Patent Application
20170001344
The present invention relates to reducing aldehyde emissions during injection molding of cellulosic fiber-reinforced polypropylene compositions.
Volatile organic compound (VOC) emissions are caused by low molecular weight compounds. For example, residual monomers from polymerization, additives, plasticizers, degradation byproducts from processing and aging of a molded part. It is of particular importance to avoid VOC emissions in high value-added bioproducts, particularly for automotive applications. Cellulosic and lignocellulosic materials, such as wood, flax, hemp, sisal, abaca and coir may be used as reinforcement in polypropylene because of their lower density and cost. Nevertheless, exposing cellulose-based materials to thermal oxidative degradation, for example, from drying, compounding and molding operations, results in a drastic increase in the acetaldehyde and formaldehyde content in the end part.
Acetaldehyde and formaldehyde are harmful. Its content in automotive end parts is regulated by existing legislation in important jurisdictions including the European Union (1999/13/EC), the United States (EPA), Canada (CEPA) and Japan (JAMA). Original equipment manufacturers (OEMs) have also set strict VOC limits to qualify and deploy new materials into new vehicles that are dependent on part location and market region.
Therefore, it is a goal in the art to decrease the content of acetaldehyde and formaldehyde that is generated during the injection molding of cellulosic-fiber reinforced polypropylene composites to meet automotive requirements on VOC emissions. It is also desirable in the art to decrease acetaldehyde and formaldehyde content in polypropylene parts reinforced with vegetal fibers, including those from: hardwoods, softwoods, roots, husks, fruits, seeds, grasses, reeds, basts, stalks, canes, leafs and leaf sheaths.
A method of reducing aldehyde emissions during injection molding of a part with a cellulosic fiber-reinforced polypropylene composition is provided. The method includes providing an injection molding machine capable of the parameters necessary for injection molding of a cellulosic fiber-reinforced polypropylene composition. The injection molding machine includes a hopper for holding of a pelletized cellulosic fiber-reinforced polypropylene composition material. The injection molding machine includes a feed throat portion and also a mixing chamber installed in line with the injection molding machine between the hopper and the feed throat portion. An effective amount of an aldehyde reducing composition is metered into the mixing chamber containing pelletized cellulosic fiber-reinforced polypropylene composition. In the mixing chamber the pelletized cellulosic fiber-reinforced polypropylene composition is mixed with the aldehyde reducing composition for wetting the surface of the pellets with the aldehyde reducing composition. Thereafter, a part is injection molded with the wetted pelletized mixture.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawing, wherein:
The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
Referring to
As set forth above the injection molding machine 10 of the present invention is preferably of a type which can operate in the narrow processing window of injection molding of cellulosic fiber-reinforced polypropylene composition materials. Such cellulosic fiber-reinforced polypropylene composition materials are used to make polypropylene automotive parts. The polypropylenes used in these parts are often reinforced with vegetal fibers, including those from: hardwoods, softwoods, roots, husks, fruits, seeds, grasses, reeds, basts, stalks, canes, leafs and leaf sheaths and therefore the injection molding machine 10 of the present invention is adapted and the parameters are controlled for specific use with these types of materials.
In the present invention the mixing chamber 16 is used to mix the pelletized polypropylene with the aldehyde reduction composition. The mixing chamber 16 provides agitation of the mixture either by mechanical means or by air pressure or the like to ensure the entire surface of the pellets is wetted by the mixture.
The peristaltic pump 18 is operably connected to a liquid additive reservoir, e.g., such as the reservoir indicated generally at 24, containing the aldehyde reducing composition and feeds the aldehyde reducing composition into the mixing chamber 16 installed on the feed throat 14 of the injection molding machine 10 via the hose 20. An off-relay timer, e.g., timer, control unit or the like connected wirelessly, hard wired, or incorporated into the pump 18, sends a control signal to the peristaltic pump 18 to feed a predetermined amount of the aldehyde reducing composition during the injection molding cycle, such as during the recovery time of the injection molding cycle. The aldehyde reducing composition is fed inside the mixing chamber 16 thereby wetting the pre-compounded cellulosic fiber-polypropylene pellets.
