LIQUID MONOFUNCTIONAL 1,3-DIOXOLANE COPOLYMERS

Description

[0001] The invention relates to monofunctional 1,3-dioxolane copolymers of 1,3-dioxolane and alkyl-substituted 1,3-dioxolane and a process for their preparation.

[0002] The serious contribution of increased CO2 emissions to climate change is undisputed, and not only since the signing of the Paris Climate Agreement has the reduction of CO2 emissions been an important lever for stopping the rise in the global average temperature.

[0003] Plastics production also releases significant amounts of CO2 into the atmosphere. According to projections by the EIT Climate KIC, by 2050, 15–20% of global CO2 emissions will be attributable to plastics production alone. One way to counteract this trend is to harness CO2 in plastics production and integrate CO2 into the value chain as a feedstock rather than waste. In this context, polyacetals represent an attractive class of plastics that can be produced via the intermediate stage of cyclic acetals, among other processes, through the catalytic fixation of CO2 with green hydrogen.

[0004] However, conventional polyacetals, also called polyoxymethylenes (POM), such as those obtained by polymerizing formaldehyde or trioxane (POM-H) or by ring-opening polymerization of 1,3-dioxolane (POM-C), are solid at room temperature because the polymers contain crystalline regions and an associated melting point, which, depending on the application, complicates further processing. The ability to produce liquid representatives of this material class would significantly expand the application range of polyacetals.

[0005] During synthesis, conventional polyoxymethylenes are terminated with alkyl groups. This stabilizes the polymers, but simultaneously prevents functionalization or further reaction.

[0006] Equipping the polymers with additional functional groups that enable polymer-analogous reactions on the polyacetal would also expand the application spectrum of the materials, as they could be transformed into attractive hybrid materials through simple organic reactions. Monofunctional polymers are particularly advantageous for the preparation of these hybrid materials because they are not prone to crosslinking behavior.

[0007] In "One-Step Synthesis of Bis-Macromonomers of Poly(1,3-dioxolane) Catalyzed by Maghnite-H+," J. Appl. Polym. Sci., Vol. 99, 3147-3152 (2006), Lutz et al. describe the preparation of α,ω-bisfunctional polydioxolanes by acid-catalyzed ring-opening polymerization of 1,3-dioxolane in the presence of methacrylic anhydride. However, this method fails to yield either monofunctional or liquid products.

[0008] A similar synthesis is also described by Goethals et al., "Polymer Networks Based on α,ω-Methacrylate-Terminated Poly(l,3-dioxolane)," Polym. Int., Vol. 38, 89-94 (1995). Methylene bis(oxyethyl methacrylate) acts as the initiator and chain termination of an acid-catalyzed ring-opening polymerization of 1,3-dioxolane, resulting in bisfunctional, α,ω-methacrylate-terminated, solid polydioxolane.

[0009] WO14095971 A2 describes the polymerization of trioxane and cyclic acetals starting from bifunctional polyols, whereby the terminal OH groups of the polyacetal are subsequently terminated using glutaric anhydride to yield carboxylic acid-terminated polymers. Solid products are obtained.

[0010] The object of the present invention was therefore to obtain liquid, monofunctional polyacetals over a wide temperature range, which can be realized from cyclic acetals.

[0011] The invention relates to 1,3-dioxolane copolymers of the general formula I H- [O-CH 2 -O-CH 2 -CH 2 -] x1 [O-CH 2 -CH 2 O-CH 2 -] x2 [O-CH 2 -O-CHR 1< -CHR 2< -] y1 [O-CHR 1< -CHR 2< O-CH 2 -] y2 O R 3< (I), in the x1+x2 Values ​​from 10 to 2000 mean R 1< and R 2< hydrogen radicals or C 1 - to C 18 -alkyl radical, where in each case at least one radical R 1< or R 2< in the units [O-CH 2 -O-CHR 1< -CHR 2< -] y1 and [O-CHR 1< -CHR 2< O-CH 2 -] y2 represents a C 1 to C 18 alkyl radical, with the proviso that y1+y2 Values ​​from 3 * (x1+x2+y1+y2) / 100 to 50 * (x1+x2+y1+y2) / 100 means R 3< an aliphatically saturated or unsaturated hydrocarbon radical having 1 to 100 carbon atoms, which is unsubstituted or substituted by halogen atoms, amino groups, C 1-6 alkyl, C 1-6 alkoxy or silyl groups, in which one or more non-adjacent -CH 2 units may be replaced by -O-, -S-, C=O, -OC(O)-, or -NR 4< - groups and in which one or more non-adjacent =CH units may be replaced by -N= groups and R 4< a hydrogen radical or C 1 to C 18 alkyl radical.

