JPH10174530A - Light shield material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a light shielding material adequate for use as curtains in greenhouses, open-field tunnel materials, etc., in light shielding cultivation of high-temp. seasons by coating at least one surface of a nonwoven fabric made of synthetic fibers with a synthetic resin binder dispersed with white pigments of a high refractive index and drying the coating. SOLUTION: The split fiber nonwaven fabric is obtd. by subjecting a PVA film having, for example, an average degree of polymn. of 1700 and a saponification rate of 99.9% to stretching and heat treatment, then applying an aq. 5% PVA soln. having the average degree of polymn. of 1,400 and the saponification rate of 99.9% thereon, then laminating and adhering the film. Next, the white split fiber nonwoven fabric obtd. by coating the split fiber nonwoven fabric surface by an immersion method with a binder formed by dispersing 10 pts.wt. rutile type titanium dioxide pigments with the aq. 5% PVA soln. having the average degree of polymn. of 1,400 and the saponfication rate of 99.9% and drying the coating is subjected to embossing so as to shrink about 10% in a longitudinal direction, by which the desired light shielding material having a light shielding rate of 50% is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an agricultural covering material suitable for use as a curtain in a house, a material for an open-field tunnel, a material for an open-field solid, and the like, mainly in shade cultivation in a high temperature period such as summer. Specifically, the present invention relates to an agricultural covering material having a low light-shielding rate, a high light-receiving property, and a high heat-shielding property.

[0002]

2. Description of the Related Art Agricultural coating materials (hereinafter, abbreviated as light-shielding materials) conventionally used for shading cultivation include films or sheets made of various synthetic resins such as a vinyl chloride synthetic resin and a polyolefin synthetic resin. Things have been used.

[0003] These synthetic resins are not themselves light-shielding materials, but are provided with light-shielding properties by a complex means such as adding a light-shielding pigment or coating. Usually, a sheet made by kneading aluminum powder into a sheet, a sheet coated with aluminum powder via a binder, a lamination processing of a sheet and aluminum foil, or a metallized film obtained by vapor-depositing aluminum on a sheet Is used. Further, a sheet prepared by kneading a black pigment such as carbon black or the like, or a colored film or sheet obtained by coating a sheet has been used.

[Problems to be solved by the invention]

However, in light-shading cultivation, the sunshine intensity is corrected to an appropriate level for the target crop during a particularly high intensity of the sunshine, such as in summer, to artificially create a cultivation environment suitable for the target crop. Since a light-shielding material is used in order to perform the light-shielding operation, appropriate light-shielding properties and heat-shielding properties are required as the performance required for the light-shielding material.

[0005] Regarding pigments, since aluminum powder has a lower reflectance of infrared rays (heat rays) than its light-shielding effect, the material temperature rises when irradiated with sunlight, and the aluminum powder enters the coating system. Re-emission of infrared rays occurred, and the temperature in the coating system increased, so that sufficient heat shielding properties could not be obtained. Further, from the above, in the case of a material using aluminum, when an appropriate amount of light is required, for example, when it is desired to suppress the light shielding ratio to a low value of 60% or less, the light shielding ratio is increased only by adding a small amount of aluminum powder. Therefore, the amount of addition is limited, and therefore, infrared rays (heat rays)
However, there is a problem that the heat shielding property cannot be sufficiently blocked and reflected, and the heat shielding property is reduced, so that a low light blocking rate and a high heat shielding property cannot be achieved at the same time. Another drawback of aluminum is that it is easily oxidized by moisture and temperature, and discoloration and alteration cannot be completely prevented. Therefore, there is a problem that a long-term use lowers the light blocking ratio.

Also, in the case of black pigments such as carbon black, the pigment absorbs infrared rays in the same manner as aluminum powder, so that infrared rays are re-emitted into the coating system, and sufficient heat shielding properties can be obtained. Did not.

