JPS6043480B2 - Paper making method for neutral decorative board base paper with improved titanium dioxide and pigment yield - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for making neutral decorative board base paper with improved titanium dioxide and pigment retention.

In particular, the present invention relates to a paper making method characterized in that a melamine formaldehyde resin is added when making a neutral decorative board base paper using a polyamide polyamine epichlorohydrin resin as a wet paper strength enhancer. In the present invention, the term "pigment" refers to white fillers other than titanium dioxide, white pigments, and organic and inorganic pigments of various colors other than white. Decorative laminate base paper is printed or directly impregnated with decorative laminate molding resin (melamine resin, polyester resin, diallyl phthalate resin, etc.) and then pressed onto a decorative laminate base material layer made of phenolic core, plywood, hardboard, particle board, etc. to form a decorative board.

For this reason, the main properties required of decorative laminate base paper include printability, impregnability, and shielding properties for shielding the decorative laminate base material layer. Furthermore, when the base paper for decorative laminate is impregnated with a water-soluble resin such as melamine resin as a resin for molding the decorative laminate, the base paper for decorative laminate needs to have a certain degree of strength in the aqueous impregnating liquid.

For this reason, decorative board base paper is usually made by adding a wet paper strength agent. Conventionally, base paper for decorative laminates has been made using sulfuric acid as a fixing agent in an acidic region around pH 4, and melamine formaldehyde resin has been used as a wet paper strength enhancer.

However, in recent years, with the diversification of secondary processing methods for base paper for decorative laminates, a neutral paper making method has been developed in which paper is made in a neutral region.

In this case, the system is neutral and not acidic during heating and drying, so the melamine formaldehyde resin cannot exhibit its effectiveness as a wet paper strength enhancer.This is because the crosslinking reaction of the melamine formaldehyde resin proceeds in the neutral region. This is because it is difficult.

Therefore, polyamide polyamine epichlorohydrin resin is mainly used as a wet paper strength enhancer for neutral decorative board base paper. However, the neutral decorative laminate base paper using this polyamide polyamine epichlorohydrin resin has a lower yield of titanium benoxide and pigment than the conventional acidic decorative laminate base paper. That is, neutral paper requires a greater amount of titanium dioxide and pigment added than acidic paper to obtain a paper of a certain shielding property and color. As a result, neutral paper costs more compared to acidic paper. The present inventors conducted a detailed study to improve this drawback of neutral paper, and as a result, they discovered that the objective could be achieved by adding melamine formaldehyde resin, and completed the present invention.

The method of the present invention uses melamine formaldehyde resin in a neutral system in combination with polyamide polyamine epichlorohydrin resin in the paper stock for making neutral paper.

The amount of melamine formaldehyde resin added is Bulb 100.
A suitable amount is 0.5 to 2 parts by weight.

If the amount is 2 parts by weight or more, the effect will not be improved even if the amount is increased, and if it is less than 0.5 parts by weight, the effect will not be noticeable.

In the present invention, the effect of using the melamine formaldehyde resin in combination differs depending on the timing of addition of the polyamide polyamine epichlorohydrin resin, and when the polyamide polyamine epichlorohydrin resin is added after titanium dioxide and pigments are added to the valve slurry, the progress of titanium dioxide and pigments is lower. The effect of improving retention is best seen.

The principle behind the effectiveness of the present invention is not clear. In a neutral system, the melamine formaldehyde resin synergistically promotes the effect of the polyamide polyamine epichlorohydrin resin on fixing titanium dioxide and pigments to the bulb.

In a neutral system, it is not necessary to use the sulfuric acid band used in general acidic systems, but a small amount, 0 to 1 part per 100 bulbs, can be used to prevent floating seeds and bubbles of the raw material. However, in that case, the system must be neutralized using a neutralizing agent such as caustic soda or sodium aluminate.
The effect of the present invention is that good shielding properties and color development can be obtained with a smaller amount of titanium dioxide or pigment added than before.

Titanium dioxide and pigments are several times more expensive than bulbs, so being able to save on these costs has a great effect on industrial production. On the other hand, in conventional neutral papermaking, not only is the yield of titanium dioxide and pigments poor, but also the suitability of paper stock containing large amounts of titanium dioxide and pigments (not fixed on the valves) is poor, making stable production impossible. In contrast, the present invention has a good yield of titanium dioxide and pigments, so it does not have the above-mentioned drawbacks and can stably produce high-quality paper, which is more effective than simply improving the yield. The shielding property used as an evaluation method of the present invention is to measure the color of a white back molded board and a black back molded board created by the following method using a color analyzer manufactured by Hitachi, Ltd., and calculate the Y value of the X-Y-Z color system. This is the ratio of the Y value of the black back molded plate to the Y value of the white back molded plate.

(1) The test paper and white decorative board base paper with high shielding properties are impregnated with melamine resin, overlapped, and hot-press molded. This is called a white back molded plate. (2) The same test paper as in (1) and black decorative board base paper with high shielding properties are impregnated with melamine resin, and then stacked and hot-press molded.

This is called a black back molded plate. In addition, after impregnating the test paper with melamine resin and hot-pressing it by overlaying it on a melamine resin-impregnated barrier paper on a phenol resin-impregnated core paper, the color was measured using a color analyzer, and the L-a-b color representation was performed. Systems a and b were used as color developers. The present invention will be explained below based on examples.

Example 1 Bleached kraft valve adjusted to a beating degree of 25 light SR 1
Melamine formaldehyde resin is added to 0 and 0 saliva parts respectively.
．． 5, 1, 2, and 4 parts by weight were added, and 1 part by weight of polyamide polyamine epichlorohydrin resin and 2 parts by weight of titanium dioxide were added to each as a wet paper strength agent in this order, and then sulfuric acid was added. Neutralized.