[0012] The 1,3-dioxolane copolymers of the general formula I are polyacetals.

[0013] Through the targeted incorporation of impurities in the form of alkyl groups protruding from the polymer backbone of the 1,3-dioxolane copolymers of general formula I, the crystallinity of the polyacetal is eliminated, not merely reduced. Such amorphous behavior can be demonstrated by differential scanning calorimetry measurements when only a glass transition point but no melting point is present.

[0014] The copolymers are composed of 1,3-dioxolane and 1,3-dioxolane substituted at the 4- and / or 5-position. They are liquid over a wide temperature range and therefore very suitable for further processing.

[0015] They preferably have a glass transition between -50°C and -70°C and particularly preferably have no melting point. The copolymers have a decomposition onset >100°C, in particular >110°C.

[0016] The 1,3-dioxolane copolymers have the units [O-CH 2 -O-CH 2 -CH 2 -] x1 , [O-CH 2 -CH 2 O-CH 2 -] x2 , [O-CH 2 -O-CHR 1< -CHR 2< -] y1 , [O-CHR 1< -CHR 2< O-CH 2 -] y2 , randomly or in blocks.

[0017] Preferably mean x1+x2 Values ​​from 20 to 1000, particularly preferably from 30 to 500, in particular from 50 to 300.

[0018] Examples of alkyl radicals R1< , R2< and R 4< are linear and branched alkyl radicals, such as methyl, ethyl, i-octyl, n-octyl, and cycloalkyl radicals, such as cyclohexyl. Preferably R1< , R2< and R 4< independently of one another, hydrogen radicals or C 1 to C 6 alkyl radicals, particularly preferably hydrogen radicals, methyl, ethyl, n-propyl or i-propyl radicals.

[0019] Preferably, only one residue R 1< or R 2< in the units [O-CH 2 -O-CHR 1< -CHR 2< -] y1 and [O-CHR 1< -CHR 2< O-CH 2 -] y2 a C 1 - to C 18 -alkyl radical.

[0020] R 3< preferably has 1 to 30, in particular 1 to 18 carbon atoms.

[0021] Examples of R 3< ,which represent an aliphatically saturated hydrocarbon radical are alkyl radicals, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, neopentyl, tert-pentyl radical; hexyl radicals, such as n-hexyl radical; heptyl radicals, such as n-heptyl radical; octyl radicals, such as n-octyl and isooctyl radicals, such as 2,4,4-trimethylpentyl radical; nonyl radicals, such as n-nonyl radical; decyl radicals, such as n-decyl radical; dodecyl radicals, such as n-dodecyl radical; Hexadecyl radicals, such as the n-hexadecyl radical; octadecyl radicals, such as the n-octadecyl radical; cycloalkyl radicals, such as the cyclopentyl, cyclohexyl, cycloheptyl, and methylcyclohexyl radicals; aryl radicals, such as the phenyl, naphthyl, anthryl, and phenanthryl radicals; alkaryl radicals, such as the o-, and p-tolyl, xylyl, mesitylenyl, and o-, m-, and p-ethylphenyl radicals; and alkaryl radicals, such as the benzyl radical, the α-, and β-phenylethyl radicals. In a preferred embodiment, R 3< an alkyl radical with 1 to 18 carbon atoms.

[0022] Examples of R 3< , which represent an aliphatically unsaturated hydrocarbon radical are alkenyl radicals and alkynyl radicals in which one or more non-adjacent -CH 2 units may be replaced by -O- or -OC(O)- groups. Preferred alkenyl radicals R 3< have 2 to 10 carbon atoms, such as vinyl, allyloxyethyl, propyl methacrylate, butyl methacrylate, methallyl, 1-propenyl, 5-hexenyl, ethynyl, butadienyl, hexadienyl, cyclopentenyl, cyclopentadienyl, cyclohexenyl, acrylate, and methacrylate; particularly preferred are vinyl, allyl, acrylate, methacrylate, allyloxyethyl, propyl methacrylate, and butyl methacrylate. Preferred alkenyl radicals R 3< Polyethylene glycols containing terminal alkenyl radicals are also examples.

