Carbomer and preparation method therefor, and gel medium thickener

Abstract

The present application provides a carbomer and a preparation method therefor, and a gel medium thickener. The carbomer comprises a core-shell polymer, wherein the core-shell polymer comprises a core polymer and a shell polymer at least partially encapsulating the core polymer; the core polymer is formed by polymerization of a first monomer mixture; the shell polymer is formed by polymerization of a second monomer mixture; the first monomer mixture comprises an unsaturated carboxylic acid and a first hydrophobic monomer; the second monomer mixture comprises an unsaturated carboxylate and a second hydrophobic monomer; and in the second monomer mixture, the mass ratio of the unsaturated carboxylate to the second hydrophobic monomer is 6-15:1. The carbomer provided by the present application has the advantages of a high wetting rate, good ion tolerance, high transparency, and the ability to achieve a desired viscosity upon addition of a small amount thereof to a formulation system.

Description

A carbomer and its preparation method, a gel medium thickener Technical Field

[0001] This application relates to the field of polymer materials, and more particularly to a carbomer and its preparation method, and a gel medium thickener. Background Technology

[0002] Rheology modifiers, also known as thickeners or viscous agents, are a class of chemical substances used to increase the viscosity of liquid or semi-solid systems. They are commonly found in various commercial formulations, such as personal care formulations, medical care formulations, agricultural formulations, coating formulations, clothing and fabric care formulations, and industrial and institutional cleaning formulations.

[0003] Carbomer is a very important rheology modifier. Structurally, it belongs to a class of high molecular weight polymers that are either alkali-swellable acrylic thickeners or hydrophobically modified alkali-swellable acrylic thickeners. Neutralized carbomer is an excellent gel matrix with excellent thickening, suspending and emulsifying properties. It has good compatibility with other excipients and is often used as an adhesive, pharmaceutical excipient and nutritional additive, especially in emulsions, creams and gels.

[0004] However, existing carbomers have drawbacks such as poor wetting time, poor thickening efficiency, poor ion resistance, or low transparency.

[0005] Application content

[0006] To address the aforementioned issues, this application provides a carbomer that offers advantages such as fast wetting rate, good ion resistance, high transparency, and high thickening efficiency.

[0007] This application also provides a method for preparing carbomer, which can prepare the above-mentioned carbomer and has a simple process flow.

[0008] This application also provides a gel medium thickener, which, since it includes the above-mentioned carbomer, has the characteristics of high wetting rate, good ion resistance, high transparency and high viscosity.

[0009] In a first aspect, this application provides a carbomer comprising a core-shell polymer, the core-shell polymer comprising a core polymer and a shell polymer at least partially coating the core polymer; the core polymer is polymerized from a first monomer mixture; the shell polymer is polymerized from a second monomer mixture; the first monomer mixture comprises an unsaturated carboxylic acid, a crosslinking agent, and a first hydrophobic monomer; the second monomer mixture comprises an unsaturated carboxylate and a second hydrophobic monomer; in the second monomer mixture, the mass ratio of the unsaturated carboxylate and the second hydrophobic monomer is 6-15:1.

[0010] Furthermore, in the second monomer mixture, the mass ratio of the unsaturated carboxylate and the second hydrophobic monomer is 8-12:1.

[0011] Furthermore, in the first monomer mixture, the mass ratio of the unsaturated carboxylic acid to the first hydrophobic monomer is 15-50:1.

[0012] Furthermore, the first hydrophobic monomer and the second hydrophobic monomer have the general formula structure shown in Formula 1:

[0013] In this case, R1 is hydrogen or methyl, and R2 is an alkyl structure containing 12-20 carbon atoms.

[0014] Furthermore, the shell polymer accounts for 6-14% of the mass fraction of the core-shell polymer.

[0015] Furthermore, the unsaturated carboxylate is a monovalent metal salt of an unsaturated carboxylic acid.

[0016] Further, the unsaturated carboxylic acid is at least one selected from acrylic acid, methacrylic acid, maleic acid, cinnamic acid, itaconic acid, fumaric acid, crotonic acid, and aconitic acid;

[0017] And / or, the anionic portion of the unsaturated carboxylate is at least one selected from acrylic acid anion, methacrylic acid anion, maleic acid anion, cinnamic acid anion, itaconic acid anion, fumaric acid anion, crotonic acid anion, and aconitic acid anion.

[0018] Furthermore, the crosslinking agent contains at least two unsaturated carbon-carbon double bonds.

[0019] Furthermore, the crosslinking agent is a polyfunctional acrylate containing at least two polymerizable olefinic unsaturated double bonds, and / or a polychain alkenyl polyether containing at least two polymerizable olefinic unsaturated double bonds.

[0020] Furthermore, the mass of the crosslinking agent is 0.01-5% of the total mass of the first monomer mixture.

[0021] Secondly, this application provides a method for preparing the above-mentioned carbomer, comprising the following steps:

[0022] 1) A mixture of a first monomer mixture, solvent, crosslinking agent and free radical initiator is subjected to a single polymerization reaction to obtain a material system including a core polymer;

[0023] 2) The material system including the core polymer, the second monomer mixture, and the free radical initiator are mixed and subjected to a secondary polymerization reaction to obtain the carbomer.

