JP2007313753A - Method for manufacturing thermal transfer receiving sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a thermal transfer receiving sheet in which such defects on printed image as density variation and white drop-out caused by foreign substances, fibers or the like are improved and which has low cost, high sensitivity and high image quality, in the thermal transfer receiving sheet which is suitable for a dye thermal transfer printer, and is provided with an intermediate layer comprising hollow particles. <P>SOLUTION: In the method for manufacturing the thermal transfer receiving sheet wherein the intermediate layer comprising the hollow particles and an image receiving layer are successively formed on at least one face of a sheet-like supporting body comprising a cellulose pulp as a main component, this method for manufacturing the thermal transfer receiving sheet is provided with a process wherein before an intermediate layer coating process and/or an image receiving layer coating process, the surface of the sheet-like supporting body before forming the intermediate layer and/or before forming the image receiving layer is brought into contact with and passed through the surface of a roll on which the pressure-sensitive adhesive face is stuck outward by using a pressure-sensitive adhesive sheet with a probe tack of 2.45-7.84 N based on JIS Z 0237. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a thermal transfer receiving sheet in which an image is formed by thermally transferring a dye on a thermal transfer sheet (hereinafter also simply referred to as an ink ribbon) with a thermal head by superimposing it on a thermal transfer sheet. More specifically, the present invention is particularly suitable for a dye thermal transfer printer, and has a thermal transfer receiving sheet (hereinafter, also simply referred to as a receiving sheet) having an intermediate layer containing hollow particles between a sheet-like support and an image receiving layer. It is related with the manufacturing method.

  In recent years, thermal printers have attracted attention, and dye thermal transfer printers that can print clear full-color images have attracted attention. In a dye thermal transfer printer, a dye layer containing a dye of an ink ribbon and an image receiving layer (hereinafter also simply referred to as a receiving layer) containing a dye-stainable resin of a receiving sheet are superposed and supplied from a thermal head or the like. An image is formed by transferring the dye at a required portion of the dye layer by a predetermined concentration onto the receiving layer by heat. The ink ribbon sequentially has dye layer regions of three colors of yellow, magenta and cyan, or four colors obtained by adding black to this. A full-color image is obtained by repeatedly transferring each color dye on the ink ribbon to the receiving sheet in order. In such a dye thermal transfer type printer, the receiving sheet is generally supplied in a sheet state.

  The development of digital image processing technology using computers has dramatically improved the quality of recorded images and the market for dye thermal transfer systems. In addition, with the improvement of the thermal head temperature control technology, there is an increasing demand for high speed and high sensitivity of the printing system. Therefore, how to efficiently use the amount of heat generated by a heating device such as a thermal head for image formation is an important technical issue. In addition, there is a demand for printer price reduction and structure simplification, and lowering of the printing pressure by a thermal head and extending the life of the head are also technical issues. Currently, printers that can print one A6 size within 30 seconds are also on sale, and it is expected that there will be further demands for higher printing speeds in the future.

In general, in order to efficiently form an image with high image quality and high density, a receiving sheet provided with a receiving layer mainly composed of a dye-dyeable resin on a support is used. When a normal film is used, it has excellent smoothness, but the heat from the thermal head escapes to the base material, resulting in insufficient recording sensitivity, and the film does not have sufficient cushioning properties. Inadequate adhesion results in density unevenness.
In order to solve such a problem, a support body (for example, refer to Patent Document 1) in which a foam film is bonded to a core material layer such as paper as a support body, and a thermoplastic resin such as a polyolefin resin as a main component. A support or the like in which a biaxially stretched film (synthetic paper) including a void (void) structure is bonded to a core material layer such as paper has been proposed (for example, see Patent Document 2). Receptor sheets using these supports are excellent in heat insulation and smoothness, but have disadvantages such as no paper-like texture and high cost.

  Also, when paper is used as a support for the receiving sheet, the recording sensitivity is insufficient as in the case of the film, and the cushioning property is slightly better than that of the film, but uneven adhesion between the ink ribbon and the receiving layer due to uneven density of paper fibers. Due to this, there is a tendency that unevenness of the printed image occurs. Therefore, a receiving sheet is disclosed in which an intermediate layer containing hollow particles is provided between a paper support and a receiving layer in order to improve transfer density and the like (see, for example, Patent Documents 3 and 4). The sensitivity of this receiving sheet is improved by the effect of improving the heat insulating property and cushioning property of the hollow particle-containing layer, but there is a tendency that the receiving sheet surface is uneven due to the influence of the hollow particles.

  Regarding the improvement of the unevenness of the surface of the receiving sheet, a receiving sheet having a specific surface roughness, glossiness, etc. has been proposed by defining the average particle diameter and hollow ratio of the hollow particles used in the intermediate layer (for example, patents) (Ref. 5, 6). Also, a receiving sheet has been proposed in which a smoothing process is performed on a receiving sheet formed by forming a resin layer including a bubble layer and a receiving layer on a base material, so that the bubble layer and / or the receiving layer is smoothed. (For example, refer to Patent Document 7). However, dust, foreign matter, etc. are present on the front or back surface of the support of the receiving sheet, resulting in defects such as an intermediate layer, an uncoated portion of the receiving layer, or a dent in the coated layer, and an image is recorded. At the same time, there is a problem that the image becomes defective in printing and the commercial value is remarkably lowered.

