Toluene-free modified akd paper sizing agent and preparation and application thereof

Abstract

The present application provides a modified AKD paper sizing agent, which comprises any one or mixture of several compounds with the structure shown in general formula (I), wherein R 1 and R 2 are each independently selected from C1-C22 hydrocarbon groups or hydrocarbon groups with cyclic anhydride functional groups, and R 1 and R 2 each contain at least one unsaturated hydrocarbon group segment with a cyclic anhydride group. The present application also provides a method for preparing the modified AKD paper sizing agent and an emulsion made from the sizing agent. Compared with conventional AKD paper sizing agents, the modified AKD paper sizing agent of the present application makes the sizing agent emulsion used in papermaking have a faster maturation speed, a high papermaking efficiency, no toluene residue, a reduced environmental pollution, a suitable low-temperature emulsification, a saved energy consumption and a reduced production cost.

Description

Technical Field

[0001] This invention relates to the field of chemistry, and more particularly to a modified AKD paper sizing agent and its preparation and application. Background Technology

[0002] The papermaking process is usually divided into three steps: pulping, papermaking, and coating. Each step requires a variety of papermaking additives to improve efficiency, reduce consumption, improve paper quality, and enhance paper performance. Many types of paper require the addition of papermaking sizing agents in the papermaking stage to give the paper certain water resistance properties, so as to delay the penetration of paper and paperboard by water or water-based solutions and prevent the paper from becoming damp.

[0003] AKD (alkyl ketene dimer) is a neutral-alkaline paper sizing agent developed in the 1940s and 50s. It was first invented and put into production by the Hercules Corporation in the United States in 1948, primarily for the production of high-quality paper and baby bottle paperboard. However, its emulsion stability was very poor, and its retention rate was low. Over half a century of development has seen continuous optimization, resulting in significant improvements in AKD's quality and stability. Significant progress has also been made in AKD sizing research, highlighting its excellent sizing effect and advantages such as low dosage, low cost, and ease of use. Therefore, it has been widely used in the paper industry, and AKD currently holds a large market share among neutral sizing agents worldwide.

[0004] AKD is prepared by reacting acyl chloride and triethylamine. The reaction produces a large amount of solid triethylamine hydrochloride, resulting in a very high viscosity of the reaction system. Under traditional process conditions, stirring is difficult, leading to uneven reaction between the acyl chloride and triethylamine. This results in AKD products that are dark in color, have low content, and are of poor quality. To obtain high-quality products, domestic and international AKD manufacturers generally use toluene as a reaction solvent. This not only leads to a poor production environment but also leaves toluene residue in the AKD product, polluting the downstream pulp sizing environment and restricting its use in the sizing of various food packaging papers. To address the toluene residue problem, some solvent-free methods for synthesizing AKD have been reported. However, the publicly reported processes each have their advantages and disadvantages, and few have truly achieved industrial-scale production.

[0005] AKD's molecular structure contains two long-chain alkyl side chains. Therefore, after AKD reacts with fibers, the long-chain alkyl side chains act as hydrophobic ends, facing the fiber surface to form a hydrophobic layer, thus achieving the sizing function. AKD itself is insoluble in water and is an oil-soluble product, making it difficult to integrate with aqueous systems used in papermaking. Therefore, its reaction with cellulose is relatively slow. Specifically, AKD sizing particles do not react much in the wet section of the paper machine, existing only in the form of electrostatic adsorption and free particles on the fine fibers, fillers, and fiber surfaces. In the drying section, the reaction begins as the temperature rises and the moisture decreases. However, the papermaking speed is very fast, and the paper or paperboard cannot achieve complete sizing under normal operating conditions. After finishing the paper, it needs to be left to mature for a period of time to achieve the best sizing effect, generally requiring 5-7 days of storage. This large-scale storage not only occupies space but also reduces the production efficiency of finished paper.

[0006] Therefore, it is necessary to develop a new type of paper sizing agent to solve the shortcomings of the existing AKD paper sizing agent, such as slow curing and long sizing time during the sizing process, so as to improve its application performance and increase papermaking efficiency. Summary of the Invention

[0007] To address the above challenges, the inventors of this invention, through extensive research, have developed a novel modified AKD paper sizing agent, its preparation method, and the preparation and application of its emulsion. This type of paper sizing agent possesses characteristics such as no toluene residue, short curing time, high stability, and superior application performance. It solves the problem of slow curing speed when using conventional AKD paper sizing agents, improves sizing agent utilization, reduces sizing agent dosage, and increases paper sizing degree.

[0008] A first aspect of the present invention provides a modified AKD paper sizing agent, said sizing agent comprising any one or a mixture of compounds with the structure shown in general formula (I).

