Gel composition, production method and application thereof

Abstract

The invention discloses a method for producing a gel composition, the gel composition and application of the gel composition. The method comprises the following steps: (1) reacting a gel precursor with a catalyst in a reactor to prepare sol; (2) mixing the sol with an active component to obtain a mixture; (3) dispensing the mixture into a receiving container and solidifying to form a gel composition encapsulating the active ingredient; wherein in the step (1), after the reaction is started, the temperature rise amplitude in the reactor is controlled not to exceed 20 DEG C. The produced hydrogel has the characteristic of long-term controlled release of active ingredients.

Description

Technical Field

[0001] The present disclosure relates to a gel composition, a method for producing the gel composition, and specific uses of the gel composition. More specifically, the present disclosure relates to the production of silica hydrogels, and in particular to embodiments for designing and manufacturing controlled release hydrogels. The present disclosure also relates to methods for industrially producing hydrogels of various formulations to meet their specific applications in odor inhibition of microbial activity. Background Art

[0002] The gel can be designed to continuously release various active ingredients to meet its specific use. Examples of such specific uses include disinfection, microbial inhibition, deodorization, etc. The gel produced by this method can play a role in its specific use for a long time.

[0003] Many gel compositions and their production methods (especially industrial production methods) in the existing technology still have some problems, such as complex production process, low production efficiency, high cost, difficulty in controlling the quality of gel products, and solidification in reactors and pipelines.

[0004] Therefore, to date, it remains a great technical challenge to develop an efficient and economical method to achieve the controlled release of active ingredients that control odors from microbial activities.

[0005] Silanol esters can react with water to hydrolyze to form silanol groups, which can further react with each other or with unhydrolyzed silanol esters to form a three-dimensional silica network in the liquid phase. In addition, colloidal silica suspensions can also form a three-dimensional gel skeleton through polycondensation. Currently, such inorganic silica gels or colloidal silica suspensions have not been used in active ingredients for controlling the odor of microbial activity. Summary of the invention

[0006] In order to solve at least one of the above problems, the present invention aims to provide an efficient method for producing a gel composition, in particular a large-scale production method (for example, the volume of the reaction system is at least 1L to 1 ton, preferably at least 2L to 1 ton, more preferably at least 5L to 1 ton). The present invention also provides a gel composition prepared by the above production method and its controlled release application in controlling the odor of microbial activity.

[0007] Specifically, the present invention provides:

[0008] A method for producing a gel composition, characterized in that it comprises the following steps:

[0009] (1) reacting a gel precursor with a catalyst in a reactor to prepare a sol;

[0010] (2) mixing the sol with an active ingredient to obtain a mixture;

[0011] (3) dispensing the mixture into a receiving container and solidifying to form a gel composition encapsulating the active ingredient;

[0012] The step (1) comprises controlling the temperature rise in the reactor to not exceed 20° C. after the reaction is started.

[0013] Optionally, the temperature rise in the reactor is controlled to not exceed 20°C by at least one of the following methods: pre-hydrolyzing the gel precursor mixture for at least 5 minutes before adding it to the reactor; providing a cooling water circulation system on the reactor; adding ice or ice water to the reactor no more than 10 minutes after the start of the hydrolysis reaction in the reactor; and continuously flowing the sol solution to at least one of an external pipeline static mixer no longer than 5 minutes after the start of the reaction.

[0014] Optionally, the method is a batch process and includes adding a solution of a gel precursor and a catalyst into a reactor at one time for hydrolysis, adding ice or ice water into the container during the hydrolysis process to control the temperature in the reactor and adjust the sol concentration to 10-20% by weight, mixing with the active ingredient after the hydrolysis is completed, and dispensing the resulting mixture solution into the container at one time.

[0015] The amount of ice added is 1-15 wt %, preferably 10-15 wt %, relative to the total weight of the reaction composition.

[0016] Optionally, the method is a continuous flow process, and comprises continuously reacting a solution of a gel precursor and a catalyst in a continuously stirred reactor, and continuously flowing the obtained sol solution into a pipeline static mixer outside the reactor to mix with an active ingredient, and then dispensing the obtained mixture into another container to solidify into a gel composition.

[0017] Optionally, the active ingredient is selected from at least one of a microbial disinfectant, a microbial inhibitor, a metabolic inhibitor and a deodorant, and the gel composition controls the release of the active ingredient to inhibit odor generated by microbial activity.

[0018] Optionally, the method further comprises the step of adding a cross-linking agent in step (2).

[0019] Optionally, the gel precursor is a silanol ester, preferably at least one of tetraethyl orthosilicate (TEOS), methyl orthosilicate (TMOS) and propyl orthosilicate (TPOS),

[0020] Optionally, the catalyst is selected from an acid hydrolysis catalyst or a base hydrolysis catalyst. The acid hydrolysis catalyst is preferably at least one of hydrochloric acid, nitric acid, and citric acid. The base hydrolysis catalyst is preferably at least one of ammonia water, sodium hydroxide, potassium hydroxide, and a base-stabilized colloidal silica suspension.

