JP2009279759A - Base film for liquid pressure transfer printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base film for liquid pressure transfer printing which is excellent in transfer printability and further in a film removing property after transfer and which has improved productivity. <P>SOLUTION: This invention relates to the base film for liquid pressure transfer printing consisting of a poly(vinyl alcohol) film, which is formed from a polyvinyl alcohol resin comprising a polyvinyl alcohol resin (A1) with average saponification of 80 to 95 mol%, a polyvinyl alcohol resin (A2) with higher average saponification than that of the polyvinyl alcohol resin (A1) and a polyvinyl alcohol resin (A3) with lower average saponification than that of the polyvinyl alcohol resin (A1). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a base film for hydraulic transfer printing that can be used by floating on a liquid surface, particularly a water surface, and can smoothly transfer a design printed on the film surface to a transfer target.

  Conventionally, as a base film for hydraulic transfer printing, a polyvinyl alcohol resin film using a polyvinyl alcohol resin as a forming material has been used. And it uses for the hydraulic transfer method as follows using the said polyvinyl alcohol-type resin film. That is, a desired design is printed on the surface of the polyvinyl alcohol-based resin film, the design printed surface is faced up and floated on the water surface, and the transferred object is pressed against the printed surface of the design from above the film to transfer the design to the transferred object. Has been done.

  In such a hydraulic transfer method, various base films have been studied according to the purpose. For example, Patent Document 1 proposes a polyvinyl alcohol film composed of a polyvinyl alcohol resin having an average degree of polymerization of 300 to 3000 and an average degree of saponification of 50 to 97 mol%. Furthermore, the average degree of polymerization and the average degree of saponification are proposed. It has also been proposed to blend two different types. In Patent Document 2, an ultrahigh polymerization degree polyvinyl alcohol resin having an average degree of polymerization of 3200 or more and an average degree of saponification of 65 to 95 mol%, and a polyvinyl having an average degree of polymerization of less than 3200 and an average degree of saponification of 65 to 95 mol%. A polyvinyl alcohol film formed by mixing an alcohol resin has been proposed. Further, Patent Document 3 contains a polyvinyl alcohol resin having an average saponification degree of 70 to 98 mol%, a carboxyl group and / or a sulfonic acid group-modified polyvinyl alcohol resin having an average saponification degree of 70 mol% or more, and a boron compound. A polyvinyl alcohol film formed by the above method has also been proposed.

JP-A-55-25330 Japanese Patent Laid-Open No. 7-117327 JP 2003-11590 A

  However, in the hydraulic transfer method using the polyvinyl alcohol film disclosed in the above-mentioned patent document, a good design can be obtained, but the film removal property of the polyvinyl alcohol film after transfer is insufficient. If the film removal property of the polyvinyl alcohol film after the transfer is insufficient, the polyvinyl alcohol film partially remains on the design surface, and the protective layer top-coated for the purpose of surface protection partially drops off after the transfer. There is a problem that the film may be removed, and further film removal properties are required.

  Therefore, the present invention has been made in view of such circumstances, and it is excellent in transfer printing suitability, and also has excellent film removal properties of a polyvinyl alcohol film and can improve productivity. The purpose is to provide.

  However, as a result of studies conducted by the inventor repeatedly to achieve the above-mentioned object, paying attention to the resin composition of the base film and focusing on this, the resin composition constituting the polyvinyl alcohol-based film is determined as an average The inventors have found that by containing at least three types of polyvinyl alcohol resins having different degrees of conversion, the transfer printing characteristics are excellent and the film-removability of the polyvinyl alcohol film after transfer is also excellent, and the present invention has been completed.

  That is, the gist of the present invention is a base film for hydraulic transfer printing comprising a polyvinyl alcohol-based film, wherein the polyvinyl alcohol-based film is a polyvinyl alcohol-based resin (A1) having an average saponification degree of 80 to 95 mol%. Polyvinyl alcohol containing polyvinyl alcohol resin (A2) higher than average saponification degree of polyvinyl alcohol resin (A1) and polyvinyl alcohol resin (A3) lower than average saponification degree of polyvinyl alcohol resin (A1) The present invention relates to a base film for hydraulic transfer printing composed of a resin.

