MXPA98006973A - A procedure to prepare a copolicarbon - Google Patents

Abstract

The present invention relates to a process for preparing a copolymer resin, which comprises introducing component (a) and component (b) in an extruder under conditions designed to promote the reactive mixture between them in the presence of a transesterification catalyst, wherein said component (a) is a wet aromatic polycarbonate resin containing moisture in an amount greater than 0.02 percent relative to its weight and having units that conform to where D is a divalent residue of a dihydroxy compound and wherein said component (b) is a lactone-siloxane block copolymer having structural units that conform to: wherein m is 1-90, n is 60-150, R is an alkyl or phenyl radical, p is 2-12 and q is 2 -

Description

A PROCEDURE FOR PREPARING A COPOLICARBONATE Field of the Invention The invention relates to a process for preparing a thermoplastic molding composition and, more specifically, to a reactive mixing process including a polycarbonate and a caprolactone-co-siloxane. COMPENDIUM OF THE INVENTION A process for preparing a copolymer resin is described. Accordingly, component (a) and component (b) are introduced into an extruder under conditions designed to promote reactive mixing therebetween in the presence of a trans-esterification catalyst. Component (a) is a wet aromatic polycarbonate resin that contains moisture in an amount greater than 0.02 percent by weight and has units that conform to where D is a divalent residue of a dihydroxy compound. Component (b) is a lactone-siloxane block copolymer having structural units that conform to where m is 1-90, n is 60-150, R is an alkyl or phenyl radical, p is 2-12 and q is 2-20. Surprisingly, the use of a polycarbonate containing moisture in the process results in a copolymer having good properties, although a corresponding process in which the reactive lactone-siloxane block copolymer has a lower number of repeating units gives a lower product. BACKGROUND OF THE INVENTION Polycarbonate resins are well-known thermoplastic resins that have been used for a long time in a variety of applications requiring impact resistance. At low temperatures, generally below 20 ° C, the polycarbonate becomes brittle and its usefulness is, therefore, limited by this drawback. It is known that the low temperature impact resistance of polycarbonate can be improved by introducing (by copolymerization) silicone blocks into the carbonate structure. The US Patents 3,189,662, 3,419,634, 4,123,588, 4,569,970, 4,920,183 and 5,068,032 are cited for their descriptions of relevant copolymers. Relevant copolymers have been prepared according to a melt mixing process described in US Pat. 4,994,532. The process involves the melt blending of an aromatic polycarbonate resin and a poly-organo-organosiloxane having at least one functional carboxylic acid group. The US patent is also relevant in the present context. No. 4,657,989, which described a method of preparation in which a siloxane compound reacts with polycarbonate, where at least one of the reactants is anionic and the other is reactive with nucleophiles. More relevant is the description of the US patent. 5,414,054, which described the reactive polycarbonate mixture with a copolymer of lactone and siloxane in the presence of a catalyst. The resulting compositions exhibit better impact resistance at low temperature.