Further, when a metal such as aluminum or a black pigment such as carbon black is used for the light-shielding element, the unblocked light becomes transmitted light, so that most of the transmitted light is direct light and scattered light is poor. Shadows were easily formed in the coating system, and problems such as uneven growth of crops and insufficient coloring of fruits and the like were likely to occur.

Further, as for the sheet material, conventionally used synthetic resin has poor moisture absorption and moisture permeability of the material itself, cannot cope with an increase in humidity due to a temperature drop at night, and the inside of the coating system is over-humidified. In addition to the above, condensation of excess water vapor was generated, causing the occurrence of diseases such as gray mold.

Therefore, in order to suppress the occurrence of a disease under an over-humid condition, a reticulated web obtained by stretching, splitting and heat-treating a PVA-based synthetic resin film having high moisture-absorbing and moisture-permeable properties is used. There is known a light-shielding material in which at least one surface of a split-fiber nonwoven fabric obtained by laminating and bonding sheets is subjected to aluminum processing (JP-A-61-260817, etc.).

However, since the light-shielding material uses aluminum as the light-shielding element, the above-described problem has occurred.

Further, in order to enhance the heat shielding property of the split fiber nonwoven fabric made of PVA synthetic resin, a heat shielding (light shielding) material comprising an aluminum layer or a biotite layer and a titanium dioxide layer sequentially provided on the surface of the split fiber nonwoven fabric. And its manufacturing method (Japanese Patent Application Laid-Open
No. 153168). However,
Also in this material, since the aluminum layer or the biotite layer is used as a heat-shielding element, the light-shielding rate is high, and the light-shielding rate is low, in other words, it is not suitable for growing crops that require daylighting. Since the layer or the biotite layer blocks incident light, there is a problem that scattered light transmitted through the coating system is poor and a shadow is easily formed in the coating system.

[0012] Titanium dioxide is well known as a photo-oxidation catalyst and oxidizes and cuts a polymer by light energy (ultraviolet light), thus causing a problem that the weather resistance of the material is remarkably reduced. For this reason, when using titanium dioxide, it is essential to add an ultraviolet absorber. However, if the ultraviolet absorber blocks the transmission of ultraviolet light into the coating system, poor growth may occur in some crops, or ultraviolet light may be blocked. There has been a problem that it is impossible to remove pests by bumblebees that use activities.

The present invention has been made to solve such a problem, and has an appropriate light-shielding property, allows abundant scattered light to pass through the coating system, has a high heat-shielding property, and has a gray scale. An object of the present invention is to provide a light-shielding material that suppresses the occurrence of diseases such as mold disease.

[0014]

According to the first aspect of the present invention, there is provided a synthetic resin binder comprising a nonwoven fabric made of synthetic resin fibers and a high-refractive-index white pigment dispersed on at least one surface of the nonwoven fabric. Is a light-shielding material obtained by coating and drying.

Further, according to the invention of claim 2, a plurality of webs obtained by stretching, splitting and heat-treating a synthetic resin film are laminated so that the stretching direction is perpendicular to the process.
A light-shielding material obtained by coating and drying a synthetic resin binder in which a white pigment having a high refractive index is dispersed on at least one surface of a split fiber nonwoven fabric obtained by bonding.

According to a third aspect of the present invention, in the light shielding material according to the second aspect, the synthetic resin film is a hydrophilic synthetic resin film.

According to a fourth aspect of the present invention, in the light shielding material according to the third aspect, the hydrophilic synthetic resin film is
It is a polyvinyl alcohol-based synthetic resin film.

Further, the invention of claim 5 is based on claims 1, 2, and
3. The light-shielding material according to item 3 or 4, wherein the white pigment is rutile-type titanium dioxide.

Further, the invention of claim 6 is based on claims 1, 2 and
6. The light-shielding material according to 3, 4, or 5, wherein the synthetic resin binder is a hydrophilic synthetic resin aqueous solution.

