Crosslinked polymer of unsaturated carboxylic acid, and preparation method therefor and use thereof

Abstract

Provided in the present invention are a crosslinked polymer of an unsaturated carboxylic acid, and a preparation method therefor and the use thereof. The method comprises: subjecting an unsaturated carboxylic acid product to a polymerization reaction under the action of a crosslinking agent and a radical initiator, wherein the unsaturated carboxylic acid product comprises an unsaturated carboxylic acid and a multimer formed by means of the self-polymerization of the unsaturated carboxylic acid, the content of the multimer in the unsaturated carboxylic acid product being 0.02-1 wt%. The crosslinked polymer of an unsaturated carboxylic acid in an embodiment of the present invention is used in personal care products, and can improve the viscosity and transparency of the product.

Description

A cross-linked polymer of unsaturated carboxylic acid and its preparation method and application Technical Field

[0001] The present invention relates to the field of polymer material preparation, and in particular to a cross-linked polymer of unsaturated carboxylic acid, a preparation method and application thereof. Background Art

[0002] With China's aging population and growing awareness of the increasing demand for personal care products, demand for powdered polyacrylic acid thickeners, widely used in this field, has continued to rise year after year. Especially during the COVID-19 pandemic of 2020, hand sanitizers, which can be seen as an effective antiseptic method for isolating viruses and protecting people, have seen significant market acceptance. The thickening agent used in hand sanitizers is carbomer.

[0003] Traditional thickeners for aqueous systems are mainly water-soluble polymers with completely hydrophilic molecular structures and no hydrophobic structures, such as cellulose (HEC) and acrylic thickeners (ASE). These thickeners achieve the purpose of thickening the aqueous phase system by forming hydrogen bonds with water molecules in the system.

[0004] Polyurethane thickeners, a class of thickeners developed in the 1980s, are water-soluble oligomers composed of hydrophilic polymer chains and hydrophobic groups. The hydrophilic polymer chains are linked to the hydrophobic groups via covalent bonds, forming an associative thickener. In aqueous systems, the hydrophilic portion of these thickeners forms hydrogen bonds with water, ensuring the dissolution or dispersion of the thickener molecules. In aqueous systems, the hydrophobic portion bridges the hydrophobic association with emulsions, solid particles, and micelles in the aqueous system, forming a three-dimensional network structure and thickening the aqueous system. This type of thickener can be divided into hydrophobic alkali-swellable thickeners (HASE), polyurethane associative thickeners (HEUR), and other associative thickeners. Aqueous systems incorporating HEUR exhibit superior leveling properties, excellent film buildup, and high gloss, leading to their widespread application.

[0005] Carbomer is a homopolymer or copolymer of acrylic acid and a very important rheology modifier. Neutralized carbomer is an excellent gel matrix with excellent thickening, suspending and emulsifying effects. It has good compatibility with other excipients and is mostly used in adhesives, pharmaceutical excipients and nutritional additives, especially in lotions, creams and gels.

[0006] CN103755861 discloses a carbomer that is primarily prepared by polymerizing acrylic acid in a mixed solvent of water and tert-butyl alcohol using a water-soluble initiator to obtain a powdered carbomer. This method provides a more inclusive, green, and friendly aqueous reaction system by adding tert-butyl alcohol, resulting in high-quality carbomer. However, this type of carbomer product has certain limitations in particle size, and after thickening, the product exhibits a glassy state, resulting in poor transparency and suspension properties.

[0007] CN101633718A discloses a comb-shaped polyurethane associative thickener, its preparation method, and its application. This patent synthesizes a chain extender containing long hydrophobic chains. By introducing the chain extender into the thickener molecule to increase the hydrophobic segments, the thickening effect is improved. However, the synthesis process of this chain extender is relatively complex.

[0008] EP1765900 describes thickeners for aqueous preparations based on nonionic water-dispersible or water-soluble polyurethanes with a special structure. The special structures of these polymers are achieved by the presence of allophanate bonds produced by using excessive isocyanates. As component (a), a hydrophilic polyol with at least 2-OH groups can be used, which can additionally contain ether groups. This water-soluble polyurethane thickener is still lacking in terms of aqueous thickening, and the product does not have a suspension effect in the formulation system.

[0009] CN105037606 discloses a carbomer resin comprising the following raw materials by weight: 10-110 parts of a carboxylic acid monomer, 0.01-1.5 parts of a cross-linking agent, 10-1000 parts of water, and 0.01-5.0 parts of other additives. The carboxylic acid monomer is a carboxylic acid monomer having an olefinic double bond; the cross-linking agent is a monomer having two or more double bonds; and the other additives are one or more of sodium fatty alcohol benzenesulfonate, sodium fatty alcohol sulfate, fatty alcohol polyoxyethylene ether and its sulfates, hydrogen peroxide, persulfate, EDTA and its salts. This carbomer resin has excellent thickening efficiency, but still fails to meet performance requirements in terms of suspended particles.

[0010] CN 108299608 describes an alkali-swellable associative thickener. This alkali-swellable associative thickener is made from the following components in percentage by weight: 10-15% methacrylic acid, 15-20% ethyl acrylate, 0.1-5% polyurea crosslinking monomer, 0.1-3% hydrophobic associating monomer, 0.5-2% anionic surfactant, 0.2-0.1% nonionic surfactant, and 0.1-1% initiator. It is produced by emulsion polymerization. This thickener is not easily affected by residual solvents in the aqueous system, additives such as dispersants, or the ion concentration of the system, and exhibits excellent stability.

[0011] CN103483491 discloses a method for preparing a powdered carbomer. The method involves polymerizing acrylic acid using an oil-soluble initiator in a mixed solvent of ethyl acetate and cyclohexane to produce a white powder of polyacrylic acid, which has a good thickening effect in aqueous phases and in the personal care field. However, the suspension performance of the carbomer formulation system still fails to meet performance requirements.

