Deinking agent for the reclamation of waste paper

Abstract: A deinking agent for the reclamation of waste paper which is a product obtained by reacting an alkylene oxide adduct of a polyhydric alcohol with at least one alkyl (or alkenyl) succinic acid or monoalkyl (or alkenyl) ester thereof, alkyl (or alkenyl) succinic acid polyalkylene glycol monoester or fatty acid. A deinking agent for the reclamation of waste paper is a product obtained by reacting an alkylene oxide adduct of a polyhydric alcohol with a fatty acid. When used as a deinking agent, this compound, which shows excellent ability to collect, aggregate and liberate ink, gives reclaimed paper having high whiteness which is contaminated with little unliberated ink.

Description: This invention relates to a deinking agent to be used for the reclamation of waste paper such as is used newspapers, OA (office automation) papers, magazines and books. More particularly, it relates to a deinking agent excellent in its ability to collect, aggregate and liberate ink. Therefore, a deinked pulp having high whiteness and contaminated with little unliberated ink can be obtained by deinking, for example, newspapers, OA papers, magazines and books with the deinking agent of the present invention by a flotation method, a washing method or a combined flotation/washing method. It has become the practice to reclaim printed waste paper including newspapers and magazines. Recently, the uses for deinked pulp have been enlarged and advanced. On the other hand, the effective utilization of waste paper has become more and more important in order to reduce paper manufacturing costs. Further, the reclamation of waste paper is highly valuable from the viewpoints of saving energy, refuse collection in urban communities and conservation of forest resources. On the other hand, recent improvements in printing techniques, printing systems and ingredients of printing inks have made it difficult to deink waste paper. In order to facilitate deinking, therefore, attempts have been made to improve deinking devices. Deinking agents may be roughly classified into two types, namely, dispersion-type deinking agents whereby liberated ink is removed from the system in a finely dispersed state (mainly involving nonionic surfactants), and aggregation-type deinking agents whereby liberated ink is aggregated to a certain degree and then removed from the system. Known chemicals which have been employed as such deinking agents for reclaiming waste paper include anionic surfactants (for example, alkylbenzene sulfonates, alkyl sulfates, α-olefin sulfonates, dialkyl sulfosuccinates, higher fatty acid salts), nonionic surfactants (for example, higher alcohol ethylene oxide adducts, alkyl phenol ethylene oxide adducts, fatty acid ethylene oxide adducts, fatty acid amide ethylene oxide adducts, polypropylene glycol ethylene oxide adducts, fat ethylene oxide adducts, higher alcohol ethylene oxide propylene oxide adducts) and ampholytic surfactants (for example, amine oxides, alkyl betaines). In addition, JP-A-57-117690 discloses a deinking agent obtained by reacting a polyoxyalkylene adduct of a polybasic acid, the reaction being only with a dibasic acid. Although this compound shows deinking performance to a certain degree, it is not always satisfactory (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). However, these chemicals and blends thereof would not always show a sufficiently high deinking efficiency in the flotation stage. Thus, they do not always give a reclaimed paper having high whiteness which is contaminated with less unliberated ink. When a fatty acid which is in the form of a solid at room temperature is used, it shows excellent ability to aggregate ink but a number of unliberated ink spots are frequently formed. Further, high cost for supplying energy for melting the solid fatty acid is involved. When a fatty acid salt is used as such or in the form of an aqueous solution, the obtained reclaimed pulp shows low whiteness. When a fatty acid which is in the form of a liquid at room temperature is used, it suppresses foaming of a surfactant employed as a foaming agent and thus the liberated ink cannot be fully removed from the system. As a result, the whiteness of the pulp thus reclaimed cannot be increased. Although common nonionic surfactants are excellent in their ability to disperse ink, detergency and foaming properties, they result in only poor aggregation of ink. Therefore, the reclaimed pulp obtained will not always show high whiteness. As described above, there has been found no chemicals which are excellent in all characteristics including