JPH0252614B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a method for producing a composite film for preventing dew condensation, in which a plastic film is provided with a slippery and drip-proof resin layer made of a special water-soluble polyester ether on at least one side thereof. It is. [Prior Art] In recent years, forced cultivation of vegetables, fruits, and flowers has become widely practiced, and agricultural greenhouses have become rapidly popular.
Plastic films, which are lightweight, inexpensive, and easy to install, have come to be used often as covering materials for agricultural greenhouses, and in particular, plastic films that have been treated with so-called drip-proof treatment to prevent fogging inside the greenhouse have begun to be used. This drip-proofing treatment is often applied to the film itself before it is expanded into a greenhouse, and the general method used is to apply a drip-proofing agent to the film by spraying or the like. However, recently, a method of applying a drip-proofing agent during the film manufacturing process has been developed, and it is seen as a promising method in terms of simplifying the work and reducing costs. That is, this is a method in which a drip-proofing agent is applied to an unstretched film or a uniaxially stretched film, the film is stretched uniaxially or biaxially, and then heat treated to create a film that has drip-proof properties all at once. However, in this method, the coated film surface is exposed to high temperatures in the stretching and heat treatment sections, which often causes the film to become cloudy. A cloudy film has extremely low sunlight transmittance and is unsuitable for use as a house film, and the disadvantage is that it is difficult to obtain a highly transparent film using conventional coating methods in the film manufacturing process. [Object of the Invention] An object of the present invention is to provide a method for producing a composite film that eliminates the drawbacks of the above-mentioned prior art, has excellent transparency, and can maintain drip-proof performance over a long period of time. [Configuration of the Invention] In order to achieve the above object, the present invention has the following configuration:
That is, in a method for producing a composite film, the plastic film is stretched and heat-set after applying a water-soluble or aqueous dispersion containing at least a water-soluble polyester ether resin and an inorganic colloid to at least one side of the plastic film.
The method is characterized in that polyhydric alcohol is added to the aqueous solution or aqueous dispersion in an amount of 0.1 to 90% by weight based on the solid content of the dry coating film. The plastic film used in the present invention includes polyethylene, polypropylene, polyvinyl chloride,
Refers to films such as polystyrene, polymethyl methacrylate, polycarbonate, polysulfone, and polyester. Among these, the present invention is preferably applied to polyester films from the viewpoint of mechanical properties, and most preferably applied to polyester films in which 85 mol% or more of the repeating units are ethylene terephthalate units. Next, what is water-soluble polyester ether resin?
A polycondensate of aromatic dicarboxylic acid and/or non-aromatic dicarboxylic acid and ester-forming sulfonic acid alkali metal salt compound and glycol,
0.5% by weight or more, preferably 1% by weight in water at 20℃
Means something soluble in water (50 to
It is carried out at a high temperature of 100℃, then cooled to 20℃,
0.5% by weight or more, preferably 1% by weight or more, solubility may be maintained). Aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 1,4-naphthalene dicarboxylic acid, 2,6
-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,
p'-dicarboxylic acids and their ester-forming derivatives, and non-aromatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, 1,2-cyclohexanedicarboxylic acid,
Examples include 1,4-cyclohexanedicarboxylic acid and ester-forming derivatives thereof. It is preferable that at least 60 mol% of the dicarboxylic acid component is an aromatic dicarboxylic acid and/or its ester-forming derivative, and when the aromatic dicarboxylic acid component is within this range, the adhesion to the film of the water-soluble polyester ether resin is improved. It is more preferable because the drip-proof effect improves as the value increases. Examples of the ester-forming sulfonic acid alkali metal salt compounds include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and sulfo-p-
Examples include xylylene glycol, alkali metal salts (alkali metal salts of sulfonic acid) such as 2-sulfo-1,4-bis(hydroxyethoxy)benzene, and ester-forming derivatives thereof;
More preferred are sulfoisophthalic acid, sodium sulfoterephthalic acid, and ester-forming derivatives thereof. The amount of these ester-forming sulfonic acid alkali metal salt compounds added is 7 to 40 mol%, preferably 10 to 20 mol%, based on the total dicarboxylic acid components.
