text: the ( meth ) acrylic ester oligomers of the present invention are preparable from high - molecular - weight aromatic polyesters such as polyethylene naphthalate ( pen ), polyethylene terephthalate ( pet ) or mixtures thereof . pet sources are either virgin or recycled pet , or waste pet from many sources such as beverage bottles , sheets , film and synthetic fibers . the ( meth ) acrylic ester oligomers of the invention contain pet amounts within the range of about 10 to 80 wt . %; a more preferred range is from about 20 to 50 wt . %; especially preferred 30 to 40 wt . %. preferably , pet should be flaked and washed before use , but the direct use of waste beverage bottles is possible . the also inventive synthesis of the ( meth ) acrylic ester oligomers is based on a two - step process , but the steps can be achieved consecutively in a one pot reaction . the steps of the process consist in : ( i ) generation of hydroxy terminated binder precursor oligomers ( oh - precursors ) said generation involving a glycolysis or similar reaction of aromatic polyester ( s ) such as pet and in the scope of the present invention , the product of step ( i ) that is further reacted in step ( ii ) is termed “ hydroxy terminated binder precursor oligomers ” or — shorter —“ oh - precursors ” since it usually is a mixture of oh - terminated oligomers . said term comprises — dependent on whether or not a modification ( chain extension ) is performed — the “ glycolysis ” product ( hydroxy terminated oligomer ) or the reaction product of said “ glycolysis ” product with dicarboxylic acid ( s ) and / or anhydride ( s ). the term “ glycolysis ” for simplification is considered as also comprising the reaction with aminoalcohols . the synthesis is now further described for the preferred polyester pet , however , it is also applicable to other aromatic polyesters . in accordance with the present invention , pet is first reacted with a polyol or polyol mixture in molar ratios of 0 . 2 ( oh groups in polyol ): 1 ( repetition unit in pet ) to 2 ( oh groups in polyol ): 1 ( repetition unit in pet ) in the presence of an esterification catalyst to yield low - molecular - weight polyesters containing free oh - groups . particularly favorable are mixture in molar ratios of 0 . 8 ( oh - groups in polyol ): 1 ( repetition unit in pet ) to 1 . 5 ( oh groups in polyol ): 1 ( repetition unit in pet ), and even more favorable 1 . 1 ( oh groups in polyol ): 1 ( repetition unit in pet ) to 1 . 3 ( oh groups in polyol ): 1 ( repetition unit in pet ). the reaction requires normally 0 . 5 to 4 hours at temperatures between 210 ° c . and 250 ° c ., and it is preferably carried out under a n 2 atmosphere . the polyols used for the glycolysis can be aliphatic , cycloaliphatic , aromatic and / or heterocyclic polyols , and are preferably selected from diols or triols . examples of suitable polyols are diethylene glycol , triethylene glycol , tetraethylene glycol , tripropylene glycol , 1 , 4 - butanediol , 1 , 6 - hexanediol , glycerin , dipropylene glycol , neopentyl glycol , 2 , 2 , 4 - trimethyl - 1 , 3 - pentane diol , 1 , 2 - propane glycol , 1 , 3 - propane glycol , 1 , 3 - butane glycol , 2 , 3 - butane glycol , 1 , 5 - pentanediol , 2 - methyl - 1 , 5 - pentanediol , 2 - methyl - 2 - ethyl - 1 , 3 - propanediol , bisphenol - a - ethoxylate , dodecahydro - bisphenol - a , dimethylol propionic acid , oh - terminated polybutadiene , trimethylolethane , 1 , 4 - cyclohexanedimethanol , 1 , 2 - cyclohexanedimethanol , 1 , 3 - cyclohexanedimethanol , 1 , 4 - bis ( 2 - hydroxyethoxy ) cyclohexane , norbornylene glycol , 1 , 4 - benzenediethanol , 2 , 4 - dimethyl - 2 - ethylenehexane - 1 , 3 - diol , 2 - buten - 1 , 4 - diol , ethoxylated trimethylolpropane , trimethylolhexane , trimethylolpropane - monoallyether , 1 , 2 , 4 - butanetriol , dipentaerythritol , pentaerythrite , dicyclopentadienedimethanol , ethoxylated neopentyl glycol , dimethylhydantoin glycol , ethoxylated dimethylhydantoin glycol , ethoxylated isocyanurate , and in particular di -( 2 - hydroxyethyl )- 5 , 5 - dimethylhydantoin , 1 , 3 - dimethylol - 5 , 5 - dimethylhydantoin , tri -( 2 - hydroxyethyl )- isocyanurate , and hydroxyalkyl isocyanurates . the pet - glycolysis can also be achieved with a mixture of polyols or polyols and aminoalcohols such as diethanolamine , triethanolamine and triisopropanolamine . instead of polyols , aminoalcohols or mixtures of aminoalcohols can also be used . it is preferred that linear glycols such as diethylene glycols etc . are used in combination with branched glycols to reduce the risk of crystallization . as catalyst , 0 . 