JP2705457B2 - Tissue paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tissue paper, and more particularly to a tissue paper which is soft and has a good touch.

[0002]

2. Description of the Related Art As is well known, tissue paper such as cosmetic tissues, toilet tissues, and towels is desired to be soft, have a good touch, have high strength, have high elasticity, and have excellent absorbency. ing. However, being soft and excellent in touch and having high strength are contradictory characteristics, and it is actually difficult to achieve both.

[0003] The strength of tissue paper is not only an important characteristic in the papermaking process and in the process of processing the tissue paper after papermaking, but also one of the important conditions for consumer use.

Conventionally, as pulp for so-called household thin paper (hereinafter referred to as tissue paper) such as toilet paper, tissue paper, paper towel, etc., chemical pulp obtained by digesting wood chips from hardwood and coniferous wood is used. Deinked waste paper pulp obtained by deinking waste paper is used. These pulp can be used alone in unbleached and / or bleached pulp or in unbeaten or beaten pulp depending on the quality design. Or, they are used as a mixture.

The average fiber length and fiber width of hardwood and softwood used as raw materials for these pulp are shown in Table 1.
The fiber length of hardwood is shorter than that of softwood. Therefore, when pulp using hardwood as a raw material is used, there is a problem that the strength is correspondingly too low. As is clear from the results of analysis of commercial products and the like, softwood pulp is usually blended in an amount of 50% by weight or more.

Table 1 shows the length and width of plant fiber for papermaking (Paper Science: Chugai Industry Research Council, page 22, published on March 25, 1982). Use of hardwood and softwood pulp as commercially available tissue paper. Table 2 shows the results of the analysis of the ratio (based on the TAPPI standard T401om-82 method).

[0007]

[Table 1]

[0008]

[Table 2]

Techniques for improving the softness and feel, which are important qualities of tissue paper, have been studied for some time. For example, a laminated tissue paper in which the type of pulp and its usage ratio are adjusted and a method for producing the same are described. (Japanese Unexamined Patent Publication No. 54-46914, Japanese Utility Model Application No. 2-110449),
By appropriately selecting a paper machine such as a short net, a twin wire, a round net, a Yankee machine, or a paper softener such as a fatty acid ester softener (US Pat. No. 3,296,065), a quaternary ammonium salt type cation Activator (JP
48-22701), urethane alcohol, salts or cations thereof (JP-A-60-139897), polyphosphates (JP-A-2-36288), polysiloxanes (JP-A-2-36288).
Various methods have been proposed, such as a method of adding an additive chemical such as 224626 and 3-900) to slush pulp to make the slush pulp itself slippery, to improve the feel and soften it.

The present inventors use dry pulp as one layer of a two-layered tissue paper, contact the layer with a mirror surface of a Yankee dryer, and dry the layer. ), Two papers were superposed to form a tissue paper having a good touch feeling ( Japanese Patent Application Laid-Open No. 5-285644 ). Because the unit price is high,
There was a problem that the cost of the finished tissue paper was high and a large amount of dry pulp could not be used.

[0011] When three or more layers of laminated tissue paper are laminated, the texture may be deteriorated and the quality may be degraded. Therefore, a two-layer tissue paper is currently the mainstream.

In the method using the above-mentioned additive chemicals, a good softening effect may be obtained in some cases. However, since the foaming property is large, there is a possibility that the paper making operation itself may be hindered. There was a problem that the water absorption was reduced.

In order to increase the wet strength of tissue paper, urea formaldehyde resin, melamine formaldehyde resin, polyamide, polyamine, epichlorohydrin resin, etc. are known as paper wet strength agents for paper. In the case of (1), since a formaldehyde resin is disliked, a polyamide, a polyamine, and an epichlorohydrin resin are mainly used. However, there is a problem that the bond with the epoxy resin is very firm and not only insoluble in water, but also the tissue paper itself becomes rigid, and the points of softness and touch are reduced.

