JPS6059196A - Production of paper containing humidity control agent - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a paper containing iron chloride at constant humidity using a paper machine for making ordinary paper and paperboard.

Traditionally, paper and paperboard (generally impregnated with chemicals)
Hereinafter referred to as paper. ) in order to uniformly impregnate the chemicals.
It has been manufactured by using water-absorbing paper, impregnating it in a secondary process using a processing machine, and drying it. Not only does this secondary processing increase costs, but once ordinary paper is dried during the papermaking process and turned into a product, the fibers become keratinized and contain sizing agents, which makes it difficult to absorb chemicals. Especially the basis weight is 1009/n? In the case of the above-mentioned thick papers, it is difficult to uniformly impregnate the entire paper layer with chemicals, so paper quality paper such as sizeless blotting paper or F paper is used; It had low rigidity and was not suitable for processing such as printing and box making, so it could only be used for special purposes.

In recent years, it has become increasingly desirable to store and transport various chemicals, foods, and other industrial products at a certain desired constant relative temperature, especially fresh foods such as fruits and vegetables, and flowers. At present, various measures are taken to prevent drying during transportation. In other words, since it is not possible to actually store and transport the product at the desired relative humidity, it is better to puncture it immediately after production to prevent moisture from dissipating or absorbing moisture, or to keep it in a state with less moisture than to absorb moisture. Preferred, but unsatisfactory, packaging has been achieved with desiccant products such as silica gel.

It is generally known that chemicals that are solid and have the property of dissolving in water exhibit a water vapor partial pressure characteristic of that aqueous solution in the state of a saturated solution. Glass desiccators and other devices have been used to create containers with constant humidity to store various products and chemicals, but these chemicals have not been used in actual packaging. is the current situation.

In view of the current situation, and as a result of various studies, the present invention aims to create a constant humidity condition anywhere by uniformly impregnating paper with chemicals and supplying moisture that saturates the impregnating chemicals. It has now become possible to manufacture a sheet that can do this, leading to the present invention.

In other words, when paper that has been made into a product through a drying process in the papermaking process is used to impregnate chemicals, the fibers become keratinized as described above and the absorption of chemicals is poor. Paper that has been beaten and made by adding sizing agents and the like has poor water absorption, and it is difficult to uniformly impregnate it with an aqueous solution of chemicals in a short period of time. For this reason, we considered impregnating chemicals in the papermaking process, and as a result, in the middle of the drying process, when the moisture content of the wet paper ranges from 15 to 45% by weight, the chemical solution is uniformly dispersed and absorbed over the entire paper layer. It turned out that it would be done.

In addition, in order to make wet paper impregnated and dried with chemicals to a saturated state by adding water and to prevent the solution from seeping out of the paper, the water retention Ji of the paper and the content of chemicals are issues. Become.

In general, the water retention capacity of paper refers to the total amount of bound water that binds to the paper fibers, adsorbed water that is adsorbed to the fibers, and retained water that maintains the interfiber pressure. let it absorb,
When excess water is removed by applying a pressure of about 51 v'cn for about 3 minutes with a press, that is, when water drops do not fall from the paper when the paper returns to normal condition, the amount of water contained is defined as the water retention amount. Ta.

In order to measure the water retention rate of various boats under these conditions, the analytical filter paper tsubo @ 90 f/rr? It is 146 heavy duty, strong size Gagaku Shitsubo J) 150 t/d is 149
The weight percent was 173 weight percent at a white paperboard basis weight of 295 f/rd.

Also, from this, if the water retention rate of paper is set to 140 f# for safety reasons, then if the amount of water required to form a saturated solution of the chemical to be impregnated is known, the amount of impregnation for that chemical can be determined. Become.

In other words, the amount of chemicals that can be claimed is A1 Paper fiber (pulp) i! ' is W2 If the chemical content is B weight l2, then in order to prevent water from seeping out of the paper, the water ratio of the chemical should be 1 (, and if the water retention rate of heavy paper is C weight width, then AR≦WC・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・■ is sufficient. Therefore, ■,■
From the formula, B≦□ ×100・・・・・・・・・・・・・・・(3
)C+R If C=140, it is possible to determine the addition rate of the chemical more.

Any chemical can be used as a humidifying agent as long as it has a known water vapor partial pressure when made into a saturated aqueous solution, but the relative humidity, vapor pressure, and
Table 1 shows those for which the chemical concentration is known.

It should be noted that chemicals that have the property of absorbing moisture in the air and deliquescing when left in the air can also act as a desiccant if used in a dry state, so do not use paper other than humidity-controlled paper. It is also possible to use it as a dryer, so the scope of application is wide.

Table 1 The papermaking pulp used in the production of the constant-humidity side content paper according to the present invention is wood pulp commonly used for papermaking, that is, wood pulp of Japanese pine tree, hardwood, and other papermaking pulps. If it is a natural fiber to be used as pulp (=1 may be used, but from the viewpoint of strength and quality, at least 10% of the weight of the raw material pulp is blended with Senba tree pulp, and the raw material pulp is slightly beaten. The freeness should be approximately 500 cp or less (according to JIS, P, 8121 pulp furnace water measurement method), and if too much sizing agent is added, the water absorbency of the paper itself will deteriorate, so It is best to use a weak size with a gravity factor of about 0.1.

