MX2008007431A - Method of recycling paints as a component of an immiscible polymer blend - Google Patents

Abstract

An immiscible polymer blend including a first polymer component including a paint polymer phase and a second polymer component immiscible with the first polymer component and selected from polyolefins and polymethylmethacrylate (PMMA). A method of recycling paint by blending a first polymer component including a paint polymer phase with a second polymer component immiscible with the first polymer component and selected from polyolefins and polymethylmethacrylate (PMMA) is also presented.

Description

METHOD FOR RECYCLING PAINTS AS A COMPONENT OF A MIXTURE OF POLYMERS Background of the Invention According to the United States Environmental Protection Agency, unwanted paint is a component of residential household hazardous waste throughout the country. It is estimated that they generate 34 million gallons of consumer paint remains annually in the United States. However, this estimate does not include significant amounts of residual paint generated by contractors, incorrect colors of retailers, paint manufacturers, private companies or other businesses, schools and other public agencies.

The main component of wastewater streams from retailers includes unused whole paint containers that are returned as an incorrect color or by another error. The cost of the final disposal, a cost for each container for recycling or the disposal of hazardous waste, is very high for the retailer. Much of this paint could be remixed and converted into paint for use by government or private entities, particularly unused gallons that are returned to retailers. However, the Markets for remixed paint have so far not proven to be profitable.

Currently, latex paint is the most popular paint on the market. In 1997, $ 270,000 was spent on the collection and recycling of 1.3 million pounds of latex paint. The amount of latex paint after sale to the consumer has grown every year, and in 2003, the amount of latex paint collected increased to two million pounds.

The high volume of residual or unwanted latex paint in the municipal solid waste stream makes it an attractive material for recycling. In addition, many jurisdictions prohibit the disposal of residual paint in a liquid state, due to its propensity to spill on the way to the landfill or the incinerator that may cause contamination of the facilities.

Latex paint is composed of 59.3% water, 15.7% latex polymer concentration, 12.5% titanium dioxide concentration, 12.5% diluent pigments and 1.1% concentration of polyethylene glycol. However, in the 1980s and before, mercury was used as a preservative in latex paint. Therefore, the liquid residual paint that was collected in the recycling facilities should be tested for the presence of mercury and other contaminants before deciding their destination: be recycled for reuse or use in non-traditional products, landfill or hazardous waste. Latex paint manufactured after the 1980s can be disposed legally in a solid, dry form without being taken to a sanitary landfill for hazardous waste. Drying the residual paint to a solid state releases only water and fractional amounts of volatile non-organic compounds, safe in the environment. However, it consumes time, and requires considerable effort due to weather conditions and safety.

Therefore, it is necessary to develop a program and a voluntary, proactive recycling technology to reuse this material while simultaneously creating financial benefits. Said program must be successful in removing a large percentage of unused paint from the wastewater stream to eliminate the need for a mandatory or special tax program.

Extract of the Invention The present invention uses recycled paint to prepare immiscible polymer blends. A mixture of immiscible polymers is presented, which includes a first polymeric component having a polymeric paint phase and a second polymeric component immiscible with the first polymeric component and selected from polyolefins and polymethylmethacrylate (PMMA).

One embodiment includes a method for recycling paint by mixing a first polymer component having a polymeric paint phase with a second polymer component immiscible with the first polymer component and selected from polyolefins and polymethylmethacrylate (PMMA).

Yet another embodiment includes an article of a mixture of immiscible polymers, wherein the mixture includes a first polymer component having a polymeric paint phase and a second polymeric component immiscible with the first polymer component and selected from polyolefins and polymethyl methacrylate (PMMA) ).

Another embodiment includes an article formed using a method for recycling paint, wherein the method includes mixing a first polimepco component having a polymeric paint phase with a second polymeric component immiscible with the first polymer component and selected from polyolefins and polymethyl methacrylate (PMMA).

Brief Description of the Drawings Figure 1 represents the loss of mass as a function of drying time for two paint samples, A and B.

Figure 2 is a graph showing the tensile modulus as a function of the weight percentage of paint in the PMPE / HDPE blends.

Figure 3 is a graph showing the tensile modulus as a function of the percentage by weight of paint in PMtura / PMMA blends.

Figure 4 shows the final tensile strength as a function of the weight percentage of paint in paint / PMMA and paint / HDPE mixtures.

Figure 5 represents stress-strain curves for glossy and matte / HDPE paint mixtures.

Figure 6 depicts stress-strain curves for gloss and matte / PMMA paint mixtures.

Figure 7 shows differential scanning calorimetry (DSC) scans of 35% / 65% by weight of Brilliant / HDPE blends.

Figure 8 shows differential scanning calorimetry (DSC) scans of 35% / 65% Brilliant / PMMA mixture.

