Hydroxypropyl methylcellulose hollow capsule and preparation method thereof
By adding sorbitol as an excipient to the HPMC hollow capsules and controlling the residue on ignition, the salt spray problem under high residue conditions was solved, salt spray suppression and cost reduction were achieved under extreme storage conditions, and production efficiency and product quality stability were improved.
Patent Information
- Application Number
- CN202511009505.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-22
- Publication Date
- 2025-09-16
AI Technical Summary
Existing HPMC hollow capsules are prone to salt spray under high residue conditions, and the salt spray phenomenon is serious under extreme storage conditions, affecting the capsule appearance and filling on the machine. The existing technology requires strict control of ignition residue to avoid salt spray, but the raw material selection range is narrow and the cost is high.
By adding sorbitol as an excipient and controlling the ignition residue of HPMC to ≤1%, combined with specific stirring and drying conditions, HPMC hollow capsules are prepared. The excipient addition amount is 0.5-2% of the total mass of HPMC, which delays the occurrence of salt spray under extreme storage conditions.
It expands the selection range of HPMC ignition residue, reduces raw material costs, and is salt-free for 30 days under harsh conditions, improving production utilization and cost-effectiveness.
Smart Images
Figure CN120643527A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of pharmaceutical excipients, in particular to a hollow capsule of hypromellose and a preparation method thereof. Background Art
[0002] The existing technology has developed new hollow plant capsule products made from three different raw materials: cellulose ethers (such as hypromellose, etc.), plant polysaccharides (pullulan, alginic acid, etc.), and plant starches (such as modified corn starch, potato starch, and sweet potato starch). Among these raw materials, hypromellose (HPMC) has shown great potential for the development of hollow plant capsules due to its excellent performance. However, after long-term storage, a mist-like substance called "salt mist" will precipitate from the transparent capsule surface of the HPMC hollow capsule. The cause of the salt mist is related to the residual ion content in the HPMC. Sodium ions and chloride ions are introduced during the alkalization and neutralization stages of the HPMC preparation process. Due to different washing processes, the residual ion content is also different. The residual ion content can be represented by the ignition residue. Generally, the higher the ignition residue content, the larger the area of the salt mist in the prepared capsule and the shorter the time required. Therefore, the higher the ignition residue content of HPMC, the higher the probability of salt spray in the capsule. Since the residue of HPMC varies with the process, a method is needed to prevent salt spray from occurring in the capsule even when the residue content is high.
[0003] In addition, the appearance of salt mist is also related to the storage environment of the capsules. Under normal storage conditions (10-25°C, 30-60% RH), it takes a long time for the capsules to produce relatively mild salt mist. Under high temperature and low humidity conditions (35°C, 28% RH), the capsules will produce large areas of salt mist in a short period of time. If the capsules with salt mist are placed in conditions with higher humidity (70% RH), the salt mist in the capsules will gradually decrease or even disappear. Currently, the salt mist in the capsules mainly appears at the waist and inside of the capsules, with less salt mist on the top. Salt mist can affect the appearance of the capsules and also have a certain impact on the filling of the capsules. Existing technologies require strict limits on the ignition residue of HPMC (≤0.5%) to avoid salt mist, but the raw material selection range is narrow and the cost is high. There is an urgent need for a method that allows the use of high-residue HPMC (≤1%) and suppresses salt mist. Summary of the Invention
[0004] Technical problem to be solved: In response to the technical problems existing in the prior art, the present invention provides a hollow capsule and a preparation method that can expand the selection range of HPMC ignition residue, delay salt spray under extreme storage conditions (35°C, 28% RH), and prevent salt spray under conventional environments (25°C, 60% RH). The preparation success rate is high and the product quality is stable.
[0005] Technical solution: The method for preparing a hollow capsule of hypromellose according to the present invention comprises the following steps: Step 1, sol: Disperse the coagulant, gelling agent and excipients in 85°C hot water, stir at 1000 r / min until completely dissolved, and add HPMC; Step 2, curing the glue: stirring at 50-60°C, vacuum degree -0.04~-0.08 MPa, 40-60 r / min for 2-4 hours; Step 3: Capsule making: insert the mold into the glue solution and turn it over to make the gel shell; Step 4: Post-processing: drying, shelling, cutting, and fitting to obtain finished hollow capsules; The auxiliary material is sorbitol, and the addition amount is 0.5-2% of the total mass of HPMC; the ignition residue of the HPMC is ≤1%.
