WO2020076649A1

WO2020076649A1 - Talc-filled polyolefin compounds exhibiting low odor

Info

Publication number: WO2020076649A1
Application number: PCT/US2019/054820
Authority: WO
Inventors: Lily LIU; Doug LUNZ
Original assignee: Polyone Corporation
Priority date: 2018-10-08
Filing date: 2019-10-04
Publication date: 2020-04-16

Abstract

Thermoplastic compounds include non-visbroken polyolefin and mineral filler selected from talc having a median particle size from about (9) to about (11) microns. The compounds have an odor rating of less than about 3.3 according to VDA 270 B3 (without rounding down to a nearest half-grade of the odor rating) while also maintaining desirable physical and mechanical properties, which makes the compounds especially useful for molding thermoplastic articles for use as parts in automotive interiors, HVAC systems, and the like.

Description

TALC-FILLED POLYOLEFIN COMPOUNDS

EXHIBITING LOW ODOR

CLAIM OF PRIORITY

[0001] This application claims priority from both U.S. Provisional Patent

Application Serial Number 62/742,689 bearing Attorney Docket Number 12018027 and filed on October 8, 2018 and U.S. Provisional Patent Application Serial Number 62/742,774 bearing Attorney Docket Number 12018028 and filed on October 8, 2018, both of which U.S. Provisional Patent Applications are incorporated by reference.

FIELD OF THE INVENTION

[0002] This invention relates generally to thermoplastic compounds and thermoplastic articles molded therefrom. More particularly, this invention relates to talc-filled polyolefin compounds which exhibit low odor.

BACKGROUND OF THE INVENTION

[0003] Polyolefins are widely used to make thermoplastic articles in a variety of markets and end-use applications.

[0004] Advantageously, neat polyolefin resin can be compounded with mineral fillers such as talc to provide talc-filled polyolefin compounds which when molded into a thermoplastic article have enhanced properties, such as mechanical stiffness, impact strength, dimensional stability, and heat resistance, relative to those of a thermoplastic article molded from the neat polyolefin resin. Additionally, use of talc as a filler tends to reduce the cost of the thermoplastic article because the amount of polyolefin resin is correspondingly reduced.

[0005] Undesirably, however, talc-filled polyolefin compounds can exhibit malodors. Moreover, attempts to reduce the malodor by simply adjusting the levels of polyolefin resin and talc in a talc-filled polyolefin compound have been unsuccessful.

[0006] First, both the polyolefin resin and the talc are believed to be contributors to such malodors. Accordingly, because a decrease in the amount of talc typically necessitates an increase in the amount of polyolefin resin, any reduction in malodor resulting from the talc can be negated by corresponding an increase in malodor resulting from the polyolefin resin, and vice versa.

[0007] Second, any change in the amount polyolefin resin relative to the amount of talc can alter the physical and mechanical properties of the thermoplastic article molded from the talc-filled polyolefin compound. Thus, attempts to reduce the malodor can render a talc-filled polyolefin compound unsuitable for end-use applications which require certain physical or mechanical properties.

SUMMARY OF THE INVENTION

[0008] Consequently, a need exists for talc-filled polyolefin compounds which exhibit low odor while also maintaining desirable physical and mechanical properties when molded into a thermoplastic article.

[0009] The aforementioned needs are met by one or more aspects of the present invention.

[00010] One aspect of the invention is thermoplastic compounds as described herein.

[00011] Another aspect of the invention is thermoplastic articles molded from the thermoplastic compounds as described herein.

[00012] A further aspect of the invention is methods of making thermoplastic compounds as described herein.

[00013] An even further aspect of the invention is methods of reducing odor of thermoplastic compounds as described herein.

[00014] According to aspects of the invention, thermoplastic polyolefin compounds include non-visbroken polyolefin and mineral filler selected from talc having a median particle size from about 9 to about 1 1 microns. The compounds have an odor rating of less than about 3.3 according to VDA 270 B3 (without rounding down to a nearest half-grade of the odor rating) while also maintaining desirable physical and mechanical properties, which makes the compounds especially useful for molding thermoplastic articles for use as parts in automotive interiors, HVAC systems, and the like.

[00015] Features of the invention will become apparent with reference to the following embodiments. There exist various refinements of the features noted in relation to the above-mentioned aspects of the present invention. Additional features may also be incorporated in the above-mentioned aspects of the present invention. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the described aspects of the present invention may be incorporated into any other of the described aspects of the present invention alone or in any combination unless specifically described otherwise.

