A hydrogen peroxide stabilizer

Abstract

The application belongs to the papermaking bleaching technical field, discloses a hydrogen peroxide stabilizer, which comprises the following components in parts by weight: 80-90 parts of poly-alpha-hydroxy acrylic acid; and 10-20 parts of polyvinyl alcohol. The stabilizer is combined with poly-alpha-hydroxy acrylic acid and polyvinyl alcohol, so as to relieve the gel phenomenon caused by the lactonization of poly-alpha-hydroxy acrylic acid in an overalkaline environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of papermaking bleaching technology, and particularly relates to a hydrogen peroxide stabilizer. BACKGROUND

[0002] Hydrogen peroxide (H2O2) is widely used in pulp bleaching due to its strong oxidizing properties and environmental friendliness. However, trace amounts of metal ions (such as iron, copper, and manganese) remaining in the pulp can catalyze the rapid decomposition of hydrogen peroxide, leading to loss of active ingredients, reduced bleaching efficiency, and even affecting the whiteness and strength of the finished paper.

[0003] Therefore, the role of hydrogen peroxide stabilizer in papermaking bleaching mainly lies in controlling the decomposition rate of hydrogen peroxide to prevent its premature decomposition, thereby ensuring the stability and effectiveness of the bleaching process. Among them, poly-alpha-hydroxy acrylic acid as a hydrogen peroxide stabilizer has particularly outstanding stabilizing effect and is a popular choice.

[0004] As prior art 1: JP4878710B2 discloses a hydrogen peroxide stabilizer for bleaching, refining and soaping of fibers, which has excellent alkali resistance and hydrogen peroxide stabilizing effect, can maintain the bleaching performance of hydrogen peroxide even in the presence of high concentration of alkali, and is a hydrogen peroxide stabilizer that can improve the whiteness of fibers. Solution: (a) obtained by free radical polymerization of at least one monomer selected from acrylic acid, methacrylic acid, maleic acid and salts thereof with poly-alpha-hydroxy acrylic acid and / or its salt. (b) water-soluble magnesium compound, wherein the weight ratio of polymer to magnesium is 1:1-45:1 hydrogen peroxide stabilizer.

[0005] Prior art 1 discloses the use of poly-alpha-hydroxy acrylic acid and at least one monomer of acrylic acid, methacrylic acid, maleic acid and salts thereof to polymerize freely and then compound with water-soluble magnesium compound, which can more effectively stabilize hydrogen peroxide in the presence of higher concentration of alkali.

[0006] However, in actual papermaking production, caustic soda will be added during the entire bleaching process, and production workers will directly pour a large amount of caustic soda in the process of adding caustic soda in order to save trouble, which will cause the local environment to be too alkaline in a short time, leading to gelation of poly-alpha-hydroxy acrylic acid and affecting its function of stabilizing hydrogen peroxide. Poly-alpha-hydroxy acrylic acid gels in a strong alkali environment, and its use may be limited in some hydrogen peroxide alkaline formulations.

[0007] Therefore, it is necessary to find a method to avoid the gelation of poly-alpha-hydroxy acrylic acid caused by the excessive alkalinity of the local environment in the actual production process, to avoid the reduction of bleaching efficiency, and to improve the alkali resistance of poly-alpha-hydroxy acrylic acid, increase its stability in the presence of alkali, and expand its application scenarios. SUMMARY

[0008] One of the purposes of the present application is to provide a hydrogen peroxide stabilizer, which uses poly-α-hydroxy acrylic acid and polyvinyl alcohol in combination to alleviate the gel phenomenon caused by lactonization of poly-α-hydroxy acrylic acid in an over-basic environment.

[0009] Meanwhile, the present application also provides a hydrogen peroxide stabilizer, which comprises the following components in parts by weight:

[0010] poly-α-hydroxy acrylic acid 80-90 parts;

[0011] polyvinyl alcohol 10-20 parts.

