Highly branched asymmetric styrene-butadiene-styrene copolymer and its preparation method and use in shoe soles

Abstract

The application discloses a kind of highly branched asymmetric styrene-butadiene-styrene copolymer and its preparation method and application in shoe sole.The highly branched asymmetric styrene-butadiene-styrene copolymer of the application has three-dimensional network structure, which is asymmetric styrene-butadiene-styrene copolymer as arm, divinylbenzene as coupling core point, with high degree of branching, good oiling performance, good processing performance and other characteristics, blending granulation with polystyrene, processing operating oil and the like, without vulcanization, shoe sole product can be obtained by injection molding or compression molding process, simple and environment-friendly process, DIN abrasion of product is less than 70mm 3 , dry and wet skid friction coefficient is greater than 0.8, and can be widely applied in high wear-resistant, high non-slip shoe sole.

Description

Technical Field

[0001] This invention discloses a highly branched asymmetric styrene-butadiene-styrene copolymer (b-SBS) and its preparation method, and also relates to the application of the highly branched asymmetric styrene-butadiene-styrene copolymer in shoe sole materials, belonging to the field of polymer materials technology. Background Technology

[0002] Styrene-butadiene-styrene copolymer (SBS) is one of the main types of styrene-based thermoplastic elastomers (TPS), with applications primarily including asphalt modification, plastic modification, and footwear manufacturing. Footwear is the largest consumer of SBS, mainly due to its advantages over vulcanized rubber and PVC in terms of cost, processing technology, recycling, and low-temperature performance. As people's needs for a better life continue to grow, higher demands are being placed on the performance of footwear, with abrasion resistance and slip resistance being the most basic requirements for shoe soles.

[0003] Traditional SBS structures include linear SBS and low-branched star-shaped SBS. The wear-resistant and slip-resistant properties of soles made with these materials no longer meet higher requirements and are gradually being replaced by vulcanized rubber, which is more expensive, has a stronger odor, and requires more complex processing. For example, Chinese patent CN 114874514 A discloses a slip-resistant and wear-resistant rubber for shoe soles based on polybutadiene and its preparation method. The rubber, by weight, comprises the following components: 60 parts polybutadiene rubber, 32-48 parts thermoplastic elastomer SBS, 26-35 parts modified boron-magnesium stone composite particles, 1.5-3.6 parts terpene phenol resin, 0.2-0.8 parts silane coupling agent, 1.2-1.8 parts antioxidant, 2.3-4.6 parts sulfur, and 1.1-1.6 parts accelerator. The resulting rubber not only has wear-resistant and slip-resistant properties but also is lightweight and highly elastic. Furthermore, its aging resistance has been significantly improved.

[0004] Currently, it is necessary to innovate the existing SBS sole material and replace vulcanized rubber, which is costly, has a strong odor, and requires complex processing. This is an inevitable trend. Summary of the Invention

[0005] In view of the fact that existing wear-resistant and anti-slip shoe sole materials mainly use vulcanized rubber, which has drawbacks such as high cost, strong odor, and complex processing technology, the first objective of this invention is to provide a highly branched asymmetric styrene-butadiene-styrene copolymer (b-SBS). This b-SBS has a special three-dimensional network structure with high branching degree and branching efficiency, which not only provides excellent wear resistance and anti-slip properties, but also provides good oil filling performance, high oil filling ratio, and excellent oil locking performance. At the same time, it has asymmetric styrene-butadiene-styrene copolymer arms, which can endow b-SBS with excellent processing performance and ensure that the subsequent composition has good processing performance.

[0006] The second objective of this invention is to provide a method for preparing highly branched asymmetric styrene-butadiene-styrene copolymer. This method is simple, can use the mature SBS process, is easy to operate, has low cost, and is conducive to industrial production.

[0007] The third objective of this invention is to provide an application of a highly branched asymmetric styrene-butadiene-styrene copolymer, which, when applied to shoe sole materials, can produce shoe sole materials with a high coefficient of friction and low DIN wear.

