JP5122040B2 - Polyvinyl alcohol-based water-soluble film and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention comprises a specific amount of a plasticizer and a specific amount of a surfactant blended with polyvinyl alcohol (hereinafter, polyvinyl alcohol may be abbreviated as “PVA”), and at least one surface of the film is a process for producing PVA-based water-soluble fill beam characterized by having a specific surface roughness.
[0002]
[Prior art]
In recent years, various chemicals such as agricultural chemicals are sealed and packaged in a certain amount in a water-soluble film, put into the water in its packaging form at the time of use, and the contents are used by dissolving or dispersing the whole packaging film in water. The method is to be done. The advantages of this unit packaging are that it can be used without direct contact with hazardous chemicals when used, that it does not need to be weighed because a certain amount is packaged, and that a container or bag that packs or transports drugs is used. The later processing is unnecessary or simple.
[0003]
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 water and hot water, and have performances such as excellent mechanical strength.
[0004]
[Problems to be solved by the invention]
Since agricultural chemicals are often used in early spring, packaging, transportation and storage of agricultural chemicals are often performed in winter. There is a need for a water-soluble film that satisfies the required performance such as low blocking during storage and less bag breakage during transportation. However, the conventional PVA film has a problem that the film has no waist and is easy to block, or has a low impact resistance and is easy to break.
[0005]
An object of the present invention eliminates the above drawbacks, occur blocking in the film storage difficult, impact resistance and to provide a method for producing good breakage hardly PVA-based water-soluble fill beam.
[0006]
[Means for Solving the Problems]
As a result of diligent study in view of the present situation, the present inventor has formulated a specific amount of plasticizer and a specific amount of surfactant into PVA, which will be described later , and at least one surface of the film has a specific surface roughness. PVA-based water-soluble fill beam fabrication process with is found to be very useful as a method for producing PVA-based water-soluble fill beam which has excellent properties for the purpose, and completed the present invention.
[0007]
That is, in the present invention , a film-forming stock solution formed by blending 5 to 30 parts by weight of a plasticizer and 0.01 to 2 parts by weight of a surfactant with respect to 100 parts by weight of PVA has a surface roughness of 1S or more at 80 to 110 ° C. A film formed by blending 5 to 30 parts by weight of a plasticizer and 0.01 to 2 parts by weight of a surfactant with respect to 100 parts by weight of PVA , which is dried on a metal surface having irregularities of 10S or less. The at least one surface of this invention relates to the manufacturing method of the PVA-type water - soluble film which has the unevenness | corrugation of surface roughness 1S or more and 10S or less .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in further detail below.
The PVA used in the present invention is a polymer obtained by polymerizing a vinyl ester monomer, usually saponified using an alkali or acid catalyst in an alcohol solution, and the vinyl ester unit is converted to a vinyl alcohol unit. Can be used.
[0009]
Examples of the vinyl ester monomers used for the production of PVA include vinyl acetate, vinyl propionate, vinyl formate, vinyl versatate, vinyl pivalate, and the like, one or two of these. The above can be used. Among these, it is preferable to use vinyl acetate which is industrially produced and advantageous in terms of 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 monomer units include α-olefins such as ethylene, propylene, 1-butene, isobutene, and 1-hexene, acrylic acid and salts thereof, methyl acrylate, ethyl acrylate, and acrylic acid n-. Acrylic acid esters 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 its Salt, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, Such as octadecyl methacrylate Luric acid esters, acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid and its salt, acrylamidopropyldimethylamine and its salt or quaternary salt thereof, N Acrylamide derivatives such as methylolacrylamide and derivatives thereof, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and salts thereof, methacrylamidepropyldimethylamine and salts thereof or quaternary salts thereof, N -N-biphenyl such as methacrylamide derivatives such as methylolmethacrylamide and its derivatives, N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, etc. Nylamides, allyl ethers having 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, t-butyl vinyl ether, dodecyl vinyl ether, stearyl Vinyl ethers such as vinyl ether, nitriles such as acrylonitrile and methacrylonitrile, vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride and vinylidene fluoride, allyl compounds such as allyl acetate and allyl chloride, maleic acid and salts thereof Alternatively, there are esters thereof, vinylsilyl compounds such as vinyltrimethoxysilane, and isopropenyl acetate. The amount of modification is usually 5 mol% or less.
