KR20050018964A - Thermoplastic Polycarbonate Compositions Having High Toughness - Google Patents

Abstract

Thermoplastic molding compositions are disclosed which feature improved low temperature properties and are therefore suitable for automotive exterior parts. This composition

(A) 80% to 60% copolycarbonate derived from 65 mol% to 75 mol% of the structural unit and 25 mol% to 35 mol% of the structural unit is derived from the compound of formula II %, And

(B) containing 20% to 40% homopolycarbonate of bisphenol A having a melt flow rate of 3 g / 10 min to 12 g / 10 min measured according to ASTM D-1238 under a load of 1.2 kg at 300 ° C. do.

<Formula I>

<Formula II>

Wherein R ¹ , R ² , R ³ and R ⁴ are independently of each other H, C ₁ -C ₄ -alkyl, phenyl, substituted phenyl or halogen, and R ⁵ , R ⁶ , R ⁷ and R ⁸ are Independently H, CH ₃ , Cl or Br and X is C ₁ -C ₅ -alkylene, C ₂ -C ₅ -alkylidene, C ₅ -C ₆ -cycloalkylene or C ₅ -C ₁₀ -cycloalkyl Leeden.

Description

Thermoplastic Polycarbonate Compositions Having High Toughness

The present invention relates to thermoplastic compositions, more specifically to polycarbonate compositions having high impact strength at low temperatures.

Summary of the Invention

Thermoplastic molding compositions are disclosed that are suitable for making articles in which good properties are combined. This composition is based on the weight of the following (A) and (B)

(A) 80% to 60% copolycarbonate derived from 65 mol% to 75 mol% of the structural unit and 25 mol% to 35 mol% of the structural unit is derived from the compound of formula II %, And

(B) containing 20% to 40% homopolycarbonate of bisphenol A having a melt flow rate of 3 g / 10 min to 12 g / 10 min measured according to ASTM D-1238 under a load of 1.2 kg at 300 ° C. do.

Wherein R ¹ to R ⁴ are independently of each other H, C ₁ -C ₄ -alkyl, phenyl, substituted phenyl or halogen, R ⁵ to R ⁸ are independently of each other H, CH ₃ , Cl or Br, X is C ₁ -C ₅ -alkylene, C ₂ -C ₅ -alkylidene, C ₅ -C ₆ -cycloalkylene or C ₅ -C ₁₀ -cycloalkylidene.

There has been a long need for transparent thermally stable polycarbonates which are characterized by improved chemical resistance and superior impact strength at low temperatures compared to conventional bisphenol-A based homopolycarbonates.

Copolycarbonates based on 4,4'-dihydroxydiphenyl (hereinafter "DOD") and 2,2-bis (4-hydroxyphenyl) propane are described in Japanese Patent No. 51,172, European Patent No. 544 407, US Pat. No. 5,470,938, 5,532,324 and 5,401,826. The copolycarbonates are disclosed to have the same mechanical properties and transparency as commercially available homopolycarbonates of bisphenol A, while at the same time being chemical and heat resistant and flame retardant.

German Patent 10047483.7 discloses copolycarbonates of 4,4'-dihydroxydiphenyl and 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), which exhibit particularly good low temperature properties. . However, as the content of 4,4'-dihydroxydiphenyl is lowered, good low temperature properties are described as decreasing. Since 4,4'-dihydroxydiphenyl is an expensive component compared to 2,2-bis (4-hydroxyphenyl) -propane, 4,4'-dihydrate is without losing the desired improvement in low temperature strength. It is desirable in terms of cost to keep the oxy-diphenyl content as low as possible.

A pending patent application (attorney's case number Mo-7146) discloses blends containing copolycarbonates of DOD and homopolycarbonates of bisphenol A that exhibit highly desirable properties.

There is a need for materials suitable for applications requiring low temperature impact strength. Impact strength is measured by notched Izod and multi-axis impact strength. The prior art did not recognize that the multiaxial impact strength at low temperatures was critically dependent on the melt flow rate of the homopolycarbonate component, which was not found until the present invention. It has also been found that not all of the blends disclosed above are equivalent to each other and that the compositions within the limited defined range exhibit unexpected surprising properties.

