JP3504307B2 - Coloring film production method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a color-imparting film in which strip-shaped colored portions and transparent portions are arranged in the longitudinal direction. In particular, the present invention relates to a method for forming a coloration film suitable for an agricultural coloration mulch film.

[0002]

2. Description of the Related Art In recent years, year-round cultivation of agricultural crops is spreading to general farmers, and the growth of crops is regulated by forming a part where sunlight is well exposed and a part where soil temperature is high in the same ridge. The method to do is adopted actively. As a multi-film for that purpose, a color multi-film is often used.

By the way, this color arrangement multi-film has heretofore been a color arrangement multi-film composed of a black portion and a transparent portion (for example, JP-B-49-7164, etc.) and a color-arrangement multi-film formed of a silver portion and a transparent portion (for example, JP-B-47). -336
No. 33) is generally known. These color arrangement films are mainly formed by the T-die method. Although the film formed by the same method has excellent thickness uniformity, there is a limitation on the film width that can be formed from the same die. Therefore, a film forming method based on the inflation method is being studied in which a film having an arbitrary width can be easily obtained from the same die.

However, in the case of forming a color arrangement film by the inflation method, when compressed air is blown into a melting tube having a coextruded band-shaped colored portion and a transparent portion to expand the transparent portion, the transparent portion is more than the colored portion. It swells greatly. The so-called blister phenomenon occurs. Therefore, a large thickness difference occurs between the colored part and the transparent part, and as a result, winding wrinkles or unevenness on the roll winding surface may occur, or "unpleasant drag" or "slack" may occur when unwound. The smoothness of the film was impaired. Further, the strength of the boundary between the colored portion and the transparent portion was extremely weak. Therefore, when used as a mulch film for agriculture, there is a problem that the boundary portion is easily torn during laying or the like.

[0005]

DISCLOSURE OF THE INVENTION The present invention has a small thickness difference between a colored portion and a transparent portion in the production of a color arrangement film by an inflation method and has a uniform thickness.
An object of the present invention is to provide a method for forming a coloration film in which the strength of the boundary between the colored portion and the transparent portion is high.

[0006]

Means for Solving the Problems The inventors of the present invention have made earnest studies on the method of forming a color arrangement film by the inflation method, and as a result, have found that the melt index of the resin composition used for the colored portion and the resin composition used for the transparent portion It was found that the strength of the boundary portion between the colored portion and the transparent portion is greatly improved by not only the problem of the thickness difference between the colored portion and the transparent portion but also the strength of the boundary portion is greatly improved by setting the specific ratio of the above to complete the present invention. .

That is, a coloring film in which a strip-shaped colored portion and a transparent portion are arranged along the longitudinal direction, or one surface of a layer in which the strip-shaped colored portion and the transparent portion are arranged along the longitudinal direction, or
In the method for forming a color-imparting film having resin layers laminated on both sides by an inflation method, the melt index (MIA) of the ethylene-α-olefin copolymer composition used in the colored part and the ethylene-α-olefin used in the transparent part Melt index (MIB) of copolymer composition
Satisfies the following formula. 1.2 ≦ MIA / MIB ≦ 4.0

In the present invention, an ethylene-α-olefin copolymer (hereinafter referred to as L-LDP) used for the colored portion and the transparent portion.
Called E. ) Is a copolymer of ethylene and an α-olefin having 4 to 12 carbon atoms. Examples of the α-olefin include butene-1, hexane-1, 4-methylpentene-1, octene-1 and the like. And LL
DPE includes various antioxidants, ultraviolet absorbers, antiblocking agents, antifog agents, antifoaming agents, fillers, antistatic agents,
Additives such as lubricants, LDPE and HDPE
It may be a resin composition obtained by blending a polyolefin resin such as.

Further, in the method of the present invention, L-LDPE is used for the colored portion and the transparent portion so that the adhesive strength at the boundary surface between the colored portion and the transparent portion is good and the strength of the boundary portion becomes strong. . The reason for using L-LDPE is that a film having high strength and excellent heat resistance can be obtained, and the film-forming property is good, and the cost is low.

The L-LD used for the colored portion and the transparent portion
The melt index of the PE composition must satisfy the following formulas. 1.2 ≦ MIA / MIB ≦ 4.0 In the present invention, the melt index of each resin composition is a value measured at 190 ° C. according to JIS K7210.

When the ratio (MIA / MIB) of the melt index (MIA) of the resin composition of the colored part and the melt index (MIB) of the resin part of the transparent part is less than 1.2, the thickness of the transparent part Becomes significantly thinner than the thickness of the colored portion, and wrinkles are generated and irregularities are generated on the roll winding surface, and the strength of the boundary between the colored portion and the transparent portion is weakened. In addition, the melt index ratio (M
When IA / MIB) exceeds 4.0, the thickness of the transparent portion becomes thicker than the thickness of the colored portion, and similar to the above, occurrence of winding wrinkles and unevenness on the roll surface, as well as coloring portion and transparent portion. The strength of the boundary part of is also weak.

