Polymer composition

Abstract

The present invention relates to polymer composition comprising 100 parts by weight of halogen containing polymer, 10 to 70 parts by weight of plasticizer, 2 to 10 parts by weight of stabilizer, 1-15 parts by weight of a layered double hydroxide (LDH) having the formula (I) wherein M and M′ are different and each is at least one metal cation, z=1 or 2; y=3 or 4, 0<x<0.9, b=0 to 10, c=0 to 10, X is an anion, n is the charge on the anion, and a=z(1−x)+xy−2; solvent is organic solvent with a hydrogen bond donor or acceptor function; as well as an article comprising the polymer composition.
[M.sup.z+.sub.1−xM′.sup.y+.sub.x(OH).sub.2].sup.a+(X.sup.n−).sub.a/n.bH.sub.2O.c(solvent)  (I)

Claims

1. A polymer composition comprising 100 parts by weight of halogen containing polymer, 10 to 70 parts by weight of plasticizer, 2 to 10 parts by weight of stabilizer, 1-15 parts by weight of a layered double hydroxide (LDH) having the formula
[(Mg.sub.pZn.sub.qSn.sup.(II).sub.r).sub.1−x(Al.sub.sSn.sup.(IV).sub.t).sub.x(OH).sub.2].sup.a+(X.sup.n−).sub.a/n.bH.sub.2O.c(solvent) wherein p+q+r=1, p=0 to 0.33, q=0.67 to 1, r=0-1, s+t=1, s=0-1, t=0-1, x=0.10-0.40, b=0 to 10, c=0 to 1, X is an anion, n is the charge on the anion, and a=[(2p+2q+2r)(1−x)]+[(3s+4t)x]−2; solvent is organic solvent with a hydrogen bond donor or acceptor function.

2. The polymer composition according to claim 1, wherein the LDH has the formula
[(Mg.sub.pZn.sub.q).sub.1−xAl.sub.x(OH).sub.2].sup.a+(X.sup.n−).sub.a/n.bH.sub.2O.c(solvent) wherein p+q=1, p=0 to 0.33, q=0.67 to 1, x=0.10-0.40, b=0 to 10, c=0 to 1, X is an inorganic oxyanion, n is the charge on the anion, and a=[(2p+2q)(1−x)]+3x−2; solvent is ethanol.

3. The polymer composition according to claim 1, wherein X is an anion selected from at least one of halide, inorganic oxyanion, anionic surfactants, anionic chromophores, and anionic UV absorbers.

4. The polymer composition of claim 3, wherein the inorganic oxyanion is selected from the group consisting of carbonate, bicarbonate, hydrogenphosphate, dihydrogenphosphate, nitrite, borate, nitrate, sulphate, phosphate, and mixtures thereof.

5. The polymer composition according to claim 1, wherein the organic solvent with a hydrogen bond donor or acceptor function is selected from the group consisting of ethyl acetate, acetone, acetonitrile, dimethylformamide, dimethylsulfoxide, dioxane, ethanol, m-cresol, o-cresol, p-cresol, methanol, n-propanol, isopropanol, n-butanol, sec-butanol, n-pentanol, n-hexanol, cyclohexanol, diethyl ether, diisopropyl ether, di-n-butyl ether, methyl tert-butyl ether (MTBE), tert-amyl methyl ether, cyclopentyl methyl ether, anisole, butyl carbitol acetate, cyclohexanone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), methyl isoamyl ketone, methyl n-amyl ketone, isophorone, isobutyraldehyde, furfural, methyl formate, methyl acetate, isopropyl acetate, n-propyl acetate, isobutyl acetate, n-butyl acetate, n-amyl acetate, n-hexyl acetate, methyl amyl acetate, methoxypropyl acetate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, n-butyl propionate, n-pentyl propionate, triethylamine, 2-nitropropane, aniline, N,N-dimethylaniline, nitromethane, tetrahydrofurane, and mixtures of two or more thereof.

