Source: http://www.freepatentsonline.com/9040615.html
Timestamp: 2018-01-18 10:06:05
Document Index: 60417361

Matched Legal Cases: ['Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60']

20070227748 Fire Retarded Flexible Nanocomposite Polyurethane Foams 2007-10-04 Liggat et al. 169/45
6084019 High I.V. polyester compositions containing platelet particles 2000-07-04 Matayabas et al. 524/445
This application is a continuation-in-part of U.S. application Ser. No. 12/418,344 filed Apr. 3, 2009, which in turn is a continuation of U.S. application Ser. No. 11/312,068, filed Dec. 20, 2005, now abandoned which in turn claims the benefit of priority of U.S. Provisional Application No. 60/638,225, filed Dec. 22, 2004, U.S. Provisional Application No. 60/686,675, filed Jun. 2, 2005, U.S. Provisional Application No. 60/686,728, filed Jun. 2, 2005, U.S. Provisional Application No. 60/686,847, filed Jun. 2, 2005, U.S. Provisional Application No. 60/686,689, filed Jun. 2, 2005, U.S. Provisional Application No. 60/686,707, filed Jun. 2, 2005, U.S. Provisional Application No. 60/686,708, filed Jun. 2, 2005.
This invention concerns compositions comprising thermoplastic polyesters and fibrous clays, which are made by adding a fibrous clay to a polyester polymerization, and forming the compositions into useful parts.
In some cases, it is necessary to include both platelet-type nanoparticles and other fillers to achieve desired characteristics. For example, U.S. Pat. No. 7,138,453 discloses dispersing platelet-type nanoparticles in a thermoplastic polyester and then melt kneading the resulting nanocomposite with reinforcing fibrous fillers, e.g., glass fiber, carbon fiber, aramid fiber, silicon carbide fiber, alumina fiber and boron fiber, whiskers such as silicon carbide whisker, silicon nitride whicker, magnesium oxide whisker, potassium titanate whisker and alunimo borate whisker, and needle crystals such as wollastonite, zonotolite, PMF, plaster fiber, dawsonite, MOS, phosphate fiber and sepiolite. For both processing capability and reinforcing efficacy, the reinforcing fibers are 2 to 20 micrometers in diameter (U.S. Pat. No. 7,138,453, col. 5, line 45 through col. 6, line 7; Examples 18 through 24).
Another process for making thermoplastic polyester nanocomposites, using untreated “layered phyllosilicate” (i.e., platelet nanoclays), is disclosed in U.S. Pat. No. 7,138,453, comprising preparing a dispersion containing layered phyllosilicate and water, adding the dispersion continuously or successively to a component having low polymerization degree of the thermoplastic polyester resin at a rate of 0.01 to 10.0 parts by weight per minute based on 100 parts by weight of the component having low polymerization degree of the thermoplastic polyester resin; and polymerizing the thermoplastic polyester.
As used herein, term “organically modified” describes a clay that has been contacted with an organic compound to change the clay's surface properties or interlayer distance. A clay can be treated with an organic compound, a “hydrophobicizer,” to make the clay surface more compatible with systems of low-to-medium polarity; an example is treatment with a quaternary ammonium salt such as dimethylbenxylalkylammonium chloride, as disclosed in European Patent Application 221,225. Further, in forming a polymer nanocomposite with a smectic clay like montmorillonite, an ionic hydrophobicizer can replace metal cations between the constituent layers of the clay (“intercalation”), pushing the layers farther apart (“delamination”). Clay having a high cation exchange capacity (e.g., at least 50 meq/100 g) is thus preferred for this approach to be effective. Subsequent processing is then needed to fully exfoliate the clay. Typically, hydrophobicizers are organic compounds derived from oxonium, ammonium, phosphonium or sulfonium ions, which may carry one or more organic radicals. Quaternary ammonium salts are commonly used. Many other hydrophobicizers are listed in U.S. Pat. No. 6,458,879 (col. 3, I. 63-col. 5, I. 30).
As used herein, “a solid particulate filler exclusive of the fibrous clay” means any solid (infusible at temperatures to which the composition is normally exposed) which is finely divided enough to be dispersed under melt mixing conditions (see below) into the composition.
Sepiolite [Mg4Si6O15(OH)2.6(H2O)] is a hydrated magnesium silicate filler that exhibits a high aspect ratio due to its fibrous structure. Unique among the silicates, sepiolite is composed of long lath-like crystallites in which the silica chains run parallel to the axis of the fiber. The material has been shown to consist of two forms, an α and a β form. The α form is known to be long bundles of fibers and the β form is present as is amorphous aggregates.
Attapulgite (also known as palygorskite) is almost structurally and chemically identical to sepiolite except that attapulgite has a slightly smaller unit cell. As used herein, the term “fibrous clay(s)” includes attapulgite clay, sepiolite clay and mixtures thereof.
