Deinking agent

Abstract

Provided is a deinking agent making it possible to improve ink collecting power in the step of flotation and yield high-quality deinked pulp without lowering the yield of pulp. It is a deinking agent comprising an ester of an alkylene oxide-added product of glycerin, its hydroxyl value (OHV), saponification value (SV) and acid value (AV) satisfying the following: OHV / (SV-AV+OHV) ranges from 0 to 0.3.

Description

[0001] The present invention relates to a deinking agent.PRIOR ART[0002] Importance has been increasingly attached to effective use of waste paper in connection with global environment problems such as protection of forest resources and waster disposal. When deinked pulp, which is regenerated from waster paper, is used to attain a high blend ratio thereof, it is necessary to obtain higher-quality deinked pulp, that is, deinked pulp wherein the amount of residual ink is small. For deinking, it is necessary to perform effectively deinking for releasing ink from paper and ink removal for separating the released ink from pulp. About deinking agents, it has been desired to develop deinking agents and ink removing methods which are good in ink releasing property and ink collecting property. As deinking agents, there have been developed a reaction product wherein an alkylene oxide (referred to as an AO hereinafter) is added to a mixture of oil and fat and an alcohol (for example, Japanese ...

AI Technical Summary

Benefits of technology

[0038] The average number of the added AO molecules is from 45 to 1000, more preferably from 70 to 1000, still more preferably from 100 to 1000, and particularly preferably from 150 to 1000 per mole of the material to which the AO is to be added. The average number is most preferably from 150 to 600, considering the handling property. If the average number of the added AO molecules is 45 or more, linked micelles are construed to produce the advantageous effects of the present invention satisfactorily.

[0039] In the case that two or more (kind) AO are contained in the compound represented by the general formula (Y) or the general formula (a), about the addition form thereof a block polymerization chain or a random polymerization chain is allowable. The form is not particularly limited. Considering an appropriate bubble amount at the time of floatation, about the existence ratio (mole ratio) of EO in the AO the following is preferred: EO / AO=0.3 to 1. As the AO, EO and PO are preferably used together. About the mole ratio in this case, EO / PO=10 / 0 to 3 / 7 is preferred, and EO / PO=9 / 1 to 4 / 6 is more preferred.

[0040] R of the general formula (Y) and R.sup.1 to R.sup.3 of the general formula (a) are each a hydrogen atom or an acyl group having 1 to 24 carbon atoms provided that at least one R.sup.1 to R.sup.3 is an acyl group having 8 to 24 carbon atoms. More preferably, two or more thereof are acyl groups. These acyl groups may be unsaturated or saturated. The ratio of acyl groups having 8 to 24 carbon atoms, more preferably 12 to 24 carbon atoms in all groups of R and R.sup.1 to R.sup.3 is preferably 80% or more by weight.

[0041] The content of the compound represented by the general formula (Y) or the general formula (a) in the deinking agent is preferably from 50 to 100% by weight, particularly preferably from 70 to 100% by weight.

[0042] The compound represented by the general formula (Y) or the general formula (a) can be obtained by esterifying a reaction product wherein the AO is added to glycerin or a mixture of glycerin and oil and fat with a carboxylic acid. The OHV / (SV-AV+OHV) can be adjusted by setting a target value of the AV in light of the mole ratio between charging ingredients, picking up a sample and measuring the AV.

[0043] The compound represented by the general formula (a) is also present in a known reaction product wherein an AO is added to a mixture of oil and fat and an alcohol. However, according to this reaction, by-products such as an AO copolymer besides the compound represented by the general formula (a) are produced if they are caused to react in accordance with a formulation described, for example, in Japanese Patent No. 1573380. For this reason, the value of the OHV becomes large so that the OHV / (SV+OHV-AV) of the whole of the mixture becomes larger than 0.3.

Problems solved by technology

However, the higher alcohol AO-added product has superior ink releasing property, but has strong ink dispersing power so as to be poor in ink collecting property.

However, these measures have problems from the viewpoints of workability, facilities, and costs since additional treatment is conducted.

1) In any (conventional) deinking agent that forms micelles which are not linked by AO chains, it is necessary that its hydrophobic groups adsorbed on ink particles are newly adsorbed on bubbles. However, in the deinking agent of the present invention, hydrophobic groups of micelles which are not adsorbed on ink particles, among micelle structures linked by AO chains, are adsorbed on bubbles and simultaneously ink particles linked by the AO chains are also entrained and adsorbed on this. Thus, the respective hydrophobic groups can independently fulfill their given functions.

2) Since such structures are formed, it is difficult that the ink particles are entirely covered with the hydrophobic groups because of three-dimensional entanglement. It therefore appears that the fact that hydrophobic faces remains in the surfaces of the ink particles is also a factor for promoting adsorption onto the bubbles.

This by-product is poor in deinking.

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