JP2002347112A - Method for manufacturing water-soluble embossed film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a water-soluble embossed film excellent in blocking resistance, free from shining, giving high quality feeling and excellent in pin hole resistance. SOLUTION: Embossing process is carried out by passing a water-soluble film between an embossed roll marked with uneven shape having satin patterns and a back up roll to form the satin patterns with the surface roughness (Ra) 0.1-8 μm and the uneven pattern with less than 100 meshes and 50-300 μm deep.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a water-soluble embossed film having excellent blocking resistance, no shininess, high quality and pinhole resistance.

[0002]

2. Description of the Related Art Conventionally, packaging materials made of water-soluble films such as polyvinyl alcohol-based films have been used for agricultural chemicals, drugs,
It is widely used as a material for accommodating dyes, detergents, fertilizers, cosmetics, sanitary products, etc. Such packaging materials are directly injected into aqueous media using the water solubility of the film to decompose the packaging materials. Alternatively, it is used for applications such as dissolving to obtain a solution, or disposing of a packaging material opened at the time of use by pouring it into water and discarding it. Such a water-soluble film is subjected to a surface treatment in practical use, for example, a matte treatment for giving a matte pattern to the water-soluble film for matting or blocking prevention,
In order to improve the blocking property, an embossing process for forming an uneven shape on the film is performed. For example, as the latter example, Japanese Patent Application Laid-Open No. 7-290567 discloses an embossing method.
In the publication, the thickness of the concave portion is 15 to 25 μm (the thickness of the convex portion is 2 μm).
0-100 μm) and the tensile strength of the film is 2.5-
A method for producing an embossed water-soluble film of 4.5 kg / mm ² has been proposed.

[0003]

However, the present inventor studied the above-mentioned prior art, and found that in this prior art, in terms of blocking resistance, a large number of films were stacked for a long period of time under high temperature and high humidity. It is clear that the effect is limited when stored or when a long film is wound into a roll and stored for a long period of time. It became. In the market, there is a high demand for high-quality products, and a method for producing a water-soluble embossed film that does not cause blocking even under such severe conditions is required.

[0004]

Therefore, the present inventor has performed an embossing process by passing a water-soluble film between an embossing roll and a backup roll, each of which is imprinted with a satin pattern, and embossing the film surface. A method for producing a water-soluble embossed film, characterized by forming a matte pattern having a surface roughness (Ra) of 0.1 to 8 μm and a concavo-convex pattern having a depth of 50 to 300 μm with a mesh size of 100 mesh or less has the above object. We have found that we can achieve this and have completed the present invention.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The water-soluble resin as a raw material of the water-soluble film of the present invention is not particularly limited, and examples thereof include various types of synthetic or natural product derivatives such as polyvinyl alcohol-based resins, carboxymethyl celluloses, starches, polyethylene oxides, and pullulans. Although a resin material is mentioned, a polyvinyl alcohol-based resin is particularly preferable.

The polyvinyl alcohol resin is usually produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate. However, the present invention is not limited to this, and a small amount of unsaturated carboxylic acid (Including salts, esters, amides, nitriles, etc.), olefins, vinyl ethers, unsaturated sulfonates, polyoxyalkylene allyl ethers, and the like.

Among such polyvinyl alcohol resins, a saponification degree of 70 to 100 mol% is particularly preferable.
Furthermore, 75 to 99 mol% is preferable. If the saponification degree is less than 70 mol%, the water solubility tends to deteriorate, which is not preferable. Further, the average degree of polymerization is 300 to 4000, and furthermore 5
When the average degree of polymerization is less than 300, the strength of the film is inferior. When the average degree of polymerization exceeds 4,000, the film-forming properties deteriorate, which is not preferable.

In order to obtain a water-soluble film using the above water-soluble resin, the water-soluble resin is melt-molded by a method such as a method of casting on a smooth metal surface such as a drum or an endless belt or an extrusion method. And the like.

At the time of film formation, if necessary, a plasticizer of a polyhydric alcohol such as glycerin, diethylene glycol, triethylene glycol, or the like,
In addition to amine-based antioxidants, stabilizers such as phosphoric esters, etc., ordinary addition of coloring agents, fragrances, extenders, depackaging agents, release agents, ultraviolet absorbers, inorganic powders, surfactants, etc. An agent can be added.

The thickness of the water-soluble film is not particularly limited, but is preferably from 10 to 120 μm, more preferably from 15 to 80 μm, and if it is less than 10 μm, the mechanical strength will be insufficient, and will exceed 120 μm. This leads to a decrease in water solubility and a decrease in film formation efficiency, which is not preferable. The water content of the water-soluble film is not particularly limited, but is preferably from 1 to 15% by weight, more preferably from 2 to 10% by weight, and if it is less than 1% by weight, the film is too hard and an uneven pattern is formed. When the content exceeds 15% by weight, the film is too soft and the uneven pattern is not retained, which is not preferable.

