Classifications

• • 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
  • C08J2359/00—Characterised by the use of polyacetals containing polyoxymethylene sequences only
  • C08J2359/02—Copolyoxymethylenes

Definitions

• POM oxymethylene polymers
• the present invention now relates to a further embodiment of the latter method and is characterized in that the granular oxymethylene polymer particles obtained by precipitation with a grain diameter of more than 70 microns are separated and dried.
• the invention further relates to granular oxymethylene polymers which are produced by the aforementioned process.
• Oxymethylene polymers for the purposes of the invention are understood to mean poly (oxymethylenes) which, in addition to oxymethylene units, also have 0.1 to 20, preferably 0.5 to 10 percent by weight oxyalkylene units with 2 to 8, preferably 2, 3 or 4 adjacent carbon atoms in the main valence chain; Oxymethylene polymers whose proportion of oxyalkylene units is 0.7 to 5 percent by weight are particularly suitable.
• the oxymethylene polymers are known in a known manner by polymerizing the monomers in bulk, suspension or solution in the presence of cationically active catalysts. B. at a temperature of 0 to 100 ° C, preferably 50 to 90 ° C, (see. For example, US Patent 30 20 352).
• the cationically active catalysts used here are (1) protonic acids, for example perchloric acid, (2) esters of protonic acids, in particular esters of perchloric acid with lower aliphatic alcohols, for example perchloric acid tert.
• Lewis acids especially halides of Boron, tin, titanium, phosphorus, arsenic and antimony, for example boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentachloride, phosphorus pentafluoride, arsenic pentafluoride and antimony pentafluoride and (5) complex compounds or salt-like compounds of Lewis acids, preferably etherates or onium ether salts, for example boron trifluoride, for example boron trifluoride, for example boron trifluoride -n-butyl etherate, triethyloxonium tetrafluoroborate, trimethyloxonium hexafluorophosphate, triphenylhe
• the amount of the catalysts used in the copolyemerization depends primarily on the strength of their effectiveness; in general, the catalysts are used in an amount by weight of 0.1 to 2000, preferably 0.2 to 500 ppm, based on the total amount of the compounds to be polymerized.
• Good effective catalysts as boron trifluoride are advantageously in an amount by weight of 10 to 150, preferably 20 to 100 ppm, based on the overall amount of the poly - mer ensueden compounds.
• the corresponding molar amounts apply to complex compounds or salt-like compounds of the catalysts mentioned.
• Very powerful catalysts such as perchloric acid are used in an amount of 0.2 to 10 ppm, preferably 0.3 to 5 ppm.
• catalysts are diluted with an inert gas, for example nitrogen or a noble gas such as argon, while liquid or solid catalysts are dissolved in an inert solvent.
• an inert gas for example nitrogen or a noble gas such as argon
• Aliphatic or cycloaliphatic hydrocarbons and nitrated aliphatic or aromatic hydrocarbons are particularly suitable as solvents. Examples include: cyclohexane, methylene chloride, Ethylene chloride, nitromethane and nitrobenzene.
• the weight ratio of catalyst to diluent is usually 1: 5 to 1: 10,000, preferably 1:10 to 1: 100. Very powerful catalysts are advantageously diluted in a ratio of 1: 5,000 to 1: 20,000.
• the polymerization process is preferably carried out under an inert gas atmosphere and in the absence of moisture; inert gases are preferably inert gases, e.g. Argon, and nitrogen suitable.
• Suitable compounds which are copolymerizable with trioxane are, in particular, a) cyclic ethers with 3, 4 or 5 ring members, preferably epoxides, b) cyclic acetals, preferably formals, with 5 to 11, preferably 5, 6, 7 or 8 ring members and c) linear polyacetals, preferably polyformals.
• cyclic ethers are ethylene oxide, propylene oxide, styrene oxide, cyclohexene oxide, oxacyclobutane and Phenylglycidyl ether used, while as cyclic formals for example 1,3-dioxolane, 1,3-dioxane, 1,3-dioxepane and 1,3,6-trioxocane and 4-methyl-1,3-dioxolane, 4-phenyl-1, 3-dioxolane, 1,3-dioxonane and 1,3-dioxacycloheptene (5) can be used.
