Process And Apparatus For Manufacture of Processable Polyvinyl Alcohol

Abstract

A method for the manufacture of a plasticized polyvinyl alcohol polymer mixture comprising the steps of: introducing into a mixing reactor a polyvinyl alcohol polymer comprising homopolymeric polyvinyl alcohol or a blend thereof having a degree of hydrolysis in the range of 93% to 98% or more; wherein the mixing reactor comprises a blending chamber having a primary inlet, a primary outlet and at least two inter-engaging components extending between the primary inlet and primary outlet, the components being arranged to apply a shearing force to the polymer while the polymer is conveyed by the components from the inlet through a reaction zone to the outlet; one or more secondary inlets located downstream from the primary inlet for introducing reactants comprising a processing aid and a plasticizer to the chamber to form a reaction mixture; wherein the plasticizer is selected from the group consisting of the following compounds and mixtures thereof: (a) sugar alcohols selected from the group consisting of: diglycerol, triglycerol, fructose, ribose, xylose, D-mannitol, triacetin, and mixtures thereof; polyols selected from the group consisting of: pentaerythritol, dipentaerythritol, and mixtures thereof; (b) diols selected from the group consisting of: methyl pentanediol, 1,2-propanediol, 1,4-butanediol, 2-hydroxy-1,3-propanediol, 3-methyl-1,3-butanediol, 3,3-dimethyl-1,2-butanediol, and mixtures thereof; (c) glycols selected from the group consisting of: polyethylene glycol 300, polyethylene glycol 400, alkoxylated polyethylene glycol, and mixtures thereof; (d) caprolactam, tricyclic trimethylolpropane formal, rosin esters, euricamide, and mixtures thereof; wherein the blending chamber comprises a plurality of heated regions arranged so that the mixture is subjected to a temperature profile whereby the temperature increases from the inlet to the outlet; a secondary outlet located between the reaction zone and primary outlet arranged to allow removal of processing aid from the chamber; reacting the processing agent, plasticizer and polymer in the reaction zone to form plasticized polymer; and
allowing the plasticized polymer to pass from the primary outlet.

Claims

1. A method for manufacture of a plasticized polyvinyl alcohol polymer mixture, the method comprising the steps of: introducing into a mixing reactor a polyvinyl alcohol polymer comprising homopolymeric polyvinyl alcohol or a blend thereof having a degree of hydrolysis in the range of 93% to 98% or more; wherein the mixing reactor comprises a blending chamber having a primary inlet, a primary outlet and at least two inter-engaging components extending between the primary inlet and primary outlet, the components being arranged to apply a shearing force to the polymer while the polymer is conveyed by the components from the inlet through a reaction zone to the outlet; one or more secondary inlets located downstream from the primary inlet for introducing reactants comprising a processing aid and a plasticizer to the chamber to form a reaction mixture; wherein the plasticizer is selected from the group consisting of the following compounds and mixtures thereof: (a) sugar alcohols selected from the group consisting of: diglycerol, triglycerol, fructose, ribose, xylose, D-mannitol, triacetin, and mixtures thereof; polyols selected from the group consisting of: pentaerythritol, dipentaerythritol, and mixtures thereof; (b) diols selected from the group consisting of: methyl pentanediol, 1,2-propanediol, 1,4-butanediol, 2-hydroxy-1,3-propanediol, 3-methyl-1,3-butanediol, 3,3-dimethyl-1,2-butanediol, and mixtures thereof; (c) glycols selected from the group consisting of: polyethylene glycol 300, polyethylene glycol 400, alkoxylated polyethylene glycol, and mixtures thereof; (d) caprolactam, tricyclic trimethylolpropane formal, rosin esters, euricamide, and mixtures thereof; wherein the blending chamber comprises a plurality of heated regions arranged so that the mixture is subjected to a temperature profile whereby the temperature increases from the inlet to the outlet; a secondary outlet located between the reaction zone and primary outlet arranged to allow removal of processing aid from the chamber; reacting the processing agent, plasticizer and polymer in the reaction zone to form plasticized polymer; and allowing the plasticized polymer to pass from the primary outlet.

2. A method as claimed in claim 1 wherein the plasticizer is selected from the group consisting of: sugar alcohols selected from the group consisting of: diglycerol, triglycerol, fructose, ribose, xylose, D-mannitol, triacetin, and mixtures thereof; polyols selected from the group consisting of: pentaerythritol, dipentaerythritol, and mixtures thereof.