6. The polymer composition according to claim 1, wherein the LDH as defined in formula (1) has b+c in the range of 0-1.

7. The polymer composition according to claim 1, wherein the plasticizer comprises at least one plasticizer selected from the group of phthalate, mellitate, adipate, azelate, maleate, sebacate, epoxidized oil, chlorinated paraffin oil, polymeric plasticizer or a mixture thereof.

8. The polymer composition according to claim 1, wherein the stabilizer comprises at least one stabilizer selected from the group of lead-based stabilizer, mixed metal-based stabilizer or a mixture thereof.

9. The polymer composition according to claim 1, wherein the LDH further comprising a surface-treating agent, said surface-treating agent is an organic moiety capable of covalent or ionic association with at least one surface of the layered double hydroxide, and which modifies the surface properties of the layered double hydroxide.

10. The polymer composition according to claim 9, wherein the surface-treating agent is an organic moiety comprising at least 4 carbon atoms and at least one functional group that is capable of covalent or ionic association with at least one surface of the layered double hydroxide.

11. The polymer composition of claim 10, wherein the surface-treating agent is selected from the group consisting of an organosilane compound, a fatty acid or a salt thereof, a fatty acid/phosphoric acid ester, a polyhydric alcohol ester, and mixtures thereof.

12. The polymer composition according to claim 1, wherein the polymer composition is compounded by an extrusion process at a high temperature and a screw speed in the range of 30-100 rpm.

13. The polymer composition of claim 12, wherein the temperature of the extrusion process is from 150° C. to 190° C.

14. The polymer composition of claim 13, wherein the temperature of the extrusion process is from 160° C. to 180° C.

15. The polymer composition of claim 12, wherein the screw speed of the extrusion process is from 40 rpm to 60 rpm.

16. An article comprising the polymer composition according to claim 1, wherein the article is an electric or electronic circuit component, a structural element for transportation and building or an indoor everyday object.

17. An electrical wire or cable coated with the polymer composition according to claim 1.

Description

(1) Further features and advantages of the present invention will now be illustrated in the following detailed description by means of examples and is further illustrated by the drawings.

(2) In the drawing,

(3) FIG. 1 illustrates the tensile strength before aging of polymer compositions prepared according to Example 2;

(4) FIG. 2 illustrates the elongation at break before aging of polymer compositions prepared according to Example 2;

(5) FIG. 3 illustrates the retention of tensile strength after heat aging of polymer compositions prepared according to Example 2;

(6) FIG. 4 illustrates the elongation at break after heat aging for polymer compositions prepared according to Example 2;

(7) FIG. 5 illustrates the retention of tensile strength after oil aging of polymer compositions prepared according to Example 2;

(8) FIG. 6 illustrates the retention of elongation at break after oil aging for polymer compositions prepared according to Example 2; and

(9) FIG. 7 illustrates the smoke density of PVC compositions prepared according to Example 2.

(10) The abbreviations used in the below examples and tables have the following meanings LDH-CO.sub.3: LDH having the formula (I) whereas the anion (X.sup.n−) is carbonate LDH-B.sub.4O.sub.7: LDH having the formula (I) whereas the anion (X.sup.n−) is borate Mg.sub.3Al—CO.sub.3: [(Mg.sub.0.75Al.sub.0.25(OH).sub.2][CO.sub.3].sub.0.5.nH.sub.2O; common Hydrotalcite without solvent treatment Mg.sub.2.5Zn.sub.0.5Al—CO.sub.3: [(Mg.sub.0.83Zn.sub.0.17).sub.0.75Al.sub.0.25(OH).sub.2][CO.sub.3].sub.0.125.bH.sub.2O.c(solvent) Mg.sub.2ZnAl—CO.sub.3: [(Mg.sub.0.66Zn.sub.0.33).sub.0.75Al.sub.0.25(OH).sub.2][CO.sub.3].sub.0.125.bH.sub.2O.c(solvent) Mg.sub.1.5Zn.sub.1.5Al—CO.sub.3: [(Mg.sub.0.5Zn.sub.0.5).sub.0.75Al.sub.0.25(OH).sub.2][CO.sub.3].sub.0.125.bH.sub.2O.c(solvent) MgZn.sub.2Al—CO.sub.3: [(Mg.sub.0.33Zn.sub.0.66).sub.0.75Al.sub.0.25(OH).sub.2][CO.sub.3].sub.0.125.bH.sub.2O.c(solvent) Mg.sub.3Al.sub.0.7Sn.sub.0.3—CO.sub.3: [(Mg).sub.0.75(Al.sub.0.7Sn.sub.0.3).sub.0.25(OH).sub.2][CO.sub.3].sub.0.16.bH.sub.2O.c(solvent) Zn.sub.2Al—B.sub.4O.sub.7: [(Zn).sub.0.67(Al).sub.0.33(OH).sub.2][B.sub.4O.sub.7].sub.0.17.bH.sub.2O.c(solvent) ATH: Aluminium trihydrate