[0012] US3912921 discloses a copolymer of acrylic acid and acrylic ester (alkyl group containing 10-30 carbon atoms). The copolymer is obtained by free radical polymerization in a solvent system to obtain a mixture of the polymer and the solvent. Finally, a powdered acrylic ester copolymer is obtained through separation, washing, drying and other processes. The powdered acrylic ester copolymer can achieve a good thickening effect in water, but its transparency and suspension effect are poor.

[0013] In summary, existing cross-linked polymers of unsaturated carboxylic acids still have problems such as poor thickening efficiency, poor suspension performance, poor transparency, or complicated process routes.

[0014] Summary of the Invention

[0015] One of the objectives of the present invention is to address at least one problem of the prior art and provide a method for preparing a cross-linked polymer of an unsaturated carboxylic acid. In the method, an unsaturated carboxylic acid is polymerized in a solvent in the presence of a cross-linking agent and a free radical initiator to obtain a cross-linked polymer of an unsaturated carboxylic acid. In the method, the unsaturated carboxylic acid feed contains 0.02-1 wt% of polymer, preferably 0.2-1 wt% of polymer; and the mass fraction of active substance in the obtained cross-linked polymer of unsaturated carboxylic acid product is ≥95 wt%, preferably ≥97 wt%. The active substance is a product generated by polymerization of the raw unsaturated carboxylic acid, i.e., the cross-linked polymer of unsaturated carboxylic acid.

[0016] One embodiment of the present invention effectively controls the polymerization rate of unsaturated carboxylic acid monomers by controlling the content of polymers in unsaturated carboxylic acids, thereby obtaining a polymer with an ideal molecular weight (or viscosity). This also prevents the solid accumulation of the polymer from being too dense, thereby affecting the transparency and suspension properties of the product (or formulation system) to which it is applied. The cross-linked polymer of the unsaturated carboxylic acid can establish a three-dimensional network structure in the application system, constraining the movement of free molecules in the system and comprehensively improving the viscosity and transparency of the product. Furthermore, adding a small amount of the cross-linked polymer of the unsaturated carboxylic acid to a formulation system (e.g., personal care products) can achieve the desired viscosity.

[0017] One embodiment of the present invention provides a method for preparing a cross-linked polymer of an unsaturated carboxylic acid, comprising: subjecting an unsaturated carboxylic acid product to a polymerization reaction under the action of a cross-linking agent and a free radical initiator; wherein the unsaturated carboxylic acid product comprises an unsaturated carboxylic acid and a polymer formed by self-polymerization of the unsaturated carboxylic acid, and the content of the polymer in the unsaturated carboxylic acid product is 0.02-1 wt%.

[0018] In one embodiment of the present invention, the content of the polymer in the unsaturated carboxylic acid product can be 0.02-1wt%, preferably 0.2-1wt%, for example 0.23wt%, 0.25wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.55wt%, 0.6wt%, 0.7wt%, 0.76wt%, 0.8wt%, 0.9wt%, 0.96wt%.

[0019] The inventors discovered that during actual production and use, unsaturated carboxylic acids inevitably undergo self-polymerization, forming dimers, tetramers, and other polymers of the unsaturated carboxylic acid. Specifically, the polymer content in the unsaturated carboxylic acid product slowly increases with storage time. Furthermore, the inventors surprisingly discovered a clear correlation between the polymer content in the unsaturated carboxylic acid product used to prepare the cross-linked polymer and the aforementioned technical problems of the prior art. Furthermore, through extensive experimental studies, they determined that when the mass content of the polymer in the unsaturated carboxylic acid product is 0.02-1%, the polymerization rate of the unsaturated carboxylic acid monomer can be effectively controlled to produce a cross-linked polymer with an ideal viscosity. At the same time, the solid accumulation of the polymer is not too dense, thereby affecting the transparency and suspension properties of the product to which it is applied, thereby comprehensively improving the viscosity and transparency of the product. Furthermore, the ideal viscosity can be achieved by adding a small amount of cross-linked polymer of unsaturated carboxylic acid to the formulation system. When the polymer content in an unsaturated carboxylic acid product exceeds 1% by weight, the polymer can interfere with the polymerization reaction, resulting in a decrease in the degree of polymerization (DP), a decrease in polymer molecular weight, an increase in oligomer content, and low viscosity, reduced suspension properties, and a yellowish appearance in the final product (e.g., personal care products), all of which affect product quality. When the polymer content in an unsaturated carboxylic acid product is less than 0.02% by weight, the molecular weight increases too rapidly during polymerization, leading to dense polymer accumulation. This prevents the product from fully swelling and establishing effective viscosity when used in low-addition systems.

[0020] In one embodiment of the present invention, the cross-linked polymer of unsaturated carboxylic acid is a substance having a thickening effect. When preparing the cross-linked polymer of unsaturated carboxylic acid, an emulsifier or other component may be optionally added as needed.

[0021] In one embodiment of the present invention, the unsaturated carboxylic acid includes C3-C6 carboxylic acids containing double bonds, preferably one or more of acrylic acid, maleic acid, itaconic acid, fumaric acid, methacrylic acid, crotonic acid, and aconitic acid.

[0022] In one embodiment of the present invention, the polymer is a polymerization product of two or more unsaturated carboxylic acids.

[0023] In one embodiment of the present invention, the crosslinking agent comprises a substance containing at least two unsaturated carbon-carbon double bonds, preferably a multifunctional acrylate containing at least two polymerizable ethylenically unsaturated double bonds and / or a polyalkenyl polyether containing at least two polymerizable ethylenically unsaturated double bonds; preferably, the multifunctional acrylate and polyalkenyl polyether are obtained by esterification or etherification of a linear or branched polyol; preferably, the amount of the crosslinking agent used is 0.01-5%, preferably 0.1-3%, and more preferably 0.5-2% of the total mass of the active polymer (i.e., the crosslinked polymer of the unsaturated carboxylic acid). As is well known in the art, the above crosslinking agent is a commonly used crosslinking agent prepared by methods commonly used in the art.

