JP2002027842A - Polyvinyl chloride resin film for agricultural use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyvinyl chloride resin film for agricultural use exhibiting small longitudinal shrinkage after unrolling independent of the time lapsed after the manufacture and, accordingly, small longitudinal shrinkage of the film with temperature in the case of storing a laterally welded vinyl sheet in a storehouse and fully developing the function of anticlouding property, antifogging property and antiblocking property and provide a processed product of the film. SOLUTION: The polyvinyl chloride resin film for agricultural use having a shrinkage of <=3% in machine direction(MD) after unrolling is produced by heat-treating a film roll produced by calendaring or extrusion method at 35-60 deg.C for 2-48 hr. A laterally welded sheet of the film is also disclosed in the specification.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyvinyl chloride resin film for agricultural use, which has a small shrinkage in the vertical direction after being unwound from a scroll. The present invention relates to a processed product of an obtained polyvinyl chloride resin film for agriculture without wrinkles or burrs.

[0002]

2. Description of the Related Art A vinyl chloride resin film for agricultural use (hereinafter referred to as "agricultural plastic") is used for other agricultural purposes in terms of transparency, drip-proofness, heat retention, mechanical strength, durability, workability, economy and the like. It is most widely used as a coating material for agricultural houses and the like because it is superior to plastic films for agricultural use. In general, agriculture is manufactured by a calendar molding method or an extrusion molding method (T
Die method), and a calendar molding method is particularly often used.

[0003] In the case of the calender molding method, generally, a rolling step in which a vinyl chloride resin melted and kneaded in a pretreatment step is formed into a sheet by a calender roll, and the sheet is taken in a vertical (MD) direction by a take-off roll and a tenter. A winding product that is stretched in the transverse (TD) direction to form a film having a predetermined thickness and width, a widening / stretching process, a cooling process with a cooling roll, and finally, a winding process of winding around a paper tube with a winding device. Is produced. In the case of the extrusion molding method (T-die method), after the vinyl chloride resin melted and kneaded by an extruder is formed into a sheet using a T-die, the process is substantially the same as that of the calendar molding method. Is manufactured.

In the production of agricultural plastics, tension is applied to a sheet or film in the above-mentioned widening / stretching step, cooling step and winding step. Since the widening / stretching is performed in a state where the vinyl chloride resin is molten, distortion due to tension hardly remains on the film, but the tension applied after the cooling step in which the vinyl chloride resin is cooled below the glass transition temperature is applied to the film. Causes strain. Since the tension after this cooling step is applied in the vertical (MD) direction of the film, the agricultural vine after being unwound from the roll undergoes contraction in the vertical (MD) direction and expansion in the horizontal (TD) direction.

[0005] The shrinkage of agricultural vines in the vertical (MD) direction is mainly determined by conditions such as the line speed ratio between the equipment and the film temperature after the cooling step, and the line speed ratio is particularly important. Normally, cooling roll speed (V _c )
The speed ratio of the winding speed _{(V w) (V w /} V c) is controlled in 1.030 to 1.070 for the winding wrinkles prevention, the speed ratio (V _w / V _c) is As the size increases, the contraction rate in the vertical (MD) direction (hereinafter, referred to as the vertical contraction rate) also increases. If the speed ratio (V _w / V _c ) is 1.030 or less, the warp shrinkage can be reduced, but it is difficult to obtain a rolled product having a good appearance because wrinkles are liable to be generated due to the film thickness and the like. If wrinkles are contained in a roll product of agriculture (hereinafter referred to as agriculture raw material), the film strength of the wrinkled portion is weakened, the film is easily torn, and the smoothness of the appearance is impaired.

However, when agricultural rice is produced at such a speed ratio that wrinkles do not occur, the vertical shrinkage immediately after production is 5 to 10%.
%. This vertical shrinkage gradually decreases as time elapses after winding. That is, the vertical shrinkage differs depending on the elapsed time after the production of the agricultural vine, and a difference of several percent in the vertical shrinkage occurs between the agricultural virgin immediately after the production and the agricultural virgin after several months.

[0007] Generally, agricultural vines are produced only for products with a width of 5 m or less for reasons of manufacturing facilities. Therefore, they are called "vinyl processing plants" which specialize in width joining of agricultural vines using a high frequency welding machine or the like. In a factory, a wide joint is processed to a size suitable for an agricultural house, and the processed product is often shipped to farmers. The width joining process unwinds a film from a plurality of agricultural raw materials of the same type or different types and feeds out the film (hereinafter, referred to as unraveling), overlaps the edges of the film, and applies the overlapped portion with a high frequency welding machine or the like. This is welding and joining.

