Preparation method and application of quaternary ammonium salt type lignin waterproof and oil-proof agent

Abstract

The invention discloses a preparation method and application of a quaternary ammonium salt type lignin waterproof and oil-proof agent, and belongs to the technical field of bio-based waterproof and oil-proof agents. Lignin and quaternary ammonium salt are used as raw materials, quaternary ammonium salt type lignin is prepared through a substitution reaction, the quaternary ammonium salt type lignin is compounded with starch, and the quaternary ammonium salt type lignin waterproof and oil-proof agent is obtained. Paper is coated with the quaternary ammonium salt type lignin waterproof and oil-proof agent in a double-layer mode, the Cobb 60 value of the paper can be reduced to 18.01 g / m < 2 > from 62.14 g / m < 2 >, the Kit value is increased to 10 grade from 0 grade, the tensile index is increased to 57.87 Nm / g from 40.82 Nm / g, and the waterproof performance, the oil-proof performance and the mechanical performance of a paper coating can be remarkably improved; the preparation method disclosed by the invention is simple, wide in raw material source, low in cost, biodegradable, suitable for large-scale industrial production, and capable of meeting the major strategic demand of sustainable development of the material industry in China.

Description

Technical Field

[0001] The invention belongs to the technical field of bio-based water-proof and oil-proof agents, and more specifically, relates to a preparation method and application of a quaternary ammonium salt type lignin water-proof and oil-proof agent. Background Art

[0002] The world produces more than 400 million tons of plastics each year, but only 8% of them are recycled. About 30% of the world's total plastic use comes from packaging products, and these traditional plastics based on petrochemical materials are difficult to degrade in the natural environment and difficult to recycle. Such packaging materials are mainly disposed of through landfill, incineration, and ocean discharge. This treatment method, which only treats the symptoms but not the root cause, not only damages the ecological environment, but also accumulates through the food chain, affecting human life and health.

[0003] Paper-based materials have multiple natural advantages such as being renewable, recyclable, and biodegradable. Paper is mainly made of natural plant fibers interwoven with each other. The paper structure is loose and porous, and its main chemical components are hydrophilic cellulose and hemicellulose. There are a large number of hydroxyl groups in the molecular structure, which makes it have strong liquid absorption, allowing water and oil to penetrate into the paper through capillary action, thereby affecting the mechanical properties of paper-based materials and limiting their wide application in more fields. Therefore, it is of great research significance to improve the water- and oil-blocking barrier properties of paper-based materials.

[0004] At present, the traditional methods mainly use polyacrylate coating, lamination or addition of long-chain perfluorooctanoic acid and other polymers to achieve paper barrier properties, but these ingredients are not easily biodegradable and affect the repulping and recycling performance of paper. In particular, fluorine-containing waterproof and oil-proofing agents are highly persistent and bioaccumulative in the environment, which can cause harm to the human body. At present, various countries are developing new non-toxic and environmentally friendly waterproof and oil-proofing agents. Among them, there are many related studies on the preparation of waterproof and oil-proofing agents using bio-based polymers (such as polysaccharides, proteins, lipids, etc.) as the main raw materials. On this basis, bio-based waterproof and oil-proofing agents have been developed, mainly including chitosan, hemicellulose, microfibrillated cellulose and starch. Although these materials are bio-friendly, they still have high hydrophilicity. Films made of these materials are usually more hygroscopic, resulting in partial loss of barrier properties under high humidity conditions.

[0005] Chinese patent CN 114960224 A discloses a chitosan-organic silicon oil-proof hydrophobic gas barrier coating and its preparation method, however, chitosan and organosilicon are expensive and not suitable for large-scale production. Chinese patent CN 115821628A discloses a preparation method and application of a cationic starch-based nanocellulose oil-proof agent, but it is processed through three refining processes, the operation is cumbersome, and it only has oil-proof performance.

[0006] As a typical biomass macromolecule, lignin is cheap, easily available, environmentally friendly, biodegradable, and has good hydrophobic properties. Lignin contains hydroxyl and carboxyl groups with high chemical reactivity, and can be chemically modified to regulate its related properties, thus realizing the high-value utilization of "agricultural and forestry waste" lignin.

