ABS molding composition having improved crack and chemical resistance and its use

Abstract

Thermoplastic molding composition scan be advantageously used in hydrofluoro olefin containing areas, comprising components A, B, C and, D: 10 to 35 wt.-% ABS graft rubber A obtained by emulsion polymerization, 50 to 75 wt.-% SAN copolymer B, 4 to 20 wt.-% copolymer C from ethylene and C.sub.1-C.sub.6-alkyl(meth)acrylate, and 4 to 20 wt.-% ABS graft rubber copolymer D obtained by mass polymerization.

Claims

1. A method in which a thermoplastic molding composition is formed into a shaped article requiring resistance to hydrofluoro olefins, wherein the thermoplastic molding composition comprises components A, B, C, and D: (A) 10 to 35 wt.-% of at least one graft rubber copolymer A obtained by emulsion polymerization and built up from: (a.sub.1) 30 to 90 wt.-%, based on (A), of at least one graft base (a.sub.1) made from: (a.sub.11) 70 to 98 wt.-%, based on (a.sub.1), of at least one diene, and (a.sub.12) 2 to 30 wt.-%, based on (a.sub.1), of at least one monomer selected from the group consisting of styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, and methyl methacrylate, and (a.sub.2) 10 to 70 wt.-%, based on (A), of a graft (a.sub.2), grafted onto the graft base and built up from: (a.sub.21) 65 to 95 wt.-%, based on (a.sub.2), of at least one vinylaromatic monomer, (a.sub.22) 5 to 35 wt.-%, based on (a.sub.2), of acrylonitrile and/or methacrylonitrile, and (a.sub.23) 0 to 20 wt.-%, based on (a.sub.2), of at least one monomer selected from the group consisting of C.sub.1-C.sub.4-alkyl(meth)acrylates, maleic anhydride, N-phenyl maleimide, N-cyclohexyl maleimide, and (meth)acrylamide; (B) 50 to 75 wt.-% of at least one copolymer B made from: (b.sub.1) 50 to 95 wt.-%, based on (B), of at least one vinylaromatic monomer, (b.sub.2) 5 to 50 wt.-%, based on (B), of acrylonitrile and/or methacrylonitrile, and (b.sub.3) 0 to 20 wt.-%, based on (B), of one or more of the monomers as described for (a.sub.23); (C) 4 to 20 wt.-% of at least one copolymer C made from (c.sub.1) 70 to 91 wt.-%, based on (C), of ethylene, (c.sub.2) 9 to 30 wt.-%, based on (C), at least one C.sub.1-C.sub.6-alkyl(meth)acrylate, and (c.sub.3) 0 to 15 wt.-%, based on (C), of at least one further comonomers copolymerizable with (c.sub.1) and (c.sub.2); and (D) 4 to 20 wt.-% of at least one graft rubber copolymer D obtained by mass polymerization and built up from: (d.sub.1) 10 to 25 wt.-%, based on (D), of at least one graft base (d.sub.1) made from: (d.sub.11) 75 to 100 wt.-%, based on (d.sub.1), of at least one diene, and (d.sub.12) 0 to 25 wt.-%, based on (d.sub.1), of at least one vinylaromatic monomer, and (d.sub.2) 75 to 90 wt.-%, based on (D), of a graft (d.sub.2), grafted onto the graft base and built up from: (d.sub.21) 68 to 82 wt.-%, based on (d.sub.2), of at least one vinylaromatic monomer, (d.sub.22) 18 to 32 wt.-%, based on (d.sub.2), of acrylonitrile or methacrylonitrile, and (d.sub.23) 0 to 20 wt.-%, based on (d.sub.2), of one or more of the monomers as described for (a.sub.23); wherein the sum of components A, B, C, and D totals 100 wt.-%.

2. The method according to claim 1, wherein the thermoplastic molding composition further comprises 0.01 to 20 parts by weight of at least one further additive and/or processing aid F, based on 100 parts by weight of the composition consisting of components A, B, C, and D.

