JPS62223391A - Reinforcing agent for paper, cardboard and corrugated board and processed paper, cardboard and corrugated board - 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 Field of the Invention The present invention relates to a reinforcing agent for paper, paperboard, and corrugated board, and to paper, paperboard, and corrugated poles treated with the reinforcing agent.

(Prior Art) Conventionally, paper strength enhancers for paper and paperboard, particularly compressive strength improvers, have been used to improve the strength of paper and paperboard. It is also known to be added internally to paperboard or applied to the surface.

However, when using these compressive strength improvers, 1
Depending on the use of paper and paperboard, there are drawbacks such as difficulty in bonding with adhesives afterwards, and limitations in improving compressive strength.

In addition, in recent years, there have been proposals to improve the compressive strength of corrugated cardboard by coating or impregnating an alkali metal silicate such as sodium silicate on the inner and inner core of the corrugated cardboard.
In issue 66947.

A method for producing corrugated poles in which the compressive strength of the corrugated core paper is improved by applying or impregnating at least one side of the core paper of the corrugated board with an alkali metal silicate such as sodium silicate was further disclosed in JP-A-59-130398. discloses a composition for improving the stiffness (compressive strength and cracking prevention) of paper, which is a mixture of water glass and a polymer emulsion or latex.

However, alkali metal silicates such as sodium silicate.

When coated or impregnated on the surface of paper, its stickiness may cause problems with adhesion to heating rolls after applying the reinforcing agent during the corrugated board manufacturing process, or blocking may occur in paper rolled up after applying the reinforcing agent during the paper manufacturing process. Therefore, even if a polymer emulsion or latex is blended with the above-mentioned sodium silicate, problems such as roll adhesion and blocking cannot be solved.

In order to solve this problem, the inventor filed a patent application in
No. 010 and No. 60-88957 proposed a reinforcing agent for paper, paperboard, and corrugated board made by adding an anionic sulfate ester salt type surfactant to an alkali metal silicate.

On the other hand, paper, paperboard, and single-corrugated cardboard treated with alkali metal silicate have significantly improved strength than those without treatment in a normal atmosphere (standard condition), but in a high-humidity atmosphere (
When exposed to K (high humidity), the strength decreases and the effect of the reinforcing agent is almost negated.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned drawbacks of alkali metal silicate salts.

That is, the one-stage pole reinforcing agent for paper and paperboard of the present invention improves the hygroscopicity of the alkali metal silicate by adding boric acid, borate, and borax to the alkali metal silicate.
The purpose of the present invention is to provide paper, paperboard, and cardboard processed with a reinforcing agent that is coated or impregnated with a reinforcing agent that exhibits less strength loss even under high humidity.

In addition, the present invention uses an anionic sulfate ester salt type surfactant in combination with the alkali metal silicate in order to simultaneously solve the other drawbacks of the alkali metal silicate, such as roll adhesion or blocking due to stickiness. This is very valid.

Note that Japanese Patent Application Laid-Open No. 57-669 disclosed in the above-mentioned prior art
The detailed explanation in Publication No. 47 exemplifies boric acid, which has a slow reaction rate, as an acid to be mixed with the aqueous alkali metal silicate salt solution, and states that the combined use of an acid has the effect of improving the compressive strength and waterproofness of the core. There is.

However, the present inventor added boric acid to the alkali metal silicate.
As a result of various studies on the method of adding boric acid and borax and coating it on a piece of paper, we found that, although normally it gels immediately when boric acid is added, it is possible to redissolve this gel by stirring strongly for a certain period of time. After discovering this, it became possible to apply surface treatments such as coating and impregnating it as a reinforcing agent for paper, paperboard, and cardboard.

(Means for Solving the Problems) The present invention was made to solve the above-mentioned problems of alkali metal silicate salts. The present invention was completed based on the knowledge that the gelled product, which is stirred for a certain period of time to be redissolved and transformed into an aqueous solution of alkali borosilicate, improves hygroscopicity.

The composition of the present invention is that boric acid is added to an alkali metal silicate.

A reinforcing agent for paper, paperboard, and cardboard containing borate and borax, and paper, paperboard, and cardboard processed with the reinforcing agent.

Examples of the alkali metal silicate used in the present invention include sodium silicate, potassium silicate, and lithium silicate.

The alkali metal silicate has a solid concentration of 10 to 404
It is preferable to use the reinforcing agent in an amount of 70 to 99% by weight.

