Pigmented thermoplastic material, method for the production and use

• US 20070191511A1
• Filed: 11/03/2006
• Published: 08/16/2007
• Est. Priority Date: 11/04/2005
• Status: Active Grant

• Current Assignee: Heubach GmbH
• Original Assignee: Heubach GmbH
• Inventors: Heubach, Rainer, Maratta, Gerald
• Granted Patent: US 7,892,461 B2
• Time in Patent Office: Days
• US Class Current: 523/333
• CPC Class Codes: C08J 3/226 using a polymer as a carrier

Abstract

Description of a method for the production of a pigmented thermoplastic material. The method characterizes that during a first step an aqueous suspension presenting a solid matter contents of approximately 10 to 75% by weight, containing at least one flow enhancer in form of dissolved salt and the pigment, is ground under alkaline conditions in a high energy charging mill by means of grinding bodies having a diameter of 0.2 to 2 mm, and the obtained grinding product is transformed during a second step with a thermoplastic material into the pigmented thermoplastic material by means of a flush process performed by a kneader or extruder, at increased temperature and a pH value of initially 7 or less. In addition, the invention concerns a pigmented thermoplastic material produced according to said method, as well as beneficial applications for production of transparent molded bodies, in particular of fibers, foils, injection moldings and extruded parts. The invention-specific method provides pigmented plastic material which can reliably be processed into high quality products. Foils which are produced accordingly are, for example, free from coloration defects.

Claims

1. Method for the production of a pigmented thermoplastic material, characterized in that in a first step an aqueous suspension, presenting a solid matter contents of approximately 10 to 75% by weight, which contains a flow enhancer in form of a dissolved salt and the pigment, is ground under alkaline conditions in a high-energy feed mill with grinding bodies having a diameter of 0.2 to 2 mm, and the obtained grinding product is converted from. a thermoplastic material into the pigmented thermoplastic material during a second step, making use of a flush process performed in a kneading device or extruder, at increased temperature and a pH value of initially 7 or less.

2. Method according to claim 1, characterized in that the pH-value is adjusted during the second step to approximately 2 to 6, in particular to 2.8 to 4.5.

3. Method according to claim 2, characterized in that the pH-value is adjusted toward the end of the second step to approximately 8 to 10 by means of a base, in particular to approximately 8.5 to 9.5 in order to remove incorporated excess species in water-soluble form.

4. Method according to claim 1, characterized in that a kneading device is utilized in the second step, in particular a heatable twin shaft kneader, and the grinding product from the first step is introduced in several charges into the kneader, whereby after each charge, with onset of phase separation, the excess aqueous phase is decanted.

5. Method according to claim 4, characterized in that the temperature of the material contained within the kneader is raised in order to remove in particular any remaining, more difficult to dissolve, interfering substances from the pigmented thermoplastic material.

6. Method according to claim 1, characterized in that during the second step, or the flush process, the temperature is adjusted to 100°

C. or below, in particular to approximately 85 to 95°

C.

7. Method according to claim 1, characterized in that as thermoplastic material, polyethylene (PE) is used, in particular high pressure polyethylene (HDPE) or low pressure polyethylene (LDPE), polypropylene (PP), polyvinyl-chloride (PVC), ethylene-methacryl acid ester co-polymer (EMA), polystyrene (PS), polyacryl-nitrile (PAN) or polyester (Diolen®

).

8. Method according to claim 1, characterized in that the flush process is performed with use of a kneader, under reduced pressure, in particular without pressure.

