Environment-friendly chlorine-free wet strength agent and preparation method thereof

Abstract

A preparation method of the environment-friendly chlorine-free wet strength agent comprises the following steps: uniformly mixing 10-25 parts by weight of adipic acid, 5-10 parts by weight of urea and a proper amount of water, adding 6-18 parts by weight of glycidyl methacrylate and a proper amount of a cosolvent, reacting at 115-135 DEG C for 1-3 hours, adding a proper amount of acetic acid, and continuously keeping the temperature for 3-6 hours to obtain an intermediate; diluting the intermediate to a certain solid content, adding 2-8 parts by weight of epoxy chloropropane, heating to 30-40 DEG C, and keeping the temperature; adding 0.5-3.0 parts by weight of organic amine and a proper amount of water, continuously carrying out heat preservation reaction, and adding acid to adjust the pH value of the system to 2-4 when the viscosity of the system is increased to 30-50mPa. S; and adding deionized water to adjust the solid content to obtain the environment-friendly chlorine-free wet strength agent. The prepared wet strength agent is free of chlorine, environmentally friendly and low in cost, industrial production can be achieved, retention and drainage aiding performance is remarkably improved, and the dry and wet strength of paper can be greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of papermaking wet strength agent preparation, in particular to an environmentally friendly chlorine-free wet strength agent and a preparation method thereof. Background Art

[0002] Common wet strength agents include polyethyleneimine (PEI), urea-formaldehyde resin (UF), polyamide polyamine epichlorohydrin resin (PAE), etc., all of which have good wet strength effects. At present, the most widely used wet strength agent is polyamide polyamine epichlorohydrin resin, which is a water-soluble, cationic, thermosetting resin that does not contain formaldehyde polymers. It can be papered under neutral, slightly alkaline and acidic conditions, and has a wide range of pH values. PAE wet strength agent has a higher reinforcing effect on wood pulp than on grass waste paper. With the increase of beating degree, the surface area of ​​pulp fiber increases, the adsorption capacity of wet strength agent is greater, and the dry and wet strength of paper is correspondingly improved. It has a strong adsorption effect on negatively charged fillers, sizing agents and fine fibers, and has obvious retention and filtration effects in the papermaking process. The amount of addition depends on the wet strength requirements of the paper. Excessive addition will cause pulp flocculation, affecting the papermaking uniformity and the recycling of broken paper. It also improves the folding resistance, surface strength and transverse expansion rate of paper, and has a good effect on reducing wet paper breakage during paper machine operation.

[0003] During the preparation process of polyamide polyamine epichlorohydrin resin, the exogenous chlorinated organic matter produced is mobile, which will increase the content of organic chlorine in the finished paper and papermaking wet system, endangering people's health in the end product and use. At present, regulations have been made on the restricted addition of chemicals PAE to household paper, requiring that the sum of the contents of organic chlorinated oligomer epichlorohydrin (ECH), 1,3-dichloro-2-propanol (DCP) and 3-chloro-1,2-propylene glycol (MCPD) in PAE moisturizing and strengthening agents shall not exceed 0.7% of the total amount of PAE, which also affects the application value of PAE resin. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a chlorine-free, environmentally friendly, low-cost, high-humidification strength, high-retention and drainage-aid type wet strength agent and a preparation method thereof, thereby overcoming the above-mentioned defects of the prior art.

[0005] The present invention is achieved by adopting the following technical solutions:

[0006] A method for preparing an environmentally friendly chlorine-free wet strength agent comprises the following steps:

[0007] S1, 10-25 parts by weight of adipic acid, 5-10 parts by weight of urea, and an appropriate amount of water are mixed evenly, 6-18 parts by weight of glycidyl methacrylate and an appropriate amount of cosolvent are added, reacted at 115-135° C. for 1-3 hours, an appropriate amount of acetic acid is added, and the mixture is kept warm for 3-6 hours to obtain an intermediate;

[0008] S2, dilute the intermediate to a certain solid content, add 2-8 parts by weight of epichlorohydrin, and heat to 30-40°C for insulation;

[0009] S3, adding 0.5-3.0 parts by weight of an organic amine and an appropriate amount of water, continuing the heat-keeping reaction, and when the viscosity of the system rises to 30-50 mPa·s, adding an acid to adjust the pH of the system to 2-4;

[0010] S4. Add deionized water to adjust the solid content to obtain an environmentally friendly chlorine-free wet strength agent.

