Patents by Inventor Helmut Schlaf
Helmut Schlaf has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 5608030Abstract: Process for continuous preparation of homo- and copolyoxymethylenes with stable end groups in a homogeneous phase, in which in a tubular reactor with static mixing elements cyclic formaldehyde oligomers are polymerized in the presence of protonic acids as initiators in amounts of 0.005 to 500 ppm in a polymerization zone, in which the residence time of the reaction components in this zone is 0.1 to 10 min and in which the initiator is deactivated immediately after polymerization, there being a fluid transition between the polymerization and deactivator zones which is determined solely by the addition of deactivator, and in which, besides deactivation, stabilization of the chain ends is carried out in the presence of residual monomers, with the volatile constituents being removed from the reaction mixture in a subsequent vent unit. Stabilization is carried out in the presence of alkaline substances, either at temperatures of 150.degree. C. to 250.degree. C.Type: GrantFiled: August 15, 1994Date of Patent: March 4, 1997Assignee: Hoechst AktiengesellschaftInventors: Michael Hoffmockel, Karl-Friedrich M uck, Helmut Schlaf, Karlheinz Burg
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Patent number: 5401859Abstract: In the process for the preparation of pure trioxane by continuous or semicontinuous crystallization processes, if alkaline organic compounds are added no flocks appear after more than 120 hours of operation. As a result, blockage of the crystallization unit is prevented and problem-free running is made possible.Type: GrantFiled: June 7, 1993Date of Patent: March 28, 1995Assignee: Hoechst AGInventors: Karl Muck, Helmut Schlaf, Siegbert Rittner
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Patent number: 5266633Abstract: The invention relates to a mixture composed essentially of polyoxymethylene (component A), a rubber-elastic graft copolymer in which the particles have been formed from a rubber-elastic, single-phase core based on polydiene and a hard graft shell (component B) and, if appropriate, a polymeric third component (component C). The invention also relates to a three-component mixture of the components A, B' and C, the core, in the case of B', being preponderantly or entirely composed of poly(meth)acrylic acid ester or silicone rubber instead of polydiene.The shaped articles produced from these mixtures are particularly distinguished by good low-temperature impact strength.Type: GrantFiled: June 17, 1991Date of Patent: November 30, 1993Assignee: Hoechst AktiengesellschaftInventors: Karlheinz Burg, Harald Cherdron, Friedrich Kloos, Helmut Schlaf
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Patent number: 5256733Abstract: Thermoplastic molding composition composed of A) 50 to 95% by weight of polyoxymethylene, B) 5 to 50% by weight of a rubber-elastic graft copolymer and optionally customary additives, in which the component B) is composed of a rubber-elastic core based on at least one polydiene, which is at least partially crosslinked, and at least one hard graft shell and has a bimodal particle size distribution. Monomers for formation of the graft shell are styrene, (meth)acrylonitrile and/or methyl methacrylate. The moldings produced from the molding compositions possess good tough fracture characteristics even at low temperatures.Type: GrantFiled: August 7, 1991Date of Patent: October 26, 1993Assignee: Hoechst AktiengesellschaftInventors: Dietrich Fleischer, Helmut Schlaf
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Patent number: 5047471Abstract: The invention relates to a mixture composed of polyoxymethylene (component A), a rubber-elastic graft copolymer in which the particles have been formed from a rubber-elastic, single-phase core based on polydiene and a hard graft shell (component B) and a polymeric third component (component C).The invention also relates to a three-component mixture of the components A, B' and C, the core, in the case of B' being preponderantly or entirely composed of poly(meth)acrylic acid ester or silicone rubber instead of polydiene.The shaped articles produced from these mixtures are particularly distinguished by good low-temperature impact strength.Type: GrantFiled: May 20, 1988Date of Patent: September 10, 1991Assignee: Hoechst AktiengesellschaftInventors: Karlheinz Burg, Harald Cherdron, Friedrich Kloos, Helmut Schlaf