The target basis weight of paper, that is, the basis weight of paper made only from pulp fibers, is preferably as large as possible in order to improve the moisture absorption effect, and is preferably 200 t/n? It is desirable that there be at least one.

Therefore, in order to impregnate thin paper with chemicals, it is possible to add a solution to it using a press before entering the drying process, or use a size press during the drying process.
Thick 100 f/'tr? Above, special K 200 f/r
r? It has been found that the best way to uniformly impregnate paper with a chemical solution is to immerse the paper in the solution.

Hereinafter, the present invention will be explained according to examples.

Example 1 The chemical used was calcium chloride, which had a relative humidity of 32.3% in a saturated solution at a temperature of 20°C, and the raw materials were mixed and adjusted as shown in Table 2. It was impregnated in the paper machine during the drying process and dried.

Note that calcium chloride becomes CaCt at a temperature of 30°C or lower.
, -6H,0 and hexahydrate, CaC1°・2 at 100℃
It is said that the dihydrate of H,0 is in a stable state, and the moisture content of paper is measured after drying at a temperature of 100° to 105°C, so the dihydrate of calcium chloride, CaC4.2H,
Calculated as 0. Calcium chloride has hygroscopic and deliquescent properties, but when it is impregnated into paper, the relative humidity in the air is 1 (
Since it is estimated that the water absorption rate will not exceed 210% by weight even if it becomes 10%, the ratio of water in calcium chloride, R = 210, is calculated using the following formula, B≦ It becomes 40. In other words, the limit of calcium chloride content is:
Since it is 40 weight i%, it is sufficient if it is less than that.

In this embodiment, economical efficiency is also taken into consideration; 4. v, L,
, a trial paper was made with a target weight of 20.

Table 2 shows softwood kraft pulp, LBKP.

2. The sizing agent and sulfuric acid band were shown as the addition rate to the pulp as the solid content of the rosin size, and the addition rate to the pulp as the solid content of the sulfuric acid band.

3. Freeness is measured by J-Ko S, P after beating the pulp of each blending ratio according to the conventional method.

The results are shown in the results measured according to 8121.

4. The target weightage is shown in the weightage number when the paper is made with only a sizing agent and a sulfuric acid band added to the pulp and dried.

The chemical impregnation conditions and measurement results are shown in Table 3.

Note 1. The basis weight was expressed as a basis weight including moisture after drying.

2. The chemical content was calculated from the bone dry basis weight of the paper stock alone before impregnation and the bone dry basis weight after impregnation, and the chemical was calculated as calcium chloride trihydrate.

3. All centimeters widths are expressed as weight ratios.

The resulting calcium chloride-impregnated paper was left in a room with a lagoon of 120 DEG C. and a relative humidity of 65 DEG C. In each case, the moisture content was 25 to 32% by weight, indicating that it was hygroscopic. The measurement results of humidity stability were conducted using Sample 2, and are summarized in Table 5VC of Example 2.

Example 2 As impregnation chemicals, potassium acetate CH3C(χ)K, potassium carbonate, CO, iron chloride FeCz, and sodium chloride NaCt were used. The raw material composition is A of Example 1.
The same conditions as No. 2 were used. That is, pulp composition N
BKP 50% LBKP 50% Sizing agent 0.04 inch (for pulp) Aluminum sulfate 1 width (r) Note 1. (HJ is also expressed in terms of weight.

The freeness of the pulp after beating is 450 c, c, and the absolute dry basis weight of the pulp alone before chemical impregnation is 27.
The paper was made so that it became 0η-.

Table 4 Note 1. (self-directed) shows regret.

2. The moisture content of the wet paper at the time of chemical impregnation was 30%.

3. Measurement of product tsubo 1vl (absolutely dry), temperature 105℃
I did it. Therefore, K, CO,, FeC4 is 100℃
Here, ~cow -3/2H,0, FeCz, -2-〇, and the respective eigenhite are shown as ten, and and ~ were calculated as anhydrous.

The obtained sheet was cut into circles with a diameter of 50 WLtn, each placed in a 500-volume sealed container, dried completely in a dryer at 105°C, and after cooling in the usual manner, the basis weight was determined. After adding the required amount of distilled water to each container so that the chemicals were saturated, the containers were sealed and left in a room at a temperature of 20°C for about 2 hours, and the relative humidity inside the container was measured, as shown in Table 5. It shows the relative humidity of chemicals.

Table 5 Note 1. (2) indicates A2 of Example 1.

2. Relative humidity was measured using a capacitive hygrometer.

Furthermore, among the obtained sheets, potassium acetate, potassium carbonate, and iron chloride are hygroscopic, so the absolute dry sheet was placed in a sealed container, and after about 24 hours, the relative humidity inside the container was measured. The results showed that it can also be used as a moisture absorbent material.

Claims (1)

[Claims] In the process of making paperboard using paper pulp as the main raw material, wet paper is dried to a moisture content of 15 to 45% by weight, impregnated with an aqueous solution of a humidity stabilizer such as iron chloride, and then the moisture of the impregnated paper is reduced by 10% by weight. A method for producing paper containing a constant humidity side, which is characterized by drying the paper to a constant humidity level.