FI64965C - FOERFARANDE FOER BEHANDLING AV PAPPERSMASSA - Google Patents

Description

I. J1 r_, ANNOUNCEMENT.

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National Board of Patents and Registration of Finland Nihtivftksipanon I · moonUulkatou date. - οι 10 flo

Patents and registers in the field of public service (*) (32) (33) (31) umolkuu »BugSrd prtarftut (T1) Central Institute of Public Administration Bumagi, ulitsa Lenina 15/1, Poselok Pravdinsky Moskovskoi obl Gosudarstvenny Institut Prikladnoi Khimii, Prospekt Dobroljubova lU, Leningrad, USSR (SU) (72) Anatoly Vasilievich Kuchmenko, Poselok Pravdinsky Moskovskoi oblast,

Alla Timofeevna Kapanchan, Poselok Pravdinsky Moskovskoi oblast,

Ekaterina Fedorovna Shtreis, Poselok Pravdinsky Moskovskoi oblast,

David Solomonovich Zhuk, Moscow, Petr Alexandrovich Gembitsky, Moscow, Anatoly Ivanovich Chmarin, Moscow, Oleg Alexeevich Krylov, Leningrad, Grigory Iosifovich Bass, Leningrad, Valery Mikhailovich Trishin,

Leningrad, USSR (SU) (7 * 0 Oy Kolster Ab (50 Method for treating pulp - Förfarande för behandling av pappersmas)

This pulp contains an intermediate used in the manufacture of various types of bonded and non-adhesive papers, such as newsprint and typographic paper. The pulp is treated, in general, with various polyelectrolytes. This is associated with a number of efficiency problems in the papermaking process in an effort to reduce the amount of harmful resin and slime formed at various stages of the process; in addition, the pulp processing technology with polyelectrolytes makes it possible to improve the quality of the paper produced, for example by improving the degree of whiteness of the paper and its mechanical properties.

Methods are known in the art for treating pulp prior to casting. These methods include mixing various polyelectrolytes, including polyethylene irine and its irradiated products with urea, isocyanates, and acrylamide, into the pulp (cf. U.S. Patent No. 3,016,325 to Cl. 162-164, published 1963; No. 3,184,373 Cl. 162-152, issued 1964; No. 3,248,280 Cl. 162-164, published 1966; No. 3,642,572 Cl. 162-164, published 1972; FRG Patent No. 1,225,862; No. 1,930,213; French Patent No. 1,553,208, Cl. D 21h, 1969; USSR Inventor's Certificate No. 488832, Int. Cl. C 08 F 8/30).

The treatment of the pulp with polyethyleneimine is usually carried out with the pH of the pulp medium being neutral or premature; in this case, yellowing of the paper is noticeable.

Said modified polyethyleneimines are effective in an acidic medium and do not cause yellowing of the paper. However, they reduce the efficiency of pulp bleaching when using optical brighteners, i. they prevent the action of optical brighteners. As a result of the modification of the polyethyleneimine by means of urea and isocyanates, some of the amine groups are converted into amide groups, thus preventing a sufficient amount of water from leaving the pulp, with a decrease in the retention rate of the fillers.

In addition, the modification of polyethylene min with urea and isocyanates involves a complex and multi-step process.

A process for treating pulp with acrylamide-modified polyethyleneimine is known in the art (cf. USSR Inventor's Certificate No. 487194).

The organic synthesis of the product is relatively simple and does not require advanced process equipment. The efficiency of the obtained product can be observed in a wider pH range of the pulp medium than when using the above-mentioned modified polyethyleneimines.

In addition, the modified polyethyleneimine with a high content of ethyleneamino / 5-ethylamide units (50-70%) increases the optical bleaching efficiency of the pulp in the presence of bleaching agents.

However, this pulp treatment method does not allow to fully satisfy the requirements for process conditions in papermaking, such as (1) the degree of water removal from the pulp is insufficient in the wide pH range of this medium; (2) the degree of retention of the fillers is insufficient over a wide pH range of the pulp; 6 4 9 6 5 (3) improving the whiteness of the paper, i.e. is it impossible to avoid inhibiting the effectiveness of optical brighteners? (4) the products do not reduce biodegradation and mucus formation in the process equipment.

The object of the present invention is to overcome the above-mentioned drawbacks. The present invention relates to a process for treating pulp by mixing a polyelectrolyte, a polyelectrolyte which ensures a high degree of dehydration of the pulp, a high degree of retention of fillers in the wide pH range of the pulp medium, a high degree of whiteness of the paper formed and less mucus formation.

