In the manufacturing of wheels using overmolding techniques—where a soft TPU (thermoplastic polyurethane) outer layer is bonded to a harder substrate like PP (polypropylene) or nylon—engineers often face a critical challenge: the TPU may fail to properly adhere or fully encapsulate the harder material, leading to defects and reduced product durability. One effective method to overcome this is the two-shot injection molding process, where the TPU outer layer is molded first, followed by injecting the hard plastic (PP or nylon) into it. This approach relies on high-temperature bonding to create a secure, integrated part. Let’s explore why this issue occurs and how to implement this solution successfully. Common Causes of Overmolding Failure When TPU is overmolded onto PP or nylon, several factors can lead to poor encapsulation or adhesion: Material Incompatibility: TPU, PP, and nylon have different chemical polarities and surface energies, making natural adhesion difficult. Insufficient Melt Temperature: If the hard plastic substrate is not hot enough when the TPU is injected, the materials won't fuse properly. Shrinkage Mismatch: Different cooling and shrinkage rates can cause the TPU to pull away from the rigid core. Mold Design Flaws: Inadequate venting, gate placement, or insufficient injection pressure can prevent complete filling and wrapping. The Two-Shot Molding Solution: TPU First, Then Hard Plastic The traditional method injects the hard material first, then overmolds TPU onto it. Reversing this sequence—molding the TPU outer shell first, then injecting PP or nylon inside it—can solve many encapsulation problems. Here's how and why it works: Process Breakdown: Step 1: The TPU is injected to form the flexible outer wheel (tread, sidewalls). Step 2: While the TPU is still very hot and within its processing temperature window, the rigid plastic (PP/nylon) is injected into its core or designated cavity. Step 3: At this high interface temperature, the incoming melt of the hard plastic slightly remelts the inner surface of the TPU, allowing the materials to interdiffuse and mechanically lock together at the molecular level. Key Advantages of This Method: Superior Mechanical Lock: The high-temperature injection of the hard plastic creates a strong fusion bond as it melts into the TPU's inner layer. Better Encapsulation: The TPU outer shell acts as a defined mold cavity for the hard core, ensuring complete containment and eliminating flow fronts that cause incomplete wraps. Reduced Stress: Since the TPU cools and shrinks around the already-solidified hard core (which cools last), residual stresses are minimized, improving dimensional stability. Critical Parameters for Success To implement this method effectively, precise control of process parameters is non-negotiable: Temperature Control: The interface temperature is the most critical factor. The inner surface of the TPU must be above its softening point when the hard plastic is injected. This o...

We are thrilled to announce that KUNSUN POLYMER MATERIAL (FUJIAN) CO., LTD. successfully participated in the 28th Wenzhou International Leather, Shoe Materials, and Shoe Machinery Exhibition, held from August 22nd to 24th, 2025, at the Wenzhou International Convention and Exhibition Center. It was an incredible platform to showcase our innovative TPU shoe material solutions and connect with industry professionals from around the globe. A Major Attraction: Our TPU Shoe Materials Our booth became a focal point of interest, drawing numerous domestic and international clients and professionals specializing in shoe materials. Visitors were particularly captivated by our high-performance TPU samples, which highlight the versatility, durability, and aesthetic appeal of our products. From enhanced elasticity and abrasion resistance to eco-friendly recyclability and stunning transparency, our TPU materials are engineered to meet the evolving demands of the modern footwear industry. Whether for athletic sneakers, fashion-forward casual wear, or rugged outdoor boots, KUNSUN TPU offers cutting-edge solutions that combine performance with sustainability. Learning and Growing Together Beyond promoting our brand and products, this exhibition was also a profound learning experience. We had the privilege of engaging with potential clients of different ages, backgrounds, and professional experiences. Each conversation provided us with new insights into market needs, design trends, and technical challenges—helping us grow not only as a company but as innovators committed to serving the global footwear community. We are inspired by the feedback we received and energized by the opportunities to collaborate with partners who value quality, creativity, and sustainability.