[0012] In the production process, sudden local increase of alkalinity in the water environment can cause lactonization of poly-α-hydroxy acrylic acid, and its hydroxyl and carboxyl groups can be esterified to form a gel. The present application uses water-soluble polyvinyl alcohol to esterify part of the carboxyl groups of poly-α-hydroxy acrylic acid, thereby reducing the esterification within and between the molecules of poly-α-hydroxy acrylic acid and effectively alleviating the gel phenomenon in the case of sudden increase of alkalinity. Tests show that in the same alkaline environment, the use of polyvinyl alcohol can greatly reduce or even eliminate the gel phenomenon. The fundamental reason is that the esterification between and within the molecules of poly-α-hydroxy acrylic acid is relatively dense, and the adjacent carboxyl and hydroxyl groups of the same segment or other segments can be esterified, and the esterification density is relatively high. When the alkalinity of the system is diluted, the hydrolysis time is relatively long, and the gel phenomenon disappears in a long time. After the use of polyvinyl alcohol, esterification still occurs, but the esterification between poly-α-hydroxy acrylic acid and polyvinyl alcohol is intermittent. The esterification sites are few, and the polyvinyl alcohol connected to poly-α-hydroxy acrylic acid also increases the steric hindrance of poly-α-hydroxy acrylic acid, making it difficult to form a sufficient crosslinking network and thus difficult to exhibit a gel phenomenon. In addition, due to the intermittent esterification, the esterification density is low, and once the alkali in the water is diluted, the esterification sites will rapidly hydrolyze, restoring the hydrogen peroxide stabilizing effect of poly-α-hydroxy acrylic acid.

[0013] In addition, polyvinyl alcohol is also a relatively good metal ion chelating agent, which can also stabilize hydrogen peroxide by chelating metal ions, like poly-α-hydroxy acrylic acid.

[0014] Therefore, even if part of the polyvinyl alcohol is added, the overall hydrogen peroxide stabilizing effect is not inferior to that of the same weight of poly-α-hydroxy acrylic acid.

[0015] In the above hydrogen peroxide stabilizer, the viscosity of a 4wt% polyvinyl alcohol aqueous solution at 20°C is 3.0-300 mPa.s.

[0016] In the above hydrogen peroxide stabilizer, the 4wt% aqueous solution of the polyvinyl alcohol has a viscosity of 10-150 mPa.s at 20℃.

[0017] In the above hydrogen peroxide stabilizer, the polyvinyl alcohol is composed of a first polyvinyl alcohol and a second polyvinyl alcohol; the 4wt% aqueous solution of the first polyvinyl alcohol has a viscosity of 10-50 mPa.s at 20℃; the 4wt% aqueous solution of the second polyvinyl alcohol has a viscosity of 110-150 mPa.s at 20℃; and the weight ratio of the first polyvinyl alcohol to the second polyvinyl alcohol is 1-10:1-10.

[0018] As the polyvinyl alcohol commonly used in the art, the fully hydrolyzed polyvinyl alcohol of Shin-Etsu can be selected, and the specific trade name is: JF-03, JF-04, JF-05, JF-10, JF-17, JF-17L, JF-20, JC-25, JC-33, JC-40, etc.

[0019] In the above hydrogen peroxide stabilizer, the weight ratio of the first polyvinyl alcohol to the second polyvinyl alcohol is 1-3:7-9.

[0020] In the above hydrogen peroxide stabilizer, the poly-α-hydroxy acrylic acid has a molecular weight of 20,000-400,000 and a molecular weight distribution of 1-10.

[0021] Advantages

[0022] Compared with the prior art, the poly-α-hydroxy acrylic acid and the polyvinyl alcohol are combined in the present application, and the esterification between the poly-α-hydroxy acrylic acid and the polyvinyl alcohol partially replaces the intermolecular and intramolecular esterification of the poly-α-hydroxy acrylic acid in the strong alkaline environment, so as to relieve the gel phenomenon caused by the intramolecular esterification of the poly-α-hydroxy acrylic acid in the strong alkaline environment.

[0023] Meanwhile, the stabilizing effect of the stabilizer of the present application is not inferior to that of the same weight of poly-α-hydroxy acrylic acid. DETAILED DESCRIPTION

[0024] The present application will be further described below in conjunction with examples, but does not constitute any limitation to the present application, and any limited modification made within the scope of the claims of the present application is still within the scope of the claims of the present application.

[0025] In order to describe the technical content of the present application in detail, the following further describes in conjunction with the embodiments.

[0026] Preparation of the first part of poly-α-hydroxy acrylic acid

[0027] Example 1

[0028] A method for preparing poly-α-hydroxyacrylic acid, comprising the following steps:

[0029] Step 1: 700g of water, 100g of α-chloroacrylic acid, and 0.4g of sodium persulfate were added to a reaction container in an inert atmosphere, and reacted at a constant temperature of 80°C for 3h under stirring;

[0030] Step 2: After the reaction was stopped, the polymer solids were collected by filtration;

[0031] Step 3: The polymer solids were added to an aqueous solution of sodium hydroxide at a concentration of 1.5mol / L, and hydrolyzed at a temperature of 80°C to obtain poly-α-hydroxyacrylic acid, which was named as poly-α-hydroxyacrylic acid 1.