  Further, for the purpose of removing dust, foreign matters, etc., for example, a method using an adhesive rubber roll (see, for example, Patent Documents 8, 9, and 10) and a method using a cleaning sheet (see, for example, Patent Document 11). .) Is disclosed. However, when a sticky rubber roll as described above is used, foreign matters such as normal dust and dust can be removed, but foreign matter generated particularly when paper is used as a support, that is, the paper making process of the support. The fibers removed from the felt of the press part in the core cannot be removed, and remain on the front and back surfaces of the paper to become nuclei, resulting in an uncoated part or a dent in the coated layer in the subsequent coating process. Cause print defects. It is considered that fibers and the like are relatively firmly attached to the paper surface due to the action of internal chemicals such as a sizing agent contained in the paper raw material. It is conceivable to cover the defective part with a coating film in the coating process, but there are some that are attached in a fuzzy state, and it is actually difficult to completely cover them.

JP 61-197282 A (first page) JP-A-62-198497 (first page) JP-A-63-87286 (page 1-2) Japanese Patent Laid-Open No. 1-27996 (page 1-3) JP-A-9-99651 (page 2-5) JP 2001-39043 A (page 2-3) JP-A-6-210968 (page 2-4) JP 2003-327349 A (second page) JP 2002-28596 A (2nd page) JP 11-60849 A (2nd page) Japanese Unexamined Patent Publication No. 2000-312862 (2nd page)

  The present invention has been made in view of the circumstances as described above, and solves the above-described problems in the conventional method for producing a receiving sheet, particularly in a receiving sheet provided with an intermediate layer containing hollow particles, An object of the present invention is to provide a low-cost, high-sensitivity, high-quality receiving sheet manufacturing method that improves image defects caused by foreign matter.

The present invention includes the following contents.
(1) In the method for producing a thermal transfer receiving sheet in which an intermediate layer containing hollow particles and an image receiving layer are sequentially formed on at least one surface of a sheet-like support mainly composed of cellulose pulp, an intermediate layer coating step and / Or roll surface pasted with an adhesive sheet having a probe tack of 2.45 to 7.84N based on JIS Z 0237 so that the adhesive surface faces outward before the image receiving layer coating step The method for producing a thermal transfer receiving sheet, further comprising a step of bringing the surface of the sheet-like support before the intermediate layer formation and / or the image receiving formation into contact with each other.
(2) The method for producing a thermal transfer receiving sheet according to (1), wherein the pressure-sensitive adhesive sheet has an adhesive strength based on JIS Z 0237 of 370 to 1200 N / m.

  The receiving sheet manufactured using the manufacturing method of the present invention is suitable for a dye thermal transfer printer, has a texture that the support is paper, has an intermediate layer containing hollow particles, and has uneven density and white spots. Is a receptive sheet with extremely high quality, which can be recorded at low cost, high sensitivity and high image quality, and has no printing defects due to foreign matter or the like.

Next, the present invention will be described in more detail with reference to preferred embodiments.
In the present invention, as a result of intensive studies to eliminate printing defects due to foreign matters and fibers, a pressure sensitive adhesive sheet having a probe tack based on JIS Z 0237 in the range of 2.45 to 7.84N is used. By passing the surface of the sheet-like support before forming the intermediate layer and / or before forming the image receiving layer in contact with the surface of a roll (also referred to as an adhesive roll) attached so as to face outward, a sheet-like shape is obtained. It has been found that almost all foreign materials and fibers can be removed without damaging the support, and a high-sensitivity and high-quality image free from printing defects can be obtained. The probe tack is more preferably in the range of 2.9 to 5.9N. When the probe tack of the pressure-sensitive adhesive sheet is less than 2.45N, the pressure-sensitive adhesive force is insufficient and the felt fibers and the like cannot be completely removed. On the other hand, if the probe tack exceeds 7.84N, the felt fibers can be sufficiently removed, but the adhesive sheet may be excessively adhered to the paper, causing the paper support to delaminate or break, It cannot be manufactured stably.
The probe tack was measured with n = 5 under the conditions of a 5 mm diameter SUS probe, a contact speed of 5 cm / sec, a contact time of 0.1 sec, and a contact load of 0.98 N / cm ² , and an average value was adopted.

  In the present invention, the surface of the sheet-like support using the adhesive roll is cleaned before the intermediate layer coating step and / or the receiving layer coating step. For example, before the intermediate layer coating step, It may be a sheet-like support production process (papermaking process), and is preferably performed immediately after the papermaking process or immediately before the intermediate layer coating process. Moreover, before the receiving layer coating step includes after the intermediate layer coating, and may be after the formation of a barrier layer or the like, if necessary, and is preferably performed immediately before the receiving layer coating step. Of course, a cleaning treatment may be performed before forming all the layers such as the intermediate layer, the barrier layer, and the receiving layer. As the adhesive roll, the roll itself may be formed of a material having adhesive force, or an adhesive layer may be provided directly on the roll.

The strength of the probe tack is controlled by the type of adhesive, the thickness of the adhesive layer of the adhesive sheet, the coating amount, and the like. Depending on the kind of the pressure-sensitive adhesive, generally coating amount is preferably adjusted within the range of ^{1~30g / m 2, 5~25g / m} 2 is more preferable. The thickness of the adhesive layer is preferably adjusted in the range of 1 to 30 μm, and more preferably 5 to 20 μm. Moreover, it can also adjust by adding an isocyanate type crosslinking agent or an epoxy type crosslinking agent suitably to an adhesive.
The pressure-sensitive adhesive used in the present invention is not particularly limited as long as the probe tack is 2.45 to 7.84N, and various pressure-sensitive adhesives such as acrylic pressure-sensitive adhesive, natural rubber-based pressure-sensitive adhesive, and synthetic rubber-based pressure-sensitive adhesive can be used. it can. In addition, various forms of pressure-sensitive adhesives such as a solvent-type pressure-sensitive adhesive, an emulsion-type pressure-sensitive adhesive, and a hot-melt-type pressure-sensitive adhesive can be used. Furthermore, various auxiliary agents such as a tackifier, a plasticizer, an antifoaming agent, and a preservative can be appropriately added to the pressure-sensitive adhesive.

