A phb resin particle and a method for producing the same

Abstract

The application provides a PHA resin particle and a preparation method thereof, and the preparation method comprises the following steps: S10, drying, melting and spinning polyhydroxyalkanoate and an additive in sequence to obtain a PHA fiber; S20, cooling the PHA fiber, and spraying a modifier liquid on the surface of the PHA fiber during the cooling to obtain a modified PHA fiber; and S30, sequentially performing oiling, winding and crushing on the modified PHA fiber to obtain the PHA resin particle. The application aims to prepare the PHA resin particle sprayed with the modifier through a melt spinning process, so as to avoid that the modifier reduces the product performance of the PHA resin particle.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biodegradable polymer materials, in particular to a kind of PHA resin particles and preparation method thereof. BACKGROUND

[0002] Polyhydroxyalkanoate (PHA) is a kind of biologically friendly, ocean-degradable, performance-adjustable bio-based polymer material, and its application prospect is very broad. The known PHA can be used in medical, pharmaceutical, cosmetic and other high value-added fields, such as surgical suture, drug release system carrier, cosmetic microbeads, etc. It also has a wide application prospect in the fields of environmental protection packaging materials, spraying materials, appliance materials, electronic communication, agricultural products, automation products, chemical media, etc. Among them, the modified PHA resin particles can be used for coating emulsion products, which not only can realize the functional diversification of PHA products, but also can ensure the non-toxic and non-polluting products, such as anticorrosive coating, fire-retardant coating, food packaging coating, etc.

[0003] In the prior art, in order to prepare modified PHA products, the modifier is usually mixed in the product during the preparation of the product. On the one hand, mixing the modifier in the product can easily lead to the loss of flexibility, and on the other hand, the modification function is usually applied to the surface of the product, while the modification liquid in the material cannot be really well utilized, resulting in the loss of modifier. SUMMARY

[0004] The present application aims to prepare a modified PHA resin particle by melt spinning process.

[0005] In order to achieve the above purpose, the present application provides a preparation method of PHA resin particles, comprising the following steps: S10: drying, melting and spinning polyhydroxyalkanoate and auxiliary agent in sequence to obtain PHA fiber; S20: cooling the PHA fiber, and spraying modification liquid on the surface of the PHA fiber during cooling to obtain modified PHA fiber; S30: oiling, winding and crushing the modified PHA fiber in sequence to obtain PHA resin particles.

[0006] The melt spinning process is to use polymer melt as raw material, extrude through the spinneret, rapidly condense in the air and solidify into fibers. The melt spinning process is simple, the spinning solution is the melt of the fiber-forming polymer itself, and there is no need to recover the spinning solvent or the coagulation bath. Moreover, the fiber forming process is completed in the gas phase, the friction resistance is small, and a higher winding speed can be used, so the production efficiency is high. Among them, the melting temperature of the fiber-forming polymer must be lower than the thermal decomposition temperature by 25-35 DEG C, otherwise it is difficult to spin by the classical melt method. The purpose of the present application is to prepare PHA fibers, and then to process PHA resin particles. The melting temperature and decomposition temperature of PHA meet the basic conditions of the melt method, so the melt spinning process can be used for preparation.

[0007] The present application prepares PHA fibers by the melt spinning process. First, polyhydroxyalkanoate and additives are heated as spinning raw materials to obtain a melt, and then the melt is sequentially sprayed, stretched, cooled, oiled and wound to obtain the required PHA fibers. In the cooling process, a plurality of modified auxiliaries are applied to the surface of the fiber in the form of spraying to functionalize the fiber. The fiber with the attached modifier is crushed to obtain modified PHA resin particles. Among them, the modification in the form of spraying can reduce the loss of modifier, and more importantly, the attached modifier can make the PHA resin particles multifunctional, which is beneficial to the coating of emulsion products.

[0008] In any of the above technical solutions, S10 specifically comprises: S11: drying polyhydroxyalkanoate and additives under vacuum conditions at a temperature of 75-80 DEG C for 6-10 hours to obtain spinning raw materials; S12: feeding the spinning raw materials into a double screw extruder to melt under the condition that the screw rotation speed is 220-420 r / min, and the extrusion temperature is 100-180 DEG C to obtain a melt;

[0009] S13: filtering and metering the melt, and then spinning at a temperature of 165-195 DEG C at a spinning speed of 250-550 m / min to obtain PHA fibers.

[0010] The present application uses polyhydroxyalkanoate and additives as spinning raw materials. The additives can improve the production process and provide product performance, thereby improving the use value and life of the product. The smaller the particle size of the additives, the more beneficial to the tensile strength and impact strength of the filler material. The moisture content of the spinning raw material has a great influence on the stability of spinning. In the high-temperature melting state, high moisture content can easily accelerate the hydrolysis reaction, causing the macromolecular chain segment to break. Moreover, water vaporization forms bubbles, causing uneven fiber formation and frequent breakage, thereby increasing the unevenness of the product fineness and reducing the breaking strength. Therefore, the raw material chips before spinning must be dried to control the moisture content within a certain range.

[0011] In the melting process of the application, a double screw extruder is selected as the main production device, and the friction and extrusion between the raw materials in the double screw extruder generate a certain amount of heat, so that the raw materials are heated and melted, and are compressed by the double screw extruder to have a certain melt pressure, thereby ensuring that the obtained melt is extruded from the discharge port. If the temperature of the melt is too high, the polymer will be degraded and bubbles will be formed; if the temperature is too low, the viscosity of the melt will be too high; both of which will cause the spinning process to be unable to proceed normally, so it is necessary to select appropriate screw rotation speed and melt extrusion temperature.

[0012] Before spinning, impurities in the melt can be filtered out by filtration treatment. Filtration will generate high resistance, which will generate heat by friction of the melt during the spinning process, thereby increasing the temperature and improving the rheological properties of the melt. The filtered melt is metered to ensure that the linear density of the fiber is consistent and the strip is uniform.

[0013] In any of the above technical solutions, S20 specifically comprises: cooling the PHA fiber, stretching at a cooling temperature of 65-75 DEG C, spraying a modifier on the PHA fiber at a cooling temperature of 70-80 DEG C for modification, and finally cooling and forming to obtain modified PHA fiber.

[0014] The PHA fiber obtained by spinning is in a high temperature and unformed state, so it needs to be cooled, which can usually be cooled by cold air blowing or water circulation. At the same time of cooling, the PHA fiber is gradually refined before solidification due to the stretching effect of spinning. In addition, a modifier is sprayed during the cooling process, which is beneficial to the adhesion and emulsification of the coated emulsion product by adding the modifier.

[0015] In any of the above technical solutions, the cooling comprises five-stage cooling and temperature reduction, and the temperatures of the first, second, third, fourth and fifth cooling stages are 85-102 DEG C, 65-75 DEG C, 60-65 DEG C, 70-80 DEG C and 20-30 DEG C, respectively; and / or the stretching ratio is 6-10.

[0016] In the cooling and forming process of the application, a cooling section is needed to cool the un-solidified PHA fiber. The cooling comprises five-stage cooling and temperature reduction, and the temperature of the cooling is provided by blowing cold air. The air temperature has little effect on the tension and properties of the fiber during the cooling and forming process, but when the air temperature is low, the fiber feels hard; when the air temperature is abnormal and fluctuates greatly, the unevenness of the fiber and the unevenness of the dynamic hot stretching stress will be affected, and the number of broken filaments and fuzz will increase.

[0017] The stretching is performed while cooling, and a proper stretching ratio not only ensures the toughness and strength of the fiber, but also reduces the fineness of the fiber, so as to increase the specific surface area of the modifier during subsequent spraying.

[0018] In any of the technical solutions, S30 specifically comprises: oiling the modified PHA fiber, then winding and collecting the modified PHA fiber at a speed of 1400 m / min-1600 m / min, subsequently cutting the modified PHA fiber under the condition of a protective atmosphere, and putting the modified PHA fiber into a ball mill for crushing to obtain PHA resin particles.

[0019] During cooling, the cooling air also has a drying effect, which causes the fiber to easily generate static electricity due to drying, and the cohesion between filaments is poor, the sliver is loose, and the friction coefficient is large, so that subsequent processing cannot be performed. Therefore, the fiber can be immediately subjected to oiling treatment after cooling, and the oiling treatment can facilitate the bundling of the sliver, reduce static electricity, and improve smoothness, so as to meet the requirements of subsequent processing.

[0020] The fiber subjected to the oiling treatment is changed in direction and tension by the up-and-down guide device, so as to be wound on a bobbin. The bobbin needs to rotate at a constant winding speed, so as to maintain a certain winding tension and ensure that the final winding shape of the fiber is good.

[0021] In any of the technical solutions, the mass ratio of the grinding medium in the ball mill to the modified PHA fiber is (3-7):1; the grinding medium comprises large balls and small balls, and the number ratio of the large balls to the small balls is 1:2.

[0022] The modified PHA fiber is crushed by the ball mill, a certain mass ratio of the grinding medium to the modified PHA fiber is selected, a proper mass ratio is beneficial to rapid grinding of the fiber; a certain number ratio of the large balls to the small balls is selected, and a proper number ratio can avoid that the product particle size obtained by grinding is too small, so as to ensure that the modified liquid does not separate from the fiber, and the emulsion product can be coated on the particles.

[0023] In any of the technical solutions, the polyhydroxyalkanoate is a random copolymer or block copolymer containing 6-14 carbon atoms in a monomer, and having a melting point of 60-150℃.

[0024] If the monomer of the polyhydroxyaliphatic ester contains medium and long chains with less than 6 carbon atoms, the property of the polyhydroxyaliphatic ester is inclined to wax, and the mechanical property is poor, if the monomer of the polyhydroxyaliphatic ester contains medium and long chains with more than 16 carbon atoms, the property of the polyhydroxyaliphatic ester becomes hard and brittle, and the flexibility of the product cannot be guaranteed, and the hydroxyaliphatic ester used in the application contains medium and long chains with 6-14 carbon atoms in the monomer, which can meet the mechanical property and the flexibility, the specific melting point range can be determined according to the specific polyhydroxyaliphatic ester, and then the appropriate extrusion temperature can be set.

[0025] In any of the above technical solutions, the mass ratio of the polyhydroxyaliphatic ester and the auxiliary agent is (80-120):(1-30); and / or the mass ratio of the modification liquid and the PHA fiber is (1-3):(8-10); and / or the concentration of the modification liquid is 35wt%-50wt%.

[0026] By adding the auxiliary agent to the polyhydroxyaliphatic ester, the production process can be improved and the product performance can be provided, and by spraying the modification liquid on the surface of the PHA fiber, the emulsion product to be coated can be adhered and emulsified, and the combination effect of the PHA resin particles and the emulsion product can be improved.

[0027] In any of the above technical solutions, the auxiliary agent includes at least one of an antioxidant, a thermal stabilizer, an anti-blocking agent, and a coupling agent; and / or the modification liquid includes at least one of a surfactant and an emulsifier.

[0028] The antioxidant can avoid the yellowing, degradation and strength reduction of the product caused by the oxidation of the resin itself, the thermal stabilizer can avoid the thermal degradation during processing, the anti-blocking agent can improve the smoothness, anti-blocking, anti-static and wear resistance of the emulsion product, and the coupling agent can improve the dispersion state of the inorganic auxiliary material in the polymer raw material and improve the mechanical property and use performance of the product as a whole.

[0029] The surfactant can improve the wetting and permeation effect of the emulsion product on the surface of the resin particles, and also has the functions of emulsification, dispersion and solubilization. The emulsifier can reduce the surface tension between the emulsion product and the resin particles, so that the emulsion product can rapidly spread to the entire surface of the particles, and the stability of the formed emulsion can be improved.

[0030] The application also provides a PHA resin particle, which is obtained by the preparation method of any of the above technical solutions, and therefore has the same beneficial effects as the preparation method, which will not be described here.

[0031] After the technical solutions of the application are used, the following technical effects can be achieved:

[0032] The purpose of the present application is to prepare PHA fibers, and then to process PHA resin particles, the melting temperature and decomposition temperature of PHA meet the basic conditions of the melt method, and the PHA resin particles are prepared by using the melt spinning process, which is simple in process, the spinning solution is the melt of the fiber-forming polymer itself, and there is no need to recover the spinning solvent or the coagulation bath, and the fiber forming process is completed in the gas phase, the friction resistance is small, and a higher winding speed can be used, and the production efficiency is high. The present application first heats polyhydroxyalkanoate and additives as spinning raw materials to obtain a melt, and then sprays, stretches, cools, oils, and winds the melt in sequence to obtain the required PHA fibers. In the cooling process of the present application, a plurality of modified auxiliaries are applied to the surface of the fiber in the form of spraying to realize the functionalization of the fiber, and the fiber attached with the modifier is crushed to obtain modified PHA resin particles. DETAILED DESCRIPTION

[0033] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0034] The related polyhydroxyalkanoate product has become a research hotspot of those skilled in the art in recent years due to its good biodegradability. Modifying the polyhydroxyalkanoate product can increase the functions of the product and expand the application field of the product. In the prior art, in order to prepare the modified polyhydroxyalkanoate product, the polyhydroxyalkanoate is often mixed with a modifier, and finally a shaped body is prepared. On the one hand, mixing the modifier inside the product easily leads to loss of flexibility, and on the other hand, the modification function is usually applied to the surface of the product, and the modification liquid inside the material cannot be really well utilized, resulting in loss of the modifier.

[0035] The embodiment of the present application provides a preparation method of PHA resin particles, including the following steps: S10: polyhydroxyalkanoate and additives are sequentially dried, melted and spun to obtain PHA fibers; S20: the PHA fibers are cooled, and a modification liquid is sprayed on the surface of the PHA fibers during cooling to obtain modified PHA fibers; S30: the modified PHA fibers are sequentially oiled, wound and crushed to obtain PHA resin particles.

[0036] Firstly, the polyhydroxyalkanoate and the auxiliary agent are melt-spun to prepare the PHA fiber with good performance, secondly, the modification liquid is sprayed on the surface of the PHA fiber during the cooling of the PHA fiber, so that the adhesion of the modification liquid is good, and finally, the modified PHA fiber is crushed to obtain the modified PHA resin particles. The process can avoid the performance reduction of the PHA resin particles and improve the utilization rate and application effect of the modification liquid by spraying the modification liquid on the PHA product during the cooling of the PHA product.

[0037] In some embodiments of the present application, S10 specifically comprises: S11: drying the polyhydroxyalkanoate and the auxiliary agent under vacuum condition and at a temperature of 75-80℃ for 6-10h to obtain a spinning raw material; S12: feeding the spinning raw material into a double-screw extruder to melt at a screw rotation speed of 220-420r / min and an extrusion temperature of 100-180℃ to obtain a melt;

[0038] S13: filtering and metering the melt, and then spinning at a temperature of 165-195℃ and a spinning speed of 250-550m / min to obtain the PHA fiber.

[0039] Preferably, the auxiliary agent can be at least one of an antioxidant, a heat stabilizer, an anti-blocking agent and a coupling agent, and the smaller the particle size of the auxiliary agent, the more beneficial to the tensile strength and impact strength of the filler material.

[0040] It should be noted that during the melt spinning process, the raw material needs to be first sliced for melt processing, and the slice moisture content has a great influence on the stability of spinning. If the slice moisture content is high, the hydrolysis reaction is easily intensified under the condition of high-temperature melting, which causes the macromolecular chain segment to break; and the water vaporization forms bubbles, causing the fiber forming to be uneven in thickness and frequent breakage, thereby increasing the fineness unevenness rate of the product and reducing the breaking strength; in addition, the hydrogen of the water molecules and the oxygen of the polyhydroxyalkanoate form intermolecular hydrogen bonds. When the number of water molecules in the melt increases, the mass fraction of the intermolecular hydrogen bonds increases, thereby increasing the intermolecular force, which causes the elastic factor of the melt to increase, which is not conducive to spinning. Therefore, the slice of the raw material before spinning must be dried to control the moisture content within a certain range. Preferably, the drying temperature is 76-79℃, the drying time is 7-9h, and the moisture content of the slice of the raw material is controlled to be below 180ppm.

[0041] For example, in the melting process of the present application, a twin-screw extruder is selected as the main production device. The spinning raw material enters the twin-screw extruder from the feeding port by gravity, and moves forward along the screw groove due to the rotation of the screw. The outer side of the screw sleeve is equipped with heating elements, which transfer heat to the raw material through the sleeve. At the same time, the raw material in the twin-screw extruder generates a certain amount of heat through friction and extrusion, causing the raw material to melt and be compressed by the twin-screw extruder to have a certain melt pressure, thereby ensuring that the obtained melt is extruded from the discharge port. The sleeve can be set to have a gradient temperature from the inlet to the outlet, with the temperature gradually increasing. The temperature of the melt can be controlled by using the temperature of each section of the sleeve. If the temperature of the melt is too high, it will cause the polymer to degrade and form bubbles. If the temperature is too low, the viscosity of the melt will be too high. Both of these will prevent the spinning process from proceeding normally. The temperature of the first section of the sleeve is 90-130°C, the temperature of the second section is 5-20°C higher than that of the first section, and the temperature of the other sections is 10-30°C higher than that of the second section. Preferably, the screw rotation speed is 260-380 r / min, and the extrusion temperature is 120-160°C.

[0042] Preferably, the melt at the discharge port is mixed uniformly by using a static mixer, thereby strengthening the uniformity of the melt and reducing the difference in temperature and residence time between the pipe wall and the pipe center when the melt passes through the elbow pipe. Those skilled in the art can choose whether to use a static mixer according to the uniformity of the melt.

[0043] Preferably, impurities in the melt can be filtered out before spinning by using a filter material. The filter material includes carborundum, sea sand, ultra-fine glass beads, filter screens, etc., and is preferably a filter layer assembly with coarse particle size and thick filter sand or a multi-layer filter sand assembly with different particle sizes, wherein the particle sizes of the filter sand should be arranged in a gradient that gradually decreases. In high-pressure spinning, the filter layer will generate a high resistance, causing the melt to generate heat through friction, thereby increasing the temperature and improving the rheological properties of the melt.

[0044] The melt output by the screw extruder is distributed to the metering pumps at each spinning site by a distribution pipe to ensure that the linear density of the fibers is consistent and the evenness is uniform. At the same time, the metering pump can pressurize the melt to meet the needs of spinning. Preferably, the pressure in the metering pump is 6-13 MPa; further preferably, the pressure in the metering pump is 8-11 MPa.

[0045] After metering, the melt is distributed to various spinneret orifices on the spinneret and extruded from the orifices to form PHA fibers. The main function of the spinneret is to transform the melt into a fine stream with a specific cross-section through micro-orifices, preferably with an orifice diameter of 0.1 mm to 0.4 mm. Preferably, the spinning temperature is 170℃ to 190℃ and the spinning speed is 300 m / min to 500 m / min; more preferably, the spinning temperature is 175℃ to 185℃ and the spinning speed is 350 m / min to 400 m / min.

[0046] In some embodiments of the present invention, S20 specifically includes: cooling the PHA fiber, stretching it at a cooling temperature of 65°C-75°C, spraying a modifying liquid onto the PHA fiber at a cooling temperature of 70°C-80°C for modification, and finally cooling and molding to obtain modified PHA fiber.

[0047] The PHA fibers obtained from the spinneret are in a high-temperature, unformed state, so they are introduced into a cooling channel for cooling. Typically, cooling can be achieved using cold air blowing or water circulation. In this case, the fibers also need to be dried; therefore, the preferred cooling medium is cooling air forced out by the air vent at the top of the channel, which also ensures uniform cooling conditions. During cooling, the PHA fibers gradually become finer before solidification due to the stretching effect of the spinneret. A temperature range of 65℃-75℃ is favorable for stretching; a temperature range of 70℃-80℃ is favorable for the application of the modified liquid. The modified liquid includes at least one surfactant and emulsifier; the addition of the modifier facilitates the adhesion and emulsification of the coated emulsion product.

[0048] In some embodiments of the present invention, the cooling includes five stages of cooling and temperature reduction, in the following order: the temperature of the first cooling stage is 85℃-102℃, the temperature of the second cooling stage is 65℃-75℃, the temperature of the third cooling stage is 60℃-65℃, the temperature of the fourth cooling stage is 70℃-80℃, and the temperature of the fifth cooling stage is 20℃-30℃; and / or the stretching ratio is 6-10.

[0049] In the cooling and molding process of this invention, a channel with a ring-shaped airflow is required to cool the unsolidified PHA fibers. Preferably, the length of the channel is 3.2m-3.8m. The channel is divided into five cooling sections, and the cooling temperature is provided by blowing cold air. The air temperature has almost no effect on the tension and properties of the fibers during the cooling and molding process, but when the airflow temperature is low, the fibers feel stiff. When the airflow temperature is abnormal or fluctuates greatly, it will affect the fiber evenness and the unevenness of dynamic thermal tensile stress, and cause increased fiber breakage and fuzzing.

[0050] The first three sections from the entrance of the duct have gradually decreasing temperatures, wherein the drawing ratio is preferably 7-9 while the temperature is decreasing in the second cooling section, and the suitable drawing ratio not only ensures the toughness and strength of the fiber, but also reduces the fineness of the fiber, so as to increase the specific surface area of the modifier during subsequent spraying; the temperature of the second cooling section is 65-75 DEG C, which is beneficial to the drawing of the fiber. The temperature of the fourth cooling section is slightly increased to 70-80 DEG C, and the temperature range is beneficial to the adhesion of the sprayed modification liquid on the surface of the fiber, and the modification liquid is not easy to fall off, so as to ensure that the emulsion can be uniformly and firmly coated on the resin particles in subsequent operations. Preferably, the temperature of the first cooling section is 80-95 DEG C, the temperature of the second cooling section is 68-72 DEG C, the temperature of the third cooling section is 61-64 DEG C, the temperature of the fourth cooling section is 73-77 DEG C, and the temperature of the fifth cooling section is 23-27 DEG C.

[0051] In some embodiments of the present application, S30 specifically comprises: oiling the modified PHA fiber, and then winding and collecting at a speed of 1400-1600 m / min, and then cutting the modified PHA fiber under the condition of a protective atmosphere, and putting the modified PHA fiber into a ball mill for crushing to obtain PHA resin particles.

[0052] During cooling, the cooling air can also play a role in drying, which leads to the fact that the fiber is easy to generate static electricity due to drying, and the cohesion between the filaments is poor, the sliver is loose, and the friction coefficient is large, so that the post-processing cannot be carried out. Therefore, the fiber can be immediately subjected to oiling treatment after cooling, and the oiling can play a role in facilitating the bundling of the sliver, reducing static electricity, and improving smoothness, so as to meet the requirements of subsequent processing. It should be noted that the oiling position is different when different processes are used for spinning. The uniformity of the oiling treatment also needs to be considered, and the oiling methods generally include three forms of gear pump dosing nozzle oiling, oil pan oiling, and nozzle and oil pan combination.

[0053] The oiled fiber is changed in direction and tension by the up and down guide device so that the guide roller can wind the fiber on the bobbin. The winding tension and its stability not only affect the physical property and unevenness of the fiber, but also affect the quality of the formed winding package. If the winding tension is too high, the winding package will be formed poorly, the end face of the winding package will be irregular, and the subsequent unwinding will be difficult due to the high winding tension. If the winding tension is too low, the winding density will be low and the winding package will be easy to be off the bobbin. Therefore, the winding tension must be controlled in the production process of the present application. In normal production, the optimal value of the winding tension is different for different products, and is generally between 0.1-0.2 cN / dtex. Therefore, the bobbin needs to be kept at a constant winding speed when rotating, so as to keep a certain winding tension and ensure that the final winding shape of the fiber is good, and the shape of the bobbin is generally cylindrical. The stretching and heating temperature of the guide roller is controlled at 45-70℃, preferably 55-65℃; the guide speed is controlled at 1300-1500 m / min, preferably 1350-1450 m / min; and the winding speed is controlled at 1400-1600 m / min, preferably 1450-1550 m / min. In addition, a ring air blower is arranged around the guide roller, and the temperature is controlled at 18-45℃.

[0054] In some embodiments of the present application, the mass ratio of the grinding medium in the ball mill to the modified PHA fiber is (3-7): 1; the grinding medium includes large balls and small balls, and the number ratio of the large balls to the small balls is 1:2.

[0055] By using the ball mill to crush the modified PHA fiber, preferably, the mass ratio of the grinding medium to the modified PHA fiber is (4-6): 1, and the suitable mass ratio is conducive to rapid grinding of the fiber; and the number ratio of the large balls to the small balls is 1:2, and the suitable number ratio can avoid that the particle size of the obtained product is too small, so as to ensure that the modification liquid does not separate from the fiber, and ensure that the emulsion product can be coated on the particles.

[0056] In some embodiments of the present application, the polyhydroxyalkanoate is a random copolymer or block copolymer containing 6-14 carbon atoms in the monomer, and the melting point is 60-150℃.

[0057] If the monomer of the polyhydroxyaliphatic ester contains medium-long chain with carbon atom number less than 6, the property of the polyhydroxyaliphatic ester is inclined to wax, and the mechanical property is poor; if the monomer of the polyhydroxyaliphatic ester contains medium-long chain with carbon atom number more than 16, the property of the polyhydroxyaliphatic ester is hard and brittle, and the flexibility of the product cannot be ensured; the hydroxyaliphatic ester used in the application contains medium-long chain with carbon atom number of 6-14, which can meet the mechanical property and the flexibility. The specific melting point range can be determined according to the specific polyhydroxyaliphatic ester, and the appropriate extrusion temperature is set, and the person skilled in the art can select the appropriate polyhydroxyaliphatic ester in the range of the limited carbon atom number according to the own needs.

[0058] The polyhydroxyaliphatic ester includes at least one of poly-3-hydroxyhexanoic acid (3HHx), poly-3-hydroxyoctanoic acid ester (PHO), poly-3-hydroxynonanoic acid ester (PHN), poly-3-hydroxydecanoic acid ester (PHD), copolymer of 3-hydroxybutyric acid and 3-hydroxyhexanoic acid (PHBHHx), and copolymer of 3-hydroxybutyric acid and 3-hydroxyheptanoic acid (PHBHHp).

[0059] In some embodiments of the application, the mass ratio of the polyhydroxyaliphatic ester and the auxiliary agent is (80-120):(1-30); and / or the mass ratio of the modification liquid and the PHA fiber is (1-3):(8-10); and / or the concentration of the modification liquid is 35wt%-50wt%.

[0060] By adding the auxiliary agent to the polyhydroxyaliphatic ester, the production process can be improved and the product performance can be provided, preferably, the mass ratio of the polyhydroxyaliphatic ester and the auxiliary agent is (90-110):(5-30). By spraying the modification liquid on the surface of the PHA fiber, the emulsion product to be coated can be adhered and emulsified, and the combination effect of the PHA resin particles and the emulsion product can be improved, preferably, the mass ratio of the modification liquid and the PHA fiber is (1-2):(8-9). Preferably, the concentration of the modification liquid is 40wt%-45wt%.

[0061] In some embodiments of the application, the auxiliary agent includes at least one of an antioxidant, a heat stabilizer, an anti-blocking agent, and a coupling agent; and / or the modification liquid includes at least one of a surfactant and an emulsifier.

[0062] The antioxidant can avoid the product from yellowing, degradation and strength reduction caused by the oxidation of the resin itself, the antioxidant mainly includes phenolic primary antioxidant and auxiliary antioxidant such as thiodipropionic acid ester and phosphite, and the primary and auxiliary antioxidants are usually used together to play a synergistic effect, preferably, the content of the antioxidant is 0.1wt%-1.0wt%. The heat stabilizer can avoid thermal degradation during processing, the application selects 2-ethylhexanoate, fatty acid soap as the heat stabilizer, and further selects the fatty acid soap as the preferred one, wherein the calcium soap and zinc soap are non-toxic, and the two are used together to produce a synergistic effect, preferably, the content of the heat stabilizer is 3wt%-5wt%. The anti-blocking agent mainly includes leveling agent, opening agent, antistatic agent, which can improve the smoothness, anti-blocking, anti-static and anti-wear performance of the emulsion product, preferably, the content of the anti-blocking agent is 0.1wt%-3.0wt%. The coupling agent can improve the dispersion state of inorganic auxiliary materials in the polymer raw materials, and improve the mechanical properties and use performance of the product as a whole, the application selects silane coupling agent as the preferred one, the organic group of the silane coupling agent is selective to the reaction of the polymer, so the type of the silane coupling agent needs to be selected according to the type of the polymer, preferably, the content of the coupling agent is 1.0wt%-5.0wt%.

[0063] Further, the antioxidant can be antioxidant CA, LOWINOX 44B25, antioxidant RIANOX 1098, antioxidant RIANOX 1790, antioxidant RIANOX 168, antioxidant RIANOX 626. The heat stabilizer can be magnesium 2-ethylhexanoate, zinc 2-ethylhexanoate, zinc stearate, calcium stearate, calcium laurate, magnesium laurate. The anti-blocking agent can be oleic acid amide, stearic acid amide, BYK3700 silicone leveling agent, silica opening agent AB-MB-09, antistatic agent MOA3-PK. The coupling agent can be silane coupling agent Z-6020, silane coupling agent KH-550, silane coupling agent KBM-602, TTS, KR-38S.

[0064] The surfactant can improve the wetting and penetration effect of the emulsion product on the surface of the resin particles, and also has the functions of emulsification, dispersion and solubilization, and the anionic surfactant is preferred, mainly including sulfate, sulfonate and phosphate. The emulsifier can reduce the surface tension between the emulsion product and the resin particles, so that the emulsion product can rapidly spread to the whole surface of the particles, and at the same time, the stability of the formed emulsion is improved.

[0065] Further, the surfactant can be sodium lauryl sulfate, sodium stearate, sodium dodecyl benzene sulfonate and the like. The emulsifier can be fatty alcohol polyoxyethylene ether, polyvinyl alcohol, lecithin and the like.

[0066] The following examples 1-3 are further illustrations of the technical solutions of the application.

[0067] Example 1

[0068] The present embodiment provides a method for preparing PHA resin particles, comprising the following steps:

[0069] S11: The polyhydroxyalkanoate and the auxiliary agent are weighed according to a mass ratio of polyhydroxyalkanoate: auxiliary agent = 80: 1, and are subjected to a drying treatment at a temperature of 75°C for 6h to obtain a spinning raw material.

[0070] S12: The spinning raw material is fed into a double-screw extruder, and is subjected to melting at a screw rotation speed of 220r / min, and an extrusion temperature of 100°C to obtain a melt.

[0071] S13: The melt is filtered and metered, and is then subjected to a spinning treatment under vacuum and at a temperature of 165°C, and a spinning speed of 250m / min to obtain a PHA fiber.

[0072] S20: The PHA fiber is cooled, is stretched at a cooling temperature of 65°C, is modified by spraying a modifying liquid on the PHA fiber at a cooling temperature of 70°C, and is finally cooled and molded to obtain a modified PHA fiber. The mass ratio of the modifying liquid to the PHA fiber is 1:8, and the concentration of the modifying liquid is 35wt%.

[0073] S30: The modified PHA fiber is oiled, and is then wound and collected at a speed of 1400m / min, and is then cut and crushed in a ball mill under the condition of a protective atmosphere to obtain PHA resin particles.

[0074] Example 2

[0075] The present embodiment provides a method for preparing PHA resin particles, comprising the following steps:

[0076] S11: The polyhydroxyalkanoate and the auxiliary agent are weighed according to a mass ratio of polyhydroxyalkanoate: auxiliary agent = 120: 30, and are subjected to a drying treatment at a temperature of 80°C for 10h to obtain a spinning raw material.

[0077] S12: The spinning raw material is fed into a double-screw extruder, and is subjected to melting at a screw rotation speed of 420r / min, and an extrusion temperature of 180°C to obtain a melt.

[0078] S13: The melt is filtered and metered, and is then subjected to a spinning treatment under vacuum and at a temperature of 195°C, and a spinning speed of 550m / min to obtain a PHA fiber.

[0079] S20: cooling the PHA fiber, stretching at a cooling temperature of 75℃, modifying by spraying a modifying liquid on the PHA fiber at a cooling temperature of 80℃, and finally cooling and forming to obtain modified PHA fiber. The mass ratio of the modifying liquid to the PHA fiber is 3:10, and the concentration of the modifying liquid is 50wt%.

[0080] S30: oiling the modified PHA fiber, and then winding and collecting at a speed of 1600m / min, subsequently cutting the modified PHA fiber under the condition of a protective atmosphere, and putting it into a ball mill for crushing to obtain PHA resin particles.

[0081] Example 3

[0082] The embodiment provides a preparation method of PHA resin particles, comprising the following steps:

[0083] S11: weighing polyhydroxyalkanoate and an additive according to a mass ratio of polyhydroxyalkanoate: additive = 100:20, and drying the polyhydroxyalkanoate and the additive under a temperature condition of 78℃ for 8h to obtain spinning raw material.

[0084] S12: feeding the spinning raw material into a double-screw extruder, melting under a screw rotation speed of 300r / min, and obtaining a melt with an extrusion temperature of 150℃.

[0085] S13: filtering and metering the melt, and then spinning under a vacuum condition and a temperature condition of 180℃ at a spinning speed of 400m / min to obtain PHA fiber.

[0086] S20: cooling the PHA fiber, stretching at a cooling temperature of 70℃, modifying by spraying a modifying liquid on the PHA fiber at a cooling temperature of 75℃, and finally cooling and forming to obtain modified PHA fiber. The mass ratio of the modifying liquid to the PHA fiber is 2:9, and the concentration of the modifying liquid is 45wt%.

[0087] S30: oiling the modified PHA fiber, and then winding and collecting at a speed of 1500m / min, subsequently cutting the modified PHA fiber under the condition of a protective atmosphere, and putting it into a ball mill for crushing to obtain PHA resin particles.

[0088] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the same; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement to some technical features thereof; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing PHA resin particles, characterized in that, Includes the following steps: S10: Polyhydroxy fatty acid ester and auxiliaries are dried, melted and spun in sequence to obtain PHA fiber; S20: Cool the PHA fiber, and spray the modified liquid onto the surface of the PHA fiber during cooling to obtain modified PHA fiber; S30: The modified PHA fiber is sequentially oiled, wound, and crushed to obtain PHA resin particles; Specifically, S20 includes: stretching at a cooling temperature of 65℃-75℃, spraying the modified liquid onto the PHA fiber at a cooling temperature of 70℃-80℃ for modification, and finally cooling and molding to obtain the modified PHA fiber. The cooling process includes five stages of cooling, in the following order: the temperature of the first cooling stage is 85℃-102℃, the temperature of the second cooling stage is 65℃-75℃, the temperature of the third cooling stage is 60℃-65℃, the temperature of the fourth cooling stage is 70℃-80℃, and the temperature of the fifth cooling stage is 20℃-30℃. The stretching ratio is 6-10; S10 specifically includes: S11: Drying the polyhydroxy fatty acid ester and the auxiliary agent under vacuum conditions at a temperature of 75℃-80℃ for 6h-10h to obtain a spinning raw material; S12: Feeding the spinning raw material into a twin-screw extruder and melting it at a screw speed of 220r / min-420r / min and an extrusion temperature of 100℃-180℃ to obtain a melt; S13: Filtering and metering the melt, and then spinning it at a temperature of 165℃-195℃ and a spinning speed of 250m / min-550m / min to obtain the PHA fiber; The polyhydroxy fatty acid ester is a random copolymer or block copolymer with a monomer containing 6-14 carbon atoms in a medium-long chain and a melting point of 60℃-150℃.

2. The method for preparing PHA resin particles according to claim 1, characterized in that, S30 specifically includes: The modified PHA fiber is oiled, then wound and collected at a speed of 1400m / min-1600m / min. Subsequently, under a protective atmosphere, the modified PHA fiber is cut and pulverized in a ball mill to obtain the PHA resin particles.

3. The method for preparing PHA resin particles according to claim 2, characterized in that, The mass ratio of the grinding media to the PHA fiber in the ball mill is (3-7):1; The grinding media includes large balls and small balls, and the ratio of the number of large balls to the number of small balls is 1:

2.

4. The method according to claim 1, characterized in that, The mass ratio of the polyhydroxy fatty acid ester to the auxiliary agent is (80-120):(1-30); and / or The mass ratio of the modified liquid to the PHA fiber is (1-3):(8-10); and / or The concentration of the modified liquid is 35wt%-50wt%.

5. The method according to claim 4, characterized in that, The adjuvant includes at least one of antioxidants, heat stabilizers, anti-blocking agents, and coupling agents; and / or The modified liquid includes at least one of a surfactant and an emulsifier.

6. A PHA resin particle, characterized in that, The PHA resin particles are obtained by the preparation method as described in any one of claims 1 to 5.