JPH07229085A - Wood-free paper - Google Patents

Abstract

PURPOSE:To obtain a wood-free paper or a wood-free coating base paper having excellent smoothness, softness, cushioning property and whiteness. CONSTITUTION:This wood-free paper contains <=5wt.% of mechanical pulp and is treated with a size pressing agent. The pulp to be used in the paper-making process contains 10-50wt.% of dissolving pulp (JIS-P2701) having a plastic deformation ratio of >=75% and the size pressing agent is composed mainly of 100 pts.wt. of a polyvinyl alcohol and 5-25 pts.wt. of glycerol. The paper is especially useful as a coating base paper for gravure printing paper and gravure printing coated paper having excellent dot reproduction or as a wood- free paper for recording and copying having excellent recording and copying suitability or its coating base paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high quality paper for printing or copying for printer recording which is excellent in smoothness, a soft cushioning property, and whiteness, and a high quality coated base paper. The present invention relates to a high-quality paper and a high-quality coated base paper for gravure printing, which has less dot reproducibility and for copying for printer recording, which has excellent recording suitability.

[0002]

2. Description of the Related Art High-quality papers and high-quality coated papers which are excellent in smoothness, flexible cushioning property and whiteness have been demanded as various printing papers, recording papers and copying papers. For example,
As printing paper, high-quality full-color gravure printing paper, etc., and as recording paper, self-coloring type thermal recording,
Continued research and development of paper with properties superior to general high-quality paper and coated paper as paper suitable for recording methods such as melt-type thermal transfer recording, capsule-type pressure-sensitive copying recording, inkjet recording, and electrophotographic copying recording. ing.

Gravure printing is widely used because it has good reproducibility from the highlight portion to the intermediate portion and enables beautiful printing. However, since gravure printing is a printing method that transfers gravure ink directly from the concave surface of the plate cylinder roll to the paper surface in both sheet printing and web-fed rotary printing, misdots and halftone dot reproducibility are likely to occur, and Quality characteristics such as smoothness and soft cushioning may cause serious defects that hinder the printing effect. Visualization, colorization, high quality, and thinning of printed materials are progressing,
There is an increasing demand for improvement in high-quality paper for gravure printing or coated paper for gravure printing to have high smoothness, high cushioning property, and high whiteness.

The misdots generated in gravure printing are a phenomenon in which the ink of the intaglio plate is not sufficiently transferred to the paper surface to cause defects, and the paper surface is smooth and has sufficient smoothness even under pressure conditions during gravure printing. The lack of layer cushioning is believed to be the main cause. Therefore, printing paper, coated base paper,
Various improvements have been proposed from the viewpoint of papermaking technology such as coating compositions and the like, and from the viewpoint of printing technology such as ink and plate making, but satisfactory improvement effects have not yet been obtained, and further research and development has been requested. It is the present situation.

In addition, various recording and copying methods have been widely used, and full-color recording and copying are realized.
As high-speed recording, smoothness of uncoated paper or coated base paper as paper with even better recording and copying suitability,
Flexible cushioning and whiteness are required.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-quality paper and a high-quality coated base paper which are excellent in smoothness, flexible cushioning property and whiteness, and particularly, to prevent misdots in gravure printing. To provide a gravure printing paper and a coating base paper for gravure printing coated paper, which does not occur and has good dot reproducibility. Further, there is provided a high-quality paper for recording copy or a base paper coated with the same, which has excellent suitability for recording and copying.

[0007]

DISCLOSURE OF THE INVENTION According to the present invention, in a high-quality paper treated with a size press agent at a mechanical pulp content of 5% by weight or less of the total pulp, a plastic deformation rate of 75% or more as a pulp type Pulp (JIS-P270
The content of 1) is 10 to 50% by weight based on the total pulp, and the size press agent is the main component of polyvinyl alcohol 100.
It is a high-quality paper characterized by containing 5 to 25 parts by weight of glycerin with respect to parts by weight.

It is more preferable that the polyvinyl alcohol is a completely saponified polyvinyl alcohol having a polymerization degree of 1,000 to 2,000.

It is a preferred embodiment that the high-quality paper is a gravure printing paper or a gravure printing coated base paper.

[0010]

As a preferred embodiment of the present invention, in gravure printing paper and coated paper for gravure printing, high smoothness is imparted by calendering or supercalendering the printing paper (static smoothness), and during gravure printing. By smoothing the paper under the pressure of the plate cylinder and impression cylinder and imparting flexible cushioning property (dynamic smoothness), there is no occurrence of misdots, which is a serious defect in gravure printing, and halftone dots are reproduced. Provided are high-quality gravure printing high-quality paper and high-quality coated base paper for gravure printing.