  In the present invention, foreign substances, fibers, and the like can be more completely removed by bringing the pressure-sensitive adhesive sheet surface into contact with not only one side but also both sides of the sheet-like support, or by repeating several times instead of once. Furthermore, it is possible to remove more efficiently by installing several pressure-sensitive adhesive sheets affixed to a paper roll so that they can be brought into contact with both sides of the sheet-like support several times. FIG. 1 shows an example in which the adhesive surface of the adhesive sheet is in contact with both surfaces of the sheet-like support, and the adhesive surface is on the outer side of each surface of the paper rolls C, D, E, and F. An adhesive sheet is affixed to the sheet, and the sheet-like support is unwound from the winding A and comes into contact with both surfaces twice.

  Specifically, in a coating machine when an intermediate layer is provided on a paper-made sheet-like support, a pressure-sensitive adhesive sheet is attached to a paper roll immediately before the coating process or a paper roll immediately after the drying process, thereby supporting the sheet form. By allowing the body to pass through, foreign matter and the like attached to the sheet-like support can be removed. Similarly, in a coating machine when a receiving layer is provided on an intermediate layer, a sheet provided with an intermediate layer by sticking an adhesive sheet to a paper roll immediately before the coating process or a paper roll immediately after the drying process By passing the sheet-like support, foreign matter or the like attached to the sheet-like support can be removed. In addition, foreign matters and the like can be completely removed by installing in the same manner also in the smoothing process and the process of cutting to the required dimensions.

  Furthermore, by setting the adhesive strength based on JIS Z 0237 of the pressure-sensitive adhesive sheet used in the present invention to a range of 370 to 1200 N / m, the removed foreign matter can be firmly attached to the pressure-sensitive adhesive sheet, more preferably. Is in the range of 450 to 850 N / m. If the adhesive strength is less than 370 N / m, the fiber may be separated from the adhesive sheet and taken again by the sheet-like support. If it exceeds 1200 N / m, the probe tack generally increases, and in the case of a paper support, it may adhere more strongly than necessary, causing the paper to delaminate or break.

  As the support for the pressure-sensitive adhesive sheet used in the present invention, papers mainly composed of cellulose pulp, synthetic resin films, and the like are used. For example, paper such as high-quality paper (acidic paper, neutral paper), medium-quality paper, coated paper, art paper, glassine paper, resin-laminated paper, or polyolefin such as polyethylene or polypropylene, polyester such as polyethylene terephthalate, polyamide Films or sheets based on synthetic resins such as polyvinyl chloride, polystyrene, polycarbonate, polyvinyl alcohol, polyvinyl chloride, or porous single layer stretched films or porous materials based on thermoplastic resins such as polyolefin or polyester Multi-layer stretched film (for example, synthetic paper) and the like, and a laminate obtained by laminating and sticking these films to each other and other films and / or papers, and the like are appropriately used.

The layer structure of the receiving sheet of the present invention has at least a sheet-like support, an intermediate layer, and a receiving layer, and these layers will be described in detail below.
(Sheet support)
As the sheet-like support of the present invention, a paper base material mainly composed of cellulose pulp is used. For example, high-quality paper, coated paper, art paper, cast coated paper, at least one thermoplastic resin layer such as polyolefin resin is used. Laminating paper, synthetic resin impregnated paper, emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper, foamed paper containing thermally expandable particles, papers mainly composed of cellulose pulp such as paperboard preferable.

  The sheet-like support of the present invention may have a structure in which a first base material layer on which a receiving layer is formed, an adhesive layer, a release agent layer, and a second base material layer are sequentially laminated. Of course, a sheet-like support having a structure of a sticker or a seal type can also be used.

  The sheet-like support used in the present invention preferably has a thickness of 100 to 300 μm. Incidentally, if the thickness is less than 100 μm, the mechanical strength is insufficient, the rigidity of the receiving sheet obtained therefrom is small, the repulsive force against deformation is insufficient, and the curling of the receiving sheet that occurs during printing is reduced. There are cases where it cannot be sufficiently prevented. On the other hand, if the thickness exceeds 300 μm, the thickness of the obtained receiving sheet becomes excessive, so that the capacity of the receiving sheet in the printer is reduced, or if the predetermined number of receiving sheets is stored, the volume of the printer In some cases, this causes an increase and makes it difficult to make the printer compact.

(Middle layer)
In the present invention, an intermediate layer is formed on at least one surface of a sheet-like support mainly composed of cellulose pulp. Since the intermediate layer has a porous structure mainly composed of an adhesive resin and hollow particles and has a high cushioning property, a highly sensitive receiving sheet can be obtained even when paper is used as the sheet-like support.

  By containing hollow particles in the intermediate layer, the receiving sheet is given a suitable degree of deformation freedom, and the followability and adhesion of the receiving sheet to the printer head shape and ink ribbon shape are improved. The thermal efficiency of the printer head can be improved, the print density can be increased, and the image quality can be improved. Further, in the high energy application operation of the high-speed printer, it is possible to prevent printing defects due to ribbon wrinkles generated on the ink ribbon at the same time.