[0008] The fourth objective of this invention is to provide a method for preparing shoe soles. Based on the excellent oil-filling and processing properties of highly branched asymmetric styrene-butadiene-styrene copolymer, this method involves mixing it with processing oil and polystyrene. Without vulcanization, the sole can be directly obtained through injection molding or compression molding. The process is simple and environmentally friendly, and the resulting shoe sole has a DIN abrasion wear of less than 70mm. 3 With a dry and wet friction coefficient greater than 0.8, it has broad application prospects.

[0009] To achieve the above-mentioned technical objectives, the present invention provides a highly branched asymmetric styrene-butadiene-styrene copolymer having the following molecular structural formula:

[0010]

[0011] in,

[0012] SBS is an asymmetric styrene-butadiene-styrene copolymer arm;

[0013] The divinylbenzene unit is the coupling core point;

[0014] m = 1~2, n = 1~2;

[0015] M represents a terminator residue.

[0016] The highly branched asymmetric styrene-butadiene-styrene copolymer (b-SBS) provided by this invention uses divinylbenzene units as coupling cores and has high branching efficiency, with a branching degree of 4-7, giving it a three-dimensional network structure. Furthermore, the polymer arms in b-SBS are triblock SBS copolymers. Based on the special molecular structure of b-SBS, it not only possesses excellent wear resistance and anti-slip properties but also provides good oil-filling performance, with a high oil-filling ratio and excellent oil-locking properties. In addition, the polymer arms in b-SBS are asymmetric triblock SBS copolymers, with the polystyrene chain in the third block having a different length than that in the first block. This design endows b-SBS with excellent processing properties, ensuring good processing performance in subsequent compositions.

[0017] As a preferred embodiment, the molecular structure of the asymmetric styrene-butadiene-styrene copolymer arm is as follows:

[0018]

[0019] Wherein, S1 = 433–1875, S2 = 144–425, a = 2444–7583, and b = 305–1517. The different lengths of the polystyrene chains at both ends of the arms of the asymmetric styrene-butadiene-styrene copolymer can endow b-SBS with excellent processing properties.

[0020] As a preferred option, b / (a+b) = 0.1 to 0.2. The soft segment structure in the asymmetric styrene-butadiene-styrene copolymer arm at this preferred ratio is similar to the molecular structure of the processing oil, which can improve compatibility with the processing oil.

[0021] As a preferred embodiment, the degree of branching of the highly branched asymmetric styrene-butadiene-styrene copolymer is in the range of 4.0 to 7.0.

[0022] As a preferred embodiment, the number-average molecular weight of the highly branched asymmetric styrene-butadiene-styrene copolymer is between 300,000 and 650,000. If the molecular weight is too low, the improvement in the polymer's wear resistance is not significant; if the molecular weight is too high, the polymer's processability is too poor, limiting its processing applications.

[0023] This invention also provides a method for synthesizing highly branched asymmetric styrene-butadiene-styrene copolymer. In an anionic polymerization system, styrene and an initiator are first added to initiate a first-stage polymerization, then butadiene is added for a second-stage polymerization, then styrene is added for a third-stage polymerization, and finally divinylbenzene is added for a coupling reaction. After the coupling reaction is completed, the reaction is terminated.

[0024] As a preferred embodiment, the conditions for the polymerization are: a temperature of 60–80°C and a time of 25–35 min.

[0025] As a preferred embodiment, the conditions for the two-stage polymerization are: a temperature of 60–80°C and a time of 40–60 min.

[0026] As a preferred embodiment, the conditions for the three-stage polymerization are: a temperature of 60–80°C and a time of 25–35 min.

[0027] As a preferred embodiment, the coupling reaction conditions are: a temperature of 60–80°C and a time of 25–35 min.

[0028] As a preferred embodiment, the anionic polymerization system contains cyclohexane and / or n-hexane solvents. The amount of solvent added is conventional, generally ensuring that the mass percentage content of the polymerizable monomer is around 15%.