[0009]

[0010] Where R 1 and R 2 They can be the same or different, each independently selected from C1-C22 hydrocarbon groups or hydrocarbon groups with cyclic anhydride functional groups, and R 1 and R 2 It contains at least one unsaturated hydrocarbon segment with a cyclic anhydride group;

[0011] The unsaturated hydrocarbon segment with a cyclic anhydride group has the general formula (II) as follows:

[0012]

[0013] In general formula (II), at least one of the two sites X and Y has a cyclic anhydride group of general formula (III) as shown below;

[0014]

[0015] In the general formula (III), R 3 It is a C2-C20 secondary hydrocarbon group, preferably a C2-C10 secondary hydrocarbon group, and more preferably a C2-C6 secondary hydrocarbon group; the secondary hydrocarbon group can be a straight-chain, branched, or cyclic secondary hydrocarbon group.

[0016] In one or more embodiments, the hydrocarbon group may be a straight chain, a branched chain, or a cyclic structure, and may be saturated or unsaturated, monounsaturated or polyunsaturated.

[0017] In one or more embodiments, the secondary hydrocarbon group may be saturated or unsaturated, and may contain one or more unsaturated bonds. Preferably, the secondary hydrocarbon group has 2-4 carbon atoms forming a cyclic structure with carbonyl groups on both sides.

[0018] In one or more embodiments, the modified AKD paper sizing agent has an active functional group content of 1.6-2.5 mmol / g, preferably 1.7-2.3 mmol / g, and more preferably 1.8-2.1 mmol / g.

[0019] A second aspect of the present invention provides a method for preparing a modified AKD paper sizing agent, the method comprising the following steps:

[0020] The starting material (IV) and the cyclic anhydride (V) are added to a reaction flask and heated to mix; wherein the starting material (IV) has the general formula:

[0021]

[0022] In the general formula (IV), R' and R” can be the same or different, and each is independently selected from hydrocarbon groups of C1-C22;

[0023] The general formula for the cyclic anhydride (V) is:

[0024]

[0025] In the general formula (V), R 4 It is a C2-C20 hydrocarbon group.

[0026] In one or more embodiments, the hydrocarbon group may be a straight-chain, branched, or cyclic hydrocarbon group, preferably a cyclic hydrocarbon group.

[0027] In one or more embodiments, the hydrocarbon group can be saturated or unsaturated, and can be monounsaturated or polyunsaturated.

[0028] In one or more embodiments, at least one of R' and R” is an unsaturated hydrocarbon group.

[0029] In one or more embodiments, the R 4 It is a C2-C10 hydrocarbon group, preferably a C2-C6 hydrocarbon group.

[0030] In one or more embodiments, the hydrocarbon group may be a straight-chain, branched, or cyclic hydrocarbon group.

[0031] In one or more embodiments, the alkylene group may contain one or more unsaturated bonds, preferably having 2-4 carbon atoms forming a cyclic structure with carbonyl groups on both sides, and containing an intracyclic double bond.

[0032] In one or more embodiments, the molar ratio of the raw material (IV) to the cyclic anhydride (V) can be 0.3 to 3:1, preferably 0.5 to 2:1, and more preferably 0.8 to 1.5:1.

[0033] In one or more embodiments, the heating method may be direct heating or segmented heating.

[0034] In one or more embodiments, the heating method is a staged heating process, which involves pre-stirring at a low temperature first, followed by a gradual increase in temperature.

[0035] In one or more embodiments, the low-temperature pre-stirring temperature is 70-100°C, preferably 80-90°C; the pre-stirring time is 10-60 min, preferably 20-40 min; the maximum reaction temperature is 130-280°C, preferably 150-250°C; and the reaction time is 1-8 h, preferably 2-6 h, more preferably 3-4 h.

[0036] In one or more embodiments, one or more additives may be selectively added during the reaction process, and the additives may be selectively added to one or more of the following: catalyst, organic solvent, antioxidant, polymerization inhibitor, etc.

[0037] In one or more embodiments, the catalyst is selected from one or more of Lewis acids, metal oxide supported solid acids, organometallic compounds, transition metals, or transition metal compounds.

[0038] In one or more embodiments, the Lewis acid is selected from one or more of aluminum trichloride, boron trifluoride, ferric chloride, zinc chloride, and ferric bromide.

[0039] In one or more embodiments, the metal oxide-supported solid acid is selected from SO4. 2- / TiO2, PO4 3- / TiO2、BO3 3- One or more of / TiO2.

[0040] In one or more embodiments, the organometallic catalyst is selected from organometallic tin and / or organometallic zirconium.

