JP2019183317A - Aramid pulp paper - Google Patents

Abstract

To provide aramid pulp paper dissolved in a hindrance factor even when a content of aramid pulp is larger than 90 wt.% and suitable for use.MEANS FOR SOLVING THE PROBLEM: Aramid pulp paper containing 90 wt.% or more of aramid pulp having a microfibril structure is provided. This makes it possible to provide aramid pulp paper having a surface smooth to such an extent as visually recognizing no air bubbles even when a content of the aramid pulp exceeds 90 wt.%.SELECTED DRAWING: Figure 1

Description

The present invention relates to paper using aramid pulp and a method for producing the paper.

Conventionally, paper using aramid and a method for producing the paper are known. Paper using aramid has received high acclaim for its excellent heat resistance, and has properties such as lightness, high strength, good dimensional stability, and non-conductivity. Yes.

In addition, since the aramid pulp having a microfibril structure among aramids is produced by beating the aramid fibers, the applicant has a more flexible fiber and a strong bond between fibers during drying. We thought that the resulting effect could be obtained.

Patent Document 1 exists as an invention of paper using both aramid fibers and aramid pulp.

JP2016-223021

In Patent Document 1, an aramid paper formed from a mixture of a fibrid formed from an aromatic polyamide and short fibers, and an aramid paper having a fibrid content and thickness satisfying the following inequalities (1) and (2): (Claim 1). “Fibrid” here means aramid pulp (paragraph [0006]).
40 ≦ [FB] ≦ 90 (1)
[Thickness] / ([Fiber diameter of short fiber] × 2) ≦ 1.25 (2)
[Wherein [FB] is the fibrid content (% by weight) in the aramid paper]

However, in the invention according to Patent Document 1, “if the (fibrid content) exceeds 90% by weight, the content of the short fibers is relatively reduced, and the hot pressure is sandwiched between at least a pair of heating elements described later. The shrinkage rate of the aramid paper after processing exceeds 3%, and the increase in thickness due to shrinkage makes it difficult to have a thickness in the range of the above formula (2) ”(paragraph [0008]). , Pointing out the obstruction factors when the aramid pulp is greater than 90% by weight, it is explicitly excluded from the subject of the invention.

An object of the present invention is to provide an aramid pulp paper suitable for use since the obstruction factor is eliminated even when the aramid pulp is larger than 90% by weight.

In order to solve the above problems, the present invention provides an aramid pulp paper containing 90% by weight or more of an aramid pulp having a microfibril structure.

As a second invention, in addition to the above features, an aramid pulp paper in which the aramid pulp is para-aramid or / and meta-aramid is provided.

As a third invention, an aramid pulp-containing raw material preparation step for preparing an aramid pulp-containing raw material beaten with aramid short fibers, an aramid pulp raw paper generation step for producing an aramid pulp base paper by papermaking the generated aramid pulp-containing raw material, Aramid pulp comprising a low temperature heating step for heating the produced aramid pulp base paper at a temperature relatively lower than the heating temperature described later, and a high temperature heating step for heating at a temperature relatively higher than the heating temperature of the low temperature heating step A method for producing paper is provided.

As 4th invention, the aramid pulp containing raw material preparation process which prepares the aramid pulp containing raw material which beaten the aramid short fiber, the aramid short fiber preparation process which prepares an aramid short fiber, and the prepared aramid pulp containing raw material were prepared. A mixing process for preparing an aramid pulp-containing raw material by mixing aramid short fibers, an aramid pulp base paper generating process for producing an aramid pulp base paper by producing a mixed aramid pulp-containing raw material obtained by mixing Production of aramid pulp paper comprising a low temperature heating step for heating the aramid pulp base paper at a temperature relatively lower than the heating temperature described later, and a high temperature heating step for heating at a temperature relatively higher than the heating temperature of the low temperature heating step Provide a method.

As 5th invention, the aramid short fiber preparation process which prepares an aramid short fiber, the aramid pulp containing raw material production | generation process which beats the prepared aramid short fiber and produces | generates an aramid pulp containing raw material, and the produced aramid pulp containing An aramid pulp base paper production process for producing aramid pulp base paper by making a raw material, a low temperature heating process for heating the generated aramid pulp base paper at a temperature relatively lower than a heating temperature described later, and a heating temperature of the low temperature heating process A method for producing an aramid pulp paper comprising a high-temperature heating step of heating at a relatively higher temperature than the above.