[0021] Optionally, the method further comprises the step of extruding the mixture to produce gel products of different sizes and shapes before dispensing into containers for solidification.

[0022] Optionally, relative to the total weight of the gel composition, the gel composition comprises:

[0023] 0.1-12% by weight of an active agent;

[0024] 5-35 wt.% of a silica matrix and

[0025] Optionally 0-20 wt% of a crosslinking agent.

[0026] Optionally, the method is a batch process, wherein the gel precursor and the catalyst are added to the reactor at one time for hydrolysis, the active ingredient is added to the reactor after the hydrolysis is completed, and the resulting mixture solution is then dispensed into the container at one time.

[0027] Optionally, the volume of the reaction system in the reactor is at least 1L to 1 ton, preferably at least 2L, more preferably at least 5L.

[0028] A gel composition prepared by any of the methods described above.

[0029] Any of the above gel compositions is used for controlling the dosage of the active ingredient to suppress odors caused by microbial activity.

[0030] The present invention has the following technical advantages:

[0031] 1) The present invention provides a method for industrially producing a hydrogel (e.g., silica gel) composition, wherein the produced hydrogel has the property of long-term controlled release of active ingredients. During the production process, the addition of catalysts such as acids and / or bases can accelerate the reaction, achieve uniformity, and enhance the performance of the hydrogel, thereby increasing its storage dose of active ingredients. The active ingredients are added during the preparation process and are encapsulated and stored in the gel network during the process.

[0032] 2) The method of the present invention can prevent the temperature from rising during large-scale reactions, thereby inhibiting the premature solidification of the sol after the reaction in the pipeline or reactor; and

[0033] 3) The method of the present invention requires simple equipment, is easy to operate, has fast material forming and low preparation cost.

[0034] BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A block diagram showing a production method according to an embodiment of the present invention.

[0036] Figure 2 The figures show the temperature curves of the reaction at (A) 2 times the stirring speed and different acid catalyst dosages in a batch reactor according to one embodiment of the present invention; (B) the temperature curves of the reaction at different stirring speeds at 1 times the acid catalyst dosage; and (C) the concentration diagram of the gel precursor and the ethanol product during the hydrolysis reaction in the batch reactor.

[0037] Figure 3 Schematic diagram showing the preparation of a gel composition by a batch process according to one embodiment of the present invention. Notes: 1. The gel precursor solution reacts while monitoring the temperature increase; 2. Ice cubes are added to cool the reaction and adjust the sol concentration; 3. Active ingredients are added and hydrogel is formed; 4. Thermometer; 5. Reactor; 6. Silica hydrogel.

[0038] Figure 4 A photograph showing (A) a batch reactor equipped with a cooling jacket and an axially positioned agitator, (B) monitoring the temperature of the batch reactor and adding ice cubes for cooling before mixing the active ingredient, and (C) collecting the hydrogel product containing the active ingredient in a basin in a method of preparing a gel composition by a batch process.

[0039] Figure 5 A schematic diagram of (A) a continuous flow production method and (B) a continuous flow production method including an additive adding step according to the present invention is shown, wherein 52 represents a gel precursor solution tank, 51 represents a gel precursor solution, 54 represents an acid or base catalyst, 53 represents a catalyst tank, 56 represents an active ingredient, 57 represents an active ingredient tank, and 60 represents an additive, 59 represents an additive tank, 55 represents a continuous stirring reactor, 552 represents a thermometer, 551 represents a cooler, 58 represents a gel mold, and 553 represents cooling water.

[0040] Figure 6 A photograph showing a bench test setup for continuous flow production according to one embodiment of the present invention, wherein 1: TEOS, 2: acid catalyst; 3: cold water; 4: pump for TEOS solution; 5: pump for acid; 6: pump for cold water; 7: pump for outlet flow; 8: agitator; 9: jacketed reactor.

[0041] Figure 7 A photograph showing a continuous flow production unit according to one embodiment of the present invention.

[0042] Figure 8The graph shows the temperature variation curve of the reactor at the beginning of the continuous flow production process according to one embodiment (Example 9) of the present invention.

[0043] Fig. 9 The reactor temperature variation curves of Example 1, Example 8 and Example 2 are shown respectively.

[0044] Fig.10 ATR-FTIR spectra of silica gel compositions prepared by (A) the batch production process of Example 1 and (B) the continuous flow production process of Example 2 are shown.

[0045] Fig.11 Shown are (A) a schematic diagram of the continuous flow production process of shaped silicone hydrogels containing active agents, and a photograph of an extrusion nozzle showing the (B) inlet, (C) contour shape, and (D) outlet.

