WO2006057064A1

WO2006057064A1 - Sheet of high whiteness degree

Info

Publication number: WO2006057064A1
Application number: PCT/JP2004/017739
Authority: WO
Inventors: Taiji Ohashi; Ming Tsung Tsai; Heri Susanto
Original assignee: Pt. Pabrik Kertas Tjiwi Kimia Tbk.
Priority date: 2004-11-29
Filing date: 2004-11-29
Publication date: 2006-06-01
Also published as: CN101068982A; JPWO2006057064A1

Abstract

A sheet of high whiteness degree comprising a paper having a fluorescent whitener incorporated therein and, superimposed on the surface thereof, a layer of coating film water-soluble resin or a layer of a mixture of coating film water-soluble resin and another water-soluble resin, thereby having a whiteness degree of 92 to 98%. The amount of coating film water-soluble resin used in the sheet of high whiteness degree is preferably in the range of 0.6 to 5 g/m2 with respect to both major surfaces of the paper. Further, it is preferred that the coating film water-soluble resin be at least one member selected from among polyvinyl alcohol, polyacrylamide and carboxymethylcellulose. Thus, there can be obtained a sheet of high whiteness degree that even when a hand is brought into contact with the surface of a sheet of high whiteness degree having a fluorescent whitener incorporated therein, is free from sticking of the fluorescent whitener to the hand, and that can be used in both not only black and white but also color electrophotographic transfer and inkjet recording.

Description

Specification

High whiteness paper

Technical field

The present invention relates to a high whiteness paper that can be used for both color electrophotographic transfer and ink jet recording as well as black and white, and in particular, touches the surface of a high whiteness paper internally containing a fluorescent brightening agent. The present invention relates to a high-whiteness paper that can be used for both electrophotographic transfer and ink-jet recording without having a fluorescent brightening agent.

Background art

[0002] Since the first electrophotographic transfer paper (hereinafter referred to as “PPC paper”) was produced in Japan in 1972, the production volume of this PPC paper has been increasing year by year. Currently, information paper can be used as inkjet recording paper, thermal transfer paper, and small format offset paper if it can be applied to the most demanding PPC paper. It is clearly stated that the part can be used as paper as above.

By the way, most of images formed on paper by a printing press, an electrophotographic transfer method, an ink jet recording method, etc. are full-color images and monochrome images. The power of traditional full-color image printing has been mainly offset printing. In the past few years, the ratio of full-color images has increased rapidly in electrophotographic transfer systems and ink-jet recording systems, which used to be monochrome images. .

[0004] Currently, the medium that forms the full-color image by offset printing is overwhelmingly the medium, so-called coated paper with a whiteness of 85% -95% to express the beauty and clarity of the image. Art paper is commonly used. On the other hand, in the electrophotographic transfer method and the ink jet recording method mainly composed of monochrome images, generally non-coated paper with a whiteness of 70% -85% is a so-called PPC paper or a paper with a slightly smooth surface treated. It has been used. However, the demand for full color is also increasing in the electrophotographic transfer method and the ink jet recording method, and the beauty and clarity of the image has been demanded as in the case of offset printing. For this purpose, it is essential to increase the whiteness of the paper. [0005] On the other hand, in order to increase the whiteness of paper, a method using a raw material with high whiteness, that is, a high whiteness pulp filler (calcium carbonate, talc, kaolin, etc.), and a fluorescent whitening agent are added. And a method of adding both of them. Among them, the technology of adding fluorescent whitening agent to pulp to increase the whiteness of paper and using it as part of the surface sizing agent has been known for several decades.