3. A method as claimed in claim 1 wherein the plasticizer is selected from the group consisting of: diols selected from the group consisting of: methyl pentanediol, 1,2-propanediol, 1,4-butanediol, 2-hydroxy-1,3-propanediol, 3-methyl-1,3-butanediol, 3,3-dimethyl-1,2-butanediol, and mixtures thereof.

4. A method as claimed in claim 1 wherein the plasticizer is selected from the group consisting of: glycols selected from the group consisting of: polyethylene glycol 300, polyethylene glycol 400, alkoxylated polyethylene glycol, and mixtures thereof.

5. A method as claimed in claim 1 wherein the plasticizer is selected from the group consisting of: caprolactam, tricyclic trimethylolpropane formal, rosin esters, euricamide, and mixtures thereof.

6. A method as claimed in claim 1 wherein the polyvinyl alcohol polymer has a degree of hydrolysis of 93 wt % to 98 wt %.

7. A method as claimed in claim 6 wherein the polyvinyl alcohol polymer has a degree of hydrolysis of 93 wt % to 97 wt %.

8. A method as claimed in claim 7 wherein the polyvinyl alcohol polymer has a degree of hydrolysis of 93 wt % to 95 wt %.

9. A method as claimed in claim 1, wherein the polyvinyl alcohol polymer comprises a lower viscosity polymer and a higher viscosity polymer, wherein both polymers have the same degree of hydrolysis.

10. A method as claimed in claim 1 wherein the processing aid is water.

11. A method as claimed in claim 1 wherein the plasticizer comprises two or more polyols selected from the group consisting of: dipentaerythritol, methyl pentanediol, triacetin, 2-hydroxy-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, tricyclic trimethylolpropane formal, D-mannitol, triglycerol; and xylose.

12. A method as claimed in claim 1 wherein the plasticizer comprises one or more compounds selected from the group consulting of caprolactam and alkoxylated polyethylene glycol.

13. A method as claimed in claim 1 wherein the plasticizer is selected from the group consisting of: dipentaerythritol, triacetin, methyl pentanediol, rosin esters and mixtures thereof.

14. A method as claimed in claim 1 wherein the reactants further comprise a reactive stabilizer selected from the group consisting of: sodium stearate, potassium oleate, sodium benzoate, calcium stearate, stearic acid, dimethyl propionic acid and mixtures thereof.

15. A method as claimed in any claim 11, wherein the amount of the reactive stabilizer is from 0.2 wt % to 5 wt %.

16. A method as claimed in claim 15, wherein the amount of the reactive stabilizer is from 0.5 wt % to 3 wt %.

17. A method as claimed in claim 16, wherein the amount of the reactive stabilizer is from 0.5 wt % to 2 wt %.

18. A method as claimed in claim 17, wherein the amount of reactive stabilizer is from 0.5 wt % to 1.5 wt %, preferably 1 wt %.

Description

EXAMPLE 1: PROPERTIES OF PLASTICISERS

[0095] The experimental results shown below illustrate properties of homopolymer polyvinyl alcohols according to this invention using various plasticisers and plasticiser combinations. The results show that the disclosed combinations provide greater stability and processability of the polymers in comparison to the traditionally used plasticisers such as glycerol. The use of these combinations has increased the range of processing conditions available for manufacture of specific polyvinyl alcohol products.

[0096] The procedure was as follows:—50 g samples were added to a batch mixer at a specific temperature and specific mixing speed. Torque was monitored. Several combinations of plasticiser were employed. The results are set out in the following Table:

TABLE-US-00004 Max Torque Torque Levelled Plasticiser Combination Temp (Nm) Value (Nm) Capa: 5.00% 210° C. 19.8 @ 9 s 4.1 MPD: 5.00% Capa: 5.00% 210° C. 5.4 @ 14 s 2.5 MPD: 5.00% TMP: 5.00% Capa: 5.00% 210° C. 7.9 @ 1:15 min 3.1 MPD: 5.00% RE1: 5.00% Capa: 5.00% 210° C. 7.9 @ 1:23 min 3.3 MPD: 5.00% RE1LO: 5.00% Capa: 5.00% 210° C. 18.8 @ 9 s 3.1 MPD: 5.00% PEG 400: 5.00% Capa: 5.00% 210° C. 18.3 @ 15 s 3.0 MPD: 5.00% Di-penta: 5.00% Capa: 5.00% 210° C. 21.7 @ 8 s 3.3 MPD: 5.00% TA: 5.00% TA: 10.00% 210° C. 19.9 @ 14 s 3.7 MPD: 5.00% RE1LO: 10.00% 210° C. 5.0 @ 7 s 0.0 TA: 5.00% TA: 5.00% 210° C. 6.1 @ 9 s 4.6 RE1: 5.00% TA: 10.00% 210° C. 8.3 @ 17s 0.0 RE1: 5.00% DP: 14.37% 210° C. 14.0 @ 8 s 2.4 TA: 4.29% TA: 14.37% 210° C. 20.7 @ 5 s 4.1 MPD: 4.29% Penta: 14.37% 210° C. 5.6 @ 20 s 1.8 TA: 4.29% Penta: 11.55% 210° C. 7.9 @ 12 s 2.4 TA: 3.45% Penta: 7.70% 210° C. 14.0 @ 10 s 3.4 TA: 2.30% Penta: 5.78% 210° C. 19.6 @ 13 s 4.0 TA: 1.73% Penta: 3.85% 210° C. 23.1 @ 12 s 4.6 TA: 1.15% MPD: 5.00% 210° C. 23.0 @ 12 s 4.6 Polyol 4525: 5.00% MPD: 5.00% 210° C. 27.5 @ 10 s 3.9 Polyol 3380: 5.00% TA: 9.33% 210° C. 22.2 @ 16 s 3.5 Polyol 3380 9.33% TA: 5.00% 210° C. 25.5 @ 38 s 4.0 Polyol 3380: 5.00% Penta: 10.00% 210° C. 7.7 @ 11 s 2.2 MPD: 5.00% Di penta: 10.00% 210° C. 14.4 @ 9 s 2.6 MPD: 5.00% Polyol 4525: 5.00% 210° C. 17.4 @ 10 s 3.8 MPD: 5.00% PEG 400: 5.00% Polyol 3380: 5.00% 210° C. 19.3 @ 9 s 3.3 MPD: 5.00% PEG 400: 5.00% Key: Capa = caprolactam MPD = methyl pentanediol TMP = trimethylol propane RE1 = resin ester (modified) RE1LO = rosin ester (lower hydroxyl) PEG 400 = polyethylene glycol 400 Di penta = dipentaerythritol TA = triacetin Penta = pentaerythritol

[0097] Plasticiser combinations with a lower torque provide a polymer with improved processability and stability.

Preferred combinations are:—

Capa: 5.00%, MPD: 5.00%, RE1: 5.00%

DP: 14.37%, TA: 4.29%

Penta: 10.00%, MPD: 5.00%

EXAMPLE 2—LOSS OF VOLATILES

[0098] The loss of volatiles during processing was measured. The results are illustrated in the following Table:—

TABLE-US-00005 % weight % weight % weight % weight % weight loss 5 loss 10 loss 15 loss 30 loss 60 Plasticiser mins mins mins mins mins TMP 1.69 2.86 3.90 6.58 10.82 Triacetin/MPD 1.11 1.98 2.74 4.66 7.43 Di penta/Triacetin 0.90 1.28 1.51 1.93 2.51 Di Penta/Triacetin/MPD 0.84 1.3 1.8 2.9 4.9 Polyol 3880/Triacetin 0.32 0.60 0.87 1.67 3.19 Triacetin/MPD 1.48 2.45 3.15 4.52 9.39 Triacetin/MPD/Capa 1.11 1.98 2.74 4.66 7.42 Rosin ester/MPD/Capa 0.55 0.96 1.35 2.39 4.13 MPD/Capa/PEG 400 0.76 1.36 1.92 3.51 6.40 Key: See Example 1

[0099] The results show that the stability of the polymer is improved when using the plasticiser combinations of this invention. Particularly advantageous combinations include rosin ester, MPD and Capa; and also Polyol 3880 with triacetin. These show a decreased weight loss in the region of <5%.