DETAILED DESCRIPTION OF THE INVENTION The catalytic process of the invention for preparing a copolymer resin consists in introducing the component (a) and the component (b) in an extruder under conditions designed to promote the reactive mixture between them in the presence of a catalyst of the trans-rification. Accordingly, component (a) is a wet aromatic polycarbonate resin that contains moisture in an amount greater than 0.02, preferably from 0.03 to approximately 0.35 percent, based on its weight and that has units that conform to where D is a divalent residue of a dihydroxy compound. Component (b) is a lactone-siloxane block copolymer having structural units that conform to where m is 1-90, n is 60-150, R is an alkyl or phenyl radical, p is 2-12 and q is 2-20. The term "reactive mixture" as used in the present context refers to a homogeneous mixture of the polycarbonate resin and the lactone-siloxane block copolymer in the molten state, i.e., in the state in, that these resins are in a thermoplastic state (heated to a plasticity condition by which the resins flow as a fluid). Typically, the temperature is within a range that produces reaction between the resins, generally in the range of 200 to 350 ° C, preferably 250 to 320 ° C. Polycarbonate resins suitable for preparing the copolymer of the present invention are homopolycarbonates and polycarbonates and mixtures thereof. The polycarbonates generally have a weight-average molecular weight of 10,000-200,000, preferably 20,000-L80,000, and their melt flow rate, according to ASTM D-1238 at 300 ° C, is from about 1 to about 65 g / 10. min., preferably about 2-15 g / 10 min. They can be prepared, for example, by the known diphasic process from a carbonic acid derivative, such as phosgene, and dihydroxy compounds by polycondensation (see German Patent Application Publications 2,063,050, 2,063,052, 1,570. 703, 2,211,956, 2,211,957 and 2,248,817; French Patent 1,561,518, and monograph by H. Schnell, "Chemistry and Physics of Polycarbonates", Interscience Publishers, New York, New York, 1964, all of which are hereby incorporated by reference). In the present context, suitable dihydroxy compounds for the preparation of the polycarbonates of the invention conform to structural formulas (1) or (2). where A represents an alkylene group of 1 to 8 carbon atoms, an alkylidene group of 2 to 8 carbon atoms, a cycloalkylene group of 5 to 15 carbon atoms, a cycloalkyl group of 5 to 15 carbon atoms, a group carbonyl, an oxygen atom, a sulfur atom, -SO- or -S02 or a radical that conforms to e and g both represent the number 0 to 1; Z represents F, Cl, Br or C 1 -C 4 alkyl and, if several Z radicals are substituents on an aryl radical, they may be identical or different from each other; D represents an integer from 0 to 4, and f represents an integer from 0 to 3. Among the dihydroxy compounds useful in the practice of the invention are hydroquinone, resorcinol, bis (hydroxyphenyl) alkanes, bis (hydroxyphenyl) ethers, bis ( hi-droxyphenyl) ketones, bis (hydroxyphenyl) sulfoxides, bis (hydroxyphenyl) sulphides, bis (hydroxyphenyl) sulfones and, a-bis (hydroxyphenyl) diisopropylbenzenes, as well as their nuclear alkylated compounds. These and other suitable aromatic dihydroxy compounds are described, for example, in US Pat. 5,105,004, 5,126,428, 5,109,076, 5,104,723, 5,086,157, 3,028,356, 2,999,835, 3,148,172, 2,991,273, 3,271,367 and 2,999,846, all of which are hereby incorporated by reference. Other examples of suitable bisphenols are 2,2-bis (4-hydroxyphenyl) panthenol (bisphenol A), 2, -bis (4-hydroxy-phenyl) -2-methylbutane, 1,1-bis (4-hydroxyphenyl) cyclohexane, a, a '-bis (4-hydroxyphenyl) -p-diisopropylbenzene, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, bis (3, 5-dimethyl-4-hydroxyphenyl) methane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) -panoene, bis (3,5-dimethyl-4-hydroxyphenyl) sulfide, bis (3, 5-dimethyl-4-hydroxyphenyl) sulfoxide, bis (3,5-dimethyl-4-hydroxyphenyl) sulfone, dihydroxybenzophenone, 2,4-bis (3,5-dimethyl-4-hydroxyphenyl) cyclohexane, a '-bis (3, 5-dimethyl-4-hydroxyphenyl) -p-diisopropylbenzene and 4,4'-sulphonyldiphenol. Examples of particularly preferred aromatic bisphenols are 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (3, 3, 5-trimethyl-4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl). cyclohexane. The most preferred bisphenol is 2,2-bis (4-hydroxyphenyl) propane (bisphenol A). The polycarbonates of the invention may include in their structure units derived from one or more of the suitable bisphenols. Among the resins suitable in the practice of the invention are the polycarbonate based on phenolphthalein, copolycarbonates and terpolycarbonates such as those described in US Pat. 3,036,036 and 4,210,741, both incorporated herein by reference. The polycarbonates of the invention can also be branched by condensation in them of small amounts, for example 0.05-2.0 mol% (relative to bisphenols) of polyhydroxyl compounds. Polycarbonates of this type have been described, for example, in German Patent Application Publications 1,570,533, 2,116,974 and 2,113,374; in British Patents 885,442 and 1,079,821, and in US Pat. 3,544,514. The following are some examples of polyhydroxyl compounds that can be used for this purpose: phloroglucinol, 4,6-dimethyl-2,4,6-tri (4-hydroxyphenyl) heptane, 1,3,5-tri (4-hydroxyphenyl) benzene, 1,1, l-tri- (4-hydroxyphenyl) ethane, tri (4-hydroxyphenyl) phenyl-methane, 2,2-bis [4, 4- (4, '-dihydroxydiphenyl)] cyclohexylpropane, 2 , 4-bis (4-hydroxy-l-isopropylidine) phenol, 2,6-bis (2'-dihydroxy-5'-methylbenzyl) -4-methylphenol, 2,4-dihydro-xibenzoic acid, 2- (4- hydroxyphenyl) -2- (2,4-dihydroxyphenyl) propane and 1,4-bis (4,4'-dihydroxytriphenylmethyl) benzene. Some of the other polyfunctional compounds are 2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride and 3,3-bis (4-hydroxyphenyl) -2-oxo-2,3-dihydroindole. In