1. A mother liquor for use in the preparation of styrene-maleic anhydride copolymers by photo-initiated polymerization, comprising: a comonomer, a photoinitiator and an organic solvent,

the mass percent of the comonomer is 5-30 wt% relative to the total weight of the mother liquor,

the mass percentage of the photoinitiator relative to the comonomer is 0.2-4.0 wt%,

the comonomer contains styrene and maleic anhydride, and the molar ratio of the styrene to the maleic anhydride is 1: 1-1.5: 1.

2. The mother liquor of claim 1, wherein the photoinitiator is a photolytic initiator and/or a hydrogen abstraction photoinitiator.

3. The mother liquor according to claim 2, wherein the photolytic initiator is at least one selected from the group consisting of α -hydroxyketone photoinitiators 1173, α -hydroxyketone photoinitiators 184, α -hydroxyketone photoinitiators 2959, photoinitiators 651, oxalate photoinitiators MBF, α -aminoketone photoinitiators 907, α -aminoketone photoinitiators 369, acylphosphino photoinitiators TPO, acylphosphino photoinitiators 819, represented by the following structural formula;

the hydrogen abstraction type photoinitiator is at least one of benzophenone photoinitiator BP, benzophenone photoinitiator EMK and thioxanthone photoinitiator ITX shown in the following structural formula and at least one of MDEA and EDB used as co-initiator,

4. the mother liquor according to any one of claims 1 to 3, wherein the organic solvent is at least one selected from butyl acetate, isobutyl acetate, sec-butyl acetate, amyl acetate, isoamyl acetate, benzyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, isoamyl butyrate, ethyl isovalerate, isoamyl isovalerate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, isoamyl benzoate, methyl phenylacetate and ethyl phenylacetate.

5. The mother liquor as claimed in claim 1, wherein the comonomer further comprises alpha-methyl styrene and vinyl acetate, and the content of maleic anhydride, styrene, alpha-methyl styrene and vinyl acetate is 40-50%, 10-20% and 20-30% respectively by mass, relative to the total weight of the comonomer.

6. A preparation method of styrene-maleic anhydride copolymer is characterized by comprising the following steps:

the preparation method comprises the following steps: placing the mother liquor of any one of claims 1 to 5 in an inert gas atmosphere;

and (3) photo-initiated polymerization: irradiating the mother liquor by light under the protection of inert gas to perform light-initiated polymerization reaction to generate a styrene-maleic anhydride copolymer and obtain a milky suspension containing the styrene-maleic anhydride copolymer;

a separation step: and after the step of photo-initiated polymerization reaction is finished, separating the obtained styrene-maleic anhydride copolymer emulsion suspension to obtain styrene-maleic anhydride copolymer precipitate.

7. The preparation method according to claim 6, wherein in the photo-initiated polymerization step, the reaction temperature is controlled to be 20 to 40 ℃.

8. The production method according to claim 6, wherein the light irradiated in the photo-initiation polymerization step is LED light having a wavelength of 365nm to 405nm, an irradiation time of 10 minutes to 3 hours, and an irradiation intensity of 10 mW/cm to 1000 mW/cm.

9. The method of claim 6, further comprising the steps of:

and (3) raw material supplement step: supplementing a comonomer and a photoinitiator to the reaction liquid remaining after the separation of the styrene-maleic anhydride copolymer precipitate after the separation step;

after the raw material replenishing step, the photoinitiated polymerization step and the separation step are continued.

10. An apparatus for preparing styrene-maleic anhydride resin by photo-initiation polymerization is characterized by comprising a batching kettle, a photo-initiation polymerization kettle, a dissolution kettle, a devolatilization kettle and a receiving groove,

the batching kettle is used for preparing the mother solution as claimed in any one of claims 1 to 5, a discharge hole of the batching kettle is connected with a feed inlet of the photo-initiation polymerization kettle,

the photopolymerization kettle is used for generating photoinitiated polymerization reaction and is provided with a light source, a discharge hole of the photoinitiated polymerization kettle is connected with a feed inlet of the dissolution kettle,

the dissolution and desorption kettle is used for separating a product obtained after the reaction in the photo-initiation polymerization kettle into styrene-maleic anhydride copolymer precipitate and other materials, the dissolution and desorption kettle is provided with a precipitate discharge port and a solvent discharge port, the precipitate discharge port is connected with the devolatilization kettle, the solvent discharge port is connected with the receiving tank, the separated styrene-maleic anhydride copolymer precipitate enters the devolatilization kettle through the precipitate discharge port, and the other materials enter the receiving tank through the solvent discharge port;

the devolatilization kettle is used for removing residual solvent in the styrene-maleic anhydride copolymer precipitate, and is connected with the receiving tank.

11. The apparatus for photo-initiated polymerization preparation of styrene-maleic anhydride resin according to claim 10, wherein said photo-initiated polymerizer is provided therein with a quartz glass window for transmitting light irradiated from said light source.

12. The apparatus as claimed in claim 10, wherein the receiving tank is connected with the batching kettle, and a pump is arranged on a connecting path of the receiving tank and the batching kettle and is used for pumping the solvent in the receiving tank into the batching kettle.

Background

Photo-initiated polymerization refers to a polymerization reaction in which a photoinitiator generates active species (radicals or cations, etc.) to initiate a chain polymerization reaction of mono-or polyfunctional oligomers and/or reactive diluents under illumination (ultraviolet or visible light) to rapidly form a linear or highly crosslinked polymer network. The photo-initiated polymerization has the advantages of rapidness, high efficiency, simple and convenient operation, realization of time-space controllability and the like, is widely applied to the fields of coatings, adhesives, printing ink, biomedicine, 3D printing and the like, and has extremely high commercial value.

