WO2004073995A1 - Inkjet recording sheet - Google Patents

Abstract

An inkjet recording sheet is disclosed which comprises a supporting body at least one surface of which is provided with an ink-accepting layer which contains alumina and colloidal silica as pigments. The ink-accepting layer is formed by a cast coating method using a coating liquid which contains alumina and colloidal silica as pigments and into which a alkyl acrylate-dimethylaminoalkyl methacrylate-styrene copolymer is blended.

Description

 Description Inkjet recording sheet Technical field

 The present invention relates to an ink jet recording sheet, and more particularly to an ink jet recording sheet for improving glossiness. Background art

 The ink jet recording method is a method of recording images, characters, etc. by ejecting fine ink droplets by various operating principles and attaching the ink droplets to an ink jet recording sheet or the like. It has advantages such as high flexibility of recording patterns and no need for fixed development. It is rapidly spreading in various applications as a recording device for various figures including kanji and color images. Furthermore, images formed by an ink jet recording method using multicolor inks containing dyes such as yellow, magenta, cyan, and black, respectively, are compared with multicolor printing by the plate making method and printing by the force photographic method. As a result, it is possible to obtain comparable recorded images, and in applications where the number of copies required is small, it is being widely applied to the field of full-color image recording because it is less expensive than development using silver halide photography. .

The ink jet recording sheet used in the ink jet recording method may be an ink jet recording device, a dye-structured ink composition surface so that general paper such as high-quality paper or coated paper used for ordinary printing and writing can be used. However, as the performance of inkjet recording devices has increased and applications have expanded, such as higher speeds and higher definition and full color, more advanced characteristics are also required for inkjet recording sheets. Required. In other words, the ink jet recording sheet has a high density of print dots, a bright and vivid color tone, a fast ink absorption, no ink bleeding or bleeding even when print dots overlap, and a print dot sheet. To the surface It is necessary to satisfy various requirements, such as that the diffusion of the ink does not become larger than necessary, that the shape of the ink dots is close to a perfect circle, the periphery is smooth and not blurred, that the whiteness is high, and that the contrast with the ink dots is large. .

 Conventional general ink jet recording sheets include a base material such as a base paper and a pigment and a binder such as amorphous silica or synthetic silica, clay, and calcium carbonate as main components on at least one surface of a support of the recording sheet. It is known that an ink receiving layer is formed by applying a coating liquid using a blade coater, an air knife coater, a rono recorder, a no coater, a gravure coater, a rod blade coater, a lip coater, a curtain coater, a die coater, or the like. ing.

Further, in this general Inkujetto recording sheet, for absorbing and preventing bleeding of Inku is not sufficient, on at least one surface of a support, a specific surface area in the pigment is 5 0 ~1 3 0 m ² Z by the soft calcium carbonate is g contained 5 0 wt _^0/0 or more, coating the coating liquid in a cast coating method, containing 5 to 5 0 parts by weight of a binder to the pigment 1 0 0 parts by weight One in which an ink receiving layer is formed has been proposed (for example, see Japanese Patent No. 3195330).

 In addition, while increasing the ratio of the soft calcium carbonate to further exert the above-mentioned effects and increasing the power and discoloration resistance, at the same time as improving the smoothness and the gloss, which are reduced accordingly, at least one of the supports is used. On the surface, the pigment contains 70% by weight or more of the above-mentioned soft calcium carbonate, preferably less than 30% by weight of synthetic silica, and 5 to 50 parts by weight of a binder with respect to 100 parts by weight of the pigment. In addition, there has been proposed an ink receiving layer formed by applying a coating solution containing an aluminum chelate compound by a cast coat method (for example, see Japanese Patent No. 31955329). ).

However, even with these ink jet recording sheets, it is not possible to obtain high glossiness such as multicolor printing by a plate making method or printing by a color photographic method. Therefore, as an ink jet recording sheet having high glossiness, at least one surface of the support contains alumina and colloidal silica in the pigment, and 100 parts by weight of the pigment such as cationic acrylic emulsion is used. Contains 30 to 50 parts by weight of a binder, and if necessary, an auxiliary agent It is known that an ink receiving layer is formed by applying a coating liquid containing a cation stabilizer or the like by a cast coating method.

