JP2002020507A - Polyvinyl alcohol-based water-soluble film and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a PVA-based water-soluble film whose blocking is scarcely caused during the storage of the film, which has good impact resistance, and whose bag is hardly broken, and to provide a method for producing the water- soluble film. SOLUTION: This polyvinyl alcohol-based water-soluble film characterized by comprising 100 pts.wt. of polyvinyl alcohol, 5 to 30 pts.wt. of a plasticizer, and 0.01 to 2 pts.wt. of a surfactant, and having unevenness with a surface roughness of >=1S on at least one side of the film. The method for producing the polyvinyl alcohol-based water-soluble film, characterized by drying a film- forming solution comprising 100 pts.wt. of polyvinyl alcohol, 5 to 30 pts.wt. of a plasticizer, and 0.01 to 2 pts.wt. of a surfactant on a 80 to 110 deg.C metal surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a film comprising polyvinyl alcohol (hereinafter, polyvinyl alcohol may be abbreviated as "PVA"), a specific amount of a plasticizer and a specific amount of a surfactant, and a film. Characterized in that at least one surface has a specific surface roughness.
The present invention relates to a VA-based water-soluble film and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, a certain amount of agricultural chemicals and other chemicals are hermetically sealed and packaged in a water-soluble film, and when used, put into water as it is in its packaging form, and the contents are dissolved or dissolved in water together with the packaging film. The method of dispersing and using is being performed. The advantages of this unit package are that it can be used without directly touching dangerous chemicals when used, that it is not necessary to weigh it when used because a fixed amount is packed, and that the use of containers or bags packed or transported drugs The subsequent processing is unnecessary or simple.

Conventionally, a partially saponified PVA film has been used as such a water-soluble film for unit packaging. These water-soluble films are easily soluble in cold or hot water and have properties such as excellent mechanical strength.

[0004]

Since pesticides are often used in early spring, packaging, transportation and storage of pesticides are often performed in winter. There is a need for a water-soluble film that satisfies the required performances, such as low blocking properties during storage and little bag breakage during transportation. However, the conventional P
The VA film has a problem that the film is rigid and easy to block, and the impact resistance is low and the bag is easily broken.

An object of the present invention is to eliminate the above-mentioned disadvantages, to prevent blocking during storage of the film, to have a good impact resistance and to prevent the bag from breaking, and to provide a method for producing the PVA-based water-soluble film. Is to provide.

[0006]

Means for Solving the Problems As a result of intensive studies in view of the present situation, the present inventor has found that a specific amount of a plasticizer and a specific amount of a surfactant are blended with PVA, and at least one surface of the film is formed. Having a specific surface roughness
The present inventors have found that a water-based water-soluble film and a method for producing the same are very useful as a PVA-based water-soluble film having the desired excellent properties and a method for producing the same, and have completed the present invention.

That is, in the present invention, 5 to 30 parts by weight of a plasticizer and 0.01 to 10 parts by weight of a surfactant are added to 100 parts by weight of PVA.
A PVA-based water-soluble film, wherein 2 parts by weight are blended, and at least one surface of the film has irregularities with a surface roughness of 1S or more;
80 to 1 parts by weight of a film forming stock solution obtained by mixing 5 to 30 parts by weight of a plasticizer and 0.01 to 2 parts by weight of a surfactant with respect to parts by weight.
A process for producing the water-soluble film, characterized by drying on a metal surface at 10 ° C.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. PVA used in the present invention is a polymer obtained by polymerizing a vinyl ester monomer, usually saponified in an alcohol solution using an alkali or acid catalyst, and the vinyl ester unit is converted to a vinyl alcohol unit. Can be used.

Examples of the vinyl ester monomers used in the production of PVA include vinyl acetate, vinyl propionate, vinyl formate, vinyl versatate, vinyl pivalate, and the like. Alternatively, two or more kinds can be used. Among them, it is preferable to use vinyl acetate which is industrially produced and is advantageous in cost.

