Plasticizer-free article made of PVC graft copolymers

Abstract

The invention relates to blends of vinyl chloride graft copolymers as well as to a method for preparing such vinyl chloride graft copolymers and their blends. The invention also relates to molded articles manufactured by using the blends according to the invention.

Claims

1. A polymer blend, comprising: a first vinyl chloride graft copolymer prepared using emulsion polymerization and including a graft base having a first glass transition temperature and a grafted copolymer phase including vinyl chloride and having a second glass transition temperature, the first vinyl chloride graft copolymer having a first percentage weight distribution of graft base and grafted copolymer phase; and a second vinyl chloride graft copolymer prepared using emulsion polymerization and including the graft base and the grafted copolymer phase, the second vinyl chloride graft copolymer having a second percentage weight distribution of graft base and grafted copolymer phase which is different than the first percentage weight distribution, wherein the first and second vinyl chloride graft copolymers have an average particle size below 300 nm.

2. The polymer blend of claim 1, wherein the first glass transition temperature is from about 80 C. to about 20 C.

3. The polymer blend of claim 2, wherein the second glass transition temperature is from about 20 C. to about 120 C.

4. The polymer blend of claim 1, wherein the first vinyl chloride graft copolymer includes: the graft base in an amount from about 41 wt. % to about 70 wt. % by weight of the first vinyl chloride graft copolymer and the grafted copolymer phase in an amount from about 30 wt. % to about 59 wt. % by weight of the first vinyl chloride graft copolymer.

5. The polymer blend of claim 1, wherein the first vinyl chloride graft copolymer includes: the graft base in an amount from about 26 wt. % to about 40 wt. % by weight of the first vinyl chloride graft copolymer and the grafted copolymer phase in an amount from about 60 wt. % to about 74 wt. % by weight of the first vinyl chloride graft copolymer.

6. The polymer blend of claim 1, wherein the first vinyl chloride graft copolymer includes: the graft base in an amount from about 5 wt. % to about 25 wt. % by weight of the first vinyl chloride graft copolymer and the grafted copolymer phase in an amount from about 75 wt. % to about 95 wt. % by weight of the first vinyl chloride graft copolymer.

7. The polymer blend of claim 1, wherein the first and second vinyl chloride graft copolymers are selected from the group consisting of: vinyl chloride graft copolymer A including the graft base in an amount from about 41 wt. % to about 70 wt. % by weight of the vinyl chloride graft copolymer A and the grafted copolymer phase in an amount from about 30 wt. % to about 59 wt. % by weight of the vinyl chloride graft copolymer A; vinyl chloride graft copolymer B including the graft base in an amount from about 26 wt. % to about 40 wt. % by weight of the vinyl chloride graft copolymer B and the grafted copolymer phase in an amount from about 60 wt. % to about 74 wt. % by weight of the vinyl chloride graft copolymer B; and vinyl chloride graft copolymer C including the graft base in an amount from about 5 wt. % to about 25 wt. % by weight of the vinyl chloride graft copolymer C and the grafted copolymer phase in an amount from about 75 wt. % to about 95 wt. % by weight of the vinyl chloride graft copolymer C.

8. The polymer blend of claim 7 and further comprising: from about 0 to about 75 wt. % additional ingredients by weight of the polymer blend; and optionally, a third vinyl chloride graft copolymer prepared using emulsion polymerization and including the graft base and the grafted copolymer phase, the third vinyl chloride graft copolymer having a third percentage weight distribution of graft base and grafted copolymer phase which is different than the first and second percentage weight distributions, wherein the first, second and optional third vinyl chloride graft copolymers are selected from the group consisting of: the vinyl chloride graft copolymer A, present in an amount from about 1.0 wt. % to about 99 wt. % by weight of the polymer blend; the vinyl chloride graft copolymer B present in an amount from about 1.0 wt. % to about 99 wt. % by weight of the polymer blend; and the vinyl chloride graft copolymer C present in an amount from about 1.0 wt. % to about 99 wt. % by weight of the polymer blend, wherein the grafted copolymer phase has a glass transition temperature from about 20 C. to about 120 C., and the graft base has a glass transition temperature from about 80 C. to about 20 C., and wherein the sum of the vinyl chloride graft copolymer, the second vinyl chloride graft copolymer, the optional third vinyl chloride graft copolymer and the additional ingredients adds up to 100 wt. %.

9. The polymer blend of claim 1, wherein the graft base is prepared by copolymerizing vinyl compounds.

10. The polymer blend of claim 1, wherein the grafted copolymer phase of the first vinyl chloride graft copolymer includes about 60 wt. % to about 100 wt. % vinyl chloride by weight of the grafted copolymer phase and from about 0 wt. % to about 40 wt. % by weight of the grafted copolymer phase other vinyl compounds.

