Reversed-phase suspension method acrylic acid grafted starch as well as preparation method and application thereof

Abstract

The invention discloses reverse-phase suspension method acrylic acid grafted starch as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The preparation method specifically comprises the following steps: (1) adding starch into water, stirring and gelatinizing to obtain gelatinized starch for later use; (2) adding sodium hydroxide into water to obtain a sodium hydroxide solution; (3) firstly adding acrylic acid into a sodium hydroxide solution for neutralization reaction, then adding an initiator and a cross-linking agent, and uniformly stirring to obtain a mixture A; (4) adding the mixture A into gelatinized starch, and uniformly stirring to obtain a mixture B; and (5) adding an organic solvent and a dispersing agent into the reaction flask, uniformly stirring, adding the mixture B, carrying out heating reaction, filtering, washing, dehydrating and drying, thereby obtaining the product. The acrylic acid grafted starch is synthesized by adopting a reversed-phase suspension polymerization method, and the method has the characteristics of uniform product particle size distribution, high water and salt absorption rate, easiness in reaction control and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and more particularly to an inverse suspension method acrylic acid grafted starch and a preparation method and application thereof. Background Art

[0002] Gel patches are topical patches made from a water-soluble polymer material. They contain medication and deliver it to the affected area via a transdermal sustained-release technique. They are commonly used for local anti-inflammatory and analgesic treatments, as well as to relieve muscle and joint pain. Compared to traditional plasters, they offer improved breathability, are less prone to allergies, and leave no residue when removed, making them suitable for those who require long-term application or have sensitive skin.

[0003] In the gel patch formula, acrylic acid grafted starch is a key polymer excipient. Because it's starch-based, it reduces skin irritation, has better biocompatibility than polyacrylates and sodium polyacrylate, and has higher adhesion than natural starch, making it less likely to fall off after application.

[0004] However, acrylic acid grafted starch generally has unstable product quality control, poor adhesion, low drug loading, inability to flexibly control the starch grafting rate, inability to effectively adjust the drug release rate, and unstable production process control of the reverse suspension method, and is prone to self-aggregation during the reaction.

[0005] Therefore, how to develop a mature inverse suspension method for producing acrylic acid grafted starch is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the object of the present invention is to provide an inverse suspension method acrylic acid grafted starch and its preparation method and application, so as to solve the deficiencies in the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing acrylic acid grafted starch by an inverse suspension method specifically comprises the following steps:

[0009] (1) Add starch to water, stir and gelatinize to obtain gelatinized starch, and set aside;

[0010] (2) adding sodium hydroxide into water to obtain a sodium hydroxide solution;

[0011] (3) first adding acrylic acid into sodium hydroxide solution for neutralization reaction, then adding initiator and cross-linking agent, stirring evenly to obtain mixture A;

[0012] (4) adding mixture A to gelatinized starch and stirring uniformly to obtain mixture B;

[0013] (5) Add an organic solvent and a dispersant to the reaction flask, stir evenly, add mixture B to react at elevated temperature, filter, wash and dehydrate, and dry to obtain the reverse suspension method acrylic acid grafted starch.

[0014] Furthermore, in the above step (1), the starch is at least one of tapioca starch, corn starch and potato starch, preferably corn starch, with a purity of >85% and a moisture content of <14%; and the mass ratio of starch to water is (3.67-9.62):60.

[0015] The above further beneficial effects are that the grafting reaction conditions of corn starch (such as gelatinization temperature of 62-64°C) are moderate and can be completed efficiently without special equipment, the proportion of amylose is moderate, and the grafting efficiency is high; the particle characteristics are conducive to the reaction.

[0016] Furthermore, in the above step (1), the stirring and gelatinization conditions are as follows: nitrogen is introduced, the temperature is 60-80° C., and the time is 30 minutes.

[0017] Furthermore, in the above step (2), the mass ratio of sodium hydroxide to water is 5.6:40.

[0018] Furthermore, in the above step (3), the initiator is at least one of ammonium persulfate, potassium persulfate, sodium persulfate, benzoyl peroxide and azobisisobutyronitrile, preferably ammonium persulfate; the crosslinking agent is at least one of N,N-methylenebisacrylamide and trimethylolpropane triacrylate; and the mass ratio of acrylic acid, initiator and crosslinking agent is 18:0.972:0.07.

[0019] A further benefit of using the above-mentioned method is that ammonium persulfate efficiently initiates free radical polymerization, resulting in a high grafting rate. N,N-methylenebisacrylamide has longer graft chains (higher degree of polymerization) and a higher molecular weight, forming a looser three-dimensional network and providing ultra-high water absorption. Trimethylolpropane triacrylate has shorter graft chains (lower degree of polymerization) and a moderate molecular weight, forming a tighter network structure, emphasizing mechanical strength and adhesion.

