Thermoplastic Composition

The invention relates to a composition containing a particulate solid, a plastic material (such as a thermoplastic polymer) and a hydrogenated vegetable oil wax. The hydrogenated vegetable oil wax is capable of being a dispersant.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a composition and use as disclosed herein above.

Hydrogenated Vegetable Oil Wax

The hydrogenated vegetable oil wax may be chemically modified, or un-modified. A chemically modified hydrogenated vegetable oil wax may contain amide functionality, imide functionality, whole or partial salts (typically of an ammonium counterion or metal such as alkali or alkaline earth metals). In one embodiment, the hydrogenated vegetable oil wax may not be amide-functionalised. Typically, the hydrogenated vegetable oil wax may be un-modified.

The hydrogenated vegetable oil wax may be a vegetable derived wax, or mixtures thereof. The hydrogenated vegetable oil wax may be solid at room temperature and melts at 50° C. or higher. The melting point may be 50° C. to 80° C. The hydrogenated vegetable oil wax may have an iodine number of up to 7 or less than 7. The hydrogenated vegetable oil wax may contain triglycerides of fatty acids.

The hydrogenated vegetable oil wax may be a derived wax that may include arrayan wax, carnauba wax, sugar cane wax, candelilla wax or hydrogenated castor oil. The hydrogenated vegetable oil wax may be a derived wax that may include candelilla wax or hydrogenated castor oil. In one embodiment, the hydrogenated vegetable oil wax may be hydrogenated castor oil wax, or mixtures thereof.

The hydrogenated vegetable oil wax may be employed alone as a dispersant in the composition disclosed herein.

The hydrogenated vegetable oil wax may be employed as a dispersant in a mixture with at least one additional dispersant known in the field of solid plastic material.

INDUSTRIAL APPLICATION

In one embodiment, the hydrogenated vegetable oil wax, as described herein, is a processing aid or dispersant.

The particulate solid present in the composition may be any inorganic or organic solid material.

The solid particulate may be an organic pigment, an inorganic pigment, an organic filler, an inorganic filler, a flame retardant, or mixtures thereof.

The solid particulate may be an inorganic pigment, an inorganic filler, a flame retardant, or mixtures thereof. In one embodiment, the particulate solid is a pigment.

The solid particulate may be an organic pigment, an organic filler, or mixtures thereof.

In one embodiment, the particulate solid is an organic pigment from any of the recognised classes of pigments described, for example, in the Third Edition of the Colour Index (1971) and subsequent revisions of, and supplements thereto, under the chapter headed “Pigments”.

Examples of other inorganic pigments include metallic oxides such as titanium dioxide, rutile titanium dioxide and surface coated titanium dioxide, titanium oxides of different colours such as yellow and black, iron oxides of different colours such as yellow, red, brown and black, zinc oxide, zirconium oxides, aluminium oxide, oxymetallic compounds such as bismuth vanadate, cobalt aluminate, cobalt stannate, cobalt zincate, zinc chromate and mixed metal oxides of manganese, nickel, titanium, chromium, antimony, magnesium, cobalt, iron and aluminium, Prussian blue, vermillion, ultramarine, zinc phosphate, zinc sulphide, molybdates and chromates of calcium and zinc, metal effect pigments such as aluminium flake, copper, and copper/zinc alloy, pearlescent flake such as lead carbonate and bismuth oxychloride.

The solid plastic material may be a thermoplastic resin, or mixtures thereof. The thermoplastic resin may be a homopolymer, or a copolymer. In one embodiment, thermoplastic resin includes polyolefins (homopolymers or copolymers), polyesters, polyamides, polycarbonates, polyurethanes, polystyrenics, poly(meth)acrylates, celluloses and cellulose derivatives. Said compositions may be prepared in a number of ways but melt mixing and dry solid blending are typical methods.

The compositions, typically, contain from 1 to 95% by weight of the particulate solid, the quantity depending on the nature of the solid and the relative densities of the solid and the plastic material. For example, a composition in which the solid is an organic material, such as an organic pigment, in one embodiment contains from 15 to 60% by weight of the solid whereas a composition in which the solid is an inorganic material, such as an inorganic pigment, filler or extender, in one embodiment contains from 40 to 90% by weight of the solid based on the total weight of composition.

