JPH11196678A - Covering material for agriculture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a covering material for agriculture having both of light transmissivity and heat-retaining property, excellent in dimensional stability, workability and strength and having long useful life by arranging monoaxially drawn lines comprising a raw material consisting mainly of high-density polyethylene. SOLUTION: This raw material is obtained by arranging monoaxially drawn lines 8 comprising a raw material obtained by compounding a high density polyethylene with a linear polyethylene, a heat insulating material and a polyolefin in which at least one terminal is modified with an acid in at least either one direction of longitudinal and latitudinal directions. In the covering raw material obtained by longitudinally and latitudinally arranging multilayer monoaxially drawn lines 3 obtained by attaching an outer layer 2 of a thermoplastic synthetic resin having lower melting point than that of a core material 1 to the surface of the core material 1 which is monoaxially drawn line of a thermoplastic synthetic resin in which high density polyethylene is compounded and melting crossing parts 4 of multilayer monoaxially drawn lines 3, a heat insulating material, a linear polyethylene and a polyolefin in which at least partial terminal is modified with an acid can be compounded in at least either one of the core material 1 and the outer layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a covering material for agricultural use to be sewn on vegetables, fruit trees, or the like, or to be laid on a tunnel house, an agricultural house, or the like.

[0002]

2. Description of the Related Art In recent years, in order to increase the added value of agricultural products, facility cultivation using solid hanging, tunnel houses, agricultural houses, and the like has been actively performed. In some regions, the temperature of the atmosphere and the soil temperature in the cultivation facility significantly decrease during the low temperature period from winter to early spring. Often causes harm. From such a background,
Even in the field of coating materials, polyvinyl chloride film,
Many materials having excellent light transmittance or heat retention, such as a split-fiber nonwoven fabric made of a stretched and split polyvinyl alcohol-based web, have been developed.

[0003]

However, as the polyvinyl chloride film is used, the plasticizer contained in the film bleeds to the surface, and furthermore, the light transmittance is reduced due to the adhesion of dust and the like. In order to do so, during the day, there is a problem that it is not possible to supply sufficient sunlight to the crops and the ground in the cultivation facility, while the split-fiber nonwoven fabric made of polyvinyl alcohol is easily swelled due to high hygroscopicity, As a result, there is a problem that the tensile strength is reduced, and that the resin expands and contracts in response to moisture absorption and drying, resulting in poor dimensional stability. Also, simply adding a heat insulating agent to enhance the heat insulating effect, the light transmission becomes poor due to the generation of voids due to the stretching process,
There is also a problem that it is not suitable for applications where both high heat retention and good sunshine are desired.

[0004] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an agricultural covering material having both light transmittance and heat retention, and further provides dimensional stability and workability. It is an object of the present invention to provide a long-life agricultural covering material having excellent properties and strength and, in some cases, excellent air permeability.

[0005]

The agricultural covering material according to the present invention, which has been made to solve the above-mentioned problems, comprises a high-density polyethylene, a linear polyethylene, a heat insulator, and a polyolefin having at least a part of a terminal acid-modified. Characterized in that it is constituted as a woven or non-woven fabric in which a uniaxially stretched strip made of a material blended is arranged in at least one of the vertical and horizontal directions.
On the surface of a core material, which is a uniaxially stretched thermoplastic synthetic resin blended with high-density polyethylene, a multilayer uniaxially stretched strip formed by applying an outer layer of a thermoplastic synthetic resin having a lower melting point than the core material vertically and horizontally. Agricultural covering material arranged as a woven or non-woven fabric formed by fusing the intersections of the multilayer uniaxially stretched strips, wherein at least one of the core material and the outer layer has a heat insulating agent, linear polyethylene and at least A coating material for agricultural use which is characterized by blending a polyolefin partially modified with an acid may be used. Further, in these agricultural covering materials, the uniaxially stretched strips arranged vertically and horizontally may be separated from each other to form ventilation holes, and a light-transmitting surface layer film may be formed on at least one of the front and back surfaces. good. The uniaxially drawn strip may be a flat yarn called flat yarn, or may be a monofilament having a circular or elliptical cross section or a continuous thread thereof. Further, as a mode of the multilayer uniaxially stretched strip, there may be a case where an outer layer is applied only to a flat portion or a portion close to the flat portion of the monoaxially stretched strip as the core material to form a so-called multilayer, or over the entire surface of the core material. In some cases, the core material and the outer layer may be formed in a multilayer structure such that the core material and the outer layer are positioned concentrically.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an agricultural covering material according to the present invention will be described below with reference to the drawings. (B) of FIG.
The coating materials for agricultural use shown in (e) to (e) are formed on both surfaces of a core material 1 which is a stretched tape (uniaxially stretched strip) of a thermoplastic synthetic resin mainly composed of high-density polyethylene. A multi-layer uniaxially stretched strip 3 (hereinafter referred to as a multi-layer flat yarn 3) formed by applying an outer layer 2 of a plastic synthetic resin is arranged lengthwise and crosswise, and an intersection 4 between the multi-layer flat yarns 3 is fused. A coating material for agricultural use comprising at least one of the core material 1 and the outer layer 2, a hydrotalcite compound and a linear polyethylene as a heat insulating agent, and a polyolefin having at least a part of a terminal acid-modified. Things. In each of the figures, the outer layer 2 of each multilayer flat yarn 3 is shown in a state of being integrated with the outer layer 2 of another adjacent multilayer flat yarn 3 by fusion.

