JP2009280792A - Method for producing base film for hydraulic transfer printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a base film for hydraulic transfer printing, excellent in printability of designs and excellent in transfer efficiency. <P>SOLUTION: In the method for producing the base film for hydraulic transfer printing by forming a film from a water dispersion of a film-preparing raw material mainly composed of a polyvinyl alcohol-based resin, water having ≤5 ppm silicon content is used. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing 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-based resin film containing a polyvinyl alcohol-based resin as a main component 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, for example, in Patent Document 1, the base film is made of polyvinyl alcohol having a polymerization degree of 500 to 3000 and a saponification degree of 80 to 99.9 mol%, and has a moisture content of 1.5 to 4. Polyvinyl alcohol system having a width shrinkage of 0.01 to 1.5% when applied with a tension of 8.0 kg / m at 50 ° C. for 1 minute in the longitudinal direction of the film at 0%, a thickness of 20 to 50 μm It is proposed to use a resin film, and the film-forming raw material containing such polyvinyl alcohol is discharged onto a rotating drum of a drum-type film forming machine or a belt running on a belt-type film forming machine and dried to have a moisture content. It is described that it is produced by peeling from a drum or a belt at 1.5 to 4.0%.

JP 2005-60636 A

  However, in the conventional hydraulic transfer method using the polyvinyl alcohol-based resin film including Patent Document 1, the film stretches when a high-definition design is printed on the base film, or the base film before printing stretches. There is a problem that the printability is difficult because it is difficult to print according to the image, and there is still a need for improvement.

  Then, this invention aims at providing the manufacturing method of the base film for hydraulic transfer printing excellent in the printability at the time of printing a design on a base film in such a background.

  However, as a result of intensive studies to achieve the above object, the present inventor has found that water for dissolving or dispersing a film-forming raw material containing a polyvinyl alcohol resin as a main component is important. By producing a base film using very little water, it was found that the design was excellent in printability and effective for hydraulic transfer printing, and the present invention was completed.

  That is, the gist of the present invention is to form an aqueous dispersion of a film-forming raw material containing a polyvinyl alcohol resin as a main component, and to produce a base film for hydraulic transfer printing, water having a silicon content of 5 ppm or less. The present invention relates to a method for producing a base film for hydraulic transfer printing.

  Here, the use of water with a low silicon content is known in the production method of a raw polyvinyl alcohol film for a polarizing film (see JP 2007-009056 A), but in this case, The purpose is to not deteriorate the optical properties of the resulting polarizing film. However, in the case of a base film for hydraulic transfer printing as in the present invention, the optical properties of the film are not relevant, and therefore it is considered that there is no need to use special water, but on the other hand, it was operated for a long time. In some cases, it has been found that defects such as a decrease in the peelability of the film from the drum surface or the belt surface occur and the physical properties of the film to be formed decrease due to this. The raw film for polarizing film and the base film for hydraulic transfer printing have different film forming conditions such as temperature, concentration, etc., and there is a problem in film peelability from the drum or belt surface. This is the first problem in the present invention used for hydraulic transfer printing, and the present invention solves this.

  The base film for hydraulic transfer printing obtained by the method of the present invention has good design printability and is very useful as a base film for hydraulic transfer printing.

Hereinafter, the present invention will be described in detail.
In the present invention, an aqueous dispersion of a film-forming raw material mainly composed of polyvinyl alcohol (hereinafter sometimes abbreviated as PVA) resin is formed, and a base film for hydraulic transfer printing is produced. A base film for hydraulic transfer printing is produced using water having a silicon content of 5 ppm or less.
In the present invention, the “main component” means that the PVA resin is contained in an amount of 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, and particularly preferably 80% by weight or more. In addition, it is intended to include the case of only PVA resin.

  The above PVA resins may be used alone or in combination of two or more as required. The PVA-based resin 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 such 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 ethers, polyoxyethylene (meth) allyl ether, polyoxyalkylene (meth) allyl ether such as polyoxypropylene (meth) allyl ether, polyoxyethylene (meth) acrylate, Polyoxyalkylene (meth) acrylates such as reoxypropylene (meth) acrylate, polyoxyethylene (meth) acrylamide, polyoxyalkylene (meth) acrylamides such as polyoxypropylene (meth) acrylamide, polyoxyethylene [1- (meta ) Acrylamide-1,1-dimethylpropyl] ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine, N-acrylamidomethyltrimethylammonium Chloride, allyltrimethylammonium chloride, dimethyldiallylammonium chloride, dimethylallyl vinyl ketone N- vinylpyrrolidone, vinyl chloride, vinylidene chloride and the like. In addition to the above, modified species containing active hydrogen such as acetoacetyl group modification, mercapto group modification, diacetone acrylamide modification, and the like are also included. The above monomers may be used alone or in combination of two or more.

