Transparent article made of PVC graft copolymers

Abstract

The invention relates to a method for producing vinyl chloride graft copolymers by emulsion polymerization and to a method for producing mixtures of said graft copolymers. The invention also relates to transparent articles produced using the claimed graft copolymers or mixtures thereof.

Claims

1. A transparent article formed of a vinyl chloride graft copolymer, the article prepared by a process comprising: forming the vinyl chloride graft copolymer by: preparing a graft base by polymerizing monomers, wherein the graft base has a first glass transition temperature; grafting a copolymer phase having a second glass transition temperature onto the graft base by emulsion polymerization, to form a vinyl chloride graft copolymer latex including the vinyl chloride graft copolymer; and separating the vinyl chloride graft copolymer as a solid from the vinyl graft copolymer latex, wherein the first glass transition temperature is lower than the second glass transition temperature, the average particle size of the vinyl chloride graft copolymer is less than 200 nm, and the article has a transmittance of at least 65% as measured according to ISO 13468 for a plate having a thickness from 1.49 mm to 1.74, a haze value of less than 60 as measured according to ISO 13468 for a plate having a thickness from 1.49 mm to 1.74 and measured at an angle of 2 degrees to an axis of irradiation, or a transmittance of at least 65% as measured according to ISO 13468 for a plate having a thickness from 1.49 mm to 1.74 and a haze value of less than 60 as measured according to ISO 13468 for a plate having a thickness from 1.49 mm to 1.74 and measured at an angle of 2 degrees to an axis of irradiation.

2. The transparent article of claim 1, wherein the second glass transition temperature is from about 20 C. to about 120 C. and the first glass transition temperature is from about 80 C. to about 20 C.

3. The transparent article of claim 1, wherein the copolymer phase is grafted onto the graft base by emulsion polymerization using at least one emulsifier.

4. The transparent article of claim 3, wherein from about 60 wt. % to about 100 wt. % of the at least one emulsifier is pre-charged, based on the total amount of the at least one emulsifier.

5. The transparent article of claim 1, wherein the graft base of monomers is polymerized at a temperature of from about 20 C. to about 90 C.

6. The transparent article of claim 1, wherein the copolymer phase is grafted onto the graft base at a temperature of from about 45 C. to about 90 C.

7. The transparent article of claim 1, wherein the vinyl chloride graft copolymer includes from about 5 wt. % to about 70 wt. % of the graft base and from about 30 wt. % to about 95 wt. % of the copolymer phase.

8. The transparent article of claim 1, wherein the graft base includes a first polymerized vinyl compound and a second polymerized vinyl compound.

9. The transparent article of claim 1, wherein the copolymer phase comprises from about 60 wt. % to about 100 wt. % vinyl chloride and from about 0 wt. % to about 40 wt. % polymerized vinyl compounds.

10. The transparent article of claim 1, wherein the graft base, the grafted copolymer phase, or a combination thereof are cross-linked.

11. The transparent article of claim 1 prepared by the process further comprising: forming a second vinyl chloride graft copolymer by: grafting the copolymer onto the graft base by emulsion polymerization to form a second vinyl chloride graft copolymer latex including the second vinyl chloride graft copolymer; and separating the second vinyl chloride graft copolymer as a solid from the second vinyl graft copolymer latex; and combining the vinyl chloride graft copolymer and the second vinyl chloride graft copolymer, wherein the weight ratio of the graft base to the grafted copolymer base of the vinyl chloride graft copolymer is different than that of the second vinyl chloride graft copolymer.

12. The transparent article of claim 11, wherein the vinyl chloride graft copolymer and the second vinyl chloride graft copolymer are selected from the group consisting of: graft copolymer A including from about 41 wt. % to about 70 wt. % of the graft base and from about 30 wt. % to about 59 wt. % of the grafted copolymer phase; graft copolymer B including from about 26 wt. % to about 40 wt. % of the graft base and from about 60 wt. % to about 74 wt. % of the grafted copolymer phase; and graft copolymer C including from about 5 wt. % to about 25 wt. % of the graft base and from about 75 wt. % to about 95 wt. % of the grafted copolymer phase.