[0006] Preferably, the amount of the excipient added is 1% of the total mass of HPMC.
[0007] Preferably, the residue on ignition of the HPMC is 0.7%.
[0008] Preferably, the coagulant aid is potassium chloride, and the addition amount is 0.2-0.6% of the total mass of HPMC; the gelling agent is κ-carrageenan, and the addition amount is 1-3% of the total mass of HPMC.
[0009] Preferably, the weight proportions of the raw materials in step 1 are: 10-30 parts of HPMC, 90-160 parts of water, 1-3 parts of gelling agent, 0.2-0.6 parts of coagulant aid, and 0.5-2 parts of auxiliary materials.
[0010] Preferably, in step 3, the capsule making environment temperature is 20-35° C., the humidity is 25-60% RH, and the insulation temperature of the glue tank is 45-50° C.
[0011] The invention discloses a hollow capsule of hypromellose, which is prepared by the above method and has no salt mist when stored for 30 days under the conditions of 35° C. and 28% RH.
[0012] The invention also discloses an application of sorbitol in inhibiting salt spray of HPMC hollow capsules. The amount of sorbitol added is 0.5-2% of the total mass of HPMC, and the HPMC ignition residue of the hollow capsule is ≤1%.
[0013] Compared with the prior art, the present invention has the following beneficial effects: The preparation method of the present invention avoids the generation of salt mist in the hollow capsules of hypromellose, expands the selection range of raw materials, allows the use of high-residue HPMC (≤1%), and reduces the raw material cost by more than 20%. There is no salt mist for 30 days under harsh conditions (35°C, 28% RH). The trimmed scraps and products with substandard appearance can be recycled, thereby improving the utilization rate and reducing the production cost by 15%. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 This is a flow chart for preparing the hollow capsules of the present invention; Figure 2 Salt spray observation results of the film prepared in Example 1 of the present invention ((a) is the observation result on the 6th day; (b) is the observation result on the 30th day); Figure 3 Salt spray observation results of the film prepared in Example 2 of the present invention ((a) is the observation result on the 6th day; (b) is the observation result on the 30th day); Figure 4 Salt spray observation results of the film prepared in Example 3 of the present invention ((a) is the observation result on the 6th day; (b) is the observation result on the 30th day); Figure 5 The salt spray observation results of the film prepared in Example 4 of the present invention on the 30th day; Figure 6 The salt spray observation results of the film prepared in Example 5 of the present invention on the 30th day; Figure 7 The salt spray observation results of the film prepared in Example 6 of the present invention on the 30th day; Figure 8 Salt spray observation results of the film prepared in Comparative Example 1 of the present invention ((a) is the observation result on the first day; (b) is the observation result on the 30th day); Figure 9 Salt spray observation results of the film prepared in Comparative Example 2 of the present invention ((a) is the observation result on the first day; (b) is the observation result on the 30th day); Figure 10 The salt spray observation results of the film prepared in Comparative Example 3 of the present invention on the 30th day; Figure 11 The salt spray observation results of the film prepared in Comparative Example 4 of the present invention on the 30th day; Figure 12 The salt spray observation results of the film prepared in Comparative Example 5 of the present invention on the 30th day; Figure 13 Salt spray observation results of the film prepared in Comparative Example 6 of the present invention ((a) is the observation result on the 13th day; (b) is the observation result on the 30th day); Figure 14The salt spray observation results of the capsule samples prepared in the examples of the present invention on the 30th day ((a) is the sample of Example 4; (b) is the sample of Example 5; (c) is the sample of Example 6); Figure 15 30-day salt spray observation results of capsule samples prepared in the comparative examples of the present invention ((a) is the sample of comparative example 2; (b) is the sample of comparative example 5; (c) is the sample of comparative example 6). DETAILED DESCRIPTION
[0015] To make the purpose, technical solutions and advantages of the present invention clearer, the following Figures 1-15 The technical solution of the present invention is clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.
