Composition for hydrolytic stabilization of polyester

Abstract

The invention relates to the use of at least one compound of the formula (1) wherein R.sub.1 and R.sub.2 are the same or different and denote a C.sub.1-C.sub.10-alkyl as a hydrolysis stabilizer in polyester materials. ##STR00001##

Claims

1. A method of stabilization of polyester materials against hydrolysis said method being characterized by adding at least one compound of the formula (1) ##STR00004## wherein R.sub.1 and R.sub.2 are the same or different and denote a C.sub.1-C.sub.10-alkyl, as a hydrolysis stabilizer in said polyester materials, and wherein the compound of formula (1) is in a proportion of from 0.1 to 20.0 wt.-%, based on the weight of a proportion of the stabilized polyester materials.

2. The method as claimed in claim 1, wherein the compounds of the formula (1) are dimethylterephthalate, diethylterephthalate, dipropylterephthalate, dibutyl-terephthalate, dipentylterephthalate, dihexylterephthalate, diheptylterephthalate, dioctylterephthalate, dinonylterephthalate or didecylterephthalate.

3. The method as claimed in claim 1, wherein the compound of formula (1) is dimethylterephthalate.

4. The method as claimed in claim 1, wherein the polyester in the polyester materials is polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, dibenzoyl polyethylene terephthalate, dibenzoyl polybutylene terephthalate, dibenzoyl polyethylene naphthalate or mixtures thereof.

5. The method as claimed in claim 1, wherein the polyester in the polyester materials is polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and polytrimethylene terephthalate, and mixtures and co-polyesters thereof.

6. The method as claimed in claim 1, wherein the polyester in the polyester materials are aliphatic polyesters selected from the group consisting of polyhydroxybutyrate and its copolymer with polyhydroxyvalerate, polyhydroxybutyrate-valerate, poly (-caprolactone).

7. The method as claimed in claim 1, further comprising forming the polyester materials in to a stretched film.

8. The method as claimed in claim 1, wherein the proportion of the compound of formula (1) is from 1.0 to 10.0 wt.-%, based on the weight of the stabilized polyester material.

9. The method as claimed in claim 1, wherein the proportion of the compound of formula (1) is from 1.5 to 5.0 wt.-%, based on the weight of the stabilized polyester material.

10. The method as claimed in claim 1, wherein the compound of formula (1) is added in combination with further additives selected from the group consisting of radical scavengers, light stabilizers, heat stabilizers, flame retardants, pigments, dyes, antioxidants, antibacterial agents, neutralizers, antistatic agents, antiblocking agents, optical brighteners, heavy metal inactivation agents, hydrophobic agents, peroxides, water scavengers, acid scavengers, hydrotalcites, elastomers, impact modifiers, laser marking additives, processing aids, and mixtures thereof.

11. The method as claimed in claim 1, wherein the compound of formula (1) is added in combination with UV-absorbers.

12. The method as claimed in claim 1, further comprising dispersing the compound of formula (1) in a carrier material to form a masterbatch and adding the masterbatch to said polyester materials.

13. The method as claimed in claim 1, wherein the polyester material is in the form of a film or a sheet.

Description

EXAMPLES

(1) The following materials are used: PET1: (XPURE 4004, Invista, I.V. 0.63) PET2: regranulat RT4027 (Invista/Erema) PET3: RAMAPET R 180 GR BB (Indorama Plastics) PC (Polycarbonate): (Trirex 3022PJ(01) Entec) Hydrolysis stabilizator: DMT (dimethylterephthalat) UV-Absorber: 2-(4,6-Diphenyl-1,3,5-triazin-2-yl)-5-hexyloxy-phenol (TINUVIN 1577 ED, BASF)

(2) Two Masterbatches (MB) were produced by using a twin-screw extruder Leistritz MASS technology (27 mm/40D). MBHS contains 10% of DMT on PC for the hydrolysis stabilization. MBUV contains 15% of the UV-absorber Tinuvin 1577 on PET3.

Example 1

(3) A three layer film was produced with a structure of ABA. The composition of the core layer B consists of 53% PET1, 15% PET 2, 2% MBHS, 30% MBUV. The outer layers A consists of 67% PET1, 3% MBHS, 30% MBUV. The used PET was predried at 100-170 C. The main extruder was equipped with vacuum 10 mbar. The coextruder was equipped with vacuum20 mbar.

(4) The extrusion temperatures of the different zones are displayed in Table 1.

(5) TABLE-US-00001 TABLE 1 Extrusion Temperatures in C.: Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 Zone 8 Zone 9 100 102 104/105 106 120/130 210 210/215 220 200/190

(6) The molten polymer was discharged from a nozzle of a draw roller. The film was stretched by a factor of 3.0 in the machine direction and stretched in a cross-stretching by a factor of 3.4. Subsequently, the film was heat set at 225 C. and relaxed in the transverse direction by 3% at temperatures of 220-180 C. The final film thickness was 50 microns.

Example 2 (Comparative)

(7) A three layer film was produced with a structure of ABA. The composition of the core layer B consists of 45% PET1, 25% PET 2, 30% MBUV. The outer layers A consists of 70% PET1, 30% MBUV. The used PET was predried at 100-170 C. The main extruder was equipped with vacuum 10 mbar. The coextruder was equipped with vacuum20 mbar.

(8) The extrusion temperatures of the different zones are displayed in Table 2.

(9) TABLE-US-00002 TABLE 2 Extrusion Temperatures in C.: Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 Zone 8 Zone 9 100 102 104/105 106 120/130 210 210/215 220 200/190

(10) The molten polymer was discharged from a nozzle of a draw roller. The film was stretched by a factor of 3.0 in the machine direction and stretched in a cross-stretching by a factor of 3.4. Subsequently, the film was heat set at 225 C. and relaxed in the transverse direction by 3% at temperatures of 220-180 C. The final film thickness was 50 microns.

(11) Test Results

(12) TABLE-US-00003 TABLE 3 Results of testing Test Example 1 Example 2 comp. Pressure Cooker Test = 78% after 40 h 76% after 40 h Elongation at break retention after 69% after 50 h 42% after 50 h autoclavation (120 C./2 bar abs) 69% after 60 h Damp Heat Test 71% after 2000 h 43% after 2000 h Elongation at break retention after 52% after 2500 h 1% after 2500 h conditioning (85% rH/85 C.) Intrinsic melt Viscosity (I.V.) 0.621 0.527 Standard Viscosity (S.V.) 0.628 0.608

(13) The test results of example 1, which contain the anti-hydrolysis-additive convinces in all tests, which simulate hydrolysis degradation of polymer. In the pressure cooker test the film stayed significantly longer stabile than the film without anti-hydrolysis-additive. Also in the damp heat test the material equipped with anti-hydrolysis-additive resisted significantly longer than the non-equipped film. Also the measurement of the melt viscosity and the standard viscosity show the more stabilized material is the one which was equipped with the anti-hydrolysis-additive. All films of Example 1 display a high UV stability.