  By including hollow particles in the intermediate layer, the heat insulating property of the receiving sheet is improved, thereby improving the thermal efficiency of the thermal head with respect to the receiving layer, thereby increasing the print density and improving the image quality. Even if the receiving sheet is subjected to high pressure by the thermal head and the conveying roll of the printer, it is possible to absorb this stress inside the receiving sheet, so that spike marks and dents on the printing screen are formed by the conveying roll of the receiving sheet. Resistance to is improved.

  The hollow particles used in the intermediate layer of the present invention are composed of a shell formed of a polymer material and one or more hollow portions surrounded by the shell, and the average particle diameter of the hollow particles is It is 0.5-10 micrometers, Preferably it is 0.8-8 micrometers. When the average particle diameter of the foamed hollow particles is less than 0.5 μm, the volume hollowness of the resulting hollow particles is low, so the heat insulation and cushioning properties are generally low, so the sensitivity and image quality improvement effects are sufficiently obtained. It may not be possible. On the other hand, when the average particle diameter exceeds 10 μm, the smoothness of the obtained intermediate layer surface is lowered, the unevenness of the surface of the receiving sheet is increased, the uniformity of the thermal transfer image is insufficient, and the image quality may be inferior.

Moreover, the maximum particle diameter of the foamed hollow particles used in the present invention is preferably 25 μm or less, more preferably 20 μm or less. When the maximum particle diameter of the foamed hollow particles exceeds 25 μm, unevenness in density and white spots of the print due to coarse particles may occur in the thermal transfer image, resulting in poor image quality. Although there is no special restriction | limiting about the manufacturing method of a hollow particle, It can select from what was manufactured as follows (b) and (b).
(A) Expanded hollow particles produced by thermally expanding a thermoplastic polymer material containing a thermally expandable substance.
(B) The pore-forming material is volatilized and escaped from the microcapsules produced by the microcapsule polymerization method using the polymer-forming material as the shell-forming material and the volatile liquid as the pore-forming material. Microcapsule-like hollow particles obtained by the above process.

  Further, as the hollow particles, particles made of a thermoplastic substance containing a thermally expandable substance are used in an unfoamed state, and the foamed hollow particles are foamed by heat in the manufacturing process of the receiving sheet, for example, heat in the drying process. Forming is also conceivable. However, as described above, if a thermoplastic material containing a thermally expandable material is foamed by heating during the manufacturing process of the receiving sheet, it is difficult to foam to a uniform particle size, and the particle size after thermal expansion is strictly limited. Since it cannot be managed, the surface of the intermediate layer becomes a surface with large irregularities, and the smoothness may be inferior. Since the receiving sheet having the intermediate layer as described above also has large irregularities on the surface of the receiving layer, the uniformity of the heat-transferred image may be lowered and the image quality may be inferior. Therefore, in the present invention, hollow foamed particles produced by thermally expanding particles made of a thermoplastic material containing a thermally expandable material in advance are preferably used.

  The foamed hollow particles produced by thermally expanding a thermoplastic material-containing thermoplastic material are, for example, a volatile material such as n-butane, i-butane, pentane, and / or neopentane as a thermally expandable core material. Encapsulating low-boiling hydrocarbons in thermoplastic materials, and encapsulating homopolymers or copolymers of vinylidene chloride, vinyl chloride, acrylonitrile, methacrylonitrile, styrene, (meth) acrylic acid esters, etc. as thermoplastic materials The particles obtained as a shell (wall) material are subjected to a treatment such as heating in advance, so that they are thermally expanded to a predetermined particle diameter to obtain hollow particles in an already foamed state.

  In addition, the expanded hollow particles produced by thermally expanding the thermoplastic material-containing thermoplastic material as described above generally have a small specific gravity, and therefore, for the purpose of further improving the handling workability and dispersibility thereof, calcium carbonate Further, foamed composite hollow particles in which an inorganic powder such as talc or titanium dioxide is adhered to the surface of the foamed hollow particle by thermal fusion and the surface is coated with the inorganic powder can also be used in the present invention.

In order to prevent the hollow particles used in the present invention from containing coarse particles having a maximum particle size exceeding 25 μm, in the production of hollow particles generally showing a normal distribution state, the set value of the average particle size is set to It is possible to respond by adjusting. Further, by providing a particle classification step, it is possible to reliably obtain hollow particles that do not contain coarse particles.
The particle diameter of the hollow particles is a value measured using a particle size distribution measuring device (trade name: SALD2000, manufactured by Shimadzu Corporation).

  The volume hollowness of the hollow particles used in the present invention is preferably 30 to 97%, more preferably 45 to 95%. When the volumetric hollow ratio of the hollow particles is less than 30%, the sensitivity improving effect of the entire receiving sheet is not sufficiently exhibited. On the other hand, when the volumetric hollow ratio exceeds 97%, the coating strength of the intermediate layer is lowered, the intermediate layer is easily damaged, and the appearance may be deteriorated.

  The volumetric hollow ratio of the hollow particles is the ratio of the volume of the hollow part to the volume of the particles. Specifically, the specific gravity of the hollow particle dispersion composed of the hollow particles and the poor solvent, and the hollow particles in the dispersion It can be determined from the mass fraction and the true specific gravity of the polymer resin forming the shell (wall) of the hollow particles and the specific gravity of the poor solvent. Moreover, about the average particle diameter and volume hollow rate of a hollow particle, the cross section can be calculated | required from cross-sectional photograph observation with a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

  The blending amount of the hollow particles in the intermediate layer is preferably in the range of 30 to 75% and more preferably in the range of 35 to 70% in terms of the ratio of the hollow particle mass to the total solid mass of the entire intermediate layer. When the mass ratio of the hollow particles to the total solid mass of the entire intermediate layer is less than 30%, the heat insulating property and cushioning property of the intermediate layer are insufficient, and the sensitivity and image quality improvement effect may not be sufficiently obtained. Moreover, when the mass ratio of the hollow particles exceeds 75%, the coating properties of the resulting intermediate layer coating solution are lowered, and the coating film strength may be insufficient, and the desired effect cannot be obtained. There is.