[0023] Preferably means y1+y2Values ​​from 5 * (x1+x2+y1+y2) / 100 to 40 * (x1+x2+y1+y2) / 100, particularly preferably values ​​from 10 * (x1+x2+y1+y2) / 100 to 30 * (x1+x2+y1+y2) / 100, in particular values ​​from 14 * (x1+x2+y1+y2) / 100 to 25 * (x1+x2+y1+y2) / 100.

[0024] The 1,3-dioxolane copolymers preferably have a molecular weight Mw between 750 - 300,000, particularly preferably between 1,500 - 125,000, very particularly preferably between 2,200 - 63,000, in particular between 4,000 - 25,000.

[0025] The 1,3-dioxolane copolymers preferably have a dynamic viscosity at 25 °C between 50 mPas - 500 Pas, particularly preferably between 500 mPas - 200 Pas, in particular between 700 mPas - 50 Pas.

[0026] The 1,3-dioxolane copolymers of the above general formula I can be prepared in a simple manner and with short reaction times. Due to the production process, the 1,3-dioxolane copolymers of the above general formula (I) can also be mixed with proportions of copolymers in which the radical in the general formula (I) R 3< is replaced by a hydrogen atom or the hydrogen atom at the other end of the 1,3-dioxolane copolymers is replaced by a radical R 3< Preferably, the copolymers of the above general formula (I) are mixed with at most 5 mol%, particularly preferably at most 1 mol%, in particular at most 0.1 mol% of copolymers in which in the general formula (I) the radical R 3< is replaced by a hydrogen atom or the hydrogen atom at the other end of the 1,3-dioxolane copolymers is replaced by a radical R 3< is replaced.

[0027] The invention also relates to a process for the preparation of 1,3-dioxolane copolymers of the general formula (I) H- [O-CH 2 -O-CH 2 -CH 2 -] x1 [O-CH 2 -CH 2 O-CH 2 -] x2 [O-CH 2 -O-CHR 1< -CHR 2< -] y1 [O-CHR 1< -CHR 2< O-CH 2 -] y2 O R 3< (I), in the x1+x2 Values ​​from 10 to 2000 mean R 1< and R 2< hydrogen radicals or C 1 - to C 18 -alkyl radical, where in each case at least one radical R 1< or R 2< in the units [O-CH 2 -O-CHR 1< -CHR 2< -] y1 and [O-CHR 1< -CHR 2< O-CH 2 -] y2 represents a C 1 to C 18 alkyl radical, with the proviso that y1+y2 Values ​​from 3 * (x1+x2+y1+y2) / 100 to 50 * (x1+x2+y1+y2) / 100 means R 3< an aliphatically saturated or unsaturated hydrocarbon radical having 1 to 100 carbon atoms, which is unsubstituted or substituted by halogen atoms, amino groups, C 1-6 alkyl, C 1-6 alkoxy or silyl groups, in which one or more non-adjacent -CH 2 units may be replaced by -O-, -S-, C=O, -OC(O)-, or -NR 4< - groups and in which one or more non-adjacent =CH units may be replaced by -N= groups and R 4< a hydrogen radical or C 1 - to C 18 -alkyl radical, in which 1,3-dioxolane is reacted with alkyl-substituted 1,3-dioxolane of the general formula II in the presence of a Lewis or Brønstedt acid and an alcohol of the general formula R 3< OH is copolymerized, wherein the molar ratio of Lewis or Brønstedt acid to alcohol of the general formula R 3< OH is less than 1.

[0028] In the general formula II there are alkyl radicalsR 1< and R 2< in 4 and 5 position of the 1,3-dioxolanes.

[0029] The process is a ring-opening polymerization of dioxolane monomers by cationic catalysis. The catalyst is a Lewis or Brønsted acid. The alcohol R 3< OH has the function of an initiator.