addition to the above-mentioned polycondensation process, other processes for the preparation of the polycarbonates of the invention are the polysondensation in a homogeneous phase and the transesterifi cation. Suitable procedures are described in US Pat. here incorporated as reference 3.028.365, 2,999,846, 3,153,008 and 2,991,273. The preferred process for the preparation of polycarbonates is the interphase polycondensation process. Other synthesis methods can be used in the formation of the polycarbonates of the invention, such as those described in US Pat. 3,912,688, incorporated herein by reference. Suitable polycarbonate resins can be purchased commercially, for example Makrolon FCR, Makrolon 2600, Makrolon 2800 and Makrolon 3100, all of which are bisphenol-based homopolycarbonate resins that differ in terms of their respective molecular weights and characterized by the fact that their ratios Melt Flow (RFF) according to ASTM D-1238 are approximately 16.5-24, 13-16, 7.5-13.0 and 3.5-6.5 g / 10 min., respectively. These are products of the Bayer Corporation of Pittsburgh, Pennsylvania. A polycarbonate resin suitable in the practice of the invention is known and its structure and methods of preparation have been described, for example, in U.S. Pat. 3,030,331, 3,169,121, 3,395,119, 3,729,447, 4,255,556, 4,260,731, 4,369,303 and 4,714,746, all incorporated herein by reference. Of the utmost importance in the context of the present invention, the polycarbonate which is introduced into the reactive mixing process contains a relatively high moisture content and is not dried before introduction into the extruder. While, typically, the polycarbonate for the reactive mixture is introduced into the extruder in the dry state, the polycarbonate used in the process of the invention contains more than 0.02%, preferably 0.03 to about 0.35%. one hundred weight by weight of water, the percentages being relative to the weight of the polycarbonate. The lactone-siloxane block copolymer suitable in the present context is preferably a block copolymer having a structure conforming to 0 R R 0 I Q0- "(CH2) p-C-0-HCH2) q -Si-0- • Si- (CH2) q- -0-C- (CH2) p- -0Q I R R where m is 1-90, preferably 1-50, and n is 60-150, preferably 60-100. R represents a substituted or unsubstituted C1-C20 alkyl radical or phenyl, preferably methyl; Q represents H, C ^^ alkyl or a substituted Cx-C4 alkyl group, a substituted hydrocyclic or hydrocyclic group, a substituted aromatic or aromatic group, a substituted benzyl or benzyl group or a substituted silyl or silyl group; p is 2 to 12, preferably 2, 4 or 5, and q is 2-20, preferably 6-10. In preparing the copolymer of the present invention, it is important to keep the length of the lactone block to a minimum; however, too short a length results in incompatibility between the lactone-siloxane polymer and the polycarbonate resin, which, in turn, results in an excessively slow rate of reaction. While the slow reaction rate can be reconciled by increasing the amount of catalyst, this in turn has an adverse effect on the properties of the final product. The best results were obtained in cases where the length of the di-ethylsiloxane block is about 60 to 80 repetitive units and each block of caprolactone has about 5 to 15 repeating units. A more preferred lactone-siloxane block copolymer is Tegomer H-Si 6720, a Goldschmidt product, having a PDMS block length of about 70 repeating units and a PCL block length of about 10 repeating units. In preparing the copolymer of the invention, it is important that the amount of siloxane in the final product is about 1 to 20%, preferably 2 to 10%, and more preferably about 3 to 6%, relation to the weight of the copolymer. In the process of the invention, the amount of catalyst used in the course of the molten mixture is from about 5 to 1000 ppm, preferably 25 to 500 ppm and, more preferably, 50 to 200 ppm, based on the weight of the resulting copolymer. Suitable catalysts are the known transesterification catalysts, which are stable at temperatures above 200 ° C, including the titanium, tin, zinc, antimony and lead compounds, which are known in the art for their catalytic effect. Special mention would be made of titanium (IV) butoxide, tetrakis (2-ethylhexyl) titanate, tin oxide (IV), dibutyltin oxide, dioctyltin oxide, dibutyltin dilaurate, dioctyltin dilaurate, hydroxide butyltin oxide, octyltin hydroxide, zinc oxide (IV), zinc oxide (II), lead phenolate and lead acetate. The formation of the composition of the invention can be achieved by any conventional melt mixing technique, included in a thermoplastic extruder, preferably a double-helix extruder, where the reactants are heated to a melting temperature and completely mixed in the presence of a catalyst. to effect a reaction. In carrying out the preparation of the copolymer of the invention, the polycarbonate is introduced into an extruder, preferably a double-screw extruder, and the lactone-siloxane copolymer is mixed with the resins and introduced through the feeder, or is molten and pumped with a suitable pump, preferably a gear pump, to an addition inlet downstream of the extruder. The catalyst can be (i) added together with the polycarbonate resins in the feeder or (ii) dispersed in the molten lactone-siloxane copolymer and pumped to the extruder or (iii) dissolved in a suitable solvent, for example methylene chloride, chloroform and tetrachloroethane, mixed with the lactone-siloxane copolymer and then pumped into the extruder. The extrusion and pelletization are carried out following known methods; a vacuum of approximately 20-25 inches of water was applied during the extrusion step. The parameters of the extrusion process, measured in a double-screw extruder ZSK-30, are usually as follows: melting temperature 200-350 ° C, preferably 250-320 ° C; propeller speed 100-700 rpm, preferably 200-600 rpm, more preferably 300-500 rpm.

