Cationic water-based polyamide resin and preparation method thereof

Abstract

The invention discloses cationic water-based polyamide resin, and belongs to the field of high-molecular polymers. The polyamide resin comprises the following raw materials in parts by mass: 65-70 parts of a polyamide resin intermediate, 20-25 parts of an acrylate monomer, 10-15 parts of a vinyl cationic monomer and 5-10 parts of a glycidyl-group-containing vinyl monomer, the polyamide resin intermediate is prepared from polyamine, binary acid and allyloxy polyoxyethylene ether. Dimer acid with a flexible molecular chain and allyloxy polyoxyethylene ether are introduced into a polyamide resin intermediate, and polyamide resin is modified. And acrylate, cationic groups and glycidyl groups are introduced, so that the resin is endowed with cationic property, the hydrophilicity of the polyamide resin is increased, the resin has a cross-linked structure, the polyamide resin can be combined with paper fibers, and the strength of the paper is further improved. Epoxy chloropropane is not used, and organic solvents and emulsifiers are not needed, so that the method is safe and environment-friendly.

Description

Technical Field

[0001] The invention belongs to the field of high molecular polymers, and specifically relates to a cationic water-based polyamide resin and a preparation method thereof. Background Art

[0002] Polyamide resin is a chain or network polymer with repeated amide groups (-CONH-) in the molecule. Since the amide bond is a strong polar group, it can form hydrogen bonds between macromolecules, making polyamide resin have the characteristics of high strength, corrosion resistance, weather resistance, solvent resistance, etc. It has been widely used in the fields of ink, hot melt adhesive, synthetic fiber and coating. Polyamide resin can be divided into solvent-based polyamide and non-solvent-based polyamide according to solubility. Since solvent-based polyamide produces more volatile organic compounds (VOCs) during use, it pollutes the environment and endangers human health. Non-toxic and pollution-free water-based polyamide is an important development direction in this field.

[0003] At present, the main methods for preparing water-based polyamide are: introducing amine or carboxyl groups into the resin molecular chain, neutralizing with acid or alkali to form cationic or anionic resins, making them water-soluble or solubilized and dispersed in water; introducing a certain number of strong hydrophilic groups such as carboxyl, amino, hydroxyl, amide, ether, etc. into the resin molecular chain, self-emulsifying and dispersing in water. Based on the molecular structure characteristics of polyamide resin itself (such as strong polarity and reactivity, etc.), the study of water-based modification can further broaden the application field of this resin.

[0004] In addition, in the field of papermaking, paper strength is the main factor that determines the use of paper, which includes dry strength and wet strength. In the wet-end chemistry of papermaking, additives are often added to improve the connection between fibers, such as adding polymer resins, using the combination between resin and fiber to produce interlaced entanglement, forming a cross-linked network structure, and giving the resin itself as a polymer strength to the paper, thereby improving the performance of the paper in all aspects. Polyamide resin contains a large number of amide bonds in its molecular structure. Most of the industry uses epichlorohydrin (ECH) to react with it to prepare water-soluble resins, but the hydrolysis of epichlorohydrin (ECH) will produce mutagenic organic chlorine 1,3-dichloro-2-propanol (DCP) and 3-chloro-1,2-propylene glycol (MCPD). Long-term exposure to these harmful substances will pose potential risks to the health of users.

[0005] CN 109629335 A discloses a wet strength agent for household paper and a preparation method thereof, wherein polyethylene polyamine and an organic dibasic acid are mixed and reacted to obtain a polyamide polyamine prepolymer; and the polyamide polyamine prepolymer is mixed and reacted with epichlorohydrin, acrylamide, a cationic monomer, an initiator, a coupling agent, and a crosslinking agent to obtain a wet strength agent. The invention introduces epichlorohydrin, and the tensile strength retention rate after immersion in water is only 8.67-17.74%. Summary of the invention

[0006] In order to solve the problems existing in the above-mentioned prior art, the object of the present invention is to provide a cationic water-based polyamide resin.

