FILLERS FOR FOAMED RIGID POLYMER PRODUCTS

Abstract

The present invention relates to a resin composition for preparing foamed rigid polymer products, comprising at least one polymer resin, a surface-treated calcium carbonate having a weight median particle diameter d.sub.50 of between 0.1 m and 1 m, measured according to the sedimentation method, in an amount of at least 10 parts per hundred parts of the at least one polymer resin (phr) and a blowing agent in an amount of less than 1 phr, to a foamed rigid polymer product prepared from the composition, to a method for preparing a foamed rigid polymer product as well as to the use of a calcium carbonate for reducing the density of a foamed rigid polymer product.

Claims

1. A resin composition for preparing foamed rigid polymer products, said composition comprising a) at least one polymer resin, b) a surface-treated calcium carbonate having a weight median particle diameter d.sub.50 of between 0.1 m and 1 m, measured according to the sedimentation method, in an amount of at least 10 parts per hundred parts of the at least one polymer resin (phr), and c) a blowing agent in an amount of less than 1 phr.

2. The composition according to claim 1, wherein the calcium carbonate has a weight median particle diameter d.sub.50 of between 0.4 m and 1 m, preferably from 0.5 m to 0.9 m, more preferably from 0.6 m to 0.8 m and most preferably of 0.7 m, measured according to the sedimentation method.

3. The composition according to claim 1 or 2, wherein the calcium carbonate has a top cut of below 8 m, preferably of below 6 m and more preferably of about 4 m.

4. The composition according to any one of the preceding claims, wherein the calcium carbonate has a specific surface area of from 1 m.sup.2/g to 25 m.sup.2/g, preferably 5 m.sup.2/g to 15 m.sup.2/g and more preferably 8 m.sup.2/g to 13 m.sup.2/g, measured using nitrogen and the BET method.

5. The composition according to any one of the preceding claims, wherein the calcium carbonate is ground calcium carbonate (GCC) and/or precipitated calcium carbonate (PCC), preferably ground calcium carbonate.

6. The composition according to any one of the preceding claims, wherein at least 1% of the aliphatic carboxylic acid accessible surface area of the calcium carbonate is covered by a coating comprising at least one aliphatic carboxylic acid having between 4 and 24 carbon atoms and/or reaction products thereof, preferably by a coating comprising stearic acid and/or reaction products thereof.

7. The composition according to any one of the preceding claims, wherein the calcium carbonate is present in an amount of at least 5.0 phr, preferably of at least 10 phr, more preferably of at least 15 phr and most preferably of 20 phr.

8. The composition according to any one of the preceding claims, wherein the blowing agent is present in an amount of between 0.3 phr and 0.8 phr and most preferably in an amount of between 0.5 phr and 0.7 phr and/or the blowing agent is azodicarbonamide.

9. The composition according to any one of the preceding claims, wherein the composition further comprises at least one component selected from the group comprising nucleating agents, stabilizers, impact modifiers, lubricant additives, processing aids and mixtures thereof.

10. The composition according to any one of the preceding claims, wherein the at least one polymer resin is selected from the group comprising halogenated polymer resins, styrenic resins, acrylic resins, polyolefines, polycarbonate resins, unsaturated polyester resins, polyurethane resins, polyamide resins and mixtures thereof, preferably the polymer resin is PVC.

11. The composition according to claim 10, wherein the PVC resin has a K-value of between 50 and 68.

12. A method for preparing a foamed rigid polymer product comprising the following steps: a) providing the resin composition according to any one of claims 1 to 11, and b) subjecting the resin composition of step a) to conditions under which said resin composition is converted into a foamed rigid polymer product.

13. The method according to claim 12, wherein the obtained foamed rigid polymer product has a density of below 1 g/cm.sup.3, preferably of below 0.80 g/cm.sup.3, more preferably of below 0.75 g/cm.sup.3 and most preferably of below 0.73 g/cm.sup.3, for example of about 0.71 g/cm.sup.3.

14. The method according to claim 12 or 13, wherein the obtained foamed rigid polymer product has a charpy impact strength at 23 C. of between 1.65 kJ/m.sup.2 and 2 kJ/m.sup.2, more preferably between 1.70 kJ/m.sup.2 and 1.95 kJ/m.sup.2 and most preferably between 1.75 kJ/m.sup.2 and 1.80 kJ/m.sup.2, measured according to ISO 179/leA on extruded samples.

15. Use of a surface treated calcium carbonate having a weight median particle diameter d.sub.50 of between 0.1 m and 1 m, measured according to the sedimentation method, for reducing the density of a foamed rigid polymer product.

