JP4100600B2 - Agricultural coating - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an agricultural covering material characterized by comprising a woven fabric obtained by splitting a laminate obtained by bonding two or more polyvinyl alcohol resin biaxially stretched films into a flat yarn .
[0002]
[Prior art]
Conventionally, polyvinyl chloride films, polyethylene films, ethylene-vinyl acetate copolymers, etc. have been widely used as agricultural coating materials because of their price advantages. Polyvinyl alcohol-based resin films, especially biaxially stretched films, are also available. Application is being tried in many fields because of its excellent ultraviolet ray blocking property.
[0003]
Such a polyvinyl alcohol-based resin film has excellent heat retention in the house at night, but has a drawback in that it prevents strong solar heat during the daytime and prevents excessive temperature rise in the house. In many cases, it is used as a laminate in which a film of a hydrophobic resin, a woven fabric, a non-woven fabric or the like is bonded with a polyurethane adhesive. Such techniques are disclosed in JP-A-56-67251, JP-A-62-282931, JP-A-63-319148, and the like.
However, such laminates still have problems with anti-fogging properties and shrinkage stability. For example, Japanese Patent Publication No. 57-135167 has been devised to laminate a uniaxially stretched polyvinyl alcohol-based resin film so that the orientation axes intersect. Yes.
[0004]
[Problems to be solved by the invention]
However, as a result of studies by the present inventor, a known laminate using such a polyvinyl alcohol-based resin film has low productivity, and in particular, if it is subjected to a change in humidity difference between daytime and nighttime over a long period of time, it is insufficient in flexibility. It has become clear that there are problems such as the occurrence of cracks due to.
[0005]
[Means for solving problems]
However, the present inventors have result of intensive studies on such problems, and a flat yarn to Wari繊a laminated body formed by bonding a port polyvinyl alcohol resins biaxially oriented film two or more, and weaving this fabric It has been found that an agricultural covering material comprising the above-mentioned drawbacks is improved, and the present invention has been completed.
That is, in the present invention, a laminate formed by laminating two or more polyvinyl alcohol resin biaxially stretched films is split into a flat yarn, and is made of a woven fabric. The remarkable effect that the splitting property at the time of production is far superior to the use of the biaxially stretched film of a single layer can be expected.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The laminate of the present invention will be specifically described below.
As the raw material of the polyvinyl alcohol resins biaxially oriented film used in the present invention, a polyvinyl alcohol, the polyvinyl alcohol is homopolymerizing vinyl acetate, it is further prepared by saponifying it.
[0007]
Among such polyvinyl alcohol resins is preferably not less than 80 mol% degree of saponification, further 90 to 100 mol%, in particular is advantageously from 99 to 100 mol%. When the saponification degree is less than 80 mol%, the water resistance is lowered.
[0008]
The viscosity of the 4% by weight aqueous solution is preferably 2.5 to 100 mPa · s (20 ° C.), more preferably 2.5 to 70 mPa · s (20 ° C.), particularly 2.5 to 60 mPa · s (20 ° C.). Is advantageous. If the viscosity is less than 2.5 mPa · s (20 ° C.), mechanical properties such as film strength may be inferior. On the other hand, if it exceeds 100 mPa · s (20 ° C.), the film-forming property on the film is deteriorated. . The viscosity is measured according to JIS K6726.
[0009]
Further according polyvinyl alcohol resins coloring preventing film, 0.8 weight% the amount of sodium acetate contained in the resin for strength reduction prevention or less, preferably it is adjusted to 0.5 wt% or less It is advantageous.
[0010]
In producing the polyvinyl alcohol resins film includes a drum, it is melt-extruded on a metal surface such as an endless belt or to form a film by casting a polyvinyl alcohol resins solution, or by an extruder.
As a stock solution for the normal film, polyvinyl alcohol resins concentration from 15 to 60 wt%, preferably 20 to 50% by weight of polyvinyl alcohol resins - preparing the composition of water.
[0011]
Also, if necessary, plasticizers of polyhydric alcohols such as ethylene glycol, glycerin, polyethylene glycol, diethylene glycol, triethylene glycol, antioxidants such as phenols and amines, stabilizers such as phosphate esters, coloring Ordinary additives such as a fragrance, a fragrance, a bulking agent, a defoaming agent, a release agent, an ultraviolet absorber, an inorganic powder, and a surfactant may be appropriately added. Also, starch, carboxymethyl cellulose, methyl cellulose, may be mixed with polyvinyl alcohol tree other water-soluble resin other than fat, such as hydroxymethyl cellulose.
[0012]
Polyvinyl alcohol resins prepared above - the composition of water or be linked to the film forming machine (extruder), or Once pelletized, Ltd. is supplied to the rear casting machine after flaking extruded film.