• Poly (1,3-dioxolane) and poly (1,3-dioxepane) are particularly suitable as linear polyformals.
• a regulator for the production of oxymethylene polymers with certain molecular weight ranges, it is expedient to carry out the polymerization in the presence of a regulator.
• a regulator Formaldehyde dialkyl acetals having 3 to 9, preferably 3, 4 or 5 carbon atoms, e.g. Formaldehyde dimethyl acetal, diethyl acetal, dipropylacetal and di-butyl acetal, as well as lower aliphatic alcohols, preferably alkanols with 1 to 4 carbon atoms, e.g. Methanol, ethanol, propanol and butanol.
• the regulator is usually used in an amount of up to 0.5 percent by weight, preferably from 0.005 to 0.1 percent by weight, based on the total amount of the compounds to be polymerized.
• the oxymethylene polymers are expediently subjected to thermal, controlled, partial degradation to primary alcohol end groups in order to remove unstable fractions (cf. US Pat. Nos. 31 74 948, 32 19 623 and 36 66 714).
• the thermal treatment is carried out at a temperature of 130 to 200 ° C, preferably 140 to 190 ° C, especially under non-acidic conditions in aqueous / methanolic solution, advantageously in the presence of a basic reaction compound, for example a lower tertiary aliphatic amine such as triethyl or Triethanolamine or a secondary alkali phosphate such as disodium hydrogen phosphate.
• a temperature of 150 to 180 ° C is particularly favorable.
• the duration of the thermal treatment is 10 seconds to 2 hours, preferably 1 minute to 60 minutes, depending on the temperature. The higher the temperature, the shorter it can be Dwell time. At 180 ° C approximately 1 to 2 minutes are sufficient, at 160 ° C approximately 5 to 10 minutes, at 150 ° C approximately 10 to 30 minutes and at 140 ° C approximately 20 to 60 minutes.
• the treatment is preferably carried out with the substantial exclusion of oxygen.
• a solution or a dispersion of an oxymethylene polymer, the polymer content of which is 3 to 35, preferably 5 to 30, percent by weight is used as the starting material for the process according to the invention. Very good results are obtained with a polymer solution or dispersion which contains 10 to 20 percent by weight of oxymethylene polymers.
• a methanol / water mixture with a methanol content of at least 75 percent by weight is used as the solvent or dispersant; preferably a mixture is used which consists of 99.9 to 80 percent by weight of methanol and 0.1 to 20 percent by weight of water.
• a mixture of 99.5 to 85 percent by weight of methanol and 0.5 to 15 percent by weight of water is particularly advantageous, the best results being obtained with a mixture of 99 to 90 percent by weight of methanol and 1 to 10 percent by weight of water.
• the temperature of the solution or dispersion is 5 to 65 ° C, preferably 10 to 60 ° C above the sintering temperature of the oxymethylene polymer, the temperature range from 25 to 55 ° C above the sintering temperature being particularly advantageous.
• the coolant has a temperature of 1 to 10 ° C, preferably 1 to 5 C, in particular 2 to 4 ° C below the sintering temperature of the oxymethylene polymers.
• the amount of the precipitated oxymethylene polymer in the suspension resulting from the introduction of the polymer solution or dispersion is at most 25, preferably 5 to 15 percent by weight.
• the methanol used in the context of this invention can contain up to 30, preferably up to 10 percent by weight of methanol-soluble organic impurities which are usually formed as by-products in the synthesis of oxymethylene polymers, e.g. Formaldehyde, cyclic oligomers of formaldehyde, methylal, glycol, glycol formal, glycol monomethyl ether, glycol dimethyl ether and lower aliphatic alcohols, lower aliphatic esters and acetone.