[0007] Chinese patent CN 108532362 A provides a method for preparing a lignin sizing agent. The product is used together with starch to apply sizing to the surface of corrugated paper, which can improve the water resistance of the corrugated paper, but the oil-proof effect is not proposed.

[0008] Patent CN 105899628 A discloses a lignin-based waterproof coating, which is formed by dissolving lignin in a solvent to form a lignin solution, and coating the lignin solution on a substrate to enhance the waterproofness of the substrate, but does not mention the oil-proof performance.

[0009] Therefore, there is an urgent need to develop a fully bio-based paper waterproof / oil-proof agent that has both waterproof and oil-proof functions. Summary of the invention

[0010] In view of the above problems existing in the prior art, the technical problem to be solved by the present invention is to provide a method for preparing a quaternary ammonium salt type lignin waterproof and oil-proof agent, which has a wide source of raw materials, a simple preparation method and low cost. Another technical problem to be solved by the present invention is to provide a quaternary ammonium salt type lignin waterproof and oil-proof agent prepared by the above method, which can form a dense barrier coating on the surface of paper. Another technical problem to be solved by the present invention is to provide the application of the above quaternary ammonium salt type lignin waterproof and oil-proof agent in the preparation of waterproof and oil-proof paper-based materials.

[0011] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0012] The invention discloses a method for preparing a quaternary ammonium salt type lignin waterproof and oil-proof agent. The method comprises taking lignin and a quaternary ammonium salt as raw materials, preparing the quaternary ammonium salt type lignin through a substitution reaction, and compounding the quaternary ammonium salt type lignin with starch to obtain the quaternary ammonium salt type lignin waterproof and oil-proof agent.

[0013] Preferably, the mass ratio of the lignin to the quaternary ammonium salt is 1:1-10.

[0014] Preferably, in the substitution reaction, the reaction temperature is 50°C to 100°C, and the reaction time is 2h to 6h.

[0015] Preferably, the lignin is alkali lignin.

[0016] Preferably, the quaternary ammonium salt is selected from any one of 2,3-epoxypropyltrimethylammonium chloride, alkyldimethylbenzylammonium chloride, dodecylglycidyldimethylammonium chloride and dioctadecyldimethylammonium bromide.

[0017] Preferably, the mass ratio of starch to quaternary ammonium salt lignin is 1:0.1-0.6.

[0018] Preferably, the starch is selected from any one of surface starch, native starch and oxidized starch.

[0019] The preparation method of the quaternary ammonium salt type lignin water and oil proofing agent specifically comprises the following steps:

[0020] 1) mixing lignin, 20 wt% sodium hydroxide solution and quaternary ammonium salt uniformly and performing substitution reaction, adjusting the pH to 7 after the reaction, performing rotary evaporation to dehydrate, washing the precipitate, and obtaining quaternary ammonium salt lignin;

[0021] 2) The quaternary ammonium salt lignin, starch and purified water prepared in step 1) are mixed and gelatinized to prepare a quaternary ammonium salt lignin waterproof and oil-proof agent, and the mixture is kept warm at 60° C. for use.

[0022] Preferably, in step 1), the mass ratio of lignin to 20 wt% sodium hydroxide solution is 1:5-10.

[0023] Preferably, in step 2), the starch concentration is 8%.

[0024] The method for preparing the quaternary ammonium salt type lignin waterproof and oil-proof agent prepares the quaternary ammonium salt type lignin waterproof and oil-proof agent.

[0025] The invention discloses an application of the quaternary ammonium salt type lignin waterproof and oil-proof agent in preparing waterproof and oil-proof paper-based materials.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention utilizes quaternary ammonium salt-modified lignin to be positively charged, and can be combined with negatively charged paper fibers through electrostatic adsorption to fill the pores on the surface of the paper as a filler, and can be better retained on the surface of the paper by compounding with starch, thereby forming a dense barrier coating on the surface of the paper that has dual barrier effects of water and oil resistance;

[0028] (2) The quaternary ammonium salt type lignin water-proof and oil-proof agent prepared by the present invention is applied to paper-based materials to improve the water-proof and oil-proof properties, and the Cobb 60 value of paper can be increased from 62.14 g / m 2 Down to 18.01g / m 2The Kit value increased from 0 to 10, and the tensile index increased from 40.82Nm / g to 57.87Nm / g, which significantly improved the waterproof, oil-proof and mechanical properties of the paper coating.