[0011] The inventor unexpectedly discovered that the use of adipic acid, urea, and glycidyl methacrylate to prepare an intermediate, and then sequentially adding epichlorohydrin and an organic amine to form a modified PAE wet strength agent, unexpectedly can greatly improve the retention and drainage performance, and greatly improve the wet and dry strength of paper. The principle is not very clear, but it is speculated that it may be because the wet strength agent prepared by the present invention has a highly branched structure, which makes it easy to adsorb on the fiber surface. The retention performance is well improved when used alone. The cross-linked network formed between and within molecules improves the bonding strength between paper fibers, which can greatly improve the wet and dry strength of paper. The inventor further found that replacing urea with conventional diethylenetriamine or replacing glycidyl methacrylate with epoxy resin does not significantly improve the wet and dry strength of paper. It is speculated that the joint participation of urea and glycidyl methacrylate in the reaction produces an unexpected synergistic effect. Based on the above findings, the present invention is completed.

[0012] The organic amine is selected from at least one of dimethylamine, trimethylamine, triethylamine, diethanolamine, triethanolamine and diethylenetriamine. Preferably, the amount of the organic amine is 0.5-3.0 parts by weight.

[0013] Furthermore, the preferred dosage of each component is as follows: 15-25 parts by weight of adipic acid, 6-10 parts by weight of urea, 12-18 parts by weight of glycidyl methacrylate, 5-8 parts by weight of epichlorohydrin, and 2-3.0 parts by weight of organic amine.

[0014] More preferably, the amounts of the components are as follows: 20-25 parts by weight of adipic acid, 8-10 parts by weight of urea, 15-18 parts by weight of glycidyl methacrylate, 7-8 parts by weight of epichlorohydrin, and 2.5-3.0 parts by weight of organic amine.

[0015] The co-solvent is selected from at least one of ethylene glycol butyl ether, ethylene glycol tert-butyl ether and propylene glycol methyl ether. Preferably, the amount of the co-solvent is 2-10 parts by weight.

[0016] Preferably, in step S1, the amount of acetic acid used is 0.5-2.0 parts by weight.

[0017] Preferably, in step S2, the insulation time is 1-2h.

[0018] In step S3, the acid may be an acid commonly used in the art, such as hydrochloric acid, sulfuric acid, acetic acid, or acetic acid.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The wet strength agent prepared by the present invention is chlorine-free, environmentally friendly, low-cost, and can be industrially produced;

[0021] 2. The wet strength agent prepared by the present invention greatly improves the dry and wet strength of paper;

[0022] 3. The wet strength agent prepared by the present invention can greatly improve the retention and filtration effects of paper. DETAILED DESCRIPTION

[0023] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only used as examples, but are not used to limit the scope of the present invention. Those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalent solutions, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0024] The instruments or raw materials in the present invention without indicating the manufacturer are all conventional commercial instruments or raw materials.

[0025] Unless otherwise mentioned, the detection indicators involved in the embodiments of the present invention are detected by conventional detection methods in the art.

[0026] Example 1

[0027] Step (1): 10 parts by weight of adipic acid, 25 parts by weight of water and 5 parts by weight of urea are uniformly mixed, 10 parts by weight of glycidyl methacrylate and 4 parts by weight of ethylene glycol tert-butyl ether are added, the mixture is reacted at 120° C. for 1 hour, 1 part by weight of acetic acid is added, and the mixture is kept warm for 3 hours to obtain an intermediate;

[0028] Step (2): dilute the intermediate to a solid content of 35%, add 4 parts by weight of epichlorohydrin, raise the temperature to 35° C., and keep the temperature for 1 hour;

[0029] Step (3): adding 3 parts by weight of deionized water and 1 part by weight of triethylamine, continuing the reaction at a heat preservation temperature, and when the viscosity of the system rises to 45 mPa·s, adding acetic acid to adjust the pH of the system to 3.0;

[0030] Step (4): adding deionized water to adjust the solid content to about 12.5% ​​to obtain an environmentally friendly chlorine-free wet strength agent.

[0031] Example 2

[0032] Step (1): 15 parts by weight of adipic acid, 35 parts by weight of water, and 6.5 parts by weight of urea are uniformly mixed, 12 parts by weight of glycidyl methacrylate and 6 parts by weight of ethylene glycol butyl ether are added, the mixture is reacted at 125° C. for 1 hour, 1 part by weight of acetic acid is added, and the mixture is kept warm for 4 hours to obtain an intermediate;

[0033] Step (2): dilute the intermediate to a solid content of 40%, add 6 parts by weight of epichlorohydrin, raise the temperature to 35° C., and keep the temperature for 1.5 h;

[0034] Step (3): adding 4 parts by weight of deionized water and 2 parts by weight of triethanolamine, continuing the reaction at a heat preservation temperature, and when the viscosity of the system rises to 45 mPa·s, adding acetic acid to adjust the pH of the system to 3.0;

[0035] Step (4): adding deionized water to adjust the solid content to about 12.5% ​​to obtain an environmentally friendly chlorine-free wet strength agent.