• oxymethylene polymers e.g. Formaldehyde, cyclic oligomers of formaldehyde, methylal, glycol, glycol formal, glycol monomethyl ether, glycol dimethyl ether and lower aliphatic alcohols, lower aliphatic esters and acetone.
• the temperature is referred to, in which the gas to the methanol / water mixtures suspended solid polymer particles on the surface are soft and stick together, without completely melting.
• the sintering temperature depends on the composition and molecular weight of the polymer and also on the type of solvent or dispersion medium.
• the sintering temperature of the oxymethylene polymers used in the invention is in the range of 100 to 140 o C, in particular 125-135 ° C.
• the process according to the invention is carried out, for example, in an autoclave provided with a stirrer.
• the cooling and precipitating agent is initially introduced, and the solution or dispersion of the oxymethylene polymer is advantageously initiated by a heated dip tube or a nozzle in the precipitating agent, the latter wegun by agitation in turbulent loading is maintained g.
• the process can be carried out batchwise or continuously; in the case of continuous operation, the polymer suspension obtained is removed at the bottom of the autoclave to the extent that Solution or dispersion and optionally additional precipitant are added.
• the average residence time of the oxymethylene polymer in the precipitation vessel is 1 minute to 12 hours, preferably 2 to 120 minutes.
• the pressure is 5 to 40, preferably 8 to 30 bar.
• solid polymer particles with different grain sizes are formed by precipitation or agglomeration.
• the majority of the POM particles obtained consist of granular particles with a grain diameter of more than 70 ⁇ m, while a small amount consists of fine-grain particles with a grain diameter of preferably less than 50 ⁇ m (sieve analysis).
• the granular particles preferably have grain diameters of 100 to 1000 ⁇ m and in particular of 150 to 400 ⁇ m.
• the merge of the fine-grained product to be separated is generally less than 20 percent by weight, based on the total amount of solid polymer particles; the fine grain fraction is preferably less than 15 and in particular 3 to 10 percent by weight.
• the POM particles with a particle diameter of above 70 ⁇ m are separated by conventional separation processes, for example by filtration, Centrifuging or decanting, separated.
• the POM particles with a particle diameter of more than 70 ⁇ m can be removed from the remaining mixture with the aid of a separator, and the solvent can be reused as a liquid coolant.
• the separated oxymethylene polymer is finally dried at a temperature of 20 to 135 ° C, preferably 50 to 120 ° C. Drying under an inert gas atmosphere, e.g. under an inert gas or nitrogen atmosphere, is recommended. It is also possible to separate the total amount of solid polymer particles from the liquid and to carry out the separation according to particle size during or after drying, for example by means of wind screens or sieving.
• the granular oxymethylene polymers obtained according to the invention are macromolecular; the values of their reduced specific viscosity (RSV) are 0.3 to 2.0, preferably 0.5 to 1.5 dl / g (measured on a 0.5% by weight solution of the polymer in y-butyrolactone, the 2% by weight diphenylamine as stabilizer contains, at a temperature of 140 ° C).
• the crystallite melting points of the oxymethylene polymers are in the range from 140 to 180 ° C, their melt index values (MFI 190/2) are 0.1 to 50, preferably 1 to 30 g / 10 min (measured according to DIN 53 735 at a temperature of 190 ° C and a load of 2.16 kg).
• the bulk density of the granular oxymethylene polymers obtained according to the invention is generally more than 300, preferably 350 to 550 g / l (determined on the polymer dried under nitrogen at a temperature of 70 ° C. after two minutes of homogeneous mixing in a laboratory fluid mixer at a speed of 3000 rpm).
• the RSV values of the separated fine-grained products are below 0.3 dl / g and are preferably 0.05 to 0.25 and in particular 0.1 to 0.2 dl / g.
• the oxymethylene copolymers obtained according to the invention can additionally be stabilized by homogeneously mixing them with stabilizers against the influence of heat, oxygen and / or light.
• the homogenization is usually carried out in a commercially available mixing device, for example an extruder, at a temperature above the melting point of the polymer up to 250 ° C., preferably at 180 to 210 ° C.
