JP2002129104A - Coating fluid for protecting surface of printing sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating fluid for protecting the surface of a printing sheet which can obtain a matte surface having very low gloss required for wall covering materials and the like and, at the same time, can obtain high fastness to crocking and anti-staining performance. SOLUTION: The coating fluid is coated on the surface of an inkjet printing sheet having a porous inkjet ink receptive layer and the like and is formulated to have 30-60 pts.wt. acrylic resin based on 100 pt.wt. silicone rubber based resin as the weight ratio of the solid content of the resin components present in an aqueous emulsion solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating liquid for protecting the surface of a print sheet suitable for a wall material printed by an ink jet printer.

[0002]

2. Description of the Related Art With the widespread use of wide format type ink jet printers, print images, which have conventionally been produced only by a large amount or an expensive method such as printing and photographs, can be easily obtained in a small amount and at a low price. One of the prints produced by such an ink jet printer is a print on an indoor wall covering or the like.

[0003] Embossed wallpaper is most commonly used as a wall covering having a picture, and conventionally, a picture is formed by printing on a paper medium, and then foaming and embossing while applying heat are performed. By doing so, the surface is provided with a concavo-convex emboss pattern.

In order to create such embossed wallpaper not by printing but by inkjet printing,
For example, a method disclosed in JP-A-2000-226799 is exemplified.

[0005] The method for producing embossed wallpaper disclosed in this gazette is to apply an ink receiving layer for inkjet printing on a thermoplastic resin layer and then apply embossing to a wallpaper medium dedicated to inkjet printing. A desired pattern is formed on the surface using an ink jet printer.

[0006] In a print sheet or the like on which an image is formed by ink-jet printing, the surface of the ink-receiving layer that receives the ink-jet ink or the printing ink is liable to be stained as it is and has low friction fastness, which poses a practical problem.

[0007] To solve this problem, an easily conceivable solution is to laminate an extremely thin plastic sheet on the wallpaper surface after printing.
In the case of this laminating process, by performing laminating after printing, and then embossing,
An embossed wallpaper with a protected surface can be obtained.

[0008] However, this embossing requires a large-scale apparatus, and since the embossing is performed in units of several hundred meters or more, a variety of small quantities of several meters to at most several tens of meters in length are required. It is not suitable for printing on a print sheet produced by an inkjet printer that mainly performs production. That is, the print sheet produced by the inkjet printer is several meters to at most several tens of meters as described above, and even if an attempt is made to emboss the wallpaper that has been subjected to lamination on such a print sheet, This is because the length of the wallpaper is too short to be well adapted to the embossing device.

Therefore, in order to combine the ink jet printing and the embossing, a long ink embossed wallpaper for ink jet printing is prepared in advance, and the ink jet printing is performed on the wall paper. Will be applied.

However, in this case, the laminating process is performed after the embossing process and the printing process are performed, and a thin plastic sheet must be attached along the embossed uneven pattern. This is a very difficult task.

As described above, it can be said that it is not appropriate to employ lamination as a technique for protecting the surface of the wallpaper that has already been embossed. As another surface protection processing method for solving the above problem, there is known a method in which a coating liquid is applied to the surface of a print sheet to form a protective film.

A coating liquid applied onto a pattern such as an image formed by ink jet printing is made of a resin-based colorless and transparent resin such as an acrylic resin or a polyurethane resin so as to obtain a glossy surface for both surface protection and image quality improvement. A coating agent is variously formulated and used.

That is, by applying a coating liquid to the surface of the print sheet after the embossing and the ink jet printing, a protective film can be formed satisfactorily on a fine uneven pattern due to the embossing.
It is possible to easily form the protective film.

[0014]

However, on the surface of the interior wall covering material such as embossed wallpaper, (1) a surface finish in which shine due to specular reflection is seen depending on the viewing angle is not preferred. ) Sufficient friction fastness, (3) Surface properties that can easily remove stains from coloring materials used in writing instruments such as water-based felt-tip pens and crayons, (4) Finishes that have the effect of preventing fading of pictures by ultraviolet rays, It is necessary to satisfy every requirement.