[0046] Fig.12 Shown are photographs of extruded silicone hydrogels containing active ingredients in (A) spherical and (B) cylindrical shapes; (C) different colors, and (D) sizes.

[0047] Fig.13 Photographs of the gel compositions obtained are shown respectively: A-Comparative Example 1, B-Example 1, and C-Example 2.

[0048] Fig.14 The release concentrations of the active ingredients (represented by zinc salt and copper salt) of the gel compositions prepared in Examples 1-3 at different times are shown. DETAILED DESCRIPTION

[0049] The following definitions are used to understand the present invention and to construct the claims.

[0050] Unless otherwise specified, the singular forms "a" and "an" in the present invention also include the plural meaning.

[0051] The "gel composition" in the specification and claims may refer to both the initial mixed system (whose viscosity will gradually increase over time and transform into a solid gel within a specific time) and the final hydrogel encapsulating the active agent. Therefore, the term "composition for controlling the dosage of the active agent released to inhibit the odor generated by the activity of microorganisms" may be understood as the gel composition of the active agent used herein.

[0052] The "active ingredient" in the present invention may include any active substance used for disinfection, microbial inhibition, deodorization, etc., such as at least one of a microbial disinfectant, a microbial inhibitor, a metabolic inhibitor and a deodorant, which can inhibit odors generated by microbial activity.

[0053] The "sol" in the present invention may include a reaction mixture consisting of an aqueous solution of a gel precursor (eg, silanol ester) and an acidic or basic catalyst.

[0054] The "active ingredient" in the present invention may include a single active substance as well as a mixture of multiple active ingredients.

[0055] In the present invention, the structure / skeleton of the gel is an inorganic silica network composed of silica sol, which can be prepared by hydrolyzing silanol esters or a colloidal silica suspension. Further polycondensation reactions cause the silica sol to grow, aggregate and crosslink, and after a period of time, the expansion of the silica network will cause the entire sol system to solidify.

[0056] Unless otherwise defined, the meanings of technical and scientific terms used in the present invention are consistent with those commonly recognized by those skilled in the art.

[0057] In order to better understand the content of the present invention and not to limit the content of the present invention, unless otherwise specified, all numbers including quantities, percentages and ratios in the present invention are approximate values, which are obtained from experimental data according to the properties of the corresponding parameters and based on the conventional principle of rounding off significant figures.

[0058] like Figure 1 As shown, the preparation of the gel composition involves a hydrolysis process (S1) of a gel precursor 11 (e.g., a silanol ester) in the presence of a catalyst 12 (e.g., an acid or base catalyst). After the hydrolysis, a polymerization process (S2) is also included to form a sol (e.g., a silica sol). After S2, an active ingredient 13 can be added, and then the active ingredient is encapsulated in the sol (e.g., a silica sol) in S3. Optionally, an additive 14 (e.g., a cross-linking agent) can also be added after S3. S4 involves a condensation polymerization process. The condensation polymerization reaction causes the sol to grow, aggregate, and cross-link, which further firmly encapsulates the active ingredient and optional additives (e.g., a cross-linking agent) in the sol. The sol can then be discharged into another container for aging / forming (S5), thereby forming a hydrogel (e.g., a silica hydrogel) encapsulating the active ingredient and / or the inert additive 14.

[0059] In the hydrolysis of the gel precursor and other reactions, the reaction temperature may be significantly increased, which may lead to the production of overly viscous silica sol or even pre-gelation, which is not conducive to the subsequent preparation process. This is especially true in large-scale production or industrial production.

[0060] Therefore, in one aspect, the present invention provides a method for producing a gel composition, comprising the following steps: (1) reacting a gel precursor with a catalyst in a reactor to prepare a sol; (2) mixing the sol with an active ingredient to obtain a mixture; (3) dispensing the mixture into a receiving container and solidifying it to form a gel composition encapsulating the active ingredient. Preferably, step (1) comprises controlling the temperature rise in the reactor to not exceed 20°C, preferably not exceed 10°C, more preferably not exceed 5°C, or not exceed 2°C after the reaction is started.

[0061] The temperature rise in the reactor can be controlled to not exceed 20°C in a variety of ways, including pre-hydrolyzing the gel precursor for at least 5 minutes before adding it to the reactor; providing a cooling water circulation system on the reactor; adding ice or ice water to the reactor no more than 10 minutes after the hydrolysis reaction in the reactor is started; and continuously flowing the sol solution to at least one of an external pipeline static mixer no longer than 5 minutes after the reaction is started.

[0062] The above methods can be combined, for example, starting the cooling water circulation system and continuously flowing the sol solution to the external pipeline static mixer; setting a cooling water circulation system on the reactor and adding ice or ice water into the reactor no more than 10 minutes after the hydrolysis reaction in the reactor is started.

