BRPI0617474A2 - thermoplastic polyurethane powder compositions and their uses - Google Patents

Abstract

<B> THERMOPLASTIC POLYURETHANE POWDER COMPOSITIONS AND THEIR USES <D> Thermoplastic powder compositions and related processes of the invention comprise at least one thermoplastic polyurethane having a melt index of at least about 8g / 10mm when tested according to ASTM D1238 at 190 <198> C and a weight of 2.16 kg; at least one internal lubricant in an amount of up to 5% by weight of the composition; and, optionally, at least one flow agent or other components. Such thermoplastic powder compositions are suitable for forming on a variety of articles, using, for example, high speed impact melting or mud molding techniques.

Description

THERMOPLASTIC POLYURETHANE POWDER COMPOSITIONS AND THEIR USES CLAIMING PRIORITY

This application claims the priority of U.S. Provisional Patent Serial No. 60 / 727,367 with document number 12004007 and filed October 17, 2005, which is incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to polyurethane powder thermoplastic compositions and their uses.

Over many decades, the use of polymerstransformed the world. Polymer science has evolved rapidly to produce thousands of different thermoplastic and thermoplastic products within the four corners of polymer physics: thermoplastic plastics, thermoplastic elastomers, thermoformed plastics, and thermoformed elastomers.

No large scale production of any polymer or articles thereof can rest on current ingredients or processing conditions. Cost reduction, improved productivity, better performance delivery, lower cost products all drive the polymer science industry. With the advent of new materials and associated processes, it is often beneficial to replace older polymeric materials with materials having improved properties, processing capabilities and / or processing efficiencies in particular applications and associated processes.

For example, in certain applications, polyvinyl chloride (PVC) substitutions are desired. PVC formed articles, while relatively inexpensive and easy to process, tend to become brittle (and thus exhibit a brittle failure mode) when used at lower temperatures. Thus, the use of PVC to form articles subjected to cold weather and other relatively low temperatures can be problematic for certain applications requiring ductile failure modes.

In particular, an application where failure modes are preferred involves the manufacture of articles for vehicle passenger compartments such as cars, airplanes, trucks, farm equipment, construction equipment, etc. Polymeric materials are used to manufacture many parts and subsets within such passenger compartments. For example, instrument panels, door panels, backrest, headrest, center consoles, and air bags, etc. may be made of one or more polymeric materials.

A subcomponent of such articles often takes the form of a "polymeric skin." 11 Polymeric skins can provide the outer surface of larger articles, being filled with molded foam or other padded materials to provide the body and a sculpted appearance to the entire article. For example, articles padded or filled inside passenger compartments, such as instrument panels, door panels, and the like, were produced by providing a PVC mud molded skin.The skin is held in place on a substrate and then backfilled with a foam material. (eg urethane foam) in an injection process wherein the edges of the skin are sealed to provide a finished product.The finished product includes the skin with the sub-layer foam-padded protective covering, which may include the edges of a door panel. , the edges of an instrument panel, or the like.The reference to the use of polymeric skins in this An example can be found within, for example, U.S. Patent Publication 2002/0125734 Al.

When materials exhibiting brittle failure modes break some or all of the intended use temperatures are used in producing polymeric skins for such applications, however, they pose a risk to the passenger in the event of impact, or the other case leading to failure of an article. This risk is increased by using fragile materials due to the tendency of fragile materials to break and fragment into tiny parts, often having jagged or sharp edges. The generation of such shrapnel endangers the safety of those inside and outside the passenger compartment.

As such, a prerequisite for selecting materials for use in passenger car manufacturing often involves testing to determine the ability of a material for use in a variety of environments. Materials for a particular article within the passenger compartments - air bags - are carefully selected under a wide variety of environmental conditions. The performance of a material at temperatures of about -40 ° C (-40 ° F) and below is an important starting point in determining the ability of a material to pass these tests. PVC often fails these tests due to its fragile tendency at lower temperatures. Furthermore, PVC is advantageous over conventional substitutes because of its relatively low cost. Thus, alternative materials are desired.

Not only are materials still desired, but efficient and replicable methods for producing articles are desired as well. A wide variety of processes are known for the manufacture of polymeric components such as those described above. One particular process for the formation of polymeric skins is called high speed impact fusion (HVIF).

In this process, a polymerized powder is melted into an inert gas such as nitrogen before it is accelerated into a mold or other tool where the powder accumulates on one or more target surfaces and then solidifies into a solid film. The target surface is typically maintained at about room temperature to promote solidification of the film. See, for example, U.S. Patent No. 5,285,967.

HVIF has been used to check polymeric coatings on articles to protect the surfaces or underlying materials that come in contact with the underlying surfaces from damage (eg contamination).

Frequently, the polymeric coating provides a relatively clean, non-toxic surface and is produced from a relatively inert material. For example, polyethylene is coated inside wagons using HVIF to prevent foodstuffs carried by wagons from becoming contaminated.

It is desirable to expand the application of HVIF to other materials due to the processing advantages associated with the method and its ability to form articles having the desired surface characteristics. This is particularly true for those applications that want surface coatings of a particular gauge (for example, one that is smooth and uniform or one that has a uniform leathery appearance). Until now, however, the expansion of HVIF to include the preparation of articles for industries such as those involving the manufacture of polymeric articles used in passenger compartments has been difficult because the appropriate powder compositions for this original process are not yet known. As such, injection molding has become a prevalent method for forming polymeric skins and other polymeric articles in these applications due to the limitations and disadvantages associated with HVIF and other manufacturing techniques (eg vacuum forming, slurry molding, molderotatory, and spraying). Again, reference is made to U.S. Patent Publication 2002/0125734

BRIEF SUMMARY OF THE INVENTION

Advantageously, the invention provides a suitable thermoplastic emulsion composition for forming into a high speed impact melt article. Such powder compositions have a unimodal particle size distribution and comprise at least one polyurethanothermoplastic having a melt index of at least about 8 g / 10 min when tested according to ASTMD1238 at 190 ° C and a weight of 2.16 kg; at least one internal lubricant in an amount of up to about 5% by weight based on the total weight of the composition; and optionally at least one flow agent or other components (e.g., thermal stabilizers, photostabilizers, pigments, antioxidants, plasticizers, fillers, and adjusting agents).