The styrene-maleic anhydride resin is a copolymer of maleic anhydride and styrene. The styrene-maleic anhydride and the ester derivative thereof are widely applied to the fields of polymer alloys, dispersing agents and the like. Styrene and maleic anhydride form complexes at low temperatures, alternating polymerization can take place under the action of thermal initiators, and random copolymerization can also take place at higher temperatures.

In the prior published reports, the preparation of styrene-maleic anhydride resins is carried out by solution polymerization or precipitation polymerization. In order to control the composition of the polymer, it is generally necessary to control the reaction temperature by means of, for example, dropwise addition, and to control the reaction time, the dropping rate, and the like in accordance with the half-lives and the like of the thermal initiator at different temperatures. The energy consumption is high due to the need of heating, and a precipitator or toxic toluene and the like are used as a solvent, which is unfavorable for environmental pollution, carbon emission and the like.

CN101580564A, CN102250273A and the like disclose methods of dissolving styrene monomer, maleic anhydride, thermal initiator organic peroxide or azo compound in a certain proportion in organic acid alkyl ester under nitrogen gas, and reacting at 60-90 ℃ to prepare alternating copolymers and random copolymers of styrene and maleic anhydride.

However, how to efficiently prepare styrene-maleic anhydride copolymer with low energy consumption is a technical problem which needs to be solved in the field.

Disclosure of Invention

The present inventors have conducted intensive studies in view of the disadvantages of the prior art and have found that a styrene-maleic anhydride copolymer prepared by photo-initiated polymerization using a comonomer and a photoinitiator as reaction raw materials by innovatively combining photo-initiated polymerization with a styrene-maleic anhydride copolymerization system can initiate polymerization by illumination without heating necessary for thermal initiation, and can use a mother liquor necessary for pre-prepared photo-initiated polymerization without long-time dropping necessary for thermal initiation polymerization, thereby saving the time necessary for reaction and improving the production efficiency. Thus, the present invention has been completed.

Specifically, the present invention provides the following technical solutions.

In one aspect, the present invention provides a mother liquor for preparing a styrene-maleic anhydride copolymer (styrene-maleic anhydride copolymer) by photo-initiated polymerization, comprising: the mass percent of the comonomer is 5-30 wt%, the mass percent of the photoinitiator is 0.2-4.0 wt%, the comonomer contains styrene and maleic anhydride, and the molar ratio of the styrene to the maleic anhydride is 1: 1-1.5: 1.

The mother liquor is a homogeneous solution, and can be prepared by mixing and stirring raw materials such as a comonomer, a photoinitiator, an organic solvent and the like, and the stirring may be mechanical stirring or magnetic stirring, and is not particularly limited. The added comonomer and photoinitiator are solvated in the organic solvent by stirring to form a homogeneous solution.

Preferably, the aforementioned photoinitiator is a photolytic initiator and/or a hydrogen abstraction photoinitiator.

More preferably, the photolytic initiator is at least one selected from the group consisting of α -hydroxyketone photoinitiators 1173, α -hydroxyketone photoinitiators 184, α -hydroxyketone photoinitiators 2959, photoinitiators 651, oxalate photoinitiators MBF, α -aminoketone photoinitiators 907, α -aminoketone photoinitiators 369, acylphosphine oxide photoinitiators TPO, and acylphosphine oxide photoinitiators 819 represented by the following structural formula;

the hydrogen abstraction photoinitiator is at least one selected from benzophenone photoinitiator BP, benzophenone photoinitiator EMK and thioxanthone photoinitiator ITX shown in the following structural formula, and at least one selected from MDEA and EDB as co-initiator.

Preferably, the organic solvent is at least one selected from the group consisting of butyl acetate, isobutyl acetate, sec-butyl acetate, amyl acetate, isoamyl acetate, benzyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, isoamyl butyrate, ethyl isovalerate, isoamyl isovalerate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, isoamyl benzoate, methyl phenylacetate and ethyl phenylacetate.

Preferably, the comonomer further comprises alpha-methylstyrene and vinyl acetate, and the weight percentage of the total weight of the comonomer is 40-50% of maleic anhydride, 10-20% of styrene, 10-20% of alpha-methylstyrene and 20-30% of vinyl acetate.

In another aspect, the present invention also relates to a method for preparing a styrene-maleic anhydride copolymer, which comprises the steps of:

the preparation method comprises the following steps: putting the mother solution for preparing the styrene-maleic anhydride copolymer by photoinitiated polymerization in an inert gas atmosphere;

and (3) photo-initiated polymerization: irradiating the mother liquor by light under the protection of inert gas to perform light-initiated polymerization reaction to generate styrene-maleic anhydride copolymer and obtain milky suspension containing the styrene-maleic anhydride copolymer;

a separation step: and (3) after the photo-initiated polymerization reaction step is finished, separating the obtained styrene-maleic anhydride copolymer emulsion suspension to obtain styrene-maleic anhydride copolymer precipitate.

In another aspect, the invention also relates to a device for preparing styrene-maleic anhydride resin by photoinitiation polymerization, which comprises a batching kettle, a photoinitiation polymerization kettle, a dissolution kettle, a devolatilization kettle and a receiving groove,

the material mixing kettle is used for preparing the mother solution for preparing the styrene-maleic anhydride copolymer by photoinitiation polymerization, a material outlet of the material mixing kettle is connected with a material inlet of the photoinitiation polymerization kettle,

the photopolymerization kettle is used for generating photoinitiated polymerization reaction and is provided with a light source, a discharge hole of the photoinitiated polymerization kettle is connected with a feed inlet of the dissolution kettle,

the dissolution and desorption kettle is used for separating the product after the photo-initiated polymerization reaction into styrene-maleic anhydride copolymer precipitate and other materials, the dissolution and desorption kettle is provided with a precipitate discharge port and a solvent discharge port, the precipitate discharge port is connected with the devolatilization kettle, the solvent discharge port is connected with the receiving tank, the separated styrene-maleic anhydride copolymer precipitate enters the devolatilization kettle through the precipitate discharge port, and the other materials enter the receiving tank through the solvent discharge port;

the devolatilization kettle is used for removing residual solvent in the styrene-maleic anhydride copolymer precipitate, and is connected with the receiving tank.