[0024] In one embodiment of the present invention, the crosslinking agent includes one or more of trimethylolpropane diallyl ether, pentaerythritol triallyl ether, 1,6-hexanediol diacrylate, and triethylene glycol diacrylate.

[0025] In one embodiment of the present invention, the free radical initiator is one or more of an organic peroxide compound, an azo compound, an inorganic persulfate compound, and hydrogen peroxide, preferably one or more of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, lauroyl peroxide, ammonium persulfate, sodium persulfate, and hydrogen peroxide. As is well known in the art, the above-mentioned initiators are commonly used in the art.

[0026] In one embodiment of the present invention, the polymerization reaction of the unsaturated carboxylic acid product is carried out in a solvent, wherein the solvent comprises an alkane and / or an alkyl acetate, preferably C1-C 10 The alkane and / or alkyl acetate containing a C1 to C4 alkyl group. Further, the alkane may contain 6 to 10 carbon atoms.

[0027] In one embodiment of the present invention, the alkane includes one or more of n-hexane, cyclohexane, n-heptane, cycloheptane, and n-decane.

[0028] In one embodiment of the present invention, the alkyl acetate includes one or more of ethyl acetate, butyl acetate, ethyl propionate, and butyl propionate.

[0029] It is well known in the art that the above solvents are commonly used solvents in this field.

[0030] In one embodiment of the present invention, the preparation method comprises the following steps:

[0031] S1: adding reaction components (unsaturated carboxylic acid product) to a solvent and mixing to obtain a reaction system;

[0032] S2: adding a free radical initiator to the reaction system to carry out a polymerization reaction; cooling the system after the reaction, filtering and separating, washing and drying to obtain a cross-linked polymer product of unsaturated carboxylic acid.

[0033] In one embodiment of the present invention, a dispersant is optionally added in step S1. Preferably, the dispersant is a nonionic emulsifier with an HLB value of 2-6.5. The nonionic emulsifier is preferably one or more of propylene glycol monostearate (e.g., HLB value of 3.4), sorbitan stearate (e.g., HLB value of 4.7), sorbitan tristearate (e.g., HLB value of 2.1), and diethylene glycol monolaurate (e.g., HLB value of 6.1). As is well known in the art, the above dispersants are commonly used in the art.

[0034] In one embodiment of the present invention, the reaction system in step S2 is heated to 50-80° C. for reaction.

[0035] In one embodiment of the present invention, the reaction temperature of step S2 can be 54°C, 58°C, 62°C, 66°C or 78°C.

[0036] As is well known in the art, the steps included in the above preparation method are common steps for preparing cross-linked polymers of unsaturated carboxylic acids in the art.

[0037] Another object of the present invention is to provide a cross-linked polymer of unsaturated carboxylic acid.

[0038] One embodiment of the present invention provides a cross-linked polymer of an unsaturated carboxylic acid or a cross-linked polymer product of an unsaturated carboxylic acid, which is prepared by the above method.

[0039] One embodiment of the present invention provides a cross-linked polymer product of an unsaturated carboxylic acid, prepared using the above-described preparation method. In a thickening efficiency test method, the viscosity of a system (or product) containing the cross-linked polymer at a viscometer speed of 20 rpm is 40,000-55,000 cp; the transparency of the system (or product) containing the cross-linked polymer is ≥90%; and the suspension properties of the system (or product) containing the cross-linked polymer remain stable for 10-15 days. The viscosity at 20 rpm in the thickening efficiency test method is a commonly used indicator in the art.

[0040] Another object of the present invention is to provide a use of a cross-linked polymer of an unsaturated carboxylic acid.

[0041] One embodiment of the present invention provides a cross-linked polymer of an unsaturated carboxylic acid or a use of a cross-linked polymer product of an unsaturated carboxylic acid, wherein the polymer product is prepared using the above-mentioned preparation method, and the polymer is used in the field of personal care (e.g., personal care products), preferably in a transparent gel medium.

[0042] In one embodiment of the present invention, the personal care product or formulation system may include one or more of shampoo, shower gel, and facial mask.

[0043] In one embodiment of the present invention, the crosslinked polymer of an unsaturated carboxylic acid or the crosslinked polymer product of an unsaturated carboxylic acid can be used as a thickener for personal care products.

[0044] One embodiment of the present invention provides a personal care product comprising the above-mentioned cross-linked polymer of unsaturated carboxylic acid or a cross-linked polymer product of unsaturated carboxylic acid.

[0045] In one embodiment of the present invention, the main structure of the cross-linked polymer of unsaturated carboxylic acid is polyacrylic acid, polymethacrylic acid, or polyacrylic acid and polymethacrylic acid. When the polymer is added to an aqueous system, with the addition of an alkaline substance, the carboxylic acid on the poly(meth)acrylic acid main chain becomes a carboxylate group. Since the carboxylate group is negatively charged, the charge repulsion causes the polymer main chain to extend and fill the space in the system. At the same time, the carboxylate group forms hydrogen bonds with water, greatly restricting the free movement of water molecules, thereby increasing the viscosity of the entire system.

[0046] The method for preparing a cross-linked polymer of an unsaturated carboxylic acid according to one embodiment of the present invention can effectively control the polymerization rate of the unsaturated carboxylic acid product to obtain a polymer with an ideal viscosity.

[0047] The cross-linked polymer of unsaturated carboxylic acid according to one embodiment of the present invention has a solid accumulation that is not too dense to affect the transparency and suspension performance of the applied product (formulation system); and a small amount of the polymer can be added to the formulation system to obtain an ideal viscosity.

