AU622738B2

AU622738B2 - Method for avoiding pitch troubles

Info

Publication number: AU622738B2
Application number: AU45822/89A
Authority: AU
Inventors: Kunio Hata; Yuko Irie; Motoo Matsukura
Original assignee: Jujo Paper Co Ltd
Current assignee: Nippon Paper Industries Co Ltd
Priority date: 1988-12-13
Filing date: 1989-12-01
Publication date: 1992-04-16
Anticipated expiration: 2009-12-01
Also published as: JPH02160997A; CA2005087A1; CA2005087C; NO174433C; EP0374700B1; NZ231637A; DE58907179D1; NO174433B; ATE102667T1; NO894988D0; EP0374700A2; AU4582289A; ES2052874T3; EP0374700A3; NO894988L; FI895901A0; JPH0429794B2; FI96520C; FI96520B

Abstract

A process for preparing mechanical pulp and/or paper containing the mechanical pulp is described, wherein an acylglycerol lipase is used. The process according to the invention avoids the problems caused by the resins in the preparation of mechanical pulp and/or paper containing said pulp.

Description

622738 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION NAME ADDRESS OF APPLICANT: Jujo Paper Co., Ltd.

No. 4-1, Oji 1-Chome, Kita-ku, Tokyo Japan NAME(S) OF INVENTOR(S): Yuko IRIE Mocoo MATSUKURA Kunio HATA ADDRESS FOR SERVICE: DAVIES COLLISON 0* Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

00* COMPLETE SPECIFICATION FOC,. THE INVENTION ENTITLED: 0 Method for avoiding pitch troubles The following statement is a full description of this invention, including the best method of performing it known to me/us:- 6~

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0*555 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for avoiding pitch troubles in a process for the production of mechanical pulp and/or of mechanical pulp-containing paper.

2. Prior Art Mechanical pulp, such as groundwood pulp (hereinafter refered to as GP), Refiner groundwood pulp arid thermomechanical pulp are produced by a simplified mechanical treatment of grinding logs or chips by means of a grinder or refiner. The mechanical pulp, which has a defect of providing lower strength, exhibits advantages of providing higher yield, lower costs and higher opacity; compared with a chemical pulp produced by various chemicals such as alkaline chemicals. On the contrary, the wood constituents remain unchanged in tie mechanical pulp.

In general, a wood contains circa 1-10% of pitch, organic solvent-soluble extractive, besides three 1A

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major constituents composed of cellulose, hemicellulose and lignin. The amount and quality of pitch vary with wood species. However, it is well-known that softwood, i.e. a main raw material of mechanical pulp, contains a large amount of pitch constituents such as fatty acids, resin acids, glycerides, etc. In the pulping process, these pitch-constituents are released from pulp, wherein they exist in state of liberation, deposition or fiber surface, and covering thereon. That is, they transform from a fixed state to a liberated state. Pitches suspended in reused water (white-water) are microparticles of about 0.

2 2 p, which are known as the so-called "colloidal pitch".

In general, a paper is manufactured as follows: Pulps are prepared in various pulping processes, are treated in a screening process, are mixed with different auxiliaries to prepa'e a paper furnish.

A paper is made from the paper furnish on a paper machine. In a series of processes, the liberated pitch or the deposited pitch is accumulated in pipes, tanks, wire part, or press part, thereby causing the so-called pitch troubles, such as paper contaminations or paper brokes. In the production of a paper containing a large amount of mechanical pulp, pitch troubles occur -2 frequently. As one of the conventional methods for avoiding pitch troubles, there is the so-called seasoning, in which logs after felling are held outside and seasoned in a long period. As another method therefor, there is an addition of surface-active agent in a pulping or paper-making process, as demonstrated in Japanese Patent Publication No.50-2260., wherein the surface active agent includes, forexample, alkylether of polyoxyethylene with various addition moles, alkyl phenyl derivatives, chemicals containing the, is a main ingredient.

Although the above seasoning method causes the change and the decrease of pitch constituents in wood mainly by air-oxidation, it requires a broad area and a long period, for example, 3-6 monthes, or more.

Accordingly, it is practically difficult to avoid the pitch troubles only by the above seasoning method.

On the other hand, the addition of surface active agent, which is said to disperse the pitch particles and to prevent the pitch deposits, is not

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recognized as a substantial method for avoiding pitch troubles.

