WO1992002569A1 - Polymer pellet configuration for solid-state polymerization - Google Patents
Polymer pellet configuration for solid-state polymerization Download PDFInfo
- Publication number
- WO1992002569A1 WO1992002569A1 PCT/US1991/005399 US9105399W WO9202569A1 WO 1992002569 A1 WO1992002569 A1 WO 1992002569A1 US 9105399 W US9105399 W US 9105399W WO 9202569 A1 WO9202569 A1 WO 9202569A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- solid
- polymer
- pellet
- pellets
- state polymerization
- Prior art date
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B13/00—Conditioning or physical treatment of the material to be shaped
- B29B13/06—Conditioning or physical treatment of the material to be shaped by drying
- B29B13/065—Conditioning or physical treatment of the material to be shaped by drying of powder or pellets
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/78—Preparation processes
- C08G63/80—Solid-state polycondensation
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/12—Powdering or granulating
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
Definitions
- the present invention relates to polymer pellet configuration for solid—state polymerization. More specifically, the present invention relates to pellets having a short path length for volatiles to be removed from the pellets, and a reduced contact area among pellets to minimize sticking of the pellets undergoing solid—state polymerization in a stationary or moving bed reactor.
- polyethylene terephthalate may be prepared in the molten state by polycondensation accompanied by liberation of ethylene glycol from prepolycondensates in autoclaves of conventional design. Intrinsic viscosities of approximately 0.7 are usually obtained. Intrinsic viscosities as high as 1.00 can be obtained in specifically designed reactors which improve the evaporation of glycol.
- These prior art processes have the disadvantage that high reaction temperatures, high catalyst concentrations and long reaction time periods are required to achieve high relative viscosities. The inevitable result is an increasing thermal degradation of the melt which manifests itself by a large number of carboxyl end groups and an intensive yellow coloring of the end product.
- a high percentage of carboxyl end groups leads to strong signs of degradation during the re elting of the polycondensate.
- the discolorations are particularly undesirable if pellucid polycondensates are needed for the manufacture of, for instance, packing material for foodstuffs or beverages.
- elevated concentrations of aldehydes are to be expected in the melt. These properties are particularly undesirable if the end product is used to manufacture beverage bottles.
- the aldehydes diffuse into the liquid and affect the flavor of these beverages. Further, such aldehyde containing beverages may be considered to be unfit for human consumption by certain regulatory bodies.
- Figure 1 is a plan view of a pellet according to the present invention taken along lines 1—1 of Figure 2;
- Figure 2 is a side view of the pellet shown in Figure 1;
- Figure 3 is a modification of the pellet according to the present invention;
- Figure 4 is a view showing two pellets stacked together. Description of the Invention
- a polymer pellet having improved reactivity for solid state polymerization and less tendency to stick during processing with heat, the pellet having opposite faces generally lying in parallel planes, and in cross—section in a plane parallel to the faces the pellet having a generally rectangular central section, the corners thereof protruding into generally rounded lobes, the generally rectangular central section having dimensions A and B wherein the ratio of A to B is 1.2 to 6 and the ratio of B to the average radius of said lobes is 0.3 to 5.
- the polymer of the pellet according to this invention may be any polymer which is to be polymerized in the solid state.
- Preferred polymers are polyesters, and in particular poly(ethylene terephthalate) or copolymers thereof.
- polyesters such as poly(ethylene terephthalate) are produced to an intermediate molecular weight of, say 0.4—0.65 in a melt phase, by reacting a dicarboxylic acid or ester with a glycol using suitable catalysts under conventional reaction condition well known in the art. Following melt phase polymerization, the polymer may be subjected to further polymerization in the solid state.
- Solid state polymerization is a well known technique for building up molecular weight of a polymer in the solid state.
- One conventional solid—stating operation takes place in so—called plug flow reactors wherein polymer pellets are introduced into the top of a tall cylindrical vessel and removed from the bottom at the same rate. During the residence times in the reactor, which is commonly in the order of 8—18 hours, the pellets reach high temperatures, generally 200—250°C.