[0030] Compared to classical methods, this process eliminates the need for subsequent functionalization of an α,ω-hydroxy-terminated polymer.

[0031] In the process, preferably at least 10 mol%, particularly preferably at least 20 mol%, in particular at least 30 mol% of alkyl-substituted 1,3-dioxolane of the general formula II are used, based on the total amount of 1,3-dioxolane and alkyl-substituted 1,3-dioxolane of the general formula II.

[0032] In the process, more alkyl-substituted 1,3-dioxolane of the general formula II must be used than is mathematically necessary to achieve a certain proportion of values y1+y2 to achieve.

[0033] Examples of acids are Lewis acids such as BF 3 , AlCl 3 , TiCl 3 , SnCl 4 , SO 3 , PCl 5 , POCl 3 , FeCl 3 and its hydrates and ZnCl 2 ; Brønstedt acids, such as boric, tetrafluoroboric, nitric, nitrous, phosphoric, phosphorous, hypophosphorous, sulfuric, sulfurous, peroxosulfuric, hydrochloric, hydrofluoric, hydroiodic, hydrobromic, perchloric, hexafluorophosphoric acid, aluminum chloride, zinc chloride, benzenesulfonic, p-toluenesulfonic, methanesulfonic, trifluoromethanesulfonic and carboxylic acids, such as chloroacetic, trichloroacetic, acetic, acrylic, benzoic, trifluoroacetic, citric, crotonic, formic, fumaric, maleic, malonic, gallic, itaconic, lactic, tartaric, oxalic, phthalic and succinic acid, acidic ion exchangers, acidic zeolites, acid-activated bleaching earth and acid-activated carbon black.

[0034] Trifluoromethanesulfonic acid is particularly preferred.

[0035] The process preferably takes place in the absence of water. This suppresses the formation of copolymers in which the radical in the general formula (I) R 3< is replaced by a hydrogen atom.

[0036] The process can be carried out in the presence or absence of aprotic solvents. If aprotic solvents are used, solvents or solvent mixtures with a boiling point or boiling range of up to 120°C at 0.1 MPa are preferred.Examples of such solvents are ethers such as dioxane, tetrahydrofuran, diethyl ether, methyl tert-butyl ether, diisopropyl ether, diethylene glycol dimethyl ether; chlorinated hydrocarbons such as dichloromethane, trichloromethane, carbon tetrachloride, 1,2-dichloroethane, trichloroethylene; hydrocarbons such as pentane, n-hexane, hexane isomer mixtures, heptane, octane, white spirit, petroleum ether, benzene, toluene, xylenes; siloxanes, in particular linear dimethylpolysiloxanes with trimethylsilyl end groups with preferably 0 to 6 dimethylsiloxane units, or cyclic dimethylpolysiloxanes with preferably 4 to 7 dimethylsiloxane units, for example hexamethyldisiloxane, octamethyltrisiloxane, octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane; Ketones such as acetone, methyl ethyl ketone, diisopropyl ketone, methyl isobutyl ketone (MIBK); esters such as ethyl acetate, butyl acetate, propyl propionate, ethyl butyrate, ethyl isobutyrate; carbon disulfide and nitrobenzene, or mixtures of these solvents.

[0037] The term "solvent" does not mean that all reaction components must be soluble in it. The reaction can also be carried out in a suspension or emulsion of one or more reactants. The reaction can also be carried out in a solvent mixture with a miscibility gap, where at least one reactant is soluble in each of the mixed phases.

[0038] Particularly preferred is a solution of trifluoromethanesulfonic acid and the initiator, with methylene chloride being used as the preferred solvent.

[0039] The amount of catalyst and initiator used determines the achievable molecular weight of the 1,3-dioxolane copolymer of general formula I.

[0040] The alcohol used as initiator R 3< OH regulates the desired chain length of the 1,3-dioxolane copolymers of the general formula (I).

[0041] The Lewis or Brønstedt acid is used in catalytic amounts to activate the initiator.

[0042] Preferably, the molar ratio of Lewis or Brønstedt acid to alcohol of the general formula R 3< OH between 0.5 and 0.001, especially between 0.1 and 0.01.

