KR20160039667A - Film for agricultural use - Google Patents

Abstract

The present invention relates to a polypropylene resin composition containing a vinyl acetate-derived structural unit in an amount of 14 mass% or more and having a melt flow rate (MFR, JIS K7210-1999, 190 占 폚, 2160 g load; (A) and a polyolefin (B) having an MFR of 5 g / 10 min or less and a content ratio of the ethylene / vinyl acetate copolymer (A) and the polyolefin (B) A) :( B)] in a mass ratio of 30:70 or more to 70:30 or less and an average content of constituent units derived from vinyl acetate is 6% by mass or more and less than 12% Min to 10 g / 10 min or less.

Description

{FILM FOR AGRICULTURAL USE}

The present invention relates to agricultural films.

Generally, as the agricultural film, it is desired that the light transmittance is high. However, it is desired that the proportion of direct light (direct light) is reduced as much as possible and the ratio of the scattered light is increased depending on the kind of the crop. For example, in a nursery house of soft vegetables such as leaf tobacco and lettuce, it is indispensable to use an agricultural film having little direct light for preventing sunburn. In the dry house of leaf tobacco, it is indispensable to use an agricultural film having little direct light for prevention of rapid drying or for prevention of generation of seedlings and side leaves. For this reason, satin-like films have been used as agricultural films.

Examples of the easy-type agricultural film include a mixture of a vinyl acetate content of 24 to 34 wt%, an ethylene-vinyl acetate copolymer (A) of 4 to 40 MI and a polyethylene (B) of 0.04 to 2.0 MI, (A) / (B) is 10 to 100, the vinyl acetate content is 12 to 22% by weight, and the film is formed into a plastic film having a silk- (See, for example, Japanese Patent Application Laid-Open No. 63-67812).

For example, when at least one layer of the outermost layer contains an ethylene-vinyl acetate copolymer (A) having a vinyl acetate content of 20 to 35 wt% and a melt flow rate (MFR) of 4 to 50 g / 10 min and an MFR of 0.04 (A) and (B) is 35 to 90/65 to 10 (weight ratio), and the mixing ratio of (A) to (B) An agricultural film having a vinyl acetate content of 12 to 22% by weight and a MFR ratio (MFR / (B) MFR) of 10 to 100 is disclosed in JP-A- Japanese Patent Application Laid-Open No. 06-143509).

Further, for example, in a polyolefin multilayer film for outdoor agriculture comprising at least three layers of an outer layer, an intermediate layer, and an inner layer, the inner layer may be a polyolefin (for example, a polyolefin comprising an ethylene-vinyl acetate copolymer having a melt flow rate of 1.2 to 10 g / (A) and a polyolefin (B) having at least one kind selected from a high-pressure-treated low-density polyethylene and a linear low-density polyethylene having a melt flow rate of 0.2 g / 10 min or more lower than that of the polyolefin Polyolefin-based multilayer film for outdoor-use agriculture characterized in that it has a antifogging film (coating film) composed of a binder made of a thermoplastic resin and an inorganic colloidal sol on the surface of the inner layer, (See, for example, Japanese Patent Application Laid-Open No. 2011-109991).

As shown in Japanese Patent Publication Nos. 63-67812, 06-143509, and 2011-109991, an agricultural film having a variety of functions and having an easy surface (plastics Film), various attempts have been made.

From the viewpoint of producing an agricultural film having an easy-to-touch feel, a resin having a content of a structural unit derived from vinyl acetate to some extent has been conventionally demanded.

However, if the content of the vinyl acetate-derived structural unit is increased, the tackiness of the agricultural film tends to increase, and the following cases are likely to occur. That is, when it is easy to adhere to a roll or the like in a manufacturing process, blocking easily occurs between the agricultural films, and when the inflation film is poorly formed.

The present invention has been made in view of the above. In other words,

The present invention provides an agricultural film in which satin-like appearance is maintained and adhesion is suppressed.

In addition, the term "image" refers to a surface state having a rough texture with a plurality of irregularities on the surface of irregular fine spots as in the skin of a flesh of a ship.

<1> An ethylene / vinyl acetate copolymer (A) having a content of a structural unit derived from vinyl acetate of 14 mass% or more and a melt flow rate (MFR) of 11 g / 10 min or more and 300 g / (A) :( B) of the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) is 30:70 Or more and 70:30 or less and an average content of constituent units derived from vinyl acetate is 6% by mass or more and less than 12% by mass and the MFR is 1 g / 10 minutes or more and 10 g / 10 minutes or less, to be.