[0020] Furthermore, in the above step (5), the organic solvent is at least one of cyclohexane and n-hexane; the dispersant includes Tween-80, NP-40 (ethylphenyl polyethylene glycol), polyethylene glycol-4000 (PEG4000) and polydimethylsiloxane; the mass ratio of cyclohexane, Tween-80, NP-40, polyethylene glycol-4000 and polydimethylsiloxane is 200:1.188:0.396:3.6:7.2.

[0021] A further beneficial effect of the above method is that the dispersant selected in the present invention can form stable suspension droplets, so that the finished product particles are uniform.

[0022] Furthermore, in the above step (5), the stirring condition is to introduce nitrogen for 30 minutes.

[0023] Furthermore, in the above step (5), the temperature of the temperature-raising reaction is 60-65° C., and the time is 3-4 h.

[0024] Furthermore, in the above step (5), the washing and dehydration reagent is anhydrous ethanol, and the number of times is 3-5 times.

[0025] Furthermore, in the above step (5), the drying equipment is a vacuum oven, the temperature is 60° C., and the drying time is 4-10 hours.

[0026] The present invention also claims protection for an inverse suspension acrylic acid grafted starch prepared by the above preparation method.

[0027] The present invention also claims protection for the use of the reverse suspension acrylic acid grafted starch prepared by the above preparation method in the preparation of gel patches and cosmetics.

[0028] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. The present invention adopts the inverse suspension polymerization method to synthesize acrylic acid grafted starch, which has the characteristics of uniform product particle size, high water and salt absorption rate, and easy reaction control.

[0030] 2. The present invention significantly reduces the viscosity of the system, improves heat dissipation and product morphology, directly obtains granular resin, and simplifies the post-processing process by dispersing the water phase in the oil phase.

[0031] 3. The acrylic acid grafted starch synthesized by the reverse suspension method of the present invention has a water absorption rate of up to 8 times (800%) of its own weight, which can effectively maintain the moist state of the gel patch, prevent drying and falling off, and prolong the drug release time.

[0032] 4. The three-dimensional network structure formed by the graft copolymerization of the present invention gives the material excellent flexibility and support, ensuring that the patch is not easily broken when the skin is bent and maintains structural integrity.

[0033] 5. The starch-based material selected in the present invention is naturally non-toxic and retains good skin affinity after acrylic acid grafting, making it suitable for long-term application and reducing the risk of allergies. DETAILED DESCRIPTION

[0034] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0035] Example 1

[0036] The preparation method of acrylic acid grafted starch by the reverse suspension method specifically comprises the following steps:

[0037] (1) Add 3.67 g corn starch to 60 g water, place in an 80°C water bath, and stir for 30 min under nitrogen protection to gelatinize to obtain gelatinized starch, which is set aside;

[0038] (2) Weighing 5.6 g of sodium hydroxide and adding it to 40 g of water, and cooling it to room temperature to obtain a sodium hydroxide solution;

[0039] (3) Weigh 18 g of acrylic acid into a beaker and slowly add it to a sodium hydroxide solution in a cold water bath for neutralization. After the neutralization heat dissipates, add 0.972 g of potassium persulfate and 0.07 g of N,N-methylenebisacrylamide and stir evenly to obtain a mixture A.

[0040] (4) adding mixture A to gelatinized starch and stirring uniformly to obtain mixture B;

[0041] (5) Add 200 g of cyclohexane to the reaction flask, followed by 1.188 g of Tween-80, 0.396 g of NP-40, 3.6 g of polyethylene glycol-4000, and 7.2 g of polydimethylsiloxane, and introduce nitrogen and stir for 30 min. Slowly add mixture B dropwise to the reaction flask using a peristaltic pump. After the addition is complete, move the mixture to a 65°C water bath and react for 3 h. Maintain a constant nitrogen flow rate throughout the entire process.

[0042] (6) The reaction flask was taken out, and the upper cyclohexane layer was poured out and stored in a beaker for recycling; the particles obtained by the reaction were poured into another beaker, and washed and dehydrated with anhydrous ethanol for 4 times. The product was placed in a vacuum oven at 60°C and dried after 10 hours of constant weight to obtain the reverse suspension method acrylic acid grafted starch.