[0016] like Figure 1 As shown, the present invention discloses a method for preparing a hollow capsule of hypromellose, comprising the following steps: Step 1, sol: The raw materials are as follows: 10-30 parts HPMC, 90-160 parts water, 1-3 parts gelling agent, 0.2-0.6 parts coagulant, and 0.5-2 parts auxiliary materials. Disperse the coagulant, gelling agent, and auxiliary materials in 85°C hot water, stir at 1000 rpm until completely dissolved, and add HPMC (HPMC residue on ignition ≤ 1%). The auxiliary material is sorbitol, and the auxiliary material addition amount is 0.5-2% of the total HPMC weight; the coagulant is potassium chloride, and the addition amount is 0.2-0.6% of the total HPMC weight; the gelling agent is κ-carrageenan, and the addition amount is 1-3% of the total HPMC weight. Step 2, curing the glue: stirring at 50-60°C, vacuum degree -0.04~-0.08 MPa, 40-60 r / min for 2-4 hours; Step 3: Capsule making: In a capsule making environment with a temperature of 20-35°C, a humidity of 25-60% RH, and a gel tank insulation temperature of 45-50°C, the mold is inserted into the gelatin and turned over to form a gel shell; Step 4: Post-processing: drying, shelling, cutting and fitting to obtain the finished hollow capsules.
[0017] The invention discloses a hollow capsule of hypromellose, which is prepared by the above method and has no salt mist when stored for 30 days under the conditions of 35° C. and 28% RH.
[0018] The invention also discloses an application of sorbitol in inhibiting salt spray of HPMC hollow capsules. The amount of sorbitol added is 0.5-2% of the total mass of HPMC, and the HPMC ignition residue of the hollow capsule is ≤1%.
[0019] Example 1: 0.4g of κ-carrageenan, 0.24g of potassium chloride, and 0.1g of sorbitol (0.25%) were dispersed in 182mL of 85°C purified water. After complete dissolution, 40g of HPMC (0.7% residue on ignition) was added and stirred for 30 minutes to form a uniform and stable slurry. The dispersion system was closed, the sol was kept at 50°C, the stirring speed was controlled at 40r / min, and the vacuum system was activated. Stirring was continued at a vacuum of 0.08MPa for 2 hours. In the capsule making environment with a temperature of 35°C and a humidity of 28% RH, and the insulation temperature of the glue tank at 45°C, a scraper with a thickness of 0.8-1mm was selected to scrape the film on the acrylic plate (only to meet experimental requirements); the acrylic plate was placed in a forced air drying oven to dry, and a film with a thickness of 100±10μm was selected. The moisture content of the film was tested and then placed in an environment of 35°C and 28% RH to observe salt spray for up to 30 days.
[0020] Example 2: Disperse 0.8g of κ-carrageenan, 0.16g of potassium chloride, and 0.2g of sorbitol (0.5%) in 182mL of 85°C purified water. Stir continuously at 1000 rpm for 10 minutes until completely dissolved. Then, add 40g of HPMC (0.7% residue on ignition) and stir for 30 minutes to form a uniform and stable slurry. Close the dispersion system, maintain the sol tank at 55°C, control the stirring speed at 55 rpm, activate the vacuum system, and stir at a vacuum of 0.02 MPa for 3 hours. In the capsule making environment with a temperature of 21°C, humidity of 60% RH, and insulation temperature of the glue tank at 48°C, a scraper with a thickness of 0.8-1mm was selected to scrape the film on the acrylic plate (only to meet experimental requirements); the acrylic plate was placed in a forced air drying oven to dry, and a film with a thickness of 100±10μm was selected. The moisture content of the film was tested and then placed in an environment of 35°C and 28% RH to observe salt spray for up to 30 days.
[0021] Example 3: 1.2g of κ-carrageenan, 0.08g of potassium chloride, and 0.3g of sorbitol (0.75%) were dispersed in 182mL of 85°C purified water. After complete dissolution, 40g of HPMC (0.7% residue on ignition) was added and stirred for 30 minutes to form a uniform and stable slurry. The dispersion system was closed, the sol tank was kept at 60°C, the stirring speed was controlled at 60r / min, and the vacuum system was activated. Stirring was continued at a vacuum of -0.04MPa for 4 hours. In an encapsulation environment with a temperature of 21°C, a humidity of 60% RH, and a glue tank insulation temperature of 50°C, a scraper with a thickness of 0.8-1mm was selected to scrape the film on the acrylic plate (only to meet experimental requirements); the acrylic plate was placed in a forced air drying oven to dry, and a film with a thickness of 100±10μm was selected. The moisture content of the film was tested and then placed in an environment of 35°C and 28% RH for salt spray observation for up to 30 days.