-3- 4* S S *5* -4- SUMMARY OF THE INVENTION It is the object of the present invention to avoid pitch troubles in a process for the production of mechanical pulp or of mechanical pulp-containing paper.

According to the present invention there is provided a method for avoiding pitch troubles in a process for t;ie production of mechanical pulp and/or of mechanical pulpcontaining paper, which comprises treating the paperstock and/or reused water by the addition of an acylglycerol lipase. The object and features of the present invention will become more apparent from the following description which is provided by way of illustration and is not intended to be limiting on the invention.

DETAILED DESCRIPTION OF THE INVENTION In order to obtain an effective method for avoiding pitch troubles, the inventors have investigated in detail: pitch constituents extracted from Japanese red pine (Pinus densiflora) as a typical pulpwood of mechanical pulp and pitch constituents deposited in a process for the production of Japanese red pine-GP and/or of paper containing the pine-GP. As a result, it has been found that the main constituents of the deposited pitch are the same as those contained 2 .':F9AT.'I24l5\l<2 j.;riL,4 in the original wood and consist mainly of triglycerides, fatty acids, resin acids and metal salts thereof. Further, it has been demonstrated that the deposited pitch contains always a large amount of triglycerides. It has been assumed that the triglyceride is responsible for one of the main constituents causing pitch troubles. From a point of view that the decomposition or removal of triglycerides by some method is effective for avoiding the pitch troubles, the inventors have investigated various chemical or biochemical methods.

~As a result, the object of the present invention has been performed by using an acylglycerol lipase, wherein the triglyceride is decomposed and thus the pitch deposits do not occur without giving harm effects on the pulp or paper qualities and on the runconditions. That is, the object of the present invention is performed by treating the paper-stock and/or reused water with an acylglycerol lipasein a

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process for the production of mechanical pulp and/or of mechanical pulp-containing paper. It is preferred that the acylglycerol lipase is that produced from at least one microorganism selected from the group consisting of _1 Aspergillus niger, Pseudomonas fluorescent, Pseudomonas fragi, Geotrichum candidum, and Candida cylindracea The acylglycerol lipase of the present invention is an enzyme for hydrolyzing triglycerides, i.e. one of the main constituents of pitch, wherein any enzyme, if it hydrolyzes triglycerides, can be used.

Microorganisms for producing the enzyme of the present invention include, for example, Aspergillus niger, Pseudomonas fluorescens, Pseudomonas fragi, Geotrichum candidum, Candida cylindricea, Mucor javanicus, Rhizopus javanicus, Rhizopus delemar, .Rhizopus niveus, fungi of genus Rhizopus and the like.

Among these fungi, Aspergillus -iger, Pseucomonas fluorescens, Pseudomonas fragi, Geotrichum candidum and Candida cylindracea are more effective.

The purer the acylglycerol lipase produced from the above microorganisms, the better the effect.

Further, the acylglycerol lipases are used alone or in Scombination. And the good effect can be obtained, too, when the acylglycerol lipase of the present invention is used in combination with other decomposition-enzymes, such as cellulase, hemicellulase, pectinase, protease, etc.

-6- -r ~-r 1 :I i i "I I In a process for production of mechanical pulp and/or of mechanical pulp-containing paper, the acylglycerol lipase of the present invention is added to a paper-stock slurry, under agitation or standing. In this case, the enzyme of the present invention is added thereto in an amount of 0.1-10000 ppm (by weight), based on the weight of mechanical pulp, the temperature is S preferably 10-70°C, more preferably 35-55°C. At less than 10OC, the enzyme functionates weakly and slowly.

S*o. At more than 70 0 C, the enzyme may become inactive. With 0ein the increased amount of the enzyme, the reaction is usually accelerated, wherein 10000 ppm of the enzyme, a based on the weight of mechanical pulp, is satisfactory, 0 0 in the calculation from the amount of triglyceride as a substrate. The addition of More than 10000 ppm of the S. ma be adde, but general@ enzymekis economically disadvantageous. The suitable pH-value is 3-11, and outside this range, the activity :0 0 of the enzyme is decreased reasonably.