Furthermore, in addition to the features of the third to fifth inventions, there is provided a method for producing an aramid pulp paper in which the aramid pulp paper is para-aramid or / and meta-aramid. Further, the aramid pulp-containing raw material production step provides a method for producing an aramid pulp paper containing 90% by weight or more of aramid pulp in the produced aramid pulp-containing raw material.

According to the above invention, even when the aramid pulp is larger than 90% by weight, the obstruction factor is eliminated, and a paper suitable for use can be provided. The effect inherent in containing a large amount of aramid pulp paper is described in paragraph [0054] and subsequent paragraphs.

Structural formula of para-aramid Structural formula of meta-aramid The figure which shows an example of an aramid short fiber Diagram showing an example of aramid pulp Fig. 1 shows the state of bubbles in aramid pulp paper FIG. 1 is a flowchart showing a manufacturing method according to the present invention. Diagram showing tensile strength according to processing conditions Figure 2 shows the state of air bubbles in aramid pulp paper FIG. 2 shows a flowchart of the manufacturing method of the present invention. FIG. 3 shows a flowchart of the manufacturing method of the present invention.

Hereinafter, an embodiment for carrying out the present invention will be described. It should be noted that the present invention should not be construed as being limited to the embodiments described below.

<Configuration of aramid pulp paper>
The aramid pulp paper of the present invention is an aramid pulp paper containing 90% by weight or more of an aramid pulp having a microfibril structure. “Microfibril” refers to a state of being attached to a fiber and having a width smaller than the diameter of the main (stem) portion of the fiber and a micro or sub-micro level. It has excellent characteristics that cannot be obtained artificially. In addition, “containing 90% by weight or more of aramid pulp” includes the case of 100% by weight of aramid pulp, but in other cases, it may contain less than 10% by weight of aramid fiber. Aramid short fibers have excellent heat resistance. When an aramid fiber is used, an aramid fiber having a fiber diameter in the range of 1 μm to 30 μm and a fiber length in the range of 1 mm to 10 mm is desirable. In addition, it may be nylon (here, it means nylon when used separately from aramid fiber). Nylon is weak in heat resistance, but since the resistance of the fiber itself is strong, it is not affected by oils, molds, insects, bacteria, etc., and can be strong against acids and alkalis. Alternatively, carbon fiber may be used. If it is carbon fiber, in addition to excellent heat resistance, it is lightweight and strong, and also has good electrical conductivity, excellent electromagnetic shielding properties, excellent X-ray transparency, etc. It has the features of

In the following, “aramid” refers to two types of meta-aramid and para-aramid. Unless otherwise specified, these two kinds of arbitrary ones are meant and not limited to any one.

FIG. 1 is a structural formula of para-aramid. The molecular skeleton is characterized by being linear throughout. It has the characteristics of high tensile strength and elastic modulus and excellent heat resistance.

FIG. 2 is a structural formula of meta-aramid. The molecular skeleton is characterized by a zigzag shape as a whole. Although tensile strength and heat resistance are inferior to para-aramid, it is excellent in workability.

As these aramids, there are aramid fibers and aramid pulp produced by beating the aramid fibers. The term “beating” as used herein means a process in which fibers are fluffed by applying mechanical shearing force or concentric loosening is given to increase the flexibility of the fibers and strengthen the bond between fibers during drying. . This beating promotes fiber branching. The beating method classically includes placing the fiber on a hitting board and hitting it with a stick, but from the viewpoint of efficiency, it is more preferable that the fiber suspension is placed in the space where the gears are arranged. (Slurry) is circulated and beaten with a gear, or a fiber suspension (slurry) is uniformly fed into the beating space and beaten by the action of two rotating blades and a fixed blade. Conceivable.

FIG. 3 is an example of an enlarged view of an aramid fiber. FIG. 4 is an example of an enlarged view of aramid pulp. It is clear that the aramid pulp (0401) is more loosely branched than the aramid fiber (0301).

By using aramid pulp, the following effects can be obtained. However, when the aramid pulp content exceeds 90% by weight, there is a demerit that the thickness of the paper finally obtained increases. As a factor of increasing the thickness, bubbles are generated in the manufacturing process.

FIG. 5 is a diagram showing the bubble generation state of paper when the content of aramid pulp exceeds 90% by weight and according to a normal manufacturing method. It can be seen that a large amount of bubbles are generated. This cannot withstand use as paper.