  Since the base film for hydraulic transfer printing of the present invention comprises a polyvinyl alcohol film composed of a resin composition containing at least three types of polyvinyl alcohol resins having different average saponification degrees, the transfer printing characteristics are excellent. It has an excellent effect on the film-removability of the polyvinyl alcohol film after transfer, and it can be applied to the exterior and exterior of mobile phones, various electrical appliances, building materials, household and household items, etc. It can be widely applied to transfer printing applications.

Hereinafter, the present invention will be described in detail.
The base film for hydraulic transfer printing of the present invention comprises a polyvinyl alcohol film.
In the present invention, “consisting of a polyvinyl alcohol film” includes a case where another layer (film, coating film, etc.) is laminated in addition to the polyvinyl alcohol film. In many cases, only a base film is used as a base film.

  The polyvinyl alcohol film is formed into a film using a polyvinyl alcohol (hereinafter abbreviated as PVA) resin. In the present invention, the average saponification degree is 80 to 95 as the PVA resin. The PVA resin (A2) having a mol% of PVA resin (A1), the PVA resin (A2) higher than the average saponification degree of the PVA resin (A1), and the PVA resin (A3) lower than the average saponification degree of the PVA resin (A1). ).

  Here, the PVA system means PVA itself or one modified by, for example, various modified species, and the degree of modification is usually 20 mol% or less, preferably 15 mol% or less, more preferably 10 mol. % Or less.

  Examples of the modified species include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, α-octadecene, acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid and the like. Unsaturated acids or salts thereof, mono- or dialkyl esters, nitriles such as acrylonitrile and methacrylonitrile, amides such as acrylamide and methacrylamide, olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid or the like Salt, alkyl vinyl ether, polyoxyethylene (meth) allyl ether, polyoxyalkylene (meth) allyl ether such as polyoxypropylene (meth) allyl ether, polyoxyethylene (meth) acrylate, Polyoxyalkylene (meth) acrylates such as oxypropylene (meth) acrylate, polyoxyalkylene (meth) acrylamides such as polyoxyethylene (meth) acrylamide, polyoxypropylene (meth) acrylamide, and polyoxyethylene [1- (meth) Acrylamide-1,1-dimethylpropyl] ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine, diacrylacetone amide, N- Acrylamide methyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethyldiallylammonium chloride, di Chill allyl vinyl ketone, N- vinylpyrrolidone, vinyl chloride, vinylidene chloride and the like. These other monomers may be used alone or in combination of two or more.

  Further, as the PVA resin, it is also preferable to use a PVA resin having a 1,2-diol bond in the side chain, and the PVA resin having a 1,2-diol bond in the side chain is, for example, (a) acetic acid A method of saponifying a copolymer of vinyl and 3,4-diacetoxy-1-butene, (a) a method of saponifying and decarboxylating a copolymer of vinyl acetate and vinyl ethylene carbonate, and (c) vinyl acetate. Of saponifying and deketalizing a copolymer of 2,2-dialkyl-4-vinyl-1,3-dioxolane, and (d) saponifying a copolymer of vinyl acetate and glycerol monoallyl ether. Obtained by a method, etc.

The PVA resin (A1) used in the present invention needs to be a PVA resin having an average saponification degree of 80 to 95 mol%, preferably 83 to 93 mol%, particularly preferably 85 to 90 mol. %. If the average saponification degree of the PVA resin (A1) is less than the above range, it tends to require a long time for dissolution of the base film after transfer, and if it exceeds the above range, the dissolution time of the base film is delayed or transfer is possible. Even if this occurs, a film removal failure may occur in the film removal process after transfer.
The average degree of saponification is measured according to JIS K 6726.

The PVA-based resin (A1) is preferably in the range of 10 to 70 mPa · s, particularly in the range of 15 to 60 mPa · s, more preferably in the range of 20 to 55 mPa as the average viscosity of the 4 wt% aqueous solution at 20 ° C. -It is preferable that it is the range of s. If the average viscosity of the 4% by weight aqueous solution is too low, the film strength is insufficient when printing designs (patterns, patterns, etc.) on the base film, so printing spots tend to occur and the base film dissolves. As a result, there is a problem that the transferable time is shortened due to acceleration of the film, and the design printed on the film when it floats on water is not stable, and the throwing power tends to decrease. On the other hand, if the average viscosity of the 4% by weight aqueous solution is too high, it is possible to suppress the extension of the film on the water surface, but there is a tendency that the transfer time is delayed and the viscosity is high and the film formation becomes difficult.
The average viscosity of a 4% by weight aqueous solution of the PVA resin at 20 ° C. is measured according to JIS K 6726.