1 wt . % to 2 wt . % of any esterification catalyst such as tin ( ii ) caprylate , cobalt acetate , mangan ( ii ) acetate , calcium hydroxide , calcium formiate , sodium hydroxide , barium hydroxide , and organic tin and titan catalysts can be added . preferably , t - butyl ortho titanate is used . the oh - precursors obtainable by the glycolysis reaction ( see above ), and optionally the chain extension reaction ( see below ), are further reacted with ( meth ) acrylic acid ( maa ) in molar ratios of 0 . 5 ( acid group in maa ): 1 ( oh group in oh - precursor ) to ( acid groups in maa ): 1 ( oh groups in oh - precursor ) at temperatures from 90 ° c . to 140 ° c . to yield low - odor ( meth ) acrylic ester binders . the reaction is generally carried out in the presence of 0 . 1 wt . % to 2 wt . % of an esterification catalyst such as p - toluene sulfonic acid , methane sulfonic acid , sulfuric acid , boron trifluoride or any acid esterification catalyst . to prevent polymerization during reaction , a free - radical inhibitor such as hydroquinone , methyl hydroquinone , t - butyl p - cresol , phenothiazine and the like may be added in amounts ranging from 0 . 1 wt . % to 1 wt . % based on the weight of maa . an inert solvent can be used to azeotrope the water resulting from the esterification reaction . examples of solvents that are particularly useful are hexane , pentane , cyclopentane , cyclohexane , benzene , toluene , xylene or mixtures thereof . the preferred solvent is toluene . the reaction mixture may contain from about 5 wt . % to 30 wt . % of the selected solvent . the reaction is run for 4 to 5 hours or until no more water is formed . the properties of the cured acrylic systems can be varied by modification of the ( meth ) acrylic ester binders . following the glycolysis step , the oh - terminated low - molecular - weight polyesters can be reacted with at least one difunctional or multifuntional organic acid ( and / or anhydride ). the resultant polyester prepolymers yield , after direct esterification , methacrylic ester binders , which provide cured systems with special properties . suitable organic acids ( or anhydrides ) are aliphatic and aromatic difunctional or multifunctional acids such as adipic acid , azelaic acid , phthalic acid or anhydride , isophthalic acid , dodecandicarboxylic acid , maleic acid or anhydride , trimellitic acid or anhydride and the like . the same procedure as outlined above can also be used with other starting materials such as pen instead of pet , acrylic acid instead of methacrylic acid and aminoalcohols instead of polyols or part of polyols . furthermore , in order to achieve specific features it is of course also possible to use mixtures of starting materials such as mixtures of aromatic polyesters , mixtures of acrylic acid and methacrylic acid , mixtures of polyols or polyols and aminoalcohols , etc . curable acrylic systems for special applications can also be obtained by replacing a certain amount of the polyols by a monofunctional alcohol in the glycolysis step . the amount of monofunctional alcohol ( s ), or a mixture of monofunctional alcohol , depends on the desired end use of the acrylic system . preferably , the monofunctional alcohol ( s ) replaces 1 to about 90 mol % of the diol or polyol or aminoalcohol . suitable alcohols include the c 5 - c 22 linear and branched saturated and unsaturated alcohols including , for example , 4 - methyl - 1 - pentanol , hexanol , linoleoyl alcohol , benzyl alcohol , trimethylolpropane diallylether , allyl alcohol and nonanol . other useful alcohols include the oh - functional polyethers , polyesters , polyurethanes , polycaprolactones , etc . 