Blends of styrene-butadiene co-polymers (SBC) with random blocks and SMMA

Abstract

Polymer composition comprising (a) 33 to 52 wt.-% star-shaped block copolymers (a) comprising terminal vinylaromatic polymer blocks S.sub.1 and S.sub.2, and random styrene/butadiene copolymer blocks (B/S); and (b) 48 to 67 wt.-% SMMA copolymers (b). Moldings and shaped articles produced thereof have a high clarity and toughness and can be used in the household, appliance and healthcare sector.

Claims

1. A polymer composition comprising components (a), (b), and (c): (a) 33 to 52 wt.-% of at least one star-shaped block copolymer (a) which comprises at least two terminal polymer blocks S.sub.1 and S2 made from vinylaromatic monomers and at least one random copolymer block (B/S) made from 20 to 60 wt.-% vinylaromatic monomer, and from 40 to 80 wt.-% diene, and where the total block copolymer (a) is made from 50 to 85 wt.-% vinylaromatic monomer and from 15 to 50 wt.-% diene; (b) 48 to 67 wt.-% of at least one copolymer (b) made from 65 to 90 wt.-% vinylaromatic monomer (b11) and 10 to 35 wt.-% methyl methacrylate (b12); and optionally (c) 0 to 5 wt.-% of one or more additive(s) and/or processing aid (c), wherein the total amount of components (a), (b), and (c) is 100 wt.-%; the star-shaped block copolymer (a) has structures in which the star has at least one branch having the block sequence S.sub.1-(B/S).sub.1-(B/S).sub.2 and at least one branch having the block sequence S.sub.2-(B/S).sub.1-(B/S).sub.2, or in which the star has at least one branch with the block sequence S.sub.1-(B/S).sub.1-(B/S).sub.2-S.sub.3 and at least one branch with the block sequence S.sub.2-(B/S).sub.1-(B/S).sub.2-S.sub.3, wherein: M.sub.n of S.sub.1 is from 5,000 to 30,000 g/mol; M.sub.n of S.sub.2 is from 35,000 g/mol to 150,000 g/mol; and S.sub.3 is a further polymer block made from vinylaromatic monomers with M.sub.n being smaller than 2,500 g/mol; and the random copolymer block (B/S).sub.1 is made from 40 to 60 wt.-% vinylaromatic monomer and from 40 to 60 wt.-% diene, and the random copolymer block (B/S).sub.2 is made from 20 to 39 wt.-% vinylaromatic monomer and from 61 to 80 wt.-% diene.

2. The polymer composition according to claim 1 comprising components (a), (b), and (c) in the following amounts: 33 to 50 wt.-% (a), 50 to 67 wt.-% (b), and 0 to 5 wt.-% (c).

3. The polymer composition according to claim 1 comprising components (a), (b), and (c) in the following amounts: 34 to 45 wt.-% (a), 55 to 66 wt.-% (b), and 0 to 4 wt.-% (c).

4. The polymer composition according to claim 1, wherein the values of the refractive index of components (a) and (b) differ no more than 0.005.

5. The polymer composition according to claim 1, wherein the copolymers (b) are made from 70 to 85 wt.-% (b11), and 15 to 30 wt.-% (b12).

6. The polymer composition according to claim 1, wherein the copolymers (b) are made from 74 to 84 wt.-% (b11) and 16 to 26 wt.-% (b12).

7. A process for the preparation of the polymer composition according to claim 1, prepared by mixing the components (a), (b), and (c).

8. A molding, a fiber, or a foil, comprising the polymer composition according to claim 1.

9. A method of using a molding, a fiber, or a foil, comprising the polymer composition according to claim 1 in the household, appliance, and healthcare sector.

10. The polymer composition according to claim 1, wherein the star-shaped block copolymer (a) is of the following structures: ##STR00003## where X is a tetrafunctional coupling agent.