3. The method according to claim 1, wherein the thermoplastic molding composition further comprises 0.01 to 10 parts by weight of at least one inorganic additive E selected from phyllosilicates (E1) and nano calcium carbonate (E2), based on 100 parts by weight of the composition consisting of components A, B, C, and D.

4. The method according to claim 1, wherein the thermoplastic molding composition comprises components A, B, C, and D in the following amounts: (A): 18 to 28 wt.-%; (B): 55 to 70 wt.-%; (C): 6 to 15 wt.-%; and (D): 6 to 15 wt.-%.

5. The method according to claim 1, wherein graft rubber copolymer A is built up from: (a.sub.1) 40 to 90 wt.-% of at least one graft base (a.sub.1) made from: (a.sub.11) 80 to 98 wt.-% of at least one diene (a.sub.11), and (a.sub.12) 2 to 20 wt.-% of at least one monomer (a.sub.12), and (a.sub.2) 10 to 60 wt.-% of a graft (a.sub.2), grafted onto the graft base (a.sub.1) and built up from: (a.sub.21) 65 to 80 wt.-% of at least one vinylaromatic monomer (a.sub.21), (a.sub.22) 20 to 35 wt.-% of acrylonitrile and/or methacrylonitrile (a.sub.22), and (a.sub.23) 0 to 20 wt.-% of at least one monomer (a.sub.23).

6. The method according to claim 1, wherein copolymer B is made from: (b.sub.1) 60 to 82 wt.-% of styrene or α-methylstyrene, and (b.sub.2) 18 to 40 wt.-% of acrylonitrile.

7. The method according to claim 1, wherein copolymer C has a weight average molar mass M.sub.w of less than 1,000,000 g/mol.

8. The method according to claim 1, wherein copolymer C has a MFR of from 0.5-50 [g/10 min] (190° C./2.16 kg load, according to ASTM D1238; ISO 1133-1:2011).

9. The method according to claim 1, wherein copolymer C is an ethylene methylacrylate copolymer.

10. The method according to claim 1, wherein graft copolymer D is built up from: (d.sub.1) 12 to 20 wt.-% of a graft base (d.sub.1) made from: (d.sub.11) 75 to 100 wt.-% of 1,3-butadiene, and (d.sub.12) 0 to 25 wt.-% of styrene, and (d.sub.2) 80 to 88 wt.-% of a graft (d.sub.2), grafted onto the graft base and built up from: (d.sub.21) 68 to 82 wt.-%, based on (d.sub.2), of styrene, and (d.sub.22) 18 to 32 wt.-%, based on (d.sub.2), of acrylonitrile.

11. The method according to claim 3, wherein component E1 is present in an amount of from 0.01 to 5 parts by weight, based on 100 parts by weight of the composition consisting of components A, B, C, and D.

12. The method according to claim 3, wherein component E2 is present in an amount of from 0.01 to 10 parts by weight, based on 100 parts by weight of the composition consisting of components A, B, C, and D.

13. The method according to claim 1, wherein the thermoplastic molding composition is formed into the shaped articles by extrusion or co-extrusion.

14. The method according to claim 1, wherein the shaped article is an inliner in cooling apparatuses.

15. A thermoplastic molding composition as defined in claim 1.

16. The thermoplastic molding composition according to claim 15, comprising components A, B, C, and D in the following amounts: (A): 18 to 28 wt.-%; (B): 55 to 70 wt.-%; (C): 6 to 15 wt.-%; and (D): 6 to 15 wt.-%.