It is. If it is less than 7 mol%, there is no drip-proof effect and it is not practical, and if it exceeds 40 mol%, the melt viscosity increases dramatically during the polymerization process, making it difficult to obtain a water-soluble polyester ether resin with an appropriately high degree of polymerization. This is not preferable because it is difficult and the durability of the drip-proof effect of the film decreases. Addition amount is 10-20 mol%
The best polymerization, initial drip-proofing properties, and drip-proofing durability can be obtained when Glycols include aliphatic or alicyclic glycols, such as ethylene glycol, 1,3-
Propanediol, 1,4-butanediol,
1,4-cyclohexanedimethanol etc. can be used, but diethylene glycol or triethylene glycol is added to this glycol component in an amount of 1 to 60 mol%, preferably 2 to 60% by mole based on the total glycol component.
It is more preferable to use one containing up to 18 mol%. In some cases, diethylene glycol and triethylene glycol may be used together.
If the amount of diethylene glycol or triethylene glycol is less than 1 mol % based on the total glycol components, it tends to be difficult to make the water-soluble polyester ether resin water-soluble and to make the coating uniform. Furthermore, if the component amount of diethylene glycol or triethylene glycol is 60 mol % or more, the coated film will block or whiten after being applied, which is not preferable. The best drip-proofing effect and applicability can be obtained when the copolymerization content is 2 to 18 mol%. The inorganic colloid used in the present invention is defined in the Kyoritsu Shuppan Chemical Dictionary, and contains 10 5 to 10 ⁵ in one particle.
It contains ¹⁰⁹ atoms. Depending on the element, it can be obtained as a metal colloid, an oxide colloid, or a hydroxide colloid, but colloids that are finer than the wavelength of visible light are preferred for the present invention in order to prevent clouding. Preferably used metal colloids include gold, palladium, platinum, silver, and sulfur; examples of oxide colloids, hydroxide colloids, carbonate colloids, and sulfate colloids include zinc, magnesium, silicon, calcium, aluminum, and strontium. , barium, zirconium,
Oxide colloids, hydroxide colloids, carbonate colloids, and sulfate colloids of titanium, manganese, iron, cobalt, nickel, tin, etc. are preferably used in the present invention. For example, silicic acid colloids obtained by adding silicon tetrahalide to water or gradually adding concentrated hydrochloric acid to an aqueous solution of alkali silicate are very preferably used in the present invention. An oxide colloid, a hydroxide colloid, a carbonate colloid,
By adding sulfate colloid or metal colloid, blocking of the composite film can be prevented, and the drip-proof property immediately after being expanded into an agricultural greenhouse can be further improved, and the drip-proof property can be maintained for an extremely long period of time. The polyester ether resin aqueous solution containing inorganic colloid used in the present invention has a
It is often better to include 0.01 to 1% of a surfactant. As the surfactant, any of the cationic type, anionic type, amphoteric type, and nonionic type can be used, but the anionic type is particularly preferred, and sodium dodecylbenzenesulfonate, sodium dodecylbenzenesulfonate,
Examples include alkylbenzenesulfonates such as sodium dodecylxylene sulfonate, alkylnaphthalenesulfonates, and alkylphenolsulfonates. Among them, sodium dodecylbenzenesulfonate is preferred. Now, the gist of the present invention is to add a polyhydric alcohol to an aqueous solution (hereinafter, the term aqueous solution will also include an aqueous dispersion) containing at least a water-soluble polyester ether resin and an inorganic colloid. By this addition, even if this liquid is applied to one or both sides of an unstretched film or a uniaxially stretched film, the film is uniaxially or biaxially stretched, and heat-treated, the film does not become cloudy and can be used for the purpose of the present invention. A film with suitable transparency can be obtained. The polyhydric alcohol referred to here is a dihydric or trihydric alcohol, which has good water solubility and a boiling point.
