JPH04370300A - Water-disaggregative paper with multilayer structure and production thereof - Google Patents

Abstract

PURPOSE:To obtain the title paper with high mechanical strength after chemical impregnation, excellent in water disaggregation and productivity, useful as e.g. cleansing tissues, by putting two kinds of paper stock each containing specified amount of a paper strengthening agent to multilayer papermaking process so that said two kinds of paper stock make up the respective outermost layers followed by drying. CONSTITUTION:(A) The first paper stock 10 containing 10-60wt.%, on a dry basis, of a paper strengthening agent, i.e., carboxymethylated pulp salt, water-soluble PVA, water-soluble PVA fibers or a mixture thereof, and (B) the second paper stock 10' containing <=5wt.%, on a dry basis, of such agent, are put to multilayer papermaking process so that the above two kinds of paper stock 10, 10' make up the respective outermost layers 14,15 of a wet paper 16, and the outermost layer 14 consisting of the second paper stock 10' is dried as the contact surface for a contact-type dryer 17, thus obtaining the objective water-disaggregative paper 1. It is preferable that said carboxymethylated pulp salt be a sodium salt or mixed salt containing the same with the substitution degree of 0.2-0.6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to water-disintegrable paper having a multilayer structure, which has high strength when impregnated with a chemical solution such as alcohol, and has excellent water-disintegrability.

0002

BACKGROUND OF THE INVENTION Water-disintegrable paper and quick-dissolve paper, which are cleaning paper impregnated with a cleaning alcohol or the like, and whose constituent fibers are quickly dispersed in water when the paper is thrown into water, are well known. For example, Japanese Patent Publication No. 42-2925 discloses a method for continuously producing fast-dissolving detergent-containing washing paper, decorative paper, etc. by etherifying continuous paper made essentially of cellulose in its paper form. There is. According to this technology, commercially available paper can be suitably and rapidly dissolved. Furthermore, JP-A-1-168999 discloses a technique for obtaining water-disintegrable paper that is easily water-dispersible and has high strength when impregnated with a chemical solution by mixing water-dispersible papermaking fibers and water-insoluble carboxymethylated pulp. are doing.

0003

[Problems to be Solved by the Invention] According to each of the above-mentioned techniques, a detergent, disinfectant, or other chemical solution provided by the present invention is impregnated and used. For example, it is possible to obtain water-disintegrable paper for cleaning paper such as hand towels.

However, the technology disclosed in Japanese Patent Publication No. 42-2925 requires foldable continuous paper, and furthermore, it is necessary to unroll the continuous paper and etherify it, so the continuous paper that can be used for this purpose is comparatively difficult. It is a paper with a large basis weight. In other words, there is a problem in that it is difficult to produce water-disintegratable paper with a relatively small basis weight, for example, about 10 to 50 g/m2. Furthermore, the technique disclosed in Japanese Patent Application Laid-open No. 1-168999 involves making paper from a paper stock mixed with a large amount of water-insoluble carboxymethylated pulp as a paper strength enhancer. When such a paper stock is used in a contact dryer in the dry part of the papermaking process, as drying progresses, the contact surface strongly adheres to the dryer, making it difficult to separate. Therefore, this technique has a problem in that it is difficult to use a general-purpose contact dryer.

[0005] Therefore, the present invention comprises a water-disintegratable paper with at least two layers, one of the two opposing outermost layers of the water-disintegratable paper contains a relatively large amount of paper strength enhancer, and the other outermost layer contains a paper strength enhancer in a relatively large amount. This problem is attempted to be solved by including a relatively small amount of paper strength enhancer.

[0006]

[Means for Solving the Problems] The gist of the present invention for solving the above problems is as follows.