16. The use according to claim 15, wherein the calcium carbonate has a weight median particle diameter d.sub.50 of between 0.4 m and 1 m, preferably from 0.5 m to 0.9 m, more preferably from 0.6 m to 0.8 m and most preferably of 0.7 m, measured according to the sedimentation method.

17. The use according to claim 15 or 16, wherein the calcium carbonate has a top cut of below 8 m, preferably of below 6 m and more preferably of 4 m.

18. The use according to any one of claims 15 to 17, wherein the calcium carbonate has a specific surface area of from 1 m.sup.2/g to 25 m.sup.2/g, preferably 5 m.sup.2/g to 15 m.sup.2/g and more preferably 8 m.sup.2/g to 13 m.sup.2/g, measured using nitrogen and the BET method.

19. The use according to any one of claims 15 to 18, wherein the calcium carbonate is ground calcium carbonate (GCC) and/or precipitated calcium carbonate (PCC), preferably ground calcium carbonate.

20. The use according to any one of claims 15 to 19, wherein at least 1% of the aliphatic carboxylic acid accessible surface area of the calcium carbonate is covered by a coating comprising at least one aliphatic carboxylic acid having between 4 and 24 carbon atoms and/or reaction products thereof, preferably by a coating comprising stearic acid and/or reaction products thereof.

21. The use according to any one of claims 15 to 20, wherein the calcium carbonate is present in an amount of at least 5 phr, preferably of at least 10 phr, more preferably of at least 15 phr and most preferably of 20 phr.

22. The use according to any one of claims 15 to 21, wherein the foamed rigid polymer product has a density of below 1 g/cm.sup.3, preferably of below 0.8 g/cm.sup.3, more preferably of below 0.75 g/cm.sup.3 and most preferably of below 0.73 g/cm.sup.3, for example of about 0.71 g/cm.sup.3.

23. The use according to any one of claims 15 to 22, wherein the foamed rigid polymer product has a charpy impact strength at 23 C. of between 1.65 kJ/m.sup.2 and 2 kJ/m.sup.2, more preferably between 1.70 kJ/m.sup.2 and 1.95 kJ/m.sup.2 and most preferably between 1.75 kJ/m.sup.2 and 1.80 kJ/m.sup.2, measured according to ISO 179/leA on extruded samples.

24. A foamed rigid polymer product prepared from the resin composition according to claims 1 to 11.

Description

DESCRIPTION OF THE FIGURES

[0149] FIG. 1: illustrates the effect of various calcium carbonate products on the density of free foam PVC for Comparative Examples E1 to E9 and Examples E10 to E17.

[0150] FIG. 2: illustrates the effect of various calcium carbonate products on the charpy impact strength of free foam PVC for Comparative Examples E1 to E9 and Examples E10 to E17.

EXAMPLES

A. Measuring Methods

[0151] If not otherwise indicated, the parameters mentioned in the present invention are measured according to the measuring methods described below.

A1. Density Density measurements are made with Mettler Toledo's Density Kit by using the buoyancy technique. For the determination, 5 samples are cut out of the obtained PVC foams each sample having dimensions of 1010 mm.sup.2 and are weight. Subsequently, the buoyancy (P) in distilled water is measured and the density is calculated with the formula (M/(MP))*density of water.

A2. Weight Median Particle Diameter d.SUB.50 .Value

[0152] Throughout the present invention, d.sub.50 is the weight median particle diameter by weight, i.e. representing the particle size so that 50 wt.-% of the particles are coarser or finer.

[0153] The weight median particle diameter was measured according to the sedimentation method. The sedimentation method is an analysis of sedimentation behaviour in a gravimetric field. The measurement is made with a Sedigraph 5100 of Micromeritics Instrument Corporation. The method and the instrument are known to the skilled person and are commonly used to determine grain size of fillers and pigments. The measurement is carried out in an aqueous solution of 0.1 wt.-% Na.sub.4P.sub.2O.sub.7. The samples were dispersed using a high speed stirrer and supersonic.

A3. Specific Surface Area (BET)

[0154] The specific surface area was measured using nitrogen and the BET method according to ISO 9277.

A4. Charpy Impact Strength

[0155] Charpy impact strength (23 C.2 C. and 50% relative humidity10% relative humidity) was measured according to ISO 179/leA on extruded samples which were cut out of the extrudate in machine direction.

A5. Moisture Content

[0156] Moisture content of the inorganic filler is determined by thermogravimetric analysis (TGA). TGA analytical methods provide information regarding losses of mass with great accuracy, and is common knowledge; it is, for example, described in Principles of Instrumental analysis, fifth edition, Skoog, Holler, Nieman, 1998 (first edition 1992) in Chapter 31 pages 798 to 800, and in many other commonly known reference works. In the present invention, thermogravimetric analysis (TGA) is performed using a Mettler Toledo TGA 851 based on a sample of 500+/50 mg and scanning temperatures from 25 C. to 350 C. at a rate of 20 C./minute under an air flow of 70 ml/min.