13. The transparent article of claim 12, wherein the vinyl chloride graft copolymer and the second vinyl chloride graft copolymer are selected from the group consisting of: from about 1.0 wt. % to about 99 wt. % graft copolymer A; from about 1.0 wt. % to about 99 wt. % graft copolymer B; and from about 1.0 wt. % to about 99 wt. % graft copolymer C; wherein the graft base has a glass transition temperature from about 80 C. to about 20 C., the grafted copolymer phase has a glass transition temperature from about 20 C. to about 120 C., and the transparent article contains at least 25 wt. % of the vinyl chloride graft copolymer and the second copolymer.

14. The transparent article of claim 1 prepared by the process further comprising: forming a second vinyl chloride graft copolymer by: grafting the copolymer onto the graft base by emulsion polymerization to form a second vinyl chloride graft copolymer latex including the second vinyl chloride graft copolymer; and separating the second vinyl chloride graft copolymer as a solid from the second vinyl graft copolymer latex; forming a third vinyl chloride graft copolymer by: grafting the copolymer onto the graft base by emulsion polymerization to form a third vinyl chloride graft copolymer latex including the third vinyl chloride graft copolymer; and separating the third vinyl chloride graft copolymer as a solid from the third vinyl graft copolymer latex; and combining the vinyl chloride graft copolymer, the second vinyl chloride graft copolymer, and the third vinyl chloride graft copolymer, wherein the weight ratio of the graft base to the grafted copolymer base of the vinyl chloride graft copolymer is different than that of the second vinyl chloride graft copolymer and the weight ratio of the graft base to the grafted copolymer base of the third vinyl chloride graft copolymer is different than the vinyl chloride graft copolymer and the second vinyl chloride graft copolymer.

15. The transparent article of claim 14, wherein the vinyl chloride graft copolymer, the second vinyl chloride graft copolymer, and the third vinyl chloride graft copolymer are selected from the group consisting of: graft copolymer A including from about 41 wt. % to about 70 wt. % of the graft base and from about 30 wt. % to about 59 wt. % of the grafted copolymer phase; graft copolymer B including from about 26 wt. % to about 40 wt. % of the graft base and from about 60 wt. % to about 74 wt. % of the grafted copolymer phase; and graft copolymer C including from about 5 wt. % to about 25 wt. % of the graft base and from about 75 wt. % to about 95 wt. % of the grafted copolymer phase.

16. The transparent article of claim 15, wherein the vinyl chloride graft copolymer, the second vinyl chloride graft copolymer, and the third vinyl chloride graft copolymer are selected from the group consisting of: from about 1.0 wt. % to about 99 wt. % graft copolymer A; from about 1.0 wt. % to about 99 wt. % graft copolymer B; and from about 1.0 wt. % to about 99 wt. % graft copolymer C; wherein the grafted copolymer phase has a glass transition temperature from about 20 C. to about 120 C., the graft base has a glass transition temperature from about 80 C. to about 20 C., and the transparent article contains at least 25 wt. % of the vinyl chloride graft copolymer, the second vinyl chloride graft copolymer, and the third vinyl chloride graft copolymer.

Description

EXAMPLES

Example 1

Graft Base

(1) 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, adding of 784.3 g of a 0.3% aqueous solution of potassium peroxodisulfate was carried out within 180 min. Simultaneously, 11.36 g of allyl methacrylate and 2263 g of butyl acrylate were added within 180 min. After the addition had ended the reaction temperature was maintained for 60 min and the preparation was cooled down subsequently.

(2) 7911 g of the 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 (PSV) was 12 nm.

Graft Copolymer

(3) 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, adding 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 bars, the preparation was set to cool and depressurized. The dispersion was discharged. The solid content of the dispersion 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 2

Graft Base

(4) The graft base of Example 1 was used.