  The PVA resin (A2) used in the present invention may be any PVA resin that is higher than the average degree of saponification of the PVA resin (A1). Among them, the average saponification degree of the PVA resin (A1) is 5 mol% or more, particularly 6 mol% or more, more preferably 7 mol% or more, and particularly preferably 8 mol% or more. It is preferable in terms of the film removal property. If the difference in the average saponification degree is too small, the film removal after transfer tends not to be improved. In addition, the upper limit of the difference in average saponification degree is usually 20 mol% or less, preferably 15 mol% or less, because of the concern of separation in a solution state.

  Specifically, the average saponification degree of the PVA-based resin (A2) is preferably 90 to 100 mol% from the viewpoint of film removal after transfer, particularly 91 to 99 mol%, more preferably 92 to It is preferable that it is 98 mol%. If the average degree of saponification is too low, the film removal property after transfer tends not to be improved.

  Further, the average viscosity of a 4 wt% aqueous solution of the PVA resin (A2) at 20 ° C. is preferably 1 to 50 mPa · s, particularly 3 to 40 mPa · s, more preferably 5 to 5 mPa · s. It is preferably ˜30 mPa · s. If the average viscosity is too low, the strength of the film tends to decrease, and if the average viscosity is too high, the solubility tends to decrease.

  Furthermore, regarding the relationship between the average viscosity (y) of a 4 wt% aqueous solution of PVA resin (A2) at 20 ° C. and the average viscosity (x) of a 4 wt% aqueous solution of polyvinyl alcohol resin (A1) at 20 ° C., The average viscosity (y) is preferably smaller than the average viscosity (x) from the viewpoint of solubility. In particular, the ratio (y / x) is 0.1 to 0.5, more preferably 0.15 to 0.45. It is preferable.

  The PVA resin (A3) used in the present invention may be any PVA resin lower than the average degree of saponification of the PVA resin (A1). Among them, the average saponification degree of the PVA resin (A1) is 5 mol% or more, particularly 6 mol% or more, more preferably 7 mol% or more, and particularly preferably 8 mol% or less. It is preferable in terms of the film removal property. If the difference in the average saponification degree is too small, the film removal after transfer tends not to be improved. In addition, the upper limit of the difference in average saponification degree is usually 20 mol% or less, preferably 15 mol% or less, because of the concern of separation in a solution state.

  The average saponification degree of the PVA resin (A3) is preferably 65 to 85 mol% from the viewpoint of film removal after transfer, particularly 67 to 82 mol%, more preferably 70 to 80 mol%. Preferably there is. If the average degree of saponification is too low or too high, the film removal after transfer tends not to improve.

  In addition, the average viscosity of a 4% by weight aqueous solution of the PVA resin (A3) at 20 ° C. is preferably 1 to 50 mPa · s, particularly 3 to 40 mPa · s, and more preferably 5 to 5 mPa · s. It is preferably ˜30 mPa · s. If the average viscosity is too low, the strength of the film tends to decrease, and if the average viscosity is too high, the solubility tends to decrease.

  Furthermore, regarding the relationship between the average viscosity (z) of a 4 wt% aqueous solution of PVA resin (A3) at 20 ° C and the average viscosity (x) of a 4 wt% aqueous solution of polyvinyl alcohol resin (A1) at 20 ° C, The average viscosity (z) is preferably smaller than the average viscosity (x) from the viewpoint of solubility. In particular, the ratio (z / x) is 0.1 to 0.5, more preferably 0.11 to 0.45. It is preferable.