[0048] The cross-linked polymer of unsaturated carboxylic acid according to one embodiment of the present invention is used as a thickener for personal care products, can produce good thickening efficiency, does not affect the transparency of the product, and can also make the product have excellent storage stability. DETAILED DESCRIPTION

[0049] In order to better implement the present invention, the present invention is further described below with reference to the embodiments, but the embodiments are not intended to limit the present invention.

[0050] The main raw materials and information used in the examples are shown in Table 1 below:

[0051] Table 1

[0052] The main equipment information used in this embodiment is shown in Table 2 below:

[0053] Table 2

[0054] The polymer test in unsaturated carboxylic acid products is carried out in accordance with the national standard GBT 17529.1-2008. The chromatographic column selected is a capillary column.

[0055] The specific test method for polymers in unsaturated carboxylic acid products is as follows:

[0056] 1) Check before starting the machine: Check whether the power supply of the instrument host and the matching injector are normal.

[0057] 2) Wait for the instrument self-test to complete. Open the OpenLAB software, select [GC-82 (WHNB-SB-7126)], and click [Start]. Load the test method, click "Control" > "Download Method to Instrument," and wait for the instrument to stabilize. Also, check the instrument's readiness status on the main interface and verify that the baseline is stable and normal.

[0058] 3) Confirm the method parameters.

[0059] 4) Shake the sample to be tested. Weigh 10 g of sample and 0.01 g (use a dedicated pipette to transfer 100 μl) of dimethyl sebacate (internal standard) into a 50 ml stoppered Erlenmeyer flask and shake well. Transfer 1.5 ml of sample to a 2 ml gas phase vial, label it, and place it in the sample tray of the autosampler.

[0060] 5) Open the test method sequence and edit the information such as [number of repetitions, sample bottle, sample ID, volume, sample ID, method, file name, sample mass, multiplication factor].

[0061] 6) Confirm the sequence information and click [Run Sequence].

[0062] 7) Modify the sample information in [Sequence Run]: [Result Path] is saved in the folder of the current month, and [Result Name] is entered <d> <s>Sample number, click Start. Observe the normal operation of the instrument and wait for the instrument to finish running.

[0063] 8) Open OpenLAB, click [Offline Start] on the corresponding instrument, open [Result Set], and call the spectrum in the folder of the current month according to the sample information.

[0064] 9) After the integration is completed, click [Analysis], click [Report], and then click [Method Report] to open the report results of the spectrum.

[0065] 10) The quantitative method is the internal standard percentage method, the value is expressed in %, and the result is rounded to two decimal places.

[0066] The test methods for thickening efficiency, transparency and suspension performance in this article are as follows:

[0067] Thickening efficiency test method: Add 208.5g of deionized water to a 300ml, 8cm diameter plastic bottle, then add 1.4g of the prepared cross-linked polymer of unsaturated carboxylic acid. Let it sit for 8 hours to allow it to fully absorb and swell. Add a stirring paddle, start stirring, and slowly add 18wt% sodium hydroxide aqueous solution dropwise. Stir at 800rpm for 40-60min, and adjust the pH value to 7.5±0.2. Place in a constant temperature water bath at 25±1℃ and let it stand for 8 hours until it stabilizes. Use a Brookfield DV-II digital viscometer to measure the viscosity at 20rpm.

[0068] Transparency Test Method: Prepare a sample solution of a cross-linked polymer of an unsaturated carboxylic acid using the same method as described for the thickening efficiency test. Place an appropriate amount of the stabilized sample solution into a centrifuge tube. Place the tube in a centrifuge at 5000 rpm for 10 minutes. After centrifugation, carefully remove the sample and place it into a cuvette (to avoid introducing bubbles). Place the cuvette in a spectrophotometer for transparency measurement.

[0069] Suspension test method: The suspension test was performed using the formulation shown in Table 3 below.

[0070] Table 3

[0071] 1) Weigh 38.3 g of deionized water into a 300 ml straight bottle, place it under a mechanical stirrer, and position a four-bladed propeller as close to the bottom of the bottle as possible. Turn on the mechanical stirrer, adjust the speed to 200 rpm, and begin stirring.

[0072] 2) Weigh 0.6 g of the cross-linked polymer sample of unsaturated carboxylic acid and slowly add it to the straight bottle near the bottle wall. The addition time is controlled to be 45-60 seconds. After the addition is complete, adjust the speed to 800 rpm and stir for 30 minutes.

[0073] 3) After stirring at 800 rpm, adjust the speed to 200 rpm and stir the mixture in the flask for 15 minutes until the liquid at the bottom becomes clear.

[0074] 4) adjusting the speed to 400 rpm, raising the temperature of the mixture in the straight bottle to 85° C., and slowly adding 146 g of sodium laureth sulfate and 12 g of cocamidopropyl betaine to the bottle and mixing well;

[0075] 5) Adjust the temperature of the mixture in the flask to 60°C, slowly add 0.1 g of mica, and stir until no mica aggregates are observed;

[0076] 6) Cool the mixture in the bottle to room temperature, slowly add 1.0 g of phenoxyethanol and 1.0 g of fragrance, and stir for 30 minutes to mix thoroughly.

[0077] 7) Adjust the speed to 500 rpm, add 1.0 g of sodium chloride powder to the straight bottle, and stir for 20 minutes to mix well;

[0078] 8) Maintaining the rotation speed, slowly add 18 wt % sodium hydroxide solution into the straight bottle to adjust the pH value of the system to between 5.3 and 5.8 to complete the preparation of the suspended test solution.

[0079] 9) Pour the obtained test solution into three transparent glass bottles, place them in a 45°C oven, and observe the mica sedimentation and water separation.