Graft Copolymer

(5) 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, adding 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 bars, 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 3

Graft Base

(6) The preparation of Example 1 was repeated. 7909 g of an aqueous dispersion were discharged. The solid content of the dispersion was 30 wt %, the surface tension was 54.4 mN/m, the pH was 7.4. The average volume-based particle size was 12 nm.

Graft Copolymer

(7) 3144 g of water, 387.3 g of a 5% solution of potassium myristate, 1400 g of graft base, 1906 g of vinyl chloride and 7.63 g of diallyl phthalate were pre-charged and polymerized following Example 1. 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.

Example 4

Graft Base

(8) Into a 10-liter reactor with stirrer, 2642 g of deionized water, 0.80 g of diallyl phthalate, 77 g of butyl acrylate, 315.3 g of potassium myristate (concentration: 1.85 wt %) and 0.714 g of potassium peroxodisulfate were pre-charged and heated to 80 C. After the reaction had started, adding of 1167 g of a 0.1% aqueous solution of ammonium peroxodisulfate was carried out within 180 min. Simultaneously, 22.55 g of diallyl phthalate, 2233 g of butyl acrylate and 1009 g of a 1.85% potassium myristate solution 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. 7335 g of the dispersion were obtained. The solid content was 30.9%, the surface tension was 54.4 mN/m and the pH was 8.3.

Graft Copolymer

(9) 2144 g of water, 280 g of 5% potassium myristate solution and 3021 g of graft base were pre-charged and heated to 68 C. Then, 117 g of vinyl chloride were added and further 1278 g of vinyl chloride were added within 100 min. For the activation, a hydrogen peroxide solution and an ascorbic acid solution were used. 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 bars, the preparation was set to cool and depressurized. The solid content of the dispersion was 28.8 wt %, the surface tension was 54.9 mN/m, the pH was 7.5. The average volume-based particle size was 92 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 41.1 wt % by an oxygen analysis.

Example 5

Graft Base

(10) Into a 10-liter reactor with stirrer, 1784 g of deionized water, 68.25 g of butyl acrylate, 0.35 g of allyl methacrylate, 411.8 g of potassium myristate (concentration: 1 wt %), and 0.63 g of potassium peroxodisulfate were pre-charged and heated to 80 C. After the reaction had started, adding of 686 g of a 0.3% aqueous solution of potassium peroxodisulfate was performed within 180 min. Simultaneously, 1980 g of butyl acrylate, 9.94 g of allyl methacrylate and 2059 g of a 1% potassium myristate solution 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. 6963 g of the dispersion were discharged, having a solid content of 29.6 wt %, the surface tension was 56.4 mN/m and the pH was 8.1. The average volume-based particle size was 74 nm.

Graft Copolymer

(11) The preparation was prepared following Example 1. The solid content of the dispersion was 32.4 wt %, the surface tension was 48.8 mN/m, the pH was 8.0. The average volume-based particle size was 131 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 50.0 wt % by an oxygen analysis.

(12) The samples according to the invention can be processed to transparent press plates. The samples according to the invention are characterized in that both the graft base and the graft shell are non-cross-linked, or that the graft base is non-cross-linked while the graft shell is cross-linked, or that the average particle size is below 150 nm when both the graft base and the graft shell are cross-linked, or when only the graft base is cross-linked while the graft shell is non-cross-linked.

(13) The Comparative Examples mentioned below give proof that such press plates are opaque that were made from graft copolymers having a particle size of greater than 150 nm, which have both a cross-linked graft base and a cross-linked graft shell or which have a cross-linked graft base and a non-cross-linked graft shell.