The thermoplastic synthetic resin used as the material of the stretched tape as the core material 1 is a mixture of high-density polyethylene and linear polyethylene. The blending ratio of the linear polyethylene is preferably in the range of about 5 to 30% by weight, and if it is less than 5%, a remarkable effect due to the addition of the linear polyethylene cannot be obtained. Although it is possible to obtain the core material 1 having excellent permeability and heat retention, it is highly likely that the core material 1 will be extremely weak in strength depending on the blending amount of other materials (such as a heat insulating agent).

As high-density polyethylene, density (JI
SK7112, omitted hereafter): about 0.942 to 0.96
0 g / cubic centimeter, melting point (melting end temperature by DSC method, hereinafter omitted): about 130 to 140 ° C., melt flow rate (JIS K7210, hereinafter omitted): 0.3
２．０2.0 g / 10 minutes, and a linear polyethylene having a density (JIS K7112,
(Abbreviated below): about 0.890 to 0.930 g / cubic centimeter, melt flow rate (JISK721)
0, hereinafter omitted): An ethylene / α-olefin copolymer satisfying the condition of 0.3 to 10.0 g / 10 minutes is selected.

When the density of the linear polyethylene is less than the lower limit of the suitable range (0.890 g / cubic centimeter), the multilayer flat yarn 3 obtained by adding the linear polyethylene is used.
Is significantly reduced, and the upper limit of the suitability range (0.930 g
/ Cubic centimeter), the dispersion of the hydrotalcite compounds added to impart appropriate heat retention to the agricultural covering material using the multilayer flat yarn 3 becomes poor, and voids due to stretching are also generated. Become noticeable,
It is difficult to satisfy both light transmittance and heat retention. The melt flow rate is at the lower limit of the above-mentioned suitable range (0.3 g / 1
If the melt flow rate exceeds the upper limit (10.0 g / 10 minutes) of the melt flow rate, the unevenness appears during the extrusion of the core material 1 and the light transmittance does not improve. The strength of the layer flat yarn 3 is significantly reduced. The most preferred density range is 0.895-0.
928 g / cubic centimeter, and the most preferred range of melt flow rate is 0.5-6.0 g / 10 minutes.

The thermoplastic resin used as the material of the outer layer 2 includes low density polyethylene, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / ethyl acrylate copolymer, ionomer, linear low density It may be selected from polyethylene or the like, but low-density polyethylene or linear low-density polyethylene is desirable in view of workability and cost.

The low-density polyethylene or linear low-density polyethylene used for the outer layer 2 has a density of about 0.900.
0.930 g / cubic centimeter, melting point: about 90-
120 ° C., melt flow rate: 0.3 to 10.0 g /
Select from those satisfying the conditions of 10 minutes.

The core 1 serves to secure the strength of the multilayer flat yarn 3, that is, to ensure the durability of the agricultural covering material. The outer layer 2 has a base material 6 of the covering material. It functions as a sealant material for fusing and fixing the intersections 4 of the multilayer flat yarns 3 running vertically and horizontally. The above items show some of the conditions suitable for each role, and the materials described may be mixed to such an extent that the required physical properties are not impaired. The melting point of the thermoplastic synthetic resin constituting the outer layer 2 is desirably about 10 ° C. or lower than the melting point of the material constituting the core 1, but the outer layer 2 made of the same material is not necessarily formed on both sides of the core 1. do not have to.