[0010] The PVA of the present invention may contain other monomer units as long as the gist of the present invention is not impaired. Examples of such a monomer unit include α-olefins such as ethylene, propylene, 1-butene, isobutene, and 1-hexene, acrylic acid and salts thereof, methyl acrylate, ethyl acrylate, and n-acrylate. Acrylates such as propyl, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, methacrylic acid and the like Salt, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, methacrylic acid 2
Methacrylic esters such as -ethylhexyl, dodecyl methacrylate, octadecyl methacrylate, acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid and salts thereof, acrylamidopropyl Acrylamide derivatives such as dimethylamine and its salts or quaternary salts thereof, N-methylolacrylamide and its derivatives,
Methacrylamide, N-methylmethacrylamide, N-
Methacrylamide derivatives such as ethyl methacrylamide, methacrylamide propanesulfonic acid and salts thereof, methacrylamidopropyldimethylamine and salts or quaternary salts thereof, N-methylol methacrylamide and derivatives thereof, N-vinylpyrrolidone, N-vinylformamide N-vinylamides such as N-vinylacetamide, allyl ethers having a polyalkylene oxide in the side chain, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, vinyl ethers such as t-butyl vinyl ether, dodecyl vinyl ether and stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; , Vinyl halides such as vinylidene chloride, vinyl fluoride and vinylidene fluoride, allyl compounds such as allyl acetate and allyl chloride, maleic acid and its salts or esters, vinyl silyl compounds such as vinyltrimethoxysilane, and isopropenyl acetate There is.
The amount of modification is usually 5 mol% or less.

As the polymerization method of the polyvinyl ester copolymer, conventionally known methods such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method and an emulsion polymerization method can be applied. As the polymerization catalyst, depending on the polymerization method, an azo catalyst, a peroxide catalyst,
A redox catalyst or the like is appropriately selected.

For the saponification reaction of the copolymer, alcoholysis and hydrolysis with a conventionally known alkali catalyst or acid catalyst can be applied. Among them, N using methanol as a solvent
A saponification reaction using an aOH catalyst is simple and most preferable.

The degree of polymerization (viscosity average degree of polymerization) of PVA is not particularly limited, but in the case of a water-soluble film, the mechanical properties of the film are also important. Is required, and the viscosity average degree of polymerization is from 300 to 1000 in view of the strength and toughness of the film.
It is preferably 0, more preferably 500 to 8000. Further, from the viewpoint of water solubility, 500 to 2000 is particularly preferable. If the viscosity average polymerization degree is less than 300, the film strength tends to be weak, and if it is more than 10,000, the viscosity of the film forming raw material solution used when forming the film increases, and the workability tends to decrease. is there.

The degree of saponification of PVA is from 80 to 95 mol%, preferably from 82 to 92 mol%, particularly preferably from 85 to 90 mol%, from the viewpoint of water solubility. When the degree of saponification is less than 80 mol% or when the degree of saponification is more than 95 mol%, the water solubility is not sufficient, which is not preferable. The degree of saponification can be measured by the method described in JIS.

In general, a water-soluble film is transported, stored, and used even in a high-temperature and high-humidity region or a cold region, so that the film must have high strength and toughness. In particular, impact resistance at low temperatures is required. Therefore, various plasticizers are used to lower the glass transition point of the film.

The plasticizer used in the present invention is PV
There is no particular limitation as long as it is generally used as a plasticizer of A, for example, glycerin, diglycerin, diethylene glycol, trimethylolpropane, triethylene glycol, dipropylene glycol, polyhydric alcohols such as propylene glycol, polyethylene glycol, Polyethers such as polypropylene glycol; phenol derivatives such as bisphenol A and bisphenol S; amide compounds such as N-methylpyrrolidone; and compounds obtained by adding ethylene oxide to polyhydric alcohols such as glycerin, pentaerythritol and sorbitol. And one or more of these can be used.