  In order for the intermediate layer to exhibit desired performance such as heat insulation and cushioning, the thickness of the intermediate layer is preferably 20 to 90 μm, more preferably 25 to 85 μm. If the film thickness of the intermediate layer is less than 20 μm, the heat insulation and cushioning properties are insufficient, and the sensitivity and image quality improvement effect may be insufficient. On the other hand, if the film thickness exceeds 90 μm, the effects of heat insulation and cushioning are saturated, and not only higher performance can be obtained, but also it may be economically disadvantageous.

  The intermediate layer of the present invention contains hollow particles and an adhesive resin. In consideration of the solvent resistance of the hollow particles, the intermediate layer coating solution of the present invention is preferably an aqueous coating solution. Accordingly, the adhesive resin can be either water-based or organic solvent-based, but is more preferably an aqueous resin. The adhesive resin used is not particularly limited. For example, hydrophilic polymer resins such as polyvinyl alcohol resins, cellulose resins and derivatives thereof, casein, and starch derivatives are film forming properties, heat resistance, and flexibility. Are preferably used. In addition, emulsions of various resins such as (meth) acrylic acid ester resins, styrene-butadiene copolymer resins, urethane resins, polyester resins, ethylene-vinyl acetate copolymer resins are used as low-viscosity and high-solids aqueous resins. The The adhesive resin used for the intermediate layer is preferably a combination of the hydrophilic polymer resin and an emulsion of various resins from the viewpoints of coating strength, adhesiveness, and coatability of the intermediate layer.

  In the intermediate layer, various additives, for example, an antistatic agent, an inorganic pigment, an organic pigment, a resin crosslinking agent, an antifoaming agent, a dispersing agent, a colored dye, a release agent, a lubricant, etc. Two or more kinds may be appropriately selected and used.

(Barrier layer)
In the present invention, if necessary, a barrier layer may be provided on the intermediate layer, and the receptor layer is provided on this barrier layer. In this barrier layer, the solvent of the coating solution for the receiving layer is generally an organic solvent such as toluene or methyl ethyl ketone, and is effective as a barrier for preventing the hollow particles in the intermediate layer from swelling and dissolving due to the penetration of the organic solvent. In addition, since the surface of the intermediate layer has irregularities due to the hollow particles of the intermediate layer, the receiving layer provided thereon may also have irregularities on the surface, and the resulting image has many white spots and uneven shading due to the irregularities. In some cases, problems arise in image uniformity and resolution. In order to improve this problem, it is effective to improve the image quality to provide a barrier layer containing an adhesive resin having flexibility and elasticity.

  As the adhesive resin used for the barrier layer, a resin having excellent film forming ability, preventing penetration of an organic solvent, and having elasticity and flexibility is used. Specifically, it is formed from water-soluble polymers such as polyvinyl alcohol, starch, modified starch, casein, urethane resin, vinyl acetate resin, polyester resin, acrylic resin and copolymer thereof, or a resin using them in combination.

  In addition, in the intermediate layer and the barrier layer, in order to provide concealability and whiteness, and to improve the texture of the receiving sheet, as inorganic pigments, calcium carbonate, titanium dioxide, zinc oxide, aluminum hydroxide, barium sulfate, barium dioxide, White inorganic pigments such as silicon, aluminum oxide, talc, kaolin, diatomaceous earth, and satin white, fluorescent dyes, and the like may be included.

The solid content coating amount of the barrier layer is preferably in the range of 0.5 to 10 g / m ² , more preferably in the range of 1 to 8 g / m ² . Incidentally, when the barrier layer solid content coating amount is less than 0.5 g / m ² , the barrier layer may not be able to completely cover the surface of the intermediate layer, and the organic solvent permeation preventing effect may be insufficient. On the other hand, when the coating amount of the barrier layer solid content exceeds 10 g / m ² , the coating effect is saturated and not only uneconomical, but also the heat insulation effect of the intermediate layer due to the excessive thickness of the barrier layer. In addition, the cushioning property may not be sufficiently exhibited, and the image density may be lowered.

(Receptive layer)
In the receiving sheet of the present invention, the receiving layer is provided directly on the intermediate layer or via a barrier layer. The receiving layer itself may be a known dye thermal transfer receiving layer. As the resin for forming the receiving layer, a resin having a high affinity for the dye transferred from the ink ribbon and having a good dyeing property is used. Examples of such dye dyeable resins include polyester resins, polycarbonate resins, polyvinyl chloride resins, vinyl chloride-vinyl acetate copolymer resins, polyvinyl acetal resins, polyvinyl butyral resins, polystyrene resins, polyacrylate resins, and cellulose. Examples thereof include cellulose derivative resins such as acetate butyrate, thermoplastic resins such as polyamide resin, and active energy ray curable resins. These resins preferably have a functional group reactive with the crosslinking agent used (for example, a functional group such as a hydroxyl group, an amino group, a carboxyl group, or an epoxy group).

