Composition based on a vinyl halide polymer

Abstract

Composition comprising at least one vinyl halide polymer and 0.1 to 5% by weight, relative to the weight of the vinyl halide polymer, of at least one polymer of at least one acrylic ester obtained by polymerization in solution in a liquid medium comprising at least one chain transfer agent chosen among the C.sub.3-C.sub.20 hydrocarbons containing at least one secondary alcohol function. Process for its manufacture, article obtained starting from this composition and use of this composition for manufacturing sheets and films via calendaring or for manufacturing profiles by extrusion. Process for the manufacture of a polymer of at least one acrylic ester which can be used in the composition.

Claims

1. A method for forming a polymer composition, the method comprising: forming an acrylic ester polymer by polymerizing at least one acrylic ester in a solution having a liquid medium comprising at least one chain transfer agent selected from the group consisting of C.sub.3-C.sub.20 hydrocarbons having at least one secondary alcohol function, wherein a ratio of the weight of the at least one acrylic ester (kg) to the volume of the at least one chain transfer agent (l) is greater than or equal to 1.5/1 and less than or equal to 5/1; and forming a blend comprising the acrylic ester polymer and a vinyl halide polymer by polymerizing at least one vinyl halide monomer in an aqueous suspension comprising at least a portion of the acrylic ester polymer and at least a portion of the at least one chain transfer agent.

2. The method of claim 1, wherein the vinyl halide monomer is a vinyl chloride monomer.

3. The method of claim 1, wherein the at least one vinyl halide monomer is polymerized with at least one comonomer.

4. The method of claim 1, wherein the acrylic ester polymer is a polymer of acrylic acid esters derived from C.sub.1-C.sub.8 aliphatic monoalcohols.

5. The method of claim 1, wherein the liquid medium consists essentially of the at least one chain transfer agent.

6. The method of claim 1, wherein the chain transfer agent is selected from the group consisting of C.sub.3-C.sub.8 hydrocarbons containing one secondary alcohol function.

7. The method of claim 1, wherein the chain transfer agent is selected from the C.sub.3-C.sub.20 hydrocarbons containing only one secondary alcohol function.

8. The method of claim 1, wherein the chain transfer agent is selected from aliphatic C.sub.3-C.sub.8 hydrocarbons containing only one secondary alcohol function.

9. The method of claim 1, wherein the chain transfer agent is selected from aliphatic C.sub.3-C.sub.6 hydrocarbons containing only one secondary alcohol function.

10. The method of claim 1, wherein the at least one chain transfer agent is selected from the group consisting of isopropanol, sec-butyl alcohol, 2-pentanol, 2-hexanol, 2-heptanol and 2-octanol.

11. The method of claim 1, further comprising: incorporating a natural organic filler into the blend.

12. The method of claim 11, wherein the natural organic filler is low-density or high-density wood, in the form of flour or fibres.

13. Article or part of article comprising a polymer composition formed according to claim 1.

14. A method for manufacturing sheets or films, the method comprising: forming a polymer composition according to claim 1; and calendaring the polymer composition to form a sheet or a film.

15. A method for manufacturing a profile, the method comprising: forming a polymer composition according to the method of claim 1; and extruding the polymer composition to form a profile.

Description

EXAMPLE 1

A. Preparation of the Acrylic Ester Polymer (Polymer A)

(1) 1164 g of n-butyl acrylate and 727 g of methyl acrylate were mixed under normal conditions (20° C.; 1 bar), in order to obtain a solution known as solution 1.

(2) Moreover, 5.76 g of t-butyl per-2-ethylhexanoate were introduced into 120 g (153 ml) of isopropanol under normal conditions, in order to obtain a solution known as solution 2.

(3) Introduced into a 3.5 l reactor equipped with a stirrer were 60 g of solution 1, 4.76 g of solution 2 and 350 g (446 ml) of isopropanol (acting as both the polymerization liquid medium and the chain transfer agent). The reactor was sealed, sparged 3 times with nitrogen under a pressure of 10 bar (absolute pressure, that is to say the gauge pressure measured with a manometer (“gauge”) plus the atmospheric pressure) and it was degassed at atmospheric pressure.

(4) The reactor was then put under a partial vacuum equivalent to 1/13.sup.th of a bar. The stirrer was rotated at 500 rpm and the contents of the reactor were heated at 105° C.

(5) After 30 minutes, the balance of solution 1 (1831 g) was gradually introduced over a period of 150 minutes, then the balance of solution 2 (121 g) was gradually introduced over a period of 30 minutes.

