Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
  • B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
  • B22C1/14—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives for separating the pattern from the mould
• • 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
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/42—Block-or graft-polymers containing polysiloxane sequences
  • C08G77/442—Block-or graft-polymers containing polysiloxane sequences containing vinyl polymer sequences
• • 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
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/38—Polysiloxanes modified by chemical after-treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
  • B22D17/20—Accessories: Details
  • B22D17/2007—Methods or apparatus for cleaning or lubricating moulds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D29/00—Removing castings from moulds, not restricted to casting processes covered by a single main group; Removing cores; Handling ingots
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/56—Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
  • B29C33/60—Releasing, lubricating or separating agents
  • B29C33/62—Releasing, lubricating or separating agents based on polymers or oligomers
  • B29C33/64—Silicone
• • 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
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
• • 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
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/06—Preparatory processes
• • 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
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/06—Preparatory processes
  • C08G77/08—Preparatory processes characterised by the catalysts used
• • 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
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/12—Polysiloxanes containing silicon bound to hydrogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
  • C08L83/04—Polysiloxanes
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M155/00—Lubricating compositions characterised by the additive being a macromolecular compound containing atoms of elements not provided for in groups C10M143/00 - C10M153/00
  • C10M155/04—Monomer containing boron
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M173/00—Lubricating compositions containing more than 10% water
  • C10M173/02—Lubricating compositions containing more than 10% water not containing mineral or fatty oils
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2229/00—Organic macromolecular compounds containing atoms of elements not provided for in groups C10M2205/00, C10M2209/00, C10M2213/00, C10M2217/00, C10M2221/00 or C10M2225/00 as ingredients in lubricant compositions
  • C10M2229/04—Siloxanes with specific structure
  • C10M2229/041—Siloxanes with specific structure containing aliphatic substituents
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2229/00—Organic macromolecular compounds containing atoms of elements not provided for in groups C10M2205/00, C10M2209/00, C10M2213/00, C10M2217/00, C10M2221/00 or C10M2225/00 as ingredients in lubricant compositions
  • C10M2229/04—Siloxanes with specific structure
  • C10M2229/044—Siloxanes with specific structure containing silicon-to-hydrogen bonds
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2040/00—Specified use or application for which the lubricating composition is intended
  • C10N2040/36—Release agents or mold release agents

Definitions

• This invention relates to new silicones, processes for the production thereof and their uses, e.g., as die casting lubricants.
• Waxes are commonly used in pressure die casting release agents, mostly as aqueous emulsions, to provide good lubrication and release, especially for larger and heavy castings.
• waxes leads to build-up of wax on the spray nozzles, which eventually blocks them and requires regular extensive cleaning of the spray equipment.
• due to residual wax sticking to the mold, such processes necessitate also regular cleaning of the molds with concomitant downtime of the casting equipment.
• the use of waxes can entail excessive cleaning of the castings in order to achieve satisfactory painting or plating thereof.
• US 6,635,606 B2 discloses a release agent being an aqueous emulsion comprising a mixture of a dimethyl silicone and an alkyl-modified silicone having an alkyl chain of 6-18 carbon atoms, surfactant, and water.
• the kinematic viscosity of the alkyl-modified silicone is 100-3000 cSt at 25 °C.
• US 6,21 1 ,323 B1 relates to triorganosiloxy-endblocked poly(methyl(C6-C40alkyl)siloxane)- poly(methyl(aralkyl)siloxane)-poly(methyl(C2-C4alkyl)siloxane) terpolymers and their use as release agents.
• US 2005/0167071 A1 discloses die cast release agents for lubricating at die cast mold comprising a silicone wax compound having a molecular weight from 9,000 to 50,000 and a melting point of about 90 to 220 °F, wherein the silicone wax compound has alkyl side groups having at least 18 carbon atoms.
• a silicone wax compound having a molecular weight from 9,000 to 50,000 and a melting point of about 90 to 220 °F
• the silicone wax compound has alkyl side groups having at least 18 carbon atoms.
