Compositions, containing thermoplastics based on polyvinyl chloride and containing cross-linked NBR microgels modified with hydroxyl groups

Abstract

The present invention relates to a composition obtainable by mixing to incorporate at least one microgel (B) that has been crosslinked by means of free-radical generators photochemical by using a wavelength>0.1 m and/or thermally and that contains hydroxy groups and that is based on polybutadiene-acrylonitrile copolymers (NBR) into polyvinyl chloride (PVC) in an extruder, to processes for production thereof and to use thereof for reproduction of transparent thermoplastically processable molded items, and also to molded items produced from the said compositions.

Claims

1. A composition comprising: at least one polyvinyl chloride thermoplastic, and at least one microgel comprising at least one of: a crosslinked polybutadiene-acrylonitrile copolymer microgel that contains hydroxy groups, and a crosslinked, carboxylated, polybutadiene-acrylonitrile copolymer microgel that contains hydroxy groups, wherein the microgel is thermally cross-linked using organic peroxides, as thermal free-radical initiator.

2. The composition according to claim 1, wherein the microgel contains individual primary particles, and the deviation of the diameters of an individual primary particle of the microgel, defined as
[(d1d2)/d2]100% is smaller than 500%, where d1 and d2 are diameters of the primary particle with the proviso that d1 is >d2.

3. The composition according to claim 1, wherein the median particle size d.sub.50 of the primary particles of the microgel is 5 to 500 nm.

4. The composition according to claim 1, wherein the crosslinked polybutadiene-acrylonitrile copolymer microgel that contains hydroxy groups, and the crosslinked, carboxylated, polybutadiene-acrylonitrile copolymer microgel that contains hydroxy groups each have an acrylonitrile content of 10% to 80%.

5. The composition according to claim 1, wherein the microgel comprises at least about 70% by weight of fractions insoluble in toluene at 23 C.

6. The composition according to claim 1, wherein: the swelling index of the microgel in toluene at 23 C. is less than about 80; the glass transition temperature of the microgel is from 60 C. to +50 C.; and the breadth of the glass transition range of the microgel is greater than about 5 C.

7. The composition according to claim 1, wherein the microgel is cross-linked using trimethylolpropane trimethacrylate (TMPTMA).

8. The composition according to claim 1, the composition has a thermoplastic/microgel ratio by weight of 99:1 to 60:40.

9. The composition according to claim 1, produced by a method comprising mixing the at least one polyvinyl chloride and the at least one microgel.

10. A process for the production of the composition according to claim 1, the process comprising: crosslinking the at least one microgel thermally using organic peroxides to produce at least one crosslinked microgel; and mixing the at least one polyvinyl chloride and the at least one crosslinked microgel.

11. A masterbatch for thermoplastic materials, the masterbatch comprising a composition according to claim 1.

12. Moulded items obtained via moulding of a composition according to claim 1.

13. The composition according to claim 1, wherein: the microgel contains individual primary particles, and the deviation of the diameters of an individual primary particle of the microgel, defined as [(d1d2)/d2]100%, where d1 and d2 are diameters of the primary particle with the proviso that d1 is >d2, is smaller than 500%; the median particle size d.sub.50 of the primary particles of the microgel is 5 to 500 nm; the crosslinked polybutadiene-acrylonitrile copolymer microgel that contains hydroxy groups, and the crosslinked carboxylated, polybutadiene-acrylonitrile copolymer microgel that contains hydroxy groups each have an acrylonitrile content of 10% to 80%; the microgel comprises at least about 70% by weight of fractions insoluble in toluene at 23 C.; the swelling index of the microgel in toluene at 23 C. is less than about 80; the glass transition temperature of the microgel is from 60 C. to +50 C.; the breadth of the glass transition range of the microgel is greater than about 5 C.; and the composition has a thermoplastic/microgel ratio by weight of 99:1 to 60:40.

14. The composition according to claim 13, wherein: the acrylonitrile content of the crosslinked polybutadiene-acrylonitrile copolymer microgel that contains hydroxy groups, and the crosslinked, carboxylated, polybutadiene-acrylonitrile copolymer microgel that contains hydroxy groups is 20% to 30%; the median particle size d.sub.50 of the primary particles of the microgel is 40 to 80 nm; the microgel comprises at least about 90% by weight of fractions insoluble in toluene at 23 C.; the swelling index of the microgel in toluene at 23 C. is 1 to 15; the glass transition temperature of the microgel is from 40 C. to 15 C.; the breadth of the glass transition range of the microgel is greater than about 20 C.; and the thermoplastic/microgel ratio is 97:3 to 85:15.