Description

EXAMPLES

Graft Rubber Copolymer A

Preparation of the Graft Base a.SUB.1

(1) The particulate cross-linked fine-particle rubber base used for the preparation of component A (emulsion graft rubber copolymer) was prepared by radical emulsion polymerization of butadiene and styrene (monomer weight ratio 90/10) in the presence of distilled tallow fatty acid (CAS-No. 67701-06-8, C14-C18-saturated and C15-C18-unsaturated straight chain aliphatic monocarboxylic acid), tert-dodecylmercaptan as chain transfer agent, potassium persulfate as initiator at temperatures from 60° to 85° C. As salt tetrasodium pyrophosphate is used.

(2) The addition of initiator marked the beginning of the polymerization. Finally the fine-particle butadiene rubber latexes are cooled below 50° C. and the non-reacted monomers were removed partially under vacuum (200 to 500 mbar) at temperatures below 50° C. which defines the end of the polymerization.

(3) The starting styrene/butadiene-rubber (SBR) rubber base so obtained has solid content of 41 wt.-%, a rubber gel content of 93% (wire cage method in toluene), a rubber composition comprising units derived from styrene and butadiene in a weight ratio of 10/90 and a weight-average particle size of 0.08 μm (determined via Differential Centrifugation using a disc centrifuge from CPS Instruments). The starting SBR was subjected to particle size enlargement with acetic anhydride in two batches to a weight-average particle size D.sub.w of 0.25 μm and 0.55 μm, respectively.

(4) In order to achieve agglomerated butadiene rubber latices with D.sub.w of 0.25 μm, the fine-particle butadiene rubber latexes are being provided first at 25° C. and are adjusted if necessary with deionized water to a concentration of 36 wt.-% and stirred. The temperature was raised to 40° C. To this dispersion, 1.3 weight parts of acetic anhydride based on 100 parts of the solids from the fine-particle butadiene rubber latex as aqueous mixture is added and mixed with the latex. After this the agglomeration is carried out for 10 minutes without stirring.

(5) Anionic dispersant of sulfonic polyelectrolyte type (Sodium naphthalene sulfonate formaldehyde condensates, CAS 9084-06-04) are added as aqueous solution to the agglomerated latex and mixed by stirring. Subsequently KOH are added as aqueous solution to the agglomerated latex and mixed by stirring. The solid content of the agglomerated butadiene rubber latex with D.sub.w of 0.25 μm is 28.5 wt.-%.

(6) In order to achieve agglomerated butadiene rubber latices with D.sub.w of 0.55 μm, the fine-particle butadiene rubber latices are being provided first at 25° C. and are adjusted if necessary with deionized water to a concentration of 33 wt. % and stirred. To this dispersion, 2 weight parts of acetic anhydride based on 100 parts of the solids from the fine-particle butadiene rubber latex as aqueous mixture is added and mixed with the latex. After this the agglomeration is carried out for 30 minutes without stirring. Anionic dispersant of sulfonic polyelectrolyte type (Sodium naphthalene sulfonate formaldehyde condensates, CAS 9084-06-04) are added as aqueous solution to the agglomerated latex and mixed by stirring. Subsequently KOH are added as aqueous solution to the agglomerated latex and mixed by stirring. The solid content of the agglomerated butadiene rubber latex with D.sub.w of 0.55 μm is 24.7 wt.-%. The two latexes with 0.25 μm (80 pts.) and 0.55 μm (20 pts.) were combined to rubber base a1 which is used in the further reaction step in form of polymer latexes which have solids content of 26 wt.-%.

Preparation of the Graft Rubber Copolymer A

(7) The graft copolymer A is prepared (as parts by weight) from 52 styrene/butadiene-rubber (SBR), 34 styrene, 14 acrylonitrile, together with cumene hydroperoxide, dextrose, ferrous sulfate, t-dodecylmercaptane, disproportionated potassium rosinate soap, and emulsion graft polymerization was conducted. Firstly, the afore-mentioned SBR latex a.sub.1 was charged, and the temperature was raised to 70° C. Styrene, acrylonitrile, t-dodecylmercaptane, disproportionated potassium rosinate soap and deionized water were added. At 70° C., the catalyst solution (sodium pyrophosphate, dextrose, cumene hydroperoxide and ferrous sulfate dissolved in water) was added. After completion of the addition, the stirring was continued for further 30 minutes, and then the mixture was cooled. To the graft copolymer latex thus obtained, an aging-preventive agent (e.g. Antioxidant PL/Wingstay L, Phenol, 4-methyl-, reaction products with dicyclopentadiene and isobutene, CAS-No. 68610-51-5) was added, and the mixture was added under stirring to an aqueous magnesium sulfate solution heated to 95° C., for coagulation. The coagulated product was washed with water and dried to obtain a high rubber content resin composition in the form of a white powder.