Other thermoplastic powder compositions are also facilitated by the present invention. Depending on the application, the powder composition may have a unimodal particle size distribution or a bimodal particle size distribution.

For example, the invention provides a suitable thermo-plastic powder composition for forming into an article using the mud mold. Such powder compositions have a bi-modal particle size distribution and comprise at least one thermoplastic polyurethane having a melt index of at least about 8 g / 10 minutes when tested according to ASTM D1238 at 190 ° C and a weight of 2.16 kg; at least one internal lubricant in an amount up to about 5% by weight based on the total weight of the composition; and optionally at least one flow agent or other components (e.g., thermal stabilizers, photostabilizers, pigments, antioxidants, plasticizers, fillers, and adjusting agents).

In exemplary embodiments of the invention, the thermothermic polyurethane comprises aliphatic thermoplastic polyurethane or aromatic thermoplastic polyurethane. In other embodiments, the thermoplastic polyurethane comprises the polyether-based thermoplastic polyurethane (for example, a polyetheraromatic thermoplastic polyurethane) or the thermoplastic polyurethane based on an aliphatic polyester. When the amounts of the individual components vary, desired application and process, in one embodiment the thermoplastic powder composition will comprise from 0.01 to about 1.0% by weight of an internal lubricant such as mono- and distearyl acid phosphate. Preferably, although not necessarily, the composition is essentially free of the components prone to flourishing migration in the prepared articles thereof.

In other embodiments, the powder composition may be a mixture of the powder composition. The powder composition mixtures of the invention comprise at least one thermoplastic polyurethane and at least one other polymer (e.g. polyvinyl chloride). In one exemplary embodiment, the other polymer comprises more than about 10% by weight of the total composition. For example, the other polymer may be polyvinyl chloride in an amount up to about 90% by weight of the total composition. In exemplary embodiments of the powder composition, the composition comprises from about 5 to about 50% by weight. about 10 to about 30% by weight, or further promotes about 15 to about 25% by weight of thermoplastic polyurethane based on the total weight of the composition. Other components may also be present, including for the example melt-processable rubber.

A variety of articles may be prepared from the thermoplastic powder compositions of the invention. For example, the polymeric subcomponents of the skin of further articles for passenger compartments of a vehicle may be formed from thermoplastic powder compositions. Further articles include instrument panels, door panels, armrests, backrest. for the head, center consoles, and air bags for a passenger compartment of a vehicle. The compositions of the invention provide alternative advantages and advantages over conventional materials used for such purposes.

The processes of the invention include those for preparing thermoplastic powder compositions. Such processes include steps of providing a thermoplastic polyurethane, demixing the thermoplastic polyurethane with one or more optional components, and transforming the thermoplastic polyurethane and optional components into a powder having a uni-modal particle size distribution or otherwise predetermined. In an exemplary embodiment, the composition is transformed into a powder using cryogenic grinding, sorting and recycling steps.

Processes for preparing articles of the thermo-plastic powder composition include those using a high speed impact melt, a leitofluidized powder coating, an electrostatic spray, a thermal spray, a mud mold, or a rotational domination technique. According to exemplary embodiments of the invention, an external mold release agent is not required or used to form such articles.

BRIEF DESCRIPTION OF VARIOUS VIEWS OF DRAWINGS

Figure 1 is a single-mode particle size distribution associated with powder compositions useful for forming articles according to a high speed impact melt technique according to the invention.

Figure 2 is a bi-modal particle size distribution associated with the powder compositions useful for forming articles according to an emlama mold technique according to the invention.

Figure 3 is a schematic flowchart of an exemplary process for forming powder compositions of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Compositions

The thermoplastic polyurethane powder (TPU) compositions of the invention comprise at least one lower TPU and one or more optional components, selected according to the intended use of the composition.

TPU is a desirable thermoplastic elastomer because it exhibits high tensile strength and ruptures, has high flexibility at low temperatures, and extremely good abrasion and scratch resistance. TPU is also relatively stable against oil, fats and many solvents, as well as ultraviolet radiation. Because of these desirable characteristics, TPU can be beneficially used for a number of usofinal applications, such as those in the automotive and decal industries.

For the sake of simplicity, the term "polyurethane" as used herein includes polymers containing deurethane bonds (also known as carbamate), deurea bonds, or combinations thereof (i.e. depoli (urethane urea) s). Thus, polyurethanes

The thermoplastics of the invention contain at least deurethane bonds and optionally urea bonds. A wide variety of TPU chemicals is suitable for use as the base TPU of the invention. For example, a number of ear-aliphatic chemicals may be used. One or more TPU chemicals may be used to form the base TPU for compositions of the invention.

The term "aromatic" refers to TPUs derived from mononuclear aromatic hydrocarbon groups or polynuclear aromatic hydrocarbon groups. The term includes those TPUs derived from arylene groups. The term "arylene group" means a divalent aromatic group.