Detailed description of the invention The present invention provides mixtures of immiscible color polymers formed using paint as one of the polymeric components. A mixture of immiscible polymers according to the present invention includes a first polymeric component, which includes a polymeric paint phase, and a second polymeric component immiscible with the first polymeric component and which is selected from polyolefins and polymethylmethacrylate (PMMA).

The first polymeric component includes a polymeric paint phase preferably derived from water-based paints, oil-based paints, or solvent-based paints.

Preferably, the paint is collected from an effluent treatment facility or directly from the unwanted provision of a retail or consumer business. The paint is collected in liquid or dry form. In one embodiment, the paint is collected in liquid form and mixed with the second immiscible polymer component in the liquid form. In another embodiment, the paint is collected in liquid form and dried to reduce the water, oil and / or solvent content before mixing it with the second immiscible polymeric component.

In one embodiment, the first polymer component is a polymer phase of latex paint preferably derived from matte latex paint or glossy latex paint. The terms "glossy paint" and "glossy latex paint" as used herein include semi-gloss and very glossy paints.

The polymeric phase of the paint is usually formed from one or more polymers including acrylates, vinyl acrylates, vinyl acetates, styrene acrylates, polyurethanes, epoxies, neoprene, polyesters and alkyd polyesters. Paints containing acrylate and / or polyester polymers are preferred. The polymer phase of the paint can be mixed with another miscible polymer before mixing it with an immiscible polymer component. Examples of miscible mixtures include polystyrene / polyethylene oxide and polycarbonate / acrylonitrile butadiene styrene.

The polymeric phase of the paint is mixed with a second immiscible polymer component to form the immiscible polymer blends of the present invention. The second polymer component is selected from polyolefins and polymethylmethacrylate (PMMA). Examples of polyolefins include polystyrene and polypropylene. Preferably, the second polymer component is selected from PMMA and high density polyethylene (HDPE). A preferred blend includes a polymer phase of latex paint derived from glossy paint and PMMA.

One embodiment includes a paint / second polymer component selected ratio of 20/80, 30/70 and 35/65, wherein the ratio of 35/65 is preferred. In one embodiment, the second polymer component includes between 65% and 80% by weight of PMMA or HDPE. In another embodiment, the first polymer component includes 65% by weight of PMMA.

Articles formed from the polymer mixture are also presented. Suitable articles include those that are they usually form from polyolefins or PMMA. For example, a typical use for PMMA is as an impact resistant substitute for glass. Examples of HDPE articles include packaging articles, preferably, packages, merchandise bags, shrink films, shopping bags and industrial coatings.

The present invention also includes a method for recycling paint by mixing a first polymer component comprising a polymeric paint phase with a second polymeric component immiscible with the first polymeric component and selected from polyolefins and PMMA. In one embodiment, the first polymer component and the second polymer component are both in liquid form prior to mixing. Another embodiment includes reducing the water, oil and / or solvent content of the polymeric paint phase after combining it with the second immiscible polymeric component. For example, the water, oil and / or solvent content of the polymeric paint phase can be removed by heating and / or producing a vacuum over the mixture of the first polymer component / second immiscible polymer component. Examples of apparatus for reducing the water, oil and / or solvent content of the polymeric paint phase include twin screw extruders manufactured, for example, by Leistritz Corp. Allendale, NJ and paint devolatilizers. In One embodiment, the first polymer component and the second immiscible polymer component, both in liquid form, are mixed in a twin-screw extruder immediately before extrusion.

Another embodiment includes the step of forming an article with the polymer blend. In one embodiment, the forming step includes injection molding, blow molding, thermoforming, rotational molding or extrusion molding. Another embodiment includes an article formed in accordance with the method of the present invention.

The following non-exhaustive examples set forth below represent certain aspects of the invention.

EXAMPLES Example 1: Preparation and Analysis of the Paint Thirteen cans of paint were collected after the consumer, separated by bright content and labeled glossy or matt. Both the very bright and the semi-gloss paint were classified in the glossy category, and the matte paint was labeled matt.

A small sample was collected from each can, weighed and weighed again after five days to determine changes in the mass. After this preliminary experiment, samples of glossy paint and matte paint were poured into baking sheets of 25 cm by 55 cm, dried under room temperature conditions overnight to form a thin layer or a solid layer in the surface, and were placed in a Precision Mechanical Conventional Furnace at 85 ° C for a period of twelve hours. The twelve-hour period was repeated for each sample until the paint could be released from the source in a clean manner. The total drying time varied due to the bright paint content. The total drying time of the matte paint was three to four days, while the total drying time of the bright paint was five to seven days.