[0011]
As the polymerization method of the polyvinyl ester copolymer, conventionally known methods such as solution polymerization method, bulk polymerization method, suspension polymerization method and emulsion polymerization method can be applied. As the polymerization catalyst, an azo catalyst, a peroxide catalyst, a redox catalyst or the like is appropriately selected according to the polymerization method.
[0012]
For the saponification reaction of the copolymer, alcoholysis or hydrolysis with a conventionally known alkali catalyst or acid catalyst can be applied. Of these, a saponification reaction with a NaOH catalyst using methanol as a solvent is simple and most preferred.
[0013]
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, and strong strength and flexibility are required even at a thin thickness of 10 to 100 μm. In view of the strength and toughness of the film, the viscosity average degree of polymerization is preferably from 300 to 10,000, and more preferably from 500 to 8,000. Furthermore, 500 to 2000 is particularly preferable from the viewpoint of water solubility. When the viscosity average polymerization degree is less than 300, the film strength tends to be weak, and when 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.
[0014]
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. Even when the saponification degree is less than 80 mol% and when the saponification degree is more than 95 mol%, the water solubility is insufficient, which is not preferable. The degree of saponification can be measured by the method described in JIS.
[0015]
In general, a water-soluble film is transported, stored, and used even in a hot and humid region or a cold region, so that the strength and toughness of the film are required. In particular, impact resistance at low temperatures is required. Therefore, various plasticizers are used to lower the glass transition point of the film.
[0016]
The plasticizer used in the present invention is not particularly limited as long as it is generally used as a plasticizer for PVA. For example, glycerin, diglycerin, diethylene glycol, trimethylolpropane, triethylene glycol, dipropylene glycol, propylene glycol Polyhydric alcohols such as polyethylene glycol and polypropylene glycol, phenol derivatives such as bisphenol A and bisphenol S, amide compounds such as N-methylpyrrolidone, and polyhydric alcohols such as glycerin, pentaerythritol and sorbitol Examples thereof include compounds obtained by adding ethylene oxide to one of these, and one or more of these can be used.
[0017]
The blending ratio of the plasticizer is 5 to 30 parts by weight with respect to 100 parts by weight of PVA, preferably 8 to 25 parts by weight, and more preferably 10 to 20 parts by weight. When the blending ratio of the plasticizer is less than 5 parts by weight, the impact resistance is insufficient. On the other hand, when the blending ratio of the plasticizer exceeds 30 parts by weight, the bleed-out of the plasticizer increases and the film is likely to block, which is not preferable. Moreover, it is preferable to mix | blend in the ratio of 30 weight part or less also from the point of the waist (process passability, such as a bag making machine) of the film obtained. From the viewpoint of improving the water solubility of the resulting film, the greater the amount of plasticizer, the better. Further, the heat seal temperature varies depending on various factors, but in particular, the greater the amount of the plasticizer, the lower the heat seal temperature, which is preferable because the productivity at the time of making a film is improved. In particular, the plasticizer is preferably blended at a rate such that the heat seal temperature of the resulting film is 170 ° C. or less, and more preferably blended at a rate such that the heat seal temperature is 160 ° C. or less.
[0018]
The PVA of the present invention can further contain an inorganic filler as necessary. Examples of the inorganic filler used in the present invention include silica, heavy, light or surface-treated calcium carbonate, aluminum hydroxide, aluminum oxide, titanium oxide, diatomaceous earth, barium sulfate, calcium sulfate, zeolite, zinc oxide, and silicic acid. , Silicate, mica, magnesium carbonate, kaolin, halosite, pyroferrite, sericite and other clays, talc, and the like, and one or more of these can be used. Among these, silica or talc is preferably used particularly from the viewpoint of dispersibility in PVA. The particle diameter of the inorganic filler is preferably 1 μm or more from the viewpoint of blocking prevention, and is preferably 10 μm or less from the viewpoint of dispersibility in PVA. In order to achieve both performances, a particle size of about 1 to 7 μm is more preferable.
