JPH06192992A - Glassine paper and its production - Google Patents

Abstract

PURPOSE:To obtain glassine paper having excellent transparency and barrier properties, improved wet strength and other strength. CONSTITUTION:Glassine paper wherein a fibrous starch is packed into voids of a pulp fiber layer and the fibrous starch is in a bonded state in the contact face between the fibrous starch and the pulp fibers. A pulp fiber suspension is mixed with the ungelatinized fibrous starch, both the fibrous starch and the pulp fibers are gradually bonded at the contact face while making paper in a papermaking process to produce glassine paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glassine paper which has high transparency, is dense and has excellent wet strength, and a method for producing the same.

[0002]

2. Description of the Related Art Generally, glassine paper is a thin paper that is translucent through a super calender with a large number of steps to make it a high-density frosted glass by giving a suitable amount of water to paper made by viscous beating chemical pulp. It has similar transparency and is thinner than general paper, and is widely used in food packaging, drug packaging, laminated paper, etc. Unlike the so-called film, the glassine paper has a mesh-like entangled structure of wood pulp fibers, has pores of the order of microns, and has a function such as air permeability that the film does not have. Originally, cellulose itself is a highly transparent substance and has a transparency close to that of films such as cellophane.
In glassine paper, opacity is provided by the voids existing between the cellulose fibers. From the light refractive index, cellulose is 1.53, while air is 1.
Since it is 00, the difference becomes a factor that hinders transparency.

Therefore, conventionally, various methods have been adopted in order to remove the air contained in the glassine paper and improve the transparency. First, use softwood pulp rather than hardwood pulp as raw material pulp for glassine paper production, use sulphite pulp from kraft pulp, alkali pulp, and perform beating of pulp with strength, and air expulsion using a super calender. Therefore, measures such as increasing water, temperature, linear pressure, and hardness of calender rolls were made, but as a result, the mechanical strength of glassine paper was weakened, and the power cost was increased due to beating strength, and it was a good-quality transparent material. It was not possible to obtain glassine paper with high properties. In addition, it has been attempted to impregnate the paper layer with oils and fats and synthetic resins in various forms such as emulsions and solutions, but the image of the product is different, the material cost is high, and each processing step is different. There was a problem that the resin and the like adhered to the calender rolls and other equipment, and the amount of work required to prevent such trouble was also great.

Next, regarding transparency, cellophane paper in which cellulose is dissolved and regenerated has a density of 1.4, which is close to that of cellulose.
Whereas a 0~1.55g / cm ^3, glassine paper is a at 1.3 g / cm ³ or less, transparency will be the presence of air in much cellulose fiber interstices of the paper decreases naturally. Transparency is the absence of air in the glassine paper layer,
In addition, based on the finding that the substance is improved if it is filled with a substance having a photorefractive index equal to or close to that of cellulose, the present inventor has found that as a technique for substituting a substance having a property similar to that of cellulose, non-gelatinized starch granules are used. Has been proposed (Japanese Patent Publication No. 4-57798), and a method of filling cation-modified starch granules whose surface has been gelatinized by swelling into the voids of the pulp fiber.

[0005]

SUMMARY OF THE INVENTION In proposing the present invention, there are some problems, which will be described below. As a means for filling voids by starch of glassine paper,
When gelatinized starch is applied, the starch molecules are thinly adsorbed on the surface of the pulp fiber and only serve to bond the fibers, and the minimum amount of starch does not sufficiently fill the voids in the network structure of the pulp fiber. , Inefficiency for improving transparency.
On the other hand, the problem in paper production when starch is not gelatinized, that is, when it is added in the form of granules, is that the bond between starch granules and pulp fibers is extremely poor, and the yield of starch in the wet part, especially the wire part, is low, It is to break into white water. Further, a problem in paper production when adding cationized modified starch granules that are swollen and gelatinized only on the surface is that it is difficult to control the degree of swelling of the starch granules to an appropriate state. If the gelatinization of the starch is insufficient, the yield of the starch is poor, and if the gelatinization is excessive, the granules become liquid and the voids between the pulp fibers are insufficiently filled, which hinders the improvement of transparency.

Further, when the pulp fiber in the paper layer is replaced with starch (the amount of starch is increased), there is a problem that the strength of the wet paper at the wet end is lowered and a paper breakage problem is likely to occur. This invention enhances transparency by filling the voids in the paper with a starch material having a relatively close optical refractive index to that of the above-mentioned prior art, and further improves the binding strength between pulp fiber and starch to improve the wet strength. The problem is to reduce the yield due to falling off when using starch particles, and to improve the difficulty of swelling gelatinization, and take a step further to obtain high quality glassine paper with high transparency and wet strength. Is an issue.

[0007]

The structure of the present invention is such that the fibrous starch fills the voids of the pulp fiber layer, and
The glassine paper characterized in that the contact surface between the fibrous starch and the pulp fiber is in a bonded state, and the ratio of the fibrous starch in the glassine paper is 1 to 4 per pulp fiber.
A non-gelatinized fibrous starch is added to a suspension of glassine paper and pulp fiber, which is characterized by 0% by weight, and the fibrous starch is sequentially bonded at the contact surface with the pulp fiber in the papermaking process. The present invention relates to a method for producing glassine paper, which is characterized by making a paper.