[0006] For example, in Patent Document 1 below, for the purpose of obtaining an electrophotographic transfer paper in which the color tone of an image transferred by a copying machine can accurately reproduce the color tone of an original, starch and a fluorescent brightening agent are formed on the surface of the base paper. An invention of an electrophotographic transfer paper having a whiteness of 81.8% -86.5% coated with is disclosed. Patent Documents 2 to 5 below disclose inventions in which a fluorescent whitening agent is contained in the image receiving layer of a color child photographic transfer paper so as to have a specific gloss and hue. Furthermore, in Patent Document 6 below, for the purpose of obtaining a coated paper for offset rotary printing with little generation of creases and prestars and good printing finish, pigments and polyvinyl alcohol having a specific degree of chain are formed on the surface of the base paper. (Hereinafter referred to as “PVA”) is applied to the front and back surfaces, and at least one of these layers contains a wetting agent, and the pore diameter and the pore diameter density of the pigment coating layer are within a predetermined range. The invention maintained in the above is disclosed.

[0007] In order to produce high-white pulp, generally, a variety of chips with few colored components are used, and chlorine bleach such as dioxychlorine and hypochlorite are used for pulp bleaching. It is necessary to use a large amount of. Thus, using a large amount of chlorine bleach in the pulp bleaching process is not preferable from the viewpoint of environmental pollution. In addition, the cost of selecting grape seeds and the bleaching process is considerably high, and at the same time, increasing the bleaching process lowers the yield of pulp and has a great economic impact.

[0008] On the other hand, paper coated with a fluorescent brightening agent added to pulp or added to a sizing agent coated on the paper surface is economical and has a beautiful and clear color image. Although it is excellent in terms of size, the use of fluorescent brighteners on paper is regulated by the Food Sanitation Law, and when a certain amount of fluorescent brightener comes into contact with the human body, it may cause eczema. It has been pointed out.

[0009] Furthermore, paper added with a fluorescent whitening agent has a greater decrease in whiteness when exposed to sunlight or electric light even at the same whiteness compared to paper using high whiteness pulp. U There are drawbacks.

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-209204

Patent Document 2: JP 2001-13710

Patent Document 3: Japanese Patent Laid-Open No. 2001-42559

Patent Document 4: Japanese Patent Laid-Open No. 2001-209204

Patent Document 5: Japanese Unexamined Patent Publication No. 2003-322990

Patent Document 6: Japanese Patent Application Laid-Open No. 2004-27411

Disclosure of the invention

Problems to be solved by the invention

[0011] Therefore, in order to meet the demand for full color in the electrophotographic transfer system and the ink jet recording system, in order to obtain a paper with high whiteness, considering the problem of environmental pollution and the economy, the fluorescent whitening agent is applied to the paper. However, it is necessary to solve the problem of contact with the human body when using a fluorescent brightener as described above and to suppress the decrease in whiteness due to light. .

[0012] The inventor of the present application has conducted various experiments in order to solve the problems in the case of using the above-described conventional fluorescent whitening agent, and as a result, the paper is obtained by adding the fluorescent whitening agent to the pulp. By applying a water-soluble resin such as PVA or polyacrylamide, which is transparent and film-forming by a size press in the papermaking process, alone or mixed with starch, etc. As a result, the present inventors have found that the fluorescent whitening agent in the paper is less likely to come into direct contact with the surface of the human body and can suppress the decrease in whiteness due to light. is there.

[0013] That is, the present invention maintains the advantages of whiteness improvement and economic efficiency due to the fluorescent whitening agent-added glass, reduces the possibility of adverse effects on the human body at the time of contact, which is a weak point, and reduces the whiteness due to light. The objective is to provide high-whiteness paper that is suitable for electrophotographic transfer systems and ink jet recording systems.

Means for solving the problem

[0014] The above object of the present invention can be achieved by the following configurations. That is, the invention of the high whiteness paper according to claim 1 is a layer comprising a film-form water-soluble resin on the surface of a paper in which a fluorescent brightening agent is internally added. Alternatively, it is a high whiteness paper having a whiteness of 92% to 98%, which is provided with a layer comprising a mixture of a film-form water-soluble resin and another water-soluble resin.

Note that “whiteness” in the present invention is a measured value based on ISO 2470. If the whiteness is 92% or more, high whiteness paper with color image printing characteristics equivalent to or better than general coated paper and art paper can be obtained, but if it exceeds 98%, the whiteness is reduced by light. Is unfavorable because of the increase.