(11) Synthesis of LDHs of the Invention

Synthesis of LDH-CO.SUB.3 .(LDH-C 1 to 5)

(12) LDH-C 1 to 5 were synthesized by adding a metal precursor solution drop-wise into 1.4 L of a 1.5 M Na.sub.2CO.sub.3 solution with a drop rate of 36 ml/minute. The pH of the precipitation solution was controlled at 10 using a NaOH solution (12M). After 4 hours of aging in original solution, the resulting slurry was filtered by vacuum filtration technique and washed with deionized water until a pH is 7 was obtained. The filtered slurry was washed with ethanol for 1 hour, and then was dried by vacuum oven at 65° C. overnight. The metal precursor solution were prepared by dissolving metals as stated in Table 1 in 1.4 L water.

(13) TABLE-US-00001 TABLE 1 LDH-C 1 LDH-C 2 LDH-C3 LDH-C 4 LDH-C 5 Mg.sub.2.5Zn.sub.0.5Al—CO.sub.3 Mg.sub.2ZnAl—CO.sub.3 Mg.sub.1.5Zn.sub.1.5Al—CO.sub.3 MgZn.sub.2Al—CO.sub.3 Mg.sub.3Al.sub.0.7Sn.sub.0.3—CO.sub.3 Metal precursor solution Zn(NO.sub.3).sub.2•6H.sub.2O (kg) 0.094 0.189 0.283 0.379 — Mg(NO.sub.3).sub.2•6H.sub.2O (kg) 0.407 0.326 0.244 0.163 0.490 Al(NO.sub.3).sub.3•9H.sub.2O (kg) 0.239 0.239 0.239 0.239 0.168 SnCl.sub.4•5H.sub.2O (kg) — — — — 0.050

Synthesis of Zn.SUB.2.Al—B.SUB.4.O.SUB.7 .(LDH-B 1)

(14) LDH-B 1 was synthesized by adding a metal precursor solution drop-wise into a 1.4 L of 1.5 M Na.sub.2 B.sub.4O.sub.7 solution with a drop rate of 36 ml/minute. The pH of the precipitation solution was controlled at 9 using a NaOH solution (12M). After 4 hours of aging in original solution, the resulting slurry was filtered by vacuum filtration technique and washed with deionized water until a pH is 7 was obtained. The filtered slurry was washed with ethanol for 1 hour, and then was dried by vacuum oven at 65° C. overnight. The metal precursor solution was prepared by mixing 379.3 g of Zn(NO.sub.3).sub.2.6H.sub.2O, 239.1 g of Al(NO.sub.3).sub.3.9H.sub.2O in 1.4 L of water.

(15) Characterisation Methods a) Color stability of prepared LDHs filled PVC compositions was evaluated after extrusion by eyes and by spectrophotometer CM-3600A (Konica Minolta). LDH filled PVC compositions were compression molded into 11×11 cm.sup.2 square plaques of uniform thickness (approximately 3 mm.) for measurement whiteness index (WI), yellowness index (YI), L*, a*, b*, C, h and delta E by spectrophotometer. b) Determination of physical properties of the polymer composites 1. Tensile strength and % Elongation is measured by IEC60502. The specimen in dumbbell shape is extended at the cross head speed of 200 mm/min by using the test machine U.T.M. The breaking point is measured. Tensile strength and elongation are calculated by the following formula.