Further, as recording papers and copying papers, papers suitable for recording and copying methods such as self-coloring type heat-sensitive recording, fusion type heat-sensitive transfer recording, capsule type pressure-sensitive copying recording, ink jet recording, electrophotographic copying recording and the like are provided. To do.

The first feature of the present invention is that the dissolving pulp is used together with general chemical pulp as the pulp constituting the paper or the coated base paper. Dissolving pulp is mainly used in the production of viscose rayon and acetate, and is a raw material for chemical fibers, cellophane, plastics, synthetic pastes and various other cellulose derivatives. Conventionally, using dissolved pulp as a raw material for papermaking has generally been excluded as a raw material for general papermaking because it has no advantage, but the present inventor conversely utilizes the drawbacks for papermaking for specific quality characteristics. And achieved the present invention.

Dissolving pulp is, for example, DSP90 is a pulp having α-cellulose of 89.8% or more, which is the most highly purified pulp selected from general chemical pulps, as specified in JIS P2701. is there. Therefore, compared with other general chemical pulps, the content of β-cellulose is 6.5% or less, which is extremely low.

In the present invention, the dissolving pulp has a plastic deformation ratio of 75.
% Or more, more preferably 77% or more, and it is important that the usage rate is in the range of 10 to 50%, more preferably 20 to 40% with respect to the total pulp constituting the paper.

The plastic deformation rate of the dissolving pulp is the compression amount (1 kg / cm ² and 100) of the pulp sheet obtained by beating the dissolving pulp alone.
Thickness difference of Kg / cm ² ) and recovery amount after releasing pressure (50 Kg / cm ²
The thickness is calculated as a percentage, and the detailed measuring method will be described collectively in the section of the measuring method described later.

When the dissolving pulp having a plastic deformation rate of 75% or more is used, the paper is made as a paper having a relatively weak fiber-fiber bond. As a result, the surface of the paper is easy to be smoothed when pressed by a calendering process in a paper machine, a super calendering process after coating, etc. (excellent in static smoothness). Since the paper has cushioning properties (evaluated by Young's modulus) and flexibility, it exerts an effect of high smoothing action (dynamic smoothness) under pressure during gravure printing and recording copying. Even if the dissolving pulp is used, the intended effect cannot be exhibited if the beating progresses and the plastic deformation rate becomes less than 75%.

The second feature of the present invention is to provide a paper having a weak fiber-to-fiber bond by blending a dissolving pulp with the necessary paper strength and surface strength without impairing the soft cushioning property of the paper. It relates to a size press agent.
That is, in general, a starch aqueous solution is used as a size press agent to impart surface strength to paper, but by mixing a specific dissolving pulp, sufficient paper strength and surface strength can be obtained for paper with relatively weak interfiber strength. In order to maintain the soft cushioning property of the paper, a mixed composition liquid containing polyvinyl alcohol (hereinafter, PVA) and glycerin as main components of the size press agent is used.

It is known to use PVA as a size press agent, but generally PVA has a tough and rigid paper surface film after drying. Therefore, in order to impart the flexibility and cushioning property (static smoothness) which are the objectives of the present invention, it acts as an opposite effect, and becomes rigid and lacks flexibility, resulting in misdots and halftone dots during gravure printing. This causes poor reproducibility. Also, the suitability for recording is similarly deteriorated as a recording sheet.

The PVA used in the size press agent is generally completely saponified or partially saponified, a low viscosity product having a polymerization degree of about 500, a medium viscosity product having a polymerization degree of about 1,000, and a polymerization degree of 2,000. There are high-viscosity products centered on the degree. In the present invention, among others, the degree of polymerization is 1,000 to 2,40.
0 to medium to high viscosity product, more preferably polymerization degree of 1,500 to
The intended effect can be obtained by using a mixed solution of 2,000 completely saponified PVA and glycerin. That is, glycerin is added to 5-2 to 100 parts by weight of completely saponified PVA having a polymerization degree of 1,000 to 2,400.
5 parts by weight, and more preferably 10 to 20 parts by weight, is applied to apply a size press agent containing a composition as a main component, so that the finished paper has a low Young's modulus (excellent in flexibility and cushioning property). Nevertheless, a paper having excellent paper strength and surface strength can be obtained. The main component here is 80% by weight or more in the case of a clear size press that does not intentionally use pigments, and in the case of a pigment size press that intentionally uses pigments, based on the total solid content of the size press agent. 5
It is 0% by weight or more.