The hydrotalcite compound to be mixed with at least one of the core material 1 and the outer layer 2 of the multilayer flat yarn 3 corresponds to the chemical formula of Chemical Formula 1, and the n-valent anion is listed in Chemical Formula 2. Specific examples of the hydrotalcite compound are listed in Chemical formula 3.

[0014]

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[0015]

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[0016]

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It is desirable that the above-mentioned hydrotalcite compound is added to the core material 1 and the outer layer 2 in an amount of 5 to 20% by weight. good. When adding to both the core material 1 and the outer layer 2 as described above, the amount added to the outer layer 2 is smaller than the amount added to the core material 1.

Similarly, at least a part of the polyolefin (hereinafter, referred to as acid-modified PO), which is mixed with the main material of the multilayer flat yarn 3 and whose terminal is at least partially acid-modified, has a property of increasing the adhesion of a material which is difficult to mix, and is used for stretching. The formation of voids due to the accompanying addition of the hydrotalcite compound is suppressed, and the mixing ratio of the multilayer flat yarn 3 to the material is preferably about 5 to 20% by weight.

The acid-modified PO can be synthesized by chemically adding at least one of an unsaturated carboxylic acid and an anhydride thereof to the polyolefin having a terminal double bond. Desirable acid-modified PO has a softening point of 90 to 170.
C. and about 5 to 80 mg KOH / g, and a polyolefin having a desirable terminal double bond has a terminal double bond of 1 to 10 per 1,000 carbon atoms, and a number average molecular weight of Those in the range of 800 to 20,000 are mentioned. If the terminal double bond is below the lower limit, the desired acid modification cannot be carried out. If the terminal double bond exceeds the upper limit, the heat resistance of the acid-modified PO is undesirably reduced. On the other hand, when the number average molecular weight is below the lower limit, the strength of the flat yarn is lowered and the processability is deteriorated. On the other hand, when the number average molecular weight is higher than the upper limit, sufficient acid modification cannot be performed.

Examples of the acid modifier used include unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, fumaric acid, and itaconic acid, or maleic anhydride, itaconic anhydride, citraconic anhydride, allylsuccinic anhydride, It is desirable to contain at least one of unsaturated carboxylic acid anhydrides such as nadic anhydride in an amount of about 0.1 to 12% by weight, but these directly acid-modified products may be appropriately diluted with unmodified products before use. .

Although the addition of the hydrotalcite compound enhances the heat retention as described above, the generation of voids becomes remarkable as the blending amount increases, and the light transmittance tends to decrease. In particular, the tendency becomes stronger as the core material 1 becomes thicker. However, as described above, the generation of voids can be suppressed by adding the acid-modified PO. Therefore, by appropriately adjusting the amounts of these components according to the application, it is possible to impart the optimal heat-retaining effect and light transmittance for the application to the agricultural covering material.
Furthermore, by blending linear polyethylene of an appropriate density into the material of the core material 1 and the outer layer 2, the multilayer flat yarn 3
Without lowering the strength, the heat insulation of the agricultural covering material using the multilayer flat yarn 3 can be further improved.

The material containing the above-mentioned materials can be prepared by using a known kneading machine by using an existing dispersant, heat stabilizer, light stabilizer, ultraviolet absorber, lubricant, antifogging agent, antistatic agent, antibacterial agent, coloring agent. It may be prepared by kneading together with the above, or a high-concentration so-called master batch may be prepared and diluted for use.

When the multi-layer flat yarn 3 is formed using the above-mentioned material, the high-density polyethylene and the linear polyethylene, or the low-density polyethylene and the linear low-density polyethylene may be used for the core material 1 or the outer layer 2. Hydrotalcite compounds and acid-modified P
A material obtained by appropriately blending O with a three-layer round die or a three-layer T
1. Extruded into a film shape by two extruders equipped with a die, cooled and solidified, cut into a tape shape, for example, in a take-off direction using a hot air circulation oven, a hot roll, a hot plate, or the like. The film is stretched 5 to 8.0 times, and further subjected to a relaxation heat treatment of 0 to 15% at 80 to 160 ° C using a hot air circulation oven or the like.

