Thermoplastic elastomer used in waterproof hot melt adhesive and preparation method and application thereof

Abstract

The invention discloses a thermoplastic elastomer used in a waterproof hot melt adhesive as well as a preparation method and application of the thermoplastic elastomer. The thermoplastic elastomer is prepared from the following raw materials: a styrene-isoprene-styrene block copolymer, a styrene-butadiene-styrene block copolymer and dibenzoyl peroxide. The preparation method comprises the following steps: mixing the styrene-isoprene-styrene block copolymer, the styrene-butadiene-styrene block copolymer and the dibenzoyl peroxide, pouring the mixture into a high-speed mixing mill, blending for 3-8 minutes, and granulating by a double-screw extruder to obtain the thermoplastic elastomer. By controlling the shearing rate and temperature, the SIS and the SBS are crosslinked by using the benzoyl peroxide, so that the SIS and the SBS are blended and crosslinked under the action of the shearing force of a screw to form a crosslinked network, an additional compatibilizer is not needed, the chemical structure is changed compared with that of pure physical blending, and meanwhile, the process is simpler than a chemical synthesis process.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically to a thermoplastic elastomer for use in waterproof hot melt adhesives, its preparation method, and its application. Background Technology

[0002] Traditional chemical synthesis of styrene-isoprene-styrene block copolymers (SIBS) presents several significant problems. First, the process is complex, requiring multiple polymerization steps. Each step demands precise control of temperature, pressure, and other conditions; even slight deviations can affect product performance. Furthermore, purification and separation between reactions are cumbersome. Second, costs are high. The use of large quantities of chemical reagents and solvents, coupled with long reaction cycles leading to increased energy consumption and equipment depreciation, keeps production costs high. Third, the long production cycle, from raw material preparation to product output, takes several days or even weeks, impacting production efficiency and supply capacity, and reducing the company's market competitiveness.

[0003] Existing blending systems also have shortcomings. To improve polymer compatibility, compatibilizers are often added, but this introduces impurities and reduces material purity. In fields such as medicine where purity requirements are extremely high, impurities may trigger adverse reactions such as allergies and inflammation, limiting their application. Furthermore, the molecular structure and properties of compatibilizers may not match those of the matrix polymer, altering the molecular chain arrangement and crystal structure, thus affecting mechanical properties; their thermal and chemical stability may also differ, leading to decomposition or reaction at high temperatures or under specific chemical environments, resulting in decreased material performance or failure, thus limiting their application range.

[0004] Therefore, it is essential to develop novel thermoplastic elastomers for waterproof hot melt adhesives and their preparation methods. This is expected to overcome existing defects, meet the needs of various fields, especially high-requirement fields, and promote industrial development. Summary of the Invention

[0005] In view of this, the present invention provides a high-performance SIBS thermoplastic elastomer prepared through a specific physical blending process without the need for compatibilizers. This solves the problems of poor compatibility and unstable performance of existing blended materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A thermoplastic elastomer for use in waterproof hot melt adhesives comprises: 50-70 wt% styrene-isoprene-styrene block copolymer; 20-40 wt% styrene-butadiene-styrene block copolymer; and 1.5-2% benzoyl peroxide.

[0007] Another object of the present invention is to provide a method for preparing the above-mentioned thermoplastic elastomer for waterproof hot melt adhesive, characterized in that styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer and benzoyl peroxide are mixed and poured into a high-speed mixer and mixed for 3-8 minutes, and then granulated by a twin-screw extruder to obtain the thermoplastic elastomer. The twin-screw extruder temperature is 180-220°C and the screw speed is 300-500 rpm.

[0008] Another objective of this invention is to provide the application of the above-mentioned thermoplastic elastomer used in waterproof hot melt adhesives in the adhesive layer of polymer waterproof membranes, which has strong cohesion, high peel strength, and is cheaper than SIS.

[0009] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: 1. The thermoplastic elastomer provided by this invention has high elasticity, weather resistance and processing performance, and is suitable for medical devices, adhesives, sealing materials and other fields.

[0010] 2. This invention controls the shear rate and temperature, and uses benzoyl peroxide to crosslink SIS and SBS, so that SIS and SBS are crosslinked under the action of screw shear force to form a crosslinked network. No additional compatibilizer is needed, the chemical structure is changed compared with simple physical blending, and it is simpler than chemical synthesis process. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0012] Figure 1 Peel force diagram: Peel force of hot melt pressure-sensitive adhesives tested using SIBS and SIS. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] Example 1 1. Raw material preparation Select 600g (60wt%) of styrene-isoprene-styrene block copolymer (SIS), 400g (40wt%) of styrene-butadiene-styrene block copolymer (SBS), and 15g of benzoyl peroxide (BPO) (accounting for 1.5% of the total mass of SIS and SBS).

[0015] 2. Preparation process Add the above-mentioned SIS, SBS and BPO to a high-speed mixer, set the mixing speed to 800 rpm, and mix for 3 minutes until the materials are uniformly mixed; feed the mixed materials into a twin-screw extruder, set the extruder temperature to 180℃ (feeding section), 200℃ (melting section), and 220℃ (extrusion section), and the screw speed to 300 rpm. After extrusion, cooling and pelletizing, the thermoplastic elastomer granules for waterproof hot melt adhesive are obtained.

[0016] 3. Performance Testing The elastomer has a melt index of 8 g / 10 min (190℃ / 2.16 kg) and a bonding strength of 1.8 MPa with the waterproof membrane substrate. After being placed in an 80℃ oven for 72 hours, the bonding strength retention rate is 90%.

[0017] Example 2 1. Raw material preparation The following materials were selected: 800g (80wt%) of styrene-isoprene-styrene block copolymer (SIS), 200g (20wt%) of styrene-butadiene-styrene block copolymer (SBS), and 20g (2% of the total mass of SIS and SBS).

[0018] 2. Preparation process SIS, SBS and BPO were added to a high-speed mixer, and the mixing speed was set to 1000 rpm. The mixture was mixed for 8 minutes until there were no obvious particles in the material. The material was then fed into a twin-screw extruder, and the extruder temperature was set to 190℃ (feeding section), 210℃ (melting section), and 220℃ (extrusion section). The screw speed was 500 rpm. After extrusion, water cooling and pelletizing, thermoplastic elastomer granules for waterproof hot melt adhesive were obtained.

[0019] 3. Performance Testing The elastomer has a melt index of 6 g / 10 min (190℃ / 2.16 kg) and a bonding strength of 2.2 MPa with the waterproof membrane substrate. After being placed in an 80℃ oven for 72 hours, the bonding strength retention rate is 92%.

[0020] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0021] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A thermoplastic elastomer for use in waterproof hot melt adhesives, characterized in that, include: The ingredients include 60-80 wt% styrene-isoprene-styrene block copolymer, 20-40 wt% styrene-butadiene-styrene block copolymer, and benzoyl peroxide, wherein the benzoyl peroxide accounts for 1.5-2% of the total mass of the two raw materials.

2. The method for preparing the thermoplastic elastomer for waterproof hot melt adhesive as described in claim 1, characterized in that, Styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer and benzoyl peroxide are mixed and poured into a high-speed mixer and blended for 3-8 minutes. Then, the mixture is granulated by a twin-screw extruder to obtain a thermoplastic elastomer. The twin-screw extruder temperature is 180-220℃ and the screw speed is 300-500 rpm.

3. The application of the thermoplastic elastomer as described in claim 1 in the adhesive layer of a polymer waterproof membrane.

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