[0080] Example 1

[0081] The polymer content in the unsaturated carboxylic acid product used in this example was measured to be 0.4 wt %.

[0082] The following steps are used to prepare the cross-linked polymer product C1 of unsaturated carboxylic acid:

[0083] 250 g of cyclohexane and 250 g of ethyl acetate were added to a 1500 ml four-necked flask equipped with a mechanical stirrer, and 0.4 g of sorbitan stearate was added. The mixture was mixed evenly and nitrogen was passed through for more than 30 min to replace the oxygen content in the system to 1 × 10 -7 mg / L or less;

[0084] Add 99.2 g of acrylic acid product and 0.8 g of trimethylolpropane diallyl ether into a four-necked flask, mix well, and continue to pass nitrogen to replace oxygen;

[0085] The reaction temperature was raised to 78°C, and 0.6 g of benzoyl peroxide was added to the four-necked flask (to initiate the reaction) to start the polymerization reaction, which was continued for 5 h until the reaction was complete.

[0086] Maintaining the reaction temperature at 78°C, a mixed solution of 12.5 g of ethyl acetate, 12.5 g of cyclohexane, and 0.2 g of benzoyl peroxide (to remove residual monomers) was added to a four-necked flask, and the mixture was allowed to react for another 2 h to remove residual monomers. After the reaction was complete, the system was cooled to room temperature to obtain a suspension solution of a cross-linked polymer of an unsaturated carboxylic acid.

[0087] The obtained suspension was filtered under negative pressure to obtain a white precipitate, which was then washed and filtered three times with a mixed solvent (cyclohexane:ethyl acetate = 1:1 mass ratio) to obtain a white polymer containing the solvent;

[0088] The solvent-containing white polymer was placed in a vacuum oven, maintained at 90° C., and dried under negative pressure for 24 hours to obtain a cross-linked polymer product C1 of unsaturated carboxylic acid. C1 was tested according to the aforementioned method, and the results are shown in Table 4.

[0089] Example 2

[0090] The polymer content in the unsaturated carboxylic acid product used in this example was measured to be 0.23 wt %.

[0091] The following steps are used to prepare the cross-linked polymer product C2 of unsaturated carboxylic acid:

[0092] 170 g of cyclohexane and 340 g of ethyl acetate were added to a 1500 ml four-necked flask equipped with a mechanical stirrer, and 0.2 g of propylene glycol monostearate was added. The mixture was mixed evenly and nitrogen was passed through for more than 30 min to replace the oxygen content in the system to 1 × 10 -7 mg / L or less;

[0093] 74.4 g of methacrylic acid product, 25 g of crotonic acid product and 0.6 g of pentaerythritol triallyl ether were added to a four-necked flask, mixed evenly, and nitrogen was continuously passed through to replace oxygen;

[0094] The reaction temperature was raised to 62°C, and 0.22 g of lauroyl peroxide was added to the four-necked flask to initiate the polymerization reaction, which was continued for 7 h until the reaction was complete.

[0095] Maintaining the reaction temperature at 62°C, a mixed solution of 36 g of ethyl acetate, 18 g of cyclohexane, and 0.2 g of dodecyl peroxide was added to the four-necked flask and allowed to react for another 2 h to remove residual monomers. After the reaction was complete, the system was cooled to room temperature to obtain a suspension solution of a cross-linked polymer of an unsaturated carboxylic acid.

[0096] The obtained suspension was filtered under negative pressure to obtain a white precipitate, which was then washed and filtered three times with a mixed solvent (cyclohexane:ethyl acetate = 1:2 by mass) to obtain a white polymer containing the solvent;

[0097] The solvent-containing white polymer was placed in a vacuum oven, maintained at 90° C., and dried under negative pressure for 24 hours to obtain a cross-linked polymer product C2 of unsaturated carboxylic acid. C2 was tested according to the aforementioned method, and the results are shown in Table 4.

[0098] Example 3

[0099] The polymer content in the unsaturated carboxylic acid product used in this example was measured to be 0.76 wt %.

[0100] The following steps are used to prepare the cross-linked polymer product C3 of unsaturated carboxylic acid:

[0101] 290 g of cyclohexane and 145 g of ethyl acetate were added to a 1500 ml four-necked flask equipped with a mechanical stirrer, and 0.9 g of sorbitan tristearate was added. The mixture was mixed evenly and nitrogen was passed through for more than 30 min to replace the oxygen content in the system to 1 × 10 -7 mg / L or less;

[0102] 98.8 g of methacrylic acid product and 1.2 g of 1,6-hexanediol diacrylate were added to a four-necked flask, mixed evenly, and nitrogen was continuously passed through to replace oxygen;

[0103] The reaction temperature was raised to 54°C, and 0.68 g of azobisisobutyronitrile was added to the four-necked flask to initiate the polymerization reaction, which was continued for 9 h until the reaction was complete.

[0104] Maintaining the reaction temperature at 54°C, a mixed solution of 10 g of ethyl acetate, 20 g of cyclohexane, and 0.2 g of azobisisobutyronitrile was added to a four-necked flask and allowed to react for another 2 hours to remove residual monomers. After the reaction was complete, the system was cooled to room temperature to obtain a suspension solution of a cross-linked polymer of an unsaturated carboxylic acid.

[0105] The obtained suspension was filtered under negative pressure to obtain a white precipitate, which was then washed and filtered three times with a mixed solvent (cyclohexane:ethyl acetate = 2:1 by mass) to obtain a solvent-containing white polymer.

[0106] The solvent-containing white polymer was placed in a vacuum oven, maintained at 90° C., and dried under negative pressure for 24 hours to obtain a cross-linked polymer product C3 of unsaturated carboxylic acid. C3 was tested according to the aforementioned method, and the results are shown in Table 4.