The material temperature at the time of extrusion is about 200 to 280 ° C., the thickness after cooling and solidification is about 30 to 130 μm, and the tape-shaped cutting width is about 1 to 20 mm. The flat yarn has a denier of 50 to 2,000, a yarn width of 0.3 to 6.0 mm, and a thickness of 1
5 to 80 μm, thickness composition ratio of outer layer: core material: outer layer = 5: 9
0: 5 to 25:50:25. The thickness of the outer layer 2 may be different between the front and back sides of the stretched tape as the core material 1, and sometimes the core material 1 and the outer layer 2 may have a multilayer structure.

As a means for forming the film before cutting into a flat yarn into a multilayer structure, a film as the core material 1 and a film as the outer layer 2 are formed in advance, and a dry laminating method or a heat laminating method is used. Any means can be appropriately selected and used from known means such as a means for forming a multilayer by extrusion, a means for extruding and laminating the outer layer 2 on a film to be a core material 1 formed in advance, and a means for extruding and forming a laminated film by a multilayer coextrusion method. Although good, the multilayer co-extrusion method is superior in terms of ease of molding and cost, as well as adhesion and light transmittance between layers of the product.

The base cloth 6 of the agricultural covering material is usually about 4
It is formed as a woven fabric on which a plain weave or twill weave is applied at a width of up to 25 yarns / inch, and for example, a nonwoven fabric formed by laminating and stacking the multilayer flat yarns 3 produced as described above horizontally and vertically, It may be formed as a split-fiber nonwoven fabric obtained by widening and laminating a wide web subjected to split processing.
Then, according to the specification, the intersection of the warp and the weft is adhered by a heating roll, a hot plate or the like, and the intersection 4 is fixed (the temperature at the time of adhesion is the denier of the flat yarn, the wall thickness, the outer layer 2). Depends on the melting point of the material selected as above, the take-up speed of the base cloth 6, etc.). Preferably, the warp and weft are orthogonal to each other, thereby increasing the convergence of the coating. Incidentally, in order to increase the strength of the base fabric 6, a single layer of flat yarn (a material obtained by mixing a hydrotalcite compound or an acid-modified PO to a main material obtained by mixing a linear polyethylene with a high-density polyethylene) may be used in at least one direction in all directions. ) Or a flat yarn 3 made of a material different from that described above may be driven in a range that does not impair the heat-sealing property of the intersection 4 between the warp and the weft and the adhesiveness between the base fabric 6 and the surface layer film 7.

A plurality of samples (hereinafter referred to as test samples) of the base material of the agricultural covering material produced through the above-mentioned means using the materials in the range described above were collected, and linear polyethylene and hydrotalcite were obtained. -Like compounds and acid-modified PO
These properties were measured and considered using the difference in the blending state of the as a parameter. Tables 1, 2 and 3 show the main compositions of the test samples and other samples, and the measurement results of the light transmittance, heat retention, tensile strength, tensile elongation, tear strength and basis weight of each sample. In order to clarify the practical effect of the agricultural covering material using the multilayer flat yarn 3 in which linear polyethylene is blended in the core material 1 and the outer layer 2, the core material 1 and the outer layer 2 of the multilayer flat yarn 3 Tables 4, 5 and 6 show the results of the same measurement performed on a base fabric not containing the polyethylene in the form of a mixture (hereinafter, referred to as a test sample). For clarification, Table 2, Table 3, Table 5 and Table 6 also show the measurement results of the polyvinyl alcohol-based nonwoven fabric and the polyvinyl chloride film.