[0008] Usually, the crops cultivated in the house are almost the same in each area, and the time for replacing the agricultural covering material is also the same. Extreme busy periods and off periods occurred. Therefore, in recent years, in order to average the amount of work of the joint processing throughout the year at vinyl processing plants, orders have been received from farmers in advance several months in advance, and the joint processing has been performed in the off season such as winter. I have.

[0009] In this case, the processed agricultural products are stored for several months in the warehouse of the vinyl processing plant until they are shipped.
In the meantime, there is a tendency that the material contracts gradually in the vertical direction according to the magnitude of the vertical contraction rate. Especially in summer, the temperature in the warehouse becomes high, and this tendency is easily promoted by the influence of heat. As a result, if the vertical shrinkage rate is large, it will shrink below the order length due to long-term storage,
If the length of shrinkage of a plurality of agricultural raw fabrics used for width joint processing is different, when the processed product is spread on a house, wrinkles and lumps are generated at the width joint, and water droplets condensed on the film surface from the wrinkle part However, there is a problem in that the crop falls on the crop, causing a disease or the like on the crop.

[0010] The ripened agricultural vine shrinks in the vertical (MD) direction and expands in the horizontal (TD) direction. In other words, the width of the farm is widened. The expansion rate in the horizontal (TD) direction (hereinafter referred to as the horizontal expansion rate) is smaller than the vertical shrinkage rate, and the change due to the elapsed time after the production of the agricultural vine is small. The ratio tends to increase, and an extra width is produced in processed agricultural products, which is not preferable from the viewpoint of resource saving.

In general, agricultural plastics contain an antifogging agent, an antifog agent, a lubricant and the like, and these components migrate from the inside of the film to the surface, so that the antifogging property, the antifogging property and the antiblocking property are improved. Express. When raw agricultural raw material after production is stored at room temperature, since the blow-out of these components on the film surface is slow, anti-fogging, anti-fog, and anti-blocking properties are sufficient for agricultural plastic immediately after production. Was not expressed in some cases.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a vertical shrinkage ratio after resolving is small irrespective of a difference in elapsed time after production,
Therefore, even when the processed product after the vinyl width joint processing is stored in a warehouse or the like, the shrinkage of the film in the vertical direction due to temperature is small, and the anti-fog, anti-fog, and anti-blocking functions are sufficiently exhibited. It is an object to provide the processed product.

[0013]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a roll of a film produced by a calender molding method or an extrusion molding method is further subjected to a heat treatment at 35 to 60 ° C. for 2 to 2 hours.
Agricultural polyvinyl chloride resin film (agricultural plastic) having a vertical shrinkage ratio of 3% or less after demolition, obtained by heating for 48 hours, and a jointed product thereof can solve the above problem. The present invention has been completed based on this finding.

The present invention has the following configuration. (1) The roll of film produced by the calender molding method or the extrusion molding method is further subjected to 2-48 at 35-60 ° C.
An agricultural polyvinyl chloride-based resin film having a shrinkage ratio in the vertical (MD) direction after disintegration of 3% or less, which is obtained by heating for a time.

(2) A processed product of an agricultural polyvinyl chloride resin film obtained by cross-cutting the agricultural polyvinyl chloride resin film described in the above (1).

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be specifically described below. In the present invention, the polyvinyl chloride resin used for agriculture includes not only a vinyl chloride homopolymer, but also a copolymer of vinyl chloride containing more than 50% by weight of vinyl chloride with other monomers. Say. Examples of the monomer compound that can be copolymerized with vinyl chloride include vinyl acetate, ethylene, propylene, alkyl vinyl ether, acrylate, methacrylate, maleate, acrylonitrile, and vinylidene chloride. In addition to using the polyvinyl chloride resin alone,
Two or more kinds may be used in combination.

The average degree of polymerization of the polyvinyl chloride resin is not particularly limited, but is preferably from 700 to 3000, more preferably from 1100 to 1500. The average degree of polymerization is 70
When it is 0 to 3000, physical properties such as strength of the agricultural vine are good,
Agricultural production is also easy. In the present invention, it is possible to use polyvinyl chloride resins having different average polymerization degrees in combination. The polyvinyl chloride resin is an emulsion polymerization method,
Any of the conventionally known production methods such as a suspension polymerization method, a solution polymerization method, and a bulk polymerization method may be used.

