阅读说明：本技术 一种杜仲胶与马来酸酐的熔融接枝方法 (Melt grafting method of gutta-percha and maleic anhydride ) 是由 师煜 杨浩 武彦杰 李红莲 冀超 宋洪港 渠慧鹏 魏文武 吴迪 杨洪钧 朱万权 于 2021-02-06 设计创作，主要内容包括：本发明公开了一种杜仲胶与马来酸酐的熔融接枝方法。通过选择合适的原材料配方、工艺设备和工艺参数进行杜仲胶接枝马来酸酐的制备,其中配方原材料质量比m(杜仲胶):m(马来酸酐):m(引发剂)＝4:1:0.15,采用密炼机作为反应载体,在温度为170℃,转子转速为50r/min的条件下杜仲胶单独密炼时间5min、接枝反应时间5min,得到初产物,再经过后续纯化即得到纯化产物。本发明所采用的熔融接枝法,具有技术可靠、反应时间短、可连续操作、成本低廉以及不会产生对环境有害的化学废液等独特优势,十分有利于杜仲胶接枝马来酸酐的工业化生产。(The invention discloses a melt grafting method of gutta-percha and maleic anhydride. The preparation method comprises the steps of selecting a proper raw material formula, proper process equipment and proper process parameters to prepare the eucommia ulmoides gum grafted maleic anhydride, wherein the mass ratio of the raw materials in the formula m (eucommia ulmoides gum) to m (maleic anhydride) to m (initiator) is 4:1:0.15, an internal mixer is adopted as a reaction carrier, the eucommia ulmoides gum is subjected to independent internal mixing for 5min and grafting reaction for 5min under the conditions that the temperature is 170 ℃ and the rotating speed of a rotor is 50r/min, so as to obtain a primary product, and then the primary product is subjected to subsequent purification, so as to obtain a purified product. The melt grafting method adopted by the invention has the unique advantages of reliable technology, short reaction time, continuous operation, low cost, no generation of chemical waste liquid harmful to the environment and the like, and is very favorable for the industrial production of the eucommia ulmoides gum grafted maleic anhydride.)

1. A method for melt grafting gutta-percha and maleic anhydride is characterized by comprising the following steps:

(1) putting the gutta-percha into an internal mixer for internal mixing for 5 min;

(2) adding maleic anhydride and an initiator into the eucommia ulmoides gum subjected to banburying in the step (1), and continuing to banbury for 5min to obtain a primary product;

(3) taking out the primary product, placing the primary product in a container, adding dimethylbenzene into the container, and stirring and reacting for 2-3h at a constant temperature of 100 ℃;

(4) placing the initial product treated in the step (3) in an acetone solution, uniformly dispersing, and performing suction filtration to obtain a solid;

(5) and (5) placing the solid obtained in the step (4) in a vacuum drying box for drying at normal temperature to obtain the maleic anhydride grafted gutta-percha.

2. The method for melt grafting of gutta-percha and maleic anhydride as claimed in claim 1, wherein the mass ratio of the gutta-percha, the maleic anhydride and the initiator is 4:1: 0.15.

3. The method for melt grafting gutta percha and maleic anhydride as claimed in claim 1 or 2, wherein said initiator is azobisisobutyronitrile.

4. The method for melt grafting of gutta percha and maleic anhydride as claimed in claim 1, wherein the banburying temperature of said banbury mixer in the step (1) and the step (2) is 170 ℃ and the rotation speed of the rotor is 50 r/min.

5. The method for melt grafting gutta-percha and maleic anhydride as claimed in claim 1, wherein the mass volume ratio of the primary product to xylene in the step (3) is 2 g/mL.

6. The method for melt grafting gutta percha and maleic anhydride as claimed in claim 1, wherein the suction filtration operation in the step (4) is performed 3 times or more.

Technical Field

The invention relates to the technical field of traffic, in particular to the field of rubber asphalt modification, and more particularly relates to a melt grafting method of gutta-percha and maleic anhydride.

Background

The eucommia ulmoides tree is a special economic tree species in China, the pericarp, the bark and the leaves of the eucommia ulmoides tree all contain abundant gutta-percha, the gutta-percha is mainly produced in China and is a high-quality natural rubber resource. The gutta-percha has a unique double bond structure, the double bond of the gutta-percha can participate in the grafting reaction, the grafted gutta-percha can greatly improve the performances of different types of asphalt, particularly the storage stability and the construction workability of the rubber asphalt can be obviously improved, and the gutta-percha is an asphalt modifier with superior performance.

The grafting reaction is the copolymerization reaction of grafting a branched chain consisting of another monomer or several monomers on the main chain of a polymer consisting of one or several monomers through a certain path. The polymer can obtain new superior performance after graft modification, and particularly the compatibility with other polar materials is obviously improved, so that the graft polymer can be used as a compatilizer, an adhesive and the like, and the application field of the existing polymer can be greatly widened by the graft polymerization technology. The traditional preparation method of gutta-percha grafted maleic anhydride is a solution grafting method, the solution grafting method needs a large amount of chemical solvent, the grafting process is complicated in steps, meanwhile, the harmless treatment of the solvent needs to consume a large amount of manpower, material resources and financial resources, and environmental pollution can be caused when the solvent is treated improperly, so that the production cost for preparing the gutta-percha grafted maleic anhydride by adopting the solution grafting method is too high and does not accord with the environmental protection concept.