[0007] The present invention is based on the provision of a multi-layered water-disintegratable paper and a method for producing the same, and the water-disintegratable paper has a multi-layer structure consisting of at least two layers, and the two outermost layers of the water-disintegratable paper are located opposite to each other. One of the outermost layers is 10 to 60% by weight.
The gist is that the other outermost layer contains 5% by weight or less of a paper strength enhancer. Further, the method for producing a multilayered water-disintegratable paper includes a step of drying a wet paper using a contact dryer, and the method includes a paper strength enhancer in an amount of 10 to 60% by weight on a dry weight basis. 1st
At least a paper stock and a second paper stock containing 5% by weight or less of a paper strength agent are used. After obtaining a wet paper with a multilayer structure such that each stock constitutes the outermost layer of each of the wet paper webs, the outermost layer of the wet paper made of the second paper stock is used as a contact surface for the contact dryer to dry. The gist is that the first and second stock constitute the outermost layer of each of the water-disintegratable papers.

In a preferred embodiment, the paper strength agent is in each case a salt of carboxymethylated pulp, water-soluble polyvinyl alcohol, water-soluble polyvinyl alcohol fiber, or a mixture thereof; To salt the pulp, use sodium salts or mixed salts containing sodium salts.

[0009]

[Function] In the water-disintegratable paper according to the present invention constructed as described above, the outermost layer containing a high content of paper strength enhancer exhibits excellent surface strength even when impregnated with a chemical solution, and does not tear easily. This outermost layer is suitable for use exclusively as a wiping surface. The other outermost layer has a low content of paper strength agents, containing at most 5%. Therefore, this layer quickly disperses in water, and is good for water-disintegratable paper, even though the outermost layer tends to reduce the water-disintegratability of water-disintegratable paper due to the influence of high content of paper strength enhancer. Provides water degradability. Furthermore, in the water-disintegratable paper having such a structure, the outermost layer containing a low content of paper strength enhancer can be used as a contact surface for a contact dryer during the paper-making process. This contact surface is extremely easily peeled off from the dryer after drying, so that the productivity of the water-disintegratable paper is not reduced even though one of the outermost layers contains a large amount of paper strength enhancer.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be explained below with reference to the accompanying drawings.

FIG. 1 schematically shows the paper-making process of water-disintegratable paper 1 according to the present invention. The process includes at least two lines of first and second raw material preparation processes 2 and 2', one short screen wire 9 and one circular screen paper machine 13, a pickup felt belt 11, a felt belt 12, a drying cylinder 17, etc. . In each raw material preparation process 2, 2', first and second disintegrating tanks 4, 4', sizing agents, paper strength enhancers, etc. are mixed with the raw material pulp to prepare first and second paper stock 10, 10'. It includes first and second blending tanks 5, 5', which are connected by transfer pipes 6, 6'. The first mixing tank 5 is a head box 7
The head box 7 faces above the belt 9' at one end of the wire part 9 consisting of an endless wire mesh belt 9', and supplies the stock 10 therein. The belt 9' runs counterclockwise in FIG. 1, and the other end of the wire part 9 contacts an endless pick-up felt belt 11. This belt 11 runs clockwise. On the other hand, the second blending tank 5' is connected to the circular mesh paper machine 13, and supplies the stock 10' to the filter tank 12. In the circular screen paper machine 13, a portion of the circular screen 13' is immersed in the paper stock 10', and its top is in contact with the pick-up felt belt 11. While traveling clockwise, the pickup felt belt 11 first picks up the paper layer 14 formed by the first stock 10 from the belt 9', and then picks up the paper layer 14 formed by the first stock 10, and then picks up the paper layer 14 formed by the first stock 10 from the belt 9'.
A paper layer 15 made of the second paper stock 10' is picked up from the paper layer 14 in a manner that it adheres to the paper layer 14. The wet paper web 16 consisting of the paper layers 14 and 15 formed on the pickup felt belt 11 is picked up by the felt belt 12 and then transferred to the surface of a dryer 17 where it is heated and dried to form two layers. The structured water-disintegratable paper 1 is rolled up and
This results in a roll of 18. Such a series of papermaking processes can be performed using well-known processes and equipment, and incidental equipment other than those described above may be added as appropriate. In this invention, in the first raw material preparation step 2, the amount of paper strength enhancer added is
The amount added is 5% or less on a dry weight basis, and in the second preparation step 2', the amount added is 10 to 60%. As a result, the wet paper 16 has a paper layer 14 containing a small amount of paper strength enhancer added to the drying tube 1.
It can be dried by contacting it with water. After drying, the paper layer 14 containing at most 5% paper strength agent is easily peeled off from the drying tube 17.