475 g pet flakes from recycled beverage bottles , 520 g ethoxylated neopentyl glycol and 5 g t - butyl ortho titanate are charged into a reactor equipped with mechanical stirrer , temperature controller and condenser . the reaction mixture is heated for 2 hours at 240 ° c . under n 2 atmosphere . then , the solution is allowed to cool until the reaction mixture has reached 130 ° c . and then 365 g toluene , 460 g methacrylic acid containing 0 . 2 g phenothiazine , and 15 g p - toluene sulfonic acid are added . the reactor is further equipped with a water separator and the reaction is carried out at the boiling temperature of the mixture ( about 130 ° c .). the water produced is distilled off with the solvent and collected in the separator . the reaction is finished after about 4 hours , or when no more water is formed . finally , the toluene is removed under reduced pressure . the mixture obtained has low viscosity and is cured at room temperature with 2 wt . % benzoylperoxide as initiator and 0 . 5 wt . % dimethylaniline as catalyst to provide systems with tensile strength ( ts )& gt ; 35 mpa , elongation at break of 9 %, good scratch resistance and compressive strength , and excellent weather and chemical resistance . 475 g pet flakes from recycled beverage bottles , 520 g ethoxylated neopentyl glycol and 5 g t - butyl ortho titanate are charged into a reactor equipped with mechanical stirrer , temperature controller and condenser . the reaction mixture is heated for 2 hours at 240 ° c . under n 2 atmosphere . then , the solution is allowed to cool until the reaction mixture has reached 130 ° c . and then 459 g toluene , 836 g methacrylic acid containing 0 . 4 g phenothiazine , and 18 g p - toluene sulfonic acid are added . the reactor is further equipped with a water separator and the reaction is carried out at the boiling temperature of the mixture ( about 130 ° c .). the water produced is distilled off with the solvent and collected in the separator . the reaction is finished after about 4 hours or when no more water is formed . finally , the toluene is removed under reduced pressure . the mixture obtained has low viscosity and is cured at room temperature with 2 wt . % benzoylperoxide as initiator and 0 . 5 wt . % dimethylaniline as catalyst to provide systems with tensile strength ( ts )& gt ; 65 mpa , elongation at break of 4 %, good scratch resistance and compressive strength , and excellent weather and chemical resistance . 465 g pet flakes from recycled beverage bottles , a mixture of 300 g ethoxylated neopentyl glycol and 230 g nonanol n , and 5 g t - butyl ortho titanate are charged into a reactor equipped with mechanical stirrer , temperature controller and condenser . the reaction mixture is heated for 2 hours at 240 ° c . under n 2 atmosphere . then , the solution is allowed to cool until the reaction mixture has reached 130 ° c . and then 454 g toluene , 815 g methacrylic acid containing 0 . 4 g phenothiazine , and 18 g p - toluene sulfonic acid are added . the reactor is further equipped with a water separator and the reaction is carried out at the boiling temperature of the mixture ( about 130 ° c .). the water produced is distilled off with the solvent and collected in the separator . the reaction is finished after about 4 hours or when no more water is formed . finally , the toluene is removed under reduced pressure . the mixture obtained has low viscosity and is cured at room temperature with 2 wt . % benzoylperoxide as initiator and 0 . 5 wt . % dimethylaniline as catalyst to provide systems with tensile strength ( ts )& gt ; 30 mpa , elongation at break of 4 %, good scratch resistance and compressive strength , and excellent weather and chemical resistance . 395 g pet flakes from recycled beverage bottles , 440 g diethylene glycol and 5 g t - butyl ortho titanate are charged into a reactor equipped with mechanical stirrer , temperature controller and an overhead condenser with receiver . the reaction mixture is heated for 2 hours at 240 ° c . under n 2 atmosphere . then , the reactor is allowed to cool to 200 ° c . and 160 g phthalic acid anhydride are added . the mixture is kept at this temperature for about 2 hours and the water formed is collected in the receiver . once no more water is formed , the solution is allowed to cool until the reaction mixture has reached 130 ° c ., and then 378 g toluene , 513 g acrylic acid containing 0 . 