[0029] (3) The present invention uses lignin derived from biomass as the main raw material, which has a wide range of sources and is inexpensive, biodegradable, green and non-toxic, meeting the major strategic needs of the sustainable development of my country's materials industry;

[0030] (4) The preparation method of the quaternary ammonium salt lignin water and oil resistant agent provided by the present invention is simple to operate, low in cost, and has a broad industrial application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Infrared spectra of alkali lignin and quaternary ammonium salt lignin (L2) prepared in Example 2. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described below in conjunction with specific embodiments. In the following examples, unless otherwise specified, the technical means used are conventional means well known to those skilled in the art. If specific conditions are not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0033] The performance testing method adopted by the present invention is as follows:

[0034] 1. Water resistance test of paper: refer to the determination of water absorption of paper and paperboard GB / T 1540-2002;

[0035] 2. Test on oil resistance of paper: refer to the determination of oil resistance of paper and paperboard GB / T 22805.2-2008;

[0036] 3. Test on the tensile index and elongation of paper: refer to the determination of tensile index of paper and paperboard GB / T453-2002.

[0037] The pulping black liquor and native starch used in the following examples were provided by APP Group; the surface starch and oxidized starch were provided by Elkem Silicones (Shanghai) Co., Ltd. The preparation process of the selected alkali lignin was as follows: 500g of alkali pulping black liquor was added into a beaker, mechanically stirred at 300rmp at 60°C, sulfuric acid was added dropwise while stirring, and when the pH value of the black liquor reached 3, the acid addition was stopped, the mixture was kept warm and stirred for 90min, and then allowed to stand overnight, centrifuged and washed until neutral, freeze-dried for 48h, ground, and vacuum-dried at 40°C for 24h to obtain 24.65g of alkali lignin.

[0038] Example 1

[0039] A method for preparing a quaternary ammonium salt type lignin water and oil proofing agent comprises the following steps:

[0040] 1) 2 g of alkali lignin, 10 g of 20 wt% sodium hydroxide solution and 2 g of 2,3-epoxypropyltrimethylammonium chloride were mixed, and the mixture was reacted at 50° C. with mechanical stirring for 6 h. After the reaction, the pH was adjusted to 7 with acetic acid, and the mixture was dehydrated by rotary evaporation to obtain a precipitate, which was then washed and dried to obtain 1.23 g of quaternary ammonium salt lignin;

[0041] 2) 0.5 g of the quaternary ammonium salt lignin prepared in step 1), 2 g of surface starch and 23 g of pure water were gelatinized at 98° C. for 1 h to obtain a quaternary ammonium salt lignin waterproof and oil-proof agent, and the mixture was kept warm at 60° C. for standby use.

[0042] Example 2

[0043] A method for preparing a quaternary ammonium salt type lignin water and oil proofing agent comprises the following steps:

[0044] 1) 2 g of alkali lignin, 15 g of 20 wt% sodium hydroxide solution, and 10 g of 2,3-epoxypropyltrimethylammonium chloride were reacted at 80° C. with mechanical stirring for 4 h. After the reaction, the pH was adjusted to 7 with acetic acid, and the precipitate was washed and dried to obtain 1.31 g of quaternary ammonium salt lignin;

[0045] 2) 0.5 g of the quaternary ammonium salt lignin prepared in step 1), 2 g of surface starch and 23 g of pure water were gelatinized at 98° C. for 1 h to obtain a quaternary ammonium salt lignin waterproof and oil-proof agent, which was kept warm at 60° C. for use.