For the test sample, as the thermoplastic resin used for the core material 1, high-density polyethylene having a melting point of 133 ° C. and a melt flow rate of 0.6 g / 10 minutes, and a melt flow rate of 2.2 g were used. And a low-density polyethylene having a melting point of 113 ° C. and a melt flow rate of 4.0 g / 10 minutes was selected as the thermoplastic resin used for the outer layer 2. A heat stabilizer and a light stabilizer were appropriately mixed together with the hydrotalcite compound and the acid-modified PO to prepare materials for the core material 1 and the outer layer 2. From those materials, an extrusion process was performed using a three-layer round die at a material temperature of about 230 ° C., and a process of drawing 7.2 times in the take-off direction at about 105 ° C. by a hot plate drawing method. After a relaxation heat treatment at a relaxation rate of 5%, 520 denier, a yarn width of 1.1 mm, a wall thickness of about 55 μm, and a wall thickness composition ratio of outer layer: core material: outer layer = 1
A multilayer flat yarn 3 having a ratio of 0:80:10 was produced and used as a sample yarn. Then, from the three-layer flat yarn serving as the raw yarn, a base fabric 6 plain-woven with the number of fibers to be driven: length / width 8 / inch width was woven, and a heat roll at about 120 ° C. was brought into contact with the base fabric 6 and arranged vertically and horizontally. The intersection 4 of the three-layer flat yarn was heat-sealed to obtain an agricultural coating material (base fabric) sample. Incidentally, in the above-mentioned test sample, linear polyethylene was not blended in the core material 1 and the outer layer 2, and the draw ratio in the take-off direction was 6.5 times, the relaxation rate was 8%, and the yarn width was 1. 5
mm, a thickness: about 40 μm, and a multilayer flat yarn 3 having a thickness ratio of outer layer: core material: outer layer = 15: 70: 15.

[0029]

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In order to obtain the light transmittance, the illuminance of the sunlight (I0) under uncovered light was measured by an illuminometer.
At the same time, the illuminance (I1) due to sunlight when the sample was individually interposed 50 cm above the illuminometer was measured and calculated by the following equation. Light transmittance (%) = I1 / I0 × 100 Regarding the change with time of light transmittance, each sample was actually disposed by a tunnel coating method, and measured by the above method at predetermined intervals.

The heat retention shown in Table 3 was obtained by installing agricultural tunnels each having a frontage of about 1.0 m, a height of 0.8 m, and a length of about 3 m using each sample including a test sample.
The air temperature inside and outside each agricultural tunnel is continuously measured from January to May at a position 15 cm above the ground, and the lowest value of the measured air temperature inside each agricultural tunnel is displayed. Incidentally, the outside air temperature on that day was -0.5 ° C.
On the other hand, the heat retention shown in Table 6 was about 1.0 m in frontage and 0.1 mm in height using each sample including the already tested samples.
An agricultural tunnel with a length of about 8 m and a length of about 3 m will be installed, and the temperature inside and outside the agricultural tunnel will be 12 cm at a position 15 cm above the ground.
The measurement is continuously performed from the month to February of the following year, and the lowest value of the measured temperature inside each agricultural tunnel is displayed. Incidentally, the outside air temperature on that day was -1.0 ° C. The tensile strength, tear strength, tensile elongation, and basis weight (weight per unit area) are as specified in JIS L-109.
6 and is an average of measured values in the vertical and horizontal directions of the base fabric 6.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

[Table 4]

[0036]

[Table 5]

[0037]

[Table 6]

Table 1 shows the blended state of high-density polyethylene, linear polyethylene, hydrotalcite compounds and acid-modified PO in each sample including the test sample, and Table 4 shows the test samples. FIG. 3 shows the compounding state of high-density polyethylene, hydrotalcite compounds, and acid-modified PO in each of the first and second samples. In Table 4, in the column of outer layer, a or b
Is a sample in which a hydrotalcite compound and an acid-modified PO are blended not only in the core material 1 but also in the outer layer 2, and the acid-modified PO is the same as the core material 1 in both a and b. Is compounded, and the compounding ratio of the hydrotalcite compound is 9.0 wt% in a,
In the case of b, the content was 4.8% by weight.

From the viewpoint of heat retention, it can be seen that a relatively large difference occurs in the minimum temperature in the tunnel depending on whether or not the core material 1 contains a predetermined amount of linear polyethylene. In addition, the numerical value is larger than that of the test samples listed in Table 1 as compared with the test sample (see Table 4) containing more hydrotalcite-type compounds as the heat retaining agent (see Table 3). (Compare with Table 6). However, there is no difference in the value of the light transmittance that may be the basis for such a difference in the heat retention. In addition, when comparing Sample 7 with Sample 8, Sample 14, Sample 20, Sample 23 and Sample 26 in Table 1, even if the amount corresponding to the linear polyethylene was replaced with the acid-modified PO and blended, the linear polyethylene was contained. It turns out that the heat retention which deserves to be performed cannot be obtained. In view of such phenomena, agricultural covering materials using flat yarns formed by blending linear polyethylene with high-density polyethylene, hydrotalcite compounds and acid-modified PO have a kind of unique heat retaining effect. It is considered something.