[0041] In one or more embodiments, the organotin catalyst is selected from one or more of monobutyltin oxide, dibutyltin oxide, dibutyltin oxide chloride, dibutyltin dilaurate, and dibutyltin diacetate.

[0042] In one or more embodiments, the transition metal or transition metal compound is selected from one or more of rhodium, ruthenium, palladium, titanium, tungsten, etc., and the transition metal compound is selected from their oxides, chlorides, etc.

[0043] In one or more embodiments, the amount of catalyst used is 0.1-3% of the mass of the feedstock (IV), preferably 0.4%-2%, more preferably 0.8%-1.5%.

[0044] In one or more embodiments, the organic solvent is selected from acetone and hexane.

[0045] In one or more embodiments, the antioxidant or polymerization inhibitor is selected from one or more of aromatic compounds, boron-containing compounds, organic acids, and reducing metals, such as 2,6-di-tert-butyl-p-cresol, citric acid, ascorbic acid (VC), vitamin E, phytic acid, aluminum powder, phosphites, bisphenol A, hydroquinone, 2,6-di-tert-butyl-4-cresol, di-(3,5-di-tert-butyl-4-phenol)-methane, boric acid, etc.

[0046] In one or more embodiments, the amount of the antioxidant or polymerization inhibitor is 0.01-2% of the mass of the raw material (IV), preferably 0.1%-1%, more preferably 0.2%-0.5%.

[0047] In one or more embodiments, the preparation method further includes a pretreatment step of the reaction system.

[0048] In one or more embodiments, the pretreatment step includes dehydration and / or deoxygenation of the reaction system.

[0049] In one or more embodiments, the preparation method further includes post-processing the mixture obtained from the reaction step.

[0050] In one or more embodiments, the post-processing includes filtration to remove excess cyclic anhydrides.

[0051] In one or more embodiments, the post-processing further includes a purification step.

[0052] In one or more embodiments, the reaction process is protected by an inert gas, preferably nitrogen or argon.

[0053] In one or more embodiments, the reaction system pressure during the reaction process is 0-1 MPa, preferably 0.1-0.8 MPa, and more preferably 0.2-0.5 MPa.

[0054] A third aspect of the present invention provides a method for preparing a modified AKD paper sizing agent emulsion, the method comprising the following steps:

[0055] 1) Mix and disperse the modified AKD paper sizing agent, emulsifier, and water evenly;

[0056] 2) The dispersed mixture is homogenized.

[0057] In one or more embodiments, the method further includes a step of heating the modified AKD paper sizing agent prior to step 1).

[0058] In one or more embodiments, the heating step involves heating to 20-100°C, preferably 40-90°C, and more preferably 45-55°C.

[0059] In one or more embodiments, the emulsifier is selected from one or more of starch emulsifiers, polymeric emulsifiers, etc.

[0060] In one or more embodiments, the dry basis amount of the emulsifier is 5-40% of the amount of the sizing agent, preferably 5-30%, more preferably 8-25%.

[0061] In one or more embodiments, the modified AKD paper sizing agent is dispersed with emulsifier and water in a high-speed disperser.

[0062] In one or more embodiments, the dispersion time of the high-speed disperser is 5-30 min, preferably 10-20 min.

[0063] In one or more embodiments, the homogenization is performed in a high-pressure homogenizer.

[0064] In one or more embodiments, the pressure of the high-pressure homogenizer is 10-40 MPa, preferably 20-30 MPa; and the high-pressure homogenization is performed 1-3 times.

[0065] In one or more embodiments, the homogenized mixture in step 2) is cooled to below 50°C, preferably below 30°C, more preferably below 20°C, and most preferably below 10°C.

[0066] In one or more embodiments, the method further includes step 3) adding an additive to the homogenized mixture and stirring to mix evenly to obtain a sizing agent emulsion. In one or more embodiments, the additive includes one or more of a stabilizer, a curing agent, a defoamer, and a bactericide.

[0067] In one or more embodiments, the stabilizer includes zirconium oxychloride, hydrochloric acid, sulfuric acid, etc.

[0068] In one or more embodiments, the curing agent includes polydimethyldiallylammonium chloride, polyamide polyepoxychloropropane resin, etc.

[0069] In one or more embodiments, the defoamer includes polyether defoamers, silicone defoamers, etc. In one or more embodiments, in step 3), an additive is added to the homogenized mixture, water is used to adjust the solid content to 8-40%, and the mixture is stirred and mixed evenly to obtain a sizing agent emulsion.

[0070] In one or more embodiments, the solid content is 10-30%, preferably 12-20%.

