Establishing a cooperative relationship with chemical wholesalers involves several steps and strategies. Here are some key points:

1. Finding the Right Supplier:
- Conduct market research and seek references from peers to find a supplier that matches your business needs. You can find suitable suppliers by attending industry trade shows, searching online directories, and networking with other wholesalers.

2. Building Trust:
- In the early stages of cooperation, build a relationship of trust with the supplier. This can be done through face-to-face meetings and phone calls to understand the supplier's product quality, delivery time, after-sales service, and to share your business philosophy and market demands.

3. Signing Contracts:
- To ensure stability and control in the cooperative relationship, sign a formal contract with the supplier. The contract should specify the rights and obligations of both parties, including product quality standards, delivery times, pricing, payment terms, and after-sales service. A well-drafted contract can reduce risks and disputes in the cooperation process.

4. Establishing a Supplier Evaluation System:
- Create a supplier evaluation system to regularly assess the supplier's performance. The evaluation indicators may include product quality, on-time delivery rate, and after-sales service quality. Based on the evaluation results, communicate with the supplier to jointly develop improvement measures and enhance cooperation efficiency and quality.

5. Co-developing New Products:
- Collaborate with suppliers to develop new products that meet market demands and consumer preferences. This can be achieved through market research, product design, and technological upgrades to develop competitive new products, thereby promoting the business development of both parties.

6. Providing Quality Customer Service:
- Commit to providing quality customer service to meet customer needs and maintain good customer relationships. This includes promptly responding to customer inquiries and complaints, providing accurate product information, ensuring timely delivery, and offering flexible after-sales service.

7. Establishing Long-Term Relationships:
- Build long-term relationships with suppliers and customers. This can be achieved through regular meetings and communications, joint participation in market activities, and conducting market research together. Long-term relationships increase trust and interdependence, thereby improving the effectiveness of cooperation.

8. Maintaining Communication and Transparency:
- Establish transparent, timely, and effective communication channels with suppliers to stay informed about product information, price changes, delivery times, and other important information. Also, promptly share market demands and customer feedback with suppliers so they can adjust production and supply plans.

By following these methods, you can establish a stable and mutually beneficial cooperative relationship with chemical wholesalers.