(6) The reactor was cooled to room temperature after a total period of 270 minutes. A solution of polymer A in isopropanol was drawn off.

B. Preparation of the Composition Based on a Vinyl Halide Polymer

(7) Introduced into a 300 l stainless steel reactor equipped with a stirrer were:

(8) 103 l of demineralized water;

(9) 95 g of hydroxypropyl methyl cellulose sold under the name Metocel 181;

(10) 90 g of sodium tripolyphosphate;

(11) 35 g of t-butyl perneodecanoate;

(12) 50 g of dilauryl peroxide; and

(13) 0.91 kg of polymer A in the form of the solution of polymer A in isopropanol obtained in part A of Example 1.

(14) The reactor was then sealed, sparged 3 times with nitrogen under a pressure of 12 bar and degassed at atmospheric pressure. It was then put under a partial vacuum equivalent to 400 mbar. The stirrer was rotated at 220 rpm, 70 kg of vinyl chloride were introduced into the reactor and its contents were heated at 64° C. This temperature was kept constant over the duration of the polymerization.

(15) At the end of the polymerization, when the pressure had decreased by one bar so when the conversion rate is 79%, the reaction was stopped by injecting 200 ppm of the product IRGANOX® 1141. The stirrer was slowed down to 100 rpm and the unpolymerized vinyl chloride was degassed for 90 minutes at 80° C.

(16) After cooling to 30° C., the composition based on a vinyl halide polymer that was obtained was filtered, washed with demineralized water and dried at 50° C. for 24 hours.

EXAMPLE 2R

(17) This example is given by way of comparison.

A. Preparation of the Modifying Polymer (Polymer B)

(18) 1152 g of n-butyl acrylate, 720 g of methyl acrylate and 48 g of t-dodecyl mercaptide (tDDM) (conventional chain transfer agent) were mixed under normal conditions, in order to obtain a solution known as solution 3.

(19) Moreover, 5.76 g of t-butyl per-2-ethylhexanoate were introduced into 120 g (152 ml) of methanol under normal conditions, in order to obtain a solution known as solution 4.

(20) The preparation of polymer B was continued in a manner similar to that of polymer A described in Example 1, except that 210 g (266 ml) of methanol were introduced into the reactor and that it functioned with solutions 3 and 4 respectively as with solutions 1 and 2 in Example 1. A solution of polymer B in methanol was drawn off.

B. Preparation of the Composition Based on a Vinyl Halide Polymer

(21) This preparation was carried out as described in point B of Example 1, except that 0.91 kg of polymer B, in the form of the solution of polymer B in methanol obtained in part A of Example 2R was introduced into the reactor.

EXAMPLE 3R

(22) This example is given by way of comparison.

A. Preparation of the Modifying Polymer (Polymer C)

(23) This preparation was carried out as described in point A of Example 2R. A solution of polymer C in methanol was drawn off.

B. Preparation of the Composition Based on a Vinyl Halide Polymer

(24) Introduced into a 300 l stainless steel reactor equipped with a stirrer were:

(25) 103 l of demineralized water;

(26) 69 g of hydroxypropyl methyl cellulose sold under the name Metocel 181;

(27) 63 g of sodium tripolyphosphate;

(28) 24.5 g of t-butyl perneodecanoate;

(29) 31.5 g of dilauryl peroxide; and

(30) 0.525 kg of polymer C, in the form of the solution of polymer C in methanol obtained in part A of Example 3R.

(31) The reactor was then sealed, sparged 3 times with nitrogen under a pressure of 12 bar and degassed at atmospheric pressure. It was then put under a partial vacuum equivalent to 400 mbar. The stirrer was rotated at 220 rpm, 70 kg of vinyl chloride were introduced into the reactor and its contents were heated at 64° C. This temperature was kept constant over the duration of the polymerization.

(32) At the end of the polymerization, when the pressure had decreased by one bar so when the conversion rate is 79%, the reaction was stopped by injecting 200 ppm of the product Bisphenol A as a 50% methanolic solution. The stirrer was slowed down to 100 rpm and the unpolymerized vinyl chloride was degassed for 90 minutes at 80° C.

(33) After cooling to 30° C., the composition based on a vinyl halide polymer that was obtained was filtered, washed with demineralized water and dried at 50° C. for 24 hours.

EXAMPLE 4R

(34) This example is given by way of comparison.