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

  In this invention, it is preferable that the average viscosity in 20 degreeC of the 4 weight% aqueous solution of the said PVA-type resin is the range of 10-70 mPa * s, and it is more preferable that it is the range of 15-60 mPa * s. If the average viscosity of the 4% by weight aqueous solution is too low, printing strength tends to be generated due to insufficient film strength when a design (pattern, pattern, etc.) is printed on the base film. However, there is a tendency that the transfer time is shortened due to the acceleration of the film, and the design printed on the film when it floats on water is not stable, and the throwing power is lowered. On the other hand, if the average viscosity of the 4% by weight aqueous solution is too high, the adhesiveness between the transferred material and the base film on which the design is printed is lowered during transfer of the printed design to the transferred material, and wrinkles and peeling occur. Although there is a tendency to occur, and the extension of the film on the surface of the water can be suppressed, the transfer time is delayed and the viscosity is high and the film formation tends to be difficult. The average viscosity of the 4% by weight aqueous solution at 20 ° C. is measured according to JIS K 6726.

  Furthermore, it is preferable that the average saponification degree of the said PVA-type resin is the range of 70-98 mol% normally, More preferably, it is the range of 75-96 mol%. If the average saponification degree of such a PVA resin is too low, there is a tendency that it takes a long time to dissolve the base film after transfer. If it is too high, the dissolution time of the base film is delayed, and the film strength at the time of transfer is low. Since it is high, there is a tendency that creases occur at the time of transfer, and even if transfer is performed, film removal failure tends to occur. The saponification degree is measured according to JIS K 6726.

  Moreover, in addition to said PVA-type resin, it is also preferable to mix | blend a plasticizer as needed. 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 preferably 10 parts by weight or less, more preferably 5 parts by weight or less, and particularly preferably 0.05 to 4 parts by weight with respect to 100 parts by weight of the PVA resin. When there is too much content of the said plasticizer, the dimensional stability at the time of printing a design on a film surface is bad, and the tendency for high-definition printing to become difficult is seen. In addition, when there is too less than the said range, there exists a tendency for the plastic effect to be low and to cause the fracture | rupture of the obtained base film.

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

  For example, it is preferable to add a surfactant for the purpose of improving the peelability between a metal surface such as a drum or belt as a base 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 usually 0.01-5 weight part with respect to a total of 100 weight part of PVA-type resin and a plasticizer, and it is 0.03-4.5 weight part. Is more preferable. 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.

  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 (silicon dioxide, etc.), organic powders (starch, polymethyl methacrylate, etc.), and other water-soluble polymer compounds (sodium polyacrylate, polyethylene oxide, polyvinylpyrrolidone, dextrin, chitosan, chitin, Methyl cellulose, hydroxyethyl cellulose, etc.) may be added.

Next, the manufacturing method of the base film for hydraulic transfer printing is demonstrated.
First, raw materials such as the PVA resin and plasticizer are blended in a predetermined blending amount to prepare a film forming raw material. The film-forming raw material is usually dispersed in water, preferably 10 to 40% by weight, particularly preferably 15 to 35% by weight, and supplied to the film-forming step.

Here, in the present invention, it is necessary to use water having a silicon content of 5 ppm or less, preferably 4 ppm or less, particularly preferably 3 ppm or less, and preferably as little as possible. By using water having a low silicon content, an effect can be obtained that a film having good film peelability from the surface of the film forming drum or film forming belt and having no deflection can be obtained. When the silicon content exceeds the above range, when long-term continuous operation is performed during the film forming process, the peelability of the film from the surface of the film forming drum or the film forming belt is lowered, the film is stretched, The change of wettability causes problems such as spots on design printing.
In addition, about content of the silicon contained in water, it measures by the molybdenum blue method.