This object is realized by a pulp treatment method by mixing a polyelectrolyte containing a modified polyethyleneimine into the pulp, wherein, according to the present invention, a polyethyleneimine modified with acrylamide and acrylic acid is used as the modified polyethyleneimine? wherein in this process the content of ethyleneamine / 3-amide units in the modified polyethyleneimine is 10 to 50 mol% and the content of ethyleneamino / N-propionate units is 10 to 50 mol% of the total number of basic units of polyethyleneimine.

As the modified polyethyleneimine, it is preferable to use polyethyleneimine, which is also modified with guanidine, with a content of guanidine units of 10 to 50 mol% of the total number of basic polyethyleneimine units.

Polyethyleneimine modified with acrylamide, acrylic acid and guanidine is a multi-purpose paper material. Each of the specified modifiers gives the final product special properties. Thus, modification of polyethyleneimine with acrylamide improves the degree of dehydration of the pulp and increases the degree of retention of the fillers over a wider pH range of the pulp medium.

Modification of the polyethyleneimine with acrylic acid gives it the properties of a polyamolyte, thus allowing the pulp to be treated in substantially any pH range of its medium.

The mechanical properties of the paper are also improved and, most importantly, the mechanical properties of the obtained paper can be improved and, most importantly, the high strength of the obtained paper can be ensured. Modification of the polyethyleneimine with guanidine, in combination with acrylamide and acrylic acid, gives the final product good bactericidal and antifungal activity.

Therefore, only said combination of the above-mentioned modifiers, when used in the above-mentioned specified quantitative ratios, creates favorable conditions for the production of various paper products.

The pulp processing method of the present invention makes it possible to increase the efficiency of the papermaking process due to the acceleration of the dehydration of the pulp. The retention rate of mineral fillers and fine fiber is substantially increased, thus improving the clarification conditions of the circulating water. In addition, the quality of the formed paper is substantially improved due to its better degree of whiteness and higher mechanical properties. The use of polyethyleneimine modified with acrylamide, acrylic acid and guanidine for the treatment of pulp makes it possible to prevent the growth of the microorganism in the process equipment, thus promoting a higher yield of the product and an improvement in the quality of the paper produced.

The process for treating pulp with the modified polyethyleneimine according to the present invention is technically simple and feasible using the following preferred method.

To the pulp containing powdered fibrous intermediate, filler, and (in certain cases) optical brightener, adhesive, and coagulant, modified polyethyleneimine is added prior to casting in an amount of 0.03 to 0.1% by weight of the amount of absolute dry fibrous material. counting. The efficiency of the polyelectrolyte is manifested in approximately any pH range of the pulp.

Any cellulose, wood chips, waste paper can be used as the fibrous starting material.

Kaolin, chalk, Blanc fix, titanium dioxide are used as fillers.

Natural adhesives and synthetic polymers are used as adhesives.

The determination of the dewatering efficiency of the modified polyethyleneimine according to the present invention is carried out in a Shopper-Rigler.

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The paper web casting is performed in a Rapid-Ketten.

The polyethyleneimine modified with acrylamide and acrylic acid used as a starting material in the process of the present invention is prepared as follows.

A calculated amount of crystalline acrylamide is added to an aqueous solution of polyethyleneimine at a concentration of 10-15%. The coupling of the acrylamide takes place as an exothermic reaction and the temperature of the reaction mixture rises to 30-40 ° C. At the end of the exothermic period, the reaction solution is heated for another 2-3 hours at a temperature between 80-100 ° C to complete the modification.

The modified polyethyleneimine formed is not separated from the reaction mixture. To prevent structuring, it is neutralized with 50 mol% of inorganic acid, based on amino groups. A calculated amount of acrylic acid is then added to the resulting mixture, and the reaction mixture is maintained at 70-80 ° C for another 8-10 hours.

The preparation of polyethyleneimine modified with acrylamide, acrylic acid and guanidine is carried out by adding a calculated amount of guanidine hydrochloride to an aqueous solution of polyethyleneimine at a concentration of 10-15%. The solution is heated to boiling. The end point of the reaction is stated as the cessation of the evolution of ammonia formed by the reaction of polyethyleneimine with guanidine. Thereafter, the method is performed in the same manner as described above.

To clarify the comprehensibility of the present invention, a few specific examples are set forth below.

