A hydrogenated conjugated diene-arylvinyl random copolymer, a method of preparing the same, and use in a flexible clamp for phase change material

Abstract

The application discloses a hydrogenated conjugated diene-aryl ethylene random copolymer, a preparation method thereof and application thereof in a phase change material flexible clamp. The hydrogenated conjugated diene-aryl ethylene random copolymer is obtained by selectively hydrogenating an aryl ethylene-conjugated diene random copolymer; the hydrogenated conjugated diene-aryl ethylene random copolymer is melt compounded with oil and / or solid organic matter, has high hardness, an elastic modulus and good high-frequency impact resistance, moderate melting temperature, low viscosity in a molten state, easy flow, high use temperature, no adhesion and winding of a tool in a solid state, easy removal from a workpiece, is friendly to people and the environment, can be repeatedly used, and can be used as a main component of a phase change material flexible clamp in a weak-rigidity machine part machining process.

Description

Technical Field

[0001] This invention relates to a hydrogenated conjugated diene-arylethylene random copolymer, particularly to a hydrogenated conjugated diene-arylethylene random copolymer with high flowability, high elastic modulus, good impact resistance, high operating temperature and suitable hardness. It also relates to its preparation method and its application in the preparation of flexible clamps for phase change materials, belonging to the field of lithium polymer materials technology. Background Technology

[0002] With industrial development, various thin-walled parts and large-sized weakly rigid machine parts are increasingly used in aerospace, automotive and other fields. At the same time, they also face the problem of how to process them. In the process of machining weakly rigid machine parts, due to the relatively low rigidity of the workpiece and poor machinability, the milling process is prone to problems such as tool deflection, deformation and vibration under the influence of various factors such as cutting force, cutting vibration and cutting heat. The machining quality is difficult to control, and in severe cases, it can lead to the scrapping of the workpiece. This situation is particularly prominent in the aerospace industry.

[0003] In industrial applications, methods such as repeated finishing or deformation pre-compensation are often used to address the machining problems of weakly rigid machine parts. However, these methods do not change the inherent low stiffness of the parts and result in low machining efficiency. In this context, phase change material flexible fixtures offer unique advantages as a novel solution.

[0004] Machine tools are the basic tools for metal processing, and machine tool fixtures are the basic components of metal processing equipment. They serve as the interface between workpieces and machine tools, cutting tools, robots, and other equipment, and their flexibility has a crucial impact on modern manufacturing technology.

[0005] Flexibility generally refers to variability or adaptability. The flexibility of a fixture refers to its ability to adapt to parts of different shapes and sizes. Flexible fixtures are a large family, including combination fixtures, programmable fixtures, general-purpose flexible fixtures, phase change material flexible fixtures, and other fixtures. Among them, phase change material flexible fixtures are simply called phase change material fixtures, which are further divided into two main categories: true phase change material fixtures and pseudo phase change material fixtures.

[0006] Clamps based on phase change materials possess unique characteristics, including a large clamping area and uniform clamping force. They are particularly suitable for clamping workpieces with low stiffness and complex shapes. The workpiece is positioned within the liquid phase change material, and then external stimuli (such as changes in temperature, magnetic field, or current) are used to rapidly transform the phase change material into a solid state, achieving uniform clamping of the workpiece. After machining, the phase change material is quickly transformed back from a solid to a liquid state, allowing for easy removal of the workpiece.

[0007] There are many phase change materials that can be used in machine tool fixtures. Different types of fixtures can be obtained by using different phase change materials. They generally include the following categories: water-ice, wax-based materials, low-melting-point alloys (such as lead-tin-bismuth alloys), magnetorheological materials, and electrorheological materials. Each of these phase change materials has its own application characteristics and limitations.

[0008] From the perspective of the requirements for the use of phase change material fixtures, phase change material fixtures need to have the following characteristics: they can undergo solid-liquid phase change under certain conditions, have good fluidity in the liquid phase, have high hardness and high elastic modulus in the solid phase, do not break under high frequency impact, do not adhere to or wrap around the machining tool, are easy to remove from the workpiece, can be reused, are friendly to humans and the environment, and have no odor.

[0009] p-Methylstyrene, formally known as 4-methylstyrene (PMS), is a homologue of styrene and shares similar chemical properties. Polymethylstyrene (PPMS) can be obtained through various catalytic systems. Compared to polystyrene, its most significant advantage is its superior thermal properties. Highly crystalline PPMS exhibits higher glass transition temperature, Vicat softening point, and heat distortion temperature. Heat-resistant PPMS has a glass transition temperature of 113℃, 11% higher than polystyrene, a Vicat softening point 6% higher, and a heat distortion temperature 7% higher. Its hardness is also higher than polystyrene, while its mechanical properties are slightly lower or essentially equivalent.