 However, there is a problem that even an ink jet recording sheet having a glossy ink receiving layer is not enough to obtain high glossiness close to printing by a photographic method. That is, 75% gloss is 75% according to “75-degree specular gloss test method for paper and paperboard, JISP 8142”, and 20% according to “specular gloss test method, JISZ8741”. ° Gloss is about 20%, and there is a problem that it is not possible to achieve a 75 ° gloss of 80% or more and a 20 ° gloss of 30% or more, which are equivalent to the glossiness by printing. As a method of improving the gloss, a method of increasing the nip pressure pressing the drum by the cast coat method or a method of reducing the coating speed can be considered, but the former method causes the ink receiving layer to be pressed. As a result, the ink absorbency decreases and the ink jet adequacy decreases, and the latter method causes a problem that the productivity decreases.

 An object of the present invention is to provide an ink jet recording sheet having a high glossiness equivalent to photographic printing in view of the above conventional problems. Disclosure of the invention

 The ink jet recording sheet of the present invention is an ink jet recording sheet provided with an ink receiving layer containing anoremina and colloidal silica as a pigment on at least one surface of a support, wherein the ink receiving layer comprises:

R = alkyl group W

 Four

 R = alkyl group

Characterized in that an alkyl acrylate and a dimethylaminoalkyl styrene methacrylate copolymer having the following structural formula are blended.

 By adding and blending the above copolymer as an auxiliary in this way, the glossiness of the ink receiving layer can be improved.For example, 75 ° gloss obtained by conventional printing is 80% or more, and 20 ° gloss is 30% or more. Glossiness can be obtained in the ink receiving layer, and high-quality photographic images can be formed by ink jet recording.

 The copolymer is preferably blended in an amount of 0.1 to 0 parts by weight per 100 parts by weight of the pigment. If the amount is less than 0.1 part by weight, the effect of improving glossiness is not sufficiently exhibited. If the amount exceeds 10 parts by weight, if the water resistance and the surface strength of the ink receiving layer are lowered, a disadvantage occurs. Further, as the copolymer, those having n and (r + s + t) in the structural formula of 30 to 500 and r> 5, s> 5, and t> 5 can be suitably used. . In addition, if the pigment particle size is equal to or less than the wavelength of visible light, scattering of the visible light does not occur.By setting the particle size to 400 nm or less, the glossiness of the ink receiving layer can be improved. 50 ηπ! High gloss can be obtained by setting the thickness to 10 nm.

In addition, when the ink receiving layer is formed by a cast coating method in which the wet coating layer formed on the base paper surface has a mirror-finished cylindrical outer surface and is pressed against a heated drum, the glossiness is high. The ink receiving layer can be formed with high productivity. The film surface It is also possible to apply a film transfer method in which a wet coating layer is formed on the base paper, and this film is pressed against a base paper with a heating drum to transfer and form an ink receiving layer. By using this, a desired glossiness can be obtained even when an arbitrary coating method is applied. BEST MODE FOR CARRYING OUT THE INVENTION

In the ink jet recording sheet of the present invention, a mixture of alumina and colloidal silica is used as the pigment. The mixing ratio is typically 50 parts by weight for both, but is appropriately selected and blended in the range of 10 to 90 parts by weight depending on the use. The particle size of the pigment is preferably at most 400 nm, which is equal to or less than the wavelength of visible light of 400 to 800 nm, because light can be suppressed from being scattered by the pigment. By setting the thickness to about 0 nm or less, the glossiness can be further improved. In order to obtain desired printability, it is preferable to use those pigments having a specific surface area of 100 m ² / g or more by BET, more preferably 200 m ² Zg or more. It is suitable.

 Specific examples include alumina having a particle diameter of about 40 nm using "Desperal HP 10" (crystal particle diameter is 10 nm) manufactured by Sassonore Co., Ltd. and colloidal powder manufactured by Nissan Chemical Industries, Ltd. A mixture obtained by mixing 50 parts by weight of silica, "Snowtex II" or "Snowtex OL" having a particle diameter of about 40 nm and 50 parts by weight is also preferably used. In some cases, an optional pigment such as clay can be added.

It is preferable to form 30 to 50 parts by weight of a cationic acryl emulsion as a binder with respect to 100 parts by weight of these pigments to form a coating liquid. Other binders include, for example, polyvinyl alcohol, silanol-modified polyvinyl alcohol, butyl acetate, oxidized starch, etherified starch, cellulose derivatives such as carboxymethylcellulose, hydroxyxethyl cellulose, casein, gelatin, Soy protein, silyl-modified polyvinyl alcohol, etc .; conjugated diene copolymers such as maleic anhydride, styrene butadiene copolymer, methyl methacrylate butadiene copolymer Polymer latexes; acrylic polymer latexes such as polymers or copolymers of acrylates and methacrylates; or functional group-modified polymers of these various polymers with functional group-containing monomers such as carboxyl groups Latex; water-based adhesives such as melamine resins, urethane resins, and other thermosetting synthetic resins; synthesis of polymethyl methacrylate, polyurethane resins, unsaturated polyester resins, vinyl chloride-butyl acetate copolymer, polybutylbutyral, alkyd resins, etc. One or more resin-based adhesives can be used alone or in combination.