11. The polymer composition according to claim 1 comprising components (a), (b), and (c): (a) 33 to 52 wt.-% of at least one star-shaped block copolymer (a) which comprises at least two terminal polymer blocks S.sub.1 and S.sub.2 made from styrene and at least one random copolymer block (B/S) made from 20 to 60 wt.-% styrene and from 40 to 80 wt.-% 1,3-butadiene, and where the total block copolymer (a) is made from 50 to 85 wt.-% styrene and from 15 to 50 wt.-% 1,3-butadiene; (b) 48 to 67 wt.-% of at least one copolymer (b) made from 65 to 90 wt.-% styrene (b11) and 10 to 35 wt.-% methyl methacrylate (b12); and (c) 0 to 5 wt.-% of one or more additive(s) and/or processing aid (c), wherein the total amount of components (a), (b), and (c) is 100 wt.-%; the star-shaped block copolymer (a) has structures in which the star has at least one branch having the block sequence S.sub.1-(B/S).sub.1-(B/S).sub.2 and at least one branch having the block sequence S.sub.2-(B/S).sub.1-(B/S).sub.2, or in which the star has at least one branch with the block sequence S.sub.1-(B/S).sub.1-(B/S).sub.2-S.sub.3 and at least one branch with the block sequence S.sub.2-(B/S).sub.1-(B/S).sub.2-S.sub.3, wherein: M.sub.n of S.sub.1 is from 5,000 to 30,000 g/mol; M.sub.n of S2 is from 35,000 g/mol to 150,000 g/mol; and S.sub.3 is a further polymer block made from vinylaromatic monomers with M.sub.n being smaller than 2,500 g/mol; and the random copolymer block (B/S).sub.1 is made from 40 to 60 wt.-% styrene and from 40 to 60 wt.-% 1,3-butadiene, and the random copolymer block (B/S).sub.2 is made from 20 to 39 wt.-% styrene and from 61 to 80 wt.-% 1,3-butadiene.

Description

EXAMPLES

(1) Test methods:

(2) Modulus of elasticity, tensile stress at break, and tensile strain at break were determined in the tensile test to ASTM D638. The melt flow rate was determined to ASTM D1238 at 200° C. and 5 kg. The Notched Izod impact strength was determined in accordance with D256. The haze and optical properties were determined in accordance with ASTM D1003. The Vicat softening point was determined according to ASTM D1525 (10 N force and 120° C/hour rate).

(3) Starting materials: SMMA 1 random styrene-methylmethacrylate-copolymer with a methylmethacrylate content of 24% by weight; M.sub.w 280,000 g/mol; with 3 wt.-% (related to the total weight of the SMMA copolymer) mineral oil plasticizer (Drakeol® 34) incorporated in the SMMA copolymer. SMMA 2 random styrene-methylmethacrylate-copolymer with a methylmethacrylate content of 21.5% by weight, M.sub.w 220,000 g/mol. SBC 1 star shaped styrene butadiene copolymer of the structure

(4) ##STR00002## with random 50/50 butadiene/styrene copolymer blocks (B/S).sub.1and random 67/33 butadiene/styrene copolymer blocks (B/S).sub.2 and styrene homopolymer blocks S1, S2, and S3.

(5) Star-shaped styrene butadiene block copolymers SBC 1 were obtained by sequential anionic polymerisation of styrene and butadiene in cyclohexane as solvent at from 60 to 90° C., followed by coupling using epoxidized linseed oil (Edenol B 316 from Henkel).

(6) The process was carried out using as initial charge of sec-butyllithium and cyclohexane titrated to the end point with sec-butyllithium in a 1500 I stirred reactor and metering in the amount of styrene (styrene I) needed to prepare the block Sa.

(7) This was followed by another initiation using sec-butyllithium (sec-BuLi II) and metering in the appropriate amount of styrene (styrene II) for the block Sb. After all of the styrene had been consumed, potassium tert. acrylate (KTA) (Li:K=36:1) was added as randomizer and the blocks (B/S).sub.1 were attached by adding a mixture of styrene (styrene III) and butadiene I. Then the blocks (B/S).sub.2 were polymerized on by adding a mixture of styrene (styrene IV) and butadiene II. A final amount of styrene (styrene V) was added to make a short block S.sub.c. The resultant living block copolymer chains were then coupled using Edenol B 316.

(8) The amounts of the starting materials used are given in Table 1.

(9) (The block termed S.sub.i in the description corresponds to S.sub.b, S.sub.2 is formed from S.sub.a and S.sub.b.)

(10) TABLE-US-00001 TABLE 1 Amounts of starting materials used for SBC 1 Block unit Cyclohexane I 300 Styrene I S.sub.a kg 183 sec-Buli I 1.35 m I 2.197 K-THL (3%) I 0.325 sec-Buli II 1.35 m I 5.270 Styrene II S.sub.b kg 114 Butadiene I (B/S).sub.1 kg 38.1 Styrene III (B/S).sub.1 kg 37.4 Butadiene II (B/S).sub.2 kg 102 Styrene IV (B/S).sub.2 kg 49.3 Styrene V S.sub.c kg 14.0 Edenol B316 I 1.19

(11) SBC 2: Styrolux® 684D obtained from INEOS Styrolution, Frankfurt/Germany; a styrene butadiene block copolymer with a tapered block architecture where the B/S block becomes progressively more rich in one monomer constituent as it progressives from one end to the other.

