Lubricant for papermaking coating and preparation method thereof

Abstract

The invention discloses a lubricant for papermaking coating and a preparation method thereof, belonging to the technical field of lubricant processing, and is used to solve the technical problems in the prior art that the lubricant for papermaking coating has high viscosity, poor self-bearing capacity and the glossiness of coated paper needs to be further improved. The invention comprises the following raw materials in parts by weight: 40-60 parts of base oil, 10-15 parts of modified colloid, 4-8 parts of polyether sulfonate, 2-6 parts of phosphoric acid amide auxiliary agent, 0.5-1 part of viscosity index improver, 2-5 parts of additives and 7-10 parts of purified water, the base oil is composed of liquid paraffin, palm oil and pentaerythritol ester in a weight ratio of 3:6:2, and the viscosity index improver is composed of polymethacrylate and polyisobutylene in a weight ratio of 2:1. The lubricant prepared by the invention not only has low viscosity and high bearing capacity, but also can improve the glossiness of coated paper.

Description

Technical Field

[0001] The invention relates to the technical field of lubricant processing, and in particular to a lubricant for papermaking coating and a preparation method thereof. Background Art

[0002] In the papermaking industry, the coating process is a key step. By coating with coating materials, a uniform coating can be formed on the surface of the paper, which can not only improve the smoothness of the paper, but also reduce the ink absorption of the paper, making the printed matter clearer and brighter, directly affecting the quality and performance of the final paper. Coating usually uses coating materials containing white powder (such as chalk powder, gypsum powder, etc.). These white powders can increase the whiteness of the paper. At the same time, coating can also make the surface of the paper smoother and make the paper look brighter. During the coating process, there will be a certain amount of friction between the paper and the coating device. The coating material containing lubricant can reduce this friction, reduce the wear of the coating device and paper, and extend the service life of the equipment.

[0003] The paper coating lubricant in the prior art usually includes a base oil and a series of additives, which usually have a high viscosity and are difficult to be evenly coated on the paper surface during the coating process. In addition, the lubricant's own load-bearing capacity is limited. During the coating process, it cannot fully lubricate the entire paper surface, causing wear and friction during the coating process, resulting in insufficient gloss of the coated paper. The gloss of paper is one of the important indicators for evaluating its quality. In addition to the insufficient gloss caused by its own load-bearing capacity, the lubricant in the prior art is often unable to improve the gloss of the paper well during the coating process after the lubricant is mixed with the coating material.

[0004] In view of the technical defects in this aspect, a solution is now proposed. Summary of the invention

[0005] The object of the present invention is to provide a paper coating lubricant and a preparation method thereof, so as to solve the technical problems in the prior art that the paper coating lubricant has high viscosity, poor self-bearing capacity and the glossiness of the coated paper needs to be further improved.

[0006] The object of the present invention can be achieved by the following technical scheme: a lubricant for papermaking coating, comprising the following raw materials in parts by weight: 40-60 parts of base oil, 10-15 parts of modified colloid, 4-8 parts of polyether sulfonate, 2-6 parts of phosphoric acid amide auxiliary agent, 0.5-1 part of viscosity index improver, 2-5 parts of additives and 7-10 parts of purified water;

[0007] The base oil is composed of liquid paraffin, palm oil and pentaerythritol ester in a weight ratio of 3:6:2;

[0008] The viscosity index improver is composed of polymethacrylate and polyisobutylene in a weight ratio of 2:1;

[0009] The additives are composed of anti-wear agent, antioxidant, corrosion inhibitor, defoamer and extreme pressure agent in a weight ratio of 10:5:5:2:3, the anti-wear agent is orthophosphate, the antioxidant is antioxidant 1010, the corrosion inhibitor is tricresyl phosphate, the defoamer is defoamer silicone oil, and the extreme pressure agent is sulfurized fatty acid ester.

[0010] Furthermore, the preparation method of the pentaerythritol ester is as follows: pentaerythritol, pimelic acid and a catalyst are added to a nitrogen-protected reactor and stirred, the temperature of the reactor is increased to 105-115° C., and the reaction is kept warm for 40-60 minutes, n-pentanoic acid, n-heptanoic acid and undecanoic acid are added to the reactor, and the reaction is kept warm for 4-6 hours, and the pentaerythritol ester is obtained by post-processing.

[0011] Furthermore, the weight ratio of the pentaerythritol, pimelic acid, catalyst, pentanoic acid, heptanoic acid and undecanoic acid is 14:24:0.5:2.5:2.6:1.9, the catalyst is stannous oxide, and the post-treatment operation includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, ethyl acetate is added to the reactor, stirred for 20 to 30 minutes, filtered, the filtrate is transferred to the reactor, the temperature of the reactor is raised to 55 to 65°C, and distilled under reduced pressure until no liquid is produced to obtain pentaerythritol ester.

[0012] Furthermore, the modified colloid is obtained by processing the following steps:

[0013] A1, guar gum and purified water were added to a reactor, stirred and mixed at room temperature, and then allowed to stand for swelling for 3-5 hours, and alkali solution was added to the reactor, and the temperature of the reactor was raised to reflux, and the reactor was heat-treated for 5-7 hours, and the pretreated guar gum was obtained by post-treatment;

[0014] A2. Add the pretreated guar gum, modifier and dimethyl sulfoxide into a reactor and stir until the system is dissolved. Add a catalyst into the reactor, increase the temperature of the reactor to 75-85°C, keep the temperature for 2-3 hours, and perform post-treatment to obtain a modified guar gum.