Incidentally, polyvinyl alcohol resins - Preparation and film-forming operation of the composition of the water can also be carried out using the same extruder but or to increase the L / D, or by using a multi-screw extruder, gear pump It is necessary to pay attention to uniform mixing and film formation stability.
[0013]
The method of forming the polyvinyl alcohol resins film is not particularly limited, was melt-kneaded by supplying the stock solution to an extruder, T-die method, and extrusion film forming by inflation method, a method of drying is preferred.
[0014]
The melt kneading temperature in the extruder is preferably 55 to 140 ° C, more preferably 55 to 130 ° C. If the temperature is less than 55 ° C, the film skin will be defective. The film after film formation is dried and commercialized.
About this drying, it is preferable to carry out at 70-110 degreeC, Preferably it is 80-100 degreeC.
[0015]
The present invention further water resistance applying polyvinyl alcohol resins film is further biaxially oriented preferably sequential biaxial stretching, flexible, imparting physical properties such as mechanical strength.
[0016]
For such stretching, the stretching ratio in the longitudinal direction is preferably 1.5 to 5.0 times, and the stretching ratio in the transverse direction is preferably 2.0 to 5.0 times, more preferably the stretching ratio in the longitudinal direction is 3. The draw ratio in the transverse direction is 3.0 to 5.0 times. If the stretching ratio in the machine direction is less than 1.5 times, it is difficult to improve physical properties by stretching, and if it exceeds 5.0 times, the film tends to tear in the machine direction. Further, if the stretching ratio in the transverse direction is less than 2.0 times, it is difficult to improve physical properties by stretching, and if it exceeds 5.0 times, the film breaks, which is not preferable.
[0017]
Such In the sequential performing biaxial stretching, the polyvinyl alcohol the water content of Le resins film 5 to 30 wt%, preferably preferably be previously adjusted to 20 to 30% by weight, before drying obtained above or adjust the moisture content of the polyvinyl alcohol resins film subsequently dried, method or adjusting the water content of the polyvinyl alcohol Ruff Ilm a moisture content of less than 5% by weight is subjected to such moisture immersion or adjusted to a water or the like There is.
[0018]
If the moisture content is less than 5% by weight, the draw ratio cannot be sufficiently increased, and if it exceeds 30% by weight, the longitudinal and transverse stretch ratios cannot be increased in the stretching step.
[0019]
Furthermore, after sequentially performing biaxial stretching, it is preferable to perform the heat, the temperature of such heat is preferably selected from a range of up to 40 ° C. lower than the melting point or melting point of the polyvinyl alcohol resins . When the temperature is lower than 40 ° C. below the melting point, the dimensional stability is poor and the shrinkage rate is increased. Heat setting temperature when polyvinyl alcohol resins are saponified vinyl acetate homopolymer, for example, 160 to 230 ° C.. The heat setting time is preferably 1 to 30 seconds, more preferably 5 to 10 seconds.
[0020]
The obtained polyvinyl alcohol resins film has a thickness 8 to 50 m, are stacked preferably 10 to 40 [mu] m.
[0021]
Agricultural covering material of the present invention (1) Polyvinyl alcohol resins biaxially oriented film of two or more bonded laminate, to obtain a flat yarn by Wari繊(2) laminate was weaving it Since there are two forms of fabric, they will be described in turn below.
(1) Polyvinyl alcohol resins biaxially bonding stretched film laminate aligned polyvinyl alcohol resins biaxially stretched film are preferably the same ones in terms of prevention of curling and the like, saponification degree optionally 4 wt% aqueous solution viscosity, the use of polyvinyl alcohol resins having different varieties such as sodium acetate content, as stretching ratio and the thickness of the film is different, etc., lamination of polyvinyl alcohol resins biaxially oriented film of a heterologous also possible is there.
[0022]
An adhesive is used during the production of the laminate of the present invention. The adhesive is not particularly limited, and examples thereof include polyurethane adhesives, particularly polyester polyurethane adhesives. The adhesive is a two-component type in which the terminal hydroxyl group of the polyester polyol obtained by the condensation reaction of dicarboxylic acid and diol is mixed with isocyanate before coating the adhesive, and one component having a terminal hydroxyl group that has been urethanized in advance. Any of the types may be used.
[0023]
In the present invention, the use of a water-based adhesive is advantageous in order to prevent the laminate from curling or causing delamination as much as possible.
As the water-based adhesive, vinyl resin emulsions such as vinyl acetate resin emulsions, acrylic resin emulsions, ethylene-vinyl acetate copolymer emulsions, and particularly those using polyvinyl alcohol as a protective colloid are suitable. The water-soluble polymer aqueous solution, in particular polyvinyl alcohol resins aqueous solution is useful. Such polyvinyl alcohol resins are the same as the raw material used in the polyvinyl alcohol resins film for laminate of the present invention described above.