(16) $\mathrm{Tensile}\mathrm{strength}\left(\frac{\mathrm{kfg}}{{\mathrm{mm}}^2}\right)=\frac{\mathrm{Load}\mathrm{value}\left(\mathrm{kgf}\right)}{\mathrm{Width}\left(\mathrm{mm}\right)\times \mathrm{Thickness}\left(\mathrm{mm}\right)}$$\%\mathrm{Elongation}=\frac{\mathrm{Extension}}{\mathrm{Primary}\mathrm{length}}\times 100$ 2. Tensile strength and % Elongation after heat aging is measured by IEC60502. The specimen in dumbbell shape is heated at 100° C. for 168 hours before extended at the cross head speed of 200 mm/min by using the test machine U.T.M. The breaking point is measured. Retention of tensile strength and elongation at break are calculated by the following formula.

(17) $\%\mathrm{Retention}\mathrm{of}\mathrm{tensile}\mathrm{strenght}=\frac{\mathrm{Tensile}\mathrm{strength}\mathrm{after}\mathrm{aging}}{\mathrm{Tensile}\mathrm{strength}\mathrm{before}\mathrm{aging}}\times 100$$\%\mathrm{Retention}\mathrm{of}\mathrm{elongation}=\frac{\mathrm{Elongation}\mathrm{after}\mathrm{aging}}{\mathrm{Elongation}\mathrm{before}\mathrm{aging}}\times 100$ 3. Tensile strength and % Elongation after oil aging is measured by 902. The specimen in dumbbell shape is heated in oil at 70° C. for 4 hours before extended at the cross head speed of 200 mm/min by using the test machine U.T.M. The breaking point is measured. Retention of tensile strew and elongation at break are calculated by the formula as shown in 2. c) Flame-retardant performance of prepared LDHs filled PVC compositions was evaluated using a cone calorimetry (Toyoseiki). Approximately 30 g of PVC composition was compression molded into 10 cm×10 cm square plaques of uniform thickness (approximately 3 mm.) before the tests were performed. A cone-shape heater with incident flux of 50 kW/m2 was used, and the spark was continuous until the sample ignited. The results from cone calorimeter are generally considered to be reproducible to +/−10%. This provides the peak heat release rate (PHRR) and ignition time. The fire performance index (FPI) which is the ratio between the ignition time and the peak rate of heat release. d) Congo red test of prepared LDH filled PVC compositions was evaluated by putting 1-g sample into the test tube which will be placed in the heating block at 180° C. Litmus paper will be placed at the top of the tube. Once the paper turns red, the time is recorded indicating the emission of acid gas from the composition. e) Smoke density test is measured by ASTM E 662. Sample was prepared into 3×3 inches with 3 mm thickness. The test was performed with non-flaming mode where the sample was radiated with heat source (2.5 W/cm.sup.2). As smoke generated, optical transmission was measured. The specific optical density (Ds) is then calculated and plotted against time.

EXAMPLE 1

(18) PVC compositions, Comparative example 1-7 (Com.Ex. 1-7) and Embodiment 1-14 (Em. 1-14), were prepared by dry blending 100 parts by weight of PVC resin, 4 parts by weight of tribasic lead sulphate, 20 parts by weight of 1,2-benzenedicarboxylic acid diisodecyl ester, 10 parts by weight of tris(2-ethylhexyl) trimellitate, 5 parts by weight of chlorinated paraffin oil, 5 parts by weight of epoxidized soybean oil, 50 parts by weight of CaCO.sub.3, 0.2 parts by weight of epoxidized PE wax, 3 parts by weight of antimony trioxide, 2 parts by weight of silicon dioxide, 1 parts by weight of acrylic processing aid, and the prepared LDH-CO.sub.3, the prepared LDH-B.sub.4O.sub.7, common hydrotalcite (Mg.sub.3Al—CO.sub.3) or ATH in an count as dictated in table 2 and 3M high speed mixer at 500-2,000 rpm and heat up to 120° C. to produce a uniform powder mixture. Then, melt mixing the dry blend by single screw extruder at a temperature of 160-180° C. with a screw speed of 60 rpm to form LDHs filled PVC pellet. The prepared composition have been tested and analyzed, the results are given in Table 2 and 3 below.

