CN1034103C - Encapsulation method of essence microcapsule - Google Patents

Abstract

The present invention relates to a production method of microcapsule formed by interfacial polymerization reaction, in particular, it relates to a method for producing microcapsule by using essence as main core material, and is characterized by that it adopts the comprehensive measures of adding additive component into organic phase, increasing dosage of capsule wall material, controlling reaction temperature, shortening reaction time and regulating dispersion speed so as to form the invented essence microcapsule with round and beautiful appearance, single dispersion, fragrance-retaining time up to above one year and recovery rate up to above 95% and different grain sizes.

Description

The present invention relates to a production method of forming microcapsules through interfacial polymerization, in particular, with essence as the main capsule core, by adding additional ingredients and increasing the amount of capsule wall materials in the organic phase, controlling the reaction temperature, shortening the reaction time, Adjusting fractional speed and other comprehensive measures to form flavor microcapsules with round and beautiful appearance, long fragrance retention time, high recovery rate and different particle sizes.

Essence is a highly volatile liquid. In order to prolong the fragrance retention time after use, it must be made into a slow-release type. Microcapsules are the most ideal type of slow-release type. It has good slow-release performance and uniform release speed. , Beautiful appearance. Microcapsules are made of polymer compounds as the capsule wall, which wraps the capsule core that needs to be wrapped, and becomes a small or extremely tiny capsule. The microencapsulation process is a chemical reaction process that takes place in a container. There are many ways to make microcapsules, which have been widely used after being developed in various fields. The encapsulated substance (capsule core) is generally a water-immiscible liquid, or the capsule wall is first dissolved, suspended or dispersed in organic matter It is due to coacervation and sedimentation or the aggregation of substances in the droplets or in the surrounding continuous liquid phase to produce aggregates that settle on the surface of these droplets. Other methods are to eject the droplets so that the sedimentation film of the material passing through the liquid capsule wall , which then solidifies around a single droplet. It is difficult to form capsules with essence as the capsule core material, and it is highly volatile, and the loss is also great during the heating reaction process of capsule formation. Most foreign countries use ethyl cellulose as the capsule wall material, and make essence microcapsules by coagulation method. At this time, the capsule wall material condenses around the essence droplet. The coagulation method is generally not easy to accurately grasp, and often condenses into flocs, and the coating is not complete, and the shape is not beautiful. For example, the air freshener produced in Hong Kong uses US Patent No. 503833. The essence microcapsules in the interior are agglomerated, and single dispersed round particles are rarely seen. Other patents on flavor microcapsules such as US 4013442, 4002458, 3977992, 3985840, etc., interfacial polymerization is an excellent microcapsule forming method: the method is mainly an organic phase (including capsule wall materials and capsule cores, etc.) Disperse in the water phase to the desired size, and under the action of heating or catalyst, the wall material is polymerized into capsules at the interface of the two phases. The operating procedures of this method are relatively easy to grasp, and the produced microcapsules are round and beautiful, individually dispersed, and the coating of the capsule wall is also very uniform and complete. There are many reports on the interfacial polymerization method, such as US Patent 3577517, 4046741 and so on. However, the general interfacial polymerization method cannot be used to successfully encapsulate essence microcapsules. Although the appearance can be round, the production recovery rate of essence is extremely low, only about 10-30%, and most of them are empty capsules under microscope observation, so the fragrance remains light. short time.

The purpose of the present invention is to overcome the shortcomings of the existing encapsulation method, and develop essence microcapsules with high production recovery rate, long fragrance retention time, round and beautiful capsule shape, and different particle diameters according to different costs. For this reason, the task of this patent is to select the basic method of interfacial aggregation to form capsules, and to improve the characteristics of essence: easy volatilization, difficult capsule formation, and many empty capsules. The production recovery rate is above 95%, the fragrance lasts for more than one year, the appearance is round, the coating is complete, and there is no empty capsule. In terms of technology, based on the existing objective conditions in our country, we strive for simple technology, less equipment and less investment.