[0063] The cooling water circulation system may include a cooling jacket surrounding the reactor, a cooler, and a pipe connecting the cooling jacket and the cooler, wherein the cooling water circulates among the cooling jacket, the pipe, and the cooler.

[0064] In one embodiment, the method for producing the gel composition is a batch process, comprising adding a solution of a gel precursor and a catalyst into a reactor at one time, adding ice or ice water into the container to keep the temperature rise less than 2° C. and adjusting the sol concentration to 10-20% by weight before mixing with the active ingredient. The resulting mixture solution can then be dispensed into another container at one time.

[0065] In another embodiment, the method for producing the gel composition is a continuous flow process, comprising continuously reacting a gel precursor solution and a catalyst in a continuously stirred reactor, and continuously flowing the obtained sol into a pipeline static mixer outside the reactor to be mixed with an active ingredient, and then dispensing the obtained mixture into containers to solidify into a gel composition.

[0066] In another embodiment, the method for producing the gel composition is a batch process, comprising pre-hydrolyzing the gel precursor outside the reactor for at least 5 minutes, adding the pre-hydrolyzed precursor and the catalyst to the reactor at one time, adding the active ingredient to the reactor, and then dispensing the resulting mixture solution into the container at one time.

[0067] In the present invention, the preferred gel composition is a silica hydrogel composition. The production of the silica hydrogel composition involves a series of complex processes and reactions ( Figure 1 ), and the heat generated may cause premature gelation. To avoid premature gelation, corresponding countermeasures need to be established in the design and operation of batch and continuous flow production lines. Batch production can use ice water in the reaction to quickly cool the mixture and delay the gelation process, while in the continuous flow production process, the pre-hydrolyzed sol can be quickly mixed with the active ingredient in the pipeline static mixer, which can also quickly dissipate heat. Hydrogels can be molded into different sizes and shapes before solidification by using container molds or through extrusion processes.

[0068] Figure 2 It is shown that at different amounts of acid catalyst ( Figure 2 A) and different solution mixing speeds ( Figure 2 B) under the temperature change curve of intermittent hydrolysis of gel precursor. The extent of the reaction is determined by monitoring the concentration of gel precursor and ethanol product ( Figure 2 C). More acid catalyst ( Figure 2 A) and faster mixing speed ( Figure 2 B) Rapidly generate heat and produce ethanol as the gel precursor is converted ( Figure 2 C).

[0069] Figure 3 and Figure 4 The use of ice water as a hydrolysis reactant to reduce the reaction temperature and adjust the sol concentration to prevent the mixture from freezing rapidly and uncontrolled. Figure 3 As shown, the process includes: 1. reacting the gel precursor solution while monitoring the temperature rise; 2. adding ice cubes to cool the reaction and adjust the sol concentration; 3. adding the active ingredient and forming a hydrogel, such as silica hydrogel 6. Specifically, the process involves hydrolyzing the gel precursor with water in a well-stirred batch reactor using an acid or base catalyst, and cooling by the cooling jacket of the reactor to slow down the temperature rise. The temperature of the reactor 5 needs to be monitored (monitored by a thermometer 4), and before adding the active ingredient, ice cubes are added in a certain amount (0-30 weight %) to keep its temperature rise less than 20°C, and at the same time adjust the concentration of the sol (at 10-20 weight %). Then, the mixture is evenly mixed and distributed into a receiving container for solidification. Figure 4 A batch reactor ( Figure 4 A) Add ice cubes to cool down ( Figure 4 B) and a photograph of the solidified hydrogel product containing the active ingredient.

[0070] In the present invention, the gel precursor is preferably a silanol ester. The present invention can use silanol esters prepared by methods in the art or commercial products, and silanol esters include but are not limited to tetraethyl orthosilicate (TEOS), methyl orthosilicate (TMOS) and propyl orthosilicate (TPOS). Considering the material cost and reaction properties, tetraethyl orthosilicate is a preferred silanol ester. The silanol ester reacts with water to generate silicon hydroxide through hydrolysis, and the silicon hydroxides or the unhydrolyzed silanol esters react to form a three-dimensional silicon oxide network in a liquid medium through a polycondensation reaction, while releasing water and / or alcohol molecules.

[0071] Optionally, the catalyst is selected from an acid hydrolysis catalyst or a base hydrolysis catalyst, the acid hydrolysis catalyst is preferably at least one of hydrochloric acid, nitric acid, and citric acid, and the base hydrolysis catalyst is preferably at least one of ammonia water, sodium hydroxide, potassium hydroxide, and a base-stabilized colloidal silica suspension.