(12) SBC 3: K-Resin® SBC grade KR03 obtained from Chevron Phillips Chemical Company LP, USA; a styrene butadiene block copolymer with a sharp block transition. Block copolymer SBC 1 with random blocks (B/S) was blended with copolymer SMMA 1 (see Tables 2, 3 and 4).

(13) The materials as shown in Tables 2 and 3 were compounded using a 30 mm twin screw extruder with zone temperatures set from 180 to 190° C. Specimens were injection molded and tested for their mechanical and optical properties.

(14) TABLE-US-00002 TABLE 2 wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- Formulation % % % % % % % % SMMA 1 80 70 60 50 40 30 20 10 SBC 1 20 30 40 50 60 70 80 90 Total 100 100 100 100 100 100 100 100 Properties Melt Flow 2.5 3.1 3.8 4.5 3.1 4.5 6.8 8.2 Rate, g/10 min. Notched Izod 0.5 0.4 8.6 12.5 13.8 13.3 11.4 13.6 impact strength, ft-lb/in Haze, % 2.0 1.4 1.0 1.4 2.4 2.8 2.1 2.2

(15) Notched Izod impact strength measurements exceeding 8.0 ft-lb/in, which is quite high, were obtained with as little as 40 wt.-% of the SBC (cp. Table 2).

(16) TABLE-US-00003 TABLE 3 Formulation wt.-% wt.-% wt.-% wt.-% wt.-% SMMA 1 69.9 59.9 49.9 39.9 29.9 SBC 1 30 40 50 60 70 Irganox 1076 0.1 0.1 0.1 0.1 0.1 Properties Notched Izod impact strength, ft-lb/in 0.4 11.7 12.8 13.6 11.4 Melt flow rate, g/10 min 3.4 4.5 5.0 5.3 6.4 Tensile stress at yield, psi 4300 3380 3010 2380 2380 Tensile stress at break, psi 4350 3580 3240 2930 2680 Tensile strain at break, % 32 47 73 104 136 Flexural strength, psi 8710 6400 5200 4160 3520 Flexural modulus, kpsi 351 268 229 192 166 Vicat Softening Point, ° C. 98 96 93 87 81 Clarity (Illuminate CIE-C), % 98.5 98.6 98.7 99.2 99.2 Haze (Illuminate CIE-C), % 2.2 2.2 2.6 2.4 3.0 Transmittance (Illuminate CIE-C), % 89.7 89.7 89.2 88.9 88.8

(17) The materials as shown in Table 4 were compounded using a single screw 1.5 inch extruder with zone temperatures set from 218 to 232° C. Specimen were injection molded and tested for their mechanical and optical properties.

(18) TABLE-US-00004 TABLE 4 Formulation wt.-% wt.-% wt.-% wt.-% wt.-% SMMA 1 69 66 63 60 57 SBC 1 31 34 37 40 43 Total 100 100 100 100 100 Properties Notched Izod impact 0.4 3.3 3.9 5.5 8.1 strength, ft-lb/in Melt flow rate, g/10 min 3.0 3.6 3.7 3.7 4.0 Vicat Softening Point, 97 97 97 95 95 ° C. Tensile stress at yield, 4104 3854 3647 3516 3368 psi Tensile stress at break, 4281 3952 3819 3678 3567 psi Tensile strain at break, % 42 42 42 47 54 Clarity (Illuminate 98.7 98.2 98.7 98.6 97.8 CIE-C) Haze (Illuminate CIE-C) 2.8 2.8 2.5 2.5 2.9 Transmittance 90.3 89.8 90.0 90.0 89.2 (Illuminate CIE-C)

(19) A tough product with notched Izod impact strength exceeding 3 ft-lb/in was achieved with as little as 34 wt.-% SBC (cp. Table 4), which demonstrates extremely high potency.

(20) Block copolymer SBC 1 with random blocks (B/S) was blended with copolymer SMMA 2 (see Table 5). The materials as shown in Table 5 were compounded using a single screw 1.5 inch extruder with zone temperatures set from 218 to 232° C. Specimens were injection molded and tested for their mechanical and optical properties.

