CN117069881A - Low cis-polybutadiene rubber and preparation method and application thereof - Google Patents

Abstract

The invention relates to the field of polymer preparation and discloses a low cis polybutadiene rubber and its preparation method and application. The molecular weight of the low cis polybutadiene rubber has a bimodal distribution, and has the following characteristics: the ratio of the number average molecular weight of the high molecular weight component of the bimodal distribution to the number average molecular weight of the low molecular weight component is 5-6; The number average molecular weight of the low molecular weight component with peak distribution is 30000-50000 and the molecular weight distribution index is 1-1.1; the number average molecular weight of the high molecular weight component with bimodal distribution is 150000-300000 and the molecular weight distribution index is 1-1.1; low The Mooney viscosity ML ₁₊₄ of cis-polybutadiene rubber is 45-65 at 100°C; the viscosity of a 5 wt% styrene solution at 25°C is 10-28 centipoise. The low cis polybutadiene rubber has a high branching degree, low 5% styrene solution viscosity and high Mooney viscosity, and can be suitable for high-gloss HIPS resin.

Description

Low-cis polybutadiene rubber and its preparation method and application

Technical Field

The invention relates to the field of polymer preparation, and in particular to a low-cis polybutadiene rubber and a preparation method and application thereof.

Background Art

Continuous bulk HIPS can be divided into high flow HIPS, high gloss HIPS, matte HIPS, high impact HIPS and ultra-high impact HIPS according to different uses. Polybutadiene rubber is the first choice for the toughening rubber of continuous bulk HIPS due to its low glass transition temperature and good low-temperature impact resistance. According to different microstructures, polybutadiene rubber used for HIPS toughening is divided into high cis polybutadiene rubber and low cis polybutadiene rubber. Among them, low cis polybutadiene rubber has low gel content, does not contain transition metals, has good color, has random distribution of cis and trans, has no crystallization tendency, has good low-temperature impact resistance, can freely adjust molecular weight, has moderate content of 1,2-structural units, and has high grafting and cross-linking reaction activity. It is the first choice for toughening rubber modification of continuous bulk HIPS resin.

Within a reasonable range of rubber particle size, as the rubber particle size increases, the rubber particles are more likely to induce silver streaks and shear bands, thereby better dissipating impact energy and improving the impact resistance of HIPS resin. As the rubber particle size increases, the scattering effect on light weakens, and the gloss of the HIPS resin decreases. In the HIPS production process, the toughened rubber is dissolved in the styrene monomer and thermal initiation (or free radical initiation) is used. In the early stage of polymerization, the rubber phase is the continuous phase. As the grafting reaction proceeds, when the solution viscosity of the polystyrene phase is equal to the solution viscosity of the rubber phase, a phase inversion begins to occur. Therefore, the greater the viscosity of the rubber solution, the later the phase inversion occurs, and more polystyrene will be contained in the rubber phase, thereby forming a larger rubber particle size. Generally speaking, the preparation of high-gloss HIPS requires a toughened rubber with a 5% styrene solution viscosity of less than 50 centipoise to obtain rubber particles less than 1μm.

CN109503747A discloses a low cis polybutadiene rubber with a Mooney viscosity of 40-65 and a viscosity of 80-120 centipoise of a 5 wt% styrene solution at 25°C and its application in HIPS/ABS resin. CN109251262A discloses a low cis polybutadiene rubber with a trimodal molecular weight distribution and its application in HIPS resin. CN109251263A discloses a low cis polybutadiene rubber with a weight average molecular weight of 170,000-380,000 and a molecular weight distribution of 2-3 and its application in HIPS/ABS resin. CN109503746A discloses a low cis polybutadiene rubber with a Mooney viscosity of 40-65 and a viscosity of 140-190 centipoise of a 5 wt% styrene solution at 25°C and its application in HIPS/ABS resin. CN106589247A discloses a low cis polybutadiene rubber with a Mooney viscosity of 50-70 and a viscosity of 40-60 centipoise of a 5 wt% styrene solution at 25°C and its application in HIPS/ABS resin. In order to ensure that the Mooney viscosity of the product is within a suitable range to obtain good processing performance, the 5% styrene solution viscosity of the product is relatively high, which limits its application in the field of high gloss HIPS.

The star-shaped low-cis polybutadiene rubber products formed on the market are almost all coupled with silicon tetrachloride to obtain four-arm branched star-shaped low-cis polybutadiene rubber. For ultra-high gloss continuous bulk HIPS resin, it is necessary to reduce the 5% styrene solution viscosity of the toughened rubber as much as possible. The 5% styrene solution viscosity of the existing four-arm coupled star-shaped low-cis polybutadiene rubber cannot be infinitely reduced, otherwise its Mooney viscosity will be reduced to the point where it cannot be processed. At present, the low-cis polybutadiene rubber product with the lowest 5% styrene solution viscosity on the market is 720AX from Asahi Chemical of Japan. Its 5% styrene solution viscosity is in the range of 20-30 centipoise, but its 100°C Mooney viscosity is below 40, and the cold flow phenomenon is very serious during processing.

Therefore, there is an urgent need to develop a low-cis polybutadiene rubber product with lower 5% styrene solution viscosity and moderate Mooney viscosity to meet the demand for upgrading high-quality HIPS resin products.

Summary of the invention

The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and to provide a low-cis polybutadiene rubber and a preparation method and application thereof. The low-cis polybutadiene rubber has a high degree of branching, a low 5% styrene solution viscosity and a high Mooney viscosity and can be suitable for high-gloss HIPS resin.