That is, the saponification degree is preferably 80 mol% or more, more preferably 90 to 100 mol%, particularly 99 to 100 mol%. When the saponification degree is less than 80 mol%, the water resistance is lowered.
[0024]
The viscosity of the 4% by weight aqueous solution is preferably 2.5 to 100 mPa · s (20 ° C.), more preferably 2.5 to 70 mPa · s (20 ° C.), particularly 2.5 to 60 mPa · s (20 ° C.). Is advantageous. If the viscosity is less than 2.5 mPa · s (20 ° C.), mechanical properties such as film strength may be inferior. On the other hand, if it exceeds 100 mPa · s (20 ° C.), the viscosity becomes too high and the coating operation becomes difficult. .
Aqueous solution of an alkali metal or alkaline earth metal Other water-based adhesive, such as lithium chloride, sodium chloride, calcium chloride, include aqueous solutions of magnesium chloride, and, using this alone or in combination with polyvinyl alcohol resins Is done.
[0025]
Bonded on one or all either polyvinyl alcohol resins biaxially oriented film, dipping method water-based adhesive, a coating method, after coating with the known means of spraying or the like, if bonded to both dry Good.
The coating amount of the adhesive is suitably about 0.01 to 5 g / m 2 in terms of solid content.
[0026]
(2) Wari繊the laminate to obtain a flat yarn, method blown compressed air production is polyvinyl alcohol resins biaxially oriented film of the fabric flat yarn was woven it, resection, any means of friction method And the width is about 1 to 10 mm.
This is used for all or a part of the warp yarns, and is made into a cloth-like body by a well-known knitting means such as Russell weave or plain weave using fibers such as polyester, polyethylene, polypropylene, polyamide, vinylon as weft.
Of particular importance is the use of the agricultural dressings of the present invention.
[0027]
The agricultural covering material of the present invention is effective for use in heat retention, overhumidity prevention, water drop prevention, etc. in a vinyl house, and usually covers the outside of the vinyl house with polyethylene, glass, etc. Place and use as a double house (heat insulation curtain).
[0028]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples.
In the examples, “%” means weight basis unless otherwise specified.
[0029]
Reference example 1
Polyvinyl alcohol (viscosity of 4% by weight aqueous solution 40 mPa · s, saponification degree 99.7 mol%) from the hopper of a twin-screw extruder type kneader (screw L / D = 40) with the jacket temperature set at 60 to 150 ° C. Sodium acetate content 0.3%, “GOHSENOL NH-17Q” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and water (polyvinyl alcohol / water weight ratio 40/60) are supplied by a metering pump, kneaded and discharged 500 kg / It discharged on the conditions of hr.
[0030]
This discharged material is immediately pumped to a single screw extruder (screw L / D = 30), kneaded at a temperature of 85 to 140 ° C., extruded from a T-die onto a 5 ° C. cast roll, and dried for 30 seconds with a 90 ° C. hot air dryer. Then, a film (A) having a water content of 25% (thickness 150 μm) was produced. Subsequently, the film (A) was stretched 4.2 times in the longitudinal direction, then stretched 4.2 times in the transverse direction with a tenter, and then heat-fixed at 220 ° C. for 8 seconds to obtain a biaxially stretched film (B) (thickness). 14 μm) was obtained.
[0031]
Next, 10% of polyvinyl alcohol (viscosity of 4% by weight aqueous solution 40 mPa · s, saponification degree 99.7 mol%, sodium acetate content 0.3%, “GOHSENOL NH-17Q” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) An aqueous solution was prepared.
The polyvinyl alcohol adhesive is applied to the biaxially stretched film (B) at a rate of 0.5 g / m 2 in terms of solid content, and is bonded to the same biaxially stretched film (B) and dried at 120 ° C. A coating material was obtained.
[0032]
The following performance was measured for the coating material, and the results are shown in Table 1.
(Prevents temperature rise in the vinyl house)
A metal frame (170mm x 70mm) provided with a daylight (light that tends to rise in temperature) at a position 150cm in height outside the vinyl house (width 80cm, height 80cm, height 100cm) and 10cm away from the roof ) And the temperature of the ground surface after 20 minutes, 40 minutes and 60 minutes at the start of irradiation was measured.
[0033]
(Deterioration prevention effect against humidity change)
The above-mentioned covering material was exposed to repeated conditions of 8 hours of rainfall and 32 hours of irradiation with a sunshine weather meter for 1000 hours, and the state of the covering material was observed. ・ Flexibility state of the covering material ○: No change in flexibility △ : The flexibility was somewhat lowered and a slight break was observed when it was rubbed by hand. ×: The flexibility was remarkably lowered and a break was easily recognized when it was rubbed by hand.