Examples of boric acid, borates, and borax used in the present invention include boric acid, potassium borate, ammonium borate, and borax. Boric acid, borate.

Borax should be added in an amount of 1 to 20% by weight per reinforcing agent component.
- Preferred. The addition amount was set to 1 to 20 heavy fk.
11fLl14 Without grooves, the moisture-proofing effect is slight.

This is because even if it is used in an amount exceeding 20% by weight, no improvement in the moisture-proofing effect can be expected.

When boric acid is added to an aqueous solution of sodium silicate, which is a typical example of an alkali metal silicate, a poorly soluble silicon dioxide compound is produced as shown in the formula below.

Gells, 3 Na, O・ns i 02 + 2 H3BO3+
Bo, 0−+ 2 Na6BO3+ 3 nrusio,
6x'H, O+x'H10 In the present invention, this gelled product is stirred for a certain period of time to be redissolved into sodium borosilicate. Sodium borosilicate is a product in which sodium and non-crosslinked oxygen ionize and become water-soluble.

Regarding the moisture absorption properties of sodium borosilicate produced in this manner, the amount of moisture absorbed under high humidity conditions decreases as the amount of boric acid added increases. In other words, when base paper is strengthened, the compressive strength of the strengthened paper in high humidity conditions is greatly improved by adding boric acid, borate, and borax to the strengthener.

In a previous application, the present inventors investigated a chemical that is stable when added to an alkali metal silicate salt and does not cause the above-mentioned adhesion problem.

Focusing on surfactants, the solubility with alkali metal silicate,
Stability, permeability into paper 1 Considering the compressive strength characteristics of paper, etc.
In particular, it was proposed that anionic sulfate ester salt type surfactants give the most favorable results as adjuvants for alkali metal silicate salts.

When added to a concentrated sodium silicate aqueous solution, non-ionic ones, for example, are mostly insoluble and some dissolve, but their permeability is weak and it is difficult to improve the physical properties of an alkali metal silicate aqueous solution. I can not use it.

Cationic systems have poor stability (and are not suitable for use) in concentrated aqueous solutions of alkali metal silicate.

Since amphoteric systems have both anions and cations bound to their hydrophobic groups, most of them do not completely dissolve in concentrated sodium silicate aqueous solutions. Although some of them dissolve, they have low penetration effects and cannot be used in the present invention.

On the other hand, many anionic products exhibit their effectiveness as surfactants even under strong alkali conditions (.

Many of them coexist stably with sodium silicate.

It is suitable as an additive to the reinforcing agent of the present invention.

Anionic surfactants include carboxylate type (R-Co
o-), sulfate ester salt type (R-0-8O3-),
There are sulfoyate salt type (R-SO, -), phosphate ester salt temperature, etc., but in the present invention, sulfuric acid ester salt is most suitable, and when the alkyl group ② has 6 to 18 carbon atoms, The best results can be obtained in terms of solubility in alkali metal silicate salts, stability, permeability to paper and paperboard, compressive strength improvement effect, etc. In the present invention, the amount of the anionic sulfate ester type surfactant added to the reinforcing agent can be 0.1 to 15 parts by weight, preferably 2 to 10 parts by weight.

The amount of coating or impregnation of the reinforcing agent of the present invention on paper, paperboard, and corrugated poles is preferably 2 to 20 f/♀.

The paper and paperboard of the present invention 1 As the base paper to be coated or impregnated with the reinforcing agent for corrugated board, any commonly available commercially available paper or paperboard (including base paper for corrugated board) that can be coated or impregnated can be used.

The reinforcing agent of the present invention can be processed by coating or impregnating the liner and/or core of the corrugated board using a size press in a paper machine for paper, board, or corrugated board, as well as an off-coater or on-machine of a corrugator for manufacturing corrugated board. This can be done by

Paper and paperboard processed with the reinforcing agent of the present invention can be used for various boxes, containers such as barrels, daily necessities 1 stationery, toys, interior decorations,
It can be used for a wide range of applications depending on the thickness of the paper, paperboard, cardboard base paper, and the combination of these papers, such as interior materials for automobiles, simple furniture, musical instrument cases, bags, etc. (Example) (1) Alkali metal silicate boric acid, borate,
Moisture absorption improvement effect with borax Boric acid and borate for No. 2 sodium silicate aqueous solution.