[0010] Alpha-methylstyrene is a colorless liquid with a pungent odor. It polymerizes upon heating and is flammable. It can be used in the production of coatings and plasticizers, and is also used as a solvent in organic synthesis. 4-tert-butylstyrene (4-tert-butyl-4-ethenylbenzene) is also a derivative of styrene. Like α-methylstyrene and 4-tert-butylstyrene, the polymers of α-methylstyrene and 4-tert-butylstyrene exhibit better thermal properties than polystyrene. Also like 4-methylstyrene, when copolymerized with other monomers, the copolymers exhibit the same characteristics as the monomers, similar to styrene copolymers. Internationally, industrial-grade methylstyrene has been available since the 1980s, and in recent years, a few manufacturers in my country have begun producing industrial-grade polymers. For example, the butadiene-4-methylstyrene random copolymer obtained using an anionic catalytic system has a structure similar to solution-polymerized styrene-butadiene rubber. Its physical structure, properties, processing properties, and product performance are similar to solution-polymerized styrene-butadiene rubber (SBR). In some aspects, such as abrasion resistance and heat resistance, it is even better than SBR and can be used as a substitute for SBR.

[0011] In lithium-based anion catalytic systems, p-methylstyrene can replace styrene to synthesize random copolymers of butadiene and p-methylstyrene. The resulting butadiene-p-methylstyrene random copolymer has a higher melting point than the butadiene-styrene block copolymer, i.e., solution-polymerized styrene-butadiene rubber. Butadiene and methylstyrene can also be copolymerized in a block copolymerization manner. In the block copolymerization, the methylstyrene content can be higher, but the viscosity in the melt state will also be higher, which is contrary to the requirements for use in phase change material fixtures.

[0012] α-Methylstyrene and p-tert-butylstyrene are the same as p-methylstyrene.

[0013] Isoprene, IUPAC nomenclature 2-methyl-1,3-butadiene, is an organic compound with the chemical formula C5H8. It is a colorless, volatile liquid, insoluble in water but soluble in most organic solvents such as ethanol and ether. It is mainly used in the production of polyisoprene rubber and is also the second monomer of butyl rubber. It is also used in the manufacture of pesticides, pharmaceuticals, fragrances, and adhesives. Isoprene, IUPAC nomenclature 1,3-pentadiene, chemical formula C5H8, has cis and trans isomers and is mainly used in the production of petroleum resins. Like butadiene, isoprene and isoprene are conjugated diene hydrocarbons and can be randomly copolymerized with arylethylene in lithium-based anionic polymerization to form random copolymers.

[0014] Currently, there are no reports of successful applications of hydrogenated conjugated diene-arylethylene random copolymers as phase change material fixtures. Summary of the Invention

[0015] To address the limitations of existing phase change material fixtures, such as limited operating temperature, excessively high or low phase change temperature, poor fluidity in the liquid phase, and low elastic modulus in the solid phase, the first objective of this invention is to provide a hydrogenated conjugated diene-arylethylene random copolymer that simultaneously possesses excellent properties such as high fluidity, moderate hardness, high elastic modulus, and high operating temperature.

[0016] A second objective of this invention is to provide a simple, low-cost, and mild method for preparing the hydrogenated conjugated diene-arylethylene random copolymer.

[0017] The third objective of this invention is to provide an application of a hydrogenated conjugated diene-arylethylene random copolymer. This hydrogenated conjugated diene-arylethylene random copolymer has the characteristics of good melt flowability, high elastic modulus, high hardness, and high operating temperature. When applied to the preparation of phase change material flexible fixtures, its comprehensive performance meets the requirements of phase change material flexible fixtures in the machining process of weakly rigid parts. It has a moderate phase change temperature, good fluidity of the liquid phase, high elastic modulus of the solid phase, high operating temperature, does not adhere to or wrap around the machining tool, is easy to peel off and remove from the machine part, is friendly to humans and the environment, and can be reused.

[0018] To achieve the above-mentioned technical objectives, the present invention provides a hydrogenated conjugated diene-arylethylene random copolymer, which is obtained by selective hydrogenation of alkenyl groups in the conjugated diene-arylethylene random copolymer; the mass percentage composition of arylethylene units to conjugated diene units in the conjugated diene-arylethylene random copolymer is 20-65%:35-80%; the ratio of 1,4-structural units to 1,2-structural units and / or 3,4-structural units in the conjugated diene-arylethylene random copolymer is 0.3-2:1.

[0019] The hydrogenated conjugated diene-arylethylene random copolymer provided by this invention has a unique molecular structure. The conjugated diene unit and arylethylene unit in the butadiene-p-methylstyrene random copolymer exhibit a random copolymer structure, containing an appropriate proportion of arylethylene units and 1,2- and / or 3,4- structural units of the butadiene conjugated diene hydrocarbon. After selective hydrogenation of the alkenyl groups, various side groups on the main chain are transformed into ethyl, propenyl, and isopropyl branches. Simultaneously, the side chains also contain rigid p-methylbenzene rings, α-methyl, and p-tert-butylbenzene rings. This unique molecular structure endows the hydrogenated conjugated diene-arylethylene random copolymer with excellent tensile properties, hardness, elastic modulus, and melt flowability, as well as a high melting temperature, which can better meet the performance requirements of flexible clamps for phase change materials.