[0029] As a preferred embodiment, the anionic polymerization system contains a tetrahydrofuran activator, the concentration of which in the solvent is 50–200 ppm. Tetrahydrofuran, as an activator, can adjust the 1,2-structure content of butadiene; generally, as its proportion increases, the proportion of the 1,2-structure of butadiene will increase appropriately.

[0030] As a preferred embodiment, the initiator is butyllithium and / or sec-butyllithium. The most common initiator is n-butyllithium. Its dosage is 2–6 mmol / 100g polymer.

[0031] As a preferred embodiment, the terminator is a phenolic compound, specifically p-methylphenol. Its dosage is 2–6 mmol / 100g polymer.

[0032] This invention also provides an application of a highly branched asymmetric styrene-butadiene-styrene copolymer in shoe sole materials. The highly branched asymmetric styrene-butadiene-styrene copolymer of this invention is a highly branched polymer with a helical structure and a high molecular weight. It exhibits good oil-filling properties and can still achieve excellent physical strength even at high oil-filling ratios, with physical properties comparable to vulcanized rubber.

[0033] As a preferred embodiment, the sole material comprises a highly branched asymmetric styrene-butadiene-styrene copolymer, processing oil, and polystyrene. The introduction of an appropriate amount of polystyrene can maintain good dimensional stability in the sole product.

[0034] As a preferred embodiment, the sole material comprises the following components in parts by weight: 50-80 parts of highly branched asymmetric styrene-butadiene-styrene copolymer; 15-35 parts of processing oil; and 5-20 parts of polystyrene. If the proportion of highly branched asymmetric styrene-butadiene-styrene copolymer is too high and the proportion of polystyrene is too low, the dimensional stability of the sole product is poor. Conversely, if the proportion of highly branched asymmetric styrene-butadiene-styrene copolymer is too low and the proportion of polystyrene is too high, the hardness of the sole product is too high, affecting comfort. The most preferred sole material comprises the following components in parts by weight: 70 parts of highly branched asymmetric styrene-butadiene-styrene copolymer; 20 parts of processing oil; and 10 parts of polystyrene.

[0035] The processing method for the sole material of the present invention is a conventional mixing and granulation process: highly branched asymmetric styrene-butadiene-styrene copolymer, processing oil (such as naphthenic oil 4010, naphthenic oil 4006, No. 26 white oil, etc.) and polystyrene are mixed evenly in a high-speed mixer according to a certain ratio, and then extruded and granulated in a twin-screw extruder to obtain the composite granules. The processing temperature of the twin-screw extruder is 170-200°C, preferably 190°C.

[0036] The present invention also provides a method for preparing a shoe sole, which involves blending the highly branched asymmetric styrene-butadiene-styrene copolymer, processing oil and polystyrene, and then molding them by compression molding or injection molding.

[0037] As a preferred embodiment, the molding temperature is 175–185°C.

[0038] As a preferred embodiment, the injection molding temperature is 185–195°C.

[0039] Compared with existing technologies, the beneficial technical effects of the present invention are as follows:

[0040] The highly branched asymmetric styrene-butadiene-styrene copolymer provided by this invention has, on the one hand, a special three-dimensional network structure with high branching degree and branching efficiency, which not only provides excellent wear resistance and anti-slip properties, but also good oil-filling properties, with a high oil-filling ratio and excellent oil-locking performance; on the other hand, it uses an asymmetric triblock structure SBS for coupling branching reaction, and the polystyrene chain of the third block is not the same length as the polypropylene chain of the first block. This design can endow the polymer with excellent processing properties and ensure that the subsequent composition has good processing properties.

[0041] The hot abrasion resistance (60°C) of the molded or injection-molded articles of the highly branched asymmetric styrene-butadiene-styrene copolymer, processing oil and polystyrene provided by this invention is comparable to the abrasion resistance at room temperature, a property that other SBS polymers cannot achieve.