[0071] In a fourth aspect, the present invention provides a modified AKD paper sizing agent emulsion, the emulsion comprising the modified AKD paper sizing agent of the first aspect of the present invention or the sizing agent obtained by the method of the second aspect of the present invention; or prepared by the method of the third aspect of the present invention.

[0072] Compared with existing traditional AKD paper sizing agents, the modified AKD paper sizing agent of the present invention has the following characteristics:

[0073] (1) Improved sizing agent retention rate and utilization rate, faster maturation speed after machine, and higher papermaking efficiency;

[0074] (2) The loss rate in wastewater is low, and there is no toluene residue in the sizing agent product, which reduces environmental pollution;

[0075] (3) Suitable for low-temperature emulsification, saving energy and reducing production costs. Attached Figure Description

[0076] Figure 1 : A schematic diagram of the reaction process between the raw material (IV) and the cyclic anhydride (V) in this invention. Detailed Implementation

[0077] In this invention, AKD, or alkyl ketone dimer, is an unsaturated lactone.

[0078] The present invention will now be described in detail. The descriptions of the technical features described below are based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0079] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0080] In this specification, the terms "substantially" or "truly" are used to indicate that the standard deviation from the theoretical model or theoretical data is within 5%, preferably 3%, and more preferably 1%.

[0081] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0082] In this instruction manual, "normal temperature" refers to an indoor temperature of 23±2℃.

[0083] In this specification, "optional" or "optionally" means that the event or situation described below may or may not occur, and the description includes both the scenario in which the event occurs and the scenario in which the event does not occur.

[0084] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0085] This invention mainly provides a paper sizing agent and its preparation and application.

[0086] <First Aspect>

[0087] In a first aspect, a modified AKD paper sizing agent is provided, the sizing agent comprising a mixture of one or more compounds including the structure shown in general formula (I).

[0088]

[0089] Where R 1 and R 2 They can be the same or different, each independently selected from C1-C22 hydrocarbon groups or hydrocarbon groups with cyclic anhydride functional groups, but R 1 and R 2It contains at least one unsaturated hydrocarbon segment with a cyclic anhydride group;

[0090] The unsaturated hydrocarbon segment with a cyclic anhydride group has the general formula (II) as follows:

[0091]

[0092] In general formula (II), at least one of the two sites X and Y has a cyclic anhydride group of general formula (III) as shown below;

[0093]

[0094] In the general formula (III), R 3 It is a C2-C20 secondary hydrocarbon group, preferably a C2-C10 secondary hydrocarbon group, and more preferably a C2-C6 secondary hydrocarbon group.

[0095] Specifically, the secondary hydrocarbon group can be a straight-chain, branched, or cyclic secondary hydrocarbon group; the secondary hydrocarbon group can be saturated or unsaturated, and can contain one or more unsaturated bonds. Preferably, the secondary hydrocarbon group has 2-4 carbon atoms forming a cyclic structure with carbonyl groups on both sides.

[0096] Specifically, the hydrocarbon group can be a straight-chain, branched, or cyclic hydrocarbon group; the hydrocarbon group can be saturated or unsaturated, and can be monounsaturated or polyunsaturated.

[0097] In some specific embodiments of the present invention, the effective functional group content of the modified AKD paper sizing agent is 1.6-2.5 mmol / g, preferably 1.7-2.3 mmol / g, and more preferably 1.8-2.1 mmol / g.

[0098] In this invention, the modified AKD paper sizing agent is in a liquid state at room temperature.

[0099] <Second aspect>

[0100] In a second aspect of the present invention, a method for preparing a modified AKD paper sizing agent is provided, the method comprising the following steps: adding a raw material (IV) and a cyclic anhydride (V) to a reaction flask and heating and mixing; wherein the general formula of the raw material (IV) is:

[0101]

[0102] The general formula for the cyclic anhydride (V) is:

[0103]

[0104] In the general formula (IV), R' and R” can be the same or different, and each is independently selected from hydrocarbon groups of C1-C22;

[0105] In the general formula (V), R 4 It is a C2-C20 hydrocarbon group.

[0106] Specifically, the raw material (IV) consists of a mixture of saturated and unsaturated hydrocarbon groups containing fourteen and sixteen carbon atoms, respectively, with hexadecane groups accounting for 80-95%.

[0107] In some specific embodiments of the present invention, the molar ratio of raw material (IV) to cyclic anhydride (V) can be 0.3 to 3:1, preferably 0.5 to 2:1, and more preferably 0.8 to 1.5:1.

[0108] In some specific embodiments of the present invention, the heating method can be direct heating or segmented heating.