In order to obtain an indication of the blending amount of the linear polyethylene, the sample 11 in Table 1 which is remarkably inferior in heat retention to other samples containing the linear polyethylene is used as a reference. That is, at least 5% by weight is necessary to obtain an extremely high heat retaining property by blending the linear polypropylene. In addition, in order to obtain a desired standard of linear polyethylene density to be used, the sample 26 in Table 1 is used as a reference. That is, even if linear polyethylene having an excessively high density (the sample has a density of 0.932 g / cubic centimeter) is used, high heat retention cannot be obtained.

As described above, when it is necessary to satisfy the heat retaining property and to further have the strength, the mixing ratio of each of the above materials becomes important. In order to ensure that the tensile strength is not significantly inferior to that of the test sample, it is desirable to secure the blending amount of high-density polyethylene at least about 60% by weight. Depends on the density of the linear polyethylene. That is, if the density of the linear polyethylene is high, the amount of the high-density polyethylene can maintain at least a constant tensile strength, but if the density of the linear polyethylene is low, a certain amount is not set unless the amount of the high-density polyethylene is high. Tensile strength cannot be maintained.

In Tables 1 to 3, the characteristics of the samples having inferior heat retention were as follows: a sample having a small amount of linear polyethylene added (sample 11); a sample having only a large amount of a hydrotalcite compound (sample 16); A linear polyethylene having a high density (sample 26) is exemplified. In view of the method of measuring heat retention, this data
It does not show only the heat retention, but also includes a light-transmitting element in that the amount of light received by the soil inside the tunnel during the daytime also has a considerable effect. That is, the balance between the heat retention properties of the hydrotalcite compounds and the acid-modified PO and the void suppression effect imparted by the addition of linear polyethylene having a density of about 0.886 to 0.930 g / cubic centimeter is good and high. It can be said that the sample to which the light transmittance is given gives a preferable result in the item of the heat retention. Although not listed in the table, an attempt was made to suppress the generation of voids solely with linear polyethylene without blending the acid-modified PO, but any sample tends to be turbid. The addition of acid-modified PO to the uniaxially stretched strip constituting the agricultural covering material according to the present invention is considered to be indispensable.

Although the addition of the hydrotalcite compound enhances the heat retention as described above, the generation of voids becomes remarkable with an increase in the compounding amount, and the light transmittance tends to decrease. In the production, the mixing ratio of the hydrotalcite compound, the acid-modified PO and the linear polyethylene must be appropriately adjusted depending on the application while taking this into consideration. The thermoplastic synthetic resin to which the hydrotalcite compound is added tends to absorb moisture (water), and the use of a moisture-absorbing material causes a foaming phenomenon due to evaporation of moisture in the extrusion process. Therefore, the use of a dried material during extrusion processing suppresses unintentional foaming, in other words, increases the certainty of controlling the light transmittance by adjusting the blending amounts of the heat insulator and the acid-modified PO, As a result, a flat yarn excellent in appearance can be obtained. As a means for adjusting the light transmittance, there is also a means of applying light coloring to the multilayer flat yarn within a range that does not impair the physical properties, providing fine streaky irregularities continuous in the longitudinal direction, and applying a fine split processing. No.

In the embodiment, the agricultural covering material having the above-described structure is used as the base fabric 6, and at least one of the front and back surfaces thereof is provided.
In some cases, the light-transmitting surface layer 7 is formed by a laminating method or the like. As the resin composition for the surface layer film 7, a polyethylene resin having a density of not less than 0.910 g / cubic centimeter and not more than 0.945 g / cubic centimeter can be basically used, but the abrasion resistance is enhanced or the extrudability is improved. From the viewpoint of stabilization, a density of 0.928 g / cubic centimeter to 0.942 g / cubic centimeter is desirable. Melt flow rate is 4-20g /
10 minutes is desirable.