[0032] Example 2

[0033] A method for preparing poly-α-hydroxyacrylic acid, comprising the following steps:

[0034] Step 1: 700g of water, 100g of α-chloroacrylic acid, and 0.8g of sodium persulfate were added to a reaction container in an inert atmosphere, and reacted at a constant temperature of 75°C for 4h under stirring;

[0035] Step 2: After the reaction was stopped, the polymer solids were collected by filtration;

[0036] Step 3: The polymer solids were added to an aqueous solution of sodium hydroxide at a concentration of 2mol / L, and hydrolyzed at a temperature of 80°C to obtain poly-α-hydroxyacrylic acid, which was named as poly-α-hydroxyacrylic acid 2.

[0037] Example 3

[0038] A method for preparing poly-α-hydroxyacrylic acid, comprising the following steps:

[0039] Step 1: 700g of water, 100g of α-chloroacrylic acid, and 2g of sodium persulfate were added to a reaction container in an inert atmosphere, and reacted at a constant temperature of 85°C for 1h under stirring;

[0040] Step 2: After the reaction was stopped, the polymer solids were collected by filtration;

[0041] Step 3: The polymer solids were added to an aqueous solution of sodium hydroxide at a concentration of 2.5mol / L, and hydrolyzed at a temperature of 80°C to obtain poly-α-hydroxyacrylic acid, which was named as poly-α-hydroxyacrylic acid 3.

[0042] The molecular weight and molecular weight distribution of the above-mentioned poly-α-hydroxyacrylic acid 1 to poly-α-hydroxyacrylic acid 3 can be seen in Table 1 below; the molecular weight was tested by dynamic light scattering method.

[0043] Table 1 Molecular weight table of poly-α-hydroxyacrylic acid

[0044]

[0045] Second part of hydrogen peroxide stabilizer

[0046] The composition of the hydrogen peroxide stabilizer can refer to Table 2 below;

[0047] Table 2 Composition of hydrogen peroxide stabilizer

[0048]

[0049] The 4wt% aqueous solution of JF-03 has a viscosity of 3.0-4.0 mPa.s at 20℃;

[0050] The 4wt% aqueous solution of JF-17 has a viscosity of 28.0-32.0 mPa.s at 20℃;

[0051] The 4wt% aqueous solution of JC-33 has a viscosity of 110.0-150.0 mPa.s at 20℃.

[0052] Third part of performance test

[0053] 3.1 Alkali resistance test

[0054] Test method:

[0055] (1) Prepare a 15% concentration of sodium hydroxide solution;

[0056] (2) Take 30g of the stabilizer to be tested in a 500ml beaker, and slowly add 270g of the above sodium hydroxide solution;

[0057] (3) Observe the gel agglomeration phenomenon in the solution, record the amount of sodium hydroxide solution added when the gel agglomeration appears, and after the sodium hydroxide solution is added, observe and record the time when the gel agglomeration disappears, the test results are as follows:

[0058] Table 3 Alkali resistance test of hydrogen peroxide stabilizer

[0059]

[0060] The above experimental results show that:

[0061] 1. The larger the molecular weight of poly-α-hydroxy acrylic acid, the worse the alkali resistance, and a small amount of sodium hydroxide can cause it to appear gel agglomeration, and the time required for the gel agglomeration to disappear is longer, which may be due to the longer molecular chain of poly-α-hydroxy acrylic acid, containing more carboxyl and hydroxyl groups that can be lactonized, more easily gel agglomeration, and the space structure of the formed gel agglomeration is more complex, which needs more time to extend into a chain structure in the solution.

[0062] 2. Poly-α-hydroxy acrylic acid, first polyvinyl alcohol JF-03, JF-33 or second polyvinyl alcohol JF-17 is added alone, the alkali resistance is improved to a certain extent, and it can be seen that the alkali resistance improvement effect of poly-α-hydroxy acrylic acid is JF-33 > JF-17 > JF-03, which may be due to the fact that the polyvinyl alcohol with longer molecular chain is combined more closely with the carboxyl esterization of poly-α-hydroxy acrylic acid, and the alkali resistance improvement effect is more significant.