[0072] Before adding to the reactor, the gel precursor can be mixed with a liquid medium to obtain a precursor solution. The gel precursor and the liquid medium can also be pre-hydrolyzed before adding to the reactor, and the pre-hydrolyzate is then added to the reactor. The liquid medium can be water, alcohol, and other water-soluble solvents. The presence of an acid or base can accelerate the above-mentioned hydrolysis and polycondensation process. Under appropriate conditions, an inorganic silicon oxide matrix is ​​obtained, which can be a transparent self-supporting gel immobilized with a liquid medium.

[0073] Figure 5 Schematic diagrams of two continuous flow production processes for gel compositions (e.g., silica hydrogel compositions) are shown. The process is designed to solve the problem of rapid temperature rise during the reaction to prevent the mixture from solidifying in the reactor and pipeline, thereby producing a more uniform product. Figure 5 A shows a production process consisting of three well-stirred tanks 52, 53 and 57, each of which contains a gel precursor (such as a silanol ester, preferably also containing a liquid medium such as water), a dilute acid or alkaline catalyst solution in water, and a solution of an active ingredient. The active ingredient includes a microbial disinfectant such as sodium chlorite, sodium or potassium, sodium hypochlorite or potassium hypochlorite, sodium nitrite, Cooper's salt, polyhexamethylene biguanide; metabolic inhibitors (e.g., essential oils, polyphenols, polycarboxylic acids, zinc salts, copper salts) and deodorants (e.g., sodium nitrite, chlorine dioxide, permanganate). The selection of the active ingredient is based on its ability to reduce the viability of microorganisms and slow down their metabolism, thereby inhibiting the generation of malodorous gases.

[0074] The gel precursor solution 51, the acid or base catalyst 54 and the liquid medium (e.g., water) are mixed in the reactor 55 and stirred continuously to generate a sol. The reactor 55 can dissipate the heat generated by the hydrolysis reaction through a circulating water cooling system 551 (containing cooling water 553) including a cooling jacket. The short residence time (<5 minutes) also limits the heat that can be generated in the reactor 55. The sol is then pumped through a finned pipeline static mixer to uniformly mix the sol and the active ingredient 56, and finally distributed to another collection tank 58 (i.e., a gel mold) for solidification. Figure 6 is based on Figure 5 Photograph of the benchtop unit constructed by A.

[0075] exist Figure 5 The process in B also includes an additional tank 59 containing additives 60. The additives include colloidal silica, alumina sol, polymers and surfactants, which are used to change the strength, surface charge, elasticity and porosity of the silica gel to control its hardness, compatibility, durability and release rate. Figure 7 is based on Figure 5 B Photo of the continuous production unit established.

[0076] Figure 8 The reactor temperature curve at the start-up of a continuous production device according to one embodiment of the present invention (Example 9) is shown. First, the gel precursor solution is added to the reactor under stirring (200 rpm), and a small amount of catalyst (0.01-1 weight %) is added to initiate the reaction. 1 represents 0 seconds: stirring (200 rpm) is started. Then, the temperature rises rapidly with the reaction. 2 represents 450 seconds: the temperature rises rapidly. The temperature of the reactor is allowed to rise to 60°C to initiate the hydrolysis reaction. 3 represents 540 seconds: the hydrolysis is completed, and the peak temperature is 60.9. Once the temperature begins to drop, the flow process can be started. During the initial flow process, the temperature will rise by 10°C more gently. 4 represents 2415 seconds: TEOS and acid are continuously added (the temperature begins to rise). 5 represents that the cooling caused by the continuous flow can maintain the temperature at 30.9°C. 6 represents 3735 seconds: the addition of TEOS and acid is stopped (the temperature begins to drop). About 15 minutes after the flow starts, the temperature of the reactor will stabilize at about 25±2°C.

[0077] Fig. 9 The temperature variation curves of the reactors of Example 1, Example 8 and Example 2 are shown respectively. Fig. 9 As shown, the temperature rise of the continuous production with a cooling water circulation system (Example 2, i.e. 93) is negligible compared to the batch production process with the addition of ice (Example 1, i.e. 91) or the pre-hydrolyzed precursor (Example 8, i.e. 92). Fig.10According to the ATR-FTIR (Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy) analysis in the experiment, the quality and chemical properties of the silica hydrogels produced by the batch (Example 1) and the continuous production process (Example 2) are comparable.

[0078] Fig.11 A is a schematic diagram showing a continuous production process for extruding and forming hydrogels of different shapes and sizes. The continuous production process includes a continuous production device, which includes a continuous stirred tank reactor 112 equipped with a cooling jacket (which is connected to incoming cold water 114 and outgoing hot water 115), used to hydrolyze the gel precursor to produce a sol 113 (for example, a hydrolyzed TEOS solution) and a container 115 for containing an active ingredient and an alkaline catalyst. Thermometer 111 is used to monitor the temperature of reactor 112. The sol and the active ingredient are pumped into a three-way pipe 117 by a pump 116 and enter a pipeline static mixer 114 for mixing, and the product is extruded through a nozzle, such as Fig.11 BD. The extrudate is allowed to solidify in an oil column 117. Fig.12 AB show different spherical and cylindrical shapes of cured hydrogels produced by this method. Fig.12 The CD also shows the different colors and sizes that can also be made.