The composition may be prepared by any of the conventional methods known for preparing thermoplastic compounds. Thus, the solid, the thermoplastic polymer, and the dispersant may be mixed in any order, the mixture then being subjected to a mechanical treatment to reduce the particles of the solid to an appropriate size, for example, by Banbury mixing, ribbon blending, twin-screw extrusion, twin-roll milling, compounding in a Buss co-kneader, or similar equipment.

In one embodiment, the composition of the invention further includes one or more additional known dispersants.

In one embodiment, the invention provides for a micronised composition as is described herein. In one embodiment, the particle size (volume average) fraction may be 50 nm to 1 mm diameter, or 100 nm to 0.5 mm.

Another use of the hydrogenated vegetable oil wax of the present invention is in the production of dispersible solids in powder particle and/or fibre particle form, particularly of dispersible pigments or polymeric fillers, where the particles are coated with the dispersant. Coatings of this kind, of both organic and inorganic solids, are carried out in a known way, as described for example in EP-A-0 270 126. In this case, a solvent or emulsion medium may either be removed or remain in the mixture, forming pastes. These pastes are customary commercial products and may further comprise binder fractions and also further auxiliaries and additives. In the case of pigments, it is possible to coat the pigment surface during or after the synthesis of the pigments, by, for example, adding the hydrogenated vegetable oil wax of the invention to the pigment suspension, or during or after the operation of pigment finishing. The pigments pretreated in this way are notable for greater ease of incorporation and also for enhanced viscosity, flocculation and gloss performance and for higher colour strength, as compared with untreated pigments.

The composition comprising the hydrogenated vegetable oil wax and the plastic material may be formulated with the particulate solid in a similar manner to that described hereinbefore for the hydrogenated vegetable oil wax, and the plastic material. This composition may then be treated as a “master batch” and added to additional polymeric material when forming fabricated articles. The amount of “master batch” which is mixed with the additional polymeric material may vary over wide limits depending on the nature of polymeric material and the particulate solid. In different embodiments, the amount of “master batch” ranges include 0.1 to 50%, or 0.5 to 20%, or 1 to 5% based on the total weight of the final plastic article (typically thermoplastic). Although the plastic material used in preparing the “master batch” may differ from the addition of further plastic material, but typically it may be the same. The use of “master batches” is especially useful where the plastic material include polystyrene, high impact polystyrene (HIPS), styrene acrylonitrile styrene (SANS), polypropylene, polyethylene, polyethylene/polypropylene diene, ethyl vinyl acetate, polychloroprene, chlorinated polyethylene, chloro sulphonated polyethylene, poly(vinyl chloride), natural and synthetic rubber such as butadiene-based elastomers (for instance, butadiene-styrene, butadiene-acrylonitrile rubbers, polybutadiene), polyisoprene or natural rubber.

The following examples provide illustrations of the invention. These examples are non exhaustive and are not intended to limit the scope of the invention.

Examples

A series of thermoplastic compositions are prepared from high density polyethylene (HDPE). Comparative Example 1 (CE1) is a thermoplastic composition that contains no dispersant. Comparative Example 2 (CE2) is a polyethylene wax AC-16a commercially available from Honeywell, at 12 wt. % loading. Inventive Example 1 (IE1) contains hydrogenated castor oil wax at 12 wt. % loading.

Dispersant Evaluation Test 1: 60 parts of each agent are charged into a Henschel mixer with Heuco Green 600703K (Pigment Green 7, 200 parts) and LDPE pellets (Exxon Mobil LD600 240 parts). The materials are blended together for 60 seconds to form a premix. This premix is compounded through a Thermo Prism TSE16TC twin screw extruder, with a screen pack profile of 400/60 mesh. The temperature profile for the extruder zones is 60/130/140/160/160 from feeder to die. The pressure in bar behind the screen pack is recorded digitally. The pressure data, taken at 100 second intervals, is presented in the table below. The letters OP in the table indicate that the pressure behind the screen pack is greater than 100 bar, the over-pressure limit of the extruder. The results obtained are:

Dispersant Evaluation Test 2: The melt is prepared in a similar way as shown in Test 1. Then the coloured masterbatch (2 parts) is letdown with a white masterbatch (13.33 parts) (Plaswite PE7024 ex Cabot) containing 60% titanium dioxide and more letdown HDPE polymer (384.67 parts) (ex Borealis MG9641) using a Betol single screw extruder. The extruded pellets were collected and then injection moulded on a Boy 15S Injection Moulder into 50×35 mm plaques. The changes in colour strength of the plaques for each example versus the control are measured using the Spectroflash 600 spectrophotometer. The results obtained are:

Dispersant Evaluation Test 3: 84 parts of each agent are charged into a Henschel mixer with Irgalite Rubine 4BP (Pigment Red 57.1, 210 parts, ex BASF) and LLDPE pellets (Dowlex 2631 406 parts, ex Dow). The control contained 490 g of LLDPE powder and no dispersant. The agent IE1 was also tested at reduced dosage (56 parts), the weight of the formulation being made up by increasing the amount of LLDPE used (434 parts). The materials are blended together for 60 seconds to form a premix. This premix is compounded through a Thermo Prism TSE16TC twin screw extruder, with a screen pack profile of 400/60 mesh. The temperature profile for the extruder zones is 80/160/170/200/180 from feeder to die. Then the coloured masterbatch (16.67 parts) is letdown into LDPE polymer (183.33 parts) (ex Exxon LD600BA) using a Brabender Filtratest Unit with a temperature profile for the extruder zones of 180/190/200/200/200 from feeder to die and a melt volume throughput of 50 cm3/min. The filter pressure value, defined as the increase of pressure/gram of colourant, was calculated from the measurements taken according to the method described in DIN EN 13900-5.

Dispersant Evaluation Test 4: The masterbatch is prepared in a similar way, as shown in Test 3. Then the coloured masterbatch (0.67 parts) is letdown with a white masterbatch (3.33 parts) (Plaswite PE7024 ex Cabot) containing 60% titanium dioxide and more letdown LDPE polymer (96 parts) (ex Exxon LD605BA) using a Betol single screw extruder. The extruded pellets were collected and then injection moulded on a Boy 15S Injection Moulder into 50×35 mm plaques. The changes in colour strength of the plaques for each example versus the control are measured using the Spectroflash 600 spectrophotometer. The results obtained are:

Dispersant Evaluation Test 5: 84 parts of each agent are charged into a Henschel mixer with Irgalite Rubine 4BP (Pigment Red 57.1 210 parts, ex BASF) and PP powder (Elftex HV 001 PF 406 parts, ex Solvay). The control contained 490 g of LLDPE powder and no dispersant. The materials are blended together for 60 seconds to form a premix. This premix is compounded through a Thermo Prism TSE16TC twin screw extruder, with a screen pack profile of 400/60 mesh. The temperature profile for the extruder zones is 170/190/210/220/220 from feeder to die. Then the coloured masterbatch (3.33 parts) is letdown into PP polymer (196.67 parts) (ex Total Petrochemical PPH 5060) using a Brabender Filtratest Unit with a temperature profile for the extruder zones of 180/200/220/220/230 from feeder to die and a melt volume throughput of 50 cm3/min. The filter pressure value, defined as the increase of pressure/gram of colourant, was calculated from the measurements taken according to the method described in DIN EN 13900-5.

Dispersant Evaluation Test 6: The masterbatch is prepared in a similar way, as shown in Test 5. Then the coloured masterbatch (0.67 parts) is letdown with a white masterbatch (3.33 parts) (Plaswite PE7024 ex Cabot) containing 60% titanium dioxide and more letdown PP polymer (96 parts) (ex Total Petrochemical PPH 5060) using a Betol single screw extruder. The extruded pellets were collected and then injection moulded on a Boy 15S Injection Moulder into 50×35 mm plaques. The changes in colour strength of the plaques for each example versus the control are measured using the Spectroflash 600 spectrophotometer. The results obtained are:

Overall, the data obtained from the tests indicates that the compositions of the invention have acceptable performance after more than one thousand seconds. Accordingly, the composition of the present invention is capable of dispersing a pigment that also allows for a thermoplastic to have at least one of a reduction in aggregates and specks, provides a finer state of dispersion (for example, having a lower filter pressure value), has acceptable tinctorial strength, and has acceptable brightness and faster rates of dispersion.