In a pulping or paper-making process, there is used a large amount of water of which the major portion is recycled and reused. Since the reused water (white water) contains the pitch constituents, *the addition of -7-

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In this case, the superior effects are obtained by the direct addition of the above, acylglycerol lipase into the white water, or by the addition of so-called immobilized acylglycerol lipase or of the so-called immobilized microorganism capable of producing acylglycerol lipase extracellularly, wherein the immobilization of the enzyme or microorganism is carried out by the conventional method, such as carrierbinding-, cross-linking-, entrapment-method, etc.

Since the method of present invention causes a highly selective reaction known as an enzyme-reaction against triglyceride, and since this reaction is mild, the stock treated with the enzyme is not denatured so that the method of the present invention exerts no harm influence on the usual operation.

Pitch troubles occur in a complicate system comprising pulp' fibers, pitches, metal ions, fillers, etc. Although the reason for causing pitch troubles is not perfectly known, it is said that the pitch troubles depend upon various factors, such as pitch consistency, pulp consistency, pH-value, temperature, metal-ion consistency, metal-ion kinds and the like. In general, 8 an adsorption onto a solid surface is due to the exertion of Van der Waals-force which fixes the substance adhered onto a solid surface.

As the mutual interaction between i.he substance and the solid, there are various types of actions, among which a hydrophobic bond, a reciprocal action of dipole moments, etc. are important. And a hydrophobic or non-polar molecule or a hydrophobic *h S* molecule-portion is easily attracted to a hydrophobic or non-polar surface, whereas a hydrophilic or polar molecule is easily attracted to a polar surface.

Considering the mechanism for the pitch deposition in a pulp- or paper-making process, accordingly, tryglycerides play.the following roll. Through Van der Waals force, triglycerides, i,e. the non-polar constituent in colloidal pitch, adheres to the i hydrophobic or non-polar surface, such as the metal surface of tank, pipe, etc.; the surface of the center 4 a roll of paper-making press section; and the like. The adhered portion exerts as a nucleus, to which tht hydrophobic or non-polar molecule. or the hydrophobic molecule-portions in pitch-constituents adhere successively to form the pitch deposits.

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The mechanism for avoiding the pitch depositions according to the present invention is as follows. The acylglycerol lipase exerts on the nonpolar tryglyceride which exits in pulp surface-pitch or in colloidal pitch (such as pitch in white water) and which has high tackiness to the hydrophobic and nonpolar surface, whereby triglyceride is hydrolyzed to water-soluble glycerol and polar fatty acid.

Accordingly, the pitch depositions to hydrophobic surface of metal-pipes, chests, rolls, etc. are avoided.

*4 Since the pitch depositions are avoided in the early i stage, the growth of the pitch deposits do not occur, which avoids pitch troubles- The method of present invention has an advantage of avoiding pitch troubles, such as pitch spots and holes in a paper-web, etc., caused by pitch deposited in a process for the production of mechanical pulp and of mechanical pulp containing paper. Further, the method of the present invention has no harm effect on the paper qualities and the practical run, it is simplified and applied to a conventional pulp- and paper Smaking process without installing additional equipments.

10 The present invention will be understood more readily with reference to the following examples.

However, these examples are intended to illustrate the present invention and are not to be contrued to limit the scope of the present invention. Throughout the Examples, na'ples without enzyme-treatment are shown as "control".

[Example 1] Fresh Japanese red pine chip was extracted i with methanol, using a soxhlet extractor. 10g of the obtained extracts were dissolved in a mixed solution of 100me iaopropanol, 60me acetone and 5me water to obtain ee a pitch solution.

10me of the pitch solution were charged in a beaker containing le of water and were dispersed under vigorous stirring to prepare a pitch dispersion. In such a see* mnnan the resultant pitch was obtained in an yield of based on the weight of oven-dry chip, and it contained 31.8% triglycerides.

Then, the pH-value of the pitch dispersion was adjusted to 7 by adding hydrochloric acid and/or sodium hydroxide. The acylglycerol lipase was added thereto in ii different consistencies at various temperatures, as shown in Table 1, and was treated under gentle stirring for 4 hours to prepare a treated solution. In accordance with Tappi Routine Control Method RC-324, a cylinder built from polyethylene plate of 22cm width and 7cm length is setted 2.5cm above the water level. The adjusted solution was stirred for 30 minutes by using a Vibromixer (Linitator, manufactured by U.S. Heidon Co.) Polyethylene-cylindrical plate was taken out and dried. The weight of the deposited pitch and the percentage to untreated pulp were indicated in Table 1.