[0109] Specifically, the heating method is a segmented heating process, which involves pre-stirring at a low temperature first, followed by gradual heating.

[0110] Furthermore, the low-temperature pre-stirring temperature is 70-100℃, preferably 80-90℃; the pre-stirring time is 10-60min, preferably 20-40min; the maximum reaction temperature is 130-280℃, preferably 150-250℃; and the reaction time is 1-8h, preferably 2-6h, more preferably 3-4h.

[0111] In some specific embodiments of the present invention, one or more additives may be selectively added during the reaction process. The additives may be selectively added to one or more of the following: catalyst, organic solvent, antioxidant, polymerization inhibitor, etc.

[0112] In some specific embodiments of the present invention, the catalyst is selected from one or more of Lewis acids, metal oxide supported solid acids, organometallic compounds, transition metals, or transition metal compounds.

[0113] In some specific embodiments of the present invention, the Lewis acid is selected from one or more of aluminum trichloride, boron trifluoride, ferric chloride, zinc chloride, and ferric bromide.

[0114] In some specific embodiments of the present invention, the metal oxide-supported solid acid is selected from SO4. 2- / TiO2, PO4 3- / TiO2、BO3 3- One or more of / TiO2.

[0115] In some specific embodiments of the present invention, the organometallic catalyst is selected from organometallic tin and / or organometallic zirconium.

[0116] Furthermore, the organometallic tin catalyst is selected from one or more of monobutyltin oxide, dibutyltin oxide, dibutyltin oxide chloride, dibutyltin dilaurate, and dibutyltin diacetate.

[0117] In some specific embodiments of the present invention, the transition metal or transition metal compound is selected from one or more of rhodium, ruthenium, palladium, titanium, tungsten, etc.; specifically, the transition metal compound is selected from their oxides, chlorides, etc.

[0118] In some specific embodiments of the present invention, the amount of catalyst used is 0.1-3% of the mass of the raw material (IV), preferably 0.4%-2%, more preferably 0.8%-1.5%.

[0119] In some specific embodiments of the present invention, the organic solvent is selected from inert solvents other than alcohols and amines that do not react with acid anhydrides or esters, such as acetone, hexane, etc., or is not used, preferably not toluene or other organic solvents.

[0120] In some specific embodiments of the present invention, the antioxidant or polymerization inhibitor is selected from one or more of aromatic compounds, boron-containing compounds, organic acids, and reducing metals, such as 2,6-di-tert-butyl-p-cresol, citric acid, ascorbic acid (VC), vitamin E, phytic acid, aluminum powder, phosphites, bisphenol A, hydroquinone, 2,6-di-tert-butyl-4-cresol, di-(3,5-di-tert-butyl-4-phenol)-methane, boric acid, etc.

[0121] In some specific embodiments of the present invention, the amount of antioxidant and polymerization inhibitor is 0.01-2% of the mass of raw material (IV), preferably 0.1%-1%, more preferably 0.2%-0.5%.

[0122] In some specific embodiments of the present invention, the preparation method further includes a pretreatment step of the reaction system.

[0123] In some specific embodiments of the present invention, the pretreatment step includes dehydration and / or deoxygenation of the system. The dehydration and / or deoxygenation refers to the dehydration and / or deoxygenation of the entire reaction vessel and its piping, etc.; for example, inert gas protection is used, preferably nitrogen or argon.

[0124] In some specific embodiments of the present invention, the preparation method further includes post-processing of the mixture obtained in the reaction step.

[0125] In some specific embodiments of the present invention, the post-treatment includes filtration to remove excess maleic anhydride.

[0126] In some specific embodiments of the present invention, the post-processing further includes a purification step.

[0127] In some specific embodiments of the present invention, the reaction system pressure during the reaction process is 0-1 MPa, preferably 0.1-0.8 MPa, and more preferably 0.2-0.5 MPa.

[0128] <Third aspect>

[0129] In a third aspect of the present invention, a method for preparing a modified AKD paper sizing agent emulsion is provided, the method comprising the following steps:

[0130] 1) Mix and disperse the modified AKD paper sizing agent, emulsifier, and water evenly;

[0131] 2) The dispersed mixture is homogenized.

[0132] In one or more embodiments of the present invention, the method further includes a step of heating the modified AKD paper sizing agent before step 1), wherein the modified AKD paper sizing agent is preferably heated to 20-100°C, more preferably 40-90°C, and more preferably 45-55°C in the heating step.

[0133] In one or more embodiments of the present invention, the emulsifier is selected from one or more of starch emulsifiers, polymeric emulsifiers, etc.