(July 10-13, 2025) – From July 10th to 13th, the 22nd Asia-Pacific Plastics & Rubber Exhibition was grandly held at the Qingdao World Expo City International Convention and Exhibition Center. KUNSUN POLYMER MATERIAL（FUJIAN）CO., LTD., an industry pioneer with over 30 years of dedicated focus on TPU R&D and manufacturing, made a grand appearance at Booth S3C195. Showcasing its renowned brand Koslen® and innovative achievements, the company became a focal point in the TPU sector at this year's exhibition, leveraging its profound technical expertise and cutting-edge new product portfolio. The KUNSUN booth experienced a continuous flow of visitors and sustained surge in popularity. Professionals and partners from diverse fields including footwear materials, pipes, medical products, wearable electronics, wheels, automotive parts, injection molding, and modification stopped to explore the rich array of application samples and core material exhibits. They engaged in in-depth discussions and enthusiastic negotiations with the KUNSUN technical team. Visitors gained an immersive experience of the exceptional performance and broad applicability of Koslen® TPU materials, seeking new opportunities for win-win collaboration. With thirty years of deep cultivation in the TPU field, KUNSUN Polymer has consistently focused on technological innovation and quality enhancement. The Koslen® brand has earned widespread trust from global customers through its superior physical and mechanical properties, processing stability, and eco-friendly characteristics, successfully penetrating numerous critical application scenarios. At this exhibition, Kunsheng Polymer powerfully launched two innovative product lines: Aliphatic TPU Series: Delivers an ideal solution for fields demanding stringent color stability and appearance. SCF (Supercritical Foaming) Dedicated TPU Series for Micro/Macro Foaming: Tailor-made for advanced supercritical physical foaming processes, this series overcomes technical barriers. It empowers customers to achieve large-scale, stable production of high-performance, lightweight foamed products (like premium sports shoe midsoles, lightweight cushioning materials), pushing the boundaries of performance.

April 18, 2025-Shenzhen, China KUNSUN Polymer Material (Fujian) Co., Ltd., a leading innovator in thermoplastic polyurethane (TPU) solutions, made a significant impact at CHINAPLAS 2025 (Booth 17M61), Asia’s premier plastics and rubber trade fair. The company highlighted its cutting-edge KOSLEN® TPU portfolio, with a special focus on its newly developed aliphatic TPU series tailored for advanced foaming technologies, drawing widespread attention from global industry professionals.   Star of the Show: Aliphatic TPU for Next-Gen Applications The spotlight at KUNSUN’s booth shone on its aliphatic TPU solutions, engineered for high-performance applications such as:     Supercritical SCF (Supercritical Fluid Foaming): Enabling ultra-lightweight, energy-absorbing components for automotive interiors and sports equipment.   Microcellular Foaming & Injection Molding Foaming: Delivering precision-engineered foamed parts with exceptional strength-to-weight ratios for industrial and consumer goods.   E-TPU & TPU Foam: Revolutionizing footwear midsoles, protective packaging, and vibration-damping materials through customizable cell structures.   These innovations align with global trends toward sustainability and lightweight design, offering recyclability and reduced material consumption without compromising durability.   Global Engagement: Bridging Expertise with Market Needs TheKUNSUN booth attracted a steady stream of visitors, including:   International Brands & Manufacturers: Representatives from automotive, footwear, and electronics sectors explored collaborations for lightweighting and eco-friendly material substitution.   Technical Partners: Existing and new clients brought specific case studies seeking tailored TPU solutions, particularly for replacing PVC, rubber, or rigid plastics.   Industry Experts: Engineers and R&D teams engaged in deep-dive discussions on optimizing foaming parameters and co-developing application-specific grades.   "The overwhelming interest in our aliphatic TPU series validates our R&D focus on solving real-world challenges,"saidBruce,R&D Director at KUNSUN."From sustainable packaging to electric vehicle components, we’re empowering industries to innovate with materials that perform and protect the planet."   Driving the Future of TPU As a National Specialized“Little Giant” Enterprise and Fujian Province High-Tech Innovator,KUNSUN continues to invest in advanced TPU technologies. The company plans to expand its collaboration network post-CHINAPLAS 2025, offering technical workshops and co-development programs to accelerate product commercialization.

[Shenzhen, China - April 15-18, 2025] KUNSUN POLYMER MATERIAL（FUJIAN）CO., LTD, a leading manufacturer of polyurethane materials, is pleased to announce its participation in Chinaplas 2025 (The 37th International Exhibition on Plastics and Rubber Industries). The exhibition will be held from April 15-18, 2025 at the Shenzhen World Exhibition & Convention Center (Bao'an New Venue). KUNSUN will showcase its innovative TPU (Thermoplastic Polyurethane) and groundbreaking Supercritical foam(SCF) material solutions. KUNSUN will present its revolutionary supercritical foaming process, which enables microcellular foaming of TPU materials. This technology significantly enhances lightweight properties and cushioning performance while maintaining excellent mechanical strength and resilience. Key applications include: Footwear: Lightweight and elastic midsole solutions,Automotive: NVH (Noise, Vibration, and Harshness) damping materials,Sporting goods: Sports mats and protective gear,Packaging: High-cushion protective materials. Warm Invitation to Industry Peers KUNSUN cordially invites global customers, partners, and industry experts to visit our booth (Booth No.:17M61). Through live demonstrations, sample displays, and technical exchanges, we will comprehensively showcase KUNSUN's innovation capabilities. Exhibition Information Exhibition Name: Chinaplas 2025 Date: April 15-18, 2025 Venue: Shenzhen World Exhibition & Convention Center (Bao'an New Venue) KUNSUN Booth No.:17M61 Contact Us For more information or to schedule a meeting, please contact: Email:KOSLEN@163.com Website: www.tpupolymer.com We look forward to meeting you in Shenzhen to create the future of thermoplastic polyurethane(TPU resin)materials together!