Therefore, the protective film formed on the surface of the print sheet is expected to satisfy the above-mentioned requirements. However, the conventional colorless and transparent coating liquid for surface protection which forms this protective film has a high friction resistance. Despite being able to meet the other requirements for surface protection, it was not possible to meet the requirement for a matte effect with extremely low gloss.

As a coating apparatus used in the coating step, a type using a coating roller for suppressing scattering of the coating liquid and wasteful consumption of the coating liquid is preferable.
It is expected that the coating liquid is well adapted to such a coating apparatus. However, it has been difficult to obtain a coating liquid that suppresses the occurrence of coating unevenness due to a shortage of supply or an excessive supply, in addition to the purpose of suppressing scattering and useless consumption of the coating liquid.

In view of the above-mentioned problems, the present invention provides (1) a print sheet which can obtain a matte surface with extremely low gloss required for a wall covering material and the like, as well as a high friction fastness and a stain prevention performance. It is intended to provide a surface protective coating liquid. (2) Another object of the present invention is to provide a print sheet surface protective coating liquid which improves the light resistance of an image, in addition to the object of the above (1). (3) In addition to the object of the above (1), the present invention also provides a print sheet surface protective coating liquid which is suitable for a rotary coating roller type coating apparatus and can provide a protective film having an appropriate thickness and no unevenness. Is to do.

[0018]

According to the present invention, there is provided a coating liquid for coating a surface of an ink-jet print sheet or the like having a porous ink-jet ink receiving layer on the surface thereof, in order to achieve the above object. The solid content ratio of the resin component contained in the aqueous emulsion solution is 100 parts by weight of the silicone rubber-based resin,
The acrylic resin was formulated so as to be 30 to 60 parts by weight.

In the above coating solution, 4 parts by weight of an ultraviolet absorber made of ultrafine zinc oxide was added to 100 parts by weight of the total solid content of the resin component. In the coating liquid, the total solid weight of the resin component is 1%.
4 to 8 parts by weight of an ultraviolet absorber composed of ultrafine zinc oxide was added to 00 parts by weight.

The total solid weight of the resin component contained in the 1000 cc coating liquid is set to 120 to 160
g. Further, a coating liquid in which a silicone rubber-based resin is added to a water-based emulsion solution, which is applied to a surface of an ink-jet print sheet or the like having a porous ink-jet ink receiving layer on the surface thereof, and has a thickness of 1000 c
The total solid weight of the resin component contained in the coating liquid of c was set to 80 to 120 g.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The preferred performance of wallpaper to be applied as an interior finish such as a wall or ceiling of a building is as follows.
In A6921 of the JIS standard, the test method and the acceptable value determined by the test method are defined.

For example, with respect to the fading property, a test method shown in 5.4.1 in the above standard is applied, and a performance of a fourth grade or higher is required. Although this fading property largely depends on the performance of the raw material of the ink-jet ink for forming an image, if the performance of the pigment or dye alone of the ink-jet ink alone cannot provide a sufficient evaluation of the fading property, the surface has an ultraviolet absorbing property. It can also be improved by applying a coating or the like.

As for the abrasion resistance, the performance of the dry friction and the wet friction must be at least class 4 after applying the test method shown in 5.4.2 in the above standard. The abrasion resistance of the surface of a wallpaper material having a porous ink-jet ink-receiving layer on the surface is about second class. Therefore, it can be said that reinforcement by some kind of surface protection is necessary from the viewpoint of practical use and satisfying the standard.

The other performance items specified in JIS A6921 have a low relevance to the properties of the wallpaper surface, and thus the description thereof will be omitted. Although not specified in A6921 of the JIS standard, the performance items considered to be practically important as wallpaper include the dirt-prevention product performance display rules stipulated by the Japan Vinyl Industry Association and 21 companies of the Vinyl Construction Subcommittee. It is stipulated that if a product has a performance of class 4 or higher according to a given measurement method, the product may be displayed with a stain prevention performance. In the case of a wallpaper material having a porous ink-jet ink-receiving layer on the surface, only a first-class performance can be obtained on the surface as it is, which is a practical problem. Therefore, some improvement by surface protection is necessary.