[0016] The pulp that can be used in the high whiteness paper of the present invention is not limited to the production method or type thereof, and is a well-known pulp that is widely used, for example, hardwood pulp, softwood cocoon, etc. Pulp, waste paper pulp, blended pulp with different blending ratio of waste paper pulp, etc. can be used. In addition, as fillers that can be used for the high whiteness paper of the present invention, known materials such as heavy calcium carbonate, light calcium carbonate, talc, kaolin, clay, amorphous silica, titanium dioxide and titanium dioxide are used. Can do. Further, as a sizing agent that can be used for the high whiteness paper of the present invention, in the case of neutral papermaking, alkyl ketene dimer, alkaryl succinic anhydride, neutral sizing agent, etc. can be used. Rosin sizing agent may be used for papermaking

[0017] Further, examples of the fluorescent whitening agent that can be used in the high whiteness paper of the present invention include well-known carbostyryl compounds, coumarin compounds, stilbene compounds, naphthalimide compounds, biphenyl compounds, Benzoxazoline compounds, pyrazoline compounds, diaminostil benzisulfonic acid derivatives, imidazole derivatives, coumarin derivatives, triazole derivatives, force rubazole derivatives, pyridine derivatives, naphthalic acid derivatives, imidazolone derivatives, etc. Preference is given to acid derivatives, imidazole derivatives, coumarin derivatives, triazole derivatives, force rubazole derivatives, imidazolone derivatives, stilbene compounds, benzoxazoline compounds, and so on.

[0018] In the high whiteness paper of the present invention, well-known auxiliaries blended in normal paper according to the application, for example, a yield improver, a drainage improver, a dispersant, a disinfectant for additive chemicals. A foaming agent, an antistatic agent, a conductive treatment agent, a lubricant, a pH adjuster, a mold release agent, a flow modifier, a water resistant agent, a paper strength improver, and the like may be appropriately selected and added.

[0019] In such an embodiment, the coating amount of the water-soluble film-forming resin is 0.6 gZm ² or more on both sides. It is preferably 5 gZm ² or less. If the coating amount of the water-soluble resinous film is less than 0.6 mg / m 2, the fluorescent whitening agent is not used when the paper comes into contact with the human body, even though the decrease in whiteness due to light does not decrease so much. This is not preferable because the rate of adhesion to the human body surface starts to increase. In addition, the upper limit is not critical from the viewpoint of reduction in whiteness due to light and adhesion of the fluorescent whitening agent to the human body, but when the coating amount of the film-soluble water-soluble resin exceeds 5 gZm ^2. In particular, when it is used for electrophotographic transfer paper, the curling characteristics after fixing and copying are deteriorated, which is not preferable. Therefore, 5 gZm ² or less is preferable.

[0020] Further, for such an embodiment, it is preferable that the film-forming water-soluble resin is at least one selected from PVA, polyacrylamide, and carboxymethyl cellulose. This film-soluble water-soluble rosin can be used alone or in combination with a known paper strength enhancer such as various starches.

[0021] In addition, the high whiteness paper of this aspect can be used as a paper for electrophotographic transfer and ink jet recording.

The invention's effect

[0022] The present invention has the above-described configuration, so that the whitening degree is high and the fluorescent whitening agent is used as will be described in detail while comparing the following Examples and Comparative Examples. Nevertheless, even when the paper comes into contact with the human body, a high whiteness paper can be obtained in which the fluorescent whitening agent does not adhere to the human body and can suppress a decrease in whiteness due to light.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best mode for carrying out the present invention will be described while comparing the examples and the comparative examples. The examples shown below are equally applicable to other embodiments included in the scope of claims, which are not intended to limit the present invention. Further, the content ratio in the following means mass% (equivalent to% by weight) unless otherwise specified.

First, as Example 1, the following raw material composition was used to make a neutral papermaking at a papermaking speed of 700 mZ using a long net paper machine with a papermaking width of 3.7 m by a conventional method. A size press was applied so that the coating amount was 1.5 gZm ^{2 on} both sides. 1 paper was manufactured.