Example 1

Pulp containing a mixture of cellulose fiber ground to a Shopper-Rigler scale of 40 °, kaolin, resin glue, aluminum sulfate and an optical brightener used in a weight of 0.1% by weight. based on the amount of absolute dry cellulose fiber, an aqueous suspension having a pH of 6.0 is added with modified polyethyleneimine based on 0.07% by weight based on the amount of absolute dry cellulose fiber. The modified polyethyleneimine contains 50 mole% of ethyleneamino / β-amide units and 10 mole% of ethylamino / β-propionate units based on the total number of original units of polyethyleneimine. The ingredients are mixed together for 15 seconds. The dehydration time of this pulp is 45 seconds.

6 64965 The characteristics of a roll of paper made from this pulp are shown in the table below.

Check 1

The dehydration time of the above-mentioned pulp without optical brightener and polyelectrolyte is 97 seconds.

The properties of a roll of paper made from this pulp are shown in the table below.

Check 2

A paper roll is made from the pulp of Example 1 without polyelectrolyte. The properties of the paper roll are shown in the table below.

Check 3

To the pulp of Example 1 is added a polyelectrolyte-modified polyethyleneimine having 50 mol% of ethyleneamine-ethylamide units based on the total number of original units of polyethyleneimine, the amount added corresponding to 0.03% by weight of the absolute dry cellulose fiber. The dehydration time of this pulp is 56 seconds. The properties of a roll of paper made from this pulp are shown in the table below.

Example 2

An aqueous suspension of kaolin, resin glue, aluminum sulphate is added to a pulp containing a mixture of cellulose fiber ground to 40 ° on a Shopper-Rigler scale as a mixture, maintaining the pH at 4.5, in an amount of 0.07% by weight absolute. based on the amount of dry cellulose fiber. The modified polyethyleneimine has 25 mole% of ethyleneamino / 5-amide units and 25 mole% of ethylene amino / β-propionate units based on the total number of original units of polyethyleneimine. The resulting pulp is mixed for 15 seconds and then filtered on a Shopper-Rigler.

The dehydration time of this pulp is 47 seconds.

The properties of a roll of paper made from this pulp are shown in the table below.

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Example 3

To the pulp of Example 1 having a pH of 4.5 is added 0.07% of modified polyethyleneimine (based on the weight of absolute dry cellulose fiber) having 10 mole percent of ethyleneamino-amide units and 50 mole% of ethylene-amino-amide units. propionate yksiköi-s.

The dehydration time of this pulp is 48 seconds.

The properties of a roll of paper made from this pulp are shown in the table below.

Example 4

To the pulp of Example 1 having a pH of 4.5, modified polyethyleneimine (in an amount of 0.07% by weight based on the weight of the absolute dry fiber) containing 10 mol% of ethyleneamino / β-amide units, 40 molar % ethyleneamino / 5-propionate units and 10 mole% guanidine units.

The dehydration time of this pulp is 39 seconds.

The properties of a roll of paper made from this pulp are shown in the table below.

Example 5

Modified polyethyleneimine is added to a pulp having a pH of 7.5 and a mixture of cellulose fiber ground to a Shopper-Rigler scale value of 40 ° and an aqueous suspension of chalk in an amount of 0.1% by weight of the absolute dry cellulose fiber. counting. The modified polyethyleneimine has 10 mole% of ethyleneamine / 3-amide units, 40 mole% of ethylene amino / i-propionate units and 50 mole% of guanidine units. The resulting mass is mixed for 15 seconds and filtered on a Shopper-Rigler. The dehydration time of this pulp is 35 seconds.

The properties of a roll of paper made from this pulp are shown in the table below.

While polyethyleneimine modified with acrylamide, acrylic acid and guanidine is effective as a dehydration and retention aid, it at the same time slows down the growth of some mucus-forming microorganisms; the mortality of the latter from modified polyethyleneimine is as high as 70%.

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Table

Example No. Fill Whiteness- Degree of breakage retention, degree,%, m%

Example 1 72 97.3 3 780

Check 1,47 80.0 3,500

Check 2,479.0 3,500

Check 3 60 94.0 3 550

Example 2 73 90.0 3840

Example 3 75 98.0 4 100

Example 4 78 99.4 3 800

Example 5 79 93.0 4 470

The conclusion from the results presented in the above examples, as well as from the values shown in the table, is that the pulp treatment method of the present invention allows to increase, as before (control 3), a dehydration rate of 10-20%, a filler retention rate of 12-30% , improves the whiteness of the paper by 5%, as well as improves the mechanical strength properties of the obtained paper.