JP3529374B2 - Paper sheet base material and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sheet-like substrate used for various purposes and a method for producing the same.

[0002]

2. Description of the Related Art A thin sheet material having a certain degree of rigidity and tensile strength is used as a sheet-shaped substrate in various fields. For example, a sheet material such as glass cloth is used as a base material for a printed wiring board. Many of such conventional sheet-shaped base materials are impregnated with a resin and have many merits, but on the other hand, the influence on the environment at the time of disposal is a problem. Papers made from vegetable fiber as a main raw material have a very low impact on the environment, regardless of the type of disposal. However, since thin paper has a weak stiffness and is easily torn, it is difficult to use it as a sheet-like base material for applications such as a printed wiring board. Thick papers (paperboards) can fulfill a function as a sheet-shaped substrate to some extent, but when stacked, the space occupancy rate becomes large, which is not preferable in many cases. By impregnating a paper as a base with a resin, a thin sheet-like base material having a required strength can be obtained and used as a laminated base material for a printed wiring board. But,
The impregnated resin may adversely affect the environment when the sheet-shaped substrate is disposed of.

[0003]

The present invention has been made against the background of the above-mentioned technical environment at present, and is a novel sheet-like base material without giving any consideration to the influence on the environment at the time of disposal. The purpose is to provide.

[0004]

Means for Solving the Problems The present inventor has conducted a great deal of research and experiment to obtain a sheet-like substrate which meets the above-mentioned object, and impregnates a commercially available paper with a starch solution and dries it. By laminating a plurality of those made, and simply pressing it under high temperature and high pressure, its tensile strength is greatly improved as compared with the case where starch is not impregnated and before pressing, and further, We have discovered the surprising fact that the rigidity is also improved. Although the reason for this is not clear, pressing at high temperature and high pressure causes the vegetable fibers to become entangled with each other between the surfaces of the laminated paper sheets, increasing the cohesive force, and further heating the starch impregnated on the thin paper. It is considered that the mechanical strength of the laminate is improved as a result of the addition of a bonding force when it is solidified again after being melted by.

The present invention is based on the above findings, and in the paper sheet-like base material according to the present invention, basically, two or more sheets of superposed thin paper are integrated so as not to be peeled by a high temperature and high pressure treatment. A sheet-like base material made of paper, characterized in that all or part of the laminated thin papers are thin papers that have been impregnated with starch in advance. The method for producing a paper sheet substrate according to the present invention is a method for producing a paper sheet substrate, which comprises subjecting two or more thin paper sheets to high-temperature and high-pressure treatment in a superposed state, A starch impregnated paper which has been impregnated with a starch solution and then dried is used as the whole or a part of the thin paper to be superposed, and at least a step of melting all or a part of the starch impregnated by the high temperature and high pressure treatment is required. .

In the present invention, the "thin paper" is an existing sheet-like paper made from vegetable fiber as a raw material, that is, a paper which is a commercial object as a thin paper made by a conventionally known method. , Is used as a material including all the materials, and a non-woven material is also included. Specific examples include newsprint, printing / information paper, wrapping paper, sanitary paper, and miscellaneous paper. The sanitary paper includes what are called tissue paper, dust paper, toilet paper, towel paper, and the like. Other hybrid papers include calligraphy paper and other household hybrid papers. These papers are distinguished from so-called "paperboard".

In the present invention, starch is defined as a natural polymer obtained from plant raw materials such as potato, corn and wheat, and any starch can be used as long as it is soluble in water. Well, there is no particular limitation. A commercially available starch is dissolved in warm water to prepare a starch solution having an appropriate concentration, and the thin paper described above is impregnated therein. In the experiments conducted by the present inventors, when the same type of thin paper was dipped in the starch solution for the same time, the thin paper impregnated with the solution having a high starch concentration was used as a paper sheet having higher tensile strength. It became the base material. Further, when the same type of thin paper was dipped in a starch solution of the same concentration, the thin paper used for a long impregnation time became a paper sheet-like base material having higher tensile strength.

In the present invention, at least two sheets of starch-impregnated paper, which have been soaked in the above-mentioned starch solution and then dried to a normal water content, are laminated without any particular humidification. Alternatively, the heating and pressurizing treatments are carried out in a state of being superposed with a thin paper that does not contain the same or another kind of starch. The thin paper impregnated with starch may be the same kind of thin paper or may contain different kinds of thin paper. The amount of starch impregnated in each of the laminated thin papers is preferably the same, but different thin papers may contain different amounts.

Heat and pressure treatment of a laminate of laminated thin paper impregnated with at least one starch, ie,
For high-temperature and high-pressure processing, the commonly known hot press (
It does not matter whether or not the mold is used). At that time, in order not to transfer the minute unevenness of the press plate surface to the paper sheet-shaped base material to be manufactured, and to make the load unevenness on the press plate surface uneven to the thickness of the paper sheet-shaped base material to be manufactured. It is preferable to dispose a heat-resistant resin sheet between the laminate and the surface of the press plate so as not to generate it and to further improve the releasability from the surface of the press plate. As the resin sheet, a film or sheet of polyethylene terephthalate (PET) resin, fluorine resin or the like can be used.