The term "aliphatic" refers to TPUs derived from saturated or unsaturated, linear, branched, or cyclic hydrocarbon groups. This term is used to include those TPUs derived from alkylene (e.g., oxyalkylene), aralkylene, and cycloalkylene groups (e.g., oxycycloalkylene), for example. The term "alkylene group" means a linear, branched or divalent saturated hydrocarbon group. Particularly preferred alkylene groups are oxyalkylene groups.

The term "oxyalkylene group" means a divalent, straight or branched saturated hydrocarbon group with a terminal oxygen atom. The term "aralkylene group" means a divalent saturated straight or branched hydrocarbon group containing at least one aromatic group. The term "cycloalkylene group" means a saturated, linear or branched divalent hydrocarbon group containing at least one cyclic group. The term "oxycycloalkylene group" means a divalent, straight or branched hydrocarbon divalent group which contains at least one cyclic group and a terminal deoxy oxygen atom.

According to one embodiment of the invention, a TPU is obtained by reacting a difunctional isocyanate composition with at least one difunctional polyhydroxy compound and optionally a chain extender in such amounts that the isocyanate index is between about 90 and about 110, preferably between about 95 and about 105, and most preferably between about 98 and about 102.

The term "difunctional" as used herein means that the average functionality of the isocyanate and decomposed polyhydroxy composition is about 2.

The term "isocyanate index" as used herein is the correlation of hydrogen reactive isocyanate atoms about the isocyanate groups present in a composition, provided in percent. That is, the isocyanate index expressed as a percentage of isocyanate actually used in a composition with respect to the amount of isocyanate required theoretically reacting with the amount of hydrogen reactive isocyanate used in a composition.

It should be noted that the isocyanate index as used herein is considered from the point of view of the actual polymer forming the process involving the isocyanate ingredient and the reactive isocyanate ingredients. All two cyanate groups consumed in a preliminary step to produce modified polyisocyanates (such isocyanate derivatives including those known in the art as quasi-semisprepymers) or no active hydrogen reacted with isocyanate to produce modified polyols or polyamines are not taken into account in the calculation of the deisocyanate index. Only the free isocyanate groups and free reactive isocyanate hydrogens present in the actual elastomer that form in the stage are taken into consideration.

In this embodiment, the difunctional polyhydroxy compound has a weight average molecular weight of between about 50 and about 20,000, and diols such as polyesteramides, polythiols, polycarbonates, polyacetals, polyolefins, polysiloxanes, polybutadienes and preferably polyesters and polyethers, or mixtures are selected. of the same. Other dihydroxy compounds such as hydroxyl-terminated styrene butadiene block copolymers, SBS, SIS, SEBS, or SIBS block copolymers are known and may be used as well.

Mixtures of two or more compounds of such or other features and in such ratios that the average functionality of the total composition is about 2 may also be used as the difunctional polyhydroxy compound. For polyhydroxy compounds, the actual functionality may be less than the functionality. initiation due to some terminal unsaturation. Accordingly, for example, small amounts of polyhydroxytrifunctional compounds may also be present in order to achieve the desired average functionality of the composition.

Polyether diols which may be used include the products obtained by polymerizing a cyclic oxide for the example ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran in the presence, where necessary, of difunctional initiators. The appropriate starter compounds contain two active hydrogen atoms and include water; butanediol; ethylene glycol propylene glycol; diethylene glycol; methylene glycol dipropylene glycol; 1,3-propane diol; neopentyl glycol 1,4-butanediol; 1,5-pentanediol; 1,6-pentanediol; and the similar. Mixtures of initiators and / or cyclic oxides may be used.

Especially useful polyether diols include polyoxypropylene diols and poly (oxyethylene) diols obtained by the simultaneous or sequential addition of ethylene or propylene oxides to the difunctional initiators. Random copolymers having oxyethylene indices of about 10-80 wt%, block copolymers having oxyethylene indices of up to about 25 wt% and random / block copolymers having up to about 50 wt% oxyethylene indices Total weight based on the total weight of oxyalkylene units may be mentioned, in particular those having at least the part of the oxyethylene groups at the end of the polymer stream. Other useful polyether diols include the polytetramethylene diols obtained by dotetrahydrofuran polymerization. Also suitable are polyether diols containing low unsaturation levels (i.e. less than about 0.1 milliequivalents per gram diol).

Other diols which may be used include dispersions or solutions of the addition or condensation of polymers in the diols of the types described above. Such modified diols, often referred to as "polymer diols" include products obtained by in situ polymerization of one or more vinyl monomers, for example styrene and acrylonitrile, into polymeric diols, for example, polyether diols, or by the reaction thereof. It is located between a polyisocyanate and an amino and / or hydroxy functional compound, such as triethanolamine, in a polymeric diol.

Polyoxyalkylene diols containing about 5-50% by weight of the dispersed polymer are useful as well. Particle sizes of the dispersed polymer of less than 50 microns are preferred.

Polyester diols which may be used include hydroxyl-terminated reaction products of hydroxy alcohols such as ethylene glycol; propylene glycol, diethylene glycol; 1,4-butanediol; neopentyl glycol; 2-methylpropanediol; 3-methylpentane-1,5-diol; 1,6-hexanediol; cyclohexane dimethanol; and mixtures of such dihydric alcohols and dicarboxylic acids or their adipic acid ester derivatives (for example succinic acid, glutaric acid, and / or their esters of dimethyl, sebacic acid, phthalic anhydride, tetrachlorophthalic anhydride, and mixtures thereof).

Polyesteramides may be obtained by the inclusion of amino alcohols such as ethanolamine in polyesterification mixtures.

Politioether diols which may be used include products obtained by condensing thiodiglycol alone or with other glycols, alkylene oxides, dicarboxylic acids, formaldehyde, amino alcohols, or amino carboxylic acids.