The present invention at least significantly reduces, and preferably eliminates, aldehyde content such as acetaldehyde and formaldehyde.
With respect to the aldehyde reducer or “scavenger composition” or “liquid additive scavenger”, an anthranilamide, an anthranilamide derivative 1,8 diaminonaphthalene, or 3,4-diaminobenzoic acid and/or mixtures of these is used to form a condensation reaction with any aldehydes which are present and released during melt processing. The product of this reaction is to form an organic compound and water. This binds the free acetaldehyde and formaldehyde compositions. Thus, the process dramatically reduces aldehyde-based VOC emissions during injection molding of automotive parts for vehicles. Examples of such an additive is a ColorMatrix™ “Triple A™” liquid additive and formulations: typically 180-30609-1, 180-30610-1 and particularly 180-30611-1 also available through ColorMatrix Corporation, Cleveland, Ohio.
In one embodiment the aldehyde reducing composition is formed by at least two thermally stable moieties where at least one of the moieties is anthranilamide, an anthranilamide derivative 1,8 diaminonaphthalene, or 3,4-diaminobenzoic acid. Each moiety is reactive with the free acetaldehyde and formaldehyde released of the cellulosic fiber-reinforced polypropylene melt to produce an organic compound and water, thereby binding the free acetaldehyde and formaldehyde and preventing them from being released.
The above aldehyde reducing compositions are metered into the mixing chamber 16 in effective amounts such that a low percent is found in the end part, generally not more than 1.0 weight percent, typically between 0.21 and 0.525 or 0.15 and 0.375, preferably between 0.15 and 0.525 weight percent is found in the end part. It has been found that such amounts provided predetermined desired reduced VOCs which meet the stringent requirements imposed in automotive manufacturing. The above aldehyde reducing compositions are a non-hazardous, non-toxic, effective acetaldehyde and formaldehyde scavengers that works efficiently in the narrow processing window of cellulose-based materials. The above aldehyde reducing compositions also do not have negative effects on the mechanical performance, surface color and odor of the resulting composite.
The method for decreasing aldehyde content, e.g., acetaldehyde and formaldehyde, in injection molded cellulosic fiber-reinforced polypropylene composites for automotive applications using the above aldehyde reducing compositions typically forms a condensation reaction during melt processing to form an organic compound and water.
The equations below, for example, illustrate condensation reactions between the aldehyde reducing composition and the acetaldehyde and formaldehyde formed during the melt processing of cellulosic fiber-reinforced polypropylene during injection molding.
The present invention is further illustrated by means of the following examples.
All VOC tests were performed from injection molded samples having a surface area of 8,000 mm2 (80×100 mm with thickness: 3 mm).
The test materials were conditioned for 7 days at temperature 20.0±5° C. and relative humidity 50.0±5% prior VOC testing by a testing facility. After conditioning, the test materials were wrapped in aluminum foil and shipped to the testing facility. No ink, adhesive tape, or absorbing packaging material was used on, or in conjunction with the test samples, as this may have an effect on the results.
The following procedure was performed to measure the VOCs:
The results are shown in the following examples.
A polypropylene matrix (TOTAL™ 3622) was compounded with (Thermo-Mechanical Pulp, “TMP”) wood fiber, coupling agent (OREVAC® CA) and anti-oxidant (ADD-VANCE® 453) indicated in table 1. The compound was pelletized and molded in an ENGEL™ 200 TL injection molding machine.
The resin and the wood fiber were dried to a final moisture content of 0.1 wt. % prior to compounding and injection molding.
In this example, no liquid additive scavenger was used.
The VOC test was performed after aging the test specimens.