  About the content rate of PVA-type resin (A1), PVA-type resin (A2), and PVA-type resin (A3) in said PVA-type resin, PVA-type resin (A1), PVA-type resin (A2), and PVA-type resin The content of PVA resin (A1) is 40 to 98% by weight, the content of PVA resin (A2) is 1 to 40% by weight, and the content of PVA resin (A3) is the total amount of (A3) The ratio is preferably 1 to 40% by weight from the viewpoint of the balance between solubility and film-removing property at the time of transfer, and particularly preferably the content ratio of PVA resin (A1) is 45 to 90% by weight, PVA resin ( The content ratio of A2) is 5 to 35% by weight, the content ratio of PVA resin (A3) is 5 to 35% by weight, more preferably the content ratio of PVA resin (A1) is 50 to 90% by weight, PVA resin The content ratio of (A2) is 5 to 3 Wt%, the content of the PVA-based resin (A3) is 5 to 30 wt%. When the content ratio of the PVA resin (A1) is too small, the solubility tends to be lowered and transfer cannot be performed. When the content is too large, the film removal property tends not to be improved. If the content ratio of the PVA-based resin (A2) is too small, the film removal property tends not to be improved, and if it is too large, the solubility tends to be lowered and transfer cannot be performed. If the content ratio of the PVA-based resin (A3) is too small, the film-removing property tends not to be improved.

  Moreover, in this invention, it is preferable that it is 20 / 80-80 / 20 (weight ratio) about the content rate of the said PVA-type resin (A2) and PVA-type resin (A3), Especially 30 / 70- It is preferably 70/30 (weight ratio), more preferably 40/60 to 60/40 (weight ratio).

  Thus, in the present invention, as the PVA resin, the PVA resin (A1), the PVA resin (A2), and the PVA resin (A3) are used to form the PVA film. Usually, a plasticizer is blended. Examples of the plasticizer include glycerins such as glycerin, diglycerin, and triglycerin, alkylene glycols such as triethylene glycol, polyethylene glycol, polypropylene glycol, and dipropylin glycol, and trimethylolpropane. These may be used alone or in combination of two or more.

  The content of the plasticizer is appropriately set according to the physical properties of the target PVA-based film. For example, it is usually 5 parts by weight or less, preferably 0 with respect to a total of 100 parts by weight of the PVA-based resin. 0.05 to 4 parts by weight. When the content of the plasticizer is too small, the plastic effect is low, and a tendency to cause breakage of the obtained PVA film is observed. When the content is too large, dimensional stability when printing a design on the film surface is observed. There is a tendency that high-definition multi-color printing is difficult due to poor performance.

  In addition to the PVA resin and the plasticizer, various additives can be blended as necessary.

  For example, a surfactant can be blended for the purpose of improving the peelability between a metal surface, such as a drum or belt, which is a PVA film forming apparatus, and the film formed. Examples of the surfactant include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl nonyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan mono Polyoxyethylene alkylamines such as palmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyalkylene alkyl ether phosphate monoethanolamine salt, polyoxyethylene laurylamine, polyoxyethylene stearylamine Etc. These may be used alone or in combination of two or more. Among these, it is preferable to use polyoxyalkylene alkyl ether phosphate monoethanolamine salt, polyoxyethylene alkylamine, and polyoxyethylene sorbitan monolaurate from the viewpoint of peelability.

  About content of the said surfactant, it is preferable that it is 0.01-5 weight part normally with respect to a total of 100 weight part of a PVA-type resin and a plasticizer, More preferably, it is 0.03-4.5. Parts by weight. When the content of the surfactant is too small, there is a tendency that the peelability between the metal surface such as a drum or belt of the film forming apparatus and the film formed is lowered and the production becomes difficult, and conversely, when the content is too large. There is a tendency to bleed on the film surface and cause the design print layer to fall off.

