Method for accelerating dissolution of polyvinyl alcohol
The present invention discloses a method for accelerating the dissolution of polyvinyl alcohol, which uses mechanical activation to treat polyvinyl alcohol, destroys its molecular structure, and adds a solid small molecule solvent while mechanically activating, and the solid small molecule solvent penetrates into In the polyvinyl alcohol molecule, it causes solid phase swelling, thereby achieving rapid dissolution of polyvinyl alcohol. The method adopted by the invention has low energy consumption, short time-consuming, simple operation, no pollution, no high temperature and high pressure, and is an environment-friendly method; the mechanical activation treatment of polyvinyl alcohol pre-destroys the hydrogen bond between the polyvinyl alcohol molecules and The crystal structure effectively shortens the dissolution time of the polyvinyl alcohol; the solid phase swelling of the polyvinyl alcohol is shortened, and the time of interaction with the liquid solvent is shortened; in the dissolution process, the solid-liquid two solvents are relatively infiltrated, greatly improving The dissolution efficiency of polyvinyl alcohol; at the same time, the method has wide applicability and can effectively improve the solubility of the water-soluble polymer, especially for the polyhydroxy compound.
A method for accelerating the dissolution of polyvinyl alcohol
The present invention belongs to the field of polymer materials, and in particular relates to a method for accelerating the dissolution of polyvinyl alcohol by mechanical activation and solid phase swelling.
Polyvinyl alcohol (PVA) is a non-toxic water-soluble polymer which is widely used in the fields of fibers, films, medicines, adhesives and the like. Polyvinyl alcohol is a polyhydroxy compound, which is very hydrophilic, but polyvinyl alcohol particles are hardly soluble in water, which severely limits the application and development of polyvinyl alcohol. The dissolution process of polyvinyl alcohol in water is complicated, and it differs greatly depending on its degree of polymerization and degree of alcoholysis. The reason is due to the intermolecular and intramolecular hydrogen bonding and high crystallinity of polyvinyl alcohol. Therefore, exploring a method for rapidly dissolving polyvinyl alcohol is a major practical problem faced by current industrial production.
In order to rapidly dissolve polyvinyl alcohol, it has been explored from the preparation stage of polyvinyl alcohol. For example, Chinese Patent No. CN 102827316 A discloses a process for preparing a low crystallinity polyvinyl alcohol. The method comprises the steps of polymerization, alcoholysis and drying of the respective units, and the alcohol-decomposed polyvinyl alcohol semi-finished product is dried by hot air at 30 to 120 ° C for 0.5 to 5 hours to obtain a low crystallinity polyvinyl alcohol, and the prepared product is dissolved. Performance has improved. This method is explored from the preparation stage of polyvinyl alcohol, and is not applicable to the problem of difficulty in dissolving the finished polyvinyl alcohol.
At present, the usual dissolution methods for the finished polyvinyl alcohol are heating and stirring methods and modification methods. The heating and stirring method is high-temperature cooking, high-speed stirring, and the dissolution process is as long as 2 to 4 hours, and the energy consumption is extremely high; the modification method is to introduce some hydrophilic groups into the polyvinyl alcohol molecule to enhance the water solubility of the polyvinyl alcohol. Although this method can solve the problem of difficulty in dissolving polyvinyl alcohol, in general, the introduced group easily affects other properties of polyvinyl alcohol, such as viscosity, permeability, and the like. Therefore, it is of great practical significance to find a new dissolution method with low energy consumption, short time consumption and no degradation of the excellent properties of polyvinyl alcohol.
[Summary of the Invention]
In view of the deficiencies in the above prior art, the present invention provides a method for solving the problem of accelerated polyvinyl alcohol dissolution in which polyvinyl alcohol has high energy consumption and long time.
In order to solve the above technical problem, the present invention adopts the following technical solutions:
A method for accelerating the dissolution of polyvinyl alcohol, which uses mechanical activation to treat polyvinyl alcohol, destroys its molecular structure, and adds a solid small molecule solvent while mechanically activating, and the solid small molecule solvent penetrates into the polyvinyl alcohol molecule, thereby making it Solid phase swelling occurs to achieve rapid dissolution of polyvinyl alcohol.
As a preferred embodiment of the present invention, the mechanical activation comprises two stages: a pretreatment stage and a mechanical force treatment stage;
The pretreatment stage refers to pretreating polyvinyl alcohol by microwave, light irradiation, ultrasonic, electric field or magnetic field; the mechanical force treatment stage refers to friction, collision, impact or pretreatment of the pretreated polyvinyl alcohol. Shear mechanical force treatment.
