Analysis of Patent Proposals for Waste Plastic Utilization

By Song Jiajin, State Intellectual Property Office of China

With the development of the world economy and the progress of science and technology, plastic products have come to be viewed by people everywhere as a necessity of daily life. Millions of tons of plastic is discarded in China each year, and it does not naturally degrade. At present, China recycles very little of such waste, allowing serious white pollution to accumulate. Moreover, the raw materials of plastics mainly come from coal and petrochemical fuels like oil that are non-renewable. The supply of plastic raw materials in China is very tight, so large quantities are imported from abroad. Therefore, the treatment and recycling of waste plastics would help to resolve the two huge and growing problems in China – the plastic raw material supply and white pollution.

Quantitative analysis of the subjects of patent applications

The main technologies for recycling waste plastics are plastics recycling (plastic to plastic), chemical cracking and thermal incineration. At present, in China’s patenting process, plastics recycling is generally included in the special classification number B29B17, then by using the keywords like ‘cracking,’ ‘combustion’ and ‘incineration’ to search, and removing rubber-related patents, a total of 2 028 patents were found. See Figure 1 for details.
According to Figure 1, the quantity of such patent applications was less than 50 in 2000 and increased nine-fold to 450 in 2013. The quantity of patent application showed steady trend of year-by-year growth, except for slight drops in 2004 and 2006. This shows that China has paid more and more attention to waste plastics utilization and that this field has become an R&D focus.

Distribution of the applicants

According to our analysis of applications in this area, foreign entities applied for 620 invention patents in China. Although domestic entities applied for 1 408 patents, 877 of those applications requested utility model patents while, only 531 requested invention patents (which involve higher technical content). This shows that foreign businesses and innovators have paid more attention to China’s plastic recycling utilization market. The top 10 applicants for Chinese patents are listed in Table 1.
The applicants are mainly enterprises. The top three applicants are all foreign companies, showing that in this sector, foreign companies have established obvious advantages in the realm of patents. Zhangjiagang Yili Machinery Co., Ltd and Zhejiang Boretech Co., Ltd have applied for many beverage equipment patents, especially label peeling equipment and plastic film recycling granulators. Feng Yubin has applied for many patents in areas such as garbage recycling/utilization and plastic crushing and separation.
According to our analysis of the main applicants, the patents of foreign applicants either have more advanced patented technology or have wide applicability, such as patent in recycling waste materials while maintaining their original performance, waste plastic depolymerization during recycling or in preparation as fuel. Moreover, the level of recovery technology is higher.  An example of broad applicability is a recovery technology related to a wide range of material sources like thermosetting, foam, metal plastics and insulation materials. A second example is a technology that can be used in breaking/melting equipment for recycling of various materials, so the patent has a high value. Comparatively speaking, the domestic proposals are more scattered, making it difficult to form a patent pool. Among the patents requested by domestic applicants submitting multiple applications, the proportion of invention patents is not high. In addition, domestic applications tend to target a single application field, are mostly related to the simple regeneration process and have unimpressive overall technical advantages.
On the other hand, domestic applicants are mainly distributed in the regions with more developed processing and manufacturing industries such as Jiangsu, Zhejiang and Guangdong provinces, while foreign applicants are mainly distributed in the developed countries like Japan, the United States and Germany, showing that the developed countries and regions remain at the forefront of R&D for recycling & reutilization technology, at least for waste plastics.