• wax-free pressure die casting release agents have been marketed based on polysiloxanes functionalized with medium length alkyl groups.
• all these lubricants are not able to compete fully with wax containing products, especially in large heavy castings.
• the present invention thus relates to a mixture of polyalkylsiloxanes obtainable through a hydrosilylation reaction wherein a mixture of monounsaturated olefins consisting of
• each polyalkylhydrosiloxane comprises a repeating unit according to the general structure (I):
• n the number of repeating units being in a range of from 5 to 10,000;
• residue R being selected from linear or branched alkyl groups with less than 6 carbon atoms.
• the present invention relates to a polyalkylsiloxane comprising repeating units according to general structure (II):
• n indicates the number of repeating units comprised in the polyalkylsiloxane, wherein n is an integer of 5 to 10,000 and residue R is selected from the group consisting of linear or branched alkyl groups with less than 6 carbon atoms,
• a) in 1 -20 % of the repeating units R 2 is selected from the group consisting of linear or branched alkyl groups with 40 to 60 carbon atoms, in 1 -20 % of the repeating units R 2 is selected from the group consisting of linear or branched alkyl groups with 16 to 30 carbon atoms, and
• R 2 is selected from the group consisting of linear or branched alkyl groups with 6 to 15 carbon atoms,
• the present invention relates to a water-based composition suitable for use in metal casting processes as a mold release agent comprising
• the present invention relates to the use of polyalkylsiloxanes as a mold release agent in a metal casting process, wherein i) the polyalkylsiloxanes are a mixture of polyalkylsiloxanes as defined herein, ii) the polyalkylsiloxanes are polyalkylsiloxanes as defined herein, or iii) the polyalkylsiloxanes comprise a repeating unit according to the following general structure (III):
• n indicates the number of repeating units being in a range of from 5 to 10,000; wherein for each repeating unit the residue R is independently selected from linear alkyl groups with less than 6 carbon atoms; and wherein for each repeating unit the residue R 2 is independently selected from hydrogen or linear or branched alkyl groups having 6 to 15 carbon atoms, 16 to 30 carbon atoms or 40 to 60 carbon atoms, while the fraction of repeating units with a residue R 2 being hydrogen is less than 0.1 , being a linear or branched alkyl group having 16 to 30 is in a range of from 0.01-0.2, being a linear or branched alkyl group having 40 to 60 carbon atoms is in a range of from 0.01-0.2, and being a linear or branched alkyl group having 6 to 15 carbon atoms is in a range of from 0.6-0.98.
• the inventive lubricant shows better performance compared to current wax-free die casting lubricants.
• These new and improved polyalkylsiloxane derivatives may be in the form of silicone oil.
• This compound may be directly used as a lubricant or included in a wax-free release agent for pressure die casting.
• the new polyalkylsiloxane derivatives are particularly advantageous in water-based emulsions.
• the present invention relates to a modified polysiloxane which is prepared by hydrosilylation of polymethylhydrosiloxane with a mixture of short (C6-C15), medium (C16-C30), and long a-olefins (> C40, preferably C40-C60) according to state of the art methodology.
• the ratio of the constituting ⁇ -olefins is chosen such to provide a modified polysiloxane with a high content of long alkyl groups while keeping the polysiloxane liquid with a kinematic viscosity of 200-20000 mPa-s at 25 °C.
• the thus formed modified polysiloxanes can be applied in wax-free die casting release agent.
• the modified polysiloxanes can be directly applied to the mold.
• the modified polysiloxanes are included in an aqueous emulsion.
• the die casting release agent may be an aqueous emulsion comprising the modified polysiloxane (5-50 wt.-%), a surfactant mixture (1 -15 wt.-%) and water adding up to 100 wt.-%.