[0024] Furthermore, the mixed system also includes a stabilizer; the stabilizer has an HLB value of 2.0-5.6; and / or, the reaction temperatures of the primary polymerization reaction and the secondary polymerization reaction are each independently 52-80°C.

[0025] Thirdly, this application provides a gel medium thickener, including the carbomer described in the first aspect, or the carbomer prepared by the preparation method described in the second aspect.

[0026] The carbomer provided in this application includes a core-shell polymer. The shell polymer enables rapid surface wetting of the carbomer in water and improves its resistance to ions. The core polymer provides water absorption channels within the carbomer structure, allowing water molecules to enter quickly. The core and shell polymers work together to enable the carbomer to quickly establish a three-dimensional network structure in the application system, restricting the movement of free molecules in the system and comprehensively improving the wetting rate, viscosity, and transparency of the product. In addition, adding a small amount of this product to the formulation system can achieve the desired viscosity. Detailed Implementation

[0027] To enable those skilled in the art to better understand the solutions of this application, a further detailed description of this application is provided below. The specific embodiments listed below are merely descriptions of the principles and features of this application; the examples are only for explaining this application and are not intended to limit its scope. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0028] In a first aspect, this application provides a carbomer comprising a core-shell polymer, the core-shell polymer comprising a core polymer and a shell polymer at least partially coating the core polymer; the core polymer is polymerized from a first monomer mixture; the shell polymer is polymerized from a second monomer mixture; the first monomer mixture comprises an unsaturated carboxylic acid, a crosslinking agent, and a first hydrophobic monomer; the second monomer mixture comprises an unsaturated carboxylate and a second hydrophobic monomer; in the second monomer mixture, the mass ratio of the unsaturated carboxylate and the second hydrophobic monomer is 6-15:1.

[0029] The carbomer provided in this application comprises a core-shell polymer with a specific composition. The shell polymer contains an appropriate amount of carboxylic acid anions. When added to water, the anionic structure in the shell polymer readily hydrates with surrounding water molecules through hydrogen bonds, causing the shell polymer molecular chains to extend and swell. Simultaneously, surrounding water molecules rapidly enter the polymer structure, achieving rapid wetting. The carboxylic acid in the core-shell polymer, after neutralization with an alkaline substance, can swell sufficiently due to the charge repulsion principle of the carboxylic acid structure, allowing the polymer molecular chains to extend over a large range, thus effectively filling the system volume. This rapidly establishes a three-dimensional network structure in the application system, restricting the movement of free molecules and achieving the required increase in viscosity and rheological properties. Furthermore, some hydrophobic monomers in the polymer backbone can associate in water due to their hydrophilic-hydrophobic relationship, further "firmly" enhancing the volume filling and thus significantly improving the viscosity and transparency of the system. Meanwhile, after adding some salt to the carbomer, the charge repulsion of the carboxylate group on the carbomer main chain is reduced, causing the main chain to shrink and the entire carbomer structure to begin to "collapse". However, the appropriate amount of the second hydrophobic monomer in the shell polymer can effectively hydrophobically associate during the shrinkage, preventing further shrinkage of the carbomer structure, thereby increasing the viscosity of the system after adding salt, and achieving the improvement of the carbomer's ion resistance viscosity and transparency after adding salt.

[0030] Furthermore, in this application, the second monomer mixture includes an unsaturated carboxylate and a second hydrophobic monomer. When the mass ratio of the unsaturated carboxylate to the second hydrophobic monomer in the second monomer mixture is 6-15:1, it can further ensure that the carbomer has good wettability, viscosity, transparency, and ion resistance. When the mass ratio of the unsaturated carboxylate to the second hydrophobic monomer is less than 6:1, the product surface is more hydrophobic and has lower surface tension, making it difficult to wet and adsorb water, resulting in non-water absorption. When the mass ratio of the unsaturated carboxylate to the second hydrophobic monomer is greater than 15:1, the addition of salts such as sodium chloride to the system can easily cause excessive contraction of the shell chain segments, which greatly weakens the association during contraction, thereby reducing the viscosity of the product after adding salt, reducing the ion resistance and transparency of the system, and failing to meet the usage requirements.

[0031] The application scenarios of carbomer described above are not particularly limited in this application. Due to its advantages, in some embodiments, the carbomer of this application can be used in creams, lotions, gels and skin care products as a thickener and emulsifying stabilizer, providing a smooth texture and good spreadability; in other embodiments, the carbomer of this application is also used in topical pharmaceutical preparations, gels and ointments as a thickener and stabilizer, providing suitable viscosity and stability.

[0032] In this application, the ion resistance of the carbomer is reflected in the fact that when a certain amount of monovalent or / and divalent ion salt compounds, such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium nitrate, potassium nitrate, calcium nitrate, etc., are added to the carbomer-thickened aqueous gel system, its viscosity is reduced to more than 20% of the initial viscosity.

[0033] In a preferred embodiment, the mass ratio of the unsaturated carboxylate and the second hydrophobic monomer in the second monomer mixture is 8-12:1.

[0034] The second monomer mixture described above can further ensure the water-wetting and adsorption properties of carbomer, avoid affecting the wetting effect due to excessive hydrophobic monomers, and effectively enhance the association of the shell polymer when salt is added, further reducing the structural shrinkage of carbomer.