In the present invention, the water-soluble film obtained as described above is passed between an embossing roll and a backup roll on which a concavo-convex pattern having a satin finish is imprinted, and embossing is performed, so that the film has a surface roughness ( Ra) is 0.1 to
8 μm, further 0.4 to 5 μm, especially 0.8 to 4 μm
Pearskin pattern, 100 mesh or less, and even 20-80
Mesh with a depth of 50-300 μm, and even 60-2
It is characterized by forming an uneven pattern of 00 μm. If the surface roughness is less than 0.1 μm, the blocking resistance is poor, and if it exceeds 8 μm, the pinhole resistance is poor and unsuitable. Also, when the uneven pattern exceeds 100 mesh, the obtained water-soluble embossed film has poor blocking resistance,
In addition, a film having a high quality feeling cannot be obtained, which is inappropriate. Further, if the depth of the uneven pattern is less than 50 μm, a sufficient apparent film thickness cannot be obtained, and if it exceeds 300 μm, pinholes are generated in the film and the object of the present invention cannot be achieved.

The surface roughness (Ra) mentioned here is measured by a laser microscope (for example, an ultra-depth shape measuring microscope, "VK-8510" manufactured by KEYENCE CORPORATION). Is measured by the method of JIS B0601.

As the uneven pattern satisfying the above conditions,
A lattice pattern, a silk pattern, a tortoise pattern, a rhombus pattern, and the like can be given. Among them, a silk pattern is preferable in terms of high-quality feel and blocking resistance.

In embossing, an embossing roll and a backup roll, each of which is imprinted with a textured pattern having a satin finish, are used. Specifically, the embossing roll has a surface roughness (Ra) of 0. 3-10μ
m, moreover, 0.5-7 μm, especially 1-5 μm satin shape and 100 mesh or less, further 80 mesh or less,
In particular, it is 20-60 mesh, and the depth is 100-400μ.
It is preferable to use an embossing roll on which an uneven shape of 150 m to 300 m is stamped.

[0015] Such embossing rolls are as follows: 1) The surface of a metal roll or a ceramic roll is provided with a satin pattern by a sand blasting method, a chemical matting method, or an etching method, and then a silk-shaped (irregularly shaped) seed roll is used. A method of applying an eye pattern and performing plating and the like as necessary,
2) A silk pattern is applied to the surface of a metal roll or a ceramic roll using a seed roll having a silk pattern, and then a matte pattern is applied by a sand blast method, a chemical mat method, or an etching method, and plating is performed as necessary. How to apply processing, etc.
3) It is manufactured by applying a satin pattern by an electric discharge machine of a transistor pulse power supply, then applying a silk pattern by a silk-shaped seed roll, and performing plating if necessary.

The metal roll is not particularly limited, but includes metal rolls such as iron, SUS, mild steel, hard steel, chromium steel, nickel steel, cast steel, and brass. Ceramic rolls include aluminum oxide and silicon dioxide. , Silicon nitride,
A ceramic roll made of a ceramic such as silicon carbide may be used.

The above-mentioned backup roll is preferably a rubber roll coated with a synthetic rubber such as a urethane-based, silicone-based, fluorine-based or olefin-based rubber, a cotton roll or a paper roll. When the backup roll is a rubber roll, it is preferable to use one having a roll surface hardness of A50 ° to A95 °, more preferably A55 ° to A95 °, and particularly A60 °.
~ A95 °. The surface hardness of the roll is A50 °
If it is less than A95 °, a sufficient apparent film thickness cannot be obtained, and if it exceeds A95 °, although an apparent film thickness can be obtained, transfer of an embossed pattern cannot be sufficiently performed and pinholes are easily generated, which is not preferable.

In the case of a cotton roll or paper roll, it is preferable to use a roll having a surface hardness of D50 ° to D90 °, and more preferably D55 ° to D8.
5 °, in particular D60 ° to D85 °. If the surface hardness of the roll is less than D50 °, a sufficient apparent film thickness cannot be obtained, and if it exceeds D90 °, the apparent film thickness can be obtained, but sufficient embossed pattern transfer cannot be performed and pinholes are generated. It is not easy to do. Here, the surface hardness is
This is a hardness determined by a measuring method according to JIS K6301.

The pressure applied to the water-soluble film when passing the water-soluble film between the embossing roll and the backup roll is preferably from 10 to 150 kg / cm, more preferably from 30 to 100 kg / cm.