 In the present invention, 0.1 to 10 parts by weight of the alkyl acrylate-dimethylaminoalkyl methacrylate-styrene copolymer represented by the above structural formula is added as an aid of the coating solution. As a specific example, “Pearl Gum CT100” manufactured by Hoshi Photo Chemical Industry Co., Ltd., which is used as one kind of cationic sizing agent, can be suitably used. In addition, other additives include cationic dye fixing agents, pigment dispersants, thickeners, flow improvers, defoamers, foam inhibitors, release agents, foaming agents, penetrants, coloring dyes, coloring Pigments, fluorescent whitening agents, ultraviolet absorbers, preservatives, fungicides, water-proofing agents, wet paper strength enhancers, dry paper strength enhancers, antioxidants and the like can also be added as appropriate.

As the support, there are known pulp such as chemical pulp such as LBKP and NBKP, mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP and CGP, waste paper pulp such as DIP, and known pulp. Pigment as a main component, mixed with one or more additives such as binder, sizing agent, fixing agent, retention agent, cationizing agent, paper strength agent, etc. Paper made with various devices such as a paper machine and a twin-wire paper machine, and a size press made of starch, polyvinyl alcohol, etc. on this paper, and a paper coated layer. Includes coated paper such as art paper, coated paper, and cast-coated paper. Such a base paper or a coated paper may be provided with an ink receiving layer as it is, or a calendar device such as a machine calendar, a TG calendar, or a soft calendar may be used for the purpose of controlling flatness. In addition, a porous synthetic resin sheet having open cells can be used as the support. As a method of providing the ink receiving layer on the support, a wet coating layer is formed on the surface of the support. It is preferable to apply a cast coating method which has a mirror-finished cylindrical outer surface and presses against a heated drum after forming the ink, since an ink-receiving layer having high gloss can be formed with high productivity. It is also possible to apply a film transfer method in which a wet coating layer is formed on the film surface, and the finolem is pressed against the support with a heating drum to transfer and form the ink receiving layer on the support surface. Also, by using a pigment having a small particle size as a pigment, a desired glossiness may be obtained even if an arbitrary coating method is applied.

 (Example)

 Next, some examples and comparative examples of the present invention will be described.

The sample ink jet recording sheet was prepared as follows. 5 0 parts by weight of alumina of 4 0 eta m particle size (available from Sasol, "HP 1 0") and, ₅ 0 parts by weight of 4 0 nm colloidal silica particle size (3 production Chemical Industry Co., Ltd. , “Snowtex”), a binder obtained by adding an appropriate amount of polybier alcohol to a cationic acryle marsion, and an auxiliary represented by the above formula (1) or (formula 2). An alkyl acrylate-dimethinoleaminoalkyl methacrylate monostyrene copolymer (Pearl Gum CT 100, manufactured by Seiko Chemical Co., Ltd.) was used according to each example and each comparative example. The coating liquid was prepared by changing the molecular weight and the added parts by weight. The coating liquid was applied to one surface of a support by a cast coating method to form an ink receiving layer, thereby producing an ink jet recording sheet.

 The gloss was evaluated by measuring 75 ° gloss according to JISP 8142 and 20 ° gloss according to JISPZ8741.

 In addition, the applicability of the ink jet printing was evaluated as follows. Using an ink jet printer (PM-800C: Epson), print at 23 ° C and 50% humidity, and measure and observe print density, bleeding and 7-resistance. did.

 Print density was measured by printing solid colors of black, yellow, magenta, and cyan, and measuring the print density of each color using a Macbeth print densitometer (TR 927). , A similar thing was marked as 〇, and a low thing was marked as X.

The bleeding is red, which is made up of the colors of yellow, magenta, and cyan inks, Purple and green are printed solid (size 3.0 cm X 3. O cm) respectively, and the bleeding after printing for 30 minutes is visually confirmed. ◎ No bleeding is observed, and bleeding is slightly observed. Was evaluated as X, and those with bleeding were evaluated as X.

 Water resistance is determined by printing solid black, yellow, magenta, and cyan solid colors, visually confirming bleeding after 30 minutes of printing and immersion in water for 1 minute, and no bleeding due to immersion. , 〇, slightly larger, X

 (Example 1)

 5 parts by weight of a copolymer of the formula (1) where n is 100 was added.

 (Example 2)

 10 parts by weight of the copolymer of the formula (1) where n is 30 was added.