[0036] Example 3

[0037] Step (1): 20 parts by weight of adipic acid, 40 parts by weight of water and 8.5 parts by weight of urea are uniformly mixed, 15 parts by weight of glycidyl methacrylate and 8 parts by weight of propylene glycol methyl ether are added, the mixture is reacted at 130° C. for 1 hour, 1.5 parts by weight of acetic acid is added, and the mixture is kept warm for 5.5 hours to obtain an intermediate;

[0038] Step (2): dilute the intermediate to a solid content of 40%, add 7 parts by weight of epichlorohydrin, raise the temperature to 40° C., and keep the temperature for 2 hours;

[0039] Step (3): adding 4 parts by weight of deionized water and 2.5 parts by weight of dimethylamine, continuing the reaction at a heat preservation temperature, and when the viscosity of the system rises to 45 mPa·s, adding acetic acid to adjust the pH of the system to 3.0;

[0040] Step (4): adding deionized water to adjust the solid content to about 12.5% ​​to obtain an environmentally friendly chlorine-free wet strength agent.

[0041] Example 4

[0042] Step (1): 25 parts by weight of adipic acid, 50 parts by weight of water and 10 parts by weight of urea are uniformly mixed, 18 parts by weight of glycidyl methacrylate and 9 parts by weight of propylene glycol methyl ether are added, the mixture is reacted at 130° C. for 1 hour, 2 parts by weight of acetic acid are added, and the mixture is kept warm for 6 hours to obtain an intermediate;

[0043] Step (2): dilute the intermediate to a solid content of 45%, add 8 parts by weight of epichlorohydrin, raise the temperature to 40° C., and keep the temperature for 2 hours;

[0044] Step (3): adding 5 parts by weight of deionized water and 3 parts by weight of diethylenetriamine, continuing the reaction at a heat preservation temperature, and when the viscosity of the system rises to 45 mPa·s, adding acetic acid to adjust the pH of the system to 3.0;

[0045] Step (4): adding deionized water to adjust the solid content to about 12.5% ​​to obtain an environmentally friendly chlorine-free wet strength agent.

[0046] Comparative Example 1

[0047] The conventional method is used to prepare the polyamide polyamine epichlorohydrin resin wet strength agent, and the specific process is as follows:

[0048] Step (1): 15 parts by weight of adipic acid and 11 parts by weight of diethylenetriamine are mixed, and reacted at 170° C. for 8 hours to obtain an intermediate polyamide polyamine;

[0049] Step (2): diluting the intermediate to a solid content of about 40%, adding 13 parts by weight of epichlorohydrin, and continuing the reaction at a heat preservation temperature. When the viscosity of the system rises to 35 mPa·s, adding acetic acid to adjust the system pH to 2.5;

[0050] Step (3): adding deionized water to adjust the solid content to about 12.5% ​​to obtain a polyamide polyamine epichlorohydrin resin wet strength agent.

[0051] Comparative Example 2

[0052] Without adding glycidyl methacrylate and propylene glycol methyl ether, the other processes are similar to those in Example 4, and the specific process is as follows:

[0053] Step (1): 25 parts by weight of adipic acid, 50 parts by weight of water and 10 parts by weight of urea are mixed uniformly, and the mixture is reacted at 130° C. for 7 hours to obtain an intermediate;

[0054] Step (2): dilute the intermediate to a solid content of 45%, add 8 parts by weight of epichlorohydrin, raise the temperature to 40° C., and keep the temperature for 2 hours;

[0055] Step (3): adding 5 parts by weight of deionized water and 3 parts by weight of diethylenetriamine, continuing the reaction at a heat preservation temperature, and when the viscosity of the system rises to 45 mPa·s, adding acetic acid to adjust the pH of the system to 3.0;

[0056] Step (4): adding deionized water to adjust the solid content to about 12.5% ​​to obtain a wet strength agent.

