the shading net coating method has a problem that the preparation cost is increased because the shading net itself is expensive, and that the installed shading net is not easily removed when the implementation is finished. there were.

  Because of these problems, a method for forming a light shielding surface has been widely used as a method for suppressing adverse effects on plants by intense light. In the light-shielding surface forming method, an agricultural light-shielding agent is used. As the agricultural light-shielding agent, a composition composed of a composition containing water, an aqueous binder, and a pigment is used. Conventionally, calcium carbonate has been mainly used as a pigment contained in agricultural shading agents (for example, Patent Document 1). This agricultural light-shielding agent has a white color derived from calcium carbonate. When the light-shielding surface forming method is performed, a white structure is formed on the sheet material as the light-shielding structure of the agricultural light-shielding agent. The outer surface side of the material is the light shielding surface. At this time, the white structure may be formed in a film shape. Such a white structure softens the amount of light applied to the plant through the sheet material to a certain level, thereby suppressing adverse effects on the plant due to strong light.

JP 2006-25698 A

  However, in the conventional method for forming a light-shielding surface using an agricultural light-shielding agent, it is difficult to evenly spread the agricultural light-shielding agent on the sheet material, and the outer surface side of the sheet material is uneven. There is a problem that a light-shielding surface is easily formed, and even after the outer surface side of the sheet material is made a light-shielding surface with an agricultural light-shielding agent, the light-shielding structure tends to flow down from the sheet material due to rain, etc. There is a problem that it is difficult to hold the light-shielding structure on the surface of the sheet material until the surface forming method is completed.

  The present invention allows the outer surface of the sheet material to be dispersed on the outer surface, thereby forming a light-shielding structure with reduced unevenness to be a light-shielding surface, and suppressing the risk of falling off due to rain or the like An object of the present invention is to provide an agricultural shading agent capable of forming a light shielding structure.

The present invention is (1) an agricultural shading agent comprising water, an aqueous binder and a pigment,
The aqueous binder is an aqueous resin emulsion having an acid value of 30 to 300,
The pigment comprises titanium oxide having an average particle diameter of 0.1 μm or more and 0.5 μm or less subjected to surface hydrophilization treatment , and calcium carbonate, and the mixing ratio of titanium oxide to calcium carbonate is expressed as a weight ratio. Agricultural shading agent, characterized in that it is 1/10 or more and 5 or less,
(2) Calcium carbonate contained in the pigment has the gist of the agricultural shading agent according to the above (1) having an average particle diameter of 0.05 μm or more and 10 μm or less .

  According to the present invention, by spreading the sheet material on the outer surface, it is possible to form a light-shielding structure with reduced unevenness on the outer surface, and to flow down due to rain or the like. It is possible to provide an agricultural light-shielding agent capable of forming a light-shielding structure with a reduced amount of light.

[Agricultural shading agent]
The agricultural shading agent of this invention contains water, an aqueous binder, and a pigment.

(Water-based binder)
The aqueous binder is an aqueous resin emulsion having an acid value of 30 or more and 300 or less. Examples of the resin constituting the aqueous resin emulsion include acrylic resins, urethane resins, vinyl resins, polyester resins, epoxy resins, etc., but water dispersible acrylic resins, water dispersible urethane resins. Is preferably selected.

  The acid value is determined by potassium hydroxide titration using phenolphthalein as an indicator.

  In general, the acid value in the resin is a value related to the average number of free carboxylic acid groups per polymer chain constituting the resin. The greater the value of acid value in the resin, the poorer the water resistance, that is, the more easily it is soluble in water. The smaller the value of the acid value in the resin, the more difficult the resin is soluble in water. In consideration of this, the aqueous binder contained in the agricultural shading agent is an aqueous resin emulsion, and the acid value of the resin component constituting the aqueous resin emulsion is 30 or more and 300 or less. A state in which the binder is mixed with water can be formed effectively, and an agricultural shading agent is dispersed on the outer surface of a predetermined sheet material to form a light shielding structure, and the outer surface side of the sheet material is shielded from light. In this case, the light-shielding surface can ensure water resistance for a certain period.