Preparation of the Matrix Copolymer B

(8) Statistical SAN-copolymer B1 was produced by suspension polymerization from 72 wt.-% styrene and 28 wt.-% acrylonitrile with a weight average molar mass of 230,000 kg/mol (determined by gel permeation chromatography and using polystyrene for calibration) and MVR of 3.5 cm.sup.3/10 min (220° C./10 kg load (ISO 1133-1:2011)).

(9) Statistical SAN-copolymer B2 was produced by suspension polymerization from 66 wt.-% styrene and 34 wt.-% acrylonitrile with a weight average molar mass of 89,000 kg/mol (determined by gel permeation chromatography and using polystyrene for calibration) and MVR of 75 cm.sup.3/10 min (220° C./10 kg load (ISO 1133-1:2011)).

(10) Statistical SAN-copolymer B3 was produced by suspension polymerization from 66 wt.-% styrene and 34 wt.-% acrylonitrile with a weight average molar mass of 180,000 kg/mol (determined by gel permeation chromatography and using polystyrene for calibration) and MVR of 3 cm.sup.3/10 min (220° C./10 kg load (ISO 1133-1:2011)).

(11) Statistical SAN-copolymer B4 was produced by mass polymerization from 69 wt.-% styrene and 31 wt.-% acrylonitrile with a weight average molar mass of 140,000 kg/mol (determined by gel permeation chromatography and using polystyrene for calibration) and MVR of 19 cm.sup.3/10 min (220° C./10 kg load (ISO 1133-1:2011)).

(12) Statistical SAN-copolymer B5 was produced by suspension polymerization from 69 wt.-% styrene and 31 wt.-% acrylonitrile with a weight average molar mass of 200,000 kg/mol (determined by gel permeation chromatography and using polystyrene for calibration) and MVR of 4 cm.sup.3/10 min (220° C./10 kg load (ISO 1133-1:2011)).

Preparation of Graft Rubber Copolymer D (mABS)

(13) Continuous mass ABS copolymer D was produced by free-radical solution polymerization from 17% butadiene, 63% styrene, 20% acrylonitrile by weight in the presence of methylethyl ketone with a gel content of 30% (acetone method), a weight average particle size of the grafted rubber of 0.6 to 1 μm (determined via Differential Centrifugation using a disc centrifuge from CPS Instruments) and a MVR of 5.5 cm.sup.3/10 min (ISO 1133-1:2011).

(14) The gel content was determined in acetone or toluene as dispersant. Approximately, 0.25 g of the polymer composition were dispersed in 20 g of dispersant for 12-24 h and separated with an ultracentrifuge at 20,000 rpm at 25° C. into the gel and sol phase. The separated phases were dried and the gel content is calculated by the following formula:
gel=mass(gel phase)/(mass(gel phase)+mass(sol phase))*100[%]

Preparation of the Thermoplastic Molding Compositions

(15) In the following examples and comparative examples, the afore-mentioned copolymers A, B and D and the following components C and F were used in the amounts as given in Table 1. The additives and processing aids (component F) were added to 100 parts by weight (pbw.) of the polymer components as listed in Table 1 (left column).