Experimental: In a series of operations, 94 percent by weight of polycarbonate resin containing moisture and 6 percent of the polycaprolactone-siloxane of the invention were reactive mixed in an extruder (melting temperature of about 315 ° C. , speed of the propeller 300 rpm) in the presence of (150 ppm) dibutyltin dilaurate catalyst. The polycarbonate was Makrolon 3200 homopolycarbonate based on bisphenol A, a product of Bayer Corporation (melt flow rate @ 300 ° C, 1.2 kg Load, approximately 5 g / 10 min according to ASTM D 1238); the polycaprolactone-siloxane was Tegomer H-Si 6720, from Goldschmidt. The extruded copolymer was examined for its properties and the results are summarized in Table 1. Table 1 (l) Moisture content in polycarbonate. The extrudates did not show delamination and exhibited good surface quality. In a corresponding set of experiments, the copolymers prepared according to the invention were compared with corresponding extrudates in which the polycaprolactone-siloxane was Tegomer H-Si 6520 (from Goldschmidt), which is outside the scope of this invention. In this series, the polycarbonate and the polycaprolactone siloxane according to the invention, as well as the relative amounts of the reactants and the catalyst, were identical to those of the experiments described above. A summary of the results is shown in Table 2. Table 2 (a) Comparative examples including as polycaprolactone-siloxane Tegomer H-Si 6520. < The moisture content in the polycarbonate The surface appearance of Examples 8 and 9, representative of the invention, was good and the extruded copolymer showed no delamination The surface appearance of Comparative Example 5 (which had a low moisture content) was good and free from delamination, Examples 6 and 7 exhibited poor surfaces and were laminated.The dependence of the properties of the inventive copolymer with respect to the relative amounts of polycaprolactone-siloxane is shown in Table 3 The preparation of the copolymer followed the procedure described above Dibutyltin dilaurate catalyst (150 ppm) was used in the reactions The polycarbonate used in this series was DP9-9350 copolycarbonate (based on 35 mole percent of 2,2-bis) (3, 3, 5-trimethyl-4-hydroxyphenyl) propane and 65 molar percent BFA) The moisture content of the polycarbonate was 0.1%.