[0035] For example, the mass ratio of the unsaturated carboxylate to the second hydrophobic monomer is 8:1, 9:1, 10:1, 11:1, 12:1, etc.

[0036] In a preferred embodiment, the mass ratio of the unsaturated carboxylic acid to the first hydrophobic monomer in the first monomer mixture is 15-50:1.

[0037] The first monomer mixture described above ensures that when carbomer is neutralized and applied in the target system, the carbomer molecular chains can be effectively extended to establish a large-scale three-dimensional structure, thereby further increasing the viscosity of the system. At the same time, the first monomer mixture can provide appropriate association of hydrophobic monomers, thereby further improving the viscosity and transparency of carbomer.

[0038] To further enhance the ion resistance of carbomer, in a preferred embodiment, the first and second hydrophobic monomers have the general structure shown in Formula 1:

[0039] In this case, R1 is hydrogen or methyl, and R2 is an alkyl structure containing 12-20 carbon atoms.

[0040] As described above, the first and second hydrophobic monomers can further ensure the viscosity and transparency of carbomer. When R2 contains less than 12 carbon atoms, its association in the system after carbomer stretching is low, and it is difficult to establish a "tight" structure when salt is added to the system, resulting in insufficient improvement in the system's resistance to ions. When R2 contains more than 20 carbon atoms, its hydrophobicity is too strong, and it will curl up in the molecular chain, resulting in low product transparency.

[0041] It should be noted that the specific structures of the first hydrophobic monomer and the second hydrophobic monomer may be the same or different, and this application does not impose any special restrictions on this.

[0042] For example, the first hydrophobic monomer and the second hydrophobic monomer are each independently one or more of lauryl acrylate, lauryl methacrylate, tetradecyl acrylate, tetradecyl methacrylate, cetyl acrylate, cetyl methacrylate, octadecyl acrylate, octadecyl methacrylate, ecicoacrylate, and ecicoacrylate.

[0043] In a preferred embodiment, the shell polymer accounts for 6-14% of the mass fraction of the core-shell polymer.

[0044] As described above, the core-shell polymer can further ensure the rapid water absorption and wetting of the outer layer of carbomer, improve the wetting effect of carbomer, and ensure that the association strength of the shell polymer is not too large, so that the carbomer can fully swell in the system, further improving the thickening viscosity and transparency of the product.

[0045] For example, the shell polymer accounts for any value or a range of any two of the mass fraction of the core-shell polymer, such as 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%.

[0046] In a preferred embodiment, the unsaturated carboxylate is a monovalent metal salt of an unsaturated carboxylic acid;

[0047] In a preferred embodiment, the unsaturated carboxylic acid is at least one selected from acrylic acid, methacrylic acid, maleic acid, cinnamic acid, itaconic acid, fumaric acid, crotonic acid, and aconitic acid.

[0048] And / or, the anionic portion of the unsaturated carboxylate is at least one of acrylic acid anion, methacrylic acid anion, maleic acid anion, cinnamic acid anion, itaconic acid anion, fumaric acid anion, crotonic acid anion, and aconitic acid anion.

[0049] The anionic moiety of the unsaturated carboxylate and the structure of the unsaturated carboxylic acid may be the same or different, and this application does not impose any particular limitation on this.

[0050] In some embodiments, the crosslinking agent contains at least two unsaturated carbon-carbon double bonds.

[0051] In some embodiments, the crosslinking agent is a polyfunctional acrylate containing at least two polymerizable olefinic unsaturated double bonds (e.g., a (meth)acrylate compound of a straight-chain or branched polyol having 2-20 carbon atoms), and / or, a polychain alkenyl polyether containing at least two polymerizable olefinic unsaturated double bonds (e.g., an etherification product of allyl alcohol and a straight-chain or branched polyol having 2-15 carbon atoms).

[0052] In this application, the aforementioned crosslinking agent can effectively establish a three-dimensional network structure, thereby reducing the free water in the entire carbomer system and improving the viscosity and stability of the system.

[0053] Exemplarily, the multifunctional acrylates and multi-chain alkenyl polyethers are formed by the esterification or etherification of linear and branched polyols; the polyols are selected from one or more of sucrose, pentaerythritol, dipentaerythritol, trimethylolpropane and its dimers, and triethylolpropane and its dimers; the (meth)acrylate compounds used as crosslinking agents are, for example, selected from ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,6-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, etc. One or more of the following: acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, and pentaerythritol tetra(meth)acrylate; the multi-chain alkenyl polyethers used as crosslinking agents include polyallyl ethers having 2-4 functionalities per molecule, such as pentaerythritol diallyl ether, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, trimethylolpropane diallyl ether, and trimethylolpropane triallyl ether.

[0054] It is understood that other types of crosslinking agents, such as silicone crosslinking agents, zinc oxide crosslinking agents, divinylbenzene, methylenediacrylamide, etc., can also be used in this application.

[0055] In a preferred embodiment, the crosslinking agent is used at a mass of 0.01-5% of the total mass of the first monomer mixture. Using a crosslinking agent within this range avoids over-crosslinking or under-crosslinking. More preferably, the crosslinking agent is used at a mass of 0.1-3% of the total mass of the first monomer mixture, and more preferably at 0.5-2.5%.