[0015] Furthermore, in step A1, the dosage ratio of guar gum, purified water and alkali solution is 2g:7mL:1mL, and the alkali solution is composed of potassium hydroxide, sodium benzoate and purified water in a dosage ratio of 3g:2g:40mL. The post-treatment operation in step A1 includes: after the reaction is completed, the temperature of the reactor is reduced to room temperature, the pH of the reaction system is adjusted to 7-8, anhydrous ethanol is added to the reactor, stirred for 20-30min, filtered, the filtrate is transferred to the reactor and stirred, the temperature of the reactor is increased to 65-75°C, and distilled under reduced pressure until no liquid is produced to obtain pretreated guar gum; in step A2, the pretreated guar gum, The amount ratio of the modifier, dimethyl sulfoxide and the catalyst is 3g:2g:30mL:0.02g, the catalyst is tin tetrachloride, and the post-treatment operation in step A2 includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, ethyl acetate is added to the reactor and stirred for 20-30min, a saturated sodium chloride solution is added to the reactor, and the reaction mixture is allowed to stand for separation, the aqueous phase is back-extracted with ethyl acetate twice, the ethyl acetate phases are combined, and the ethyl acetate phases are washed 5 times with purified water, the organic phase is transferred to the reactor, the temperature of the reactor is raised to 65-75°C, and the reaction mixture is distilled under reduced pressure until no liquid is extracted to obtain a modified colloid.

[0016] Further, the modifier is obtained by processing the following steps:

[0017] B1, add abietyl alcohol, toluene and catalyst into a reactor, stir until the system is dissolved, lower the temperature of the reactor to 20-25°C, slowly drop epichlorohydrin into the reactor, and after the addition is complete, slowly increase the temperature of the reactor to 60-70°C, keep the reaction at this temperature for 5-7h, and post-treat to obtain intermediate I;

[0018] B2. Add intermediate I, toluene and alkali solution into a reactor and stir. Raise the temperature of the reactor to 45-50° C. and keep the reaction temperature for 5-6 hours. Post-treat to obtain a modifier.

[0019] The synthetic reaction principle of the modifier is:

[0020]

[0021] Furthermore, in step B1, the amount ratio of abutilon, toluene, catalyst and epichlorohydrin is 2g:7mL:0.1g:1.3g, the catalyst is boron trifluoride etherate, and the post-treatment operation includes: after the reaction is completed, the reactor is kept at 60-70°C, and distilled under reduced pressure until no liquid is produced to obtain intermediate I; in step B2, the amount ratio of intermediate I, toluene and alkali solution is 2g:5mL:8mL, and the alkali solution is 40-45wt% potassium hydroxide solution, and the post-treatment operation includes: after the reaction is completed, standing and separating the liquids, washing the organic phase three times with saturated sodium chloride solution, transferring the filtrate to the reactor, keeping the reactor at 75-85°C, and distilling under reduced pressure until no liquid is produced to obtain a modifier.

[0022] Furthermore, the preparation method of the phosphoric acid amide auxiliary agent is: octadecylamine, dimethyl phosphate, and chloroform are added to a reactor and stirred until the system is dissolved, a catalyst is added to the reactor, the temperature of the reactor is increased to 55-60° C., the reaction is kept warm for 4-6 hours, and the phosphoric acid amide auxiliary agent is obtained by post-processing.

[0023] Furthermore, the molar ratio of octadecylamine and dimethyl phosphate is 1:1, the usage ratio of octadecylamine, chloroform and catalyst is 1g:4mL:0.1g, the catalyst is triethylamine, and the post-treatment operation includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, the filtrate is transferred to the reactor, the temperature of the reactor is raised to 55-60°C, and distilled under reduced pressure until no liquid is produced to obtain a phosphoric acid amide auxiliary agent.

[0024] Furthermore, the preparation method of the polyether sulfonate is: nonylphenol polyoxyethylene ether is added to a reactor, the temperature of the reactor is lowered to -10 to 0°C, a sulfonating agent is slowly added to the reactor, after the addition is completed, the reaction is kept warm for 40 to 60 minutes, the temperature of the reactor is raised to room temperature, the reaction is kept warm for 2 to 3 hours, and the polyether sulfonate is obtained by post-treatment.

[0025] Furthermore, the dosage ratio of the nonylphenol polyoxyethylene ether and the sulfonating agent is 5g:3g, the sulfonating agent is 95-98wt% sulfuric acid, and the post-treatment operation includes: after the reaction is completed, adding anhydrous ethanol to the reactor, lowering the temperature of the reactor to 0-5°C, dripping 5mol / L sodium hydroxide solution into the reactor, adjusting the system pH to 7, filtering, transferring the filtrate to the reactor, raising the temperature of the reactor to 60-70°C, and distilling under reduced pressure until no liquid is produced to obtain polyether sulfonate.