  In addition, in order to prevent the receiving layer and the ink ribbon from fusing by heating with a thermal head during printing, one or more of a crosslinking agent, a release agent, a slipping agent, etc. are added to the receiving layer. It is preferable that it is mix | blended as an agent. Moreover, you may add 1 or more types, such as fluorescent dye, a plasticizer, antioxidant, a pigment, a filler, an ultraviolet absorber, antistatic agent, etc. in said receiving layer as needed. These additives may be mixed with the forming component of the receiving layer before coating, or may be coated on and / or under the receiving layer as a coating layer different from the receiving layer.

The solid coating amount of the receiving layer is preferably 1 to 12 g / m ² , more preferably 3 to 10 g / m ² . Incidentally, when the solid content coating amount of the receiving layer is less than 1 g / m ² , the receiving layer may not completely cover the barrier layer surface, which may cause deterioration in image quality or heating of the thermal head. There may be a fusing problem that the ink ribbon and the ink ribbon are bonded. On the other hand, when the solid content coating amount exceeds 12 g / m ² , not only is the effect saturated and uneconomical, but also the coating strength of the receiving layer is insufficient and the coating thickness becomes excessive. As a result, the heat insulation effect of the intermediate layer may not be sufficiently exhibited, leading to a decrease in image density.

(Back layer)
In the receiving sheet of the present invention, a back layer may be provided on the back side of the sheet-like support (the side opposite to the side on which the receiving layer is provided). The back layer is mainly composed of a resin effective as an adhesive, and may contain a crosslinking agent, a conductive agent, an anti-fusing agent, an inorganic and / or organic pigment, and the like.

  For the back layer of the present invention, a back layer forming resin effective as an adhesive is used. This resin is effective in improving the adhesive strength between the back surface layer and the sheet-like support, print transportability of the receiving sheet, preventing scratches on the receiving layer surface, and preventing the dye from transferring to the back layer contacting the receiving layer surface. As such a resin, an acrylic resin, an epoxy resin, a polyester resin, a phenol resin, an alkyd resin, a urethane resin, a melamine resin, a polyvinyl acetal resin, and a reaction cured product of these resins can be used.

  In the back layer of the present invention, a cross-linking agent such as a polyisocyanate compound or an epoxy compound may be appropriately blended in the back layer coating solution in order to improve the adhesion between the sheet-like support and the back layer. As a compounding ratio, generally about 1-30 mass% is preferable with respect to the back layer total solid content.

  A conductive agent such as a conductive polymer or a conductive inorganic pigment may be added to the back layer of the present invention in order to improve print transportability and prevent static electricity. Examples of the conductive polymer include cationic, anionic and nonionic conductive polymer compounds. Examples of the cationic polymer compound include polyethyleneimine, acrylic polymers containing cationic monomers, and cation-modified acrylamide polymers. And cationic starch. Examples of the anionic polymer compound include polyacrylate, polystyrene sulfonate, and styrene-maleic acid copolymer. In general, the blending ratio of the conductive agent is preferably about 5 to 50% by mass with respect to the total solid content of the back surface layer.

  Examples of conductive inorganic pigments include compound semiconductor pigments such as oxides and / or sulfides, and inorganic pigments coated with the compound semiconductor pigments. Examples of the compound semiconductor include copper (I) oxide, zinc oxide, zinc sulfide, and silicon carbide. Examples of inorganic pigments coated with a compound semiconductor include titanium oxide and potassium titanate coated with semiconductor tin oxide, and acicular and spherical conductive inorganic pigments are commercially available.

  If necessary, an organic or inorganic filler can be blended in the back layer of the present invention as a friction coefficient adjusting agent. As the organic filler, nylon filler, cellulose filler, urea resin filler, styrene resin filler, acrylic resin filler, and the like can be used. As the inorganic filler, silica, barium sulfate, kaolin, clay, talc, heavy calcium carbonate, light calcium carbonate, titanium oxide, zinc oxide and the like can be used. For example, in the case of a nylon filler, the average particle size is preferably about 1 to 15 μm, and the blending amount is preferably about 2 to 30% by mass based on the total solid content of the back surface layer, although it depends on the particle size.

  The back layer may contain an anti-fusing agent such as a lubricant and a release agent as necessary. Examples of the anti-fusing agent include non-modified and modified silicone oils, silicone block copolymers, silicone compounds such as silicone rubber, phosphate ester compounds, fatty acid ester compounds, fluorine compounds, and the like. Conventionally known antifoaming agents, dispersants, colored pigments, fluorescent dyes, fluorescent pigments, ultraviolet absorbers and the like may be appropriately selected and used.

The solid content coating amount of the back layer is preferably in the range of 0.3 to 10 g / m ² . More preferably, it is 1-8 g / m < ² >. When the back layer solid content coating amount is less than 0.3 g / m ² , the scratch resistance when the receiving sheet is rubbed is not sufficiently exhibited, coating defects occur, and the surface electrical resistance value is May go up. On the other hand, if the solid content coating amount exceeds 10 g / m ² , the effect is saturated and uneconomical.

  In the present invention, each coating layer such as an intermediate layer, a receiving layer, a back layer, and a barrier layer is formed according to a conventional method, and a coating solution containing necessary components is prepared for each bar coater, gravure coater, comma coater. Using a known coater such as a blade coater, an air knife coater, a gate roll coater, a die coater, a curtain coater, a lip coater, and a slide bead coater, it is coated on a predetermined surface of a sheet-like support and dried. Thereafter, it can be formed by heat curing if necessary.

