JP2004338313A - Ink jet recording sheet and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording sheet which has a high surface smoothness and can obtain an excellent printing image, and to provide its manufacturing method. <P>SOLUTION: A first layer 1 mainly composed of a polyvinyl alcohol base resin and a second layer 2 mainly composed of a polyalkylene oxide base resin are provided. A substrate sheet 10 is laminated to non the first layer side of the second layer and a surface smoothness of the first layer is 1.0-2.0 μm. The second layer 2 is formed on the substrate sheet 10 and the first layer is formed on the substrate 11. The first layer 1 is laminated on the second layer 2 in facial contact. The substrate 11 is peeled off, a smooth synthetic resin film 12 is superimposed on the surface of the first layer 1 to be hot pressed, and the synthetic resin film 12 is peeled off. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４６】
【発明の効果】
以上のように、本発明のインクジェット記録用シートによれば、通常のインクジェットプリンターを用いて、写真画質に近似した印刷品質を、容易に得ることのできる。
また、本発明の製造方法によれば、この写真画質に近似した優れた印刷品質を得ることのできるインクジェット記録用シートを、極めて容易な操作で得ることができる。
【図面の簡単な説明】
【図１】本発明の方法を順を追って模式的に示す。
【符号の説明】
１ 第１層
２ 第２層
１０ 基材シート
１１ 支持体
１２ 合成樹脂フィルム[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink jet recording sheet capable of obtaining an excellent printed image having a high surface smoothness and therefore close to photographic quality, and a method for producing the same.
[0002]
[Technical background]
The ink jet recording method is rapidly spreading because it is excellent in high-speed printing and low noise, can perform multicolor printing, and has low apparatus and running costs.
In particular, recently, printing quality similar to photographic quality has been developed, and in applications where the number of copies is small, the cost is lower than with photographic technology. There is a request for formation.
[0003]
On the other hand, as a recording sheet compatible with an ink jet recording method, a sheet in which a water-soluble resin such as polyvinyl alcohol or polyvinylpyrrolidone is blended in the ink receiving layer, or an inorganic filler such as silica or alumina mixed with the resin, or a polyethylene oxide-based resin And the like using the above thermoplastic resin have been developed and proposed.
[0004]
However, those using the above-mentioned water-soluble resin or those containing an inorganic filler in the resin, due to limitations in the layer structure and layer (film) thickness, etc., have a liquid absorbing performance (that is, ink receiving performance). In some cases, unevenness of ink placement, poor drying of ink, etc. may occur, causing a problem of print quality, and the above-mentioned request cannot be satisfied.
[0005]
Further, those using the above polyethylene oxide-based thermoplastic resin have good ink receptivity, but have a high haze due to the surface roughness, poor light scattering due to light scattering, and the entire image is dark. However, it cannot be said that the above request has been met.
[0006]
Therefore, a technique in which a hydrophilic resin layer such as polyvinyl alcohol or polyurethane is provided on the ink receiving layer by a transfer method using polyethylene terephthalate having a high surface smoothness (hereinafter sometimes referred to as PET) or the like. .
According to this technique, an inkjet recording sheet having a high surface smoothness can be provided, and it is presumed that a print image close to a photograph is formed.
However, in the case of this technology, when the ink receiving layer is thermoformed, a hydrophilic layer such as polyvinyl alcohol or the like separately formed on a PET sheet is formed on the receiving layer simultaneously with the extrusion forming of the ink receiving layer by an extrusion sandwich lamination method. The PET sheet is peeled off after this, and the surface may be roughened at the time of peeling, and cohesive failure of the inorganic filler mixed with the hydrophilic resin may occur. May be worse.
[0007]
In the case where the ink receiving layer is produced by the above-described heat (melt) molding, a thermoplastic resin layer such as polyvinyl alcohol can be molded simultaneously with the production of the ink receiving layer by simple coextrusion.
However, in this technique, surface shrinkage and crystallization occur during cooling after co-extrusion, and accordingly, surface haze deteriorates and surface gloss decreases.
[0008]
[Object of the invention]
The present invention has no problems as described above, and can obtain a high print quality close to the photographic image quality. The purpose is to provide a suitable method.