Although not specified by the standards, most commercially available wallpapers have a very low gloss surface. This is considered to be because when the glossiness is strong, strong non-uniform regular reflection light enters the eyes depending on the irradiation direction of the illumination light and the viewing angle, making the image difficult to see, and giving the user an unpleasant impression.

A sample attached to a commercially available wallpaper sample book using a gloss meter “PG-1M (trade name)” (manufactured by Nippon Denshoku Industries Co., Ltd.) having a measuring optical system based on JIS Z8741. Were measured, a measurement angle of 85
Most of the measurements in degrees are less than 5 and at most 10
There was nothing beyond. Therefore, it is determined that the glossiness of the wallpaper is 10 or less, preferably 5 or less.

Based on the above situation, the following experiments were conducted to develop a coating solution for surface protection that can be applied to a print sheet for wallpaper to which ink-jet printing and embossing are applied. Went like so. (Experimental example 1: no protective film) A polyolefin foam layer containing a heating foaming agent was formed on a non-combustible inorganic paper containing wood pulp and aluminum hydroxide as main components, and a porous layer comprising silica and a binder resin was formed on the surface thereof. The wallpaper medium provided with the ink-jet ink receiving layer was heated to about 200 ° C. and foamed, and then embossed to prepare a print sheet for wallpaper.

An image was printed on the print sheet for the wallpaper with pigment ink using an ink jet printer “PJ-3600 (trade name)” (manufactured by Olympus Optical Industrial Co., Ltd.) to prepare a wallpaper. When the performance evaluation test described above was performed on the created wallpaper,
The result as shown in FIG. 1 was obtained.

As shown in FIG. 1, since the preferable standard value of each measurement item is class 4 or higher, none of them has reached the value. In particular, there is a large difference between the abrasion resistance and the stain-proofing property of the water-based felt-tip pens and crayon, and it is judged that great improvement is essential. The fading property is slightly unachievable, and improvement is desired.

Regarding glossiness, commercially available wallpaper 1
Since it is sufficiently lower than the average measured value of the five gloss levels, there is no need to particularly improve. (Experimental example 2) In order to improve the abrasion resistance and stain prevention performance of the wallpaper used in Experimental example 1, it is an emulsion type water-based coating agent which has no adverse effect on the environment and is easy to handle such as cleaning. A coating liquid composed of an acrylic resin widely used as a clear coating agent was applied to the wallpaper surface used in Experimental Example 1.

The coating liquid used was of two types,
"Accel Reset EX-8 (registered trademark)" (manufactured by Nippon Shokubai Co., Ltd.) and "ULS-1700 (trade name)" (manufactured by Yushi Yushi Kogyo Co., Ltd.).

Both can improve the abrasion resistance and stain prevention performance, but both have extremely high gloss as shown in FIG. 2, resulting in an unsuitable finish for wallpaper. (Experimental Example 3) As a result of evaluating many coating agents to obtain a colorless and transparent coating solution capable of obtaining a matte surface finish, it was found that a silicone rubber-based coating agent met the requirements. Among these, as an aqueous emulsion type silicone rubber-based coating agent, "SE1980 Clear (trade name)" (manufactured by Dow Corning Toray Silicone Co., Ltd.)
Was applied to the surface of the wallpaper used in Experimental Example 1. FIG.
Table 2 shows the measurement items and the results. As shown in FIG. 3, the coating with a coating liquid composed of a silicone rubber-based coating agent has improved stain prevention and abrasion resistance while preventing the finished surface from becoming glossy. It can be understood. (Experimental Example 4) In the evaluation of the case where the coating liquid composed of SE1980 clear mentioned in Experimental Example 3 was applied, the wet friction resistance in the wear resistance test did not reach Class 4. In this experiment, attention was paid to this point, and in order to improve this, an acrylic resin coating agent was added to a silicone rubber-based coating agent to prepare a coating liquid, and an experiment was performed using the coating liquid. The above-mentioned SE1980 clear was used as a coating agent for the silicone rubber-based resin, and the above-mentioned Acryset EX-8 was used as a coating agent for the acrylic resin to be added thereto.