Therefore, the present invention

Based on the total weight of (A) and (B)

(A) 65 mol% to 75 mol% of the structural unit, preferably 68 mol% to 73 mol% is derived from the compound of formula (I) and 25 mol% to 35 mol%, preferably 27 mol% of the structural unit 80% to 60%, preferably 65% to 75% of the copolycarbonate derived from the compound of formula II

(B) homopolycarbonates of bisphenol A with a melt flow rate (hereinafter referred to as "MRF") measured according to ASTM D-1238 under a load of 1.2 kg at 300 ° C. It relates to a thermoplastic molding composition containing 20% to 40%, preferably 25% to 35%.

<Formula I>

<Formula II>

Wherein R ¹ , R ² , R ³ and R ⁴ independently of one another are H, C ₁ -C ₄ -alkyl, phenyl, substituted phenyl or halogen, preferably H, C ₁ -C ₄ -alkyl or halogen And particularly preferably all are the same radicals, in particular H or tert-butyl, R ⁵ , R ⁶ , R ⁷ and R ⁸ are independently of each other H, CH ₃ , Cl or Br and X is C ₁ -C ₅ -alkylene, C ₂ -C ₅ -alkylidene, C ₅ -C ₆ -cycloalkylene or C ₅ -C ₁₀ -cycloalkylidene.

Surprisingly, the polycarbonate blends according to the invention have been found to have good low temperature properties, including notched Izod and multiaxial impact strength.

The composition of the present invention is useful for producing molded articles having insufficient property profiles of conventional polycarbonates and copolycarbonates. The compositions of the present invention are specifically for the electrical and architectural sectors, including glazing, and especially for the automotive sector, and for the production of films, sheets, fittings or housing parts that require thermal dimensional stability, chemical resistance and good low temperature properties. Applicable to

According to the invention, it is understood that the low temperature is a temperature below 0 ° C, particularly preferably below -10 ° C and most particularly preferably below -30 ° C.

Suitable compounds of formula I include 4,4'-dihydroxydiphenyl (DOD) and 4,4'-dihydroxy-3,3 ', 5,5'-tetra (tert-butyl) diphenyl, 4 , 4'-dihydroxy-3,3 ', 5,5'-tetra (n-butyl) diphenyl and 4,4'-dihydroxy-3,3', 5,5'-tetra (methyl) -Diphenyl is mentioned. 4,4'-dihydroxydiphenyl is particularly preferred.

Suitable compounds of formula II are 2,2-bis (4-hydroxyphenyl) -propane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane and 1,3-bis [ 2- (4-hydroxyphenyl) -2-propyl] benzene, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1-bis (4-hydroxyphenyl) -cyclohexane, Especially 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane (bisphenol TMC). Especially preferred is 2,2-bis (4-hydroxyphenyl) propane (bisphenol A).

Copolycarbonates (A) may be derived from at least one compound of formula (I) and at least one compound of formula (II).

Processes for preparing (co) polycarbonates are known.

The production of polycarbonates by interfacial processes or melt transesterification processes is known. In this regard, see "Schnell", Chemistry and Physics of Polycarbonates, Polymer Reviews, Vol. 9, Interscience Publishers, New York, London, Sydney, 1964, p. 33 ff and to Polymer Reviews, Volume 10, "Condensation Polymers by Interfacial and Solution Methods", Paul W. Morgan, Interscience Publishers, New York 1965, Chap. VIII, p. 325.

In general, the preparation of copolycarbonates comprising a compound of formula (I) is preferably carried out in solution, ie by an interfacial process or a process in a homogeneous phase. Production by a melt transesterification process is also possible, for example described in DE-A 19 64 6401 or DE-A 1 42 38 123. In addition, the transesterification process is described in U.S. Pat. Nos. 3,494,885, 4,386,186, 4,661,580, 4,680,371 and 4,680,372, all of which are incorporated herein by reference, and European Patent 26120, 26121. , No. 26684, No. 28030, No. 39845, No. 91602, No. 97970, No. 79575, No. 146887, No. 156103, No. 234913, No. 240301 And in German patents 1495626 and 2222377.

The polycarbonates and copolycarbonates according to the invention preferably contain structural units derived from any of the various chain terminators. Suitable chain terminators include those according to formula III.