[0020] The mass ratio of arylethylene units to conjugated diene units in the random copolymer of conjugated diene-arylethylene provided by this invention is an important factor affecting the hardness of the hydrogenated conjugated diene-arylethylene random copolymer, and also a factor affecting its melt flowability. The arylethylene content is positively correlated with hardness; a high arylethylene content has an adverse effect on melt flowability. As a preferred embodiment, the proportion of arylethylene in the total mass is 20%–65%.

[0021] As a preferred embodiment, the number-average molecular weight of the conjugated diene-arylethylene random copolymer is 45,000 to 100,000, and the molecular weight distribution index is ≤1.08. Molecular weight affects the tensile properties, hardness, and melt flowability of the hydrogenated conjugated diene-arylethylene random copolymer. Molecular weight is positively correlated with tensile properties and hardness, but a high molecular weight is detrimental to melt flowability. Considering the existing production process of solution-polymerized styrene-butadiene rubber, the molecular weight is selected to be between 45,000 and 100,000, with a molecular weight distribution index ≤1.08.

[0022] As a preferred embodiment, the degree of hydrogenation of the alkenyl group in the hydrogenated conjugated diene-arylethylene random copolymer is not less than 98%, and the degree of hydrogenation of the benzene ring is not more than 5%. Through selective hydrogenation of the alkenyl group, rigid p-methyl, α-methyl, p-tert-butyl groups are retained, while a large number of short-branched and flexible alkane chains are generated.

[0023] The hydrogenated conjugated diene-arylethylene random copolymer provided by this invention has the following chemical structural formula (specifically illustrated using butadiene-p-methylstyrene as an example):

[0024]

[0025] Where x, y, and z are all degrees of polymerization, x is the number of hydrogenated butadiene units with a 1,4-structure, y is the number of hydrogenated butadiene units with a 1,2-structure, and z is the number of p-methylstyrene units.

[0026] From a molecular structure perspective, the melt viscosity of hydrogenated arylethylene thermoplastic elastomers with block structures has the following relationship with their molecular weight: η = KM 5.5 Where η is viscosity, K is a constant, and M is molecular weight; while for homopolymers and random copolymers, η = KM 3.4 The symbols have the same meaning as in the above formula. Clearly, block structures are not conducive to the low viscosity required by the target material. While polyarylene blocks in hydrogenated arylethylene thermoplastic elastomers also provide good hardness, the hardness can be improved through random copolymerization of arylethylene and conjugated dienes, and also by adjusting the formulation of the phase change material flexible clamp, at a lower cost. Furthermore, the random copolymerization process of the hydrogenated conjugated diene-arylethylene random copolymer described in this invention is simpler and more advantageous than the synthesis process of block structures.

[0027] This invention uses a hydrogenated conjugated diene-arylethylene random copolymer, which has better melt flowability compared to hydrogenated conjugated diene-arylethylene block copolymer.

[0028] In the random copolymer of conjugated diene-arylethylene of the present invention, arylethylene units and conjugated diene units are relatively uniformly distributed according to their molar ratio. Although the arylethylene units and conjugated diene units are relatively uniformly distributed, the degree of randomization cannot reach 100% in practice. Thus, some polyarylethylene microblocks will exist in the chain segments. Microblocks can increase the material hardness, but they also increase the melt viscosity of the material. Furthermore, large microblocks may form thermoplastic elastomers. Therefore, the microblocks must be controlled within a suitable range. The control of microblocks is closely related to the structure modifier, polymerization temperature, and feeding method. The polymerization temperature has a very important influence on many aspects and is basically controlled at 60-80℃ in industrial production. The feeding method is also affected by factors such as cost and control in the production process and is basically fixed. Therefore, the present invention controls the microblocks by the type and concentration of the structure modifier.

[0029] The 1,4-structure of butadiene forms polyethylene upon hydrogenation, and the 1,2-structure forms poly-1-butene upon hydrogenation. The 1,4-structure of isoprene forms a polyethylene unit and a polypropylene unit linked together upon hydrogenation. The 1,2-structure yields poly-2-methyl-1-butene upon hydrogenation, and the 3,4-structure yields poly-3-methyl-1-butene upon hydrogenation. The 1,4-structure of isoprene yields a polyethylene unit and a polypropylene unit linked together upon hydrogenation, the 1,2-structure yields poly-1-pentene, and the 3,4-structure yields poly-2-pentene. Except for the 1,4-structure of butadiene, all other structures have side groups, which can disrupt the crystallization of the main chain, resulting in macroscopic properties similar to rubber.

[0030] If there are more than five consecutive polyethylene units, they easily crystallize, macroscopically manifesting as polyethylene plastic segments. If there are too many butadiene 1,4-structures in the copolymer, it leads to an increased glass transition temperature and the loss of the material's rubber properties. Therefore, during the molecular design stage, by using arylethylene units and the side groups formed after hydrogenation of 1,2- or 3,4-structures, and ensuring a certain proportion and relatively uniform distribution within the chain segments, the crystallization caused by excessively long polyethylene units can be disrupted, thus maintaining a balance between tensile properties and hardness in the material.

