Method and Composition for Detackifying Organic Contaminants in the Process of Pulping and Papermaking

Abstract

The present invention discloses a method for detackifying organic contaminants in the process of pulping and papermaking and a composition used for the same. Specifically, the invention discloses that the water circulation system of pulping and papermaking process can be provided with non-ionic cellulose ether and cationic coagulant in lower amount, through which, the deposition of organic contaminants can be inhibited under the synergistic action of pre-coagulation and detackification.

Claims

1-20. (canceled)

21. A method of detackifying organic contaminants in a pulp process comprising: adding polyaluminum chloride (“PAC”) and hydroxypropyl methyl cellulose (“HPMC”) having a molar degree of substitution of from 0.01 to 3 into a papermaking pulp, wherein the HPMC and the PAC are added at a HPMC-to-PAC ratio of 1:0.5 to 1:20.

22. The method of claim 21, wherein the HPMC has a molecular weight of from 10,000 to 1,000,000.

23. The method of claim 22, wherein the HPMC has a molecular weight of from 50,000 to 500,000.

24. The method of claim 23, wherein the HPMC has a molar degree of substitution of from 0.5 to 2.8.

25. The method of claim 23, wherein the HPMC has a molecular weight of from 80,000 to 250,000.

26. The method of claim 25, wherein the HPMC has a molar degree of substitution of from 1.5 to 2.5.

27. The method of claim 21, wherein the HPMC and the PAC are added at a HPMC-to-PAC ratio of 1:1 to 1:10.

28. The method of claim 21, wherein the papermaking pulp comprises at least one of recycled pulp, coated broke, deinked pulp, mechanical pulp, and high-yield pulp.

29. A composition useful for detackifying organic contaminants in the process of pulping or papermaking comprising polyaluminum chloride (“PAC”) and hydroxypropyl methyl cellulose (“HPMC”) having a molar degree of substitution of from 0.01 to 3, wherein the HPMC and PAC are present in the composition at a HPMC-to-PAC ratio of 1:0.5 to 1:20.

30. The composition of claim 29, wherein the molecular weight of the HPMC is from 10,000 to 1,000,000

31. The composition of claim 29, wherein the HPMC and the PAC are present in the composition at a HPMC-to-PAC ratio of 1:1-1:10.

32. The composition of claim 29, wherein the HPMC has a molar degree of substitution of from 0.5 to 2.8.

33. The composition of claim 29, wherein the HPMC has a molar degree of substitution of from 1.5 to 2.5.

34. The composition of claim 29, wherein the HPMC has a molar degree of substitution of methoxy group from 0 to 3.

35. The composition of claim 29, wherein the HPMC has a molar degree of substitution of methoxy group from 1.5 to 2.

36. The composition of claim 29, wherein the HPMC has a molar degree of substitution of hydroxypropyl group from 0.01 to 0.5.

37. The composition of claim 29, wherein the HPMC has a molar degree of substitution of hydroxypropyl group from 0.1 to 0.3.

38. The composition of claim 29, wherein the composition is a liquid.

39. The composition of claim 29, wherein the composition is a powder.

40. The composition of claim 29, wherein the composition is an emulsion, dispersion, or slurry in an aqueous carrier.

Description

DESCRIPTION OF THE INVENTION

[0019] The purpose of the invention is to provide a detackifying treatment for organic contaminants to inhibit and control the deposition of organic contaminants in the process of pulping and papermaking. By adopting the method according to the invention, good detackifying results can be realized by very low amount of composite detackifier, so that the deposition of organic contaminants can be inhibited or controlled effectively. Wherein, in the field of the invention, detackifying treatment is to make organic contaminants absorb a water hydration layer by means of surface passivation to improve its surface energy and hydrophilicity, in order to achieve the purpose of reducing the deposition of the organic contaminants.

[0020] For this purpose, the invention discloses a method for detackifying organic contaminants in the process of pulping and papermaking, comprising adding an effective dose of non-ionic cellulose ether and cationic coagulant into water circulation system of pulping and papermaking process.