(21) TABLE-US-00005 TABLE 5 wt- wt- wt- wt- wt- wt- Formulation .% .% .% .% .% .% SMMA 2 69.9 59.9 49.9 39.9 29.9 19.9 SBC 1 30.0 40.0 50.0 60.0 70.0 80.0 Irganox 1076 0.1 0.1 0.1 0.1 0.1 0.1 Total 100 100 100 100 100 100 Properties Notched Izod impact strength, ft-lb/in 0.5 0.5 3.0 11.9 13.3 13.7 Melt flow rate, g/10 min 3.8 4.4 4.8 5.1 6.0 6.6 Vicat Softening Point, ° C. 101 99 97 95 89 84 Tensile stress at yield, psi 5950 4633 3647 3363 2697 1916 Tensile stress at break, psi 4350 3981 3589 3493 3162 2881 Tensile strain at break, % 16 28 56 69 96 130 Clarity (Illuminate CIE-C) 98.1 98.1 98.7 98.8 98.7 98.6 Haze (Illuminate CIE-C) 1.5 2.0 1.5 1.6 1.7 2.2 Transmittance (Illuminate CIE-C) 91.1 90.6 90.3 90.6 90.2 90.4

(22) Outstanding toughness was achieved with as low as 50 wt.-% SBC 1 (cp. Table 5).

(23) By comparison, Tables 6 and 7 contain the results of SMMA 2 blended with an SBC with a tapered block arrangement (SBC 2).

(24) The materials as shown in Tables 6 and 7 were compounded using a single screw 0.75 inch extruder with zone temperatures set from 160 to 200° C. Specimens were injection molded and tested for their mechanical and optical properties.

(25) TABLE-US-00006 TABLE 6 wt.- wt.- wt.- wt.- wt.- wt.- wt.- Formulation % % % % % % % SBC 2 60 55 50 45 40 38 36 SMMA 2 40 45 50 55 60 62 64 Total 100 100 100 100 100 100 100 Properties Notched Izod impact 0.4 0.3 0.3 0.3 0.4 0.5 0.4 strength, ft-lb/in Melt flow rate, g/10 min 5.5 5.4 5.3 4.6 4.7 4.8 5.0 Vicat Softening Point, ° C. 96 97 98 99 100 100 100 Tensile stress at yield, psi 4222 4507 4827 5268 5312 5318 5166 Tensile stress at break, psi 3624 3764 4032 4326 4252 4258 4128 Tensile strain at break, % 45 45 36 34 29 13 16 Haze (Illuminate CIE-C), % 2.5 2.7 2.6 2.4 1.8 1.6 1.7

(26) TABLE-US-00007 TABLE 7(a) wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- Formulation % % % % % % % % % % % SBC 2 0 10 20 30 40 50 60 70 80 90 100 SMMA 2 100 90 80 70 60 50 40 30 20 10 0 Total 100 100 100 100 100 100 100 100 100 100 100 Properties Melt flow 2.8 2.6 2.7 3.4 4.2 5.2 5.2 6.3 7.5 8.4 10.1 rate, g/10 min Notched Izod 0.4 0.4 0.3 0.4 0.4 0.4 0.2 0.5 0.7 0.6 0.6 impact strength, ft-lb/in Haze 0.5 0.8 1.1 1.3 1.6 2.1 2.5 3.1 3.3 3.5 2.8 (Illuminate CIE-C), %

(27) TABLE-US-00008 TABLE 7(b) Mineral oil (Drakeol 34) is incorporated into SMMA 2 to improve ductility. wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- Formulation % % % % % % % % % % % SBC 2 0 10 20 30 40 50 60 70 80 90 100 SMMA 2 + 3 100 90 80 70 60 50 40 30 20 10 0 wt.-% Mineral Oil Total 100 100 100 100 100 100 100 100 100 100 100 Properties Melt flow rate, 3.5 4.2 4.5 5.2 5.8 6.2 6.8 7.5 8.6 8.8 10.1 g/10 min Notched Izod 0.4 0.4 0.4 0.5 0.5 0.3 0.6 4.4 2.5 0.8 0.6 impact strength, ft-lb/in Haze (Illuminate 0.5 1.3 2.4 2.9 3.3 3.7 4.0 3.9 3.8 3.8 2.8 CIE-C), %

(28) The amount of the mineral oil relates to the total weight of the SMMA copolymer.

(29) Aside from a narrow range around 70% SBC (Table 7(b)) the toughness of such blends is low. In all cases, the toughness is below that of the blends according to Tables 2 to 5 comprising SBCs with randomly arranged blocks.

(30) Also by comparison, Tables 8 and 9 contain results for SBC 2 with tapered block architecture blended with SMMA 1. The materials as shown in Table 8 were compounded using a single screw 0.75 inch extruder with zone temperatures set from 160 to 200° C. Specimens were injection molded and tested for their mechanical and optical properties.