Wherein R, R 'and R''are each independently of each other H, optionally branched C ₁ -C ₃₄ -alkyl or cycloalkyl, C ₇ -C ₃₄ -alkaryl or C ₆ -C ₃₄ -aryl . Preferred chain terminators include butylphenol, tritylphenol, cumylphenol, phenol and octylphenol. Most preferred are butylphenol and phenol. The chain terminators used in the preparation of the copolycarbonates (A) may be the same or different than those used in the preparation of the polycarbonates (B).

Each component (A) and (B) may independently contain a small amount of branching agent from 0.02 mol% to 3.6 mol% (based on the dihydroxy compound). Suitable branching agents are compounds having three or more functional groups, preferably compounds having three or more phenolic OH groups, for example 1,1,1-tri- (4-hydroxyphenyl) ethane and isatin Biscresol.

In order to change the properties of the compositions of the invention, additives, fillers and / or reinforcing agents may be incorporated. These include heat stabilizers, UV stabilizers, rheology modifiers, mold release agents, flame retardants, pigments, fine minerals, fibrous materials, flame retardant materials such as alkyl and aryl phosphites, phosphates, phosphates, low molecular weight carboxylic acid esters, Halogenated compounds, salts, chalk, quartz powders, glass fibers and carbon fibers, pigments and combinations thereof. Such compounds, which are known in the art for the effect of imparting particular effects or properties to thermoplastic polycarbonate compositions, are known and are described herein by "Plastics Additives", R. Gaechter and H. Mueller, Hanser. Publishers, 1983.

Other polymers such as polyolefins, polyurethanes, polyesters, acrylonitrile-butadiene-styrenes and polystyrenes may also be blended with the components of the compositions of the present invention.

Such materials can be added to the compositions of the present invention by conventional means and by the following conventional procedures.

Components (A) and (B) are 10,000 to 60,000 as determined at room temperature by relative solution viscosity (0.5 wt% solution) in dichloromethane or a mixture of equivalent weights of phenol / o-dichlorobenzene, measured by light scattering. And preferably has a weight average molecular weight of 20,000 to 55,000.

The polycarbonate blends according to the invention can be treated with thermoplastics at temperatures of typically 240 ° C. to 380 ° C., preferably 260 ° C. to 360 ° C. Molded articles and films of any kind can be produced in a known manner by injection molding or extrusion methods. The present application also relates to molded articles and extrudates made from the compositions of the present invention.

The compositions of the present invention can be readily dissolved in solvents such as chlorinated hydrocarbons, for example methylene chloride, and thus can be processed into cast films, for example, in known manner.

The following examples are intended to illustrate the invention and are not intended to limit the invention.

Component (A), which is a copolycarbonate containing 30 mol% dihydroxydiphenyl (DOD) and 70 mol% bisphenol A, was prepared. tert-butylphenol was used as chain terminator. The particles have a relative solution viscosity of 1.30.

Bisphenol A based homopolycarbonate having the indicated melt flow rate (MFR) was used as component (B) and also used in Comparative Examples.

The compositions exemplified contained conventional flame retardants, UV stabilizers and pigments that are not considered important to the discovery of the present invention. Impact performance at −30 ° C. and −40 ° C. was determined by notched Izod impact strength and set (multiaxial) impact strength at 1/8 inch thickness. 3 in. For disc-shaped specimens 4 inches in diameter. Multiaxial impact tests were performed at a speed of 15 mph using a window and a 1/2 inch radius of dart.

Preparation of the composition was conventionally carried out. The test results are summarized in Table 1 below.

"Component A" shown was copolycarbonate of 30 mol% DOD and 70 mol% bisphenol A (BPA).

The "homopolycarbonate" shown was a BPA-based homopolycarbonate. Melt flow rate MFR is measured in g / 10 min as measured according to ASTM D-1238 under a load of 1.2 kg at 300 ° C. The amount of components is weight percent relative to the composition.

The composition further contained conventional flame retardant materials, UV stabilizers and pigments unrelated to the findings of the present invention.