[0043] Example 2

[0044] The preparation method of acrylic acid grafted starch by the reverse suspension method specifically comprises the following steps:

[0045] (1) Add 9.62 g corn starch to 60 g water, place in an 80°C water bath, and stir for 30 min under nitrogen protection to gelatinize to obtain gelatinized starch, which is set aside;

[0046] (2) Weighing 5.6 g of sodium hydroxide and adding it to 40 g of water, and cooling it to room temperature to obtain a sodium hydroxide solution;

[0047] (3) Weigh 18 g of acrylic acid into a beaker and slowly add it to a sodium hydroxide solution in a cold water bath for neutralization. After the neutralization heat dissipates, add 0.972 g of potassium persulfate and 0.07 g of trimethylolpropane triacrylate and stir evenly to obtain a mixture A.

[0048] (4) adding mixture A to gelatinized starch and stirring uniformly to obtain mixture B;

[0049] (5) Add 200 g of cyclohexane to the reaction flask, followed by 1.188 g of Tween-80, 0.396 g of NP-40, 3.6 g of polyethylene glycol-4000, and 7.2 g of polydimethylsiloxane, and introduce nitrogen and stir for 30 min. Slowly add mixture B dropwise to the reaction flask using a peristaltic pump. After the addition is complete, move the mixture to a 65°C water bath and react for 3 h. Maintain a constant nitrogen flow rate throughout the entire process.

[0050] (6) The reaction flask was taken out, and the upper cyclohexane layer was poured out and stored in a beaker for recycling; the particles obtained by the reaction were poured into another beaker, and washed and dehydrated with anhydrous ethanol for 4 times. The product was placed in a vacuum oven at 60°C and dried after 10 hours of constant weight to obtain the reverse suspension method acrylic acid grafted starch.

[0051] Example 3

[0052] The preparation method of acrylic acid grafted starch by the reverse suspension method specifically comprises the following steps:

[0053] (1) Add 60 kg of water to the reactor 1, start stirring and add 3.67 kg of corn starch, raise the temperature to 80 ° C, and stir for 30 minutes under nitrogen protection to gelatinize to obtain gelatinized starch, which is set aside;

[0054] (2) adding 40 kg of water to a dissolving kettle, weighing 5.6 kg of sodium hydroxide, slowly adding the solution and turning on the cooling, cooling to room temperature to obtain a sodium hydroxide solution;

[0055] (3) Weighing 18 kg of acrylic acid and slowly adding it to the sodium hydroxide solution in the dissolution kettle for neutralization reaction. After the neutralization heat dissipates, add 0.972 kg of potassium persulfate and 0.07 kg of N,N-methylenebisacrylamide and stir evenly to obtain a mixture A;

[0056] (4) Pumping mixture A into reactor 1 through a pipeline and mixing it with gelatinized starch to obtain mixture B;

[0057] (5) Add 200 kg of cyclohexane to reactor 2, followed by 1.188 kg of Tween-80, 0.396 kg of NP-40, 3.6 kg of polyethylene glycol-4000, and 7.2 kg of polydimethylsiloxane, and introduce nitrogen and stir for 30 min; slowly add mixture B dropwise to reactor 2 for 1 h; after the addition is complete, heat to 65 °C in a water bath and react for 3 h, keeping the nitrogen flow rate constant throughout the process;

[0058] (6) Filter, and keep the cyclohexane for recycling; pour the particles obtained by the reaction into the reactor 3, add anhydrous ethanol to wash and dehydrate 4 times, place the product in a vacuum oven at 60°C and dry it after 10 hours of constant weight, and then take it out to obtain the reverse suspension method acrylic acid grafted starch.

[0059] Example 4

[0060] The preparation method of acrylic acid grafted starch by the reverse suspension method specifically comprises the following steps:

[0061] (1) Add 60 kg of water to the reactor 1, start stirring and add 9.62 kg of corn starch, raise the temperature to 80 ° C, and stir for 30 minutes under nitrogen protection to gelatinize to obtain gelatinized starch, which is set aside;

[0062] (2) adding 40 kg of water to a dissolving kettle, weighing 5.6 kg of sodium hydroxide, slowly adding the solution and turning on the cooling, cooling to room temperature to obtain a sodium hydroxide solution;

[0063] (3) Weighing 18 kg of acrylic acid and slowly adding it to the sodium hydroxide solution in the dissolution kettle for neutralization reaction. After the neutralization heat dissipates, 0.972 kg of potassium persulfate and 0.07 kg of trimethylolpropane triacrylate are added and stirred uniformly to obtain a mixture A;

[0064] (4) Mixture A is pumped into reactor 1 through a pipeline and mixed with gelatinized starch to obtain mixture B

[0065] (5) Add 200 kg of cyclohexane to reactor 2, followed by 1.188 kg of Tween-80, 0.396 kg of NP-40, 3.6 kg of polyethylene glycol-4000, and 7.2 kg of polydimethylsiloxane, and introduce nitrogen and stir for 30 min; slowly add mixture B dropwise to reactor 2 for 1 h; after the addition is complete, heat to 65 °C in a water bath and react for 3 h, keeping the nitrogen flow rate constant throughout the process;

[0066] (6) Filter, and keep the cyclohexane for recycling; pour the particles obtained by the reaction into the reactor 3, add anhydrous ethanol to wash and dehydrate 4 times, place the product in a vacuum oven at 60°C and dry it after 10 hours of constant weight, and then take it out to obtain the reverse suspension method acrylic acid grafted starch.