When the degree of polymerization of PVA is less than 1,000, it is necessary to increase the coating amount of the size press agent in order to obtain paper strength and surface strength, and it tends to be difficult to obtain a balance with flexibility cushioning properties. . On the other hand, when the degree of polymerization exceeds 2,400, the balance between viscosity and concentration during size press coating becomes poor, making it difficult to obtain the intended effect. The saponification degree is 9
A complete saponification type PVA of 8 to 99 mol% is stable in a phase solution with glycerin, and is excellent in both flexibility cushioning property and paper surface strength. A partially saponified type PVA having a saponification degree of 87 to 89 mol% or a modified PVA such as carboxy-modified has a defect in continuous workability in a paper machine size press and may not be used.

In the total solid content of the size press agent, surface sizing agents or size press additives and pigments for pigment size which are generally used as auxiliaries are used according to the purpose. Further, for example, starch, a cellulose derivative, gum, alginic acid or the like can be used as a fluidity improving aid within a range that does not impair the intended effects of the present invention. The above-mentioned pigments and auxiliaries can be commonly used for internal filling and coating.

As the method for applying the size press agent of the present invention, for example, a two roll size press, a gate roll size press, a bill blade size press, a transfer roll size press using a blade or a rod, a spray size press, etc. In addition, an on-machine coater such as a blade coater or a short dwell coater can also be used.

If desired, an internal filler may be added to the papermaking raw material of the high-quality paper obtained in the present invention. The type of filler is not particularly limited, and commonly used fillers for internal addition are appropriately selected and used. Specific examples thereof include talc, kaolin, heavy calcium carbonate, light calcium carbonate, titanium dioxide, synthetic silica and various minerals such as calcium, magnesium, aluminum and silica, and organic-inorganic synthetic fillers.

Further, various internally used sizing agents and anionic, nonionic or amphoteric retention aids, drainage improvers and paper strengths are used so far as the desired effects of the present invention are not impaired. An internal additive for paper making such as a reinforcing agent is appropriately selected and used as necessary.

The high-quality paper of the present invention can be made into paper by a paper machine as described above, and various smoothing treatments such as machine calendering, soft calendering and compact calendering can be used. it can.

The high-quality paper of the present invention is used as a base paper for coating on-machine or off-machine coater, for example, a coater equivalent to the above size press, air knife coater, rod coater, roll coater, reverse coater, curtain coater, lip coaty. Alternatively, the desired composition may be coated with a gravure coater or the like to form a coating layer, and various calendar finishes may be performed.

For the coating layer, generally known coating agents can be used. For example, in coating paper for printing, melt-type thermal transfer paper, ink jet recording paper, etc., a coating containing a pigment and an adhesive as main components. A self-coloring thermosensitive recording paper is provided with a coating layer containing a colorless or light-colored dye coloring agent and an inorganic-organic coloring agent as a basic mixture.

The coating amount is generally 2 to 25 g / side.
In m ² about, there is a coating amount suitable for each coating varieties,
It can be applied as a single layer, multiple layers, one side or both sides. For calendering, there is a single calender or multiple calender method in which super calender and other elastic rolls and rigid rolls are configured in multiple stages or two stages and nip pressure is applied.

[0029]

EXAMPLES The present invention will be described in more detail below with reference to examples of high-quality paper for gravure, but the present invention is not limited thereto. Unless otherwise specified,% and parts in the examples indicate% by weight and parts by weight. Further, the blending percentage of the pulp and the raw materials of the mixed stock material shows the percentage with respect to the total pulp.

Example 1 Dissolving pulp DSP90 was beaten with a double disc refiner to obtain Canadian standard freeness (hereinafter C
SF) 557 ml of beating material (A) was obtained. The plastic deformation rate of the beaten raw material (A) was 80.0%. Similarly, commercially available NBKP is beaten to 600 ml of CSF to beat the raw material (B),
Commercially available LBKP was beaten to 580 ml of CSF to obtain a beaten raw material (C) having a plastic deformation rate of 71.0%.

10% of beaten raw material (A), beaten raw material (B)
20% and beaten raw material (C) 70% and 1% talc (trade name: NK talc / Chuo Kaolin Co.) as a filler
0%, rosin (trade name: SPE / manufactured by Arakawa Chemical Industry Co., Ltd.) 0.2% as an internally added sizing agent, and 3.0% sulfuric acid band were each added to obtain a papermaking raw material.