Preferably, the photo-initiated polymerization reactor is provided with a quartz glass window for transmitting light irradiated from a light source.

Preferably, the receiving tank is connected with the batching kettle, and a pump is arranged on a connecting path of the receiving tank and the batching kettle and used for pumping the solvent in the receiving tank into the batching kettle.

Preferably, the photo-initiation polymerization kettle is further provided with a cooling device for cooling the temperature of the reaction system in the photo-initiation polymerization kettle during photo-initiation polymerization, and the temperature of the reaction system is controlled to be 20-40 ℃, more preferably 25-30 ℃.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

FIG. 1 is a diagram of a styrene-maleic anhydride copolymer prepared in one example¹H NMR spectrum.

FIG. 2 is a schematic view of an apparatus for preparing a styrene-maleic anhydride copolymer by photo-initiated polymerization, according to an exemplary embodiment.

Fig. 3 is a schematic view of an apparatus for preparing a styrene-maleic anhydride copolymer by photo-initiated polymerization, shown in another exemplary embodiment.

Detailed Description

[ mother liquor for preparing styrene-maleic anhydride copolymer by photo-initiated polymerization ]

The mother liquor for preparing the styrene-maleic anhydride copolymer by photoinitiated polymerization contains: the mass percent of the comonomer, the photoinitiator and the organic solvent is 5-30 wt% in total relative to the total weight of the mother solution, the mass percent of the photoinitiator relative to the comonomer is 0.2-4.0 wt%,

the comonomer contains styrene and maleic anhydride, the maleic anhydride is also called maleic anhydride, and the molar ratio of the styrene to the maleic anhydride is 1: 1-1.5: 1.

The mother liquor for preparing the styrene-maleic anhydride copolymer by photo-initiated polymerization can initiate photopolymerization by light irradiation. The prepared mother solution is directly used for photo-initiated polymerization reaction, so that the preparation and production time can be saved. In addition, the components in the mother solution can be directly added and mixed, and the mother solution can be placed for a long time under the conditions of light protection and normal temperature.

The photoinitiator in the mother liquor is a photolysis type initiator and/or a hydrogen abstraction type photoinitiator.

Preferably, the photolytic initiator is at least one selected from the group consisting of an α -hydroxyketone photoinitiator 1173, an α -hydroxyketone photoinitiator 184, an α -hydroxyketone photoinitiator 2959, a photoinitiator 651, an oxalate photoinitiator MBF, an α -aminoketone photoinitiator 907, an α -aminoketone photoinitiator 369, an acylphosphine oxide photoinitiator TPO, and an acylphosphine oxide photoinitiator 819 represented by the following structural formula;

the hydrogen abstraction photoinitiator is at least one selected from benzophenone photoinitiator BP, benzophenone photoinitiator EMK and thioxanthone photoinitiator ITX shown in the following structural formula, and at least one selected from MDEA and EDB as co-initiator.

Examples of the organic solvent include at least one selected from the group consisting of butyl acetate, isobutyl acetate, sec-butyl acetate, amyl acetate, isoamyl acetate, benzyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, isoamyl butyrate, ethyl isovalerate, isoamyl isovalerate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, isoamyl benzoate, methyl phenylacetate and ethyl phenylacetate. Preferably isoamyl acetate or butyl acetate.

The term "styrene-maleic anhydride copolymer" used in the present invention means a copolymer obtained by photo-initiated copolymerization using styrene and maleic anhydride as comonomers, and the comonomers may be not limited to both styrene and maleic anhydride, and may be included as long as they are capable of photo-initiated polymerization together with styrene and maleic anhydride.

In certain embodiments, the comonomer may further comprise other monomers capable of together undergoing photoinitiated polymerization. For example, alpha-methylstyrene and vinyl acetate are contained as comonomers. In the case of containing α -methylstyrene and vinyl acetate, the maleic anhydride content is, for example, 40 to 50% by mass, the styrene content is 10 to 20% by mass, the α -methylstyrene content is 10 to 20% by mass, and the vinyl acetate content is 20 to 30% by mass, based on the total weight of the comonomers.

When the mother liquor for preparing the styrene-maleic anhydride copolymer by photoinitiated polymerization is used for photoinitiated polymerization, the reaction system needs to be replaced by an inert gas atmosphere, such as a nitrogen atmosphere.

[ method for producing styrene-maleic anhydride copolymer ],

the preparation method of the styrene-maleic anhydride copolymer comprises the following steps:

the preparation method comprises the following steps: putting the mother solution for preparing the styrene-maleic anhydride copolymer by photoinitiated polymerization in an inert gas atmosphere;

and (3) photo-initiated polymerization: irradiating the mother liquor by light under the protection of inert gas to perform light-initiated polymerization reaction to generate styrene-maleic anhydride copolymer and obtain milky suspension containing the styrene-maleic anhydride copolymer;

a separation step: and (3) after the photo-initiated polymerization reaction step is finished, separating the obtained styrene-maleic anhydride copolymer emulsion suspension to obtain styrene-maleic anhydride copolymer precipitate.