Polycarbonate diols which may be used include those prepared by reacting glycols such as diethylene glycol, triethylene glycol, or the abnormaldehyde hexanediol. Suitable polyacetals may also be prepared by polymerizing cyclic acetans.

Suitable polyolefin diols include the hydroxy-terminated butadiene homopolymers.

Suitable polysiloxane diols include solid dimethylsiloxane diols.

Suitable difunctional chain extenders include aliphatic diols, such as ethylene glycol; 1,3-propanediol; 1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol; 1,2-propanediol; 2-methylpropanediol; 1,3-butanediol; 2,3-butanediol; 1,3-pentanediol; 1,2-hexanediol; 3-methylpentane-1,5-diol; diethylene glycol dipropylene glycol; and tripropylene glycol, and aminoalcohols such as ethanolamine, N-methyldiethanolamine, and the like. Of these, 1,4-butanediol is preferred.

According to another embodiment, the TPU powder composition comprises a polyester-based aromatic TPU. According to another embodiment, the TPU powder composition comprises an aliphatic, polyester-based TPU. The latter TPU chemical is particularly desirable because of the ability to more precisely and accurately control melting properties (e.g., melt index (MFI)) thereof compared to the previous chemical.

A number of appropriate TPU compositions are commercially available. Depending on the use to which powder composition will be applied, the TPU composition MFI is often considered when selecting a TPU. Generally, according to the exemplified uses described below, it is desirable for a TPU to have an MFI of at least about 8 g / 10 minutes when tested according toASTM D1238 at 190 ° C and a weight of 2.16 kilograms. In other embodiments, it is desirable for a TPU to have a MFI of at least about 10 g / 10 minutes when tested according to ASTM D1238 at 190 ° C and a weight of 2.16 kilograms. In other embodiments, it is desirable for a TPU to have a MFI of at least about 12 g / 10 minutes when tested according to ASTM D 1238 at 190 ° C and a weight of 2.16 kilograms.

BASF Corp. (Wiandotte, MI) and other chemical companies offer a wide variety of TPUs suitable for use in the invention. An exemplary line of TPU types is available from BASF Corp. under the trademark ofELASTOLLAN.

Although commercial sources of TPUs that have a preferred MFI in the preferred range are available, TPUs that have a lower MFI can also be used as the base TPU. In order to sufficiently increase the MFI to a desired level, however, small amounts of water may be injected into an extruder containing the molten TPU. Addition of water in this manner causes the molten main structure of the TPU polymer to undergo chain incision, which reduces the molecular weight and increases the MTP doTPU. The incision of the chain in this manner can be further accelerated by increasing the temperature and speed of the extruder thread as soon as it is used. However, in order to prevent the increase in TPU MFI in this manner to a level that negatively impacts the physical properties resulting from the article formed thereof, other methods and materials are typically preferred.

Generally, the prepared or supplied TPU base will be provided in an unpowdered form (e.g. as pellets or granules). Thus, the base TPU and other optional components described below are formed into a powder after mixing and prior to use. The process of powder formation is further described below.

Other Components

Other components may be included in the compositions of the invention to improve or obtain certain properties of the composition or components, such as the desired TPU base MFI. It should be understood that depending on the manufacturing method of the base TPU or the commercial source thereof, one or more additional components may already be present in the base TPU. If other desired components are not present, however, they may be added to the base TPU when preparing the inventive compositions.

These components include, for example, lubricants, flow agents, internal thermal stabilizers and others, photostabilizers, pigments (e.g. smoke black), antioxidants, plasticizers, fillers (eg talc and CaCO3), and adjusting agents (eg polyurea powders and various silicones). Those skilled in the art may, without due experimentation, select various components and various quantities of other desired properties.

For example, materials that reduce the porosity of a melt film of the composition during the formation of articles are beneficially added when the self-compositing MFI alone does not sufficiently minimize air trapping between the melt film and the surface on which it is formed. If too much air becomes trapped, aporosity will be apparent on the external surface of the article shape. In many applications, particularly those involving parts for consumer applications, very little porosity can be tolerated before the article is discarded for aesthetic reasons. When plasticizers may be added for this purpose, their use in certain applications should be minimized due to their tendency to migrate from the surface of the material (for example, often referred to as "flowering," a phenomenon that causes windscreen cloudiness when used on windscreen panels). negatively impact on the physical properties resulting from the articles prepared therein.

According to a preferred embodiment of the invention, at least one lubricant is incorporated into the composition in order to decrease porosity in resulting articles without the disadvantages associated with effecting lower porosity by increasing TPU1S with MFI alone. Another advantage of incorporating a lubricant into the composition is the ability to reduce or eliminate the need for using an external mold release agent during forming of molded articles.

In one embodiment, the compositions of the invention comprise up to about 5% by weight based on the total weight of the composition of at least one internal lubricant. For example, a composition comprising about 0.01 to about 1.0% by weight of distearyl monacid phosphate (e.g., AX-71, available from Asahi DenquaQUogio.QU., Tokyo, Japan, under the brand name). (based on the total weight of the composition was useful according to the invention). Although AX-71 was not marketed as an internal lubricant, it was found to be useful for this purpose. When TPU comprises an aliphatic chemical, it is generally less lubricating to obtain the same results as when the lubricant is used in conjunction with TPUs which comprises aromatic chemical.

According to another embodiment of the invention, at least one flow agent is incorporated into the composition in order to decrease the porosity in resulting articles without the disadvantages associated with effecting lower porosity by increasing MFI TPUs alone. For example, a composition comprising precipitated amorphous silicone (e.g., PS-200, available from Glassven C. OA., A Venezuelan company, under the trademark PIROSIL) may beneficially be used in accordance with the invention.