It is also possible to blend a crosslinking agent to the PVA-based resin, a crosslinking agent, as long as it causes a crosslinking reaction with the PVA-based resin, for example, and K ₃ C6H ₅ O ₇ (tripotassium citrate), Boric acid, calcium borate, cobalt borate, zinc borate (zinc tetraborate, zinc metaborate, etc.), aluminum borate / potassium borate, ammonium borate (ammonium metaborate, ammonium tetraborate, ammonium pentaborate, Ammonium octaborate, etc.), cadmium borate (cadmium orthoborate, cadmium tetraborate, etc.), potassium borate (potassium metaborate, potassium tetraborate, potassium pentaborate, potassium hexaborate, potassium octaborate, etc.) ), Silver borate (silver metaborate, silver tetraborate, etc.), copper borate (cupric borate, copper metaborate, copper tetraborate, etc.), Sodium oxalate (sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate, etc.), lead borate (lead metaborate, lead hexaborate, etc.) Nickel borate (nickel orthoborate, nickel diborate, nickel tetraborate, nickel octaborate, etc.), barium borate (barium orthoborate, barium metaborate, barium diborate, barium tetraborate, etc.), boron Bismuth acid, magnesium borate (magnesium orthoborate, magnesium diborate, magnesium metaborate, trimagnesium tetraborate, pentamagnesium tetraborate, etc.), manganese borate (manganese borate, manganese metaborate, tetraborate) Manganese oxide), lithium borate (lithium metaborate, lithium tetraborate) , Pentaborate and lithium) other such as borax, car Knight, In'yoaito, island stone, Suian stone include boron compounds such as borate minerals such Zaiberi stone. These crosslinking agents are used alone or in combination of two or more. Among the above crosslinking agents, borax and boric acid are preferably used.
The amount of the crosslinking agent is preferably 0.01 to 10 parts by weight, and more preferably 0.05 to 5 parts by weight with respect to 100 parts by weight of the total PVA resin.

  Furthermore, as long as the effects of the present invention are not hindered, antioxidants (phenolic, amine-based, etc.), stabilizers (phosphate esters, etc.), coloring agents, fragrances, extenders, antifoaming agents, rust inhibitors, Ultraviolet absorber, inorganic powder, organic powder (starch, polymethyl methacrylate, etc.), and other water-soluble polymer compounds (polyacrylic acid soda, polyethylene oxide, polyvinylpyrrolidone, dextrin, chitosan, chitin, methylcellulose, hydroxyethylcellulose, etc. ) Etc. may be added.

  The PVA-based film constituting the base film of the present invention is manufactured, for example, as follows. First, each raw material such as the PVA resin, plasticizer, surfactant and water is blended in a predetermined blending amount to prepare a film forming material. Next, a film-forming material is cast from a T-die onto a film-forming belt or film-forming drum, dried, and preferably heat-treated to form a film. The temperature condition for the heat treatment is preferably set to 70 to 100 ° C.

  The heat treatment method is not particularly limited, and examples thereof include a heat roll (including a calender roll), hot air, far infrared rays, dielectric heating, and the like. Further, the surface to be heat-treated is preferably a surface opposite to the surface in contact with the film forming belt or the film forming drum, but there is no problem even if it is nipped. Moreover, it is preferable that the water content of the film which heat-processes is about 4 to 8 weight% normally. Furthermore, the water content of the film after the heat treatment is usually preferably 3 to 7% by weight.

  More specifically, it is preferable to pass one or more heat treatment rolls having a surface temperature of 70 to 100 ° C. until the film is wound after being peeled from the film-forming belt or the first film-forming drum of the film-forming drum. Here, the film-forming belt has an endless belt that runs across a pair of rolls, and the film-forming material flowing out from the T-die is cast on the endless belt and dried. The endless belt is preferably made of, for example, stainless steel, and its outer peripheral surface is mirror-finished.

  The film-forming first drum is a drum-type roll located on the uppermost stream side in a film-forming machine for casting and drying the film-forming material flowing out from the T-die onto one or more rotating drum-type rolls. is there. The film forming material discharged from the T-die or the like is dried on the film forming belt or the first film forming drum to become a film shape until it is peeled off after being peeled off from the film forming belt or the first film forming drum. The process of peeling from the film-forming belt or the film-forming first drum, preferably through a heat treatment machine, and being wound up by the winder is shown. It is preferable to perform the heat processing by the said heat processing machine at 70-100 degreeC, More preferably, it is 75-98 degreeC. That is, when the heat treatment temperature is too low, the swelling ratio of the obtained base film tends to be extremely high, and the design tends to be extended until transfer and the design property tends to be lowered. On the other hand, if the heat treatment temperature is too high, the pattern tends to break with respect to a molded product that is required to be attached. Furthermore, although the time required for the heat treatment depends on the surface temperature of the heat treatment roll, it is usually 0.5 to 60 seconds, particularly 0.5 to 30 seconds, and more preferably 0.5 to 15 seconds. If the time is too short, the heat treatment tends to be insufficient, and if it is too long, the heat treatment tends to be excessive, and the productivity tends to decrease. The heat treatment is usually performed with a separate heat treatment roll following the drying roll treatment for drying the film.