• the modified polysiloxane is prepared as follows:
• the modified silicone oil is prepared by addition of the appropriate mixture of ⁇ -olefins to polymethylhydrosiloxane using a platinum catalyst giving a Si-H conversion of >94%.
• the modified polysiloxane may be a polymethylsiloxane functionalized with a mixture of long alkyl groups (>C40, preferably C40-C60, 1-20 mol%), medium sized alkyl groups (C16-C30, 1 -20 mol%), and the remainder with short alkyl groups (C6-C15).
• the modified polysiloxane preferably has a kinematic viscosity below 20000 mPa-s, preferably below 7000 mPa s at 25 °C to allow successful emulsification.
• the present invention relates to mixture of polyalkylsiloxanes obtainable through a hydrosilylation reaction wherein a mixture of monounsaturated olefins consisting of
• each polyalkylhydrosiloxane comprises a repeating unit according to the general structure (I):
• n indicating the number of repeating units being in a range of from 5 to 10,000; with the residue R being selected from linear or branched alkyl groups with less than 6 carbon atoms.
• olefin refers to monounsaturated olefins, hydrocarbons having a single ethylenic double bond such as normal and branched chain aliphatic olefins. Olefins do not comprise double unsaturated bonds.
• short olefin or alkyl relates to C6-C15 olefins or alkyls.
• intermediate olefins or alkyls relates to C16-C30 olefins or alkyls.
• long olefins or alkyls relates to C40-C60 olefins or alkyls.
• mol% of olefin relates to the molar ratio of a short, medium, or long chain olefin in a reaction with regard to the total moles of olefin in the reaction.
• polyalkylhydrosiloxane refers to a polymer comprising repeating units according to a general structure (I). In certain embodiments, the polymer further comprises trimethyl groups as terminators.
• hydrosilylation also called catalytic hydrosilation, describes the addition of Si-H bonds across unsaturated bonds. Typically, the reaction is conducted catalytically and usually the substrates are unsaturated organic compounds. Alkenes and alkynes give alkyl and vinyl silanes. A platinum catalyst is usually employed.
• Olefins with 6 to 15 carbon atoms are preferably selected from the group of olefins with 10 to 14 carbon atoms. Most preferably, the olefin with 6 to 15 carbon atoms selected for use in the present invention is 1-dodecene.
• olefins consist of linear or branched alkyl groups with 40 to 60 carbon atoms.
• olefins consist of linear or branched alkyl groups with 16 to 30 carbon atoms.
• 60-96 mol% or 75-96 mol%, preferably 60-90 mol% or 75-90 mol% olefins consist of linear or branched alkyl groups with 6 to 15 carbon atoms.
• n is an integer of from 5 to 10,000, 5 to 7,000, or 5 to 5,000.
• n is an integer of from 5 to 2,500, 5 to 1 ,000, or 5 to 500. More preferably, n is an integer of from 5 to 250, 5 to 200, 5 to 100. Even more preferably, n is an integer of from 5 to 50, 5 to 40, 5 to 30, 5 to 29, 5 to 28, 5 to 27, 5 to 26, or 5 to 25.
• R is selected from the group consisting of methyl, ethyl, linear or branched C3-C5 alkyl. In some embodiments, R is selected from the group consisting of methyl, ethyl, n- propyl, 1 -methyl-ethyl, n-butyl, tert-butyl, 1 -methyl propyl, 2-methyl propyl, n-pentyl, 2-pentyl, 3- pentyl, 2-methyl butyl, 3-methyl butyl, 3-methyl but-2-yl, 2-methyl but-2-yl, and 2, 2, -dimethyl propyl. In certain embodiments, R is selected from the group consisting of H, ethyl, n-propyl, 1 -methyl ethyl. In certain embodiments, R is H.
• the resulting mixture of polyalkylsiloxanes is an oil.
• the mixture of polyalkylsiloxanes is obtained in a hydrosilylation reaction being conducted with an amount of polyalkylhydrosiloxanes that equals at least 60 %, preferably at least 80 % of the stoichiometric amount, but preferably equals not more than the stoichiometric amount.