11. The polymer blend of claim 1, wherein the graft base of the first vinyl chloride graft copolymer is cross-linked.

12. The polymer blend of claim 1, wherein the grafted copolymer phase of the first vinyl chloride graft copolymer is cross-linked.

13. The polymer blend of claim 1, wherein the polymer blend has a transmittance of at least 65% as measured according to ISO 13468 for a plate having a thickness from 1.46 mm to 1.74 mm.

14. The polymer blend of claim 1, wherein the polymer blend has a haze value of less than 60 as measured according to ISO 13468 for a plate having a thickness from 1.46 mm to 1.74 mm.

15. A method of forming a polymer blend, the method comprising: forming a first vinyl chloride graft copolymer solid having an average particle size below 300 nm by polymerizing a graft base having a first glass transition temperature; and grafting a copolymer phase including vinyl chloride and having a second glass transition temperature onto the graft base using emulsion polymerization; forming a second vinyl chloride graft copolymer solid having an average particle size below 300 nm by polymerizing the graft base; and grafting the copolymer phase onto the graft base using emulsion polymerization; and mixing the first and second vinyl chloride graft copolymer solids to form the polymer blend, wherein the first and second vinyl chloride graft copolymer solids differ from each other by their percentage weight distribution of grafted copolymer phase and graft base.

16. The method of claim 15, wherein forming the first and second vinyl chloride graft copolymers includes grafting the copolymer phase onto the graft base by emulsion polymerization using at least one emulsifier.

17. The method of claim 15, wherein a polymerization temperature for the graft base is from about 20 C. to about 90 C.

18. The method of claim 15, wherein a grafting polymerization temperature for the grafted copolymer phase is from about 45 C. to about 90 C.

19. The method of claim 15, wherein the polymer blend has a transmittance of at least 65% as measured according to ISO 13468 for a plate having a thickness from 1.46 mm to 1.74 mm.

20. The method of claim 15, wherein the polymer blend has a haze value less than 60 as measured according to ISO 13468 for a plate having a thickness from 1.46 mm to 1.74 mm.

Description

EXAMPLES

Example 1

(1) Graft Base

(2) Into a 10-liter stirrer reactor with a water-cooled double jacket and equipped with a paddle agitator, 1166 g of deionized water, 68.6 g of butyl acrylate, 3088 g of a 1% solution of potassium myristate and 0.63 g of potassium peroxodisulfate were pre-charged and heated to 80 C. After the reaction had started, addition of 686 g of a 0.3% aqueous potassium peroxodisulfate solution within 180 min was started. Simultaneously, 1990 g of butyl acrylate were added within 180 min. After the addition had ended, the interior reactor temperature was maintained for 60 min and the preparation was cooled down subsequently. 6894 g of dispersion were discharged, having a solid content of 30%, a surface tension of 51.6 mN/m and a pH of 7.6. The average volume-based particle size (PSV) was 12 nm.

(3) Graft Copolymer

(4) Into a 10-liter autoclave with a water-cooled double jacket and a paddle agitator, 124 g of water, 1937 g of a 1% solution of potassium myristate, 3500 g of graft base and 1283 g of vinyl chloride were pre-charged and heated to 68 C. When the polymerization temperature was reached, addition of potassium peroxodisulfate and ascorbic acid was started. The adding speed was adjusted in such a way that the difference between the interior temperature and the supply temperature of the jacket cooling was about 10 C. After the pressure had dropped by 4 bar, the preparation was set to cool and depressurized. The dispersion was discharged. The solid content of the dispersion was 31.3 wt %, the surface tension was 56.6 mN/m, the pH was 8.3. The average volume-based particle size was 68 nm. The preparation was precipitated with calcium chloride and filtered by suction filtration. The residue was dried at 30 C. in a recirculating-air dryer to a residual moisture of <0.3% and finely ground with a centrifugal mill (Retsch ZM 200). The PBA content was determined to be 48.6 wt % by an oxygen analysis.

Example 2

(5) Graft Base

(6) The graft base was prepared following Example 1. 6936 g of dispersion were discharged, having a solid content of 30 wt %, a surface tension of 49 mN/m and a pH of 7.5. The average volume-based particle size was 14 nm.

(7) Graft Copolymer

(8) 407 g of water, 2471 g of a 1% potassium myristate solution, 2330 g of graft base and 1633 g of vinyl chloride were pre-charged and polymerized following Example 1. The dispersion was discharged. The solid content of the dispersion was 30.1%, the surface tension was 57.8 mN/m, the pH was 8.8. The average volume-based particle size was 64 nm. The preparation was precipitated with calcium chloride and filtered by suction filtration. The residue was dried at 30 C. in a recirculating-air dryer to a residual moisture of <0.3% and finely ground with a centrifugal mill (Retsch ZM 200). The PBA content was determined to be 34.4 wt % by an oxygen analysis.