In addition, 1 part by weight of melamine formaldehyde resin and 2 parts by weight of titanium dioxide were added to 1 part by weight of the above LBKPl (1 part by weight).
After adding 1 part by weight of polyamide polyamine epic rehydrin resin in this order,... Addition of sulfate was followed by neutralization. Furthermore, as a comparative example, the above LBKPl
After adding 1 part by weight of polyamide polyamine epichlorohydrin resin to the O rut area, 22, 24, and 2 parts of titanium dioxide were added to the rut area.
6, 28, and 3 parts by volume were added, followed by a small amount of sulfuric acid, and then neutralized. No melamine formaldehyde resin was added. The paper stock thus obtained was hand-sheeted to a weight of 80 y/y using a TAP Yen hand-paper machine and molded, and the color was measured using a color analyzer to determine the shielding properties. The results are shown in Table 1. From Table 1, it can be seen that the shielding properties are higher when the melamine formaldehyde resin is added.

For example, when 2 parts by weight of melamine formaldehyde resin is added, the shielding properties are approximately the same as when about 2 parts by weight of titanium dioxide is added. It can also be seen that the shielding properties are further improved when the polyamide polyamine epichlorohydrin resin is added after the addition of titanium dioxide.

Even if the amount of melamine formaldehyde resin added exceeds 2 parts by weight, the effect is no more noticeable. Example 2 A bleached kraft valve adjusted to a freeness of 28 parts SR was added to 10 parts by weight, 1 part by weight of melamine formaldehyde resin, further 1 part by weight of yellow pigment, and then 1 part by weight of polyamide polyamine epichlorohydrin resin. of sulfuric acid was added and then neutralized.

In addition, 1 part by weight of melamine formaldehyde resin and 1 part by weight of polyamide polyamine epichlorohydrin resin and 1 m of yellow pigment were added to 10 parts by weight of the above-mentioned bulb. parts were added in this order.

Furthermore, as a comparative example, after adding 1 part by weight of polyamide polyamine epichlorohydrin resin to 100 parts by weight of the above-mentioned bulb, yellow pigments were added at 10, 11, 12, 13, 14, and 15 parts by weight, respectively.
Part by weight was added.

The paper stock thus obtained was hand-sheeted to a weight of 80 g/771' using a TAPPI hand-paper machine, molded, and measured with a color analyzer to determine color development. The results are shown in Table 2. From Table 2, it can be seen that those to which melamine formaldehyde resin was added had higher color development. It can also be seen that color development is further enhanced when the polyamide polyamine epichlorohydrin resin is added after the addition of the yellow pigment. For example, 1 part by weight of melamine formaldehyde resin 1 part by weight of yellow pigment
The amount of yellow pigment added in this order is approximately 1J of yellow pigment and 1 part by weight of polyamide polyamine epichlorohydrin resin.
The color development is almost the same as when adding 10%.

Example 3 A paper stock was prepared in the same manner as in Example 2 except that 2 parts by weight of a red pigment was added instead of the yellow pigment in Example 2, and as a comparative example, 2.0 and 2.2 parts of red pigment were added respectively. ,2.4,2
．． 6, 2.8, 3. It was prepared and hand-sheeted in exactly the same manner as in Example 2, except that a portion of sludge was added.

Furthermore, it was molded and measured using a color analyzer to determine color development. The results are shown in Table 3. From Table 3, it can be seen that those to which melamine formaldehyde resin was added had higher color development. It can also be seen that the color development is even higher when the polyamide polyamine epichlorohydrin resin is added after the red pigment is added. For example, 1 part by weight of the melamine formaldehyde resin, 2.0 parts by weight of the red pigment, and 1 part by weight of the polyamide polyamine epichlorohydrin resin are added. When added in this order, the color development is almost the same as when about 2.5 parts by weight of red pigment is added.Example 4 10 parts by weight of the bulb adjusted to a freeness of 30 colors SR and 21.4 parts by weight of titanium dioxide After adding 1.1 part by weight of yellow pigment and 0.01 part by weight of red pigment, 1 part by weight of melamine formaldehyde resin and 1 part by weight of polyamide polyamine epichlorohydrin resin were added in this order, and further sulfuric acid band was added. added and then neutralized.

This paper stock was made into paper with a basis weight of 80 y/d using a Fourdrinier paper machine. On the other hand, without using melamine formaldehyde resin,
In addition, polyamide polyamine epichlorohydrin resin is added before adding titanium dioxide and pigment, and the following is prepared according to the above preparation method, so that the shielding property and color development property of the paper after molding are exactly equal to the former. 30.3 parts by weight of titanium dioxide, 1.40 parts by weight of yellow pigment, 0 parts of red pigment.
．． 016i parts had to be added. Example 5 After adding 2 parts by weight of melamine formaldehyde resin and 2 parts by weight of polyamide polyamine epichlorohydrin resin to 10 parts by weight of a valve adjusted to a freeness of 25 SR, 4 parts by weight of titanium dioxide were added, and sulfuric acid band was added. was added and then neutralized.

This paper stock was made into paper with a basis weight of 100 y/y using a Fourdrinier paper machine.

Claims (1)

[Scope of Claims] 1. In making decorative board base paper, polyamide polyamine epichlorohydrin resin is used as a wet paper strength enhancer, and melamine formaldehyde resin is added at a ratio of 0.0% to the pulp.
A method for making neutral decorative board base paper with improved retention of titanium dioxide and pigment, characterized by using a neutral paper stock containing 5 to 2.0 parts by weight. 2. The method for making neutral decorative board base paper according to claim 1, wherein the polyamide polyamine epichlorohydrin resin is added after adding titanium dioxide and/or pigment to the paper stock.