the liberation of ink from waste paper and aggregation of the liberated ink in the pulping stage as well as foaming properties and the ability to collect ink in the flotation stage. Thus, the general practice is to combine or blend two or more specific chemicals. Although a deinking method using a blend thus obtained exerts effects at a certain level, it is not always satisfactory. In recent years, the utilization of deinked pulp has been enlarged and the mixing ratio thereof with fresh pulp has been increased. As a result, contamination of the deinked pulp with unliberated ink spots, which are not removed from waste paper, has become a serious problem. In addition, waste paper which can hardly be deinked (for example, OA paper with the use of toners) has recently been more and more employed. Under these circumstances, it has been urgently required to develop a deinking agent having an improved ability to liberate ink. German Patent Application DE-3401444 reveals a method of deinking and regenerating waste paper. A deinking agent comprising a polyethylene oxide ester of a carboxylic acid is contained as an active ingredient. The agent must also contain at least one propyl or butyl oxide group in order to function properly. SUMMARY OF THE INVENTION Therefore, the present inventors conducted extensive research in order to find a deinking agent free from the above-mentioned disadvantages, thus reaching the present invention. The deinking agent for the reclamation of waste paper of the present invention comprises the following reaction products: a reaction product which is obtained by reacting a reaction product obtained by adding 10 or more mols, per mol of a polyhydric alcohol, of alkylene oxide(s) to the polyhydric alcohol (the added 10 or more mols alkylene oxide(s), namely, polyoxyalkylene group(s), are selected from among ethylene oxide, propylene oxide and butylene oxide and may be either a random polymer chain or a block polymer chain when two or more kinds of the oxyalkylene groups are present) with at least one of the compounds represented by the following general formulae (1), (2), (3) and (4). General formula (1): wherein R₁ represents an alkyl or alkenyl group having 5 to 30 carbon atoms. General formula (2): wherein R₂ represents an alkyl or alkenyl group having 5 to 30 carbon atoms; and R₃ and R₄ both represent hydrogen atoms or either one represents an alkyl or alkenyl group having 1 to 8 carbon atoms and the other represents a hydrogen atom. General formula (3): wherein R₅ represents an alkyl or alkenyl group having 5 to 30 carbon atoms; and A₁O represents a polyoxyalkylene group formed by polymerizing oxyalkylene groups having 2 to 4 carbon atoms which may be either a random polymer chain or a block polymer chain when two or more kinds of the oxyalkylene groups are present and n represents a number of 1 or above so as to give a number average molecular weight to the corresponding polyoxyalkylene group of 10,000 or less. General formula (4): R₆-COOH wherein R₆ represents an alkyl or alkenyl group having 5 to 21 carbon atoms or an alkylphenyl or alkenylphenyl group having an alkyl or alkenyl group having 3 to 20 carbon atoms. The deinking agent of the present invention for the reclamation of waste paper comprising a reaction product, which is obtained by, for example, further reacting a specific dibasic acid or fatty acid with a polyoxyalkylene oxide adduct obtained by adding alkylene oxide(s) to a polyhydric alcohol, is superior to those obtained by merely reacting a dibasic acid such as maleic or succinic acid in its ability to collect, deterge, disperse and aggregate ink and in its foaming properties. Thus, the compound of the present invention shows good deinking performance when employed alone. In addition, it is in the form of a liquid and thus can be easily handled, different from, for example, fatty acids. DETAILED DESCRIPTION OF THE INVENTION The present invention will how be described in detail. Any method may be arbitrarily selected in order to add alkylene oxide(s) to a polyhydric alcohol to thereby give the polyoxyalkylene adduct, so long as the desired compound can thereby be obtained. Examples of the polyhydric alcohol used here include ethylene glycol, propylene glycol, trimethylene glycol, butylene glycol, glycerol, trimethylolpropane, trimethylolethane, 1,2,4-butanetriol, 1,2,6-hexanetriol, 1,1,1-trimethylolhexane, pentaerythritol, tetramethylol cyclohexanol and diglycerol. The compound represented by general formula (1) used in the present invention, which is an alkylsuccinic anhydride or an alkenylsuccinic anhydride, may be obtained by