 (Example 3)

 0.1 part by weight of a copolymer of the formula (1) where n is 500 was added.

 (Example 4)

 An r force of 15, a s force of S15, and a t of 15, a total of 45 copolymers of the formula (2) were added by 5 parts by weight U.

 (Example 5)

 0.1 parts by weight of the copolymer of the formula (2), which had an r force of 5, an s force of 15, and a t of 10, were added in a total of 30 parts.

 (Example 6)

 A total of 500 copolymers (formula 2), 150 and 8, 300 and t, were added in 10 parts by weight.

 (Comparative Example 1)

 No copolymer was added.

 (Comparative Example 2)

 15 parts by weight of the copolymer of the formula (1) where n is 30 was added.

 (Comparative Example 3)

0.05 parts by weight of a copolymer of the formula (1) with n of 50 was added. (Comparative Example 4)

 0.2 part by weight of a copolymer of the formula (1) where n is 800 was added.

 (Comparative Example 5)

 10 parts by weight of the copolymer of the formula (1) where n is 10 was added.

 (Comparative Example 6)

 5 parts by weight of the copolymer of the formula (2) in which r was 0, s force was 30, and t was 0, that is, a total of 30 were added. (Comparative Example 7)

 5 parts by weight of a copolymer of the formula (2) in which r was 500, s was 0, and t was 0, that is, a total of 500 were added.

 (Comparative Example 8)

 5 parts by weight of a copolymer of the formula (2) in which r was 0, s force S100, and t was 100, totaling 200 were added.

 (Comparative Example 9)

 Five parts by weight of the copolymer of the formula (2) with an r force of 300, an s of 200, and a t of 200, totaling 700, were added.

 (Comparative Example 10)

 15 parts by weight of the copolymer of the formula (2) in which r was 50, s was 0, and t was 50, that is, 100 in total were added.

 Tables 1 and 2 show the evaluation results of the glossiness and printability of each of the above Examples and Comparative Examples. table 1

表 2

Table 2

表 1において、 助剤として、 構造式 1の nが 100の共重合物を 5重量部配合し た実施例 1においては、 75° 光沢が 85%、 20° 光沢が 41%を達成し、 かつ 印字性における印字濃度、 滲み、 耐水性も良好である。 また、 nが 30と小さい共重 合物を 10重量部配合した実施例 2においては、 所望の光沢度は達成できているが、 光沢及び印字性で若干劣ることが分かる。 また、 逆に nが 500と大きい共重合物を 0. 1重量部だけ配合した実施例 3においては、 所望の光沢度が達成できるとともに 印字性も良好であることが分かる。 また、 構造式 1の共重合物を配合しない従来例に 相当する比較例 1では、 印字性は良好であるが、 75° 光沢が 75%、 20° 光沢 が 20%と低く、 光沢度が不充分である。 また、 配合量を 15重量部とした比較例 2 では、 光沢度は高いが、 印字性が著しく悪化してしまっている。 また、 配合量が 0. 05重量部と少ない比較例 3では、 比較例 1の従来例とあまり変わらず、 構造式 1の 共重合物を添加した効果が得られないことが分かる。 また、 構造式 1の nが 800と 大きレ、共重合物を配合した比較例 4では、 力ラ一調整自体が不可能で、 実施不可とな つている。 逆に、 構造式 1の nが 10と小さい共重合物を 10重量部配合した比較例 5では、 光沢度が比較例 1の従来例とあまり変わらずかつ印字性が悪化している。 こ れらより、 構造式 1の nが 30〜500共重合物を、 0. 1〜； L 0重量部配合するこ とで、 75° 光沢が 80%以上、 20° 光沢が 30%以上を達成し、 かつ印字性に おける印字濃度、 滲み、 耐水性も良好であることが分かる。