[0031] In summary, this invention utilizes the unique structure of hydrogenated conjugated diene-arylethylene random copolymers, specifically the molecular weight, the mass ratio of arylethylene to conjugated diene, the content of polyarylethylene microblocks, the uniformity of the distribution of arylethylene and conjugated diene units in the chain segments, the total amount of 1,2- and 3,4-structures in the conjugated diene units and the ratio and uniformity of the 1,4-structure, and the selective hydrogenation to eliminate double bonds in the conjugated diene units in the chain segments, to obtain hydrogenated conjugated diene-arylethylene random copolymers that meet performance requirements.

[0032] As a preferred embodiment, the degree of hydrogenation of the alkenyl group in the conjugated diene-arylethylene random copolymer is ≥98%, and the degree of hydrogenation of the benzene ring is ≤5%. A high degree of selective hydrogenation of the alkenyl group imparts good flexibility to the polymer, resulting in better processability, heat resistance, aging resistance, and reusability. If the alkenyl group is not hydrogenated or has a very low degree of hydrogenation, although it can still be used as the main material for flexible phase change material clamps, the resulting products have a short storage time and are prone to aging during use, which is not conducive to the reuse of the material.

[0033] As a preferred embodiment, the arylethylene unit is at least one of p-methylstyrene, α-methylstyrene, and p-tert-butylstyrene; the conjugated diene unit is at least one of isoprene, isoprene, and butadiene. Combining at least one styrene derivative such as p-methylstyrene, α-methylstyrene, or p-tert-butylstyrene with at least one of the conjugated diene hydrocarbons, such as isoprene, isoprene, or butadiene, can yield random copolymers similar to solution-polymerized styrene-butadiene rubber through anionic polymerization. Various combinations of styrene derivatives and conjugated diene hydrocarbons, when anionicly polymerized, yield structures similar to the random copolymers of this invention, and can also be applied to flexible clamps made of phase change materials.

[0034] The present invention also provides a method for preparing a hydrogenated conjugated diene-arylethylene random copolymer. The method involves adding a mixture of arylethylene and conjugated diene monomers to an anionic polymerization system for random copolymerization to obtain a conjugated diene-arylethylene random copolymer solution. The conjugated diene-arylethylene random copolymer solution is then subjected to a selective hydrogenation reaction to obtain the final product.

[0035] As a preferred approach, the conjugated diene monomer and arylethylene monomer are thoroughly mixed before being added to the anionic polymerization system for polymerization. The highly homogeneous mixing of the conjugated diene monomer and arylethylene monomer in the copolymerization reaction is beneficial for increasing the degree of random copolymerization.

[0036] As a preferred embodiment, the conjugated diene monomer and the arylethylene monomer are mixed by the following method: 1) evacuating the sealed container I to a negative pressure and injecting the arylethylene monomer into the sealed container I; 2) evacuating the sealed container II to a negative pressure and injecting the conjugated diene monomer into the sealed container II; 3) using nitrogen gas to pressurize the arylethylene monomer in the sealed container I into the sealed container II, and using the nitrogen pressure in the sealed container II to fully mix the arylethylene monomer and the conjugated diene monomer; or, using nitrogen gas to pressurize the conjugated diene monomer in the sealed container II into the sealed container I, and using the nitrogen pressure in the sealed container I to fully mix the conjugated diene monomer and the arylethylene monomer.

[0037] As a preferred embodiment, the nitrogen pressure in the sealed container I or sealed container II is maintained at 0.4 to 0.6 MPa.

[0038] As a preferred approach, the conjugated diene and arylethylene mixed monomers can be added in one go, in batches, or slowly and continuously. To improve the degree of random copolymerization, a continuous and slow addition method is preferable.

[0039] As a preferred embodiment, the anionic polymerization system comprises a nonpolar alkane solvent, an initiator, and a structure modifier.

[0040] As a preferred embodiment, the nonpolar alkane solvent is cyclohexane; the amount of cyclohexane used maintains the total mass percentage concentration of the monomers in the anionic polymer system within the range of 5% to 15%.

[0041] As a preferred embodiment, the initiator is n-butyllithium. Other common alkyllithium or aryllithium initiators are also frequently used in the art.

[0042] As a preferred embodiment, the structure modifier is at least one selected from bis(tetrahydrofurfuryl)propane, tetramethylethylenediamine, tetrahydrofurfuryl ethyl ether, and tetrahydrofuran. As a preferred embodiment, the amount of the structure modifier relative to the nonpolar alkane solvent is 70–290 mg / kg. This invention, by selecting appropriate structure modifiers and their concentrations in the anionic polymerization system, comprehensively controls the microblock content, the ratio of 1,2-structures, 3,4-structures to 1,4-structures, and while ensuring the content of 1,2-structures and 3,4-structures, also controls the content of microblocks, thus obtaining materials that meet the required properties.