[0079] In another aspect, the present invention also provides a gel composition prepared by the method.

[0080] For example, the gel composition prepared according to the method of the present invention may contain 0.1-12 wt % of an active agent; 5-35 wt % of a silica matrix and optionally 0-20 wt % of an additive.

[0081] In a third aspect, there is also provided a use of the gel composition for controlling the dosage of the released active ingredient to inhibit odors generated by microbial activities.

[0082] Preferably, the present invention provides a method for producing a silica hydrogel, wherein the produced silica hydrogel has the characteristics of long-term controlled release of active ingredients. The silica hydrogel is composed of a silica precursor, which forms a silica cross-linked network through reaction, which is used to store and release specific active ingredients. The addition of acid and / or base catalysts can accelerate the reaction, achieve uniformity, and enhance the performance of silica to increase its storage dose of active ingredients. The active ingredient can be added during the preparation process and is encapsulated and stored in the silica gel network during the process.

[0083] The production method of silica hydrogel includes, but is not limited to, hydrolysis of silica precursor, addition of active ingredient, addition of silica sol, and gelation of the product. The batch production method includes hydrolyzing the silica precursor, adding cold water or ice water to reduce its temperature, adding the active ingredient and mixing rapidly, and finally dispensing into a container and gelling into a solidified silica hydrogel. The continuous production method includes hydrolyzing the silica precursor and an acid or base catalyst in a continuously stirred tank reactor to produce a pre-hydrolyzed sol. The sol is mixed with the active ingredient and colloidal silica through a pipeline static mixer, and dispensed into a container to gel into a solidified silica hydrogel, or molded into different shapes, including spheres, through an extrusion process.

[0084] example

[0085] In the following examples, the volume of the reaction system was 1 L or more.

[0086] Example 1

[0087] like Figure 4 As shown in FIG. 1 , a controlled-release hydrogel composition for inhibiting odors from microorganisms is prepared by batch production. First, Figure 4 In the reactor in A, 35.0 wt% of a mixture of tetraethyl orthosilicate (98% purity) and water was added and hydrolyzed relative to the total weight of the reaction mixture. Under rapid stirring (200 rpm), 10 wt% of an acid catalyst (i.e., 0.14 M nitric acid) was added to initiate the reaction. Figure 4 As shown in Figure B, the reaction is cooled by adding ice (15 wt%), and the concentration of silica sol is also adjusted to less than 20 wt%. Then, a microbial disinfectant, a metabolic inhibitor and a deodorant, including sodium chlorite, thyme oil, copper and zinc salts, are added to the reactor to obtain a mixture. The mixture is distributed to a solidification container and solidified to obtain a malodor control (MOC) hydrogel, which contains 0.6 wt% sodium chlorite, 1 wt% thyme oil, 1.7 wt% copper salt, 2.1 wt% and zinc salt and 10 wt% silica matrix, and the remaining components are water. The obtained hydrogel composition is as shown in Figure B. Figure 4 As shown in C.

[0088] Example 2

[0089] Controlled-release hydrogels for inhibiting odors of microbial origin were prepared by continuous flow method ( Figure 7), first, relative to the total weight of the reaction mixture, 35.0 wt% tetraethyl orthosilicate (purity 98%) and 0.014 M nitric acid aqueous solution are added to a continuously stirred (200 rpm) tank reactor for reaction to generate a silica sol, wherein the tank reactor is equipped with a cooling water circulation system. Then, the sol solution is continuously flowed into a pipeline and mixed with the active ingredient during passing through a pipeline static mixer. The mixture is distributed into a solidification container and solidified to generate an odor control (MOC) hydrogel composition, which contains 0.6 wt% sodium chlorite, 1 wt% thyme oil, 1.7 wt% copper salt, 2.1 wt% zinc salt and 10 wt% silica matrix, and the remaining components are water.

[0090] Example 3

[0091] like Figure 4 As shown, a controlled-release hydrogel composition for microbial disinfection is prepared by batch production. First, Figure 4 In a reactor, 35.0 wt% of a mixture of tetraethyl orthosilicate (98% purity) and water was added and hydrolyzed relative to the total weight of the reaction mixture. Under rapid stirring (200 rpm), 10 wt% of an acid catalyst (i.e., 0.14 M nitric acid) was added to initiate the reaction. The reaction was cooled by adding ice (10 wt%), and the silica sol concentration was adjusted to less than 20 wt%. Microbial disinfectants including sodium chlorite, citric acid, copper salts and zinc salts were then added to the reactor, and the resulting mixture was distributed into a solidification container to produce an antibacterial (AM) hydrogel composition containing 2 wt% of sodium chlorite, 1.1 wt% of citric acid, 0.5 wt% of copper salts, 0.5 wt% of zinc salts and 10 wt% of a silica matrix, and the remaining components were water.