(31) TABLE-US-00009 TABLE 8 wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- Formulation % % % % % % % % % % % SBC 2 0 10 20 30 40 50 60 70 80 90 100 SMMA 1 100 90 80 70 60 50 40 30 20 10 0 Total 100 100 100 100 100 100 100 100 100 100 100 Properties Melt flow rate, 1.5 1.8 2.2 3.2 3.7 4.5 5.3 6.5 7.4 11.0 10.1 g/10 min Notched Izod 0.7 0.6 0.4 0.4 0.5 0.6 11.9 12.2 12.6 0.9 0.6 impact strength, ft-lb/in Haze (Illuminate 0.7 1.8 2.2 2.6 2.8 3.1 2.7 3.0 3.6 6.9 2.8 CIE-C), %

(32) The materials as shown in Table 9 were compounded using a 30 mm twin screw extruder with zone temperatures set from 180 to 190° C. Specimens were injection molded and tested for their mechanical and optical properties.

(33) TABLE-US-00010 TABLE 9 wt.- wt.- wt.- wt.- wt.- wt.- Formulation % % % % % % SMMA 1 54.9 49.9 44.9 39.9 34.9 29.9 SBC 2 45.0 50.0 55.0 60.0 65.0 70.0 Irganox 1076 0.1 0.1 0.1 0.1 0.1 0.1 Total 100 100 100 100 100 100 Properties Notched Izod impact strength, 0.5 2.0 2.5 11.7 11.3 11.5 ft-lb/in Melt flow rate, g/10 min 4.6 5.0 5.1 5.8 5.9 7.1 Tensile stress at yield, psi 3550 3370 3180 2990 2700 2670 Tensile stress at break, psi 3590 3490 3380 3260 3110 3020 Tensile strain at break, % 58 72 83 85 98 103 Clarity (Illuminate CIE-C), % 99.3 99.3 98.8 99.3 99.3 99.4 Haze (Illuminate CIE-C), % 2.0 1.8 1.8 2.1 2.5 2.6 Transmittance (Illuminate CIE-C), % 89.9 89.5 89.5 89.9 88.5 88.5

(34) The range of high toughness is again narrower and begins at a significantly higher SBC content (see Tables 8 and 9) demonstrating a lack of potency vs. SBC 1 (cp. Tables 2 to 5).

(35) Tables 10 and 11 illustrate comparative data obtained by blending an SBC with a sharp block transition (SBC 3) with SMMA 2. The materials as shown in Table 10 were compounded using a single screw 0.75 inch extruder with zone temperatures set from 160 to 200° C.

(36) Specimens were injection molded and tested for their mechanical and optical properties.

(37) TABLE-US-00011 TABLE 10 wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- wt.- Formulation % % % % % % % % % % % SBC 3 0 10 20 30 40 50 60 70 80 90 100 SMMA 2 + 100 90 80 70 60 50 40 30 20 10 0 3 wt.-% Mineral Oil Total 100 100 100 100 100 100 100 100 100 100 100 Properties Melt flow rate, g/10 min 3.5 4.0 4.1 4.9 5.0 4.9 5.3 5.6 5.8 6.4 7.0 Notched Izod 0.4 0.4 0.4 0.4 0.4 0.5 0.6 1.0 0.8 0.5 5.8 impact strength, ft-lb/in Haze (Illuminate CIE-C), % 0.5 0.9 1.7 2.2 2.3 2.4 2.3 2.1 2.0 1.6 1.5

(38) The materials as shown in Table 11 were compounded using a single screw 1.5 inch extruder with zone temperatures set from 218 to 232° C. Specimens were injection molded and tested for their mechanical and optical properties.

(39) TABLE-US-00012 TABLE 11 Formulation wt.-% wt.-% wt.-% SMMA 2 39.9 29.9 19.9 SBC 3 60.0 70.0 80.0 Irganox 1076 0.1 0.1 0.1 Total 100 100 100 Properties Notched Izod impact strength, ft-lb/in 0.5 0.5 0.5 Melt flow rate, g/10 min 4.4 4.7 5.4 Vicat Softening Point, ° C. 98 96 94 Tensile stress at yield, psi 3945 3444 3351 Tensile stress at break, psi 3489 3176 2963 Tensile strain at break, % 54 81 94 Clarity (Illuminate CIE-C) 99.5 98.8 99.3 Haze (Illuminate CIE-C) 1.1 1.5 0.9 Transmittance (Illuminate CIE-C) 91.1 90.9 91.1

(40) Tables 10 and 11 illustrate the comparative lack of toughness obtained by blending an SBC with a sharp block transition (SBC 3) with SMMA 2.