Incidentally, L- used for the colored portion and the transparent portion of the present invention.
LDPE preferably has a melt index of 0.1 to 5 g / 10 minutes and a melt index of 0.1 g.
If it is less than / 10 minutes, the inflation molding process is difficult, and if it exceeds 5 g / 10 minutes, the film strength becomes weak, which is not preferable.

Examples of the coloring agent used in the coloring portion of the present invention include Al powder for silver, carbon black for black, titanium oxide for white, and phthalocyanine lean for green.

In the method of the present invention, when the obtained color arrangement film is used for an agricultural color arrangement mulch film, an ethylene-α-olefin copolymer colored silver, green or black in the colored portion. It is preferred to use the composition.

In the method of the present invention, the resin composition for the colored portion and the transparent portion is supplied from different extruders to an annular die having a special resin distribution flow path, and the belt-shaped colored portion and the transparent portion are provided along the longitudinal direction. Co-extrude the placed melt tube. Then, compressed air is blown into the co-extruded melting tube to expand it. At that time, the blow ratio is preferably about 1.5 to 4.0 from the viewpoint of the strength of the obtained film and the accuracy of uneven thickness.

Further, the method for forming a color arrangement film of the present invention comprises:
Not only a single layer film having a colored portion and a transparent portion but also a color arrangement film in which another resin layer is laminated on one side or both sides of a layer having a colored portion and a transparent portion can be used. For example, a method of coextruding a transparent resin layer or a colored resin layer on one surface of a layer having a colored portion and a transparent portion, or a coextrusion of a transparent resin layer on both surfaces of a layer having a colored portion and a transparent portion. Or a method of co-extruding a transparent resin layer on one surface of the layer having a colored portion and a transparent portion and a colored resin layer on the other surface. Colored film in which colored resin layers are laminated is an outer layer that can be seen through the color of the colored portion of the intermediate layer and the transparent portion of the intermediate layer when viewed from the side opposite to the surface on which the colored resin layer is laminated. The color of the colored resin layer and the color of the colored resin layer are arranged in a strip shape. The resin to be laminated on one side or both sides of the layer having the colored portion and the transparent portion is not particularly limited, but in view of film-forming property by coextrusion and interlayer adhesive strength, L- LDPE is preferred.

The above-mentioned two-layer or three-layer color arrangement film is particularly suitable as an agricultural color arrangement mulch film because of its excellent strength and weather resistance.

[0018]

EXAMPLES The methods of the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these methods.

The methods for measuring and evaluating the physical properties used in the present invention are as follows. (1) Film thickness The film thickness was measured along the width direction of the film with a measuring device capable of measuring the film thickness to 1 μm. (2) Width 10 mm × length 120 mm so that the boundary between the colored portion and the transparent portion at the boundary is located parallel to the width at the center in the length direction.
The test piece of 1 was punched out, and the maximum tensile strength was measured by a tensile tester. (3) Rolled state A test film having a length of 200 m was rolled on a paper tube having a diameter of 50 mm and the state was visually evaluated. In addition, there are no wrinkles and the surface of the roll is smooth and has no irregularities. Moreover, when the film is unwound, "pulling"
(○) that the surface of the film is smooth without any slack
And those that were not (X).

[Embodiment 1] The colored portion contains 10% of Al powder.
Silver-colored L-LDPE composition (MI =
0.9 g / 10 minutes), the transparent part has MI = 0.5 g / 10
A color distribution film was formed by an inflation method using two extruders and an annular die having a special distribution channel so as to obtain transparent L-LDPE. The film forming conditions are as follows: extrusion temperature 200 ° C., extrusion amount 150 Kg / h
r, the blow ratio was 2.8, the take-up speed was 50 m / min, the width of the colored portion and the transparent portion was 2: 1, and two stripes each were provided.
In addition, the tubular film thus taken off was cut into central portions of the colored portions to obtain two color arrangement films. The thickness of the obtained color arrangement film, the strength of the boundary portion, the rolled shape, etc. were measured and shown in Table 1. As a result, as is clear from Table 1, the difference in thickness between the colored portion and the transparent portion was small, the roll winding surface and the unwound film surface were smooth, and the strength of the boundary portion between the colored portion and the transparent portion was also strong.

[0021]

[Table 1]

Example 2 Example 1 was repeated, except that L-LDPE composition (MI = 1.0 g / 10 minutes) was used in which 10% of phthalocyanine lean was blended in the colored portion to give a green color. A color arrangement film was formed by the same method. The thickness of the obtained color arrangement film, the strength of the boundary portion, the rolled shape, etc. were measured and are shown in Table 1. As a result, similar to Example 1, the difference in thickness between the colored portion and the transparent portion was small, the roll winding surface and the unwound film surface were smooth, and the strength of the boundary portion between the colored portion and the transparent portion was also strong.

