JPH02169796A - Specific paper - Google Patents

Abstract

PURPOSE:To obtain specific paper having both sides usable properly, comprising one side with high sizing degree and high smoothness and the other with low sizing degree and low smoothness, containing a specific amount of filler in paper. CONSTITUTION:A pulp raw material such as bleached kraft pulp of broadleaf tree is blended with >=5.0% filler (e.g. ground limestone), mixed with a sizing agent (e.g. alkyl ketene dimer), a fixing agent and an enhancer (e.g. oxidized starch) as inner addition agents in order to change sizing degree of two sides of paper, made into paper and further coated with the sizing agent and the enhancer as outer addition agents by changing blending and concentration by gate rolls, etc. To make difference in smoothness, the side with low sizing degree is treated with a netlike structure and wet paper by press, etc., to give the aimed specific paper comprising one side having >=4.0 class sizing degree and high smoothness for pen-written use and the other having <=3.0 class sizing degree and low smoothness for pen-written use.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is a special paper, more specifically a postcard paper having one side suitable for offset and gravure printing and the other side suitable for letterpress printing.

This paper relates to special paper suitable for card stock.

[Prior art] As is well known, postcard paper and card paper have a basis weight of 100.
So-called high-quality paper of g/m2 or higher is used.

[Problems to be solved by the present invention] Conventional paper has the same size on both sides of the paper so that writing with a pen does not bleed, so there is no problem with offset, gravure printing, or writing with a pen. However, when using letterpress printing or block printing, there were problems such as poor penetration of ink 2 paint.

In addition, Japanese paper is sometimes used as postcard paper or card paper, but in this case, there is no problem with the permeability of ink and paint when printing with letterpress printing, but there are problems such as ink bleeding when writing with a pen. There was.

The present invention solves the above-mentioned problems with conventional postcard paper and card paper, and is a special paper that has both sides: one surface that is suitable for offset printing, gravure printing, and pen writing, and the other surface that is excellent for letterpress printing and printmaking. The purpose is to provide the following.

[Means for Solving the Problems] The present invention provides special paper containing 5.0% or more of filler, which has a pen writing size degree of grade 4.0 or higher on one side of the paper and a smoothness of the paper. It is a special paper that has a high surface, the pen writing size on the opposite side is 3.0 grade or less, and the smoothness is low.

Here, the pen writing size is J, TAPPI, paper pulp test method No. 12-76, and the smoothness is TAPPI Standard T 479. am-81
This is due to

Next, the special paper of the present invention will be explained in more detail.

The valve used is the conventionally used LBHP (
Hardwood bleached kraft valve), NBKP (softwood bleached kraft valve), BSP (bleached sulfide valve), GP (ground wood valve), TMP (thermomechanical valve), CTMP (chemical thermomechanical valve), RGP (refiner ground wood valve), etc. Single raw material or 2fff of these
A mixed raw material of i or more can be used, and it is also possible to mix and use synthetic fibers such as rayon, polyethylene, and polypropylene.

In addition, fillers are usually added to improve the opacity of paper, but fillers that can be used include heavy calcium carbonate, light calcium carbonate, talc, clay, and titanium dioxide. In order to fully exhibit the subsequent opacity, it is necessary to add 5.0% or more as a filler.

Although the paper of the present invention contains 5.0% or more of filler, it is further desirable that the paper of the present invention has a p)I of 7.0 or more and a basis weight of 100 g/m2 or more.

The present invention is particularly excellent as postcard paper and card paper, but postcard paper and card paper are desired to be stored for a long period of time, and the p)l of the paper is 7.0 due to the neutral paper making that does not cause storage deterioration.
It is necessary to do the above.

As chemicals for imparting neutral sizing, both known alkyl ketene dimer (AKD) and alkenyl succinic anhydride (ASA) can be used.

The methods for adding sizing agents include the internal addition method in which the sizing agent and fixing agent are added to the paper stock material and fixed, the external addition method in which the sizing agent and fixing agent are applied to the surface of the paper, or the combination of the internal addition method and the external addition method. It is also possible. In order to provide a difference in size between the front and back sides of the present invention, it is desirable to use both the internal addition method and the external addition method. That is, by changing the formulation and concentration of the externally added sizing agent between the front and back sides, it is possible to intentionally obtain double-sided sizing properties. The external addition method is the well-known combination of rolls and blades.

A coating device such as a gate roll may be used, or two single-sided coating machines may be installed, each coating a different surface size.