Further, the invention of claim 7 is the invention of claims 1, 2,
6. The light-shielding material according to 3, 4, or 5, wherein the synthetic resin binder is a polyvinyl alcohol-based synthetic resin aqueous solution.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, one embodiment of the above-mentioned light shielding material of the present invention will be described.

The nonwoven fabric used in the present invention is not particularly limited in both form (production method) and material, but is a split-fiber nonwoven fabric or a soft sheet which is easily processed to coat a white pigment. It is preferable to use a non-woven fabric having thin and flat fibers such as a tape-glued adhesive, and a hydrophilic synthetic resin is used as the material to improve the moisture absorption and moisture permeability of the material. Is preferred. However, the nonwoven fabric also includes a general nonwoven fabric made of synthetic resin fibers in addition to the split-fiber nonwoven fabric.

In the present invention, the split-fiber nonwoven fabric is obtained by laminating and bonding a plurality of webs obtained by stretching, splitting and heat-treating a synthetic resin film so that the stretching direction is perpendicular to the process. . As a method of stretching the synthetic resin film, any known method can be used, but preferably the glass transition temperature of the synthetic resin film or more,
It is preferable to perform free-width uniaxial stretching in which stretching is performed at an appropriate temperature equal to or lower than the melting temperature by a difference in speed between rolls, so that the molecular orientation is aligned in the stretching direction, and the next split processing is facilitated. For the splitting, a known splitter such as a razor splitter or a needle splitter can be appropriately used.

The hydrophilic synthetic resin used in the present invention includes acrylic synthetic resin, polyamide synthetic resin, PV
A-type synthetic resin and the like can be mentioned, but it is particularly preferable to use a PVA-type synthetic resin having high absorption and moisture permeability and good weather resistance.

Examples of the white pigment used in the present invention include calcium carbonate, aluminum oxide, and titanium dioxide. Titanium dioxide having a high refractive index is particularly preferable. 2
As the titanium oxide, any of a rutile type and an anatase type can be used, but it is preferable to use a rutile type having a relatively high refractive index because it hardly causes chalking.

The hydrophilic synthetic resin binder for dispersing the white pigment used in the present invention is not particularly limited as long as it has a good affinity for the nonwoven fabric as the base material and good weather resistance. When the nonwoven fabric is made of a PVA-based synthetic resin, it is preferable to use a PVA-based synthetic resin aqueous solution as a hydrophilic synthetic resin binder. The mixing ratio of the white pigment to the PVA-based synthetic resin aqueous solution is as follows:
It is preferable that PVA-based synthetic resin solid content / pigment weight = 1 or more in that the pigment is fixed to the surface of the nonwoven fabric.

When titanium dioxide is used as the white pigment, it is preferable to use a PVA-based synthetic resin aqueous solution as the hydrophilic binder.

This is because titanium dioxide is a photo-oxidation catalyst and, when added as a pigment, usually significantly reduces the weather resistance of the material. This is because oxygen in contact with titanium dioxide is converted into active oxygen by light energy (ultraviolet light),
This is because the active oxygen oxidizes and cuts the polymer constituting the material.

On the other hand, it is well known that PVA is a material which is hardly deteriorated by ultraviolet rays due to its high hydrogen bonding and high bonding energy in the molecular structure.
In addition, it is a crystalline polymer having a high degree of crystallinity, and a dried film of PVA has characteristics of excellent gas barrier properties and low oxygen permeability.

In the present invention, titanium dioxide is dispersed in an aqueous PVA-based synthetic resin solution, coated on a nonwoven fabric, and dried, so that titanium dioxide particles are coated with a PVA film having a low oxygen permeability. So,
Since the generation of active oxygen is suppressed, the weather resistance of the material is not reduced. Further, since it is not necessary to use an ultraviolet absorber, it is possible to sufficiently transmit ultraviolet light into the coating system.

The light-shielding material obtained by the present invention uses a white pigment having a high reflectance in the infrared region as a light-shielding element. Re-radiation (radiation) is suppressed, and has high heat shielding.