  As the water, it is preferable to use water close to pure water from which impurities are removed. For example, ion exchange water or the like is used. In addition, so-called industrial water can be used as long as it does not depart from the spirit of the present invention. In consideration of productivity and cost, industrial water, soft water, ion-exchanged water, or the like can be used in combination. preferable. Furthermore, in the present invention, it is better that the number of chlorine atoms is small, and it is preferable to use water having, for example, less than 0.5 ppm as residual chlorine.

  Next, it is manufactured by casting an aqueous dispersion of a film-forming material from a T-die onto a film-forming belt or film-forming drum, drying it to form a film, and preferably further heat-treating.

  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, one or more heat treatment rolls having a surface temperature of 50 to 140 ° C., preferably 60 to 130 ° C., are taken up after being peeled from the film forming belt or the first film forming drum of the film forming drum. It is preferable to pass through. 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.

  Then, after peeling from the film forming belt or the first film forming drum and until winding, the aqueous dispersion of the film film forming material discharged from the T die or the like is dried on the film forming belt or the first film forming drum. The film is formed into a film and is peeled off from the film forming belt or the first film forming drum, preferably through a heat treatment machine and wound up by a winder.

  It is preferable to perform heat processing by the said heat processing apparatus normally at 50-140 degreeC, More preferably, it is 60-130 degreeC. When the temperature of the heat treatment is too low, the curling of the surface in contact with the film forming belt or the film forming first drum is strong, and there is a tendency to cause problems in the printing and transfer processes. When the temperature of the heat treatment is too high, There is a tendency for the water solubility of the base film to decrease. Furthermore, although the time required for the heat treatment depends on the surface temperature of the heat treatment roll, it is usually preferable to set the time to 0.5 to 15 seconds. The heat treatment is usually performed with a separate heat treatment roll following the drying roll treatment for drying the film.

  Thus, a base film can be obtained. In the present invention, the base film preferably has the following specific film characteristics.

That is, its specific film characteristics, with respect to the width direction of the film, one region within 30% of the overall width from the end (S ₁₎ and the other from the end portion within 30% of the total width of the area (S ₂ ) Is a film surface deflection rate (T) (%) of 3% or less, preferably 2.5% or less, more preferably 2% or less, and particularly preferably 1.5% or less. If the deflection rate (T) of the film surface is too large, it tends to cause wrinkles during design printing, which may hinder processing productivity. The lower limit value of the deflection rate (T) of the film surface is usually 0.1%.

In the present invention, other than the region (S ₁ ) within 30% of the total width from one end and the region (S ₂ ) within 30% of the total width from the other end in the width direction of the film. The film surface deflection rate (T) (%) in the region (S ₃ ) is preferably 3% or less from the viewpoint of printing suitability, more preferably 2.5% or less, and particularly preferably 2% or less. is there. When the deflection rate (T) of the film surface is too large, there is a tendency that wrinkles occur during printing of the design on the water-soluble film, resulting in poor printing. The lower limit value of the deflection rate (T) of the film surface is usually 0.1%.

In the present invention, the film surface deflection rate (T) is measured as follows.
That is, in an environment of 23 ° C. × 50% RH, the film was unwound from a roll sample wound with a base film having a predetermined width (w) (hereinafter also simply referred to as “film”), and the unwound film was 2 m apart and the same height. In an apparatus for winding after passing over two horizontal guide rolls (diameter: 120 mm) installed on the film, the film is unwound at an arbitrary length after unwinding the film at a length of 1 kg per 1 m of film width. The film 1 is temporarily stopped on the guide rolls, and at that time, as shown in FIG. 1, the area of the film 1 (S ₁ ) between the guide rolls based on the height of the film 1 passing over the guide rolls. (S ₂₎ and in each of the (S _3), measure the maximum value (h) of the height difference of the way to the hanging by being part of the in each region, calculates a deflection rate based on the distance as follows In measuring the height difference, the ultrasonic displacement sensor (UD-300 manufactured by Keyence) is run on the film 1 horizontally in the width direction. In addition, the sensor installation position in the flow direction is a central portion that is an equal distance from the two guide rolls.

Deflection rate (T) (%) = 100 × h / w
h: Maximum height difference (mm) up to the most drooping part in the film
w: Film width (mm)

In the present invention, the film width (w) is meant to include both the film width immediately after production and the film width after slitting each product size after production. The film width after slitting is advantageous from the viewpoint of printability.
At this time, the end portion to be slit is usually 2 to 50%, particularly preferably 5 to 30%, with respect to the entire film width immediately after production. Is done.