[0056] In a preferred embodiment, the carbomer is prepared by a method comprising the following process:

[0057] 1) A mixture of a first monomer mixture, solvent, crosslinking agent and free radical initiator is subjected to a single polymerization reaction to obtain a material system including a core polymer;

[0058] 2) The material system including the core polymer, the second monomer mixture, and the free radical initiator are mixed and subjected to a secondary polymerization reaction to obtain the carbomer.

[0059] The solvent used in the above preparation method can be any liquid that can dissolve the monomer and does not react with the monomer, for example, selected from alkanes having 1 to 10 carbon atoms, alkyl acetates having 1 to 4 carbon atoms in alkyl groups and mixtures thereof, wherein the hydrocarbons used include, but are not limited to, n-hexane, cyclohexane, n-heptane, cycloheptane, n-decane and mixtures thereof; wherein the alkyl acetates used include, but are not limited to, ethyl acetate, butyl acetate, ethyl propionate, butyl propionate and mixtures thereof.

[0060] The free radical initiators used in the above preparation method include, but are not limited to, one or more of organic peroxide compounds, azo compounds, inorganic persulfate compounds, and hydrogen peroxide; preferably, the free radical initiator is one or more of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, dodecyl peroxide, ammonium persulfate, sodium persulfate, and hydrogen peroxide.

[0061] For example, the amount of the free radical initiator can be 0.05-1 wt% of the total weight of the monomer, preferably 0.2-0.7 wt%, such as 0.1%, 0.4%, or 0.6%.

[0062] Secondly, this application provides a method for preparing the above-mentioned carbomer, comprising the following steps:

[0063] 1) A mixture of a first monomer mixture, solvent, crosslinking agent and free radical initiator is subjected to a single polymerization reaction to obtain a material system including a core polymer;

[0064] 2) The material system including the core polymer, the second monomer mixture, and the free radical initiator are mixed and subjected to a secondary polymerization reaction to obtain the carbomer.

[0065] Furthermore, the mixed system also includes a stabilizer; the stabilizer has a hydrophilic-lipophilic balance (HLB) value of 2.0-5.6; and / or, the reaction temperatures of the primary polymerization reaction and the secondary polymerization reaction are each independently 52-80°C.

[0066] In some embodiments, the total solid content of the primary or secondary polymerization in the polymerization system is 15-18%, wherein the solid content is calculated as (stabilizer + crosslinking agent + shell polymerization monomer + core polymerization monomer) / total mass of the polymerization system × 100%.

[0067] The solvent used in the above preparation method can be any liquid that can dissolve the monomer and does not react with the monomer, for example, selected from alkanes having 1 to 10 carbon atoms, alkyl acetates having 1 to 4 carbon atoms in alkyl groups and mixtures thereof, wherein the hydrocarbons used include, but are not limited to, n-hexane, cyclohexane, n-heptane, cycloheptane, n-decane and mixtures thereof; wherein the alkyl acetates used include, but are not limited to, methyl acetate, ethyl acetate, propyl acetate, butyl acetate and mixtures thereof.

[0068] The solvents used in the above preparation method are alkanes and alkyl acetates. The alkanes and alkyl acetates can be used alone or in combination, preferably in combination. When used in combination, the mass ratio of the alkane solvent to the alkyl acetate is 2:1 to 1:2.

[0069] The free radical initiators used in the above preparation method include, but are not limited to, one or more of organic peroxide compounds, azo compounds, inorganic persulfate compounds, and hydrogen peroxide; preferably, the free radical initiator is one or more of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, dodecyl peroxide, ammonium persulfate, sodium persulfate, and hydrogen peroxide.

[0070] For example, the amount of the free radical initiator can be 0.05-1 wt% of the total weight of the monomer, preferably 0.2-0.7 wt%, such as 0.1%, 0.4%, or 0.6%.

[0071] The stabilizers include, but are not limited to, one or more of the following: sorbitan tristearate (HLB value 2.1), propylene glycol monostearate (HLB value 3.4), polyoxyethylene sorbitan 4,5 oleate (HLB value 3.7), sorbitan monooleate (HLB value 4.3), propylene glycol monolaurate (HLB value 4.5), diethylene glycol monostearate (HLB value 4.7), isotridecyl polyether-1.5 (HLB value 5.4), and glyceryl monostearate (HLB value 5.5).

[0072] For example, the amount of the stabilizer used may be 0.2-1.2% of the total mass of the monomer.

[0073] For example, the system comprising a first monomer mixture, a solvent, and a crosslinking agent is heated to 52-80°C, and the free radical initiator is added to carry out a polymerization reaction to obtain a material system comprising a core polymer.

[0074] Thirdly, this application provides a gel medium thickener, including the carbomer described in the first aspect, or the carbomer prepared by the preparation method described in the second aspect.

[0075] To further understand this application, the technical solutions of this application will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0076] Unless otherwise specified, all reagents involved in the embodiments of this application are commercially available products and can be purchased through commercial channels.

[0077] The raw materials and information used in the following experiments are shown in Table 1 below.

[0078] Table 1:

[0079] The main equipment used in the following experiments is shown in Table 2 below.