any method so long as the desired compound can thereby be synthesized. The alkyl and alkenyl groups may either be the same or different from each other in carbon atom number. Further, either straight-chain compounds or branched compounds may be used. However, it is undesirable that the carbon atom number of R₁ is 31 or more, since the compound is liable to solidify in this case and, further, the deinking performance of the reaction product obtained by reacting the compound with a polyoxyalkylene adduct obtained by adding alkylene oxide(s) to a polyhydric alcohol is deteriorated. In addition, it is not usual to use the carbon number of 4 or less in R₁, since the compound becomes vapor. The compound represented by general formula (2) used in the present invention, which is an alkylsuccinic acid, an alkenylsuccinic acid or an alkyl or alkenyl monoester thereof, may be obtained by any method so long as the desired compound can thereby be synthesized. The alkyl and alkenyl groups in the alkylsuccinic or alkenylsuccinic acid may be either the same or different from each other in carbon atom number. Further, either straight-chain compounds or branched compounds may be used. However, it is undesirable that the carbon atom number of R₂ is 31 or more, since the compound is liable to solidify in this case and, further, the deinking performance of the reaction product obtained by reacting the compound with a polyoxyalkylene adduct obtained by adding alkylene oxide(s) to a polyhydric alcohol is deteriorated. When R₃ and R₄ represent alkyl or alkenyl groups having 9 or more carbon atoms, the deinking performance of the product obtained by reacting the compound is deteriorated. The compound represented by general formula (3) used in the present invention, which is obtained by esterifying 1 mol of an alkylsuccinic acid or an alkenylsuccinic acid with 1 mol of a polyalkylene glycol obtained by preliminarily polymerizing alkylene oxide(s), may be obtained by any method so long as the desired compound can thereby be synthesized. The alkyl and alkenyl groups in the alkyl or alkenyl succinic acid may either be the same or different from each other in carbon atom number. Further, either straight-chain compounds or branched compounds may be used. However it is undesirable that the carbon atom number of R₅ is 31 or more or the number average molecular weight of A₁O is 10,000 or more, since the deinking performance of the reaction product obtained by reacting the compound is deteriorated. The compound represented by general formula (4) used in the present invention is a fatty acid. Examples thereof include straight-chain fatty acids (for example, lauric acid, stearic acid), unsaturated fatty acids (for example, oleic acid) and branched fatty acids (for example, isostearic acid). Either saturated or unsaturated and straight-chain or branched fatty acids may be used in the present invention. The reaction for producing a reaction product by reacting a reaction product, which is obtained by adding alkylene oxide(s) to a polyhydric alcohol, with at least one of the compounds of general formulae (1), (2), (3) and (4) may be performed by any method so long as the desired product can thereby be obtained. When two or more compounds from general formulae (1) to (4) are selected, they may be successively reacted one by one so as to give the desired product. For example, 1 mol of a reaction product obtained by adding alkylene oxides to a polyhydric alcohol is reacted with a given amount of a compound represented by general formula (2) and then 1 mol of the resulting product is reacted with a given amount of a compound represented by general formula (4), to thereby give the desired deinking agent for the reclamation of waste paper. As one example, 1 mol of alkylene oxide adduct of glycerine is mixed with 1 mol of alkenylsuccinic acid monomethyl ester having C₁₆ alkenyl group and 2 mol of stearic acid and reacted at 200°C for 1.5 hours to obtain the desired deinking agent for the reclamation of waste paper. Although the deinking agent of the present invention shows good deinking performance when employed alone, it may be blended or combined with other deinking agents. For example, the deinking agent of the present invention may be used together with a conventionally used deinking agent (e.g., fatty acids, fatty acid derivatives, nonionic surfactants, cationic surfactants, anionic surfactants) in any desired ratio. In the reclamation of waste paper, the deinking agent of the present invention may be added either at the pulping stage or the soaking tower stage. The amount of the deinking agent may vary depending