• the reaction is performed with an amount of polyalkylhydrosiloxanes that equals at least 60 %, 70 %, 80 %, 90 % , 95 %, 97,5 %, 99 %, or 99,5 % of the stoichiometric amount.
• the mixture of polyalkylsiloxanes is obtained in a hydrosilylation reaction being conducted with polyalkylhydrosiloxanes that are at least partially selected from polymethylhydrosiloxanes, and preferably with polyalkylhydrosiloxanes wherein at least 80 mol% of the repeating units according to the general structure (I) have a residue R being a methyl group.
• polyalkylhydrosiloxanes are employed, wherein at least 80, 85, 95, 97,5, 98, 99, or 99,5 mol% of the repeating units according to the general structure (I) have a residue R being a methyl group.
• the mixture of polyalkylsiloxanes is obtained in a hydrosilylation reaction wherein at least 80 mol% of the monounsaturated olefins are selected from a-olefins.
• the mixture of polyalkylsiloxanes is obtained in a hydrosilylation reaction wherein at least 80 mol%, 90 mol %, 95 mol%, 97,5 mol%, 99 mol%, or 99,5 mol% of the monounsaturated olefins are selected from a-olefins.
• the mixture of polyalkylsiloxanes is obtained in a hydrosilylation reaction wherein the hydrosilylation catalyst is a platinum catalyst.
• the platinum catalyst may be selected from the group consisting of chloroplatinic acid , alcohol modified chloroplatinic acids, olefin complexes of chloroplatinic acid, complexes of chloroplatinic acid and divinyltetramethyldisiloxane, fine platinum particles adsorbed on carbon carriers, platinum black, platinum acetylacetonate, platinous halides exemplified by PtCb, PtCU, Pt(CN)2, complexes of platinous halides with unsaturated compounds exemplified by ethylene, propylene, and organovinylsiloxanes, styrene hexamethyldiplatinum, RhCl3(Bu2S)3, speier's catalyst, and karstedt's catalyst.
• the platinum catalyst is speier's or
• the mixture of polyalkylsiloxanes is obtained in a hydrosilylation reaction wherein the reaction mixture is kept at temperature in the range of from 80 to 180 °C, preferably for a time sufficient to yield a mixture of polyalkylsiloxanes that contains not more than 10 mol% Si-H bonds.
• the reaction is carried out for a time sufficient to yield a mixture of polyalkylsiloxanes containing not more than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 mol% Si-H bonds.
• the reaction is carried out for a time sufficient to yield a mixture of polyalkylsiloxanes containing not more than 6 mol% Si-H bonds.
• the mixture of polyalkylsiloxanes is obtained in a hydrosilylation reaction wherein the weight fraction of an inert liquid vehicle that acts as a solvent for the amount of the one or more polyalkylhydrosiloxanes and/or the mixture of monounsaturated olefins may be less than 20 wt.-%, preferably less than 10 wt.-%, more preferably less than 1 wt.-%.
• Suitable inert liquid vehicles may be selected from, but not limited to, aprotic solvents, such as toluene or tetrahydrofurane.
• the reaction is preferably carried without any such inert liquid vehicle. Any residual solvent is preferably removed after completion of the reaction.
• the catalyst may be removed from the reaction mixture by methods known in the art
• the mixture comprises polyalkylsiloxanes wherein the ratio of R 2 falling within the scope of linear or branched alkyl groups having 16 to 30 carbon atoms and linear or branched alkyl groups having 40 to 60 carbon atoms is in the range of from 2 : 3 to 3 : 2.
• the polyalkylsiloxanes comprise repeating units wherein some substituents R 2 fall within the scope of linear or branched alkyl groups with 40 to 60 carbon atoms and other substituents R 2 falling within the scope of linear or branched alkyl groups with 16 to 30 carbon atoms.
