JPH02125791A - Paper for confidential postcard and preparation thereof - Google Patents

Abstract

PURPOSE:To obtain paper for a confidential postcard mutually and temporarily adhered without using an adhesive and easily released by dehydrating a paper stock containing 5-95 pts.wt. of a polyethylene fiber and 95-5 pts.wt. of a natural plant fiber and applying specific heat treatment to said stock to form such a structure that fibers are entangled mutually. CONSTITUTION:A polyethylene fiber and a natural plant fiber are contained in a ratio of 5-95 pts.wt. and 95-5 pts.wt. Further, in order to enhance the smoothness and printability of paper for a confidential postcard and to increase the whiteness thereof while preventing strike through, for example, a filler and a flocculant can be contained. The dehydration of a paper stock containing the polyethylene fiber and the natural plant fiber as well as the formation and drying of a paper layer are performed by a known papermaking machine. Next, taken-up base paper 12 is arranged to the take-up shaft of a oven type heat processing machine and passed through a heating oven 14 at a speed of 40m/min while heated to 220 deg.C equal to or higher than the softening point of the polyethylene fiber by the irradiation with infrared rays and taken up by a take-up reel 15 to prepare paper for a confidential postcard.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to confidential postcard paper, and more specifically, the present invention relates to confidential postcard paper, which is temporarily bonded to each other by heating and pressure treatment, and is easily bonded after the temporary bonding. This invention relates to confidential postcard paper that can be peeled off and its manufacturing method.

<Prior Art> Conventionally, sealed letters and the like have been used as advertising means for product sales, etc., or as notification means in financial institutions such as banks, in order to keep the contents of the mail secret, even down to the addressee. However, as the number of mail items that need to be kept confidential has increased, various methods have recently been developed to conceal the contents using postcards, which are cheaper in postage than sealed letters.

However, in order to be treated as a postcard, the entire surface of the postcard must be attached in a removable manner, so in order to hide the content written on conventional postcards, the postcard itself must be multi-layered and adhesive A method of temporary adhesion in a releasable manner has been proposed.

However, this method requires steps such as adhesive application and processing, and is economically disadvantageous. Furthermore, it is necessary to perform printing before applying the adhesive, and there is also the disadvantage that the surface coated with the adhesive tends to collect dust and is difficult to handle. Therefore, it is desired to develop confidential postcards that do not require adhesives.The main purpose of the present invention is to develop confidential postcards that can be temporarily attached to each other without using adhesives and that can be easily peeled off. Our objective is to provide paper and its manufacturing method.

Another object of the present invention is to provide confidential postcard paper that allows printing on the adhesive surface and does not damage the printed surface when peeled off, and a method for manufacturing the same.

Still another object of the present invention is to provide a confidential postcard paper whose writing range is more than twice that of conventional postcards, and a method for manufacturing the same.

Means for Solving the Problems> According to the present invention, there is a confidential postcard paper that can be temporarily adhered to each other by heating and pressurizing treatment and can be peeled off after the temporary adhesion, and the paper is made of polyethylene fibers. 5 to 95 parts by weight of polyethylene fibers and 95 to 5 parts by weight of natural vegetable fibers, and is characterized by a structure in which the softened polyethylene fibers retaining their fiber shape and natural vegetable fibers are intertwined with each other. Confidential postcard paper will be provided.

According to the present invention, a paper material containing 5 to 95 parts by weight of polyethylene fibers and 95 to 5 parts by weight of natural vegetable fibers is dehydrated to form one paper layer, and then heated during or after drying. In producing flexible postcard paper having a structure in which the polyethylene fibers and the natural vegetable fibers are intertwined with each other, the heat treatment is performed at a temperature equal to or higher than the softening point of the polyethylene fibers. A method for manufacturing postcard paper is provided.

The present invention will be explained in more detail below.

The flexible postcard paper of the present invention contains polyethylene fibers and natural plant fibers as essential components, and has a structure in which the softened polyethylene fibers and the natural plant fibers are intertwined with each other while retaining the shape of the fibers. By overlapping the flexible postcard papers of the present invention and heating and pressurizing them at a specific temperature and pressure, the overlapping polyethylene fibers of each other are moderately softened and the overlapping surfaces are temporarily bonded. It is. In addition, before the heating and pressure treatment, it has no adhesive ability at all and is similar to ordinary paper, so it is easy to write secret information on the mutual surfaces that are to be temporarily bonded. is possible. Furthermore, after temporary adhesion and peeling work, there is no adhesion ability at room temperature, so there is no risk of dust or the like attaching.