[0042] The shoe sole material comprising highly branched asymmetric styrene-butadiene-styrene copolymer provided by this invention can be directly molded into shoe sole products by compression molding or injection molding without vulcanization, and the prepared shoe sole mass spectrometry shows a DIN abrasion of less than 70 mm. 3 With a coefficient of friction greater than 0.8 in both dry and wet conditions, it can be applied to highly wear-resistant and highly slip-resistant shoe soles, exhibiting excellent overall performance and being recyclable.

[0043] The method for preparing highly branched asymmetric styrene-butadiene-styrene copolymer provided by this invention is simple, can use the mature SBS process, is easy to operate, has low cost, and is conducive to industrial production. Attached Figure Description

[0044] Figure 1 The GPC spectrum of the highly branched asymmetric SBS polymer prepared in Example 1.

[0045] Figure 2 The 1H NMR spectrum of the highly branched asymmetric SBS polymer prepared in Example 1 Detailed Implementation

[0046] To make the objectives, features, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in more detail below with reference to the examples. However, the scope of protection of the claims of the present invention is not limited to the specific embodiments disclosed below.

[0047] The test methods and standards used for highly branched asymmetric SBS polymers and shoe sole materials in the following examples are as follows:

[0048] GPC testing methods are in accordance with ISO 13885-1:2020.

[0049] The DIN abrasion test method is in accordance with GB / T3903.2-2017.

[0050] The test method for the anti-slip friction coefficient shall be in accordance with GB3903.6-2017.

[0051] Example 1

[0052] Step 1: Synthesis of highly branched asymmetric SBS polymers:

[0053] The 5L polymerization reactor was purged with high-purity nitrogen to remove impurities. 3000ml of solvent (THF content in the solvent was 115ppm) was added, and stirring was started. The temperature of the polymerization reactor was raised to about 65℃. 82ml of styrene was added, followed by 14ml of butyllithium (concentration of 0.25mol / L) to initiate the reaction. After 30min, 315ml of butadiene was added and reacted for 50min. In the third stage, 33ml of styrene was added and reacted at 65℃ for 30min. Finally, 4ml of divinylbenzene was added and reacted for 30min, with the reaction temperature controlled at 65℃. Finally, 4ml of terminating agent 2.6.4 was added to terminate the reaction, with a reaction time of 25min.

[0054] The polymer GPC was sampled and tested. The GPC test results are as follows:

[0055]

[0056] The GPC spectrum is shown in the attached figure.

[0057] Step Two: Composition Preparation and Performance Testing

[0058] Take 2500ml of the adhesive solution obtained in step one, add 62.5g of naphthenic oil No. 4010 (oil filling ratio of 20%), 3‰ of antioxidant 1076 and 3‰ of antioxidant 168, and stir at 60℃ for 30min. Desolventize the oil-filled adhesive solution by steam condensation to obtain adhesive blocks. Dry and pulverize the adhesive blocks, weigh 200g of dry oil-filled adhesive (containing 160g of polymer and 40g of white oil), and 20g of polystyrene. Mix them evenly in a small high-speed mixer, and extrude and granulate them on a small screw extruder at 180℃. Mold the obtained granules onto a flat vulcanizing machine to prepare 2cm thick sheets at 175℃ for 25min and a pressure of 10MPa. Cold press at 10MPa for 10min. After 24h, test the DIN abrasion and anti-slip coefficient of the sheets according to relevant standards.

[0059] Example 2

[0060] The amount of butyllithium in step 1 was increased to 18 mL, while other conditions remained unchanged. The GPC test results of the resulting polymer are as follows:

[0061]

[0062] Step 2 is the same as in Example 1.

[0063] Example 3

[0064] The amount of butyllithium in step 1 was increased to 22 mL, while other conditions remained unchanged. The GPC test results of the resulting polymer are as follows:

[0065]

[0066] Step 2 is the same as in Example 1.