[0134] In one or more embodiments of the present invention, the polymeric emulsifier is selected from one or more of polydimethyldiallylammonium chloride, polydimethyldiallylammonium bromide, polyethyleneimine, etc.

[0135] In one or more embodiments of the present invention, the dry basis amount of the emulsifier is 5-40% of the amount of the sizing agent, preferably 5-30%, more preferably 8-25%.

[0136] In one or more embodiments of the present invention, in order to uniformly disperse the modified AKD paper sizing agent in the emulsifier and water, any dispersion technique may be used. Specifically, a high-speed disperser is used for dispersion, and the specific dispersion time depends on the amount of material and the temperature. For example, the dispersion time of the high-speed disperser is 5-30 min, preferably 10-20 min.

[0137] In one or more embodiments of the present invention, the homogenization process can employ any commonly used homogenization method in the art, such as using a high-pressure homogenizer with a pressure of 10-40 MPa, preferably 20-30 MPa; and homogenizing under high pressure 1-3 times.

[0138] In one or more embodiments of the present invention, the homogenized mixture in step 2) is cooled to below 50°C, preferably below 30°C, more preferably below 20°C, and most preferably below 10°C.

[0139] In one or more embodiments of the present invention, the additives added to the homogeneous mixture include stabilizers, ripening agents, defoamers, and bactericides.

[0140] In one or more embodiments of the present invention, the stabilizer includes, but is not limited to, zirconium oxychloride, hydrochloric acid, sulfuric acid, etc.

[0141] In one or more embodiments of the present invention, the curing agent includes, but is not limited to, polydimethyldiallylammonium chloride, polyamide polyepoxychloropropane resin, etc.

[0142] In one or more embodiments of the present invention, the defoamer includes, but is not limited to, polyether defoamers, silicone defoamers, etc.

[0143] In one or more embodiments of the present invention, the bactericide is any commonly used bactericide, including but not limited to chlorophenols, isothiazolinones, and quaternary ammonium salts.

[0144] In one or more embodiments of the present invention, in step 3), an additive is added to the homogenized mixture, and water is used to adjust the solid content to 8-40%, preferably 10-30%, more preferably 12-20%, and the mixture is stirred and mixed evenly to obtain a sizing agent emulsion.

[0145] <Fourth Aspect>

[0146] In a fourth aspect of the invention, a modified AKD paper sizing agent emulsion is provided, the emulsion comprising the modified AKD paper sizing agent of the first aspect of the invention or the sizing agent obtained by the method of the second aspect of the invention; or prepared by the method of the third aspect of the invention.

[0147] Example

[0148] The following embodiments are further illustrations of the present invention and are for explanatory and illustrative purposes only. The content of the present invention is not limited thereto. The embodiments in this specification are only for illustrating the present invention and do not limit the scope of protection of the present invention. The scope of protection of the present invention is defined only by the claims. Any additions, substitutions, or modifications made by those skilled in the art based on the embodiments disclosed in the present invention will fall within the scope of protection of the present invention.

[0149] The raw material used in the synthesis of the novel modified AKD paper sizing agent was LKD-101 (which contains the structure of general formula (IV), and R' and R” in the structure are a mixture of saturated and unsaturated hydrocarbon groups containing fourteen and sixteen carbon atoms, respectively, with hexadecane groups accounting for 80-95%, and this raw material was provided by Wilmar Oils Technology Co., Ltd.); the polymer emulsifier (Jiangsu Fumiao Technology Co., Ltd., model "FA-22"), the starch emulsifier (Yanzhou Tiancheng Chemical Co., Ltd., product name: AKD emulsifier); and the remaining reagents were all commercially available.

[0150] All instruments used were standard laboratory glassware.

[0151] Equipment used: High-speed disperser (IKA, Germany, model T25); High-pressure homogenizer (Shanghai Donghua High-Pressure Homogenizer, GYB Laboratory Type 40-10S).

[0152] Test methods: The content of active functional groups in the sizing agent was determined according to the method for determining the content of active ingredients in GB / T27565-2011 - Alkyl ketene dimers for industrial use. The results were expressed as molar content of active functional groups, in mmol / g. The Cobb value was determined according to GB / T1540-2002 - Determination of water absorption of paper and paperboard, in g / m³. 2 .

[0153] The following examples are only used to explain and illustrate the synthesis method of the sizing agent of the present invention, and the content of the present invention is not limited thereto.

