JP2003171891A - Papermaking belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a papermaking belt improved in releasability of wet paper, by destroying a water film formed between the wet paper and the papermaking belt. <P>SOLUTION: In this papermaking belt 1, many convexity- and concavity- forming components 3 comprising at least one kind of compound selected from a water-soluble inorganic salt, a highly water-absorbing resin, and a water-soluble polymer are dispersed in a papermaking side layer 2 composed of an elastomeric resin, such as polyurethane. Thus, an existing state of the water on the papermaking side surface 21 is changed by renewedly forming the convexities and concavities on the papermaking side surface 21 of the papermaking side layer 2, or by modifying characteristics of the papermaking side surface 21 of the papermaking side layer 2, so that the water film between the wet paper and the papermaking belt is destroyed, and further, the releasability of the wet paper is improved. Further, the belt has suitable hardness, because the concavity-forming components are dispersed in the papermaking side layer of the papermaking belt without being formed into hollows, so that durability and workability of the belt are not deteriorated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a papermaking belt, and more specifically to a papermaking belt having improved wet paper peeling property by destroying a water film formed between the wet paper web and the papermaking belt. For belts.

[0002]

2. Description of the Related Art Conventionally, in a papermaking process, a dehydrated wet paper web is received by a wire part, conveyed to a press part, further squeezed water between press rolls, and at the same time, the surface of the wet paper web is smoothed to produce a dry part. To send to
Papermaking belts are used. Then, in the conventional papermaking process, when the wet paper web that has gone through the press part is separated from the papermaking belt, a re-moisture absorption phenomenon occurs in which the moisture that has been transferred from the wet paper web to the papermaking belt is transferred again to the wet paper web by a capillary phenomenon,
Water extraction efficiency may decrease. Therefore, conventionally, a papermaking belt or the like made of a material having a low air permeability has been proposed in order to prevent such a re-moisture absorption phenomenon and prevent a reduction in water squeezing efficiency.

However, in the conventional papermaking belt, when the wet paper web is conveyed, a water film having a uniform thickness is formed between the wet paper web and the papermaking belt due to the moisture contained in the wet paper web. Sometimes. As a result, this water film adheres strongly to the papermaking belt, which lowers the peelability of the wet paper and causes a decrease in papermaking efficiency. In particular, when a material having a considerably low air permeability is used to prevent re-absorption of moisture, this water film is likely to be formed, and thus such a problem is likely to occur.

In order to prevent the peeling property of the wet paper web from decreasing, a concave or convex portion is provided on the surface of the paper making side, and the water film is destroyed by the concave or convex portion to improve the peelability of the wet paper web. Is being developed. For example, a papermaking machine in which a large number of protrusions are formed by dispersing a particulate filler having a hardness higher than that of a polymer elastic member such as kaolin clay, an inorganic material, or a metal in the polymer elastic member and projecting it onto the wet paper placement surface. Belts are known (JP-A-6-57678, etc.). Further, there is also known a papermaking belt in which microcapsules or air bubbles are mixed in a polymer elastic member, and innumerable recesses formed by cuts of microcapsules or traces of air bubbles are provided on a wet paper placement surface (Japanese Patent Laid-Open No. 2-212058).
001-89989).

However, when the particulate filler or the like is mixed in the elastic polymer member as described above, a relatively large amount of the particulate filler or the like must be mixed in order to improve the peelability. If there is a large amount, the hardness of the belt itself becomes high, and the durability may be reduced, or the weight of the belt may increase, which may hinder the work of putting the belt on the apparatus. Also, when microcapsules or air bubbles are mixed, since it is hollow, it becomes too flexible and it is difficult to sufficiently dehydrate by pressurizing, or it is difficult to smooth the surface of the wet paper, and the material of the microcapsules and On the contrary, depending on the mixing amount, there is a problem that it becomes too hard and durability deteriorates. Furthermore, when the papermaking belt is continuously used in the papermaking process, the surface of the papermaking side is worn due to the transport and dehydration of the wet paper, and the projections and depressions formed on the surface of the papermaking side become smooth. However, there is a problem that the releasability of the wet paper web decreases with time.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to remove a wet film by breaking a water film formed between the wet paper and the papermaking belt. An object of the present invention is to provide a papermaking belt having improved performance.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made earnest studies on the relationship between the construction of a papermaking belt and various properties such as releasability of wet paper. As a result, the papermaking surface side layer of the papermaking belt, by contacting the papermaking water contained in the wet paper,
By separating from the papermaking surface side layer and dispersing a large number of recess forming components capable of forming recesses on the papermaking surface of the papermaking belt, while achieving appropriate hardness, even if the papermaking surface is worn The present invention has been completed by finding that the concave portions can be renewed and formed to maintain the peelability of the wet paper web.