FIG. 2 is an enlarged side view of a portion A of the drying cylinder 17, showing a state in which the paper layer 14 of the wet paper web 16 is in contact with the drying cylinder 17. Incidentally, if the paper layer 15 of the wet paper web 16 is in contact with the drying cylinder 17, as the drying progresses, the paper layer 15 will strongly adhere to the drying cylinder 17, and subsequent peeling may become difficult or impossible. .

FIG. 3 is a schematic side view of a water-disintegratable paper 30 illustrating a usage mode of the water-disintegratable paper according to the present invention. In the figure (A), two sheets of water-disintegratable paper 1 according to the present invention are interposed between water-disintegratable tissue paper 33, the layer 35 containing a large amount of paper strength enhancer is the outermost layer, and the layer 34 containing less paper strength enhancer is the inner layer. It is integrated by embossing so that it faces towards the surface. In this way, both the outermost layers of the water-disintegratable paper 30 have high chemical solution impregnation strength. (B) in the figure shows the water-disintegratable paper 30 of (A) subjected to crepe processing, and by doing so, it is possible to give a supple feel to the water-disintegratable paper 30, which tends to be relatively thick.

Next, the multilayered handmade paper according to the present invention and a single layered handmade paper as a comparative example were produced in a process substantially comparable to the papermaking process described above, and the results of a comparative study of their properties are as follows. show. (Example 1) A first layer containing 30% by weight of sodium salt of carboxymethylated pulp with a degree of substitution of 0.4 and pH 6 and 70% by weight of bleached softwood kraft pulp, and 5% by weight of sodium salt of the same carboxymethylated pulp. % and a second layer containing 95% by weight of softwood bleached kraft pulp, a handmade two-layer paper with a basis weight of 30 g/m2 was produced with a weight ratio of the first layer and the second layer of 1:1. (Example 2) A first layer containing 60% by weight of a mixture of sodium salt and aluminum salt of carboxymethylated pulp with a degree of substitution of 0.4 and a pH of 6 and 40% by weight of bleached softwood kraft pulp, and a bleached softwood kraft pulp. A handmade two-layer paper with a basis weight of 30 g/m2 was produced by setting the weight ratio of the first layer and the second layer to 1:1. (Example 3) The first layer containing 25% by weight of water-soluble polyvinyl alcohol fibers and 75% by weight of bleached softwood kraft pulp was one of the outermost layers, and 10% by weight of the water-soluble polyvinyl alcohol fibers and 90% by weight of bleached softwood kraft pulp. A second layer consisting of 5% by weight of the same polyvinyl alcohol fiber and 95% by weight of softwood bleached kraft pulp is used as an intermediate layer.
A handmade multilayer paper was manufactured by stacking the first to third layers in order such that the third layer consisting of % by weight was the other outermost layer. The weight ratio of each layer is 1:1:1, and the overall basis weight is 30g/m2
And so. (Comparative Example 1) A handmade single-layer paper with a basis weight of 30 g/m 2 was produced using the same sodium salt of carboxymethylated pulp as in Example 1 at 20% by weight and bleached softwood kraft pulp at 80% by weight. (Comparative Example 2) The same polyvinyl alcohol as in Example 3 was
0% by weight and 80% by weight of softwood bleached kraft pulp,
A handmade single-layer paper with a basis weight of 30 g/m2 was produced. Example 1
Table 1 shows the results of evaluating the surface strength, water disintegrability (water dispersibility), and paper-making property when wetted by chemical impregnation for Comparative Examples 1 and 3 and Comparative Examples 1 and 2. Table 1 shows that the multilayer papers of Examples 1 to 3 exhibited almost the same performance in surface strength as the single-layer papers of Comparative Examples 4 and 5, and were superior in water disintegration (water dispersibility) and paper-making properties. It can be seen that it has excellent performance.