Thermally initiated polymerization, as used in the prior art, is a conventional method for preparing polymers by initiating polymerization of comonomers by thermal initiator decomposition by heating to generate free radicals. For the preparation of styrene-maleic anhydride copolymer, the thermal initiators usually used are mainly azobisisobutyronitrile, dibenzoyl peroxide and the like, the thermal decomposition temperature of the thermal initiators is 70-90 ℃, and the half-life period of the thermal decomposition of the two initiators is 5-12 hours in the temperature range. For example, azobisisobutyronitrile and dibenzoyl peroxide have half-lives of 5.08 hours and 13.25 hours, respectively, at 69 ℃. Therefore, when the styrene-maleic anhydride copolymer is prepared by thermal initiation polymerization, the whole polymerization system must be heated and maintained for a sufficient time to ensure the generation of sufficient free radicals and the yield of polymer preparation, and the energy consumption and time consumption in the reaction process are high, so that the reaction efficiency is difficult to improve. In addition, high temperature reaction has certain potential safety hazard and has the danger of implosion and kettle flushing.

The present inventors have innovatively conceived the introduction of photo-initiated polymerization into a preparation system of a styrene-maleic anhydride copolymer. For a preparation system of the styrene-maleic anhydride copolymer, the reaction time required by photopolymerization is greatly shortened compared with that of a thermal polymerization process, so that the reaction efficiency can be greatly improved. The photo-initiated polymerization is a reaction in which a photo-initiator molecule is photolyzed by light irradiation to generate a radical, thereby initiating polymerization of a monomer. The efficiency of photolysis is improved by many times compared with the efficiency of thermal decomposition, so that the energy consumption is greatly reduced, the cost can be saved, and the environment is protected.

The efficiency improvement and energy saving effects of photopolymerization over thermally initiated polymerization are illustrated below by taking photons emitted from a 365nm LED as an example.

Assuming that the quantum yield of photolysis is 0.5 (i.e. two photons can decompose one photoinitiator, in practice the efficiency may be higher), 2mol photons are required to decompose 1mol photoinitiator. The energy per photon is the product of the planck constant and the photon fluctuation frequency, so the energy E for 2mol photons is:

E＝2*NA*h*c/λ

where NA is the Avogastrol constant, h is Planck's production, c is the speed of light, and λ is the wavelength, here taken to be 365 nm.

Thus, E ═ 2 × 6.02 × 10²³×6.626×10^-34×3×10⁸/(365×10^-9)＝6.5×10⁵Joule 650 kilojoules. That is, only 650 kj of energy is required to decompose 2mol of photoinitiator. Assuming that the power of the light source is 1kW, all the photoinitiators can be photolyzed only by light for 650 seconds and less than 11 minutes, corresponding to the electric energy consumption of about 0.18 degrees, the photoelectric conversion efficiency of the LED light source is about 30% at 365nm and reaches more than 60% at 385nm, and therefore, the power consumption in the whole process is calculated to be less than 1 degree. In the actual polymerization process, thisThe process can be slowed down appropriately to control the progress of the reaction, for example by illumination for 30 minutes. The same effect can be achieved with a weaker light intensity, since the light excitation is only dependent on the wavelength of the photons and not on the light intensity.

In the same case, the molecular weight of azobisisobutyronitrile, for example, was 164.21, and 2mol was 328.4 g, based on 1% by weight of the thermal initiator based on the total monomer mass and 20% by weight of the total monomer based on the polymerization system, 32.8 kg of the monomer system and 164 kg of the total system were required. Calculated by the specific heat of isoamyl acetate of 1.92 KJ/(kg. K), the required energy for heating from room temperature of 20 ℃ to 70 ℃ is as follows:

e ═ c × m × Δ T ═ 1.92 × 164 × 50 ═ 15744 kilojoules. The energy is only the energy required by temperature rise, and the energy consumed by heat preservation for 5-12 hours is not included.

From the above analysis, it can be shown that by introducing photoinitiated polymerization in the preparation of styrene-maleic anhydride copolymer, both the reaction time and the energy required for the reaction are greatly reduced. Therefore, compared with the preparation method of the styrene-maleic anhydride copolymer by thermal initiation polymerization in the prior art, the preparation method of the styrene-maleic anhydride copolymer can greatly improve the reaction efficiency, is more environment-friendly and energy-saving, can greatly reduce the cost, and is more suitable for industrial application.

Hereinafter, each step will be described in detail.

[ preparation procedure ]

In the preparation step, the aforementioned mother liquor for preparing the styrene-maleic anhydride copolymer by photo-initiated polymerization is placed in an inert gas atmosphere. The term "in an inert gas atmosphere" as used herein means that an inert gas is introduced into the reaction system to replace the reaction system for a certain period of time, so that the system is in an inert gas atmosphere.

The inert gas atmosphere may be, for example, a helium gas atmosphere or a nitrogen gas atmosphere, and a nitrogen gas atmosphere is preferred from the viewpoint of cost saving.

[ photo-initiated polymerization step ]

In the photo-initiation polymerization step, under the protection of inert gas, the homogeneous solution obtained in the preparation step is irradiated with light to perform photo-initiation polymerization reaction, so that the styrene-maleic anhydride copolymer is generated.

In the aforementioned photo-initiated polymerization step, the polymerization reaction is initiated by irradiating light. By irradiating light to the reaction system, the photoinitiator in the system generates active species such as free radicals or cations after being irradiated by the light, the comonomer in the reaction system is initiated to generate chain polymerization, and the copolymer generated by the reaction is precipitated from the reaction system, belonging to precipitation polymerization, also called heterogeneous polymerization.

The principle of photoinitiated polymerization will be described below by taking α -hydroxyketone photoinitiator 1173, which uses a photolytic photoinitiator, as an example of the photoinitiator. The mother liquor obtained through the preparation step is irradiated with light using 365nm or 385nm LED as a light source. Wherein, the molecule of the alpha-hydroxy ketone photoinitiator 1173 as the photoinitiator is irradiated by light to generate homolytic reaction shown in the following reaction formula (1) to generate two high-activity free radicals, and further, the generated free radicals attack the double bond of the comonomer to initiate chain reaction to generate the styrene-maleic anhydride copolymer. The aforementioned chain reaction process is well known to those skilled in the art, and the description thereof is omitted here.

