JP2010155453A - Base film for hydraulic transfer printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base film for hydraulic transfer printing, which is excellent in transfer printability and in dissolvability or dispersibility of polyvinyl alcohol-based film, and improved in the productivity. <P>SOLUTION: In the base film for hydraulic transfer printing including polyvinyl the alcohol-based film, the polyvinyl alcohol-based film includes: a polyvinyl alcohol-based resin (A1), in which the viscosity in 4 wt.% aqueous solution at 20°C is 15-50 mPa s; and a polyvinyl alcohol-based resin (A2), in which the viscosity in 4 wt.% aqueous solution at 20°C is 1-10 mPa s. <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 method for printing a design on the surface of a three-dimensional molded product having a complicated surface shape, a transfer film having a printing layer on which the design is formed on the surface of the base film is used. After floating on the liquid surface (water surface) so as to be the upper surface, a predetermined molded body (transferred body) for transferring the printing layer is pushed in from above, and the printing layer of the transfer film is formed on the surface of the molded body by liquid pressure. There are known methods for transcribing. As such a base film for hydraulic transfer printing, a polyvinyl alcohol film having a polyvinyl alcohol resin as a forming material is used. From the viewpoint of film strength, a viscosity of 25 to 50 mPa · s is usually used at a viscosity of 4 wt% at 20 ° C. The polyvinyl alcohol-based resin film is used.

  In such a hydraulic transfer method, various base films have been studied depending on 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 patent document, a good design is obtained, but the solubility or dispersibility of the polyvinyl alcohol film after transfer is insufficient. If the polyvinyl alcohol film after transfer is insufficiently soluble or dispersible, the polyvinyl alcohol film partially remains on the design surface, and the top-coated protective layer partially drops off after transfer. There is a problem that it may occur, and further dissolution or dispersibility of the film is required.

  Further, a hydrophobic transfer layer that can be dissolved in an organic solvent is formed on the surface of the base film, and the base film is floated on the surface of the water, and an activator is applied to the transfer layer to activate the transfer layer. After that, the object to be transferred is pressed against the transfer layer, the transfer layer is transferred to the surface of the object to be transferred, the base film is removed, and then the transfer object to which the transfer layer is transferred is irradiated with active energy rays. When the transfer method is applied, the transfer layer is cured by applying at least one of heating and heating, and the design transferred to the transfer object is fixed, so that the moisture does not enter from the cured layer side and the swelling behavior of the transfer film In this respect, the solubility of the base film is a particular problem, and a base film having further excellent solubility or dispersibility is demanded.

  Therefore, the present invention has been made in view of such circumstances, and is a base for hydraulic transfer printing that is excellent in transfer printing suitability and excellent in solubility or dispersibility of a polyvinyl alcohol film and can improve productivity. The purpose is to provide a film.

  However, the present inventor conducted extensive studies to achieve the above-mentioned object, and paid attention to the resin composition of the base film, and as a result of conducting research mainly on this, as a resin composition constituting the polyvinyl alcohol-based film, By including at least two types of polyvinyl alcohol resins having a molecular weight and a low molecular weight, but having different molecular weights, the transfer printing characteristics are excellent, and the polyvinyl alcohol film after transfer has excellent solubility or dispersibility. As a result, the present invention has been completed.

  That is, the gist of the present invention is a base film for hydraulic transfer printing including a polyvinyl alcohol-based film, wherein the polyvinyl alcohol-based film has a viscosity of 15 to 50 mPa · s at a viscosity of 4 wt% aqueous solution at 20 ° C. The present invention relates to a base film for transfer printing comprising a resin (A1) and a polyvinyl alcohol resin containing 1 to 10 mPa · s of a polyvinyl alcohol resin (A2) at a viscosity of 4% by weight at 20 ° C.