It is preferable that the vapor pressure at 150°C or higher and 20°C is 5 mmHg or lower. Specific examples include ethylene glycol, 1,2-propylene glycol,
1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-butene-1,4- Diol, 2-methyl-2,4-pentanediol, 2
-Ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol,
Examples include tetraethylene glycol, 1,2,6-hexanetriol, hexaglycerol, and glycerin. Among them, triethylene glycol, tetraethylene glycol, hexaglycerol, and glycerin are more preferred, and glycerin is most preferred. The solid content ratio of water-soluble polyester ether resin: inorganic colloid: surfactant constituting the aqueous solution is preferably in the range of 20 to 94:80 to 1:0 to 5 (wt%). The amount of polyhydric alcohol added to the solid content with this composition ratio is 0.1 based on the total weight of all solid content including polyhydric alcohol.
-90% by weight, preferably 7-60% by weight. 0.1% by weight of polyhydric alcohol, preferably 7
If it is less than 90% by weight, preferably 60% by weight, the coated surface will tend to become cloudy during the process of stretching and heat-setting the plastic film coated with this aqueous solution (drop-proofing agent), and if it is more than 90% by weight, preferably 60% by weight, the composite film will This is not preferable because it tends to block when rolled. The aqueous solution used in the present invention is prepared by dissolving a water-soluble polyester ether resin in water, and then adding an inorganic colloid, a polyhydric alcohol, and, if necessary, other components such as a surfactant. The concentration of the aqueous solution is preferably 0.01 to 30% by weight, more preferably 0.1 to 10% by weight expressed as total solid weight.
has excellent coating properties. As the coating method, a general known method can be applied. Examples include a gravure coating method, an air knife coating method, a roll coating method, and a dip method. The present invention can also be applied to a method of manufacturing a composite film in which a plastic film is coated with an aqueous solution, then stretched uniaxially or biaxially and heat-set. It can be preferably applied to a manufacturing method in which the axis is stretched and heat-set. The manufacturing method in which coating is applied after biaxial stretching and heat setting, or the method in which coating is applied after biaxial stretching and heat setting, does not meet the purpose of the present invention because the resulting composite film will block.
As the stretching method, a known method such as a roll method or a tenter method can be used, but the tenter method is preferable for stretching after coating. The stretching temperature is preferably 80 to 150℃, preferably 90 to 150℃.
120℃ is good. If the temperature is below this temperature, the coating film will not be sufficiently dried and the film will likely break, and if the temperature is above this temperature, the coating film will become more likely to become cloudy. In addition, the heat setting of the stretched film is
Preferably, the temperature is 110-240°C. The dimensions of the film may be relaxed by 0-10% by heat setting. Note that a known method for polymerizing polyethylene terephthalate or the like can be applied to the polymerization of the copolyester ether resin. In addition, the drip-proof agent layer may contain pigments,
Dyes, antioxidants, ultraviolet absorbers, inert inorganic particles, etc. may also be added. The thickness of the composite film of the present invention is 25 μm to 250 μm
is the preferred range. [Effects of the Invention] The effects of the present invention are summarized as follows. Clouding of the surface coated with the drip-proofing agent is eliminated, and the transparency of the film can be significantly improved. The drip-proofing agent has excellent applicability and can form a uniform resin layer. The winding workability of the composite film is good. The composite film obtained by the production method of the present invention can be used in addition to agricultural greenhouses, solar collectors, photo-selective membranes, traffic signs, packaging materials for fruits and vegetables and meat, coating materials for freezers such as fish and meat and ice cream, automobiles and houses. Used as interior material and for a wide range of other purposes. The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to these Examples. In addition, the evaluation criteria in the following examples were determined based on the following. (1) Application property: The state when an aqueous solution is applied to a film using a gravure roll. (2) Application whitening: Visually judge the degree of clouding of the film. (3) Blocking property; 50 according to JIS Z-0219