[0026] The present invention also provides a method for preparing a lubricant for papermaking coating, comprising the following steps:

[0027] S1. Add modified colloid, polyether sulfonate, phosphoric acid amide additive, additive and purified water into a reactor, raise the temperature of the reactor to 65-75°C, and stir for 40-60 minutes;

[0028] S2, add base oil to the reactor, add it to the reactor, keep warm and stir for 30 to 40 minutes;

[0029] S3, add viscosity index improver to the reactor, and stir at the temperature for 20 to 30 minutes;

[0030] S4. The temperature of the reactor is lowered to room temperature, and the mixture is filtered through a 200-mesh filter to obtain a lubricant.

[0031] The present invention has the following beneficial effects:

[0032] 1. The present invention uses pentaerythritol and pimelic acid as raw materials, and an esterification reaction occurs under the action of a catalyst to form a plurality of pentaerythritol cross-linked intermediates, and then an esterification reaction is performed with n-pentanoic acid, n-heptanoic acid, and undecanoic acid to generate pentaerythritol esters with multiple cross-links. The multiple cross-linked structure of pentaerythritol esters enhances its own lubricating properties, thereby improving the load-bearing capacity of the lubricant and reducing friction and wear in the papermaking coating process; polyether sulfonate is prepared by sulfonating nonylphenol polyoxyethylene ether under the action of a sulfonating agent. Ether sulfonate is a surfactant, which has excellent wetting and dispersing properties, increases the water dispersibility of the lubricant and reduces the friction between molecules, reduces the viscosity of the lubricant, and improves the fluidity and uniformity of the lubricant in the coating process. The anionic nature of the polyether sulfonate may interact with the cationic substances in the coating material to form a stable coating, thereby improving the load-bearing capacity of the lubricant. The two are synergistically combined to further enhance the load-bearing capacity of the lubricant.

[0033] 2. The modifier of the present invention generates an intermediate I by a nucleophilic substitution reaction between a hydroxyl group on abietic alcohol and an alkylene oxide group on epichlorohydrin under a catalyst condition, and then an electrophilic substitution reaction is generated between the chlorine element on the intermediate I and the hydroxyl group under an alkaline condition to reform an epoxy group; the guar gum is subjected to an alkaline hydrolysis reaction with an alkali solution composed of potassium hydroxide and sodium benzoate to generate a pretreated guar gum containing galactose and mannose and other basic units constituting the guar gum; the hydroxyl group on the pretreated guar gum and the epoxy group on the modifier undergo a nucleophilic substitution addition reaction under the action of a catalyst, and the modifier is grafted onto the pretreated guar gum to obtain a modified gum; the guar gum is subjected to alkaline hydrolysis to generate a small molecular guar gum monomer, which reduces its own viscosity, and the modified guar gum contains an alkane side chain, which improves the compatibility of the modified gum with the base oil, reduces phase separation and interface problems, and the guar gum itself has excellent film-forming properties and is suitable for paper A uniform and smooth coating is formed on the surface of the paper, thereby improving the gloss of the paper, and the polyether sulfonate cooperates with the modified colloid to improve the dispersant of pentaerythritol ester in the lubricant, improve the wettability and dispersibility of the paper surface, form a uniform and dense coating on the paper surface, and further improve the gloss of the coated paper; phosphoric acid amide is prepared by octadecylamine and dimethyl phosphate under the condition of triethylamine catalyst, and the phosphoric acid amide molecules can form a strong interaction with other components of the lubricant, which helps the lubricant to be evenly dispersed and stably suspended, improve the uniformity and hiding power of the coating, and then increase the bearing capacity of the coating. The phosphoric acid amide additive can reduce the roughness and tiny bumps on the surface of the coating by improving the bearing capacity and uniformity of the coating, and cooperate with other components to further improve the transparency and gloss of the coating, so that the coating can better reflect light and improve the gloss of the paper.

[0034] 3. The present invention also prepares a lubricant by selecting liquid paraffin, palm oil, and pentaerythritol ester to mix in proportion to form a base oil of the lubricant, and then mixing modified colloid, polyether sulfonate, phosphoric acid amide auxiliary agent with orthophosphate, antioxidant 1010, tricresyl phosphate, defoaming agent silicone oil, and sulfurized fatty acid ester. The mixture is uniformly mixed with the base oil under a high temperature environment, and the lubricant is prepared by blending with a viscosity index improver. Liquid paraffin and palm oil both have relatively low viscosity, and the viscosity of pentaerythritol ester is relatively high. By adjusting the ratio between liquid paraffin, palm oil, and pentaerythritol ester, the overall viscosity of the lubricant is reduced. Pentaerythritol ester generally has good lubricity and load-bearing capacity, and can form a lubricating film on the friction interface to reduce friction and wear. Both pentaerythritol ester and palm oil have certain lubricity, and the smoothness and glossiness of the coating surface are improved. Through the interaction between the modified colloid, polyether sulfonate, phosphoric acid amide auxiliary agent and the additive, the viscosity of the lubricant is reduced, while the load-bearing capacity of the lubricant and the glossiness of the coated paper are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 It is a line graph of the viscosity grades of lubricants prepared in the examples and comparative examples of the present invention;

[0037] Figure 2 The figure is a bar graph of the load-bearing capacity of the lubricants prepared in the embodiments of the present invention and the comparative examples;