In order to achieve the above object, the present invention provides a low-cis polybutadiene rubber on one hand, characterized in that the molecular weight of the low-cis polybutadiene rubber is bimodal distribution, and the low-cis polybutadiene rubber has the following characteristics:

(1) The ratio of the number average molecular weight Mn2 of the high molecular weight component of the bimodal distribution to the number average molecular weight Mn1 of the low molecular weight component is 5-6;

(2) The number average molecular weight Mn1 of the low molecular weight component of the bimodal distribution is in the range of 30,000-50,000, and the molecular weight distribution index Mw1/Mn1 is 1-1.1;

(3) The number average molecular weight Mn2 of the high molecular weight component of the bimodal distribution is in the range of 150,000-300,000, and the molecular weight distribution index Mw2/Mn2 is 1-1.1;

(4) The Mooney viscosity ML ₁₊₄ of the low cis polybutadiene rubber at 100° C. is in the range of 45-65;

(5) The viscosity of a 5 wt% styrene solution of the low-cis polybutadiene rubber at 25° C. is in the range of 10-28 centipoise.

A second aspect of the present invention provides a method for preparing low-cis polybutadiene rubber, characterized in that the preparation method comprises the following steps:

(1) in an organic solvent, in the presence of an organic lithium initiator and a structure regulator, subjecting 1,3-butadiene to anionic solution polymerization until the conversion rate of 1,3-butadiene is above 99%, thereby obtaining a polybutadiene active chain; wherein the molar ratio of the 1,3-butadiene to the organic lithium initiator is 550-950:1;

(2) in the presence of a hexafunctional coupling agent, subjecting the polybutadiene active chain to a coupling reaction; the molar ratio of the coupling agent to the organic lithium initiator is 0.14-0.19:1;

(3) terminating the product of the coupling reaction in the presence of a terminator.

The third aspect of the present invention provides a low-cis polybutadiene rubber prepared by the above preparation method.

A fourth aspect of the present invention provides a use of the low-cis polybutadiene rubber in a HIPS resin.

The low-cis polybutadiene rubber provided by the present invention and its preparation method and application achieve the following beneficial effects:

The low cis polybutadiene rubber provided by the invention has high Mooney viscosity, ultra-low 5% styrene solution viscosity, low gel content and halogen content, good APHA chromaticity, and suitable molecular weight distribution. When used for toughening continuous bulk HIPS resin, it can significantly improve the glossiness of HIPS resin.

DETAILED DESCRIPTION

The endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article.

The first aspect of the present invention provides a low-cis polybutadiene rubber, characterized in that the molecular weight of the low-cis polybutadiene rubber is bimodal distribution, and the low-cis polybutadiene rubber has the following characteristics:

(1) The ratio of the number average molecular weight Mn2 of the high molecular weight component of the bimodal distribution to the number average molecular weight Mn1 of the low molecular weight component is 5-6;

(2) The number average molecular weight Mn1 of the low molecular weight component of the bimodal distribution is in the range of 30,000-50,000, and the molecular weight distribution index Mw1/Mn1 is 1-1.1;

(3) The number average molecular weight Mn2 of the high molecular weight component of the bimodal distribution is in the range of 150,000-300,000, and the molecular weight distribution index Mw2/Mn2 is 1-1.1;

(4) The Mooney viscosity ML ₁₊₄ of the low cis polybutadiene rubber at 100° C. is in the range of 45-65;

(5) The viscosity of a 5 wt% styrene solution of the low-cis polybutadiene rubber at 25° C. is in the range of 10-28 centipoise.

The low cis polybutadiene rubber provided by the present invention has high Mooney viscosity and low 5% styrene solution viscosity. When the molecular weight of the low cis polybutadiene rubber has the above characteristics, more small-size rubber can be obtained. When the low cis polybutadiene rubber is used for toughening continuous bulk HIPS resin, the glossiness of the HIPS resin can be significantly improved.

Specifically, in the present invention, when the number average molecular weight of the high molecular weight component in the bimodal distribution is controlled to meet the above range, the Mooney viscosity ML ₁₊₄ of the low cis polybutadiene rubber at 100°C can be within the range of 45-65. In the present invention, when the number average molecular weight of the low molecular weight component in the bimodal distribution is controlled to meet the above range, the viscosity of the 5 wt% styrene solution of the low cis polybutadiene rubber at 25°C can be within the range of 10-28 centipoise.

Furthermore, when the ratio of the number average molecular weights of the low molecular weight component and the high molecular weight component in the bimodal distribution (Mn2/Mn1) is controlled to meet the above range, the low cis polybutadiene rubber can have a higher number of branched arms, thereby ensuring that when the viscosity of the 5% styrene solution of the low cis polybutadiene rubber at 25°C is low, the Mooney viscosity can be maintained in an appropriate range, thereby having good processing performance.

Further, the number average molecular weight Mn1 of the low molecular weight component of the bimodal distribution is in the range of 35,000-45,000.

Further, the number average molecular weight Mn2 of the high molecular weight component of the bimodal distribution is in the range of 180,000-270,000.

Furthermore, the Mooney viscosity ML ₁₊₄ of the low-cis polybutadiene rubber at 100° C. is in the range of 50-60.

Furthermore, the viscosity of a 5 wt% styrene solution of the low-cis polybutadiene rubber at 25° C. is in the range of 12-26 centipoise, preferably in the range of 15-24 centipoise.

According to the present invention, the number average molecular weight Mn of the low-cis polybutadiene rubber is in the range of 140,000-260,000, and the molecular weight distribution index Mw/Mn is 1.1-1.5.

In the present invention, when the number average molecular weight and the molecular weight distribution index of the low cis polybutadiene rubber meet the above ranges, the low cis polybutadiene rubber can have a suitable particle size distribution and a 5 wt% styrene solution viscosity at 25°C. When the low cis polybutadiene rubber is used for toughening a continuous bulk HIPS resin, the comprehensive performance of the HIPS resin can be excellent.

