JPS61252395A - Method for reinforcing paper strength - 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 Industrial Application) The present invention relates to a method for strengthening paper strength, and more specifically, the present invention relates to a method for strengthening paper strength. The present invention relates to an improved method for increasing the paper strength of paperboard, and in particular, it is a method useful for strengthening the core in the production of corrugated paperboard and increasing the paper strength of the corrugated paperboard.

(Description of Prior Art) Various manufacturing methods have been proposed and patent applications have been filed for reinforcing the core of corrugated paperboard, but in general, water-soluble resins and/or water-insoluble resin liquids, such as vinyl acetate emulsion, have been proposed and patent applications have been filed. There are known methods of applying a liquid, a water-soluble or water-insoluble urethane resin liquid, or a natural processed resin liquid such as starch or dextrin. On the other hand, a method of increasing paper strength by applying an inorganic compound such as water glass is also known.

However, in the case of these conventional methods, paper strength decreases as the oral cavity changes, and exhaust gas during coating becomes a problem.
This method could not be said to be fully satisfactory from both an economic and a pollution standpoint, as the paper exhibited extreme alkalinity. Therefore, it has been desired to develop a non-polluting coating agent that is economical and does not reduce paper strength over a long period of time.

(Objectives and Solutions of the Invention) The object of the present invention is to provide a method for increasing the paper strength of paper such as corrugated paperboard and reinforced corrugated paperboard at low cost and effectively. This is achieved by applying a resin liquid and a specific inorganic compound to the paper surface.

(Structure of the Invention) The present invention will be described in detail below. Examples of the water-soluble and/or water-insoluble resins covered by the present invention include vinyl acetate emulsion, modified vinyl acetate aqueous solution, and vinyl acetate/acrylic resin. Copolymers, copolymers of vinyl acetate such as ethylene/vinyl acetate copolymers, water-soluble and water-insoluble acrylic polymer resins, acrylic-styrene copolymer resins, acrylic-ethylene copolymers, water-soluble and water-insoluble eboxy resin, modified evoxy resin, polyvinyl alcohol, anionic polyvinyl alcohol, cationic polyvinyl alcohol, amine salts and diamine salts of polyvinyl alcohol, polyacrylamide and its derivatives,
Examples include mixing of each of the above compounds with melamine resin, melamine resin, water-soluble and water-insoluble urethane resins, and the like. Furthermore, water-soluble and water-insoluble resins such as starch, dextrin, carrageenan, CMC, taracanth gum, and gum arabic produced from natural products can also be mentioned. These resins are typically utilized as emulsions or aqueous solutions.

The present invention involves applying a mixture of the water-soluble and/or water-insoluble resin liquid and an inorganic powder to paper, or combining this resin liquid and water glass, or this resin liquid, water glass, and a hardening agent for water glass. The inorganic powders used in the former case are usually inorganic powders such as diatomaceous earth, perlite, talc, clay, red iron, bentonite, silica, silica gel, and clay. Natural compounds, aluminum oxide, titanium oxide, silica nitride,
titanium nitride, sintered silica, and alumina, zinc oxide,
Examples include fine powders and colloids of synthetic inorganic compounds such as boric acid, sodium sulfate, sodium carbonate, calcium carbonate, aluminum sulfate, and aluminum hydroxide. The particle size of this inorganic powder is usually 80 μm or less, preferably 5 μm or less.

These resin liquids and inorganic powder are mixed, and the amount of inorganic powder used is usually 0.1 to 10 times the weight of the resin. If the amount of inorganic powder used is too small, paper strength cannot be improved as expected, which is not preferable.

By spraying or coating the core of paper and cardboard with such a mixture, the paper strength of the paper and cardboard as a whole is strengthened and increased.

In the present invention, the amount of resin liquid applied to paper is usually 10
It is 1 to 500 σ per 11 Tr of paper, preferably 1 g to 50 g, in terms of 0% weight. In addition, inorganic powder is usually used for paper 1
r+? 0.01 to 500g, preferably 0.2 to 500g per
It is applied at a rate of 50g.

In addition, in the present invention, paper strength can also be strengthened by applying the above-mentioned resin liquid and water glass to the paper surface, but in this case, the resin liquid and water glass, and if necessary, the paper strength can be strengthened. The curing agent can be applied to the paper surface separately, simultaneously, or mixed. In the case of this method, a mixture of inorganic powder and resin liquid is finally formed on the paper surface, and this becomes fixed to the paper surface, so the resin liquid containing the above-mentioned inorganic powder is applied to the paper surface. It will be essentially the same as if

The water glass used in the present invention usually includes sodium silicate, potassium silicate, ammonium silicate, lithium silicate, and the like. Particularly preferred are sodium silicate (water glass) No. 1 to No. 3.