9. Method according to claim 1, characterized in that during the first step an untreated crude pigment is used.

10. Method according to claim 1, characterized in that an organic pigment is employed as pigment, in particular in form of phthalocyanine-, quinacridon-, perylene-, perinon-, anthraquinon, amino- and hydroxyl-anthraquinon-, indathron-, flavanthron-, anthranthron-, isoviolanthron-, di-ketopyrrolophyrrol-, dioxazin-, thioindigo-, quinophthalon-, isoindolinon- and isoindolin pigments, quinoxalindion- and benzimidazolon- Azo-pigments and phthalimidylazo-pigments, disazo-pigments, in particular diarylid-, bisacetoacetarylid, disazopyrazolon- or disazo-condensation pigments, azo pigments in particular β

-naphthol pigments, naphthol AS-pigments, monoazo-yellow pigments, metal complex pigments and/or triphenylmethane salt pigments and/or mixtures, composites and crystalline mixed phases (“

solid solutions”

) of these pigments.

11. Method according to claim 1, characterized in that the solid body percentage is adjusted during the first step to approximately 30 to 75 percent by weight, in particular to approximately 50 to 75% by weight.

12. Method according to claim 1, characterized in that during grinding in the first step, the particle size of the pigment is adjusted to smaller than 150 nm, in particular smaller than 120 nm.

13. Method according to claim 1, characterized in that one or several of the following compounds are employed as flow enhancers during the first step:

sodium lauryl sulfonate, in particular jointly with a de-foaming agent for adjustment of desired surface tension, modified sunflower oil (Edenor ES), in particular in interaction with an oil such as mineral oil PKWF, fatty acid sodium salt DT30, sodium salt of oleic acid, azelaic acid, in particular in interaction with an oil, such as mineral oil PKWF, Dresinate (saponified colophonium resin, containing Na-salt of the dehydro abietic acid) in particular in interaction with a mineral oil PKWF, in particular with use of organic pigments, as well as naphthaline formaldehyde-sulfonate condensate and/or melamine-formaldehyde-sulfonate condensate, in particular with use of inorganic pigments.

14. Method according to claim 1, characterized in that esters and glycerides are used for method optimization, which are hydrolyzed in controlled fashion by managing the pH value during the process and are thus being modified in their effect, in particular palmic acid glyceride, stearic acid glyceride, triglycerol di-isostearate and/or ethyllinoleate.

15. Method according to claim 1, characterized in that further adjuvants for control of process are utilized, in particular agents enhancing the affinity between pigment and lipophile phase or the deformability of the thermoplastic material, in particular acenaphthene, mesitylene, xylene, naphthaline, solvent facilitators, in particular 2-methyl-1-propanol, cyclo-hexanol and/or cetyl-alcohol, as well as various oils jointly with employed fatty acids, in particular in form of mineral oil PKWF, linseed oil and hydrated oil of ricinus.

16. Method according to claim 1, characterized in that flow enhancers in the aqueous suspension are adjusted during the first step to a concentration of 0.2 to 20% by weight, in particular to 2 to 10% by weight.

17. Method according to claim 1, characterized in that part of the thermoplastic material to be pigmented is already ground together with the pigment in the ball mill during the first step to a common average grain diameter of 20 to 200 nm, in particular of 80 to 150 nm, with a half value width of grain distribution below 50 nm.

18. Method according to claim 1, characterized in that use is being made of a crude, not as yet pigmentary application-ready pigment or highly amorphous pigment or mixtures of several of such type of crude pigments.

19. Method according to claim 1, characterized in that the pigment concentration in the aqueous suspension during the first step is adjusted in such manner that with addition of the thermoplastic material during the second step, 1 part by weight of thermoplastic material is allotted approximately 0.2 to 4 parts by weight, in particular approximately 1 to 3 parts by weight of pigments:

20. Pigmented thermoplastic material, obtainable by a method according to claim 1, wherein the therein contained pigments present an average grain diameter below 200 nm, in particular less than 150 nm, with a half value width of grain distribution of less than 80 nm.

21. Pigmented thermoplastic material according to claim 20, characterized in that the average grain diameter of the pigments, with a half value width of grain distribution of less than 50 nm, amounts to less than 100 nm.

22. Application of the pigmented thermoplastic material according to claim 20 for the production of transparent molded bodies, in particular of fibers, foils, injection moldings and extruded pieces.