Furthermore, the number average molecular weight Mn of the low-cis polybutadiene rubber is in the range of 160,000-240,000, and the molecular weight distribution index Mw/Mn is 1.15-1.45.

According to the present invention, the weight ratio of the low molecular weight component to the high molecular weight component of the bimodal distribution is 0.01-0.25:1.

In the present invention, when the weight ratio of the low molecular weight component to the high molecular weight component of the bimodal distribution satisfies the above range, the degree of branching of the low cis polybutadiene rubber can be controlled, thereby achieving control of the Mooney viscosity of the low cis polybutadiene rubber, so that the low cis polybutadiene rubber has a high degree of branching and a suitable Mooney viscosity to obtain good processing performance, thereby facilitating the control of the gel content and chromaticity of the product, and when used as a toughening agent, a HIPS resin with better comprehensive performance can be obtained.

In the present invention, the weight ratio of the low molecular weight component to the high molecular weight component of the bimodal distribution is measured by the GPC method.

Furthermore, the weight ratio of the low molecular weight component to the high molecular weight component of the bimodal distribution is 0.04-0.18:1.

According to the present invention, the weight ratio of the 1,2-structure content to the 1,4-structure content in the low-cis polybutadiene rubber is 0.06-0.25:1.

In the present invention, the term "1,2-structure" refers to a structural unit formed by 1,2-polymerization of butadiene, and the term "1,4-structure" refers to a structural unit formed by 1,4-polymerization of butadiene. When the weight ratio of the 1,2-structure content to the 1,4-structure content in the low cis polybutadiene rubber is controlled to meet the above range, when the low cis polybutadiene rubber is used to prepare HIPS resin, the grafting rate before the polymerization phase inversion of the continuous bulk HIPS resin and the crosslinking degree in the later stage of polymerization can be controlled.

Furthermore, the weight ratio of 1,2-structure content to 1,4-structure content in the low-cis polybutadiene rubber is 0.08-0.2:1.

According to the present invention, the gel content of the low cis polybutadiene rubber is ≤150 mg/kg, preferably ≤100 mg/kg, and more preferably ≤50 mg/kg. The gel in the low cis polybutadiene rubber will produce crystal points in the HIPS resin, forming stress concentration, resulting in a decrease in the mechanical properties of the HIPS resin and a deterioration in gloss. The lower the gel content, the less likely the prepared HIPS resin is to have defects and the better the overall performance.

According to the present invention, the metal content of the low cis polybutadiene rubber is ≤100 mg/kg, preferably ≤50 mg/kg, and more preferably ≤30 mg/kg. The metals in the low cis polybutadiene rubber, especially the variable valence metals, can cause the color of the product to deteriorate. In the present invention, the low cis polybutadiene rubber has a low metal content, so that the HIPS resin prepared from the low cis polybutadiene rubber has a low yellow index.

According to the present invention, the halogen content of the low cis polybutadiene rubber is ≤150 mg/kg, preferably ≤100 mg/kg, and more preferably ≤50 mg/kg. In the present invention, the low cis polybutadiene rubber has a low halogen content, which can avoid the increase of APHA chromaticity due to excessive halogen content in the low cis polybutadiene rubber, and at the same time, the increase of the yellow index of the HIPS resin.

According to the present invention, the APHA chromaticity of the low cis polybutadiene rubber is ≤10, preferably ≤7, and more preferably ≤5. In the present invention, the low cis polybutadiene rubber has a low APHA chromaticity, indicating that the low cis polybutadiene rubber solution has high clarity and transparency, avoiding the increase in the yellowness index of the HIPS resin due to the increase in the APHA chromaticity of the low cis polybutadiene rubber.

A second aspect of the present invention provides a method for preparing low-cis polybutadiene rubber, characterized in that the preparation method comprises the following steps:

(1) in an organic solvent, in the presence of an organic lithium initiator and a structure regulator, subjecting 1,3-butadiene to anionic solution polymerization until the conversion rate of 1,3-butadiene is above 99%, thereby obtaining a polybutadiene active chain; wherein the molar ratio of the 1,3-butadiene to the organic lithium initiator is 550-950:1;

(2) in the presence of a hexafunctional coupling agent, subjecting the polybutadiene active chain to a coupling reaction; the molar ratio of the coupling agent to the organic lithium initiator is 0.14-0.19:1;

(3) terminating the product of the coupling reaction in the presence of a terminator.

In the present invention, the low cis polybutadiene rubber described in the first aspect of the present invention can be obtained by adopting the above preparation method. In particular, in the present invention, in the presence of a 6-functional coupling agent, the polybutadiene active chain is coupled, and when the molar ratio of the coupling agent to the organic lithium initiator is controlled to meet the above range, the low cis polybutadiene rubber obtained can have a high Mooney viscosity, an ultra-low 5% styrene solution viscosity, low gel content and halogen content, good APHA chromaticity, and appropriate molecular weight distribution. When used for toughening continuous bulk HIPS resin, the gloss of the HIPS resin can be significantly improved.

According to the present invention, in step (1), the anionic solution polymerization reaction will obtain a polymer active chain of 1,3-butadiene, and the reaction process will be controlled so that 1,3-butadiene is polymerized to obtain a polybutadiene active chain with a number average molecular weight of 30,000-50,000, preferably a number average molecular weight of 35,000-45,000. In particular, the molecular weight distribution index of the polybutadiene active chain is 1.0-1.1.

In the present invention, in step (1), the organic solvent may be an organic solvent commonly used in the art, such as an alkane solvent and/or a cycloalkane solvent. The alkane solvent is preferably at least one of C4-C8 alkane solvents, more preferably at least one of n-pentane, n-hexane, n-heptane and isooctane. The cycloalkane solvent is preferably at least one of C4-C8 cycloalkane solvents, more preferably cyclopentane and/or cyclohexane.