• the total amount of stabilizers added is 0.1 to 10, preferably 0.5 to 5 percent by weight, based on the total mixture.
• Bisphenol compounds, alkaline earth metal salts of carboxylic acids and guanidine compounds are particularly suitable as stabilizers.
• the bisphenol compounds used are primarily esters of mono- or di-core 4-hydroxyphenylalkanoic acids which are nucleus-substituted with a 1 to 4 carbon atom-containing alkyl radical and contain 7 to 13, preferably 7.8 or 9 carbon atoms, with aliphatic di-, tri- or tetra-alcohols containing 2 to 6, preferably 2, 3 or 4 carbon atoms, for example Esters of w - (3-tert-butyl-4-hydroxy-phenyl) -pentanoic acid, ß- (3-methyl-5-tert-butyl-4-hydroxy-phenyl) -propionic acid, (3,5-ditert .-Butyl-4-hydroxyphenyl) acetic acid, ß- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid or (3,
• alkaline earth metal salts of carboxylic acids used are, in particular, alkaline earth metal salts of aliphatic, preferably hydroxyl-containing, mono-, di- or tri-base carboxylic acids having 2 to 20, preferably 3 to 9 carbon atoms, e.g. the calcium or magnesium salts of stearic acid, ricinoleic acid, lactic acid, mandelic acid, malic acid or citric acid.
• guanidine compounds used in which R represents a hydrogen atom, a cyano group or an alkyl radical having 1 to 6 carbon atoms, for example cyanoguanidine, N-cyano-N'-methyl-guanidine, N-cyano-N'-ethyl-guanidine, N-cyano-N '-iso-propylguanidine, N-cyano-N'-tert-butyl-guanidine or N, N'-dicyanoguanidine.
• the guanidine compound is optionally used in an amount of 0.01 to 1, preferably 0.02 to 0.5 percent by weight, based on the total mixture.
• Known light stabilizers such as benzophenone, acetophenone or trjazine derivatives can also be added to the oxymethylene polymers prepared according to the invention.
• Other conventional additives such as dyes, pigments, reinforcing and filling agents or nucleating agents can also be added.
• the oxymethylene polymers obtained according to the invention are characterized in that they have improved mechanical properties, in particular toughness properties, compared to known oxymethylene polymers. They can be processed by all the usual methods for thermoplastics, e.g. by injection molding, extrusion, extrusion blow molding, melt spinning and deep drawing. They are suitable as a material for the production of semi-finished and finished parts such as moldings, e.g. Ingots, rods, plates, tapes, bristles, threads, fibers, films, foils, pipes and hoses, as well as household items, e.g. Bowls and cups, and machine parts, e.g. Housings and gears. They can be used primarily as a technical material for the production of dimensionally stable and dimensionally stable molded parts.
• Products A and B are dried at 70 ° C under nitrogen. The bulk weights and RSV values of the dried products are then determined. Part of the products are then mixed with stabilizers (0.1% dicyandiamide; 0.5% bis (2-hydroxy-3-tert.butyl-5- methyl-phenyl) -methane) and injection molded into test specimens.
• the impact behavior is tested in accordance with DIN 53 443 in a dart bolt test.
• Square plates with an edge length of 60 mm and a thickness of 2 mm as well as a drop bolt with a weight of 100 g are used for this; the ring opening of the contact surface is - in deviation from the norm - 25 mm.
• the determined head is a measure of the toughness of the material.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Polyoxymethylene Polymers And Polymers With Carbon-To-Carbon Bonds (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Processes Of Treating Macromolecular Substances (AREA)

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• 1977
  • 1977-08-10 DE DE2735946A patent/DE2735946C3/de not_active Expired
• 1978
  • 1978-08-01 EP EP78100565A patent/EP0000765B1/fr not_active Expired
  • 1978-08-01 DE DE7878100565T patent/DE2860773D1/de not_active Expired
  • 1978-08-08 US US05/931,985 patent/US4195158A/en not_active Expired - Lifetime
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