  Furthermore, in this invention, it is preferable that the moisture content of a base 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 base 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 base film include the following methods. That is, according to the moisture content adjustment method described below, the moisture content of the base film within the above range can be set.

(1) The moisture content is adjusted by a method of humidifying and dehumidifying the base film by raising and lowering the dryer temperature when the dope in which the PVA resin is dissolved is dried to form a film. The temperature of the dope is adjusted within the range of 70 to 98 ° C. because the temperature affects the drying efficiency. In drying, it is preferably 150 to 50 ° C., more preferably 145 to 60 ° C., in at least two or more hot air dryers having a temperature gradient, preferably 1 to 12 minutes, more preferably Drying for 1 to 11 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 base film is humidified and dehumidified by passing it through a humidity control tank before winding the base film, and the moisture content is adjusted.
(3) Before winding the base film, the base film is dehumidified by heat treatment to adjust the moisture content.

  The base film for hydraulic transfer printing obtained in the present invention is used for hydraulic transfer printing, and the film thickness of the film is generally 20 to 50 μm, preferably 23 to 47 μm, particularly preferably. 25-45 μm. If the film thickness is too thin than the above range, the printed film will swell quickly and unsuitable for transfer, and if it is thicker than the above range, the film may remain on the transfer or the concentration of polyvinyl alcohol resin in water in the transfer bath The drainage load tends to increase rapidly.

  The base film (raw film) obtained in the above is, for example, treated in a conventionally known moisture-proof packaging so that the moisture content does not change as described above, and is suspended in an atmosphere of 10 to 25 ° C. It is preferable to store them.

  In the present invention, if necessary, before film winding is performed, the film edge is slit as it is to the product size and then wound (online slit), or once the film is formed, if necessary. After winding up the subsequent film, it is unwound again and slit into the product size and wound up (off-line slit).

The film width after film formation (before slitting) obtained above is appropriately selected depending on the size of the product size, etc., but is usually preferably 300 to 4000 mm from the viewpoint of the product slit yield, in particular. The thickness is preferably 500 to 3000 mm, more preferably 700 to 2000 mm.
Further, the film length of the entire film is preferably 500 m or more, particularly 700 m or more, and more preferably 1000 m or more from the viewpoint of the efficiency of using the film. The lower limit of the film length is usually 100 m.

  Next, a method for printing and transferring a design using the base film of the present invention will be described.

  Examples of the hydraulic transfer method using the base film of the present invention include a continuous hydraulic transfer method and a batch hydraulic transfer method.

First, the hydraulic transfer method using the continuous method will be described.
That is, a predetermined design is printed on the surface of the base film obtained as described above. Thereafter, an activator is applied to the design printed surface. In order to prevent the base film from spreading and absorbing the design after water absorption, a regulation of 1.25 times or less in the width direction with respect to the flow direction of the base film is provided so that the design printing surface on which the activator is applied faces upward. The base film is floated on the liquid surface and moved. 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, 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 above continuous method, the base film is stretched after water absorption, and the active agent is applied with a vertical and horizontal restriction of 1.25 times or less in 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 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 fixed sufficiently 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 target by the hydraulic transfer method passing through such a process. 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 activator to be applied to the design print 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. An agent, a curing agent, and the like can be added as appropriate. 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.

  The material of the material to be transferred in such a hydraulic transfer method 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 can be used. . 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, “%” and “part” mean weight basis unless otherwise specified.

[Example 1]
100% PVA with 4% aqueous solution viscosity 26 mPa · s (20 ° C.), average saponification degree 88 mol%, 2 parts glycerin as plasticizer, 1.2 parts polyoxyethylene sorbitan monolaurate as surfactant, and 5 parts starch Was mixed with ion-exchanged water (silicon content 0.01 ppm or less) to obtain an 18% aqueous dispersion. Then, using the above aqueous dispersion, the film was formed according to the casting film forming method at a speed of 10 m / min with a belt film forming machine equipped with a stainless steel endless belt, and dried at a temperature of 95 ° C., After obtaining the PVA film, both ends of the film were slit, and a base film was continuously produced for 2 weeks (film width: 1000 mm, film length: rewound every 1000 m, film thickness: 30 μm). At that time, the tension required to peel the film from the belt surface during film formation was 1 kg / m. In addition, about the content of the silicon contained in water, it measured by the molybdenum blue method.
The obtained base film was evaluated as follows.

