SU1010171A1 - Method of producing filler for paper pulp - Google Patents

Abstract

METHOD FOR PREPARING A FILLER FOR PAPER MASS, including the interaction of urea with formaldehyde with a detergent in an aqueous medium in the presence of sulfuric acid at elevated temperature, neutralizing the resulting suspension and filtering the precipitate, characterized in that, to increase the yield of filler and whiteness of paper at the same time reducing its cost and environmental pollution, as a formaldehyde-containing reagent, use the bottom residue from the distillation of methanol from the tar water; Urea-formaldehyde resin with a formaldehyde content of 4-10%, and the interaction is carried out at an equimolar ratio of urea and formaldehyde (L yes, contained in the vat residue.

Description

This invention relates to methods for producing synthetic paper pulp fillers for making high quality types of paper of high whiteness and opacity. Methods for obtaining synthetic mineral paper paper fillers (barium sulphate, titanium dioxide) are known by precipitating them from reaction solutions ij. However, the mineral fillers produced according to limestone methods have a high density (2.64, 2 g / cm |), which makes it difficult to produce paper of small mass of 1 m. In addition, the abrasive nature of these fillers has a certain effect on the durability of clothing of papermaking machines and printing machines. The disadvantages of these methods also include the high cost of the products obtained. There is a known method for preparing a filler by polymerizing urea precursor condensate and formaldehyde in the presence of an acid catalyst with This method allows to improve the optical properties of the filler, its retention in the paper, and with the introduction of such a filler in the pulp - to reduce its versatility, increase its whiteness and opacity 2. -I. However, since the coating is applied to the mineral substrate, the filler obtained also has a relatively high density. The disparity of the filler obtained by this method depends on the particle size of the kaolin used. As a result, the dispersion has certain limitations and cannot be adjusted by grinding. Closest to the proposed one, g is a method of obtaining a synthetic organic filler by combining urea with urea and a formic acid-containing reagent in the presence of sulfuric acid at elevated temperature, neutralizing the resulting suspension, filtering the precipitate. Commodity formaldehyde is used as formaldehyde containing reagent. In this case, the molar ratio of urea and formaldehyde is from 1: 1.3 to 1: 1.8. The resulting precipitate can be dried and milled. The filler obtained by a known method has a high whiteness, a density of about 1.45 g / cm 3, is practically non-abrasive and allows to obtain light-weight types of paper with a high level of optical properties. However, the use of formaldehyde in this method leads to the high cost of the product obtained. At the same time, the specified molar ratio of urea and formaldehyde does not allow complete binding of formaldehyde, which on the one hand leads to a decrease in the yield of the filler, and the other to the contamination of waste water with unreacted formaldehyde. The purpose of the invention is to increase the yield of filler and the whiteness of the paper while reducing its cost and pollution of the environment. The goal is achieved by the fact that according to the method of producing a filler for paper pulp, including the interaction of urea with a formaldehyde-containing reagent in an aqueous medium in the presence of sulfuric acid at elevated temperature, neutralizing the resulting suspension and filtering the precipitate, as a formaldehyde-containing reagent, distillation residue is used methanol from the resin water of urea formaldehyde resin production with β-formaldehyde content of 4-10%, and the interaction is carried out at Vimol polar relation | Shenii urea and formaldehyde contained in the bottoms. The use of the proposed method as a formaldehyde-containing reagent from the bottom of the distillate from distillation of methanol from over-resin water formed during the production of urea resin makes it possible to utilize the waste of the said production, eliminate the need to use commodity formaldehyde and significantly reduce the cost of the filler. The found molar ratio of urea and formaldehyde leads to the almost complete removal of formaldehyde from the reaction solution, which increases the yield of the product, reduces the wastewater pollution by formaldehyde during the filler process and contributes to increasing the whiteness of the paper. The proposed method is carried out as follows. In the reactor, equipped with a stirrer and a jacket for heating and cooling, pour the residue from the distillation of methanol from the resin water of the urea-formaldehyde resin, containing 4-10% formaldehyde and up to 1% methanol. Next, the urine is loaded into the reactor; well, the molar ratio of urea and formaldehyde should be 1: 1. The mixture is heated to 0100 ° C, preferably 70-80 ° C, and the acid catalyst sulfuric acid is introduced to a pH in the reaction mixture equal to 1.0-1.5. The mixture is maintained at the indicated parameters for 1.5-2 hours. Then the mixture is cooled to 20 ° C ° C. And kept for 1.5-2 hours to complete the reaction. The resulting suspension is neutralized with a caustic agent (sodium hydroxide or sodium carbonate) to pH 6 -eight. The white solid, insoluble product is separated by filtration and washed. The resulting package can be used as an overweight in both wet and dried condition. To achieve the desired degree of dispersion, the product may be ground. Example. 