Reaction formula (1): mechanism for generating free radicals by homolytic cleavage reaction of photoinitiator 1173

In the case of using a hydrogen abstraction type photoinitiator, first, ITX as a main initiator, for example, obtains one proton from MDEA as a co-initiator by a hydrogen abstraction reaction under irradiation of light, and MDEA as a co-initiator forms a corresponding radical, and has a very high initiating activity to initiate polymerization of a monomer. Specifically, the reaction is represented by the following reaction formula (2).

Reaction formula (2): mechanism for generating free radicals under ITX (internal transcribed X) illumination of hydrogen abstraction type photoinitiator

The light source used in the aforementioned photo-initiated polymerization step is not particularly limited, and light in the ultraviolet or visible wavelength range may be used. Preferably, LED lamps are used.

The conditions of light irradiation, such as the area of the light source, the light intensity, and the light irradiation time, can be appropriately set depending on the scale of the system at the time of production, as long as the photoinitiator can be excited to cleave. Since the chain reaction proceeds spontaneously after the start, the light irradiation may be performed intermittently, not necessarily continuously.

The wavelength of the light source used may be, for example, 365nm to 405 nm. For example, light having a wavelength of 365nm, 385nm, 395nm, or 405nm may be used. More preferably, 365nm or 385nm light is used.

The light source may be a surface light source or a point light source, and is preferably a surface light source. The light irradiation time may be, for example, 10 minutes to 3 hours, and the light irradiation intensity may be, for example, 10 milliwatts per square centimeter to 1000 milliwatts per square centimeter.

The photo-initiated polymerization reaction is carried out in an inert gas atmosphere, preferably a nitrogen gas atmosphere.

As the polymerization reaction is exothermic, the exothermic heat of reaction is accumulated in the reaction system along with the reaction, so that the temperature of the system is increased continuously.

According to the scale of the reaction system, the temperature of the reaction system is preferably controlled to be 20 to 40 ℃, more preferably 25 to 30 ℃ in the photoinitiated polymerization step. By controlling the temperature of the reaction system to be in the range, the phenomenon that the complexation of the monomers is damaged due to the increase of the reaction temperature is avoided, and the structure and the performance of the prepared copolymer are further influenced; on the other hand, by controlling the temperature of the reaction system within the above range, the produced polymer precipitates after reaching a certain molecular weight, and the increase in the solubility of the produced copolymer due to the increase in the reaction temperature is avoided, so that the polymer is not easily precipitated from the reaction system. Further, by controlling the temperature of the reaction system in the above range, the broadening of the molecular weight distribution of the copolymer due to the large temperature fluctuation is avoided.

The temperature control of the reaction system may be performed by a low-temperature cycle such as a cycle of condensed water, and is not particularly limited.

In the photo-initiated polymerization step, the reaction may be carried out by irradiating with light while stirring in order to make the temperature of the reaction system uniform. The stirring may be mechanical stirring or magnetic stirring, and is not particularly limited. By stirring, the reaction solution blocked by the copolymer precipitate can be exposed to a place where light can be irradiated, and thus the unreacted monomer can be allowed to continue to react. The reaction system gradually changed to a white suspension system as the reaction proceeded, and after a certain amount of the copolymer was produced, the system hardly continued to absorb light and photopolymerization was completed.

The styrene-maleic anhydride copolymer is reacted to form a milky suspension containing the styrene-maleic anhydride copolymer by the aforementioned photo-initiated polymerization step.

[ separation step ]

After the photopolymerization step is finished, the styrene-maleic anhydride copolymer in the obtained milky suspension is separated to obtain the precipitate of the styrene-maleic anhydride copolymer.

The separation may be performed by a solid-liquid separation method such as precipitation, filtration, or centrifugation, which is conventionally used in the art, and centrifugation is preferably used. When centrifugal separation is adopted, the centrifugal rotation speed can be set to be 1000-3000 rad/min, and the centrifugal time can be 10-30 min.

Further, the preparation method of the present invention may further comprise the steps of:

and (3) raw material supplement step: after the separation step, the reaction liquid remaining after the separation of the styrene-maleic anhydride copolymer is supplemented with a comonomer and a photoinitiator. The amounts of the comonomer and the photoinitiator to be replenished were calculated from the concentrations of the monomer and the photoinitiator in the recovered remaining reaction solution measured by gas chromatography, and the amounts of the corresponding monomer and photoinitiator consumed in the reaction were calculated as the amounts of the monomer and the photoinitiator to be replenished.

After the raw material replenishing step, the photo-initiated polymerization step and the separation step are continued.

After the separation step, the reaction mixture is supplemented with the comonomer and the photoinitiator, whereby the photo-initiated polymerization reaction can be continued under the irradiation with light. The separation step may then be continued.

By recycling the aforementioned raw material replenishment step, photo-initiation step and separation step, the organic solvent can be reused many times, thereby avoiding the generation of a large amount of organic waste liquid during the reaction and also causing little solid waste.

In the photo-initiated polymerization, small amounts of oligomers having a relatively low molecular weight are also produced, and these oligomers are dissolved in an organic solvent such as isoamyl acetate, butyl acetate, etc. Therefore, after the aforementioned raw material replenishing step, photo-initiation step and separation step are repeatedly circulated a plurality of times, the concentrations of these oligomers increase to affect the photopolymerization of the comonomer, and in this case, the aforementioned circulation is ended. The number of cycles may be, for example, 2 to 10 cycles, preferably 2 to 5 cycles.