[0043] The ratio of the total amount of 1,2- and 3,4-structures to the number of 1,4-structures in the conjugated diene unit: The structure regulator added in the polymerization process of this invention actually has three functions: First, it acts as a dissociator, breaking the association of n-butyllithium in nonpolar solvents, which is beneficial to improving the utilization efficiency of n-butyllithium; second, it acts as a polymerization rate regulator, adjusting the polymerization rate of arylethylene and conjugated diene, thereby adjusting the uniformity of the distribution of arylethylene and conjugated diene in the polymer chain. The greater the regulating effect, the more uniform the distribution and the fewer the microblocks; third, it acts as a structure regulator for conjugated diene, adjusting the ratio of the total amount of 1,2- and 3,4-structures to the 1,4-structure. The greater the regulating effect, the higher the total content of 1,2- and 3,4-structures. The latter two have opposite regulating directions, that is, the higher the content of 1,2-structures, the lower the content of microblocks. Therefore, it is necessary to select appropriate types and concentrations of structure regulators.

[0044] As a preferred embodiment, during the random copolymerization process, the pressure is maintained in the range of 0.1MPa to 0.5MPa, the temperature is 60 to 80℃, and the time is ≥70min (until the reaction is complete).

[0045] As a preferred embodiment, the conditions for the hydrogenation reaction are: hydrogen pressure of 1.0–2.0 MPa, hydrogenation reaction temperature of 70–75 °C, and time of 1.5–2.5 h.

[0046] As a preferred embodiment, the hydrogenation reaction employs a dicyclopentadiene titanium dichloride / dimethyl phthalate combined hydrogenation catalyst. This preferred hydrogenation catalyst exhibits high selectivity for hydrogenating alkenes.

[0047] In the hydrogenation reaction process of this invention, the adhesive is pumped into a hydrogenation reactor purged with nitrogen, heated to 70-75°C, and first, dimethyl phthalate, a co-catalyst, is added for passivation reaction for 5-15 minutes. Then, the main catalyst, dicyclopentadiene titanium dichloride, is added, and the hydrogenation reaction is carried out under a hydrogen pressure of 1.0-2.0 MPa for 1.5-2.5 hours. The degree of hydrogenation of the alkenyl group in the polymer is ≥98%, and the degree of hydrogenation of the benzene ring is ≤5%.

[0048] The hydrogenated conjugated diene-arylethylene random copolymer prepared by this invention requires the removal of metal ions. The main process is as follows: first, the hydrogenated adhesive solution is terminated by a small amount of soft water for 15 min; then, it is acidified with tert-decanoic acid or citric acid for 30 min; finally, soft water with a volume ratio of 10% of the adhesive solution is added, and emulsification is carried out for 15 min. After centrifugation and settling, the aqueous phase is separated. This process is repeated twice. β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate n-octadecyl alcohol ester (1076) or a mixture of it and tris[2,4-di-tert-butylphenyl]phosphite (168) is added to the remaining adhesive solution as an antioxidant. The adhesive solution is heated in water with steam to remove the solvent, and then dried in a forced-air drying oven at 60°C for 8 h to obtain the final product.

[0049] The present invention also provides an application of a hydrogenated conjugated diene-arylethylene random copolymer for the preparation of a phase change material flexible clamp.

[0050] As a preferred approach, hydrogenated conjugated diene-arylethylene random copolymers are melt-composited with oils and / or solid organic compounds.

[0051] As a preferred embodiment, the hydrogenated conjugated diene-arylethylene random copolymer has a mass percentage composition of 20-40%:60-80% for oil and / or solid organic matter.

[0052] As a preferred embodiment, the oil product comprises saturated liquid hydrocarbons; the solid organic matter comprises saturated solid hydrocarbons or saturated fats.

[0053] The technical solution of this invention involves mixing a hydrogenated conjugated diene-arylethylene random copolymer with oil and / or solid organic matter, melting it into a liquid, stirring it thoroughly until homogeneous, and then cooling and solidifying it to obtain a mixed material. This mixed material can be used as a phase change material flexible fixture for the processing of weakly rigid machine parts.

[0054] The solid organic compound in this invention is mainly composed of saturated organic compounds, such as a solid mixture of hydrocarbons primarily composed of straight-chain alkanes, preferably No. 58 paraffin wax. It can also be a low-melting-point solid organic compound containing other elements, such as polyethylene wax or stearic acid, preferably polyethylene wax. The oil is mainly composed of a liquid hydrocarbon mixture primarily composed of straight-chain alkanes, preferably cosmetic-grade No. 26 white oil. It can also be a cycloalkane oil whose main component is saturated cycloalkanes, preferably KN4003.

[0055] The preferred technical solution of this invention is to combine cosmetic-grade No. 26 white oil and No. 58 paraffin wax in the following mass percentages: 20-50% hydrogenated styrene-butadiene random copolymer, 20-60% No. 58 paraffin wax, and 20-50% cosmetic-grade No. 26 white oil. The mixture is heated until it melts (at a temperature of 150-210°C), and stirred thoroughly while heating. The mixture is then allowed to cool naturally to a solid state to obtain the desired material.