(19) TABLE-US-00002 TABLE 2 Color stability of polymer composition prepared with LDHs having various metal types Com. Com. Ex 1 Ex 2 Em. 1 Em. 2 Em. 3 Em. 4 Em. 5 Em. 6 LDHs (parts by weight) LDH-C1 — — 30 LDH-C2 — — 30 LDH-C3 — — 30 LDH-C4 — — 30 LDH-C5 — — 30 LDH-B1 — — 30 Mg.sub.3Al—CO.sub.3 — 30 Color stability Color by eye White Black Dark Brown Yellow Quite white Quite white Quite white brown WI 40.73 −39.67 −129.1 −103.1 −27.28 43.84 −25.62 25.77 YI 4.85 40.75 75.66 59.94 33.69 6.65 31.83 12.92 L* 78.56 67.38 52.78 49.24 70.76 80.8 70.77 78.34 a* −0.85 9.37 14.34 9.75 5.97 0.72 4.82 1.42 b* 2.51 13.15 22.08 16.47 12.15 2.76 11.82 5.28 C 2.65 16.14 26.33 19.14 13.54 2.85 12.76 5.47 h 108.64 54.51 57 59.36 63.85 75.27 67.79 74.91 dE — 18.5 35.8 34.2 14.2 2.75 13.4 3.58

(20) As table 2, for the inventive polymer compositions (Em.1-6), it was found in a preferred embodiment that an increase of Zn-content in the LDH and an incorporation of Sn(IV) in the LDH results in a less yellowing (browning) of the polymer/LDH composition after processing at high temperatures and pressures while common hydrotalcite, Mg.sub.3Al—CO.sub.3(Com.Ex 2) provides a dark brown/black material after processing compared to the PVC composition without LDHs (Com.Ex 1).

(21) TABLE-US-00003 TABLE 3 Mechanical and flame retardancy properties of PVC composition Com. Com. Com. Com. Com. Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Em. 7 Em. 8 Composition Type ATH Mg.sub.3Al—CO.sub.3 LDH-C 4 parts by weight 30 3 5 7 10 3 5 Property Method Spec Specific gravity ASTM D 792 — 1.568 1.516 1.523 1.528 1.547 1.527 1.531 Tensile strength, MPa IEC 60502 Min. 12.5 23.4 22.6 22.4 20.9 16.7 24.6 24.1 Elongation at break, % IEC 60502 Min. 150 277 288 279 245 114 261 268 After heat aging at 100° C., 168 h Method Spec Tensile strength, MPa IEC 60502 Min. 12.5 21.7 21.8 21.3 19.7 20.1 22.6 22.3 Elongation at break, % IEC 60502 Min. 150 254 250 245 200 5 274 269 Retention of tensile strength, % IEC 60502 75-125 93 96.4 95.2 94.1 120.5 92 93 Retention of elongation at break, % IEC 60502 75-125 92 86.8 87.9 81.5 4.4 105 100 Flammability Behavior at 50 kW/m.sup.2 Method Spec Ignition time (sec) — — 46.2 — — — — 20.3 160.9 Peak heat release rate (kW/m.sup.2) — — 160.23 — — — — 127.67 118.39 Fire performance index, s .Math. m.sup.2/kW — — 0.47 0.23 0.17 0.16 0.21 0.16 1.36 Congo red (min) — min 120 503 — — — — 450 373 Em. Em. Em. Em. Em. Em. 9 10 11 12 13 14 Composition Type LDH-C 4 LDH-B 1 parts by weight 7 10 3 5 7 10 Property Method Spec Specific gravity ASTM D 792 — 1.536 1.548 1.518 1.518 1.513 1.516 Tensile strength, MPa IEC 60502 Min. 12.5 25.3 24.4 23.5 23.3 23.8 22.7 Elongation at break, % IEC 60502 Min. 150 305 302 271 261 266 249 After heat aging at 100° C., 168 h Method Spec Tensile strength, MPa IEC 60502 Min. 12.5 22.6 22.9 22.8 22.3 22.7 21.6 Elongation at break, % IEC 60502 Min. 150 265 251 225 253 248 233 Retention of tensile strength, % IEC 60502 75-125 89 94 91.7 97.5 93.8 100.0 Retention of elongation at break, % IEC 60502 75-125 87 83 83.1 96.9 93.0 93.6 Flammability Behavior at 50 kW/m.sup.2 Method Spec Ignition time (sec) — — 351.6 410.9 78.1 136.2 286.3 61.5 Peak heat release rate (kW/m.sup.2) — — 104.31 95.50 138.49 130.30 113.54 22.24 Fire performance index, s .Math. m.sup.2/kW — — 3.37 3.58 0.56 1.05 2.52 6.71 Congo red (min) — min 120 355 380 375 350 340 305