The mixing ratio of the plasticizer is 5 to 30 parts by weight, preferably 8 to 25 parts by weight, more preferably 10 to 20 parts by weight, per 100 parts by weight of PVA.
When the mixing ratio of the plasticizer is less than 5 parts by weight, the impact resistance is insufficient. On the other hand, if the blending ratio of the plasticizer exceeds 30 parts by weight, the bleed out of the plasticizer becomes large, and the film is easily blocked, which is not preferable.
In addition, the stiffness of the obtained film (process passability of bag making machine etc.)
In view of the above, it is preferable to mix them in a proportion of 30 parts by weight or less. From the viewpoint of improving the water solubility of the obtained film, the larger the amount of the plasticizer, the better. In addition, the heat sealing temperature varies depending on various factors. Particularly, as the blending amount of the plasticizer increases, the heat sealing temperature decreases, and the productivity at the time of forming a film is improved. In particular, it is preferable to mix the plasticizer at such a ratio that the heat sealing temperature of the obtained film is 170 ° C. or lower, and it is more preferable to mix the plasticizer at a ratio that is 160 ° C. or lower.

The PVA of the present invention may further contain an inorganic filler, if necessary. As the inorganic filler used in the present invention, for example, silica, heavy, light or surface-treated calcium carbonate, aluminum hydroxide, aluminum oxide, titanium oxide, diatomaceous earth,
Barium sulfate, calcium sulfate, zeolite, zinc oxide, silicic acid, silicate, mica, magnesium carbonate, kaolin, halothite, pyroferrite, clay such as sericite, talc, etc., and one or two of these can be mentioned. More than one species can be used. Among these, it is preferable to use silica or talc from the viewpoint of dispersibility in PVA. The particle size of the inorganic filler is
1 μm or more is preferred from the viewpoint of anti-blocking properties.
The thickness is preferably 10 μm or less from the viewpoint of dispersibility in VA. In order to achieve both performances, it is more preferable that the particle size is about 1 to 7 μm.

The type of the surfactant of the present invention is not particularly limited, but an anionic or nonionic surfactant is preferable. As the anionic surfactant, for example, a carboxylic acid type such as potassium laurate, a sulfate type such as octyl sulfate, and a sulfonic acid type such as dodecylbenzenesulfonate are preferable. Examples of nonionic surfactants include, for example, alkyl ether type such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether,
Alkyl phenyl ether type such as polyoxyethylene octyl phenyl ether, alkyl ester type such as polyoxyethylene laurate, alkyl amine type such as polyoxyethylene lauryl amino ether, alkyl amide type such as polyoxyethylene lauric amide, polyoxy Nonionic surfactants such as polypropylene glycol ether type such as ethylene polyoxypropylene ether, alkanolamide type such as oleic acid diethanolamide, and allyl phenyl ether type such as polyoxyalkylene allyl phenyl ether are preferable. One or a combination of two or more of these surfactants can be used. Alkyl ether surfactants are preferred from the viewpoint of anti-blocking properties, and among them, polyoxyethylene oleyl ether is particularly preferred. The addition amount of the surfactant is 0.01 to 2 parts by weight, preferably 0.1 to 1 part by weight, and particularly preferably 0.2 to 0.5 part by weight based on 100 parts by weight of PVA. If the amount is less than 0.01 part by weight, the peelability between a metal surface such as a die or a drum of a film forming apparatus and a formed film or a stock solution of a film is lowered, and it is not preferable because production becomes difficult. If the added amount is more than 2 parts by weight, it is unfavorable because it is eluted on the film surface and causes blocking, which may lower the handleability.

The composition of the present invention comprising a PVA, a plasticizer, a surfactant and, if necessary, an inorganic filler may further contain, if necessary, a coloring agent, a fragrance, a bulking agent, an antifoaming agent, a release agent,
A normal additive such as an ultraviolet absorber may be appropriately compounded. Also, if necessary, a different type of PVA from the PVA of the present invention, as long as the effects of the present invention are not lost.
Water-soluble polymers such as starch, carboxymethylcellulose, methylcellulose and hydroxymethylcellulose may be blended.