15. A thermoplastic composition comprising: polyvinyl chloride, and hydroxy-functionalized, polybutadiene-acrylonitrile copolymer microgel, crosslinked with organic peroxides.

16. The thermoplastic composition according to claim 15, wherein the microgel has a hydroxy number of 0.1 to 100 mg KOH/g of polymer as determined in accordance with DIN 53240 via reaction with acetic anhydride and use of KOH for titration of the acetic acid liberated.

17. The thermoplastic composition according to claim 16, wherein the hydroxy number is 0.5 to 50 mg KOH/g of polymer.

Description

EXAMPLES

(1) Starting Materials

(2) Baymod N XL 38.43, an unmodified NBR rubber from Lanxess Deutschland GmbH. Nanoprene B M75-OH-VP, a peroxidically crosslinked, nanoscale BR elastomer from Lanxess Deutschland GmbH, modified with hydroxy groups. Polyvinyl chloride (PVC, Troilit1003), a PVC from GRANULAT 2000 Kunststoff Compound GmbH & Co. KG. EDTA=ethylenediaminetetraacetic acid from Merck-Schuchardt. Iron(II) sulphate7H.sub.2O from Merck-Schuchardt. Diethylhydroxylamine from Sigma Aldrich. HEMA=hydroxyethyl methacrylate from Sigma Aldrich. p-Menthane hydroperoxide (Trigonox NT 50) from Akzo-Degussa. Sodium formaldehyde sulphoxylate hydrate (Rongalit) from Merck-Schuchardt. Trisodium phosphate12H.sub.2O from Benckiser. Trimethylolpropane trimethacrylate (TMPTMA) from Lanxess Deutschland GmbH. Mersolat K30/95: the Na salts of a mixture of long-chain alkylsulphonic acids from Bayer MaterialScience AG.

(3) 1. Production of Microgels (B)

(4) Production example 1 for NBR-based microgel containing hydroxy groups and derived from thermal/peroxidic crosslinking by means of TMPTMA (Micromorph 20).

(5) Production of the microgel used the following monomers in the stated ratios by weight: 68.8% by weight of butadiene, 26.7% by weight of acrylonitrile, 3.0% by weight of TMPTMA and 1.5% by weight of HEMA.

(6) 172 g of Mersolat K30/95 were dissolved in 12.427 kg of water and used as initial charge in a 40 l autoclave. The autoclave was evacuated three times and filled with nitrogen. 2957 g of butadiene, 1150 g of acrylonitrile, 129 g of TMPTMA (90%), 64.5 g of HEMA (96%) were then added. The reaction mixture was heated to 30 C. with stirring. An aqueous solution composed of 45 g of water, 500 mg of EDTA, 500 mg of iron(II) sulphate7H.sub.2O, 1.00 g of sodium formaldehyde sulphoxylate hydrate (Rongalit Merck-Schuchardt) and 1.5 g of trisodium phosphate12H.sub.2O were then added to the mixture.

(7) The reaction was initiated via addition of 3.0 g of Trigonox NT 50 in 200 g of water, and 185 g of water were used subsequently here for flushing. After a reaction time of 2.5 hours, the reaction temperature was increased to 40 C. After a reaction time of a further hour, 350 mg of Trigonox NT 50, which had been dissolved in an aqueous solution of 25 g of water and 1.25 g of Mersolat K30/95, were used for post-activation. The polymerization temperature here was increased to 50 C. Once conversion>95% had been achieved, the polymerization process was terminated via addition of an aqueous solution of 53 g of diethylhydroxylamine dissolved in 100 g of water. Unconverted monomers were then removed from the latex by stripping with steam

(8) The latex was filtered and, as in Example 2 of U.S. Pat. No. 6,399,706, stabilizer was admixed, and the latex was coagulated and dried.

(9) Prior to use of the microgel, it was dried to constant weight at 100 mbar in a Vacutherm VT 6130 vacuum drying oven from Heraeus Instruments.