[0107] Example 4

[0108] The polymer content in the unsaturated carboxylic acid product used in this example was measured to be 0.96 wt %.

[0109] The following steps are used to prepare the cross-linked polymer product C4 of unsaturated carboxylic acid:

[0110] 188g of cyclohexane and 282g of ethyl acetate were added to a 1500ml four-necked flask equipped with a mechanical stirrer, and 0.7g of diethylene glycol monolaurate was added. The mixture was mixed evenly and nitrogen was passed through for more than 30min to replace the oxygen content in the system to 1×10 -7 mg / L or less;

[0111] 98.2 g of acrylic acid product, 0.8 g of pentaerythritol triallyl ether and 1.0 g of triethylene glycol diacrylate were added to a four-necked flask, mixed evenly, and nitrogen was continuously passed through to replace oxygen;

[0112] The reaction temperature was raised to 58°C, and 0.7 g of benzoyl peroxide was added to the four-necked flask to initiate the polymerization reaction, which was continued for 8 h until the reaction was complete.

[0113] Maintaining the reaction temperature at 58°C, a mixed solution of 15 g of ethyl acetate, 10 g of cyclohexane, and 0.2 g of benzoyl peroxide was added to the four-necked flask and allowed to react for another 2 h to remove residual monomers. After the reaction was complete, the system was cooled to room temperature to obtain a suspension solution of a cross-linked polymer of an unsaturated carboxylic acid.

[0114] The obtained suspension was filtered under negative pressure to obtain a white precipitate, which was then washed and filtered three times with a mixed solvent (cyclohexane:ethyl acetate = 1:1.5 mass ratio) to obtain a white polymer containing the solvent;

[0115] The solvent-containing white polymer was placed in a vacuum oven, maintained at 90° C., and dried under negative pressure for 24 hours to obtain a cross-linked polymer product C4 of unsaturated carboxylic acid. C4 was tested according to the aforementioned method, and the results are shown in Table 4.

[0116] Example 5

[0117] The polymer content in the unsaturated carboxylic acid product used in this example was measured to be 0.55 wt %.

[0118] The following steps are used to prepare the cross-linked polymer product C5 of unsaturated carboxylic acid:

[0119] 290 g of cyclohexane and 193.3 g of ethyl acetate were added to a 1500 ml four-necked flask equipped with a mechanical stirrer, and 0.6 g of propylene glycol monostearate was added. The mixture was mixed evenly and nitrogen was passed through for more than 30 min to replace the oxygen content in the system to 1 × 10 -7 mg / L or less;

[0120] 98.4 g of acrylic acid product, 0.8 g of pentaerythritol triallyl ether and 0.8 g of 1,6-hexanediol diacrylate were added to a four-necked flask, mixed evenly, and nitrogen was continuously passed through to replace oxygen;

[0121] The reaction temperature was raised to 66°C, and 0.45 g of benzoyl peroxide was added to the four-necked flask to initiate the polymerization reaction, which was continued for 6 h until the reaction was complete.

[0122] Maintaining the reaction temperature at 66°C, a mixed solution of 10 g of ethyl acetate, 15 g of cyclohexane, and 0.2 g of dodecyl peroxide was added to the four-necked flask and allowed to react for another 2 h to remove residual monomers. After the reaction was complete, the system was cooled to room temperature to obtain a suspension solution of a cross-linked polymer of an unsaturated carboxylic acid.

[0123] The obtained suspension was filtered under negative pressure to obtain a white precipitate, which was then washed and filtered three times with a mixed solvent (cyclohexane:ethyl acetate = 1.5:1 mass ratio) to obtain a white polymer containing the solvent;

[0124] The solvent-containing white polymer was placed in a vacuum oven, maintained at 90° C., and dried under negative pressure for 24 hours to obtain a cross-linked polymer product C5 of unsaturated carboxylic acid. C5 was tested according to the aforementioned method, and the results are shown in Table 4.

[0125] Comparative Example 1

[0126] A cross-linked polymer product D1 of an unsaturated carboxylic acid was prepared using a method substantially identical to that of Example 5, differing only in that the polymer content of the unsaturated carboxylic acid product used was 0.016 wt %. The cross-linked polymer product D1 was tested using the aforementioned method, and the results are shown in Table 4.

[0127] Comparative Example 2

[0128] A cross-linked polymer product D2 of an unsaturated carboxylic acid was prepared using a method substantially identical to that of Example 5, differing only in that the polymer content of the unsaturated carboxylic acid product used was 1.2 wt %. The cross-linked polymer product D2 was tested using the aforementioned method, and the results are shown in Table 4.

[0129] Table 4

[0130] The following application examples 1-4 are applications of the cross-linked polymer products C1-C5 of unsaturated carboxylic acids of Examples 1-5 and the polymer products D1 and D2 of Comparative Examples 1 and 2. The test methods involved are as follows:

[0131] 1) Thickening efficiency: Add the same amount of thickener to the system and measure the viscosity of the system at 20 rpm at 20°C (unit: cp);

[0132] 2) Transparency test: measured using a Unicolor 7200 spectrophotometer, with 100% being optimal;

[0133] 3) Storage stability: The product was placed in a 50°C oven for 14 days and the changes in the appearance of the system were observed. The evaluation criteria were: good storage stability was scored as 5 points, and poor storage stability was scored as 1 point.

[0134] 4) Suspension test: For pearlescent shampoo formulas, place the formulated product in a 45°C oven. Observe the degree of water separation and the amount of sedimentation at the bottom of the bottle every other day. Record the number of days when obvious sedimentation occurs. The more days, the better.