The stock solution for obtaining the PVA-based water-soluble film of the present invention comprises a PVA, a plasticizer, a surfactant, and, if necessary, an inorganic filler and other components described above.
It can be produced by mixing in a desired manner.

Using the above-mentioned stock solution of the present invention, a film forming method generally used for forming a cast film, for example, a casting film forming method, a wet film forming method, a dry film forming method, A PVA-based water-soluble film can be formed by a film forming method such as an extrusion film forming method and a melt film forming method. A composition comprising the above-mentioned PVA, a plasticizer, a surfactant and, if necessary, an inorganic filler and other components as water for forming a film is prepared by using water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, methanol, n-propanol, i-propanol. In order to prepare a uniform solution dissolved in a solvent such as phenol, the components constituting the PVA-based composition may be mixed in advance and then dissolved in the solvent, or the PVA-based composition may be dissolved. After dissolving the respective components in a solvent, the solutions may be mixed. The concentration of the film forming stock solution is preferably 50% by weight or less (solvent content is more than 50% by weight) from the viewpoint of viscosity, and 35% by weight or less (solvent content) from the viewpoint that a mat state is easily formed on the surface of the formed film. Is more preferably 65% by weight or more.

The temperature of the metal surface on which the stock solution is cast is 80 to 110 ° C., preferably 85 to 105 ° C.,
90-100 ° C. is particularly preferred. If the temperature is lower than 80 ° C., the peelability after drying tends to be insufficient, and the blocking property of the obtained film may be deteriorated. If the temperature is higher than 110 ° C., the film may foam and pores may be formed, which is not preferable.

The thickness of the PVA-based water-soluble film of the present invention is preferably from 10 to 100 μm, and more preferably from 30 to 80 μm from the viewpoint of the balance between strength and water solubility.

The PVA-based water-soluble film of the present invention requires that at least one surface of the film has irregularities with a surface roughness of 1S or more. The unevenness of the surface roughness is more preferably 2S or more, and particularly preferably 3S or more. If it is smaller than 1S, the anti-blocking property is insufficient. The upper limit is not particularly limited, but if the surface roughness is too large, the film strength will be low and the film will be easily broken.
0S or less is preferable.

The surface roughness of the PVA-based water-soluble film of the present invention is determined by adjusting the humidity of the film to 20 ° C. and 40% RH.
Using a surface roughness meter having a tip R of 0.3 μm, the film surface was randomly measured 5 times at a distance of 30 cm, and the average value is shown. Incidentally, the surface roughness of the present invention,
Maximum height (Rma) defined in JIS B0601
x).

In order to exhibit the anti-blocking property of the PVA-based water-soluble film of the present invention, at least one surface of the film must have the above-mentioned unevenness having a surface roughness of 1S or more. Various methods can be used. For example, the surface of the water-soluble film can be roll-matted, a powder for preventing blocking such as silica or starch can be applied, or embossing can be performed. The film surface can be formed into a roll mat by forming fine irregularities on a roll in contact with the film before drying during film formation. The embossing process can be generally performed after the film is formed by nip between an embossing roll and a rubber roll while applying heat or pressure. Although application of the powder has a large effect of preventing blocking, it may not be used depending on the application. Therefore, it is preferable to apply a roll mat or emboss to prevent blocking. It is particularly preferable to form a roll mat because of a large anti-blocking effect.

The surface roughness of the matted roll metal surface is 1S or more, preferably 2S or more, particularly preferably 3S or more. If it is smaller than 1S, the anti-blocking property is insufficient. The upper limit is not particularly limited, but is preferably 10 S or less because air bubbles may be generated depending on the viscosity and pores may be opened. In addition, the surface roughness of the metal surface
It is the maximum height (Rmax) defined in B0601.