Conventionally, the smoothness of the surface is improved by using one or two sets of a calender composed of a pair of sufficiently polished chilled rolls and metal rolls, one each for upper and lower, after a tissue paper machine. Is used. However, in this calendar, there is a problem that when the linear pressure is increased to improve the smoothness, the thickness becomes thin and rigid, and the touch feeling deteriorates.

[0015]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has been intensively researched on the problem of manufacturing tissue paper which is soft, has a good touch, and has excellent strength. The fiber length obtained from bleached pulp (pulp that has not been subjected to drying treatment and hereinafter referred to as slash pulp), pulp obtained by drying the pulp (hereinafter referred to as dry pulp), and printing paper used in office automation equipment in offices By paying attention to the properties of the deinked waste paper pulp, it was possible to obtain a tissue paper having a novel flexibility and improved feel.

[0016]

Means for Solving the Problems The present invention relates to a tissue paper comprising two layers made mainly of pulp fiber,
The raw material pulp constituting one layer of tissue paper is 5 to 15% by weight of slash pulp of bleached hardwood pulp and 5 to 20% by weight of dry pulp obtained by drying the pulp to a moisture of 3 to 25% (per absolutely dry pulp weight). And a pulp sieving test (JIS P 8207) consisting of a mixture of 65 to 90% by weight of deinked waste paper pulp consisting of 9 to 15% by weight of fibers remaining in the 24 mesh and 16 to 21% by weight of fibers passing through the 150 mesh. Other 1
The raw pulp constituting the layer is made of slush pulp of undried softwood bleached pulp, and the layer containing the deinked waste paper pulp is dried by contacting the mirror surface of the Yankee dryer, and the layer is on the outside. This is tissue paper in which two sheets are superimposed and laminated.

That is, the present invention relates to the use of deinked waste paper pulp (hereinafter referred to as DIP) having a specified fiber length as a raw material pulp for tissue paper together with dry pulp. The present invention focuses on making it possible to produce a tissue paper having excellent softness and touch feeling, which promotes the softness of slush pulp which is caused by fibers in a so-called "withered state".

[0018] One of the two layers of tissue paper is
One layer is formed of a hardwood bleached pulp containing the dry pulp and DIP, and the other layer is formed of a mashed slush pulp of softwood bleached pulp, and the dry pulp and the DIP are combined. The containing layer is dried by touching the mirror surface of the Yankee dryer and laminating two tissue papers so that the surface is on the outside (that is, the side where the user touches the hand, the same applies hereinafter). ,
It is a tissue paper with improved feel and a high tensile strength.

The hardwood bleached pulp used as the raw material pulp constituting one layer of the tissue paper of the present invention is obtained by digesting hardwood wood by a known cooking method, and having a Hunter whiteness of 80 to 90%.
Any pulp that has been bleached to the maximum (referred to as slush pulp) or a pulp obtained by re-dissolving dry pulp of the pulp in water may be used, and hardwood bleached kraft pulp (LBKP) is preferably used.

The dry pulp used in the present invention is a paper machine, a pulp machine in which the above-mentioned slash pulp is combined with a well-known round or long net and a multi-cylinder dryer, or a pulp machine in which the above-mentioned sheet forming apparatus is combined with another hot-air drying apparatus. And dried to a water content of 3 to 25% (per absolutely dry pulp weight), preferably 5 to 20%.

If the moisture content of the pulp is dried to less than 3%, the pulp fiber deteriorates, which is not suitable. If the moisture content is more than 25%, moisture in the molecule of the pulp fiber cannot be removed. It is not suitable because pulp fibers in a so-called "withered state" cannot be obtained and do not contribute to improving the feel of the tissue paper.

The DIP used for the present invention is used to drum used fluorescent dye-free waste paper from offices having office automation (OA) equipment, such as computer paper, facsimile paper and word processing paper. It is manufactured by a known method of defibrating with a barker, removing impurities, deinking, and optionally bleaching in a Hunter whiteness range of 75 to 89% as required, and has a freeness of 250 to 450ml (Canada Standard Freeness)
And pulp sieving test (JIS P 8207): 9 to 15% by weight of fiber remaining 24 mesh, 16 to 16% of fiber passing 150 mesh
DIP consisting of 21% by weight is preferably used. Above all,
The feature of the present invention is that OA waste paper having the aforementioned fiber length is used.
This is based on the finding that DIP fibers are close to the characteristics of dry pulp and have a remarkably excellent effect on the texture as a tissue paper.