[0022] Example 4: 1.0 g of κ-carrageenan, 0.2 g of potassium chloride, and 0.4 g (1%) of sorbitol were dispersed in 182 mL of 85°C purified water. After complete dissolution, 40 g of HPMC (0.7% residue on ignition) was added and stirred for 30 minutes to form a uniform and stable slurry. The dispersion system was closed, the sol tank was kept at 60°C, the stirring speed was controlled at 60 r / min, the vacuum system was activated, and stirring was continued for 4 hours at a vacuum of -0.04 MPa. In an encapsulation environment with a temperature of 21°C, a humidity of 60% RH, and a glue tank insulation temperature of 50°C, a scraper with a thickness of 0.8-1mm was selected to scrape the film on the acrylic plate (only to meet experimental requirements); the acrylic plate was placed in a forced air drying oven to dry, and a film with a thickness of 100±10μm was selected. The moisture content of the film was tested and then placed in an environment of 35°C and 28% RH for salt spray observation for up to 30 days.
[0023] Example 5: 1.2 g of κ-carrageenan, 0.24 g of potassium chloride, and 0.4 g (1%) of sorbitol were dispersed in 182 mL of 85°C purified water. After complete dissolution, 40 g of HPMC (0.7% residue on ignition) was added and stirred for 30 minutes to form a uniform and stable slurry. The dispersion system was closed, the sol tank was kept at 60°C, the stirring speed was controlled at 60 r / min, the vacuum system was activated, and stirring was continued at a vacuum of -0.04 MPa for 4 hours. In an encapsulation environment with a temperature of 21°C, a humidity of 60% RH, and a glue tank insulation temperature of 50°C, a scraper with a thickness of 0.8-1mm was selected to scrape the film on the acrylic plate (only to meet experimental requirements); the acrylic plate was placed in a forced air drying oven to dry, and a film with a thickness of 100±10μm was selected. The moisture content of the film was tested and then placed in an environment of 25°C and 60% RH to observe salt spray for up to 30 days.
[0024] Example 6: 1.2 g of κ-carrageenan, 0.24 g of potassium chloride, and 0.4 g (1%) of sorbitol were dispersed in 182 mL of 85°C purified water. After complete dissolution, 40 g of HPMC (1.0% residue on ignition) was added and stirred for 30 minutes to form a uniform and stable slurry. The dispersion system was closed, the sol tank was kept at 60°C, the stirring speed was controlled at 60 r / min, the vacuum system was activated, and stirring was continued for 4 hours at a vacuum of -0.04 MPa. In an encapsulation environment with a temperature of 21°C, a humidity of 60% RH, and a glue tank insulation temperature of 50°C, a scraper with a thickness of 0.8-1mm was selected to scrape the film on the acrylic plate (only to meet experimental requirements); the acrylic plate was placed in a forced air drying oven to dry, and a film with a thickness of 100±10μm was selected. The moisture content of the film was tested and then placed in an environment of 25°C and 60% RH to observe salt spray for up to 30 days.
[0025] Comparative Example 1: Disperse 0.4g of κ-carrageenan and 0.08g of potassium chloride in 182mL of 85°C purified water. Stir continuously at 1000r / min for 10 minutes until completely dissolved. Then, add 40g of HPMC with a 1.0% residue on ignition and stir for 30 minutes to form a uniform, stable slurry. Close the dispersion system, maintain the sol tank at 60°C, control the stirring speed at 55r / min, activate the vacuum system, and stir at a vacuum of 0.02MPa for 3 hours. In a capsule-making environment at 21°C and 60% RH, and a slurry tank at 47°C, use a scraper with a thickness of 0.8-1mm to scrape a film onto an acrylic plate (for experimental purposes only). Dry the acrylic plate in a forced-air drying oven. Films with a thickness of 100±10μm were selected and tested for moisture. The film was then placed in a 35°C, 28% RH environment and observed for salt spray for 30 days.