As a result of this experiment, 100% by weight of the solid component of SE1980 clear was used to obtain ACRYSET EX-8.
If the coating liquid contains 30 parts by weight or more of the solid component, the wet friction resistance in the abrasion test is 4%.
It was found that the class was reached. However, when the amount of addition of Accreset EX-8 is 60 parts by weight or more, the incident angle 6
The glossiness of 0 ° and 85 ° became 10 or more, and there were signs that the appearance as wallpaper was impaired.

As will be described in the following experiment, when applied to a coating roller type coating apparatus, if the amount of the acrylic resin coating agent added is large, the coating can be performed even if the dilution conditions are adjusted. It was found that it was not possible to prevent the occurrence of coating defects such as unevenness and insufficient coating.

Therefore, a coating liquid in which an acrylic resin coating agent is added in an amount of about 30 to 60 parts by weight with respect to 100 parts by weight of a silicone rubber resin coating agent in terms of a solid content weight ratio. It can be said that this is suitable because the glossiness can be suppressed while improving the abrasion resistance and the wet friction resistance. (Experimental example 5) The coating liquid formulated in each of the above experimental examples did not reach the fourth grade in the evaluation of the fading property. An ultraviolet absorber was added to the coating solution in order to reach a quaternary level of fading, which was not achieved.

The ultraviolet absorber is a water-dispersed, zinc oxide-based ultrafine particle "ZW-143 (trade name)" (Sumitomo Osaka Cement Co., Ltd.) which has excellent stability and safety and also has an antibacterial and deodorizing effect. Was used.

The SE1980 clear is 1 in terms of solids weight ratio.
Parts by weight, ACRYSET EX-8 is a coating liquid comprising a mixed resin in a ratio of 0.4 parts by weight.
When 4 parts by weight of -143 was added, a quaternary grade was obtained as the evaluation of discoloration.

When the addition amount is further increased, and the addition amount exceeds 8 parts by weight, the coating liquid becomes cloudy in the embossed concave portion where the coating liquid is thickly applied, and the printed image cannot be seen. It will be difficult.

Therefore, if the discoloration evaluation is to be simply improved to quaternary or higher, the coating liquid having a total resin solid content of 100 parts by weight is required to contain not less than 4 parts by weight of an ultraviolet absorber composed of zinc oxide-based ultrafine particles. By using the coating liquid to which is added, the evaluation of the fading property can be improved.

Further, in order to make the printed image more visible, an ultraviolet absorber to be added is used.
A coating solution having less than parts by weight is desirable. (Experimental Example 6) In order to efficiently apply the coating liquid thus improved, the suitability of a coating apparatus of a coating roller type was determined. Coating equipment is "Double Star (product name)"
(Manufactured by Kyokuto Sanki Co., Ltd.) with a diameter of 90 mm and a speed of 60 rpm
m and has a groove for hanging a belt for running a belt for guiding.
They are provided at 0 cm intervals.

The preferred coating amount is 5 to 10 μm in dry film thickness.
m. When the thickness is smaller than this, the effect obtained by the coating process is insufficient. Also, if it is too thick, it takes too much time to dry, the embossed pattern will be crushed, and depending on how the wallpaper is placed during drying, coating unevenness due to the dripping phenomenon of the coating liquid will occur. Also, the hardening of the entire wallpaper after the coating liquid has dried causes adverse effects such as impairment of workability later. Another problem is that the consumption of the coating liquid increases and the cost increases.

The coating agent SE198 described in Experimental Example 3 above.
Water-based coating liquid 1000 using 0 clear
Coating liquids were prepared in which the dilution ratio was changed in the range of 50 g to 150 g of the resin solid content in cc, and the finished state of coating in each of the above coating devices was examined.

As a result, when the mixing amount is less than 80 g, the coating liquid is not sufficiently pumped up on the application roller due to the low viscosity of the coating liquid, so that the coating liquid becomes uneven on the wallpaper surface and is applied. Coating defects such as have appeared.

When the amount of the coating liquid is more than 120 g, the excessive amount of the coating liquid adheres to the wallpaper and the drying is slowed down. It has been found that coating unevenness due to this starts to occur.