The papermaking belt of the present invention is characterized in that the papermaking surface side layer contains the irregularity forming component selected from at least one of water-soluble inorganic salts, superabsorbent polymers and water-soluble polymers in a dispersed manner. And Further, the paper-making side layer may be made of an elastic member or a hydrophobic resin.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings. The papermaking belt 1 of the present invention is
As shown in FIG. 1, a large number of concavo-convex part forming components 3 are dispersed in the papermaking side layer 2. And the above-mentioned uneven portion forming component 3
Is composed of at least one of a water-soluble inorganic salt, a super absorbent polymer, and a water-soluble polymer.

The water-soluble inorganic salt that can be used as the irregularity-forming component 3 is a water-soluble inorganic salt,
In particular, since the moisture contained in the wet paper is weakly acidic with a pH of 4 to 6, it is preferable to use an inorganic salt that is easily soluble in such weakly acidic water. When such a water-soluble inorganic salt is used, when the papermaking belt 1 of the present invention is continuously used, the papermaking surface side surface 21 of the papermaking surface side layer 2 is gradually worn away, so that the irregularity forming component 3 is obtained. Can be exposed on the surface to form a convex portion, and unevenness can be formed on the papermaking surface side surface 21 of the papermaking surface side layer 2. Further, the irregularity-forming component 3 which is the water-soluble inorganic salt is dissolved by the water contained in the wet paper to easily form the concave portion in the paper-making side layer 2. As a result, the unevenness is formed on the papermaking side surface 21 of the papermaking side layer 2 regardless of the worn state, and the water film formed between the papermaking belt and the wet paper is destroyed and the wet paper is peeled off. It is possible to improve the sex. Moreover, since the unevenness forming component 3 is not hollow, it has almost no influence on the physical properties such as the hardness of the papermaking surface side layer 2 as compared with a papermaking belt having air bubbles inside the papermaking surface side layer 2. Without doing so, it is unlikely to affect durability and workability.

Specific examples of the water-soluble inorganic salt include hydrochlorides such as potassium chloride, sodium chloride and calcium chloride, carbonates such as calcium carbonate, potassium carbonate and sodium carbonate, potassium hydrogen carbonate and sodium hydrogen carbonate. Examples thereof include hydrogen carbonate, hydroxide such as calcium hydroxide, and silicate such as calcium silicate and sodium silicate. Of these, calcium carbonate is a component used in the papermaking process, so even if dissolved, it does not affect the properties of the paper to be made, and the solution can be reused in the papermaking process. preferable. Moreover, it is preferable to use the above-mentioned porous inorganic salt such as porous calcium carbonate because it can be easily peeled from the paper-making side layer 2 by dissolution. The water-soluble inorganic salt is 1
They may be used alone or in combination of two or more.

When a water-soluble polymer is used as the irregularity-forming component 3, like the water-soluble inorganic salt, as a result,
The papermaking surface 2 of the papermaking layer 2 regardless of the wear state
1 can be provided with irregularities to destroy the water film formed between the papermaking belt and the wet paper web to improve the peelability of the wet paper web, and the physical properties such as hardness of the papermaking side layer 2 And the possibility of affecting durability and workability is low.
Moreover, since the dissolved water-soluble polymer is viscous, it tends to remain on the paper-making side surface 21 of the paper-making side layer 2. Then, as a result of drawing water in the vicinity where the dissolved water-soluble polymer remains, the water film formed between the papermaking belt and the wet paper is destroyed, and the peelability of the wet paper is further improved. be able to.

The above water-soluble polymer is not particularly limited as long as it is a water-soluble polymer, and may be a natural polymer or a synthetic polymer. In particular, as a paper-strengthening agent, a thickener or a paste, etc. With the water-soluble polymer used in the papermaking process,
Even if dissolved, it does not affect the quality of paper, and the solution can be reused in the paper making process, which is preferable. Specific examples of the water-soluble polymer include sodium polyacrylate (PAA), polyacrylamide, sodium salt of carboxymethoxycellulose (CMC-Na), A
M / AA copolymer etc. are mentioned. As the water-soluble polymer, the water-soluble polymer itself may be dispersed and contained in the paper-making side layer 2, but may be dispersed and contained by being coated with an appropriate coating substance. The coating is preferable because it can be easily dispersed in the paper-making side layer 2. The above-mentioned coating substance is usually urethane,
Examples include nylon-based elastomers and olefin-based elastomers. In particular, it is preferable to use a hydrophobic one because it can be more easily dispersed in the papermaking side layer 2.

When a highly water-absorbent resin is used as the uneven portion forming component 3, the convex portion is formed by absorbing the water contained in the wet paper and swelling, so that the convex portion is formed between the papermaking belt and the wet paper. It is possible to improve the releasability of the wet paper by destroying the water film of the paper, and further swelling makes it easier to peel from the papermaking surface side layer 2. As a result, the papermaking surface is affected before the surface smoothness is affected. It is preferable because the wet paper web can be peeled off from the side layer 2 to form a concave portion, thereby improving the peelability of the wet paper web. Further, like the water-soluble polymer, water existing on the paper-making side surface 21 of the paper-making side layer 2 is easily attracted, and due to this action, it is formed between the papermaking belt and the wet paper web. The water film can be destroyed to further improve the peelability of the wet paper web.