  Thus, the PVA-type film which comprises the base film for hydraulic transfer printing of this invention can be obtained.

Furthermore, in this invention, it is preferable that the moisture content of a PVA-type film is 2 to 6 weight%, More preferably, it is 3 to 5 weight%. If the moisture content is too small, the film tends to curl at the time of transfer. If the moisture content is too large, the curl becomes small, but there is a tendency to cause problems such as misregistration of printing in actual use such as printing.
The moisture content of the PVA film can be measured using, for example, a Karl Fischer moisture meter (“MKS-210” manufactured by Kyoto Electronics Industry Co., Ltd.).

  Examples of the method for adjusting the moisture content of the PVA film include the following methods. That is, according to the moisture content adjustment method described below, it is possible to set the moisture content of the PVA film within the above range.

(1) The moisture content is adjusted by a method of increasing or decreasing the dryer temperature when forming a film by drying a dope in which PVA is dissolved to humidify or dehumidify the PVA film. The temperature of the dope is adjusted within the range of 70 to 98 ° C. because the temperature has an influence on the drying efficiency. In drying, the temperature is preferably 150 to 50 ° C., more preferably 145 to 60 ° C., in at least two hot air dryers having a temperature gradient, preferably 1 to 15 minutes, more preferably Drying for 1 to 12 minutes is preferable from the viewpoint of moisture adjustment.

  If the gradient range of the drying temperature is too large or the drying time is too long, there is a tendency to overdry, and conversely if the gradient range of the drying temperature is too small or the drying time is too short, the drying is insufficient. Tend to be.

  The above temperature gradient gradually changes the drying temperature between 150 and 50 ° C. Usually, the temperature is gradually increased from the start of drying and once set until a predetermined moisture content is reached. It is effective to reach the highest moisture temperature in the drying temperature range, and then gradually lower the drying temperature to finally achieve the desired moisture content. This is performed to control crystallinity, releasability, productivity, and the like. For example, 120 ° C-130 ° C-115 ° C-100 ° C, 130 ° C-120 ° C-110 ° C, 115 ° C-120 ° C. The temperature gradient is set such as −110 ° C. to 90 ° C., and is appropriately selected and executed.

(2) The PVA film is humidified and dehumidified by passing it through a humidity control tank before winding the PVA film, and the moisture content is adjusted.

(3) Before winding the PVA film, the PVA film is dehumidified by heat treatment to adjust the moisture content.

The total light transmittance of the PVA film is usually 85% or more, preferably 85 to 93%. That is, if the total light transmittance is too low, color matching during printing tends to be difficult.
In addition, the total light transmittance of a PVA-type film can be measured using a haze meter (Nippon Denshoku Industries make, NDH 2000), for example.

  And as a retardation value of the said PVA-type film, it is preferable that it is 40 nm or less, and also 35 nm or less is preferable. This retardation value is indicated by the product of birefringence and film thickness (birefringence index × film thickness) of the PVA-based film, and the birefringence index is given in the film manufacturing process or the like. It is determined by the degree of molecular orientation. If the retardation value is too high, wrinkles are formed on the surface of the base film, and the formation of the printing layer is hindered, or when the base film is floated on the water surface, it is stretched in a non-uniform state and the printing pattern is deformed. There is a trend. As described above, as a method for setting the retardation value to 40 nm or less, for example, the PVA film is sufficiently dried on a drum or a belt, and is adjusted by winding it without applying tension in the subsequent steps. How to do.

In addition, the elongation at break of the PVA film is preferably 150% or more, more preferably 180% or more under 23 ° C. and 50% RH humidity control conditions. That is, if the elongation at break is too low, there is a tendency for paper breakage to occur at the time of printing or to reduce the throwing power at the time of transfer.
In addition, the breaking elongation of a PVA-type film is measured based on JISK7127 (1999).

  Thus, it is preferable to set the PVA-type film obtained by film forming in the range of thickness 20-50 micrometers, More preferably, it is 25-45 micrometers.

  And the PVA-type film (raw film) obtained by forming the film is subjected to, for example, a conventionally known moisture-proof packaging so as not to cause a change in the moisture content described above, and an atmosphere of 10 to 25 ° C. It is preferable to store in a suspended state below.