Add borax in the amount (by weight) shown in Table 1 and concentrate.
The dried solid material was heated under constant humidity conditions of 20℃ and 651cm for 2 hours.
After controlling the humidity for 0 days, the amount of moisture absorbed by the dry solid was measured.

The results are shown in Table 1.

As shown in the table above in wIJ1, it can be seen that the amount of moisture absorbed is reduced by adding boric acid, borate, and borax to sodium silicate.

If the amount of boric acid, borate, or borax added is increased, the amount of moisture absorbed decreases, but when the addition rate exceeds 20 weight ill, the increase in the amount of moisture absorbed slows down.

(Comparison of 2 Physical Properties A reinforcing agent of the present invention and a conventional reinforcing agent were prepared using the chemical formulations shown in Table 2, and the physical properties of the reinforcing agents were compared.

IEZ table The reinforcing agent of the present invention (Example 1.2) has the same viscosity but a lower surface tension (1, 0-grade liner basis weight 170 f, By applying the reinforcing agent to the inside of the paper, the permeability into the inside of the paper layer passing from the back side to the front side is significantly improved.This good permeability allows most of the reinforcing agent to penetrate into the inside of the base paper, strengthening it on the surface of the base paper. This is thought to reduce the stickiness of the agent.

(3) Compressive strength of reinforced paper In a corrugator for manufacturing corrugated board that laminates the liner and core of corrugated paperboard, Examples 1 to 4 were applied to the back side of the liner at a lamination speed of 150 m/9. The solid content of the comparative example reinforcing agent was 8 tons.
/w? A test of adhesion with core paper was conducted.

Table 3 shows the results of measuring the compressive strength of the liner coated with the reinforcing agent under standard conditions and under high humidity conditions.

Note to Table 6: The standard condition is 20°C and 654 RH for 48 hours. The high humidity condition is 30°C and 90% RH for 48 hours. As is clear from Table 3, 1. Strengthening agent of the present invention The corrugated paperboard liner processed with the above has a higher compressive strength in a high humidity state than the comparative example using only sodium silicate as a reinforcing agent, and the decrease in compressive strength due to moisture absorption is improved.

(4) Comparison of adhesion troubles in corrugated pole manufacturing The reinforcing agent of the present invention (Examples 1 to 4) and the conventional reinforcing agent (comparative example) containing only sodium silicate were used in a corrugator for corrugated board manufacturing.
Basis weight 170? /? r? Each was coated on the back side of a 0 grade liner using a z st/i (solid content) roll coater, and adhesion problems with a 1-pass roll were compared.

As a result, in Example 3゜4 and Comparative Example in which no surfactant was used, adhesion problems with the heating roll occurred at a lamination speed of 30 m5, but in both Examples 1 and 2 of the present invention, the maximum corrugator No adhesion trouble occurred even at a lamination speed of 2001rLA-.

However, although Examples 3 and 4 of the present invention have problems with adhesion, the above-mentioned compressive strength under high humidity is improved, so as long as operational problems are suppressed, they have excellent physical properties as corrugated board.

(Effects of the Invention) As stated above, the present invention is applicable to an alkali metal silicate as a reinforcing agent for paper, paperboard, and corrugated board, which conventionally had the problem of decreasing compressive strength when used under high humidity.

It contains boric acid, borates, and borax to solve the problem of lower compressive strength under high humidity conditions. In addition, in addition to the aforementioned boric acid, borates, and borax, the use of an anionic sulfate ester salt-type surfactant in the alkali metal silicate salt can reduce adhesion problems of the alkali metal silicate to rolls in paper machines, off-coaters, corrugators, etc. It has the effect of solving the problems at the same time.

The reinforcing agent for paper and paperboard single-stage poles of the present invention, and the paper, paperboard, and corrugated board processed with the reinforcing agent 1. Needless to say, they have high compressive strength under normal usage conditions.

Even when used under high humidity conditions, it has far superior compressive strength than conventional arsenic-treated paper, so it can be used not only for paper cartons and packaging containers, but also for daily necessities.
It has great effects and can be used in a wide range of applications, including furniture, interior decoration, automobile interior materials, and musical instrument cases.

Claims (2)

[Claims] (1) Paper, paperboard containing 1 to 20% by weight of boric acid, borate, and borax based on the alkali metal silicate;
Strengthening agent for cardboard. (2) Paper, paperboard, and corrugated board processed with a reinforcing agent containing boric acid, borate, and borax in an alkali metal silicate salt in an amount of 1 to 20% by weight based on the alkali metal silicate salt.