Therefore, the technical personnel in the field need to solve the problem of how to provide a method for modifying eucommia ulmoides gum graft, which has simple preparation process, low cost and no pollution.

Disclosure of Invention

In view of the above, the invention provides a melt grafting method of gutta-percha and maleic anhydride, compared with the solution grafting method, the melt grafting method can not only omit the steps of product separation, solvent treatment and the like in the grafting process, but also has the grafting efficiency far higher than that of the solution grafting method, so that the melt grafting method has the advantages of low production cost, high production efficiency, almost no pollution to the environment and the like, and can realize the industrial production of gutta-percha grafted maleic anhydride.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for melt grafting gutta-percha and maleic anhydride comprises the following steps:

(1) putting the gutta-percha into an internal mixer for internal mixing for 5 min;

(2) adding maleic anhydride and an initiator into the eucommia ulmoides gum subjected to banburying in the step (1), and continuing to banbury for 5min to obtain a primary product;

(3) taking out the primary product, placing the primary product in a container, adding dimethylbenzene into the container, and stirring and reacting for 2-3h at a constant temperature of 100 ℃;

(4) placing the initial product treated in the step (3) in an acetone solution, uniformly dispersing, and performing suction filtration to obtain a solid;

(5) and (5) placing the solid obtained in the step (4) in a vacuum drying box for drying at normal temperature to obtain the maleic anhydride grafted gutta-percha.

Preferably, the mass ratio of the gutta-percha to the maleic anhydride to the initiator is 4:1: 0.15.

Preferably, the initiator is azobisisobutyronitrile.

Preferably, the banburying temperature of the banbury mixer in the step (1) and the step (2) is 170 ℃, and the rotating speed of a rotor is 50r/min

Preferably, the mass-to-volume ratio of the primary product to the xylene in step (3) is 2 g/mL.

Preferably, the suction filtration operation in the step (4) is performed for 3 times or more, the acetone is used for washing and suction filtration of the product, and the washing and suction filtration is repeated for 3 times, so that the maleic anhydride, the initiator and other by-products which are not grafted can be sufficiently removed, and the purity of the reaction product is ensured.

The principle of the technical scheme is as follows: the molecular structure of the gutta-percha is trans-polyisoprene, the molecular structure of the common natural rubber (hevea rubber) is cis-polyisoprene, the gutta-percha and the polyisoprene are isomers, although the chemical compositions are the same, the properties of the gutta-percha and the natural rubber are different greatly due to the structural difference, the natural rubber has excellent elastic performance, and the gutta-percha is the characteristic of hard plastics, which is caused by the trans-order of the molecular chain of the gutta-percha. The gutta-percha has double bonds on molecular chains, the orderliness can be changed in a mode of grafting small molecules on the double bonds, so that the crystallization in the gutta-percha is damaged, the elastic property of the gutta-percha is recovered partially, and the grafted small molecules can enable the gutta-percha to obtain new performance, so that the application range of the gutta-percha is greatly widened. In order to effectively graft the gutta percha with the maleic anhydride, a proper raw material formula, process equipment and process parameters should be selected. In order to form a tight connection network between the gutta percha and the asphalt, small molecules which are easy to react with chemical groups in the asphalt are selected as grafting monomers. Maleic Anhydride (MAH) is known as maleic anhydride and has a molecular formula of C₄H₂O₃The molecular structure of the graft monomer has unsaturated double bonds which are easy to react with active groups, so the invention selects maleic anhydride as the graft monomer. The initiator is a substance capable of decomposing under the action of light, heat, radiation and the like to generate a primary free radical to initiate monomer polymerization, and the molecular formula of the Azobisisobutyronitrile (AIBN) is C₈H₁₂N₄The azodiisobutyronitrile is white crystal powder at normal temperature, has stable property, and has a first-order decomposition process without induced decomposition, so that the azodiisobutyronitrile is used as an initiator.

An internal mixer is a machine provided with a pair of rotors of a specific shape and rotating relative to each other, which kneads and kneads polymer materials intermittently in a closed state with adjustable temperature and pressure. Under the high-temperature action of the internal mixer, strong grafting reaction can be rapidly carried out between the gutta-percha and the maleic anhydride, and the mechanical shearing action of the rotor of the internal mixer can ensure that the gutta-percha and the maleic anhydride are fully contacted, so that the grafting reaction degree is deeper, and therefore, the internal mixer is selected as equipment for the grafting process.

The grafting process of gutta-percha and maleic anhydride follows a free radical reaction mechanism, and can be divided into two types according to the difference of the positions of maleic anhydride grafted on gutta-percha: one is grafted onto the double bond and the other is grafted onto the allylic position.