For example, in the case of the intermediate layer, an intermediate layer coating solution containing at least the required components of the hollow particles and the adhesive resin is applied to the sheet-like support according to a conventional method using a known coater as described above. It can be formed by coating and drying.
When applying the intermediate layer, a molding surface may be used, or a metal plate, a metal drum, a plastic film, or the like having good dimensional stability and a highly smooth surface may be used. Moreover, in order to make it easy to peel the intermediate layer from the molding surface, if necessary, a higher fatty acid type release agent such as calcium stearate and zinc stearate, a polyethylene type release agent such as polyethylene emulsion, and wax on the molding surface. In addition, a release agent such as silicone may be applied.

In the manufacturing method of the receiving sheet of this invention, it is preferable that a smoothing process process is included.
The smoothing treatment is preferably performed by a calendering treatment in which unevenness on the surface of the receiving sheet is reduced by passing the receiving sheet between a pair of rolls consisting of a heating roll and a press roll with a certain clearance. At this time, heat and pressure can be applied between the pair of rolls.
The smoothing treatment may be any of the sheet-like support surface, intermediate layer surface, barrier layer surface, receptor layer surface, and the like. In particular, the surface of the intermediate layer and the surface of the receiving layer are preferably subjected to a smoothing treatment. Of course, the smoothing treatment can be performed on two or more surfaces.

  There are no particular limitations on the calendar apparatus used for the smoothing process and various processing conditions such as the nip pressure, the number of nips, and the heating roll surface temperature. A calendar device generally used in the paper industry, such as a calendar, gloss calendar, and machine calendar, can be used as appropriate.

  A preferable nip pressure condition for the smoothing treatment is, for example, 0.2 to 150 MPa, and more preferably 0.3 to 100 MPa. Further, the residence time of the receiving sheet at the nip is greatly affected by the hardness of the press roll, the linear pressure of the calendar, and the processing speed, but is preferably in the range of 5 to 500 milliseconds. As temperature conditions of a heating roll, the temperature range below the melting | fusing point of the adhesive agent of the coating layer which performs a smoothing process from room temperature is preferable, for example, 20-150 degreeC, More preferably, it is 30-120 degreeC. Moreover, as for the surface roughness of a heating roll, it is preferable that Ra value based on JISB0601 is 0.01-5 micrometers, More preferably, it is the range of 0.02-1 micrometers.

  The method for producing a receiving sheet of the present invention may include a thickness restoring process step in which the receiving sheet is brought into contact with a heating roll and heated immediately after the smoothing process step, in a state where pressure is released. When the receiving sheet is smoothed by passing through a nip in a pressurized state formed between a pair of rolls consisting of a heating roll and a press roll, the smoothness is improved, but the inside of the receiving sheet, particularly the intermediate layer Is compressed to reduce the thickness. When this receiving sheet is brought into contact with a heating roll in a pressure-released state immediately after passing through the nip portion, the intermediate layer expands and the thickness increases, so that the density of the entire intermediate layer decreases, and the printing density of the receiving sheet decreases. Can be increased.

  The temperature of the heating roll in the thickness restoration treatment step may be the same as the heating roll condition in the smoothing treatment, preferably 20 to 150 ° C, more preferably 30 to 120 ° C. The contact time between the receiving sheet and the heating roll is preferably 0.5 seconds or longer, more preferably 1 second or longer.

  The present invention will be described in detail by the following examples, but the scope of the present invention is not limited thereto. In Examples, unless otherwise specified, “%” and “parts” represent “mass%” and “parts by mass” of solid content, except for those relating to solvents.

Example 1
[Preparation of adhesive sheet]
On the surface of a polyethylene terephthalate film having a thickness of 100 μm, the pressure-sensitive adhesive layer coating solution-1 having the following composition was coated and dried so that the solid content coating amount was 10 g / m ² to prepare a pressure-sensitive adhesive sheet. The probe tack was 4.1 N, and the adhesive strength was 380 N / m.
Adhesive layer coating solution-1
Acrylic adhesive (trade name: AT191, made by Seiden Chemical) 100 parts isocyanate curing agent (trade name: AL, made by Seiden Chemical) 1 part Ethyl acetate 400 parts

[Production of receiving sheet]
(Formation of intermediate layer)
In the intermediate layer forming step, using a high-quality paper of 160 g / m ² as a sheet-like support, sticking it to a paper roll with the adhesive layer surface of the adhesive sheet facing outward, contacting the surface of the adhesive sheet, and passing the paper, The intermediate layer coating solution-1 having the following composition was coated and dried so that the solid content coating amount was 12 g / m ² to form an intermediate layer on the fine paper.
Intermediate layer coating solution-1
Copolymer-based foamed hollow particles mainly composed of acrylonitrile and acrylic ester (volume hollow ratio 79%, average particle diameter 3.6 μm, maximum particle diameter 19 μm) 35 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray Co., Ltd.) 15 parts Styrene-butadiene latex (trade name: PT1004, manufactured by Zeon Corporation) 50 parts Water 200 parts

(Formation of barrier layer)
In the support coated with the intermediate layer, the barrier layer coating liquid-1 having the following composition is coated on the intermediate layer so that the solid content coating amount is 3 g / m ² and dried to form a barrier layer. did.
Coating liquid for barrier layer-1
Polyvinyl alcohol (trade name: PVA420, manufactured by Kuraray) 100 parts Water 1000 parts

(Formation of receiving layer)
In the support coated with the barrier layer, the receiving layer coating solution-1 having the following composition is coated on the barrier layer so that the solid coating amount is 4 g / m ² and dried to form the receiving layer. did.
Receiving layer coating solution-1
Polyester resin (trade name: Byron 200, manufactured by Toyobo) 100 parts silicone oil (trade name: KF393, manufactured by Shin-Etsu Chemical Co., Ltd.) 3 parts polyisocyanate (trade name: Takenate D-140N,
Mitsui Chemicals Polyurethane) 5 parts Toluene / Methyl ethyl ketone = 1/1 (mass ratio) mixture 400 parts

