Polar SBS elastomer containing glycidyl ether block and preparation method thereof

Abstract

The invention discloses a polar SBS elastomer containing glycidyl ether blocks and a preparation method thereof.The elastomer is of a-[(St) a-(Bd) b-(AGE) c]-(St) a-tetrablock structure, allyl glycidyl ether (AGE) is introduced as a polar monomer, a double-initiator cooperative control system (n-butyllithium / triethyl aluminum) is adopted, and the polar SBS elastomer containing glycidyl ether blocks is prepared. A polar group is accurately positioned in a molecular chain by combining segmented anionic polymerization and epoxy ring-opening polymerization processes, the preparation method of the elastomer comprises the steps of styrene prepolymerization, butadiene gradient chain extension, AGE ring-opening grafting, styrene end capping and the like, the final product has excellent mechanical properties and polar interface compatibility, the peel strength is improved by 176% compared with that of traditional SBS, and the service life of the elastomer is prolonged. The method is especially suitable for the field of blending modification of high-performance adhesives and polar materials.

Description

Technical Field

[0001] The invention relates to the field of polymer modification, and in particular to a polar SBS elastomer containing a glycidyl ether block and a preparation method thereof. Background Art

[0002] Thermoplastic elastomer SBS (styrene-butadiene-styrene block copolymer) is one of the thermoplastic elastomers with the largest output in the world. It exhibits the elasticity of rubber at room temperature and thermoplasticity at high temperature. It has excellent tensile properties, solubility, anti-slip properties and low temperature resistance, so SBS has important applications in many fields. However, as people's requirements for material performance in production and life continue to increase, the performance of SBS alone has shown to be insufficient, and research on SBS modification has attracted widespread attention. Polyethylene oxide (PEO) appears as a chain segment in the polymer structure, and its excellent properties will be transferred to the polymer with the existence of the structure, thereby improving the polymer performance and expanding its application range.

[0003] The Chinese patent authorization announcement number is CN110894332A, which discloses an oil-extended SBS thermoplastic elastomer and a preparation method thereof. This SBS thermoplastic elastomer is mainly modified by grafting with maleic anhydride, and has defects such as low grafting rate and easy cross-linking. Summary of the invention

[0004] The purpose of the present invention is to solve the above technical problems and provide a polar SBS elastomer containing a glycidyl ether block and a preparation method thereof.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present invention is as follows: a polar SBS elastomer containing a glycidyl ether block has a four-block structure of -[(St)_a-(Bd)_b-(AGE)_c]-(St)_a-, wherein a is the degree of polymerization of the styrene segment, a=100-200; b is the degree of polymerization of the butadiene segment, b=300-500; c is the degree of polymerization of the AGE unit, c=5-30, and the AGE unit is connected to the main chain through an ether bond formed by epoxy ring opening, and the oxygen atom of the ether bond is directly connected to the carbon chain of the butadiene segment.

[0006] Preferably, the 1,4-structure content in the butadiene segment of the present invention is 60-70%, and the 1,2-structure content is 30-40%; the number average molecular weight (Mn) of the elastomer is 8×10 4 -15×10 4 The melt flow index (190°C / 5kg) is 7-10g / 10min. The SAXS test of the elastomer shows that the hard segment phase spacing is 15-18nm, and the polar groups are enriched in the soft and hard segment interface region.

[0007] Preferably, the AGE unit in the present invention accounts for 5-15 wt% of the total mass of the monomers, and the epoxy ring-opening rate is ≥90%, the molecular weight distribution index PDI ≤ 1.25, and the hydroxyl content generated after the ring-opening of the AGE unit is 0.2-1.5 mmol / g.

[0008] Preferably, a method for preparing a polar SBS elastomer containing a glycidyl ether block in the present invention comprises the following steps: (1) Under an inert atmosphere, using cyclohexane as a solvent, adding a dual initiator system, the dual initiator being n-butyllithium and triethylaluminum, and the molar ratio of Al to Li being 0.2-0.5; (2) Stepwise polymerization: a. The first stage: Polymerize styrene at 40-50 °C to form a first polystyrene segment; b. The second stage: Raise the temperature to 60-70 °C, add butadiene for gradient chain extension, and add a THF regulator during this period to control the 1,4-structure content of butadiene; c. The third stage: Maintain at 70-75 °C, add allyl glycidyl ether for ring-opening grafting reaction for 20-40 minutes; d. The fourth stage: Lower the temperature to 50-55 °C, and add styrene for capping; (3) Add a terminator to terminate the reaction, and obtain the product through the processes of coagulation and drying.