[0009]
Summary of the Invention
In order to achieve the above object, the ink jet recording sheet of the present invention has a first layer mainly composed of a polyvinyl alcohol-based resin and a second layer mainly composed of a polyalkylene oxide-based resin. A substrate sheet is laminated on the non-first layer side, and the first layer has a surface smoothness of 1.5 to 2.0 μm.
In addition, the surface smoothness in the present invention is based on a ten-point average roughness (Rz) based on JIS B0601-1994.
In the method of manufacturing an ink jet recording sheet according to the present invention, a step of forming a first layer mainly composed of a polyvinyl alcohol-based resin and a step of forming a second layer mainly composed of a polyalkylene oxide-based resin on a base sheet are provided. A step of laminating the first layer and the second layer in surface contact, a step of laminating a smooth synthetic resin film on the surface of the first layer and hot pressing the film, and a step of peeling the synthetic resin film. It is characterized by including.
At this time, the conditions of the hot pressing are as follows: the temperature is 50 to 100 ° C., the pressure is 1.5 to 10 kgf / cm, and the time (speed) is 5 to 15 m / min. It is preferable in order to increase the surface smoothness and surface glossiness.
Further, after hot pressing under these conditions and before peeling off the synthetic resin film, cooling at a rate of 8 to 25 ° C./s can be performed by the following method. It is preferable in increasing the transparency.
[0010]
As the base sheet in the present invention, a base sheet used for a usual sheet of this kind can be used as it is, and specifically, one or more kinds of natural pulp, recycled pulp, synthetic pulp and the like can be used. Examples include paper (30 to 250 g / m ² ) made from the mixed pulp, and synthetic resin sheets such as PET, acrylic resin, OPP, PVC, polycarbonate, and ABS.
[0011]
The above-mentioned papermaking paper may contain additives such as general sizing agents, paper strength agents, fillers, antistatic agents, optical brighteners, dyes, etc., and further surface sizing agents, surface strength agents, A fluorescent whitening agent, an antistatic agent, a dye, an anchoring agent and the like may be coated on the surface.
However, in the present invention, in order to increase the surface smoothness and the surface glossiness, it is preferable to use a material whose surface smoothness is enhanced by calendering or the like.
Further, the above-mentioned synthetic resin sheet may be any of transparent, translucent, and opaque with high surface smoothness.
[0012]
The first layer mainly composed of a polyvinyl alcohol-based resin appears as the outermost layer of the ink jet recording sheet of the present invention, and mainly functions as a layer for obtaining high surface smoothness and surface glossiness.
The polyvinyl resin is a water-soluble resin, and polyvinyl alcohol (hereinafter, also referred to as PVA), modified polyvinyl alcohol, or the like can be used. Examples of the modified polyvinyl alcohol include completely saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, and cation-modified polyvinyl alcohol.
Further, polyvinyl alcohol copolymerized with another resin, polyvinyl alcohol blended with another hydrophilic polymer, or the like can also be used.
[0013]
As the above-mentioned polyvinyl alcohol-based resin, a commonly used resin can be used as it is, and for example, a completely saponified type resin can be preferably used.
[0014]
The first layer may contain 5 to 60% by weight of an inorganic filler from the viewpoint of preventing blocking and improving ink absorbency.
The type of the inorganic filler is not particularly limited, and for example, silica, talc, kaolin, clay, titanium oxide, zinc oxide, calcium carbonate, etc., which are generally used for this type of recording sheet, can be used.
Although the particle size of the inorganic filler is not particularly limited, it is preferable to use those having an average particle size of about 0.1 to 2.0 μm in order to increase the surface smoothness and the surface glossiness.
If the content is less than the above, the ink absorbency is poor. If the content is more than the above, the surface smoothness or the surface gloss may be reduced, or the transparency may be hindered.
[0015]
Further, the first layer may contain a urethane-based resin in an amount of 5 to 95% by weight instead of or together with the inorganic filler.
The urethane-based resin is also compounded for the purpose of improving heat resistance and ink absorbency in addition to blocking prevention similar to the above-mentioned inorganic filler.