In addition, paper surface strength and paper interlaminar strength are also important factors from the viewpoint of suitability for use such as printability, but in order to improve paper strength, well-known oxidized starch, cationized starch, polyvinyl alcohol (PVA), etc. It is also possible to add various chemicals by an internal addition method or an external addition method, or to use a combination of an internal addition method and an external addition method.

In addition, as a means to make the smoothness of the lower side of the paper lower than the smoothness of the higher side, the size degree of the wire side of the paper, which is generally lower in smoothness than the felt side of the paper, is lowered. This is possible. More effectively, smoothness can be improved by bringing a net-like structure such as felt or canvas into close contact with wet paper using a press or the like.

In addition, it is also possible to reduce the smoothness by using a dandy roll, an embossing roll, or the like.

Also, the wire side of the paper has a higher size than the felt side,
In order to achieve high smoothness, the wire side is usually less smooth than the felt side, so in order to produce the special paper of the present invention, the smoothness is improved by bringing the network structure into close contact with the felt side of the paper. It is also possible to reduce the smoothness by lowering the smoothness or by using the dandy roll, embossing roll, or the like.

Furthermore, in order to increase the smoothness of only the wire surface, only the wire surface may be passed through a single-sided smoothing machine such as a single-sided gloss calender.

[Example] Hereinafter, the present invention will be specifically explained using Examples and Comparative Examples.

Example 1 LBKP as a valve raw material: A papermaking raw material with a freeness of 550 ml at a blending ratio of 95:5 and 0.15% of an AKD-based sizing agent (SP ni-902 manufactured by Arakawa Chemical Co., Ltd.) as an internal sizing agent. (for pulp), add light calcium carbonate as a filler to the pulp so that the ash content of the paper is approximately 10%, and then add 0.5% of cationized starch as a paper strength enhancer (for pulp) before making paper. Then, the felt base fabric side is brought into close contact with the wet paper using a dehydration press, texture-like unevenness is created on the wire side of the paper web, and after drying with a hair dryer,
A 5.0% solution of oxidized starch was applied to the wire surface using a gate roll coating device, and oxidized starch (P) was applied to the felt surface.
VA: Sizing agent (SPK-902.

A 2% solution (manufactured by Arayo Kagaku Co., Ltd.) mixed in a ratio of 90:5:5 was applied, and after drying, it was calendered to obtain special paper.

Example 2 Paper was made under the same conditions as Example 1 for pulp composition and internal chemicals,
On the dehydration wire, a mesh pattern is applied to the felt surface of the paper web using a mesh-like dandy roll, and after pre-drying with a dryer, 5.0% oxidized starch is applied to the felt surface using a gate roll.
A 2.0% solution containing oxidized starch: PVA: sizing agent = 90; 5:5 was applied to the wire surface, and after drying, it was calendered to obtain special paper.

Table 1 shows the results of comparing the paper quality and printability of Example 1, Example 2, and Comparative Example (commercially available postcard paper).

Evaluation method (1) Pen writing size: J, TAPPl, r Paper pulp test method, No. 12-7J.

(2) Smoothness: TAPPl, standard, 7
479om-81, by Beck method.

(3) Paper p)l: J, TAPPl, r Paper pulp test method.

No. 6-75 J.

(4) Offset printing suitability: Ink receptivity of the printed surface when printed under the same conditions using an RI printing tester.

Visually judge the texture, etc.

◎: Good, O: Average, ×: Bad (5) Suitability for print printing: Visually judge the daytime absorbency and condition of the printed surface when printing a print using India ink.

◎: Good, O: Average, x: Bad As shown in Table 1, the offset printing suitability of the commercial product shown in the comparative example was fair on both sides, but the printability was poor on both sides.

On the other hand, the special paper according to the present invention has both excellent suitability for offset printing and excellent suitability for printmaking, and has extremely excellent properties as postcard paper and card paper.

The surface with excellent printability and low pen-writing size has unevenness, and the low smoothness has the effect of imparting depth and three-dimensionality to the printing surface, and from this point of view as well, the special paper of the present invention is extremely suitable for printing. It can be said that it is excellent.

[Effects of the Invention] As described above, the present invention has one side of the paper with a high degree of size,
By making the surface with high smoothness and the opposite surface with low size and low smoothness, one surface is suitable for offset and gravure printing, and the other surface is suitable for letterpress printing. The paper can be made into a surface suitable for printing prints, etc., and can be used on both sides.

Claims (1)

[Claims] For special paper containing 5.0% or more filler, one side of the paper is said to have a pen writing size of grade 4.0 or higher and is highly smooth, and the other side is said to be a surface that is highly smooth. A special paper characterized by a writing size of grade 3.0 or lower and a low smoothness.