[0080] Table 2:

[0081] The following tests, involving wetting time, thickening efficiency, transparency, ion resistance, and pH value of a 1% aqueous solution, are conducted using the following methods:

[0082] Wetting time test method: Add 198g of deionized water to a 300ml plastic straight bottle with a diameter of 8cm. Weigh 2g of the carbomer sample to be tested on weighing paper and quickly and evenly spread it on the water surface of the straight bottle. Start the stopwatch and stop the timing when the white particles on the water surface disappear. The time taken is the wetting time.

[0083] Viscosity test method: Add 198g of deionized water to a 300ml, 8cm diameter plastic straight-sided bottle, then add 2g of the carbomer sample to be tested, and let it stand for 8 hours to allow it to fully absorb water and swell. Place a stirrer in the bottle, start stirring, and slowly add 18% sodium hydroxide aqueous solution dropwise. Stir at 800rpm for 40-60min, adjusting the pH value to 7.5±0.2. Place the bottle in a constant temperature water bath and let it stand for 8 hours to stabilize (this sample is a well-neutralized sample). Test its viscosity at 20rpm.

[0084] Transparency test method: Place an appropriate amount of neutralized sample into a centrifuge tube. Place the centrifuge tube in a centrifuge, set the speed to 5000 rpm, and centrifuge for 10 minutes. After centrifugation, carefully transfer the sample into a cuvette (to prevent the introduction of air bubbles). Then place the cuvette into a spectrophotometer to measure the transparency.

[0085] Ion resistance test method: Take 200g of the neutralized sample and put it into a 300ml straight bottle, add a stirrer and start stirring. Add 2g of sodium chloride solid particles to the gel, stir for 30min, then keep it at a constant temperature for 2h, and measure the viscosity at 20rpm.

[0086] Example 1

[0087] A carbomer polymer C1 was prepared, and its raw material composition is shown in Table 3 below:

[0088] Table 3:

[0089] In this embodiment, the shell polymer accounts for 6% of the mass fraction of the outer core-shell polymer, and the total solid content of the polymer raw material system is 15%.

[0090] The steps for synthesizing the ion-resistant carbomer polymer using this raw material formulation are as follows:

[0091] 1) Add 270g of ethyl acetate and 540g of n-hexane to a 3L four-necked flask equipped with a mechanical stirrer and a nitrogen inlet. Then add 0.45g of diethylene glycol monostearate and 2.88g of lauryl acrylate. Mix well and purge with nitrogen for at least 30 minutes to reduce the oxygen content in the system to 1×10⁻⁶. -7 Below mg / L;

[0092] 2) Add 138.12g of acrylic acid, 3.45g of 1,6-hexanediol diacrylate, 0.564g of azobisisobutyronitrile, 20g of ethyl acetate and 40g of n-hexane to a dropping flask, mix well and set aside.

[0093] 3) Raise the temperature of the four-necked flask to 65°C and begin adding the mixture dropwise into the flask. Control the dropping time for 4 hours and maintain the flask temperature between 63-67°C during the dropping process. After the dropping is complete, keep the flask temperature between 64-66°C and keep the substance in the flask warm to allow it to fully polymerize for 3 hours. When the polymerization time is up, the core of the polymer in this application is obtained.

[0094] 4) Add 8.0g sodium acrylate, 1.0g lauryl acrylate and 0.036g azobisisobutyronitrile to the polymerization bottle, maintain the temperature inside the reactor at 63-67℃ for 4 hours, and then cool to room temperature to obtain a suspension of ion-resistant carbomer polymer.

[0095] 5) The obtained suspension was filtered under negative pressure to obtain a white precipitate. The white precipitate was washed three times with a mixed solvent (ethyl acetate: n-hexane = 1:2 mass ratio). After each washing, the precipitate was filtered to obtain a white polymer containing solvent.

[0096] The white polymer containing solvent was placed in a vacuum oven and dried under negative pressure at a temperature of 95°C for 24 hours to obtain ion-resistant carbomer polymer C1 powder. The test data parameters are shown in Table 4 below.

[0097] Table 4:

[0098] Example 2

[0099] A carbomer polymer C2 was prepared, and its raw material composition is shown in Table 5 below:

[0100] Table 5:

[0101] In this embodiment, the shell polymer accounts for 14% of the mass fraction of the outer core-shell polymer, and the total solid content of the polymer raw material system is 18%.

[0102] The steps for synthesizing the ion-resistant carbomer polymer using this raw material formulation are as follows:

[0103] 1) Add 389g of butyl acetate and 389g of cyclohexane to a 3L four-necked flask equipped with a mechanical stirrer and a nitrogen inlet. Then add 1.62g of glyceryl monostearate and 8.6g of octadecyl methacrylate. Mix well and purge with nitrogen for at least 30 minutes to reduce the oxygen content in the system to 1×10⁻⁶. -7 Below mg / L;

[0104] 2) Add 146.2g of methacrylic acid, 2.34g of trimethylolpropane triacrylate, 0.3096g of benzoyl peroxide, 30g of butyl acetate and 30g of cyclohexane to a dropping flask, mix well and set aside.

[0105] 3) Raise the temperature of the four-necked flask to 78°C and begin adding the mixture dropwise to the flask. Control the dropping time for 4 hours and maintain the flask temperature between 76-80°C during the dropping process. After the dropping is complete, keep the flask temperature between 77-79°C and keep the substance in the flask warm to allow it to fully polymerize for 3 hours. When the polymerization time is up, the core of the polymer in this application is obtained.