As the urethane resin, those generally used for this type of recording sheet can be used as they are, for example, a polyurethane resin having an alkylene oxide chain such as ethylene oxide, propylene oxide, butylene oxide, or a combination thereof, a sulfonic acid group, and the like. Polyurethane resin containing a polycarbonate chain, polyurethane resin containing a polycarbonate chain and a polyester chain, and the like.
[0016]
The second layer mainly composed of a polyalkylene oxide resin is formed on the lower surface side of the first layer and on the upper surface of the base sheet, and mainly functions as an ink receiving layer.
The polyalkylene oxide-based resin is a water-absorbing resin, and those usually used for this type of recording sheet can be used as they are, for example, polyethylene oxide, polypropylene oxide, polybutylene oxide, and the like. Copolymerized oxides obtained by the combination of these, and their transesterified products can be used.
[0017]
Further, the second layer may contain 5 to 70% by weight of the cationic resin.
The cationic resin is blended to improve the bleeding characteristics of the ink, and is, for example, a copolymer comprising a monomer having a quaternized amino group such as polyallylamine hydrochloride and polyalkylaminoacrylate. Polymers and the like are preferably used.
These cationic resins preferably have a melting point of 60 to 200 ° C. and a molecular weight of 1,000 to 100,000.
If the amount of the cationic resin is less than the above, the bleeding property of the ink cannot be improved, and if the amount is more than the above, this effect is not only saturated, but also the content of the polyalkylene oxide-based resin becomes relatively small. However, the ink receiving function itself may be impaired.
[0018]
The first layer and the second layer may include a cationic surfactant such as polyethyleneimine, quaternary ammonium chloride, and quaternary ammonium sulfate, and a nonionic surfactant such as polyoxyethylene alkylamine and glycerin fatty acid ester. A surfactant may be incorporated in an amount of about 1 to 10% by weight.
Further, various additives such as an antioxidant and an ultraviolet absorber may be added to the first and second layers as long as the characteristics of the present invention are not impaired.
In particular, in order to prevent thermal degradation of these layers (particularly thermal degradation during melt extrusion) and to enhance thermal stability, it is preferable to add an antioxidant in an amount of about 0.3 to 1.5% by weight.
[0019]
It is important that the first layer, which is the outermost layer of the recording sheet of the present invention, has a surface smoothness in the range of 1.0 to 2.0 μm.
If the surface smoothness is less than this, it is not possible to obtain a print quality as high as photographic quality, and even if the surface smoothness is higher than this, the effect of high print quality is saturated with the current inkjet printer. Not only that, the transportability of the printer is rather hindered.
On the other hand, if the thickness of the first layer is too small, the desired surface smoothness, surface glossiness, or transparency cannot be obtained. If the thickness is too large, this effect is saturated and uneconomical. Therefore, the thickness is preferably about 0.1 to 1.5 μm.
If the thickness of the second layer is too small, the desired ink receptivity cannot be obtained. If the thickness is too large, this effect is saturated and uneconomical, so that it is preferably about 15 to 50 μm. .
The total thickness of the first layer and the second layer is preferably about 15.1 to 51.5 μm.
[0020]
The inkjet recording sheet of the present invention having the above configuration can be preferably obtained by the following production method of the present invention.
That is, first, a first layer having the above thickness mainly composed of the polyvinyl alcohol resin is formed.
This formation method may be any method, for example, a method of coating a solution mainly composed of the polyvinyl alcohol-based resin on a support made of a synthetic resin or the like, drying the solution, and forming a film of the polyvinyl resin. It can be formed by a method of forming a melt mainly composed of an alcohol-based resin into a film by an extrusion method, or a method of laminating the extruded film on a support made of a synthetic resin or the like. In addition, various methods such as gravure coating, knife coating, roll coating, comma doctor coating, and rotary screen coating can be applied to the above-mentioned coating.
[0021]
Further, when the first layer is formed by coating on a support or when the first layer is laminated on the support, the support is peeled off after lamination of the first layer and the second layer, as described later. Therefore, for example, it is made of a synthetic resin (specifically, PET, PEN, or the like) that hardly adheres to the polyvinyl alcohol-based resin that is a constituent material of the first layer and has little repelling of the paint so that the peeling can be easily performed. It is preferable to use a film or a thin metal plate, or to use a material in which a release agent is applied on these supports in advance.