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Patent number: 5039741Abstract: The invention relates to a mixture composed essentially of polyoxymethylene (component A), a rubber-elastic graft copolymer in which the particles have been formed from a rubber-elastic, single-phase core based on polydiene and a hard graft shell (component B) and, if appropriate, a polymeric third component (component C). The invention also relates to a three-component mixture of the components A, B' and C, the core, in the case of B', being preponderantly or entirely composed of poly(meth)acrylic acid ester or silicone rubber instead of polydiene.The shaped articles produced from these mixtures are particularly distinguished by good low-temperature impact strength.Type: GrantFiled: March 2, 1990Date of Patent: August 13, 1991Assignee: Hoechst AktiengesellschaftInventors: Karlheinz Burg, Harald Cherdron, Friedrich Kloos, Helmut Schlaf
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Patent number: 4195158Abstract: Oxymethylene polymers (POM) are obtained in a granular form, by cooling a POM solution or dispersion, whose temperature is above the sintering temperature of the POM, to a temperature slightly below the sintering temperature of the POM, and extracting from the suspension obtained only those POM particles which show a grain diameter of more than 70 .mu.m. As solvent or dispersing agent as well as precipitating and cooling agent there is used a mixture of methanol and water with a methanol content of at least 75% by weight. The POM obtained is suitable as engineering plastic material for the manufacture of shaped articles having improved mechanical properties.Type: GrantFiled: August 8, 1978Date of Patent: March 25, 1980Assignee: Hoechst AktiengesellschaftInventors: Karlheinz Burg, Alwin Heller, Hans-Dieter Sabel, Helmut Schlaf, Gunter Sextro
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Patent number: 4151346Abstract: Oxymethylene polymers are obtained in a granular form by cooling a solution or dispersion of an oxymethylene polymer, the temperature of which solution or dispersion is above the sintering temperature of the oxymethylene polymer, to a temperature just below the sintering temperature of the oxymethylene polymer. As dissolving or dispersing agent as well as precipitating and cooling agent there is used a mixture of methanol and water having a methanol content of at least 75% by weight. The oxymethylene polymer obtained is suitable as engineering plastic for preparing moulded articles.Type: GrantFiled: January 26, 1978Date of Patent: April 24, 1979Assignee: Hoechst AktiengesellschaftInventors: Gunter Sextro, Karlheinz Burg, Helmut Schlaf, Hans J. Leugering, Alwin Heller
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Patent number: 4111912Abstract: Granular oxymethylene polymers are prepared by cooling a solution or dispersion of an oxymethylene polymer, the temperature of the said solution or dispersion being above the sintering temperature of the oxymethylene polymer, to a temperature just below the said sintering temperature. As dissolving or dispersing agent there is used a mixture of methanol and water. The cooling of the said solution or dispersion is effected in two stages while using a liquid cooling agent or a cooling device. After precipitation the coarse-granular polymer is separated from the fine-granular portion. It is suitable as engineering plastic for preparing molded articles.Type: GrantFiled: May 4, 1977Date of Patent: September 5, 1978Assignee: Hoechst AktiengesellschaftInventors: Gunter Sextro, Karlheinz Burg, Helmut Schlaf, Hans-Dieter Sabel, Alwin Heller
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Patent number: 4082729Abstract: Oxymethylene polymers are prepared by polymerization of trioxane, optionally in the presence of comonomers, with the acid of a cationically active initiator. Suitable initiators are salt-like compounds, especially onium salts of Lewis acids. The initiator is used in the form of a solution in a cyclic carbonic acid ester present in a liquid phase. The oxymethylene polymers are thermoplastic and may be used as engineering materials.Type: GrantFiled: August 31, 1976Date of Patent: April 4, 1978Assignee: Hoechst AktiengesellschaftInventors: Karlheinz Burg, Helmut Schlaf
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Patent number: 4046738Abstract: Oxymethylene polymers (POM) are obtained in granular form by cooling a POM solution or dispersion having a temperature above the sintering temperature of the POM in two stages to a temperature just below the said sintering temperature. The solvent or dispersion agent used is a mixture of methanol and water and the cooling agent is a methanol/water mixture which may contain POM suspended therein. The granular POM obtained is suitable as technical material for making shaped articles.Type: GrantFiled: November 5, 1975Date of Patent: September 6, 1977Assignee: Hoechst AktiengesellschaftInventors: Gunter Sextro, Karlheinz Burg, Hans Joachim Leugering, Helmut Schlaf, Alwin Heller