The highly water-absorbent resin is not particularly limited as long as it has a property of expanding when absorbing water, and specifically, for example, cellulose-based, acrylic-based,
Examples thereof include polyvinyl alcohol-based, acrylamide-based, polyoxyethylene-based, and polyurethane-based resins.

Further, the shape, size, etc. of the unevenness forming component 3 are not particularly limited as long as the wet paper can be kept peelable. The shape of the concavo-convex part forming component 3 may be, for example, in the form of particles as shown in FIG. 1, or in a substantially hemispherical shape, a substantially conical shape, a substantially rectangular shape, or an irregular shape. It is preferable that the irregularity-forming component 3 has a particulate shape because it is possible to suppress deterioration of the surface smoothness even when exposed on the paper-making side surface of the paper-making side layer. When made into particles, the diameter thereof is usually 2 to 80 μm, preferably 2 to 50 μm, and more preferably 5 to 10 μm.
The thickness of 2 μm or more is preferable because the influence on the paper manufacturing process can be reduced and the peelability due to the destruction of the water film can be further improved. Further, when the thickness is 80 μm or less, it is possible to suppress the formation of line marks on the surface of the paper made by papermaking, which is preferable.

The recess-forming component 3 may be used singly as long as it is at least one of the above-mentioned water-soluble inorganic salt, superabsorbent resin and water-soluble polymer, or two or more thereof may be used. You may use together. Further, the number of the recess forming components 3 in the papermaking belt of the present invention is not particularly limited, and various numbers can be provided as necessary. Usually, it is 50 or more, preferably 100 or more, and more preferably 200 or more per 1 cm ² . The above range is preferable because the peelability of the wet paper due to the destruction of the water film can be further improved.

The paper-making side layer 2 is not particularly limited in material as long as it can convey wet paper, and may be made of various materials as necessary.
It is preferably composed of an elastic member. When the paper-making surface side layer 2 is formed of an elastic member, it is possible to prevent re-absorption of water that has been transferred from the wet paper to the paper-making surface side layer 2 during pressing, to the re-absorption of water. . Further, during the pressing, the concave portion 4 formed on the papermaking surface side surface 21 of the papermaking surface side layer 2 is pushed down by the pressure and the elastic action of the elastic member during the pressing, and the concave portion 4 is closed and the above The surface of the papermaking surface side layer 2 is in a substantially flat state, which can prevent deterioration of the surface smoothness, and physically acts between the papermaking belt and the wet paper web by the elastic action when returning to the original shape after pressing. It is preferable because the water film formed between them can be destroyed and the peelability of the wet paper can be enhanced.

The material of the elastic member is not particularly limited as long as it has elasticity, and normally, it can be selected from various resins such as rubber and elastomer. In particular, when a hydrophobic elastic material such as polyurethane resin or olefin elastomer is used, water film formation is prevented by aggregating the moisture between the wet paper web and the papermaking belt, and the wet paper release property is further improved. It is possible because it is possible.

The papermaking belt 1 of the present invention is not limited in its structure as long as it has the papermaking side layer 2. Usually, it is a multi-layer structure having a plurality of layers made of other materials, but if necessary, it may be a single-layer structure made of a single elastic member as shown in FIG. Further, a fabric layer or a felt layer formed by weaving warp and weft or arranging warp or weft is used as a base member, and the base member is impregnated with and filled with an elastic member to form the papermaking side layer. You can also do it. With such a configuration, the papermaking belt 1 of the present invention can be reinforced, which is preferable.

The present invention is not limited to the specific examples described above, and various modifications can be made according to the purpose and application. For example, if necessary, the papermaking belt 1 of the present invention can be used as a smooth surface for the papermaking surface side surface 21 of the papermaking surface side layer 2 by polishing the surface before use.

[0022]

EFFECTS OF THE INVENTION The papermaking belt of the present invention comprises a specific unevenness forming component in the papermaking surface side layer so that the unevenness portion is renewed and formed on the surface of the papermaking surface side layer. The water film formed between the belt and the wet paper can be destroyed to improve the peelability of the wet paper. Further, by using a specific unevenness forming component, the surface state of the papermaking surface side layer is modified to change the state of water present, and a water film formed between the papermaking belt and the wet paper web. Destroy the
The peelability of the wet paper can also be improved. Further, the papermaking surface side layer of the papermaking belt of the present invention has an appropriate hardness because the recess forming component is dispersed without having a hollow, and the durability and workability are deteriorated. There is no.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a papermaking belt of the present invention.

[Explanation of symbols]

1; papermaking belt, 2; papermaking surface side layer, 21; papermaking surface side surface of papermaking surface side layer, 3;

Claims (3)

[Claims] 1. A papermaking belt, wherein the papermaking surface side layer contains a concavo-convex portion-forming component selected from at least one of a water-soluble inorganic salt, a superabsorbent polymer and a water-soluble polymer. 2. The papermaking belt according to claim 1, wherein the papermaking side layer is composed of an elastic member. 3. The papermaking belt according to claim 1, wherein the papermaking side layer is made of a hydrophobic resin.