All of the MFRs were measured at 190 占 폚 under a load of 2160 g in accordance with JIS K7210-1999.

&Lt; 2 > The agricultural film according to < 1 >, wherein the mixture layer is the outermost layer.

According to the present invention, there is provided an agricultural film in which satin-like appearance is maintained and adhesion is suppressed.

[Agricultural film]

The agricultural film of the present invention has a content of constituent units derived from vinyl acetate of 14 mass% or more and a melt flow rate (MFR, JIS K7210-1999, 190 占 폚, 2160 g load) of 11 g / (B) having an MFR (JIS K7210-1999, 190 DEG C, 2160 g load) of not more than 5 g / 10 min, wherein the ethylene / vinyl acetate copolymer (A) (A): (B)] in a mass ratio of 30:70 or more to 70:30 or less and an average content of constituent units derived from vinyl acetate of 6% by mass or more and less than 12% by mass, Further, it has a mixture layer having MFR (JIS K7210-1999, 190 占 폚, 2160 g load) of 1 g / 10 min or more and 10 g / 10 min or less.

The agricultural film of the present invention is a combination of an ethylene / vinyl acetate copolymer (A) and a polyolefin (B) having a large MFR difference as described above. As the ethylene-vinyl acetate copolymer (A), those containing a large amount of vinyl acetate structural units are used. In the present invention, by applying such an ethylene / vinyl acetate copolymer (A) and a polyolefin (B), the agricultural film in the present invention has improved haze and realizes an ideal surface.

In addition, the agricultural film of the present invention contains the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) at the specified content ratio described above, and the content of the structural unit derived from vinyl acetate And the MFR of the agricultural film is set within the above range. By doing so, the agricultural film in the present invention is kept in an image state and the stickiness is suppressed.

In the present invention, the tackiness refers to both the tackiness of the agricultural film in the manufacturing process and the tackiness of the obtained agricultural film.

If the stickiness of the agricultural film in the manufacturing process is suppressed, it is considered that the ease of processing can be improved by inhibiting the winding of the agricultural film and the deterioration of the constitution of the agricultural film with respect to the processing member such as the roll used in the production.

Further, when the adhesiveness of the obtained agricultural film is improved, it is considered that the occurrence of blocking during storage of the agricultural film can be suppressed.

Hereinafter, each component contained in the agricultural film of the present invention will be described in detail.

Unless otherwise stated, the melt flow rate (MFR) is a value measured at 190 占 폚 under a load of 2160 g in accordance with JIS K7210-1999 [g / 10 min].

[Mixture Layer]

The agricultural film in the present invention has a mixture layer containing an ethylene / vinyl acetate copolymer (A) and a polyolefin (B).

The mixture layer may contain other polymers or additives as required.

&Lt; Ethylene-vinyl acetate copolymer (A) >

The ethylene-vinyl acetate copolymer (A) has a content of constituent units derived from vinyl acetate of 14 mass% or more and an MFR of 11 g / 10 min or more and 300 g / 10 min or less.

The ethylene-vinyl acetate copolymer contains at least a constituent unit derived from ethylene and a constituent unit derived from vinyl acetate, and may be a random copolymer, a block copolymer or an alternating copolymer.

Since the ethylene-vinyl acetate copolymer (A) has a content of constituent units derived from vinyl acetate of 14 mass% or more, the difference in the content of the constituent units derived from vinyl acetate with the polyolefin (B) increases, The agricultural film can be realized.

The content of the constituent unit derived from vinyl acetate in the ethylene-vinyl acetate copolymer (A) is preferably at least 16 mass%, more preferably at least 18 mass%.

The content of the constituent unit derived from vinyl acetate in the ethylene-vinyl acetate copolymer (A) is preferably 25% by mass or less from the viewpoint of reducing the average content of the constituent units derived from vinyl acetate in the mixture layer, More preferably 22 mass% or less.

The MFR of the ethylene · vinyl acetate copolymer (A) is within the above range, so that an agricultural film can be easily obtained.

