JPS6261712B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a deinking agent for recycling used paper that disintegrates and deinks printed waste paper. In order to obtain recycled pulp from waste paper, it is necessary to deink the printed waste paper, but the deinking method for used printed paper is to process the waste paper together with an alkaline agent and a deinking agent (surfactant) in an earth pot at high temperature and high pressure. There is a cleaning method in which ink particles are removed by cooking the paper in a pulper, and then the digested material is passed through wires such as a decker, extractor, or inclined screen to remove ink particles.An improved method is to cook the waste paper in a pulper together with an alkaline agent and a deinking agent. A method in which ink particles are removed by heat treatment at 50 to 60°C and then the same operation as the above-mentioned cleaning method, and after treatment with an alkaline agent and a deinking agent in a pulper,
A flotation method is used to remove ink by blowing air into the processing solution and causing the ink to adhere to bubbles. In either method, conventional deinking agents include fatty acid soaps, anionic surfactants such as alkyl sulfates, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, etc. nonionic surfactants or mixtures thereof have been used. By the way, most of the recovered paper is newspapers and magazines, and these are mainly ground pulp, but conventional deinking agents have a low deinking effect, and even when used, the recycled pulp has a bluish tinge. The problem was that the color could not be restored to the original yellow color of the new ground pulp. This invention is intended to improve the conventional drawbacks as described above, and by using a copolymer of an anionic monomer and a hydrophobic monomer as a deinking agent, the removal rate of printing ink can be improved. The purpose of the present invention is to provide a deinking agent that can improve the color of used paper and regenerate it into a new ground pulp color. This invention uses a copolymer of an anionic monomer and a hydrophobic monomer (does not include a graft polymer obtained by adding an anionic monomer to a polymer of a hydrophobic monomer) as an active ingredient. It is a deinking agent for waste paper recycling that contains Examples of the anionic monomer include acrylic acid, maleic acid, and maleamic acid, and these may be used alone or in combination of two or more. Examples of hydrophobic monomers include alkenes having 5 to 18 carbon atoms, styrene, and styrene derivatives having substituents having 1 to 12 carbon atoms.
These may be used alone or in combination of two or more. Examples of these hydrophobic monomers include pentene, hexene, dodecene, octadecene, diisobutylene, styrene, and 4-dodecylstyrene. The deinking agent in the present invention contains a copolymer of an anionic monomer and a hydrophobic monomer as an active ingredient. The molar ratio is 85:15~
15:85, preferably 70:30-50:50,
Moreover, the molecular weight is preferably 1,000 to 100,000. The copolymer may also contain other monomers as structural units. The copolymer can be produced by a general polymerization method using the above-mentioned anionic monomer and hydrophobic monomer as starting materials. This copolymer contains hydrophilic structural units and hydrophobic structural units, so it has a surface-active effect, but its high molecular weight distinguishes it from conventional low-molecular-weight surfactants. The deinking agent of the present invention may contain only one kind of the above-mentioned copolymers, but may contain two or more kinds of copolymers depending on the difference between the anionic monomer and the hydrophobic monomer. They may also contain other copolymers or other additives. When the deinking agent of the present invention disintegrates and recycles used paper,
By adding it into the system, the printing ink can be released from the fibers. The addition location differs depending on each disintegration method, but it may be added to the reaction tower before disintegration in the deinking step or before the floatator. The amount added varies depending on each system, but is generally 0.01 to 0.5% by weight based on the waste paper. The peeled ink is dispersed in the pulp and removed by washing or flotation.
When the deinking agent of the present invention is added, the removability is excellent in all cases, and since the foaming property is small, pulp outflow due to foam is small, and the amount of washing water is also reduced. As described above, according to the present invention, since a copolymer of an anionic monomer and a hydrophobic monomer is used, the removal rate of printing ink is higher than that of the conventional method. It is possible to reduce the number of residual ink particles and improve whiteness, as well as improve the b value in the Lab color difference formula, and regenerate waste paper into recycled pulp with a new yellowish color of ground pulp. can do. Furthermore, it can be applied to both the washing method and the flotation method, and has the effect of reducing pulp outflow and the amount of washing water. Next, examples of the present invention will be described. Example 1 Deinking treatment was performed using the deinking agent shown in Table 1.
The deinking processing method is as follows. (1) Disintegration of waste paper Mainichi, Asahi, and Yomiuri newspapers (both are used once after printing)
70g of waste paper containing 80% (2 months old) and 20% flyers cut and mixed with a turbo cutter, 10
% Sodium hydroxide 10.5g, 10% Sodium silicate (No. 3) 21g, Hydrogen peroxide 0.7g, 1% Deinking agent
Add 14g and 1280g of water, set the waste paper concentration to 5%, and use a 3-capacity hydra pulper (3000 rpm).
After processing at 55°C for 20 minutes, 933 g of water was added to dilute the waste paper concentration to 3%, and the mixture was stirred for 5 minutes to completely disintegrate it. Next, to the completely disintegrated paper stock,
Ink was removed using the following method from a sample in which 4,666 g of water was added to further dilute the waste paper concentration to 1%. (2) Ink removal (A) Washing method Filter the sample from (1) through an 80 mesh sieve,
Furthermore, water was added so that the concentration of the recycled pulp was 1%, and the carbon was removed by filtering it again through an 80-mesh sieve. Pulp concentration 1% for recycled pulp after washing
Water was added to the mixture to give a pulp sheet by hand using a Tatsupi standard sheet machine. (B) Floatation method The sample from (1) was injected into a 5-fluorite floatator, floated for 10 minutes, the carbon aggregates in the upper layer removed, and hand-sheeted using a Tatsupi standard sheet machine to form a pulp sheet. I got it. The evaluation results by the washing method are shown in Table 2, and the evaluation results by the floatation method are shown in Table 3. Deinking effect evaluation method Whiteness: The reflectance was measured using a photoelectric reflectance meter, assuming that the reflectance of magnesium oxide was 100.
The values in the table are the average values of 5 points x 5 sheets. b value: Based on the Lab color difference formula of JIS Z8730. Number of remaining inks: The number of remaining inks was counted using a microscope with a magnification of 40 and converted to a value per 1 cm ² . From the results in Tables 2 and 3, it can be seen that the examples are superior to the comparative examples in whiteness, b value, and number of remaining inks. As for the b value, the larger the absolute value of +, the more yellowish it appears, so it can be seen that the color of the example is closer to the color of new ground pulp.