[0057] Comparative Example 3

[0058] The same amount of diethylenetriamine was used to replace urea, epoxy resin E-20 was used to replace glycidyl methacrylate, and the other steps were the same as in Example 4. The specific process is as follows:

[0059] Step (1): 25 parts by weight of adipic acid, 50 parts by weight of water, and 10 parts by weight of diethylenetriamine are uniformly mixed, 18 parts by weight of epoxy resin E-20 and 9 parts by weight of propylene glycol methyl ether are added, the mixture is reacted at 130° C. for 1 hour, 2 parts by weight of acetic acid are added, and the mixture is kept warm for 6 hours to obtain an intermediate;

[0060] Step (2): dilute the intermediate to a solid content of 45%, add 8 parts by weight of epichlorohydrin, raise the temperature to 40° C., and keep the temperature for 2 hours;

[0061] Step (3): adding 5 parts by weight of deionized water and 3 parts by weight of diethylenetriamine, continuing the reaction at a heat preservation temperature, and when the viscosity of the system rises to 45 mPa·s, adding acetic acid to adjust the pH of the system to 3.0;

[0062] Step (4): adding deionized water to adjust the solid content to about 12.5% ​​to obtain a wet strength agent.

[0063] Comparative Example 4

[0064] The same amount of diethylenetriamine was used to replace urea, and the other steps were the same as in Example 4. The specific process is as follows:

[0065] Step (1): 25 parts by weight of adipic acid, 50 parts by weight of water, and 10 parts by weight of diethylenetriamine are uniformly mixed, 18 parts by weight of glycidyl methacrylate and 9 parts by weight of propylene glycol methyl ether are added, the mixture is reacted at 130° C. for 1 hour, 2 parts by weight of acetic acid are added, and the mixture is kept warm for 6 hours to obtain an intermediate;

[0066] Step (2): dilute the intermediate to a solid content of 45%, add 8 parts by weight of epichlorohydrin, raise the temperature to 40° C., and keep the temperature for 2 hours;

[0067] Step (3): adding 5 parts by weight of deionized water and 3 parts by weight of diethylenetriamine, continuing the reaction at a heat preservation temperature, and when the viscosity of the system rises to 45 mPa·s, adding acetic acid to adjust the pH of the system to 3.0;

[0068] Step (4): adding deionized water to adjust the solid content to about 12.5% ​​to obtain a wet strength agent.

[0069] Comparative Example 5

[0070] The same amount of epoxy resin E-20 was used to replace glycidyl methacrylate, and the other steps were the same as in Example 4. The specific process is as follows:

[0071] Step (1): 25 parts by weight of adipic acid, 50 parts by weight of water and 10 parts by weight of urea are uniformly mixed, 18 parts by weight of epoxy resin E-20 and 9 parts by weight of propylene glycol methyl ether are added, the mixture is reacted at 130° C. for 1 hour, 2 parts by weight of acetic acid are added, and the mixture is kept warm for 6 hours to obtain an intermediate;

[0072] Step (2): dilute the intermediate to a solid content of 45%, add 8 parts by weight of epichlorohydrin, raise the temperature to 40° C., and keep the temperature for 2 hours;

[0073] Step (3): adding 5 parts by weight of deionized water and 3 parts by weight of diethylenetriamine, continuing the reaction at a heat preservation temperature, and when the viscosity of the system rises to 45 mPa·s, adding acetic acid to adjust the pH of the system to 3.0;

[0074] Step (4): adding deionized water to adjust the solid content to about 12.5% ​​to obtain a wet strength agent.

[0075] Chloropropanol was detected by GC / MS (Agilent 7890B-7000C) triple quadrupole gas chromatography-mass spectrometry, and the chromatographic column was Agilent HP-5 chromatographic column. The test results of organic chlorine content are shown in Table 1.

[0076] Table 1 Sample organic chlorine content test data

[0077]

[0078] Application Examples

[0079] Unbleached kraft pulp was used, wherein the ratio of coniferous wood pulp to hardwood wood pulp was 5:5, and the beating degree was 38°SR. The filler addition amount was 15%, the retention agent dosage was 400ppm, the pulp concentration was diluted to 1.0% (mass percentage) with tap water, the wet strength agent addition amount was 1% (absolute dry weight of wet strength agent / absolute dry weight percentage of pulp), and the wet strength agent prepared in the above examples was added and stirred for 1 minute. The paper weight was 120g / m 2 The retention rate is compared based on the quantitative analysis of the hand sheets, and the water filterability is compared based on the beating degree of various pulps. Then, the dry tensile strength and wet tensile strength are tested according to GB / T2914-2008 and GB / T465.2-2008, and the ratio of wet / dry tensile index is calculated. For test data, see Table 2 for the test results of pulp and paper indicators after adding wet strength agent.