As another preferred embodiment of the present invention, the molecular structure is a hydrogen bond structure and a crystal structure.
As a further preferred embodiment of the present invention, solid phase swelling refers to the spontaneous or non-spontaneous entry of solid small molecular substances into the polymer molecular chain, weakening or destroying the force between the polymer molecular chains, or inserting into In the crystal lattice of the polymer, the lattice of the polymer is distorted, and the volume of the polymer is expanded to some extent.
As a modification of the present invention, the solid phase swelling treatment of polyvinyl alcohol refers to mixing a solid small molecule solvent with polyvinyl alcohol, and a solid small molecular substance enters the molecule of polyvinyl alcohol during mechanical activation. Between the chains, the force between the molecular chains of the polyvinyl alcohol is weakened or destroyed, or inserted into the crystal lattice of the polyvinyl alcohol, the lattice of the polyvinyl alcohol is distorted, and the volume of the polyvinyl alcohol is expanded to some extent.
As another modification of the present invention, the solid small molecule solvent is a substance having strong polarity or strong permeability.
As a further improvement of the present invention, polyvinyl alcohol dissolution means that the polyvinyl alcohol is dissolved at 30 to 95 °C.
As a further improvement of the present invention, the polyvinyl alcohol is a polyvinyl alcohol which has undergone mechanical activation and solid phase swelling treatment.
Compared with the prior art, the present invention has the following beneficial effects:
1. The method adopted by the invention has low energy consumption, short time consumption, simple operation, no pollution, no high temperature and high pressure, and is an environment-friendly method.
2. The invention adopts mechanical activation treatment of polyvinyl alcohol, which pre-destroys the hydrogen bond and crystal structure between the polyvinyl alcohol molecules, and effectively shortens the dissolution time of the polyvinyl alcohol.
3. The present invention causes the polyvinyl alcohol to solid phase swell and shorten the time of interaction with the liquid solvent.
4. The polyvinyl alcohol treated by the method of the invention has a relative penetration of the solid and liquid solvents during the dissolution process, thereby greatly improving the dissolution efficiency of the polyvinyl alcohol.
5. The method of the present invention has wide applicability and can effectively improve the solubility of the water-soluble polymer, especially for the polyhydroxy compound.
【detailed description】
The present invention will be described in further detail below in conjunction with the Detailed Description.
A method for accelerating the dissolution of polyvinyl alcohol, the polyvinyl alcohol is treated by mechanical activation for 3 min to 5 min; then the pretreated polyvinyl alcohol is uniformly mixed with the solid small molecule solvent, and mechanically treated for 30 min to 60 min. The polyvinyl alcohol which has been mechanically activated and solid-phase swelled is added to deionized water, and dissolved at 30 to 95 ° C to dissolve.
wherein polyvinyl alcohol (PVA) is treated by a mechanical activation method, the mechanical activation comprising two stages: a pretreatment stage and a mechanical force treatment stage. The pretreatment stage refers to pretreatment of polyvinyl alcohol by microwave, light irradiation, ultrasonic, electric field or magnetic field, etc., so that the toughness of PVA is reduced, brittleness is increased, and preparation for mechanical force treatment is prepared. The mechanical force treatment stage refers to the mechanical treatment of friction, collision, impact or shearing of the pretreated polyvinyl alcohol. The mechanical force processing equipment includes stone grinding, ball mill, pulverizer, etc., according to the principle of energy conservation, mechanical energy The internal energy of polyvinyl alcohol is converted into energy, the energy is enhanced, the activity is enhanced, the stability of the polymer is weakened, the order of structure is weakened, the hydrogen bond association between molecules is weakened, and the crystallinity is lowered, thereby achieving rapid dissolution. The purpose of PVA.
The solid phase swelling treatment PVA is used to make the solid small molecular substances spontaneously or non-spontaneously enter the molecular chain of the polyvinyl alcohol, weaken or destroy the force between the polyvinyl alcohol molecular chains, or insert into the polyvinyl alcohol. In the crystal lattice, the lattice of the polyvinyl alcohol is distorted, and the volume of the polyvinyl alcohol is expanded to some extent. Its molecular structure, especially hydrogen bonding and crystal structure, is destroyed. The solid small molecule solvent can also be mixed with polyvinyl alcohol. During the mechanical activation process, the solid small molecular substance enters the molecular chain of the polyvinyl alcohol, weakening or destroying the force between the polyvinyl alcohol molecular chains, or inserting into the poly In the crystal lattice of vinyl alcohol, the lattice of the polyvinyl alcohol is distorted, and the volume of the polyvinyl alcohol is expanded to some extent.