e o* 12 eS Table 1 Enzyme Temperature_____ l~oncentra- 20 0 C 40 0 C 60 0

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C n dr t i o n 4 1 0 2 m g 1 1 7 m g cnrl(100%) (100%) (100%) 93mg Li. OF( 1 500ppm 50mg 35mg 9 01mg (301.4%) (78.3%) I 28mg LOO0ppII Li. A( 2 5 0 0ppm, 66mg 54mg 9 6mg r~i p(3) 150ppm, 67mg 60mg 83mg 1(58.3%) (72.7%) 99 9

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(Note 1) Li,OF; trade name =LIPase OF (manufactured b~ Meitosangyo produced from Candida cylindracea.

(Note 2) Li,A; trade name =Lipase A (manufactured by Amano'Seiyaku Co.)t produced from Aspergillus niger.

(Note 3) Li,P; trade name Lipase P (manufactured by Amano Seiyaku produced from Pseudomonas fluorescens.

(Note 4) Concentation =Concentration of enzyme addition, based on pitch.

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[Example 2] The pH-value of the pitch dispersion was adjusted to 7 with hydrochloric acid and/or sodium hydroxide. The acyiglycerol li~ase was added thereto in an amount of 5O0ppm, based on the weight of pitch, and was stirred at 40 0 C. After a certain time, the amount of deposited pitch was obtained in the same manner as in Example 1 and was indicated in Table 2.

Table 2 ______En7zyme Temperature____ fconcentra- 2hours 4hours 6hours Kind t-o Control 105mg 101mg 107mg (100%) (100%) (100%) Li. OF SO0PPM 67mg 31mg 31mg (24.4%) Li.- GC-( 5 50Opm 85 -Mg. 70mg 59mg p. (55.1%) V U ii* 3 0 0 0

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*0S (Note 5) Li. GC-5, trade name Lipase (manufactured by Aviano Seiyaku produced from Geotrichum candidum.

14 (Example 3] 1i of a slurry containing 10g GP of 63me CSF(Canadian Standard Freeness) was prepared from Japanese red pine.

The acylglycerol lipases were added thereto in various consistencies and was treated under different pH-values in the same manner as in Example 1.

The amount of pitch deposited to polyethylenecylindrical plate was measured as shown in Example 1, and was indicated in Table 3.

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Kind Concentration (7 3 5 7 9 Control 118mg 112mg 102mg 121mg (100%) (100%) (100%) (100%) 'app Li. OF 50ppm 80mg 58mg 28mg 62mg 21mg (20.6%) lOppm -96mg Li. B( 6 50ppm 95mg 65mg 42m g 27mg (41.2w) (22.3%) Oppm 24mg S(19.8%) Li. A S0ppm. 84mg 66mg 49mg 88mg 1_ (72.7%) 0 C, Treating period 4 hours) (Note 6) Li, B; trade name Lipase B (manufactured by SAPPORO BREWERIES LIMITED), produced from Pseudomonas fraji 22-39 B.

(Note 7) Concentration- Concentration of enzyme addition, based on the weight of pulp.

(Example 4] The same sample as in Example 3 was'used. The enzyme of the present invention was added to the sampl in an amobunt of 5Oppm, based on*the weight of pitch, and wa reated in the same manner as in Example 1, at different temperatures and times. The amount of deposited pitch was measured and indicated in Table 4.

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Control u1ing l02mg ll7mg (100%) (100%) (100%) 72hours Li. OF 4hours 64mg 29mg l0 mg (85.5%) 8hours 27mg Control 2m 2m13 g (19.4%) 8 h o u r s2 5 m g 1 1 (18.7%)

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[Example 1% pulp slurry consisting of 20% of waste newspaper pulp (105 me CSF), 25% of GP (63me CSF), of thermomechanical pulp (107me CSF) and 30% of kraft pulp was prepared. e1 of this pulp slurry was used as a sample. The enzyme of the present invention was added thereto in an amount of 50ppm, based on the weight of pulp, treated at 40 0 C for 4 hours, stirred for 120 minutes by a Vibromixer equipped with polyethylene cylindrical plate. The amount of deposited pitch was measured and indicated in Table Table Amount of deposited pitch Control 65mg (100%) Lipase OF 18mg (27.7%) 19 i:il 7 [Example 6] 3e of white water obtained by filtering Japanese red pine GP in a screening-stage were used as a sample. The enzyme of the present invention was added to the sample in an amount of 0.5ppm, based on ie weight of the white water, treated at 40°C for 2 hours, and stirred with a Vibromixer for 120 minutes. The amount of pitch deposited to polyethylene cylindrical plate was measured and indicated in Table 6.