The surface layer 7 made of a polyethylene resin composition having a density of less than 0.910 g / cm 3 has poor abrasion resistance and slipperiness, so that the sheet surface is easily scratched and causes a decrease in light transmittance. In the winding and lowering operations, the workability is deteriorated due to poor slipperiness of the sheet surface. On the other hand, when the density of the raw material resin exceeds 0.945 g / cubic centimeter, problems such as an increase in extrusion load and deterioration in workability, and an increase in sheet stiffness and deterioration in workability arise.
Thus, by setting the density range as described above, it becomes possible to form an agricultural covering material having both light transmittance continuity, abrasion resistance and workability. The thickness of the surface layer film is 15 to 80, which balances rigidity and workability.
The range of μm is desirable.

In the above-described embodiment, an example in which the base fabric 6 is formed by the multilayer flat yarn 3 has been described. However, if the mixing ratio of the heat insulating agent and the acid-modified PO is well-balanced, FIG. The base cloth 6 is made of a single-layer uniaxially stretched strip 8 made of a thermoplastic synthetic resin as shown in FIG.
In the production method, there is no significant difference from the case of using the multilayer flat yarn 3 except that a single-layer die is used and the intersection is not fused after weaving. In addition, the material of the heat insulator is not limited to the hydrotalcite compounds, but may be an aluminum / lithium composite hydroxide salt.

Further, even if the flat yarns arranged vertically and horizontally are separated from each other and the ventilation holes are formed, it is possible to satisfy both the air permeability and the heat retaining effect by blending the heat retaining agent into the material of the flat yarns. it can. In other words, the coating material containing the heat insulating agent, although air enters and exits through the air holes, can prevent electromagnetic waves (those having a wavelength in the infrared region) due to terrestrial radiation from being emitted outside the house. The worst-case situation where the surface and the air in contact with it cools and freezes can be reliably prevented.

[0048]

As described above, when the agricultural covering material according to the present invention is used, excellent light transmittance and heat retention are stable for a long period of time, and for example, suitable cultivation of agricultural crops such as soft vegetables is possible. Becomes Moreover, it has high practicality, such as a long service life due to high strength and durability, and high dimensional stability and light weight, so that the workability of stretching is extremely good. Furthermore, if the surface layer is formed, the surface becomes smooth and the light transmittance can be increased, and if the surface layer having high wear resistance is formed, the predetermined light transmittance can be stably maintained for a longer period of time. Can be kept. In addition, according to the agricultural covering material, which is formed by separating the multi-layered flat yarns arranged vertically and horizontally from each other and forming an air hole, an important air permeability imparting to crop cultivation, an excessive temperature rise and an effect of preventing stuffiness are added, While the growing condition of the crop is enhanced, it is possible to prevent the occurrence of diseases and the invasion of pests, and to contribute to the improvement of convergence and workability in addition to weight reduction.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a coating material according to the present invention (a) (b) (c) (d) (e).

FIGS. 2A and 2B are plan views showing examples of a base fabric of a covering material according to the present invention.

[Explanation of symbols]

 1,8 Core material 2 Outer layer 3 Flat yarn 4 Intersection 5 Vent hole 6 Base cloth 7 Surface film

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mikio Maruyama 2000 Kutsukake, Kurobe City, Toyama Prefecture Inside of Diatex Corporation Kurobe Plant

Claims (4)

[Claims] An uniaxially stretched strip (8) comprising a material obtained by mixing a linear polyethylene, a heat insulating agent and a polyolefin having at least a part of a terminal acid-modified with high-density polyethylene.
Agricultural covering materials, wherein at least one of the length and width is arranged. 2. An outer layer (2) of a thermoplastic synthetic resin having a melting point lower than that of the core material (1) on a surface of a core material (1), which is a uniaxially stretched strip of a thermoplastic synthetic resin containing high-density polyethylene. A coating material for agricultural use which is obtained by arranging a multi-layered uniaxially stretched strip (3) vertically and horizontally, and fusing the intersections (4) between the layers. A coating material for agricultural use, characterized in that at least one of (1) and the outer layer (2) is blended with a heat insulating agent, linear polyethylene and at least a partially terminally acid-modified polyolefin. 3. The agricultural covering material according to claim 1, wherein the uniaxially stretched strips (8, 3) arranged vertically and horizontally are separated from each other to form a ventilation hole (5). 4. An agricultural use, characterized in that a light-transmitting surface layer (7) is formed on at least one surface of a base cloth (6) comprising the agricultural covering material according to claim 1 or 2. Coating materials.