The present invention makes it possible to produce an aramid pulp paper that has a smooth surface and does not generate bubbles even when the content of the aramid pulp exceeds 90% by weight, by producing by the following production method. did. In addition to the production method described below, the present invention includes an aramid pulp paper obtained thereby.

<Manufacturing method>
The method for producing an aramid pulp paper according to the present invention comprises an aramid pulp-containing raw material preparation step for preparing an aramid pulp-containing raw material beaten with aramid short fibers, and an aramid for producing an aramid pulp base paper by papermaking the generated aramid pulp-containing raw material Pulp base paper generation step, low temperature heating step for heating the generated aramid pulp base paper at a temperature relatively lower than the heating temperature described later, and high temperature heating step for heating at a temperature relatively higher than the heating temperature of the low temperature heating step Is a manufacturing method comprising: Since there can be other manufacturing methods, the manufacturing method is hereinafter referred to as “manufacturing method 1”.

FIG. 6 is a diagram showing a flowchart of the steps in the manufacturing method 1. The production method 1 includes an aramid pulp-containing raw material preparation step (S0601), an aramid pulp base paper generation step (S0602), a low temperature heating step (S0603), and a high temperature heating step (S0604).

The “aramid pulp-containing raw material preparation step” is a step of preparing an aramid pulp-containing raw material in which aramid short fibers are beaten. The beating method is as described above.

The “aramid pulp base paper generation step” is a step of making aramid pulp base paper by papermaking the generated aramid pulp-containing raw material. As a papermaking method, a suspension (slurry) in which aramid pulp raw material is dispersed in water is made, and the suspension is made on a wire (net) to form a sheet, which is then dried with a rotary dryer. The so-called wet papermaking method is preferably selected. As the paper machine, general equipment used in the production of paper pulp and wet nonwoven fabric can be used, and is not particularly limited. As for the production conditions in the paper machine, the production rate is desirably 5 to 100 m / min, and the drying temperature is desirably 105 to 135 ° C.
Aramid purple base paper generally has a basis weight in the range of 5 to 200 g / square meter, preferably 30 to 110 g / square meter. Moreover, in the preferable range of basic weight, it becomes the range of thickness 50-400 micrometers.

The “low temperature heating step” is a step of heating the generated aramid pulp base paper at a temperature relatively lower than the heating temperature described later. The heating assumes heating by a so-called calendar processing machine.

The “high temperature heating step” is a step of heating at a relatively higher temperature than the heating temperature of the low temperature heating step. It is assumed that this high temperature heating process is usually a process after the low temperature heating process. The heating here is also assumed to be heating by a so-called calendering machine.

≪Effect of passing through two-stage heating process of low temperature heating process and high temperature heating process≫
The production method of the present invention is characterized in that it undergoes a two-step heating process of high-temperature heating after low-temperature heating, as compared with a normal production method. Therefore, in the following, the effect of undergoing such a two-step heating process will be described.

First, “low temperature” in the first stage means that the temperature is higher than that in the high-temperature superheating process, but it is about 210 degrees Celsius, that is, in the range of 180 degrees to 230 degrees Celsius, and more preferably 205 degrees Celsius to 215 degrees Celsius. Desirably within a range of degrees.

Next, “high temperature” in the second stage means that the temperature is relatively higher than that temperature. The “high temperature” in the second stage is produced under this high temperature condition although it can withstand use as paper without generating bubbles if it is within the range of 240 to 290 degrees Celsius. Since the tensile strength of paper is different, it is desirable that the tensile strength is within a high range.

FIG. 7 is a diagram showing a comparison of tensile strength when the “high temperature” heating condition in the second stage is changed. The conditions for the first stage low temperature heating are all at 210 degrees Celsius, but the relationship with the tensile strength when the conditions for the second stage high temperature heating are changed should be (a) 210 degrees Celsius. For example, 0.9N / mm, (b) If there is 250 degrees Celsius, there is no bubble, but the tensile strength is 1.05 N / mm, and (c) If it is 280 degrees Celsius, there is no bubble and the tensile strength is 1. 7 N / mm. Therefore, even if it is within the range of 240 to 260 degrees Celsius, there is no bubble and it can be used as paper, but it is more desirable from the viewpoint of tensile strength, preferably about 280 degrees Celsius, specifically, Celsius. It is desirable to be within the range of 270 to 290 degrees, more specifically within the range of 275 to 285 degrees Celsius.