- Molecular weight as measured by inherent viscosity (I.V.), increases during the time the pellets are in the reactor. Typically, I.V. is increased from a range of 0.4—0.65 to greater than 0.7. This process is thoroughly described in U.S. Patent No. 4,064,112, which is incorporated herein by reference.
- Described herein is a design of the cross section of the pellets that incorporates into a pellet of a given weight a reduced path length the volatiles need to travel to the exterior of the pellet to increase solid—state polymerization rate, and reduced contact area among pellets to minimize sticking.
- This design will also reduce the initial degradation experienced by the pellets during solid—state polymerization because the shorter path allows the moisture content of the pellets to leave in much shorter times and minimize the probability of hydrolytic degradation.
- the design is shown in Figures 1 and 2.
- Figure 1 illustrates pellet 10 having a generally rectangular central section 12 having dimensions A and B.
- the corners of section 12, 14, 16, 18 and 20 are illustrated in broken lines and protrude into generally rounded lobes 22, 24, 26 and 28, respectively.
- the lobes are preferably rounded as shown in Figure 1, but may be of the general shape shown in Figure 3 wherein the C dimension would be an average distance or radius as indicated in Figure 3 by broken line 30.
- the optimal design has the ratio of B to C of 1 and the ratio of A to B ranging from 1.6 to 4, although the benefit of this design can still be realized when the ratio of B to C varies from 0.3 to 5 and the ratio A to B varies from 1.2 to 6.
- the ratio of B to C is greater than 1, the cross section of the pellet has the general shape as shown in Figure 1.
- the advantage of the mentioned design can be demonstrated in Figure 4 wherein the pellets 10 and 11 can be stacked with minimum amount of surface contact. The added space between the two pellets also allows carrier gas to pass through to remove volatiles generated during solid-state polymerization thus increasing the rate of solid-state polymerization.
- the pellets of the present invention can be obtained by conventional methods, such as by extruding the polymer melt through a die with the die holes taking the shape as shown in Figure 1.
- the extruded polymer can then be chilled to form a solid rod and be cut into pellets of desired lengths.
- the length (1) of the pellets preferably ranges from 0.05 to 0.2 inch but can vary from 0.03 to 0.3 inch.
- the dies can have any number of holes normally ranging from 1 to 100.
- the opposite upper and lower faces 13 and 15 of pellet 10 are theoretically in generally parallel planes. However, under production conditions, these faces may not be perfectly flat or parallel due to the fact that the cutter is cutting a continuously moving strand of polymer and upon cooling of the pellet there may be slight distortion.
- lobes 22, 24, 26 and 28 are generally rounded. However, they do not have to be perfectly round and may even resemble portions of a square or rectangle as shown in Figure 3. In this case, the average diameter, or an arc 30 would be used as the C dimension.
- the following example is submitted for a better understanding of this invention.
- Pellets with cross sections taking the shape of a circle, square, rectangle and design according to this invention are prepared by extruding poly(ethylene) terephthalate with a 0.76 I.V. through a die plate with the corresponding shape of die holes.
- the circular, square and rectangular shapes are for comparison.
- the extruded rods are quenched in chilled water and cut into pellets with an average weight of 0.0177 g/pellet using a rotary cutter.
- the pellets are crystallized at 180°C and the solid—state polymerization rates are measured. The results are shown in Table 1.