【table】

【table】

【table】

【table】

[Table] Example 2 In a system where newspaper is made by blending recycled pulp obtained from used newspaper, the deinking agent No. 5 of the invention product in Example 1 was added to the pulper in the deinking process.
When 0.15% by weight (based on waste paper) was added and the whiteness of the pulp immediately after being floatated was measured, the whiteness was 50.7.
This result was superior to the whiteness of 49.0 obtained with conventional polyethylene glycol alkyl ether deinking agents. From the above results, it can be seen that the ink of the present invention exhibits an excellent deinking effect.

Claims (1)

[Claims] 1. A copolymer of an anionic monomer and a hydrophobic monomer (does not include a graft polymer obtained by adding an anionic monomer to a polymer of a hydrophobic monomer) A deinking agent for waste paper recycling that contains as an active ingredient. 2. The deinking agent for waste paper recycling according to claim 1, wherein the anionic monomer is one or more selected from the group consisting of acrylic acid, maleic acid, and maleamic acid. 3 The hydrophobic monomer is 1 selected from the group consisting of alkenes having 5 to 18 carbon atoms, styrene, and styrene derivatives having substituents having 1 to 12 carbon atoms.
The deinking agent for waste paper recycling according to claim 1 or 2, which is a type or more. 4. The hydrophobic monomer is one or more selected from the group consisting of pentene, hexene, dodecene, octadecene, diisobutylene, styrene, and 4-dodecylstyrene, according to claim 1 or 2. A deinking agent for recycling used paper. 5. Used paper recycling according to any one of claims 1 to 4, wherein the molar ratio of anionic monomer to hydrophobic monomer in the copolymer is 85:15 to 15:85. Deinking agent. 6. The deinking agent for waste paper recycling according to any one of claims 1 to 5, wherein the copolymer has a molecular weight of 1,000 to 100,000.