The resulting solid sheets of glossy paint were then cut into ten cuts of 5 cm x 9 cm and labeled A-J. The initial mass of the rectangular samples was recorded. The samples were further dried in a Fisher Scientific Isothermal Furnace at a temperature of 85 ° C for twenty-four hour periods, and the mass was recorded after each increment. The samples were dried until the change of mass in each period was minimal. The length, width and height were measured and the density was calculated for each sample. The study Preliminary to determine the approximate weight loss of glossy and matte paints resulted in average weight losses of 48.2% for glossy paint and 47.0% for matte paint. Table 1 shows the weight loss of the thirteen paint samples collected after a -day drying period. While there were only three samples of matte paint, it was hypothesized that matte paint would have a lower percentage of weight loss than glossy paint due to the higher ceramic content of the matte paint.

Table 1. Percentage of weight loss after a 5-day drying period Table 2 shows the calculated density of ten bright paint samples, labeled A-J. The average density of the bright samples is 1.45 g / cm3. Figure 1 represents the loss of mass as a function of the drying time for two of the samples, A and B, during a period of 180 hours. As expected, the curve decreases at a decreasing rate until it levels off asymptotically and the weight change is minimal.

Table 2. Density of dry bright paint Example 2: Preparation and analysis of polymer mixtures The second phase of the experiments consisted in mixing different compositions of the paint with solid latex, dry with HDPE or PMMA to produce paint / polymer mixtures. Composition ratios of 20/80% and 35/65% were prepared in weight of Matte / HDPE, Brilliant / HDPE, Matte / PMMA and Brilliant / PMMA, as well as 100% HDPE and 100% PMMA. The blends were co-extruded using a Brabender Inteli-Torque Plasti-Corder extruder operating at 50 RPM at a temperature of 180 ° C. Once cooled, the extrudate was ground in a Nelmor crusher. Each mix was injection molded into tensile specimens using a Negri Bossi V55-200 injection molding machine that operated at 205 ° C.

The mechanical properties of traction were determined using an MTS QTest / 25 Elite Controller, in accordance with ASTM D 638. Modulus, final effort and percentage of deformation in the fracture were calculated. The average results of the specimens are repeated for each composition.

The thermal properties were determined using a TA Instruments Q 1000 Differential Scanning Calorimeter in modulated DSC mode (MDSC) under a dry nitrogen atmosphere. Samples of approximately 8 mg of 35/65 Brilliant / HDPE and 35/65 Brilliant / PMMA were encapsulated in common aluminum pots and sealed by crimping. DSC scans were performed for each sample at 3 ° C / minute while simultaneously modulating at 2 ° C every 40 seconds. The Brilliant / HDPE sample was scanned at a temperature range of -20 ° C- 200 ° C and the Brilliant / PMMA sample was scanned at a temperature range of -20 ° C-160 ° C. Each sample was heated, cooled and reduced to the respective temperature range.

Table 3 shows average tensile mechanical properties (modulus, final stress and fracture strain) of paint / polymer blends of Brilliant / HDPE, Matte / HDPE, Brilliant / PMMA and Matte / PMMA. The deformation in the fracture was reported, although not all specimens were fractured. The value represents the highest percentage of deformation before the end of the test. Of the specimens tested to each composition of 100% HDPE, Brilliant / HDPE, Matte / HDPE, and Brilliant / PMMA none were fractured. However, for the compositions of Mate / PMMA, none of the specimens were fractured to the composition of 35% / 65% of Mate / PMMA, but several samples did fracture to the compositions of 30% / 70% and 20% / 80% Mate / PMMA. For the composition of 100% PMMA, the specimens tested were fractured. Brilliant / PMMA mixtures have a higher percentage of fracture deformation than pure PMMA.

Table 3. Average tensile properties of polymer blends of Brilliant and Matte Paint / HDPE and polymer blends of Brilliant and Matte Paint / PMMA to different compositions Figures 2 and 3 graphically represent a comparison of the tensile modulus as a function of the paint content between Brilliant / HDPE and Matte / HDPE blends and Bpllante / PMMA and Mate / PMMA blends, respectively. The 100% HDPE module (720 MPa) increases dramatically with the addition of 20% matte or glossy paint but then decreases again to 720 MPa. By adding 35% matte paint, the module decreases below 720 MPa. As shown in Figure 3, any aggregate of PMMA decreases the modulus above that of 100% PMMA (3,480 MPa). However, the bright paint has the opposite effect, and the modulus decreases of 3,480 MPa with any addition of bright paint.

Figure 4 graphically represents a comparison of the final tensile strength as a function of the paint content between Brilliant / HDPE and Matte / HDPE blends and Bpllante / PMMA and Matte / PMMA blends. The final strength increases of 14.5 MPa for pure HDPE with bright paint content but it is quite constant with the addition of matte paint. The final PMMA strength decreases linearly from 65.0 MPa with the addition of glossy paint and in an approximately linear fashion with the addition of matte paint.