[Deflection rate (T) (%)]
Under an environment of 23 ° C. × 50% RH, the film was unwound from a roll sample wound with a film having a predetermined width (w), and the two unrolled horizontal guide rolls (at 2 m apart and placed at the same height) In an apparatus that winds up after passing over 120 mm in diameter, at an arbitrary length after unwinding the film, it is temporarily stopped on two guide rolls by applying a tension of 1 kg per 1 m of film width, At that time, as shown in FIG. 1, each of the regions (S ₁ ), (S ₂ ), and (S ₃ ) of the film 1 between the guide rolls with reference to the height of the film 1 passing over the guide rolls. The maximum value (h) of the height difference up to the most drooping part in each region was measured, and the deflection rate was calculated as follows based on the distance. In measuring the height difference, the film 1 was detected by running an ultrasonic displacement sensor (UD-300 manufactured by Keyence Corporation) horizontally in the width direction on the film 1. In addition, the sensor installation position in the flow direction was set at the central portion at an equal distance from the two guide rolls.

Deflection rate (T) (%) = 100 × h / w
h: Maximum height difference (mm) up to the most drooping part in the film
w: Film width (mm)

〔Moisture percentage〕
The moisture content of the obtained base film was measured using a Karl Fischer moisture meter (“MKS-210” manufactured by Kyoto Electronics Industry Co., Ltd.).

[Printability]
When a transfer design (pattern, pattern) was printed on the surface of the base film for transfer printing including the part where the peel tension was obtained by continuous operation for 2 weeks, the appearance of the film was visually observed, as follows: evaluated.
○ ・ ・ ・ No appearance defect × ・ ・ ・ Wrinkle

[Example 2]
100% PVA with 4% aqueous solution viscosity 26 mPa · s (20 ° C.), average saponification degree 88 mol%, 2 parts glycerin as plasticizer, 1.2 parts polyoxyethylene sorbitan monolaurate as surfactant, and 5 parts starch Was mixed with water having a silicon content of 4 ppm prepared by mixing ion-exchanged water (silicon content of 0.01 ppm or less) and water having a silicon content of 40 ppm to obtain an 18% aqueous dispersion. Then, using the above aqueous dispersion, the film is formed according to the casting film forming method at a speed of 10 m / min by a belt film forming machine equipped with a stainless steel endless belt, and dried at a temperature of 95 ° C. Then, after obtaining a PVA film, both ends of the film were slit and a base film was continuously produced for 2 weeks (film width: 1000 mm, film length: rewinded every 1000 m, film thickness: 30 μm). At that time, the tension required for peeling the film from the belt surface during film formation was 1.5 kg / m.
About the obtained base film, evaluation similar to Example 1 was performed.

[Comparative Example 1]
In Example 1, the same procedure was followed except that the water for preparing the aqueous dispersion of the film-forming raw material was changed to water having a silicon content of 40 ppm, and a base film was produced continuously for 2 weeks. At that time, the tension required to peel the film from the belt surface during film formation was 4 kg / m.
About the obtained base film, evaluation similar to Example 1 was performed.

  The evaluation results of the above examples and comparative examples are shown in Table 1.

  From the results of Table 1 above, in the examples, the tension required for peeling the film from the belt surface was small, and there were no problems such as wrinkling during printing. On the other hand, in Comparative Example 1, since the film was formed using water having a large silicon content, the tension necessary for peeling the film from the belt surface was high, and the peelability was lowered. Problems such as wrinkles were generated, and satisfactory printing could not be performed. Therefore, the comparative product obtained after long-term continuous operation could not be put to practical use as a base film for transfer printing.

  The base film for hydraulic transfer printing obtained by the production method of the present invention is used for hydraulic transfer printing for exteriors of mobile phones, various electrical appliances, building materials, household and household items, as well as automobile interior and exterior products. Can be widely applied.

It is explanatory drawing which shows typically the measurement aspect of the deflection rate of the base film surface for hydraulic transfer printing obtained by this invention.

Explanation of symbols

  1 Base film

Claims (1)

  A liquid pressure characterized by using water having a silicon content of 5 ppm or less in producing a base film for hydraulic transfer printing by forming an aqueous dispersion of a film-forming raw material mainly composed of a polyvinyl alcohol resin. A method for producing a base film for transfer printing.

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