90 g of urea is added with stirring to the bottom residue from the distillation of methanol from supramolar water containing 4% formaldehyde and the reaction mixture is heated to 10 ° C. Sulfuric acid is then added until the pH is set to 1.5 and the reaction mixture is kept under these conditions for 2 hours. thereafter, the mixture is cooled to and maintained at this temperature to complete the reaction for 1 hour. At the end of the reaction, caustic soda is metered as a 30% solution to pH 6. The precipitate formed is filtered, washed until neutral, then dried and ground. . 1 Example2. To the bottom distillation residue from the distillation of methanol from above resin water of the production of a urea-formaldehyde resin with a formaldehyde content of 10%, 200 g of urea are added with stirring and the reaction mixture is heated to 90 ° C. After the required temperature has been reached, sulfuric acid is added to a pH of 1.0 and the mixture is kept at this temperature for 2 hours. The mixture is then cooled to and the reaction mixture is maintained at this temperature for 2 hours. Then, to neutralize the sulfuric acid into suspension. formed white insoluble product injected calcium carbonate solution to pH 8.0. The precipitate of the filling of the bodies is filtered off, washed and, at a humidity of 65-70%, is used as the filler of the pulp. In tab. 1 shows the results of determining the yield of the product and the characteristics of the wastewater that forms during the preparation of the filler at different ratios of urea and formaldehyde according to the proposed procedure and the prototype. These data show that the proposed method of obtaining a filler allows to increase its yield by 10-25%, significantly reducing the pollution of wastewater formed during the production process with unreacted wastewater and other organic substances. At the same time, in the process of obtaining the filler according to the proposed method, utilization of wastes from the production of urea resins takes place. The filler obtained in accordance with the proposed v-benefit has a low density (1.45-1.6 g / cm), high whiteness (88-96% for a Zeiss flow meter) and oil absorption (90120 g / 100 pigment). Depending on the degree of grinding, the average particle size of the filler is 2-20 µm, the specific surface is 2540 g / m. The introduction of the filler into paper and its manufacture is dried according to the generally accepted technology. EXAMPLE 3: The filler (Example 1) obtained by the inventive method was introduced in an amount of 10% into a paper pulp consisting of ground bleached sulfite cellulose, 1% rosin glue, 2% aluminum sulphate and common laboratory methods were added. conditions make paper. Next, assess the degree of whiteness and opacity of the resulting paper. The results of the determination are given in table. 2. Due to the difference of the original fiber semi-finished products with the prototype used by Vio and the instrumental difference in determining the degree of whiteness and opacity, the optical efficiency of the fillers obtained by the known and proposed method is estimated by increasing the magnitude of the increase in the whiteness and opacity of the raw paper. Indicators of optical properties of prototypes.v paper are given in Table. 2. As can be seen from the data given in table. 2, the introduction of the filler obtained by the proposed method into the paper pulp increases the whiteness of the paper by 4.3%, while the prototype increases by 2.6%. The proposed method allows to increase the yield of the product while decreasing its cost by 8-10 times. In addition, the method of producing napol yarns provides for the disposal of wastes from the production of urea resins and at the same time leads to a reduction. sewage pollution by unreacted forms of Shdegid.

Table 1

The output of the filler in relation to the initial formaldehyde content,%

Content in waste water, g / l

According to the proposed method

No filler

With the introduction of filler

Prototype

Without filler 92.7

With the introduction of filler 95, 3

150

180

Table

88,8

7.5 96.3

4.3

79.2

7.2 86.4

2.6

Claims (1)

METHOD FOR PREPARING FILLER FOR PAPER POWDER, comprising reacting urea with a formaldehyde-containing reagent in an aqueous medium at elevated temperature - neutralizing the resulting suspension and filtering the precipitate, characterized in that, in order to increase the yield of filler and whiteness of the paper while reducing cost. it and environmental pollution, as the formaldehyde-containing reagent, the bottom residue from the distillation of methanol from above *. · is used: resin water production urea-formaldehyde resin with a formaldehyde content of 4-10%, and the interaction is carried out at equimolar § the ratio of urea and formaldehyde contained in the bottom residue.