[0007] Another object of the present invention is to provide the use of the cationic water-based polyamide resin in the preparation of a paper strengthening agent.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A cationic water-based polyamide resin comprises the following raw materials in parts by weight: 65-70 parts of a polyamide resin intermediate, 20-25 parts of an acrylate monomer, 10-15 parts of a vinyl cationic monomer, and 5-10 parts of a glycidyl-containing vinyl monomer;

[0010] The polyamide resin intermediate is prepared from polyamine, dibasic acid and allyloxy polyoxyethylene ether, wherein the molar ratio of the polyamine to the dibasic acid is (0.9-1):1, and the added amount of the allyloxy polyoxyethylene ether is 10-20% by mass of the dibasic acid; the dibasic acid includes dimer acid and adipic acid; the molar ratio of the dimer acid to the adipic acid is (0.1-0.3):1.

[0011] The present invention introduces dimer acid with flexible molecular chains and allyloxy polyoxyethylene ether into a polyamide resin intermediate to modify the polyamide resin to be water-based. The dimer acid with flexible molecular chains can extend the resin molecules, so that the synthesized polyamide resin will not become brittle due to excessive rigidity when used as a paper reinforcing agent. The introduced allyloxy polyoxyethylene ether contains a large number of hydrophilic groups, which can improve the water solubility of the resin intermediate. In addition to amide bonds, the molecular structure of the polyamide resin intermediate also contains reactive groups—amino groups-NH- / -NH 2 , and introduce acrylate into the polyamide resin to further extend the chain of the polyamide molecules to form a high molecular polymer. The introduced cationic groups give the resin cationicity and increase the hydrophilicity of the polyamide resin. The introduced glycidyl groups give the resin a cross-linked structure, which enables the polyamide resin to combine with paper fibers. Amide bonds are introduced into the paper fibers, causing them to intertwine with each other to form a cross-linked network structure, thereby improving the strength of the paper.

[0012] The present invention firstly adopts a melt polycondensation method to synthesize a polyamide resin intermediate, wherein the intermediate molecular structure contains flexible links and reactive groups; then, in the presence of an initiator, a cross-linking structural unit is introduced into the molecular structure of the polyamide resin intermediate through free radical polymerization, and a cationic group is introduced while making it water-based to prepare a cationic water-based polyamide resin. Moreover, no organic solvent is required in the entire resin intermediate preparation process, which is safe and environmentally friendly, and the introduction of a polyoxyethylene ether group with a certain molecular weight can form an emulsion when the polyamide resin intermediate reacts with a vinyl monomer, and no additional emulsifier needs to be added, thereby ensuring the smooth progress of the reaction.

[0013] In the present invention, the molar ratio of the polyamine to the dibasic acid is controlled to be (0.9-1):1, so that the amino group in the raw material is excessive, thereby ensuring that the intermediate contains a certain amount of reactive groups - amine -NH- / -NH 2 , which is conducive to further chain extension of the intermediate to form a cross-linked structure, thereby combining polyester amide with fibers and improving paper strength.

[0014] Specifically, the number average molecular weight of the allyloxy polyoxyethylene ether is 600-1000.

[0015] If the molecular weight of allyloxy polyoxyethylene ether is too small, there will be too few hydrophilic groups in the polymer, which will affect the hydrophilicity of the polyamide resin and further affect the performance of the paper strengthener; if the molecular weight is too large, the viscosity of the entire reaction system will be too high, and a large amount of water will need to be added for dilution in the later stage, making it difficult to discharge the material.

[0016] Specifically, the dimer acid is an oleic acid dimer, and the oleic acid dimer is at least one of a cottonseed oleic acid dimer, a tall oil acid dimer, a palmitoleic acid dimer, a ricinoleic acid dimer, and a soybean oleic acid dimer.

[0017] Specifically, the acrylic acid ester monomer is at least one of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isooctyl (meth)acrylate, and lauryl (meth)acrylate.

[0018] Specifically, the polyamine is at least one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine and polyethylenepolyamine.

[0019] In the present invention, a catalyst is usually added to the polyamide resin intermediate during the preparation process.

[0020] Specifically, the catalyst is at least one of p-toluenesulfonic acid, 2-methylbenzenesulfonic acid, 2,5-dimethylbenzenesulfonic acid, 4-isopropylbenzenesulfonic acid, and dodecylbenzenesulfonic acid.

[0021] Specifically, the added amount of the catalyst is 0.8-1.0% of the total mass of the polyamine, the dibasic acid and the allyloxy polyoxyethylene ether.

[0022] Preferably, the catalyst is p-toluenesulfonic acid.

[0023] Specifically, the polyamide resin intermediate is synthesized by a melt polycondensation method.