[0056] The hydrogenated conjugated diene-arylethylene random copolymer provided by this invention can be used to prepare phase change material flexible fixtures by uniformly melting and mixing with other conventional materials. These fixtures can be applied to the processing of weakly rigid machine parts. Compared with existing materials such as paraffin, low-melting-point metals, urea, and water-ice, they have the characteristics of good fluidity in liquid state, high elastic modulus in solid state, good resistance to high-frequency impact, high operating temperature, non-entanglement, non-adhesion to tools and workpieces, easy removal, no odor, harmless to the human body, environmentally friendly, and reusable.

[0057] Compared with existing technologies, the beneficial technical effects of the present invention are as follows:

[0058] 1. The hydrogenated conjugated diene-arylethylene random copolymer provided by this invention has a special molecular structure, consisting of hydrogenated arylethylene and conjugated diene random copolymer segments, rather than an arylethylene block copolymer structure. Furthermore, the conjugated diene units contain a suitable proportion of 1,2- and / or 3,4- structures, and the conjugated diene units are highly hydrogenated. This special molecular structure endows the polymer with excellent comprehensive mechanical properties, particularly high fluidity in the molten state and certain hardness and elastic modulus in the elastic state. After melt blending with other materials, it is very suitable as a flexible phase change material for processing weakly rigid machine parts. It possesses advantages such as good fluidity in the liquid state, high hardness and elastic modulus in the solid state, good impact resistance, non-adhesion, non-entanglement with processing tools, a suitable solid-liquid phase change range, harmlessness to the human body, environmental friendliness, and reusability.

[0059] 2. The hydrogenated conjugated diene-arylethylene random copolymer of the present invention has four outstanding advantages: First, due to the special structure of the random copolymer segments of arylethylene and conjugated diene, the random copolymerization of arylethylene and conjugated diene ensures that the elastomeric characteristics are maintained even when the mass percentage of arylethylene in the copolymer exceeds 50%. The absence of polyarylethylene blocks improves the fluidity of the material in the molten state. At the same time, the molecular weight is controlled within a certain range, ensuring that the hydrogenated conjugated diene-arylethylene random copolymer maintains good fluidity in the molten state while maintaining certain hardness and tensile properties. Second, the type and concentration of structure regulators during polymerization simultaneously control the polyarylethylene content in the chain segments. The structural factors, such as the amount of ethylene microblocks, the total amount of 1,2- and 3,4-structures in the conjugated diene units, and their ratio and distribution to the 1,4-structure, ensure that the tensile properties, hardness, and melt flowability of the hydrogenated conjugated diene-arylethylene random copolymer meet the required performance requirements. Thirdly, selective hydrogenation of the conjugated diene-arylethylene random copolymer selectively eliminates alkenyl unsaturated bonds, reducing the factors affecting material properties and greatly improving the material's temperature resistance, allowing for reuse and reducing costs. Fourthly, the removal of ions expands the material's applicability to weakly rigid components of different materials, which is particularly evident in the aerospace field.

[0060] The method for preparing hydrogenated conjugated diene-arylethylene random copolymer of the present invention is simple, low-cost, and has mild process conditions, meeting the requirements of industrial production applications. Attached Figure Description

[0061] Figure 1 The random copolymer (styrene-butadiene) is the unhydrogenated GPC.

[0062] Figure 2 The NMR spectrum of the random copolymer (p-methylstyrene-isoprene) is shown. Detailed Implementation

[0063] To further illustrate the details of the present invention, several embodiments are provided. These embodiments are intended to illustrate the content of the present invention, rather than to limit the scope of protection of the claims of the present invention.

[0064] Analytical methods: Molecular weight and molecular weight distribution were determined by gel permeation chromatography; melt index was tested according to GB / T 3682-20008; hardness was determined according to GB / T 2411-2008; the contents of 1,2, 3,4 and 1,4 structures were determined based on HNMR analysis results.

[0065] In the following examples, butadiene monomer and p-methylstyrene monomer were mixed uniformly by the following method: 1) The sealed container I was evacuated to a negative pressure and p-methylstyrene monomer was injected into the sealed container I; 2) The sealed container II was evacuated to a negative pressure and butadiene monomer was injected into the sealed container II; 3) Nitrogen gas was used to pressurize the p-methylstyrene monomer in the sealed container I into the sealed container II, and the p-methylstyrene monomer and butadiene monomer were fully mixed uniformly by the nitrogen pressure (about 0.5 MPa) in the sealed container II.

[0066] Example 1

[0067] A base adhesive with a number average molecular weight of 90,000, 40% p-methylstyrene, and 60% butadiene was prepared first, and then hydrogen was added.

