以长三角和珠三角两大城市群为研究对象，运用空间杜宾模型以及门槛模型，分析2010—2021年知识产权保护对城市绿色创新的驱动效应。研究发现：第一，知识产权保护对城市绿色创新的影响是持续变化的，随着知识产权保护水平提升，赋能效应转变为挤出效应且负向阻碍作用呈现出由弱到强的变化趋势，其中，珠三角城市群内知识产权保护与绿色创新呈现出更为复杂的倒“U”型关系，长三角内未出现明显的非线性演化。第二，知识产权保护的溢出效应具有显著空间异质性，其中，珠三角城市群内本地知识产权保护对毗邻城市绿色创新发挥赋能效应，而长三角城市群内则呈现为挤出效应。第三，知识产权保护有利于城市绿色创新质量提升，即在严格的知识产权保护下城市更倾向于进行实质性创新而非策略性创新。作用机制检验结果表明，知识产权保护水平提高能促进研发人员及研发资金投入，在既有创新活动基础上提升城市绿色创新能力。

The urban agglomerations of the Yangtze River Delta and the Pearl River Delta are the power sources and growth poles of regional economic development. Their green innovation strategies play a crucial role in driving the surrounding areas. Among them, the economic strength and innovative elements of the two urban agglomerations are concentrated, making them key spatial carriers for strengthening the integration of intellectual property protection in the Yangtze River Delta region during the implementation of the "14th Five-Year Plan", and promoting the Guangdong-Hong Kong-Macao Greater Bay Area as an international cooperation highland for intellectual property. As the leaders in promoting the integrated development of major national regional strategies, the construction and improvement of the green innovation pattern within urban agglomerations is particularly important. How to effectively rely on intellectual property protection to accelerate and assist the development of green innovation has become a breakthrough point in promoting high-quality economic development and building a new development pattern. The existing literature emphasizes examining the empowering mechanism of IPR protection for green innovation processes from a national, provincial, industrial, and enterprise perspective. There is a lack of further exploration of the nonlinear relationship between IPR protection and urban green innovation at the city level.
This study focuses on the Yangtze River Delta and Pearl River Delta urban clusters, analyzing the driving effects of IPR protection on the development of urban green innovation and its internal mechanisms based on panel data from 2010 to 2021, using spatial Durbin models and threshold models. The study finds that (1) the empowering effect of IPR protection on urban green innovation is continuously changing. As the level of IPR protection increases, the driving effect changes from "incentive effect" to "crowding-out effect", and its negative hindering effect shows a trend of increasing strength. In the Pearl River Delta urban cluster, there is a more complex inverted "U" relationship between the two, while no significant nonlinear evolution is found in the Yangtze River Delta. (2) The spillover effect of IPR protection has significant spatial heterogeneity. In the Pearl River Delta urban cluster, local IPR protection has a "stimulating effect" on the development of adjacent urban green innovation, while the Yangtze River Delta urban cluster shows a "crowding-out effect". (3) IPR protection is conducive to promoting the quality improvement of green innovation, which means that under more stringent IPR protection, cities tend to conduct substantive green innovation rather than strategic green innovation. (4) The mechanism test shows that the improvement of IPR protection level induces R&D personnel and funding inputs, promoting the improvement of urban green innovation capabilities based on existing innovation activities.
With a focus on the two largest city clusters in China, namely the Yangtze River Delta and the Pearl River Delta, this study employs kernel density estimation and exploratory spatial analysis tools to analyze the spatial and temporal differentiation of green innovation efficiency and intellectual property protection level within these two city clusters, providing a more refined characterization of the green innovation efficiency and intellectual property protection level at the urban scale from the input-output perspective of expected and unexpected output, as well as the perspective of technology transaction market. Then, by incorporating intellectual property protection into the analysis framework of green innovation development, the study explores the incentive and crowding-out effects of intellectual property protection in driving the green innovation process, from the perspectives of heterogeneous non-linearities and spatial interaction effects, shedding light on whether intellectual property protection can break the binary constraints of "ecology" and "innovation" in urban green innovation.Furthermore, it examines the mechanism through which intellectual property protection promotes urban green innovation by investigating the transition of green innovation status and quality, and finds that investment in research and development and research funding can enable intellectual property protection to promote green innovation, resulting in cities combining green innovation with existing innovation activities;under stricter intellectual property protection, cities tend to engage in substantive rather than strategic innovation.