[0019]
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 anionic surfactant such as dodecylbenzene sulfonate are suitable. Examples of nonionic surfactants include alkyl ether types such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether, alkylphenyl ether types such as polyoxyethylene octylphenyl ether, and alkyl ester types such as polyoxyethylene laurate. , Alkylamine type such as polyoxyethylene lauryl amino ether, alkylamide type such as polyoxyethylene lauric acid amide, polypropylene glycol ether type such as polyoxyethylene polyoxypropylene ether, alkanolamide type such as oleic acid diethanolamide, poly Nonionic surfactants such as allyl phenyl ether type such as oxyalkylene allyl phenyl ether are preferred. These surfactants can be used alone or in combination of two or more. From the viewpoint of antiblocking properties, alkyl ether surfactants are preferable, and polyoxyethylene oleyl ether is particularly preferable.
As addition amount of surfactant, it is 0.01-2 weight part with respect to 100 weight part of PVA, 0.1-1 weight part is more preferable, 0.2-0.5 weight part is especially preferable. If the amount is less than 0.01 parts by weight, the peelability between the metal surface such as a die or drum of the film forming apparatus and the formed film or film stock solution is lowered, which is not preferable. If the amount added is more than 2 parts by weight, it is not preferable because it may elute on the film surface, cause blocking, and reduce the handleability.
[0020]
The composition comprising the PVA of the present invention, a plasticizer, a surfactant and, if necessary, an inorganic filler is further usually a colorant, a fragrance, an extender, an antifoaming agent, a release agent, an ultraviolet absorber, etc. These additives may be appropriately blended. If necessary, a water-soluble polymer such as PVA of different types from the PVA of the present invention, starch, carboxymethylcellulose, methylcellulose, and hydroxymethylcellulose may be blended within a range not losing the effects of the present invention. .
[0021]
The film-forming stock solution for obtaining the PVA-based water-soluble film of the present invention is prepared by blending PVA with a plasticizer, a surfactant, and, if necessary, an inorganic filler and other components described above, and mixing them in a desired manner. Can be manufactured.
[0022]
A film-forming method generally used when forming a cast film using the above-mentioned film-forming stock solution of the present invention, for example, a casting film-forming method, a wet film-forming method, a dry film-forming method, an extrusion film-forming method. A PVA-based water-soluble film can be formed by a film forming method such as a method or a melt film forming method. A composition comprising the above-mentioned PVA, plasticizer, surfactant and, if necessary, an inorganic filler or other components as a film forming stock solution is 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 composition may be mixed in advance and then dissolved in the solvent, or the PVA composition may be constituted. These components may be mixed after each component to be dissolved is dissolved in a solvent. The concentration of the film forming stock solution is preferably 50% by weight or less (the solvent content is more than 50% by weight) from the viewpoint of viscosity, and 35% by weight or less (solvent from the point that a mat state is easily formed on the surface of the film formed. Is more preferred than 65% by weight).
[0023]
The temperature of the metal surface on which the film-forming stock solution is cast is 80 to 110 ° C, preferably 85 to 105 ° C, and particularly preferably 90 to 100 ° C. When 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. A temperature higher than 110 ° C. is not preferable because the film may foam and open.
[0024]
The thickness of the PVA-based water-soluble film of the present invention is preferably 10 to 100 μm, more preferably 30 to 80 μm from the viewpoint of the balance between strength and water solubility.
[0025]
The PVA water-soluble film of the present invention requires that at least one surface of the film has irregularities having 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. Upper limit, the surface roughness is too large, the film strength is lowered, because the tear is likely to occur, it is 10S less.
[0026]
The surface roughness of the PVA water-soluble film of the present invention is determined by randomly adjusting the film surface to 20 ° C. and 40% RH, and then using a surface roughness meter with a tip R of 0.3 μm. The measurement of the distance of 30 cm is performed 5 times, and the average value is shown.
The surface roughness of the present invention is the maximum height (Rmax) defined in JIS B0601.
