Classifications

• • 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
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
  • C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
  • C08G63/16—Dicarboxylic acids and dihydroxy compounds
  • C08G63/20—Polyesters having been prepared in the presence of compounds having one reactive group or more than two reactive groups
• • 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
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
  • C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
  • C08G63/16—Dicarboxylic acids and dihydroxy compounds
  • C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
  • C08G63/181—Acids containing aromatic rings
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds

Definitions

• the present invention relates to high molecular weight copolyester resins having low melting points and peculiar crystallization behaviour and the process for preparing the resins.
• polyester resins having low melting points e.g. lower than 220°C presents serious process difficulties due to the sticking problems on the walls of the reactor caused by the high upgrading temperatures used.
• the known solid state polycondensation processes need high upgrading temperature due to the low kinetic of the upgrading reactions.
• the solid state polycondensation reactions of polyester resins are per ⁇ formed by temperatures higher than 180°C; mainly higher than 195 ⁇ C (see page 3295 of Journal of Applied Polym. Cs. 28 3289 - 3300, 1989) .
• the resins subjected to upgrading comprise copolyethylenterephtalates (COPETs) .
• COPETs copolyethylenterephtalates
• a ongs the COPETs use is exemplified of copolimers containing at most 10% in mols of units deriving from isophtalic acid on the total of the acid units. Except the melting point of the resin after upgrading and intrinsic viscosity values no other indications are given regarding the upgraded polymer.
• the resins subjected to upgrading are the copolyethylenterephtalates containing from 10 to 25% by weight on the total resin weight of units deriving from isophtalic acid (COPETs).
• the COPET is upgraded at temperature lower than 170°C and higher than the TG of the resin, preferably comprised between 130° and 160°C using an upgrading additive select ⁇ ed from the group consisting of the dianhydrides of aromatic, aliphatic cycloaliphatic tetracarboxy1ic acids.
• the upgraded COPETs present, besides the high IV values (higher than 0.85 dl/g) and molding points lower than 220°C, other valuable properties.
• the crystall zation behaviour of the resins is remarkable from the view point of the moiding applications, because the resin does not show any cristallinity also by slow cooling from the melt; the COPETs give clear, transparent amorphous solids also by very slow cooling rate, e.g. l ⁇ C/min.
• Another interesting property of the resin is its gel-free characteristic.
• COPET containing about 15% weight of the resin of isophtalic acid units, melting point of 212°C. This COPET gives clear highly transparent amorphous solid by cooling its melt also at very slow cooling rate (l°C/min). Pyromellitic dianhyd ⁇ de is the preferred upgrading compound.
• dianhydrides are the dianhydrides of 1, 2, 3, 4-cyclobutanetetracarboxyl icacid, 3 , 4-dicarboxy-l ,2,3, 4-tetrahydro-l-naphthalenesucc ⁇ n ⁇ c acid and 3, 3' , 4' benzophenone tetracarboxylic acid.
• the preferred dianhydride from the cycloaliphatic acids is 1,2,3,4 cyclobutantetracarboxylic acid dianhydride.
• the preferred concentration of the additive with respect to the polyester resin is 0,05-1% by weight.
• the solid state upgrading process comprises the steps of blending the COPET resin in a molten state with the upgrading additive, converting the melt into granules, crystallizing the granulate at temperatures higher than the TG of the resin but lower than 180°C and then upgrad ⁇ ing the crystallized resin at a temperature comprised in the range from the TG of the resin and 180°C, particularly from 130° and 170 "C.
• the process is preferably carried out in continuous way using continuous crystallizers and upgrading reactors where the chips can move counter currently with a stream of a heated gas, e.g. air, nitrogen and carbon dioxide.
• a heated gas e.g. air, nitrogen and carbon dioxide.
• Apparatus suitable for the crystallization and upgrading steps can be those described in USP 4,064,112 and 4,161,578 whose description is herewith enclosed for reference.
• the blending of the polyester resin with the additive is carried out in an equipment capable to perform reactive extrusion such as corotating or counter rotating inter- meshing or not intermeshing twin screw extruder with or without venting capability at a temperature between 200° and 350°C, depending on the melting point of the polyester .
• a counter rotating non intermeshing twin screw extruder vented or not vented is preferred.
• the extruder may be directly fed with molten COPET from a plant in which the COPET is produced by polycondensation in the molten state.
• the extruder may also be fed with solid COPET granu ⁇ lates produced in another plant.
• the extruder is preferably connected to a high vacuum oil seal pump to maintain a vacuum higher than 2 torr for the devolatilization of the reactive blend and for obtain ⁇ ing a resin with a low content of acetaldehyde.
• the blending could be also performed without the use of vacuum.
• the residence time in the extruder could be comprised between 10 and 120 sec, preferably 15-30 sec.
• the dianhydride could be also diluted using blends of the dianhydride and crystallized PET-chips (1 part addi ⁇ tive to 10 parts PET chips) .
• the dilution could be per ⁇ formed in a fanned blender using about 0,1% of polyethylenglycol or polycaprolactone , as adhesives, and using blending temperature at about 150°C.
• the reactive melt coming out of the twin screw extruder is continuously pallettized using an underwater pelletizer or a strand pelletizer system.
• the new COPETs may be modified by blending with polymers like polybutylenterephtalate , polycarbonate, polycaprolactone, polyester elastomers, phenoxy resins in amount up to about 20% by weight of the total resins, directly before the extrusion processing.
• the addition has the effect of improving the mechanical properties of the composition as well as the processing conditions without sacrifymg the transparency of the end product.
• the intrinsic viscosity was determined on a solution of 0.5 g of COPET in 100 ml of 60/40 mixture by weight of phenol and tetrachloroethane at 25°C according to ASTM D 4603 - 86.
• the acetaldehyde content was determined with a gas chromatographic method according to ASTM D 4526-85, using a Perkm Elmer 8700 gas chromatograph. (Perkin Elmer model HS 101) .
• test conditions were as follows: pyromellitic acid dianhydride in the COPET melt 0.15% by weight screw speed: 415 PM ratio length/diameter (L/D): 24 average residence time: 18 - 25 sec. barrel temperature: 235°C product melt temperature: 290°C vacuum: 1 - 5 torr A die with double holes was used as extruder die (Diame ⁇ ter: 7 mm) .
• the COPET chips had an acetaldehyde content of 5 - 8 ppm. During the test period, the IV of the product was constant over the period of 2 weeks.
• the melting point of the product was 212°C.
• the COPET-chips were then fed continuously to a solid state upgrading pilot . plant using the apparatus and the inert gas ricycling conditions set forth in European application EP 86830340.5.
• the crystallization temperature was 150°C and the residence time was 40 min.
• the temperature of the solid state upgrading reactor was 150°C and the residence time was 12 h.
• the IV of the upgraded products was 0,94 + 0,02 dl/g.
• the product was free from gel, with acetaldehyde content of 0.60 ppm.
• Fig. 1 shows the crystallization kinetic of COPET prepared according to this example in comparison with standard bottle grade polyethyleneterephthalate .
• the crystallization kinetic was determined under isothermal conditions at 120°C.
• Table 1 shows the data relating to crystallization by cooling of COPET of example 1 in comparison to standard PET.
• Curve 1 refers to standard PET cooled to a rate of 10°C/min wherein the increase of the heat of crystallization is 11.8 J/g.
• Average residence time 18 - 25 sec.
• Produst melt temperature 290°C
• Vacuum 1 - 5 torr.
• a die with double holes was used as extruder die (Diameter: 7 mm) .
• the COPET chips had an acetaldehyde content of 6 - 9 ppm. During the test period, the IV of the product was constant over a period of 2 weeks.
• the melting point of the product was 212°C.
• the modified COPET-chips were then fed continuously into a solid state polycondensation pilot plant using the apparatus and the inert gas recycling conditions described in European application EP 86830340.5.
• the crystallization temperature was 150°C and the residence time in the crystallizer was 40 min.
• the solid state temperature in the reactor was 150°C and the resi ⁇ dence time was 10 h.
• the IV of the upgraded product was 0,965 dl/g.
• the product was free from gel, with an acetaldehyde content of 0.60 ppm.
• the crystallized COPET chips were dried and fed into the twin screw.
• the IV of the product was 0.845 + 0.02 dl/g.
• Example 1 The same conditions were used as in Example 1; only the average residence time was about 25 sec.
• the solid state conditions were 130° - 140°C in the crystallizer and 140°C in the polyaddition reactor.
• the residence time in the reactor was 10 hours.
• the chips intrinsic viscosity was 0.92 + 0,015 dl/g.
• the acetaldehyde content was 0.67 ppm.
• the COPET was dried to a content of water less than 0.005% using dried air with Dew point between - 30°C and - 40 ⁇ C.
• This example describes the extrusion blowing of COPET of example 1 and mixed before blowing with 5% by weight of polycarbonate (Dow Chem. ) .
• This example describes the extrusion blowing of COPET of example 1 mixed before blowing with 5% by weight of phenoxy resin (Union Carbide).