[0157] Alternatively, the moisture content of the inorganic filler is determined by the oven method.

B. Preparation and Testing of Samples

[0158] The components and the respective amounts of the resin compositions prepared in Comparative Examples E1 to E9 are outlined in the following Table 1:

TABLE-US-00001 TABLE 1 Example component (phr) E1 E2 E3 E4 E5 E6 E7 E8 E9 PVC K-value 60 100 100 100 100 100 100 100 100 100 CaZn-containing 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 stabilizer calcium stearate 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 lubricant additive 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 titanium dioxide 1 1 1 1 1 1 1 1 1 acrylic polymer 1 1 1 1 1 1 1 1 1 high mw acrylic polymer 1 1 1 1 1 1 1 1 1 low mw Impact modifier 4 4 4 4 4 4 4 4 4 Azodicarbon- 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 amide Omyacarb FT 5 10 15 20 XP-7100T 5 10 15 20

[0159] In particular, the following commercially available components were used for preparing the compositions:

polyvinyl chloride polymer having a K-value of 60 (commercially available under the trade name Evipol SH6030 PVC; INEOS Chlor Americas Inc., Wilmington, USA),
CaZn-containing stabilizer (commercially available under the trade name Stabilox CZ 2913 GN; Inter-Harz GmbH, Elmshom, Germany),
calcium stearate (commercially available under the trade name Realube AIS), lubricant additive (commercially available under the trade name Realube 3010), low molecular weight acrylic polymer (commercially available under the trade name
Kane Ace PA101 Processing aid; Kaneka Texas Corporation, Pasadena, USA), high molecular weight acrylic polymer (commercially available under the trade name
Kane Ace PA40 Processing aid; Kaneka Texas Corporation, Pasadena, USA), and acrylic impact modifier (commercially available under the trade name Paraloid KM 366; Dow Chemical Company, Midland, USA).
Titanium dioxide (commercially available under the trade name Dupont R960; Dupont, Wilmington, USA)
Azodicarbonamide (commercially available under the trade name Forte-cell***; Cellular Additives, Asheville, USA).

[0160] Comparative Examples E2 to E5 further comprise Omyacarb FT in varying dosage levels of 5 phr, 10 phr, 15 phr and 20 phr, which is a commercially available product of calcium carbonate particles. The calcium carbonate is a wet ground GCC, treated with approximately 1% by weight of stearic acid, which had the following properties: [0161] d.sub.50=approximately 1.4 m. [0162] BET surface area (before stearic acid treatment)=approximately 5.5 m.sup.2/g.

[0163] Comparative Examples E6 to E9 further comprise XP-7100T in varying dosage levels of 5 phr, 10 phr, 15 phr and 20 phr, which is a product of calcium carbonate particles. The calcium carbonate is a wet ground GCC, treated with approximately 0.5% by weight of stearic acid and with approximately 0.5% by weight of a dispersant having a molecular weight of 35,000 g/mol prepared from 92 wt.-% methoxy polyethylene glycol methacrylate of molecular weight 2,000 g/mole and 8 wt.-% acrylic acid and totally neutralised by soda, which had the following properties: [0164] d.sub.50=approximately 1.4 m. [0165] BET surface area (before stearic acid treatment)=approximately 5.5 m.sup.2/g.

[0166] The components and the respective amounts in phr of the resin compositions prepared in Examples E10 to E11 according to the present invention are outlined in the following Table 2:

TABLE-US-00002 TABLE 2 Example component (phr) E10 E11 E12 E13 E14 E15 E16 E17 PVC K-value 60 100 100 100 100 100 100 100 100 CaZn-containing 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 stabilizer calcium stearate 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 lubricant additive 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 titanium dioxide 1 1 1 1 1 1 1 1 acrylic polymer 1 1 1 1 1 1 1 1 high mw acrylic polymer 1 1 1 1 1 1 1 1 low mw Impact modifier 4 4 4 4 4 4 4 4 Azodicarbon- 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 amide Omyacarb UFT 5 10 15 20 Hydro carb UFT Extra 5 10 15 20

[0167] The resin components are commercially available as outlined above under Table 1.

[0168] Examples E10 to E13 according to the present invention further comprise Omyacarb UFT in varying dosage levels of 5 phr, 10 phr, 15 phr and 20 phr, which is a commercially available product of calcium carbonate particles. The calcium carbonate is a wet ground GCC, treated with approximately 1% by weight of stearic acid, which had the following properties: [0169] d.sub.50=approximately 0.7 m. [0170] BET surface area (before stearic acid treatment)=approximately 9.5 m.sup.2/g.