on the quality of the waste paper and the type of ink (for example, letterpress ink and offset ink). It is generally appropriate to add 0.1 to 0.8% by weight, still preferably 0.2 to 0.6% by weight, based on the dry starting waste paper, of the deinking agent. In the compounds of general formulae (1), (2), (3) and (4), which are to be reacted with a polyoxyalkylene adduct obtained by adding alkylene oxide(s) to a polyhydric alcohol, it is particularly preferable, in order to achieve the objects of the present invention, that R₁, R₂ and R₅ each represents an alkyl or alkenyl group having 12 to 20 carbon atoms, that R₃ and R₄ each represents an alkyl or alkenyl group having 1 to 3 carbon atoms; and that R₆ represents an alkyl or alkenyl group having 11 to 17 carbon atoms. In addition, the deinking agent of the present invention may further comprise a third component. For instance, the deinking agent of the present invention may be used together with a conventionally used deinking agent (e.g., fatty acids, fatty acid derivatives, nonionic surfactants, cationic surfactants, anionic surfactants) in any desired ratio. In particular, when the deinking agent of the present invention is used with fatty acids, it is also possible to use the deinking agent of the present invention together with a polyvalent metal salt (for example, calcium chloride, magnesium chloride, magnesium hydroxide, calcium hydroxide, ammonium sulfate). By this, it is possible to make a fatty acid an insoluble salt and to remove the insoluble salt from the system. To further illustrate the present invention, and not by way of limitation, the following Examples are given. EXAMPLES 1 TO 28 By using each of the compounds of the present invention of the formulations listed in Table 1 (samples No. 1 to 28) as a deinking agent, a deinking test was performed in accordance with "Method for Determining the Deinkability of Wastepaper" specified by Japan Technical Association of the Pulp and Paper Industry (J. TAPPI: No. 39-82). For example, the deinking agent No. 14 shown in Table 1 was prepared as follows. In a flask, a reaction product which was obtained by reacting 35 mol of ethylene oxide and 20 mol of propylene oxide to 1 mol of glycerol, was mixed with 1 mol of alkenylsucinic acid monomethyl ester having C₁₆ alkenyl group and 2 mol of stearic acid, and reacted at 200°C for 1.5 hours to obtain the deinking agent No. 14. The other deinking agents shown in Table 1 were prepared according to the similar manner. Waste paper comprising 70% by weight of newspapers (Mainichi, Asahi and Yomiuri) printed 1 to 3 months ago and 30% by weight of leaflets were cut into pieces (about 5mm × 10mm) and a given amount thereof was fed into a bench disintegrator. Then, 5.0% by weight (based on the dry starting waste paper) of 70°C warm water, 1.4% by weight (based on the dry starting waste paper) of sodium hydroxide, 2.8% by weight (based on the dry starting waste paper) of sodium silicate No. 3, 1.0% by weight (based on the dry starting waste paper) of hydrogen peroxide (on a pure basis) and 0.2% by weight (based on the dry starting waste paper) of each of the deinking agents listed in Table 1 were added thereto. After disintegrating at a pulp concentration of 5% by weight at 60°C for 10 minutes, the mixture was soaked at 50°C for 1 hour. After diluting with water to give a pulp concentration of 1% by weight based on water, the mixture was subjected to flotation at 30°C for 10 minutes in a test flotator. (Amount of air is 10 liter per minute.) After the completion of the flotation, the pulp slurry was concentrated by squeezing using a nylon net having 100 meshes to thereby give a concentration of 10% by weight and then diluted with water to give a pulp concentration of 1% by weight. Next, it was treated with a TAPPI standard machine to thereby form a pulp sheet. The whiteness of the pulp sheet thus obtained was measured with a color difference meter (Z-1001DP; product of Nippon Denshoku K.K.) in accordance with JIS Z8722 and the number of unliberated ink spots contained therein and unliberated ink areas were determined using an image analyzer (Dot Analyzer DA-3000 (object glass: 5 x magnification); product of KS System Co.). Table 2 summarizes the results. COMPARATIVE EXAMPLES 1 TO 7 Four common marketed deinking agents C₁₃H₂₇COOH, C₁₂H₂₅(EO)₁₀H, HOOC(CH₂)₄COOH shown in Table 3 and others shown in Table 4 were subjected to the same test as described above to thereby evaluate the deinking performances thereof. Tables 3 and 4 summarize the results. In Table 1, EO represents an ethylene oxide unit, PO represents a propylene oxide unit and A₁O and A₂O each represents an alkylene oxide unit. The deinking agent of the present invention, which is obtained by reacting a polyoxyalkylene adduct, obtained by adding alkylene oxide(s) to a polyhydric alcohol, with a specific dibasic acid or a fatty acid, is excellent in its ability to collect, aggregate and liberate ink. Thus, paper reclaimed with the deinking agent of the present invention has high whiteness and is contaminated with less unliberated ink spots, compared with those reclaimed with a conventional deinking agent. While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