[0027]
In order to make the PVA water-soluble film of the present invention exhibit the anti-blocking property, various methods can be used to make at least one surface of the film have irregularities with the surface roughness of 1S or more. For example, the surface of the water-soluble film can be made into a roll mat, an anti-blocking powder such as silica or starch can be applied, or an embossing treatment can be performed. Roll matting of the film surface can be performed by forming fine irregularities on the roll that comes into contact with the film before drying during film formation. The embossing treatment can be generally performed by nipping between an embossing roll and a rubber roll while applying heat and pressure after the film is formed. Although the application of powder has a great effect of preventing blocking, it may not be used depending on the application, and therefore it is preferable to perform roll matting or embossing treatment to prevent blocking. It is particularly preferable to use a roll mat because of its great anti-blocking effect.
[0028]
The surface roughness of the matte roll metal surface is 1S or more, more preferably 2S or more, and particularly preferably 3S or more. If it is smaller than 1S, the anti-blocking property is insufficient. Upper limit, since the viscosity may open hole bubbles are generated is 10S less.
The surface roughness of the metal surface is also the maximum height (Rmax) defined in JIS B0601.
[0029]
Since the PVA-based water-soluble film of the present invention is often used to create a bag and wrap a medicine or the like, impact resistance is required. As an indicator, the impact burst strength at 20 ° C. is preferably 5 kg · cm or more, more preferably 10 kg · cm or more, and particularly preferably 15 kg · cm or more.
[0030]
The PVA-based water-soluble film of the present invention is not only excellent in water solubility but also excellent in heat sealability, so it is used by dissolving in water with a detergent or a solid substance showing alkalinity. It is very useful as a material packaging, especially unit packaging. The packaging bag manufactured from the PVA-based water-soluble film of the present invention is rapidly dissolved just by being put into water as it is, and its contents are released into water.
[0031]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In addition, the water-soluble measuring method of the PVA-type water-soluble film in an Example, the blocking property, and the evaluation method of impact resistance were performed with the following method.
[0032]
(1) Method for measuring water solubility of water-soluble film:
The water solubility of the PVA water-soluble film in the present invention is a value for a water-soluble film having a thickness of 40 μm.
Install a magnetic stirrer in a constant temperature bath at 20 ° C. A 1 L glass beaker containing 1 L of distilled water is placed in a bath and agitated at 250 rpm using a 5 cm rotor. After the distilled water in the beaker reaches 20 ° C., the water solubility measurement is started.
The film was cut into 40 × 40 mm squares, sandwiched between slide mounts, immersed in 20 ° C. stirring water, and the dissolved state of the film was observed. The time (second) until the film was dissolved was measured. When a film having a film thickness different from 40 μm is used, the film thickness is converted into a value of 40 μm according to the following formula (1).
[0033]
Dissolution time (seconds) = [40 / film thickness (μm)] ² × actual dissolution time (seconds) (1)
[0034]
(2) Evaluation method of blocking property:
A 15 x 20 cm film that has been conditioned for 1 week at 20 ° C and 65% RH is placed between two glass plates with 100 layers of uneven surfaces in the same direction, and a 1 kg weight is placed between them. Placed and stored for 1 week. The ease of peeling at the center of the stacked film was evaluated.
[0035]
(3) Measurement of impact resistance:
The impact rupture strength was measured according to ASTM D-3420 using a film impact tester.
[0036]
Example 1
To 100 parts by weight of PVA having a saponification degree of 88 mol% and a polymerization degree of 1700, 20 parts by weight of glycerin as a plasticizer, 0.2 part by weight of polyoxyethylene oleyl ether as a surfactant and water are added, and the temperature is uniform at 95 ° C. A film-forming stock solution having a concentration of 20% by weight (water content 80% by weight) is prepared, cast onto a stainless steel roll having a surface roughness of 3S at 95 ° C., and dried to have a thickness of 40 μm and the surface roughness on the stainless steel roll side. A 3S film was obtained. The film was water-soluble (time until dissolved in water) at 20 ° C. for 30 seconds. The blocking property test result was good, and the impact burst strength (impact resistance) was 26 kg · cm.