In the present invention, the amount of the organic solvent can vary within a wide range. Preferably, the content of 1,3-butadiene is 10-20% by weight based on the total weight of the organic solvent and 1,3-butadiene.

In the present invention, there is no particular limitation on the type of the organic lithium initiator, and various organic lithium initiators conventionally used in the preparation of polybutadiene rubber in the art can be used. Preferably, the organic lithium initiator is a compound represented by the formula R ¹ Li, wherein R ¹ is selected from a C1-C10 alkyl group; more preferably, the organic lithium initiator is one or more of n-butyl lithium, sec-butyl lithium, isobutyl lithium and tert-butyl lithium, more preferably n-butyl lithium and/or sec-butyl lithium, and further preferably n-butyl lithium. The organic lithium initiator is added to the polymerization system in the form of a solution, and the solvent of the organic lithium initiator can be, for example, one or more of hexane, cyclohexane, heptane, etc., and the concentration is preferably 0.1-1.0 mol/L.

In the present invention, the amount of the organic lithium initiator can be reasonably selected according to the amount of the monomer and the number average molecular weight of the low cis polybutadiene rubber to be obtained, and the amount can vary within a wide range. Preferably, the molar ratio of 1,3-butadiene to the organic lithium initiator is 550-950:1, more preferably 600-850:1, so as to control the polybutadiene active chain obtained in step (1) to have the number average molecular weight required by the present invention.

According to the present invention, the anionic solution polymerization reaction in step (1) will make the conversion rate of 1,3-butadiene more than 99%, for example, 99-100%; preferably, the conditions of the anionic solution polymerization reaction include: temperature of 40-100°C, preferably 50-90°C; time of 20-100min, preferably 30-60min; gauge pressure of 0.1-1MPa, preferably 0.2-0.5MPa.

In the present invention, the anionic solution polymerization reaction is carried out in the presence of a structure regulator. In the present invention, there is no particular limitation on the type of the structure regulator, and any conventional type of structure regulator in the art can be used. Preferably, the structure regulator is an ether compound structure regulator and/or an amine compound structure regulator.

Preferably, the ether compound structure regulator is one or more of aliphatic monoether, aliphatic polyether, aromatic ether and cyclic ether.

More preferably, the aliphatic monoether is one or more of aliphatic symmetric monoether and aliphatic asymmetric monoether, the aliphatic symmetric monoether is one or more of methyl ether, ethyl ether, propyl ether and butyl ether, and the aliphatic asymmetric monoether is methyl ethyl ether.

More preferably, the aliphatic polyether is one or more of an aliphatic symmetrical polyether and an aliphatic asymmetrical polyether, the aliphatic symmetrical polyether is one or more of ethylene glycol di-C1-C4 alkyl ether, diethylene glycol di-C1-C4 alkyl ether and diethylene glycol di-C1-C4 alkyl ether, preferably one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether and diethylene glycol diethyl ether, and the aliphatic asymmetric polyether is ethylene glycol methyl ethyl ether and/or diethylene glycol methyl ethyl ether.

Preferably, the aromatic ether is anisole and/or diphenyl ether.

Preferably, the cyclic ether is one or more of tetrahydrofuran, tetrahydrofurfuryl alcohol C1-C4 alkyl ether and 1,4-dioxetane, preferably one or more of tetrahydrofuran, tetrahydrofurfuryl alcohol methyl ether, tetrahydrofurfuryl alcohol ethyl ether, tetrahydrofurfuryl alcohol propyl ether, tetrahydrofurfuryl alcohol isopropyl ether, tetrahydrofurfuryl alcohol butyl ether and 1,4-dioxetane.

Preferably, the amine compound structure regulator is preferably one or more of N,N,N',N'-tetramethylethylenediamine, N,N-dimethyltetrahydrofurfurylamine, triethylamine and tripropylamine.

In a preferred embodiment of the present invention, the structure regulator is one or more of tetrahydrofuran, tetrahydrofurfuryl alcohol methyl ether, tetrahydrofurfuryl alcohol ethyl ether, tetrahydrofurfuryl alcohol propyl ether, tetrahydrofurfuryl alcohol isopropyl ether, tetrahydrofurfuryl alcohol butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether and diethylene glycol diethyl ether, more preferably one or more of tetrahydrofurfuryl alcohol methyl ether, tetrahydrofurfuryl alcohol ethyl ether and tetrahydrofurfuryl alcohol propyl ether, particularly preferably tetrahydrofurfuryl alcohol ethyl ether.

According to the present invention, the molar ratio of the structure regulator to the organic lithium initiator is 0.02-2: 1. When the molar ratio of the structure regulator to the organic lithium initiator meets the above range, it can ensure that the vinyl content in the prepared low cis polybutadiene rubber meets the range defined by the present invention while increasing the reaction rate.

According to the present invention, in step (2), the obtained polymer presents a bimodal distribution through a coupling reaction, and the coupling reaction is controlled to obtain a bimodal polybutadiene rubber, wherein the number average molecular weight of the low molecular weight component in the bimodal is in the range of 30,000-50,000, and the molecular weight distribution index is 1-1.1; the number average molecular weight of the high molecular weight component in the bimodal is in the range of 150,000-300,000, and the molecular weight distribution index is 1-1.1; the ratio of the number average molecular weight of the high molecular weight component to the low molecular weight component in the bimodal is 5-6; the weight ratio of the low molecular weight component to the high molecular weight component in the bimodal is 0.01-0.25:1; and the molecular weight distribution of the low cis polybutadiene rubber is 1.1-1.5.