The principle of grafting maleic anhydride on double bonds of gutta percha is as follows:

in the high-temperature environment of the internal mixer, the initiator can be decomposed to generate primary free radicals, the free radicals attack the double bonds of the gutta percha molecules to open the gutta percha molecules and form new free radicals, and the new free radicals attack the double bonds of the maleic anhydride molecules to graft the maleic anhydride molecules on the double bonds of the gutta percha.

The principle of grafting maleic anhydride on the allyl position of gutta percha is as follows:

the principle of allylic grafting is similar to that of double bond grafting, with the main difference being the position of grafting of the maleic anhydride molecule. During the reaction, firstly, the initiator is decomposed to generate a primary free radical, then the free radical takes off the hydrogen at the allyl position to form a chain free radical, and finally, the chain free radical can be directly connected with a maleic anhydride molecule and can also be subjected to a connection reaction with another chain free radical.

According to the technical scheme, compared with the prior art, the invention discloses that the maleic anhydride is grafted on the gutta percha through melt grafting, and the melt grafting method has the unique advantages of reliable technology, short reaction time, continuous operation, low cost, no generation of chemical waste liquid harmful to the environment and the like, and is very favorable for the industrial production of the gutta percha grafted maleic anhydride.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic diagram of the double bond grafting of maleic anhydride to gutta percha according to the present invention;

FIG. 2 is a schematic diagram of the graft of maleic anhydride to an allyl group of eucommia ulmoides gum according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

(1) Weighing 20g of gutta-percha, and putting the gutta-percha into an internal mixer with the reaction temperature of 170 ℃ and the rotor speed of 50r/min for internal mixing for 5 min;

(2) uniformly mixing 5g of maleic anhydride and 0.75g of azobisisobutyronitrile, adding into an internal mixer, continuously reacting at the temperature and the rotor speed, and continuously reacting with gutta percha for 5min to obtain a primary product;

(3) 2g of the primary product is put into a 250 ml flask with a stirring paddle, 50ml of dimethylbenzene is added, and the mixture is stirred for 2.5 hours at a constant temperature of 100 ℃;

(4) dispersing the reacted substances into acetone, washing and filtering, and repeatedly carrying out 3 times to obtain a solid so as to remove maleic anhydride, an initiator and other byproducts which are not grafted;

(5) and (3) putting the washed and filtered solid into a vacuum oven for drying at normal temperature to obtain the purified eucommia ulmoides gum grafted maleic anhydride.

Comparative example 1

Preparing gutta-percha grafted maleic anhydride by a solvent grafting method:

adding 20g of gutta-percha into an internal mixer with the temperature of 170 ℃ and the rotor speed of 50r/min for curing for 1h, then adding the cured gutta-percha into 50ml of dimethylbenzene, heating to 120 ℃, stirring and dissolving, cooling to the reaction temperature after complete dissolution, adding maleic anhydride according to the formula, stirring and dissolving, introducing nitrogen for 5min, then dissolving an initiator into 10ml of dimethylbenzene, slowly dripping into the solution, and controlling the temperature to react for 60 min;

and after the reaction is finished, adding absolute ethyl alcohol to completely precipitate the product, filtering, washing the precipitate with the absolute ethyl alcohol for three times, removing unreacted maleic anhydride for two hours each time, performing suction filtration on the washed sample, and drying the washed sample in a vacuum oven at normal temperature to obtain the eucommia ulmoides gum grafted maleic anhydride.

Comparing the preparation method of example 1 with the preparation method of comparative example 1, the specific results are as follows:

comparison of the two methods	Solvent grafting method (comparative example 1)	Melt grafting method (example 1)
			Length of finished product preparation	12-16h	6-8h
Whether the finished product is stable	Whether or not	Is that
			Whether it can be operated continuously or not	Is that	Is that
Loss of finished product	Is higher than	Is lower than
			Unit integrated cost	Is higher than	In general
Whether to generate chemical waste	Is that	Whether or not

After the grafted gutta-percha is prepared by two different processes, the prepared grafted gutta-percha and 30-mesh common rubber powder are subjected to a blending reaction with common matrix asphalt to prepare modified rubber asphalt, and then an asphalt performance comparison test is performed, wherein test results are shown in the following table.

Tests show that in the three tests, the test results of the solvent grafting method and the melt grafting method both meet the technical requirements, but in the asphalt rotational viscosity test, the rotational viscosity of the solvent grafting method is larger and is basically close to the upper limit. The viscosity of the asphalt is too high, so that the construction workability of the asphalt mixture is greatly reduced, and the rolling effect is influenced.

The comprehensive test results show that all properties of the grafted gutta-percha powder modified asphalt prepared by the melt grafting method meet the technical requirements, and the comprehensive properties are superior, which proves that the grafted gutta-percha plays an effective modifying role on the rubber powder, and also proves that the melt grafting method preparation process is effective and has advantages.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.