The extrudates exhibited good surfaces and no delamination. Although the invention has been described in detail in the foregoing for purposes of illustration, it is to be understood that said detail has that purpose only and that those skilled in the art can make variations therein without departing from the spirit and scope of the invention, except in what may be limited by the claims.

Claims (10)

1. CLAIMS 1. A process for preparing a copolymer resin, which consists in introducing component (a) and component (b) in an extruder under conditions designed to promote the reactive mixture therebetween in the presence of a transesterification catalyst, wherein said component (a) is a wet aromatic polycarbonate resin that contains moisture in an amount greater than 0.02 percent relative to its weight and that has units that conform to where D is a divalent residue of a dihydroxy compound and wherein said component (b) is a lactone-siloxane block copolymer having structural units that conform to where m is 1-90, n is 60-150, R is an alkyl or phenyl radical, p is 2-12 and q is 2-20. The method of Claim 1, wherein the moisture is in an amount of from 0.03 to about 0.35 percent. 3. The method of Claim 1, wherein said n is approximately 60-100. 4. The method of Claim 1, wherein said n is approximately 60-80. 5. The method of Claim 1, wherein said R is a methyl group. The method of Claim 1, wherein said p is 2, 4 or 5. 7. The method of Claim 1, wherein said is from 6 to 10. The method of Claim 1, wherein said n is approximately 65. -100, R is a methyl group, p is 2, 4 or 5 and q is 6 to 10. The method of Claim 1, wherein said D is a residue of a dihydroxy compound selected from compounds that conform to the formulas (1 or 2) where A represents an alkylene group of 1 to 8 carbon atoms, an alkylidene group of 2 to 8 carbon atoms, a cycloalkylene group of 5 to 15 carbon atoms, a cycloalkyl group of 5 to 15 carbon atoms, a group carbonyl, an oxygen atom, a sulfur atom, -SO- or -S02 or a radical that conforms to e and g both represent the number 0 to 1; Z represents F, Cl, Br or C 1 alkyl and, if several radicals Z are substituents on an aryl radical, they can be identical or different from each other; d represents an integer from 0 to 4, and f represents an integer from 0 to 3. 10. The method of claim 1, wherein said catalyst is a member selected from the group consisting of titanium (IV) butoxide, tetrakis ( 2-ethylhexyl) titanate, tin oxide (IV), dibutyltin oxide, dioctyltin oxide, dibutyltin dilaurate, dioctyltin dilaurate, butyltin oxide hydroxide, octyltin hydroxide, zinc oxide (IV), zinc oxide ( II), lead phenolate and lead acetate.