[0068] In a 5-liter polymerization reactor purged with high-purity nitrogen, 3000 mL of pure cyclohexane (water value <20 ppm) and 2.5 mL of bis(tetrahydrofurfuryl) propane (prepared as a 0.5 mol / L cyclohexane solution, equivalent to 100 mg / kg solvent) were added. Stirring was started, and the temperature was raised to 60°C. Then, 4.45 mmol of n-butyllithium was added, followed by the addition of a mixture of monomers—240 g of butadiene and 160 g of p-methylstyrene—in five equal portions, maintaining the reaction temperature at 70°C. After polymerization, the solution was transferred to a 5-liter hydrogenation reactor, heated to 70°C, and 5.0 mmol of n-butyllithium was added. The reaction was terminated with hydrogen for 10 minutes. Then, 14 mmol of dibutyl phthalate (co-catalyst) and 0.5 g of dicyclopentadiene titanium dichloride (main catalyst) were added. The hydrogenation pressure was controlled at 1.2 MPa, and the hydrogenation reaction was carried out for two hours, with 2 mL of co-catalyst added twice during the reaction. After the hydrogenation reaction was completed, the hydrogenated gel solution was transferred to a water washing vessel, heated to 65°C, and the reaction was terminated by 10 mL of soft water for 15 min. Then, it was acidified with 3.5 mL of tert-decanoic acid (dissolved in 200 mL of cyclohexane) for 30 min. Finally, it was emulsified and extracted with 350 mL of soft water for 15 min, centrifuged, allowed to stand, and the aqueous phase was separated. This process was repeated twice. The remaining gel solution was condensed with water vapor and dried to obtain hydrogenated butadiene-p-methylstyrene random copolymer.

[0069] The performance test results are as follows:

[0070] GPC analysis results showed that the number-average molecular weight of the base gel was 89,000, and the molecular weight distribution was 1.04.

[0071] Iodine value analysis results: degree of hydrogenation is 97.9%;

[0072] For performance purposes, elastomers do not require strong tensile properties; only melt flow index and hardness are measured. The Shore A hardness is 83, and the melt flow index is 16.2 g / 10 min.

[0073] The mixture is prepared with 30% hydrogenated butadiene-p-methylstyrene random copolymer, 35% No. 58 paraffin wax, and 35% No. 26 white oil by mass ratio. It is then mixed, heated to melt, mixed evenly, and then naturally cooled and solidified to room temperature. The Shore A hardness is 89. When used in flexible fixtures for phase change materials, it does not adhere to the cutting tool.

[0074] High-temperature aging resistance test method: Heat to liquid state, then naturally cool to solid state at room temperature, repeat 10 times. The product remains white and does not turn yellow. The results are summarized in Table 1.

[0075] Example 2

[0076] A random copolymer base adhesive with a number average molecular weight of 45,000, a p-methylstyrene content of 60%, and a butadiene content of 40% was prepared and then hydrogenated.

[0077] The preparation process was the same as in Example 1. The formulation for preparing the flexible clamp for phase change material was 45% hydrogenated butadiene-p-methylstyrene random copolymer by mass, 35% No. 58 paraffin wax, and 20% No. 26 white oil. The experimental results are shown in Table 1.

[0078] Example 3

[0079] A random copolymer base adhesive with a number average molecular weight of 65,000, a p-methylstyrene content of 30%, and a butadiene content of 70% was prepared and then hydrogenated.

[0080] The preparation process is the same as in Example 1. The formulation for preparing the flexible clamp for phase change materials is 30% hydrogenated butadiene-p-methylstyrene random copolymer by mass, 40% No. 58 paraffin wax, and 30% No. 26 white oil. The experimental results are shown in Table 1.

[0081] Comparative Example 1

[0082] A random copolymer base adhesive with a number average molecular weight of 90,000, a p-methylstyrene content of 40%, and a butadiene content of 60% was prepared without hydrogenation.

[0083] The preparation process was the same as in Example 1. The formulation for preparing the flexible clamp for phase change material was 30% unhydrogenated butadiene-p-methylstyrene random copolymer, 35% No. 58 paraffin wax, and 35% No. 26 white oil. The experimental results are shown in Table 1.

[0084] Heating to a liquid state and then naturally cooling to a solid state at room temperature, repeating this process 10 times, will cause the product to turn yellow and become unusable, indicating severe aging.

[0085] Comparative Example 2

[0086] A random copolymer base adhesive with a number average molecular weight of 65,000, a p-methylstyrene content of 10%, and a butadiene content of 90% was prepared and then hydrogenated.

[0087] The preparation process is the same as in Example 1, but the 1,2-structure is controlled to be below 15%. After hydrogenation, the resulting adhesive solution yields a plastic material, which cannot be used to prepare phase change flexible fixtures.

[0088] The ratio of the 1,2-structures of p-methylstyrene and butadiene both affect the crystallinity of the polymer. If the p-methylstyrene content is low and the 1,2-structure ratio of butadiene is also low, the polymer will have high crystallinity and lose its elasticity.