A plasticizer can be blended with the polyvinyl chloride resin in order to impart flexibility to agricultural plastics. The amount of the plasticizer is not particularly limited, but is preferably 20 to 60 parts by weight based on 100 parts by weight of the polyvinyl chloride resin from the viewpoint of flexibility and strength of the agricultural plastic.

Examples of the plasticizer include phthalic acid derivatives such as di-n-octyl phthalate, di-2-ethylhexyl phthalate, dibenzyl phthalate and diisodecyl phthalate; isophthalic acid derivatives such as dioctyl phthalate; di-n-butyl Adipic acid derivatives such as adipate and dioctyl adipate; maleic acid derivatives such as di-n-butyl malate; citric acid derivatives such as tri-n-butyl citrate; itaconic acid derivatives such as monobutyl itaconate; olein such as butyl oleate Acid derivatives; ricinoleic acid derivatives such as glycerin monoricinoleate; phosphoric acid derivatives such as tricresyl phosphate; epoxidized large oils; and epoxy resin plasticizers. The plasticizers may be used alone or in combination of two or more.

Additives for imparting flexibility to agricultural plastics are not limited to the above-mentioned plasticizers, and include, for example, thermoplastic polyurethane resins, ethylene-vinyl acetate-carbon monoxide terpolymers and the like. Thermoplastic resins can also be used. These thermoplastic resins may be used alone or in combination of two or more.

In addition to the plasticizers and the like, a heat stabilizer, a lubricant (slip agent, anti-blocking agent), an anti-fog agent, an anti-fog agent, an anti-oxidant And additives such as a light stabilizer, an ultraviolet absorber, a colorant, an antistatic agent, an infrared absorber, a fungicide, and an antialgal agent. The above-mentioned various additives can be used alone or in combination of several kinds. The amounts of the various additives are not particularly limited, but are preferably in a range not deteriorating the properties of the coating material, and usually 10 parts by weight or less based on 100 parts by weight of the polyvinyl chloride resin.

Examples of the heat stabilizer include zinc stearate, calcium stearate, barium stearate, dioctyltin maleate, dioctyltin mercaptide, metal organic phosphates, organic phosphates, and β-diketone compounds.

Examples of the lubricant include paraffin, fatty acids, fatty acid esters, fatty acid amides, fatty acid metal soaps, higher alcohols such as stearyl alcohol, polyethylene wax, polypropylene wax and the like.

Examples of the antifogging agent include sorbitan fatty acid esters, glycerin fatty acid esters, and alkylene oxide adducts thereof.

Examples of the antifog include fluorine surfactants and organic siloxane surfactants containing a perfluoroalkyl group or a perfluoroalkenyl group.

Examples of the antioxidant include dilaurylthiopropionate, 2,2-methylenebis (6-t-butyl-4-ethylphenol), 2,6-di-t-butyl-4-methylphenol and the like. Can be exemplified.

As the light stabilizer, 4-acetoxy-
2,2,6,6-tetramethylpiperidine, bis (4-
Acetoxy-2,2,6,6-tetramethylpiperidyl) adipate, tri (4-acetoxy-2,2,6,6)
6-tetramethylpiperidyl) benzene-1,3,5-
Tricarboxylate and the like can be exemplified.

Examples of the ultraviolet absorber include 2-hydroxy-4-methoxybenzophenone, 2,2-dihydroxy-4,4-dimethoxybenzophenone, 2- (2-hydroxy-5-methylphenyl) benzotriazole,
2- (2-hydroxy-5-t-butylphenyl) benzotriazole and the like can be exemplified.

As the coloring agent, titanium oxide, ultramarine blue,
Examples include phthalocyanine blue, phthalocyanine green, and carbon black.

Examples of the infrared absorber include oxides and hydroxides of magnesium, calcium, aluminum and the like.
Examples thereof include silicates, carbonates and composites thereof.

In the present invention, the above-mentioned additives such as a plasticizer, an ultraviolet absorber, a light stabilizer, an organic phosphate or an organic metal phosphate are blended with a polyvinyl chloride resin to produce agriculture. As a method, the required amount of each additive is weighed, and the polyvinyl chloride resin and these additives are mixed using a high-speed mixer such as a Henschel mixer (trade name) or a super mixer (trade name) or a ribbon blender. After that, a method of kneading with a Banbury mixer, a continuous kneader or a mixing roll, and further processing the film by a calender molding method or an extrusion molding method can be mentioned.