[0154] 1. Synthesis of Modified AKD Paper Sizing Agent

[0155] Example A1

[0156] A 500ml reaction flask equipped with a mechanical stirrer, thermometer, and reflux condenser was purged with nitrogen. Then, 200g of LKD-101, 41g of maleic anhydride, 1.6g of anhydrous ruthenium trichloride, and 1g of 2,6-di-tert-butyl-p-cresol were added. The reaction was carried out under constant N2 protection, stirred at 300 rpm, and preheated to 80°C. The reaction was carried out at this temperature for 30 min, then the temperature was gradually increased to 170°C while maintaining the stirring speed, and held at this temperature for 3 h. After the reaction, the solid catalyst was removed by filtration, and unreacted maleic anhydride was removed by vacuum distillation. The molar content of the active functional groups was 1.96 mmol / g (compared to 1.67 mmol / g for conventional LKD-101), and the reaction yield was 98.5%.

[0157] Example A2

[0158] The specific operating method is the same as in Example A1, except that the amount of maleic anhydride added is 31.7g, and after low-temperature preheating, the temperature is gradually increased to 150℃ and maintained at this temperature for 4 hours. The molar content of active functional groups is 1.90 mmol / g, and the reaction yield is 98.8%.

[0159] Example A3

[0160] The specific operating method is the same as in Example A1, except that the amount of maleic anhydride added is 37.3g, the catalyst is 1.8g of dibutyltin dilaurate, after low-temperature preheating, the temperature is gradually increased to 150℃, and the reaction is maintained at this temperature for 4 hours. The molar content of active functional groups is 1.85mmol / g, and the reaction yield is 98.3%.

[0161] Example A4

[0162] The specific operation method is the same as in Example A1, except that the preheating temperature after feeding is 90°C, the reaction is carried out at this temperature for 40 minutes, the temperature is slowly increased to 180°C, and the reaction is maintained at this temperature for 3.5 hours. The molar content of active functional groups is 1.93 mmol / g, and the reaction yield is 99.1%.

[0163] Example A5

[0164] The specific operation method is the same as in Example A1, except that the reaction device is changed to a 500ml reaction vessel, the amount of maleic anhydride fed is 33.6g, the system pressure is 0.5Mpa, the reaction temperature is 150℃, the reaction is kept at this temperature for 3h, the molar content of active functional groups is 2.01mmol / g, and the reaction yield is 99.3%.

[0165] Example A6

[0166] The specific operation method is the same as in Example A1, except that methylmaleic anhydride is used, the molar content of active functional groups of the product obtained by the reaction is 1.89 mmol / g, and the reaction yield is 98.6%.

[0167] 2. Application of Modified AKD Paper Sizing Agent

[0168] Example B1

[0169] Take 100g of the modified AKD paper sizing agent from Example A1, add 120g of 25% starch emulsifier preheated to 50°C and 120g of water, mix well, and disperse for 10 minutes using a high-speed disperser. The dispersed mixture is then homogenized twice under high pressure of 30MPa using a high-pressure homogenizer. After homogenization, it is rapidly cooled to below 20°C, and then the stabilizer zirconium oxychloride, curing agent (polydimethyldiallylammonium chloride), and defoamer (polyether) are added. The concentration is adjusted to 15% solid content with water to obtain the modified AKD paper sizing agent emulsion.

[0170] This modified AKD paper sizing agent emulsion was used in laboratory wood pulp sheet making at a rate of 100 g / m³. 2 During surface sizing, the addition rate is 3 kg / ton of paper, and the Cobb value of the paper sample after finishing is 40 g / m³. 2 After 24 hours, the Cobb value of the paper sample decreased to 35 g / m³. 2 After 4 days, the Cobb value of the paper sample remained essentially unchanged at 31 g / m³. 2 .

[0171] Example B2

[0172] The specific operation method for preparing the sizing agent emulsion is the same as in Example B1, except that the sizing agent used is the modified AKD papermaking sizing agent in Example A4.

[0173] The sizing procedure is the same as in Example B1. After the paper comes off the press, the Cobb value of the paper sample is 41 g / m³. 2 After 24 hours, the Cobb value of the paper sample decreased to 36 g / m³. 2 After 5 days, the Cobb value of the paper sample remained essentially unchanged at 30 g / m³. 2 .

[0174] Example B3

[0175] The specific operation method for preparing the sizing agent emulsion is the same as in Example B1, except that the emulsifier and water used are 40g of 40% high molecular weight emulsifier and 40g of water.

[0176] The sizing procedure is the same as in Example B1. After the paper comes off the press, the Cobb value of the paper sample is 38 g / m³. 2 After 24 hours, the Cobb value of the paper sample decreased to 30 g / m³. 2After 4 days, the Cobb value of the paper sample remained essentially unchanged at 25 g / m³. 2 .