[0043] Preferably, 50 to 10,000 mol ppm, particularly preferably 100 to 5,000 mol ppm, in particular 200 to 4,000 mol ppm of Lewis or Brønstedt acid are used per mole of the sum of 1,3-dioxolane and alkyl-substituted 1,3-dioxolane of the general formula II.

[0044] Preferably, the Lewis or Brønstedt acid is reacted with the alcohol of the general formula R 3< OH before the mixture is added to the 1,3-dioxolane and alkyl-substituted 1,3-dioxolane of general formula II.

[0045] The process is preferably carried out at a temperature between 10 and 60 °C, more preferably between 15 and 40 °C, in particular between 21 and 30 °C. A reaction temperature of 23 °C is most preferred.

[0046] The reaction is preferably worked up by inactivating the catalyst using a suitable base, washing with a hydrocarbon such as heptane and drying under reduced pressure.

[0047] Pyridine, triethylamine or aqueous sodium hydroxide solution are preferred bases.

[0048] The polyacetals can be used as emulsifiers or as starting materials for the preparation of functional silicone oils or similar purposes.

[0049] In the following examples, unless otherwise stated, all quantities and percentages are based on weight, all pressures are 0.10 MPa (abs.) and all temperatures are 20°C. Examples Analytics for the entire invention:

[0050] NMR spectroscopy for the determination of the proportion of alkylethylene oxide bridges.

[0051] The measurement is performed in solution in CDCl3 on a Bruker Avance 500 or Ascend 500 (500 MHz for 1H spectrum). All measurements are referenced against TMS as an external standard. The relative ratios of the monomer units in the polymer are determined by integration of the respective signal sets.

[0052] In addition, the chain length and molecular mass of the polymer can be determined by integrating the end group signals.

[0053] SEC (Size-Exclusion Chromatography): for the determination of the number-average and mass-average molecular weights Mn, Mw and the polydispersity: The measurement is carried out against polystyrene standard, in THF, at 35°C, flow rate 0.3 ml / min and detection with RID (refractive index detector) on a PLgel MiniMIX-C Guard column from Agilent with an injection volume of 20 µl.

[0054] Rheometer for determining dynamic viscosity. The measurement is carried out on an Anton Paar MCR 320 rotational viscometer at 25 °C. The graphical evaluation is performed by plotting the viscosity against the shear stress.

[0055] DSC (Differential Scanning Calorimetry / Dynamic Difference Thermal Analysis) to determine the melting point and the glass transition temperature: The measurements were carried out on a DSC-1 instrument from Mettler Toledo in a temperature range of -150 °C to 150 °C in two runs with a heating and cooling rate of 10 K, whereby the second run was used to determine the melting point and the glass transition temperature.

[0056] TGA analysis to determine the onset of decomposition: The onset of decomposition was determined using a TGA-2 instrument from Mettler Toledo, where the sample was heated at a heating rate of 10 K / min under an oxygen atmosphere. Example 1:

[0057] Preparation of the catalyst solution: 10 ml of dry dichloromethane, 1.9 ml of allyloxyethanol, and 76 µl of trifluoromethanesulfonic acid are combined and stirred for 1 h at room temperature. 1.35 ml of the previously prepared catalyst solution is added to a flask and heated to 23 °C. Then, 10.12 g (96 mmol) of 4-ethyl-1,3-dioxolane (EDX) and 6.75 ml (96 mmol) of 1,3-dioxolane (DXL) are added and stirred.

[0058] After 4 h, pyridine is added until the reaction mixture becomes decolorized. The product is washed with heptane and distilled water and then dried under vacuum. Example 2:

[0059] 2.7 ml of the catalyst solution prepared in Example 1 are placed in a flask and heated to 23 °C. Subsequently, 10.12 g (96 mmol) of 4-ethyl-1,3-dioxolane (EDX) and 6.75 ml (96 mmol) of 1,3-dioxolane (DXL) are added and stirred.

[0060] After 4 h, pyridine is added until the reaction mixture becomes decolorized. The product is washed with heptane and distilled water and then dried under vacuum. Example 3:

[0061] 5.4 ml of the catalyst solution prepared in Example 1 are placed in a flask and heated to 23 °C. Subsequently, 10.12 g (96 mmol) of 4-ethyl-1,3-dioxolane (EDX) and 6.75 ml (96 mmol) of 1,3-dioxolane (DXL) are added and stirred.