Next, a hydraulic transfer printing method using the base film of the present invention will be described.
Examples of the hydraulic transfer printing method include a continuous hydraulic transfer printing method and a batch hydraulic transfer printing method.

First, the hydraulic transfer printing method by the continuous method will be described.
That is, a predetermined design is printed on the base film surface obtained as described above. Thereafter, an ink activator is applied to the design printing surface. In order to prevent the base film from extending and absorbing the design after water absorption, a restriction of 1.5 times or less, preferably 1.4 times or less in the width direction with respect to the flow direction of the base film is provided. The base film is floated on the liquid surface and moved with the applied design printing surface facing upward. Hydraulic transfer printing is performed by pressing the transfer object from above the moving base film and transferring and fixing the design printed on the base film surface to the transfer object surface. And after adhering, the target product is obtained by removing the base film and sufficiently drying the transferred body onto which the design has been transferred.

On the other hand, the hydraulic transfer printing method by the batch method will be described.
That is, a predetermined design is printed on the base film surface obtained as described above. Thereafter, an ink activator is applied to the design printing surface. And like the above continuous method, the base film is stretched after water absorption, and the length and breadth regulation is 1.5 times or less, preferably 1.4 times or less in each of the vertical and horizontal directions with respect to the base film so that the design is not blurred. The base film is floated on the liquid surface with the design printing surface coated with the ink activator facing upward. Then, the transfer body is pressed from above the base film in a stationary state, and the design printed on the surface of the base film is transferred to the transfer body and sufficiently fixed to perform hydraulic transfer printing. After fixing, the target product is obtained by sufficiently drying the transferred body from which the base film is removed and the design is transferred.

  The design printed on the surface of the base film can be transferred to the transfer object by the hydraulic transfer printing method passing through such steps. The design printed on the surface of the base film is not particularly limited, and any design can be used as long as it can be printed, such as wood grain, various patterns, and images.

  The ink activator to be applied to the design printing surface is not particularly limited, and a resin added to a solvent capable of reactivating the design printed on the base film surface is used. A plasticizer, a curing agent, and the like can be appropriately added. For example, butyl methacrylate mixed with a pigment, a plasticizer, butyl cellosolve acetate, and butyl carbitol acetate is used. Examples of the coating method of the ink activator include a coating method using a gravure roll or a spray.

  The step of applying the ink activator to the design printed surface may be performed either before or after the base film is floated on the liquid surface, and the base film on which the design is printed. If it is before pressing a to-be-transferred material from upper direction, it will not restrict | limit in particular.

  The material of the transfer target in the hydraulic transfer printing method of the present invention is not particularly limited, and for example, a plastic molded body, a metal molded body, a wooden molded body, an inorganic molded body such as glass, or the like is used. it can. Further, the shape is not particularly limited, and the shape may be a flat surface or various solid shapes.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
In the examples, “%” means weight basis unless otherwise specified.

Example 1
<Preparation of base film>
70% PVA resin (A1) having an average saponification degree of 88 mol%, 4% aqueous solution average viscosity (20 ° C.) of 50 mPa · s, an average saponification degree of 96 mol%, 4% aqueous solution average viscosity (20 ° C.) of 15 mPa 15 parts PVA-based resin (A2), average saponification degree 72 mol%, 4% aqueous solution average viscosity (20 ° C.) 6 mPa · s PVA-based resin (A3) 15 parts, glycerin 3 parts, starch 4 parts , 20% (solid content concentration) dope consisting of 0.7 part of surfactant (polyoxyethylene sorbitan monolaurate) is discharged from T die to rotating stainless steel endless belt with surface temperature adjusted to 90 ° C Then, the film was cast and heat-treated with a hot roll adjusted to 95 ° C. to obtain a PVA film having a thickness of 40 μm, which was used as a base film for hydraulic transfer.

  The base film obtained above was evaluated as follows.

[Dispersibility of film]
Cut the film into a size of 3cm x 5cm, fix it on a jig, immerse it in 5 ° C or 30 ° C water (1 liter) in a 1 liter beaker, and stir with a stirrer until the film is dispersed The time (seconds) was measured. Here, the time until dispersion is defined as the time until the film is divided into three or more.