Compositions containing one or more of these optional components are capable of eliminating the above-mentioned flowering phenomenon with respect to plasticizers. Thus, in preferred embodiments, plasticizers and other components prone to such migration are excluded from or minimized in the inventive compositions. Such other components include certain antioxidants, amine hindered light stabilizers, UV stabilizers, and other compounds known to promote undesirable flourishing.

Compositions of the invention include powder composition mixtures comprising at least one low TPU and at least one other polymer. Such mixtures are provided in a pulverized form to facilitate their use in a variety of articles formed to processes that provide substantial benefits as discussed. For example, a preferred use involves the formation of an article using the same technique as the original HVIF. The optional components described above may also be included within the mixtures of the powder composition of the invention to obtain desired properties and facilitate efficient processing of the compositions as desired. The final mixture may also be referred to as an "alloy" when a single phase phase is obtained.

In one embodiment, the inventive powder composition mixtures include at least about 10% by weight based on the total weight of the composition of at least one polymer with the exception of TPU. It has been found, for example, that a mixed powder composition comprising% of about 10 tpp weights and up to about 90 weight polyvinyl chloride (PVC) based on the total weight of the composition is useful in providing materials with improved properties. The PVC method in blends of the powder composition of the invention provides a relatively inexpensive material with improved properties over PVC alone. When a powder composition is prepared according to one embodiment of the invention, the base TPU component is present in an amount of from about 5 to about 50% by weight based on the total composition. In progressively preferred embodiments, the base TPU component is present in amounts of from about 10 to about 30 wt% or from about 15 to about 25 wt% based on the total weight of the composition. The remaining components include PVC and other optional components.

A particular preferred component for the inclusion in certain embodiments of the inventive powder composition mixtures is melt processable with the advanced rubber available from the polymer alloy of Ferro Corp. (Wilmington, DE) under the tradename ALCRIN. Melting may be present in the compositions in an amount of from about 5 to about 50% by weight based on the total weight of the composition. In further embodiments, a melt processable rubber may be present in the compositions in an amount of from about 10 to about 40% by weight based on the total weight of the composition. In further mobile embodiments, such melt processable rubber may be present in the compositions in an amount of from about 15 to about 30% by weight based on the total weight of the composition.

The combination of TPU and PVC in the original composition of the powder mixes results in materials with improved defect modalities compared to those materials which essentially consist of PVC. PVC typically exhibits a fragile failure mode, but PVC and dopu blends have been found to exhibit a more ductile failure mode. It is preferred to use materials with ductile failure modalities in many applications. The passenger compartment bag applications are an example of those applications where the use of materials with increased brittleness is desirable. When materials exhibiting brittle fluff are used to prepare air bags, air bags tend to break when used at more low temperatures (eg, especially those temperatures less than -40 ° C). Thus, in order to effectively employ airbags in colder climates, improved materials were desired.

The powder composition blends of the invention offer such improved materials. The compositions of the invention are successfully able to pass the rigorous tests imposed by vehicle manufacturers with respect to airbag materials.

Powder Formation

The powder compositions of the invention are prepared such that they have an average particle size distribution and particle size distribution according to the desired method of use and processing for the prepared articles thereof. A variety of particle sizes can be prepared. In an exemplary embodiment, the powder compositions of the invention have an average particle size of about 80 μm to about 300 μm. In a further mode, the average department size is at least about 100 μπι, or at least about 200 μπι even in further movable modes.

Particle analysis can be performed using all appropriate equipment and methods according to those skilled in the art. In certain applications, the particle size distribution is preferably one-modal, as this distribution is illustrated in FIGURE 1. According to the particle size distribution in FIGURE 1, 50% of the selected particles were about 128 μιη or less and 95% in size. of the selected particles had a size of about 253 μπι or demons. In other applications, the particle size distribution is preferably bi-modal, as shown in FIG. 2. According to the particle size distribution in FIG. 2, 50% of the selected particles had a size of about 230 µm or less and 95%. of the selected particles had a size of about 423 μηι or less. Particle size distributions illustrated in FIGURES 1 and 2 were obtained using well known methods and available particle analysis equipment from Microtrac, Inc. of Montgomeriville, AL.

The components of the composition are mixed first in the proportional amounts selected according to the desired total form and intended use. It is during mixing of the base TPU that water may optionally be injected into the mixture in a sufficiently small amount (for example, generally a trace amount of water will suffice for this purpose) to increase the TPU MFI when desired.

Where it may not be necessary to premix the components of the composition prior to transformation into a powder, those components requiring such transformation are preferably mixed prior to forming into a powder. Alternatively, although not desired due to efficiency, the composition may be formed. by stepsmixing and forming multiple powders.

In order to obtain a substantially uniform mixture of base TPU and optional components, mixing may occur in the presence of heat and / or pressure. For example, components may be mixed in an extruder by withdrawing the extruder through a pelletizer. Once processed in this manner, pellets as soon as formed can be transformed into a powder of the desired particle size and distribution.

In order to transform the blended composition into a powder of the desired particle size and distribution, any suitable opposites forming the technique may be used. For example, a powder may be prepared from the mixed composition using mechanical techniques such as grinding or cryogenic hammer milling.

Note that a single pass with a moendocrogenic process is generally not sufficient to prepare a pulverized composition of the desired particle size distribution for later uses including the HVIF technique described below. While other powder forming techniques may be used and may be more efficient, cryogenic milling followed by selecting and recycling steps may be used to achieve the desired particle size distribution. See also U.Sno patent. 5,597,586, which discloses a method for transforming a composition into a useful powder-like form using water micropelleting. In addition, U.S. Patent No. 5,654,102 discloses a method for transforming a composition into microspheres of an appropriate size for certain applications such as slurry molding.