[0067] Example 4

[0068] The amount of butyllithium in step 1 was reduced to 12 mL, while other conditions remained unchanged. The GPC test results of the resulting polymer are as follows:

[0069]

[0070] Step 2 is the same as in Example 1.

[0071] Example 5

[0072] The amount of butyllithium in step 1 was reduced to 10 mL, while other conditions remained unchanged. The GPC test results of the resulting polymer are as follows:

[0073]

[0074] Step 2 is the same as in Example 1.

[0075] Example 6

[0076] The amount of divinylbenzene in step 1 was increased to 6 mL, while other conditions remained unchanged. The GPC test results of the resulting polymer are as follows:

[0077]

[0078]

[0079] Step 2 is the same as in Example 1.

[0080] Example 7

[0081] The amount of divinylbenzene in step 1 was reduced to 2.5 mL, while other conditions remained unchanged. The GPC test results of the resulting polymer are as follows:

[0082]

[0083] Step 2 is the same as in Example 1.

[0084] Example 8

[0085] In step 1, the amount of styrene was changed to 65 mL, and the amount of butadiene was changed to 339 mL, while other conditions remained unchanged. The GPC test results of the resulting polymer are as follows:

[0086]

[0087] Step 2 is the same as in Example 1.

[0088] Example 9

[0089] In step 1, the amount of styrene was changed to 49 mL, and the amount of butadiene was changed to 363 mL, while other conditions remained unchanged. The GPC test results of the resulting polymer are as follows:

[0090]

[0091]

[0092] Step 2 is the same as in Example 1.

[0093] Example 10

[0094] In step 1, the amount of styrene was changed to 98 mL, and the amount of butadiene was changed to 290 mL, while other conditions remained unchanged. The GPC test results of the resulting polymer are as follows:

[0095]

[0096] Step 2 is the same as in Example 1.

[0097] Example 11

[0098] The amount of butadiene in step 1 was changed to 339 mL, and the amount of styrene in step 1 was changed to 16 mL, while other conditions remained unchanged. The GPC test results of the resulting polymer are as follows:

[0099]

[0100] Step 2 is the same as in Example 1.

[0101] Example 12

[0102] The amount of butadiene in step 1 was changed to 266 mL, and the amount of styrene in step 1 was changed to 65 mL, while other conditions remained unchanged. The GPC test results of the resulting polymer are as follows:

[0103]

[0104]

[0105] Step 2 is the same as in Example 1.

[0106] Example 13

[0107] The steps are the same as in Example 1.

[0108] In step two, the oil filling rate becomes 25%, while other conditions remain unchanged.

[0109] Example 14

[0110] The steps are the same as in Example 1.

[0111] In step two, the oil filling rate is changed to 30%, while other conditions remain unchanged.

[0112] Example 15

[0113] The steps are the same as in Example 1.

[0114] In step two, the oil filling rate is changed to 15%, while other conditions remain unchanged.

[0115] Example 16

[0116] The steps are the same as in Example 1.

[0117] In step two, the amount of polystyrene used is changed to 10g, while other conditions remain unchanged.

[0118] Example 17

[0119] The steps are the same as in Example 1.

[0120] In step two, the amount of polystyrene used is changed to 40g, while other conditions remain unchanged.

[0121] Comparative Example 1

[0122] In step 1, the amount of styrene in the first stage was changed to 65 mL, the amount of butadiene in the second stage to 194 mL, and the amount of styrene in the third stage to 65 mL. Silicon tetrachloride was used as the coupling agent, and other conditions remained unchanged. The GPC results of the resulting polymer are as follows:

[0123]

[0124] Step two is the same as in Example two.

[0125] Comparative Example 2

[0126] The polymer in the examples was replaced with commercially available SBSYH-791 (linear symmetrical structure). The composition formulation and dosage were: 200g SBSYH-791, 50g naphthenic oil No. 4010, and 20g polystyrene.