Depending on the type of thin paper to be laminated, some fibers have orientation. In such a case, it is preferable to stack the thin paper sheets such that the fiber directions are alternately crossed. In the experiment of the inventor of the present invention, it was possible to eliminate the deflectability of the mechanical strength (tensile strength, bending strength, etc.) of the manufactured paper sheet-shaped base material, and achieve averaging. The reason for this is presumed to be that the difference in the degree of entanglement between the plant fibers in each part acts so as to be suppressed as much as possible.

The high-temperature and high-pressure treatment conditions for the laminate are optional, provided that all or part of the impregnated starch can be melted, and as a result, the laminated thin papers can be integrated in a non-peeling manner. In the experiment of the present inventor, the treatment temperature was 120 ° C to 200 ° C, particularly 140 ° C.
It has been found that ~ 150 ° C is preferred. At 120 ° C. or lower, plasticization of the base material, that is, thin paper, and melting of starch are insufficient, and at 200 ° C. or higher, there is a risk of causing deterioration of the base material. The processing pressure is preferably in the pressure range of 20 MPa to 100 MPa, and at a pressure of 20 MPa or less, the processing time becomes long and it is difficult to integrate the layers.
When the pressure is higher than Pa, the melted starch may flow out from the surface of the press plate and may not be pushed into the small voids of the plasticized thin paper. Further, there is a possibility that the mold may be deformed, which is not preferable.

Further, the time required for the high temperature and high pressure treatment depends on the temperature and pressure, and requires a long time under the low temperature and low pressure,
Under high temperature and high pressure, it was possible to prepare a paper sheet-like base material having required physical properties in a shorter time as compared with the above. In actual processing, some sample products were adjusted to obtain a product with desired mechanical strength.
It is desirable to set the processing time.

In the experiments conducted by the present inventor, it was effective to carry out the pressure treatment in two stages. That is, by gradually increasing the pressure to, for example, about 20 MPa in the first stage, and rapidly increasing the pressure to about 100 MPa in the second stage, and maintaining the state for about 5 to 40 minutes, a short processing time can be obtained. , It was confirmed that a product with uniform mechanical strength throughout was obtained.

After the high-temperature and high-pressure treatment is completed, the product is taken out by cooling (natural cooling or forced cooling) and decompressing. The tensile strength of the product (paper sheet substrate) taken out is significantly improved compared to that of the laminate of thin paper before being put into the hot press, and the bending strength is also high. (For example, the difficulty of bending when holding one side and directing it in the horizontal direction) is also improved. How much the mechanical strength is improved depends on the type of thin paper used and the amount of starch to be impregnated. In an experiment conducted by the present inventor, papers such as tissue papers in which plant fibers are separated to some extent have a large improvement rate (improvement rate), and papers that have been subjected to a high degree of beating treatment, such as tracing papers, The improvement rate (improvement rate) was small. Therefore, it becomes extremely effective to apply the present invention to papers such as commercially available tissue papers in which plant fibers are separated to some extent.

[0015]

EXAMPLES The present invention will be described below with reference to examples. [Example 1] Six types of thin paper (commercially available tissue tissue, printing paper, cement bag, newspaper, calligraphy paper, and tracing paper) were used as a substrate.
Commercially available soluble starch (manufactured by Sigma-Aldrich Japan, manufactured by Nacalai Tesque) was dissolved in hot water at 80 ° C to adjust the concentration to 10%, and then the starch solution was cooled to room temperature under atmospheric pressure for 5 minutes. Impregnated. The impregnated test pieces were dried at 20 ° C. for 18 hours and returned to a normal water content, and four sheets were laminated for each starch-impregnated thin paper to prepare 6 kinds of laminates. At that time, the substrate thin paper having a high degree of fiber orientation was superposed so that the fiber directions were alternately crossed.

Each laminate was subjected to a high temperature and high pressure treatment using a conventionally known hot press. Figure 1
As shown in a, the PET sheet 12 is attached to the lower press plate 11.
Lay, place the laminate 13 on top of it, and then p
With the ET sheet 12 covered, as shown in FIG. 1b, the upper press plate 14 was lowered and the whole was pressure-bonded. In parallel, the press plates 11 and 14 were heated from room temperature to 150 ° C. Crimping is normal pressure to 20M for the first minute
The pressure was gradually increased to Pa, and then rapidly increased from 20 MPa to 100 MPa in 1 minute. Continue to 100
After standing for 20 minutes in the state of MPa and 150 ° C., the press plate was cooled with water to normal temperature, and the press plate was opened and decompressed.