[0092] Example 4

[0093] Controlled-release hydrogels for microbial disinfection were prepared by continuous flow method ( Figure 7 ), first, relative to the total weight of the reaction mixture, 35% tetraethyl orthosilicate (purity 98%) and 0.014M nitric acid aqueous solution are injected into a continuously stirred (200 rpm) tank reactor for reaction to generate silica sol. The sol is continuously flowed into a pipeline and mixed with the active ingredient during passing through a pipeline static mixer. The mixture is distributed into a solidification container and solidified into an antibacterial (AM) hydrogel composition, which contains 2% by weight of sodium chlorite, 1.1% by weight of citric acid, 0.5% by weight of zinc salt and 10% by weight of a silica matrix, and the remaining components are water.

[0094] Example 5

[0095] like Figure 4As shown, a controlled-release hydrogel composition for microbial disinfection is prepared by batch production. First, Figure 4 In a reactor in the reactor, 35.0 wt% of a mixture of tetraethyl orthosilicate (98% purity) and water is added and hydrolyzed relative to the total weight of the reaction mixture. Under rapid stirring (200 rpm), 10 wt% of an acidic catalyst (i.e., 0.14 M nitric acid) is added to initiate the reaction. The reaction is cooled by adding ice (15 wt%), while the silica sol concentration is adjusted to less than 20 wt%. Sodium nitrite is then added to the reactor, and the resulting mixture is distributed to a solidification container, and a deodorant hydrogel composition containing 10 wt% of sodium nitrite and 20 wt% of a silica matrix is ​​produced, with the remainder being water.

[0096] Example 6

[0097] Controlled-release hydrogels for deodorization were prepared by continuous flow method ( Figure 7 ), first, relative to the total weight of the reaction mixture, 35.0 wt% of tetraethyl orthosilicate (purity 98%) and 0.014 M nitric acid aqueous solution are injected into a continuously stirred (200 rpm) tank reactor for reaction to generate silica sol, wherein the tank reactor is equipped with a cooling water circulation system. The sol is continuously flowed into a pipeline, and the sol is mixed with the active ingredient during the passage through the pipeline static mixer. The obtained mixture is distributed into a solidification container and solidified into a deodorant hydrogel composed of 10 wt% of sodium nitrite and 20 wt% of silicon dioxide, and the remaining component is water.

[0098] Example 7

[0099] Controlled-release hydrogels for deodorization were prepared by continuous flow method ( Figure 7 ), first, relative to the total weight of the reaction mixture, 35.0 wt% of tetraethyl orthosilicate (purity 98%) and 0.014 M nitric acid aqueous solution were injected into a continuously stirred (200 rpm) tank reactor for reaction to generate silica sol. The sol was continuously flowed into a pipeline, and the sol was mixed with the active ingredient through a pipeline static mixer. Fig.12 As shown, the mixture is extruded into different shapes and solidified to obtain a deodorant hydrogel. The hydrogel contains 5 wt % of sodium nitrite and 10 wt % of silicon dioxide, and the remaining component is water.

[0100] Example 8

[0101] The gel composition of Example 8 was prepared substantially according to the method of Example 1, except that before adding to the reactor, a mixture of 35.0 wt % tetraethyl orthosilicate (98% purity) and water was first hydrolyzed in another container for 5 minutes, and then the pre-hydrolyzed reactants were added to the reactor for reaction.

[0102] Example 9

[0103] The gel composition of Example 9 was prepared substantially according to the method of Example 2, except that the cooling water circulation system was closed.

[0104] Comparative Example 1

[0105] like Figure 4 As shown in FIG. 1 , a controlled-release hydrogel composition for inhibiting odors from microorganisms is prepared by batch production. First, Figure 4 In a reactor in the reactor, a mixture of 35.0% by weight of tetraethyl orthosilicate and water was added and hydrolyzed. Under rapid stirring (200 rpm), 10% (by weight) of an acidic catalyst (i.e., 0.14M nitric acid) was added to initiate the reaction. After 30 minutes of reaction, microbial disinfectants, metabolic inhibitors, and deodorants, including sodium chlorite, thyme oil, copper, and zinc salts, were added to the reactor. As a result, the reaction mixture gelled prematurely in the reactor, resulting in the inability to encapsulate the active ingredient and the inability to flow out of the reactor.

[0106] Test Case

[0107] 1. Visual observation

[0108] The appearance of the gel compositions obtained in Examples 1 to 9 was observed with the naked eye. The results are shown in Table 1 below.