Production method of the present invention is as follows:

1. Preparation of the organic phase. The organic phase is composed of essence, curing agent, catalyst, capsule wall material, repellent or insecticide. The amount of the organic phase is 1-20%, preferably 8-15%, weight ratio of the water phase. The essence is water-insoluble crude oil. Curing agent refers to some substances that do not participate in the reaction and are liquid above a certain temperature and solid below a certain temperature, such as paraffin, beeswax, palmitic acid, etc. The curing agent is first melted in a 60°C water bath. When the essence contains a sufficient amount of curing agent, when it is added to the warm water phase, the essence can be gradually solidified, and the essence changes from the original liquid state to solid or semi-solid. This solid or semi-solid flavor is easy to form capsules; it reduces the volatilization of the flavor, especially in the reaction process in the warm water phase, and the loss of the volatilization of the flavor is very small; the microcapsules are dispersed individually, the appearance is round, and the fluidity is good; and has The fragrance-fixing effect prolongs the fragrance retention time of the essence. The amount of the curing agent added is 2.5-15% of the essence. The material of the capsule wall in the organic phase is organic isocyanate, and the isocyanate is polymerized at the interface of the two phases during the reaction to form a capsule, and the formed capsule wall is polyurea. The usage amount of isocyanate is 30～75% of essence, weight ratio. Commonly used organic isocyanates are as follows. Can be used alone or in combination.

2,4-Toluene diisocyanate

Toluene diisocyanate (60% 2,4-isomer, 40% 2.6-isomer)

2,6-Toluene diisocyanate

Toluene diisocyanate (80% 2,4 and 20% 2,6-isomer)

Polymethylpolyphenylisocyanate

During the interfacial polymerization reaction of isocyanate to form the capsule wall, the isocyanate monomer is hydrolyzed to form an amine, and the amine reacts with another isocyanate monomer to form a polypodine. The hydrolysis of the isocyanate monomer releases carbon dioxide. Adding a catalyst in the organic phase can increase the hydrolysis rate of the isocyanate, accelerate the reaction or lower the reaction temperature. In the present invention, because the catalyst is used, a good product can be obtained in the reaction process of the essence in a relatively short period of time without high temperature. The catalysts can be basic organic amines and basic tin acetates, such as triethylenediamine, ethylenediamine, hexamethylenediamine, triethylamine, and tri(n-)butylamine. The amount added to the organic phase is 0.01-1%. Adding repellents or insecticides into the organic phase can make the essence microcapsules not only have a fragrance effect but also can repel insects or kill insects, especially suitable for preventing clothing moths. Adding drugs include: various repellants, valethrin , Permethrin. The amount added is 1-10% of the organic phase, and the weight ratio is determined according to the needs of killing insects.

2. Preparation of the water phase: Just use ordinary clean water, and dissolve the protective glue in the water. The protective colloid does not participate in the reaction in the water phase, and protects the microcapsule precursor or microcapsule during the dispersion and stirring process, and also has some effect of promoting dispersion. All soluble substances that can increase the viscosity of the aqueous phase can be used, such as polyvinyl alcohol, carboxymethyl cellulose, gelatin, bone glue, gum arabic, etc. The dosage is 1-2%, the weight ratio. When the amount of glue is not enough, the produced capsules are not round and some are obviously flattened by the blades of the stirrer. When preparing, put the glue in water first, and heat the water to 60-70°C to dissolve the glue slowly. During the whole reaction process, the temperature of the aqueous phase is kept at 30-50°C.

3. Dispersion and reaction process: The prepared organic phase must be mixed evenly, and slowly added to the water phase while stirring continuously (using a stirrer). Different stirring speeds form capsules of different particle sizes. The choice of stirring speed depends on the final needs. The faster the stirring speed is, the smaller the capsules will be. If it is necessary to form capsules with a particle size of 1-5 microns, the stirring speed should reach about 10,000 rpm. Disperse the capsules formed by the organic phase at any rate. They are all unevenly dispersed, and it is impossible to achieve a capsule with a very uniform particle size dispersion. Therefore, the accurate expression method of particle size is appropriate to use the mass median diameter or the number median diameter, and the rough method is to express the range of particle size distribution. After the organic phase is dispersed in the water phase, the capsule wall material at the interface of the two phases undergoes a polymerization reaction. The polymerization reaction occurs very quickly, and most of it occurs within half an hour of the initial reaction. In order to ensure that the polymerization reaction of the entire system is close to Completely, the reaction state needs to continue for 1 to 2 hours, but in the presence of a catalyst, the reaction time can be appropriately shortened. The reaction time required by the present invention is only 30-50 minutes, and after the reaction is completed, the formed capsule wall is complete.

During the reaction process, it is necessary to constantly adjust the pH value or add the catalyst dropwise at the same time. If the pH in the reaction solution is acidic, more carbon dioxide will be generated during the reaction and unnecessary excessive foam will be formed, so the pH should be adjusted above 7.

