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Inventions of Latvia
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Main authors:

The essence of the invention:

“Since the mid 60-ties research in a new sphere - polymer chemistry - expanded forming polymer foams of new type as very effective heat insulating materials. In the beginning they were obtained from oil compounds, later also from wood pulp recycling products. This was the way the famous and rather effective heat insulating material RIPOR was developed. It has been used also in the design of the soviet cosmic space ships «Energy-Buran» and in the cosmic air vehicles that were sent to Mars.”
J.Stradinsh. «Latvian Academy of Sciences: origin, history, transformation», Riga, «Zinatne» Publishers, 1998, p.290) (in Latvian)

Ripor (solid foams) - hard-to-burn foam plastic. Ripor is used as a heat insulating and sound proofing material: in construction, shipbuilding, for tubings and cisterns etc. The main advantages of Ripor - good adhesion to all building materials, low flammability and brittleness and little water absorbency. Different modifications of Ripor can be used in a wide range of temperatures (from + 140°C to - 253°C and lower).

Other chemists usually use products of oil chemical recycling for the production of polymer materials (incl. polyurethanes), although oil itself is an expensive raw material. Scientists from the Latvian State Institute of Wood Chemistry tried out several technologies until they managed to find the substitute for oil products. As a result tall oil (residue of cellulose boiling) became one of the raw materials for the production of plastic foam. Waste material became an economically gainful heat insulating material.


Since 1983 polyoles obtained from tall oil for the production of foam plastic Ripor are being produced by "Himprom" in Cheboxari (Russia) on the grounds of technology developed by the Latvian State Institute of Wood Chemistry.

Ripor was used in all the regions of the former USSR as well as in Latvia. The huge cisterns for ammonia storage in Ventspils (Latvia) are insulated with Ripor (see the picture).

Simultaneously with the development of Ripor technology special devices - foam generator and several modifications (foaming devices UMP, mobile foaming device PNG, portable foaming device PUN) - were produced at the office of the Latvian State Institute of Wood Chemistry (the "Wood-pulp" office) that are now being produced by the "Wood-pulp" office.

Heat insulation
for the liquid
ammonia tank
in Ventspils

heat insulation
for the carrier rocket
"Energy" of USSR


Selection of patent documents:

Authors' certificates of USSR:

  • I.Argalis, A.Alksnis, U.Silis, U.Stirna. Nr. 1126597, 1984
  • U.Stirna, P.Tukums, V.Jakushins, a.o. Nr. 1041550, 1983.
  • U.Stirna, A.Alksnis, P.Tukums, a.o. Nr. 1159309, 1982.
  • U.Stirna, A.Alksnis, V.Karlivans. Nr. 131236, 1978.

Patents of Latvia:

  • U.Stirna, I.Sevastjanova, V.Jakushins, M.Misane. Composition of biodegradable polyurethane foams. LV 11550, 1995, Int. Cl.6 C08 G18/12.
  • U.Stirna, I.Sevastjanova, M.Misane, A.Alksnis. Stable for storage polyole composites for obtaining of polyurethane and polyisocyanate foams. LV 11551, 1995, Int. Cl.6 C08 G18/12.


  • U.K.Stirna, U.K.Silis. Ripors-6T. Riga, "Zinatne" Publishers, 1988, p. 184 (in Russian).


  • U.K.Stirna, P.I.Solodovniks, V.A.Jakushins. Usage of freon in the production of solid polyurethane foams and ecological problems connected with the production process. - Proceedings of the Latvian Academy of Sciences, B, 1992, 5, p. 61-67 (in Russian).
  • U.K.Stirna, V.A.Jakushins, I.V.Sevastjanova. Polyurethane foams and polyisocyanate foams containing freon. Wood Chemistry, 1994, 1, p. 53-61 (in Russian).
  • U.Stirna, I.Sevastjanova, V.Jakushins, M.Misane. Molecular packing of plasticized starch. Latvian Journal of Chemistry, 1997, Nr. 1, pp. 120-125.
  • U.Stirna. New biodegradable polymer materials from unmodified and modified starch. Proceedings of the Latvian Academy of Sciences, 1997, Vol. 51, Nr. 3-4, pp.179-183.
  • A.Alksnis, U.Stirna. Bioabbaubare PUR-Schaumstoffe. 27. Jahrestagung der GUS. “Umwelteinflü ße erfaßen, simulieren, bewerten” . 18.-20. März, 1998, Karlsruhe, S.13-20 (in German).
  • A.Alksnis, U.Stirna. Polyurethanschaumstoffe aus nachwachsendem Rohstoff. 28. Jahrestagung der GUS. “Umwelteinflü ße erfaßen, simulieren, bewerten” . 10.-12. März, 1999, Karlsruhe, S.1-10. (in German)