[0106] 4) Add 23.26g potassium methacrylate, 1.94g octadecyl methacrylate and 0.0504g benzoyl peroxide to the polymerization bottle, maintain the temperature inside the vessel at 76-80℃ for 4 hours, and then cool to room temperature to obtain a suspension of ion-resistant carbomer polymer.

[0107] 5) The obtained suspension was filtered under negative pressure to obtain a white precipitate. The white precipitate was washed three times with a mixed solvent (butyl acetate: cyclohexane = 1:1 mass ratio). After each washing, the precipitate was filtered to obtain a white polymer containing solvent.

[0108] The white polymer containing solvent was placed in a vacuum oven and dried under negative pressure at a temperature of 95°C for 24 hours to obtain ion-resistant carbomer polymer C2 powder. The test data parameters are shown in Table 6 below.

[0109] Table 6:

[0110] Example 3

[0111] A carbomer polymer C3 was prepared, and its raw material composition is shown in Table 7 below:

[0112] Table 7:

[0113] In this embodiment, the shell polymer accounts for 10% of the mass fraction of the outer core-shell polymer, and the total solid content of the polymer raw material system is 16%.

[0114] The steps for synthesizing the ion-resistant carbomer polymer using this raw material formulation are as follows:

[0115] 1) Add 526.67g of propyl acetate and 263.33g of n-heptane to a 3L four-necked flask equipped with a mechanical stirrer and a nitrogen inlet. Then add 0.96g of sorbitan tristearate and 4.8g of cetyl methacrylate. Mix thoroughly and purge with nitrogen for at least 30 minutes to reduce the oxygen content in the system to 1×10⁻⁶. -7 Below mg / L;

[0116] 2) Add 139.2g of acrylic acid, 0.96g of pentaerythritol diallyl ether, 1.008g of azobisisoheptane, 40g of propyl acetate and 20g of n-heptane to a dropping flask, mix well and set aside.

[0117] 3) Raise the temperature of the four-necked flask to 54°C and begin adding the mixture dropwise into the flask. Control the dropping time for 4 hours, and maintain the flask temperature between 52-56°C during the dropping process. When the dropping is complete, keep the flask temperature between 53-55°C and keep the substance in the flask warm to allow it to fully polymerize for 3 hours. When the polymerization time is up, the core of the polymer in this application is obtained.

[0118] 4) Add 14.55g sodium methacrylate, 1.45g cetyl methacrylate and 0.112g azobisisobutyronitrile to the polymerization bottle, maintain the temperature inside the vessel at 52-56℃ for 4 hours, and then cool to room temperature to obtain a suspension of ion-resistant carbomer polymer.

[0119] 5) The obtained suspension was filtered under negative pressure to obtain a white precipitate. The white precipitate was washed three times with a mixed solvent (propyl acetate: n-heptane = 2:1 mass ratio). After each washing, the precipitate was filtered to obtain a white polymer containing solvent.

[0120] The white polymer containing solvent was placed in a vacuum oven and dried under negative pressure at a temperature of 95°C for 24 hours to obtain ion-resistant carbomer polymer C3 powder. The test data parameters are shown in Table 8 below.

[0121] Table 8:

[0122] Example 4

[0123] A carbomer polymer C4 was prepared, and its raw material formulation is shown in Table 9 below:

[0124] Table 9:

[0125] In this embodiment, the shell polymer accounts for 12% of the mass fraction of the outer core-shell polymer, and the total solid content of the polymer raw material system is 16%.

[0126] The steps for synthesizing the ion-resistant carbomer polymer using this raw material formulation are as follows:

[0127] 1) Add 402.5g of methyl acetate and 402.5g of cyclohexane to a 3L four-necked flask equipped with a mechanical stirrer and a nitrogen inlet. Then add 1.92g of polyoxyethylene sorbitan 4,5-oleate and 3.91g of eicosinate. Mix thoroughly and purge with nitrogen for at least 30 minutes to reduce the oxygen content in the system to 1×10⁻⁶. -7 Below mg / L;

[0128] 2) Add 136.89g of methacrylic acid, 2.88g of trimethylolpropane triacrylate, 0.5632g of azobisisobutyronitrile, 30g of methyl acetate and 30g of cyclohexane to a dropping flask, mix well and set aside.

[0129] 3) Raise the temperature of the four-necked flask to 63°C and begin adding the mixture dropwise into the flask. Control the dropping time for 4 hours and maintain the flask temperature between 61-65°C during the dropping process. When the dropping is complete, keep the flask temperature between 62-64°C and keep the substance in the flask warm to allow it to fully polymerize for 3 hours. When the polymerization time is up, the core of the polymer in this application is obtained.

[0130] 4) Add 17.28g sodium acrylate, 1.92g cetyl methacrylate and 0.0768g azobisisobutyronitrile to the polymerization bottle, maintain the temperature inside the reactor at 61-65℃ for 4 hours, and then cool to room temperature to obtain a suspension of ion-resistant carbomer polymer.