[0022]
On the other hand, a second layer having the above thickness mainly composed of the above polyalkylene oxide resin is formed on the above substrate sheet.
This forming method is not particularly limited, and any method may be used. For example, a film obtained by extruding a melt mainly composed of the above-described polyalkylene oxide-based resin is laminated on a base sheet by heat lamination. And a method of coating a solution mainly containing the above-mentioned polyalkylene oxide-based resin on the base sheet in the same manner as in the case of the above-mentioned first layer.
[0023]
Next, the first layer and the second layer are stacked in surface contact.
By this lamination, for example, when the first layer is formed on the support by coating, the first layer on the support and the second layer on the base sheet are provided between the support and the base sheet. Are present in a state where they are in surface contact with each other.
When the first layer is formed in a film form without using a support, the first layer (film) is laminated on the second layer on the base sheet by surface contact, and the first layer is formed on the base sheet. An embodiment in which the two layers and the first layer are stacked in this order is obtained.
[0024]
The method of laminating the first layer and the second layer is not particularly limited, and heat and pressure may be applied to those that are brought into surface contact with a hot roll or a hot press machine, or in some cases, an adhesive may be easily used. Can be stacked.
When laminating by applying pressure, or by applying pressure and heat, in the case of applying only pressure, the laminate is passed between two rolls to which a pressure of about 1.5 to 5 kgf / cm is applied at a speed of about 5 to 15 m / min. In the case where both pressure and heat are applied, a temperature of about 5 to 15 m / min is applied between two heat rolls to which heat of about 50 to 80 ° C. and pressure of about 1.5 to 10 kgf / cm are applied. By passing at a speed, lamination can be performed.
[0025]
When using the first layer formed on a support as the first layer, the support is removed after the above-described lamination.
As described above, this removal can be performed by a simple peeling operation because the first layer and the support are not in close contact with each other.
Therefore, the roughening of the surface state of the first layer due to the operation of removing the support can be suppressed as much as possible.
[0026]
Subsequently, a smooth synthetic resin film is overlaid on the surface of the first layer, and hot pressed from above the film.
This hot press is used to transfer the surface state (shape) of the smooth synthetic resin film to the surface of the first layer, and to enhance the surface smoothness, glossiness, and transparency of the first layer and the second layer. It is preferably performed at 50 to 100 ° C., 1.5 to 10 kgf / cm, and 5 to 15 m / min.
If the temperature is lower than the above, the pressure is lower, and the time is shorter (higher speed), the above transfer cannot be performed satisfactorily. In addition to being saturated and uneconomical, there is a possibility that the first layer and the second layer may be deteriorated.
[0027]
The smooth synthetic resin film used for this hot press does not adhere to the first layer even by the above hot press, for example, a film made of PET, PEN, or the like, a synthetic resin film to which mold release property is previously given, or the like. Can be used.
The synthetic resin film preferably has a surface smoothness of about 0.8 to 1.2 μm. If the synthetic resin film has such a surface smoothness, the first layer of the inkjet recording sheet of the present invention may be used. The surface smoothness described above can be easily achieved.
[0028]
In the present invention, after the hot pressing, the synthetic resin film is kept in contact with the surface of the first layer, in other words, the first layer and the second layer are restrained by the synthetic resin film (and the base sheet). It is preferable to cool to room temperature at a rate of 8 to 25 ° C./s as it is.
By this rapid cooling, the surface smoothness, glossiness, and transparency of the first layer and the second layer obtained by the above-mentioned hot press can be maintained.
If the cooling rate during the quenching is slower or faster than the above, surface shrinkage or crystallization may occur, which impairs smoothness, glossiness, and transparency, and the quenching is performed after the synthetic resin film is peeled off. However, similar surface shrinkage and crystallization may occur.
[0029]
After the rapid cooling, the synthetic resin film is peeled off. As described above, since the synthetic resin film does not adhere to the first layer by hot pressing as described above, the synthetic resin film can be easily removed without roughening the surface state of the first layer. Can be peeled off.
As a result, it is possible to obtain the ink jet recording sheet of the present invention which has the above-mentioned high surface smoothness and surface glossiness, and also has excellent transparency.