The evaluation method for each evaluation item is as follows. Surface strength (chemical impregnation strength) For a test paper impregnated with 50% propylene glycol aqueous solution in an amount twice the weight of the test paper, a smooth ABS resin sheet was applied over a distance of approximately 10 cm at a pressing force of 100 g/cm2 and a speed of 5 cm/sec. Scrub the surface in a reciprocating motion,
Evaluation was made as follows based on the number of reciprocations when the test paper was torn.

A: Breaks after 11 times or more B:
Breaks in 4 to 10 times C: Water disintegrability (water dispersibility) breaks in 3 times or less Pour 500 ml of tap water into a 1 liter beaker and rotate at 5 rotations.
A 5 x 5 cm test paper was added while stirring with a stirrer at 00 rpm, and the dispersion state after 1 minute was evaluated as follows.

A: Dispersion in the form of fibers B: Dispersion paper making with small fiber agglomerates Using a small rotary dryer, the outer layer of the test paper with less paper strength agent is in contact with the dryer.
After drying the wet paper of the test paper at a temperature of about 60 seconds, the peelability of the test paper from the dryer was evaluated as follows.

A: Easily peeled off B:
Slightly adheres but peels off C: Does not peel off

[0019]

[Table 1]

[0020]

[Effect] The water-disintegratable paper obtained as described above has a relatively small basis weight, and therefore, a wiping paper that is pliable and easy to handle can be obtained. Such wiping paper has high chemical impregnation strength in one outermost layer while exhibiting excellent water-disintegrability in the other outermost layer, and as a result, the water-disintegratable paper as a whole has good water-disintegrability. Such water-disintegratable paper can be easily produced by bringing the outermost layer containing relatively less paper strength enhancer into contact with a contact dryer.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a papermaking process for producing water-disintegratable paper.

FIG. 2 is a schematic enlarged view showing the positional relationship between the surface of the contact dryer and water-disintegratable paper.

FIGS. 3A and 3B are side views illustrating how water-disintegratable paper is used.

[Explanation of symbols]

1 Water-dissolving paper 14,15 Outermost layer 16 Wet paper 17 Dryer 10,10’ Paper stock

Claims (6)

[Claims] Claim 1: A water-disintegratable paper having a multilayer structure consisting of at least two layers, wherein one of the two opposing outermost layers of the water-disintegratable paper contains 10 to 60% by weight of a paper strength enhancer. ,
The water-disintegratable paper having a multilayer structure as described above, wherein the other outermost layer contains 5% by weight or less of a paper strength enhancer. 2. The water-disintegratable paper according to claim 1, wherein the paper strength enhancer is a salt of carboxymethylated pulp, water-soluble polyvinyl alcohol, water-soluble polyvinyl alcohol fiber, or a mixture thereof. 3. The carboxymethylated pulp salt according to claim 2, wherein the salt of the carboxymethylated pulp is a sodium salt or a mixed salt containing a sodium salt, and the degree of substitution thereof is from 0.2 to 0.6. Water-decomposable paper. 4. A method for producing a multilayered water-disintegratable paper comprising a step of drying a wet paper paper using a contact dryer, the first stock containing a paper strength enhancer in an amount of 10 to 60% by weight on a dry basis; A second paper stock containing a paper strength enhancer of 5% by weight or less on dry weight is multi-layered so that the first and second paper stocks each constitute the outermost layer of the wet paper web, and the second paper stock is The first and second paper stocks constitute the outermost layer of each of the water-disintegratable paper by drying the wet paper web made of paper stock as the contact surface for the contact dryer. A method for producing water-disintegratable paper. 5. The method for producing water-disintegratable paper according to claim 4, wherein the paper strength enhancer is a salt of carboxymethylated pulp, water-soluble polyvinyl alcohol, water-soluble polyvinyl alcohol fiber, or a mixture thereof. . 6. The carboxymethylated pulp salt according to claim 5, wherein the salt of the carboxymethylated pulp is a sodium salt or a mixed salt containing a sodium salt, and the degree of substitution thereof is from 0.2 to 0.6. A method for producing water-disintegratable paper.