The PVA-based water-soluble film of the present invention often needs to have impact resistance because a bag is often prepared and a medicine or the like is packaged. As an index, the impact rupture strength at 20 ° C. is 5
It is preferably at least 10 kg · cm
It is more preferably at least 15 kg · cm.

The PVA-based water-soluble film of the present invention is excellent not only in solubility in water but also in heat sealability.
It is very useful as a material for packaging, particularly unit packaging, for use after being dissolved in water. The packaging bag produced from the PVA-based water-soluble film of the present invention dissolves promptly simply by being put into water, and its contents are released into water.

[0031]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. In addition, the method of measuring the water solubility of the PVA-based water-soluble film, the method of evaluating the blocking property and the impact resistance in the examples were performed by the following methods.

Method for measuring water solubility of water-soluble film: The water solubility of a PVA-based water-soluble film in the present invention is a value for a water-soluble film having a thickness of 40 μm. 2
Install a magnetic stirrer in a constant temperature bath at 0 ° C. A 1 L glass beaker containing 1 L of distilled water is put in a bath, and stirring is performed at 250 rpm using a 5 cm rotor. After the temperature of the distilled water in the beaker reaches 20 ° C., the measurement of water solubility is started. The film was cut into a square of 40 × 40 mm, sandwiched between slide mounts, immersed in water with stirring at 20 ° C., and the dissolution state of the film was observed. The time until the film dissolved (seconds) was measured.
When a film having a thickness different from 40 μm is used, the value is converted into a value of 40 μm according to the following equation (1).

Dissolution time (sec) = [40 / film thickness (μm)] ² × actual dissolution time (sec) (1)

Evaluation method of blocking property: 20 ° C., 6
A 15 × 20 cm film conditioned for one week at 5% RH is placed on a 100 × 100 cm film so that the uneven surface is in the same direction.
The stacked pieces were sandwiched between two glass plates and placed on a 1 kg weight and stored for one week. The ease of peeling at the center of the stacked films was evaluated.

Measurement of impact resistance: The impact rupture strength was measured using a film impact tester according to ASTM D-3420.

Example 1 20 parts by weight of glycerin as a plasticizer and 0.1 part of polyoxyethylene oleyl ether as a surfactant were added to 100 parts by weight of PVA having a degree of saponification of 88 mol% and a degree of polymerization of 1700.
2 parts by weight and water were added to prepare a film forming stock solution having a uniform concentration of 20% by weight (water content: 80% by weight) at a temperature of 95 ° C.
The film was cast on a stainless steel roll having a surface roughness of 3 ° C at 95 ° C and dried to obtain a film having a thickness of 40 µm and a surface roughness of 3S on the stainless steel roll side. The water solubility (time until dissolution in water) of this film was 30 seconds at 20 ° C. The results of the blocking test were good, and the impact rupture strength (impact resistance) was 26 kg · cm.

Example 2 10 parts by weight of glycerin / 10 parts by weight of diglycerin as a plasticizer and 0.5 parts by weight of polyoxyethylene lauryl ether as a surfactant based on 100 parts by weight of PVA having a degree of saponification of 88 mol% and a degree of polymerization of 1700. And water are added to prepare a stock solution having a uniform concentration of 30% by weight (water content: 70% by weight) at a temperature of 95 ° C., cast on a stainless roll having a surface roughness of 2S at 90 ° C., and dried. Due to thickness 40
A film having a thickness of 2 μm and a surface roughness of 2S on the stainless steel roll side was obtained. The water solubility (time until dissolution in water) of this film was 35 seconds at 20 ° C. The blocking property was good, and the impact rupture strength (impact resistance) was 24 kg · cm.