The polyethylene fibers used in the present invention include low pressure polyethylene, medium pressure polyethylene, high pressure polyethylene, etc.
For example, it can be obtained by extrusion melt spinning.

Further, the natural plant fibers include, for example, wood fibers such as coniferous trees and hardwoods, seed wool fibers such as cotton and kapok, saniot, etc.
m, bast fibers such as gampi, mulberry, jute, flax, hemp, potato hemp, ramie, leaf fibers such as manila hemp, sisal hemp, and rice straw;
Preferably, the fiber is selected from one or more of the group consisting of fibres, such as rice hull, bamboo, bagasse, and esparto.

The content ratio of the polyethylene fiber and natural vegetable fiber is
5 to 95 parts by weight of polyethylene fiber, 95 to 95 parts by weight of natural vegetable fiber
The range is 5 parts by weight. If the polyethylene fiber is less than 5 parts by weight and the natural vegetable fiber is more than 95 parts by weight, temporary adhesion will not be possible when heat and pressure treatment is performed, and the polyethylene fiber will not be usable as a confidential postcard. If the amount exceeds 95 parts by weight or if the amount of natural vegetable fibers is less than 5 parts by weight, the adhesion becomes strong and difficult to peel off when heat and pressure treatment is performed, and peeling is not possible. For example, the printing may peel off at the same time, making it difficult to see the written contents.

In the present invention, in addition to the polyethylene fibers and natural plant fibers, the smoothness and printability of 1i-extended postcard paper are improved,
For example, fillers, flocculants, etc. may be included in order to increase the whiteness and prevent bleed-through. Examples of the filler include calcium carbonate, magnesium carbonate, calcium/magnesium carbonate, silicates, silicic acid, aluminum hydrate, barium sulfate, calcium sulfate, calcium sulfite, titanium dioxide, and zinc pigments.
It is preferable to select from one species or two or more species. The content ratio of the filler is preferably in the range of 0 to 40 parts by weight with respect to 100 parts by weight of the total content of polyethylene fibers and natural vegetable fibers, and when it exceeds 40 parts by weight, the content of the paper This is not preferable because the strength decreases. Examples of the flocculant include aluminum sulfate, polyethyleneimine, cationic starch, aluminum hydroxide, ferric sulfate, ferrous sulfate, ferric chloride, basic aluminum chloride, zinc chloride, and sodium aluminate. The content of the flocculant, which is preferably selected from one or more of the group consisting of If the amount exceeds 5 parts by weight, the aggregation between the fibers becomes large and the texture of the paper becomes non-uniform, which is not preferable.

In producing the flexible postcard paper of the present invention, air bubbles are generated on the surface of the produced flexible postcard paper of the present invention at the raw material stage in preparing polyethylene fibers and natural plant fibers. 1. It is preferable to mix and disperse polyethylene fibers and natural plant fibers so as not to impede surface smoothness. As a method for mixing and dispersing, polyethylene fibers are preferably mixed and dispersed using a stirrer such as a pulper. The polyethylene fibers are dispersed in water by circulating water at 5 to 60° C. for 30 to 90 minutes, and the natural vegetable fibers are stirred with a stirrer such as a pulper, washed, and then treated with a refiner to obtain the above-mentioned By mixing dispersed polyethylene fibers and natural fibers,
Each fiber can be dispersed. At this time, it is also possible to add a filler, a coagulant, etc., if necessary. Next, more preferably, the mixed solution of the polyethylene fiber and natural vegetable fiber is adjusted to a uniform concentration, and an antifoaming agent such as silicone, ester compound, paraffin, wax, mineral oil type, polyalkylene type, etc. And/or after adding a polyethylene-based, wax-based, silicone-based dryer release agent, etc., dust removal treatment is performed to reduce each fiber to a concentration of 0.1 to 0.
Mixed to 5%.

Dispersion is desirable.

In the present invention, in order to manufacture confidential postcard paper, paper raw materials containing polyethylene fibers and natural plant fibers are dehydrated to form a paper layer, and then dried to form base paper for confidential postcard paper. Can be done. The dehydration, paper waste formation and drying can be carried out using a known paper machine such as a cylinder paper machine or a Fourdrinier paper machine. Sensitive postcard paper can be produced by heat-treating the polyethylene fiber at a temperature higher than its softening point. It is also possible to perform the heating by the thermal processing machine using a paper dryer of a paper machine. Here, the thermal processing machine may be separated from the paper machine or may be integrated with the paper machine. Furthermore, the temperature above the softening point is a temperature at which the polyethylene fibers retaining their fiber shape are compatible with other polyethylene fibers and natural resin fibers in contact with them, and the polyethylene fibers are not completely dissolved, that is.