If the pressing force is less than 10 kg / cm, embossing with a sufficient depth cannot be performed, and
When the thickness exceeds cm, the thickness of the embossed film is partially reduced, mechanical strength is reduced, and pinholes tend to occur, which is not preferable.

It is preferable that the surface temperature of the embossing roll during embossing is 100 to 200 ° C. and that the surface temperature of the backup roll is 50 ° C. or higher. More preferred surface temperature of the embossing roll is 105 to 170 ° C.
And particularly preferably 110 to 160 ° C., and more preferably the surface temperature of the backup roll is 60 to 110 ° C.
° C, and particularly preferably from 65 to 100 ° C.

If the surface temperature of the embossing roll is less than 100 ° C., embossing with a sufficient depth cannot be performed,
If the temperature exceeds 200 ° C., the water solubility of the film is undesirably reduced. On the other hand, if the surface temperature of the backup roll is less than 50 ° C., it is not preferable because embossing having a sufficient depth cannot be obtained.

The water-soluble embossed film thus obtained is wound into a roll and commercialized. The water-soluble embossed film obtained in the present invention, even when a fairly strong pressure is applied between the films, also has no blocking even when stored in a high-temperature, high-humidity atmosphere, and furthermore has no shine on the film surface, It has a high-quality feel and is also excellent in pinhole resistance, and is useful as a packaging material for agricultural chemicals, drugs, dyes, detergents, fertilizers, cosmetics, sanitary products, etc. Useful for

[0024]

The present invention will be specifically described below with reference to examples. In the examples, “%” means on a weight basis unless otherwise specified.

Example 1 [Production of water-soluble film] 25% of polyvinyl alcohol resin [average degree of polymerization: 1400, degree of saponification: 88 mol%]
The aqueous solution was cast on a hot drum at 93 ° C., formed into a film, and further dried to a water content of 6% to produce a water-soluble film having a thickness of 40 μm.

[Preparation of Emboss Roll] The emboss roll had a 40-mesh silk shape (depth: 180 μm), and was subjected to a sand blast treatment so that Ra = 3 μm to give a satin finish. Such sandblasting is performed using a blasting device (“FDO type” manufactured by Fuji Seisakusho).
Nozzle pressure 3 kg / cm ² , ceramic abrasive # 100
It was carried out in.

[Backup Roll] A rubber roll coated with synthetic rubber and manufactured by Yuri Roll Co. (roll surface hardness A80 °) was used.

[Production Method of Water-Soluble Embossed Film] The above film was embossed using an embossing roll and a backup roll. First, the pressing force between the embossing roll heated to 120 ° C. and the backup roll heated to 65 ° C. is 50 kg / cm and the pressure is 10 m / mi.
Passing through the water-soluble film at the speed of n, embossing is performed to produce a water-soluble embossed film having a satin pattern of Ra = 2.4 μm and a concavo-convex pattern (silk pattern) of 40 μm and a depth of 140 μm. did. The following evaluation was performed about the obtained film.

(Blocking resistance) The obtained water-soluble embossed film (100 m) is wound into a roll (with a branch pipe diameter of about 3 inches) at a tension of 3 kg / m and a winding speed of 10 m / min.
After being left for 3 months in an atmosphere of 0 ° C. × 80 RH%, the roll was released and evaluated as follows.・ ・ ・: No blocking was observed, and the core could be unwound smoothly up to the core. ×: Blocking was observed at the core, and a part of the film was damaged when unwound.

B. The obtained water-soluble embossed film (2
00 × 200 mm), and 100 m
Place a 10kg stainless steel cylinder with mφ, 60 ℃ × 90
The state after standing for 7 days in an atmosphere of% RH was evaluated as follows.・ ・ ・: No blocking was observed ×: blocking was observed

(Tint) The obtained water-soluble embossed film was illuminated with an incandescent lamp at an oblique angle of 45 ° from the film surface, and visually observed from the opposite 45 ° direction, and evaluated as follows. ○ ・ ・ ・ Shining is not recognized × ・ ・ ・ Shining is recognized

(Luxury Quality) The appearance of the obtained water-soluble embossed film was evaluated as follows.・ ・ ・: There is a three-dimensional effect, and a high-quality impression is recognized. × ・ ・ ・ Less expensive

(Pinhole Resistance) The obtained water-soluble embossed film was placed on a filter paper, and a pinhole test solution (0.1% methanol solution of Rhodamine B, manufactured by Kishida Chemical Co., Ltd.) was poured over the filter paper. It was evaluated by measuring the bleeding point due to a pinhole on the back surface. still,
The evaluation criteria are as follows. ○ ・ ・ ・ No exudation × ・ ・ ・ Exudation

Example 2 The procedure of Example 1 was repeated except that the sandblasted nozzle pressure condition was adjusted to change the satin pattern of the embossing roll so that Ra = 1 μm. Ra = 0.8 μm
A water-soluble embossed film having a satin pattern and a 40-mesh silk pattern having a depth of 140 μm was obtained and evaluated in the same manner.