Comparative Example 1

Graft Base

(14) Into a 10-liter reactor with stirrer, 1887 g of deionized water, 68.25 g of butyl acrylate, 0.35 g of allyl methacrylate, 308.8 g of potassium myristate (concentration: 1 wt %), and 0.63 g of potassium peroxodisulfate were pre-charged and heated to 80 C. After the reaction had started, adding of 686 g of a 0.3% aqueous solution of potassium peroxodisulfate was performed within 180 min. Simultaneously, 1980 g of butyl acrylate, 9.94 g of allyl methacrylate and 2059 g of a 1% potassium myristate solution 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. 6925 g of the dispersion were discharged, having a solid content of 29.6 wt %, a surface tension of 52.6 mN/m and a pH of 8.2. The average volume-based particle size was 135 nm.

Graft Copolymer

(15) The preparation was prepared following Example 1. The solid content of the dispersion was 28.3 wt %, the surface tension was 42.5 mN/m, the pH was 8.4. The average volume-based particle size was 176 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 49.6 wt % by an oxygen analysis.

Comparative Example 2

Graft Base

(16) Into a 10-liter reactor with stirrer, 1990 g of deionized water, 68.25 g of butyl acrylate, 0.35 g of allyl methacrylate, 205.9 g of potassium myristate (concentration: 1 wt %), and 0.63 g of potassium peroxodisulfate were pre-charged and heated to 80 C. After the reaction had started, adding of 686 g of a 0.3% aqueous solution of potassium peroxodisulfate was performed within 180 min. Simultaneously, 1980 g of butyl acrylate, 9.94 g of allyl methacrylate and 2059 g of a 1% potassium myristate solution 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. The average volume-based particle size was 180 nm.

Graft Copolymer

(17) The preparation was prepared following Example 1. The solid content of the dispersion was 26.3 wt %, the surface tension was 40.8 mN/m, the was pH 8.8. 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 52 wt % by an oxygen analysis. The average volume-based particle size was 224 nm.

Comparative Example 3

Graft Base

(18) Into a 10-liter reactor with stirrer, 2134 g of deionized water, 68.29 g of butyl acrylate, 0.34 g of allyl methacrylate, 61.76 g of potassium myristate (concentration: 1 wt %) and 0.63 g of potassium peroxodisulfate were pre-charged and heated to 80 C. After the reaction had started, adding of 686.3 g of a 0.3% aqueous solution of potassium peroxodisulfate was performed within 180 min. Simultaneously, 1980 g of butyl acrylate, 9.94 g of allyl methacrylate and 2059 g of a 1% potassium myristate solution were added within 180 min. After the addition had ended the interior reactor temperature was maintained for 60 min the preparation was cooled down subsequently. 6998 g of an aqueous dispersion, having a solid content of 29.6 wt %, a surface tension of 47.9 mN/m and a pH of 8.3, were obtained. The average volume-based particle size was 272 nm.

Graft Copolymer

(19) Into a 10-liter autoclave with a water-cooled double jacket and a paddle agitator, 1515 g of water, 387 g of a 5% solution of potassium myristate, 3705 g of graft base, 9.33 g of diallyl phthalate and 1227 g of vinyl chloride were pre-charged and heated to 68 C. When the polymerization temperature was reached, adding 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 bars, the preparation was set to cool and depressurized. The dispersion was discharged. The solid content of the dispersion was 27.1 wt %, the surface tension was 38.8 mN/m, the pH was 8.2. 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 56.6 wt % by an oxygen analysis. The average volume-based particle size was 336 nm.

Comparative Example 4

Graft Base

(20) The same graft base as in Example 3 was used.

Graft Copolymer

(21) 1299 g of water, 332 g of a 5% potassium myristate solution, 3176 of graft base and 1060 g of vinyl chloride were pre-charged and then polymerized based on Comparative Example 3. The dispersion was discharged. The solid content of the dispersion was 27.1 wt %, the surface tension was 37.4 mN/m, the pH was 8.7. 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 57.2 wt % by an oxygen analysis. The average volume-based particle size was 327 nm.

(22) 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 degree of cross-linking, the particle sizes of the graft copolymers and the optical properties (transmittance, haze) are given.

Experimental Procedures

Measurement of Particle Sizes

(23) The particle size distributions were measured with a Microtrac Blue-Wave of the S3500 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.