Additionally, rheological grade sepiolite has a very low cationic exchange capacity (10-20 meq/100 g) and the interaction with electrolytes is very weak, which in turn causes rheological grade sepiolite not to be practically affected by the presence of salts in the medium in which it is found, and therefore, it remains stable in a broad pH range. The low cation exchange capacity also makes it less suitable for the cation exchange/intercalation/delamination treatment used for smectic clays having higher cation exchange capacity, like montmorillonite, which typlically has a cation exchange capacity of about 100 meq/100 g.
Where it is desired to add the fibrous clay as a slurry with one of the ambient temperature liquid ingredients, the slurry can be prepared by mixing 0.1% to 20% fibrous clay with 80% to 99.9% liquid ingredient by weight. High slurry viscosity makes it difficult to pump, meter, or otherwise transport the slurry. Increasing slurry temperature and more aggressive mixing are known to increase slurry viscosity. Slurry viscosity can be minimized by 1) mixing the fibrous clay with the liquid ingredient at as low a temperature as is practical, 2) maintaining the temperature of the slurry as low as is practical, and 3) mixing the fibrous clay powder into the liquid with only enough energy and/or shear to wet the powder, and 4) avoiding prolonged mixing once a stable slurry as been formed. In one embodiment 4% to 7% fibrous clay and 93% to 95% liquid ingredient are mixed. In another embodiment 7% to 9% fibrous clay by weight and 91% to 93% by weight liquid ingredient are mixed. In another embodiment 9% to 12% fibrous clay and 88% to 91% liquid ingredient by weight are mixed. In another embodiment 12% to 16% fibrous clay and 84% to 88% liquid ingredient by weight are mixed. In any type of process, one preferred way of carrying out the process the fibrous clay is added to one or more of the polyester precursors, especially to a liquid diol (glycol), if a diol is used in the polymerization. It is preferred to mix the liquid diol and clay so that the clay particles are wetted by the diol. The slurry formed may them be added to the polymerization process. In an especially preferred process a slurry containing the diol is added to the other process ingredients after 75 percent of the byproduct water or alcohol (from the condensation of a dicarboxylic acid or diester with a glycol) has been removed from the polymerization process. Optionally also present in the diol when the clay is added and/or mixed may be other monomers such as dicarboxylic acids or their esters, and hydroxycarboxylic acids. If a diol is not used the clay may be mixed with any other liquid monomer or polyester precursor. Again it is preferred that the clay is wetted by the polyester precursor(s). The wetting of the clay may be carried out by merely mixing the slurry of liquid polyester precursor(s) and clay, and optionally other solid polyester precursors. Other more intensive mixing methods may also be used, such as using a “homogenizer” or a paint mill. Also any other additional fillers may be present (added) at this time.
Other materials may also optionally be present during the polymerization process, such as stabilizers, antioxidants, and other materials sometimes added to such processes. Other filler(s) and/or reinforcing agent(s) may also be present in the polymerization, either from the beginning of the process or added during the process as long as they do not interfere with the polymerization (for example, increase or decrease the rate, limit the achievable molecular weight, affect formation of byproducts, etc.). If the composition is meant for eventual use in appearance parts these solids should preferably meet the particle size specifications outlined herein. However they need not meet these specifications if the composition is not meant to be used for appearance parts.
The solid particulate material may be conventionally melt mixed with the nanocomposite, for example in a twin screw extruder or Buss kneader. However the particulate material may also be added to the process for forming the polyester nanocomposite, i.e., at or near the beginning of the polymerization process. It may be added at the same time as the fibrous clay, although if a lot of particulate material is added it may increase the viscosity of the material undergoing the polymerization process, and care should be taken not to increase the viscosity too high.
In one sample preparation method the sample was simply used as was. In another method the sample was heated to 290° C., and quenched in liquid nitrogen. With either preparation method the sample was then heated at a rate of 200° C./min to the desired temperature and the crystallization exotherm followed at that temperature in the DSC. From the exotherm curve generated with time, the crystallization half life at that temperature was then calculated.
Tensile Modulus, Strength and Elongation
Determined using a Kayness Model 8052 viscometer, Kayness Corp., Morgantown Pa., U.S.A., at 280° C. and a shear rate of 1000/sec, with an orifice which was 1.52 cm (0.600″) long and 0.0762 cm (0.030″) in diameter. Holdup time was simply the amount of time which elapsed after the sample was added to the viscometer and before the measurement began, and was 6 minutes.
The material so produced was characterized using TEM, which showed the filler to be present as agglomerates with a small proportion of plate-like structures (FIG. 3).
The melt viscosities show that the compositions contained polyesters of similar molecular weights, although Comparative Examples F and H may have suffered some hydrolysis in the melt blending. The properties of the compositions of Examples 4 and 5 showed good stiffness (flexural modulus) and tensile strength while still having superior toughness. The combination of high stiffness and toughness is often difficult to achieve, whether the composition is toughened (Polymer A) or not.