On the other hand, DIP from used newspaper and magazine wastepaper contains a large amount of softwood mechanical pulp. For example, 35 to 40% by weight of long fibers such as 24 mesh residue in the sieving test are present. Nevertheless, the strength (tear length and specific rupture) is 20 to 30% lower than that of DIP from waste OA paper, which impairs the feel of the tissue paper and weakens the strength of the tissue paper. It is not preferable to use it together with dry pulp for the layer on the side where human hands touch.

The human-touchable one layer of the two-layer tissue paper of the present invention is composed of a mixture of slush pulp of bleached hardwood pulp and its dry pulp and DIP from OA waste paper as described above. The other layers constituting the layer on the side not touching are softwood bleached pulp which is strong in strength since it does not affect the feeling of touch, preferably bleached softwood bleached kraft pulp having a hunter whiteness of 80 to 90% ( NBKP) slush pulp is preferably used.

The use ratio of the NBKP and the mixed pulp in the two-layered tissue paper of the present invention is in the range of 40:60 to 70:30, preferably 50:50 to 65:35 in terms of absolute dry pulp weight.
Within the range, the pulp from the two jets is appropriately selected and used by adjusting the pulp concentration and the ejection amount.

The mixed pulp comprising LBKP slush pulp, dry pulp and DIP as raw pulp constituting one layer of the tissue paper of the present invention is brought into direct contact with the mirror surface of a Yankee dryer and dried. The proportion of slush pulp, dry pulp and DIP used in the pulp is appropriately selected and used within the range of 5 to 15% by weight of slush pulp, 5 to 20% by weight of dry pulp and 65 to 90% by weight of DIP.

If the slush pulp (LBKP) is less than 5% by weight, the strength becomes weak, so that it is not suitable. If it exceeds 15% by weight, the touch feeling is impaired, so that it is not suitable. Dry pulp (LBK
P) is most suitable for improving the feeling of touch, but this pulp is troublesome in its production and is expensive, so if used in large quantities, the cost of tissue paper is increased, which is not preferred.

Therefore, if the dry pulp content is less than 5% by weight, the effect of improving the feeling of touch is deteriorated, and if it exceeds 20% by weight, the cost is not suitable. On the other hand, the use of the above-mentioned DIP is excellent in texture and is advantageous in terms of cost.Thus, it is possible to produce tissue paper of superior quality by using as much as possible, but maintain strength and balance the quality. In order to obtain DIP, it is desirable to appropriately select and use DIP from the range of 65 to 90% by weight.

As a tissue paper machine, a Yankee machine such as a circular net, a short net, and a twin wire can be used. The base paper of tissue paper can be obtained by applying wet crepe or dry crepe on a Yankee dryer or applying wet crepe and further applying dry crepe. In the case of a boxed tissue paper or the like, two sheets of the paper are stacked and processed by a calender comprising a pair of upper and lower metal rolls to obtain a tissue paper.

[0030]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but it should be understood that the present invention is not limited thereto. In the Examples and Comparative Examples, parts,%
Represents parts by weight and% by weight unless otherwise specified.

The evaluation methods used in the following examples and comparative examples are as follows. ○ Tensile strength measurement method Two layers of tissue paper are cut into 25 mm width in parallel with the flow direction (longitudinal direction), and the length 100 mm is set on a Tensilon universal tensile tester (manufactured by Toyo Bold-in Co., Ltd.). Measure the breaking strength. ○ Softness measurement method (J.TAPPI paper pulp test method No.34 -8
0, Softness test method for thin tissue paper for sanitary use) Handle-O-Meter (Kumagaya Osamu) which measures the amount of work required to push a tissue paper sheet (200 x 200 mm) into a certain gap (6.35 mm) Was multiplied by 0.5 and the unit was g / 10 cm. The test piece is pushed in at right angles to the flow of the sample.