EMBODIMENTS OF THE INVENTION

[00016] In some embodiments, the invention is directed to thermoplastic elastomer compounds.

[00017] In other embodiments, the invention is directed to thermoplastic articles,

[00018] In further embodiments, the invention is directed to overmoldcd thermoplastic articles.

[00019] In even further embodiments, the invention is directed to methods of making overmolded thermoplastic articles.

[00020] Required and optional features of these and other embodiments of the present invention are described.

[00021] As used herein, the term“compound^** means a composition or mixture resulting from melt mixing, or compounding, a neat polymer and at least one other ingredient including but not limited to one or more additives, or one or more other polymers, or both.

[00022] As used herein, the term “free of’ a certain component or substance means, in some embodiments, that no amount of that component or substance is intentionally present, and, in other embodiments, that no functionally effective amount of that component or substance is present, and, in further embodiments, that no amount of that component or substance is present.

[00023] As used herein, the term“molded from" means, with respect to an article (or component of an article) and a thermoplastic material, that the article (or component of the article) is molded, extruded, shaped, formed, pressed, or otherwise made from the thermoplastic material under sufficient healing to enable such molding. As such, the term“molded from" means, in some embodiments, the article (or component of an article) can comprise, consist essentially of, or consist of, the material; and, in other embodiments, the article (or component of an article) consists of the material because the article (or component of an article) is, for example, made by an injection molding process.

[00024] As used herein, the term “odor rating” means the grade as determined according to VDA 270 B3 except that the grade is not rounded down to the nearest half-step grade; that is, as an exception to the specifications of VDA

270 B3, the unrounded grade is reported as the odor rating as used herein.

[00025] Thermoplastic Compounds

[00026] Some aspects of the invention are directed to thermoplastic compounds.

[00027] According to the invention, thermoplastic compounds include non-visbroken polyolefin and mineral filler selected from talc having a median particle size from about 9 to about 11 microns. By selecting specifically non- visbroken polyolefin in combination with specifically talc having a median particle size from about 9 to about 1 1 microns, it is possible for the thermoplastic compounds to achieve an odor rating of less than 3.3 according to VDA 270 B3 (without rounding down to a nearest half-grade of the odor rating), even when the thermoplastic compounds are free of any optional odor absorber. For certain end- use applications, an odor rating of less than 3.3 according to VDA 270 B3 (without rounding down to a nearest half-grade of the odor rating) can be sufficient.

[00028] In some embodiments, thermoplastic compounds further include optional odor absorber. By selecting specifically non-visbroken polyolefin in combination with specifically talc having a median particle size from about 9 to about 11 microns, and further including the optional odor absorber, it is possible for the thermoplastic compounds to achieve an odor rating of less than 3 according to VDA 270 B3 (without rounding down to a nearest half-grade of the odor rating).

[00029] Additionally, in some embodiments, thermoplastic compounds have volatile organic compound (VOC) emissions of about 25 mgC/g or less according to VDA 277. In further embodiments, thermoplastic compounds have volatile organic compound (VOC) emissions of about 20 mgC/g or less according to VDA 277.

[00030] Non-Visbroken Polyolefin

[00031] According to the invention, thermoplastic compounds include non-visbroken polyolefin.

[00032] As used herein, the term“non-visbroken^** means a polymer that is not visbroken; and the term“visbroken” means a polymer that has been subjected to a visbreaking or polymer chain scission process which results in a lower molecular weight, a higher melt flow rate, and a narrower molecular weight distribution, all relative to the value of those characteristics for the polymer prior to the visbreaking or polymer chain scission process.

[00033] Suitable non-visbroken polyolefins include conventional or commercially available polyolefins provided that such polyolefins are non- visbroken. A non-visbroken polyolefin can be used alone or in combination with one or more other non-visbroken polyolefins. [00034] In some embodiments, suitable non-visbroken polyolefins include any polyolefins prepared by Ziegler-Natta catalysis provided that such polyolefins are non-visbroken.

[00035] In other embodiments, the non-visbroken polyolefin is selected from non-visbroken polypropylene homopolymer, non-visbroken polyethylene homopolymer, non-visbroken propylene-ethylene copolymer, and combinations thereof.

[00036] In further embodiments, the non-visbroken polyolefin is non- visbroken polypropylene.