FIGURE 3 illustrates an exemplary embodiment of a process for preparing inventive powder compositions. The details and variations with respect to the stages and equipment illustrated therein are well known to those skilled in the art.

As shown in FIGURE 3, first a high intensity mixer 10 (for example, the variable speed Henschel type mixer, such as those available from the Japanese company of Mitsui) operating at a temperature of 120 ° C to 140 ° C is provided around about for the initial mix steps. The high intensity mixer 10 is charged with a mixture of daTPU base 12 and other desired components for the particular application (e.g., lubricants, flow agents, stabilizers, pigments, and the like) desired. Optionally, promote other desired components 14 for the particular application. They are then added to the high intensity mixer 10 after being preheated (e.g., in certain embodiments, the plasticizers may be added after being preheated to a temperature of about 80 ° C to about 90 ° C).

The mixture is then transferred from the high intensity mixer 10 to a low intensity mixer 16 (e.g., a refrigerating Henschel type mixer operating at a speed of about 110RPM) which simultaneously cools the mixture. If a mixture of the powder composition is being formed, another polymer 18 (e.g. polyvinyl chloride) may be added to the mixture while being processed in the low intensity mixer 16. When the mixture reaches a temperature of about 50 ° C which can be discharged to a 20 funnel so that further processing ends the dry mixing operations 22.

From the funnel 20, the mixture is run through a sieve 24 (for example, a vibrating sieve having a 10-mesh screen, such as a Sweco type sieve. All oversize components 26 are discarded with the remaining components being transferred to each other). a receptacle 28 where they remain in the form of a dry powder until transferred to an extruder 30 (e.g., a twin screw extruder such as a Leistritz 27-mm co-rotating extruder which theme designation MIC 27 GL / 40D) to match the melt (for example, at a temperature of about 180 ° C and a speed of about 350 RPM) followed by the remaining extrusion operations 32. Optionally, water can be injected into the extruder to aid in the material MFI control as desired. 30, passes through a water cooler 34 and then to a pelletizer 36 (for example, a pellet equipped with a gutter, such as those available from Conair Group Inc. of Pittsburgh, PA). Material withdraws from the doppler 36 in pellet form 38.

The pellets 38 are then subjected to moendrocryogenic operations 40. First, the pellets 38 are cooled in liquid nitrogen 42 and then transferred to a friction mill 44 (for example, as available Midwest Elastomers, Inc. De Wapaquoneta, OH). . From friction mill 44, the frets are then run through a first cyclone separator 46 to a sieve 48, which allows the transfer of particles of a desired size to a second cyclone separator 50. Large particles 52 are returned to liquid nitrogen 42 for grinding. additional. On the way to the second cyclone separator50 the selected composition can be heated using, for example, dry forced air. Finally, the resulting powder composition 54 removes the second cyclone separator 50 where it is stored until it is packaged or used to form a prepared powder composition 54 article.

Uses

The TPU compositions of the invention may be used to form to a variety of articles. Advantageously, the inventive compositions are capable of providing improved surface coatings in many prepared articles thereof. For example, due to the relatively uniform and small departmental size of certain embodiments of the powdered compositions of the invention, the shaped polymeric pellets also often have few surface imperfections compared to those prepared from other compositions.

As such, a first exemplary use of the inventive compositions involves high speed impact fusion (HVIF). This technique facilitates the formation of the skin polymer using formulations of the invention. In this mode using HVIF techniques, the TPU powder composition preferably has a medium particle size corresponding to the particle size distribution of FIGURE 1. The result size particles are menortypically wasted because they are not often able to reach the target substrate during HVIF processing. It is designed for use with particles of a large size, so their exclusion is preferred. It is noted that the particle size distribution for compositions used in HVIF processes is relatively single-modal.

According to the HVIF technique, the composition is then heated and then sprayed onto a mold surface to form an article. In one embodiment, the composition is heated to the melting point using a warm hydrogen or oxygen environment. Fluidized once this way, the composition is directed to a substrate (e.g., nickel plated steel) maintained at about room temperature. Once the composition comes to rest on the substrate, it cools to form the article. In an exemplary embodiment, the article is a continuous, continuous film (e.g., a polymeric skin). In certain embodiments using the HVIF technique, the surface of the textured molding in order to give a desired surface coating to an article. For example, the surface of the mold may texturize to appear leathery to prepare items such as instrument panels, armrests, headrests, door panels, and other items in vehicle passenger's compartments.

An exemplary commercial source of useful equipment for this HVIF technique is the Weidman Company, Inc. in Ft.Miers, Florida. Further details of one embodiment of this technique are described, for example, in patent no. US 5,285,967, which is attributed to Weidman Company, Inc. and discusses High Speed Oxygen Fuel (HVOF) spraying techniques and associated equipment. As described herein, HVOF employs a continuous combustion procedure that produces output gas velocities of up to about 1,200 - 1,500 meters / second (4,000 - 5,000 feet / second). To produce gas that has this exit velocity, a fuel gas such as propylene or hydrazine and oxygen under high pressure at about 0.4 - 0.6 MPa (60 to 90 pounds per square inch) is burned in an internal combustion chamber. . The hot discharge of the combustion chamber exhaust gases through the exhaust ports expands into a prolonged nozzle where it meets the spray composition, which is fed into the nozzle with an inert gas such as nitrogen and confined by the exhaust gas stream. The spray composition misses it and removes the nozzle into a high-speed jet stream that is about 9decimeters (36 inches) long and has a fencing stream diameter of 1.2 centimeters (1/2 inch). Using statistics, a sufficiently dense composition coating is capable of being produced with properties superior to those obtained using other techniques.