[Example 3] Example 3 except that 6% of carbon black was blended in the colored portion to give a black colored L-LDPE resin composition (MI = 1.2 g / 10 minutes) A color arrangement film was formed in the same manner as in 1. The thickness of the obtained color arrangement film, the strength of the boundary portion, the rolled shape, etc. were measured and are shown in Table 1. As a result, similar to Example 1, the difference in thickness between the colored portion and the transparent portion was small, the roll winding surface and the unwound film surface were smooth, and the strength of the boundary portion between the colored portion and the transparent portion was also strong.

[Example 4] Titanium oxide was added to the colored portion in an amount of 30%.
White L-LDPE composition (MI =
A color arrangement film was formed by the same method as in Example 1 except that 1.6 g / 10 min) was used. Table 1 also shows the thickness of the obtained color arrangement film, the strength of the boundary portion, the rolled shape, and the like. As a result, similar to Example 1, the difference in thickness between the colored portion and the transparent portion was small, the roll winding surface and the unwound film surface were smooth, and the strength of the boundary portion between the colored portion and the transparent portion was also strong.

Example 5 The resin composition used in Example 1 was used as the colored part and the transparent part, and MI = 0.8 g for both outer layers.
A colored multi-film was formed by an inflation method using three extruders and a three-layer annular die having a special distribution channel so as to obtain a transparent L-LDPE of / 10 minutes. The average thickness of the film is about 20 μm,
The thickness ratio between both outer layers and the intermediate layer was 1: 1: 1. or,
The film forming conditions and the positional relationship between the colored portion and the transparent portion were the same as in Example 1. The thickness difference between the colored portion and the transparent portion of the obtained color arrangement multi-film was as small as 1 μm, and the surface of the rolled film or the unwound film was smooth. The strength of the boundary between the colored part and the transparent part was as strong as 800 g.

[Comparative Example 1] Titanium oxide 30% in the coloring layer
White L-LDPE composition (MI =
1.6 g / 10 min), and a color arrangement film was formed by the same method as in Example 1 except that L = LDg of MI = 0.3 g / 10 min was used for the transparent portion. The thickness of the obtained color arrangement film, the strength of the boundary portion, the rolled shape and the like were measured and shown in Table 2. As a result, as is clear from Table 2,
The thickness difference between the colored part and the transparent part was large, the smoothness of the rolled surface or the unwound film surface was poor, and the strength of the boundary part between the colored part and the transparent part was weak.

[0027]

[Table 2]

[Comparative Example 2] An L-LDPE composition (MI = 0.
9g / 10 minutes), MI = 0.8g / 10 minutes L on the transparent part
A color arrangement film was formed by the same method as in Example 1 except that LDPE was used. The thickness of the obtained color arrangement film, the strength of the boundary portion, and the roll appearance etc. were measured,
It is also shown in Table 2. As a result, as in Comparative Example 1, the difference in thickness between the colored portion and the transparent portion was large, the smoothness of the rolled surface or the unwound film surface was poor, and the strength of the boundary portion between the colored portion and the transparent portion was weak.

[0029]

The method of the present invention is a simple method of specifying the melt index of the resin composition used for the colored part and the transparent part, and the difference in thickness between the colored part and the transparent part is small, and the colored part and the transparent part are transparent. It is possible to obtain a coloration film in which the strength of the boundary between the parts is high. As a result, the color arrangement film obtained by the method of the present invention is not only smooth on the surface of the roll when it is wound into a roll, but also has no "drag" or "slack" when the film is unwound. The film surface is smooth. Further, since the film has a high strength at the boundary between the colored portion and the transparent portion, it does not break from the portion. In particular,
The two-layer or three-layer color-matching film obtained by the method of the present invention has excellent weather resistance when used as a color-matching mulch film for agriculture, and does not tear from the portion when laid. From these facts, the method of the present invention is particularly useful for forming an agricultural color arrangement mulch film.

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B29C 55/28 B29C 47/20

Claims (3)

(57) [Claims] 1. An ethylene-α-used for a colored part in a method of forming a coloration film in which a band-shaped colored part and a transparent part are arranged along a longitudinal direction by an inflation method.
Melt index of olefin copolymer composition (MI
A method for forming a color-matching film, characterized in that the melt index (MIB) of the ethylene-α-olefin copolymer composition used in A) and the transparent portion satisfies the following formula. 1.2 ≦ MIA / MIB ≦ 4.0 2. The method for forming a color-imparting film according to claim 1, wherein an ethylene-α-olefin copolymer composition colored in silver, black or green is used in the colored portion. 3. A method for producing a coloration film, in which a resin layer is laminated on one side or both sides of a layer in which a belt-shaped colored portion and a transparent portion are arranged along the longitudinal direction, by an inflation method. The melt index (MIA) of the ethylene-α-olefin copolymer composition used for the above and the melt index (MIB) of the ethylene-α-olefin copolymer composition used for the transparent part satisfy the following formula. Method for forming color arrangement film. 1.2 ≦ MIA / MIB ≦ 4.0