(22) As table 3, the use of the LDHs (Em. 7 to 14) prolongs ignition time and decreases peak heat release rate (PHRR). The fire performance index (FPI) is a correlation to time to flashover of a material under burning situation. Consequently, FPI can be used to predict time available for escape. Therefore, the higher the index, the better the material is in term of flame retardancy. For both LDH systems LDH-CO.sub.3 (Em. 7 to 10), and LDH-B.sub.4O.sub.7 (Em.11 to 14), only 5-10 parts by weight additions are needed in order to get over 100% improvement in FPI compared with 30 parts by weight addition of ATH for existing PVC formulations (Com. Ex 3). In addition, the common hydrotalcite (Corn. Ex 4 to 7) shows worse FPI, tensile strength and elongation at break compared to the LDHs at the same amount of addition.

(23) It was also found that the use of the LDH allows a reduction of the amount of the LDH compared to the use of, for example, ATH in the composite to nevertheless provide improved flame retardant properties. For example, better flame retardant properties may be obtained for the LDH of the present invention using 5 or 7 or 10 parts by weight compared to the use of 30 parts by weight of ATH.

(24) In addition, it was also found that the use of the LDH lessen the Congo red value. The Congo red test is used for evaluating the dehydrochlorination rate which is the rate of HCl release from the heating of PVC composition pellet. The released HCl accelerates the PVC degradation which eventually generates crosslinked material. This crosslinked material can also act as bather to retard flame spread. In PVC/LDH, the better flame retarding performance can then be related to the lower the Congo Red value as faster barrier formation to better protect flame spread. However, the lower the Congo Red value does not affect to the processing because the Congo Red value is still longer than the resident time of material during processing.

EXAMPLE 2

(25) PVC compositions, PVC/ATH and PVC/LDH, were prepared by dry blending 100 parts by weight of PVC resin, 4 parts by weight of tribasic lead sulphate, 20 parts by weight of 1,2-benzenedicarboxylic acid diisodecyl ester, 10 parts by weight of tris(2-ethylhexyl) trimellitate, 5 parts by weight of chlorinated paraffin oil, 5 parts by weight of epoxidized soybean oil, 50 parts by weight of CaCO3, 0.2 parts by weight of epoxidized PE wax, 3 parts by weight of antimony trioxide, 2 parts by weight of silicon dioxide, 1 parts by weight of acrylic processing aid, 0.8 parts by weight of carbon black, and 30 parts by weight of ATH or 7 parts by weight of the prepared MgZn.sub.2Al—CO.sub.3, in high speed mixer at 500-2,000 rpm and heat up to 120° C. to produce a uniform powder mixture. Then, melt mixing the dry blend by single screw extruder at a temperature of 160-180° C. with a screw speed of 60 rpm to form LDHs filled PVC pellet. The prepared composition have been tested and analyzed, the results are given in FIGS. 1 to 7.

(26) As FIGS. 1 to 7, the addition of the LDHs reduces smoke generation as compared with the ATH-filled PVC composition. In addition, the PVC/LDH shows better mechanical performance than that of PVC/A system.

(27) The features disclosed in the foregoing description and in the claims may, both separately and in any combination be material for realizing the invention in diverse forms thereof.