  If the water-based resin emulsion is an emulsion of a resin having an acid value of less than 30, it may not be possible to easily remove the light-shielding structure from the sheet material. If the water-based resin emulsion is an emulsion of a resin having an acid value exceeding 300, the water resistance of the light-shielding structure is lowered, and the light-shielding structure is likely to flow off from the sheet material due to rain and wind, and the light-shielding structure is maintained for a predetermined period. There is a risk that it will not be possible.

  The average particle diameter of the resin in the state of the aqueous resin emulsion is preferably 0.01 μm or more and 0.5 μm or less, considering that the aqueous resin emulsion can function more reliably as an emulsion.

  The content of the water-based binder in the agricultural shading agent can be selected as appropriate, but generally the resin solid content contained in the water-based binder is 0.1 to 10 parts by weight with respect to 100 parts by weight of water. It is preferable that the amount is small. When the resin solid content contained in the water-based binder in the agricultural light-shielding agent is less than 0.1 parts by weight with respect to 100 parts by weight of water, the light-shielding structure may not be sufficiently formed on the sheet material. . When the resin solid content contained in the water-based binder in the agricultural light-shielding agent exceeds 10 parts by weight with respect to 100 parts by weight of water, the spraying workability of the agricultural light-shielding agent is deteriorated and time after drying is sprayed. In addition, there is a possibility that the sustainability of the light-shielding structure is not improved to the extent corresponding to the longer drying time, and an economically effective agricultural light-shielding agent may not be obtained.

(Pigment)
The pigment includes titanium oxide and calcium carbonate.

(Calcium carbonate)
The average particle diameter of calcium carbonate contained in the pigment is not particularly limited, but is preferably about 0.05 μm or more and 10 μm or less. When the average particle size of calcium carbonate exceeds 10 μm, the particles tend to settle, and when the average particle size of calcium carbonate is less than 0.05 μm, the particles tend to aggregate. In addition, the average particle diameter here shall show a primary particle diameter. The same applies to the average particle diameter of titanium oxide described later.

(Titanium oxide)
The titanium oxide contained in the pigment has an average particle size of 0.1 μm or more and 0.5 μm or less. If the average particle size of titanium oxide exceeds 0.5 μm, it tends to settle, and it may be difficult to obtain an agricultural shading agent with good workability. When the average particle size of titanium oxide is less than 0.1 μm, the tendency to easily aggregate increases, and an agricultural light-shielding agent is spread on the outer surface of a predetermined sheet material to form a light-shielding structure on the sheet material to block light. Even if the surface is formed, there is a possibility that the light shielding property may not be exhibited.

  Moreover, it is preferable that the titanium oxide has been subjected to a surface hydrophilization treatment.

(Surface hydrophilization treatment)
Examples of the method for the surface hydrophilization treatment include a method for modifying the particles to be surface hydrophilized with a special polymer, a fatty acid, a sulfonic acid, an aluminum compound, a zinc compound, silica or the like. . Thus, when the surface of the titanium oxide is subjected to a hydrophilic treatment, the wettability of the surface of the titanium oxide is improved and it becomes easy to form a dispersed state in water.

(Blend ratio of titanium oxide to calcium carbonate)
The pigment is configured such that the blending ratio of titanium oxide to calcium carbonate (titanium oxide / calcium carbonate) is 1/10 or more and 5 or less by weight. When the blending ratio of titanium oxide with respect to calcium carbonate is less than 1/10 by weight, the effect of adding titanium oxide is not sufficiently exhibited, and formed by spraying an agricultural light-shielding agent on the outer surface of the sheet material. There is a possibility that the light shielding surface may have uneven light shielding properties. On the other hand, when the blending ratio of titanium oxide to calcium carbonate exceeds 5 by weight, the weight of the agricultural light-shielding agent increases, and the workability decreases.