[0008] Fibrous starch is produced by another prior art, and includes wheat, rice, potato, sweet potato, tapioca,
A solution prepared by dissolving various starches such as sago in an alkaline solvent,
It is formed into a fibrous form in air or liquid by means such as extrusion or blowing, or a starch solution is stirred to add a coagulant to form a fibrous form, or the starch solution is stirred to form a poor solvent. It was obtained by pouring the mixture into a fibrous aggregate. The obtained fibrous starch is
It is used as it is, or is cut or beaten if necessary, and in any case, when it is mixed with wood pulp, the average fiber diameter is 0.1 μ
A fiber having a length of 50 μm and a fiber length of about 0.2 to 3.0 mm is used. The cross-sectional shape of the fiber is not limited to a substantially circular shape, but may be a flat or polygonal shape.

In the present invention, the non-gelatinized fibrous starch mixed in the stock solution for papermaking maintains its state in the wire part, and the surface is swollen and gelatinized by the water heated in the subsequent drying step, It is preferable that the pulp fibers are sequentially connected in a dot-like or linear manner, and it is important that the central part of the fibrous starch firmly holds the original form of the fibers. The temperature control for swelling and gelatinization must be determined by the relationship with the transfer rate and the type of starch, which has a considerable effect on the transparency and wet strength of glassine paper, as shown in the following examples and table. Of. The fibrous starch whose surface is swollen and gelatinized and bonded has a water content of 10 to 10 at the final stage.
After being dried to about 25%, it is pressed by calendering to eliminate the air present in the paper layer, and because the optical refractive indices of the cellulosic material and the starch material are close to each other, the transparency is high and it is extremely excellent. It enables the production of quality glassine paper.

[0010]

The glassine paper has a structure in which fibrous starch forms a network entwined with pulp fibers and is bonded at the intersections and linear contact points between the fibrous starch and pulp fibers. The non-gelatinized starch fibers swell in the steps of papermaking, press dehydration, and hot air drying, and gradually bond at the contact points with pulp fibers. In super calendering, strong pressure is applied to crush the remaining voids inside the web to eliminate air and improve transparency.

[0011]

Example 1 Softwood bleached kraft pulp (NBKP) 10
10% by weight of fibrous starch having an average fiber length of 1 mm per pulp fiber was pulped to 0 to 50 cc by Canadian Standard Freeness with a PFI mill.
In addition, it was handmade to 30 g / m ² with a tappy standard machine and dehydrated with a press to obtain a wet paper with a water content of 65%. The tensile strength of this wet paper was 0.25 kg / 15 mm.
After drying the wet paper in a hot air dryer at 105 ° C., the humidity of the wet paper is adjusted in an atmosphere of 20 ° C. and 65% RH to obtain a linear pressure of 10
Transparency, tensile strength, and air permeability were measured using a sample pressed with a super calendar of 0 kg / cm as a sample.
The amount of starch in the paper is Tappi 419-OM-85.
And the yield data of starch were obtained. Hereinafter, all the results are shown in Table 1.

Example 2 The procedure of Example 1 was repeated except that 30% by weight of fibrous starch was added to the pulp fiber.

[0012]

Comparative Example 1 The procedure of Example 1 was repeated except that the pulp fiber alone was used without adding fibrous starch.

Comparative Example 2 The procedure of Example 1 was repeated except that corn granular starch was added in an amount of 10% by weight based on the pulp fiber instead of the fibrous starch.

Comparative Example 3 The procedure of Example 1 was repeated except that 30% by weight of corn granular starch was added to the pulp fiber instead of the fibrous starch.

Comparative Example 4 In the case where fibrous starch was used but the amount exceeded 50% by weight, the other procedure was carried out according to Example 1. The starch quality used in the above Examples and Comparative Examples is as follows. Fibrous Starch-Chart-Bi (Made by Italia Novamont) Granular Starch-Prince Ace A (Prince Corn Starch)

[0013]

[Table 1] Glassine paper compounding test

[2 in Table 1] Opacity: JIS-P-8138 Breaking length: JIS-P-8113 Air permeability: JIS-P-8117 Wet paper tensile strength: JIS-P-8135

[0014]

EFFECTS OF THE INVENTION By using fibrous starch, it is possible to significantly prevent the loss of starch content, improve the starch yield in glassine paper, and save costs and avoid troubles in drainage. In addition to the fact that the starch is fibrous and has consistency with the size of pulp fiber, it is sufficiently entangled, and not only can the overall strength of the paper be improved, but also the wet paper at the wet end of the papermaking process. Since the reduction of strength can be prevented, troubles in each process can be drastically reduced and smooth work progress can be achieved. And because it has excellent transparency and barrier properties as glassine paper, the texture of the paper is also improved, and the quality of the paper can be improved without unevenness of transparency due to texture unevenness, and it was possible to obtain glassine paper that can be used in a wide range of applications. is there. Therefore, it was possible to provide a product that is far superior to the conventional one and one step further than the one using the granular starch.

Claims (3)

[Claims] 1. A glassine paper characterized in that the fibrous starch fills the voids of the pulp fiber layer, and the fibrous starch is in a bonded state at the contact surface with the pulp fiber. 2. The glassine paper according to claim 1, wherein the proportion of the fibrous starch in the glassine paper is 1 to 40% by weight based on the pulp fibers. 3. A glassine characterized by blending ungelatinized fibrous starch with a pulp fiber suspension and successively binding the fibrous starch at a contact surface with pulp fibers in a papermaking process. Paper manufacturing method.