[0089] Table 1: Application of Flexible Clamps for Copolymers and Phase Change Materials with Different Structures

[0090]

[0091]

Claims

1. An application of a hydrogenated conjugated diene-arylethylene random copolymer, characterized in that: Used to prepare flexible fixtures for phase change materials; The hydrogenated conjugated diene-arylethylene random copolymer is obtained by selective hydrogenation of the alkenyl group in the conjugated diene-arylethylene random copolymer. The mass percentage composition of the conjugated diene-arylethylene random copolymer is 20~65%:35~80% for arylethylene units and conjugated diene units. The ratio of 1,4-structural units to 1,2-structural units and / or 3,4-structural units in the conjugated diene-arylethylene random copolymer is 0.3~2:

1. The arylethylene unit is at least one of p-methylstyrene, α-methylstyrene, and p-tert-butylstyrene; The degree of hydrogenation of the alkenyl group in the conjugated diene-arylethylene random copolymer is not less than 98%, and the degree of hydrogenation of the benzene ring is not higher than 5%.

2. The application of the hydrogenated conjugated diene-arylethylene random copolymer according to claim 1, characterized in that: The number-average molecular weight of the conjugated diene-arylethylene random copolymer is 45,000 to 100,000, and the molecular weight distribution index is ≤1.

08.

3. The application of the hydrogenated conjugated diene-arylethylene random copolymer according to claim 1 or 2, characterized in that: The conjugated diene unit is at least one of isoprene, isoprene, and butadiene.

4. The application of the hydrogenated conjugated diene-arylethylene random copolymer according to claim 1 or 2, characterized in that: The hydrogenated conjugated diene-arylethylene random copolymer is obtained by the following preparation method: in an anionic polymerization system, a mixture of arylethylene and conjugated diene monomers is added for random copolymerization to obtain a conjugated diene-arylethylene random copolymer solution, and the conjugated diene-arylethylene copolymer solution is subjected to a hydrogenation reaction to obtain the final product.

5. The application of the hydrogenated conjugated diene-arylethylene random copolymer according to claim 4, characterized in that: The p-methylstyrene and butadiene mixed monomers are obtained by mixing them as follows: 1) The sealed container I is evacuated to a negative pressure and arylethylene monomers are injected into the sealed container I; 2) The sealed container II is evacuated to a negative pressure and conjugated diene monomers are injected into the sealed container II; 3) The arylethylene monomers in the sealed container I are forced into the sealed container II with nitrogen gas, and the arylethylene monomers and conjugated diene monomers are fully mixed and homogeneous by the nitrogen gas pressure in the sealed container II; or, the conjugated diene monomers in the sealed container II are forced into the sealed container I with nitrogen gas, and the conjugated diene monomers and arylethylene monomers are fully mixed and homogeneous by the nitrogen gas pressure in the sealed container I.

6. The application of the hydrogenated conjugated diene-arylethylene random copolymer according to claim 5, characterized in that: The nitrogen pressure in either sealed container I or sealed container II is maintained at 0.4–0.6 MPa.

7. The application of the hydrogenated conjugated diene-arylethylene random copolymer according to claim 4, characterized in that: The mixed monomers of arylethylene and conjugated diene are added in one go, in batches, or slowly and continuously.

8. The application of the hydrogenated conjugated diene-arylethylene random copolymer according to claim 4, characterized in that: The anionic polymerization system contains nonpolar alkane solvents, initiators, and structure modifiers.

9. The application of the hydrogenated conjugated diene-arylethylene random copolymer according to claim 8, characterized in that: The nonpolar alkane solvent is cyclohexane; The amount of cyclohexane used maintains the total mass percentage concentration of the monomers in the anionic polymer system within the range of 5% to 15%. The initiator is n-butyllithium; The structure modifier is at least one of bis(tetrahydrofurfuryl)propane, tetramethylethylenediamine, tetrahydrofurfuryl ethyl ether, and tetrahydrofuran; The amount of the structure modifier relative to the nonpolar alkane solvent is 70–290 mg / kg.

10. The application of the hydrogenated conjugated diene-arylethylene random copolymer according to claim 4, characterized in that: During the random copolymerization process, the polymerization pressure is maintained in the range of 0.1MPa to 0.5MPa, the temperature is 60 to 80℃, and the time is ≥70min.

11. The application of the hydrogenated conjugated diene-arylethylene random copolymer according to claim 4, characterized in that: The conditions for the hydrogenation reaction are: hydrogen pressure of 1.0~2.0 MPa, temperature of 70~85℃, and time of 1.5~2.5 h.

12. The application of a hydrogenated conjugated diene-arylethylene random copolymer according to claim 4 or 11, characterized in that: The hydrogenation reaction process uses a combination hydrogenation catalyst of dicyclopentadiene titanium dichloride and dimethyl phthalate.

13. The application of the hydrogenated conjugated diene-arylethylene random copolymer according to claim 1, characterized in that: The hydrogenated conjugated diene-arylethylene random copolymer is melt-mixed with oil and / or solid organic matter.

14. The application of the hydrogenated conjugated diene-arylethylene random copolymer according to claim 13, characterized in that: The mass percentage composition of the hydrogenated conjugated diene-aryl ethylene random copolymer and oil and / or solid organic matter is 20~50% : 50~80%.

15. The application of the hydrogenated conjugated diene-arylethylene random copolymer according to claim 14, characterized in that: The oil products include saturated liquid hydrocarbons; the solid organic matter includes saturated solid hydrocarbons or saturated fats.

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