[0024] Specifically, the preparation method of the polyamide resin intermediate comprises the following steps:

[0025] The polyamine, dibasic acid, allyloxy polyoxyethylene ether and catalyst are mixed in an inert atmosphere, heated to 120-140°C, and reacted for 1-2 hours; the temperature is raised to 170-190°C, and the reaction is continued for 2-3 hours, and a polyamide resin intermediate is obtained after cooling.

[0026] More specifically, the cooling includes: after the reaction is complete, draining water through a condenser, cooling to 130°C to 150°C when no water is discharged, slowly adding hot water, and cooling to 50°C to 70°C.

[0027] Preferably, the mixing is stirring at a speed of 180 to 200 rpm.

[0028] Specifically, the vinyl cationic monomer is at least one of (meth)acryloyloxyethyltrimethylammonium chloride, (meth)acryloyloxypropyltrimethylammonium chloride, dimethyldiallylammonium chloride, (meth)acryloyloxyethyldimethylbenzylammonium chloride, and (meth)acrylamidopropyltrimethylammonium chloride.

[0029] Specifically, the glycidyl group-containing vinyl monomer is at least one of allyl glycidyl ether, glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and epoxycyclohexylmethyl (meth)acrylate.

[0030] Specifically, the preparation method of the polyamide resin comprises: mixing a polyamide resin intermediate, an acrylate monomer, a vinyl cationic monomer and a glycidyl-containing vinyl monomer, and then copolymerizing the mixture to obtain the polyamide resin.

[0031] Specifically, an initiator needs to be added during copolymerization, and the initiator includes an oxidizing agent and a reducing agent.

[0032] More specifically, the polyamide resin is obtained by copolymerization using a free radical polymerization method.

[0033] More specifically, the preparation method of the polyamide resin comprises the following steps:

[0034] The polyamide resin intermediate, acrylate monomer, vinyl cationic monomer and glycidyl-containing vinyl monomer are mixed in an inert gas, the temperature is raised to 40-60° C., an initiator is added, and the reaction is carried out for 4-6 hours to obtain the polyamide resin.

[0035] More specifically, the dispersion medium of the reaction is deionized water.

[0036] More specifically, the oxidant is at least one of potassium sulfate, ammonium persulfate, sodium persulfate, and hydrogen peroxide.

[0037] More specifically, the reducing agent is at least one of sodium sulfite, sodium bisulfite, bleaching powder, tartaric acid, ferrous sulfate, ferrous pyrophosphate, and ferrous chloride.

[0038] More specifically, the amount of the oxidant added is 0.3% to 0.5% of the total mass of the reaction monomers and the intermediates, and the amount of the reducing agent added is 0.15% to 0.25% of the total mass of the reaction monomers and the intermediates.

[0039] The present invention also protects the use of the polyamide resin in preparing a paper reinforcing agent.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The present invention introduces dimer acid with flexible molecular chains and allyloxy polyoxyethylene ether into a polyamide resin intermediate to modify the polyamide resin. Acrylate, cationic groups and glycidyl groups are introduced into the polyamide resin to further extend the polyamide molecules to form a high molecular polymer, thereby giving the resin cationicity, increasing the hydrophilicity of the polyamide resin, and making the resin have a cross-linked structure, thereby making the polyamide resin able to combine with paper fibers, introducing amide bonds into the paper fibers, making them intertwined and entangled with each other, forming a cross-linked network structure, and thereby improving the strength of the paper.

[0042] The invention does not use epichlorohydrin, thus improving the safety of the paper strengthening agent. No organic solvent is needed in the preparation process, which is safe and environmentally friendly, and no additional emulsifier is needed, thus ensuring smooth reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Infrared spectrum of the polyamide resin intermediate prepared in Example 1.

[0044] Figure 2 Infrared spectrum of the cationic polyamide resin prepared in Example 1. DETAILED DESCRIPTION

[0045] The present invention is further described below in conjunction with examples. These examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually carried out according to conventional conditions in the art or according to the conditions recommended by the manufacturer; the raw materials, reagents, etc. used, unless otherwise specified, are all raw materials and reagents that can be obtained from commercial channels such as conventional markets. Any non-substantial changes and substitutions made by those skilled in the art on the basis of the present invention belong to the scope of protection claimed by the present invention.

