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PLAiR – A New Material Made from Plants and Air

Foamed PLA sheets of biomass plastic for a zero-carbon, circular economy

Background

The effects of global warming are visible as worldwide climate changes, and the industrial sector urgently needs to produce and spread alternatives to fossil-derived plastic. The Ricoh Group leads the industry with its commitment to corporate ecological management. To achieve a zero-carbon, recycling society, Ricoh has been designing its multi-function printers (MFPs) using biomass plastic components, primarily made of PLA (polylactic acid) produced from plant-derived starch and sugar. The plant-derived, compostable PLA is the foundation for developing a new material—the foamed PLA sheet.

Effective use of biomass resources

Solution

PLA has excellent ecological benefits, including carbon neutrality and compostability. Burning PLA does not increase the net amount of CO2 in the atmosphere, and PLA degrades into water and CO2 in a particular environments, such as soil or compost. Despite these advantages, PLA has not gained market popularity because it is generally hard to shape and is more costly than fossil-derived plastics.

Ricoh's has developed a foamed PLA sheet that is flexible and strong using its proprietary technologies. The sheet has a wide range of applications, including cushioning and packing material or various container types.

*CO2 emitted by the factory is collected and used so there is no increase in atmospheric emissions.

The foamed PLA sheets will benefit branded product owners by freely using biomass plastic in various scenarios. Through environment business, brand owners will garner trust for ESG investments and contribute to society.

Ricoh's foamed PLA sheets are much more flexible and stronger than conventional PLA and will give material processor owners a greater security sense as they expand their businesses.

PLA foam sheet, flexible and strong

Technical Highlight

The innovative material is flexible and strong. The PLA, a nearly 100% plant-derived, undergoes a foaming process utilizing Ricoh's “CO2 fine foam technology” to produce foam sheets.

Conventional foam methods cannot be used for manufacturing genuine PLA. Making PLA foam requires that it be blended with other materials, such as fossil-derived resins. The blending process is not the only challenge—bubble sizes are difficult to control and the results often are uneven. Conventional methods can only produce bubbles of large diameter on the order of hundreds of microns; the resulting sheets tend to break easily. Beyond that is an inevitable tradeoff, adding fossil-derived resins compromises the carbon-neutrality and biodegradability of PLA.

Ricoh's supercritical CO2 technology produces uniform bubbles only tens of microns in diameter. Through the kneading process, fillers (foam nucleating agents) are evenly distributed in PLA, and the foaming takes place with the fillers as nuclei. PLA can be made into very thin sheets while its flexibility and strength are maintained because of the bubble uniformity.

Cross-section of conventional PLA sheet
Cross-section of Ricoh's PLA sheet
Cross-sections of sheets produced by Ricoh's and conventional methods

Supercriticality is attained when CO2 is pressurized at a high temperature. Gas as dense as liquid, the CO2 particles violently collide with each other and produce natural convection. As PLA and fillers are added, they are evenly kneaded using convection. The evenly distributed fillers work as foaming nuclei , resulting in even, minute bubbles.

Metal-free, low-temperature, high-speed polymerization of PLA using supercritical CO2
Plasticization of PLA using supercritical CO2 (liquefaction)

Ricoh is producing PLA foam sheets on prototype machines to promote technological development and verify performance, including flexibility, strength, and compostablility, and demonstrate costs. Ricoh intends to deliver the PLA foam sheets in the near future.

Sample table:
values shown above are not specifications, but representative sample values (as of November 2020)
Intended purpose Cushioning and packaging materials Food containers Various trays and containers
Foaming scale High
20-25X
Medium
10-15X
Low
2-3X
Thickness 2-3mm 1-3mm 0.5-1.5mm
Piercing strength (N)
JIS Z 1707*
3.6 2.8
Tensile strength (MPa)
JIS K 6767*
MD 0.9 1.4 35
TD 0.5 1.1
*
JIS: Japanese Industrial Standards
JIS K 6767: Cellular plastics−Polyethylene−Methods of test
JIS Z 1707: General rules of plastic films for food pack

Ricoh's Vision

A new material, made from plants and air, we call it “PLAiR.” In Ricoh's vision, tenderness is the bridge to the future. We are committed to making a zero-carbon, circular economy becomes a reality, where everyone feels secure in using any material around them. We will continue to deliver new environment-conscious materials.

Sample molded PLA foam sheets (reference exhibition at nanotech 2020)
Sample molded foamed PLA sheets (reference exhibition at nanotech 2020)