[0009] Preferably, the water content of the solvent cyclohexane in step (1) of the present invention is ≤50 ppm, and the total monomer concentration is 12-18 wt%; In step (2) a, the addition rate of styrene is 0.5-1.5 kg / h, and the reaction pressure is 0.1-0.3 MPa; In step (2) b, the molar ratio of the THF regulator to Li⁺ is 4:1-6:1, and the gradient heating rate is 1-2 °C / min; In step (2) c, the addition of AGE is carried out by pulsed injection, and the injection amount each time is 10-20% of the total amount, and the interval time is 3-5 minutes; In step (2) d, the molar amount of the added styrene is 80-120% of the molar amount of the first polystyrene segment; The terminator in step (3) is a mixed solution of methanol, propylene oxide and ethyl acetate, and the volume ratio is 1-3:1:0.5-1.

[0010] Preferably, the addition temperature of the terminator in the present invention is 20-40 °C, and the addition rate is 0.5-1% / min of the total mass of the system.

[0011] Preferably, in the agglomeration process of the present invention, two-stage steam injection is adopted, with the primary steam pressure being 0.4 - 0.6 MPa and the secondary steam pressure being 0.8 - 1.2 MPa.

[0012] Preferably, the drying process of the present invention includes: first, vacuum drying at 80 - 90 °C for 2 - 4 hours with a vacuum degree ≤ -0.08 MPa; second, hot air drying at 110 - 120 °C for 1 - 2 hours with a moisture content ≤ 200 ppm.

[0013] Preferably, for the application of a polar SBS elastomer containing a glycidyl ether block in an adhesive, the components of the adhesive are 40 - 60 wt% elastomer, 20 - 30 wt% tackifying resin, 0.5 - 1 wt% antioxidant, and the balance being solvent.

[0014] Preferably, for the application of a polar SBS elastomer containing a glycidyl ether block in the blending modification of polar polymers, the addition amount when blended with PET, PA6, or PC is 5 - 20 wt%, and the blending temperature is 180 - 220 °C.

[0015] Preferably, for the UV - curable material prepared from a polar SBS elastomer containing a glycidyl ether block of the present invention, double bonds are introduced by the reaction of AGE hydroxyl groups with glycidyl methacrylate, and the dosage of the photo - initiator is 0.5 - 2 wt%.

[0016] Preferably, for the application of a polar SBS elastomer containing a glycidyl ether block in automotive sealing strips, the compression set of the sealing strip ≤ 25%, and the ozone - aging resistance grade reaches level 4 of GB / T7762 - 2014.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The hydroxyl groups formed by the ring - opening of AGE in the present invention can further react with isocyanates, acid anhydrides, or acrylate compounds, thereby enabling various functional modifications.

[0018] 2. The peel strength of the present invention against PET reaches 5.8 N / mm, and the peel strength is increased by 176% compared with traditional SBS, which is particularly suitable for the fields of high - performance adhesives and blending modification of polar materials.

[0019] 3. The melt fluidity of the elastomer of the present invention is excellent, and the melt flow index (190 °C / 5 kg) is 8.2 g / 10 min. Detailed Embodiments

[0021] The following further illustrates the present invention with reference to embodiments. The implementation manners of the present invention include but are not limited to the following embodiments.

[0022] Example 1 A preparation method of a polar SBS elastomer containing a glycidyl ether block, characterized by comprising the following steps: (1) Charge high-purity nitrogen into the reaction kettle, and add 15 kg of cyclohexane, 0.15 mol of n-butyllithium and 0.045 mol of triethylaluminum respectively, wherein the molar ratio of Al to Li is 0.3; (2) Segmented polymerization: a. The first stage: Add 2.1 kg of styrene at 40 °C and react for 30 min to form the first polystyrene segment; b. The second stage: Raise the temperature to 60 °C, add 4.5 kg of butadiene and 0.75 mol of THF, and react for 2 h; c. The third stage: Inject 0.3 kg of AGE at 70 °C and carry out a ring-opening graft reaction for 25 min; d. The fourth stage: Lower the temperature to 50 °C, add 2.1 kg of styrene as a supplement, and react for 40 min; (3) Add methanol / propylene oxide (2:1) to terminate the reaction. After steam condensation and vacuum drying at 120 °C for 90 min, a polar SBS elastomer containing a glycidyl ether block can be obtained.