Example 3

(9) Graft Base

(10) Into a 10-liter reactor with stirrer, 4156 g of deionized water, 0.4 g of allyl methacrylate, 78 g of butyl acrylate, 705.9 g of potassium myristate (concentration: 5 wt %) and 0.720 g of potassium peroxodisulfate were pre-charged and heated to 80 C. After the reaction had started, addition of 784.3 g of a 0.3% aqueous solution of potassium peroxodisulfate within 180 min was started. Simultaneously, 11.36 g of allyl methacrylate and 2263 g of butyl acrylate were added within 180 min. After the addition had ended, the interior reactor temperature was maintained for 60 min and the preparation was cooled down subsequently. 7911 g of dispersion were obtained. The solid content was 29.8%, the surface tension was 52.2 mN/m and the pH was 7.6. The average volume-based particle size was 12 nm.

(11) Graft Copolymer

(12) Into a 10-liter autoclave with a water-cooled double jacket and a paddle agitator, 1367 g of water, 332 g of a 5% solution of potassium myristate, 3087 g of graft base, 4.32 g of diallyl phthalate and 1076 g of vinyl chloride were pre-charged and heated to 68 C. When the polymerization temperature was reached, the addition of potassium peroxodisulfate and ascorbic acid was started. The adding speed was adjusted in such a way that the difference between the interior temperature and the supply temperature of the jacket cooling was about 10 C. After the pressure had dropped by 4 bar, the preparation was set to cool and de-depressurized. The dispersion was discharged. The solid content was 30.7 wt %, the surface tension was 56.7 mN/m, the pH was 7.7. The average volume-based particle size was 61 nm. The preparation was precipitated with calcium chloride and filtered by suction filtration. The residue was dried at 30 C. in a recirculating-air dryer to a residual moisture of <0.3% and finely ground with a centrifugal mill (Retsch ZM 200). The PBA content was determined to be 46.9 wt % by an oxygen analysis.

Example 4

(13) Graft Base

(14) The graft base of Example 3 was used.

(15) Graft Copolymer

(16) Into a 10-liter autoclave with a water-cooled double jacket and a paddle agitator, 2365 g of water, 387.3 g of a 5% solution of potassium myristate, 2506 g of graft base, 6.347 g of diallyl phthalate and 1580 g of vinyl chloride were pre-charged and heated to 68 C. When the polymerization temperature was reached, the addition of potassium peroxodisulfate and ascorbic acid was started. The adding speed was adjusted in such a way that the difference between the interior temperature and the supply temperature of the jacket cooling was about 10 C. After the pressure had dropped by 4 bar, the preparation was set to cool and depressurized. The dispersion was discharged. The solid content of the dispersion was 30.5 wt %, the surface tension was 58.5 mN/m, the pH was 8.0. The average volume-based particle size was 58 nm. The preparation was precipitated with calcium chloride and filtered by suction filtration. The residue was dried at 30 C. in a recirculating-air dryer to a residual moisture of <0.3% and finely ground with a centrifugal mill (Retsch ZM 200). The PBA content was determined to be 33 wt % by an oxygen analysis.

Example 5

(17) Graft Base

(18) The preparation of Example 3 was repeated. 7909 g of an aqueous dispersion were discharged. The solid content of the dispersion was 30%, the surface tension was 54.4 mN/m, the pH was 7.4. The average volume-based particle size was 12 nm.

(19) Graft Copolymer

(20) 3144 g of water, 387.3 g of a 5% potassium myristate solution, 1400 g of graft base, 1906 g of vinyl chloride and 7.63 g of diallyl phthalate were pre-charged and then polymerized following Example 3. The dispersion was discharged. The solid content of the dispersion was 29.6 wt %, the surface tension was 51.9 mN/m, the pH was 8.1. The average volume-based particle size was 56 nm. The preparation was precipitated with calcium chloride and filtered by suction filtration. The residue was dried at 30 C. in a recirculating-air dryer to a residual moisture of <0.3% and finely ground with a centrifugal mill (Retsch ZM 200). The PBA content was determined to be 19.2 wt % by an oxygen analysis.

(21) On a two-roll roller the powdered graft copolymers were processed and pressed into rolled sheets. In the following Table 1, the poly(butyl acrylate) content, the cross-linking, the particle sizes of the graft copolymers and the optical properties (transmittance, haze) are given.

(22) Experimental Procedures:

(23) Measurement of Particle Sizes:

(24) The particle size distributions were measured with a Microtrac Blue-Wave of the S 3500 series by Particle Metrix. The valid measuring range lies between 0.01 and 2000 m. For the measurement, a standard procedure for dispersions was created, where certain physical properties of the dispersion were given. Before measurement, three drops of Hellmanex by Hellmanex-Analytics Inc. were added to the deionized water inside the circulation unit, using a disposable 3 ml pipette. The cleanliness of the measurement system was validated by a baseline measurement. Dispersion was added carefully to the sample unit until a loading factor of about 0.004 was reached. Normally, 1 or 2 drops of dispersion are sufficient. The measurement time was 30 s. Evaluation of the measurement is carried out automatically. The average volume-based particle size is used.