℃ and 80 to 90 RH%, a load of 500 g/12 cm ² was applied and the blocking property was evaluated after 24 hours. (4) Light transmittance; broadband self-recording spectrophotometer (Hitachi
323 type) to measure the parallel light transmittance at 550 mμ. (5) Drip-proof performance: A film was installed on the roof of an outdoor house measuring approximately 22 tsubo at an angle of 15 degrees from the horizontal plane, and its drip-proof performance was investigated over a six-month winter period (October to March). (6) Indication of judgment criteria; ○: Good △: Slightly poor ×: Bad Example 1 150 parts of dimethyl terephthalate, 15 parts of dimethyl isophthalate, 44.5 parts of dimethyl 5-sodium sulfoisophthalate, 124 parts of ethylene glycol, manganese acetate 0.106 parts of tetrahydrate and 0.07 parts of calcium acetate dihydrate were mixed, methanol was distilled off at 140 to 220°C, and transesterification was performed, followed by 0.09 parts of trimethyl phosphate, 7.2 parts of diethylene glycol,
Add 0.06 part of antimony trioxide and heat from 240℃ to 280℃
The temperature was raised over 1 hour and 30 minutes, and the pressure was gradually lowered from normal pressure to 0.5 mmHg, the ethylene glycol produced was removed from the system, and this state was maintained for an additional 40 minutes to react, and [η] = 0.58. A water-soluble polyester ether resin was obtained. The obtained water-soluble polyester ether resin is 80
It was dissolved in hot water at °C to make a 6% by weight aqueous solution. A colloidal silica aqueous solution with a concentration of 20% by weight and sodium dodecylbenzenesulfonate were added to this,
The composition ratio of the solids is 59% by weight of water-soluble polyester ether resin, 40% by weight of colloidal silica, and 1% by weight of sodium dodecylbenzenesulfonate.
It was expressed as weight%. Add 45.4% by weight of glycerin based on the solid content to this aqueous solution and create an aqueous solution (dripproof agent aqueous solution).
The total solids concentration was 6% by weight. On the other hand, polyethylene terephthalate was melt extruded at 290°C, cast onto a cast drum at 20°C to which an electrostatic charge was applied, and then made into a non-stretched sheet.
It was preheated to 80°C and stretched 3.3 times in the longitudinal direction by roll stretching. After applying the drip-proofing agent aqueous solution on one side of this uniaxially stretched film, it was stretched 3.5 times in the width direction at 95°C, and heat-treated at 210°C while slightly loosening, to form a polyethylene terephthalate layer with a drip-proofing agent layer of 0.25μ. A 125μ composite film based on was obtained. The obtained composite film was a highly transparent film without clouding. When the drip-proof layer was placed inside an agricultural greenhouse, there was no clouding at all, and it was found that it maintained an extremely excellent drip-proof effect after 6 months. Example 2 and Comparative Example The same aqueous solution as in Example 1 was prepared, except that various polyhydric alcohols shown in Table 1 were used instead of the glycerin in Example 1, and a composite film was formed under the same conditions as in Example 1. I made it. The evaluation results for this film are shown in Table 1. As is clear from Table 1, Experiments Nos. 1 to 7 corresponded to the present invention and had good transparency and drip-proof properties. Experiment Nos. 8 and 9 were comparative examples outside the invention, and both were cloudy and had defects in transparency. Example 3 and Comparative Examples The evaluation results of films obtained by changing the amount of glycerin added based on Example 1 are shown in Table 1, Experiment No. 10~
Shown in 12. Experiment No. 11 corresponds to the present invention, and Experiment No.
10 and 12 are comparative examples. These results show that if the amount of polyhydric alcohol (glycerin in this experiment) is less than 0.1% based on the total solid weight, there is no clouding prevention effect, and on the other hand, if it exceeds 90%, the blocking property is particularly poor. I know it's going to get worse.

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Claims (1)

[Claims] 1. On at least one side of the plastic film,
A method for producing a composite film in which a plastic film is stretched and heat-set after applying an aqueous solution or aqueous dispersion containing at least a water-soluble polyester ether resin and an inorganic colloid, wherein a polyhydric alcohol is dried and applied to the aqueous solution or aqueous dispersion. 1. A method for producing a composite film, which comprises adding 0.1 to 90% by weight based on the solid content of the film.