(00037( In some embodiments, the non-visbroken polypropylene has a molecular weight distribution (Mw/Mn) of about 4.5 or greater. In other embodiments, the non-visbroken polypropylene has a molecular weight distribution (Mw/Mn) of about 4.8 or greater. In further embodiments, the non- visbroken polypropylene has a molecular weight distribution (Mw/Mn) of about 5 or greater. In even further embodiments, the non-visbroken polypropylene has a molecular weight distribution (Mw/Mn) of about 5.5 or greater.

[00038] As used herein, the weight average molecular weight (Mw) and the number average molecular weight (Mn), and, in turn, the molecular weight distribution (Mw/Mn), which is also referred to as polydispersity or dispersity, are determined by high temperature gel permeation chromatography (GPC) using a POLYMER CHAR GPC-IR chromatograph with an infrared detector available from Polymer Characterization.

[00039] In some embodiments, the non-visbroken polypropylene has a melt flow rate (230 °C, 2.16 kg) of about 20 or less according to ASTM D1238. In other embodiments, the non-visbroken polypropylene has a melt flow rate (230 ^eC, 2.16 kg) of about 17 or less according to ASTM D1238.

[00040] Non-limiting examples of commercially available non-visbroken polypropylene homopolymer include grade F180A available from Braskem; and PRO-FAX 6523 available from LyondellBasell.

(00041[ Talc Mineral Filler [00042] According to the invention, thermoplastic compounds include mineral filler selected from talc having a median particle size from about 9 to about 1 1 microns.

[00043] Suitable talc includes conventional or commercially available talc provided that such talc has a median particle size from about 9 to about 1 1 microns.

[00044] In some embodiments, the talc has a median particle size of about 10 microns, for example, 10.1 microns.

[00045] As used herein, median particle size is determined by sedimentation analysis using a SEDIGRAPH 5120 particle size analyzer available from Micrometries.

[00046] Non-limiting examples of commercially available talc include

BENWOOD 2213 available from IMI Fabi.

[00047] As reported by the manufacturer, BENWOOD 2213 talc is 98% talc, 1% chlorite, and 1% dolomite, with no detection of quartz or fibrous minerals, according to thcrmogravimetric and X-ray diffraction.

[00048] As further reported by the manufacturer, BENWOOD 2213 talc has a median particle size (median diameter) of 10.1 microns; a Hegman Grindometer Fineness of 2; a specific gravity of 2.7 g/cm³; and a bulk density of 28 pounds/fV.

[00049] Optional Odor Absorber

[00050] In some embodiments, thermoplastic compounds further include odor absorber.

[00051] Suitable odor absorber includes conventional or commercially available odor absorbers.

[00052] In some embodiments, the odor absorber is selected from aerogels, activated charcoals, carbonates, metal oxides, silicates, zeolites, and combinations thereof.

[00053] In some embodiments, the odor absorber is hydrophobic zeolite. [00054] Non-limiling examples of commercially available hydrophobic zeolite include ZEOFLAIR grades 100 and 810 available from Zeochem.

[00055] In further embodiments, thermoplastic compounds are free of any odor absorber.

[00056] Optional Other Additives

[00057] In some embodiments, the thermoplastic compound includes one or more optional other additives.

[00058] Suitable optional additives include conventional or commercially available plastics additives. Those skilled in the art of thermoplastics compounding, without undue experimentation, can select suitable additives from available references, for example, E.W. Flick,“Plastics Additives Database,”

Plastics Design Library (Elsevier 2004).

[00059] Optional additives can be used in any amount that is sufficient to obtain a desired processing or performance property for the thermoplastic elastomer compound and/or the overmolded thermoplastic article. The amount should not be wasteful of the additive nor detrimental to the processing or performance of the thermoplastic elastomer compound and/or the thermoplastic article.

[00060] Non-limiting examples of additives suitable for use in the present invention include one or more selected from antioxidants and stabilizers; antiscratch and anti-mar agents; colorants; dispersion aids; lubricants; processing aids; release agents; secondary resins; ultraviolet light absorbers; waxes; and combinations thereof.

)00061) Ranges of Ingredients in the Thermoplastic Compounds

[00062] Tabic 1 below shows the acceptable, desirable, and preferable ranges of ingredients for some embodiments of the thermoplastic compounds of the present invention in terms of weight percent based on total weight of the thermoplastic compound. Other possible ranges of ingredients for certain other embodiments of the present invention are as described elsewhere herein. [00063] Thermoplastic compounds of the present invention can comprise, consist essentially of, or consist of these ingredients. Any number between the ends of the ranges is also contemplated as an end of a range, such that all possible combinations are contemplated within the possibilities of Table 1 as embodiments of compounds for use in the present invention. Unless expressly stated otherwise herein, any disclosed number is intended to refer to both exactly the disclosed number and “about^** the disclosed number, such that either possibility is contemplated within the possibilities of Table 1 as embodiments of compounds for use in the present invention.