Example 3 20 parts by weight of glycerin as a plasticizer and 0.1 part of polyoxyethylene oleyl ether as a surfactant were added to 100 parts by weight of PVA having a degree of saponification of 88 mol% and a degree of polymerization of 1700.
2 parts by weight and water were added to prepare a film forming stock solution having a uniform concentration of 20% by weight (water content: 80% by weight) at a temperature of 95 ° C.
The film was cast on a stainless roll having a surface roughness of 1.5 S at a temperature of 95 ° C. and dried to obtain a film having a thickness of 40 μm and a surface roughness of 1.5 S on the stainless roll side. The water solubility (time until dissolution in water) of this film is 4 at 20 ° C.
It was 0 seconds. The blocking property was good, and the impact rupture strength (impact resistance) was 25 kg · cm.

Comparative Example 1 A film having a thickness of 40 μm and a surface roughness of 3S was obtained in the same manner as in Example 1, except that glycerin was not added to the stock solution for film formation. Water solubility of this film (time to dissolve in water)
Was 52 ° C. at 20 ° C. The blocking property was good, and the impact rupture strength (impact resistance) was 4 kg · cm.

Comparative Example 2 Glycerin was added to 100 parts by weight of PVA in a stock solution for film formation.
Except for adding 0 parts by weight, a thickness of 4
A film having a thickness of 0 μm and a surface roughness of 3S was obtained. The water solubility (time until dissolution in water) of this film was 21 seconds at 20 ° C. The blocking property was poor, and the film adhered and was difficult to peel. Impact burst strength (impact resistance) is 32k
g · cm.

Comparative Example 3 A film was prepared in the same manner as in Example 1 except that no surfactant was added to the stock solution for film formation. This film was in intimate contact with the stainless steel roll and had poor releasability, and a satisfactory film could not be obtained.

Comparative Example 4 A film having a thickness of 40 μm and a surface roughness of 3S was obtained in the same manner as in Example 1 except that 5 parts by weight of polyoxyethylene lauryl ether was added to 100 parts by weight of PVA to the stock solution for film formation. . The water solubility (time until dissolution in water) of this film was 28 seconds at 20 ° C. The blocking property was poor, and it was difficult to peel off due to close contact. The impact rupture strength (impact resistance) was 20 g · cm.

Comparative Example 5 A film was obtained in the same manner as in Example 1 except that the stock solution was dried on a stainless roll having a surface roughness of 3S at 70 ° C. This film was in intimate contact with the stainless steel roll and had poor releasability, and a satisfactory film could not be obtained.

Comparative Example 6 A film having a thickness of 40 μm was prepared in the same manner as in Example 1, except that the stock solution was dried on a stainless steel roll having a surface roughness of 3S at 120 ° C.
m and a film having a surface roughness of 15S. This film foamed to generate fine holes, and a satisfactory film could not be obtained.

[0045]

The PVA-based water-soluble film of the present invention has not only good water-solubility but also excellent blocking resistance and impact resistance. It is preferably used for film applications.

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 4F071 AA29 AA51 AC05 AC06 AC11 AC12 AE04 AE10 AH04 BA02 BB02 BC01 BC16 4J002 BE021 CH022 CH023 CH053 EC046 EC056 ED026 EG037 EJ036 EU026 EV187 EV247 FD010 FD022 FD02 FD0300

Claims (5)

[Claims] 1. A plasticizer of 5 to 30 parts by weight and a surfactant of 0.01 to 2 parts per 100 parts by weight of polyvinyl alcohol.
A polyvinyl alcohol-based water-soluble film characterized by being mixed with parts by weight and having at least one surface of the film having irregularities with a surface roughness of 1S or more. 2. The water-soluble film according to claim 1, wherein the surfactant is an alkyl ether surfactant. 3. A plasticizer of 5 to 30 parts by weight and a surfactant of 0.01 to 2 parts per 100 parts by weight of polyvinyl alcohol.
The method for producing a polyvinyl alcohol-based water-soluble film according to claim 1, wherein the film-forming stock solution prepared by mixing parts by weight is dried on a metal surface at 80 to 110 ° C. 4. The method for producing a water-soluble film according to claim 3, wherein the surfactant is an alkyl ether surfactant. 5. The method for producing a water-soluble film according to claim 3, wherein the metal surface has irregularities with a surface roughness of 1S or more.