[0023] Example 2 A preparation method of a polar SBS elastomer containing a glycidyl ether block, characterized by comprising the following steps: (1) Charge high-purity nitrogen into the reaction kettle, and add 15 kg of cyclohexane, 0.15 mol of n-butyllithium and 0.045 mol of triethylaluminum respectively, wherein the molar ratio of Al to Li is 0.3; (2) Segmented polymerization: a. The first stage: Add 2.1 kg of styrene at 40 °C and react for 30 min to form the first polystyrene segment; b. The second stage: Raise the temperature to 60 °C, add 4.5 kg of butadiene and 0.75 mol of THF, and react for 2 h; c. The third stage: Inject 0.6 kg of AGE at 70 °C and carry out a ring-opening graft reaction for 25 min; d. The fourth stage: Lower the temperature to 50 °C, add 2.1 kg of styrene as a supplement, and react for 40 min; (3) Add methanol / propylene oxide (2:1) to terminate the reaction. After steam condensation and vacuum drying at 120 °C for 90 min, a polar SBS elastomer containing a glycidyl ether block can be obtained.

[0024] Example 3 A preparation method of a polar SBS elastomer containing a glycidyl ether block, characterized by comprising the following steps: (1)Charge the reactor with high-purity nitrogen, and add 15 kg of cyclohexane, 0.15 mol of n-butyllithium, and 0.045 mol of triethylaluminum respectively, where the molar ratio of Al to Li is 0.3; (2)Segmented polymerization: a. The first stage: Add 2.1 kg of styrene at 40 °C and react for 30 min to form the first polystyrene segment; b. The second stage: Raise the temperature to 60 °C, add 4.5 kg of butadiene and 0.75 mol of THF, and react for 2 h; c. The third stage: Inject 0.9 kg of AGE at 70 °C and carry out a ring-opening graft reaction for 25 min; d. The fourth stage: Lower the temperature to 50 °C, add 2.1 kg of styrene as a supplement, and react for 40 min; (3)Add methanol / propylene oxide (2:1) to terminate the reaction. After steam condensation, vacuum dry at 120 °C to obtain a polar SBS elastomer containing a glycidyl ether block.

[0025] Through the comparison of the above three examples, the test results of the polar SBS elastomer of the present invention by changing the addition amount of AGE are as follows: AGE content Peeling strength (N / mm) Melt index (g / 10min) 5% 4.2 9.1 10% 5.8 8.2 15% 6.3 7.5 Example 4 An application of a polar SBS elastomer containing a glycidyl ether block in an adhesive, where the components of the adhesive are 58 wt% elastomer, 25 wt% tackifying resin, 0.5 wt% antioxidant, and the balance is solvent.

[0026] Example 5 An application of a polar SBS elastomer containing a glycidyl ether block in the blending modification of polar polymers. When the polar SBS elastomer is blended with PET, PA6 or PC, the addition amount is 15 wt%, and the blending temperature is 210 °C.

[0027] Example 6 A UV-curable material prepared from a polar SBS elastomer containing a glycidyl ether block. A double bond is introduced by reacting the hydroxyl group of AGE with glycidyl methacrylate, and the amount of the photoinitiator used is 1.2 wt%.

[0028] Example 7 An application of a polar SBS elastomer containing a glycidyl ether block in automotive sealing strips, where the compression set of the sealing strips ≤ 25%, and the ozone resistance aging grade reaches Grade 4 of GB / T7762-2014.

[0029] The above embodiments are only the preferred embodiments of the present invention and should not be used to limit the protection scope of the present invention. Any meaningless changes or polish made on the main design concept and spirit of the present invention, as long as the technical problems solved are still consistent with those of the present invention, should be included in the protection scope of the present invention.

Claims

1. A polar SBS elastomer containing a glycidyl ether block, characterized in that: -[(St)_a-(Bd)_b-(AGE)_c]-(St)_a- having a four-block structure, wherein a is the degree of polymerization of the styrene segment, a=100-200; b is the degree of polymerization of the butadiene segment, b=300-500; c is the degree of polymerization of the AGE unit, c=5-30, the AGE unit is connected to the main chain through an ether bond formed by epoxy ring opening, and the oxygen atom of the ether bond is directly connected to the carbon chain of the butadiene segment.