[0038] Figure 3 The effects of lubricants prepared in the examples and comparative examples of the present invention on the glossiness of coated paper are shown. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Example 1

[0041] This embodiment provides a method for preparing a lubricant for papermaking coating, comprising the following steps:

[0042] S1. Preparation of pentaerythritol ester

[0043] Weigh: 140 g of pentaerythritol, 240 g of pimelic acid and 5 g of stannous oxide, add to a nitrogen-protected reactor and stir, raise the temperature of the reactor to 105° C., and keep the temperature for 40 min. Add 5 g of n-pentanoic acid, 26 g of n-heptanoic acid, and 19 g of undecanoic acid to the reactor, keep the temperature for 4 h, lower the temperature of the reactor to room temperature, add 600 mL of ethyl acetate to the reactor, stir for 20 min, filter, transfer the filtrate to the reactor, raise the temperature of the reactor to 55° C., and distill under reduced pressure until no liquid is produced to obtain pentaerythritol ester.

[0044] S2. Preparation of modified colloid

[0045] Mix potassium hydroxide, sodium benzoate and purified water in a ratio of 3g:2g:40mL to obtain alkali solution for later use;

[0046] Weigh: 200 g of guar gum and 700 mL of purified water are added to a reactor, stirred and mixed at room temperature, and allowed to stand for swelling for 3 h, 100 mL of alkali solution is added to the reactor, the temperature of the reactor is increased to reflux the system, and the heat preservation treatment is performed for 5 h. The temperature of the reactor is lowered to room temperature, and the pH of the reaction system is adjusted to 7. 1000 mL of anhydrous ethanol is added to the reactor, stirred for 20 min, filtered, and the filtrate is transferred to the reactor and stirred. The temperature of the reactor is increased to 65° C., and vacuum distillation is performed until no liquid is produced to obtain pretreated guar gum.

[0047] Weigh: 200 g of abietic alcohol, 700 mL of toluene and 10 g of boron trifluoride etherate, add them into a reactor, stir until the system is dissolved, lower the temperature of the reactor to 20° C., slowly drop 130 g of epichlorohydrin into the reactor, and after the addition is complete, slowly increase the temperature of the reactor to 60° C., keep the reaction at this temperature for 5 hours, keep the reactor at 60° C., and distill under reduced pressure until no liquid is produced to obtain intermediate I;

[0048] Weigh: 200 g of intermediate I, 500 mL of toluene and 800 mL of 40 wt% potassium hydroxide solution are added to a reactor and stirred. The temperature of the reactor is raised to 45° C. and the reaction is kept warm for 5 hours. The organic phase is allowed to stand for separation. The filtrate is transferred to a reactor. The reactor is kept warm at 75° C. and distilled under reduced pressure until no liquid is produced to obtain a modifier.

[0049] Weigh: 300g of pretreated guar gum, 200g of modifier, and 3000mL of dimethyl sulfoxide are added to a reactor and stirred until the system is dissolved, 2g of tin tetrachloride is added to the reactor, the temperature of the reactor is increased to 75°C, and the reaction is kept warm for 2h. The temperature of the reactor is lowered to room temperature, 3000mL of ethyl acetate is added to the reactor and stirred for 20min, 30L of saturated sodium chloride solution is added to the reactor, and the reaction is allowed to stand for separation. After the aqueous phase is back-extracted with ethyl acetate twice, the ethyl acetate phases are combined, and the ethyl acetate phase is washed 5 times with purified water. The organic phase is transferred to the reactor, the temperature of the reactor is increased to 65°C, and distilled under reduced pressure until no liquid is produced to obtain a modified colloid.

[0050] S3. Preparation of polyether sulfonate

[0051] Weigh: 50g of nonylphenol polyoxyethylene ether is added to a reactor, the temperature of the reactor is lowered to -10°C, 30g of 95wt% sulfuric acid is slowly added dropwise to the reactor, after the addition is completed, the reaction is kept warm for 40min, the temperature of the reactor is raised to room temperature, and the reaction is kept warm for 2h, 200mL of anhydrous ethanol is added to the reactor, the temperature of the reactor is lowered to 0°C, 5mol / L sodium hydroxide solution is added dropwise to the reactor, the pH of the system is adjusted to 7, suction filtered, the filtrate is transferred to the reactor, the temperature of the reactor is raised to 60°C, and reduced pressure distillation is performed until no liquid is produced to obtain polyether sulfonate.

[0052] S4. Preparation of phosphoric acid amide additive

[0053] Weigh: 26.9 g of octadecylamine, 12.6 g of dimethyl phosphate, and 107.6 mL of chloroform, add them to a reactor and stir until the system is dissolved, add 2.7 g of triethylamine to the reactor, raise the temperature of the reactor to 55°C, keep the reaction warm for 4 hours, lower the temperature of the reactor to room temperature, filter, transfer the filtrate to the reactor, raise the temperature of the reactor to 55°C, and distill under reduced pressure until no liquid is produced to obtain a phosphoric acid amide auxiliary.