After decompressing, the sheet-shaped paper base material was taken out, and the tensile strength was measured by a test method according to JIS K7113. Length 5 for pull test
Prepare a sample with a width of 0 mm and a width of 10 mm.
mm and hold it with the upper and lower grips, and test speed 10
The load (MPa) at the time of breaking was measured by pulling at mm / min. The results are shown in Table 1 and FIG. 2 as "starch impregnation" and "10% concentration starch impregnation press".
The weight increase rate in Table 1 indicates the weight increase rate after impregnation and drying with respect to the weight before starch impregnation.

[Comparative Example 1] The same 6 sheets of thin paper as in Example 1 were prepared by simply laminating only 4 sheets thereof. At that time, the substrate thin paper having a high degree of fiber orientation was superposed so that the fiber directions were alternately crossed. The tensile strength of the laminate was measured in the same manner as in Example 1. The results are shown in Table 1 and FIG. 2 as "No impregnation and no press".

[Comparative Example 2] The same six sheets of thin paper as in Example 1 were prepared by laminating only four sheets thereof. At that time, the substrate thin paper having a high degree of fiber orientation was superposed so that the fiber directions were alternately crossed. The laminate was subjected to the same high temperature and high pressure treatment as in Example 1. Regarding the paper sheet-shaped substrate obtained after the treatment,
The tensile strength was measured in the same manner as in Example 1. The results are shown in Table 1 and FIG. 2 as “With press without impregnation”.

[0020]

[Table 1]

[Discussion] As shown in Table 1 and FIG. 2, the tensile strengths of all six types of test specimens increased in the order of Comparative Example 1 <Comparative Example 2 <Example 1. It can be seen that the physical properties of the paper sheet-shaped base material according to the present invention are greatly improved. In particular, tissue paper has a large improvement rate. This means that the paper sheet-like base material produced according to the present invention can be used for various purposes (for example, without reinforcing resin by using paper basically).
It shows that it can be effectively used as a base material (for printed wiring boards).

[Embodiment 2] Four sheets of tissue paper were superposed and adjusted in the same manner as in Example 1, 5 and 1.
Each of the papers obtained after the treatment was impregnated with a starch solution having a concentration of 0, 15, 20% in the same manner as in Example 1 and dried, and then subjected to high temperature and high pressure treatment in the same manner as in Example 1. The same tensile strength as in Example 1 was measured for the sheet-shaped substrate. Also, for reference, thickness, density,
The rate of weight gain was also measured. The results are shown in Table 2 and FIG. In Table 2, the meaning of the weight increase rate is the same as in Table 1.

[0023]

[Table 2]

[Discussion] Here, when the same type of thin paper is soaked in the starch solution for the same time, the thin paper impregnated with the solution having a high starch concentration shows higher tensile strength. From this, it is shown that the paper sheet-like base material obtained by the present invention can be variously applied depending on the required strength while basically using paper.

[0025]

As described above, according to the present invention, it is possible to obtain a novel paper sheet-like base material without giving any consideration to the influence on the environment at the time of disposal.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a high-temperature and high-pressure treatment for a laminate of thin paper.

FIG. 2 is a bar graph showing the effect of paper type on tensile strength.

FIG. 3 is a graph showing the effect of starch concentration on tensile strength.

[Explanation of symbols]

11 ... Lower press plate, 14 ... Upper press plate, 12 ... PE
T sheet, 13 ... Laminate of thin paper

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-11-21794 (JP, A) JP-A-4-34096 (JP, A) JP-A-11-70630 (JP, A) JP-B 47- 51961 (JP, B1) JP-B 45-5726 (JP, B1) JP-B 45-25843 (JP, Y1) (58) Fields investigated (Int.Cl. ⁷ , DB name) D21H 11/00-27 / 42 B32B 1/00-35/00

Claims (3)

(57) [Claims] 1. Twelve or more laminated thin papers
Temperature condition of 0 to 200 ° C. and 20 MPa to 100 MP
A sheet-like base material made of paper, which is plasticized by a high-temperature and high-pressure treatment for holding for 5 to 30 minutes or more under a pressure condition of a and is laminated and integrated in a non-peelable manner. Oh in tissue paper but impregnated with pre-starch
, The starch impregnated on the thin paper was melted by heating.
After that, the binding force when solidifying again is added, and the tensile strength is increased.
A sheet-shaped base material made of paper, characterized in that its hardness and rigidity are improved as compared with those before high temperature and high pressure treatment . 2. The paper sheet-like base material according to claim 1, wherein the laminated thin paper is commercially available toilet paper and / or tissue paper. 3. A method for producing a paper sheet-like base material, which comprises subjecting two or more sheets of thin paper to a high-temperature and high-pressure treatment in an overlapping state, wherein a high-temperature and high-pressure treatment condition is 120.
~ 200 ° C temperature conditions and 20 MPa-100 MPa
Less condition to hold for 5 to 30 minutes or more under pressure condition
In addition , the starch paper impregnated with a starch solution and then dried is used as the whole or a part of the thin paper to be superposed , and at least a step of melting all or a part of the starch impregnated by the high temperature and high pressure treatment is required. A method for manufacturing a paper sheet-shaped base material, comprising: