Method for continuously and hermetically preparing high-molecular water-absorbent resin at normal temperature and normal pressure

Abstract

The invention discloses a method for continuously and hermetically preparing high-molecular water-absorbent resin at normal temperature and pressure, and belongs to the technical field of preparation of high-molecular water-absorbent resin. The invention provides a method for continuously and hermetically preparing high-molecular water-absorbent resin at normal temperature and pressure. The method comprises the following steps: step 1, preparing a reaction solution; step 2, continuously filling the reaction liquid into a plastic film bag, and forming a continuously produced first prefabricated body; and step 3, continuously carrying out closed polymerization reaction on the reaction liquid in the film bag through UV radiation. According to the method, the high-molecular water-absorbent resin is prepared in a closed and continuous manner in a normal-temperature and normal-pressure environment, heating and pressurizing equipment is not needed, and no gas is discharged outwards in the preparation process; on one hand, the product preparation cost is reduced; on the other hand, cleanliness, safety and stability in the preparation process are guaranteed. In addition, the continuous preparation method can greatly improve the preparation efficiency and the preparation scale of the product, and the product is high in monomer conversion rate, low in residual monomer and excellent in water absorption performance.

Description

Technical Field

[0001] The invention relates to the field of preparation of polymer water-absorbing resin, and in particular to a method for continuously and airtightly preparing polymer water-absorbing resin at room temperature and pressure. Background Art

[0002] SAP is a new type of functional polymer material that can absorb hundreds of times its own weight of water, and has good water retention capacity. It does not dehydrate under pressure. SAP also has a three-dimensional network structure, is insoluble in water and organic solvents, and has the ability to absorb urine, blood, fertilizers and organic drugs. Therefore, SAP has been widely used in agriculture, forestry, horticulture, physiology and hygiene, food, civil engineering, daily chemicals, life and health care, etc.

[0003] There are two main methods for the preparation of traditional SAP. The first is belt polymerization, which is an open "explosion" polymerization production method using a continuous belt reactor. Due to the polymerization heat, a large amount of volatile waste gas is generated, which is easy to cause equipment corrosion and environmental pollution, and the monomer residue is high and the output efficiency is low. The second is kettle polymerization, that is, the reaction conditions are controlled in the reactor to produce a polymerization reaction to generate a high molecular water-absorbing resin. Because the reaction liquid needs to be pressed out at high pressure to become a solid in the later stage, the reaction liquid ratio or reaction conditions are not properly controlled, there is a safety hazard of explosion. Summary of the invention

[0004] In order to solve the problems of low safety and high cost in the preparation of related polymer water-absorbing resins, the present invention provides a method for continuously and airtightly preparing polymer water-absorbing resins at normal temperature and pressure. Based on the energy of UV light (Ultraviolet Rays, i.e., ultraviolet light), the reaction rate of the polymerization reaction of the reaction liquid is controlled, no implosion occurs at normal temperature and pressure, and no waste gas is generated during the reaction in a closed environment, thereby ensuring the safety of the preparation process. In addition, the water-absorbing resin can be prepared efficiently and continuously, which greatly improves the preparation efficiency of the water-absorbing resin and reduces the preparation cost. The product has a high monomer conversion rate, low residual monomers, and excellent water absorption performance.

[0005] The embodiment of the present application provides a method for continuously and airtightly preparing a polymer water-absorbing resin at room temperature and pressure, comprising a filling module, a packaging module, a first transmission module and a polymerization module connected in sequence; The filling module comprises a material delivery port and a continuous material feeding assembly connected to the material delivery port; The continuous feeding component continuously outputs the reaction liquid through the feeding port, and the reaction liquid includes a polymerization monomer solution; The packaging module includes an automatic bag making mechanism connected to the material feeding port, and a continuous film supply component connected to the automatic bag making mechanism; The automatic bag making mechanism is used to continuously package the transparent plastic film provided by the continuous film supply component into continuous plastic reaction bags; The preparation steps include: S1, using a packaging module to prepare a plastic reaction bag with a sealed bottom and side and continuously produced, and at the same time, filling the plastic reaction bag with the reaction liquid through the feeding port of the filling module, and exhausting the gas in the plastic reaction bag to form a first preform that is continuously produced; S2, using a first transmission module to dock the first preform, and continuously transmitting the first preform to a polymerization module according to the output rate of the first preform; S3, the polymerization module continuously irradiates the first preform with UV light, and the UV light is used for UV radiation polymerization reaction of the reaction liquid, and continuously provides energy for the polymerization reaction, so that the reaction liquid undergoes a continuous and controllable polymerization reaction in a closed state wrapped in a plastic reaction bag, and the reaction liquid is converted from liquid to solid to form a water-absorbing resin gel.

[0006] By adopting the above technical scheme, the reaction liquid is placed in a sealed plastic reaction bag, and the continuous irradiation of UV light allows the UV light to directly participate in the polymerization reaction of the reaction liquid and provide energy for the polymerization of the reaction liquid itself, thereby controlling the polymerization reaction process of the reaction liquid, avoiding the traditional method of initiating the reaction liquid through UV light, high temperature and initiator to initiate the explosion reaction of the reaction liquid, thereby causing the reaction process to generate a large amount of reaction gas and heat, making it difficult to ensure the safety and environmental protection requirements of the reaction process.

[0007] On this basis, the first preform can be continuously generated through the filling module and the packaging module. On the one hand, the long-term reaction requirements of the UV polymerization reaction can be completed during the transportation process, and the continuity and sufficiency of the reaction process can be guaranteed; on the other hand, the first preform can be continuously produced and reacted, thereby greatly improving the efficiency of the preparation method, and the efficiency of the entire preparation process can be regulated by the production rate of the first preform, which has extremely flexible adaptability. It can also improve the monomer conversion rate of the reaction liquid and reduce the residual monomers in the obtained water-absorbing resin.

[0008] In some embodiments, the reaction solution is an aqueous solution of a homopolymer or copolymer of a hydrophilic polymer monomer, including an acrylic acid monomer, an acrylate monomer or an acrylamide monomer, and the starting temperature of the reaction solution is -10 to 25°C.

[0009] By adopting the above technical scheme, the temperature of the reaction liquid is set at -10~25℃. On the one hand, this temperature range conforms to the natural climate temperature of the factory processing environment and is easy to achieve and control; on the other hand, the temperature rise rate of the reaction liquid after the polymerization reaction begins can be controlled, thereby ensuring the uniformity, controllability and continuity of the polymerization reaction of the reaction liquid.

[0010] In some embodiments, the polymerization module uses UV light with a wavelength of 320-400 nm and an intensity of 1-30 mW / cm2.

[0011] The above technical solution ensures that the intensity of UV light is greater than 1mW / cm2, so that the radiation energy of UV light can be efficiently utilized to continuously promote the controllable polymerization reaction of the reaction liquid; and the UV light can completely irradiate and penetrate the entire plastic reaction bag, ensuring that the reaction liquid in the plastic reaction bag can evenly absorb the energy of UV light, ensuring the uniformity of the reaction process, improving the uniformity of the reaction liquid after the polymerization reaction, making the monomer conversion rate of the reaction liquid high and the residual monomer low. At the same time, avoid excessive UV light intensity, which will lead to too fast polymerization reaction, increase the difficulty of control, and affect the uniformity of the product.

[0012] In some embodiments, the first transmission module is configured as a conveyor belt for horizontal transmission; The step S2 comprises: The starting end of the first preform naturally slides down to the surface of the conveyor belt under the action of gravity; The conveyor belt drives the first preform toward the polymerization module, and makes the first preform lay flat on the surface of the conveyor belt; Furthermore, the thickness of the first preform is 50-150 mm.

[0013] The above technical solution is adopted to ensure that the first preform can be stably laid flat on the surface of the conveyor belt, which is convenient for subsequent UV light to illuminate the first preform; at the same time, the thickness of the first preform is 50~150mm, which can ensure that the thickness of the first preform is not too large, ensuring that the UV light can evenly illuminate the first preform, and can also avoid the thickness of the first preform being too small, affecting the overall preparation efficiency.

[0014] In some embodiments, the aggregation module includes a second transmission module docked with the first transmission module, and an illumination device arranged relatively spaced apart from the second transmission module; The second transmission module receives the first preform from the first transmission module and transmits the first preform at a uniform speed; The illumination device forms stable UV illumination toward the surface of the second transmission module; Step S3 includes: S31, irradiating the first preform with UV light for a first time period, so that the fluidity of the reaction liquid in the first preform decreases to a first threshold value; S32, turning the first preform upside down so that the bottom surface of the first preform faces the lighting device; S33, repeating step S32 every second time period until the water-absorbing resin gel is formed.

[0015] By adopting the above technical solution, the first preform is turned over at a fixed time to ensure the uniformity of the controllable polymerization reaction of the reaction liquid in the first preform and to guarantee the quality of the final product.

[0016] In some embodiments, the first duration is 5 to 100 minutes; the second duration is 5 to 60 minutes; In step S33, step S32 is repeated 1 to 8 times.

[0017] In some embodiments, the second transmission module includes a plurality of transmission belts spaced apart and arranged horizontally in the thickness direction, and a flipping mechanism connecting two adjacent transmission belts; The flip mechanism comprises a first flip belt and a second flip belt which are arranged opposite to each other, and a flip channel is formed between the first flip belt and the second flip belt; At the entrance of the turning channel, the first turning belt is butted against the lower conveyor belt, and the turning channel is bent in the thickness direction, so that at the exit of the turning channel, the second turning belt is butted against the upper conveyor belt; and the turning channel can clamp and fix the first preform to prevent the first preform from sliding in the turning channel; A lighting device is correspondingly arranged above each conveyor belt; The step S32 comprises: When the first preform is transmitted to the end of the conveyor belt, the first reversing belt and the second reversing belt clamp the first preform and enter the reversing channel; The turning channel drives the first preform to turn upside down, and transfers the turned first preform to the upper conveyor belt.

[0018] By adopting the above technical solution, multiple conveyor belts are arranged in the thickness direction, which is beneficial to reducing the overall footprint of the equipment. At the same time, it is convenient to set up a flipping mechanism between two adjacent conveyor belts; and the flipping mechanism can flip the first preform while stably transferring the first preform to the upper conveyor belt, thereby ensuring the continuity and stability of the entire preparation process.

[0019] In some embodiments, the continuous feeding assembly includes a plurality of storage tanks for storing the reaction solution; The plurality of storage tanks are all connected to the material delivery port, and supply materials to the material delivery port in sequence; The process of continuously outputting the reaction liquid includes: when the volume of the reaction liquid in the previous storage tank drops to a set value, the next storage tank starts to supply the material to the material delivery port, so that the two storage tanks supply the material to the material delivery port at the same time until the reaction liquid in the previous storage tank is emptied; The emptied storage tank is replenished with liquid to ensure continuous supply to the feed port.

[0020] In some embodiments, the transparent plastic film provided by the continuous film supply assembly is set as a transparent PE film, and a strip of transparent plastic film is continuously provided, and the transparent plastic film includes a first side and a second side along the conveying direction; The automatic bag making mechanism comprises a plurality of edge sealing devices arranged along the forming direction of the plastic reaction bag; The first edge and the second edge of the transparent plastic film wrap the conveying port and then overlap and enter into a plurality of edge sealing devices, and any one of the plurality of edge sealing devices heat-seals the first edge and the second edge.

[0021] By adopting the above technical scheme, multiple edge sealing devices can heat seal the first edge and the second edge, so that when the edge sealing device performing heat sealing is damaged or needs maintenance, the remaining edge sealing devices can be used for heat sealing to ensure the continuity and reliability of the working process of the automatic bag making mechanism.

[0022] In some embodiments, the continuous film supply assembly includes a plurality of film supply rolls, a connecting device, a buffer device, and a film feeding device; Any one of the plurality of film supply rolls sequentially connects the transparent plastic film to the connecting device, the buffer device and the film feeding device; The film feeding device guides the transparent plastic film to the automatic bag making mechanism, and the buffer device is used to buffer the transparent plastic film of the first length, and when the film supply roll stops supplying film, the buffer device can continue to provide the transparent plastic film of the first length; The continuous supplying step of the transparent plastic film comprises: The transparent plastic film of any one of the plurality of film supply rolls is sequentially conveyed to the connecting device, the buffer device and the film feeding device, and the buffer device starts to store the transparent plastic film of the first length; When the transparent plastic film of any film supply roll is exhausted, the connecting device clamps the tail end of the transparent plastic film, and the buffer device continues to convey the buffered transparent plastic film; Connecting the head end of the transparent plastic film of any other film supply roll among the multiple film supply rolls to the connecting device; After the connecting device heat-seals the tail end of the transparent plastic film and the head end of another transparent plastic film, it releases the clamping of the transparent plastic film; At this time, the buffer device starts to store the transparent plastic film while keeping conveying the transparent plastic film until the transparent plastic film of the first length is stored, thereby realizing the continuous supply of the transparent plastic film.

[0023] By adopting the above technical solution, when a roll of film supply roll is exhausted, the buffer device can still continue to provide the transparent plastic film of the first length. Therefore, during the process of the buffer device providing the transparent plastic film, another roll of film supply roll is connected to the tail end of the transparent plastic film of the exhausted film supply roll through the connecting device, thereby continuously supplying transparent plastic film without stopping the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of a process for continuously and airtightly preparing a polymer water-absorbing resin at room temperature and pressure according to an embodiment of the present application.

[0025] Description of reference numerals: 1. A first preform; 100. Filling module; 200, packaging module; 300, post-processing module; 400. Aggregation module. DETAILED DESCRIPTION

[0026] The content of the present invention can be more easily understood by selecting the following detailed description of the preferred implementation method of the present invention and the embodiments included. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those of ordinary skill in the art to which the present invention belongs. When there is a contradiction, the definition in this specification shall prevail. As used herein, the term "prepared by..." is synonymous with "comprising". The terms "comprising", "including", "having", "containing" or any other variation thereof used herein are intended to cover non-exclusive inclusions. For example, the composition, step, method, product or device comprising the listed elements need not be limited to those elements, but may include other elements that are not clearly listed or elements inherent to such composition, step, method, product or device.

[0027] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0028] When amount, concentration or other value or parameter is expressed as range, preferred range or a series of upper preferred value and lower preferred value limit range, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when disclosing range "1 to 5", described range should be interpreted as including range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc. When numerical range is described in this article, unless otherwise stated, the range is intended to include its end value and all integers and fractions within the range.

[0029] Singular forms include plural references unless the context clearly indicates otherwise. "Optional" or "either" means that the subsequently described event or incident may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

[0030] Approximate terms in the specification and claims are used to modify quantities, indicating that the present invention is not limited to the specific quantity, but also includes acceptable and modified parts close to the quantity without causing changes in the relevant basic functions. Accordingly, the use of "about", "approximately", etc. to modify a numerical value means that the present invention is not limited to the exact numerical value. In some examples, the approximate terms may correspond to the accuracy of the instrument for measuring the numerical value. In the specification and claims of this application, range limitations can be combined and / or interchanged, and if not otherwise stated, these ranges include all subranges contained therein.

[0031] In addition, the indefinite articles "a" and "an" before the elements or components of the present invention have no restrictions on the quantity requirements (i.e. the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted as including one or at least one, and the elements or components in the singular form also include the plural form, unless the number is obviously intended to be in the singular form.

[0032] It should be noted that the conventional implosion reaction using UV light (Ultraviolet Rays), high temperature and initiator as the initiating reaction liquid is to initiate a rapid polymerization reaction of part of the reaction liquid by using UV light, high temperature and initiator, and to continuously initiate the polymerization reaction by using the high temperature generated during the rapid polymerization reaction of the part of the reaction liquid and other initiators in the reaction liquid, and to generate a chain reaction to form an implosion phenomenon, generating high temperature, high pressure and gas byproducts. (Among them, the role of UV light is the same as that of high temperature, which mainly plays the role of improving the stability of the reaction liquid to initiate the implosion reaction, and after initiating the implosion reaction, it does not participate in the subsequent polymerization reaction of the reaction liquid).

[0033] Therefore, in the prior art, in order to reduce the high temperature and high pressure effects of the implosion reaction, the safety and controllability of the preparation process can also be ensured by reducing the volume of the reaction liquid involved in the polymerization reaction. For example, in belt polymerization, the prepared raw materials need to be evenly coated on the conveyor belt in small amounts and placed in an open environment to provide rapid volume expansion and temperature dissipation during the implosion reaction of the reaction liquid; then, the raw materials on the conveyor belt are heated to initiate the polymerization reaction; however, this method can only evenly coat a small amount of reaction liquid on the conveyor belt, the thickness is extremely small and it is difficult to seal (the thickness is usually less than 30 mm). On the one hand, the efficiency of the polymerization reaction is low and it is very easy to generate waste gas, polluting the indoor environment of the factory or requiring an increase in waste gas treatment costs. On the other hand, the thickness of the reaction liquid is extremely small, and it is difficult to control the uniformity of its polymerization reaction, resulting in a large amount of residual monomers in the final product and poor quality.

[0034] In the kettle reaction, the reaction liquid is placed in a reactor with high sealing and strength to ensure the airtightness of the reaction liquid during the polymerization reaction. However, the product after the polymerization of the reaction liquid is a gel-like solid structure, and it is necessary to use high pressure to press the product out of the reactor. In addition, during the polymerization reaction, once the reaction conditions are controlled, it is easy to cause an implosion reaction of the reaction liquid, thereby generating high temperature and high pressure, which is easy to cause the safety risk of the reactor explosion. Therefore, this method has extremely high requirements for the reactor and the production environment, and the polymer product produced by the implosion reaction is difficult to control the degree of monomer conversion of the polymer product due to the fast polymerization process, resulting in high residual monomers in the product and poor quality. Furthermore, the reaction process needs to be closed, and the continuous production of the product cannot be achieved, and the preparation efficiency of the product cannot be improved.

[0035] Therefore, please refer to Figure 1 , Figure 1 This is a schematic diagram of a process for continuously and airtightly preparing a polymer water-absorbing resin at room temperature and pressure according to an embodiment of the present application.

[0036] It should be noted that the structural schematic diagrams not shown in this application can all be implemented using conventional technical means in the prior art.

[0037] like Figure 1 As shown, the embodiment of the present application provides a method for continuously and airtightly preparing a polymer water-absorbing resin at room temperature and pressure, comprising a filling module 100, a packaging module 200, a first transmission module (not shown in the figure) and a polymerization module 400 connected in sequence; The filling module 100 includes a material delivery port and a continuous material supply assembly (not shown in the figure) connected to the material delivery port; The continuous feeding component continuously outputs the reaction liquid through the feeding port, and the reaction liquid includes a polymerization monomer solution; The packaging module 200 includes an automatic bag making mechanism docked with the material delivery port, and a continuous film supply assembly (not shown in the figure) connected with the automatic bag making mechanism; The automatic bag making mechanism is used to continuously package the transparent plastic film provided by the continuous film supply component into continuous plastic reaction bags; The preparation steps include: S1, using the encapsulation module 200 to prepare a plastic reaction bag with a sealed bottom and continuously produced, and at the same time, filling the plastic reaction bag with a reaction liquid through the feeding port of the filling module 100, and exhausting the gas in the plastic reaction bag to form a continuously produced first preform 1; S2, using the first transmission module to dock the first preform 1, and continuously transmitting the first preform 1 to the polymerization module 400 according to the output rate of the first preform 1; S3, the polymerization module 400 continuously irradiates the first preform 1 with UV light. The UV light is used for UV radiation polymerization reaction of the reaction liquid and continuously provides energy for the polymerization reaction, so that the reaction liquid undergoes a continuous and controllable polymerization reaction in a closed state wrapped in a plastic reaction bag. The reaction liquid is converted from liquid to solid to form a water-absorbing resin gel.

[0038] The reaction liquid is continuously irradiated by UV light, and the UV light is directly involved in the polymerization reaction of the reaction liquid. The reaction liquid uses the energy of UV light to break the chemical bonds of its monomers in stages, and under the action of UV light, the chemical bonds of the monomers in the reaction liquid undergo a controllable polymerization reaction, thereby avoiding the generation of a chain reaction similar to an implosion reaction and achieving a controllable polymerization reaction. As a result, no or only a small amount of additional gas byproducts are generated, so that the reaction liquid can be placed in a closed environment such as a plastic reaction bag for a controllable polymerization reaction.

[0039] Furthermore, due to the controllability of the polymerization process of the reaction liquid, the polymerization reaction of the reaction liquid fully irradiated with UV light is extremely complete, so that the purity of the reaction product is extremely high, thereby greatly improving the purity and quality of the final product.

[0040] Therefore, based on the above-mentioned polymerization method, the embodiment of the present application can also continuously generate the first preform 1 through the filling module 100 and the packaging module 200, so as to achieve the continuity of the reaction process. On the one hand, the efficiency of the preparation method is greatly improved; on the other hand, the efficiency of the entire preparation process can be regulated by the production rate of the first preform 1, which has extremely flexible adaptability.

[0041] In one embodiment, a post-processing module 300 for processing the prepared water-absorbing resin gel is also included. The post-processing module 300 can perform processes such as shredding, drying, and surface treatment on the water-absorbing resin gel to obtain a final polymer water-absorbing resin product.

[0042] In one embodiment, the reaction liquid is an aqueous solution of a homopolymer or copolymer of a hydrophilic polymer monomer, including an acrylic acid monomer, an acrylate monomer or an acrylamide monomer; the starting temperature of the reaction liquid is -10-25°C (natural climate temperature), and the degree of neutralization is 50-90%.

[0043] On the one hand, avoiding the use of initiators can prevent the initiators from initiating the implosion reaction of the reaction liquid, which will lead to high temperatures or large amounts of gas in the polymerization reaction, posing a safety hazard; at the same time, it can reduce the use of raw materials and reduce the cost of the preparation process. On the other hand, setting the temperature of the reaction liquid at -15~30℃ can prevent the temperature of the reaction liquid from rising too quickly after the polymerization reaction begins, thereby affecting the uniformity and controllability of the polymerization reaction of the reaction liquid.

[0044] In one embodiment, the starting temperature of the solution of acrylic acid monomer or sodium acrylate monomer is -10 to 25° C., or -5 to 15° C. In other alternative embodiments, the starting temperature may be less than -10° C., or may exceed 25° C.

[0045] In one embodiment, the reaction solution can be prepared by acid-base neutralization, and the neutralization degree thereof can be 50-90%. In other alternative embodiments, the neutralization degree of the reaction solution can be less than 50%, and the neutralization degree can also exceed 90%.

[0046] In another embodiment, when the reaction solution is an acrylic acid monomer solution or an acrylamide monomer solution, the concept of neutralization degree may not exist.

[0047] In one embodiment, the polymerization module 400 uses UV light with a wavelength of 320-400nm and an intensity of 1-30mW / cm2. When the intensity of UV light is greater than 1mW / cm2, the radiation energy of UV light can be efficiently utilized to continuously promote the controllable polymerization reaction of the reaction liquid; and the UV light can be fully irradiated and penetrate the entire plastic reaction bag to ensure that the reaction liquid in the plastic reaction bag can evenly absorb the energy of UV light, ensure the uniformity of the reaction process, and improve the uniformity of the reaction liquid after the polymerization reaction. At the same time, avoid excessive UV light intensity, which will cause the polymerization reaction to be too fast, increase the difficulty of control, and affect the uniformity of the product.

[0048] In one embodiment, the intensity of UV light is more preferably 3 to 15 mW / cm2.

[0049] It should be noted that the first preform 1 can be formed by a flexible plastic reaction bag that encloses the reaction liquid, and when the reaction liquid has not undergone a full polymerization reaction, its fluidity is relatively large.

[0050] Therefore, in order to ensure the stability of the transmission process, in one embodiment, the first transmission module is configured as a conveyor belt for horizontal transmission; thereby ensuring stable transmission of the first preform 1 .

[0051] Step S2 includes: The starting end of the first preform 1 naturally slides down to the surface of the conveyor belt under the action of gravity; On the one hand, under the action of gravity, the excess gas in the plastic reaction bag can be discharged from the upper opening, thereby reducing the gas falling into the first preform 1 on the conveyor belt, so as to ensure the uniformity and quality of the polymerization process.

[0052] At the same time, the conveyor belt drives the first preform 1 toward the polymerization module 400, and makes the first preform 1 flat on the surface of the conveyor belt; and the thickness of the first preform 1 is 50-150 mm.

[0053] It should be noted that the polymerization reaction of the reaction liquid in the first preform 1 relies on direct irradiation of ultraviolet rays, and ultraviolet rays have high penetrability, so the thickness of the first preform 1 can exceed 50 mm, thereby greatly improving the efficiency of the entire preparation process. The preparation thickness of the traditional belt-type "implosion" reaction is usually no more than 30 mm.

[0054] Furthermore, since there is intensity attenuation when UV light penetrates the first preform 1, and the first preform 1 has greater fluidity before the reaction, and the first preform 1 needs to be flipped during the subsequent preparation process; therefore, in a preferred embodiment, the thickness of the first preform 1 may not exceed 150 mm, thereby reducing the demand for the strength of the plastic reaction bag wrapping and facilitating UV polymerization, transmission and flipping of the first preform 1.

[0055] At the same time, it should be noted that the energy of the UV light decreases as the penetration distance increases during the process of penetrating the first preform 1, which will result in a higher polymerization efficiency on the side of the first preform 1 facing the UV light source and a lower polymerization efficiency on the side away from the UV light source, making it difficult to ensure the uniformity of the overall polymerization process of the first preform 1. Therefore, the thickness of the first preform 1 is not suitable to exceed 150 mm.

[0056] In other alternative embodiments, in the case of small batch production or when the production efficiency is not considered, the thickness of the first preform 1 may also be less than 50 mm, for example, set to 30 mm, 40 mm, 45 mm, etc. At the same time, in the case of using high-intensity UV light irradiation, or irradiating both sides of the first preform 1 at the same time, where the quality requirements are low and the efficiency requirements are high, the thickness of the first preform 1 may also exceed 150 mm, for example, set to 160 mm, 180 mm, 200 mm, etc.

[0057] In one embodiment, the starting end of the transparent plastic film may be heat-sealed, and then the reaction liquid may be poured in, and the gas at the starting end of the transparent plastic film may be evacuated under the action of gravity, thereby forming the starting end of the first preform 1 .

[0058] It should be noted that the larger the width of the first preform 1 is, the larger the volume of the reaction liquid it contains, the more difficult it is to flip, and the higher the containment strength of the plastic reaction bag and the UV light irradiation area required. Therefore, in one embodiment, the width of the first preform 1 can be 800-1500 mm.

[0059] In one embodiment, the aggregation module 400 includes a second transmission module docked with the first transmission module, and an illumination device disposed relatively spaced apart from the second transmission module; The second transmission module receives the first preform 1 from the first transmission module and transmits the first preform 1 at a uniform speed; The illumination device forms stable UV illumination towards the surface of the second transmission module.

[0060] It should be noted that due to the energy attenuation of UV light penetrating the first preform 1 , when the first preform 1 is only irradiated with UV light on one side, the polymerization reaction rates on the upper and lower sides of the first preform 1 are different, affecting the uniformity of the polymerization process of the first preform 1 .

[0061] Therefore, in one embodiment, step S3 includes: S31, irradiating the first preform 1 with UV light for a first time period, so that the fluidity of the reaction liquid in the first preform 1 decreases to a first threshold value; S32, turning the first preform 1 upside down so that the bottom surface of the first preform 1 faces the illumination device; S33, repeating step S32 every second time period until the water-absorbing resin gel is formed, so that both the upper and lower sides of the first preform 1 can be uniformly irradiated with UV light, thereby ensuring the uniformity of the overall polymerization process of the first preform 1, thereby improving the purity and quality of the water-absorbing resin.

[0062] In one embodiment, the first duration is 5 to 100 minutes; the second duration is 5 to 60 minutes; In step S33, step S32 is repeated 1 to 8 times.

[0063] It should be noted that the first time length and the second time length can be freely set according to the thickness of the first preform 1 and the intensity of the UV light setting, and it is only necessary to ensure that the fluidity of the first preform 1 can be reduced to the first threshold value after being irradiated for the first time length, so as to facilitate the flipping of the first preform 1. The second time length can be determined and controlled according to the transmission rate and length of the second transmission module, and depends on the total time length for the first preform 1 to fully react and the required number of flipping times.

[0064] Therefore, in other alternative implementations, the first duration may be less than 5 minutes, or greater than 100 minutes; the second duration may be less than 5 minutes, or greater than 60 minutes; and the number of flipping times may be greater than 8 times.

[0065] It should be noted that the first preform 1 at the beginning of the reaction has a high fluidity, so it needs to be transported by a horizontal conveyor belt, and in order to achieve the continuity of the preparation process, the first preform 1 needs to be transported unidirectionally on a specific path. At the same time, the first preform 1 needs to be turned over at least once on the path to complete the double-sided irradiation of the first preform 1.

[0066] Therefore, in one embodiment, the second conveying module includes a plurality of conveying belts spaced apart and arranged horizontally in the thickness direction, and a flipping mechanism (not shown in the figure) connecting two adjacent conveying belts; The turning mechanism comprises a first turning belt and a second turning belt which are arranged opposite to each other, and a turning channel is formed between the first turning belt and the second turning belt; At the entrance of the turning channel, the first turning belt is butted against the lower conveyor belt, and the turning channel is bent in the thickness direction, so that at the exit of the turning channel, the second turning belt is butted against the upper conveyor belt; and the turning channel can clamp and fix the first preform 1 to prevent the first preform 1 from sliding in the turning channel; A lighting device is correspondingly arranged above each conveyor belt; Step S32 includes: When the first preform 1 is transmitted to the end of the conveyor belt, the first turning belt and the second turning belt clamp the first preform 1 and enter the turning channel; The turning channel drives the first preform 1 to turn upside down, and transfers the turned first preform 1 to the upper conveyor belt.

[0067] Among them, arranging multiple conveyor belts in the thickness direction is beneficial to reducing the overall footprint of the equipment. At the same time, it is convenient to set up a flipping mechanism between two adjacent conveyor belts; and the flipping mechanism can flip the first preform 1 while stably transferring the first preform 1 to the upper conveyor belt, thereby ensuring the continuity and stability of the entire preparation process.

[0068] In other alternative embodiments, multiple conveyor belts may also be arranged in an S-shape, a circle-shape, etc. on the same horizontal plane to facilitate stable transmission of the first preform 1 and avoid extra energy loss caused by transporting the first preform 1 in the thickness direction.

[0069] It should be noted that, since the first preform 1 is a flexible structure of a plastic reaction bag wrapped with liquid, and the reaction product after the polymerization reaction of the reaction liquid of the first preform 1 is in a gel state, it has high flexibility. Therefore, in other alternative embodiments, the first preform 1 can be manually turned over between adjacent conveyor belts, and the reaction state of the first preform 1 can be manually detected during the turning process.

[0070] In one embodiment, the continuous feeding assembly includes a plurality of storage tanks for storing the reaction solution; Multiple storage tanks are connected to the material delivery port, and the material delivery port is supplied with materials in sequence; The process of continuously outputting the reaction liquid includes: when the volume of the reaction liquid in the previous storage tank drops to a set value, the next storage tank starts to supply the material to the material delivery port, so that the two storage tanks supply the material to the material delivery port at the same time until the reaction liquid in the previous storage tank is emptied; Refill the emptied storage tank with liquid to ensure continuous supply to the feed port.

[0071] In one embodiment, the transparent plastic film provided by the continuous film supply assembly is set as a transparent PE film, and a strip-shaped transparent plastic film is continuously provided, and the transparent plastic film includes a first side and a second side along the conveying direction; The automatic bag making mechanism includes a plurality of edge sealing devices arranged along the forming direction of the plastic reaction bag; The first edge and the second edge of the transparent plastic film wrap the conveying port and overlap to enter into a plurality of edge sealing devices, and any one of the plurality of edge sealing devices heat-seals the first edge and the second edge.

[0072] Among them, multiple edge sealing devices can heat seal the first edge and the second edge, so that when the edge sealing device performing heat sealing is damaged or needs maintenance, the remaining edge sealing devices can be used for heat sealing to ensure the continuity and reliability of the working process of the automatic bag making mechanism.

[0073] In one embodiment, the continuous film supply assembly includes a plurality of film supply rolls, a connecting device, a buffer device, and a film feeding device; Any one of the plurality of film supply rolls sequentially connects the transparent plastic film to the connecting device, the buffer device and the film feeding device; The film feeding device guides the transparent plastic film to the automatic bag making mechanism, and the buffer device is used to buffer the transparent plastic film of the first length, and when the film supply roll stops supplying film, the buffer device can continue to provide the transparent plastic film of the first length; The continuous supply steps of transparent plastic film include: The transparent plastic film of any one of the plurality of film supply rolls is sequentially conveyed to the connecting device, the buffer device and the film feeding device, and the buffer device starts to store the transparent plastic film of the first length; When the transparent plastic film of any film supply roll is exhausted, the connecting device clamps the tail end of the transparent plastic film, and the buffer device continues to convey the buffered transparent plastic film; Connecting the head end of the transparent plastic film of any other film supply roll among the multiple film supply rolls to the connecting device; After the connecting device heat-seals the tail end of the transparent plastic film and the head end of another transparent plastic film, it releases the clamping of the transparent plastic film; At this time, the buffer device starts to store the transparent plastic film while keeping conveying the transparent plastic film until the transparent plastic film of the first length is stored, thereby realizing the continuous supply of the transparent plastic film.

[0074] When a film supply roll is used up, the buffer device can still continue to provide the transparent plastic film of the first length. Therefore, during the process of the buffer device providing the transparent plastic film, another film supply roll is connected to the tail end of the transparent plastic film of the exhausted film supply roll through the connecting device, thereby continuously supplying transparent plastic film without stopping the preparation process.

[0075] The implementation mode of the present application realizes the closed and continuous preparation of the polymer absorbent resin gel under normal temperature and pressure, that is, no heating equipment or pressurizing equipment is needed, thereby reducing the equipment cost, and then reducing the manufacturing cost, and improving the safety of the preparation process. At the same time, the closed preparation does not emit any harmful gases to the outside, and no treatment equipment is required, which achieves environmental protection while further controlling the preparation cost. In addition, continuous preparation production improves the preparation efficiency and preparation scale, and further reduces the preparation cost.

[0076] Three specific embodiments are given below to specifically illustrate the technical effect of the controllable polymerization reaction of the present application.

[0077] Embodiment 1: Step 1, preparing a reaction solution: adding alkali to acrylic acid to prepare a sodium acrylate aqueous solution with a neutralization degree of 60%, the temperature of which is controlled at 5° C., and the amount of the reaction solution can meet the needs of subsequent continuous filling and continuous polymerization; wherein the neutralized solution is the reaction solution of Example 1; Step 2, continuous filling to form a continuously produced first preform 1: continuously filling the neutralization solution into the transparent PE film tube to form a continuous first preform 1, and controlling the width of the first preform 1 to be 1000 mm and the thickness to be 120 mm; Step 3, continuous polymerization reaction: the first preform 1 is placed under UV light source with a wavelength of 385nm and an intensity of 20mW / cm2 for 90min, so that the neutralized solution undergoes polymerization reaction to generate a polymer water-absorbing resin gel, wherein the preform is turned over every 30min.

[0078] The polymer water-absorbent resin gel is subjected to the processes of cutting, drying, surface treatment, etc., and the final polymer water-absorbent resin product is obtained.

[0079] According to GB / T22875-2018, the following results were obtained:

[0080] It can be seen from the above table that all indicators of the water-absorbing resin prepared in Example 1 meet the standard indicators, especially the residual monomer indicator far exceeds the standard indicator.

[0081] Embodiment 2: Step 1, preparing a reaction solution: adding acrylic acid to an aqueous solution of potassium acrylate having a neutralization degree of 80% by potassium hydroxide to obtain a reaction solution, the temperature of which is controlled at 0°C; Step 2, continuous filling to form a continuously produced first preform 1: continuously filling the reaction liquid into the transparent PE film tube to form a continuous first preform 1, and controlling the width of the first preform 1 to be 1000 mm and the thickness to be 100 mm; Step 3, continuous polymerization reaction: synchronously with filling, the first preform 1 is sent into the polymerization reaction zone, and is placed under the irradiation of a UV light source with a wavelength of 320nm and an intensity of 15mW / cm2 for 120min, so that the neutralized solution undergoes a polymerization reaction to generate a polymer water-absorbing resin gel, wherein the preform is turned over every 40min. The polymer water-absorbing resin gel is subjected to processes such as shredding, drying, and surface treatment, and the final polymer water-absorbing resin product is obtained.

[0082] In Example 2, based on Example 1, the initial temperature of the reaction solution is lowered and the neutralization degree is increased. At the same time, the wavelength and intensity of the UV light are lowered, and the second duration of the flipping and the total irradiation duration are increased.

[0083] According to GB / T22875-2018, the following results were obtained:

[0084] It can be seen from the above table that all indicators of the water-absorbent resin product prepared in Example 2 meet the standard indicators, and the residual monomer is further improved compared with Example 1. At the same time, the absorption capacity, water retention capacity and pressurized absorption capacity also exceed the standard indicators, especially the residual monomer index far exceeds the standard indicator and similar products in the prior art.

[0085] Embodiment 3: Step 1, preparing a reaction solution: adding acrylic acid to a sodium acrylate aqueous solution having a neutralization degree of 75% by sodium hydroxide, and adding acrylamide to obtain a reaction solution, the temperature of which is controlled at -3°C; Step 2, continuous filling to form a continuously produced first preform 1: continuously filling the reaction liquid into the transparent PE film tube to form a continuous first preform 1, and controlling the width of the first preform 1 to be 1000 mm and the thickness to be 60 mm; Step 3, continuous polymerization reaction: synchronously with filling, the first preform 1 is sent into the polymerization reaction zone, and is placed under the irradiation of a UV light source with a wavelength of 360nm and an intensity of 10mW / cm2 for 150min, so that the neutralized solution undergoes a polymerization reaction to generate a polymer water-absorbing resin gel, wherein the preform is turned over every 30min. The polymer water-absorbing resin gel is subjected to processes such as shredding, drying, and surface treatment, and the final polymer water-absorbing resin product is obtained.

[0086] Among them, compared with Example 2, Example 3 further reduces the starting temperature of the reaction liquid and controls the neutralization degree within a reasonable range; at the same time, the wavelength of the UV light is set to 360nm, and the intensity is set to 10mW / cm2, which reduces the second time for flipping, increases the flipping frequency, and further increases the total irradiation time.

[0087] According to GB / T22875-2018, the following results were obtained:

[0088] It can be seen from the above table that various indicators of the polymer water-absorbing resin product prepared in Example 3 are further improved on the basis of Example 2, and all exceed the current standard indicators, especially the residual monomer indicator is further optimized.

[0089] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A method for preparing a polymer water-absorbing resin in a continuous and closed manner at room temperature and pressure, characterized in that: It includes a filling module, a packaging module, a first transmission module and an aggregation module connected in sequence; The filling module comprises a material delivery port and a continuous material feeding assembly connected to the material delivery port; The continuous feeding component continuously outputs the reaction liquid through the feeding port, and the reaction liquid includes a polymerization monomer solution; The packaging module includes an automatic bag making mechanism docked with the feeding port, and a continuous film supply component connected to the automatic bag making mechanism; The automatic bag making mechanism is used to continuously package the transparent plastic film provided by the continuous film supply component into continuous plastic reaction bags; The preparation steps include: S1, using a packaging module to prepare a plastic reaction bag with a sealed bottom and side and continuously produced, and at the same time, filling the plastic reaction bag with the reaction liquid through the feeding port of the filling module, and exhausting the gas in the plastic reaction bag to form a first preform that is continuously produced; S2, using a first transmission module to dock the first preform, and continuously transmitting the first preform to a polymerization module according to the output rate of the first preform; S3, the polymerization module continuously irradiates the first preform with UV light, and the UV light is used for UV radiation polymerization reaction of the reaction liquid, and continuously provides energy for the polymerization reaction, so that the reaction liquid undergoes a continuous and controllable polymerization reaction in a closed state wrapped in a plastic reaction bag, and the reaction liquid is converted from liquid to solid to form a water-absorbing resin gel.

2. The method for preparing a high molecular water-absorbing resin in a continuous and closed manner at normal temperature and pressure according to claim 1, characterized in that: The reaction liquid is an aqueous solution of a homopolymer or copolymer of a hydrophilic polymer monomer, including an acrylic acid monomer, an acrylate monomer or an acrylamide monomer, and the initial temperature of the reaction liquid is -10 to 25°C.

3. The method for preparing a high molecular water-absorbing resin in a continuous and closed manner at normal temperature and pressure according to claim 1, characterized in that: The polymerization module uses UV light with a wavelength of 320-400 nm and an intensity of 1-30 mW / cm2.

4. The method for preparing a high molecular water-absorbing resin in a continuous and closed manner at normal temperature and pressure according to claim 1, characterized in that: The first transmission module is configured as a conveyor belt for horizontal transmission; The step S2 comprises: The starting end of the first preform naturally slides down to the surface of the conveyor belt under the action of gravity; The conveyor belt drives the first preform toward the polymerization module, and makes the first preform spread on the surface of the conveyor belt; and the thickness of the first preform is 50-150 mm.

5. The method for preparing a high molecular water-absorbing resin in a continuous and closed manner at normal temperature and pressure according to claim 1, characterized in that: The aggregation module includes a second transmission module connected to the first transmission module, and a UV irradiation device arranged relatively spaced apart from the second transmission module; The second transmission module receives the first preform from the first transmission module and transmits the first preform at a uniform speed; The illumination device forms stable UV illumination toward the surface of the second transmission module; Step S3 includes: S31, irradiating the first preform with UV light for a first time period, so that the fluidity of the reaction liquid in the first preform decreases to a first threshold value; S32, turning the first preform upside down so that the bottom surface of the first preform faces the lighting device; S33, repeating step S32 every second time period until the water-absorbing resin gel is formed.

6. The method for preparing a high molecular water-absorbing resin in a continuous and closed manner at normal temperature and pressure according to claim 5, characterized in that: The first duration is 5 to 100 minutes; the second duration is 5 to 60 minutes; In step S33, step S32 is repeated 1 to 8 times.

7. The method for preparing a high molecular water-absorbing resin in a continuous and closed manner at normal temperature and pressure according to claim 5, characterized in that: The second transmission module includes a plurality of transmission belts spaced apart and arranged horizontally in the thickness direction, and a turning mechanism connecting two adjacent transmission belts; The flip mechanism comprises a first flip belt and a second flip belt which are arranged opposite to each other, and a flip channel is formed between the first flip belt and the second flip belt; At the entrance of the turning channel, the first turning belt is butted against the lower conveyor belt, and the turning channel is bent in the thickness direction, so that at the exit of the turning channel, the second turning belt is butted against the upper conveyor belt; and the turning channel can clamp and fix the first preform to prevent the first preform from sliding in the turning channel; A lighting device is correspondingly arranged above each conveyor belt; The step S32 comprises: When the first preform is transmitted to the end of the conveyor belt, the first reversing belt and the second reversing belt clamp the first preform and enter the reversing channel; The turning channel drives the first preform to turn upside down, and transfers the turned first preform to the upper conveyor belt.

8. The method for preparing a high molecular water-absorbing resin in a continuous and closed manner at normal temperature and pressure according to claim 1, characterized in that: The continuous feeding assembly includes a plurality of storage tanks for storing reaction liquid; The plurality of storage tanks are all connected to the material delivery port, and supply materials to the material delivery port in sequence; The process of continuously outputting the reaction liquid includes: when the volume of the reaction liquid in the previous storage tank drops to a set value, the next storage tank starts to supply the material to the material delivery port, so that the two storage tanks supply the material to the material delivery port at the same time until the reaction liquid in the previous storage tank is emptied; The emptied storage tank is replenished with liquid to ensure continuous supply to the feed port.

9. The method for preparing a high molecular water-absorbing resin in a continuous and closed manner at normal temperature and pressure according to claim 1, characterized in that: The transparent plastic film provided by the continuous film supply assembly is set as a transparent plastic film, and continuously provides a strip of transparent plastic film, wherein the transparent plastic film includes a first side and a second side along a conveying direction; The automatic bag making mechanism comprises a plurality of edge sealing devices arranged along the forming direction of the plastic reaction bag; The first edge and the second edge of the transparent plastic film wrap the conveying port and then overlap and enter into a plurality of edge sealing devices, and any one of the plurality of edge sealing devices heat-seals the first edge and the second edge.

10. The method for preparing a high molecular water-absorbing resin in a continuous and closed manner at normal temperature and pressure according to claim 1, characterized in that: The continuous film supply assembly includes a plurality of film supply rolls, a connecting device, a buffer device and a film feeding device; Any one of the plurality of film supply rolls sequentially connects the transparent plastic film to the connecting device, the buffer device and the film feeding device; The film feeding device guides the transparent plastic film to the automatic bag making mechanism, and the buffer device is used to buffer the transparent plastic film of the first length, and when the film supply roll stops supplying film, the buffer device can continue to provide the transparent plastic film of the first length; The continuous supplying step of the transparent plastic film comprises: The transparent plastic film of any one of the plurality of film supply rolls is sequentially conveyed to the connecting device, the buffer device and the film feeding device, and the buffer device starts to store the transparent plastic film of the first length; When the transparent plastic film of any film supply roll is exhausted, the connecting device clamps the tail end of the transparent plastic film, and the buffer device continues to convey the buffered transparent plastic film; Connecting the head end of the transparent plastic film of any other film supply roll among the multiple film supply rolls to the connecting device; After the connecting device heat-seals the tail end of the transparent plastic film and the head end of another transparent plastic film, it releases the clamping of the transparent plastic film; At this time, the buffer device starts to store the transparent plastic film while keeping conveying the transparent plastic film until the transparent plastic film of the first length is stored, thereby realizing the continuous supply of the transparent plastic film.

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