(Other pigment components)
The pigment may be composed of only titanium oxide and calcium carbonate, or other pigments as long as it is composed of titanium oxide and calcium carbonate having a predetermined average particle diameter and a predetermined blending ratio as described above. It may further contain a component. Examples of other pigment components include talc, clay, silica, mica, barium sulfate, and the like.

(Additive)
In addition to the above-described components, various additives may be further added to the agricultural shading agent as necessary within a range not detracting from the spirit of the present invention. Examples of additives include curing agents, preservatives, thickeners, thickeners, dispersants, surfactants, antioxidants, ultraviolet absorbers, light stabilizers, alcohols, and the like.

[Preparation of agricultural shading agent]
The agricultural shading agent can be prepared by mixing each component constituting a pigment such as titanium oxide and calcium carbonate and an aqueous binder with water.

[Use of agricultural shading agents]
The agricultural shading agent can be used by being sprayed on the outer surface of a sheet material (sometimes referred to as an agricultural sheet material) that can be used in heat insulation cultivation. The spraying method of the agricultural shading agent is not particularly limited, and an appropriate method such as spray spraying can be used. In addition, when carrying out the spraying of the agricultural light-shielding agent, a pigment, an aqueous binder and water are mixed to prepare an agricultural light-shielding agent stock solution. From the viewpoint of improving the workability of transportation from the storage place to the spraying place, it is preferable to prepare this and use it as an agricultural shading agent to which this diluted solution is sprayed.

  A vinyl chloride agricultural resin film or the like is suitably selected as a sheet material that can be used in heat-stable cultivation. The resins constituting the vinyl chloride agricultural resin film include polyvinyl chloride homopolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-isobutylene copolymer. Polymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-styrene-maleic anhydride terpolymer, copolymer of vinyl chloride and alkyl, cycloalkyl or alkylmaleimide, vinyl chloride-styrene-acrylonitrile copolymer Polymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, vinyl chloride-vinylidene chloride-vinyl acetate terpolymer, vinyl chloride-acrylic acid ester copolymer, vinyl chloride-maleic acid ester copolymer Polymer, vinyl chloride-methacrylate copolymer, vinyl chloride Le - acrylonitrile copolymer, vinyl chloride - vinyl chloride copolymers such as urethane copolymers.

The amount of application of the agricultural light-shielding agent to the sheet material that can be used in the heat insulation cultivation is not particularly limited, but the amount of application of the agricultural light-shielding agent is 0.1 to 50 g / m ^{2 in} solid content contained in the agricultural light-shielding agent. It is preferable that it is the quantity used as a grade. If it is less than 0.1 g / m ² , it may be difficult to obtain a sufficient light shielding effect. Moreover, when it exceeds 50 g / m < ² >, there exists a possibility that the loss by the dripping of the agricultural shading agent may arise from a sheet | seat material during a dispersion | spreading operation.

  When the agricultural light-shielding agent is sprayed on the sheet material in this way, a light-shielding structure is formed on the sheet material surface, and the sheet material surface forms a light-shielding surface. The light-shielding structure may be a structure formed by adhering many fine granular structures on the sheet material surface, or may be formed in a film shape on the sheet material surface. The formed light-shielding surface has excellent uniformity and moderate durability of the light-shielding structure.

(Removal of light-shielding structure)
The light-shielding structure can be easily removed with an alkaline removing solution without using a large amount of an organic solvent when it becomes unnecessary.

(Another example of a method for forming a light-shielding structure)
In addition, although the example which sprinkles agricultural light-shielding agent and forms a light-shielding structure was demonstrated above, the formation method of the light-shielding structure using an agricultural light-shielding agent is not limited to this, Agricultural light-shielding agent is used. You may form by apply | coating with a roller etc.

  The present invention will be described in more detail below using examples and comparative examples. The present invention need not be limited to these examples.