[0063] 3. JF-33 and JF-07 have a synergistic effect on the alkali resistance improvement of poly-α-hydroxy acrylic acid, and when the two are used in appropriate amounts, poly-α-hydroxy acrylic acid does not appear to be condensed and bunched when mixed with alkali, which is a surprising effect, which may be due to the fact that poly-α-hydroxy acrylic acid contains different molecular chain length units, JF-33 is carboxyl esterized with poly-α-hydroxy acrylic acid with longer molecular chain, and JF-07 is carboxyl esterized with poly-α-hydroxy acrylic acid with relatively short molecular chain, which synergistically improves the alkali resistance of poly-α-hydroxy acrylic acid.

[0064] 3.2 Chelating performance test

[0065] According to the determination of the chelating ability of textile printing and dyeing auxiliaries chelating agent GB / T 21884-2008, the chelating performance of hydrogen peroxide stabilizer is as shown in the following table 4;

[0066] Table 4 Chelating performance test of hydrogen peroxide stabilizer

[0067]

[0068] From the above data, it can be seen that part of the polyvinyl alcohol is replaced by poly-α-hydroxy acrylic acid for compounding, and under the condition of the same total weight, the chelating performance is basically equivalent to that of poly-α-hydroxy acrylic acid, which may be due to the fact that polyvinyl alcohol has a certain chelating effect, and when a small amount of poly-α-hydroxy acrylic acid is replaced, the overall chelating performance is not greatly affected.

[0069] 3.3 Bleaching performance test

[0070] Take the pulp material from the high consistency bleaching of a certain chemical pulp mill, and the pulp parameters of the high consistency bleaching running condition are as shown in the following table 5;

[0071] Table 5 Pulp parameters of high consistency bleaching running condition of a certain chemical pulp mill

[0072]

[0073] The bleaching performance of the stabilizer for stabilizing hydrogen peroxide is tested according to the following experimental steps:

[0074] (1) A certain amount of pulp is weighed in a polyethylene self-sealing bag, a certain amount of dilution water is added, the required reagent for bleaching is added according to the amount of reagent required for bleaching, kneaded for 5 minutes, and then placed in a water bath at 90°C for 60 minutes.

[0075] (2) After the required bleaching time, 11g of pulp is weighed, two bags are taken, 300g of pure water is added, and stirring is performed to disperse.

[0076] (3) After stirring for 5 minutes, filtration is performed.

[0077] (4) After filtration, the tablets are pressed for 3 minutes, then naturally cooled and dried under constant temperature and humidity conditions, and then the whiteness is detected.

[0078] (5) After each bag of pulp is weighed, the filtrate is squeezed out, and the hydrogen peroxide residue is measured.

[0079] The test results are shown in Table 6 below.

[0080] Table 6 Stabilizer test hydrogen peroxide bleaching performance

[0081]

[0082] The above data shows that when poly-α-hydroxy acrylic acid is added separately from the alkali, good hydrogen peroxide stabilizing and bleaching effects are achieved. When poly-α-hydroxy acrylic acid is added mixed with alkali, the bleaching performance and hydrogen peroxide stabilizing effect are significantly reduced, which may be due to the influence of gelation of poly-α-hydroxy acrylic acid when it is mixed with alkali. When poly-α-hydroxy acrylic acid is compounded with polyvinyl alcohol, even if it is added mixed with alkali, the bleaching performance and hydrogen peroxide stabilizing effect of the stabilizer do not decrease, indicating that the method provided in the present application effectively solves the problem of gelation of poly-α-hydroxy acrylic acid when it is mixed with alkali, which is of great significance for the actual production and use of poly-α-hydroxy acrylic acid.

[0083] The examples presented herein are only selected from combinations of all possible examples. The appended claims should not be limited by the description of the embodiments of the present application. Some numerical ranges used in the claims include sub-ranges within them, and variations in these ranges should also be covered by the appended claims.

Claims

1. A hydrogen peroxide stabilizer, characterized in that, The product comprises the following components by weight: 80-90 parts of poly-α-hydroxyacrylic acid; 10-20 parts of polyvinyl alcohol, wherein the polyvinyl alcohol is composed of a first polyvinyl alcohol and a second polyvinyl alcohol; the viscosity of a 4 wt% aqueous solution of the second polyvinyl alcohol at 20°C is 28-32 mPa·s; the viscosity of a 4 wt% aqueous solution of the first polyvinyl alcohol at 20°C is 110-150 mPa·s; and the weight ratio of the first polyvinyl alcohol to the second polyvinyl alcohol is 1-10:1-10.

2. The hydrogen peroxide stabilizer according to claim 1, characterized in that, The molecular weight of the poly-α-hydroxyacrylic acid is 20,000 to 400,000.

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