(10) TABLE-US-00002 TABLE 1 Properties of microgels (B) Proportion of Gel TMPTMA for content OH Acid Production Microgel crosslinking d.sub.50 O.sub.spec Density [% by Tg Tg number number example type [phr] [nm] [m.sup.2/g] [g/cm.sup.3] weight] Qi [ C.] [ C.] [mg KOH/g of pol.] 1 OH-NBR 3 64 102 0.974 92 8 34 11 7 7 2 OH BR 4 51 127 0.929 92 13 76 13 28 7 phr: parts per 100 rubber

(11) Test Methods:

(12) The following test methods were used to determine the physical parameters of the microgel latices produced:

(13) d.sub.50: the definition of the diameter d.sub.50 in accordance with DIN 53 206 is the value for half of all of the particle sizes. The diameter of the latex particles is determined by means of an ultracentrifuge (W. Scholtan, H. Lange, Bestimmung der Teilchengren-verteilung von Latices mit der Ultrazentrifuge [Determination of the particle size distribution of latices with an ultracentrifuge], Kolloid-Zeitcchrift und Zeitschrift fr Polymere (1972) Volume 250, Issue 8). The diameter data in the latex and for the primary particles in the compositions of the invention are practically identical, since the size of the microparticles undergoes practically no change during the production of the composition of the invention.

(14) O.sub.spec: specific surface area in m.sup.2/g

(15) density: in g/cm.sup.3 at 20 C.

(16) Gel Content

(17) The gel content corresponds to the fraction insoluble in toluene at 23 C. It was determined as described above.

(18) Swelling Index

(19) Qi (swelling index)=wet weight of microgel/dry weight of microgel. The swelling index Qi was determined as follows:

(20) the swelling index was calculated from the weight of the solvent-containing microgel swollen for 24 hours in toluene at 23 C. and the weight of the dry microgel:

(21) the swelling index is determined by swelling 250 mg of the microgel in 25 ml toluene for 24 h with shaking. The toluene-swollen (wet) gel was weighed after centrifuging at 20 000 rpm, and then was dried to constant weight at 70 C. and again weighed (dry microgel).

(22) Glass transition temperature Tg: DSC-2 equipment from Perkin-Elmer was used to determine Tg.

(23) Breadth of glass transition Tg: DSC-2 equipment from Perkin-Elmer was used to determine Tg.

(24) OH Number (Hydroxy Number)

(25) OH number (hydroxy number) was determined in accordance with DIN 53240, and corresponds to the amount of KOH in mg that is equivalent to the amount of acetic acid liberated when 1 g of substance is acetylated with acetic anhydride.

(26) Acid Number

(27) Acid number was determined in accordance with DIN 53402, and corresponds to the amount of KOH in mg that is required to neutralize 1 g of the polymer.

(28) 2. Production of the Microgel-Containing Compositions and Characterization Thereof

Example 1

(29) A material available for purchase in the market for purposes of PVC-modification, namely Baymod N XL 38.43, was used as reference in relation to the thermoplastics-microgel compositions.

(30) The microgel-containing compositions were produced in a twin-screw extruder (ZSK 27 HP, manufacturer Leistritz; screw diameter d=27 mm, L/D>56) with corotating screws. The mixing took place at a rotation rate of 300 rpm and with a throughput of 15 kg/h. The temperature profile of the extruder zones (L/D ratio per zone=4), abbreviated to Z, was: Z00=cooled, Z01=160 C., Z02=170 C., Z03=170 C., Z04=160 C., Z05=150 C., Z06=145 C., Z07=145 C., Z08=145 C., Z09=145 C., Z10=145 C., Z11=145 C., Z12=145 C., Z13=15 C., Z14=160 C. Mixtures of Micromorph 20P/Troilit 1003, Nanoprene B M75-OH-VP/Troilit 1003 and Baymod N XL 38.43/Troilit 1003 were produced in a ratio by weight of respectively 5/95%, 10/90%, 15/85%; for reference, the same procedure was used but only with Troilit 1003. The extrusion process was identical for all of the mixtures. For this, the Troilit 1003 was first continuously charged to the extruder zone Z00 by way of a gravimetric metering balance. The respective Micromorph was then added continuously to the extruder by means of a side-feed unit in Z05 by using a further gravimetric metering balance. After the extrusion process, two visually homogeneous strands were passed into a water bath for cooling and were pelletized by means of a strand pelletizer.