Examples 1 to 7, Comparative Examples 1 to 5
For each example and each comparative example, water, an aqueous binder and a pigment are mixed to prepare an agricultural shading stock solution, and 7 times (by weight) of water is added to the total agricultural shading stock solution. Then, the agricultural light-shielding agent stock solution was diluted 8 times to prepare an agricultural light-shielding agent having the composition shown in Table 1 below. Note that calcium carbonate and titanium oxide were prepared as components constituting the pigment. Two types of calcium carbonate (in Table 1, calcium carbonates 1 and 2) and three types of titanium oxide (in Table 1, titanium oxides 1, 2, and 3) were prepared. For each example and each comparative example, the pigment is composed of calcium carbonate and titanium oxide blended in the composition shown in Table 1.

  In Table 1, the components constituting the pigment and the aqueous binder are as follows.

Calcium carbonate 1: manufactured by Maruo Calcium Co., Ltd., trade name: Luminous (primary particle size: 0.1 μm).
Calcium carbonate 2: manufactured by Omi Chemical Industry Co., Ltd., trade name: Akadama (primary particle size: 2-3 μm).
Titanium oxide 1: manufactured by Teika Co., Ltd., trade name: JR-600A, (primary particle diameter: 0.25 μm), and surface hydrophilized with an aluminum compound.
Titanium oxide 2: manufactured by Teika Co., Ltd., trade name: JR-405, (primary particle size: 0.21 μm), and surface hydrophilized with an aluminum compound.
Titanium oxide 3: manufactured by Teika Co., Ltd., trade name: JR, (primary particle diameter: 0.27 μm), not subjected to surface hydrophilization treatment.
Water-based binder: An acrylic resin emulsion having an acid value of 60, a molecular weight of 200,000, and a resin solid content of 47%.

  In Table 1, for each of Examples 1 to 7 and Comparative Examples 1 to 5, the numbers shown in the columns of water, aqueous binder, calcium carbonate 1, 2 and titanium oxide 1, 2, 3 indicate parts by weight. .

  Using the agricultural light-shielding agents of Examples 1 to 7 and Comparative Examples 1 to 5, each test of sedimentation suppression confirmation test, spray uniformity confirmation test, and light-shielding confirmation test was performed, and the results were evaluated. Moreover, the workability | confirmation confirmation test was done about the agricultural shading stock solution of each Example and each comparative example, and the result was evaluated. The test methods and results evaluation criteria are as follows. The results of each test are as shown in Table 1.

(Sedimentation inhibition confirmation test)
About the adjusted agricultural shading agent (after dilution), the sedimentation degree of the pigment was visually confirmed, and the test results were evaluated according to the following criteria.

(Evaluation criteria for the results of sedimentation inhibition confirmation test)
It is recognized that there is no sedimentation by visual observation: Sedimentation suppression is good (indicated by ○ in Table 1)
Although it is recognized that there is some sedimentation by visual observation, it is recognized that the mixture is dispersed immediately after being stirred several times. The sedimentation inhibitory property is slightly poor (indicated by Δ in Table 1).
Sedimentation is observed visually and the sedimentation state remains recognized even after stirring several times: Sedimentation inhibition is poor (indicated by x in Table 1)

(Blowing uniformity confirmation test)
As a sheet material that can be used in heat insulation cultivation, a vinyl chloride agricultural resin film was prepared, and an agricultural house for carrying out house cultivation was set up so that this sheet material became an outer surface material. The prepared agricultural shading agent was sprayed on the outer surface of the sheet material constituting the agricultural house, and the outer surface of the sheet material was used as a light shielding surface. In application, the basis weight of the agricultural shading agent was set to 30 ml / m ² . Thereby, the test result was evaluated according to the following criteria based on whether or not scattering unevenness was observed on the outer surface of the sheet material of the agricultural house.