- I.V. inherent viscosity
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Polyesters Or Polycarbonates (AREA)
- Other Resins Obtained By Reactions Not Involving Carbon-To-Carbon Unsaturated Bonds (AREA)
- Polymers With Sulfur, Phosphorus Or Metals In The Main Chain (AREA)
- Heterocyclic Carbon Compounds Containing A Hetero Ring Having Oxygen Or Sulfur (AREA)
- Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP91914427A EP0541674B1 (en) | 1990-08-03 | 1991-07-31 | Polymer pellet configuration for solid-state polymerization |
DE69104206T DE69104206T2 (en) | 1990-08-03 | 1991-07-31 | POLYMERE PELLET CONFIGURATION FOR POLYMERIZATION IN SOLID STATE. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US07/563,024 US5145742A (en) | 1990-08-03 | 1990-08-03 | Polymer pellet configuration for solid-state polymerization |
US563,024 | 1990-08-03 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1992002569A1 true WO1992002569A1 (en) | 1992-02-20 |
Family
ID=24248787
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1991/005399 WO1992002569A1 (en) | 1990-08-03 | 1991-07-31 | Polymer pellet configuration for solid-state polymerization |
Country Status (9)
Country | Link |
---|---|
US (1) | US5145742A (en) |
EP (1) | EP0541674B1 (en) |
JP (1) | JPH06500133A (en) |
AT (1) | ATE111929T1 (en) |
CA (1) | CA2079326A1 (en) |
DE (1) | DE69104206T2 (en) |
DK (1) | DK0541674T3 (en) |
ES (1) | ES2060404T3 (en) |
WO (1) | WO1992002569A1 (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5391694A (en) * | 1993-10-15 | 1995-02-21 | Shell Oil Company | Solid state polymerization of polyesters with low diffusion resistance prepolymer granules |
JPH10195204A (en) * | 1997-01-14 | 1998-07-28 | Toray Ind Inc | Polyester granular chip |
KR20020074245A (en) * | 2001-03-19 | 2002-09-30 | 주식회사 파웰 | High efficiency soft-switching AC-DC boost converter using coupled inductor and energy recovery circuit having power factor correction function |
DE102004012579A1 (en) * | 2004-03-12 | 2005-09-29 | Bühler AG | Process for the preparation of a partially crystalline polycondensate |
EP2055458A1 (en) * | 2006-08-11 | 2009-05-06 | Mitsui Chemicals, Inc. | Pellets comprising polymer and package |
US8968615B2 (en) | 2004-09-02 | 2015-03-03 | Eastman Chemical Company | Low melting polyester polymers |
Families Citing this family (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5393863A (en) * | 1993-01-04 | 1995-02-28 | Eastman Chemicali Company | Production of branched polyesters |
US5393871A (en) * | 1993-01-04 | 1995-02-28 | Eastman Chemical Company | Production of polyesters and polyester articles having good clarity |
DE19505680C1 (en) * | 1995-02-20 | 1996-05-23 | Inventa Ag | Condensn. injection moulding of preform for food-quality bottle |
US6048922A (en) * | 1997-08-20 | 2000-04-11 | Eastman Chemical Company | Process for preparing high strength fiber reinforced composites |
US6043313A (en) | 1997-09-04 | 2000-03-28 | Eastman Chemical Company | Thermoplastic polyurethane additives for improved polymer matrix composites and methods of making and using therefor |
US20030060596A1 (en) * | 2001-07-18 | 2003-03-27 | Turner Sam Richard | Amorphous copolyesters |
US7834127B2 (en) * | 2001-07-18 | 2010-11-16 | Eastman Chemical Company | Amorphous copolyesters |
US20040151854A1 (en) * | 2003-02-03 | 2004-08-05 | Pecorini Thomas Joseph | Extrusion blow molded articles |
ITPD20040038A1 (en) * | 2004-02-16 | 2004-05-16 | Plastic Systems Srl | DEHUMIDIFICATION PROCESS OF PLASTIC MATERIALS IN GRANULES AND PLANT OPERATING IN ACCORDANCE WITH SUCH PROCESS |
DE102004014590A1 (en) * | 2004-03-23 | 2005-10-20 | Buehler Ag | Semicrystalline polyethylene terephthalate |
DE102007055242A1 (en) | 2007-11-16 | 2009-05-20 | Bühler AG | Process for the crystallization of crystallizable polymers with high tendency to adhere |
US7868125B2 (en) * | 2008-03-03 | 2011-01-11 | Eastman Chemical Company | Production of non-solid-stated polyester particles having solid-stated properties |