This papermaking raw material was hand-paper-made with a standard square sheet machine (manufactured by Toyo Seiki Co., Ltd.), dried, and then the degree of polymerization was 1,700.
Completely saponified polyvinyl alcohol (trade name: PVA-
117 / manufactured by Kuraray Co., Ltd.) A 5% aqueous solution of a mixed solution of 100 parts and 10 parts of glycerin is used as a size press agent, and a size press is performed with a model size press so that the amount of adhesion after drying is 2.5 g / m ² on both sides solid content After coating and drying, a two-stage metal roll machine calendering treatment was performed. And linear pressure 2
A model super calender treatment was performed at 0 kg / cm to obtain a fine paper for gravure printing with a weight of 60.0 g / m ² of tsubo.
This high-quality paper was evaluated as non-coated paper for gravure printing and Table 1
It was shown to.

(Preparation of coating liquid) Kaolin (trade name: UW
-90 / manufactured by EMC) 60 parts, aluminum hydroxide (trade name: HAL / Showa Denko) 30 parts, titanium oxide (trade name: FA55W / furukawa mining company) 10 parts and sodium polyacrylate 0.5 Parts were dispersed in water using a disperser to prepare a pigment slurry having a concentration of 68%. Oxidized starch (trade name: Ace A) obtained by boiling this pigment slurry as an adhesive in advance at 95 ° C. and 28% concentration for 30 minutes
/ Oji Constarch) 5 parts and styrene / butadiene copolymer latex (trade name: SN-307 / Sumitomo Nogatac Co., Ltd.) 8 parts were added, and further, silicon-based defoaming agent 0.05 parts and calcium stearate 0. 2 parts and water were added and mixed with stirring to obtain a coating liquid having a concentration of 60%.

(Preparation of Coated Paper) The high-quality paper obtained above after machine calendering was used as a base paper for coating, and the coating amount after drying the above coating liquid was 10 g / m ² per side. Coated on both sides using a blade coater and dried to obtain a coated paper of 80 g / m ² square meter, using a model super calender, temperature 40 ° C., linear pressure 30 Kg / cm 2.
The results are shown in Table 1.

Example 2 The procedure of Example 1 was repeated, except that 20% of the beating raw material (A), 20% of the beating raw material (B) and 60% of the beating raw material (C) were added.

Example 3 The procedure of Example 1 was repeated, except that 30% of the beating raw material (A), 20% of the beating raw material (B) and 50% of the beating raw material (C) were added.

Example 4 Same as Example 1 except that 40% of the beating raw material (A), 20% of the beating raw material (B) and 40% of the beating raw material (C) were added.

Example 5 In Example 1, 50% of the beating material (A), 20% of the beating material (B) and 30% of the beating material (C) were blended, and the size press deposit was 3.5 g / m. Example 1 except ²
Same as.

Example 6 Dissolving pulp DKP93 was beaten with a double disc refiner to obtain a beating original amount (D). Beating material (D)
The plastic deformation rate was 77.4%. 15% of this beating raw material (D) and 65% of the beating raw material (C) were blended, 10% of light calcium carbonate (trade name: TNC-30 / Toyo Denka Kogyo) as a filler, and alkyl ketene as an internally added sizing agent. 0.3% dimer (trade name: SPK-287 / Arakawa Chemical Industry), 0.24% sulfuric acid band, 0.7% cationic starch (trade name: AMYROFAX-2200 / Matsuya Chemical Industry), paper strength The same procedure as in Example 1 was performed except that 0.06% of the agent (trade name: BMA / manufactured by Nissan Eka Nobel Co., Ltd.) was added to the absolutely dry pulp, and the size press adhesion amount was 2.8 g / m ² .

Example 7 In Example 6, 10 g of glycerin as a size press agent was used.
Example 6 was repeated except that the number of parts was changed to 20.

Example 8 In Example 6, the size press agent PVA117 was used.
Partial saponification type PVA with a degree of polymerization of 500 (trade name: PV
A105 / manufactured by Kuraray Co., Ltd.).

Comparative Example 1 The procedure of Example 1 was repeated, except that 60% of the beating raw material (A) and 20% of the beating raw material (C) were blended.

Comparative Example 2 In Example 5, the dissolving pulp DKP93 was beaten with a double disc refiner to obtain 400 ml of CSF beaten raw material (E). The plastic deformation rate of this beating material is 73%
Met. Beating material (E) 50%, Beating material (C) 30
The same procedure as in Example 1 was carried out except that the content of 0.1% was added.

Comparative Example 3 In Example 2, as a size pressing agent, a 7% aqueous solution of oxidized starch (trade name: Ace A / manufactured by Oji Constarch Co., Ltd.) was dried to give a solid content of 3.0 g / m ² . Example 2 was performed in the same manner as in Example 2 except that the size was pressed so that

Comparative Example 4 In Example 2, PVA-11 was used as a size press agent.
After drying the 5% aqueous solution of No. 7, the amount of adhesion was 2.3 g / solid.
The same procedure as in Example 2 was carried out, except that the size was pressed so as to be m ² .