EXAMPLE 3: DIFFERENTIAL SCANNING CALORIMETRY (DSC)

[0100] DSC parameters used to scan the polymers were as follows:— [0101] (1) Heat from 0° C. to 250° C. at a heating rate of 10° C./min [0102] (2) Cool from 0° C. to 250° C. at a rate of 10° C./min [0103] (3) Heat from 0° C. to 250° C. at a rate of 10° C./min

[0104] The results are shown in the following Table:

TABLE-US-00006 Plasticiser Tg ° C. Tm ° C. (peak) Polyol 3990/Penta 57 208 TMP/Penta 47 211 D-Mannitol 49 211 MPD/Dipenta 59 213 Capa/TA 55 165 TA/MPD/Di penta 62 180 Rosin Ester/MPD/Capa 63 183 TA/Polyol 3380 59 170 Capa/MPD/PEG 400 57 183 Key: See Example 1

EXAMPLE 4: CAPILLARY RHEOMETRY DATA

[0105] The method used for the capillary rheometer was a shear sweep test with shear rates ranging from 8245.87 to 82.46 1/s. This method was used to test a range of viscosities and both high and low shear rates. The test was performed at 200° C. with a melt time of five minutes in order to give a sufficiently molten polymer with limited degradation for the test. The conditions were altered depending on the grades/viscosities required. For lower viscosity grades the test was performed at 220° C. and for higher viscosity grades at 230° C. The results are shown in FIGS. 1 to 3:

EXAMPLE 5: QUALITY OF POLYMERS ON AN EXTRUSION COATING LINE

[0106] The following Table illustrates the quality of polymers using various plasticisers on an extrusion line.

EXAMPLE 6: PROPERTIES OF PLASTICISED BLENDS

[0107] The polyvinyl alcohol used consisted of a blend of two polyvinyl alcohol polymers each having a degree of hydrolysis of 93% to 98%, one with a high molecular weight and one with a low molecular weight polyvinyl alcohol. The ratio of the polyvinyl alcohols used was 75% high molecular weight polyvinyl alcohol to 25% low molecular weight polyvinyl alcohol. One or more plasticisers were used comprising 12 wt % and one or more processing aids comprising 11 wt % of the polymer composition. This formulation had a high viscosity that was suitable for blown film applications.

TABLE-US-00007 Plasticiser Adhesion Adhesion Adheshion combination Nibs Gels Holes Curtain Coating 30μ 20-25μ 15-20μ Capa, MPD, No No No Good Good Poor Poor Poor and PEG 400 Di penta, No No Yes Good Poor Poor Poor Poor Glycerol Di penta, No No No Good Good Poor Poor Poor MPD MPD No No No Good Good Poor Poor Poor Rosin Ester, No No Few Good Good Poor Poor Poor MPD Rosin Ester, No No Few Good Good Poor Poor Poor MPD and Capa MPD, Capa No No Few Good Good Poor Poor Poor Dipenta, TA No Yes Yes Good Good Good Good Good Penta, TA No No Few Good Good Good Good Good Dipenta, No No No Good Good Good Good OK MPD and Capa TA, MPD Yes No No Good Good Good Good OK and Capa

EXAMPLE 7: RHEOLOGY

[0108] The polyvinyl alcohol used consisted of a blend of two polyvinyl alcohol polymers each having a degree of hydrolysis of 80% to 98%, one with a high molecular weight and one with a low molecular weight polyvinyl alcohol. The ratio of the polyvinyl alcohol in the polymer was 50 wt % high molecular weight polyvinyl alcohol and 50 wt % low molecular weight polyvinyl alcohol. One or more plasticisers were used comprising 20 wt % of the polymer composition and one or more processing aids in an amount of 10 wt % of the polymer. The formulation had a low viscosity that was suitable for extrusion coating application.

[0109] Analytical data showed the differences in the two formulations.

[0110] The results showed that by changing the polyvinyl alcohol combinations the rheology/viscosity of the polymer can be controlled. The extrusion coating formulation has a lower viscosity than the blown film formulation.

[0111] DSC data showed the difference in crystallization temperatures and melting peaks of the two formulations. The extrusion coating recrystalized at a temperature of 140° C. whereas the blown film recrystallized at a higher temperature of 180° C. This can be advantageous for certain applications where the polymer is desired to stay molten for a longer time. The melting temperature of the polymers was changed with the extrusion coating melting at 195° C. and the blown film melting at 215° C.

[0112] Thermogravimetric analysis (TGA) showed that the lower hydrolysis polyvinyl alcohol combinations (extrusion coating) were more susceptible to degradation than the polymers with a higher degree of hydrolysis. Both combinations had a degradation temperature of approximately 300° C., but the higher degree of hydrolysis combination degraded over a much shorter temperature range than the lower degree of hydrolysis combination.