The MFR of the ethylene-vinyl acetate copolymer (A) is preferably 12 g / 10 min to 200 g / 10 min, more preferably 14 g / 10 min to 160 g / 10 min.

The ethylene-vinyl acetate copolymer may be used singly or in combination of two or more different copolymers.

The ethylene-vinyl acetate copolymer may further contain other monomer units other than vinyl acetate and ethylene. In the present invention, it is preferable that an ethylene-vinyl acetate copolymer is constituted by a constituent unit derived from vinyl acetate and a constituent unit derived from ethylene, not including vinyl acetate and other monomer units other than ethylene.

&Lt; Polyolefin (B) >

The polyolefin (B) is a polyolefin having an MFR of 5 g / 10 min or less.

When the MFR of the polyolefin (B) is 5 g / 10 min or less, the above-mentioned agricultural film can be realized. The MFR of the polyolefin (B) is preferably in a range exceeding 0 g / 10 min. The MFR of the polyolefin (B) is preferably 3 g / 10 min or less, more preferably 0.01 g / 10 min or more and 1.5 g / 10 min or less.

Specific examples of the polyolefin (B) include an? -Olefin having 2 to 10 carbon atoms such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, , 3-methyl-1-butene, 1-octene, etc.). More specific examples of polyolefins include polyethylene, polypropylene, polybutene-1 and poly-4-methyl-1-pentene.

Of these, polyethylene and polypropylene are preferable, and polyethylene is particularly preferable.

The polyolefin may be used alone or in combination of two or more.

Preferred polyethylene is High Pressure Low Density Polyethylene (HP-LDPE) and Linear Low Density Polyethylene (LLDPE), and high pressure low density polyethylene is particularly preferred.

The polyethylene may be an ethylene /? - olefin copolymer obtained by copolymerization of ethylene and an? -Olefin. The ethylene /? - olefin copolymer is preferably a random copolymer.

The content ratio [(A): (B)] of the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) is in the range of 30:70 to 70:30 by mass. When the content is in this range, the agricultural film can exhibit a superior image.

The content ratio [(A) :( B)] of the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) is preferably 35:65 or more and 65:35 or less, more preferably 40:60 or more and 65:35 Or less.

For the same reason as above, the ethylene / vinyl acetate copolymer (A) and the polyolefin (B) are ethylene / vinyl acetate copolymer and low density polyethylene, and the content ratio [(A) :( B) And particularly preferably from 40:60 to 65:35 [mass ratio]. The ethylene-vinyl acetate copolymer preferably includes two kinds (preferably the MFR ratio of both is 5 or more) of an ethylene-vinyl acetate copolymer having an MFR of less than 100 and an ethylene-vinyl acetate copolymer having an MFR of 100 or more The sun is appropriate.

<Other Polymers>

Examples of the other polymer include an ethylene / (meth) acrylic acid copolymer, an ionomer, and the like. The content of the other polymer is preferably 30 mass% or less with respect to the entire agricultural film.

<Other additives>

As other additives, for example, a warming agent, an antioxidant, an ultraviolet absorber, a light stabilizer, an anti-fogging agent, an antifog agent and the like are suitably blended. As the warming agent, a known one having a refractive index approximate to the refractive index of the mixture layer can be used. It is most preferable to use hydrotalcite, which has good heat retention and does not adversely affect the light transmittance.

The content of other additives is preferably 30% by mass or less based on the entire agricultural film.

&Lt; Properties of mixture layer >

The mixture layer of the agricultural film of the present invention has an average content of constituent units derived from vinyl acetate of 6 mass% or more and less than 12 mass% and an MFR of 1 g / 10 min or more and 10 g / 10 min or less.

If the average content of constituent units derived from vinyl acetate in the mixture layer is 12 mass% or more, the agricultural film can not suppress the stickiness. When the average content of constituent units derived from vinyl acetate in the mixture layer is less than 6% by mass, the agricultural film can not maintain easiness.

The average content of constituent units derived from vinyl acetate in the mixture layer is preferably small, more preferably from 8% by mass to 11% by mass, from the viewpoint of suppressing the tackiness of the agricultural film.

The "average content of the structural units derived from vinyl acetate" specifically means the content of the structural units derived from vinyl acetate in the ethylene-vinyl acetate copolymer (A) in accordance with the method according to JIS K7192 1999 And then calculating the vinyl acetate content in the total of 100 mass% of the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) using the following formula (1). This calculated value is referred to as an average content of the constituent units derived from vinyl acetate in the mixture layer.