[0046] Depend on Figure 1 It can be seen that in the infrared spectrum of quaternary ammonium salt lignin, 1485cm -1 The peak at 1510 cm -1 The characteristic absorption peak of the benzene ring at 1485cm -1 The absorption peak is caused by the CN stretching vibration of the quaternary ammonium salt. Since the sample has been washed, it shows that the quaternary ammonium salt has been grafted successfully.

[0047] Example 3

[0048] A method for preparing a quaternary ammonium salt type lignin water and oil proofing agent comprises the following steps:

[0049] 1) 2g of alkali lignin, 20g of 20wt% sodium hydroxide solution, and 20g of 2,3-epoxypropyltrimethylammonium chloride were reacted at 100°C with mechanical stirring for 2h. After the reaction, the pH was adjusted to 7 with acetic acid, and the precipitate was washed and dried to obtain 1.19g of quaternary ammonium salt lignin;

[0050] 2) 0.5 g of the quaternary ammonium salt lignin prepared in step 1), 2 g of oxidized starch and 23 g of purified water were gelatinized at 98° C. for 1 h to obtain a quaternary ammonium salt lignin waterproof and oil-proof agent, which was kept warm at 60° C. for use.

[0051] Example 4

[0052] A method for preparing a quaternary ammonium salt type lignin water and oil proofing agent comprises the following steps:

[0053] 1) 2g of alkali lignin, 15g of 20wt% sodium hydroxide solution, and 10g of dodecyl glycidyl dimethyl ammonium chloride were reacted at 80°C with mechanical stirring for 4h. After the reaction, the pH was adjusted to 7 with acetic acid, and the precipitate was washed and dried to obtain 1.20g of quaternary ammonium salt lignin;

[0054] 2) 0.5 g of the quaternary ammonium salt lignin prepared in step 1), 2 g of native starch and 23 g of purified water were gelatinized at 98° C. for 1 h to obtain a quaternary ammonium salt lignin waterproof and oil-proof agent, which was kept warm at 60° C. for standby use.

[0055] Example 5

[0056] A method for preparing a quaternary ammonium salt type lignin water and oil proofing agent comprises the following steps:

[0057] 1) 2 g of alkali lignin, 15 g of 20 wt% sodium hydroxide solution, and 10 g of alkyl dimethyl benzyl ammonium chloride were reacted at 80° C. with mechanical stirring for 4 h. After the reaction, the pH was adjusted to 7 with acetic acid, and the precipitate was washed and dried to obtain 0.89 g of quaternary ammonium salt lignin;

[0058] 2) 0.5 g of the quaternary ammonium salt lignin prepared in step 1), 2 g of native starch and 23 g of purified water were gelatinized at 98° C. for 1 h to obtain a quaternary ammonium salt lignin waterproof and oil-proof agent, which was kept warm at 60° C. for standby use.

[0059] Example 6

[0060] A method for preparing a quaternary ammonium salt type lignin water and oil proofing agent comprises the following steps:

[0061] 1) 2g of alkali lignin, 15g of 20wt% sodium hydroxide solution, and 10g of dioctadecyldimethylammonium bromide were reacted at 80°C with mechanical stirring for 4h. After the reaction, the pH was adjusted to 7 with acetic acid, and the precipitate was washed and dried to obtain 1.00g of quaternary ammonium salt lignin;

[0062] 2) 0.5 g of the quaternary ammonium salt lignin prepared in step 1), 2 g of native starch and 23 g of purified water were gelatinized at 98° C. for 1 h to obtain a quaternary ammonium salt lignin waterproof and oil-proof agent, which was kept warm at 60° C. for standby use.

[0063] Example 7

[0064] A method for preparing a quaternary ammonium salt type lignin water and oil proofing agent comprises the following steps:

[0065] 1) 2g of alkali lignin, 15g of 20wt% sodium hydroxide solution, and 10g of 2,3-epoxypropyltrimethylammonium chloride were reacted at 80°C with mechanical stirring for 4h. After the reaction, the pH was adjusted to 7 with acetic acid, and the precipitate was washed and dried to obtain 1.15g of quaternary ammonium salt lignin;

[0066] 2) 0.2 g of the quaternary ammonium salt lignin prepared in step 1), 2 g of surface starch and 23 g of pure water were gelatinized at 98° C. for 1 h to obtain a quaternary ammonium salt lignin waterproof and oil-proof agent, which was kept warm at 60° C. for standby use.