[0021] The invention further discloses a composition used for detackifying organic contaminants in the process of pulping and papermaking, comprising non-ionic cellulose ether and cationic coagulant.

[0022] The method and detackifying composition of the invention realize good detackification of organic contaminants though the synergistic effect of non-ionic cellulose ether and cationic coagulant. Cationic coagulant catches colloidal and/or micro-sized pitch and stickies etc. to form particle aggregates with the controllable size of generally less than 100-150 micrometers by means of pre-coagulation; while hydrophilic non-ionic cellulose ether may be adsorbed onto the surfaces of these pre-coagulated aggregates by physical means, so as to make them better dispersed into the water system due to improved hydration, rather than deposited in the system of pulping and papermaking or retention to the surface of paper fibers.

[0023] After a plurality of experiments, the inventors find that aforementioned synergistic action, comparing with the prior art of detackification technology, significantly enhances the absorbability of non-ionic cellulose ether to organic contaminants to realize effective detackification of organic contaminants at relatively lower dose of detackifier composition.

[0024] In the present invention, non-ionic cellulose ether may be selected from hydroxyethyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, hydroxybutyl methyl cellulose, hydroxybutyl cellulose or the combination thereof. It is well known in prior art that the above-listed non-ionic cellulose ethers have relatively good water solubility and are cheap and easy to access.

[0025] In the presence of cationic coagulant, non-ionic cellulose ether with high molecular weight has better fluidity, and detackification capability of non-ionic cellulose ether has been significantly improved. Therefore, comparing with prior art, the method of the invention may have more broad selection of non-ionic cellulose ethers. In actual production, various non-ionic cellulose ethers and combinations thereof can be selected in response to the requirement of operating parameter in the process.

[0026] In the present invention, for the reason that there is no need for non-ionic cellulose ether to conduct special chemical modification, the process can be more simple and easy, which leads substantially same or similar result of organic contaminants detackification.

[0027] As for molecular weight of non-ionic cellulose ether, 10,000-1,000,000 is preferred, more preferred 50,000-500,000, and most preferred 80,000-250,000. Non-ionic cellulose ether in the said molecular weight range will have an improved synergistic effect with cationic coagulant.

[0028] A recommended molar degree of substitution of non-ionic cellulose ether of 0.01-3.0, 0.5-2.8 is preferred, and 1.5-2.5 is more preferred. In one embodiment of the invention, the molar degree of substitution of methoxy group of non-ionic cellulose ether may be 0-3.0, preferred 1.5-2.0; molar degree of substitution of hydroxypropyl group may be 0.01-0.5, preferred 0.1-0.3. Non-ionic cellulose ether with such range of degree of substitution will have improved synergy effect with cationic coagulant.

[0029] In the present invention, the cationic coagulant may be either inorganic coagulant or organic cationic coagulant. Wherein, inorganic coagulant includes but is not limited to aluminum sulfate, aluminum chloride, ferric sulfate, ferric chloride, polyaluminum sulfate, polyaluminum chloride, aluminum chlorohydrate, polyaluminum sulfate chloride, polyaluminum silicate chloride, polyferric chloride, polyferric sulfate, polyferric sulfate chloride, polyferric silicate chloride, and their combination. Organic cationic coagulant includes but is not limited to linear or crosslinked copolymers of epihalohydrin and aliphatic amine, poly (diallyl dimethyl ammonium chloride), copolymer and terpolymer containing cationic monomer of tertiary amino carboxylate, diallyl dimethyl ammonium chloride or vinylamine, melamine-formaldehyde resin, cationic starch, chitosan, cationic guar gum, and their combination.

[0030] In the present invention, the proportion of non-ionic cellulose ether and cationic coagulant (by weight) in the detackifier composition may be 1:0.1-1:100, more preferred 1:0.5-1:20, and most preferred 1:1-1:10. The proportion of non-ionic cellulose ether and cationic coagulant (by weight) may be varied in response to the source of pulp, the quantity and chemical properties of organic contaminants, or operating parameters in the process of pulping and papermaking.