(16) Component C: Elvaloy® AC 1224: a copolymer of ethylene and methyl acrylate containing 24% by weight methyl acrylate, produced by DuPont; melt flow rate (190° C./2.16 kg) 2.0 g/10 min (ISO 1133/ASTM D1238), density 0.944 g/cm.sup.3 (ASTM D792/ISO 1183), melting point by DSC 91° C. (ISO 3146/ASTM D3418), Vicat Softening Point 48° C. (ASTM D1525/ISO 306).

(17) F1: Ethylene bis stearamide, CAS-No. 110-30-5

(18) F2: Silicone oil, 60,000 cSt, polydimethylsiloxane, CAS-No. 63148-62-9

(19) F3: Thiosynergic heat stabilizer, 3,3′-thiodipropionic acid dioctadecylester, CAS-No. 693-36-7

(20) F4: Phenolic primary antioxidant, octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate, CAS-No. 2082-79-3

(21) F5: Titanium dioxide CAS-No. 13463-67-7

(22) The components A, B, C and D according to Table 1 and the afore-mentioned additives and processing aids F were compounded under the following conditions: Extruder Machine L/D: 30, diameter: 40 mm, co-rotating twin screw, manufacture: KraussMaffei Berstorff, Germany, die head and melt temp: 250° C., throughput: 50˜60 kg/h.

(23) The thermoplastic compositions were tested using the following methods:

(24) Notched Charpy impact strength [kJ/m2]:

(25) The notched Charpy impact strength is measured on test specimen (80×10×4 mm, injection molded at a mass temperature of 240° C. and a mold temperature of 70° C.), at 23° C. according to ISO 179-1A.

(26) Notched Izod impact strength [kJ/m.sup.2]:

(27) The notched Izod impact strength [kJ/m.sup.2] is measured on test specimen (80×10×4 mm, injection molded at a mass temperature of 240° C. and a mold temperature of 70° C.), at 23° C. according to ISO 180-1A.

(28) Melt volume index (MVR [ml/10 min]):

(29) The melt volume rate MVR is measured on a polymer melt at 220° C. and 10 kg load according to ISO 1133.

(30) Tensile strain at break [%]:

(31) The tensile strain at break [%] is measured on Dumbbell test specimen 170×10×4 mm (injection molded at a mass temperature of 240° C. and a mold temperature of 70° C.) at 23° C. according to DIN EN ISO 527.

(32) ESCR method:

(33) After compounding, the obtained thermoplastic compositions were injection molded into test bars with the dimension 80×10×4 mm under following conditions: Clamping force: 120 MT, manufacturer: Dongshing, Korea, injection temperature: 240° C., Injection speed: 60%, cycle time: 45 sec, mold temp: 60° C. The molded bars were tested in regard to their chemical resistance according to the following environmental stress crack resistance (ESCR) test:

(34) Injection molded test bars (80×10×4 mm) are mounted on a jig which maintains constant curvature at 2.5% outer fiber strain. The jig with the test pieces is placed into a jar filled with the chemical agent in a way that the test bars are completely covered. During the experiment, the proceeding degradation is monitored and reviewed in dependence of time. After allowing the test pieces to stand in the prescribed environmental conditions for a specific period of time (in normal case 300 min or till complete crack) and removing them from the jig, the condition of physical degradation is checked.

(35) The determination of chemical resistance was done optically in dependence of the following criteria: complete crack, partial crack, surface crack, edge crack, and surface quality after aging.

(36) A summary (cp. Table 2) is then given by the following symbols: X: degraded .box-tangle-solidup.: highly affected .box-tangle-solidup..box-tangle-solidup.: affected .box-tangle-solidup..box-tangle-solidup..box-tangle-solidup.: a little affected .box-tangle-solidup..box-tangle-solidup..box-tangle-solidup..box-tangle-solidup.: not affected (.box-tangle-solidup.): 0.5 .box-tangle-solidup.

(37) Table 1 describes the components of the thermoplastic compositions.