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Amount of deposited pitch Control 37mg .(100%) Li.OF 7mg (18.9%) (Example 7] A newsprint paper of circa 46g/m 2 bases weight was made by means of a Bel-Baie former multi-dryer paper machine with 5080mm width and 830m/min speed, wherein the paper stock consists of 30% GP, 45% waste newspaper pulp (deinked), 10% softwood KP and 15% thermomechanical pulp.

20 In this case, GP was prepared from red pine, and was adjusted to a freeness of 60-70 me CSF by the post refining, storaged as a stock-pulp for a while, opitionally mixed with other pulps and anxiliaries, again storaged and then fed to a paper-making process.

It takes 90 minutes from the post refiner 'through chests, tanks to the paper-making machine. The enzyme of the present invention was added to the GP slurry of 3.8% consistency before the post refiner so that Lipase OF has a concentration of 3ppm. The enzyme was continuously added to GP for two weeks.

There were determined the amounts of pitch deposited at the wire and press parts, and the interval 0 0 between the removals of pitch deposited onto the center roll. The practical output of the paper machine was, about 270 tons per day. The removal of pitch deposited on the center roll aims at preventing the excess pitch deposition for the good run, and the interval between o. the removals of pitch deposited onto the center roll is shorten with the increased amount of pitch deposits.

The obtained results were compared with those of "control", and were indicated in Table 7.

5 21 -I I--r i it Table 7 Control Li OF Amount of Max 895 89 pitch Min 73 0 deposited Aver 207 43 (g/day) age Interval Max 120 240 between the Min 30 120 removals of Aver 80 170 pitch age deposited (minutes) i K S SO [I S.

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0* *S S .r 55.5 *i S [Example 8] A light-weight printing paper of 34g/m 2 basis weight was produced in accordance with Example 7, wherein the paper-stock consists of 20% GP, 50% waste newspaper pulp (deinked), 15% softwood KP and thermomechanical pulp. Lipase OF was added to GP slurry in an amount of 3ppm. The practical output of the paper machine was about 200 tons per day. For the comparison with the results of "Control", there were determined the amount of pitch deposited in the wire and press parts, and the pitch holes of the paper due to pitch deposition at the breaker stack. The results were indicated in Table 8.

22 kPA- Table 8 Control Li OF Amount of Max 590 1 98 pitch Min 132 deposited Aver 221 47 (g/day) age Number of Max 65 14 pitch holes* Min 13 0 (per day) Aver 38 6 age Expressed by number of small paper slips peeled of f In the breaker stack.

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Claims

1. A method for avoiding pitch troubles in a process for the production of mechanical pulp and/or of mechanical pulp-containing paper, which comprises treating the paper-stock and/or reused water by the addition of an acylglycerol lipase.

2. A method according to Claim 1, wherein said acylglycerol lipase is that produced from at least one microorganism selected from the group consisting of Aspergillus niger, Pseudomonas fluorescens, Pseudomonas fragi, Geotrichum candidum and Candida cylindracea.

3. A method according to Claim 1 or Claim 2, wherein said acylglycerol lipase added to paper-stock slurry in an amount of 0.1-1000ppm, based on the weight of mechanical pulp.

4. A method according to any one of Claims 1 to 3, wherein the temperature of said paper-stock and/or reused water ranges from 10 0 C to 70 0 C.

5. A method according to any one of Claims 1 to 4, wherein the temperature of said paper-stock and/or reused water ranges from 35 0 C to 55 0 C.

6. A method according to any one of Claims 1 to wherein the pH-value of said paper-stock and/or reused water ranges from 3 to 11.

7. A method for avoiding pitch troubles substantially as hereinbefore described with reference to the Examples. SRq 42 0VT 0 25

8. Paper when produced by the process according to any one of Claims 1 to 7. DATED this 5th day of February, 1991. JUJO PAPER CO., LTD. By Its Patent Attorneys DAVIES COLLISON CAVE