DE102009009957A1 (en) | 2009-02-23 | 2010-08-26 | Bühler AG | Process for the production of polyester particles at high throughput in one line |
AT508252B1 (en) | 2009-12-28 | 2010-12-15 | Erema | METHOD AND DEVICE FOR PREPARING PARTIAL CRYSTALLINE POLYMER MATERIAL |
EP2671902B1 (en) | 2012-06-05 | 2018-01-03 | Polymetrix AG | Polyamide conditioning |
PL2712881T3 (en) | 2012-09-26 | 2015-10-30 | Polymetrix Ag | Method and apparatus for directly crystallisation of polymers under inert gas |
US10745517B2 (en) | 2012-09-26 | 2020-08-18 | Polymetrix Ag | Process and apparatus for direct crystallization of polycondensates |
KR101564500B1 (en) * | 2014-03-12 | 2015-10-29 | 주식회사 효성 | Method for preparing a polyester resin for high polymerization purpose |
EP4257629A3 (en) | 2017-02-17 | 2024-01-10 | Polymetrix AG | Method and device for direct crystallisation of polycondensates |
US20210101313A1 (en) * | 2017-04-26 | 2021-04-08 | The Coca-Cola Company | Multilobed polyester pellets |
EP3650186B1 (en) | 2018-11-08 | 2023-07-19 | Polymetrix AG | Method and device for direct crystallisation of polycondensates |
EP3708936B1 (en) | 2019-03-15 | 2024-04-17 | Polymetrix AG | Method for recycling of polyolefins |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4064112A (en) * | 1975-12-31 | 1977-12-20 | Zimmer Aktiengesellschaft | Process for the continuous production of high molecular weight polyethylene terephthalate |
EP0284544A2 (en) * | 1987-03-26 | 1988-09-28 | Shell Internationale Researchmaatschappij B.V. | Solid state polymerization of polyester prepolymers |
EP0335819A2 (en) * | 1988-04-01 | 1989-10-04 | The Goodyear Tire & Rubber Company | Preparation of ultra-high molecular weight polyester |
EP0354159A1 (en) * | 1988-08-03 | 1990-02-07 | Shell Internationale Researchmaatschappij B.V. | Solid state polymerization of porous pills made by compacting polyester prepolymers |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3188264A (en) * | 1962-12-21 | 1965-06-08 | Tektronix Inc | Loose fill packing material |
US3595737A (en) * | 1967-09-11 | 1971-07-27 | Anaconda Wire & Cable Co | Pellet for improved extrusion method |
US4169179A (en) * | 1977-10-07 | 1979-09-25 | Bussey Harry Jun | Spring-like loose fill packaging material |
US4166875A (en) * | 1977-10-07 | 1979-09-04 | Bussey Harry Jr | Free-flowing packaging material |
DE2848338A1 (en) * | 1978-11-08 | 1980-05-22 | Hoechst Ag | FREE-FLOWING PACKING MATERIAL MADE OF FOAMED PLASTIC |
-
1990
- 1990-08-03 US US07/563,024 patent/US5145742A/en not_active Expired - Fee Related
-
1991
- 1991-07-31 CA CA002079326A patent/CA2079326A1/en not_active Abandoned
- 1991-07-31 DK DK91914427.9T patent/DK0541674T3/en active
- 1991-07-31 WO PCT/US1991/005399 patent/WO1992002569A1/en active IP Right Grant
- 1991-07-31 DE DE69104206T patent/DE69104206T2/en not_active Expired - Fee Related
- 1991-07-31 AT AT91914427T patent/ATE111929T1/en not_active IP Right Cessation
- 1991-07-31 ES ES91914427T patent/ES2060404T3/en not_active Expired - Lifetime
- 1991-07-31 EP EP91914427A patent/EP0541674B1/en not_active Expired - Lifetime
- 1991-07-31 JP JP3513404A patent/JPH06500133A/en active Pending
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4064112A (en) * | 1975-12-31 | 1977-12-20 | Zimmer Aktiengesellschaft | Process for the continuous production of high molecular weight polyethylene terephthalate |
US4064112B1 (en) * | 1975-12-31 | 1994-09-13 | Davy Mckee Aktiengesellschaft | Process for the continuous production of high molecular weight polyethylene terephalate |
EP0284544A2 (en) * | 1987-03-26 | 1988-09-28 | Shell Internationale Researchmaatschappij B.V. | Solid state polymerization of polyester prepolymers |
EP0335819A2 (en) * | 1988-04-01 | 1989-10-04 | The Goodyear Tire & Rubber Company | Preparation of ultra-high molecular weight polyester |