In the present invention, the vertical shrinkage of the raw agricultural material is 3% or less when the raw material is released, and if it exceeds 3%, the processed agricultural product is stored in a warehouse of a vinyl processing plant. In addition, there is a risk of contraction under the influence of high temperatures in summer. In the case of width joint processing, if the difference in the vertical shrinkage of a plurality of films to be processed is 3% or more, wrinkles are likely to occur at the welded portion. If the vertical shrinkage of the film is uniformly 3% or less, the difference in the vertical shrinkage between the films is inevitably 3% or less. Goods can be obtained.

In the present invention, in order to uniformly reduce the lengthwise shrinkage of the raw agricultural material to 3% or less when the raw agricultural material is released, the agricultural raw material manufactured by using the calender molding method or the extrusion molding method is heated. Heating treatment is performed at a temperature of 35 to 60 ° C, preferably 40 to 50 ° C in a heating facility such as a warehouse. If the heating treatment temperature is lower than 35 ° C., the effect of reducing the shrinkage rate upon delamination is insufficient, and it is difficult to allow additives such as an antifogging agent, an antifog agent, and a lubricant to sufficiently bloom on the film surface. If the heating treatment temperature exceeds 60 ° C., discoloration and deterioration of physical properties of the agricultural vine due to thermal degradation may occur.

The time for the heating treatment varies depending on the size of the roll of the agricultural plastic to be heated, but is 2 to 48 hours, preferably 6 to 24 hours. If the heating time is less than 2 hours, the effect of reducing the vertical shrinkage at the time of delamination is insufficient, and it is difficult to sufficiently transfer additives such as an antifogging agent, an antifog agent, and a lubricant to the film surface. . If the heating time exceeds 48 hours, the vertical shrinkage decreases, but there is a possibility that discoloration of the agricultural vine and deterioration of physical properties due to thermal deterioration may occur.

There is no particular limitation on the heating equipment for heating the agricultural raw material, but the raw agricultural material may be a large heavy object having a length of up to 5 m. It is desirable to provide a facility having a sufficient volume and a temperature control function such as a heating warehouse, for example, which can perform a heating treatment at a constant temperature uniformly.

In the present invention, the thickness and width of the agricultural raw material are
Although not particularly limited, the thickness is 30 to 300 μm and the width is 5 m
The following are common. The use of the agricultural vine of the present invention is not particularly limited, and it can be used for any of external vine, internal lining, tunnel agricultural and the like. In addition, by using techniques such as adjusting the formulation, embossing, or coating, UV-cut farming, heat-protecting farming,
It can also be used as functionalized products such as pear-land farming, dust-proofing farming, and long-term anti-fog farming.

In the present invention, the processed agricultural product is obtained by breaking up a plurality of agricultural raw materials of the same type or different types, overlapping the ends of the film, and welding the overlapped portion with a high frequency welding machine or the like. After joining, it is cut into a desired length to have a width and a length that match the dimensions of a facility such as a house to be spread, and further subjected to eyelet processing or the like as necessary. Since the processed product of the agricultural vine of the present invention has a warp shrinkage ratio of 3% or less at the time of unwinding of the agricultural vine, no wrinkles or lumps are generated in the width joint portion, and water droplets condensed on the wrinkles or the lumps are not removed. There is no problem of falling on the crop and causing disease or the like on the crop.

[0038]

EXAMPLES The present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to these examples. The test methods used in Examples and Comparative Examples are as follows. Vertical shrinkage rate Adjust the condition of the raw agricultural material in a room at 23 ° C, measure the outer length (L ₁ ) [mm] of the roll of the agricultural raw material with a tape measure before breaking it, and use the needle to Pierce and mark the scroll. Agriculture raw material is broken up, a film having a length equivalent to one turn of a roll is cut out, and immersed in warm water at 50 ° C. for 10 minutes.
Then, after taking out from the warm water and drying all day and night in a room at 23 ° C., the length (L ₂ ) between the markings corresponding to one round of the scroll is obtained.
[Mm] is measured with a tape measure. The shrinkage was calculated by the following equation. Vertical shrinkage [%] = (L ₁ −L ₂ ) / L ₁ × 100

The expansion rate of the width of the agricultural raw material is adjusted in a room at 23 ° C., and the outermost film width (W ₁ ) [mm] of the roll of the agricultural raw material before being released.
Is measured with a tape measure. The film of the portion where the above-mentioned width was measured by breaking up the agricultural raw material was cut out over the entire width, and 50 ° C.
After being immersed in warm water for 10 minutes, taken out of the warm water and dried in a room at 23 ° C. for 24 hours, the length (W ₂ ) [mm] of the entire width of the film is measured with a tape measure. The expansion rate was calculated by the following equation. Horizontal expansion coefficient [%] = (W ₂ −W ₁ ) / W ₁ × 100

In a room at 23 ° C., 200 ml of 50 ° C. warm water was put into a 300 ml beaker, the entire opening of the beaker was covered with a test film, and after 15 minutes, the state of water droplets adhering to the film was observed. The antifogging property was evaluated according to the following criteria. A: The water film is uniform and the film is completely transparent. ：: The water film is slightly uneven, but the film is almost transparent. ×: Large water droplets adhered, and the film was partially opaque.