[0067] Example 8

[0068] A method for preparing a quaternary ammonium salt type lignin water and oil proofing agent comprises the following steps:

[0069] 1) 2 g of alkali lignin, 15 g of 20 wt% sodium hydroxide solution, and 10 g of 2,3-epoxypropyltrimethylammonium chloride were reacted at 80° C. with mechanical stirring for 4 h. After the reaction, the pH was adjusted to 7 with acetic acid, and the precipitate was washed and dried to obtain 1.37 g of quaternary ammonium salt lignin;

[0070] 2) 1.2 g of the quaternary ammonium salt lignin prepared in step 1), 2 g of surface starch and 23 g of purified water were gelatinized at 98° C. for 1 h to obtain a quaternary ammonium salt lignin waterproof and oil-proof agent, which was kept warm at 60° C. for use.

[0071] Example 9

[0072] A method for preparing a quaternary ammonium salt type lignin water and oil proofing agent comprises the following steps:

[0073] 1) 2 g of alkali lignin, 15 g of 20 wt% sodium hydroxide solution, and 10 g of 2,3-epoxypropyltrimethylammonium chloride were reacted at 80° C. with mechanical stirring for 4 h. After the reaction, the pH was adjusted to 7 with acetic acid, and the precipitate was washed and dried to obtain 1.26 g of quaternary ammonium salt lignin;

[0074] 2) 0.5 g of the quaternary ammonium salt lignin prepared in step 1), 2 g of native starch and 23 g of purified water were gelatinized at 98° C. for 1 h to obtain a quaternary ammonium salt lignin waterproof and oil-proof agent, which was kept warm at 60° C. for standby use.

[0075] Comparative Example 1

[0076] Add 2g of surface starch and 23g of pure water into a four-necked flask equipped with an electric stirrer, a condenser and a thermometer, then put it into a constant temperature water bath, heat it to 98°C for gelatinization reaction for 1h to obtain the surface starch surface sizing agent, and keep it warm at 60°C for standby use.

[0077] Comparative Example 2

[0078] Add 2 g of native starch and 23 g of pure water into a four-necked flask equipped with an electric stirrer, a condenser and a thermometer, then put it into a constant temperature water bath, heat it to 98°C for gelatinization reaction for 1 hour to obtain a native starch surface sizing agent, and keep it warm at 60°C for standby use.

[0079] Example 10

[0080] Use a rod coater to coat the product at a weight of 80 g / m 2 Double coating is applied on the surface of A4 paper with a coating amount of 5g / m 2 The specific process is: first apply a layer of coating, put the coated paper into a 60℃ constant temperature oven for 2 minutes, then take it out, apply it again and put it into a 60℃ constant temperature oven for 5 minutes, and finally balance the treated A4 paper in a constant temperature and humidity chamber for 24 hours before testing the physical properties of the paper.

[0081] The quaternary ammonium salt type lignin water and oil proofing agent prepared in Examples 1 to 9, the surface starch surface sizing agent prepared in Comparative Example 1, and the native starch surface sizing agent prepared in Comparative Example 2 were coated on the surface of paper by the above method, and the coated paper was tested, and the results are shown in Table 1. The smaller the Cobb 60 value, the better the water resistance of the paper; the larger the Kit value, the better the oil resistance of the paper.