[0030]
【Example】
Example 1
Methyl octadecane-1,18-dicarboxylate is added to polyalkylene oxide (hereinafter sometimes referred to as PAO) obtained by addition polymerization of ethylene oxide to ethylene glycol, then addition polymerization of butylene oxide, and further addition polymerization of ethylene oxide. In addition, a transesterification reaction was performed.
To 100 parts by weight of the thus obtained sample A ′ having a weight average molecular weight of 150,000, 1 part by weight of tocophenol (trade name “UVINUL2000AO” manufactured by BASF) is added as a heat stabilizer to prepare sample A. .
[0031]
Sample A was melt-extruded with a T-die extruder, and film-forming extrusion was performed so that the film thickness became 35 μm.
At this time, the T-die temperature was 190 ° C., and the total thickness of the two layers was 32 μm.
The 35 μm-thick sheet (second layer) thus obtained was thermally laminated (80 ° C., 7.5 kgf / cm, 3 m / min) on a 100 μm-thick PET film (base sheet) to obtain a sample. B was obtained.
A cross section of this sample B is schematically shown in FIG.
In the figure, reference numeral 10 denotes a base sheet made of a PET film, on which a second layer 2 made of a sample A (mainly PAO) is formed.
[0032]
Next, PVA (trade name “GOSEFIMER 200” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) is gravure coated on a PET (support) having a thickness of 25 μm to form a 0.5 μm PVA layer (first layer). And Sample C.
A cross section of this sample C is schematically shown in FIG.
In the figure, reference numeral 11 denotes a support made of PET, on which a first layer 1 made of PVA is formed.
[0033]
As shown schematically in FIG. 1 (C), the sample B and the sample C are overlapped by bringing the surface of the first layer 1 of the sample C into contact with the surface of the second layer 2 of the sample B, and passed between hot rolls. After heat laminating at 100 ° C. and 7.5 kgf / cm at 3 m / min, the PET (support) 11 of Sample C was peeled off to obtain Sample D schematically shown in FIG.
[0034]
Next, as schematically shown in FIG. 1 (E), a 25 μm-thick PET (synthetic resin film, trade name “Lumirror T” manufactured by Toray Industries, Inc.) 12 is placed on the surface of the sample D, that is, the surface of the first layer 1. Were stacked and passed through a hot roll to perform heat lamination at 70 ° C., 7.5 kgf / cm, and 10 m / min.
Thereafter, the PET 12 was peeled off and allowed to cool to room temperature to obtain the inkjet recording sheet of the present invention. The surface smoothness of this recording sheet (the surface of the first layer 1) was 1.4 μm.
[0035]
Example 2
In Example 1, silica having an average particle diameter of 0.6 μm was added to PVA as a constituent material of the first layer 1 at a weight ratio of PVA: silica = 1: 1, and PAO as a constituent material of the second layer 2 was mainly used. Of the present invention in the same manner as in Example 1 except that a cationic resin (trade name “Rheox” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added to Sample A at a weight ratio of Sample A: Cationic resin = 70: 30. An inkjet recording sheet was obtained. The surface smoothness of the recording sheet (the surface of the first layer 1) was 1.5 μm.
[0036]
Comparative Example 1
In Comparative Example 1, a comparative inkjet recording sheet was obtained in the same manner as in Example 1 except that the step of laminating and thermally laminating the PET 12 shown in FIG. 1E was omitted. The surface smoothness of this recording sheet (the surface of the first layer 1) was 3.2 μm.
[0037]
Example 3
In Example 1, after the PET12 shown in FIG. 1 (E) was overlaid and thermally laminated, it was quenched at a rate of 10 ° C./s between water-cooled rolls at 20 ° C. in the same manner as in Example 1 to obtain the present invention. An inkjet recording sheet was obtained. The surface smoothness of the recording sheet (the surface of the first layer 1) was 1.5 μm.
[0038]
Comparative Example 2
The sample A was formed into a 35 μm film by a T-die extruder and heat-laminated (80 ° C., 7.5 kgf / cm, 5 m / min) on a 100 μm-thick PET film as the same base sheet as in Example 1. Thus, a comparative inkjet recording sheet was obtained. The surface smoothness of this recording sheet was 2.2 μm.