According to the present invention, the 6-functional coupling agent is selected from at least one of hexachlorodisilane, hexachloroethane, 1,1,1,3,3,3-hexachloropropane, glycerol triethyl ester and glycerol trimethyl ester. Further, in order to further improve the stability and repeatability of the coupling reaction, the 6-functional coupling agent is preferably hexachlorodisilane and/or hexachloroethane.

According to the present invention, in step (2), the molar ratio of the coupling agent to the organic lithium initiator is 0.15-0.18:1.

In the present invention, when the molar ratio of the coupling agent to the organic lithium initiator satisfies the above range, the low cis polybutadiene rubber prepared thereby has a better branching degree to obtain an ideal Mooney viscosity.

According to the present invention, the conditions of the coupling reaction include: reaction temperature of 40-100° C., reaction time of 15-40 min, and gauge pressure of 0.1-1 MPa.

Furthermore, the conditions of the coupling reaction include: reaction temperature of 60-100° C., reaction time of 20-40 min, and gauge pressure of 0.1-0.5 MPa.

In the present invention, preferably, steps (1) and (2) are carried out in a protective atmosphere, and the protective atmosphere is provided by one or more inactive gases selected from nitrogen, neon and argon.

In the present invention, in step (3), the coupling reaction and the polymerization reaction can be terminated by using a terminator, so that a polymerization solution containing low-cis polybutadiene rubber can be obtained.

According to the present invention, described terminator is one or more in alcohol, organic acid and carbon dioxide of C1-C4, is preferably one or more in isopropyl alcohol, stearic acid, citric acid and carbon dioxide, more preferably carbon dioxide.Adopt carbon dioxide to carry out termination reaction, carbon dioxide can form carbonate with the metal ion in polymerization system and separate from polymkeric substance, thus avoid the chromogenic reaction of metal ion, product has lower chroma.Carbon dioxide here can be passed into reaction system in the mode of gas (for example, passing into the carbon dioxide gas that gauge pressure is 0.2-1MPa (for example, can be 0.3-0.6MPa)), can also be introduced into reaction system in the form of dry ice aqueous solution (for example concentration is 0.1-5 weight %).

According to the present invention, the amount of the terminator is 0.1-0.2 parts by weight relative to 100 parts by weight of 1,3-butadiene monomer.

According to the present invention, in order to improve the antioxidant properties of low-cis polybutadiene rubber, preferably, the method further comprises: mixing the product obtained after termination of step (3) with an antioxidant.

In the present invention, there is no particular limitation on the type of antioxidant, and it can be a conventional antioxidant in the art. For example, the antioxidant is selected from one or more of 4,6-bis(octylthiomethyl)-o-cresol (trade name: antioxidant 1520), β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (trade name: antioxidant 1076), N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (trade name: antioxidant 4020), N-isopropylphenyl-N'-phenyl-p-phenylenediamine (trade name: antioxidant 4010NA) and N-phenyl-2-naphthylamine (trade name: antioxidant D), preferably a mixture of antioxidant 1520 and antioxidant 1076, in particular a combination of antioxidant 1520 and antioxidant 1076 in a weight ratio of 0.5-5:1, preferably 1:1.

According to the present invention, the dosage of the antioxidant can vary within a wide range. Preferably, the weight ratio of the antioxidant to 1,3-butadiene is 0.1-0.3:100.

In the present invention, in order to extract the low-cis polybutadiene rubber from the reaction product in which the antioxidant is terminated or introduced, such reaction product can also be subjected to steam condensation treatment to remove the solvent and dried to remove moisture, and then obtain dry low-cis polybutadiene rubber.

The third aspect of the present invention provides a low-cis polybutadiene rubber prepared by the above preparation method.

A fourth aspect of the present invention provides an application of low-cis polybutadiene rubber in HIPS resin.

In the present invention, the low-cis polybutadiene rubber is used as a toughening agent in HIPS resin.

In the present invention, although the toughening agent contains the low cis polybutadiene rubber obtained by the above method of the present invention, a high gloss HIPS resin can be obtained, in order to obtain a HIPS resin with better comprehensive performance, preferably, the weight ratio of styrene to the toughening agent on a dry weight basis is 550-1900:100, more preferably 800-1600:100. The toughening agent is preferably a low cis polybutadiene rubber.

The HIPS resin prepared by the method of the present invention has excellent mechanical properties, especially impact strength, and higher gloss; preferably, the surface gloss of the HIPS resin at 60° is above 90, preferably above 92, and more preferably above 95.

The present invention will be described in detail below by way of examples. In the following examples,

Molecular structure: The contents of 1,2-polymer structural units and 1,4-polymer structural units in low cis-polybutadiene rubber were tested using a Bruker AVANCE400 superconducting nuclear magnetic resonance wave instrument (1H-NMR). The resonance frequency of the 1H nucleus was 300.13 MHz, the spectrum width was 2747.253 Hz, the pulse width was 5.0 μs, the data point was 16 K, the sample tube diameter was 5 mm, the solvent was deuterated chloroform CDCl3, the sample concentration was 15% (W/V), the test temperature was room temperature, the number of scans was 16, and the chemical shift of tetramethylsilane was calibrated as 0 ppm.

Molecular weight and molecular weight distribution: Determined by HLC-8320 gel permeation chromatograph of Tosoh Corporation of Japan, equipped with TSKgelSuperMultiporeHZ-N and TSKgelSuperMultiporeHZ standard columns, the solvent was chromatographically pure THF, narrow distribution polystyrene was used as standard, the polymer sample was prepared into a tetrahydrofuran solution with a mass concentration of 1 mg/mL, the injection volume was 10.00 μL, the flow rate was 0.35 mL/min, and the test temperature was 40.0°C.