Other uses of the compositions of the invention for forming articles involve conventional powder coating techniques including fluidized bed, electrostatic spray, and thermal spray techniques. Other uses include conventional molding techniques such as mud molding and rotational molding.

According to the fluidized bed technique, the desiccated metal parts are immersed in a ventilated pulverized composition bed. The powder melts in the heated part, resulting in a smooth continuous film encapsulating the metal. This process occurs in what is referred to as "a fluidized bed." The fluidized bed has three main sections: (1) an upper powder funnel where it is held, (2) a porous plate that allows it to fully plow it, and (3) a sealed lower tube. When pressurized air is fused into the air chamber, it passes through the plate and causes the powder to float or "fluidize". This fluidization allows the metal part to be coated and moved through the powder with little resistance during the dipping process. Alternatively, a cold substrate may be processed on a bed of fluidized departments that are tribo-charged and thus resonate with the substrate. The coated substrate may then be passed through a heated zone, or narrowed, to melt the coating.

According to the electrostatic spray technique, the spray composition is dispersed in an air stream and passed through a field of corona discharge. In the camp of the corona discharge, the dust acquires an electrostatic charge. The charged powder is attracted to and then deposited on the grounded substrate. The substrate, usually electrostatically coated at room temperature, is then placed in an oven where the powder melts and forms a coating.

Known thermal spray processes are characterized by their heating method. Those employing chemical combustion heating include powder flame spraying. Those employing electric heating include spraying the doplasm flame. Of these processes, plasma spraying of the flame plays a predominant role.

Plasma flame spraying is a process whereby the deposition of a largely molten material is allowed using a highly directional gas stream. Plasma, an ionized gas consisting of free electrons, positive ions, atoms, and molecules, is used as the heating means to pulverize the composition to a molten state at a high temperature (eg, about 15,000 ° C) using an electric arc. To generate the arc, a selected gas such as argon or denitrogen flows between an anode and a cathode. Between the anode and the cathode, an arc is generated in the gas flow, which heats and propels the composition to a substrate. Under an unobstructed collision, the heat of the composition melts to form a coating.

In contrast to the plasma flame spraying technique, conventional low open velocity pulverized flame spraying utilizes combustion as a means of heating the powder. The pulverized composition, combustion air, and fuel are delivered to an open mixing combustion chamber where it ignites. Ignition of the fuel and gas mixtures melts the composition, which is then charged from the combustion chamber by air to provide a coated substrate. Due to the lower velocity of the composition that collides with the substrate in this method compared to the HVIF technique described above, the resulting coatings often have insufficient deletion force and do not lend themselves to repeatable high production processes.

The mud mold utilizes an open end design of the mold forming articles (eg vehicle instrument panels). In this embodiment, the TPU powder composition preferably has a larger particle size than that preferred for use with the HVIF technique. For example, compositions with an average particle size corresponding to the particle size distribution illustrated in FIGURE 2 may be used. In this embodiment, the particle size distribution of the compositions used in this process need not be relatively single-modal as is the case with those compositions used in the HVIF process described above. Instead, the bi-modal particle size distributions can be used, such as those obtained. cryogenic grinding of TPU.

Rotational molding is another technique for forming articles (for example, armrests and headrests in passenger compartments of vehicles as well as other objects such as recreational balls). Compared to the mud mold, the rotational molding process operates on a rotary molded design using a closed design axis. Further, while a bi-modal particle size distribution may also be used when rotating the mold, the distribution is typically a larger average particle size than that used for the mud mold.

According to either of the above method or another suitable for the formation of articles using spray formulations, articles are formed from the TPU and TPU powder composition mixtures of the invention. Integrally improved spray compositions of the invention with processing techniques such as the HVIF technique, top articles are made possible. Such articles are useful for not only meeting the needs of industries such as those involving the manufacture of polymeric articles used in passenger compartments of vehicles.

Other embodiments and applications of the invention are described in the following non-limiting examples.

EXAMPLESExample 1

A base TPU was obtained from a commercially sourced ELAS TOLLAN LJ 56/187 registered source (BASF Corp. deWiandottef MI). When tested according to ASTM D123 8 at 190 ° C and a weight of 2.16 kilograms, the base TPU MFI was measured to be 55 g / 10 minutes. When tested according to ASTM D1238 at the lowest temperature of 170 ° C and the same weight of 2.16 kilograms, the base TPU MFI was measured to be 27 g / 10 minutes.

In a high intensity blender, the TPU basefo was mixed with an internal lubricant (distearyl demonic phosphate, AX-71, available from Mie Amfine Chemical, from Japan), and a pigment (smoke black, available from Cabot Corp. Boston, MA, under the registered trademark REGAL). The high intensity mixer was operated at a temperature of about 1200 ° C to about 140 ° C. The mixture was then transferred from the high intensity blender to a low intensity mixer operating at a fencing speed of 110 RPM to simultaneously mix and cool the mixture. When the mixture reached a temperature of about 50 ° C, it was discharged to a funnel and then operated through a sieve. The selected particles were then fed to a twin screw extruder operating at a temperature of about 1800 ° C and a speed of about 350 RPM. After removing the extruder, the mixture was passed through a water cooler and a pelletizer to form the pellets. The pellets were then subjected to cryogenic milling operations.

Once the powder was formed, a flow agent (PS-200, available from Glassven CA, a Venezuelan company, under the trade name PIROSIL) was mixed with the powder in an amount of 0.15% based on the total amount of the powder. composition. In the composition thus formed, the amount of the base TPU was 99.05%, the internal delubricant amount was 0.30%, and the amount of pigment was 0.50%, all weight percentages based on the total weight of the composition.