  The base film for hydraulic transfer printing of the present invention is excellent in transfer printing characteristics, and has an effect of being excellent in solubility or dispersibility of the polyvinyl alcohol film after transfer, and further, irradiation with active energy rays and heating. When applying a transfer method that hardens the transfer layer by applying at least one of the above and adheres the design transferred to the transfer object, the transfer layer exerts a remarkably excellent effect, including automobile interior and exterior products. As such, it can be widely applied to the application of hydraulic transfer printing to the exterior of mobile phones, various electrical appliances, building materials, household and household items.

Hereinafter, the present invention will be described in detail.
The base film for hydraulic transfer printing of the present invention (hereinafter sometimes simply referred to as a base film) includes a polyvinyl alcohol film.

  In the present invention, “including a polyvinyl alcohol film” means that other layers (film, coating film, etc.) are 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, a 4 wt% aqueous solution at 20 ° C. is used as the PVA resin. It contains a PVA resin (A1) having a viscosity of 15 to 50 mPa · s and a PVA resin (A2) having a viscosity of 4 to 10% by weight at 20 ° C. and having a viscosity of 1 to 10 mPa · s.

  Here, the PVA system means PVA itself or, for example, PVA modified with various modified species, and the degree of modification is usually 20 mol% or less, preferably 15 mol% or less, more preferably It is 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, polyoxyethylene (meth) acrylamide, polyoxyalkylene (meth) acrylamides such as polyoxypropylene (meth) acrylamide, 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, (1) acetic acid A method of saponifying a copolymer of vinyl and 3,4-diacetoxy-1-butene, (2) a method of saponifying and decarboxylating a copolymer of vinyl acetate and vinyl ethylene carbonate, and (3) vinyl acetate. Of saponifying and deketalizing a copolymer of 2,2-dialkyl-4-vinyl-1,3-dioxolane, and (4) saponifying a copolymer of vinyl acetate and glycerol monoallyl ether. Obtained by a method, etc.

As PVA-type resin (A1) used by this invention, it is required that it is 15-50 mPa * s by 4 weight% aqueous solution viscosity in 20 degreeC, Preferably it is 15-45 mPa * s, Most preferably, it is 16-40 mPa. -S. If the viscosity of the 4% by weight aqueous solution of the PVA-based resin (A1) is too small, the strength of the film is insufficient, causing breakage during use, and if it is too large, the solubility is insufficient.
The viscosity of the 4 wt% aqueous solution at 20 ° C. is measured according to JIS K 6726.

In addition, the average degree of saponification of the PVA resin (A1) is preferably in the range of 70 to 98 mol%, particularly in the range of 75 to 95 mol%, more preferably in the range of 80 to 90 mol%. Preferably there is. If the average saponification degree is too low or too high, the solubility tends to decrease.
The average saponification degree of the PVA resin is measured according to JIS K 6726.
The PVA-based resin (A1) can be usually obtained by appropriately selecting from commercially available products.

  The PVA resin (A2) used in the present invention is required to have a viscosity of 4% by weight aqueous solution at 20 ° C. of 1 to 10 mPa · s, preferably 2 to 9 mPa · s, particularly preferably 3 to 8 mPa · s. s. If the viscosity of the 4% by weight aqueous solution of the PVA resin (A2) is too small, it is difficult to produce a stable resin, and if it is too large, the effect of improving the solubility is lost.

The PVA resin (A2) preferably has an average degree of saponification in the range of 70 to 98 mol%, particularly in the range of 75 to 95 mol%, more preferably in the range of 80 to 90 mol%. Preferably there is. If the average saponification degree is too low or too high, internal haze is generated in the film, and the appearance tends to be poor.
The PVA-based resin (A2) can be usually obtained by appropriately selecting from commercially available products.