[0067] Performance Testing

[0068] The acrylic acid grafted starch obtained by the reverse suspension method in Examples 1-4 was taken and its grafting rate, average particle size, water absorption rate and salt absorption rate (0.9% sodium chloride solution) were tested respectively.

[0069] Among them, after the acrylic acid grafted starch was extracted with a Soxhlet extractor for 48 hours, the grafting rate G was calculated according to the following formula:

[0070] G = (m1-m2) / m1×100%;

[0071] Where:

[0072] m1 is the mass of pure grafted material;

[0073] m2 is the mass of starch.

[0074] The results are shown in Table 1.

[0075] Table 1 Grafting rate, average particle size, water absorption rate and salt absorption rate of acrylic acid grafted starch of Examples 1-4

[0076]

[0077] As shown in Table 1, the grafting rate, average particle size, water absorption rate and salt absorption rate of the acrylic acid grafted starch of Examples 1-4 are relatively stable, and the performance of the product remains stable after scale-up production.

[0078] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing acrylic acid grafted starch by an inverse suspension method, characterized in that: The specific steps include: (1) Add starch to water, stir and gelatinize to obtain gelatinized starch, and set aside; (2) adding sodium hydroxide into water to obtain a sodium hydroxide solution; (3) first adding acrylic acid into sodium hydroxide solution for neutralization reaction, then adding initiator and cross-linking agent, stirring evenly to obtain mixture A; (4) adding mixture A to gelatinized starch and stirring uniformly to obtain mixture B; (5) Adding an organic solvent and a dispersant to the reaction flask, stirring evenly, adding the mixture B to carry out a temperature reaction, filtering, washing and dehydrating, and drying to obtain the reverse suspension method acrylic acid grafted starch.

2. The method for preparing acrylic acid grafted starch by an inverse suspension method according to claim 1, wherein In step (1), the starch is at least one of tapioca starch, corn starch and potato starch; and the mass ratio of the starch to water is (3.67-9.62):

60.

3. The method for preparing acrylic acid grafted starch by an inverse suspension method according to claim 1, wherein In step (1), the stirring and gelatinization conditions are as follows: nitrogen is introduced, the temperature is 60-80° C., and the time is 30 minutes.

4. The method for preparing acrylic acid grafted starch by an inverse suspension method according to claim 1, wherein In step (2), the mass ratio of the sodium hydroxide to water is 5.6:

40.

5. The method for preparing acrylic acid grafted starch by an inverse suspension method according to claim 1, wherein In step (3), the initiator is at least one of ammonium persulfate, potassium persulfate, sodium persulfate, benzoyl peroxide and azobisisobutyronitrile; the cross-linking agent is at least one of N,N-methylenebisacrylamide and trimethylolpropane triacrylate; the mass ratio of the acrylic acid, the initiator and the cross-linking agent is 18:0.972:0.

07.

6. The method for preparing acrylic acid grafted starch by an inverse suspension method according to claim 1, wherein: In step (5), the organic solvent is at least one of cyclohexane and n-hexane; the dispersant includes Tween-80, NP-40, polyethylene glycol-4000 and polydimethylsiloxane; the mass ratio of the cyclohexane, Tween-80, NP-40, polyethylene glycol-4000 and polydimethylsiloxane is 200:1.188:0.396:3.6:7.

2.

7. The method for preparing acrylic acid grafted starch by an inverse suspension method according to claim 1, wherein: In step (5), the stirring condition is to introduce nitrogen for 30 minutes; the temperature of the temperature-raising reaction is 60-65° C. and the time is 3-4 hours.

8. The method for preparing acrylic acid grafted starch by an inverse suspension method according to claim 1, wherein: In step (5), the washing and dehydration reagent is anhydrous ethanol, and the number of times is 3-5 times; the drying equipment is a vacuum oven, the temperature is 60°C, and the time is 4-10 hours.

9. An acrylic acid grafted starch obtained by the inverse suspension method according to any one of claims 1 to 8.

10. Use of the reverse suspension method acrylic acid grafted starch prepared by the preparation method according to any one of claims 1 to 8 in the preparation of gel patches and cosmetics.

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