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

(24) 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.

(25) 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 multi-part adhesive (Loxiol G 72) 0.1 phr Calcium stearate (Ceasit SW)

(26) Rolling mill (made by Schwabenthan)

(27) Roller material: chromed surfaces

(28) Roller diameter: 150 mm

(29) Speed ratio: 17/21 1/min

(30) Roller temperature: 140 C.

(31) Rolling time: 5 min

(32) Execution:

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

(34) Press

(35) 30-ton laboratory press (Werner & Pfleiderer URH 30)

(36) Press area: 350350 mm

(37) Pressing plates: chromed surfaces

(38) Pressing frame: 2202201.0 mm

(39) Execution:

(40) For making the press plates, the previously 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.

(41) 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: 220 bar Cooling time: 8 min

(42) Transmittance and Haze (Large-Angle Scattering)

(43) In order to evaluate a film's transparency two values were considered:

(44) 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

(45) large-angle scattering (haze), which is a measure for opaqueness.

(46) Measurement:

(47) The measurement of the transmittance and the 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.

(48) The sample to be measured is illuminated perpendicularly and the transmitted light is photoelectrically measured in an integrating sphere. 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. This guarantees that the measurement conditions are the same during calibration as well as during measurement.

(49) TABLE-US-00003 TABLE 1 Overview: Test and Comparative Examples and Press Plates Made Therefrom PBA Thickness of Patent content Microtrac MV Shore Shore Press Plates Transmittance, Examples (wt %) (nm) Hardness A Hardness D (mm) % Haze Remarks Example 1 46.9 61 85 26 1.50 84 13.2 Graft base Example 2 33 58 97 46 1.68 80.7 6.92 and graft Example 3 19.2 56 97 59 1.74 74.8 9.06 shell cross- Example 4 41.1 92 90 35 1.73 83.0 11.7 linked and Example 5 50 131 87 31 1.56 78.4 13.0 PSV < 150 nm Comparative 49.6 176 87 32 1.57 73.0 21.9 Comparative Example 1 Examples Comparative 52 224 84 24 1.83 52.6 43.5 PSV Example 2 150 nm Comparative 56.6 336 88 31 1.59 52.4 52.7 Example 3 Comparative 57.2 327 85 27 1.64 48.3 63.7 Example 4 Blend Example 1 29.6 94 59 1.67 75.4 16.4 0.75 Example 2 + 0.25 Example 3 Blend Example 2 40 92 38 1.49 69.9 93.2 0.75 Example 1 + 0.25 Example 3 Vinnolit VK 710 ca. 50 85 28 1.48 78.0 65.8 Competitive Vinnolit K 707 E ca. 50 79 25 1.81 53.9 68.8 product samples

(50) The graft copolymers Vinnolit VK 710 and Vinnolit K707 E, having an acrylate content of about 50 wt %, represent the prior art. Especially due to the high haze value (which characterizes the large-angle scattering), the press plates appear translucent to opaque. The examples according to the invention have a considerably better transparency, which features a substantially lower scattering. The test and comparative samples prove the effect of particle sizes of the graft copolymers on the transparency of the PVC articles made therefrom.

(51) The Examples 8 to 12 according to the invention have a higher transparency than the Comparative Examples 1 to 3, which are cross-linked in the same manner and which have particle sizes of above 170 nm. When the graft base and the graft shell are cross-linked, the transparency of a press plate made therefrom will be improved substantially by reducing the particle size to below 200 nm.

(52) Blends consisting of the graft copolymers according to the invention that differ from each other in their PBA content (see Blend Example 1) have a higher transparency than Comparative Examples 1 to 4.

(53) In contrast to this, blends of a transparent graft copolymer with S-PVC are opaque. For example, a transparent press plate made from the graft copolymer of Example 1, which is per se transparent, becomes opaque if S-PVC is admixed to the graft copolymer to a proportion of 25 wt %.

(54) While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.

(55) Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the above described features.