• the present invention relates to a polyalkylsiloxane comprising repeating units according to general structure (II):
• n indicates the number of repeating units comprised in the polyalkylsiloxane, wherein n is an integer of 5 to 10,000 and residue R is selected from the group consisting of linear or branched alkyl groups with less than 6 carbon atoms,
• a) in 1-20 % of the repeating units R 2 is selected from the group consisting of linear or branched alkyl groups with 40 to 60 carbon atoms,
• R 2 in 1-20 % of the repeating units R 2 is selected from the group consisting of linear or branched alkyl groups with 16 to 30 carbon atoms, and
• c) in 60-98 % of the repeating units R2 is selected from the group consisting of linear or branched alkyl groups with 6 to 15 carbon atoms,
• the percentages of the repeating units as defined in a)-d) add up to 100 %.
• the percentages given relate to the total number of repeating units in the polyalkylsiloxane.
• R 2 of group a) is selected from the group consisting of linear or branched alkyl groups with 40 to 60 carbon atoms. In 1 -20% of the repeating units R 2 is chosen from group a).
• R 2 of group b) is selected from the group consisting of linear or branched alkyl groups with 16 to 30 carbon atoms. In 1 -20% of the repeating units R 2 is chosen from group b).
• R 2 of group c) is selected from the group consisting of linear or branched alkyl groups with 6 to 15 carbon atoms. In 60-98% of the repeating units R 2 is chosen from group c).
• R 2 of group d) is H. In 0-10%, preferably less than 10 %, of the repeating units R 2 is chosen from group d).
• R of general structure (II) is defined identical to R in general structu
• the polyalkylsiloxane has a kinematic viscosity of 200 to 20000 mPa s at 25 °C, preferably of 200 to 7000 mPa-s at 25 °C.
• kinematic viscosity refers to a viscosity which is determined by measuring the dynamic viscosity ⁇ , and dividing the dynamic viscosity ⁇ by the density of the fluid p. Methods for determining the dynamic viscosity are well known in the art.
• the polyalkylsiloxane is defined as above, wherein for fraction c) R 2 is selected from the group consisting of linear or branched alkyl groups with 10 to 14 carbon atoms.
• R2 of fraction c) is selected from the group consisting of hexyl, heptyl, octyl, nonyl, decly, undecyl, and dodecyl.
• R2 of fraction c) is dodecyl.
• repeating units according to fraction a), i.e. having an R 2 that is a linear or branched alkyl group with 40 to 60 carbon atoms make up 2-10%, preferably about 5 % of the total repeating units in the polyalkylsiloxane.
• repeating units with R 2 falling within the scope of fraction b) make up 2- 15 %, preferably about 5 % of the total repeating units in the polyalkylsiloxane.
• repeating units with R 2 falling within the scope of fraction c) make up 60- 96 % or 75-96 %, preferably 60-90 % or 75-90% of the total repeating units in the polyalkylsiloxane.
• the molar ratio of fraction a) to fraction b) is in the range of from 2:3 to 3:2.
• substituent R of each repeating unit according to general structure (II) is a methyl group. In further embodiments, in at least 80 % of the repeating units according to general structure (II) R is a methyl group. In certain embodiments, in at least 80, 90, 95, 97,5, 99, or 99,5 % of the repeating units according to general structure (II) R is a methyl group.
• the polyalkylsiloxane of the present invention is an oil.
• the polyalkylsiloxane can be used as die casting lubricant without further additives.
• the modified polysiloxane may be included in a water-based emulsion in combination with a suitable surfactant and water.
• the water-based emulsion comprises a surfactant mixture.
• the surfactant mixture comprises emulsifying agents which are able to form stable emulsions with the modified polysiloxanes.
• the surfactant mixture may be a mixture of ethoxylated oxo- alcohols.
• ethoxylation refers to the addition of ethylene oxide to alcohols to give a surfactant.