The reaction process of this patent can be batch or quasi-batch, continuous or quasi-continuous. When batch production, all the various liquids and reactants are concentrated, and the timing of each stage depends on the appropriate time for the individual liquids. If a suitable reaction tank is used, the output can reach more than 100 kg/day, and the whole reaction process can also be continuous or semi-continuous. In the continuous production process, the dispersion of the organic phase is carried out continuously, and the micro-droplet dispersed phase is continuously formed in the water phase, which is continuously added to the reaction tank, and the pH is adjusted in it to form a polymerization reaction. In a continuous system, appropriate reaction rates can be obtained by selecting appropriate conditions.

4. Cleaning, drying, and after the reaction is completed, pour the reaction solution into a large tank to settle, wash it with water for 3 times, dry it naturally, and sieve it to remove oversized or agglomerated particles. The reactants can also be used directly, depending on need.

The essence microcapsule produced by the above method can achieve the task proposed by this patent. Calculated by weighing, the recovery rate of the total materials used can reach more than 95%. The same as the recovery rate of other non-volatile substance microcapsules produced by us, it can be explained that the loss of essence in the encapsulation process is very small. The dry microcapsules with large particle size are placed at room temperature with free circulation of air, and the fragrance can last for more than one year. Observe the essence microcapsules with large particle size with the naked eye, such as millet grains, round and smooth, light yellow (related to the color of the essence itself), and have good fluidity. If the capsule is ruptured with a hard object such as pressure, the content can be seen to be a light yellow solid, and the other two types of essence microcapsules with small particle diameters look like powders to the naked eye. When observed with a microscope, no matter what kind of essence microcapsules are round and smooth, there is a thin layer of shiny film on the periphery, which is the capsule wall. The pale yellow capsule core is clearly visible, and no empty capsules are seen. No holes were seen either. When observed with a stereo microscope, the microcapsules are like pale yellow pearls, very plump and lovely. Observed with an electron microscope magnified 3000 times, it can be seen that the cyst wall is rough and cross-linked, with some extremely small pores on it.

According to different purposes, microcapsules with different particle sizes are produced: microcapsules with a particle size of 1-5 microns are used in various fragrant paper products, coatings, etc.; microcapsules with a diameter of 50-300 microns can be used to make fragrant paper fans and other aromatic products ; 500 ~ 1500 micron microcapsules can be made into packaging sachets.

Example 1:

Add 2 grams of polyvinyl alcohol to 200ml of clean water, boil to dissolve, and then keep the constant temperature at 30°C. Adjust the pH to 7.5. In another container, amplify 20 grams of jasmine essence, 1 gram of paraffin, and dissolve the paraffin in a water bath, then add 0.3 grams of tri(n-)butylamine and 10 grams of 2,4-toluene diisocyanate, and mix well. Put a stirrer blade in the water phase, and the required particle size can be reached in about 2 minutes at a speed of 10,000 rpm, while adjusting the pH to keep it at about 7.5. After that, stir for half a minute with the above-mentioned rotating speed every 10 minutes, and the reaction is completed in half an hour. The particle diameter of the obtained essence microcapsule is in the range of 1-5 micrometers. The reaction solution contains 29 to 30 grams of sachets, and the reaction solution can be used in its entirety, or it can be centrifuged at 4000 rpm for half an hour, and the supernatant is discarded, and then it becomes a paste-like concentrated essence microcapsule.

Example 2:

Add 1.8 grams of gum arabic to 200 ml of clean water, heat to dissolve, and then keep a constant temperature of 50°C. In another container, put 10 grams of Lanhua essence, 2 grams of repellent, and 1.2 grams of palmitic acid, heat and melt, add toluene diisocyanate (80% 2,4 and 20% 2,6-isomer) 3 gram, 3 grams of polymethyl polyphenylisocyanate, 0.01 gram of ethylenediamine, and mix well. Put stirring blades in the water phase, 150-200 rpm, maintain this stirring speed, and constantly adjust the pH value to 7.5. The reaction is completed in 30 minutes. The particle size of the formed essence microcapsules is in the range of 500-1500 microns. The reaction solution contains 18-19 grams of essence microcapsules. The supernatant was removed from the reaction solution, washed three times with water, dried naturally, and sieved.