[0046] Example 1

[0047] S1. Add 51.6g of diethylenetriamine, 58.4g of adipic acid, 56.1g of dimer fatty acid (soybean oleic acid dimer), 11.45g of allyloxy polyoxyethylene ether (number average molecular weight 800) and 1.6g of p-toluenesulfonic acid to a four-necked flask equipped with an electric stirrer, a constant pressure dropping funnel, a thermometer and a condenser, and add them to the reactor respectively, pass nitrogen, stir and heat to 140°C, stir at 180 rpm, and react for 2h; heat to 190°C, continue to react for 3h, drain water through the condenser, and when no water is discharged, cool to 150°C, slowly add 140g of hot water, cool to 50°C, and adjust to a polyamide resin intermediate with a solid content of 20±1% with deionized water. Among them, the molar ratio of polyamine to dibasic acid is 1:1; the molar ratio of dimer fatty acid to adipic acid is 0.25:1.

[0048] S2. Add 300g of deionized water as a solvent to a four-necked flask equipped with an electric stirrer, a constant pressure dropping funnel, a thermometer and a condenser, turn on the stirrer, and weigh 325g of a polyamide resin intermediate with a solid content of 20% prepared in step S1, 10g of butyl acrylate, 10g of methyl methacrylate, 13.33g of an aqueous solution containing 75wt% methacryloyloxyethyl trimethylammonium chloride and 5g of glycidyl methacrylate under a nitrogen atmosphere, add them to the four-necked flask respectively, stir at 500 rpm for 30 minutes, and then reduce the stirring speed to 200 rpm; raise the temperature in the four-necked flask to 50°C, add 2.5g of a 10% aqueous sodium bisulfite solution, and stir for 10 minutes; add 5g of a 10% aqueous ammonium persulfate solution, react for 6 hours, cool to room temperature, adjust the pH to 7.0 with acetic acid, and finally adjust to a cationic polyamide resin aqueous solution with a solid content of 15±1% with deionized water.

[0049] Example 2

[0050] S1. Add 51.6g of diethylenetriamine, 65.75g of adipic acid, 28.25g of dimerized fatty acid (soybean oleic acid dimer), 9.4g of allyloxy polyoxyethylene ether (number average molecular weight 800) and 1.6g of p-toluenesulfonic acid to a four-necked flask equipped with an electric stirrer, a constant pressure dropping funnel, a thermometer and a condenser, and add them to the reactor respectively, pass nitrogen, stir and heat to 140°C, stir at 180 rpm, and react for 2h; heat to 190°C, continue to react for 3h, drain water through the condenser, and when no water is discharged, cool to 150°C, slowly add 140g of hot water, cool to 50°C, and adjust to a polyamide resin intermediate with a solid content of 20±1% with deionized water. Among them, the molar ratio of polyamine to dibasic acid is 1:1; the molar ratio of dimerized fatty acid to adipic acid is 0.11:1.

[0051] Step S2. is the same as S2. in Example 1.

[0052] Example 3

[0053] S1. Add 51.6g of diethylenetriamine, 58.4g of adipic acid, 56.1g of dimerized fatty acid (soybean oleic acid dimer), 22.9g of allyloxy polyoxyethylene ether (number average molecular weight 800) and 1.6g of p-toluenesulfonic acid to a four-necked flask equipped with an electric stirrer, a constant pressure dropping funnel, a thermometer and a condenser, and add them to the reactor respectively, pass nitrogen, stir and heat to 140°C, stir at 180 rpm, and react for 2h; heat to 190°C, continue to react for 3h, drain water through the condenser, and when no water is discharged, cool to 150°C, slowly add 140g of hot water, cool to 50°C, and adjust to a polyamide resin intermediate with a solid content of 20±1% with deionized water. Among them, the molar ratio of polyamine to dibasic acid is 1:1; the molar ratio of dimerized fatty acid to adipic acid is 0.25:1.

[0054] Step S2. is the same as S2. in Example 1.

[0055] Example 4

[0056] S1. Add 51.6g of diethylenetriamine, 58.4g of adipic acid, 56.1g of dimerized fatty acid (soybean oleic acid dimer), 11.45g of allyloxy polyoxyethylene ether (number average molecular weight 1000) and 1.6g of p-toluenesulfonic acid to a four-necked flask equipped with an electric stirrer, a constant pressure dropping funnel, a thermometer and a condenser, respectively, and add them to a reactor, pass nitrogen, stir and heat to 140°C, stir at 180 rpm, and react for 2h; heat to 190°C, continue to react for 3h, drain water through a condenser, and when no water is discharged, cool to 150°C, slowly add 140g of hot water, cool to 50°C, and adjust to a polyamide resin intermediate with a solid content of 20±1% with deionized water. Among them, the molar ratio of polyamine to dibasic acid is 1:1; the molar ratio of dimerized fatty acid to adipic acid is 0.25:1.