[0054] S5. Preparation of lubricant

[0055] Liquid paraffin, palm oil and pentaerythritol ester are uniformly mixed in a weight ratio of 3:6:2 to obtain a base oil for later use;

[0056] The polymethacrylate and polyisobutylene are mixed uniformly in a weight ratio of 2:1 to obtain a viscosity index improver for later use;

[0057] Orthophosphate, antioxidant 1010, tricresyl phosphate, defoamer silicone oil, and sulfurized fatty acid ester are uniformly mixed in a weight ratio of 10:5:5:2:3 to obtain an additive for standby use, wherein the model of the sulfurized fatty acid ester is YD-3015;

[0058] Weigh: 100g of modified colloid, 40g of polyether sulfonate, 20g of phosphoric acid amide auxiliary agent, 20g of additive and 70g of purified water and add them to the reactor, raise the temperature of the reactor to 65°C, stir for 40min, add 400g of base oil to the reactor, add it to the reactor, keep warm and stir for 30min, add 5g of viscosity index improver to the reactor, keep warm and stir for 20min, lower the temperature of the reactor to room temperature, filter through a 200-mesh filter to obtain a lubricant.

[0059] Example 2

[0060] This embodiment provides a method for preparing a lubricant for papermaking coating, comprising the following steps:

[0061] S1. Preparation of pentaerythritol ester

[0062] Weigh: 140 g of pentaerythritol, 240 g of pimelic acid and 5 g of stannous oxide, add to a nitrogen-protected reactor and stir, raise the temperature of the reactor to 110° C., and keep warm for 50 min. Add 5 g of n-pentanoic acid, 26 g of n-heptanoic acid and 19 g of undecanoic acid to the reactor, keep warm for 5 h, lower the temperature of the reactor to room temperature, add 600 mL of ethyl acetate to the reactor, stir for 25 min, filter, transfer the filtrate to the reactor, raise the temperature of the reactor to 60° C., and distill under reduced pressure until no liquid is produced to obtain pentaerythritol ester.

[0063] S2. Preparation of modified colloid

[0064] Mix potassium hydroxide, sodium benzoate and purified water in a ratio of 3g:2g:40mL to obtain alkali solution for later use;

[0065] Weigh: 200 g of guar gum and 700 mL of purified water are added to a reactor, stirred and mixed at room temperature, and allowed to stand for swelling for 4 h, 100 mL of alkali solution is added to the reactor, the temperature of the reactor is increased to reflux the system, and the heat preservation treatment is carried out for 6 h. The temperature of the reactor is lowered to room temperature, and the pH of the reaction system is adjusted to 7.5. 1000 mL of anhydrous ethanol is added to the reactor, stirred for 25 min, filtered, and the filtrate is transferred to the reactor and stirred. The temperature of the reactor is increased to 70° C., and vacuum distillation is performed until no liquid is produced to obtain pretreated guar gum.

[0066] Weigh: 200 g of abietic alcohol, 700 mL of toluene and 10 g of boron trifluoride etherate, add them into a reactor, stir until the system is dissolved, lower the temperature of the reactor to 23° C., slowly drop 130 g of epichlorohydrin into the reactor, and after the addition is complete, slowly increase the temperature of the reactor to 65° C., keep the reaction at this temperature for 6 hours, keep the reactor at 65° C., and distill under reduced pressure until no liquid is produced to obtain intermediate I;

[0067] Weigh: 200 g of intermediate I, 500 mL of toluene and 800 mL of 43 wt% potassium hydroxide solution are added to a reactor and stirred. The temperature of the reactor is raised to 47°C and the reaction is kept warm for 5.5 hours. The organic phase is washed three times with a saturated sodium chloride solution, and the filtrate is transferred to a reactor. The reactor is kept warm at 80°C and distilled under reduced pressure until no liquid is produced to obtain a modifier.

[0068] Weigh: 300g of pretreated guar gum, 200g of modifier, and 3000mL of dimethyl sulfoxide are added to a reactor and stirred until the system is dissolved, 2g of tin tetrachloride is added to the reactor, the temperature of the reactor is increased to 80°C, and the reaction is kept warm for 2.5h. The temperature of the reactor is lowered to room temperature, 3000mL of ethyl acetate is added to the reactor and stirred for 25min, 30L of saturated sodium chloride solution is added to the reactor, and the reaction is allowed to stand for separation. After the aqueous phase is back-extracted with ethyl acetate twice, the ethyl acetate phases are combined, and the ethyl acetate phase is washed 5 times with purified water. The organic phase is transferred to the reactor, the temperature of the reactor is increased to 70°C, and distilled under reduced pressure until no liquid is produced to obtain a modified colloid.

[0069] S3. Preparation of polyether sulfonate

[0070] Weigh: 50g of nonylphenol polyoxyethylene ether is added to a reactor, the temperature of the reactor is lowered to -5°C, 30g of 97wt% sulfuric acid is slowly added dropwise to the reactor, after the addition is completed, the reaction is kept warm for 50min, the temperature of the reactor is raised to room temperature, and the reaction is kept warm for 2.5h, 200mL of anhydrous ethanol is added to the reactor, the temperature of the reactor is lowered to 2.5°C, 5mol / L sodium hydroxide solution is added dropwise to the reactor, the pH of the system is adjusted to 7, suction filtered, the filtrate is transferred to the reactor, the temperature of the reactor is raised to 65°C, and reduced pressure distillation is performed until no liquid is produced to obtain polyether sulfonate.