[0127] Comparative Example 3

[0128] The polymer in the examples was replaced with commercially available SBSYH-185 (branching degree 2.9). The composition formulation and dosage were: 200g SBSYH-185, 50g naphthenic oil No. 4010, and 20g polystyrene.

[0129] The performance test data of the above embodiments and comparative examples are shown in the table below:

[0130]

[0131]

Claims

1. A highly branched asymmetric styrene-butadiene-styrene copolymer, characterized in that: It has the following molecular structural formula: ； in, SBS is an asymmetric styrene-butadiene-styrene copolymer arm; The divinylbenzene unit is the coupling core point; m = 1 ~ 2, n = 1 ~ 2; The degree of branching of the highly branched asymmetric styrene-butadiene-styrene copolymer is in the range of 4.0 to 7.0; M is a terminator residue.

2. The highly branched asymmetric styrene-butadiene-styrene copolymer according to claim 1, characterized in that: The molecular structural formula of the asymmetric styrene-butadiene-styrene copolymer arm is as follows: ； Wherein, S1=433~1875, S2=144~425, a=2444~7583, b=305~1517.

3. The highly branched asymmetric styrene-butadiene-styrene copolymer according to claim 2, characterized in that: b / (a+b) = 0.1~0.

2.

4. A highly branched asymmetric styrene-butadiene-styrene copolymer according to any one of claims 1 to 3, characterized in that: The number-average molecular weight of the highly branched asymmetric styrene-butadiene-styrene copolymer is between 300,000 and 650,000.

5. A method for synthesizing a highly branched asymmetric styrene-butadiene-styrene copolymer according to any one of claims 1 to 4, characterized in that: In the anionic polymerization system, styrene and an initiator are first added to initiate a first-stage polymerization, then butadiene is added for a second-stage polymerization, then styrene is added for a third-stage polymerization, and finally divinylbenzene is added for a coupling reaction. After the coupling reaction is completed, the reaction is terminated.

6. The method for synthesizing a highly branched asymmetric styrene-butadiene-styrene copolymer according to claim 5, characterized in that: The conditions for the polymerization of the first stage are: temperature of 60~80℃ and time of 25~35min; The conditions for the two-stage polymerization are: temperature 60~80℃, time 40~60min; The conditions for the three-stage polymerization are: temperature 60~80℃, time 25~35min; The conditions for the coupling reaction are: temperature 60~80℃, time 25~35min.

7. The method for synthesizing a highly branched asymmetric styrene-butadiene-styrene copolymer according to claim 5, characterized in that: The anionic polymerization system contains cyclohexane and / or n-hexane solvents; The anionic polymerization system contains a tetrahydrofuran activator, and the concentration of the tetrahydrofuran activator in the solvent is 50~200ppm.

8. The method for synthesizing a highly branched asymmetric styrene-butadiene-styrene copolymer according to claim 5, characterized in that: The initiator is butyllithium and / or sec-butyllithium; The terminator is p-methylphenol.

9. The application of the highly branched asymmetric styrene-butadiene-styrene copolymer according to any one of claims 1 to 4, characterized in that: Used in shoe sole materials.

10. The application of a highly branched asymmetric styrene-butadiene-styrene copolymer according to claim 9, characterized in that: The sole material includes highly branched asymmetric styrene-butadiene-styrene copolymer, processing oil, and polystyrene.

11. The application of a highly branched asymmetric styrene-butadiene-styrene copolymer according to claim 9 or 10, characterized in that: The sole material comprises the following components in parts by weight: 50-80 parts of highly branched asymmetric styrene-butadiene-styrene copolymer; 15-35 parts of processing oil; 5-20 parts of polystyrene.

12. A method for preparing a shoe sole, characterized in that: The highly branched asymmetric styrene-butadiene-styrene copolymer according to any one of claims 1 to 4, processing oil, and polystyrene are blended and then molded by compression molding or injection molding.

13. The method for preparing a shoe sole according to claim 12, characterized in that: The molding temperature is 175~185℃; The injection molding temperature is 185~195℃.

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