[0026] Comparative Example 2: Disperse 0.8g of κ-carrageenan and 0.16g of potassium chloride (1%) in 182mL of 85°C purified water. Stir continuously at 1000 rpm for 10 minutes until completely dissolved. Then, add 40g of HPMC with a 0.7% residue on ignition and stir for 30 minutes to form a uniform, stable slurry. Close the dispersion system, maintain the sol tank at 50°C, control the stirring speed at 40 rpm, start the vacuum system, and stir at a vacuum of 0.08MPa for 2 hours. In a capsule-making environment at 21°C and 60% RH, and a slurry tank at 45°C, use a scraper with a thickness of 0.8-1mm to scrape a film onto an acrylic plate (for experimental purposes only). Dry the acrylic plate in a forced-air drying oven. Films with a thickness of 100±10μm were selected and tested for moisture. The film was then placed in a 35°C, 28% RH environment and observed for salt spray for 30 days.
[0027] Comparative Example 3: Disperse 1.2g of κ-carrageenan and 0.24g of potassium chloride in 182mL of 85°C purified water. Stir continuously at 1000r / min for 10 minutes until completely dissolved. Then, add 40g of HPMC with a 0.5% residue on ignition and stir for 30 minutes to form a uniform, stable slurry. Close the dispersion system, maintain the sol tank at 60°C, control the stirring speed to 55r / min, start the vacuum system, and stir at a vacuum of -0.04MPa for 2 hours. In a capsule preparation environment at 21°C and 60% RH, and a slurry tank at 50°C, use a scraper with a thickness of 0.8-1mm to scrape a film onto an acrylic plate (for experimental purposes only). Dry the acrylic plate in a forced-air drying oven. Films with a thickness of 100±10μm were selected and tested for moisture. The film was then placed in a 35°C, 28% RH environment and observed for salt spray for 30 days.
[0028] Comparative Example 4: Disperse 1.2g of κ-carrageenan and 0.24g of potassium chloride in 182mL of 85°C purified water. Stir continuously at 1000r / min for 10min until completely dissolved. Then, add 40g of HPMC with a 0.4% residue on ignition and stir for 30min to form a uniform, stable slurry. Close the dispersion system, maintain the sol tank at 60°C, and control the stirring speed to 60r / min. Start the vacuum system and stir at a vacuum of -0.04MPa for 4h. In a capsule-making environment at 21°C and 60% RH, with the sol tank maintained at 50°C, use a scraper with a thickness of 0.8-1mm to scrape a film onto an acrylic plate (for experimental purposes only). Dry the acrylic plate in a forced-air drying oven. Films with a thickness of 100±10μm were selected and tested for moisture. The film was then placed in a 35°C, 28% RH environment and observed for salt spray for 30 days.
[0029] Comparative Example 5: Disperse 0.8g of κ-carrageenan and 0.16g of potassium chloride in 182mL of 85°C purified water. Stir continuously at 1000 rpm for 10 minutes until completely dissolved. Then, add 40g of HPMC with a 0.7% residue on ignition and stir for 30 minutes to form a uniform, stable slurry. Close the dispersion system, maintain the sol tank at 55°C, and control the stirring speed to 55 rpm. Start the vacuum system and stir at a vacuum of 0.02MPa for 3 hours. In a capsule-making environment at 21°C and 60% RH, with the sol tank maintained at 45°C, use a scraper with a thickness of 0.8-1mm to scrape a film onto an acrylic plate (for experimental purposes only). Dry the acrylic plate in a forced-air drying oven. Films with a thickness of 100±10μm were selected and tested for moisture. The film was then placed in a 25°C, 60% RH environment and observed for salt spray for 30 days.
[0030] Comparative Example 6: Disperse 0.8g of κ-carrageenan and 0.16g of potassium chloride in 182mL of 85°C purified water. Stir continuously at 1000r / min for 10 minutes until completely dissolved. Then, add 40g of HPMC with a 1.0% residue on ignition and stir for 30 minutes to form a uniform, stable slurry. Close the dispersion system, maintain the sol tank at 55°C, and control the stirring speed to 55r / min. Start the vacuum system and stir at a vacuum of 0.02MPa for 3 hours. In a capsule-making environment at 21°C and 60% RH, with the sol tank maintained at 50°C, use a scraper with a thickness of 0.8-1mm to scrape a film onto an acrylic plate (for experimental purposes only). Dry the acrylic plate in a forced-air drying oven. Films with a thickness of 100±10μm were selected and tested for moisture. The film was then placed in a 25°C, 60% RH environment and observed for salt spray for 30 days.
[0031] Film samples were prepared according to the preparation methods of Examples 1 to 6 and Comparative Examples 1 to 6 and subjected to salt spray observation. The observation results are shown in Table 1.