[0131] 5) The obtained suspension was filtered under negative pressure to obtain a white precipitate. The white precipitate was washed three times with a mixed solvent (methyl acetate: cyclohexane = 1:1 mass ratio). After each washing, the precipitate was filtered to obtain a white polymer containing solvent.

[0132] The white polymer containing solvent was placed in a vacuum oven and dried under negative pressure at a temperature of 95°C for 24 hours to obtain ion-resistant carbomer polymer C4 powder. The test data parameters are shown in Table 10 below.

[0133] Table 10:

[0134] Example 5

[0135] A carbomer polymer C5 was prepared, and its raw material formulation is shown in Table 11 below:

[0136] Table 11:

[0137] In this embodiment, the shell polymer accounts for 8% of the mass fraction of the outer core-shell polymer, and the total solid content of the polymer raw material system is 17%.

[0138] The steps for synthesizing the ion-resistant carbomer polymer using this raw material formulation are as follows:

[0139] 1) Add 291.6g of ethyl acetate and 452.4g of cyclohexane to a 3L four-necked flask equipped with a mechanical stirrer and a nitrogen inlet. Then add 0.8g of glyceryl monostearate and 3.27g of octadecyl methacrylate. Mix well and purge with nitrogen for at least 30 minutes to reduce the oxygen content in the system to 1×10⁻⁶. -7 Below mg / L;

[0140] 2) Add 143.93g of acrylic acid, 3.84g of pentaerythritol diallyl ether, 0.8832g of azobisisoheptanenitrile, 30g of ethyl acetate and 30g of cyclohexane to a dropping flask, mix well and set aside.

[0141] 3) Raise the temperature of the four-necked flask to 54°C and begin adding the mixture dropwise into the flask. Control the dropping time for 4 hours, and maintain the flask temperature between 52-56°C during the dropping process. When the dropping is complete, keep the flask temperature between 53-55°C and keep the substance in the flask warm to allow it to fully polymerize for 3 hours. When the polymerization time is up, the core of the polymer in this application is obtained.

[0142] 4) Add 11.02g sodium acrylate, 1.78g cetyl methacrylate and 0.0768g azobisisobutyronitrile to the polymerization bottle, maintain the temperature inside the reactor at 52-56℃ for 4 hours, and then cool to room temperature to obtain a suspension of ion-resistant carbomer polymer.

[0143] 5) The obtained suspension was filtered under negative pressure to obtain a white precipitate. The white precipitate was washed three times with a mixed solvent (ethyl acetate: cyclohexane = 1:1.5 mass ratio). After each washing, the precipitate was filtered to obtain a white polymer containing solvent.

[0144] The white polymer containing solvent was placed in a vacuum oven and dried under negative pressure at a temperature of 95°C for 24 hours to obtain ion-resistant carbomer polymer C5 powder. The test data parameters are shown in Table 12 below.

[0145] Table 12:

[0146] Example 6

[0147] A carbomer polymer C6 was prepared, and its raw material formulation is shown in Table 13 below:

[0148] Table 13:

[0149] In this embodiment, the shell polymer accounts for 11% of the mass fraction of the outer core-shell polymer, and the total solid content of the polymer raw material system is 16.5%.

[0150] The steps for synthesizing the ion-resistant carbomer polymer using this raw material formulation are as follows:

[0151] 1) Add 454.17g butyl acetate and 315.83g n-hexane to a 3L four-necked flask equipped with a mechanical stirrer and a nitrogen inlet. Then add 1.6g dehydrated sorbitan tristearate and 6.47g lauryl acrylate. Mix well and purge with nitrogen for at least 30 minutes to reduce the oxygen content in the system to 1×10⁻⁶. -7 Below mg / L;

[0152] 2) Add 135.93g of acrylic acid, 2.4g of 1,6-hexanediol diacrylate, 0.7832g of azobisisobutyronitrile, 30g of ethyl acetate and 30g of cyclohexane to a dropping flask, mix well and set aside.

[0153] 3) Raise the temperature of the four-necked flask to 65°C and begin adding the mixture dropwise into the flask. Control the dropping time for 4 hours and maintain the flask temperature between 63-67°C during the dropping process. After the dropping is complete, keep the flask temperature between 64-66°C and keep the substance in the flask warm to allow it to fully polymerize for 3 hours. When the polymerization time is up, the core of the polymer in this application is obtained.

[0154] 4) Add 16.47g potassium methacrylate, 1.13g eicosinate acrylate and 0.0968g azobisisobutyronitrile to the polymerization bottle, maintain the temperature inside the reactor at 52-56℃ for 4 hours, and then cool to room temperature to obtain a suspension of ion-resistant carbomer polymer.

[0155] 5) The obtained suspension was filtered under negative pressure to obtain a white precipitate. The white precipitate was then washed three times with a mixed solvent (butyl acetate: n-hexane = 1.4:1 mass ratio). After each washing, the precipitate was filtered to obtain a white polymer containing solvent.

[0156] The white polymer containing solvent was placed in a vacuum oven and dried under negative pressure at a temperature of 95°C for 24 hours to obtain ion-resistant carbomer polymer C6 powder. The test data parameters are shown in Table 14 below.

[0157] Table 14:

[0158] Comparative Example 1

[0159] Comparative product D1, prepared according to the synthesis steps of Example 4, had a mass ratio of outer unsaturated carboxylate and second hydrophobic monomer of 4:1. Its raw material composition is shown in Table 15 below.