(Equation 1)

Average content of the constituent units derived from vinyl acetate =

Content (% by mass) of constituent unit derived from vinyl acetate in ethylene-vinyl acetate copolymer (A) 占 Content (% by mass, content of ethylene-vinyl acetate copolymer (A) + Polyolefin (B) = 100) ÷ 100

The MFR of the mixture layer is within the above range, so that the film workability is excellent.

The MFR of the mixture layer is preferably from 2 g / 10 min to 7 g / 10 min, more preferably from 2 g / 10 min to 5 g / 10 min from the viewpoint of film processability.

The thickness of the mixture layer is preferably from 3 탆 to 500 탆, and more preferably from 10 탆 to 200 탆.

[Layer other than the mixture layer]

The agricultural film in the present invention may have a layer other than the above-mentioned mixture layer from the viewpoint of obtaining necessary characteristics such as mechanical strength, durability, and warmth in the agricultural film.

Specific examples of the layer other than the mixture layer include a barrier resin layer using a barrier resin such as an olefin resin layer and an EVOH (ethylene / vinyl alcohol copolymer resin).

It is preferable that the mixture layer is the outermost layer from the viewpoint of suppressing excess direct light to plants.

[Production method of agricultural film]

Examples of the method for producing an agricultural film in the present invention include a method of preparing a mixture containing the above-mentioned components, and then molding the mixture into a film by a known method.

Hereinafter, a method for producing an agricultural film having a mixture layer alone will be described. However, the method for producing an agricultural film in the present invention is not limited to the following method.

For example, the above mixture is prepared by dry-blending or melt-blending each of the above components. In the case of the dry blend, the components are mixed in a step of melting and plasticizing in the molding machine. In the case of the melt blend, melt blending may be carried out using a mixer or a mixer such as various mixers, rolls and kneaders such as various extruders such as a single screw or twin screw extruder and Banbury mixer. The mixing order in the case of the melt blend is not particularly limited.

Thereafter, it is molded into a film shape by a known method such as an inflation method or a casting method.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples unless it exceeds its main object.

Details of components used in the production of agricultural films are as follows.

&Lt; 1. Ethylene-vinyl acetate copolymer (EVA) >

(EVA-1):

Content of constituent units of vinyl acetate (VA content): 19 mass%

MFR (JIS K7210-1999, 190 占 폚, load 2160 g) 15 g / 10 min

(EVA-2):

Content of constituent units of vinyl acetate (VA content): 19 mass%

MFR (JIS K7210-1999, 190 占 폚, load 2160 g) 150 g / 10 min

(EVA-3):

Content of constituent units of vinyl acetate (VA content): 28 mass%

MFR (JIS K7210-1999, 190 占 폚, load 2160 g) 15 g / 10 min

(EVA-4):

Content of constituent units of vinyl acetate (VA content): 10 mass%

MFR (JIS K7210-1999, 190 DEG C, load 2160 g) 9 g / 10 min

&Lt; 2. Polyolefin (PO) >

(PO-1):

Type: Low density polyethylene

MFR (JIS K7210-1999, 190 DEG C, load 2160 g) 1.1 g / 10 min

(PO-2):

Type: Low density polyethylene

MFR (JIS K7210-1999, 190 DEG C, load 2160 g) 0.15 g / 10 min

(PO-3):

Type: Low density polyethylene

MFR (JIS K7210-1999, 190 DEG C, load 2160 g) 0.3 g / 10 min

[Example 1]

(Production of agricultural film 1)

The following components were prepared.

<Component>

EVA-1: 30 parts by mass

EVA-2: 13 parts by mass

PO-1: 38 parts by mass

PO-2: 19 parts by mass

- Preparation of mixture -

The above components were subjected to melt blending using a single screw extruder (extruder screw diameter: 65 mm) under the conditions of a die temperature of 160 占 폚 and a melting zone temperature of 160 占 폚.

The content of the constituent unit of vinyl acetate (the average content (unit: mass%) of vinyl acetate-derived constituent units (expressed as VA content) in Table 1) and the MFR of the mixture after melt blending were measured according to the previously described method . The results are shown in Table 1.