[0082] Table 1 Physical properties of the quaternary ammonium salt lignin water-proof and oil-proof agent prepared in Examples 1 to 9, the surface starch surface sizing agent prepared in Comparative Example 1, and the original starch surface sizing agent prepared in Comparative Example 2 coated paper and the original paper

[0083] sample <![CDATA[Cobb 60(g / m 2 )]]> Kit Value Tensile index (Nm / g) Elongation(%) Base paper 62.14 0 40.82 1.7 Example 1 30.67 4 46.85 1.8 Example 2 18.01 10 57.87 2.0 Example 3 33.78 4 44.12 1.8 Example 4 31.34 4 46.01 1.8 Example 5 35.99 2 41.33 1.7 Example 6 30.11 1 47.11 1.8 Example 7 23.09 9 52.05 1.9 Example 8 22.14 9 52.34 1.9 Example 9 25.11 10 50.11 1.9 Comparative Example 1 45.21 1 40.00 1.6 Comparative Example 2 49.11 1 38.01 1.5

[0084] As shown in Table 1, compared with Comparative Example 1, after being coated with the quaternary ammonium salt lignin water-proof and oil-proof agent prepared by the present invention, the Cobb 60 value of the paper is increased from 45.21 g / m 2 Down to 18.01g / m 2 , Kit value increased from 0 to 10, tensile index increased from 40.82Nm / g to 57.87Nm / g, and the waterproof, oil-proof and mechanical properties of paper coatings were significantly improved. This shows that the lignin modified by quaternary ammonium salts is combined with paper fibers through electrostatic adsorption, filling the pores on the surface of paper as a filler, and is better retained on the surface of paper by compounding with starch, enhancing the film-forming property of paper, thereby forming a dense barrier coating on the surface of paper with dual barrier effects of waterproof and oil-proof.

[0085] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a quaternary ammonium salt type lignin water and oil resistant agent, characterized in that: The invention adopts lignin and quaternary ammonium salt as raw materials, obtains quaternary ammonium salt lignin through substitution reaction, and then compounds the quaternary ammonium salt lignin with starch to obtain the quaternary ammonium salt lignin water-proof and oil-proof agent.

2. The method for preparing the quaternary ammonium salt lignin water and oil resistant agent according to claim 1, characterized in that: The mass ratio of the lignin to the quaternary ammonium salt is 1:1-10.

3. The preparation method of the quaternary ammonium salt type lignin water and oil resistant agent according to claim 1, characterized in that, In the substitution reaction, the reaction temperature is 50° C. to 100° C., and the reaction time is 2 h to 6 h.

4. The method for preparing the quaternary ammonium salt lignin water and oil resistant agent according to claim 1, characterized in that: The quaternary ammonium salt is selected from any one of 2,3-epoxypropyltrimethylammonium chloride, alkyldimethylbenzylammonium chloride, dodecylglycidyldimethylammonium chloride, and dioctadecyldimethylammonium bromide.

5. The method for preparing the quaternary ammonium salt lignin water and oil resistant agent according to claim 1, characterized in that: The mass ratio of the starch to the quaternary ammonium salt lignin is 1:0.1-0.

6.

6. The method for preparing the quaternary ammonium salt lignin water and oil resistant agent according to claim 1, characterized in that: The starch is selected from any one of surface starch, native starch and oxidized starch.

7. The method for preparing the quaternary ammonium salt lignin water and oil resistant agent according to claim 1, characterized in that: The specific steps include: 1) mixing lignin, 20 wt% sodium hydroxide solution and quaternary ammonium salt uniformly and performing substitution reaction, adjusting the pH to 7 after the reaction, performing rotary evaporation to dehydrate, washing the precipitate, and obtaining quaternary ammonium salt lignin; 2) The quaternary ammonium salt lignin, starch and purified water prepared in step 1) are mixed and gelatinized to prepare a quaternary ammonium salt lignin waterproof and oil-proof agent, and the mixture is kept warm at 60° C. for use.

8. The method for preparing the quaternary ammonium salt type lignin water and oil resistant agent according to claim 7, characterized in that: In the step 1), the mass ratio of lignin to 20 wt% sodium hydroxide solution is 1:5-10.

9. A method for preparing a quaternary ammonium salt lignin water-proof and oil-proof agent according to any one of claims 1 to 8, wherein the quaternary ammonium salt lignin water-proof and oil-proof agent is prepared.

10. Use of the quaternary ammonium salt type lignin waterproof and oil-proof agent according to claim 9 in the preparation of waterproof and oil-proof paper-based materials.

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