A. Preparation of the Modifying Polymer (Polymer D)

(35) In a 2 l reactor sparged with nitrogen, 300 g of distilled water, 2.4 g of a 33.3% aqueous polystyrene dispersion with a particle size of 30 nm were introduced and heated to 90° C. under agitation. Then 25 g of a mixture of 200 g of butyl acrylate, 190 g of methyl acrylate and 10 g of t-dodecyl mercaptide (tDDM), 100 g of distilled water, 0.8 g of sodium pyrophosphate and 2 g of sodium dodecyldiphenylethersulfonate were introduced. The balance of the mixture was gradually introduced over a period of 3 hours. In parallel, a solution of 0.8 g of sodium peroxydisulfate in 100 g of water was introduced over a period of 3.5 hours. After an additional period of 30 min at 90° C., the reactor was cooled to room temperature. The obtained dispersion had a solid content of 43.2% and a pH of 5.3.

B. Preparation of the Composition Based on a Vinyl Halide Polymer

(36) Introduced into a 300 l stainless steel reactor equipped with a stirrer were:

(37) 103 l of demineralized water;

(38) 75 g of hydroxypropyl methyl cellulose sold under the name Metocel 181;

(39) 63 g of sodium tripolyphosphate;

(40) 24.5 g of t-butyl perneodecanoate;

(41) 31.5 g of dilauryl peroxide; and

(42) 0.525 kg of polymer D, in the form of the dispersion of polymer D in water obtained in part A of Example 4R.

(43) The reactor was then sealed, sparged 3 times with nitrogen under a pressure of 12 bar and degassed at atmospheric pressure. It was then put under a partial vacuum equivalent to 400 mbar. The stirrer was rotated at 220 rpm, 70 kg of vinyl chloride were introduced into the reactor and its contents were heated at 64° C. This temperature was kept constant over the duration of the polymerization.

(44) At the end of the polymerization, when the pressure had decreased by one bar so when the conversion rate is 79%, the reaction was stopped by injecting 200 ppm of the product Bisphenol A as a 50% methanolic solution. The stirrer was slowed down to 100 rpm and the unpolymerized vinyl chloride was degassed for 90 minutes at 80° C.

(45) After cooling to 30° C., the composition based on a vinyl halide polymer that was obtained was filtered, washed with demineralized water and dried at 50° C. for 24 hours.

(46) Listed in the table 1 below is the data specific to each example.

(47) The properties mentioned in this table 1 for the acrylic ester polymers and for the composition based on a vinyl halide polymer that were obtained were measured as indicated below.

(48) Acrylic Ester Polymer

(49) The “K-value” was measured on a 0.5 wt % solution of polymer in cyclohexanone with an Ubbelohde microviscometer according to the DIN 51562 standard.

(50) Composition Based on a Vinyl Halide Polymer

(51) The average particle size was measured with a Malvern Instruments device using laser diffraction according to the ISO 13320 standard.

(52) The bulk density was measured according to the DIN 53466 standard.

(53) The thermal stability was expressed by the time taken by a sample of the composition placed in a Heraeus Type UT 6200 open chamber heated at 180° C. to change from a light yellow colouration to a dark brown/black colouration.

(54) The transparency was expressed by the ratio (in %) of the incident light beam to the reflected light beam measured by a Zeiss PMQ 3 photometer.

(55) The colouration was expressed in CIELab units and measured with a Hunterlab XE spectrophotometer using D65 radiation and an observation angle of 2°.

(56) The yellowness index was measured according to the DIN 6167 standard.

(57) The whiteness index was calculated from the values Y, y and x of a sample of the composition delivered by a Minolta CR 200 Chroma Meter machine, calibrated according to the Minolta CR-200/-300 S. No. 12633171 standards and an observation angle of 2°. The whiteness index is the result of the equation: [4.100+0.847 Z], the value of Z being provided by the equation: [((Y/y)−x).Math.((Y/y)−Y)].

(58) The adhesion to the calendering rolls was measured in the following manner: using a spatula, 50 g of the composition were premixed with 0.5 g of a tin-based stabilizer (product IRGASTAB®17 MOK from Ciba) in an enamel container. A Berstorff laboratory mill was heated at 190° C. after cleaning the steel rolls with lead-stabilized PVC granules and a (Vim type) household cleaning product, removing the cleaning products and rubbing the rolls with a cloth. After spreading the stabilized composition in the nip separating the rolls, set at 0.5 mm, the mill was operated at 15 rpm; the film formed was detached, rolled up and reintroduced into the nip. This sequence of manipulations was continued until the appearance of a strong adhesion (bonding) of the film to the rolls (time noted in minutes). The test was interrupted if no adhesion was observed after 30 minutes.