- Forming -

The melt-blended mixture was melt-kneaded using a single-layer inflation molding machine (diameter 100 mm, extruder screw diameter 30 mm) at a die temperature of 160 占 폚, a melting zone temperature of 160 占 폚, LS (line speed) of 4.0 m / min, BUR Ratio 1.6) to form a mixture layer to obtain an agricultural film 1 having a diameter of 250 mm and a thickness of 50 占 퐉.

(evaluation)

Evaluation of the agricultural film 1 was conducted on the following items. The results are shown in Table 2.

- Evaluation of organizational structure -

The formed tube-shaped agricultural film 1 was placed on a sample table and stored for one day in an atmosphere of 23 ° C and 50% RH, and this was used as an evaluation sample (a state in which two sheets were stacked to form a layer). The evaluation sample was sandwiched between the thumb and forefinger of one hand and slightly twisted several times, and the number of beatings was determined until it was opened and evaluated according to the following evaluation criteria.

<Evaluation Criteria>

A: Only one bit is opened.

B: Opened only 2 to 3 times

C: Bit is not opened when the number of times is less than 5

- Appearance evaluation -

The obtained agricultural film 1 was visually evaluated in accordance with the following evaluation criteria.

<Evaluation Criteria>

A: Agricultural film has a very good image.

A-B: Agricultural films have excellent image quality.

B: An image is expressed on an agricultural film.

C: No image is expressed on the agricultural film.

- Total light transmittance -

The total light transmittance of the obtained agricultural film 1 was measured by a haze meter (manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS-K7136, and the index was used as an index for evaluating the light transmittance of the agricultural film 1.

The total light transmittance is measured by measuring both the case where light is incident on one side (referred to as &quot; face 1 &quot;) of the agricultural film 1 and the case where light is incident on the opposite side Respectively.

If the total light transmittance is 90% or more, there is no practical problem.

- Hayes -

The haze of the obtained agricultural film 1 was measured by a haze meter (manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS-K7136, and the index was used as an index for evaluating the image quality of the agricultural film 1.

The haze was measured in the case where light was incident on one side (referred to as &quot; face 1 &quot;) of the agricultural film 1 and the case where light was incident on the opposite side (referred to as &quot; face 2 &quot;).

If the haze is 70% or more, there is no practical problem.

- Polish -

The obtained agricultural film 1 was measured for gloss in accordance with JIS K7105 and used as an index for evaluating the image quality of the agricultural film 1.

The glossiness was measured in the case where light was incident on one side (referred to as &quot; side 1 &quot;) of the agricultural film 1 and the case where light was incident on the opposite side (referred to as &quot; side 2 &quot;).

[Examples 2 and 3, Comparative Examples 1 and 2]

An agricultural film was produced in the same manner as in Example 1 except that the composition of the agricultural film was changed in accordance with Table 1 in Example 1. The obtained agricultural film was evaluated in the same manner as in Example 1. The results are shown in Table 2.

As can be seen from Tables 1 to 2, it is clear that the agricultural film of the present embodiment is kept in an easy-to-see state and is excellent in individual constitution, so that the adhesiveness is suppressed. On the other hand, it is clear that the agricultural film of the comparative example is not suppressed in adhesion even though it is an ideal image.

It is also expected that the agricultural film in the present example is suppressed in adhesiveness not only after the production but also in the production process as compared with the agricultural use in the present comparative example.

The disclosure of Japanese Patent Application No. 2013-172503 is incorporated herein by reference in its entirety.

All publications, patent applications, and technical specifications described in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, and technical specification were specifically and individually indicated to be incorporated by reference.

Claims (2)

Having a content of constituent units derived from vinyl acetate of 14% by mass or more and a melt flow rate (MFR, JIS K7210-1999, 190 占 폚, 2160 g load) of 11 g / 10 min to 300 g / Vinyl copolymer (A) and a polyolefin (B) having MFR (JIS K7210-1999, 190 DEG C, 2160 g load) of 5 g / 10 min or less,
Wherein the content ratio [(A) :( B)] of the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) is in the range of 30:70 to 70:30 by mass, Wherein the average content is 6 mass% or more and less than 12 mass%, and the MFR (JIS K7210-1999, 190 占 폚, 2160 g load) is 1 g / 10 min or more and 10 g / 10 min or less. The method according to claim 1,
Wherein the mixture layer is an outermost layer.