Further, the preparation method of the present invention may further include the steps of:

a devolatilization step: a step of removing volatile components from the styrene-maleic anhydride copolymer separated in the aforementioned separation step. The devolatilization step described above may be performed by, for example, drying, vacuum evacuation, or the like. Further, washing may be performed with an organic solvent, and the organic solvent may be, for example, butyl acetate or the like. The aforementioned washing may be performed one or more times.

The styrene-maleic anhydride copolymer prepared by the preparation method has good heat resistance, and can be used as a heat-resistant modifier applied to polymers, for example, as a heat-resistant modifier of polypropylene.

[ apparatus for preparing styrene-maleic anhydride resin by photo-initiated polymerization ]

The equipment for preparing the styrene-maleic anhydride resin by photoinitiated polymerization comprises a batching kettle, a photoinitiated polymerization kettle, a dissolving and removing kettle, a devolatilization kettle and a receiving groove.

The batching kettle is used for preparing the mother liquor for preparing the styrene-maleic anhydride copolymer by photoinitiation polymerization, and a discharge port of the batching kettle is connected with a feed port of the photoinitiation polymerization kettle.

The photoinitiated polymerizer is used for generating photoinitiated polymerization reaction and is provided with a light source, and a discharge hole of the photoinitiated polymerizer is connected with a feed hole of the dissolution kettle.

The dissolving and removing kettle is used for separating a product obtained after reaction in the photo-initiation polymerization kettle into styrene-maleic anhydride copolymer precipitate and other materials, the dissolving and removing kettle is provided with a precipitate discharge port and a solvent discharge port, the precipitate discharge port is connected with the devolatilization kettle, the solvent discharge port is connected with the receiving tank, the separated styrene-maleic anhydride copolymer precipitate enters the devolatilization kettle through the precipitate discharge port, and the other materials enter the receiving tank through the solvent discharge port.

The devolatilization kettle is used for removing residual solvent in the styrene-maleic anhydride copolymer precipitate and is connected with the receiving tank.

Fig. 2 shows an example of an apparatus for preparing a styrene-maleic anhydride resin by photo-initiated polymerization. As shown in figure 2, the equipment comprises a batching kettle 1, a photoinitiated polymerization kettle 2, a dissolution kettle 3 and a devolatilization kettle 4 which are connected in sequence. The bottom discharge port of the batching kettle 1 is connected with the top feed port of the polymeric kettle 2, the bottom discharge port of the polymeric kettle 2 is connected with the top feed port of the dissolution kettle 3, and the bottom discharge port of the dissolution kettle 3 is connected with the top feed port of the devolatilization kettle 4. In order to facilitate the uniform mixing of the materials, stirring devices are arranged in the batching kettle 1, the polymerization kettle 2, the dissolution and volatilization kettle 3 and the volatilization kettle 4. For the convenience of metering, a metering pump 14 can be arranged between the batching kettle 1 and the polymerization kettle 2, a metering pump 15 can be arranged between the polymerization kettle 2 and the dissolution kettle 3, and a metering pump 16 can be arranged between the dissolution kettle 3 and the devolatilization kettle 4.

When the styrene-maleic anhydride copolymer of the present invention is prepared by using the apparatus shown in FIG. 2, a proper amount of the mother liquor for photoinitiating the polymerized styrene-maleic anhydride copolymer of the present invention in the compounding vessel 1 may be introduced directly into the prepared mother liquor, or may be prepared by adding each component required for the mother liquor into the compounding vessel 1. Then, nitrogen gas was introduced while stirring, and the system in the compounding vessel 1 was replaced with a nitrogen atmosphere. Then, a predetermined amount of the mother liquor was introduced into the photo-initiation polymerization reactor 2 by the metering pump 14, and the reaction solution in the photo-initiation polymerization reactor 2 was irradiated with light under the protection of nitrogen gas while being stirred. The light source (not shown) for light irradiation may be provided in the photo-initiation polymerization reactor 2, or may be provided outside the photo-initiation polymerization reactor 2, and the reaction system is irradiated with light through the photo-initiation polymerization reactor 2 during light irradiation. In the case of irradiation from the outside of the photo-initiation polymerization reactor 2, the photo-initiation polymerization reactor 2 may be provided with a light-transmitting window (not shown) through which the irradiation light can be transmitted, the light-transmitting window being made of a material through which the irradiation light can be transmitted, such as quartz, or the photo-initiation polymerization reactor 2 itself being made of quartz. By the irradiation with light, the photoinitiator in the photo-initiation polymerization reactor 2 is reacted to initiate photopolymerization. After the reaction is finished, the reacted materials are introduced into a stripping kettle 3. The copolymer formed by the reaction is separated from the other components in the elution tank 3. The copolymer produced by the reaction can be directly discharged to the devolatilization vessel 4 from a precipitation discharge port provided below the devolatilization vessel 3 by utilizing the self-precipitation property of the copolymer produced by the reaction. Alternatively, a centrifuge (not shown) or other separation means such as a filter or the like may be provided in the elution tank 3 for separation. The separated copolymer is led out to a devolatilization kettle 4 from a precipitation discharge hole below the dissolution kettle 3. In addition, the remaining material after the copolymer is separated in the stripping tank 3 can be returned to the photo-initiated polymerization tank 2 as a raw material for the next photo-initiated polymerization reaction. In devolatilization vessel 4, the volatile components in the separated copolymer are discharged from the upper part by heating, and the discharged volatile components are condensed by cooling and then enter receiving vessel 11.

In some embodiments, as shown in fig. 3, on the basis of the apparatus shown in fig. 2, the receiving tank 11 is further connected to the batching kettle 1, and a solvent pump 13 is disposed between the receiving tank 11 and the batching kettle 1, and the solvent received in the receiving tank 11 is pumped into the batching kettle 1 by the solvent pump 13 as a raw material for preparing a mother liquor for next photo-initiated polymerization.

