Patent Application
20080045656
These examples illustrate that compositions of the invention comprising particular radial block copolymers exhibit improved impact strength compared to compositions comprising other block copolymers. Components and amounts are presented in Table 1. All amounts are given in parts by weight. The poly(arylene ether) was a poly(2,6-dimethyl-1,4-phenylene ether) having an intrinsic viscosity of about 0.46 deciliter per gram, obtained from GE Plastics (“PPE” in Table 1). The antioxidant pentaerythritol tetrakis(3-dodecylthiopropionate) was obtained as SEENOX 412S from Shipro Kasei Kaisha (“Antioxidant” in Table 1). A radial block copolymer having a styrene content of 68 weight percent and a melt flow rate of 9.0 grams per 10 minutes measured at 200° C. and 5 kilograms load was obtained as K-Resin KK38 from Chevron Phillips Chemical Company (“KK38” in Table 1). A styrene-butadiene block copolymer described by its manufacturer as “multiarmed” and having a styrene content of 75 weight percent and a melt flow rate of 11.4 grams per 10 minutes measured at 200° C. and 5 kilograms load was obtained as KRATON® D1493 from Kraton Polymers (“D1493” in Table 1). A styrene-butadiene block copolymer described by its manufacturer as “multiarmed” and having a styrene content of 75 weight percent and a melt flow rate of 11 grams per 10 minutes measured at 200° C. and 5 kilograms load was obtained as KRATON® MD6459 from Kraton Polymers (“MD6459” in Table 1).
For each composition, all components except the block copolymer were dry blended and added to the feed throat of a twin-screw extruder. The block copolymer was added via a side-stuffer in barrel 7 of a 10-barrel extruder. It has been found that downstream addition of the block copolymer, rather than addition at the feed throat, may improve the impact strength of the resulting composition. The barrel temperatures from the feed throat to the die are 250 and 290° C. in the first two barrels, respectively, and 300° C. in the remaining barrels and at the die. The extruder operated at about 350 rotations per minute, and the feed rate was about 16 kilograms/hour (about 35 pounds/hour). The extruder had a vacuum vent at barrel 10 with 20-25 inches of water vacuum being applied. The screw design had fairly intensive mixing in barrels 2 to 4 with relatively mild mixing in barrel 9 downstream of the side stuffer.
Property values for each composition are presented in Table 1. Notched Izod impact strength was measured according to ASTM D 256 Method A at 23° C. using a 0.907 kilogram (2.00 pound) hammer, and specimens having a notch such that at least 1.02 centimeter (0.4 inch) of the original 1.27 centimeter (0.5 inch) depth remained under the notch; the specimens were conditioned for 24 hours at 23° C. after notching. Dynatup energy to maximum load, energy to failure, total energy, and maximum load were measured according ASTM D 3763 at 23° C. using an Instron Dynatup Model 8250. All Dynatup energy values are expressed in joules (J), and Dynatup maximum load values are expressed in Newtons (N). The standard deviation for each property value represents evaluation of three samples per test. In the Table 1 rows for “failure mode”, “B” indicates brittle failure (the test sample shattered into at least two fragments), “D” indicates ductile failure (the test sample was cleanly punctured), and “DB” indicates ductile-brittle failure (the test sample was punctured with some cracking). The results show that inventive Examples 1-3 exhibit substantially improved impact strength compared to the corresponding comparative examples. Example 4 has no corresponding comparative example, but it, too, exhibits excellent impact strength.
These examples illustrate that compositions of the invention comprising combinations of an alpha-hydroxyketone, a trihydrocarbyl phosphite, and a carboxylic acid compound exhibit improved (reduced) percent haze compared to corresponding compositions without these haze-reducing additives. Components and amounts are presented in Table 2. All amounts are given in parts by weight. The poly(arylene ether), the KK38 radial block copolymer, and the SEENOX antioxidant were the same as those described for Examples 1-4. Benzoin was obtained as product no. 04-666 from Aceto Chemical. Tridecyl phosphite was obtained from Dover Chemical Company (“TDP” in Table 1). Anhydrous citric acid was obtained from Cargill (“CA” in Table 1).
Compositions were compounded as described for Examples 1-4.
Percent haze was measured according to ASTM D 1003-00 at 23° C. and a thickness of 3.200 millimeters. Percent haze values for each composition are presented in Table 2. The results show that the haze-reducing additives of the invention provide substantial reductions in percent haze for all inventive examples relative to the corresponding comparative examples without such additives. Percent haze is an objective property that correlates with the subject property of optical clarity.
These examples illustrate the effectiveness of alpha-hydroxyketones, trihydrocarbyl phosphites, and carboxylic acid compounds in reducing the haze and increasing the percent transmittance of compositions comprising poly(arylene ether) and radial block copolymer. Ten compositions were prepared, including three pairs of replicates (Examples 9 and 12, Examples 13 and 17, Examples 16 and 8). Component types and amounts (in parts by weight) are summarized in Table 3.
Percent haze was measured as described above. Percent transmittance was measured according to ASTM D 1003 at a thickness of 3.2 millimeters. The results, present in Table 3, show that the lowest (most desirable) haze values were associated with the addition of benzoin alone (Example 21) or benzoin and citric acid in combination (Example 15). The highest (most desirable) percent transmittance values were associated with the combination of benzoin and tridecyl phosphate (Example 19).
These examples demonstrate additional inventive blends, including blends with relatively high proportions of the radial block copolymer component. Also included are comparative examples using a radial block copolymer that does not meet one or more criteria of the radial block copolymer used in the inventive composition.
The poly(arylene ether), KK38 radial block copolymer, benzoin, and tridecyl phosphite are the same as those used in Examples 1-4. A radial block copolymer having a styrene content of 75 weight percent and a melt flow rate of 7.5 grams per 10 minutes measured at 200° C. and 5 kilograms load was obtained as K-Resin KR05 from Chevron Phillips Chemical Company (“KR05” in Table 4). A hindered phenol antioxidant was obtained as IRGANOX 1010 from Ciba Geigy (“Antioxidant” in Table 4). Component types and amounts (in parts by weight) are summarized in Table 4. Compositions were compounded as described for Examples 1-4. Notched Izod impact strength, expressed in joules per meter (J/m), was measured at 23° C. according to ASTM D 256, Method A. The uncertainties in the notched Izod values reflect measurements on three samples per composition.
Comparison of results for Examples 23-25 (containing KK38 as radial block copolymer) with those for Comparative Examples 11-13 (containing KR05 as radial block copolymer) shows that the samples with KK38 exhibit substantially and unexpectedly greater impact strength.
The results for Examples 27-30 show that substantial improvements in impact strength are observed even with relatively low levels of the KK38 radial block copolymer (less than 20 weight percent, based on the total weight of the composition).
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.
All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Further, it should further be noted that the terms “first,” “second,” and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity).