• oxo alcohols means alcohols that are prepared by adding carbon monoxide (CO) and hydrogen to an olefin to obtain an aldehyde using the hydroformylation reaction and then hydrogenating the aldehyde to obtain the alcohol.
• ethoxylated oxo-alcohols relates to oxo-alcohols which have undergone ethoxylation.
• a surfactant for use in the water-based emulsion may be a mixture of polysorbate 85 and ethoxylated (6-8) tridecyl alcohol.
• the ethoxylated oxo-alcohols are used in the water-based emulsion at weight ratios of 1 :4 to 1 : 10 with respect to the modified polysiloxane.
• surfactants either anionic, nonionic and/or cationic may be used in the water-based emulsion.
• the present invention also relates to a water-based composition suitable for use in metal casting processes as a mold release agent comprising a) 1-50 wt.-% of a mixture of polyalkylsiloxanes or polyalkylsiloxane as defined herein, b) 1-15 wt.-% of a non-ionic surfactant having a HLB value of at least 8, and c) less than 20 wt.-%, preferably less than 10 wt.-% of waxes.
• the mold release agent preferably comprises less than 1 wt.-%, more preferably less than 0.1 wt.-%, especially preferred less than 0.01 wt.-% of waxes.
• the content of modified polysiloxane in the aqueous emulsion is 1- 50 wt.- %, preferably 5-50 wt.-%, more preferably 5-30 wt.-%.
• the content of surfactant in the aqueous emulsion may be 1-15%, preferably 5-15 wt.- %, more preferably 5-10 wt.-%.
• wax or "waxes” as used herein relates to a class of organic chemical compounds that are insoluble in water and are plastic (malleable) at 20 °C and melt above 45 °C to give a low viscosity liquid. Waxes are insoluble in water but soluble in organic, nonpolar solvents. All waxes are organic compounds, both synthetic and naturally occurring.
• plastic as used in connection with wax, relates to its deformation when undergoing nonreversible changes of shape in response to applied forces.
• malleable refers to the ability of wax to deform under compressive stress.
• waxes being used in prior art mold- release compositions are polyethylenes and polypropylenes that may be modified.
• modified in connection with polyethylenes and polypropylenes means esterified or saponified polyethylenes and polypropylenes.
• other components may be incorporated in the die casting release agent, e.g., corrosion inhibitors, antimicrobials, and emulsions of various natural or synthetic oils.
• the water-based composition according to the present invention is an oil-in-water emulsion.
• the release agent may be prepared by combining the modified polysiloxane, the emulsifier, and water using an appropriate emulsifying apparatus to produce a stable oil in water emulsion followed by addition of water and optional other constituents.
• the die casting release agent is preferably done by spray coating.
• the die casting release agent is employed in a dilution.
• the die casting release agent is employed in a 1-200 fold dilution, preferably 1 -100 dilution, 1-50 dilution, or 1-20 dilution.
• compositions are advantageous, because they have wax-like or even improved lubricating properties while being devoid of or almost devoid of wax.
• waxes are absent or almost absent, the compositions do not have the typical disadvantages connected with wax-based lubricants, e.g., the need of regular extensive cleaning of the spray equipment, i.e. spry nozzles.
• occurrence of residual wax sticking to the mold is avoided and the thereto connected need of regular cleaning of the molds with concomitant downtime of the casting equipment.
• excessive cleaning of the castings in order to achieve satisfactory painting or plating thereof is avoided.
• the water-based composition comprises non-ionic surfactants being a mixture of polysorbate 85 and ethoxylated (6-8) tridecyl alcohol.
• the water-based composition is an oil-in-water emulsion.
• the waxes are polyethylenes and/or polypropylenes which are either modified or not and are insoluble in water and are plastic (malleable) at 20 °C and melt above 45 °C.