[0031] In the present invention, the dosage of detackifier composition is the effective dosage for organic contaminants detackification, which is the understandable common content for those skilled in the art. The dosage that can be varied in response to tonnage of pulp to be treated and volume of water circulation system, is commonly 0.05-20 kilograms per ton of dry pulp base. Due to the synergy effect of non-ionic cellulose ether and cationic coagulant in the present invention, the dosage of the detackifier composition in the present invention which is preferred 0.1-5 kilograms per ton of dry pulp base, more preferred 0.25-2.5 kilograms per ton of dry pulp base, can be lower than that of prior art, based on same effect of detackification.

[0032] The detackifier composition of the present invention is effective for treating all pulps, including but not limited to recycled pulp, coated broke, deinked pulp, mechanical pulp, high-yield pulp, or combinations thereof. Furthermore, the detackifier composition of the present invention is effective for treating white water.

[0033] Wherein, organic contaminants in the present invention means interfering substances which have permanent or temporary physical tackiness and may impact the runnability of the paper machine and cause quality problems of paper, particularly means pitch and stickies produced in the process of pulping and papermaking.

[0034] In the present invention, the composition comprising non-ionic cellulose ether and cationic coagulant may be added at the same time at any stage of the process of pulping and papermaking, or non-ionic cellulose ether and cationic coagulant can be separately added at any stage. It is only necessary to guarantee that the said non-ionic cellulose ether and the said cationic coagulant would join together in pulp or in water circulation system of paper machine.

[0035] In the present invention, the composition comprising non-ionic cellulose ether and cationic coagulant may be added in any form (such as liquid, powder, aqueous carrier, etc.) in the process of pulping and papermaking.

[0036] In the present invention, the composition comprising non-ionic cellulose ether and cationic coagulant may be added by any means (such as injection, sprinkling, spraying, etc.) in the process of pulping and papermaking.

[0037] Furthermore, after treated by the method of the present invention, the organic contaminants, of which hydrophilicity is improved, can be better dispersed in the water system to effectively prevent the organic contaminants from precipitation and deposition onto papermaking equipment. Finally, the solution, with a plurality of organic contaminants dispersed, will be discharged out of circulation system of paper machine in mode of waste water discharge or in any other known mode.

[0038] Comparing with the prior art, the method for detackifying organic contaminants in the process of pulping and papermaking and composition used for the same disclosed by the present invention has the following advantages:

[0039] First, by pre-coagulation assisted detackification synergistic action of non-ionic cellulose ether and cationic coagulant, the adsorption of non-ionic cellulose ether to pitch and stickies has been enhanced to realize effective detackifying at lower amount of detackifier, so that the purpose of inhibiting deposits is achieved.

[0040] Second, there is no need to conduct any chemical modification to non-ionic cellulose ether used in the present invention. The process is simple and of low cost, which is easier to be operated and realized.

[0041] Third, the detackification of method and composition according to the present invention may not be affected by the pH and hardness of papermaking plant water system; meanwhile, the addition of cationic coagulant in the present invention can additionally provide ionic balance for stickies, which is particularly helpful for inhibiting and removing anionic trashes in paper fiber.

[0042] Fourth, foaming control performance resulted by adding and diluting detackifier composition is clearly greater than that of surfactant-type pitch control dispersant in the process of pulping and papermaking.

[0043] Fifth, the detackifier composition of the present invention may be applicable together with most chemical additives such as wet end retention, sizing, dry strength/wet strength additives etc. There is no negative effect on the operation of paper machine by the use of the composition itself and together with other chemical additives.