(Evaluation criteria for results of spray uniformity test)
It is recognized that there is no scattering unevenness by visual observation: The spraying uniformity is good (indicated by ○ in Table 1).
It is recognized that there is uneven dispersion by visual observation: spraying uniformity is poor (indicated by x in Table 1)

(Light shielding test)
Prepare a vinyl chloride agricultural resin film of the same type as that used in the spray uniformity confirmation test (referred to as the test film in the description of the light shielding confirmation test), and apply an agricultural light shielding agent to one side of the test film. Spraying was performed at a basis weight of 30 ml / m ² to obtain a test film with an agricultural shading agent. The intensity of transmitted light was measured for each of the agricultural light-shielding agent adhesion test film and the test film that was not sprayed with the agricultural light-shielding agent (referred to as a blank film). The transmitted light intensity (B) measured for the agricultural light-shielded test film against the transmitted light intensity (A) measured for the blank film, ie, (1−B / A) × 100. (%) (Referred to as shading rate (%)) was specified. The intensity of transmitted light (A) and the intensity of transmitted light (B) were both measured with a solar simulator (manufactured by Celic Co., Ltd.).

(Evaluation criteria for results of light shielding test)
Light shielding ratio (%) is 20% or more: Good light shielding property (indicated by ○ in Table 1)
The light shielding ratio (%) is 10% or more and less than 20%: The light shielding property is slightly poor (indicated by Δ in Table 1).
The light shielding ratio (%) is less than 10%: The light shielding property is poor (indicated by x in Table 1).

(Workability confirmation test)
The specific gravity of the agricultural light-shielding agent stock solution before dilution was measured using water as a standard substance, and the test results were evaluated according to the following criteria.

(Evaluation criteria for workability confirmation test results)
Specific gravity is less than 1.5: When put into a container of a predetermined volume and transported, the weight of the transported material is not easily increased, and transporting work is easy, and dilution is also easy (workability is good). (Indicated in circle in Table 1)
Specific gravity is 1.5 or more: When being put into a container of a predetermined volume and transported, the work of transporting the weight of the transported material is likely to be difficult (indicated by x in Table 1).

(Contrast of basis weight for obtaining a predetermined light shielding property)
About the agricultural shading agent of Example 1 and the comparative example 2, the fabric weight for obtaining a predetermined light-shielding property was compared as follows.

On the outer surface of the sheet material constituting the agricultural house formed in the same manner as that used in the spray uniformity confirmation test, the basis weight of the agricultural shading agent obtained in Example 1 was 30 ml / m ² . A light shielding surface was formed on the outer surface side of the sheet material so that the light shielding ratio was specified by performing a test similar to the light shielding property confirmation test on the sheet material on which such a light shielding surface was formed.

Further, the same test was performed on the agricultural shading agent obtained in Comparative Example 2. However, for the agricultural shading agent obtained in Comparative Example 2, the basis weight was 50 ml / m ² . In both Example 1 and Comparative Example 2, the light shielding rate was 25%. The basis weight required to obtain the same light shielding property is smaller in Example 1 than in Comparative Example 2. Even if it sees from this, it turns out that the agricultural light-shielding agent which uses together the calcium carbonate and titanium oxide of this invention is excellent in light-shielding property than the agricultural light-shielding agent which is not used together.

Claims (2)

An agricultural shading agent comprising water, an aqueous binder and a pigment,
The aqueous binder is an aqueous resin emulsion having an acid value of 30 to 300,
The pigment contains titanium oxide having an average particle size of 0.1 μm or more and 0.5 μm or less that has been subjected to a surface hydrophilization treatment, and the blending ratio of titanium oxide to calcium carbonate is 1/10 by weight. It is comprised so that it may become 5 or less above, The agricultural shading agent characterized by the above-mentioned. 2. The agricultural shading agent according to claim 1, wherein the calcium carbonate contained in the pigment has an average particle diameter of 0.05 μm or more and 10 μm or less .