Further, since a pigment having a high refractive index is used, abundant scattered light is transmitted into the coating system, so that shadows are hardly formed in the coating system, uniform growth of crops, fruits and flowers, etc. In addition to promoting uniform coloration, the light-shielding effect of the pigment is reduced, so that the light-shielding rate is suppressed as compared with the amount added, so that even when a low light-shielding rate is required, the entire surface of the material has a sufficient thickness. Can be coated with a light-shielding layer, for example, even if the light-shielding ratio is as low as about 30%, the pigment can be sufficiently added, and high heat-shielding properties can be imparted. On the other hand, when aluminum powder having a low refractive index is used as a pigment, the amount of the pigment needs to be suppressed because the pigment has a large light-shielding effect. It is impossible to do.

In addition, when the pigment is rutile type titanium dioxide, the titanium dioxide is relatively stable, and is not oxidized by moisture and temperature as aluminum powder, and is stable for a long period of time. It is possible to maintain the light blocking rate and the heat blocking property.

The light-shielding material obtained by the present invention has a composite structure of two or more layers in which at least one surface of a breathable nonwoven fabric is coated with a hydrophilic synthetic resin binder in which a white pigment is dispersed. The material that constitutes the product has hygroscopicity and moisture permeability, and it can suppress the rise of humidity when the temperature drops at night, the occurrence of over-humidity, and the occurrence of dew condensation. It becomes possible to suppress.

When titanium dioxide is used as a white pigment, titanium dioxide is a photo-oxidation catalyst and usually reduces the durability of the material. However, a PVA-based synthetic resin aqueous solution is used as a hydrophilic synthetic resin binder. However, by coating the pigment with a PVA-based synthetic resin film having a high gas barrier property, it is possible to prevent deterioration of material weather resistance. (Titanium dioxide generates active oxygen from oxygen by light energy (ultraviolet light and the like), and the active oxygen causes an oxidation reaction (break of molecular chain in a polymer). However, PVA has a low oxygen permeability. The generation of active oxygen can be suppressed.)

[0036]

Embodiments of the present invention will be described below.

Example 1 A PVA film having an average degree of polymerization of 1700 and a saponification degree of 99.9% was stretched 6 times at 190 ° C., and molecular orientation (stretching) was performed using a razor splitter.
After giving a fine slit of 1mm width in the direction,
Heat treatment was performed at 05 ° C. for 30 seconds to wind a stable uniaxially stretched and non-fibrillated PVA heat-treated film. Next, as a stretched film that has not been widened by slitting, a stretched film that has been doubled in width is taken as a weft, and PVA having an average degree of polymerization of 1400 and a saponification degree of 99.9%
After applying 5% aqueous solution by roll coater method,
Laminations were laminated and bonded so that the stretching directions were almost perpendicular to each other to obtain a split-fiber nonwoven fabric.

Next, the average degree of polymerization was 1400 and the degree of saponification was 99.
9% PVA 9% aqueous solution (solid content 11%), a binder in which 10 parts by weight of a rutile type titanium dioxide pigment is dispersed is coated on the surface of the split fiber nonwoven fabric by a dipping method,
The dried split-fiber nonwoven fabric obtained by drying is subjected to a crimping process so that it shrinks by about 10% in the length direction, and a light shielding ratio of 50%
Was obtained (product 1 of the present invention). FIG. 1 shows the product 1 of the present invention.
FIG.

Comparative Example 1 In the same manner as in Example 1,
Using a binder in which 3 parts by weight of aluminum powder was dispersed instead of titanium oxide, a light-shielding material having a light-shielding rate of 50% (Comparative Product 1) was obtained.

FIG. 2 shows the light-shielding materials of Example 1 and Comparative Example 1 obtained as described above, which are 20 cm above the ground when the product 1 of the present invention and the comparative product 1 are used as tunnel materials.
Shows the measurement results of the temperature transition at.