[0032] Table 1 Salt spray observation results of Examples 1 to 6 and Comparative Examples 1 to 6: .
[0033] As shown in Table 1, according to Examples 1 to 4 and Figure 2-Figure 5 It can be seen that with the increase of the amount of sorbitol added as an auxiliary material, the degree of salt spray gradually slowed down, and no salt spray occurred when the addition amount was 1%. Figures 8-11 It can be seen that when the ignition residue of HPMC is less than 0.5%, the film sample will not produce salt spray. Figure 6-Figure 7Compared with Comparative Examples 5, 6 and Figure 12-13 It can be seen that the conditions of 25℃ and 60%RH are conducive to slowing down the occurrence of salt spray on the film sample, but when the ignition residue is 1%, salt spray will still appear on the film sample.
[0034] The colloids obtained in Examples 4, 5, and 6 and Comparative Examples 2, 5, and 6 were prepared into capsules according to the capsule preparation and post-processing steps. The test standards for properties, firmness, friability, disintegration time, and moisture content were all tested in accordance with the requirements of the monograph on hypromellose in the 2020 edition of the Chinese Pharmacopoeia. In addition, the production process is described as a criterion for judging production feasibility. The specific test results are shown in Table 2, and the corresponding salt spray observation results are shown in Table 3.
[0035] Table 2 Test results of capsule samples of Example 4, Example 5, Example 6 and Comparative Example 2, Comparative Example 5, Comparative Example 6: .
[0036] Table 3 Salt spray observation results of capsule samples of Example 4, Example 5, Example 6 and Comparative Example 2, Comparative Example 5, Comparative Example 6: .
[0037] From Table 3 and Figure 14-15 Comparative Example 2 exhibited severe salt spray on day 1, while Example 4 remained free of salt spray until day 30, demonstrating that the addition of sorbitol can delay the generation of salt spray. A comparison of Examples 5 and 6 with Comparative Examples 5 and 6 shows that proper storage conditions and the addition of excipients can mitigate the generation of salt spray. However, even without the addition of excipients, salt spray still occurred when the residue on ignition of the capsule sample reached 1%. This demonstrates that the addition of excipients can broaden the range of HPMC options.
[0038] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for preparing a hollow capsule of hypromellose, characterized in that: The following steps are involved: Step 1, sol: Disperse the coagulant, gelling agent and excipients in 85°C hot water, stir at 1000 r / min until completely dissolved, and add HPMC; Step 2, curing the glue: stirring at 50-60°C, vacuum degree -0.04~-0.08 MPa, 40-60 r / min for 2-4 hours; Step 3: Capsule making: insert the mold into the glue solution and turn it over to make the gel shell; Step 4: Post-processing: drying, shelling, cutting, and fitting to obtain finished hollow capsules; The auxiliary material is sorbitol, and the addition amount is 0.5-2% of the total mass of HPMC; the ignition residue of the HPMC is ≤1%.
2. The method for preparing hollow capsules of hypromellose according to claim 1, wherein The amount of the excipient added is 1% of the total mass of HPMC.
3. The method for preparing hollow capsules of hypromellose according to claim 1, wherein The residue on ignition of the HPMC was 0.7%.
4. The method for preparing hollow capsules of hypromellose according to claim 1, wherein The coagulant is potassium chloride, and the addition amount is 0.2-0.6% of the total mass of HPMC; the gelling agent is kappa-carrageenan, and the addition amount is 1-3% of the total mass of HPMC.
5. The method for preparing hollow capsules of hypromellose according to claim 1, wherein The weight proportions of the raw materials in step 1 are: 10-30 parts of HPMC, 90-160 parts of water, 1-3 parts of gelling agent, 0.2-0.6 parts of coagulant aid, and 0.5-2 parts of auxiliary materials.
6. The method for preparing hollow capsules of hypromellose according to claim 1, wherein In step 3, the capsule making environment temperature is 20-35°C, the humidity is 25-60% RH, and the insulation temperature of the glue tank is 45-50°C.
7. A hollow capsule of hypromellose, characterized in that: The invention is prepared by the method according to any one of claims 1 to 6 and is stored at 35° C. and 28% RH for 30 days without salt fog.
8. An application of sorbitol in inhibiting salt spray of hollow hypromellose capsules, characterized in that: The added amount of sorbitol is 0.5-2% of the total mass of HPMC, and the HPMC ignition residue of the hollow capsule is ≤1%.