[0057] Step S2. is the same as S2. in Example 1.

[0058] Example 5

[0059] Step S1. is the same as S1. in Example 1.

[0060] S2. Add 300g of deionized water as a solvent to a four-necked flask equipped with an electric stirrer, a constant pressure dropping funnel, a thermometer and a condenser, turn on the stirrer, and weigh 350g of a polyamide resin intermediate having a solid content of 20% prepared in step S1, 7.5g of ethyl acrylate, 7.5g of isobutyl methacrylate, 13.33g of an aqueous solution containing 75wt% methacryloyloxyethyl trimethylammonium chloride and 5g of glycidyl methacrylate under a nitrogen atmosphere, and add them to the four-necked flask respectively, stir at 500 rpm for 30 minutes, and then reduce the stirring speed to 200 rpm; raise the temperature in the four-necked flask to 50°C, add 2.5g of a 10% aqueous sodium bisulfite solution, and stir for 10 minutes; add 5g of a 10% aqueous solution of ammonium persulfate, react for 6 hours, cool to room temperature, adjust the pH to 7.0 with acetic acid, and finally adjust to a cationic polyamide resin aqueous solution having a solid content of 15±1% with deionized water.

[0061] Example 6

[0062] Step S1. is the same as S1. in Example 1.

[0063] S2. Add 300g of deionized water as a solvent to a four-necked flask equipped with an electric stirrer, a constant pressure dropping funnel, a thermometer and a condenser, turn on the stirrer, and weigh 325g of a polyamide resin intermediate having a solid content of 20% prepared in step S1, 5g of isooctyl acrylate, 5g of tert-butyl methacrylate, 20g of an aqueous solution containing 75wt% methacryloyloxyethyl trimethylammonium chloride and 10g of glycidyl methacrylate under a nitrogen atmosphere, and add them to the four-necked flask respectively, stir at 500 rpm for 30 minutes, and then reduce the stirring speed to 200 rpm; raise the temperature in the four-necked flask to 50°C, add 2.5g of a 10% aqueous sodium bisulfite solution, and stir for 10 minutes; add 5g of a 10% aqueous ammonium persulfate solution, react for 6 hours, cool to room temperature, adjust the pH to 7.0 with acetic acid, and finally adjust to a cationic polyamide resin aqueous solution having a solid content of 15±1% with deionized water.

[0064] Example 7

[0065] S1. Add 46.43g of diethylenetriamine, 58.4g of adipic acid, 56.1g of dimer fatty acid (soybean oleic acid dimer), 11.45g of allyloxy polyoxyethylene ether (number average molecular weight 800) and 1.6g of p-toluenesulfonic acid to a four-necked flask equipped with an electric stirrer, a constant pressure dropping funnel, a thermometer and a condenser, and add them to the reactor respectively, pass nitrogen, stir and heat to 140°C, stir at 180 rpm, and react for 2h; heat to 190°C, continue to react for 3h, drain water through the condenser, and when no water is discharged, cool to 150°C, slowly add 140g of hot water, cool to 50°C, and adjust to a polyamide resin intermediate with a solid content of 20±1% with deionized water. Among them, the molar ratio of polyamine to dibasic acid is 0.9:1; the molar ratio of dimer fatty acid to adipic acid is 0.25:1.

[0066] Step S2. is the same as S2. in Example 1.

[0067] Example 8

[0068] S1. Add 51.6g of diethylenetriamine, 58.4g of adipic acid, 56.1g of dimer fatty acid (soybean oleic acid dimer), 11.45g of allyloxy polyoxyethylene ether (number average molecular weight 600) and 1.6g of p-toluenesulfonic acid to a four-necked flask equipped with an electric stirrer, a constant pressure dropping funnel, a thermometer and a condenser, and add them to the reactor respectively, pass nitrogen, stir and heat to 140°C, stir at 180 rpm, and react for 2h; heat to 190°C, continue to react for 3h, drain water through the condenser, and when no water is discharged, cool to 150°C, slowly add 140g of hot water, cool to 50°C, and adjust to a polyamide resin intermediate with a solid content of 20±1% with deionized water. Among them, the molar ratio of polyamine to dibasic acid is 1:1; the molar ratio of dimer fatty acid to adipic acid is 0.25:1.