[0039]
〔Evaluation method〕
With respect to the ink jet recording sheets obtained in the above Examples and Comparative Examples, the surface glossiness, transparency (light transmission), print quality, coloring, and print image storability (durability) were evaluated in the following manner.
[0040]
"Surface gloss":
The one immediately after the production and the photographic printing paper were visually observed and compared, and evaluated according to the following criteria. The results are shown in Table 1.
：: Very close to the gloss of photographic paper ○: Near to the gloss of photographic paper ×: Completely different from the gloss of photographic paper
"Transparency" (light transmission):
The one immediately after the production and the photographic printing paper were visually observed and compared, and evaluated according to the following criteria. The results are shown in Table 1.
◎: Very close to the transparency of photographic paper ○: Near to the transparency of photographic paper ×: Completely different from the transparency of photographic paper [0042]
“Printing quality”: Each recording sheet was aligned to A4 size, and a pattern that was independently manufactured using Hewlett-Packard's trade name “DesignJet 350C” was printed. The same photographic paper as the one used was photographed and printed with the same pattern as the pattern), and visually observed to see if the image quality close to that of the photograph was high due to its color development and surface gloss. Comparative observation was made and evaluated according to the following criteria. The results are shown in Table 1.
◎: Very close to photographic quality ：: Close to photographic quality X: Completely different from photographic quality
"Coloring property": The above image quality was visually observed and compared with the above photograph, and evaluated based on the following criteria.
：: Very close to color development of photographic quality ：: Close to color development of photographic quality X: Completely different from color development of photographic quality
“Printed image storage stability” (durability): Each sample on which an image was printed as described above was stored at 40 ° C. and 90% RH for 24 hours, and the change in the image was visually observed and judged. Was evaluated. The results are shown in Table 1.
A: The state immediately after printing is kept as it is. O: The state immediately after printing is kept almost as it is. X: The state is completely different from the state immediately after printing.
[Table 1]

[0046]
【The invention's effect】
As described above, according to the inkjet recording sheet of the present invention, it is possible to easily obtain print quality close to photographic image quality using a normal inkjet printer.
Further, according to the production method of the present invention, it is possible to obtain an ink jet recording sheet capable of obtaining excellent print quality close to the photographic image quality by an extremely easy operation.
[Brief description of the drawings]
FIG. 1 schematically shows the method of the invention in a step-by-step manner.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 first layer 2 second layer 10 base sheet 11 support 12 synthetic resin film

Claims (9)

A first layer mainly composed of a polyvinyl alcohol-based resin and a second layer mainly composed of a polyalkylene oxide-based resin, wherein a base sheet is laminated on the non-first layer side of the second layer; An ink jet recording sheet, wherein the surface smoothness of the layer is 1.0 to 2.0 μm. The ink jet recording sheet according to claim 1, wherein the first layer contains 5 to 60% by weight of an inorganic filler. 3. The ink jet recording sheet according to claim 1, wherein the first layer contains a urethane-based resin in an amount of 5 to 95% by weight. The inkjet recording sheet according to any one of claims 1 to 3, wherein the second layer contains a cationic resin in an amount of 5 to 70% by weight. Forming a first layer mainly composed of a polyvinyl alcohol-based resin,
Forming a second layer mainly composed of a polyalkylene oxide resin on the base sheet,
Stacking the first layer and the second layer in surface contact,
Superimposing a smooth synthetic resin film on the surface of the first layer and hot pressing from above the film;
Peeling the synthetic resin film,
A method for producing an ink jet recording sheet, comprising: 6. The method according to claim 5, wherein the surface smoothness of the synthetic resin film is 0.8 to 1.2 [mu] m. 7. The method according to claim 5, wherein the synthetic resin film is a polyethylene terephthalate resin film. The method for producing an inkjet recording sheet according to any one of claims 5 to 7, wherein the hot pressing is performed by a hot roll at 50 to 100 ° C, 1.5 to 10 kgf / cm, and 5 to 15 m / min. . The method for producing an ink jet recording sheet according to any one of claims 5 to 8, wherein the sheet is cooled at a rate of 8 to 25 ° C / s after hot pressing and before peeling of the synthetic resin film.

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