  In the present invention, in the comparison of the 4 wt% aqueous solution viscosity of the PVA resin (A1) and the 4 wt% aqueous solution viscosity of the PVA resin (A2), the 4 wt% aqueous solution viscosity of the PVA resin (A2) is 5 to 50% smaller than 4% by weight aqueous solution viscosity of the resin (A1) is preferable in terms of solubility and film strength, particularly preferably 10 to 50% smaller, and more preferably 15 to 47% smaller. Particularly preferably, it is 15 to 30% smaller. If the viscosity of the 4% by weight aqueous solution of the PVA resin (A2) is too small relative to the viscosity of the 4% by weight aqueous solution of the PVA resin (A1), it tends to be difficult to obtain the resin. There is a tendency that the improvement effect becomes smaller.

  Moreover, in the comparison of the average saponification degree of PVA-type resin (A1) and the average saponification degree of PVA-type resin (A2), it is preferable that the difference is 3 mol% or less from the viewpoint of good film appearance. Particularly preferably, it is 2 mol% or less, more preferably 1.5 mol% or less, and it is particularly preferable that there is substantially no difference. When the difference in the average saponification degree is too large, the internal haze tends to increase.

  Furthermore, about the content rate of PVA-type resin (A1) and PVA-type resin (A2), PVA-type resin (A2) may be 10-50 weight part with respect to 100 weight part of PVA-type resin (A1). From the viewpoint of film strength and solubility, it is preferably 10 to 40 parts by weight, more preferably 15 to 35 parts by weight. When there is too little content of PVA-type resin (A2), there exists a tendency for a solubility improvement effect to lose | eliminate, and when there is too much, there exists a tendency for film strength to be insufficient.

  In the present invention, the PVA resin (A1) and the PVA resin (A2) are used in combination, but a PVA resin other than the PVA resin (A1) and the PVA resin (A2) is further added. It can also be used together.

  Thus, in the present invention, a PVA-based film is formed by using a PVA-based resin (A1) and a PVA-based resin (A2) as a PVA-based resin. Is done.

  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, K 3 C 6 H 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, pentaborate) Ammonium, ammonium octaborate, etc.), cadmium borate (cadmium orthoborate, cadmium tetraborate, etc.), potassium borate (potassium metaborate, potassium tetraborate, potassium pentaborate, potassium hexaborate, octaborate) Potassium), 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, UV absorbers, inorganic powders, organic powders (starch, polymethyl methacrylate, etc.), and other water-soluble polymer compounds (sodium polyacrylate, 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.

Further, the total light transmittance of the PVA-based film is usually 80% or more, preferably 85 to 99%, and particularly preferably 85 to 95%. 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. The lower limit of the retardation value is usually 3 nm.

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. The upper limit of the elongation at break is usually 300%.
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 20-50 micrometers in thickness, More preferably, it is 23-47 micrometers, Especially preferably, it is 25-45 micrometers. If the film thickness is too thin, the printed film will swell quickly and unsuitable for transfer. If it is too thick, the film will remain on the transfer or the concentration of PVA resin in the water in the transfer bath will increase rapidly, resulting in a drainage load. There is a tendency to grow.

  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.
The hydraulic transfer method using the base film of the present invention can be used for various conventional hydraulic transfer methods. For example, (1) a hydraulic transfer method using a continuous method, (2) a hydraulic pressure using a batch method. Examples thereof include a transfer method.

First, (1) the hydraulic transfer 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 activator is applied to the design printed surface. Then, the design printing surface on which the activator is applied by providing, for example, a regulation of 1.3 times or less in the width direction with respect to the flow direction of the base film so that the base film extends after water absorption and the design is not blurred. The base film is floated on the liquid level and moved with the face up. Hydraulic transfer printing is performed by pressing the transferred body from above the moving base film and transferring and fixing the design printed on the surface of the base film to the surface of the transferred body. 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, (2) the batch-type hydraulic transfer method will be described.
That is, a predetermined design is printed on the base film surface obtained as described above. Thereafter, an activator is applied to the design printed surface. Then, as in the continuous method, the base film is stretched after water absorption, so that the design is not blurred. The base film is floated on the liquid surface with the printed surface of the design coated with the surface facing upward. Then, hydraulic transfer printing is performed by pressing the transfer medium from above the base film in a stationary state, transferring the design printed on the surface of the base film to the transfer medium, and sufficiently fixing it. After fixing, the target product is obtained by removing the base film and sufficiently drying the transferred body onto which the design has been transferred.