[0037]
Example 2
To 100 parts by weight of PVA having a saponification degree of 88 mol% and a polymerization degree of 1700, 10 parts by weight of glycerin / 10 parts by weight of diglycerin as a plasticizer, 0.5 part by weight of polyoxyethylene lauryl ether as a surfactant and water were added. A film forming stock solution having a uniform concentration of 30% by weight (moisture content of 70% by weight) at a temperature of 95 ° C. is prepared, cast onto a stainless steel roll having a surface roughness of 2S at 90 ° C., and dried to have a thickness of 40 μm. A film with a surface roughness of 2S on the roll side was obtained. The film was water-soluble (time until dissolved in water) at 20 ° C. for 35 seconds. The blocking property was good, and the impact burst strength (impact resistance) was 24 kg · cm.
[0038]
Example 3
To 100 parts by weight of PVA having a saponification degree of 88 mol% and a polymerization degree of 1700, 20 parts by weight of glycerin as a plasticizer, 0.2 part by weight of polyoxyethylene oleyl ether as a surfactant and water are added, and the temperature is uniform at 95 ° C. A film-forming stock solution having a concentration of 20% by weight (water content 80% by weight) was prepared, cast into a stainless steel roll having a surface roughness of 1.5S at a temperature of 95 ° C., and dried to a thickness of 40 μm. A film having a surface roughness of 1.5S was obtained. The film was water-soluble (time until dissolved in water) at 20 ° C. for 40 seconds. The blocking property was good, and the impact burst strength (impact resistance) was 25 kg · cm.
[0039]
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 film-forming stock solution. The water solubility (time until dissolved in water) of this film was 52 seconds at 20 ° C. The blocking property was good, and the impact burst strength (impact resistance) was 4 kg · cm.
[0040]
Comparative Example 2
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 40 parts by weight of glycerin was added to 100 parts by weight of PVA. The water solubility (time until dissolved in water) of this film was 21 seconds at 20 ° C. The blocking property was poor, and the film was in close contact and difficult to peel. The impact burst strength (impact resistance) was 32 kg · cm.
[0041]
Comparative Example 3
A film was prepared in the same manner as in Example 1 except that the surfactant was not added to the stock solution. This film was in close contact with the stainless steel roll and had poor peelability, and a satisfactory film could not be obtained.
[0042]
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. The water solubility (time until dissolved in water) of this film was 28 seconds at 20 ° C. The blocking property was poor and it was in close contact and difficult to peel. The impact burst strength (impact resistance) was 20 g · cm.
[0043]
Comparative Example 5
A film was obtained in the same manner as in Example 1 except that the film forming stock solution was dried on a stainless steel roll having a surface roughness of 3S at 70 ° C. This film was in close contact with the stainless steel roll and had poor peelability, and a satisfactory film could not be obtained.
[0044]
Comparative Example 6
A film having a thickness of 40 μm and a surface roughness of 15S was obtained in the same manner as in Example 1 except that the film forming stock solution was dried on a stainless steel roll having a surface roughness of 3S at 120 ° C. This film was foamed to form minute holes, and a satisfactory film could not be obtained.
[0045]
【Effect of the invention】
The PVA-based water-soluble film of the present invention is excellent in blocking resistance and impact resistance as well as having good water solubility, and is preferable for use in conventionally known water-soluble films such as chemical packaging, dye packaging, and detergent packaging. Used.

Claims (2)

A film-forming stock solution prepared by blending 5 to 30 parts by weight of a plasticizer and 0.01 to 2 parts by weight of a surfactant with respect to 100 parts by weight of polyvinyl alcohol has a surface roughness of 80 to 110 ° C. and unevenness of 1 to 10 S. It is characterized in that it is dried on a metal surface having a composition of 5 to 30 parts by weight of a plasticizer and 0.01 to 2 parts by weight of a surfactant with respect to 100 parts by weight of polyvinyl alcohol. A method for producing a polyvinyl alcohol-based water-soluble film, wherein at least one surface has irregularities having a surface roughness of 1 S or more and 10 S or less . Preparation of water-soluble film according to claim 1 surfactant is an alkyl ether-based surfactant.