PREFERRED EMBODIMENT

[0044] Standard pitch deposition test is used to evaluate the deposition inhibition effect of the detackifier composition and the method disclosed in the present invention on organic contaminant:

[0045] Standard pulp sample with 1.4% pulp consistency and Canadian standard freeness in the range of 450-500 mL at 20° C. is prepared using dry pulp laps in deionized water by Valley Beater. A synthetic pitch solution in isopropanol (i.e., 1 wt. %, 100 mL), and a calcium chloride solution (i.e., 5000 ppm as calcium ions, 5 mL) were added into 1 L standard pulp sample sequentially. Synthetic contaminants to be tested, of which both composition and proportion consistent with the those of wood pitch in hardwood and softwood (see the following table), is dispersed uniformly in the standard pulp sample in the form of colloids by gentle stirring. The only difference is that the pitch content in standard pulp sample used in test is much higher than actual content. Standard pulp sample is heated to 50° C. Stirring is continued for 1.5 hour at a constant stirring rate while the temperature is maintained. Meanwhile, the technique of quartz crystal microbalance (QCM) was applied to monitor the accumulated deposit mass on quartz crystal. The performance of the detackifier composition is also tested, wherein, after pulp sample to be tested is heated to 50° C., a certain dosage of composition is added for pre-treatment, then QCM test is conducted. Other preparation steps are the same.

TABLE-US-00001 Table of Synthetic Pitch Compositions Abietic acid  5-50% Oleic acid 10-25% Palmitic acid  5-10% Corn oil 10-35% Oleyl alcohol 2.5-7.5% Methyl stearate  5-15% Beta-sitosterol 2.5-7.5% Cholesteryl caproate 2.5-7.5%

Example 1

[0046] Hydroxyethyl cellulose (HEC) aqueous solution (8 wt. %) and epichlorohydrin-dimethylamine cross-linked copolymer (Epi-DMA) water solution (50 wt. %) is mixed with different combination proportion (proportion of 80/20, 60/40, 40/60 and 20/80 by weight); meanwhile, the detackification of organic contaminant for each composition is assessed by standard pitch deposition test. It can be seen from Table-1 that the compositions with certain proportion can detackify organic contaminants more effectively than either hydroxyethyl cellulose or organic cationic coagulant.

[0047] Wherein, blank test is a test during which any detackifier is not added.

TABLE-US-00002 TABLE 1 Pitch Deposition Test Results of Hydroxyethyl Cellulose/Organic Cationic Coagulant Compositions Weight of accumulated Dosage pitch deposits Detackification (ppm) (mg) (%) Blank test — 93.0 0 HEC (8 wt % aq. solution) 10 33.4 61.4 Epi-DMA (50 wt % aq. 10 13.7 85.3 solution) HEC (8 wt %)/Epi-DMA 10 24.3 73.9 (50 wt %) composition-80/20 HEC (8 wt %)/Epi-DMA 10 15.6 83.2 (50 wt %) composition-60/40 HEC (8 wt %)/Epi-DMA 10 8.9 90.4 (50 wt %) composition-40/60 HEC (8 wt %)/Epi-DMA 10 9.7 89.6 (50 wt %) composition-20/80 HEC (8 wt % aq. solution) 25 21.6 76.8 Epi-DMA (50 wt % aq. 25 7.4 92.0 solution) HEC (8 wt %)/Epi-DMA 25 7.4 92.0 (50 wt %) composition-80/20 HEC (8 wt %)/Epi-DMA 25 4.3 95.4 (50 wt %) composition-60/40 HEC (8 wt %)/Epi-DMA 25 2.6 97.2 (50 wt %) composition-40/60 HEC (8 wt %)/Epi-DMA 25 6.1 93.4 (50 wt %) composition-20/80

Example 2

[0048] Hydroxypropyl cellulose (HPC) aqueous solution (4 wt. %) and cationic starch (CS) aqueous solution (22 wt. %) is mixed with different combination proportion (proportion of 80/20, 60/40, 40/60 and 20/80 by weight); meanwhile, the detackification of organic contaminants for each composition is assessed by standard pitch deposition test. It can be seen from Table-2 that the compositions with certain proportion can detackify organic contaminants more effectively than either hydroxylpropyl cellulose or organic cationic coagulant.