[0135] 5) Skin Feel Test: 20 female subjects aged 20-45 years who are accustomed to using cosmetics were selected. The subjects used the pearlescent shampoo formulated with polymer products C1-C5 of the present invention and polymer products D1 and D2 of the comparative examples to sensory evaluate the freshness of the products. The scoring criteria are as follows:

[0136] No greasy feeling, very satisfactory freshness, 9-10 points,

[0137] Slightly greasy feeling is 7-8 points.

[0138] The greasy feeling is 4-6 points.

[0139] If there is a noticeable greasy feeling, it is 1-3 points.

[0140] A stronger sense of greasiness is scored as 0 points.

[0141] Calculate the average score.

[0142] 6) Moisturizing Test: In a 40-50% humidity environment, the subjects cleansed their faces and used toner and lotion, followed by applying products prepared from polymer products C1-C5 of the present invention and polymer products D1 and D2 of the comparative examples. After 30 minutes, the moisture content of the applied area was measured using a skin moisture tester, and the data was recorded.

[0143] Application Example 1

[0144] The raw materials used in preparing pearlescent shampoo are as follows:

[0145] Table 5

[0146] The preparation steps of pearlescent shampoo are as follows:

[0147] 1) Add 30g of deionized water to a 250ml beaker and heat it to 85°C;

[0148] 2) Add 60g of sodium laureth sulfate and 0.3g of cocamidopropyl betaine to a beaker while stirring and mix well;

[0149] 3) Cool the mixture in the beaker to 60° C., add 0.5 g of polyquaternium-10 and 0.02 g of mica while stirring, and mix well;

[0150] 4) Cooling the mixture in the beaker to room temperature while stirring, adding 0.02 g of BHT, 0.02 g of disodium EDTA, 0.5 g of phenoxyethanol, and 0.35 g of a cross-linked polymer of unsaturated carboxylic acid to the mixture in the beaker and mixing well;

[0151] 5) Homogenize the mixture in the beaker with a homogenizer at 20,000 rpm for 30 minutes to ensure a more uniform mixture.

[0152] 6) Slowly add 18 wt % sodium hydroxide solution to the mixed solution in the beaker, change the speed of the homogenizer as the viscosity increases to ensure uniform neutralization, and add 4.18 g of deionized water to adjust the pH value of the mixed solution to 5.2-5.8.

[0153] The polymer products C1-C5 of Examples 1-5 and the polymer products D1 and D2 of the comparative example were used as cross-linked polymer products of unsaturated carboxylic acids, and pearlescent shampoo was prepared and related performance tested according to the above steps. The results are shown in the following table, where C1 represents the pearlescent shampoo containing product C1, and the same applies to the others.

[0154] Table 6

[0155] As can be seen from the above table, the pearlescent shampoo prepared using the cross-linked polymer products C1-C5 of unsaturated carboxylic acids according to the embodiments of the present invention as thickeners has excellent viscosity, good stability, good skin feel and suspension effect, and can meet the actual needs of pearlescent shampoo.

[0156] Application Example 2

[0157] The ingredients used to prepare the transparent body wash are as follows:

[0158] Table 7

[0159] The preparation steps of shower gel are:

[0160] 1) In a 250 ml beaker, dissolve 4.0 g of potassium hydroxide in 18 g of deionized water and heat to 85°C to obtain mixture A.

[0161] 2) In a 250 ml beaker, add 8.0 g of glycerol and 0.4 g of the cross-linked polymer product of unsaturated carboxylic acid to 30 g of deionized water and mix well to obtain a mixture B;

[0162] 3) Add 7.55 g of lauric acid to mixture B, then heat the mixture B to 85° C., stir to melt, and maintain the temperature at 85° C. with continued stirring;

[0163] 4) Maintaining the temperature at 85° C., slowly add mixture A to mixture B obtained in step 3) and stir for 60 min;

[0164] 5) Cooling the mixture obtained in step 4) to 60° C., adding 20 g of sodium laureth sulfate and 12 g of cocamidopropyl betaine sequentially thereto, maintaining the temperature and stirring for 60 min to mix uniformly;

[0165] 6) The mixture obtained in step 5) was cooled to 45° C., 0.05 g of methylisothiazolinone was added thereto, stirred evenly, and cooled to room temperature.

[0166] The polymer products C1-C5 of Examples 1-5 and the polymer products D1 and D2 of the comparative example were used as cross-linked polymer products of unsaturated carboxylic acids, and shower gels were prepared and related performance tests were performed according to the above steps. The results are shown in the following table, where C1 represents the shower gel containing C1, and the same applies to the others.

[0167] Table 8

[0168] As can be seen from the above table, the cross-linked polymer products C1-C5 of unsaturated carboxylic acids according to the embodiments of the present invention also have good thickening efficiency when used in transparent shower gels, and the shower gels have good transparency and moisturizing properties as well as excellent storage stability.

[0169] Application Example 3

[0170] The raw materials used to prepare the facial mask liquid are as follows:

[0171] Table 9

[0172] The steps for preparing the facial mask liquid are:

[0173] 1) Add 60g of deionized water to a 250ml beaker and heat it to 70°C;

[0174] 2) Add 5g of polydimethylsiloxane and 2g of PEG-10-dimethylsiloxane to the beaker while stirring and mix well;

[0175] 3) Cool the mixed solution in the beaker to 50° C., add 1.0 g of butanediol, 0.8 g of glycerol, and 0.2 g of a cross-linked polymer product of an unsaturated carboxylic acid while stirring, and mix thoroughly;

[0176] 4) Cool the mixture in the beaker to room temperature and homogenize the mixture in the beaker at 20,000 rpm for 30 minutes to ensure a more uniform mixture.

[0177] 5) While stirring, slowly add 30g of polyurethane-10, 0.2g of EDTA-2Na, and 0.3g of caprylyl glycol to the mixture in the beaker, mix well, add 0.5g of diethanolamine, and change the speed of the homogenizer as the viscosity increases to ensure uniform neutralization. Adjust the pH of the mixture to 5.2-5.5.