(Formation of receiving sheet)
In the support coated with the receptor layer, the back layer coating liquid-1 having the following composition is applied to the back surface (the surface where the receptor layer is not formed) so that the solid content coating amount is 3 g / m ^2. Then, it was dried to form a back layer, and a receiving sheet was prepared.
Back layer coating solution-1
Polyvinyl acetal resin (trade name: ESREC KX-1, manufactured by Sekisui Chemical Co., Ltd.) 40 parts Polyacrylate resin (trade name: Jurimer AT613, manufactured by Nippon Pure Chemicals) 20 parts nylon resin particles (trade name: MW330, Shinto Paint) 10 parts zinc stearate (trade name: Z-7-30, manufactured by Chukyo Yushi) 10 parts cationic conductive resin (trade name: Chemistat 9800, manufactured by Sanyo Kasei) 20 parts water / isopropyl alcohol = 2/3 ( (Mass ratio) 400 parts of liquid mixture

Example 2
In the production of the pressure-sensitive adhesive sheet of Example 1, a receiving sheet was produced in the same manner as in Example 1 except that the pressure-sensitive adhesive layer coating liquid-2 was used instead of the pressure-sensitive adhesive layer coating liquid-1. . The obtained adhesive sheet had a probe tack of 6.1 N and an adhesive strength of 1150 N / m.
Adhesive layer coating liquid-2
Acrylic adhesive (trade name: OPT-1, manufactured by Toyo Ink) 100 parts isocyanate curing agent (trade name: BXX4867, manufactured by Toyo Ink) 1 part Ethyl acetate 400 parts

Example 3
In the formation of the intermediate layer of Example 1, as shown in FIG. 1, a total of four paper rolls arranged so that the adhesive layer surface of the adhesive sheet is in contact with each other on both sides of the high-quality paper to be passed. A receiving sheet was prepared in the same manner as in Example 1 except that an intermediate layer was formed by sequentially contacting high-quality paper (sheet-like support) with the surface of the pressure-sensitive adhesive roll having the pressure-sensitive adhesive sheet attached thereto. .

Example 4
Immediately before the step of forming each of the intermediate layer, the barrier layer, and the receiving layer of Example 1, the surface of the pressure-sensitive adhesive roll with the pressure-sensitive adhesive layer faced outward and attached to the paper roll, the sheet-like shape of each step A receiving layer sheet was prepared in the same manner as in Example 1 except that the surface of the support was brought into contact with each other and the intermediate layer, the barrier layer, and the receiving layer were sequentially formed.

Comparative Example 1
In the formation of the intermediate layer of Example 1, a receiving sheet was obtained in the same manner as in Example 1 except that a high-quality paper (sheet-like support) was brought into contact with the surface of the paper roll without attaching an adhesive sheet. Was made.

Comparative Example 2
In the formation of the intermediate layer of Example 1, instead of the paper roll with the adhesive sheet attached, a normal adhesive roll (trade name: CLINTACK H, manufactured by Kinyo Co., Ltd.) was used without attaching the adhesive sheet. A receiving sheet was prepared in the same manner as in Example 1.

Comparative Example 3
In the production of the pressure-sensitive adhesive sheet of Example 1, a receiving sheet was produced in the same manner as in Example 1 except that the pressure-sensitive adhesive sheet was produced by coating and drying so that the solid content coating amount was 5 g / m ^2. did. The obtained adhesive sheet had a probe tack of 2.2 N and an adhesive strength of 260 N / m.

Evaluation (frequency of printing defects)
The receiving sheets obtained in each of the above examples and comparative examples were cut into a size of 10.2 cm × 15.2 cm (corresponding to L size) for evaluation, and a commercially available thermal transfer video printer (trade name: DR100) (Manufactured by Sony Corporation), 50 gray images were printed continuously, and the total number of printing defects and the total area of printing defects were measured. The results are shown in Table 1.

  As can be seen from Table 1, the receiving sheets obtained in the examples of the present invention were extremely excellent receiving sheets with extremely few numbers and areas of printing defects.

  The receiving sheet obtained by the method of the present invention is suitable for a dye thermal transfer printer, has a texture that the support is paper, has an intermediate layer containing hollow particles, and has no uneven density or white spots. Furthermore, it is a low-cost, high-sensitivity, high-quality recording, and has an extremely high quality receiving sheet that does not have a printing defect due to foreign matter or the like, and can be sufficiently applied to image formation by a dye thermal transfer printer.

It is the schematic which shows an example of the process of removing the foreign material of the sheet-like support body in this invention.

Claims (2)

  In the method for producing a thermal transfer receiving sheet in which an intermediate layer containing hollow particles and an image receiving layer are sequentially formed on at least one surface of a sheet-like support mainly composed of cellulose pulp, the intermediate layer coating step and / or the image Before the receptive layer coating step, using a pressure-sensitive adhesive sheet having a probe tack of 2.45 to 7.84N based on JIS Z 0237, A method for producing a thermal transfer receiving sheet, comprising the step of bringing the surface of a sheet-like support before layer formation and / or image receiving formation into contact with each other. The method for producing a thermal transfer receiving sheet according to claim 1, wherein the pressure-sensitive adhesive sheet has an adhesive strength based on JIS Z 0237 of 370 to 1200 N / m.

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