[0025] Raw material formulation>

Pulp composition: Hardwood bleached pulp 90%

10% softwood bleached pulp

Filler: Precipitated calcium carbonate 10% (vs. paper)

Sizing agent: Alkyl ketene dimer 0.09% (for paper)

Optical brightener: Tinopal ABP (trade name, liquid) 0.1% (vs. paper)

(Diaminostilbene sulfone derivative)

Size press chemical compound>

PVA: 10%

Oxidized corn starch: 90%

The obtained paper of Example 1 had a basis weight of 70 gZm ² and a whiteness of 94.5%.

[0026] The paper of Example 1 was subjected to a fluorescent whitening agent peeling test and a light deterioration test by the evaluation methods described below. The results are summarized in Table 1. This evaluation method is common to all other examples and comparative examples.

[0027] (1) Fluorescent whitening agent peeling test

The surface of the sample is rubbed twice with a filter paper (Advantech Toyo Qualitative Filter Paper No. 1) with a strength that does not damage the sample by hand, and the contact surface of the filter paper with the sample is UV light (TOKI JAPAN, F20T1OBLB (trade name)) was irradiated and the presence or absence of fluorescence was visually checked.

The results were evaluated in the following three stages.

A: None or almost none

B: Some

C: Obviously

When actually handling paper, it is unlikely that the frictional papers will be rubbed strongly as in this test, so at the levels of A and B, the fluorescent whitening agent is caused by contact between the paper and the human body. It is judged that there is no influence on

[0028] (2) Whiteness degradation test by light The whiteness (based on ISO 2470) before and after irradiating with sunlight through the window glass for 8 hours was measured, and the difference was defined as the degree of whiteness deterioration. The degree of whiteness degradation should be low. The practical level depends on the application, so this test was limited to the relative value of each sample.

[0029] Next, as Examples 2-4 and Comparative Example 1, the amount of fluorescent whitening agent added was 0.1% and the amount of size press chemical applied was a constant value of 1.5 gZm ² and PVA of size press chemical was used. : Oxidized corn starch is 0: 100 (Comparative Example 1), 30: 70 (Example 2), 50: 50 (Example 3), 100: 0 (Example 4). In the same manner, whiteness, fluorescent whitening agent peeling test, and whiteness deterioration degree were measured. The results are shown in Table 1 together with the results of Example 1.

[0030] [Table 1]

[0031] The results shown in Table 1 reveal the following. In other words, when the optical brightener internal addition amount is 0.1% and the size press chemical coating amount is a constant value of 1.5 gZm ² , the content of PVA and acid corn starch in the size press chemical is white. The degree of whiteness deterioration gradually decreases in proportion to the increase in the PVA content ratio, and the results of the fluorescent whitening agent peeling test also improve. Therefore, the results shown in Table 1 indicate that when the amount of fluorescent brightener added is 0.1% —fixed and the amount of size press chemical applied is 1.5 gZm ² —fixed, the result of the peel test of the fluorescent brightener Therefore, it can be seen that good results can be obtained if the PVA content in the size press chemical is 10% or more.

Next, the optical brightener internal addition amount was 0.1% and the size press chemical PVA: Toch = 30: 70, and the application amount of size press chemical is OgZm ² (Comparative Example 2), 0.5 g / m ² (Comparative Example 3), 0.6 g / m ² (Example 5) ), 2. Og / m ² (Example 6), and PVA: oxidized corn starch = 10: 90 (Example 7) when the applied amount of size press chemical is 0.6 g / m ² Each paper was prepared, and the whiteness, the fluorescent whitening agent peeling test, and the whiteness deterioration degree test were performed in the same manner as in Example 1 for each paper. The results are shown in Table 2 together with the results of Example 2.

[0033] [Table 2]

[0034] From the results in Table 2, the following can be understood. That is, from the results of Comparative Examples 2 and 3, Examples 5, 2 and 6, the presence or absence of the application of the size press chemical does not affect the whiteness, but the amount of fluorescent brightener added is 0.1% and the size. When the press chemical PVA: oxidized corn starch = 30:70, the degree of whiteness deterioration decreases as the amount of size press chemical applied increases, and the results of the fluorescent whitening agent peeling test are also good.