A polypropylene matrix (TOTAL® 3622) was compounded with (Bleached-Chemi-Thermo-Mechanical, “BCTMP”) wood fiber, coupling agent (PRIEX® 20097), primary anti-oxidant (IRGANOX® 1010) and secondary anti-oxidant (IRGANOX® B225) indicated in table 3. The compound was pelletized and molded in an ENGEL® 200 TL injection molding machine.
The resin and the wood fiber were dried to a final moisture content of 0.1 wt. % prior to compounding and injection molding.
In this example, no liquid additive scavenger was used.
The VOC test was performed after aging the test specimens.
A polypropylene matrix (TOTAL® 3622) was compounded with (unrefined kraft) wood fiber, coupling agent (PRIEX® 20097), primary anti-oxidant (IRGANOX® 1010) and secondary anti-oxidant (IRGANOX® B225) indicated in table 5. The compound was pelletized and molded in an ENGEL® 200 TL injection molding machine.
The resin and the wood fiber were dried to a final moisture content of 0.1 wt. % prior to compounding and injection molding.
In this example, no liquid additive scavenger was used.
The VOC test was performed after aging the test specimens.
A polypropylene matrix (TOTAL® 3925) was compounded with (unrefined kraft) wood fiber, coupling agent (PRIEX® 20097), primary anti-oxidant (IRGANOX® 1010) and secondary anti-oxidant (IRGANOX® B225) indicated in table 7. The compound was pelletized and molded in an ENGEL® 200 TL injection molding machine.
The resin and the wood fiber were dried to a final moisture content of 0.1 wt. % prior to compounding and injection molding.
A liquid additive scavenger (COLORMATRIX™ “TRIPLE A”™ LIQUID ADDITIVE indicated in table 7) was used during the molding phase as described in the method disclosed above.
The VOC test was performed after aging the test specimens.
A polypropylene matrix (STYRON™ 7600) was compounded with (unrefined kraft) wood fiber, coupling agent (PRIEX® 20097), primary anti-oxidant (IRGANOX® 1010) and secondary anti-oxidant (IRGANOX® B225) indicated in table 9. The compound was pelletized and molded in an ENGEL® 200 TL injection molding machine.
The resin and the wood fiber were dried to a final moisture content of 0.1 wt. % prior to compounding and injection molding.
A liquid additive scavenger (COLORMATRIX™ “180-30609-1” indicated in table 9) was used during the molding phase as described in the method disclosed above.
The VOC test was performed after aging the test specimens.
A polypropylene matrix (STYRON™ 7600) was compounded with (unrefined kraft) wood fiber, coupling agent (PRIEX® 20097), primary anti-oxidant (IRGANOX® 1010) and secondary anti-oxidant (IRGANOX® B225) indicated in table 11. The compound was pelletized and molded in an ENGEL® 200 TL injection molding machine.
The resin and the wood fiber were dried to a final moisture content of 0.1 wt. % prior to compounding and injection molding.
A liquid additive scavenger (COLORMATRIX™ “180-30610-1”, indicated in table 11) was used during the molding phase as described in the method disclosed.
The VOC test was performed after aging the test specimens.
A polypropylene matrix (STYRON™ 7600) was compounded with (unrefined kraft) wood fiber, coupling agent (PRIEX® 20097), primary anti-oxidant (IRGANOX® 1010) and secondary anti-oxidant (IRGANOX® B225) indicated in table 13. The compound was pelletized and molded in an ENGEL® 200 TL injection molding machine.
The resin and the wood fiber were dried to a final moisture content of 0.1 wt. % prior to compounding and injection molding.
The liquid additive scavenger (COLORMATRIX™ “180-30611-1” indicated in table 13) was used during the molding phase as described in the method disclosed.
The VOC test was performed after aging the test specimens.
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
This application claims the benefit of U.S. Provisional Application No. 62/188,146, filed Jul. 2, 2015. The disclosure of the above application is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62188146 | Jul 2015 | US |