Antifogging property A rectangular parallelepiped frame having a length of 38 cm, a width of 15 cm and a height of 35 cm is made of a stainless steel pipe, and films are formed on the sides and the ceiling. In a freezer room with an outside air temperature of 5 ° C, a water temperature of 3
Water bath opening set at 0 ° C (length 30 cm x
The film is left standing for 3 hours or more with the bottom surface of the frame placed on top of (12 cm wide) to wet the inner surface of the film in advance. Next, a cold air of 5 ° C. was sent into the frame for 30 seconds, and after expelling the steam in the frame, it was put on a water bath again, and the state of fog formation was observed 5 minutes later. Was evaluated. ：: No fog is generated. ：: Slight fog is generated. ×: A state in which fog is generated in the entire frame.

Anti-blocking property The tackiness was measured according to the stickiness test method for lining of agricultural vineyards according to JIS K 6732. The smaller the measured value of the stickiness, the better the anti-blocking property.

Generation of Wrinkles after Welding Process 20 m of each of the unwrapped agricultural plastics from each of the two rolls was subjected to width joining processing using a high frequency welding machine, Quinlite LAM-304T (manufactured by Quinlite Electronics Seiko Co., Ltd.), and a temperature of 50 m. ℃ 1 heating warehouse
After being left for a month, the film was spread and the occurrence of wrinkles at the welded portion was visually observed, and evaluated according to the following criteria. ：: No wrinkles or bulges were observed at the portion in contact with the welded portion of the film. ：: Although wrinkles and lumps are slightly observed at the portion in contact with the welded portion of the film, there is no possibility that water droplets will fall even if the film is spread on the house. ×: Wrinkles and lumps are generated at a portion in contact with the welded portion of the film, and water droplets drop when the film is spread on a house.

Examples 1-2, Comparative Examples 1-5 Using the following formulation, using a 700 mmφ inverted L-type calender molding equipment, a thickness of 0.075 mm and a width of 300
After producing an agricultural plastic having a length of 100 cm and a roll length of 100 m, a heating treatment of the agricultural raw material was performed under the conditions shown in Table 1, and the vertical shrinkage, the lateral expansion, the anti-fogging property, the anti-fog property, and the blocking were performed. The prevention was evaluated. Table 1 shows the evaluation results. Polyvinyl chloride (degree of polymerization: 1300) 100 parts by weight Di-2-ethylhexyl phthalate (DOP) 45 Tricresyl phosphate (TCP) 5 Epoxy resin 2 Ba-Zn based liquid composite stabilizer 1.5 Ba-Zn based powder Complex stabilizer 1 Methylene bis stearamide 0.5 Sorbitan fatty acid ester-based anti-fog agent 2.0 Benzotriazole-based ultraviolet absorber 0.1

Examples 3 to 8 and Comparative Example 6 The test pieces A and B were evaluated for wrinkles after welding by using the agricultural plastics shown in Table 2. Test film A,
Table 2 shows the combinations of B and the evaluation results.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

The vinyl chloride resin film for agricultural use (agricultural plastic) of the present invention has a small vertical shrinkage at the time of unraveling, so that it does not become shorter than the ordered length even when it is stored for a long time after the joint processing. It is suitable as an agricultural coating material. Further, since there is little variation in the vertical shrinkage ratio between the rolls of the agricultural plastic, the occurrence of wrinkles at the welded portion is small. Furthermore, by heating treatment,
Since the components such as antifogging agent, antifogging agent and lubricant contained in agricultural plastics are blown out to the surface of the film, the antifogging property, antifogging property and antiblocking property can be quickly developed.

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Claims (2)

[Claims] 1. A roll of a film produced by a calender molding method or an extrusion molding method is further treated at 35-60.degree.
An agricultural polyvinyl chloride-based resin film having a shrinkage ratio in the vertical (MD) direction of 3% or less after disintegration, obtained by performing a heating treatment for up to 48 hours. 2. A processed product of an agricultural polyvinyl chloride resin film obtained by subjecting the agricultural polyvinyl chloride resin film according to claim 1 to a width joining process.