EP0354159A1 (en) * | 1988-08-03 | 1990-02-07 | Shell Internationale Researchmaatschappij B.V. | Solid state polymerization of porous pills made by compacting polyester prepolymers |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5391694A (en) * | 1993-10-15 | 1995-02-21 | Shell Oil Company | Solid state polymerization of polyesters with low diffusion resistance prepolymer granules |
WO1995010557A1 (en) * | 1993-10-15 | 1995-04-20 | Shell Internationale Research Maatschappij B.V. | Solid state polymerisation of polyesters with low diffusion resistance prepolymer pellets |
US5412063A (en) * | 1993-10-15 | 1995-05-02 | Shell Oil Company | Solid state polymerization of polyesters with low diffusion resistance prepolymer granules |
JPH10195204A (en) * | 1997-01-14 | 1998-07-28 | Toray Ind Inc | Polyester granular chip |
KR20020074245A (en) * | 2001-03-19 | 2002-09-30 | 주식회사 파웰 | High efficiency soft-switching AC-DC boost converter using coupled inductor and energy recovery circuit having power factor correction function |
DE102004012579A1 (en) * | 2004-03-12 | 2005-09-29 | Bühler AG | Process for the preparation of a partially crystalline polycondensate |
US8968615B2 (en) | 2004-09-02 | 2015-03-03 | Eastman Chemical Company | Low melting polyester polymers |
EP2055458A1 (en) * | 2006-08-11 | 2009-05-06 | Mitsui Chemicals, Inc. | Pellets comprising polymer and package |
EP2055458A4 (en) * | 2006-08-11 | 2013-04-03 | Mitsui Chemicals Inc | Pellets comprising polymer and package |
US8617706B2 (en) | 2006-08-11 | 2013-12-31 | Mitsui Chemicals, Inc. | Pellets comprising polymer and package containing the same |
Also Published As
Publication number | Publication date |
---|---|
DE69104206D1 (en) | 1994-10-27 |
EP0541674B1 (en) | 1994-09-21 |
CA2079326A1 (en) | 1992-02-04 |
ATE111929T1 (en) | 1994-10-15 |
JPH06500133A (en) | 1994-01-06 |
DK0541674T3 (en) | 1994-10-17 |
EP0541674A1 (en) | 1993-05-19 |
DE69104206T2 (en) | 1995-01-19 |
ES2060404T3 (en) | 1994-11-16 |
US5145742A (en) | 1992-09-08 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US5145742A (en) | Polymer pellet configuration for solid-state polymerization | |
US7329723B2 (en) | Thermal crystallization of polyester pellets in liquid | |
US10370486B2 (en) | Polyester polymer particles having a small surface to center molecular weight gradient | |
US5393871A (en) | Production of polyesters and polyester articles having good clarity | |
US5412063A (en) | Solid state polymerization of polyesters with low diffusion resistance prepolymer granules | |
CN1673251A (en) | Method for the production of highly condensed polyester granulate | |
TW200906902A (en) | High molecular weight polyester polymers with reduced acetaldehyde | |
EP0977793B1 (en) | Process for the preparation of polyesters | |
US5830982A (en) | Production of poly (ethylene terephthalate) | |
JP2004143442A (en) | Method for producing polyester resin | |
KR100942881B1 (en) | Method for Increasing Solid State Polymerization Rate of Polyester Polymers | |
US4849497A (en) | Solid state polymerization of porous pills made by compacting polyester prepolymers | |
US4977196A (en) | Solid state polymerization of porous pills made by compacting polyester prepolymers | |
US5393863A (en) | Production of branched polyesters | |
JP2004123917A (en) | Method for manufacturing polyester resin | |
US6124423A (en) | Process for crystallizing polyethylene naphthalate copolymers in the absence of devolatilization |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): CA JP KR |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): AT BE CH DE DK ES FR GB GR IT LU NL SE |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2079326 Country of ref document: CA |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1991914427 Country of ref document: EP |
|
WWP | Wipo information: published in national office |
Ref document number: 1991914427 Country of ref document: EP |
|
WWG | Wipo information: grant in national office |
Ref document number: 1991914427 Country of ref document: EP |