3 g phenothiazine , and 15 g p - toluene sulfonic acid are added . the reactor is further equipped with a water separator and the reaction is carried out at the boiling temperature of the mixture ( about 130 ° c .). the water produced is distilled off with the solvent and collected in the separator . the reaction is finished after about 4 hours or when no more water is formed . finally , the toluene is removed under reduced pressure . the mixture obtained has low viscosity and is cured at room temperature with 2 wt . % benzoylperoxide as initiator and 0 . 5 wt . % dimethylaniline as catalyst to provide systems with tensile strength ( ts )& gt ; 35 mpa , elongation at break of 6 %, good scratch resistance and compressive strength , and excellent weather and chemical resistance . 395 g pet flakes from recycled beverage bottles , 364 g diethylene glycol and 3 g t - butyl ortho titanate are charged into a reactor equipped with mechanical stirrer , temperature controller and an overhead condenser with receiver . the reaction mixture is heated for 2 hours at 240 ° c . under n 2 atmosphere . then , the reactor is allowed to cool to 200 ° c . and 237 g phthalic acid anhydride are added . the mixture is kept at this temperature for about 2 hours and the water formed is collected in the receiver . once no more water is formed , the solution is allowed to cool until the reaction mixture has reached 130 ° c ., and then 303 g toluene , 213 g methacrylic acid containing 0 . 1 g phenothiazine , and 12 g p - toluene sulfonic acid are added . the reactor is further equipped with a water separator and the reaction is carried out at the boiling temperature of the mixture ( about 130 ° c .). the water produced is distilled off with the solvent and collected in the separator . the reaction is finished after about 4 hours or when no more water is formed . finally , the toluene is removed under reduced pressure . the mixture obtained has low viscosity and is cured at room temperature with 2 wt . % benzoylperoxide as initiator and 0 . 5 wt . % dimethylaniline as catalyst to provide systems with tensile strength ( ts )& gt ; 12 mpa , elongation at break of 30 %, good scratch resistance and compressive strength , and excellent weather and chemical resistance . 379 g pet flakes from recycled beverage bottles , 440 g diethylene glycol and 2 g t - butyl ortho titanate are charged into a reactor equipped with mechanical stirrer , temperature controller and an overhead condenser with receiver . the reaction mixture is heated for 2 hours at 240 ° c . under n 2 atmosphere . then , the reactor is allowed to cool to 200 ° c . and 180 g tmas ( ws ) are added . the mixture is kept at this temperature for about 2 hours and the water formed is collected in the receiver . once no more water is formed , the solution is allowed to cool until the reaction mixture has reached 130 ° c ., and then 392 g toluene , 566 g methacrylic acid containing 0 . 3 g phenothiazine , and 16 g p - toluene sulfonic acid are added . the reactor is further equipped with a water separator and the reaction is carried out at the boiling temperature of the mixture ( about 130 ° c .). the water produced is distilled off with the solvent and collected in the separator . the reaction is finished after about 4 hours or when no more water is formed . finally , the toluene is removed under reduced pressure . the mixture obtained has low viscosity and is cured at room temperature with 2 wt . % benzoylperoxide as initiator and 0 . 5 wt . % dimethylaniline as catalyst to provide systems with tensile strength ( ts )& gt ; 37 mpa , elongation at break of 8 %, good scratch resistance and compressive strength , and excellent weather and chemical resistance . while there are shown and described presently preferred embodiments of the invention , it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practised within the scope of the following claims .