The processing speed of each heating step is preferably in the range of 1.5 to 60.0 m / min for both the first stage and the second stage. When the processing speed is slow and the heating time is long, sticking to the hot roll occurs. On the other hand, when the processing speed is high and the heating time is short, foaming occurs on the sheet surface. Further, although not essential, it is desirable to cool the temperature once until it returns to room temperature between the first stage heating and the second stage heating, and then shift to the second stage heating. By returning to room temperature at intervals, it is possible to prevent the temperature of the paper from rising excessively and to prevent adhesion to the heat roll of the calendar processing machine in the second heating step.

By passing through the two-step heating process at the above-described temperature, air can escape to the outside by the heating in the first step, so that there is an effect that bubbles are hardly generated.

FIG. 8 is a diagram showing the state of bubbles generated in the aramid pulp paper produced by the production method of the present invention when the aramid pulp content exceeds 90% by weight. It can be seen that the surface is smooth and no bubbles are present. Such an aramid pulp paper has not existed in the conventional manufacturing method.

<Deformative manufacturing method for obtaining the same product as the above manufacturing method>
Unlike the manufacturing method described above, an aramid pulp-containing raw material preparation step for preparing an aramid pulp-containing raw material beaten with aramid short fibers, an aramid short fiber preparation step for preparing aramid short fibers, and a prepared aramid pulp-containing raw material A mixing step of mixing the prepared aramid short fibers to prepare an adjusted aramid pulp-containing raw material, an aramid pulp raw paper generating step of producing an aramid pulp base paper by papermaking the adjusted aramid pulp-containing raw material obtained by mixing, Aramid pulp paper comprising a low temperature heating step for heating the produced aramid pulp base paper at a temperature relatively lower than the heating temperature described later, and a high temperature heating step for heating at a temperature relatively higher than the heating temperature of the low temperature heating step. The manufacturing method may be used. Hereinafter, such a manufacturing method is referred to as “manufacturing method 2”.

FIG. 9 is a diagram illustrating a flowchart of the steps in the manufacturing method 2. Production method 2 includes an aramid pulp-containing raw material preparation step (S0901), an aramid short fiber preparation step (S0902), a mixing step (S0903), an aramid pulp base paper generation step (S0904), and a low-temperature heating step (S0905). And a high temperature heating step (S0906).

The “aramid pulp-containing raw material preparation step” is a step of preparing an aramid pulp-containing raw material in which aramid short fibers are beaten. The contents of this step are the same as in manufacturing method 1.

The “aramide short fiber preparation step” is a step of preparing an aramid short fiber. The fiber length of the aramid short fibers is desirably 1 mm or more and 30 mm or less, specifically, desirably within a range of 2 mm to 10 mm, and more desirably within a range of 3 mm to 6 mm.

The “mixing step” is a step in which the prepared aramid pulp-containing raw material is mixed with the prepared aramid pulp-containing raw material to obtain an adjusted aramid pulp-containing raw material. The ratio of the content of the aramid short fiber and the aramid pulp in this step is from 0.1% to 9.9% by weight for the aramid short fiber, whereas from 90.1% by weight for the aramid pulp. It is desirable to be within the range of 99.9% by weight. In the case of the above-described two-stage overheating process, which will be cited later, even if such content, bubbles do not occur to some extent to hinder the use as paper, and on the other hand, they exhibit excellent effects such as heat resistance. Because.

“Aramid pulp base paper production process” is a process for producing aramid pulp base paper by making a raw material containing an adjusted aramid pulp obtained by mixing. It is the same as the “pulp base paper production process”, except that the raw material is an adjusted aramid pulp-containing raw material obtained by mixing.

The “low temperature heating step” and the “high temperature heating step” are the same as in the manufacturing method 1.

The manufacturing method 2 as described above also exhibits the same effect as the manufacturing method 1.

<Manufacturing method 3>
Unlike the above manufacturing method, an aramid short fiber preparation step for preparing an aramid short fiber, an aramid pulp-containing raw material generation step for producing an aramid pulp-containing raw material by beating the prepared aramid short fiber, and the generated aramid pulp An aramid pulp base paper producing step for producing an aramid pulp base paper by making a raw material, a low temperature heating step for heating the produced aramid pulp base paper at a temperature relatively lower than a heating temperature described later, and heating in the low temperature heating step An aramid pulp paper manufacturing method comprising a high-temperature heating step of heating at a relatively higher temperature than the temperature may be used. Hereinafter, such a manufacturing method is referred to as “manufacturing method 3”.