○ Touch feeling Sensory evaluation was conducted by 5 males and 5 females, and displayed in the following categories. ◎: Very good, ○: Good, △: Normal, ×: Poor ○ Evaluation of economic efficiency In general, the unit price of pulp varies greatly depending on whether it is self-made or purchased, and it varies depending on the factory location and the economic situation at that time. But here, the unit price of dry pulp is 1.3 to 1.5 times (average 1.4 times) of slash pulp, and DIP is 0.8 to 0.9 times (average 0.85 times) of slush pulp, and constitutes one layer that comes into contact with the Yankee dryer surface The evaluation was performed when the raw material pulp was 100 when the slush pulp of LBKP was 100%. ◎: Economic efficiency is excellent at less than 95, ○: Economic efficiency is somewhat excellent at 95 to 100, ×: Exceeds 100 and economical efficiency is poor

DIP from OA waste paper is obtained by defibrating used computer paper, copy paper, etc. of high quality paper containing no high yield pulp with a drum pulper, and removing the pulp by a known deinking treatment method. Ink and bleached were used with a Hunter whiteness of 86.0%, fibers remaining in the pulp sieving test of 11.6%, fibers passing through 150 mesh 18.7%, freeness of 345 ml., And breaking length of 4.75 km.

Drying of the pulp to obtain dry pulp
This was performed by a fourdrinier multi-cylinder dryer paper machine. The pulp used was LBKP slush pulp obtained by cooking domestic hardwood material by a known kraft cooking method and bleaching the hunter to a brightness of 85.5%. NBKP is 80% domestic pine and Douglas fir
A slush pulp obtained by digesting 20% of the mixture by the known craft method and bleaching to a Hunter brightness of 85.3% was used in the same manner as described above. LBKP slush and dry pulp and NBKP slush pulp were used at a freeness of 560 ml.

A wet paper strength enhancer (Kaimen K-1300, manufactured by Dick Hercules Co., Ltd., trade name) was added to each of the one-layer and two-layer raw material pulp in an amount of 0.10% based on the absolutely dried pulp weight.
In addition, cationized modified starch (Koji F, manufactured by Oji National Co., Ltd.) was added at 0.05% based on the weight of the absolutely dried pulp, and paper was formed using a twin-wire type two-layer Yankee paper machine. Crepe was applied by taking the difference in speed between the dry crepe and the dryer and take-up reel. The basis weight of the two layers of tissue paper made is 13.5 g / m2
It was adjusted to be.

Unless otherwise stated, the two-layered tissue papers were stacked so that the surface of the dryer in contact with the mirror surface of the dryer was on the outside (the side in contact with the user's hand). Example 1 Pulp in contact with the mirror side of a Yankee dryer of tissue paper from a two-layer tissue paper machine with a Yankee dryer was hardwood bleached kraft pulp (LBKP)
2.5 parts of slush pulp of raw pulp composing one layer
6.3%), 2.5 parts of LBKP dry pulp (6% moisture)
It consists of 6.3% of the raw material pulp composing the layer and 35 parts of DIP (87.4% of the raw material pulp composing one layer), and the surface that does not contact the mirror side of the dryer (called the anti-dryer side)
Tissue paper was manufactured using a paper pulp consisting of 60 parts of slush pulp of softwood bleached pulp (NBKP).

Example 2 5 parts of slush pulp of LBKP (12.5% of raw pulp constituting one layer), 7 parts of dry pulp of LBKP (23% of water) (17.5% of raw pulp constituting one layer) and DIP28 Department (1
Tissue paper was produced in the same manner as in Example 1 except that the raw material pulp constituting the layer was 70%).

Comparative Example 1 The raw material pulp on the mirror side of the dryer of two-layer tissue paper was 1 part of slush pulp of LBKP (2.5% of the raw material pulp constituting one layer), and the dry pulp of LBKP (moisture 6%)
1 part (2.5% of raw pulp constituting one layer) and DIP38
A tissue paper was produced in the same manner as in Example 1 except that the pulp on the side opposite to the dryer was 60 parts of slush pulp of NBKP. Comparative Example 2 The raw material pulp on the mirror side of the dryer of the two-layered tissue paper was 2 parts of dry pulp (6% moisture) of LBKP (5% of the raw pulp constituting one layer) and 38 parts of DIP (the raw material constituting one layer). Tissue paper was produced in the same manner as in Example 1 except that the pulp on the side opposite to the dryer was 60 parts of slush pulp of NBKP.

