International treaties solve, are key to cooperation and are better than domestic protections.

This study examines the influence of IP treaties on the performance of international innovation collaboration using patent data. The results revealed that international IP treaties have a significant positive effect on the importance of a country in international cooperation activities. International IP treaties protect all kinds of IPRs such as patents, trademarks and copyrights, including the IP protection processes, methods and rules mutually respected by all countries. Besides, the international protection of IPRs in international IP treaties can offset the shortcomings of IPRs being protected only at home, providing an institutional guarantee for countries to conduct international innovation cooperation.

Besides, a country's integration into an international innovation environment through IP treaties can enable the country to have more partners, enhancing the country's role in the international innovation cooperation network. This study demonstrates that the impact of the IP treaty on the degree centrality is much stronger and more significant than that on the betweenness centrality inclined to reflect the cohesive role of a country in international cooperation with other countries. The existence of the weaker influence on the betweenness centrality may be related to the fact that IP treaties have made innovation cooperation between countries around the world more frequent, indirectly leading to a decreasing number of countries that do not have a cooperative relationship. These findings may remain open to alternative interpretations. First, a country's accession to IP treaties is likely to strengthen its level of intellectual property protection and help the country acquire more opportunities for international innovation cooperation. Ginarte and Park (1997) confirmed that IP treaties have contributed to the increase in the level of IP protection and regarded whether or not to join IP treaties as one of the crucial indicators for assessing the level of IP protection in a country. In countries with strong IP protection, multinational companies are more willing to choose to cooperate with companies in the form of joint ventures or legal contracts that are considered to be more conducive to promoting innovation cooperation and driving companies to find more partners compared to FDI (Cozzolino and Rothaermel, 2018). In this study, the increase in the degree centrality is essential evidence of IP treaties to promote innovation cooperation, contributing to expanding the international innovation network and accelerating technology transfer and integration among countries. Particularly, the official text of the treaty positively and significantly affected international innovation cooperation. The official text of the treaty usually describes intellectual property protection in detail, while other texts, such as regulations and agreed statements, only supplement the provisions in the official text. Thus, the official text is more effective.

Moreover, different IP treaties have distinct effects on the role of different countries in the international innovation cooperation network. As more and more countries join IP treaties, the international innovation pattern dominated by developed countries has been gradually changed because the degree centrality of developing countries has been significantly improved relative to developed countries. Although developed countries are still the main actors in international innovation activities, developing countries are becoming more and more vital to other countries in the international innovation cooperation network, and IP treaties have played a significant role in changing the international environment for innovation and cooperation. The accession of a country to an IP treaty itself demonstrates the country's willingness to actively participate in international innovation activities. Many rules contained in IP treaties enable innovative cooperation between countries (such as developed countries versus developed countries, developed countries versus developing countries and developing countries versus developing countries) to be legally protected. Previous studies indicate that companies may adjust the way of international innovation cooperation according to the intensity of IP protection (Leahy and Naghavi, 2010; Luo, 2001; Li and Xie, 2016; Hagedoorn et al., 2005). In this study, the impact of developed countries is weaker than that of developing countries, even though FDI in developed and developing countries has no significant impact on international innovation cooperation under the influence of the IP treaty. Apparently, under the influence of the IP treaty, FDI and R&D activities have little impact on the international innovation cooperation of developed countries with stable IP protection. However, both IP treaty and R&D expenditure have had a positive and significant impact on international innovation cooperation for developing countries whose IP protection needs to be improved. Therefore, joining the IP treaty has practical significance for developing countries to strengthen intellectual property protection and optimize their own international innovation cooperation methods.