In some embodiments, the photo-initiation polymerization reactor 2 is further provided with a cooling device (not shown), and the temperature of the reaction system of the photo-initiation polymerization reactor 2 is controlled to be 20 to 40 ℃, more preferably 25 to 30 ℃ by the cooling device.

Examples

Example 1

104 parts by mass of styrene, 98 parts by mass of maleic anhydride (maleic anhydride) and 2 parts by mass of photoinitiator 184 are added into 800 parts by mass of butyl acetate, and the mixture is stirred and mixed uniformly to form a homogeneous solution, so that a mother solution A for preparing the styrene-maleic anhydride copolymer by photo-initiation polymerization is obtained.

Example 2

156 parts by mass of styrene, 98 parts by mass of maleic anhydride and 2 parts by mass of photoinitiator 184 are added to 1000 parts by mass of isoamyl acetate, and the mixture is stirred and mixed uniformly to form a homogeneous solution, so that a mother liquor B for preparing the styrene-maleic anhydride copolymer by photoinitiation polymerization is obtained.

Example 3

1000g of the mother liquor A obtained in example 1 was charged into a compounding tank 1 of an apparatus shown in FIG. 2, and after replacing the atmosphere with nitrogen, the mother liquor A was introduced into a photo-initiation polymerization tank 2 by a pump 14, and the photo-initiation polymerization tank 2 was made of quartz. After blowing nitrogen for 15 minutes, an LED area light source with the central wavelength of 385nm is close to the photo-initiated polymerization kettle 2 to directly irradiate the solution in the kettle, and the light intensity is about 50mW/cm²Stirring was carried out while carrying out light irradiation under a nitrogen atmosphere for 15 minutes, during which the temperature of the polymerization system was raised to 50 ℃ at the maximum, then the material of the whole reaction system was introduced into a dissolution-volatilization vessel, the copolymer precipitate obtained by separation with a centrifuge was washed once with fresh butyl acetate, the copolymer precipitate after centrifugation and washing was introduced into a devolatilization vessel through a pump 16, and the copolymer precipitate was dried by heating in the devolatilization vessel to obtain 124g of a white solid powder. The concentration of the photoinitiator in the mixture of the centrifugate and the washing solution was calibrated by gas chromatography, and the residual amount of the initiator 184 was found to be 23%. By using¹The resulting polymer was characterized by H NMR and is shown in FIG. 1. By calculating the integrated area of the benzene ring hydrogen in the region of 6 to 8ppm and the integrated area of the main chain hydrogen in the region of 1 to 4ppm, it can be obtained that the molar ratio of styrene to maleic anhydride in the polymer is about 1:1, the ratio is consistent with the batch charging ratio.

Example 4

The preparation was carried out using the apparatus shown in FIG. 3.

First, the preparation was carried out in the same manner as in example 3, and after completion of the preparation, 650 g of the centrifugate and the washing solution centrifuged and washed in the elution tank 3 in the preceding preparation were introduced into a receiving tank, and then, were added to the compounding tank 1, 64 g of styrene, 60g of maleic anhydride (maleic anhydride), 1.5 g of photoinitiator 184, and 226 g of butyl acetate were added to the compounding tank 1, and the mixture was stirred and dissolved, and after 15 minutes of blowing nitrogen gas, the mixture was introduced into the photo-initiation polymerization tank 2, and in the photo-initiation polymerization tank 2, an LED surface light source having a center wavelength of 385nm was brought close to the surface of the quartz flask, and the solution in the flask was directly irradiated with light having an intensity of about 50mW/cm²While stirring was continued under irradiation with light under a nitrogen atmosphere for 15 minutes, the temperature of the polymerization system was raised to 50 ℃ at the maximum. The precipitate obtained was separated by a centrifuge, washed once with fresh butyl acetate, and the centrifuged and washed copolymer precipitate was introduced into a devolatilization vessel via a pump 16, and the copolymer precipitate was heated and dried in the devolatilization vessel to obtain 120 g of a white solid powder. Calibrating the concentration of photoinitiator in the mixture of centrifugate and washing liquid by gas chromatography to obtain 25% of initiator 184¹H NMR characterization of the resulting polymer gave a molar ratio of styrene to maleic anhydride of about 1:1, consistent with the charge ratio, by calculating the integrated area of benzene ring hydrogens in the 6-8ppm region and the integrated area of backbone hydrogens in the 1-4ppm region.

Example 5

1004g of the mother liquor A obtained in example 1 was charged into a compounding tank 1 of an apparatus shown in FIG. 2, replaced with a nitrogen atmosphere, and then introduced into a photo-initiation polymerization tank 2 through a pump 14, the photo-initiation polymerization tank 2 being made of quartz and placed in an ice-water bath at a temperature of 0 to 10 ℃. Blowing nitrogen into the photo-initiation polymerization kettle 2 for 15 minutes, then enabling an LED surface light source with the central wavelength of 385nm to be close to the photo-initiation polymerization kettle 2, and directly irradiating the solution in the kettle to obtain the light intensity of about 50mW/cm²Stirring while irradiating under nitrogen atmosphere for 15 min, raising the temperature of the polymerization system to 26 deg.C, introducing the materials into a stripping kettle, and centrifuging to obtain the final productThe resulting copolymer precipitate was washed once with fresh butyl acetate, and the centrifuged and washed copolymer precipitate was introduced into a devolatilization vessel via a pump 16, and the copolymer precipitate was dried by heating in the devolatilization vessel to obtain 134g of a white solid powder. The concentration of the photoinitiator in the mixture of the centrifugate and the washing solution was calibrated by gas chromatography, and the residual amount of the initiator 184 was found to be 22%. By using¹H NMR characterization of the resulting polymer gave a molar ratio of styrene to maleic anhydride of about 1:1, consistent with the charge ratio, by calculating the integrated area of benzene ring hydrogens in the 6-8ppm region and the integrated area of backbone hydrogens in the 1-4ppm region.