[0178] The polymer products C1-C5 of Examples 1-5 and the polymer products D1 and D2 of the comparative example were used as cross-linked polymer products of unsaturated carboxylic acids, and facial mask liquids were prepared and related performance tests were performed according to the above steps. The results are shown in the following table, where C1 represents the facial mask liquid containing C1, and the same applies to the others.

[0179] Table 10

[0180] As can be seen from the above table, the cross-linked polymer products C1-C5 of unsaturated carboxylic acids according to the embodiments of the present invention also have good thickening efficiency when used in facial mask liquids, without affecting the transparency and storage stability of the facial mask liquids.

[0181] The above embodiments are preferred implementation methods of the present invention, but the present invention is not limited to the above implementation methods. Any other changes, modifications, simplifications, and replacements made without departing from the spirit and principles of the present invention should be considered equivalent replacement methods and are included in the scope of protection of the present invention.< / s> < / d>

Claims

1. A method for preparing a cross-linked polymer of an unsaturated carboxylic acid, comprising: Under the action of a crosslinking agent and a free radical initiator, the unsaturated carboxylic acid product undergoes a polymerization reaction; wherein the unsaturated carboxylic acid product comprises an unsaturated carboxylic acid and a polymer formed by self-polymerization of the unsaturated carboxylic acid, and the content of the polymer in the unsaturated carboxylic acid product is 0.02-1wt%.

2. The preparation method according to claim 1, wherein The unsaturated carboxylic acid includes C3-C6 double-bond-containing carboxylic acids; and / or, the content of the polymer in the unsaturated carboxylic acid product is 0.2-1wt%; and / or, the cross-linking agent comprises a compound containing at least two carbon-carbon double bonds; And / or, the amount of the cross-linking agent is 0.01-5% of the total mass of the cross-linked polymer of the unsaturated carboxylic acid.

3. The preparation method according to claim 1 or 2, wherein The unsaturated carboxylic acid includes one or more of acrylic acid, maleic acid, itaconic acid, fumaric acid, methacrylic acid, crotonic acid, and aconitic acid; and / or, the crosslinking agent comprises a multifunctional acrylate containing at least two polymerizable ethylenically unsaturated double bonds and / or a multialkenyl polyether containing at least two polymerizable ethylenically unsaturated double bonds; And / or, the amount of the cross-linking agent is 0.1-3% of the total mass of the cross-linked polymer of the unsaturated carboxylic acid.

4. The preparation method according to claim 3, wherein The multifunctional acrylate and the multialkenyl polyether are obtained by esterification or etherification of linear or branched polyols; And / or, the amount of the cross-linking agent is 0.5-2% of the total mass of the cross-linked polymer of the unsaturated carboxylic acid.

5. The preparation method according to any one of claims 1 to 4, wherein The free radical initiator is one or more of organic peroxide compounds, azo compounds, inorganic persulfate compounds and hydrogen peroxide; and / or, the solvent used in the polymerization reaction comprises alkanes and / or alkyl acetates; And / or, the cross-linking agent includes one or more of trimethylolpropane diallyl ether, pentaerythritol triallyl ether, 1,6-hexanediol diacrylate, and triethylene glycol diacrylate.

6. The preparation method according to claim 5, wherein: The free radical initiator is selected from one or more of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, dodecanoyl peroxide, ammonium persulfate, sodium persulfate and hydrogen peroxide; And / or, the solvent comprises C1~C 10 Alkanes and / or alkyl acetates containing C1 to C4 alkyl groups.

7. The preparation method according to claim 5, wherein: The alkane includes one or more of n-hexane, cyclohexane, n-heptane, cycloheptane, and n-decane; And / or, the alkyl acetate includes one or more of ethyl acetate, butyl acetate, ethyl propionate, and butyl propionate.

8. The preparation method according to any one of claims 1 to 7, wherein The preparation method comprises the following steps: S1: mixing a solvent and an unsaturated carboxylic acid product to obtain a reaction system; S2: adding a free radical initiator to the reaction system to carry out a polymerization reaction; cooling the system after the reaction, filtering, separating, washing and drying to obtain a cross-linked polymer product of an unsaturated carboxylic acid.

9. The preparation method according to claim 8, wherein: Optionally adding a dispersant in step S1; And / or, the reaction system in step S2 is heated to 50-80° C. for reaction.

10. The preparation method according to claim 9, wherein: The dispersant is a nonionic emulsifier with an HLB value of 2-6.5; And / or, the dispersant is one or more of propylene glycol monostearate, sorbitan stearate, sorbitan tristearate and diethylene glycol monolaurate.

11. A cross-linked polymer of an unsaturated carboxylic acid, prepared by the preparation method according to any one of claims 1 to 10.

12. A cross-linked polymer product of an unsaturated carboxylic acid, prepared by the preparation method according to any one of claims 1 to 10.

13. The product according to claim 12, comprising more than 95 wt% of the cross-linked polymer of the unsaturated carboxylic acid.

14. The product according to claim 12 or 13, comprising more than 97 wt% of the cross-linked polymer of the unsaturated carboxylic acid.

15. Use of the cross-linked polymer of unsaturated carboxylic acid according to claim 11 or the cross-linked polymer of unsaturated carboxylic acid according to any one of claims 12 to 14 in personal care.

16. The use according to claim 15, wherein: The crosslinked polymer of the unsaturated carboxylic acid or the crosslinked polymer product of the unsaturated carboxylic acid is used as a thickener.

17. A personal care product comprising the cross-linked polymer of an unsaturated carboxylic acid according to claim 11 or the cross-linked polymer product of an unsaturated carboxylic acid according to any one of claims 12 to 14.

18. The personal care product of claim 17, wherein: The personal care products include one or more of shampoo, shower gel and facial mask.

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