[0080] Table 2 Paper sample wet strength performance test data

[0081]

[0082]

[0083] It can be seen from the experimental results that the chlorine-free wet strength agent prepared by the present invention has a chloropropanol content of 0, and the comparative example 1 adopts a conventional PAE synthesis method, and the chloropropanol content is 3558ppm. The detection results are shown in Table 1.

[0084] The paper basis weight of the blank sample in Table 2 is 120.0 g / m 2 The paper weight of the comparative example is 121.2-124.9g / m 2 The paper weight of Examples 1-4 is between 127.0 g / m 2 The above is significantly higher than the blank sample and the control sample, and the highest can reach 129.1g / m 2 This indicates that the wet strength agent of the present invention has better retention, retention and drainage properties on the slurry, and can significantly improve the retention and drainage properties.

[0085] In Table 2, the beating degree of Examples 1-4 is below 37.4°SR, and the lowest reaches 36.0°SR, which is lower than the beating degree of the blank sample and the comparative example, indicating that the wet strength agent of the present invention has better slurry drainage performance. The wet tensile coefficient of Examples 1-4 is above 9.25Nm / g, which is significantly higher than the blank sample and the comparative example, indicating that the dry strength performance and wet strength performance of the wet strength agent of the present invention are better. The dry tensile coefficient of Examples 1-4 is above 39.78Nm / g, which is also significantly higher than the blank sample and the comparative example, indicating that the dry strength performance of the wet strength agent of the present invention is better.

[0086] It can be further seen from the data in Table 2 that replacing urea with diethylenetriamine or replacing glycidyl methacrylate with epoxy resin does not significantly improve paper properties such as dry and wet strength, indicating that the joint reaction of urea and glycidyl methacrylate produces an important synergistic effect.

[0087] It should be understood by those skilled in the art that the above embodiments are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

Claims

1. A method for preparing an environmentally friendly chlorine-free wet strength agent, characterized in that: The steps include: S1, 10-25 parts by weight of adipic acid, 5-10 parts by weight of urea, and an appropriate amount of water are mixed evenly, 6-18 parts by weight of glycidyl methacrylate and an appropriate amount of cosolvent are added, reacted at 115-135° C. for 1-3 hours, an appropriate amount of acetic acid is added, and the mixture is kept warm for 3-6 hours to obtain an intermediate; S2, dilute the intermediate to a certain solid content, add 2-8 parts by weight of epichlorohydrin, and heat to 30-40°C for insulation; S3, adding 0.5-3.0 parts by weight of an organic amine and an appropriate amount of water, continuing the heat-keeping reaction, and when the viscosity of the system rises to 30-50 mPa·s, adding an acid to adjust the pH of the system to 2-4; S4. Add deionized water to adjust the solid content to obtain an environmentally friendly chlorine-free wet strength agent.

2. The method according to claim 1, characterized in that The organic amine is selected from at least one of dimethylamine, trimethylamine, triethylamine, diethanolamine, triethanolamine and diethylenetriamine.

3. The method according to claim 2, characterized in that The amount of the organic amine used is 0.5-3.0 parts by weight.

4. The method according to claim 1, characterized in that The dosage of each component is as follows: 15-25 parts by weight of adipic acid, 6-10 parts by weight of urea, 12-18 parts by weight of glycidyl methacrylate, 5-8 parts by weight of epichlorohydrin, and 2-3.0 parts by weight of organic amine.

5. The method according to claim 4, characterized in that The dosage of each component is as follows: 20-25 parts by weight of adipic acid, 8-10 parts by weight of urea, 15-18 parts by weight of glycidyl methacrylate, 7-8 parts by weight of epichlorohydrin, and 2.5-3.0 parts by weight of organic amine.

6. The method according to claim 1, characterized in that The co-solvent is selected from at least one of ethylene glycol butyl ether, ethylene glycol tert-butyl ether and propylene glycol methyl ether.

7. The method according to claim 6, characterized in that The amount of the co-solvent used is 2-10 parts by weight.

8. The method according to claim 1, characterized in that In step S1, the amount of acetic acid used is 0.5-2.0 parts by weight.

9. The method according to claim 1, characterized in that In step S2, the insulation time is 1-2h.

10. An environmentally friendly chlorine-free wet strength agent prepared according to the method of claims 1-9.

Images