[0071] S4. Preparation of phosphoric acid amide additive

[0072] Weigh: 26.9 g of octadecylamine, 12.6 g of dimethyl phosphate, and 107.6 mL of chloroform, add them to a reactor and stir until the system is dissolved, add 2.7 g of triethylamine to the reactor, raise the temperature of the reactor to 57°C, keep the reaction warm for 5 hours, lower the temperature of the reactor to room temperature, filter, transfer the filtrate to the reactor, raise the temperature of the reactor to 57°C, and distill under reduced pressure until no liquid is produced to obtain a phosphoric acid amide auxiliary.

[0073] S5. Preparation of lubricant

[0074] Liquid paraffin, palm oil and pentaerythritol ester are uniformly mixed in a weight ratio of 3:6:2 to obtain a base oil for later use;

[0075] The polymethacrylate and polyisobutylene are mixed uniformly in a weight ratio of 2:1 to obtain a viscosity index improver for later use;

[0076] Orthophosphate, antioxidant 1010, tricresyl phosphate, defoamer silicone oil, and sulfurized fatty acid ester are uniformly mixed in a weight ratio of 10:5:5:2:3 to obtain an additive for standby use, wherein the model of the sulfurized fatty acid ester is YD-3015;

[0077] Weigh: 125g of modified colloid, 60g of polyether sulfonate, 40g of phosphoric acid amide additive, 35g of additive and 85g of purified water and add them to a reactor, raise the temperature of the reactor to 70°C, stir for 50min, add 500g of base oil to the reactor, add it to the reactor, keep warm and stir for 35min, add 7.5g of viscosity index improver to the reactor, keep warm and stir for 25min, lower the temperature of the reactor to room temperature, filter through a 200-mesh filter to obtain a lubricant.

[0078] Example 3

[0079] This embodiment provides a method for preparing a lubricant for papermaking coating, comprising the following steps:

[0080] S1. Preparation of pentaerythritol ester

[0081] Weigh: 140 g of pentaerythritol, 240 g of pimelic acid and 5 g of stannous oxide, add them to a nitrogen-protected reactor and stir, raise the temperature of the reactor to 115° C., and keep the temperature for 60 min. Add 5 g of n-pentanoic acid, 26 g of n-heptanoic acid and 19 g of undecanoic acid to the reactor, keep the temperature for 6 h, lower the temperature of the reactor to room temperature, add 600 mL of ethyl acetate to the reactor, stir for 30 min, filter, transfer the filtrate to the reactor, raise the temperature of the reactor to 65° C., and distill under reduced pressure until no liquid is produced to obtain pentaerythritol ester.

[0082] S2. Preparation of modified colloid

[0083] Mix potassium hydroxide, sodium benzoate and purified water in a ratio of 3g:2g:40mL to obtain alkali solution for later use;

[0084] Weigh: 200 g of guar gum and 700 mL of purified water are added to a reactor, stirred and mixed at room temperature, and allowed to stand for swelling for 5 h, 100 mL of alkali solution is added to the reactor, the temperature of the reactor is increased to reflux the system, and the heat preservation treatment is performed for 7 h. The temperature of the reactor is lowered to room temperature, and the pH of the reaction system is adjusted to 8. 1000 mL of anhydrous ethanol is added to the reactor, stirred for 30 min, filtered, and the filtrate is transferred to the reactor and stirred. The temperature of the reactor is increased to 75° C., and vacuum distillation is performed until no liquid is produced to obtain pretreated guar gum.

[0085] Weigh: 200 g of abietic alcohol, 700 mL of toluene and 10 g of boron trifluoride etherate, add them into a reactor, stir until the system is dissolved, lower the temperature of the reactor to 25° C., slowly drop 130 g of epichlorohydrin into the reactor, and after the dropwise addition is complete, slowly increase the temperature of the reactor to 70° C., keep the reaction at this temperature for 7 hours, keep the reactor at 70° C., and distill under reduced pressure until no liquid is produced to obtain intermediate I;

[0086] Weigh: 200 g of intermediate I, 500 mL of toluene and 800 mL of 45 wt% potassium hydroxide solution are added to a reactor and stirred. The temperature of the reactor is raised to 50° C. and the reaction is kept warm for 6 hours. The organic phase is allowed to stand for separation. The filtrate is transferred to a reactor, the reactor is kept warm at 85° C., and vacuum distillation is performed until no liquid is produced to obtain a modifier.

[0087] Weigh: 300g of pretreated guar gum, 200g of modifier, and 3000mL of dimethyl sulfoxide are added to a reactor and stirred until the system is dissolved, 2g of tin tetrachloride is added to the reactor, the temperature of the reactor is increased to 85°C, and the reaction is kept warm for 3h. The temperature of the reactor is lowered to room temperature, 3000mL of ethyl acetate is added to the reactor and stirred for 30min, 30L of saturated sodium chloride solution is added to the reactor, and the reaction is allowed to stand for separation. After the aqueous phase is back-extracted with ethyl acetate twice, the ethyl acetate phases are combined, and the ethyl acetate phase is washed 5 times with purified water. The organic phase is transferred to the reactor, the temperature of the reactor is increased to 75°C, and distilled under reduced pressure until no liquid is produced to obtain a modified colloid.