[0062] After 4 h, pyridine is added until the mixture becomes decolorized. The product is washed with heptane and distilled water and then dried under vacuum. Example 4:

[0063] Preparation of the catalyst solution: 10 ml of dry dichloromethane, 5.15 g of hydroxypropyl methacrylate, and 152 µl of trifluoromethanesulfonic acid are combined and stirred for 1 h at room temperature. 4.05 ml of the previously prepared catalyst solution is added to a flask and heated to 23 °C. Then, 15.18 g (144 mmol) of 4-ethyl-1,3-dioxolane (EDX) and 10.12 ml (144 mmol) of 1,3-dioxolane (DXL) are added and stirred.

[0064] After 4 h, pyridine is added until the reaction mixture becomes decolorized. The product is washed with heptane and distilled water and then dried under vacuum. Example 5:

[0065] Preparation of the catalyst solution: 10 ml of dry dichloromethane, 3.34 g of 1-dodecanol, and 76 µl of trifluoromethanesulfonic acid are combined and stirred for 1 h at room temperature. 1.35 ml of the previously prepared catalyst solution is added to a flask and heated to 23 °C. Then, 10.12 g (96 mmol) of 4-ethyl-1,3-dioxolane (EDX) and 6.75 ml (96 mmol) of 1,3-dioxolane (DXL) are added and stirred.

[0066] After 4 h, pyridine is added until the reaction mixture becomes decolorized. The product is washed with heptane and distilled water and then dried under vacuum. Example 6:

[0067] Preparation of the catalyst solution: 10 ml of dry dichloromethane, 1.05 ml of ethanol, and 76 µl of trifluoromethanesulfonic acid are combined and stirred for 1 h at room temperature. 1.35 ml of the previously prepared catalyst solution is added to a flask and heated to 23 °C. Then, 10.12 g (96 mmol) of 4-ethyl-1,3-dioxolane (EDX) and 6.75 ml (96 mmol) of 1,3-dioxolane (DXL) are added and stirred.

[0068] After 4 h, pyridine is added until the reaction mixture becomes decolorized. The product is washed with heptane and distilled water and then dried under vacuum. Example 7 (not according to the invention)

[0069] 1.35 ml of the catalyst solution prepared in Example 1 is placed in a flask and heated to 23 °C. Then, 13.5 ml (193 mmol) of 1,3-dioxolane (DXL) is added and stirred. The reaction mixture is no longer stirrable after 10 min. 1 ml of pyridine and 10 ml of dichloromethane are added to the reaction solution. The solid is then precipitated in heptane, washed with distilled water, and dried under vacuum.

[0070] Table 1 shows the results of the examples: Table 1: Example initiator Amount of initiator in mol% M in g / mol (NMR) Mn in g / mol (SEC) Mw in g / mol (SEC) PDI Viscosity in Pas Tg in °C 1 Allyloxyethanol 1,25 4120 2750 6560 2,47 5,4 -64 2 Allyloxyethanol 2, 5 2810 3860 6340 1,64 2,7 -65 3 Allyloxyethanol 5,0 1600 1610 2700 1,67 0,87 -67 4 Hydroxybutyl methacrylate 5, 6 1800 2010 3520 1,75 1,7 -62 5 Dodecanol 1,26 4980 3510 6470 1,85 4,6 -64 6 Ethanol 1,26 4020 4020 7300 1,82 7,3 -63 7* Allyloxyethanol 1,24 4800 3720 9420 2,53 nb (product is solid) -62 * not according to the invention