Example A B C D Component A 80 70 60 70 Homopolycarbonate, MFR = 4.7 20 30 40 0 Homopolycarbonate, MFR = 13.1 0 0 0 30 MFR of the composition 8.2 8 7 9.9 Notched Izod (ft-lbs / in): At -30 ℃ 6.2 7.3 8.7 5.4 At -40 ℃ 5.7 4.2 3.7 4.8 Multi-Axis Impact Strength (ft-lb): At -30 ℃ 37.4 36.2 40.3 42.8 At -40 ℃ 41 42.2 45.4 39.8 Failure mode ductility ductility ductility Ductile / brittle

The results presented above indicate the importance of MFR of homopolycarbonates in the present invention.

Example D exhibited an undesirable failure mode in the low temperature test.

In a further series of experiments, the composition contained homopolycarbonates of BPA with MFR of 4.7 as "Component A" and Component "B" as above. The results are shown in Table 2. The composition further contained white pigments that were not critical to the discovery of the present invention.

Example A B C Pigment One One One Homopolycarbonate of BPA, MFR = 4.7 99 0 30 Component A 0 99 69 MFR of the composition 5.3 8.8 7.5 Notched Izod (ft-lbs / in): At -30 ℃ 6.4 7.7 11.5 At -40 ℃ 2.9 ¹ 7.1 10.1 Multi-Axis Impact Strength (ft-lb): At -30 ℃ 44.8 36.1 ² 38.4 At -40 ℃ 47.7 33.3 ³ 39.3 ¹ -All five specimens tested fail in brittle mode ² -One of five specimens tested fails in brittle mode ³ - ^Three of five specimens tested fail in brittle mode

The results show improved surprising impact performance of the compositions of the present invention at both low temperature notched Izod impact strength and multiaxial impact strength. In comparison, Component B (Example A), which is a polycarbonate resin, exhibits poor notched Izod and shows good performance in the multi-axis impact test. On the other hand, component A alone (Example B), which is a copolycarbonate of DOD, shows good Izod impact strength but poor performance in multi-axis impact tests. The composition according to the invention (Example C) exhibits a higher Notched Izod value at low temperatures than when each component is used alone, and exhibits a ductile failure mode with a median multiaxial impact strength.

While the invention has been described in detail above for purposes of illustration, such details are for purposes of illustration only and modifications of the invention may be made by those skilled in the art without departing from the spirit and scope of the invention, except as may be limited by the claims. I think I can.

Claims (7)

Based on the total weight of (A) and (B) (A) 65 mol% to 75 mol% of the structural unit is derived from the compound of formula (I) and 25 mol% to 35 mol% of the structural unit is from 80% to 60 copolycarbonate derived from the compound of formula (II) %, And (B) 20% to 40% homopolycarbonate of bisphenol A having a melt flow rate of 3 g / 10 minutes to 12 g / 10 minutes as measured according to ASTM D-1238 under a load of 1.2 kg at 300 ° C. Thermoplastic molding composition. <Formula I> <Formula II> Wherein R ¹ , R ² , R ³ and R ⁴ are independently of each other H, C ₁ -C ₄ -alkyl, phenyl, substituted phenyl or halogen, and R ⁵ , R ⁶ , R ⁷ and R ⁸ are Independently H, CH ₃ , Cl or Br and X is C ₁ -C ₅ -alkylene, C ₂ -C ₅ -alkylidene, C ₅ -C ₆ -cycloalkylene or C ₅ -C ₁₀ -cycloalkyl Leeden. The thermoplastic molding composition of claim 1 comprising (A) 65% to 75% and (B) 25% to 35%. The thermoplastic molding composition of claim 1, wherein 68 mol% to 73 mol% of the structural units of (A) are derived from a compound of formula (I). The thermoplastic molding composition of claim ¹ , wherein R ¹ , R ² , R ³ and R ⁴ are independently of each other H, C ₁ -C ₄ -alkyl or halogen. The thermoplastic molding composition of claim ¹ , wherein R ¹ , R ² , R ³ and R ⁴ are the same and are H or tert-butyl. The thermoplastic molding composition of claim 1, wherein the compound of formula I is dihydroxydiphenyl and the compound of formula II is bisphenol A. 3. A molded article comprising the thermoplastic molding composition of claim 1.