2. The polar SBS elastomer containing glycidyl ether blocks according to claim 2, characterized in that: The 1,4-structure content in the butadiene segment is 60-70%, and the 1,2-structure content is 30-40%; the number average molecular weight (Mn) of the elastomer is 8×10 4 -15×10 4 The melt flow index (190°C / 5kg) is 7-10g / 10min. The SAXS test of the elastomer shows that the hard segment phase spacing is 15-18nm, and the polar groups are enriched in the soft and hard segment interface region.

3. The polar SBS elastomer containing glycidyl ether blocks according to claim 2, characterized in that: The AGE unit accounts for 5-15wt% of the total weight of the monomer, and the epoxy ring opening rate is ≥90%, the molecular weight distribution index PDI is ≤1.25, and the hydroxyl content generated after the AGE unit is opened is 0.2-1.5mmol / g.

4. A method for preparing a polar SBS elastomer containing a glycidyl ether block as claimed in any one of claims 1 to 3, characterized in that The following steps are involved: (1) Under an inert atmosphere, cyclohexane is used as a solvent, and a dual initiator system is added, wherein the dual initiator is n-butyl lithium and triethyl aluminum, and the molar ratio of Al to Li is 0.2-0.5; (2) Segment aggregation: a. The first stage: polymerize styrene at 40-50°C to form the first polystyrene segment; b. The second stage: the temperature is raised to 60-70°C, butadiene is added for gradient chain extension, and THF regulator is added during this period to control the 1,4-structure content of butadiene; c. The third stage: maintaining 70-75°C, adding propylene glycidyl ether for ring-opening grafting reaction for 20-40 minutes; d. The fourth stage: cool down to 50-55°C and add styrene for end-capping; (3) Add a terminator to terminate the reaction, and obtain the product through condensation and drying steps.

5. The method of preparing a polar SBS elastomer containing a glycidyl ether block according to claim 4, characterized in that: The water content of the solvent cyclohexane in step (1) is ≤50ppm, and the total monomer concentration is 12-18wt%; In step (2) a, the addition rate of styrene is 0.5-1.5 kg / h, and the reaction pressure is 0.1-0.3 MPa; In step (2) b, the molar ratio of the THF regulator to Li⁺ is 4:1-6:1, and the gradient heating rate is 1-2°C / min; In step (2) c, AGE is added by pulse injection, with each injection amount being 10-20% of the total amount and the interval time being 3-5 minutes; The molar amount of the additional styrene in step (2) d is 80-120% of the molar amount of the first styrene stage; The terminator in step (3) is a mixture of methanol, propylene oxide and ethyl acetate in a volume ratio of 1-3:1:0.5-1.

6. The method of preparing a polar SBS elastomer containing a glycidyl ether block according to claim 4, characterized in that: The terminator is added at a temperature of 20-40°C and at a rate of 0.5-1% / min of the total mass of the system; The condensation process adopts two-stage steam injection, the first-stage steam pressure is 0.4-0.6MPa, and the second-stage steam pressure is 0.8-1.2MPa; The drying process includes: first, vacuum drying at 80-90° C. for 2-4 hours, with a vacuum degree of ≤-0.08 MPa; second, hot air drying at 110-120° C. for 1-2 hours, with a moisture content of ≤200 ppm.

7. Use of a polar SBS elastomer containing a glycidyl ether block as claimed in any one of claims 1 to 3 in an adhesive, characterized in that: The adhesive comprises 40-60wt% of an elastomer, 20-30wt% of a tackifying resin, 0.5-1wt% of an antioxidant, and the remainder of a solvent.

8. Use of a polar SBS elastomer containing a glycidyl ether block as claimed in any one of claims 1 to 3 in the blending and modification of polar polymers, characterized in that: When blended with PET, PA6 or PC, the addition amount is 5-20wt% and the blending temperature is 180-220℃.

9. A UV curable material prepared from a polar SBS elastomer containing a glycidyl ether block as claimed in any one of claims 1 to 3, characterized in that: Double bonds are introduced by reacting AGE hydroxyl groups with glycidyl methacrylate, and the amount of photoinitiator used is 0.5-2wt%.

10. Use of a polar SBS elastomer containing a glycidyl ether block as claimed in any one of claims 1 to 3 in automobile sealing strips, characterized in that: The compression permanent deformation of the sealing strip is ≤25%, and the ozone aging resistance grade reaches Grade 4 of GB / T7762-2014.