Claims: A deinking agent for the reclamation of waste paper comprising a reaction product which is obtained by reacting (A) a reaction product obtained by adding 10 or more mols of (A) (i) alkylene oxide(s), expressed as polyoxyalkylene groups, being selected from the group consisting of ethylene oxide, propylene oxide and butylene oxide, wherein the alkylene oxide(s) may be either a random polymer chain or a block polymer chain when two or more kinds of oxyalkylene groups are present, per mol of (A) (ii) a polyhydric alcohol, with (B) at least one of the compounds represented by the following formulae (1), (2), (3) and (4): formula (1): wherein R₁ represents an alkyl or alkenyl group having 5 to 30 carbon atoms; formula (2): wherein R₂ represents an alkyl or alkenyl group having 5 to 30 carbon atoms; and R₃ and R₄ both represent hydrogen atoms or either one represents an alkyl or alkenyl group having 1 to 8 carbon atoms and the other represents a hydrogen atom; formula (3): wherein R₅ represents an alkyl or alkenyl group having 5 to 30 carbon atoms; and A₁O represents a polyoxyalkylene group formed by polymerizing oxyalkylene groups having 2 to 4 carbon atoms which polyoxyalkylene group may be either a random polymer chain or a block polymer claim when two or more kinds of the oxyalkylene groups are present; and n represents a number of 1 or above so as to give a number average molecular weight to the corresponding polyoxyalkylene group of 10,000 or less; and formula (4): R₆-COOH wherein R₆ represents an alkyl or alkenyl group having 5 to 21 carbon atoms or an alkylphenyl or alkenylphenyl group having an alkyl or alkenyl group having 3 to 20 carbon atoms. A deinking agent for the reclamation of waste paper as claimed in Claim 1, which further comprises at least one other deinking agent. A deinking agent for the reclamation of waste paper as claimed in Claim 1, which is used in an amount of from 0.1 to 0.8% by weight based on the dry starting waste paper. A deinking agent for the reclamation of waste paper as claimed in Claim 2, which is used in an amount of from 0.1 to 0.8% by weight based on the dry starting waste paper. A deinking agent for the reclamation of waste paper as claimed in Claim 1, which comprises a product obtained by reacting 0.5 mol or more of at least one of the compounds represented by formulae (1), (2), (3) and (4) with 1 mol of the reaction product obtained by adding 10 mols or more of alkylene oxide(s) per mol of the polyhydric alcohol. A deinking agent for the reclamation of waste paper as claimed in Claim 5, which further comprises at least one other deinking agent. A deinking agent for the reclamation of waste paper as claimed in Claim 5, which is used in an amount of from 0.1 to 0.8% by weight based on the dry starting waste paper. A deinking agent for the reclamation of waste paper as claimed in Claim 6, which is used in an amount of from 0.1 to 0.8% by weight based on the dry starting waste paper. A deinking agent for the reclamation of waste paper as claimed in Claim 1, which comprises a product obtained by reacting 1 mol or more of the compound represented by formula (4) with 1 mol of the reaction product obtained by adding 10 mols or more of alkylene oxide(s) per mol of the polyhydric alcohol. A deinking agent for the reclamation of waste paper as claimed in Claim 9, which further comprises at least one other deinking agent. A deinking agent for the reclamation of waste paper as claimed in Claim 9, which is used in an amount of from 0.1 to 0.8% by weight based on the dry starting waste paper. A deinking agent for the reclamation of waste paper as claimed in Claim 10, which is used in an amount of from 0.1 to 0.8% by weight based on the dry starting waste paper.

Inventors: AIZONO HIROFUMI, NAKAMURA TAKASHI, TAKAHASHI YOSHIO, TAKETOMI YASUAKI, AIZONO, HIROFUMI, NAKAMURA, TAKASHI, TAKAHASHI, YOSHIO, TAKETOMI, YASUAKI
Applicants: MITSUBISHI OIL CO, MITSUBISHI OIL COMPANY, LIMITED
Application year: 1991
Main classification: C09D9
IPC codes: D21C5, C09D9