  In addition, using the base film obtained above, a transfer printing film was prepared as follows, and the transfer printing film after the elapse of 2 minutes was floated on the water surface with the ink activator application surface side facing upward, One minute later, when hydraulic transfer printing was performed on an ABS resin molded product (flat plate), a good and clear design could be obtained.

<Preparation of film for transfer printing>
The obtained base film was cut into a size of 200 mm × 200 mm, and a building material ink [mixture of red dye and barium sulfate (70%), alkyd resin and nitrocellulose mixture (30%)] Was applied uniformly by gravure printing on the α surface (belt surface) side when the film was cast (dry thickness of ink layer 2 μm). Thereafter, an ink activator (butyl methacrylate / pigment / plasticizer / butyl cellosolve acetate / butyl carbitol acetate = 8/20/20/26/26 (parts by weight)) is applied thereon with a wire bar coater (# 10). Thus, a transfer printing film was produced.

Examples 2-3 and Comparative Examples 1-2
A PVA film having a thickness of 40 μm was obtained in the same manner as in Example 1 except that PVA-based resins (A1), (A2) and (A3) were used in the blending amounts shown in Table 1, and this was used for hydraulic transfer. The base film was made.
About the base film obtained above, evaluation similar to Example 1 was performed.
Moreover, when the film for transfer printing was produced and the hydraulic transfer printing was performed similarly to Example 1, the favorable clear design was able to be obtained.
The evaluation results of Examples and Comparative Examples are shown in Table 1.

  From the above results, Examples 1 to 3 in which three types of PVA having different average saponification degrees are used in combination as PVA-based resins are excellent in film dispersibility and excellent in film removal after transfer. Recognize. On the other hand, it can be seen that Comparative Example 1 using two types of PVA and Comparative Example 2 using one type cannot obtain sufficient film dispersibility and are inferior in film removal properties.

  The base film for hydraulic transfer printing of the present invention can be widely applied to the application of hydraulic transfer printing to exteriors of mobile phones, various electrical appliances, building materials, household and household items, as well as automobile interior and exterior products. Can do.

Claims (7)

A base film for hydraulic transfer printing comprising a polyvinyl alcohol film, wherein the polyvinyl alcohol film comprises a polyvinyl alcohol resin (A1) having an average saponification degree of 80 to 95 mol% and a polyvinyl alcohol resin (A1). The polyvinyl alcohol resin (A2) having a higher average saponification degree and a polyvinyl alcohol resin containing the polyvinyl alcohol resin (A3) lower than the average saponification degree of the polyvinyl alcohol resin (A1). A base film for hydraulic transfer printing. The liquid according to claim 1, wherein the polyvinyl alcohol resin (A2) having an average saponification degree higher than that of the polyvinyl alcohol resin (A1) is a polyvinyl alcohol resin having an average saponification degree of 90 to 100 mol%. Base film for pressure transfer printing. The polyvinyl alcohol resin (A3) having an average saponification degree of 65 to 85 mol% is lower than the average saponification degree of the polyvinyl alcohol resin (A1). Base film for hydraulic transfer printing. Ratio (y / x) of average viscosity (y) of 4 wt% aqueous solution of polyvinyl alcohol resin (A2) at 20 ° C to average viscosity (x) of 4 wt% aqueous solution of polyvinyl alcohol resin (A1) at 20 ° C The base film for hydraulic transfer printing according to any one of claims 1 to 3, wherein is 0.1 to 0.5. Ratio (z / x) of average viscosity (z) of 4 wt% aqueous solution of polyvinyl alcohol resin (A3) at 20 ° C to average viscosity (x) of 4 wt% aqueous solution of polyvinyl alcohol resin (A1) at 20 ° C The base film for hydraulic transfer printing according to any one of claims 1 to 4, wherein the base film is 0.1 to 0.5. The content of the polyvinyl alcohol resin (A1) is 40 to 98% by weight with respect to the total amount of the polyvinyl alcohol resin (A1), the polyvinyl alcohol resin (A2), and the polyvinyl alcohol resin (A3). 6. The hydraulic transfer printing according to claim 1, wherein the content of the resin (A2) is 1 to 40% by weight and the content of the polyvinyl alcohol-based resin (A3) is 1 to 40% by weight. Base film. The base film for hydraulic transfer printing according to any one of claims 1 to 6, wherein the polyvinyl alcohol film has a thickness of 20 to 50 µm.