Comparative Example 5 In Example 2, 10 parts of the size press agent glycerin was used.
Example 2 was repeated except that the number of parts was changed to 30 parts.

Comparative Example 6 The procedure of Example 7 was repeated, except that 20% of the beating raw material (B) and 80% of the beating raw material (C) were added.

Comparative Example 7 The procedure of Example 7 was repeated, except that water was used as the size press agent.

Evaluation Method and Judgment [Plastic Deformation Rate] A predetermined C was measured with a double disc refiner.
100 parts of pulp, rosin 0.
2%, sulfuric acid band 3.0% are added, and the rice paddy is 60.0 g /
creating a temperature 20 ° C. The handsheet sheet m ^2, 60% relative humidity
After being left to stand for 24 hours, this sheet was punched with a punching jig to prepare 50 10.5 mmφ sheets. Fifty sheets of this sheet are stacked and an automatic recording type tensile tester / INTESCO (manufactured by INTESCO) is used to obtain a strain rate of 1 mm /
The thickness under pressure of the minute was measured.

At this time, the sheet thickness at a pressure of 1 Kg / cm ² was set to A μm and the pressure was set to 100 Kg / cm ² , and subsequently, the pressure at 50 Kg / cm ² after the pressure was released was calculated as B μm by the following formula. Plastic deformation rate (%) = (A−B / A) × 100

[Young's modulus] The Young's modulus was obtained from a stress-strain curve in a tension test at Intesco. Strain rate 0.5 cm /
Minute, paper width 15mm, span length 150mm, number of samples 6
The average of the points and the chart speed of 30 cm / min were calculated by the following equation and shown in Table 1. Young's modulus (Kg / cm ² ) = (W / A) × (L / λ) where W: load (Kg), A: cross-sectional area (mm ² ),
L: span length (mm), λ: elongation (%)

[Gravure printing evaluation] Using a gravure printing tester (manufactured by Kumagai Riki), plate; conventional halftone dot gradation, printing pressure; 50 Kg / cm, printing speed; 8
0 m / min, ink; Toyo Ink OG-39, viscosity; Zahn cup No. Gravure printing was performed under each condition of 17 seconds measured in No. 3. Gravure printing evaluation is for 10% dot
Enlarged 20 times with a microscope with polaroid photo, reproducibility of 100 dots, 3 points for all, 2 points for 3/4 or more,
1 point for 1/2 or more reproduction, 0 point for 1/2 or less reproduction, and a total score of 10 sheets is 30 points,
15 points or more for uncoated paper (excellent),
10 points or more ○ (excellent), 10 points or less Δ (somewhat inferior), 5 points or less × (inferior), and in the case of coated paper 20 points or more ◎ (very excellent), 15 points or more ○ (excellent), 10 points or more △ (somewhat inferior), 10 points or less ×
It is shown in Table 1 as (poor).

[Surface Strength] A red ink (trade name: Print INK [Paper Test SD50 Red BT = 13] / T & K TOKA) is printed with an RI printing tester (manufactured by Akira Seisakusho), and the surface strength is visually observed. It was judged. The criterion is ◎; very good with no picks, ○;
It is shown in Table 1 that there is almost no pick occurrence, which is excellent.

[0054]

[Table 1]

[0055]

As shown in Table 1, the high-quality paper of the present invention is excellent in gravure printing evaluation and surface strength in both the uncoated paper for gravure printing and the coated paper for gravure printing using the same as the base paper. It was a high-quality paper with excellent smoothness and dynamic smoothness. The characteristics of this high-quality paper are effective not only for gravure printing but also for information paper.

Claims (3)

[Claims] 1. A high-quality paper which has a mechanical pulp content of 5% by weight or less of the total pulp and which has been subjected to a size-pressing agent treatment, is a dissolving pulp (JIS-P2701) having a plastic deformation rate of 75% or more as a pulp type. 1 for pulp
A high-quality paper containing 0 to 50% by weight, and 5 to 25 parts by weight of glycerin as a main component of the size press agent with respect to 100 parts by weight of polyvinyl alcohol. 2. Polyvinyl alcohol has a degree of polymerization of 1,000.
2. The high-quality paper according to claim 1, which is a completely saponified polyvinyl alcohol of about 2,000. 3. The high-quality paper according to claim 1 or 2, wherein the high-quality paper is a gravure printing paper or a coated base paper for gravure printing.