(25) Two-Roll Rolling Mill (Including Processing Conditions and Recipe)

(26) In order to determine mechanical values and optical properties, test samples have to be provided. The preparation of the rolled sheets is performed under the following conditions.

(27) TABLE-US-00001 Recipe (spatula blend) 100 phr Polymer 1.5 phr BaZn stabilizer (Baerostab UBZ 171) 3.0 phr Epoxydated soy bean oil (Edenol D 81) 0.1 phr Isotridecyl stearate (Loxiol G 40) 0.2 phr High-molecular weight multicomponent ester (Loxiol G 72) 0.1 phr Calcium stearate (Ceasit SW)
Rolling mill (made by Schwabenthan)
Roller material: chromed surfaces
Roller diameter: 150 mm
Speed ratio: 17/21 1/min
Roller temperature: 140 C.
Rolling time: 5 min
Execution:

(28) In order to form a cohesive mass (sheet) the powder compound is placed onto the roller. After formation of the sheet, the sheet is cut and turned for 3 min. Then set the thickness of the rolled sheet to 1.1 mm and continue to plasticize the sheet on the roller for further 2 min without cutting and turning. When the specified rolling time is over, the rolled sheet is taken off.

(29) Press

(30) 30-ton laboratory press (Werner & Pfleiderer URH 30)

(31) Press area: 350350 mm

(32) Pressing plates: chromed surfaces

(33) Pressing frame: 2202201.0 mm

(34) Execution:

(35) For making the press plates, the previously produced rolled sheets were cut corresponding to the frame size used, inserted into the frame and placed into the laboratory press together with the press plates that form the outer surfaces. The sheets are formed into a press plate under the conditions described below.

(36) TABLE-US-00002 Press temperature: 150 C. LP press power: 30 bar LP pressing time: 2 min HP press power: 200 bar HP pressing time: 3 min Removal temperature: 40 C. Cooling pressure: 200 bar Cooling time: ca. 8 min
Transmittance and Haze (Large-Angle Scattering)

(37) In order to evaluate a film's transparency, two values were considered: the total transmittance (here: transmittance), which stands for the ratio of transmitted light to incident light and which depends on absorption properties and surface conditions large-angle scattering (haze), which is a measure for opaqueness.
Measurement:

(38) Measurement of the transmittance and determination of the large-angle scattering of the semi-finished products produced with rollers/presses is carried out with the transparency meter Haze-Gard Dual by Byk-Gardner Inc.

(39) The sample to be measured is illuminated perpendicularly and the transmitted light is photoelectrically measured in an integrating sphere. In this process, the perpendicularly transmitted light is measured in order to evaluate the transmittance, and the light that is scattered in an angle of 2 to the axis of irradiation is measured to evaluate the opaqueness (haze). The measurements are carried out according to ISO 13468, which guarantees that the measurement conditions are the same during calibration as well as during measurement.

(40) TABLE-US-00003 TABLE 1 Overview: Test Samples and Press Plates Made Therefrom PBA Microtrac Content MV Shore Shore Thickness of Patent Examples (wt %) (nm) Hardness A Hardness D Press Plate (mm) Transmittance, % Haze Remarks Example 1 48.6 68 88 28 1.46 84.7 11.2 Graft base and graft Example 2 34.4 64 53 1.46 77.2 36.5 shell non-cross- linked Example 3 46.9 61 85 26 1.50 84 13.2 Graft base and graft Example 4 33 58 97 46 1.68 80.7 6.92 shell cross-linked Example 5 19.2 56 97 59 1.74 74.8 9.08 and PSV <150 nm Blend Example 1 29.6 94 59 1.67 75.4 16.4 0.75 Example 4 + 0.25 Example 5 Blend Example 2 41.5 41 1.56 78.4 24.4 0.50 Example 1 + 0.50 Example 2 Blend Example 3 40 92 38 1.49 69.9 93.2 0.75 Example 3 + 0.25 Example 5 Vinnolit VK 710 ca. 50 85 28 1.48 78.0 65.8 Competitive product Vinnolit K 707 E ca. 50 79 25 1.81 53.9 68.8 sample

(41) Blends consisting of the graft copolymers according to the invention, which differ from each other in their PBA content, show a high transparency. This is a major advantage as compared to blends of a transparent graft copolymer with S-PVC, which are opaque. The press plate of the transparent graft copolymer of Example 3 becomes opaque due to a content of 25 wt % of S-PVC.