  The activator to be applied to the design printing surface is not particularly limited, and a resin added to a solvent that can reactivate the design printed on the base film surface, and further, a pigment, a plasticizer A curing agent or 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 method for applying the activator include an application method using a gravure roll or spray.

  The step of applying the activator on the design printing surface may be performed either before or after the base film is floated on the liquid surface, and above the base film on which the design is printed. If it is before pressing a to-be-transferred material from, there will be no restriction | limiting in particular.

In addition to the above-described continuous and batch hydraulic transfer methods, the following hydraulic transfer method (3) may be mentioned.
That is, after printing a predetermined design in a dry state on the surface of the base film obtained as described above, an active energy ray-curable resin composition such as a solventless ultraviolet ray or electron beam containing a photopolymerizable monomer An object is applied to wet the dried design. After that, the base film is floated on the water surface with the wet design printing surface facing upward, the transferred material is pressed from above the base film, and the design printed on the base film surface is transferred to the surface of the transferred material. Next, a hydraulic transfer method of fixing the transferred design to the transferred object by irradiating the transferred object to which the design is transferred with an active energy ray such as ultraviolet ray or electron beam to cure the curable resin composition. Can be given.

Further, as another hydraulic transfer method, there is the following hydraulic transfer method (4).
That is, a hydrophobic transfer layer (design) that can be dissolved in an organic solvent is formed on the surface of the base film obtained as described above, and preferably a peelable release film is laminated on the transfer layer. Prepare a transfer film. Next, after peeling off the release film, the base film is floated on the water surface, and an activator is applied to the transfer layer to activate the transfer layer. Next, the transfer material is pressed against the transfer layer to transfer the transfer layer to the transfer material surface, and then the base film is removed. Then, the transfer layer (design) is transferred to the transfer target body by applying at least one of irradiation and heating of active energy rays such as ultraviolet rays and electron beams, and the transfer layer (design) is cured. There is a hydraulic pressure transfer method in which the design transferred to is fixed.
Here, examples of the organic solvent include toluene, xylene, carbitol, carbitol acetate, butyl carbitol acetate, butyl cellosolve, cellosolve acetate, butyl cellosolve acetate, methyl isobutyl ketone, ethyl acetate, isobutyl acetate, isobutyl alcohol, isopropyl alcohol. , N-butanol, sol-fit acetate, and the like, and mixtures thereof.

  Here, the transfer layer preferably has a curable resin layer, more preferably a curable resin layer provided on the base film and a printing ink film provided on the curable resin layer or It includes a decorative layer having a paint film.

  The curable resin layer is preferably a polyurethane (meth) acrylate having 3 or more (meth) acryloyl groups in one molecule and a polyester having 3 or more (meth) acryloyl groups in one molecule (meta ) Acrylate and an active energy ray-curable resin selected from epoxy (meth) acrylate having 3 or more (meth) acryloyl groups in one molecule.

  The base film for hydraulic transfer printing of the present invention has a film strength sufficient to withstand hydraulic transfer printing, especially when used for the hydraulic transfer method (4) among the above-mentioned hydraulic transfer printing methods. In addition, regardless of the fact that the hydrophobic curable resin layer is formed, the base film can exhibit an excellent effect on the solubility or dispersibility of the base film.

  The irradiation of the active energy ray is performed using a conventionally known ultraviolet irradiation device including a light source lamp such as a high-pressure mercury lamp and a metal halide lamp and an irradiator (lamp house) in the case of ultraviolet rays. It is.