Figures 5 and 6 present stress-strain curves for glossy and matte / HDPE and Paint / PMMA mixtures, respectively. Mixtures of Brilliant and Matte / HDPE Paint behave similarly to pure HDPE. This result suggests that Paint / HDPE blends can replace HDPE in some applications. However, the gloss and matte / PMMA paint mixtures have a very high hardness value, as is evident from the area below the stress-strain curves limited by the deformation of the fault. The hardness of the paint / PMMA blends is a surprising result that provides an improved alternative to pure PMMA.

Figures 7 and 8 present different scans of differential scanning calorimetry (DSC) of 35% / 65% by weight of Brilliant / HDPE and Brilliant / PMMA, respectively. The total heat flow and the derivative of the inverted heat flow are plotted against the temperature for both samples. In Figure 6, the Brilliant / HDPE sample, a glass transition of the paint component occurs at 14 ° C and a melting transition of the HDPE component occurs around 129 ° C. In Figure 7, the Brilliant / PMMA sample, a glass transition of the paint component occurs at 14 ° C and a glass transition of the PMMA component occurs at about 104 ° C.

The foregoing examples and description of the preferred embodiments should be taken as examples that do not limit the present invention defined by the claims. As will be readily appreciated, numerous variations and combinations of the features set forth above can be used without departing from the present invention as set forth in the claims. Said variations are not considered a departure from the spirit and scope of the invention, and all such variations are included within the scope of the following claims.

Claims (26)

1. A mixture of immiscible polymers comprising (a) a first polymer component comprising a polymeric paint phase and (b) a second polymeric component immiscible with the first polymeric component and selected from the group consisting of polyolefins and polymethylmethacrylate (PMMA).

2. The mixture according to claim 1, wherein the paint is selected from the group consisting of water-based paints, oil-based paints and solvent-based paints.

3. The mixture according to claim 2, wherein the water based paint is latex paint.

4. The mixture according to claim 3, wherein the latex paint is selected from the group consisting of matte paint and glossy paint.

5. The mixture according to claim 1, wherein said polyolefin is high density polyethylene (HDPE).

6. The mixture according to claim 3, wherein the latex paint is bright paint and the second polymeric component is PMMA.

7. The mixture according to claim 5, wherein the second polymer component comprises between 65% and 80% by weight of PMMA.

8. The mixture according to claim 7, wherein the second polymer component comprises 65% by weight of PMMA.

9. The mixture according to claim 5, wherein the second polymer component comprises between 65% and 80% by weight of HDPE.

10. The mixture according to claim 1, wherein the first polymer component also comprises a polymer miscible with the polymeric paint phase.

11. The mixture according to claim 1, wherein the first polymer component comprises a polymer phase of latex paint.

12. The mixture according to claim 1, wherein the polymeric paint phase comprises acrylates, vinyl acrylates, vinyl acetates, styrene acrylates, polyurethanes, epoxies, neoprene, alkyd polyesters, or a combination thereof.

13. A method for recycling paint, said method comprises mixing (a) a first polymeric component comprising a polymeric paint phase with (b) a second polymeric component immiscible with the first polymer component and selected from the group consisting of polyolefins and polymethylmethacrylate ( PMMA).

14. The method according to claim 13, wherein the first polymer component and the second polymer component are both in liquid form prior to mixing.

15. The method according to claim 13, wherein the paint is selected from the group consisting of water-based paints, oil-based paints, and solvent-based paints.

16. The method according to claim 15, wherein the water based paint is latex paint.

17. The method according to claim 13, wherein said polyolefin is high density polyethylene (HDPE).

18. The method according to claim 16, wherein the latex paint is selected from the group consisting of matte paint, semi-matt paint and gloss paint.

19. The method according to claim 13, which also comprises forming an article with the polymer blend.

20. The method according to claim 19, wherein the forming step comprises injection molding, thermoforming, rotational molding or extrusion molding.

21. An article comprising the polymer blend according to claim 1.

22. The article according to claim 21, wherein the article is selected from the group consisting of impact resistant substitutes for glass and packaging articles.

23. The article according to claim 22, wherein the packaging articles are selected from the group consisting of containers, merchandise bags, shrink films, shopping bags and industrial coatings.

24. An article formed by the method according to claim 13.

25. The article according to claim 24, wherein said article is selected from the group consisting of impact resistant substitutes for glass articles and for packaging.

26. The article according to claim 25, wherein the articles for packaging are selected from the group consisting of containers, merchandise bags, shrink films, bags for purchases and industrial coatings.