[0069] Step S2. is the same as S2. in Example 1.

[0070] Comparative Example 1

[0071] Commercially available PAE reinforcing agent, model: CHAMPRO-W, solid content is 15%.

[0072] Comparative Example 2

[0073] S1. Add 51.6g of diethylenetriamine, 73.1g of adipic acid, 11.45g of allyloxy polyoxyethylene ether (number average molecular weight 800) and 1.6g of p-toluenesulfonic acid to a four-necked flask equipped with an electric stirrer, a constant pressure dropping funnel, a thermometer and a condenser, and add them to the reactor respectively. Pass nitrogen, stir and heat to 140°C, stir at 180 rpm, and react for 2h; heat to 190°C, continue to react for 3h, drain water through the condenser, and when no water is discharged, cool to 150°C, slowly add 140g of hot water, cool to 50°C, and adjust to a polyamide resin intermediate with a solid content of 20±1% with deionized water. Among them, the molar ratio of polyamine to dibasic acid is 1:1; no dimer fatty acid is added.

[0074] Step S2. is the same as S2. in Example 1.

[0075] Performance Testing

[0076] (1) Infrared spectroscopy analysis

[0077] The structures of the polyamide resin intermediate and the cationic polyamide resin prepared in Example 1 were characterized by FT-IR. Figure 1 and Figure 2 shown.

[0078] Depend on Figure 1 It can be seen that at wave number 3291cm -1 The stretching vibration peak of NH on amide is 1644 cm-1 The stretching vibration peak of C=O on amide (amide absorption band I) is 1549 cm -1 The combined absorption peak of NH bending vibration and CN stretching vibration on amide (amide absorption band II) indicates that an amide structure is generated in the intermediate; 2921cm -1 、2852cm -1 -CH 2 -CH stretching vibration peak, 1463cm -1 -CH 2 -Bending vibration absorption peak, 721cm -1 -CH 2 -The rocking vibration absorption peak of -CH 2 - The structure is derived from the long carbon chain in adipic acid and dimer acid molecules; 1109cm -1 There is a strong absorption peak near it, which is -CH 2 CH 2 COC stretching vibration peak in O-structure, 961cm -1 、841cm -1 -CH 2 CH 2 O-CH 2 - has an angle-variation vibration peak, and the structure is derived from allyloxy polyoxyethylene ether; thus, it can be seen that the intermediate is a polyamide structure modified by allyloxy polyoxyethylene ether.

[0079] Depend on Figure 2 It can be seen that at wave number 3277cm -1 The stretching vibration peak of NH on amide is 1649 cm -1 The stretching vibration peak of C=O on amide (amide absorption band I) is 1551 cm -1 The combined absorption peak of NH bending vibration and CN stretching vibration on amide (amide absorption band II); 2922cm -1 、2853cm -1 -CH 2 -CH stretching vibration peak, 1455cm -1 -CH 2 -Bending vibration absorption peak, 722cm -1 -CH 2 - rocking vibration absorption peak; 1117cm -1 There is a broad and strong absorption peak near it, which is -CH 2 CH 2 COC stretching vibration peak in O-structure, 950cm -1 、846cm -1 -CH 2 CH2 O-CH 2 -variable angle vibration peaks, which are consistent with the characteristic peaks of the polyamide intermediate prepared in Example 1; 1727cm -1 The carbonyl C=O stretching vibration absorption peak in the ester group indicates that the ester group is introduced, and the group comes from the acrylic acid ester polymerization unit; 1242cm -1 COC antisymmetric stretching vibration peak, 1145 cm -1 、1117cm -1 There is a strong absorption peak at , which is the characteristic peak of COC, split into two peaks, and the peak shape becomes significantly wider. This is because the glycidyl group (epoxy group) is introduced into the molecular structure, making the COC peak shape at this point wider. Figure 1 1109cm in polyamide resin intermediate -1 The COC peak at 40° is broadened, and the COC stretching vibration peak is displaced and broadened. It can be seen that the molecular structure of the cationic polyamide resin prepared in Example 1 is in line with expectations.