  In addition, in the case of curing by irradiation with active energy rays, it is preferable to add a photopolymerization initiator, and the photopolymerization initiator has a function of initiating a polymerization reaction by absorbing light such as ultraviolet rays. For example, acetophenone compounds such as diethoxyacetophenone and 1-hydroxycyclohexyl-phenylketone, benzophenone, benzophenone compounds such as methyl-4-phenylbenzophenone o-benzoylbenzoate, benzoin compounds such as benzoin and benzoin isopropyl ether, Acylphosphine oxide compounds, thioxanthone compounds, aminobenzophenone compounds, polyether maleimide carboxylic acid ester compounds, and the like are used. These can also be used in combination.

  In addition to the photopolymerization initiator, the curable resin composition includes a photopolymerizable monomer, a sensitizer, a filler, an inert organic polymer, a leveling agent, a thixotropy imparting agent, and a thermal polymerization as necessary. Additives such as inhibitors can be added as appropriate.

  In the present invention, the design printed on the surface of the base film can be transferred to the transfer target by the hydraulic transfer printing method passing through the above-described 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 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>
85% PVA (A1) with 4% aqueous solution viscosity (20 ° C.) 18 mPa · s, average saponification degree 88 mol%, 4 m aqueous solution average viscosity (20 ° C.) 5 mPa · s, average saponification degree 88 mol% PVA (A2) 15 parts, glycerin 2 parts, starch 6 parts, surfactant (polyoxyethylene sorbitan monolaurate) 1.2 parts are dissolved in water to obtain an 18% (solid content concentration) aqueous dispersion (dope) ) Was prepared. Such a dope is discharged from a T-die onto a rotating stainless steel endless belt whose surface temperature is adjusted to 80 ° C., cast at a speed of 10 m / min, and subsequently heated with a heat roll adjusted to 80 ° C. Heat treatment was performed to obtain a 30 μm thick PVA film, which was used as a base film for hydraulic transfer.

<Preparation of curable resin composition>
60 parts (mass average molecular weight 890) of an average hexafunctional urethane acrylate (UA1) obtained by reacting 2 molar equivalents of pentaerythritol, 7 molar equivalents of hexamethylene diisocyanate and 6 molar equivalents of hydroxyethyl methacrylate, Rohm and Haas Curability of 42% solid content using 40 parts of acrylic resin “Paraloid A-11” (Tg 100 ° C., mass average molecular weight 125,000) and a mixed solvent of ethyl acetate and methyl ethyl ketone (mixing weight ratio 1/1) A resin composition was prepared.

<Preparation of decorative film (I)>
As the peelable film, a 50 μm-thick unstretched polypropylene film (hereinafter abbreviated as PP film) manufactured by Toyobo Co., Ltd. was used, and urethane ink (trade name: Univia A) was thickened on the film with a gravure 4-color printing machine. A decorative film (I) was prepared by printing a 3 μm grain pattern.

<Preparation of hydraulic transfer film (II)>
On the belt surface side of the base film, the curable resin composition is applied with a lip coater so that the film thickness after drying is 20 μm, and then dried at 60 ° C. for 2 minutes to form a curable resin composition layer. After the base film is prepared, the curable resin composition layer of this film and a uniaxially stretched polypropylene film (hereinafter abbreviated as OPP film) manufactured by Toyobo Co., Ltd. are laminated at 60 ° C., and the laminated film is wound up as it is. Thus, a hydraulic transfer film (II) was prepared.

<Preparation of hydraulic transfer film (III)>
After peeling the OPP film from the hydraulic transfer film (II), the curable resin composition layer and the ink layer of the decorative film (I) are faced and laminated at 60 ° C., and the laminated film is wound again as it is. A film for water pressure transfer (III) was prepared.
The obtained hydraulic transfer film (III) is peeled off from the PP film at the time of use. At this time, the ink layer is transferred onto the curable resin composition layer on the PVA film side without any defects.
The obtained hydraulic transfer film (III) was evaluated as follows.