[0109] 2. Release test

[0110] 100 g of the hydrogels of Examples 1 to 3 were placed in a container with a stable continuous water flow of 190 ml / min and run for 24 hours. The water was sampled at 5 minutes, 4 hours, 12 hours and 24 hours, and the content of active ingredients such as Cu salt and Zn salt in the water was analyzed by ICP-OES (Varian 725-ES) to estimate the release rate. The results are shown in Fig.14 And Table 1.

[0111] Table 1

[0112]

[0113]

[0114] It can be seen from the data in Table 1 that by controlling the temperature rise in the reactor to not exceed 20° C. after the reaction is started, the gel composition can be prevented from solidifying prematurely in the reactor, and a gel or gel product that effectively encapsulates the active ingredient can be obtained. It can be seen from Examples 1, 2, 3 and 8 that the continuous production method of pre-hydrolyzing the gel precursor mixture for at least 5 minutes before adding it to the reactor or setting a cooling water circulation system on the reactor can better control the temperature rise, thereby obtaining a gel composition that completely encapsulates the active ingredient and better controlling the release of the active ingredient.

[0115] For the subject matter described so far, it is obvious that the same modification or variation may be made in many ways. Such modifications and variations should not be regarded as departing from the spirit and scope of the subject matter, and all such modifications and variations are included within the scope of the claims.

Claims

1. A method for producing a gel composition, Features The following steps are involved: (1) reacting a gel precursor with a catalyst in a reactor to prepare a sol; (2) mixing the sol with an active ingredient to obtain a mixture; (3) dispensing the mixture into a receiving container and solidifying to form a gel composition encapsulating the active ingredient; The step (1) comprises controlling the temperature rise in the reactor to not exceed 20° C. after the reaction is started.

2. The method according to claim 1, Features The temperature rise in the reactor is controlled to not exceed 20°C by at least one of the following methods: pre-hydrolyzing the gel precursor mixture for at least 5 minutes before adding it to the reactor; providing a cooling water circulation system on the reactor; adding ice or ice water into the reactor no more than 10 minutes after the hydrolysis reaction in the reactor is started; and continuously flowing the sol solution to at least one of the external pipeline static mixers no longer than 5 minutes after the reaction is started.

3. The method according to claim 1 or 2, Features The method is an intermittent process and includes adding a solution of a gel precursor and a catalyst into a reactor at one time for hydrolysis, adding ice or ice water into the container during the hydrolysis process to control the temperature in the reactor and adjust the sol concentration to 10-20% by weight, mixing with the active ingredient after the hydrolysis is completed, and dispensing the resulting mixture solution into the container at one time.

4. The method according to claim 1 or 2, Features The method is a continuous flow process and comprises continuously reacting a solution of a gel precursor and a catalyst in a continuously stirred reactor, and continuously flowing the obtained sol solution into a pipeline static mixer outside the reactor to be mixed with an active ingredient, and then dispensing the obtained mixture into another container to solidify into a gel composition.

5. The method according to any one of claims 1 to 4, Features The active ingredient is selected from at least one of a microbial disinfectant, a microbial inhibitor, a metabolic inhibitor, and a deodorant, and the gel composition controls the release of the active ingredient to inhibit odor generated by microbial activity.

6. The method according to any one of claims 1 to 5, Features The method further comprises the step of adding a cross-linking agent in step (2).

7. The method according to any one of claims 1 to 6, Features The gel precursor is a silanol ester, preferably at least one of tetraethyl orthosilicate (TEOS), methyl orthosilicate (TMOS) and trimethyl orthosilicate (TPOS), Optionally, the catalyst is selected from an acid hydrolysis catalyst or a base hydrolysis catalyst. The acid hydrolysis catalyst is preferably at least one of hydrochloric acid, nitric acid, and citric acid. The base hydrolysis catalyst is preferably at least one of ammonia water, sodium hydroxide, potassium hydroxide, and a base-stabilized colloidal silica suspension.

8. The method according to claim 4, Features The method further comprises the step of extruding the mixture to produce gel products of different sizes and shapes before dispensing into containers for solidification.

9. The method according to any one of claims 1 to 8, Features Relative to the total weight of the gel composition, the gel composition comprises: 0.1-12% by weight of an active agent; 5-35 wt.% of a silica matrix and Optional 0-20 wt% of a crosslinking agent.

10. The method according to claim 1 or 2, Features The method is an intermittent process, wherein the gel precursor and the catalyst are added to the reactor at one time for hydrolysis, and after the hydrolysis is completed, the active ingredient is added to the reactor, and then the obtained mixture solution is distributed to the container at one time.

11. The method according to any one of claims 1 to 10, Features The volume of the reaction system in the reactor is at least 1L to 1 ton, preferably at least 2L, more preferably at least 5L.

12. A gel composition prepared according to the method of any one of claims 1 to 10.

13. Use of the gel composition according to claim 12 for controlling the dosage of the active ingredient to suppress odor caused by microbial activity.

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