Viscosity of 5 wt% rubber styrene solution at 25°C: measured using Beijing Yanshan Petrochemical Company corporate standard Q/SH3155.SXL.C26-2019, and measured at a constant temperature of 25°C using a Finn viscometer. The viscosity of rubber in styrene (solution concentration 5% by weight) at 25°C is measured using the flow resistance of the fluid through the capillary within a certain period of time. Accurately prepare a styrene solution with a 5% rubber content, fill the viscometer ball with the solution, start the timer when the solution level reaches the upper mark of the ball, stop the timer when the solution level reaches the lower mark of the ball, and record the time it takes for the solution to flow from the upper mark to the lower mark, accurate to 0.1 seconds. Instrument: constant temperature water bath and viscometer; test conditions: constant temperature of 25°C.

Gel content: Determined by weight method. The specific process is as follows: add the rubber sample to styrene, shake in an oscillator at 25°C for 16 hours to completely dissolve the soluble matter, prepare a styrene solution containing 5% by weight of rubber, and record the mass of the rubber sample as C (in grams); weigh a 360-mesh clean nickel mesh, and record the mass of the clean nickel mesh as B (in grams); then filter the above solution with the nickel mesh; rinse the nickel mesh with styrene after filtration, dry the nickel mesh at 150°C and normal pressure for 30 minutes, weigh it, and record its mass as A (in grams); calculate the gel content according to the following formula: Gel content % = [(A-B)/C] × 100%.

The Mooney viscosity was measured using a GT-7080-S2 Mooney viscometer produced by Taiwan Gotech Company in accordance with GB/T1232.1 standard, with a preheating time of 1 min, a rotation time of 4 min, and a test temperature of 100°C.

The metal content was tested by the Optima 8300 full-spectrum direct-reading ICP spectrometer of PerkinElmer (PE) in the United States, with a medium-step grating, solid-state detector, dual-path dual solid-state detector in the ultraviolet and visible light regions, and flat-plate plasma technology to ensure that the instrument has the lowest argon consumption. Instrument operating parameters: high-frequency power 1300W, plasma gas flow 15L/min, atomizing gas flow 0.55L/min, auxiliary gas flow 0.2L/min, peristaltic pump speed 1.50mL/min, integration time 10s, plasma axial observation. Analysis spectral lines: Ni 231.604nm, Al308.215nm, Li670.784nm, Fe238.204nm, Ca 317.933nm, Mg 285.213nm. Reagents: Nitric acid: high-grade pure, Sinopharm Chemical Reagent Co., Ltd., content 65%-68%; Ni, Al, Li, Fe, Ca, Mg basic standard solution: 100μg/mL, National Institute of Metrology; deionized water is used. Sample preparation: Accurately weigh 2.000g of sample in a porcelain crucible, place it in a high-temperature resistance furnace and gradually heat it to 500℃, take it out after complete ashing, add 5mL10% (V%) dilute nitric acid, slowly heat on a hot plate until completely dissolved, evaporate the solution to dryness, add 1mL concentrated nitric acid, transfer to a 50mL volumetric flask, distill water to volume, and prepare a reagent blank solution at the same time.

Halogen content: tested by combustion ion chromatography according to EN14582-2016 standard.

APHA chromaticity: The LCBR sample was prepared into a 5% styrene solution and measured using a LICO620 colorimeter with a colorimetric tube diameter of 11 mm.

The Izod notched impact strength of HIPS is measured according to GB/T1843-1996 standard (kJ/m ² ), and the 60° glossiness is measured according to ASTM D526 (60°).

The following carbon dioxide pressures refer to gauge pressure.

Cyclohexane and hexane were provided by Sinopharm Reagent Company, polymerization grade, and the molecular sieve was soaked until the water content was less than 10ppm; butadiene was provided by Yanshan Petrochemical, polymerization grade; THF was provided by Sinopharm Reagent Company, chromatographic grade, hexane was diluted 10 times and then soaked in molecular sieve for more than 15 days, and the amount used in the system was calculated as pure substance; tetrahydrofurfuryl alcohol ethyl ether was provided by Sinopharm Reagent Company, analytical grade, hexane was diluted 20 times and then soaked in molecular sieve for more than 15 days, and the amount used in the system was calculated as pure substance; n-butyl lithium was provided by J&K Reagent Co., Ltd., 1.6 mol.L ^-1 , diluted to 0.4 mol.L ^-1 ; hexachloroethane and hexachlorodisilane were provided by Inokai Reagent Company, analytical grade, diluted to 0.1 mol.L ^-1 ; antioxidants 1520 and 1076 were provided by Sinopharm Reagent Company, diluted to a mass concentration of 10%, and the amount used in the system was calculated as pure substance;

Polybutadiene rubber 720AX, purchased from Asahi Chemical, Japan, molecular structure parameters are shown in Table 3;

Polybutadiene rubber 730A was purchased from Asahi Chemical Industry Co., Ltd., Japan. The molecular structure parameters are shown in Table 3.

Example 1

This example is used to illustrate the LCBR rubber and the preparation method thereof of the present invention.

(1) under nitrogen protection, a non-polar hydrocarbon solvent, 1,3-butadiene monomer and a structure regulator (the types and amounts are shown in Table 1, and the amounts listed in the table are all measured by pure compounds) are added into a reactor, and after heating to a specified temperature, an organic lithium initiator (the types and amounts are shown in Table 1, and the amounts listed in the table are all measured by pure compounds) is added, and then an anionic solution polymerization reaction is carried out at the temperature and a specified reaction pressure (conditions are shown in Table 1) until the conversion rate of 1,3-butadiene is 100%;

(2) then adding a coupling agent (its type and amount are shown in Table 2, and the amounts listed in the table are all measured based on pure compounds) to the product of the anionic solution polymerization reaction to carry out a coupling reaction at a specified temperature and pressure (conditions are shown in Table 2);

(3) The coupling reaction was terminated by using a terminator (its type and amount are shown in Table 2), and then an antioxidant (1.2 g of a combination of 1520 and 1076 in a weight ratio of 1:1) was added and mixed to finally obtain a polymerization solution of LCBR rubber. The obtained polymerization solution was subjected to steam condensation desolventization treatment and dried to obtain LCBR rubber PB1. The structure and properties of the obtained polymer were measured, and the results are shown in Table 3.