(59) TABLE-US-00001 TABLE 1 Example 1 Example 2R Example 3R Example 4R n-butyl 61.6/38.4/- 60/37.5/2.5 60/37.5/2.5 50/47.5/2.5 acrylate/methyl acrylate/t-DDM weight proportions Ratio of the  3.16/1 weight (kg) of acrylates to the volume (1) of isopropanol “K-value” of  18.9  18.4  18.4  15.6 the acrylic ester polymer Viscosity of the 318 1020 1020 solution of the acrylic ester polymer in the liquid medium of polymerization (mPa .Math. s) (23° C.) (solution at 77.3% by weight of polymer) Modifier Polymer A Polymer B Polymer C Polymer D % by weight of  1.3   1.3   0.75   0.75 modifier relative to the weight of vinyl chloride % by weight of  1.65   1.65   0.95   0.95 modifier relative to the weight of polyvinyl chloride Properties of the composition, based on a vinyl halide polymer, obtained Average particle 125  121  127 132 size (μm) Bulk density (kg/l)  0.633   0.647   0.646  0.501 Thermal stability  80   80 (min) Transparency (%)  89   88 Colouration L: 79.9 L: 77.4 a: −0.2 a: 0.8 b: 7.8 b: 10.9 Yellowness index  16.4   24.1 Whiteness index  25.8   12.6 Adhesion to the >30   28 calendering rolls (min)

(60) These results show the advantages of the compositions according to the invention from the four-fold viewpoint of the viscosity (lower), the reduction of parasitic colourations, the reduced adhesion to the calendering rolls and the higher bulk density.

EXAMPLES 5R, 6R AND 7

(61) Examples 5R and 6R are given by way of comparison.

EXAMPLE 5R

(62) An extrudable composition was manufactured by introducing the following ingredients into a rapid mixer (up to a temperature of 90° C.): 100 parts by weight of a vinyl chloride homopolymer having a “K-value” (measured according to the ISO 1628-2 standard) of 57, sold by SolVin under the name S 257 RF; 2.5 parts by weight of a (“one pack”) Ca/Zn stabilizer; 1 part by weight of a processing aid sold by Rohm & Haas under the name Paraloïd K-125; 2.75 parts by weight of a lubricant comprising a dicarboxylic ester of a saturated fatty alcohol; and 10 parts by weight of natural calcium carbonate.

(63) To this premix, cooled to 40° C., in a rotary drum, were added 116 parts by weight of wood powder (Lignocel C250 S product sold by Rettenmeier), previously dried at around 100° C. for 24 hours.

(64) Finally the composition obtained was granulated at 100° C. in a Kahl machine equipped with a 3 mm die and driven with a rotation speed of 112 rpm.

(65) This composition (composition 5R) was then extruded in a KMD 25 counter-rotating twin-screw extruder (barrel temperature profile: zone 1: 160° C.; zone 2: 160° C.; zone 3: 160° C.; zone 4: 175° C.; screw temperature: 130° C.; die temperature: 180° C.) rotating at 30 rpm with a throughput of 7 kg/hour.

EXAMPLE 6R

(66) A composition (composition 6R) was manufactured and extruded as in Example 5R, except that the vinyl chloride homopolymer was replaced by a vinyl chloride homopolymer having a “K-value” of 60, sold by SolVin under the name S 260 RF.

EXAMPLE 7

(67) A composition (composition 7) was manufactured and extruded as in Example 5R, except that the vinyl chloride homopolymer was replaced by the vinyl chloride polymer having a “K-value” of 60 prepared as described in Example 1.

(68) The material conditions of the extrusion and the mechanical properties of the extruded compositions are listed in Table 2 below.

(69) TABLE-US-00002 TABLE 2 5R 6R 7 Extruded (com- (com- (in- composition parison) parison) vention) Extrusion conditions Motor torque % 29 27 28 Specific energy Wh/kg 69 64 66 Pressure in the bar 220 218 177 extruder head (end of screw) Mechanical properties of the extruded compositions Flexural MPa 5100 5580 5250 modulus (according to ASTM D 790) Tensile MPa 5440 6060 5300 strength (according to ASTM D 638) Heat deflection ° C. 77.1 80.1 78.5 temperature (HDT)

(70) These results show the advantages obtained during the extrusion of the compositions according to the invention: with a good aptitude for gelation, these compositions create a substantially lower pressure in the extruder head, at comparable motor torque and specific energy, without deterioration of the mechanical properties. It is therefore possible, by virtue of the compositions according to the invention, to obtain, at higher speed, extruded objects with mechanical properties comparable to those of the prior art.