Example 3:

Add 4 grams of gelatin to 200 ml of clean water, heat to dissolve, and then keep the constant temperature at 30°C. In another container, put 15 grams of brandy essence and 2.2 grams of beeswax, heat to dissolve, add 0.1 grams of triethylenediamine, 5 grams of 2,6-toluene diisocyanate, and mix well. Put stirring blades in the water phase, disperse at about 150-200 rpm, maintain this stirring speed, and constantly adjust the pH to 7, and the reaction is completed in 40 minutes. The particle size of the formed essence microcapsules is in the range of 500-1500 microns. The reaction liquid contains 21-22 grams of microcapsules, the supernatant is removed from the reaction liquid, washed with water three times, dried naturally, and sieved.

Example 4:

Add 1.8 grams of bone glue to 200 ml of clean water, heat to dissolve, and then keep the temperature at 30°C. In another container, enlarge 12 grams of Yayun essence, 0.3 grams of palmitic acid, 4 grams of polymethyl polyphenylisocyanate, 0.05 grams of tributyltin acetate, and mix well. Add stirring blades into the water phase, disperse at 500-1000 rpm, maintain the speed at 200 rpm, and constantly adjust the pH to maintain it at about pH7.5. 50 minutes to complete the reaction. The particle size of the formed essence microcapsules is in the range of 50-300 microns. The reaction liquid contains 15.5-16 grams of essence microcapsules, the supernatant of the reaction liquid is removed, washed with water three times, dried naturally, and sieved.

Claims (5)

1. A method of producing essence microcapsules developed by the process of interfacial polymerization in polyurea, by changing the composition of the organic phase, the organic phase is composed of essence and capsule wall material isocyanate monomer, in the organic phase Add flavor curing agent and catalyst, increase the thickness of the capsule wall, adjust the dispersion speed of the organic phase in the water phase containing the protective colloid, and complete the polymerization reaction at a lower temperature and shorter reaction time to produce a product The recovery rate is above 95%, the fragrance lasts for more than one year, the appearance is round, the coating is complete, and there is no empty capsule. There are three types of essence microcapsules with different particle sizes. The characteristics are: The curing agent described in 1.1 is an inactive substance that melts above a certain temperature and solidifies below a certain temperature, including beeswax, paraffin, palmitic acid, and the dosage is 2.5-15% of the essence, and the weight ratio is added before the polymerization reaction Add to the essence, heat to 60°C to pre-melt; The increase in the thickness of the capsule wall described in 1.2 means that the ratio of isocyanate to essence is increased, from 30% to 75%, and the thickness of the capsule wall is increased to achieve recovery of microcapsules with excellent dispersibility; The water phase described in 1.3 is general clear water adding water-soluble neutral substances that can increase water viscosity, such as polyvinyl alcohol, carboxymethyl cellulose, gelatin, bone glue, gum arabic, and the consumption is 1 to 2% of water. The weight ratio is preheated to dissolve, and the organic phase is 8-15% of the water phase. The catalyst described in 1.4 is triethylenediamine, ethylenediamine, hexamethylenediamine, triethylamine, tri(n-)butylamine of basic organic amines, and the consumption is 0.01～1% of the organic phase, and the weight ratio is at Add to the organic phase before the reaction and mix well; The lower polymerization reaction temperature mentioned in 1.5 is to control the temperature at 30-50°C when the organic phase added to the catalyst is dispersed in the water phase, and the temperature is controlled at 30-50°C. Complete in 30-50 minutes. 2. The use formula of a kind of catalyst in claim 1 is characterized in that triethylenediamine 10%, hexamethylenediamine 10%, weight ratio, before polymerization reaction and reaction process equal amount is added dropwise in the aqueous phase, makes aqueous phase The pH is maintained at 7.5-8.0. 3. A fragrance formula in claim 1 is characterized in that insect repellent Deet and insecticide biopyrethrin are added to the fragrance in an amount of 1-10% by weight to make moth-proof and insect-repelling fragrance microcapsules. 4. The adjustment of dispersion speed described in claim 1 is to adjust the speed of the agitator to disperse the organic phase in the water phase. The speed of the dispersion of the organic phase in the water phase is changed. The microcapsules with a diameter of 50 to 300 microns can be obtained at around rpm, and the microcapsules with a particle size of 1 to 5 microns can be obtained at a rotating speed of about 10,000 rpm. 5. A dispersing speed of 10,000 rpm in claim 4, characterized in that after the components in the organic phase are mixed evenly, pour it into the water phase while it is hot, and disperse at a speed of 10,000 rpm for 2 minutes without constant temperature. Adjust the pH to keep it at 7.5-8, stir at the above speed for half a minute every 10 minutes, and the reaction is completed in 30 minutes.