Embodiment 2-9

This example is used to illustrate the LCBR rubber and the preparation method thereof of the present invention.

The method described in Example 1 is different in that the reaction is carried out using the parameters shown in Tables 1 and 2 to obtain LCBR rubbers PB2-PB9 respectively. The structures and properties of the obtained polymers are measured, and the results are shown in Table 3.

Comparative Example 1

The method described in Example 1 is different in that the coupling agent in step (2) is silicon tetrachloride; thereby LCBR rubber DPB1 is obtained. The structure and properties of the obtained polymer are measured, and the results are shown in Table 3.

Comparative Example 2

According to the method described in Example 1, except that in step (2), the coupling agent is silicon tetrachloride, and the amount used is 2.28 mmol, to obtain LCBR rubber DPB2. The structure and properties of the obtained polymer are measured, and the results are shown in Table 3.

Comparative Example 3

The method described in Example 1 is used, except that the amount of butyl lithium used in step (1) is 6 mmol, and the amount of hexachlorosilane used in step (2) is 1 mmol, thereby obtaining LCBR rubber DPB3. The structure and properties of the obtained polymer are measured, and the results are shown in Table 3.

Comparative Example 4

The method described in Example 1 is different in that in step (1), the amount of n-butyl lithium used is 15 mmol, and in step (2), the amount of hexachlorosilane used is 2.55 mmol, thereby obtaining LCBR rubber DPB4. The structure and properties of the obtained polymer are measured, and the results are shown in Table 3.

Comparative Example 5

The method described in Example 1 is different in that the amount of hexachlorosilane used in step (2) is 1.23 mmol, thereby obtaining LCBR rubber DPB5. The structure and properties of the obtained polymer are measured, and the results are shown in Table 3.

Comparative Example 6

The method described in Example 1 is different in that the amount of hexachlorosilane used in step (2) is 1.9 mmol, so that the molecular weight of the LCBR rubber DPB6 obtained is unimodal distribution. The structure and properties of the obtained polymer are measured, and the results are shown in Table 3.

Table 1

Table 2

Table 3

Note: Area1/Area2 is the weight ratio of the low molecular weight component to the high molecular weight component of the bimodal distribution.

Table 3 (continued)

It can be seen from Table 3 that the 5% styrene solution of the low cis polybutadiene rubber prepared in the present invention has extremely low viscosity, high Mooney viscosity, moderate molecular weight distribution, low gel content, halogen content and metal content, and is particularly suitable as a toughening agent for high gloss HIPS.

Application Example 1

This example is used to illustrate the HIPS resin and its preparation method of the present invention.

100 g of low-cis polybutadiene rubber PB1, 120 g of ethylbenzene and 900 g of styrene monomer were mixed, and then 40 g of mineral oil (provided by Beijing Yanshan Petrochemical Company Chemical Plant No. 1, density 0.85-0.88 g/ml, the same below) and 0.2 g of tert-butyl peroxy-2-ethylhexyl carbonate were added and mixed, and polymerized at a stirring rate of 400 rpm and a polymerization temperature of 110° C. for 2 h, and then heated to 120° C. for polymerization for 2 h; at a stirring rate of 150 rpm, the temperature was raised to 140° C. for polymerization for 2 h, and finally the temperature was raised to 150° C. for polymerization for 2 h, and the reaction product was subjected to vacuum flash evaporation to remove unreacted monomers and solvents to obtain HIPS resin P1.

After the HIPS resin was dried, its structure and performance were measured. The results are shown in Table 4.

Application Example 2-9

This example is used to illustrate the HIPS resin and its preparation method of the present invention.

The method described in Application Example 1 is different in that low cis polybutadiene rubbers PB2-PB9 are used instead of low cis polybutadiene rubber PB1, so that the reaction products are subjected to vacuum flash evaporation and unreacted monomers and solvents are removed to obtain HIPS resins P2-P9 respectively.

After the HIPS resin was dried, its structure and performance were measured. The results are shown in Table 4.

Comparative Application Examples 1-6

The method described in Application Example 1 is different in that low cis polybutadiene rubbers DPB1-DPB6 are used instead of low cis polybutadiene rubber PB1, so that the reaction products are subjected to vacuum flash evaporation and unreacted monomers and solvents are removed to obtain HIPS resins DP1-DP6 respectively.

After the HIPS resin was dried, its structure and performance were measured. The results are shown in Table 4.

Comparative Application Examples 7-8

The method described in Application Example 1 is different in that Japanese Asahi Chemical products 720AX and 730A are used instead of low-cis polybutadiene rubber PB1, so that the reaction products are subjected to vacuum flash evaporation and unreacted monomers and solvents are removed to obtain HIPS resins DP7-DP8 respectively.

After the HIPS resin was dried, its structure and performance were measured. The results are shown in Table 4.

Table 4

It can be seen from Table 4 that by using the low-cis polybutadiene rubber of the present invention as a toughening agent, a HIPS resin with excellent gloss can be obtained while ensuring the impact strength of the HIPS resin. The HIPS resin obtained by the present invention has a significant improvement in gloss compared to the HIPS resin obtained by using a toughening agent popular on the market.