<Evaluation methods>
After the hydraulic transfer film (III) obtained above was cut into a size of 3 cm × 5 cm, the PP film was peeled off, and the PVA film side was fixed to the lower surface on a jig that can fix the film parallel to the water surface. Next, water (1 liter) is put into a 1 liter beaker, immersed in water so that the sample fixing height is at a marked line position of 600 cc while maintaining the water temperature at 30 ° C. while stirring with a stirrer. While continuing to stir at 400 rpm using a stir bar, the melting state of the PVA film on the lower surface side was confirmed.
The confirmation method was taken out from the water when a predetermined time had elapsed, touched the PVA film surface, examined for the presence of slimming, and evaluated according to the following criteria.
○ ... Sliminess disappears in less than 5 minutes.
X ... The slime does not disappear even after 5 minutes.

[Examples 2-4, Comparative Examples 1-3]
In Example 1, it carried out similarly except having changed the composition of PVA resin as shown in Table 1, and obtained the 30-micrometer-thick PVA film, and this was made into the base film for hydraulic transfer printing.

  The evaluation results of Examples and Comparative Examples are shown in Table 1.

  From the above results, as examples of the PVA resin in which two types of predetermined PVA are used in combination, the single-sided surface is covered with a hydrophobic curable resin composition layer, but has excellent solubility or dispersibility. On the other hand, in Comparative Example 1 in which only one type of PVA used for a conventional base film was not blended with a low molecular weight PVA, sufficient solubility or dispersibility was not obtained. When two types of PVA are used in combination, it can be seen that if any of the viscosity ranges of the two types of PVA is out of the range, the solubility or dispersibility is poor. This is because PVA (A2) is contained in a small amount relative to PVA (A1), so that PVA (A1) is easily disintegrated and easily dissolved or dispersed. Conventional PVA (A1) It can be inferred that the PVA swells and becomes sticky and easily remains.

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

Claims (7)

  A base film for hydraulic transfer printing comprising a polyvinyl alcohol-based film, wherein the polyvinyl alcohol-based film has a viscosity of 4 to 50% aqueous solution at 20 ° C. and a polyvinyl alcohol resin (A1) of 15 to 50 mPa · s at 20 ° C. A base film for hydraulic transfer printing comprising a polyvinyl alcohol-based resin containing a polyvinyl alcohol-based resin (A2) having a viscosity of 4% by weight in an aqueous solution of 1 to 10 mPa · s.   The 4% by weight aqueous solution viscosity of the polyvinyl alcohol resin (A2) at 20 ° C is 5 to 50% smaller than the 4% by weight aqueous solution viscosity of the polyvinyl alcohol resin (A1) at 20 ° C. The base film for hydraulic transfer printing as described.   The amount of the polyvinyl alcohol-based resin (A2) is 10 to 50 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol-based resin (A1). Base film.   The average saponification degree of the polyvinyl alcohol resin (A1) is 70 to 98 mol%, and the average saponification degree of the polyvinyl alcohol resin (A2) is 70 to 98 mol%. 3. The base film for hydraulic transfer printing according to any one of 3.   The hydraulic pressure according to any one of claims 1 to 4, wherein the difference between the average saponification degree of the polyvinyl alcohol resin (A1) and the average saponification degree of the polyvinyl alcohol resin (A2) is 3 mol% or less. Base film for transfer printing.   The base film for hydraulic transfer printing according to any one of claims 1 to 5, wherein the polyvinyl alcohol film has a thickness of 20 to 50 µm.   Form a hydrophobic transfer layer that can be dissolved in an organic solvent on the base film surface, float on the water surface with the base film down, and apply the activator to the transfer layer to activate the transfer layer. After the transfer material is pressed against the transfer layer, the transfer layer is transferred to the surface of the transfer material, the base film is removed, and then the transfer material to which the transfer layer is transferred is irradiated with active energy rays and heated. The base film for hydraulic transfer printing according to any one of claims 1 to 6, which is used in a hydraulic transfer method for curing the transfer layer by applying at least one of the above and fixing the design transferred to the transfer target.