(38) To better compare different materials also a ranking (cp. Table 2) is given (1=material with highest chemical resistance of all tested materials, 2=material with second highest chemical resistance of all tested materials, etc.).

(39) Common chemicals for testing like cyclopentane were applied at room temperature. In case of trans-1-chloro-3,3,3-trifluoropropene (b.p. 19° C.) the tests were done at 0° C. to prevent evaporation of the agent while maintaining constant test conditions.

(40) By comparison of the thermoplastic compositions according to the inventive examples 1 and 2 to the thermoplastic compositions of comparative examples Cp. 1 and Cp. 2, known from the prior art, it is found that the thermoplastic molding compositions according to inventive examples 1 and 2 show superior ESCR behavior during the applied test. Inventive example 1 does not only show very good resistance against trans-1-chloro-3,3,3-trifluoropropene but also superior resistance against cyclopentane. This is important since manufacturers use mixtures of blowing agents for their applications in most cases.

(41) The chemical resistance against both tested blowing agents of the thermoplastic composition according to inventive example 2 is extremely good.

(42) Additionally, inventive examples 1 and 2 both show the favorable properties known for ABS materials; good processability (MVR, elongation at break) and toughness (impact strength).

(43) TABLE-US-00001 TABLE 1 Thermoplastic compositions Composition SAN-copolymer (B) graft mABS Elvaloy AN (IR, MVR 220/10 Additives (F) ABS (A) (D) (C) average) [cm.sup.3/10 min] F1 F2 F3 F4 F5 No. Components parts parts parts parts [%] (average) parts parts parts parts parts Cp. 1 (A) + (B) 29 71 (9 B1 + 40 32 18.3 1 0.25 0.25 0.5 7.8 B3 + 22 B4) 1 (A) + (B) + (C) 23 10 67 (53 B1 + 29 6.7 1 0.25 0.5 0.5 5.5 14 B4) Cp. 2 (A) + (B) + (D) 20 20 60 (60 B5) 31 4.1 3 0.2 0.5 0.5 5.5 2 (A) + (B) + 20 10 10 60 (60 B5) 31 4.1 3 0.2 0.5 0.5 5.5 (C) + (D)

(44) TABLE-US-00002 TABLE 2 ESCR results and mechanical data ESCR test results Mechanical data Composition trans-1- notched notched MVR graft SAN-co- chloro-3,3,3- IZOD Charpy Elonga- (220° C., ABS mABS Elvaloy polymer Cyclopentane trifluoropropene Impact Impact tion at 10 kg) Com- (A) (D) (C) (B) chemical rank- chemical rank- strength strength break [ml/ No. ponents parts parts parts parts resistance ing resistance ing [kJ/m.sup.2] [kJ/m.sup.2] [%] 10 min] Cp. 1 (A) + (B) 29 71 .box-tangle-solidup. .box-tangle-solidup. .box-tangle-solidup. (.box-tangle-solidup.) 2 .box-tangle-solidup. .box-tangle-solidup. 3 31.8 26.4 24.8 4.4 1 (A) + 23 10 67 .box-tangle-solidup. .box-tangle-solidup. .box-tangle-solidup. .box-tangle-solidup. 1 .box-tangle-solidup. .box-tangle-solidup. .box-tangle-solidup. 2 35.2 — 50.0 5.0 (B) + (C) Cp. 2 (A) + 20 20 60 .box-tangle-solidup. .box-tangle-solidup. .box-tangle-solidup. (.box-tangle-solidup.) 2 .box-tangle-solidup. .box-tangle-solidup. .box-tangle-solidup. 2 37.4 26.7 53.1 5.0 (B) + (D) 2 (A) + (B) + 20 10 10 60 .box-tangle-solidup. .box-tangle-solidup. .box-tangle-solidup. .box-tangle-solidup. 1 .box-tangle-solidup. .box-tangle-solidup. .box-tangle-solidup. (.box-tangle-solidup.) 1 38.1 33.9 64.0 7.7 (C) + (D)