Example 6

1000g of the mother liquor B obtained in example 2 was charged into a compounding kettle 1 of the apparatus shown in FIG. 2, replaced with a nitrogen atmosphere, and then introduced into a photo-initiation polymerization kettle 2 through a pump 14, the photo-initiation polymerization kettle 2 being made of quartz and placed in an ice water bath at a temperature of 0 to 10 ℃. Blowing nitrogen into the photo-initiation polymerization kettle 2 for 15 minutes, then enabling an LED surface light source with the central wavelength of 385nm to be close to the photo-initiation polymerization kettle 2, and directly irradiating the solution in the kettle to obtain the light intensity of about 50mW/cm²Stirring was carried out while carrying out light irradiation under a nitrogen atmosphere for 15 minutes, during which the temperature of the polymerization system was raised to 28 ℃ at the maximum, then the material of the whole reaction system was introduced into a dissolution-volatilization vessel, the copolymer precipitate obtained by separation with a centrifuge was washed once with fresh butyl acetate, the copolymer precipitate after centrifugation and washing was introduced into a devolatilization vessel through a pump 16, and the copolymer precipitate was dried by heating in the devolatilization vessel to obtain 147g of a white solid powder. The concentration of the photoinitiator in the mixture of the centrifugate and the washing solution was calibrated by gas chromatography, and the residual amount of the initiator 184 was found to be 20%. By using¹H NMR characterizes the resulting polymer and by calculating the integrated area of benzene ring hydrogens in the 6 to 8ppm region and the integrated area of backbone hydrogens in the 1 to 4ppm region, a molar ratio of styrene to maleic anhydride in the polymer of about 1.4: 1, slightly lower than the batch.

Example 7

On the basis of the foregoing examples, the styrene-maleic anhydride copolymer precipitate described below was prepared by changing the kind and content of the initiator, the ratio of the monomer to the total system in the mother liquor, and the center wavelength and the light intensity of the light source. Specific formulations and operating details and yields are shown in table 1.

TABLE 1 Polymer yields for various formulations and light source information and related examples

A: butyl acetate; b: isoamyl acetate; c propyl propionate; d: butyl propionate; e: butyric acid ethyl ester

Example 8 (preparation of mother liquor C)

Adding 20.8 parts by mass of styrene, 98 parts by mass of maleic anhydride, 23.6 parts by mass of alpha-methylstyrene, 51.6 parts by mass of vinyl acetate and 2 parts by mass of photoinitiator 907 into 800 parts by mass of isoamyl acetate, and uniformly stirring and mixing to form a homogeneous solution, thereby obtaining a mother liquor C for preparing the styrene-maleic anhydride copolymer by photoinitiation polymerization.

Example 9

1000g of the mother liquor C obtained in example 8 was charged into the compounding tank 1 of the apparatus shown in FIG. 2, replaced with a nitrogen atmosphere, and then introduced into the photo-initiation polymerization tank 2 by the pump 14, and the photo-initiation polymerization tank 2 was made of stainless steel and provided with a light irradiation window made of quartz. After blowing nitrogen into the photo-initiation polymerization reactor 2 for 15 minutes, irradiating the reaction system in the photo-initiation polymerization reactor 2 through an LED surface light source with the central wavelength of 385nm through a light irradiation window with the light intensity of about 50mW/cm²Stirring while irradiating under nitrogen atmosphere for 15 min, raising the temperature of the polymerization system to 39 deg.C, introducing the material into a stripping kettle, centrifuging to obtain copolymer precipitate, washing with new isoamyl acetate, centrifuging, washing, and introducing the copolymer precipitate via pump 16 to stripping kettleIn the devolatilization vessel, the copolymer precipitate was dried by heating in the devolatilization vessel to obtain 153g of a white solid powder. The concentration of the photoinitiator in the mixture of the centrifugate and the washing solution was calibrated by gas chromatography, and the residual amount of the initiator 907 was found to be 22%. By using¹H NMR characterization of the obtained polymer shows that by calculating the integral area of benzene ring hydrogen in the region of 6-8ppm and the integral area of main chain hydrogen in the region of 1-4ppm, the mole ratio of styrene, maleic anhydride, alpha-methylstyrene and vinyl acetate in the polymer can be obtained to be consistent with the charge ratio by combining the characteristic absorption of methyl in alpha-methylstyrene and the characteristic absorption of methyl in vinyl acetate.

Example 10

The same procedure as in example 9 was repeated, except that the photo-initiation polymerization reactor 2 was placed in an ice-water bath controlled to a temperature of 0 to 10 ℃. The temperature of the polymerization system during the photo-initiated polymerization was raised to 28 ℃ at the maximum, and the copolymer was precipitated and then dried by heating to obtain 160g of a white solid powder. The concentration of the photoinitiator in the mixture of the centrifugate and the washing solution was calibrated by gas chromatography, and the residual amount of the initiator 907 was found to be 23%. By using¹H NMR characterization of the obtained polymer shows that by calculating the integral area of benzene ring hydrogen in the region of 6-8ppm and the integral area of main chain hydrogen in the region of 1-4ppm, the mole ratio of styrene, maleic anhydride, alpha-methylstyrene and vinyl acetate in the polymer can be obtained to be consistent with the charge ratio by combining the characteristic absorption of methyl in alpha-methylstyrene and the characteristic absorption of methyl in vinyl acetate.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.