(31) Infection Moulding:

(32) After drying of the materials, these were processed to give standard F3 tensile specimens in an Arburg Allrounder 320S injection-moulding machine. The machine temperature was 195 C., with a backpressure of 5 bar and a mould temperature of 80 C.

(33) The following test methods were used for all of the specimens mentioned below in the Examples:

(34) Shore D Hardness

(35) The test specimens were conditioned at RT for 1 h prior to the test. The specimens with microgel exhibit no significant changes of Shore A hardness within the bounds of accuracy of measurement. Table 2 collates the values determined.

(36) Tensile Test

(37) The tensile test took place on standard F3 test specimens (see above) in accordance with DIN 53455. The test was carried out with a universal tester (Frank 1445) with optical length sensors. The measurement range of the force sensor was from 0 to 1000 N. Table 2 collates the results of the tests.

(38) The machine-parameter settings here were as follows: preloading force: 0.1 N velocity during application of preloading force: 1 mm/min load: 1000N test velocity: 200 mm/min
Notched Impact Resistance:

(39) In order to determine the capability of the materials to resist impact-type (dynamic) stress, HIT5.5P equipment from Zwick/Roell with a 4 J Charpy pendulum was used at room temperature to carry out a notched-impact-resistance analysis on the materials. Appropriate peripheral equipment from Zwick/Roell was used to produce the notch in accordance with standard.

(40) The compositions/test specimens obtained exhibited the following properties listed in Table 2:

(41) TABLE-US-00003 TABLE 2 Results from physical testing of the following materials: Thermoplastics-microgel compositions of the invention (I1 to I3), comparative mixtures (C2 to C4 to C7) and PVC alone (C1) NIR Example (Charpy DIN 53753) Impact Elongation at No. Materials (test rig) resistance break [%] Shore D hardness C1 Troilit1003 Notched, Charpy 4J pendulum 3.3 3.8 81 I1 (NBR) 5% of Micromorph 20.sup.1) Notched, Charpy 4J pendulum 6.7 4.9 82 I2 10% of Micromorph 20.sup.1) Notched, Charpy 4J pendulum 16.8 10.6 80 I3 15% of Micromorph 20.sup.1) Notched, Charpy 4J pendulum 102.5 20.4 75 C2 5% of N XL 38.43.sup.1) Notched, Charpy 4J pendulum 2.7 3.7 81 C3 10% of N XL 38.43.sup.1) Notched, Charpy 4J pendulum 3.3 4.6 83 C4 15% of N XL 38.43.sup.1) Notched, Charpy 4J pendulum 3.0 7.2 81 C5 (BR) 5% of NanopreneB M75-OH-VP.sup.1) Notched, Charpy 4J pendulum 3.4 8.9 78 C6 15% of NanopreneB M75-OH-VP1) Notched, Charpy 4J pendulum 5.2 17.9 76 C7 15% of NanopreneB M75-OH-VP1) Notched, Charpy 4J pendulum 7.1 22.9 74 C = Comparative Example, I = according to the invention; .sup.1)remainder was composed of Troilit 1003; Nanoprene B M-75-OH-VP is a BR microgel

(42) From Table 2 if can be seen that both PVC mixtures modified with microgel that contains hydroxy groups are markedly superior not only to the PVC alone but also to the PVC provided with the commercially available product Baymod N XL 38.43. Addition of 5% of Micromorph 20 to Troilit 1003 raises the notched impact resistance by 100%, and addition of 10% of Micromorph 20 raises the same by 400%, while Shore D hardness was retained.

Example 2Transparency of the Tensile Specimens Produced

(43) Although the microgel-containing test sheets have an intrinsic colour, the NBR-containing microgels of the invention remained transparent even at 15% microgel content, since they have very good dispersion.

(44) The NBR-microgel-PVC compositions modified with hydroxy groups (I1-I3) exhibited good transparency, whereas the BR-microgel-PVC compositions (C5-C7) and Baymod N XL 38.43-PVC compositions (C2-C4) are opaque.

(45) Is therefore possible with the compositions of the invention to produce materials which in comparison with commercially available products have superior mechanical properties and moreover retain transparency.