Polyethylene fibers can be blended with other polyethylene fibers and natural plant fibers by heating them at a temperature above their softening point. This is a state in which the sheets are in contact with each other more strongly than in the untreated state, and the strength between sheets is increased, and the temperature is such that the printing will not be damaged in any way when it is temporarily attached and peeled off as a confidential postcard. At this time, if the heating is below the softening point.

This is not desirable because it cannot be temporarily bonded as a confidential postcard, and it will completely adhere when temporarily bonding at temperatures above the softening point.Also, if the polyethylene resin fibers are completely dissolved, the polyethylene fibers and natural vegetable fibers will not bond together. This is not preferable because the intertwined structure cannot be maintained and is completely adhered during temporary adhesion, making peeling difficult.

4 To use the confidential postcard paper of the present invention 1 For example, when stacked, cut it to the specified postcard size, write an article on the paper, and then remove the written part that should be kept confidential. The overlapping portions can be temporarily bonded by overlapping the sheets of paper and applying heat and pressure at a temperature equal to or higher than the softening point of the thermoplastic resin fibers so that the sheets are hidden.
Next, after temporary adhesion, the overlapped portions can be peeled off with fingers or the like, so that they can be easily peeled off without damaging the surface. In addition, during the overlapping process, by providing a portion of the end portion that does not overlap, the peeling operation can be performed more easily.

<Effects of the Invention> The confidential postcard paper of the present invention can be temporarily bonded by simply heating and pressurizing it without using an adhesive, and before the heating and pressurizing process, Since it is similar to regular paper, it is extremely easy to print articles. Furthermore, there is no risk of damaging the printed surface during peeling, and since all adhesive action is lost at room temperature after peeling, no dust or the like will adhere to the printed surface. Furthermore, the confidential postcard paper of the present invention is
Since they are used in combination, articles can be written on both sides of one overlapping section. In other words, even though the content is more than twice that of a conventional postcard, it can be used at the postage rate of a regular postcard, making it extremely economical. It is hoped that it will be used in place of confidential envelopes. Further, according to the manufacturing method of the present invention, confidential postcard paper having the above-mentioned advantages can be easily obtained.

<Examples> The present invention will be described in more detail below with reference to Reference Examples and Examples, but the present invention is not limited thereto.

Mouth side - As natural plant fibers, 50 parts by weight of bleached softwood kraft pulp was put into a pulper, stirred, roughly washed, and subjected to refiner treatment. Separately, 40 parts by weight of high-pressure polyethylene fiber and 60 parts by weight
1,333 parts by weight of warm water at ℃ was added thereto, and circulation was performed for 1 hour to disperse the polyethylene fibers. Next, the refined natural vegetable fibers and the dispersed polyethylene fibers are added to a blended bocher, and 3 parts by weight of titanium dioxide and 3 parts by weight of aluminum sulfate are added and mixed,
Each fiber was dispersed. Next, the concentration of the obtained mixed solution was adjusted to 0.4% fiber using a 'a preparation machine, and then 0.05 parts by weight of Pronal as an antifoaming agent and 0.02 parts by weight of Meiriki Lux as a dryer stripping agent. parts by weight were added.

Then after removing dust.

A raw material solution was prepared by dispersing each fiber at a fiber concentration of 0.3% based on the entire raw material.

A raw material solution was prepared in the same manner as in Reference Example 1, except that 96 parts by weight of the bleached softwood raft valve and 4 parts by weight of polyethylene fiber were used.

l (4 parts by weight of bleached softwood craft pipe, 9 parts by weight of polyethylene fiber)
A raw material liquid was prepared in the same manner as in Reference Example 1 except that the amount was 6 parts by weight.

Dear Kantanesa, Next, embodiments of the confidential postcard paper of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram of a circular mesh paper machine, in which a circular mesh 4 was rotated while the raw material liquid 2 prepared in Reference Example 1 was flowed out from a pipe 1 into a sand tank 3. By rotating the circular mesh 4,
A liquid level difference occurs between the inside and outside of the circular mesh 4, water pressure is applied to the part of the circular mesh 4 that is submerged in the raw material liquid 2, water flows out from the outside to the inside, and fibers remain on the mesh surface. When the circular mesh 4 comes out of the raw material liquid 2, the mesh of the mesh is covered with a textured paper layer, and by pressing the couch roll 3, the paper waste sticks to the felt 6 on the couch roll 5, and the adhesive The paper waste was dehydrated in a suction box 7 using a vacuum pump to a concentration of about 20%. The dewatered paper layer is further dehydrated by the press roll 8, and is automatically transferred to the upper felt by the suction pickup device, and then the transferred paper layer is
The film was transferred to a touch roll 9 and attached to a Yankee dryer 10 to be dehydrated and dried to about 6%. The pasting can be carried out by blowing steam into the inside of the Yankee dryer 10 to bring the mirror-finished surface to 110°C, and by pressing the paper layer against the Yankee dryer 10 with a touch roll 9.The paper layer is then dried. The paper layer was wound up by a winding reeler 11 to produce a winding base paper 12.