[0088] S3. Preparation of polyether sulfonate

[0089] Weigh: 50g of nonylphenol polyoxyethylene ether is added to a reactor, the temperature of the reactor is lowered to 0°C, 30g of 98wt% sulfuric acid is slowly added dropwise to the reactor, after the addition is completed, the reaction is kept warm for 60min, the temperature of the reactor is raised to room temperature, and the reaction is kept warm for 3h, 200mL of anhydrous ethanol is added to the reactor, the temperature of the reactor is lowered to 5°C, 5mol / L sodium hydroxide solution is added dropwise to the reactor, the pH of the system is adjusted to 7, suction filtered, the filtrate is transferred to the reactor, the temperature of the reactor is raised to 70°C, and reduced pressure distillation is performed until no liquid is produced to obtain polyether sulfonate.

[0090] S4. Preparation of phosphoric acid amide additive

[0091] Weigh: 26.9 g of octadecylamine, 12.6 g of dimethyl phosphate, and 107.6 mL of chloroform, add them to a reactor and stir until the system is dissolved, add 2.7 g of triethylamine to the reactor, raise the temperature of the reactor to 60°C, keep the reaction warm for 6 hours, lower the temperature of the reactor to room temperature, filter, transfer the filtrate to the reactor, raise the temperature of the reactor to 60°C, and distill under reduced pressure until no liquid is produced to obtain a phosphoric acid amide auxiliary.

[0092] S5. Preparation of lubricant

[0093] Liquid paraffin, palm oil and pentaerythritol ester are uniformly mixed in a weight ratio of 3:6:2 to obtain a base oil for later use;

[0094] The polymethacrylate and polyisobutylene are mixed uniformly in a weight ratio of 2:1 to obtain a viscosity index improver for later use;

[0095] Orthophosphate, antioxidant 1010, tricresyl phosphate, defoamer silicone oil, and sulfurized fatty acid ester are uniformly mixed in a weight ratio of 10:5:5:2:3 to obtain an additive for standby use, wherein the model of the sulfurized fatty acid ester is YD-3015;

[0096] Weigh: 150g of modified colloid, 80g of polyether sulfonate, 60g of phosphoric acid amide auxiliary agent, 50g of additives and 100g of purified water and add them to a reactor. The temperature of the reactor is raised to 75°C and stirred for 60min. 600g of base oil is added to the reactor and stirred for 40min. 10g of viscosity index improver is added to the reactor and stirred for 30min. The temperature of the reactor is lowered to room temperature and filtered through a 200-mesh filter to obtain a lubricant.

[0097] Comparative Example 1

[0098] The difference between this comparative example and Example 3 is that step S1 is omitted and pentaerythritol is not added to the base oil in step S5.

[0099] Comparative Example 2

[0100] The difference between this comparative example and Example 3 is that step S2 is eliminated, and the guar gum in step S2 is substituted for the modified gum in step S5.

[0101] Comparative Example 3

[0102] The difference between this comparative example and Example 3 is that the pretreated guar gum in step S2 is used to replace the modified gum in step S5.

[0103] Comparative Example 4

[0104] The difference between this comparative example and Example 3 is that step S3 is omitted and polyether sulfonate is not added in step S5.

[0105] Comparative Example 5

[0106] The difference between this comparative example and Example 3 is that step S4 is eliminated and no phosphoric acid amide auxiliary agent is added in step S5.

[0107] Performance Test:

[0108] The viscosity and load-bearing capacity of the lubricant samples prepared in Examples 1-3 and Comparative Examples 1-3 were tested, and the prepared lubricant samples were added to the coating material at an addition amount of 5%, and the coating material was coated at a coating amount of 20 g / m 2 The coating was carried out, and the glossiness of the prepared paper was tested. The viscosity of the lubricant sample was measured according to the standard GB / T 3141-1994 "ISO viscosity classification of industrial liquid lubricants" to determine the ISO viscosity grade of the sample; the load-bearing capacity of the lubricant was measured according to the standard GB / T 11144-2007 "Determination of extreme pressure properties of lubricating fluids - Timken method" to determine the contact pressure of the sample; the glossiness of the paper sample was tested according to the standard GB / T10335.1-2017 "Coated paper and paperboard coated art printing paper (coated paper)". The specific test results are shown in the following table:

[0109]

[0110] Data Analysis:

[0111] The ISO viscosity grade of the lubricant prepared by the present invention reaches 5, the load-bearing capacity of the lubricant reaches 55353psi, and the glossiness of the paper after being coated with the coating material containing the lubricant reaches 79gu, while the glossiness of the paper after being coated with the traditional paper coating lubricant can only reach 67gu. All the test data are better than those of the comparative example, indicating that the lubricant prepared by the present invention not only has low viscosity and high load-bearing capacity, but also can improve the glossiness of the coated paper.