Example 3 The procedure of Example 1 was repeated, except that the shape of the embossing roll was changed to 50 mesh, and Ra = 2.4 μm.
A water-soluble embossed film having a pear-skin pattern of m and a mesh pattern of 50 mesh and a depth of 140 μm was obtained and similarly evaluated.

Example 4 The procedure of Example 1 was repeated, except that the depth of the embossing roll was changed to 250 μm, and Ra = 2.
To obtain a water-soluble embossed film in which a 4 μm satin pattern and a 200 μm deep silk pattern with 40 mesh were formed,
Evaluation was performed similarly.

Comparative Example 1 The procedure of Example 1 was repeated except that the sandblasted nozzle pressure condition was adjusted to change the satin finish of the embossing roll so that Ra = 0.1 μm.
To obtain a water-soluble embossed film formed with a 8 μm satin pattern and a 140 μm deep silk pattern with 40 mesh,
Evaluation was performed similarly.

Comparative Example 2 The procedure of Example 1 was repeated except that the sandblasting nozzle pressure condition was adjusted to change the satin finish of the embossing roll so that Ra = 12 μm, and Ra = 10 μm.
A water-soluble embossed film on which a satin pattern and a 40-mesh silk pattern with a depth of 140 μm were formed was evaluated in the same manner.

Comparative Example 3 In Example 1, the embossing roll was changed to a silk shape of 120.
The same operation was performed except that the mesh was changed to Ra = 2.4.
to obtain a water-soluble embossed film in which a matte pattern of 140 μm and a silk pattern of 140 μm in depth with 120 mesh were formed,
Evaluation was performed similarly.

Comparative Example 4 The procedure of Example 1 was repeated, except that the depth of the embossing roll was changed to 55 μm, and Ra = 2.4.
A water-soluble embossed film having a μm satin pattern and a 40-mesh silk pattern having a depth of 44 μm was obtained and similarly evaluated.

Comparative Example 5 The procedure of Example 1 was repeated, except that the depth of the embossing roll was changed to 400 μm, and Ra = 2.
A water-soluble embossed film having a matte pattern of 4 μm and a silk pattern having a depth of 320 μm with 40 mesh was obtained.
Evaluation was performed similarly. Table 1 shows the results of Examples and Comparative Examples.

[0042] Table 1 Blocking resistance shine luxury feel pinhole resistance A B Example 1 ○ ○ ○ ○ ○ 〃 2 ○ ○ ○ ○ ○ 〃 3 ○ ○ ○ ○ ○ 〃 4 ○ ○ ○ ○ ○ Comparative Example 1 × × × × ○ 〃 2 ○ ○ ○ ○ × 〃 3 × × × × ○ ４ 4 × × × × ○ ５ 5 ○ ○ ○ ○ ×

[0043]

According to the present invention, embossing is performed by passing a water-soluble film between an embossing roll having a pear-skin pattern and an embossed shape engraved thereon and a backup roll, so that the film has a surface roughness (Ra). Since a pear-skin pattern of 0.1 to 8 μm and a concavo-convex pattern having a depth of 50 to 300 μm with a mesh size of 100 mesh or less are formed, the obtained water-soluble embossed film can be stored in a roll or stored under high temperature and high humidity. It has excellent blocking resistance even when left for a long period of time, has no shine, has excellent luxury, and has excellent pinhole resistance. Such films are used for pesticides, drugs, dyes, detergents, fertilizers, cosmetics, and physiology. It is useful as a packaging material for articles and the like, and particularly very useful for unit packaging of various chemicals and the like.

Claims (4)

[Claims] An embossing process is carried out by passing a water-soluble film between an embossing roll and a backup roll on which a concavo-convex pattern having a satin finish is imprinted, and the surface of the film has a surface roughness (Ra) of 0.1 to 0.1. A method for producing a water-soluble embossed film, comprising forming a matte pattern of 8 μm and a concavo-convex pattern having a depth of 50 to 300 μm with 100 mesh or less. 2. The method for producing a water-soluble embossed film according to claim 1, wherein the uneven pattern is a silk pattern. 3. The method according to claim 1, wherein the water-soluble film is a polyvinyl alcohol film.
A method for producing the water-soluble embossed film according to the above. 4. An embossing roll having a surface roughness (Ra) of 0.
The method for producing a water-soluble embossed film according to any one of claims 1 to 3, wherein the water-soluble embossed film has a matte pattern of 3 to 10 µm and an uneven shape having a depth of 100 to 400 µm.