Furthermore, the curing agent used as necessary is usually an organic acid such as formic acid, acetic acid, propionic acid,
Butyric acid, etc.; Carboxylic acids include oxalic acid, malonic acid, glutaric acid, glycolic acid, lactic acid, malic acid, etc.; Esters include methyl formate, methyl acetate, ethyl acetate, etc.; acid amides include formamide, dimethylformamide, etc.; Sulfonic acids and derivatives thereof include benzenesulfonic acid, toluenesulfonic acid, etc.; amino acids include glycine, serine, methionine, etc.; and aldehydes include formaldehyde, acetaldehyde, glyoxal, and polymers thereof. Note that among the resin liquids listed above, water-insoluble resins and water-soluble resins that react with water glass to form a gel can also be used as the curing agent. In addition, examples of inorganic acids include hydrochloric acid, sulfuric acid, phosphoric acid,
Metaphosphoric acid, birophosphoric acid, polyphosphoric acid and its salts such as aluminum phosphate, zinc phosphate, tripolyphosphoric acid 2
Aluminum, phosphoric acid compounds such as zinc tripolyphosphate,
Examples include boric acid, sodium hydrogen sulfate, potassium hydrogen sulfate, sodium bicarbonate, and sodium carbonate.

The amount of water glass and hardener applied to paper is usually 100
% weight, water glass is 1 to 500 g, preferably 1 to 50 g, and hardening agent is 0.01 to 500 g, preferably 0.1 to 50 (+
It is. In addition, the use a of the resin liquid is the same as when mixing the above-mentioned inorganic powder, and is 1 to 500 g per rrr of paper.
, preferably 1 to 50 (].

In the present invention, the method of applying resin liquid etc. to the core of paper and cardboard usually includes methods of applying with a roll coater, applying with a spatula, and applying with a spray. is reasonable. In addition, the process positions for coating include four locations: before the corrugator's pre-con, between the pre-con and pre-con, after forming a single layer, and immediately before pasting the next paper after forming a single layer, but the locations where field experiments were conducted It is particularly preferable to apply the coating using a spray gun immediately before pasting the next paper after forming the last single layer.

In the present invention, suitable combinations that are inexpensive as raw materials, have good workability, and improve the strength of paper include (1) a mixture of a water-soluble resin and a highly hard water-insoluble, non-water-absorbing inorganic fine powder; ■It is a combination of water-soluble resin, water glass, and hardening agent.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A pre-adjusted reinforcing agent shown in the table below was applied to one stage of the corrugated cardboard core shown below at a ratio of 18 (l) per 1 d, and immediately after heat treatment was performed at 170°C for 30 seconds,
℃ and 65% RH for 24 hours, or (1) As a humid condition, a cycle of 6 hours at 40℃ and 90% RH, and 18 hours at room temperature (normal condition) was repeated three times, and then 20 hours.
℃, 65% RH, each J l5-20
A plane compression test was conducted in accordance with 401, and the strength of the paper was measured, and the results shown in Table 1 were obtained.

a) Center core (a) SCP125 (AF class 8) (b)
SCPl 25 (AF 0 class) (c) SCP125
(BF 0 grade) b) Reinforcing agent Acrylic-ethylene copolymer 50a titanium oxide powder 5 g (5μ or less) Water 450 Solid content 25% Example 2 In the method of Example 1, one layer of the corrugated cardboard core shown in a below was used. A pre-prepared reinforcing agent shown in the table below was applied to the test piece, and a test was conducted in exactly the same manner as in Example 1. The results are shown in Table 2.

a) Center core (a) SCP125 (AF class 8) (0)
SCPL 25 <AF 0 class) (c) SCPL 2
5 (BF 0 grade) b) Reinforcing agent Acrylic-styrene copolymer 10g Water glass 50a Dialuminum tripolyphosphate 2g (Curing agent) Water 48g Solid content 25% (Effects of the invention) According to the present invention, it is inexpensive and, It is possible to significantly improve the paper strength, especially of the core of corrugated paperboard, by a simple method, and is extremely desirable from an industrial perspective.

Claims (1)

[Scope of Claims] 1. A method for strengthening paper strength, which comprises applying a mixture of water-soluble and/or water-insoluble resin liquid and inorganic powder to the paper surface. 2. The method according to claim 1, wherein the inorganic powder has a particle size of 80 μm or less. 3. The method according to claim 1, wherein the amount of inorganic powder used is 0.1 to 10 times the weight of the water-soluble and/or water-insoluble resin. 4. A method for strengthening paper strength by applying a solution of water-soluble and/or non-water-soluble resin liquid and water glass to the paper surface. 5 The amount of water-soluble and/or water-insoluble resin applied is 1 m^ of paper.
5. The method according to claim 4, wherein the amount is 1 to 500 g (as a resin component) per 2 parts. 6. The method according to claim 4, wherein the water-soluble and/or water-insoluble resin liquid is an emulsion or an aqueous solution.