[0112] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0113] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0114] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A lubricant for papermaking coating, characterized in that: The invention comprises the following raw materials in parts by weight: 40-60 parts of base oil, 10-15 parts of modified colloid, 4-8 parts of polyether sulfonate, 2-6 parts of phosphoric acid amide additive, 0.5-1 parts of viscosity index improver, 2-5 parts of additives and 7-10 parts of purified water; The base oil is composed of liquid paraffin, palm oil and pentaerythritol ester in a weight ratio of 3:6:2; The viscosity index improver is composed of polymethacrylate and polyisobutylene in a weight ratio of 2:1; The additives are composed of an antiwear agent, an antioxidant, an anticorrosive agent, a defoaming agent, and an extreme pressure agent in a weight ratio of 10:5:5:2:3, wherein the antiwear agent is orthophosphate, the antioxidant is antioxidant 1010, the anticorrosive agent is tricresyl phosphate, the defoaming agent is defoaming agent silicone oil, and the extreme pressure agent is sulfurized fatty acid ester; The modified colloid is obtained by processing the following steps: A1, guar gum and purified water were added to a reactor, stirred and mixed at room temperature, and then allowed to stand for swelling for 3-5 hours, and alkali solution was added to the reactor. The reactor temperature was raised to reflux, and the reactor was heat-treated for 5-7 hours, and the pre-treated guar gum was obtained by post-processing; A2, adding pretreated guar gum, modifier, and dimethyl sulfoxide into a reactor and stirring until the system is dissolved, adding a catalyst into the reactor, raising the temperature of the reactor to 75-85°C, keeping the temperature for 2-3h, and post-treating to obtain a modified colloid; The modifier is obtained by processing the following steps: B1, add abietyl alcohol, toluene and catalyst into a reactor, stir until the system is dissolved, lower the temperature of the reactor to 20-25°C, slowly drop epichlorohydrin into the reactor, and after the dropwise addition is complete, slowly increase the temperature of the reactor to 60-70°C, keep the reaction at this temperature for 5-7h, and post-treat to obtain intermediate I; B2, adding intermediate I, toluene and alkali solution into a reactor and stirring, raising the temperature of the reactor to 45-50°C, keeping the temperature for reaction for 5-6h, and post-treating to obtain a modifier; The preparation method of the polyether sulfonate is as follows: nonylphenol polyoxyethylene ether is added into a reactor, the temperature of the reactor is lowered to -10-0°C, a sulfonating agent is slowly added dropwise into the reactor, after the addition is completed, the reaction is carried out by heat preservation for 40-60 minutes, the temperature of the reactor is raised to room temperature, the reaction is carried out by heat preservation for 2-3 hours, and the polyether sulfonate is obtained by post-treatment.

2. A lubricant for papermaking coating according to claim 1, characterized in that: The preparation method of pentaerythritol ester comprises: adding pentaerythritol, pimelic acid and a catalyst into a nitrogen-protected reactor and stirring, raising the temperature of the reactor to 105-115° C., keeping the temperature for reaction for 40-60 minutes, adding n-pentanoic acid, n-heptanoic acid and undecanoic acid into the reactor, keeping the temperature for reaction for 4-6 hours, and post-treating to obtain pentaerythritol ester.

3. A lubricant for papermaking coating according to claim 2, characterized in that: The weight ratio of the pentaerythritol, pimelic acid, catalyst, n-pentanoic acid, n-heptanoic acid and undecanoic acid is 14:24:0.5:2.5:2.6:1.9, and the catalyst is stannous oxide.

4. A lubricant for papermaking coating according to claim 1, characterized in that: In step A1, the dosage ratio of guar gum, purified water and alkali solution is 2g:7mL:1mL, and the alkali solution is composed of potassium hydroxide, sodium benzoate and purified water in a dosage ratio of 3g:2g:40mL; in step A2, the dosage ratio of pretreated guar gum, modifier, dimethyl sulfoxide and catalyst is 3g:2g:30mL:0.02g, and the catalyst is tin tetrachloride.

5. A lubricant for papermaking coating according to claim 1, characterized in that: In step B1, the amount ratio of abutilon, toluene, catalyst and epichlorohydrin is 2g:7mL:0.1g:1.3g, and the catalyst is boron trifluoride etherate; in step B2, the amount ratio of intermediate I, toluene and alkali solution is 2g:5mL:8mL, and the alkali solution is 40~45wt% potassium hydroxide solution.

6. A lubricant for papermaking coating according to claim 1, characterized in that: The preparation method of the phosphoric acid amide auxiliary agent is as follows: octadecylamine, dimethyl phosphate and chloroform are added into a reaction kettle and stirred until the system is dissolved, a catalyst is added into the reaction kettle, the temperature of the reaction kettle is increased to 55-60° C., the reaction is carried out by heat preservation for 4-6 hours, and the phosphoric acid amide auxiliary agent is obtained by post-processing.

7. The method for preparing a lubricant for paper coating according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Add modified colloid, polyether sulfonate, phosphoric acid amide additive, additive and purified water into the reactor, raise the temperature of the reactor to 65-75°C, and stir for 40-60 minutes; S2, add base oil to the reactor, add it to the reactor, keep warm and stir for 30-40 minutes; S3, add viscosity index improver to the reactor, keep warm and stir for 20-30 minutes; S4. The temperature of the reactor is lowered to room temperature, and the mixture is filtered through a 200-mesh filter to obtain a lubricant.

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