The solid phase swelling is carried out while mechanically activating the polyvinyl alcohol, and the two mutually promote each other, and the crystal structure and hydrogen bond association of the polyvinyl alcohol can be destroyed to the greatest extent, thereby further accelerating the dissolution of the PVA. A solid small molecule solvent is a substance having strong polarity or strong permeability. Polyvinyl alcohol is a polyvinyl alcohol which has undergone mechanical activation and solid phase swelling treatment.
Embodiment 1
Weigh 30g PVA, ultrasonic pretreatment for 4min, and then mix with 0.03g urea and 0.05g nitrosoethylene. After the mixture is activated by stone grinding for 30min, take 20g of the treated mixture, add 280g of water, and then heat up. Dissolution was carried out at 30 °C.
Embodiment 2
Weigh 30g of PVA, put it in a microwave oven for 4min, mix it with 0.25g of urea and 0.3g of nitro-methane. Then, use a ball mill to activate the mixture for 35min, take 20g of the treated mixture, add 280g of water, then The temperature was raised to 45 ° C for dissolution.
Embodiment 3
Weigh 30g of PVA, irradiate with light for 5min, mix with 0.5g of melamine and 0.8g of nitromethane, then activate the mixture with a pulverizer for 40min, take 20g of the treated mixture, add 280g of water, and then heat up to 65 Dissolved at °C.
[0027] Embodiment 4
Weigh 30g of PVA, electric field treatment for 5min, and then mix well with 0.8g of melamine and 1.5g of urea, then activate the mixture with stone mill for 45min, take 20g of treated mixture, add 280g of water, and then heat up to 85 °C Dissolve.
Embodiment 5
30 g of PVA was weighed, placed in a magnetic field for 3 min, and then mixed with 1.2 g of melamine and 2 g of nitrosoethylene. The mixture was activated by a pulverizer for 50 min, 20 g of the treated mixture was taken, and 280 g of water was added. The temperature was raised to 95 ° C for dissolution.
It is to be understood that the above embodiments are merely illustrative of the present invention and are not to be construed as limiting. The technical solutions are modified or equivalent, without departing from the spirit and scope of the invention, and are intended to be included within the scope of the appended claims.
A method for accelerating the dissolution of polyvinyl alcohol, characterized in that polyvinyl alcohol is treated by mechanical activation to destroy its molecular structure, a solid small molecule solvent is added while mechanically activated, and a solid small molecule solvent is infiltrated into the polyethylene. In the alcohol molecule, it causes solid phase swelling, thereby achieving rapid dissolution of polyvinyl alcohol.
A method of accelerating the dissolution of polyvinyl alcohol according to claim 1, wherein said mechanical activation comprises two stages: a pretreatment stage and a mechanical force treatment stage; said pretreatment stage means gathering The vinyl alcohol is pretreated by microwave, light irradiation, ultrasonic, electric field or magnetic field; the mechanical force treatment stage refers to friction, collision, impact or shear mechanical treatment of the pretreated polyvinyl alcohol.
A method of accelerating the dissolution of polyvinyl alcohol according to claim 1, wherein the molecular structure is a hydrogen bond structure and a crystal structure.
The method for accelerating the dissolution of polyvinyl alcohol according to claim 1, wherein the solid phase swelling means that the solid small molecular substance enters the polymer molecular chain spontaneously or non-spontaneously, and weakens or destroys the polymer molecule. The force between the chains, or inserted into the crystal lattice of the polymer, causes the lattice of the polymer to be distorted and the volume of the polymer to expand to some extent.
The method for accelerating the dissolution of polyvinyl alcohol according to claim 1, wherein the solid phase swelling treatment of the polyvinyl alcohol means mixing the solid small molecule solvent with the polyvinyl alcohol during the mechanical activation process. The solid small molecular substance enters the molecular chain of the polyvinyl alcohol, weakens or destroys the force between the molecular chains of the polyvinyl alcohol, or is inserted into the crystal lattice of the polyvinyl alcohol to deform the lattice of the polyvinyl alcohol, and the polyethylene The volume of alcohol undergoes a certain degree of expansion.
A method of accelerating the dissolution of polyvinyl alcohol according to claim 1, wherein the solid small molecule solvent is a substance having strong polarity or strong permeability.
A method of accelerating the dissolution of polyvinyl alcohol according to claim 1, wherein the dissolution of polyvinyl alcohol means that the polyvinyl alcohol is dissolved at 30 to 95 °C.
A method of accelerating the dissolution of polyvinyl alcohol according to claim 1, wherein the polyvinyl alcohol is a polyvinyl alcohol which has undergone mechanical activation and solid phase swelling treatment.
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