[0035] When the amount of fluorescent brightener added is 0.1% and the size press chemical coating amount is constant at 0.6 gZm ² , the size press chemical PVA: acid corn starch = 30:70 In both cases (Example 5) and 10:90 (Example 7), there is no substantial difference between the degree of whiteness deterioration and the results of the test of the optical brightener peeling test. Therefore, the results in Table 2 indicate that the degree of whiteness deterioration and the fluorescent brightening agent can be obtained if the amount of size press chemical applied is 0.6 gZm ² or more and the PVA content in the size press chemical is 10% or more. It turns out that a peeling test result becomes favorable. In this example, the coating amount in the size press chemicals was tested up to 2. Og / m ² , but when the coating amount was too large, especially when used for electrophotographic transfer paper, after fixing and copying. Since the curl characteristics of the steel deteriorate, 5. OgZm ² should be kept below.

Furthermore, the size press chemical PVA: oxidized corn starch = 30:70, the amount of size press chemical applied was a constant value of 1.5 gZm ^{2 and} the amount of fluorescent brightener added was 0% (Comparative Example 4). Changed to 05% (Example 8), 0.2% (Example 9), 0.3% (Example 10), and size press chemical PVA: acid corn starch = 30:70, fluorescent whitening When the amount of additive added is 0.2% and the application amount of size press chemical is 0.5 gZm ² , each paper is prepared (Comparative Example 5), and each paper is white as in Example 1. , Fluorescent whitening agent peeling test and whiteness deterioration test. The results are shown in Table 3 together with the results of Example 2.

[0037] [Table 3]

[0038] From the results in Table 3, the following can be seen. That is, in Comparative Example 4 in which the addition amount of the optical brightener is 0%, the whiteness degradation due to light is the smallest, but the whiteness is the smallest at 85%. In contrast, when the amount of fluorescent whitening agent added was 0.05% (Example 8), the whiteness became 92%, and as the amount of fluorescent whitening agent added increased, the whiteness also increased and the fluorescent whitening amount increased. The whitening additive amount of whitening agent is 0.3% (Example 10) and the whiteness reaches 98%, but the degree of whiteness deterioration also increases. Therefore, when considered together with the results of the optical brightener peeling test, when the size press chemical PVA: oxidized corn starch = 30:70 and the size press chemical coating amount is a constant value of 1.5 gZm ² , the optical brightener It can be seen that the amount of internal addition is preferably 0.05% or more and 0.3% or less. On the other hand, the results of the fluorescent whitening agent peeling test are better as the amount of fluorescent whitening agent added is lower, since the amount of size press chemical applied is the same. In addition, when the amount of fluorescent whitening agent added is 0.2%, size press chemical PVA: oxidized corn starch = 30:70, and the amount of size press chemical applied is as small as 0.5 g / m ² (comparison) In Example 5), the whiteness deterioration due to light is worse than that in Example 9 where the amount of the optical brightener added is the same as that of Example 10 where the amount of the optical brightener added is larger. In addition, the results of the optical brightener peeling test are out of the acceptable range. Then, PVA size press chemicals fluorescent whitening agent in addition amount is 2% 0. Oxidation cornstarch = 30: in the case of 70, the coating weight of the size press agent product exceeds at least 0.5 5GZm ² I understand that it is necessary.

Claims

The scope of the claims

[1] A white layer in which a layer made of a film-soluble water-soluble resin or a mixture of a film-soluble water-soluble resin and another water-soluble resin is provided on the surface of a paper internally incorporated with a fluorescent brightener 92% — 98% high whiteness paper.

[2] The high-whiteness paper according to [1], wherein the coating amount of the water-soluble film-forming resin is 0.6 g / m ² or more and 5 g / m ² or less on both sides.

[3] The film-forming water-soluble rosin is at least one selected from polyvinyl alcohol, polyacrylamide, and carboxymethylcellulose strength.

High whiteness paper as described in 2.

[4] The high whiteness paper according to any one of claims 1 to 3, wherein the paper is an electrophotographic transfer and ink jet recording paper.