[0177] Comparative Example B1

[0178] The specific operation method for preparing the sizing agent emulsion is the same as in Example B1, except that the sizing agent used is conventional 1840AKD (Wilmar Oils & Fats Technology Co., Ltd.), and it needs to be heated to 60-80℃ to melt first.

[0179] The sizing procedure is the same as in Example B1. After the paper comes off the press, the Cobb value of the paper sample is 42 g / m³. 2 After 24 hours, the Cobb value of the paper sample decreased to 38 g / m³. 2 After 7 days, the Cobb value of the paper sample remained essentially unchanged at 32 g / m³. 2 .

[0180] Comparative Example B2

[0181] The specific operation method for preparing the sizing agent emulsion is the same as in Example B1, except that the sizing agent used is conventional 1840AKD (Fung Yi Oils Technology Co., Ltd.), and it needs to be heated to 60-80℃ to melt first. The emulsifier and water used are 40g of 40% high molecular weight emulsifier (model: FA-22) and 40g of water.

[0182] The sizing procedure is the same as in Example B1. After the paper comes off the press, the Cobb value of the paper sample is 40 g / m³. 2 After 24 hours, the Cobb value of the paper sample decreased to 37 g / m³. 2 After 7 days, the Cobb value of the paper sample remained essentially unchanged at 27 g / m³. 2 .

[0183] The modified AKD paper sizing agent prepared by the method of this invention results in a faster paper curing speed after sizing, with its Cobb value stabilizing in no more than 5 days. However, under the same conditions, the time required by the traditional AKD paper sizing agent is about 7 days. The papermaking efficiency is higher, and the curing time can be shortened by 1-2 days, reducing storage pressure.

Claims

1. A method for preparing a modified AKD paper sizing agent, characterized in that, The method includes the following steps: The raw material (IV) and cyclic anhydride (V) are added to a reaction flask, and a catalyst is also added to the reaction flask. The catalyst is selected from one or more organotin catalysts or transition metal compounds. The organotin catalyst is selected from one or more of monobutyltin oxide, dibutyltin oxide, dibutyltin oxide chloride, dibutyltin dilaurate, and dibutyldiethyltin. The transition metal compound is selected from oxides or chlorides of the following elements: rhodium, ruthenium, palladium, titanium, and tungsten. One or more antioxidants or polymerization inhibitors are also added to the reaction flask. The antioxidants or polymerization inhibitors are selected from one or more of the following: 2,6-di-tert-butyl-p-cresol, bisphenol A, hydroquinone, 2,6-di-tert-butyl-4-cresol, and di-(3,5-di-tert-butyl-4-phenol)-methane. The mixture is heated and mixed under a pressure of 0.1-0.8 MPa. The raw material (IV) is: (IV) The general formula for the cyclic anhydride (V) is: (V) In the general formula (IV), R' and R'' can be the same or different, and each is independently selected from C1-C22 hydrocarbon groups, and at least one of R' and R'' is an unsaturated hydrocarbon group; In the general formula (V), R 4 It is a C2-C20 hydrocarbon group, and the hydrocarbon group contains one or more unsaturated bonds; The preparation method further includes post-processing the mixture obtained by heating and mixing.

2. The method as described in claim 1, characterized in that, The molar ratio of raw material (IV) to cyclic anhydride (V) is 0.3 to 3:

1.

3. The method as described in claim 1, characterized in that, The amount of catalyst used is 0.1-3% of the mass of the feedstock (IV).

4. The method as described in claim 1, characterized in that, The preparation method further includes a pretreatment step for the reaction system; the pretreatment step includes dehydration and / or deoxygenation of the reaction system.

5. A method for preparing a modified AKD paper sizing agent emulsion, the method comprising the following steps: 1) A modified AKD paper sizing agent is prepared by any one of claims 1-4; 2) Mix the modified AKD paper sizing agent with emulsifier and water, and disperse evenly; 3) Homogenize the dispersed mixture.

6. The method as described in claim 5, characterized in that, The method further includes a step of heating the modified AKD paper sizing agent before step 2); the heating step involves heating to 20-100°C; after homogenization in step 3), the mixture is cooled to below 50°C; and The method further includes step 4) adding additives to the homogenized mixture, stirring and mixing evenly to obtain a sizing agent emulsion, wherein the additives are selected from stabilizers, curing agents, defoamers and bactericides; The stabilizer is selected from zirconium oxychloride, hydrochloric acid, or sulfuric acid; the curing agent is selected from polydimethyldiallylammonium chloride or polyamide polyepoxychloropropane resin; and the defoamer is selected from polyether defoamer or silicone defoamer.

7. A modified AKD paper sizing agent emulsion, characterized in that, The emulsion is prepared by the method according to claim 5 or 6.

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