[00064] In other embodiments, the non-visbroken polyolefin is present in an amount relative to an amount of the mineral filler at a weight ratio ranging from about 1.25: 1 to about 9: 1.

[00065] In further embodiments, the non-visbroken polyolefin is present in an amount relative to an amount of the mineral filler at a weight ratio ranging from about 3: 1 to about 4: 1.

[00066] Processing

[00067] Some aspects of the invention are directed to methods of making thermoplastic compounds as described herein.

[00068] Other aspects of the invention are directed to thermoplastic articles molded from thermoplastic compounds as described herein.

[00069] Generally, methods of making the thermoplastic compound include the steps of (a) providing ingredients comprising the non-visbroken polyolefin and the mineral filler selected from talc having a median particle size from about 9 to about 11 microns, and (b) melt mixing the ingredients to provide the compound.

[00070] In some embodiments, the melt mixing of step (b) occurs under an atmosphere of an inert gas. In Anther embodiments, the melt mixing of step (b) occurs under an atmosphere rich in an inert gas, for example, wherein the atmosphere consists of at least 80 %, or 85 %, or 90 %, or 95 %, or 99 %, or 99.9 %, by volume, of the inert gas. In some embodiments, the inert gas is diatomic nitrogen gas; that is, N>.

[00071] Otherwise, preparation of the thermoplastic compounds of the present invention is uncomplicated once the proper ingredients have been selected. The compounds can be made in batch or continuous operations.

[00072] Mixing in a continuous process typically occurs in an extruder that is elevated to a temperature that is sufficient to melt the polymer matrix with addition of all additives at the feed-throat, or by injection or side-feeders downstream. Extruder speeds can range from about 200 to about 700 revolutions per minute (rpm), for example, from about 300 rpm to about 600 rpm. Typically, the output from the extruder is pelletized for later processing.

[00073] Subsequent preparation of thermoplastic articles of the present invention also is uncomplicated once thermoplastic compounds of the present invention are provided. For example, thermoplastic articles of the present invention can be made by extrusion, injection molding, blow molding, rotational molding, thermoforming, calendering, and the like.

[00074] Processing techniques arc described in available references, for example, Dominick V. Rosato et al., Plastics Design Handbook (Springer 2013).

[00075] Methods of Reducing Odor

[00076] Some aspects of the invention are d irected to methods of reducing odor of thermoplastic compounds including polypropylene and talc.

[00077] According to the invention, the method includes the step of providing the polypropylene, wherein the polypropylene is selected from non- visbroken polypropylene having a molecular weight distribution (Mw/Mn) of about 4.5 or greater. The method also includes the step of providing the talc, wherein the talc is selected from talc having a median particle size from about 9 to about 1 1 microns.

[00078] In some embodiments, the method further includes the step of providing an odor absorber selected from hydrophobic zeolite. In these embodiments, the compound has an odor rating of 3 or less according to VDA 270 B3 (without rounding down to a nearest half-grade of the odor rating).

USEFULNESS OF THE INVENTION

[00079] According to aspects of the invention, thermoplastic polyolefin compounds include non-visbroken polyolefin and mineral filler selected from talc having a median particle size from about 9 to about 11 microns. The compounds have an odor rating of less than about 3.3 according to VDA 270 B3 (without rounding down to a nearest half-grade of die odor rating) while also maintaining desirable physical properties, which makes the compounds especially useful for molding thermoplastic articles for use as parts in automotive interior and undcr- the-hood applications. Non-limiting examples of such applications include HVAC housings and ducts, interior trim, air filter housings, fan shrouds, acoustical barrier motor covers, actuators, and the like.

[00080] Other markets and applications for thermoplastic articles of the present invention include without limitation: molding, trim, hardware, and components in the transportation market; durables, appliances, and components in the consumer market; housings, enclosures, and equipment in the electrical/electronic market; shutters, siding, trim, and plumbing in the industrial market; and other markets or applications benefiting from the article’s unique combination of properties.

EXAMPLES [00081] Non-limiting examples of thermoplastic compounds of various embodiments of the present invention arc provided herein below.

[00082] Table 2 below shows sources of ingredients for the thermoplastic compounds of Comparative Examples A to F and Examples 1 to 3.