Therefore, in order to adapt a coating liquid using the SE1980 clear to a coating apparatus, 1000 c
It is preferable that the coating liquid of c contains the resin solid content in the range of 80 g to 120 g. (Experimental Example 7) Using the same coating apparatus as in Experimental Example 6, an experiment was performed to determine an appropriate dilution concentration of the coating liquid used in Experimental Example 4. The coating liquid is obtained by adding an acrylic resin coating agent ACRYSET EX-8 at a solid content weight ratio of 0.4 to a solid content weight ratio of a silicone rubber coating agent SE1980 clear.

The formulated coating liquid 1000c
Coating liquids were prepared by changing the dilution ratio of the above resin in the range of 80 g to 200 g in terms of the solid content of the resin, and each was applied to ink jet printed wallpaper using a coating apparatus.

In the case of a coating liquid having a resin solid content of 120 g or less, the amount of the coating liquid adhering to the surface of the coating roller of the coating apparatus is too small, and streak-like coating unevenness occurs. Further, when the weight of the resin solids exceeds about 160 g, the drying time of the coating liquid becomes longer, and if the coating liquid is left in an undried state in an inclined state, a dripping phenomenon in which the coating liquid flows out occurs.

Therefore, in order to adapt the coating liquid used in Experimental Example 4 to a coating apparatus, it is preferable that the weight of the resin solids is contained in the range of 120 g to 160 g in the coating liquid of 1000 cc. is there.

As described above, the coating liquid for providing effective surface protection and the example of the formulation of the coating liquid suitable for a coating apparatus have been described for embossed and ink-jet printed wallpaper. Inkjet printed interior sheet with flat surface without embossing, inkjet printed interior sheet based on vinyl chloride resin film with normal temperature adhesive glue on the back, and inkjet ink receiving layer on the surface The coating liquid described above can be applied to such cloth-like wallpaper.

In the case of an ink-jet print sheet, it has a surface property that easily absorbs ink, so that it is familiar with the coating liquid of the present invention. Even so, the coating liquid of the present invention can be effectively applied as long as it has a surface having a property of easily absorbing an aqueous solution.

[0051]

As described above, according to the coating liquid of the present invention, a matte surface with extremely low gloss required for wall covering materials and the like can be obtained, and a surface protection having high friction fastness and stain prevention performance can be obtained. A membrane can be obtained.

Further, it is well suited to a spin coating roller type coating apparatus, and a surface protective film having an appropriate thickness and no unevenness can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing each evaluation result in Experimental Example 1.

FIG. 2 is a diagram showing evaluation results regarding glossiness in Experimental Example 2.

FIG. 3 is a diagram showing evaluation results in Experimental Example 3.

Claims (5)

[Claims] 1. A coating liquid applied to a surface of an ink-jet print sheet or the like having a porous ink-jet ink receiving layer on the surface thereof, wherein the coating liquid is a solid content weight of a resin component contained in an aqueous emulsion solution. The ratio is silicone rubber-based resin 1
A coating solution for protecting a printed sheet surface, wherein the acrylic resin is formulated to be 30 to 60 parts by weight with respect to 00 parts by weight. 2. The coating solution for protecting a print sheet surface according to claim 1, wherein 4 parts by weight of an ultraviolet absorber composed of ultrafine zinc oxide is added to 100 parts by weight of the total solid content of the resin component. 3. The print sheet surface protective coating according to claim 1, wherein 4 to 8 parts by weight of an ultraviolet absorber made of ultrafine zinc oxide is added to 100 parts by weight of the total solid content of the resin component. liquid. 4. The print sheet surface protective coating liquid according to claim 1, wherein the total solid content of the resin component contained in the 1000 cc coating liquid is 120 to 160 g. 5. A coating liquid for coating a surface of an ink-jet print sheet or the like having a porous ink-jet ink receiving layer on the surface thereof, wherein a silicone rubber-based resin is added to an aqueous emulsion solution, and the coating liquid is 1000 cc.
Wherein the total solid content of the resin component contained in the coating liquid is 80 to 120 g.