TABLE-US-00003 TABLE 2 Pitch Deposition Test Results of Hydroxypropyl Cellulose/Organic Cationic Coagulant Compositions Weight of accumulated Dosage pitch deposits Detackification (ppm) (mg) (%) Blank test — 59.6 0 HPC (4 wt % aq. solution) 10 48.4 18.8 CS (22 wt % aq. solution) 10 12.8 78.5 HPC (4 wt %)/CS (22 wt %) 10 29.8 50.0 composition-80/20 HPC (4 wt %)/CS (22 wt %) 10 7.5 87.4 composition-60/40 HPC (4 wt %)/CS (22 wt %) 10 4.9 91.8 composition-40/60 HPC (4 wt %)/CS (22 wt %) 10 5.8 90.3 composition-20/80 HPC (4 wt % aq. solution) 25 32.9 44.8 CS (22 wt % aq. solution) 25 4.1 93.1 HPC (4 wt %)/CS (22 wt %) 25 7.9 86.7 composition-80/20 HPC (4 wt %)/CS (22 wt %) 25 5.1 91.4 composition-60/40 HPC (4 wt %)/CS (22 wt %) 25 2.9 95.1 composition-40/60 HPC (4 wt %)/CS (22 wt %) 25 4.1 93.1 composition-20/80

Example 3

[0049] Hydroxypropyl methyl cellulose (HPMC) aqueous solution (5 wt. %) and polyaluminum chloride (PAC) aqueous solution (50 wt. %) is mixed with different combination proportion (proportion of 80/20, 60/40, 40/60 and 20/80 by weight); meanwhile, the detackification of organic contaminants for each composition is assessed by standard pitch deposition test. It can be seen from Table-3 that the compositions with certain proportion can detackify organic contaminants more effectively than either hydroxypropyl methyl cellulose or inorganic coagulant.

TABLE-US-00004 TABLE 3 Pitch Deposition Test Results of Hydroxypropyl Methyl Cellulose/Inorganic Compositions Weight of accumulated pitch Dosage deposits Detackification (ppm) (mg) (%) Blank test — 77.1 0 HPMC (5 wt % aq. solution) 10 24.3 68.5 PAC (50 wt % aq. solution) 10 31.7 58.9 HPMC (5 wt %)/PAC (50 wt %) 10 9.5 87.7 composition-80/20 HPMC (5 wt %)/PAC (50 wt %) 10 5.6 92.7 composition-60/40 HPMC (5 wt %)/PAC (50 wt %) 10 8.5 89.0 composition-40/60 HPMC (5 wt %)/PAC (50 wt %) 10 12.3 84.0 composition-20/80 HPMC (5 wt % aq. solution) 25 13.4 82.6 PAC (50 wt % aq. solution) 25 15.8 79.5 HPMC (5 wt %)/PAC (50 wt 25 5.6 92.7 %) composition-80/20 HPMC (5 wt %)/PAC (50 wt %) 25 2.9 96.2 composition-60/40 HPMC (5 wt %/PAC (50 wt %) 25 4.5 94.2 composition-40/60 HPMC (5 wt %/PAC (50 wt %) 25 8 89.6 composition-20/80

[0050] The data from the Table 1-3 also indicate that low-dose of the detackifier composition of the present invention can effectively reduce tackiness of organic contaminants, so as to reduce deposition of organic contaminants effectively.

[0051] Purpose of the above embodiments is to further illuminate and describe technique scheme of the invention, rather than limiting the scope of protection of the invention. According to the content disclosed in the present invention, those skilled in the art may also conduct any modification and improvement, including proportion adjustment of non-ionic cellulose ether and cationic coagulant, selection of any non-ionic cellulose ether and cationic coagulant. Such modification and improvement are not go beyond the scope of protection.