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Polyesters Or Polycarbonates (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=11359372

Family Applications (1)

Country Status (17)

Families Citing this family (16)

Family Cites Families (12)

• 1991
  • 1991-03-29 IT ITMI910885A patent/IT1245599B/it active IP Right Grant
• 1992
  • 1992-03-22 IL IL92101330A patent/IL101330A0/xx unknown
  • 1992-03-26 HU HU9203750A patent/HU9203750D0/hu unknown
  • 1992-03-26 BR BR9204821A patent/BR9204821A/pt not_active Application Discontinuation
  • 1992-03-26 CA CA002083279A patent/CA2083279A1/en not_active Abandoned
  • 1992-03-26 AU AU14343/92A patent/AU652233B2/en not_active Ceased
  • 1992-03-26 WO PCT/EP1992/000669 patent/WO1992017519A1/en not_active Application Discontinuation
  • 1992-03-26 HU HU9203750A patent/HUT64988A/hu unknown
  • 1992-03-26 EP EP92906945A patent/EP0531485A1/de not_active Withdrawn
  • 1992-03-26 JP JP92506528A patent/JPH05507760A/ja active Pending
  • 1992-03-27 MX MX9201413A patent/MX9201413A/es unknown
  • 1992-03-27 TR TR00305/92A patent/TR27173A/xx unknown
  • 1992-03-27 PT PT100318A patent/PT100318A/pt not_active Application Discontinuation
  • 1992-03-27 ZA ZA922247A patent/ZA922247B/xx unknown
  • 1992-03-28 CN CN92102952A patent/CN1066856A/zh active Pending
  • 1992-03-28 TW TW081102405A patent/TW203066B/zh active
  • 1992-11-25 NO NO92924542A patent/NO924542L/no unknown
  • 1992-11-27 FI FI925418A patent/FI925418A/fi not_active Application Discontinuation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events