KUNSUN POLYMER MATERIAL（FUJIAN）CO., LTD., a leading innovator in thermoplastic polyurethane (TPU) materials, successfully showcased its cutting-edge TPU solutions at the 2025 Hefei Asia-Pacific International Plastics & Rubber Industry Exhibition (March 13–16, 2025). Held at the Hefei Binhu International Convention and Exhibition Center, the event provided a global platform for industry leaders to highlight advancements in sustainable materials, smart manufacturing, and cross-sector collaboration. As a key exhibitor in the high-performance materials zone, KUNSUN attracted significant attention with its eco-friendly, high-performance TPU products tailored for automotive, electronics, footwear, and industrial applications. Key exhibits included: Aliphatic no-yellowing E-TPU Solutions:Non-yellowing with Excellent bending resistance E-TPU  designed to running shoes’ sole application Customizable TPU Formulations: Tailored hardness, transparency, and mechanical properties to meet diverse client needs. The company’s booth became a hub for technical discussions, drawing engineers, procurement managers, and sustainability officers from across Asia. Highlights included Interactive displays of TPU’s flexibility, durability, and bonding capabilities in multi-industry applications.Preliminary agreements signed with automotive suppliers and footwear electronic manufacturer seeking environmental friends plastic to traditional plastics. KUNSUN is committed to driving the plastics industry’s sustainable transformation. TPU can bridge performance and environmental responsibility. KUNSUN POLYMER MATERIAL（FUJIAN）CO., LTD., is a global leader in TPU polyurethane development and manufacturing, specializing in customizable, sustainable solutions for industries ranging from automotive to consumer goods. With ISO-certified facilities and a focus on R&D, the company empowers clients to meet evolving regulatory and performance demands. NEXT MONTH WE WILL BE IN SHENZHEN Chinaplas, welcome to visit our booth. 17M61 on 2025.4.15-18

Congratulation Our Successful Exhibition In Vietnam International Plastics & Rubber Industry Exhibition The production of plastic products in Vietnam witha growth rate of 15% each year later. Vietnam’s plastics industry has around 2,000 businesses, and 83% are located in the Ho Chi Minh City. Its plastics products having a great competitive edge for packaging, household products, and construction and engineering plastics. The Vietnam International Plastics & Rubber Industry Exhibition has been seen as the best path to enter Vietnam market, and the most beneficial way to promote products, services and machinery internationally. We exhibit the 22nd  Vietnam International Plastics & Rubber Industry Exhibition in Saigon Exhibition & Conference Center (SECC) from 16th Oct. to 20th Oct. We exhibit thelatest trends and innovations in E-TPU molding products, TPU resin, TPE resin. E-TPU molding products includeInjection Molding,Compression Molding,Extrusion Molding,Overmolding. TPU resin such as TPU specialized in production oil seal which required excellent oil resistance properties. Our display rack attracted many professional visitor. The visitor got our professional answer to their question. We also meet and communication with our old friends in Vietnam.

The 21st Asia Pacific International Plastics and Rubber Industry Exhibition the core of the Asian economy been held in Qingdao which is a dual-node city in the Asia-Pacific Free Trade Zone and the number one economic city in Shandong Province. This year there are 1,800+ Global high-quality suppliers gathered in the 12 exhibition halls covered with an exhibition area of 110,000 square meters. The 21st Asia Pacific International Plastics and Rubber Industry Exhibition is a highly anticipated event in the plastics and rubber industry. It serves as a premier platform for industry professionals, manufacturers, suppliers, and buyers to gather and exchange information, showcase innovative products and technologies, and explore new business opportunities. This exhibition aims to highlight the latest advancements in plastics and rubber manufacturing, including raw materials, machinery, equipment, molds, recycling technologies, and finished products. It attracts exhibitors and visitors from around the world, creating a dynamic and diverse environment for networking, knowledge sharing, and collaboration. Leading companies such as TPU resin factory KUNSUN POLYMER MATERIAL CO., LTD. and industry players exhibit their products, services, and solutions, providing visitors with insights into the latest trends, technologies, and innovations in the plastics and rubber sectors. KUNSUN POLYMER company showed their new aliphatic E-TPU granule and the accordingly application in their both S4C195. Sales manager Grace Lin also accepted an interview from the official host of the exhibition. She make a detail introduction of the company and the products TPU resin. It is a good chance to promotion company and brand to all the visitor by the official channel.