・ Coating material cracking state ○: No cracking occurred Δ: Some cracking occurred ×: Large cracking occurred ・ Area shrinking state of coating material (100 mm × 100 mm) ◎: Area shrinkage rate Less than 5% ○: Area shrinkage is 5% or more and less than 10% Δ: Area shrinkage is 10% or more
Reference Examples 2-4
In Reference Example 1, an ethylene-vinyl acetate copolymer emulsion (using polyvinyl alcohol as a protective colloid, “S-200” manufactured by Konishi Co., Ltd.) as an adhesive ( Reference Example 2), polyester / isocyanate two-part type A polyurethane adhesive ("Takelac A-3210 / Takenate A-3072 = 3/1" manufactured by Takeda Pharmaceutical Co., Ltd.) was used ( Reference Example 3), and a 30% aqueous solution of lithium chloride containing 0.5% polyvinyl alcohol was used. Except that used ( Reference Example 4 ), the same experiment as in this example was performed for evaluation. The results are shown in Table 1.
[0035]
Reference Example 5
The biaxially stretched film (B) used in Reference Example 1 is a polyvinyl vinyl alcohol having a 4 wt% aqueous solution viscosity of 40 mPa · s, a saponification degree of 99.7 mol%, and a sodium acetate content of 0.5% (Japan) Synthetic chemical industry "Gosenol N-300") The same experiment as the same example was performed except for changing to a biaxially stretched film. The results are shown in Table 1.
[0036]
Reference Example 6
Instead of the biaxially oriented film used in Example 1 (B), longitudinally 3.5 times the draw ratio of the biaxially stretched polyvinyl alcohol resins film in which the draw ratio in the transverse direction to 4.2 times The same experiment as in this example was performed except that it was used. The results are shown in Table 1.
[0037]
Reference Example 7
Instead of the biaxially oriented film used in Example 1 (B), except for using the polyvinyl alcohol resins film with glycerin is contained 15% (A) was subjected to the same experiment as the example. The results are shown in Table 1.
[0038]
Examples 1-3
The laminate of the biaxially stretched film (B) used in Reference Example 1 and the laminates of Reference Examples 5 and 6 were divided in the longitudinal direction to produce a flat yarn having a width of 7 mm, and this and a polyethylene monofilament Alternating warp yarns were used, and weft yarns were woven using polyethylene monofilaments.
The same evaluation as the same example was performed. The results are shown in Table 1.
[0039]
Comparative Example 1
Reference Example 1, the polyvinyl alcohol resins film of (A) except that bonded orthogonally to those stretched 6.0 times in a uniaxial were subjected to the same experiment as the example. The results are shown in Table 1.
[0040]
[Table 1]
Ground surface temperature change (℃) degradation prevention
At the start 20 minutes later 40 minutes later 60 minutes later Flexible crack Shrinkage situation
Reference Example 1 20 23 25 27 ○ ○ ○
Reference Example 2 20 23 24 27 ○ ○ ○
Reference Example 3 19 22 24 26 ○ ○ ○
Reference Example 4 20 23 25 27 ○ ○ ○
Reference Example 5 21 23 25 27 ○ ○ ○
Reference Example 6 20 24 26 27 ○ ○ ○
Reference Example 7 21 24 25 26 ○ ○ ○
Example 1 20 24 26 27 ○ ○ ◎
Example 2 19 23 25 27 ○ ○ ◎
Example 3 19 24 25 27 ○ ○ ◎
Comparative Example 1 21 24 26 27 ○ × △
[0041]
【The invention's effect】
In the present invention, a flat yarn to Wari繊a laminate comprising a port polyvinyl alcohol resins biaxially oriented film laminated two or more, which consists of weaving the fabric agricultural dressing daytime and nighttime Even if the fluctuation of humidity difference is continued for a long period of time, it exhibits an excellent effect without cracking or shrinkage due to insufficient flexibility, and with the above effects, the splitting property when producing flat yarn is simple. The remarkable effect of being far superior to the use of the biaxially oriented film of the layer can also be expected.

Claims (3)

And Wari繊a laminate comprising polyvinyl alcohol resins biaxially oriented film of bonding two or more as the flat yarn, agricultural covering material, characterized in that it consists of fabric woven this. As the polyvinyl alcohol resins, the average saponification degree of 80 mol% or more, 4% by weight the viscosity of the aqueous solution 2.5~100mPa · s (20 ℃), those of sodium acetate content of 0.8 wt% or less The agricultural covering material according to claim 1, which is used. Longitudinal stretching ratio of the polyvinyl alcohol resins biaxially oriented film is 1.5 to 4.5 times, according to claim 1 or 2, wherein the stretching ratio in the transverse direction, characterized in that a 2 to 4.5-fold Agricultural covering material.