• the present invention relates to the use of polyalkylsiloxanes as a mold release agent in a metal casting process, wherein i) the polyalkylsiloxanes are a mixture of polyalkylsiloxanes as defined herein, ii) the polyalkylsiloxanes are polyalkylsiloxanes as defined herein, or iii) the polyalkylsiloxanes comprise a repeating unit according to the following general structure
• n indicates the number of repeating units being in a range of from 5 to 10,000; wherein for each repeating unit the residue R is independently selected from linear alkyl groups with less than 6 carbon atoms; and wherein for each repeating unit the residue R 2 is independently selected from hydrogen or linear or branched alkyl groups having 6 to 15 carbon atoms, 16 to 30 carbon atoms or 40 to 60 carbon atoms, while the fraction of repeating units with a residue R 2 being hydrogen is less than 0.1 , being a linear or branched alkyl group having 16 to 30 is in a range of from 0.01-0.2, being a linear or branched alkyl group having 40 to 60 carbon atoms is in a range of from 0.01 -0.2, and being a linear or branched alkyl group having 6 to 15 carbon atoms is in a range of from 0.6- 0.98.
• R is defined as for general structure (I) and (II).
• R 2 may be defined as for the polyalkylsiloxanes of the invention described above.
• R 2 may be selected from the group consisting of linear or branched alkyl groups with 10 to 14 carbon atoms.
• R2 is selected from the group consisting of hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl.
• R2 is dodecyl.
• residue R of each repeating unit according to general structure (III) is a methyl group. In further embodiments, residue R of at least 80 % of the repeating units according to general structure (III) is a methyl group. In certain embodiments, residue R of at least 80, 90, 95, 97,5, 99, or 99,5 % of the repeating units according to general structure (III) is a methyl group.
• the use of polyalkylsiloxanes as a mold release agent in a metal casting process concerns polyalkylsiloxanes as defined above, wherein the fraction of repeating units according to the general structure (III) with R 2 being a linear or branched alkyl group having 16 to 30 carbon atoms is at least 0.02, preferably at least 0.05, but preferably not higher than 0.15; the fraction of repeating units according to the general structure (III) with the R 2 being a linear or branched alkyl group having 40 to 60 carbon atoms is at least 0.02, preferably at least 0.05, but preferably not higher than 0.10; and/ or the fraction of repeating units according to the general structure (III) with the residue R 2 being a linear or branched alkyl group having 6 to 15 carbon atoms is not higher than 0.96, preferably not higher than 0.90, but preferably at least 0.75.
• repeating units with R 2 falling within the scope of linear or branched alkyl groups with 40 to 60 carbon atoms have a fraction of 0.02-0.10, preferably about 0.05.
• repeating units with R 2 falling within the scope of linear or branched alkyl groups with 16 to 30 carbon atoms have a fraction of 0.02-0.15, preferably about 0.05.
• repeating units with R 2 falling within the scope of linear or branched alkyl groups with 6 to 15 carbon have a fraction of 0.60-0.96 or 0.75-0.96, preferably 0.60-0.90 or 0.75- 0.90.
• polyalkylsiloxanes for use according to the present invention are preferably an oil.
• modified polymethylsiloxane 30.5 g was added to an emulsifier mixture (14.3 g). Under vigorous stirring, water was added to create the inversion point (7.0 g). Additional modified polymethylsiloxane (59.1 g) was added slowly under vigorous stirring. After 10 minutes water (89.1 g) was added slowly followed by addition of Acticide MV14 (Thor Chemie, 0.02 g). 76 gram of this emulsion was added to a mixture of Mayco base RP8765 (Dover Chemical Corporatin, 2.6 g) and water (120.5 gram). To this mixture was added SAG 10E (Momentive, 0.1 gram) and Acticide MBS (Thor Chemie 0.8 g).
• the pressure die casting emulsion was tested against the wax-containing lubricant Deltacast CP- 579 (23% solids, 0.8% dilution in water) which gives lubricant build-up during its use.
• the new lubricant (17% solids, 1.0% dilution in water) gave good release and afforded good clean castings without observable lubricant build-up on the die or spray nozzles.

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