The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims (11)

1. A low cis-polybutadiene rubber characterized in that the molecular weight of the low cis-polybutadiene rubber is bimodal and the low cis-polybutadiene rubber has the following characteristics:

(1) The ratio of the number average molecular weight Mn2 of the bimodal high molecular weight component to the number average molecular weight Mn1 of the low molecular weight component is from 5 to 6;

(2) The bimodal low molecular weight component has a number average molecular weight Mn1 in the range of 30,000 to 50,000 and a molecular weight distribution index Mw1/Mn1 in the range of 1 to 1.1;

(3) The number average molecular weight Mn2 of the bimodal high molecular weight component is in the range of 150,000-300,000 and the molecular weight distribution index Mw2/Mn2 is from 1 to 1.1;

(4) Mooney viscosity ML of the low cis-polybutadiene rubber at 100 DEG C ₁₊₄ In the range of 45-65;

(5) The viscosity of the 5 wt.% styrene solution at 25℃of the low cis-polybutadiene rubber is in the range of 10 to 28 centipoise.

2. The low cis-polybutadiene rubber of claim 1, wherein the bimodal distribution of low molecular weight components has a number average molecular weight Mn1 in the range of 35,000-45,000;

preferably, the bimodal distribution of the high molecular weight component has a number average molecular weight Mn2 in the range of 180,000-270,000;

preferably, the low cis polybutadiene rubber has a Mooney viscosity ML at 100 DEG C ₁₊₄ In the range of 50-60;

preferably, the low cis polybutadiene rubber has a viscosity in the range of 12 to 26 centipoise, preferably 15 to 24 centipoise, in a 5 wt.% styrene solution at 25 ℃.

3. The low cis polybutadiene rubber according to claim 1 or 2, wherein the number average molecular weight Mn of the low cis polybutadiene rubber is in the range of 140,000-260,000, preferably in the range of 160,000-240,000; a molecular weight distribution index Mw/Mn of from 1.1 to 1.5, preferably from 1.15 to 1.45;

preferably, the weight ratio of bimodal low molecular weight component to high molecular weight component is from 0.01 to 0.25:1, preferably from 0.04 to 0.18:1;

preferably, the weight ratio of 1, 2-structure content to 1, 4-structure content in the low cis-polybutadiene rubber is 0.06-0.25:1; preferably 0.08-0.2:1.

4. The low cis polybutadiene rubber according to any of claims 1 to 3, wherein the gel content of the low cis polybutadiene rubber is equal to or less than 150mg/kg, preferably equal to or less than 100mg/kg, more preferably equal to or less than 50mg/kg;

preferably, the low cis polybutadiene rubber has a metal content of 100mg/kg or less, preferably 50mg/kg or less, more preferably 30mg/kg or less;

preferably, the low cis polybutadiene rubber has a halogen content of 150mg/kg or less, preferably 100mg/kg or less, more preferably 50mg/kg or less;

preferably, the low cis polybutadiene rubber has an APHA color of 10 or less, preferably 7 or less, more preferably 5 or less.

5. A process for the preparation of low cis-polybutadiene rubber, comprising the steps of:

(1) In an organic solvent, carrying out anionic solution polymerization reaction on 1, 3-butadiene in the presence of an organolithium initiator and a structure regulator until the conversion rate of the 1, 3-butadiene is more than 99%, so as to obtain a polybutadiene active chain; wherein the molar ratio of the 1, 3-butadiene to the organolithium initiator is 550-950:1, a step of;

(2) Coupling the polybutadiene living chain in the presence of a 6-functional coupling agent; the molar ratio of the coupling agent to the organolithium initiator is 0.14-0.19:1, a step of;

(3) The product of the coupling reaction is terminated in the presence of a terminating agent.

6. The process according to claim 5, wherein in step (1), the polybutadiene active chain has a number average molecular weight of 30,000-50,000, preferably 35,000-45,000;

preferably, the molar ratio of the 1, 3-butadiene to the organolithium initiator is 600-850:1;

preferably, the conditions of the anionic solution polymerization reaction include: the reaction temperature is 40-100 ℃, preferably 50-90 ℃; the reaction time is 20-100min, preferably 30-60min; the gauge pressure is 0.1-1MPa, preferably 0.2-0.5MPa;

preferably, the molar ratio of the structure modifier to the organolithium initiator is from 0.02 to 2:1.

7. the production method according to claim 5 or 6, wherein in the step (2), a molar ratio of the coupling agent to the organolithium initiator is 0.15 to 0.18:1, a step of;

preferably, the 6-functional coupling agent is selected from at least one of hexachlorodisilane, hexachloroethane, 1, 3-hexachloropropane, triethyl glycerol and trimethyl glycerol, preferably hexachlorodisilane and/or hexachloroethane;

preferably, the conditions of the coupling reaction include: the reaction temperature is 40-100 ℃, the reaction time is 15-40min, and the gauge pressure is 0.1-1MPa.

8. The preparation method according to any one of claims 5 to 7, wherein the terminator is selected from at least one of C1-C4 alcohol, organic acid and carbon dioxide, preferably at least one of isopropanol, stearic acid, citric acid and carbon dioxide, more preferably carbon dioxide;

preferably, the terminator is used in an amount of 0.1 to 0.2 parts by weight with respect to 100 parts by weight of the 1, 3-butadiene monomer.

9. The production method according to any one of claims 5 to 8, wherein the method further comprises: mixing the product obtained by terminating the step (3) with an antioxidant;

preferably, the weight ratio of the antioxidant to the 1, 3-butadiene is 0.1-0.3:100.

10. a low cis-polybutadiene rubber produced by the production process according to any one of claims 5 to 9.

11. Use of the low cis polybutadiene rubber of any one of claims 1-4 and 10 in HIPS resins.