In Table 1, in Example 1, in which 5 parts by weight of a copolymer of Structural Formula 1 with n of 100 was blended as an auxiliary, 75 ° gloss reached 85%, 20 ° gloss achieved 41%, and Good print density, bleeding, and water resistance in printability. In addition, in Example 2 in which 10 parts by weight of the copolymer having n as small as 30 was blended, the desired glossiness was achieved, but it was found that the glossiness and printability were slightly inferior. Conversely, in Example 3, in which only 0.1 part by weight of the copolymer having n as large as 500 was blended, it was found that the desired glossiness could be achieved and the printability was good. In Comparative Example 1, which corresponds to the conventional example in which the copolymer of Structural Formula 1 was not blended, the printability was good, but the 75 ° gloss was 75%, the 20 ° gloss was as low as 20%, and the gloss was not good. Is enough. In Comparative Example 2 where the blending amount was 15 parts by weight, the glossiness was high, but the printability was significantly deteriorated. Further, in Comparative Example 3 in which the blending amount was as small as 0.05 part by weight, it was found that the effect of adding the copolymer of Structural Formula 1 was not obtained, which was not much different from the conventional example of Comparative Example 1. Further, in Comparative Example 4 in which n of structural formula 1 was as large as 800 and the copolymer was blended, the adjustment of the force itself was impossible, so that it was not possible to carry out the adjustment. Conversely, in Comparative Example 5, in which 10 parts by weight of the copolymer of structural formula 1 having n as small as 10 was blended, the glossiness was not much different from that of the conventional example of Comparative Example 1, and the printability was poor. From these, the blending of the copolymer of structural formula 1 with n of 30 to 500 and 0.1 to 0 parts by weight of L gives a 75 ° gloss of 80% or more and a 20 ° gloss of 30% or more. Achieved and printability It can be seen that the print density, bleeding, and water resistance in the ink were good.

 In Table 2, in Example 4, in which 5 parts by weight of a copolymer having a total of 45, r, s, and t in Structural Formula 2 were blended, as an auxiliary, 75. Achieved a gloss of 81% and a 20 ° gloss of 38%, and good print density, bleeding, and water resistance in strong printability. Also, in Example 5, in which 0.1 part by weight of a copolymer having a total of 30 in which r was 5, s force was 15 and t was 10 was blended, glossiness was slightly reduced but good results were similarly obtained. Have been obtained. Further, in Example 6, where r was 150, 3 was 300, and t was 50, and a total of 500, a high molecular weight copolymer was compounded as much as 10 parts by weight, high gloss was obtained. Although it has been obtained, the tendency that the printability decreases is recognized. In Comparative Example 6, where r was 0, s was 30, and t was 0, and a total of 30 copolymers were blended in 5 parts by weight, since r and t were 0, the conventional copolymer in which no copolymer was blended was used. As in the example, the glossiness was not improved even though the printability was good. Further, in Comparative Example 7 in which 5 parts by weight of a copolymer of 50,000 and s force S 0, t of 0 was blended, that is, 50,000, and r and t were 0, the copolymer was The glossiness is not improved as compared with the conventional example in which the compound is not blended, and the printability is remarkably deteriorated by blending a copolymer having a large molecular weight. Further, in Comparative Example 8 in which 5 parts by weight of a copolymer having r of 0, s of 100, and t of 100, that is, a total of 200, was not improved in glossiness as compared with the conventional example, In addition, the printability tends to deteriorate. Further, Comparative Example 9 in which 5 parts by weight of a copolymer of 1: 300, 3: 200, t: 200, and a total of 700 was blended, it was impossible to adjust the force in itself, Impossible. Further, in Comparative Example 10 in which 15 parts by weight of a copolymer of r = 50, s = 0, and t = 50 was added, the glossiness was not improved and the printability was remarkable. It is getting worse. From these facts, when r, s, and t are each 5 or more, and 0.1 to 10 parts by weight of a total of 30 to 500 copolymers is blended, the 75 ° gloss is 80%. As described above, it can be seen that the 20 ° gloss reached 30% or more, and the print density, bleeding, and water resistance in printability were also excellent. Industrial applicability

As described above, according to the present invention, alkyl acrylate-dimethylaminoalkyl styrene methacrylate is contained in a coating layer containing alumina and colloidal resiliency in the pigment. Is suitable for providing an ink jet recording sheet having a high gloss corresponding to a photographic print having a 75 ° gloss of 80% or more and a 20 ° gloss of 30% or more. .

Claims

13 Scope of Claim 1. An ink jet recording sheet provided with an ink receiving layer containing alumina and colloidal silica as a pigment on at least one surface of a support, wherein the ink receiving layer comprises: ¾H

 R = alkyl group  Or

R dialkyl group Ink jet recording sheet, characterized in that blended with the copolymer having the structural formula _£ 2. The ink jet recording according to claim 1, wherein the copolymer having the structural formula is contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the pigment. Sheet. 3. The structure according to claim 1, wherein in the structural formula of the structure, n and (r + s + t) are 30 to 500, and r> 5, s> 5, and t> 5. 2. The ink jet recording sheet according to item 1. 4. The ink jet recording sheet according to claim 1, wherein the pigment has a particle size of 400 nm or less. 5. The pigment particle size is 50 ηπ! The ink jet recording sheet according to claim 4, wherein the thickness is from 10 to 10 nm. 6. The ink jet recording sheet according to claim 1, wherein the ink receiving layer is formed by a cast coat method.