[0160] Table 15:

[0161] In this embodiment, the shell polymer accounts for 12% of the mass fraction of the outer core-shell polymer, and the total solid content of the polymer raw material system is 16%.

[0162] The polymerization process was carried out according to Example 4 to obtain the comparative polymer D1 powder, and its test data parameters are shown in Table 16 below.

[0163] Table 16:

[0164] Comparative Example 2

[0165] Comparative product D2, prepared according to the synthesis steps of Example 4, had a mass ratio of outer unsaturated carboxylate and second hydrophobic monomer of 16:1. Its raw material composition is shown in Table 17 below.

[0166] Table 17:

[0167] In this embodiment, the shell polymer accounts for 12% of the mass fraction of the outer core-shell polymer, and the total solid content of the polymer raw material system is 16%.

[0168] The polymerization process was carried out according to Example 4 to obtain the comparative polymer D2 powder, and its test data parameters are shown in Table 18 below.

[0169] Table 18:

[0170] Comparative Example 3

[0171] The product, whose overall structure consists entirely of the outer layer, was prepared according to the synthesis steps of Example 4. The comparative product D3, in which the mass ratio of the unsaturated carboxylate to the second hydrophobic monomer was 9:1, has the following raw material formulation composition as shown in Table 19:

[0172] Table 19:

[0173] In this embodiment, the total solids content of the polymer raw material system is 16%.

[0174] The polymerization process was carried out according to Example 4 to obtain the comparative polymer D3 powder, and its test data parameters are shown in Table 20 below.

[0175] Table 20:

[0176] In summary, the results above show that by limiting the mass ratio of the unsaturated carboxylate and the second hydrophobic monomer in the shell polymer raw materials to 6-15:1, Examples 1-6 can ensure that the carbomer has a shorter wetting time and higher viscosity, transparency, and ionic viscosity. In contrast, the carbomer in Comparative Examples 1-3 cannot achieve the same balance of wetting time, viscosity, transparency, and ionic viscosity.

[0177] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A carbomer characterized in that, It comprises a core-shell polymer, wherein the core-shell polymer comprises a core polymer and a shell polymer at least partially coating the core polymer; the core polymer is polymerized from a first monomer mixture; the shell polymer is polymerized from a second monomer mixture; the first monomer mixture comprises an unsaturated carboxylic acid, a crosslinking agent and a first hydrophobic monomer; the second monomer mixture comprises an unsaturated carboxylate and a second hydrophobic monomer; in the second monomer mixture, the mass ratio of the unsaturated carboxylate and the second hydrophobic monomer is 6-15:

1.

2. The carbomer of claim 1, wherein, In the second monomer mixture, the mass ratio of the unsaturated carboxylate to the second hydrophobic monomer is 8-12:1; And / or, in the first monomer mixture, the mass ratio of the unsaturated carboxylic acid to the first hydrophobic monomer is 15-50:

1.

3. The carbomer of claim 1, wherein The first and second hydrophobic monomers have a general structure shown in Formula 1: In this case, R1 is hydrogen or methyl, and R2 is an alkyl structure containing 12-20 carbon atoms.

4. Carbomer according to any of claims 1 to 3, characterized in that The shell polymer accounts for 6-14% of the mass fraction of the core-shell polymer.

5. Carbomer according to any of claims 1 to 3, characterized in that The unsaturated carboxylate is a monovalent metal salt of an unsaturated carboxylate; Preferably, the unsaturated carboxylic acid is at least one selected from acrylic acid, methacrylic acid, maleic acid, cinnamic acid, itaconic acid, fumaric acid, crotonic acid, and aconitic acid; And / or, the anionic portion of the unsaturated carboxylate is at least one selected from acrylic acid anion, methacrylic acid anion, maleic acid anion, cinnamic acid anion, itaconic acid anion, fumaric acid anion, crotonic acid anion, and aconitic acid anion.

6. The carbomer according to any one of claims 1 to 3, wherein The crosslinking agent contains at least two unsaturated carbon-carbon double bonds; Preferably, the crosslinking agent is a polyfunctional acrylate containing at least two polymerizable olefinic unsaturated double bonds, and / or a polychain alkenyl polyether containing at least two polymerizable olefinic unsaturated double bonds.

7. The carbomer of claim 6 wherein, The mass of the crosslinking agent is 0.01-5% of the total mass of the first monomer mixture.

8. A method for preparing carbomer as described in any one of claims 1-7, comprising the following steps: 1) A mixture of a first monomer mixture, solvent, crosslinking agent and free radical initiator is subjected to a single polymerization reaction to obtain a material system including a core polymer; 2) The material system including the core polymer, the second monomer mixture, and the free radical initiator are mixed and subjected to a secondary polymerization reaction to obtain the carbomer.

9. The production method according to claim 8, characterized by, The mixture also includes a stabilizer; the stabilizer has an HLB value of 2.0-5.6; And / or, the reaction temperatures of the primary polymerization reaction and the secondary polymerization reaction are each independently 52-80°C.

10. A gel medium thickener characterized by, This includes the carbomer according to any one of claims 1-7, or the carbomer prepared by any one of the preparation methods according to claims 8-9.

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