Comparative Example 3 The raw material pulp on the mirror side of the dryer of the two-layered tissue paper was 2 parts of slash pulp of LBKP (5% of the raw material pulp constituting one layer) and 38 parts of DIP (of the raw material pulp constituting one layer). 95%), and the pulp on the anti-dryer side is NB
Tissue paper was produced in the same manner as in Example 1 except that 60 parts of KP slush pulp was used. Comparative Example 4 The raw material pulp on the mirror side of the dryer for two-layer tissue paper was 8 parts of slash pulp of LBKP (20% of the raw material pulp constituting one layer), and the dry pulp of LBKP (moisture 6%) 10
Example (except that the pulp on the side opposite to the dryer side is 60 parts of NBKP slush pulp) consisting of 22 parts (25% of raw pulp composing one layer) and 22 parts DIP (55% of raw pulp composing one layer) Tissue paper was produced in the same manner as in Example 1.

Comparative Example 5 Using the two-layer tissue paper obtained in Example 2, two sheets were superposed and laminated so that the surface in contact with the mirror surface of the Yankee dryer was on the inside and the anti-dryer surface was on the outside. Manufactured tissue paper.

The feel, softness, and tensile strength of the two-ply tissue paper of the example and the comparative example were measured.
Tables 3 and 4 show quality evaluations in consideration of economy. As is evident from Tables 3 and 4, two layers of LBKP slush pulp, dry pulp and DIP were used to make 5 layers of tissue paper.
When used in the range of 20% and 65-90%, and this layer is dried in contact with the mirror surface of the Yankee dryer, and when used, two tissue papers are stacked so that the layer touches human hands. Thus, a tissue paper having excellent tensile strength, softness, and especially excellent touch feeling can be obtained without losing economical efficiency without using a large amount of pulp having a high unit price.

[0042]

[Table 3]

[0043]

[Table 4]

On the other hand, if the amount of DIP used is large, it is economically excellent, but the tensile strength is slightly inferior and the feel is not improved (Comparative Examples 1, 2, 3), and the amount of DIP used is 60% of the raw pulp.
%, The amount of dry pulp used must be increased to 20% or more in order to obtain an excellent touch feeling, thus deteriorating economic efficiency (Comparative Example 4) and further contacting the Yankee dryer. When the tissue paper was obtained by laminating and laminating two sheets so that the inside was on the inside and the anti-dryer side was on the outside, the texture was extremely poor (Comparative Example 5).

[0045]

As described above, the present invention relates to a two-layer tissue paper containing pulp fiber as a main raw material, wherein one layer of raw pulp is a mixed pulp comprising LBKP slush pulp, dry pulp and DIP. Is dried in contact with the mirror surface of the Yankee dryer, and furthermore, by laminating two tissue papers so that each layer is on the outside, flexibility, tensile strength, especially feel to the touch can be obtained without impairing economic efficiency. This has the effect of making it an excellent tissue paper.

Claims (1)

(57) [Claims] 1. A tissue paper comprising two layers mainly composed of pulp fiber, wherein the raw material pulp constituting one layer of the tissue paper is 5 to 15% by weight of slash pulp of bleached hardwood pulp and water of 3%. 5 to 20% by weight of dry pulp dried to 2525% (per absolutely dry pulp weight) and 9 to 15% by weight of the remaining 24 mesh fibers in the pulp sieving test (JIS P8207)
The deinked waste paper pulp consisting of 16 to 21% by weight is made of a mixture of 65 to 90% by weight, and the other raw material pulp constituting one layer is made of undried softwood bleached pulp slush pulp. A tissue paper wherein a layer contained therein is dried by contacting with a mirror surface of a Yankee dryer, and two sheets are laminated so that the layer is on the outside.