FIG. 10 is a diagram illustrating a flowchart of the steps in the manufacturing method 3. Production method 3 includes an aramid pulp short fiber preparation step (S1001), an aramid pulp-containing raw material preparation step (S1002), an aramid pulp base paper generation step (S1003), a low temperature heating step (S1004), and a high temperature heating step (S1005). ).

In the production method 3, the difference from the production methods 1 and 2 is an “aramide pulp short fiber preparation step”. The “aramide pulp short fiber preparation step” is a step of preparing an aramid short fiber. In the “aramid pulp-containing raw material generation step”, the prepared aramid short fibers are beaten to generate an aramid pulp-containing raw material. The subsequent steps are to produce the aramid pulp base paper by making the aramid pulp-containing raw material (the aramid pulp base paper generation step), and heat the generated aramid pulp base paper at a temperature relatively lower than the heating temperature described later. (This is the same in the sense that the heating is performed at a relatively higher temperature than the heating temperature of the low-temperature heating step and the low-temperature heating step (high-temperature heating step).

Also by the manufacturing method 3 as described above, the same effects as the manufacturing methods 1 and 2 are exhibited.

<Details of the above manufacturing method>
Regarding the above production methods 1 to 3, the aramid pulp to be used is preferably para-aramid or / and meta-aramid. The structural formulas of para-aramid and meta-aramid are as described above.

Moreover, it is desirable that the aramid pulp-containing raw material generation step contains 90% by weight or more of aramid pulp in the generated aramid pulp-containing raw material.

By the above production method, even when the aramid pulp content exceeds 90% by weight, it is possible to produce aramid pulp paper having a smooth surface and no visible bubbles.

0301: Aramid fiber 0401: Aramid pulp

Claims (7)

  Aramid pulp paper containing 90% by weight or more of aramid pulp having a microfibril structure.   The aramid pulp paper according to claim 1, wherein the aramid pulp is para-aramid or / and meta-aramid. An aramid pulp-containing raw material preparation step of preparing an aramid pulp-containing raw material beaten from aramid short fibers;
An aramid pulp base paper production process for producing aramid pulp base paper by papermaking the raw material containing aramid pulp;
A low-temperature heating step of heating the produced aramid pulp base paper at a relatively lower temperature than the heating temperature described later;
A high temperature heating step of heating at a relatively higher temperature than the heating temperature of the low temperature heating step;
A process for producing an aramid pulp paper comprising: An aramid pulp-containing raw material preparation step of preparing an aramid pulp-containing raw material beaten from aramid short fibers;
An aramid short fiber preparation step of preparing an aramid short fiber;
A mixing step in which the prepared aramid pulp is mixed with the prepared aramid pulp-containing raw material to prepare an adjusted aramid pulp-containing raw material;
An aramid pulp base paper producing step for producing an aramid pulp base paper by making a paper containing an adjusted aramid pulp-containing raw material obtained by mixing;
A low-temperature heating step of heating the produced aramid pulp base paper at a relatively lower temperature than the heating temperature described later;
A high temperature heating step of heating at a relatively higher temperature than the heating temperature of the low temperature heating step;
A process for producing an aramid pulp paper comprising: An aramid staple preparation process for preparing an aramid staple,
An aramid pulp-containing raw material production step of beating the prepared aramid short fibers to produce an aramid pulp-containing raw material;
An aramid pulp base paper production process for producing aramid pulp base paper by papermaking the raw material containing aramid pulp;
A low-temperature heating step of heating the produced aramid pulp base paper at a relatively lower temperature than the heating temperature described later;
A high temperature heating step of heating at a relatively higher temperature than the heating temperature of the low temperature heating step;
A process for producing an aramid pulp paper comprising:   The method for producing an aramid pulp paper according to any one of claims 3 to 5, wherein the aramid pulp paper is para-aramid or / and meta-aramid.   The said aramid pulp containing raw material production | generation process is a manufacturing method of the aramid pulp paper as described in any one of Claims 3-6 which contains 90 weight% or more of aramid pulp in the produced | generated aramid pulp containing raw material.