Next, the winding base paper 12 was placed on a winding shaft 13 of an oven-type thermal processing machine shown in FIG.

The roll paper 12 enters the heating furnace 14 at a speed of 40 m/min, and is passed through the heating furnace 14 while being heated to 220° C., which is above the softening point of polyethylene, by infrared irradiation. The base paper 12 that has passed through is wound up by the winding roller 15. A-exhibition postcard paper was manufactured.

Next, the obtained confidential postcard paper was cut into 20×15 an size as shown in FIG. 3a, and then printed. Next, as shown in Figure 3b, overlap the confidential postcard papers so that the printed surface is hidden inside, and add the non-overlapping part 2 to the left end.
0 was formed. The stacked confidential postcard paper is 18
When heating and pressurizing at 0° C. and 4.8 kg/d for 2 seconds, one overlapping printed surface was adhered. After that, when the adhesive surface was peeled off from the non-overlapping portion 20,
No damage was observed on the printed surface.

Comparison (2) Confidential postcard paper was produced in the same manner as in Example 1, except that the raw material solution prepared in Reference Example 2 was used, and temporary adhesion and peeling tests were conducted. As a result, it was found that although temporary adhesion was achieved, the adhesive strength was weak and it peeled off quickly, making it unusable for confidential postcard paper.

Confidential postcard paper was produced in the same manner as in Example 1, except that the raw material liquid prepared in Reference Example 3 was used, and temporary adhesion and peeling tests were conducted. As a result, during temporary adhesion, the adhesive strength was strong and peeling was difficult. In addition, when it was strongly peeled off,
It turned out that the printing peeled off at the same time, making it impossible to use it as confidential postcard paper.

Confidential postcard paper was produced in the same manner as in Example 1, except that the heat treatment using the thermal processing machine shown in FIG. 2 was not performed, and temporary adhesion and peeling tests were conducted. the result.

It was found that the printing peeled off at the same time as the paper was peeled off, making it impossible to use it as confidential postcard paper.

Confidential postcard paper was produced in the same manner as in Example 1, except that the heat treatment using the heat processing machine shown in Figure 2 was carried out at 100°C, which is below the softening point of polyethylene fibers, and temporary adhesion and peeling tests were carried out. I did it. As a result, it was found that the paper adhered completely and could not be used as confidential postcard paper.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a cylinder paper machine used in an embodiment of the present invention, Fig. 2 is a schematic diagram of an oven-type thermal processing machine used in an embodiment of the present invention, and Fig. 3a is . FIG. 3b is a diagram showing an example of the use of the confidential postcard paper of the present invention, and is a diagram showing a stacked state of the confidential postcard paper of the present invention. 4. Circular net, 5. Couch roll, 8. Press roll, 9. Touch roll, 10. Yankee dryer, 1
1. Winding-up, 12.. Rolling base paper, 14.. Heating furnace, 20.. Non-overlapping portion. patent author

Claims (1)

[Scope of Claims] 1) A confidential postcard paper that can be temporarily adhered to each other by heating and pressurizing and peeled off after the temporary adhesion, comprising 5 to 95 parts by weight of polyethylene fibers; A sensitive postcard paper comprising 95 to 5 parts by weight of natural vegetable fibers, and having a structure in which the softened polyethylene fibers retaining the shape of the fibers and the natural vegetable fibers are intertwined with each other. 2) The sensitive postcard paper according to claim 1, further comprising a filler and a flocculant. 3) A paper material containing 5 to 95 parts by weight of polyethylene fibers and 95 to 5 parts by weight of natural vegetable fibers is dehydrated to form a paper layer, and then heated during or after drying, In producing a flexible postcard paper having a structure in which the polyethylene fibers and the natural plant fibers are intertwined with each other, the heat treatment is performed at a temperature equal to or higher than the softening point of the polyethylene fibers. Law. 4) The method for producing sensitive postcard paper according to claim 3, wherein the paper raw material contains a filler and a flocculant.