[0080] (2) Strength test

[0081] The wood pulp board was soaked in water for 4 hours, and then pulped with a beater and the beating degree was controlled at 370SR. 2% (relative to the absolute dry pulp) of the cationic water-based polyamide resin prepared in Examples 1 to 8 (solid content 15%) and the resins described in Comparative Examples 1 to 2 were added and stirred evenly. The paper was made into sheets with a paper sample copying machine, and the paper making weight was 50g / m 2 Then, it was pressed with a standard paper press, dried on a paper quick dryer, aged in an oven at 105°C for 15 minutes to balance the moisture, and then the dry and wet strength of the paper sample was tested with a tensile strength tester, and the wet strength retention rate was calculated, wet strength retention rate = wet tensile strength / dry tensile strength × 100%. The folding resistance of the paper was tested with a folding resistance tester. Test environment: temperature 25°C, humidity 40%. A blank control group was set up, and no reinforcing agent was added when preparing the paper. The test results are shown in Table 1.

[0082] Table 1 Measurement results of various embodiments and comparative examples

[0083]

[0084] From the data in Table 1, it can be seen that when the cationic water-based polyamide resins prepared in Examples 1 to 8 are added to paper pulp, the dry strength and wet strength are significantly improved compared with the blank sample, and the wet strength retention rate is above 15% (paper with a wet strength retention rate of more than 15% is called wet-strength paper in the industry); compared with Comparative Example 1, the cationic water-based polyamide resins prepared in Examples 1 to 8 have the same wet strength, dry strength and wet strength retention rate on paper as the commercially available reinforcing agents; compared with Comparative Examples 1 to 2 and the blank sample, the cationic water-based polyamide resins prepared in Examples 1 to 8 have a significant effect on improving the folding endurance of paper.

[0085] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A cationic water-based polyamide resin, characterized in that: The method comprises the following raw materials in parts by weight: 65 to 70 parts of a polyamide resin intermediate, 20 to 25 parts of an acrylate monomer, 10 to 15 parts of a vinyl cationic monomer, and 5 to 10 parts of a glycidyl-containing vinyl monomer; The polyamide resin intermediate is prepared from polyamine, dibasic acid and allyloxy polyoxyethylene ether, wherein the molar ratio of the polyamine to the dibasic acid is (0.9-1):1, and the added amount of the allyloxy polyoxyethylene ether is 10-20% by mass of the dibasic acid; the dibasic acid includes dimer acid and adipic acid; the molar ratio of the dimer acid to the adipic acid is (0.1-0.3):

1.

2. The polyamide resin according to claim 1, characterized in that: The number average molecular weight of the allyloxy polyoxyethylene ether is 600-1000.

3. The polyamide resin according to claim 1, characterized in that: The dimer acid is an oleic acid dimer, and the oleic acid dimer is at least one of a cottonseed oleic acid dimer, a tall oil acid dimer, a palmitoleic acid dimer, a ricinoleic acid dimer, and a soybean oleic acid dimer.

4. The polyamide resin according to claim 1, characterized in that: The acrylic acid ester monomer is at least one of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isooctyl (meth)acrylate, and lauryl (meth)acrylate.

5. The polyamide resin according to claim 1, characterized in that: The polyamine is at least one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine and polyethylenepolyamine.

6. The polyamide resin according to claim 1, characterized in that: The vinyl cationic monomer is at least one of (meth)acryloyloxyethyl trimethyl ammonium chloride, (meth)acryloyloxypropyl trimethyl ammonium chloride, dimethyl diallyl ammonium chloride, (meth)acryloyloxyethyl dimethyl benzyl ammonium chloride, and (meth)acrylamidopropyl trimethyl ammonium chloride.

7. The polyamide resin according to claim 1, characterized in that: The glycidyl group-containing vinyl monomer is at least one of allyl glycidyl ether, glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and epoxycyclohexylmethyl (meth)acrylate.

8. The polyamide resin according to claim 1, characterized in that: The preparation method of the polyamide resin comprises: mixing a polyamide resin intermediate, an acrylate monomer, a vinyl cationic monomer and a glycidyl-containing vinyl monomer, and then copolymerizing the mixture to obtain the polyamide resin.

9. The polyamide resin according to claim 8, characterized in that: During copolymerization, an initiator needs to be added, and the initiator includes an oxidizing agent and a reducing agent.

10. Use of the polyamide resin according to any one of claims 1 to 9 in the preparation of a paper strengthening agent.

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