Claims

1. 1,3-Dioxolane copolymers of the general formula I         H- [O-CH2-O-CH2-CH2-]x1 [O-CH2-CH2O-CH2-]x2 [O-CH2-O-CHR1-CHR2- ]y1 [O-CHR1-CHR2O-CH2-]y2 OR3     (I), in which x1+x2 has values of 10 to 2000, R1 and R2 are hydrogen radicals or C1 to C18 alkyl radical, where in each case at least one radical R1 or R2 in the units [O-CH2-O-CHR1-CHR2- ]y1 and [O-CHR1-CHR2O-CH2-]y2 is a C1 to C18 alkyl radical, with the proviso that y1+y2 has values of 3*(x1+x2+y1+y2) / 100 to 50*(x1+x2+y1+y2) / 100, R3 is an aliphatically saturated or unsaturated hydrocarbon radical which is unsubstituted or substituted by halogen atoms, amino groups, C1-6 alkyl, C1-6 alkoxy or silyl groups and has 1 to 100 carbon atoms, in which one or more mutually non-adjacent -CH2 units may be replaced by -O-, -S-, C=O, -O-C(O)- or -NR4- groups and in which one or more mutually non-adjacent =CH units may be replaced by -N= groups and R4 is a hydrogen radical or C1 to C18 alkyl radical.

2. 1,3-Dioxolane copolymers according to Claim 1, in which the radicals R1 and R2 are selected from hydrogen radicals or methyl, ethyl, n-propyl or i-propyl radicals.

3. 1,3-Dioxolane copolymers according to either of the preceding claims, in which in each case only one radical R1 or R2 in the units [O-CH2-O-CHR1-CHR2-]y1 and [O-CHR1-CHR2O-CH2-]y2 is a C1 to C18 alkyl radical.

4. 1,3-Dioxolane copolymers according to any of the preceding claims, which have a molecular weight Mw of between 750 - 300 000, measured against a polystyrene standard, in THF, at 35°C, flow rate 0.3 ml / min and detection with RID (refractive index detector) on an Agilent PLgel MiniMIX-C Guard column with an injection volume of 20 µl.

5. 1,3-Dioxolane copolymers according to any of the preceding claims, which have a dynamic viscosity at 25°C of between 50 mPas - 500 Pas, measured on an Anton Paar MCR 320 rotational viscometer at 25°C, where the graphical evaluation is performed by plotting viscosity against shear stress.

6. 1,3-Dioxolane copolymers according to any of the preceding claims, where R3 is an alkyl radical having 1 to 18 carbon atoms.

7. 1,3-Dioxolane copolymers according to any of the preceding claims, where R3 is an alkenyl radical having 2 to 10 carbon atoms, in which one or more mutually non-adjacent -CH2 units may be replaced by -O- or -O-C(O)-groups.

8. Process for producing 1,3-dioxolane copolymers of the general formula I         H- [O-CH2-O-CH2-CH2-]x1 [O-CH2-CH2O-CH2-]x2 [O-CH2-O-CHR1-CHR2-]y1 [O-CHR1-CHR2O-CH2-]y2 OR3     (I), in which x1+x2 has values of 10 to 2000, R1 and R2 are hydrogen radicals or C1 to C18 alkyl radical, where in each case at least one radical R1 or R2 in the units [O-CH2-O-CHR1-CHR2-]y1 and [O-CHR1-CHR2O-CH2-]y2 is a C1 to C18 alkyl radical, with the proviso that y1+y2 has values of 3*(x1+x2+y1+y2) / 100 to 50*(x1+x2+y1+y2) / 100, R3 is an aliphatically saturated or unsaturated hydrocarbon radical which is unsubstituted or substituted by halogen atoms, amino groups, C1-6 alkyl, C1-6 alkoxy or silyl groups and has 1 to 100 carbon atoms, in which one or more mutually non-adjacent -CH2 units may be replaced by -O-, -S-, C=O, -O-C(O)- or -NR4- groups and in which one or more mutually non-adjacent =CH units may be replaced by -N= groups and R4 is a hydrogen radical or C1 to C18 alkyl radical, in which process 1,3-dioxolane is copolymerized with alkyl-substituted 1,3-dioxolane of the general formula II in the presence of a Lewis or Brønsted acid and an alcohol of the general formula R3OH, where the molar ratio of Lewis or Brønsted acid to alcohol of the general formula R3OH is less than 1.

9. Process according to Claim 8, in which the acid is trifluoromethanesulfonic acid.

10. Process according to Claim 8 or 9, in which 50 to 10 000 mol ppm of Lewis or Brønsted acid is used per mol of the sum total of 1,3-dioxolane and alkyl-substituted 1,3-dioxolane of the general formula II.

11. Process according to any of Claims 8 to 10, in which the temperature is between 10°C and 60°C.