From the results shown in FIG. 2, it can be seen that the heat shielding effect of Example 1 is higher than that of Comparative Example 1. The growth of a crop is determined by the integrated temperature, and a temperature drop of 1 to 2 ° C during the day expresses a great effect. Further, since the product 1 of the present invention has a lower light blocking ratio than the comparative product 1, it can be understood that a large amount of light is transmitted into the coating system and the heat shielding property is excellent.

Next, Table 1 shows the measurement results of the ratio of scattered light transmitted through the product 1 of the present invention and the comparative product 1. The scattered light ratio was measured by the following measurement method. Diameter 20cm, height 20
The inner wall of the cm cylinder was painted black, and one end was attached to a black plate on which the sensor part of the illuminometer was mounted, to prepare a jig for direct light measurement. The positional relationship with the light source was adjusted so that the incident light directly hit the sensor portion, and the sample was mounted on the other end (opening). Thereby, the scattered light transmitted through the sample is absorbed by the inner wall surface of the cylinder, and the direct light is measured by the sensor (transmitted light 1). Next, using the same sample, the sensor of the illuminometer was directly covered without using a jig, and the direct light and the scattered light were measured simultaneously (transmitted light 2). Light source is sunlight, the brightness was 90000L _X.

Therefore, the scattered light ratio is calculated by the following equation. [Scattered light ratio] = ([light transmittance 2]-[transmitted light 1]) /
[Transmitted light 2]

[0044]

[Table 1]

From the results shown in Table 1, the product of the present invention is comparative product 1
Because the ratio of scattered light is higher than that of the present invention, the product of the present invention is rich in scattered light, it is difficult to cast shadows in the coating system, and it is possible to more uniformly irradiate crops in the coating system with sunlight. I understood.

[0046]

As described above in detail, the light-shielding material obtained by the present invention has a sufficiently low light-shielding ratio as compared with a conventionally used light-shielding material using aluminum or a black light-shielding material such as carbon black. It has heat-shielding properties, is rich in scattered light, and has high moisture absorption and moisture permeability, so it is possible to control diseases such as gray mold disease. It is useful.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view of a light shielding material according to an embodiment of the present invention.

FIG. 2 is a temperature measurement graph for comparing the heat shielding properties of a light shielding material.

FIG. 3 is an explanatory diagram of a method for measuring a light transmittance of 1;

FIG. 4 is an explanatory diagram of a method for measuring a light transmittance 2;

[Brief description of reference numerals]

 DESCRIPTION OF SYMBOLS 1 Lateral stretching 2 Longitudinal stretching 3 Titanium oxide containing white film 21 Light source 22 Sample 23 Cylinder whose inner wall was painted black 24 Sensor light receiving unit 31 Light source 32 Sample 33 Sensor light receiving unit

Claims (7)

[Claims] 1. A light-shielding material obtained by coating at least one surface of a non-woven fabric made of synthetic resin fibers with a synthetic resin binder in which a white pigment having a high refractive index is dispersed and drying. 2. A synthetic resin film is stretched, split,
At least one surface of a split fiber nonwoven fabric obtained by laminating and bonding a plurality of webs obtained by heat treatment so that the stretching direction is perpendicular to the process is coated with a synthetic resin binder in which a white pigment having a high refractive index is dispersed. Light-shielding material obtained by drying. 3. The light-shielding material according to claim 2, wherein said synthetic resin film is a hydrophilic synthetic resin film. 4. The light-shielding material according to claim 3, wherein the hydrophilic synthetic resin film is a polyvinyl alcohol-based synthetic resin film. 5. The light-shielding material according to claim 1, wherein said white pigment is rutile type titanium dioxide. 6. The light-shielding material according to claim 1, wherein the synthetic resin binder is a hydrophilic synthetic resin aqueous solution. 7. The method according to claim 1, wherein the synthetic resin binder is an aqueous solution of a polyvinyl alcohol-based synthetic resin.
4. The light-shielding material according to 4, 5, or 6.