[0171] Examples E14 to E11 according to the present invention further comprise Hydrocarb UFT Extra in varying dosage levels of 5 phr, 10 phr, 15 phr and 20 phr, which is a commercially available product of calcium carbonate particles. The calcium carbonate is a wet ground GCC, treated with approximately 0.5% by weight of stearic acid and with approximately 0.5% by weight of a dispersant having a molecular weight of 35,000 g/mol prepared from 92 wt.-% methoxy polyethylene glycol methacrylate of molecular weight 2,000 g/mole and 8 wt.-% acrylic acid and totally neutralised by soda, which had the following properties: [0172] d.sub.50=approximately 0.7 m. [0173] BET surface area (before stearic acid treatment)=approximately 9.5 m.sup.2/g.

[0174] Properties of the samples according to Comparative Examples E1 to E9 are shown in the following Table 3:

TABLE-US-00003 TABLE 3 E1 E2 E3 E4 E5 E6 E7 E8 E9 Density 0.55 0.64 0.7 0.72 0.73 0.63 0.68 0.72 0.76 g/cm.sup.3) Charpy impact 1.8 1.78 1.71 1.71 1.76 1.79 1.67 1.73 1.72 strength at 23 C. (kJ/m.sup.2) STD Dev. 0.23 0.25 0.26 0.27 0.15 0.22 0.22 0.23 0.07 (kJ/m.sup.2)

[0175] The data of Comparative Examples E2 to E9 demonstrate that the incorporation of calcium carbonate having a weight median particle diameter d.sub.50 value of about 1.4 m into the foam increases density above Comparative Example E1 representing an unfilled control, i.e. the composition does not contain calcium carbonate.

[0176] The data further demonstrate that the density increases with higher loadings of such calcium carbonate. The highest increase in density is obtained for the dosage levels of 20 phr of Omyacarb FT and XP-7100T, respectively (cf. Comparative Examples E5 and E9).

[0177] Furthermore, the data show that the charpy impact performance is equivalent across the carbonate products and loading levels used in E2 to E9. Fine calcium carbonate having a weight median particle diameter d.sub.50 value of 1.4 m develops excellent charpy impact properties at up to 20 phr (cf. Comparative Examples E5 and E9) compared to unfilled Comparative Example E1.

[0178] Properties of the samples according to Examples E10 to E11 are shown in the following Table 4:

TABLE-US-00004 TABLE 4 E10 E11 E12 E13 E14 E15 E16 E17 Density 0.61 0.65 0.67 0.71 0.63 0.67 0.69 0.73 (g/cm.sup.3) Charpy impact 1.87 1.92 1.82 1.77 1.85 1.84 1.81 1.71 strength at 23 C. (kJ/m.sup.2) STD Dev. 0.17 0.27 0.29 0.3 0.3 0.34 0.3 0.17 (kJ/m.sup.2)

[0179] The data of Examples E10 to E17 demonstrate that also the incorporation of ultrafine calcium carbonate having a weight median particle diameter d.sub.50 value of 0.7 m into the foam increases density above Comparative Example E1 (density of 0.55 g/cm.sup.3; cf. E1 in Table 3 above).

[0180] The data further demonstrate that above 5 phr, the ultrafine particles having a weight median particle diameter d.sub.50 value of 0.7 m develop lower foam densities than the fine materials having a weight median particle diameter d.sub.50 value of about 1.4 m (cf. E2 to E9 in Table 3 above).

[0181] Furthermore, it can be gathered from Table 4 that the ultrafine calcium carbonate product Omyacarb UFT (E10 to E13) develops excellent foam densities, which is even more efficient in the reduction of foam density compared to the ultrafine calcium carbonate product Hydrocarb UFT Extra (E14 to E17).

[0182] In addition thereto, the data show that the charpy impact performance is also equivalent across the carbonate products and loading levels used in E10 to E17. Ultrafine calcium carbonate having a weight median particle diameter d.sub.50 value of about 0.7 m develops excellent charpy impact properties at up to 20 phr (cf. E13 and E17) compared to unfilled Comparative Example E1.

[0183] For illustrative reasons, the effect of the respective calcium carbonate products on the density of free foam PVC is outlined in FIG. 1 for Comparative Examples E1 to E9 and Examples E10 to E17.

[0184] Furthermore, for illustrative reasons, the effect of the respective calcium carbonate products on the charpy impact strength of free foam PVC is summarized in FIG. 2 for Comparative Examples E1 to E9 and Examples E10 to E17.

[0185] Consequently, a composition for preparing foamed rigid polymer products comprising an especially surface-treated calcium carbonate and azodicarbonamide has been shown to be highly efficient in the reduction of foam density.