Analysis of ‘hot’ patent applications

According to a specific analysis of the technology content of patent applications, around 1 300 are related to recycling, around 600 involve chemical cracking and around 100 are related to incineration. On the whole, recycling and chemical cracking are the major application fields, and recycling is the most frequently addressed.
In the recycling area, by stage of recycling, around 100 applications are related to waste plastic cleaning, including 51 invention patent applications and around 14 authorization applications. These applications basically come from domestic applicants and mainly focus on enhancing the efficiency of cleaning or the recovery and treatment of cleaning wastewater. For example, the granted patent CN101896290B specifies equipment and a method for cleaning plastic containers, and by using the circumstances of the tearing unit and the inherent high friction between containers, the impurities and labels on the surface of the container are effectively removed. The patent CN101445303B presents an original cyclic utilization method and unit for cleaning wastewater for public use, and through filtration, electrolysis, aeration, flocculation, sedimentation and filtration, washing wastewater can be recycled and meet the emission standards.
Around 157 patent applications are related to separation, including around 110 invention patent applications and around 25 authorization applications. These patent applications mainly focus on complex materials like waste electrical appliances and garbage. In this sector, Japanese applicants such as Hitachi Zosen Corporation, Mitsubishi Electric Corporation and Panasonic Corporation mostly focus on waste electrical appliances, while domestic applicants mainly focus on garbage disposal. The main processes include electrostatic separation and density separation. For example, patent CN1374888B has proposes a plastic separation unit. The patent CN102303383B presents a pneumatic separation system to the public. By setting up a light material conveyor belt and a heavy material conveyor belt, high separating efficiency can be obtained.
Around 373 patent applications are involved in waste plastic crushing, including 154 invention patent applications and around 66 authorization applications. The main research focus is crushing cutters. For example, patent CN101224438B describes a plastic crushing cutter with a replaceable cutter head. The cutter body and the cutter head are designed as a split structure and are made of different metallic materials, so cost is reduced and replacement is convenient. Patent CN101693397B presents a biaxial crushing cutter which can effectively break expanded polystyrene material into smaller blocks so as to facilitate the subsequent hot melt and save energy.

Table 1   Top 10 Patent Applicants in China

Applicants                                                              Quantity
Eastman?Chemical Company                                                34
Panasonic Corporation                                                    25
Erema Engineering Recycling Maschinen Und Anlagen Gesellschaft M.B.H.    24
Zhangjiagang City Yili Machinery Co., Ltd.                                23
Feng Yubin                                                                18
Zhejiang Boretech Co., Ltd.                                                17
ZhangJiagang Baixiong Klimens Machinery Co., Ltd.                        15
Hangzhou Fulun Ecological Technology Co., Ltd.                            13
Krones                                                                    13
Changzhou Chengli Machinery Electronic Co., Ltd.                        12


Around 520 patent applications are related to melt recycling, including around 390 invention patent applications and 61 authorization applications. The main research focus is how to uniformly melt, plasticize, discharge and obtain good melt plastification. For example, patent CN1777498B proposes a unit in which the constant feeding of materials to be processed to a screw feeding port is possible. Patent CN102006981A presents a waste extrusion unit. In order to improve outgassing effect, a non-threaded outgassing space between the threads of the reverse conveying direction and the threads of the same conveying direction is set up.
Around 600 patent applications address chemical cracking and recovery, including around 400 invention patent applications and around 100 authorization applications. The main research focuses are catalyst improvement and comprehensive recovery and utilization. For example, patent CN101284235B proposes an improved catalyst and its preparation method. A catalyst that includes clay or montmorillonite and metallic oxide can be used together with a molecular sieve to increase the reaction velocity of plastic cracking, reduce the temperature in the cracking reaction and improve the selectivity of decomposition products. Patent CN101433904A presents to the public a process for regeneration of energy sources and comprehensive utilization of urban domestic garbage, and through three big steps (garbage classification, cracking of organic substances, treatment of organic substance cracking byproducts). The efficiency of waste conversion and utilization is improved.
Around 100 patent applications are related to thermal incineration, including around 30 invention patent applications and around 10 authorization applications. The technical focus is fueling technology. For example, the patent CN101215490B describes a garbage derived fuel and its preparation method. By adding the appropriate amount of coal and calcium materials, a garbage derived fuel with a certain energy concentration, hot and cold intensity and technical properties is prepared. Patent CN102066725B presents an engine fuel control system to the public. By a new way of controlling the mixture of garbage derived fuel and pipeline fuel, it can overcome the problem of deficient mixing reliability and stability.