Example 2

In a high intensity mixer, a base TPU (ELASTOLLAN LJ 56/187, available from BASF Corp. deWiandotte, MI) was mixed with an internal lubricant (distearyl mono acid phosphate, AX-71, available from Amfine Chemical from Mie, Japan), and a pigment (carbon black dispersion, available from Avi Lake PoliOneCorp., OH, under the trade name of STAN-TONE HCC-20327 BLACK). The mixture was processed to form a powder composition as described in reference to example 1. In the powder composition thus formed, the amount of base TPU was 98.2%, the internal delubricant amount was 0.2%, and the amount of pigment 1.6%, all weight percentages that are based on the total weight of the composition.

Example 3 The process described with reference to Example 1 and FIGURE 3 was used to form a mixture of the empo composition. The powder composition mixture was formed from 30.0% TPU base (ELASTOLLAN LJ 56/187, available from BASFCorp. De Wiandotte, MI), 0.1% internal lubricant (distearyl mono acid phosphate, AX -71, available from Amfine de Mie, Japan), 33.3% Polyvinyl Chloride Resin Dispensation (SUSP RESIN 20 0F (DPQU), Available from Oxi Vinyls Corp. Parks, TX), 1 % Mixed Stabilizer (CPS507, Available from Amfine deHopquinsvilie Chemicals, QUI), 0.1% Fatty Acid Ester (LS-10, Available from Mie Amfine Chemicals, from Japan), 0.9% Phosphite Stabilizer (CPL-1551 D, Available from Hopquinsville Amfine Chemical, QUI), 2.8% Pigment Dispersion (VM6432 9779 MD GRAYMB, Available from Lake Avon, OH PolyOne Corp.), 28, 1% dispersible trimellitate n-octyl plasticizer (SINPLAST NOTM ELECTRIC, available from Sinergistics of St.Remi, Canada), and 3.3% cl polyvinyl orifice (VINNOLITP70, available from Vinnolit from Ismaning, Germany). All weight percentages are based on the total weight of the composition.

Example 4

The process described with reference to example 1 and FIGURE 3 was used to form a mixture of the powder composition. The powder composition blend was formed of 30.0% low TPU (ELASTOLLAN LJ 56/187, available from BASF Corp.de Wiandotte, MI), 0.1% internal lubricant (distearyl demono phosphate, AX-71, available from Mie, Japan Amfine Chemical), 32.5% Polyvinyl Chloride Resin Suspension (SUSP RESIN 200F (LVL), Deer Oxi Vinyls Corp. Available Parks, TX), 0.1% Stabilizer (CPS 507, Available from Hopquinsville Amfine Chemicals, QUI), 0.1% Fatty Acid Ester (LS-10, Available from Amfine Mie Chemicals from Japan), 0.7% Phosphite Stabilizer (CPL- 1551 D, available from Hopquinsville Amfine Chemical, QUI), trimelitate n-octyl resin plasticizer dispersion pigment (642H V DQU PEWTER 0928189 MB, available from Avon Lake PoliOne Corp., 0H) , 30.2% (SINPLAST NOTMELETRIC, available from Sinergistics of St. Remi, Canada), and 3.9% polyvinyl chloride (V INN0LIT P70, available from Vinnolit de Ismaning, from Germani). All dope percentages are based on the total weight of the composition.

The various modifications and alterations of the invention will become apparent to those skilled in art without departing from the spirit and space of the invention, which is defined by the accompanying claims. It should be noted that the steps set forth in all claims of the passionate method necessarily need to be performed in the order presented. Those of ordinary skill in the art will recognize variations in performing the steps in the order in which they are presented.

Claims (10)

1. Thermoplastic powder composition, characterized in that it comprises: at least one thermoplastic polyurethane having a melt index of at least about 8 g / 10 minutes when tested according to ASTM D1238 at 190 ° C and a weight of 2.16 kg. at least one internal lubricant in an amount of up to about 5% by weight based on the total weight of the composition; and optionally at least one flow agent, whereby the powder has a unimodal particle size distribution. Thermoplastic powder composition according to claim 1, characterized in that the thermoplastic polyurethane comprises polyether based polyurethane, polyester based polyurethane, aromatic polyether based polyurethane, or aliphatic polyester based polyurethane thermoplastic. Thermoplastic powder composition according to claim 1, characterized in that it further comprises at least one selected component of thermal stabilizers, photostabilizers, pigments, antioxidants, plasticizers, fillers, and adjusting agents. 4. Thermoplastic powder composition, characterized in that it further comprises at least one other polymer, whereby the other polymer comprises more than about 10% by weight of the total composition to form a mixture. Thermoplastic powder composition according to Claim 4, characterized in that the other polymer comprises polyvinyl chloride in an amount up to about 90% by weight of the total composition. Thermoplastic powder composition according to Claim 5, characterized in that it still comprises a melt processable rubber. Article, characterized in that it is prepared from the powder composition of claim 1 or the mixture of the powder composition of claim 4. A process for preparing the thermoplastic powder composition of claim 1, characterized in that it comprises the steps of: providing the thermoplastic polyurethane, mixing the thermoplastic polyurethane with one or more optional components; and transform the thermoplastic polyurethane and optional powder components having a unimodal particle size distribution. Process according to Claim 8, characterized in that it further comprises reducing the molecular weight of the thermoplastic polyurethane by injecting water into an extruder at a location where the thermoplastic polyurethane is melted to increase the melt index of the thermoplastic polyurethane to at least about -8 g / 10 minutes when tested according to ASTM D123 8 at-190 ° C and a weight of 2.16 kg. Process for preparing an article from the thermoplastic powder composition of claim 1, characterized in that it comprises the steps of: providing the composition with thermoplastic powder; forming the article of the thermoplastic powder composition using a high speed impact melt technique.