[00083] Examples of the thermoplastic compound were compounded and extruded as pellets on a Coperion 26 mm twin screw extruder at a temperature of 440 °F and a mixing speed of 550 rpm. Subsequently, test specimens were prepared by injection molding and then evaluated for the reported properties.

[00084] Table 3 below shows the formulations and certain properties of Comparative Examples A to C.

[00085] Table 4 below shows the formulations and certain properties of Comparative Examples D to F.

[00086] Table 5 below shows the formulations and certain properties of Examples 1 to 3.

[00087] Without undue experimentation, those having ordinary skill in the art can utilize the written description, including the Examples, to make and use aspects of the present invention.

[00088] All documents cited in the Embodiments of the Invention are incorporated herein by reference in their entirety unless otherwise specified. The citation of any document is not to be construed as an admission that it is prior art with respect to the present invention.

[00089] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. The appended claims are intended to cover all such changes and modifications that are within the scope of the present invention.

Claims

WHAT IS CLAIMED IS:

1. A thermoplastic compound comprising:

(a) non-visbroken polyolefin; and

(b) mineral filler selected from talc having a median particle size from about 9 to about 1 1 microns;

wherein the compound has an odor rating of less than 3.3 according to VDA 270 B3 without rounding down to a nearest half-grade of the odor rating.

2. The compound of Claim 1, wherein the non-visbroken polyolefin is selected from the group consisting of non-visbroken polypropylene, non- visbroken polyethylene, non-visbroken polyolefin elastomer, and combinations thereof.

3. The compound of Claim 1 or Claim 2, wherein the non-visbroken polyolefin is non-visbroken polypropylene.

4. The compound of Claim 3, wherein the non-visbroken polypropylene has a molecular weight distribution (Mw/Mn) of about 4.5 or greater.

5. The compound of Claim 4, wherein the non-visbroken polypropylene has a melt flow rate (230 °C, 2.16 kg) of about 20 or less according to ASTM D1238.

6. The compound of any one of Claims 1 to 5, wherein the talc has a median particle size of about 10.1 microns.

7. The compound of any one of Claims 1 to 6, wherein the compound further comprises an odor absorber selected from the group consisting of aerogels, activated charcoals, carbonates, metal oxides, silicates, zeolites, and combinations thereof.

8. The compound of Claim 7, wherein the odor absorber is hydrophobic zeolite.

9. The compound of Claim 8, wherein the compound has an odor rating of 3 or less according to VDA 270 B3 without rounding down to a nearest half-grade of the odor rating.

10. The compound of any one of Claims I to 6, wherein the compound is free of any odor absorber.

1 1. The compound of any one of Claims 1 to 10, wherein the compound has volatile organic compound emissions of about 25 mgC/g or less according to VDA 277.

12. The compound of any one of Claims l to 1 1 , wherein the compound further comprises at least one additive selected from the group consisting of antioxidants and stabilizers; anti-scratch and anti-mar agents; colorants; dispersion aids; lubricants; processing aids; release agents; secondary resins; ultraviolet light absorbers; waxes; and combinations thereof.

13. The compound of any one of Claims 1 to 12, wherein the non-visbroken polyolefin is present in an amount relative to an amount of the mineral filler at a weight ratio ranging from about 1.25: 1 to about 5: 1.

14. The compound of Claim 13, wherein the weight ratio of the non-visbroken polyolefin relative to the mineral filler ranges from about 3: 1 to about 4: 1.

15. An article molded from the compound of any one of Claims 1 to 14.

16. A method of making the compound of any one of Claims 1 to 14, the method comprising the steps of:

(a) providing ingredients comprising the non-visbroken polyolefin and the mineral filler, and

(b) melt mixing the ingredients to provide the compound.

17. The method of Claim 16, wherein the melt mixing of step (b) occurs under an atmosphere consisting of at least 80 %, by volume, of an inert gas.

18. The method of Claim 17, wherein the inert gas is diatomic nitrogen gas.

19. A method of reducing odor of a thermoplastic compound including polypropylene and talc, the method comprising the steps of:

(a) providing the polypropylene, wherein the polypropylene is selected from non-visbroken polypropylene having a molecular weight distribution (Mw/Mn) of about 4.5 or greater; and

(b) providing the talc, wherein the talc is selected from talc having a median particle size from about 9 to about 11 microns.

20. The method of Claim 19, further comprising the step of providing an odor absorber selected from hydrophobic zeolite, and wherein the compound has an odor rating of 3 or less according to VDA 270 B3 without rounding down to a nearest half-grade of the odor rating.