Patent Application
20080081882
This invention provides a flooring product having at least one layer including a polymeric binder comprising thermoplastic polyester resin, wherein the polyester resin comprises at least one renewable component. The flooring product can comprise sheet or tile product structures. At least one layer in these structures may be solid or foamed, and filled or unfilled. In some embodiments, at least one layer comprises a transparent wear layer or wear layer component. Another example is similar to a vinyl composition tile (VCT), as described by ASTM Specification 1066-04. As used herein a polyester composition tile (PCT) is similar to a VCT except a polyester resin is substituted for the PVC. While the present invention is intended for use in such type tile, the invention is also directed to various other types of flooring, including tile type products such as Type III solid vinyl tile, surface applied tile, and to various sheet flooring products, wherein a polyester resin is substituted for the PVC. In one embodiment, at least one layer may comprise consolidated chips/particles having a binder comprising thermoplastic polyester resin. In another embodiment, at least one layer may be a homogeneous, melt processed layer having a binder comprising thermoplastic polyester resin. In yet another embodiment, the flooring product comprises renewable and recycle components that qualify the product for at least one point under the LEED System.
Unless at least one layer is transparent, it typically comprises a filler in addition to the polymeric binder. Limestone, talc, or other minerals are utilized as filler in flooring. Interest in using recycle materials as fillers has increased due to “green” issues. Such recycle filler materials include those obtained from wood or plants. These include pecan shells, wood flour, saw dust, walnut shells, rice hulls, corn cob grit, and others. Additionally, ground shells from animals such as clams and coral are renewable inorganic fillers. Such renewable fillers contain biobased carbon in the form of carbonates. These can be considered post-industrial or renewable materials.
Mineral fillers generated from post-industrial processes include limestone, quartz, ceramic powders, glass, fly ash, and concrete powder.
Recycle thermoset resin based fillers can also be employed. For example, powders produced by grinding thermoset polyester materials, such as products made from bulk molding compounds (BMC) or sheet molding compounds (SMC) can be post-industrial, as well as post-consumer materials. Another thermoset material of interest is recycled fillers made from Urea Formaldehyde thermoset resins. Depending upon the source, these materials can also be post-industrial or post-consumer. Another example includes ground, cured (cross-linked) rubber materials such as used in tires. These rubbers materials can be based on natural or synthetic rubbers, polyurethanes, or other well known thermoset rubber compositions.
Additionally, recycled thermoplastic resin based materials may be employed as fillers if they are incompatible with the polyester binder. For example, polyethylene (PE), polypropylene, polyamide, polyester, polystyrene, polycarbonate, acrylonitrile butadiene styrene, and thermoplastic rubbers maybe incompatible with the high molecular weight polyester binder. Such materials, if added as particulate will essentially function as fillers in these compositions. If the recycled thermoplastic resin is compatible with the binder, it may function as a binder and not as a filler in the composition. DuPont “Sarrona” Bio-PDO based carpet fiber may be recycled and would be a filler or binder depending upon compatibility with the binder. Compatibility may be dependent upon the processing conditions employed. Depending upon the source, these materials can be post-industrial or post-consumer.
In one embodiment, the thermoplastic, polyester resin is high molecular weight and has a number average molecular weight (Mn) of at least 5,000 and in some embodiments the polyester resins have a molecular weight (Mn) of at least 10,000. The polyesters may be biodegradable, and/or may contain renewable components. In one embodiment, the polyester comprises at least 50% by weight renewable components. In another embodiment, the polyester comprises greater than 80% by weight renewable components. In yet another embodiment, the polyester comprises essentially 100% renewable and recycle components.
In one embodiment, the polyester resin may comprise aliphatic diacid and aliphatic diol components. Although a wide range of aliphatic diacids and aliphatic diols may be used, these components may come from renewable sources. Renewable aliphatic diacid and aliphatic diol components may include but are not limited to Bio-PDO (1,3-propanediol), 1,4-butanediol, sebacic acid, succinic acid, adipic acid, azelaic acid, glycerin, and citric acid. These materials may also be modified by reaction with epoxidized soybean, epoxidized linseed oil, or other natural oils.
The polyesters may be pre-reacted with epoxidized natural oils, or the reaction can occur during the melt processing into flooring layers. Such reaction during melt processing is a type of dynamic vulcanization. Dynamic vulcanization is the process of intimate melt mixing of two or more reactive components, such as an acid-terminated polyester and epoxidized natural oil, and the reaction occurs between at least two of these components during the melt mixing.
Other diacid and diol components from renewable resources will become available as the need for renewable materials continues to grow. The diol components may also include diols which are branched or hindered to limit crystallinity in the final polyester binder. These can include neopentyl glycol, glycerin, and others.
Renewable components based on plants, animals, or biomass processes have a different radioactive C14 signature than those produced from petroleum. These renewable, biobased materials have carbon that comes from contemporary (non-fossil) biological sources. A more detailed description of biobased materials is described in a paper by Ramani Narayan, “Biobased & Biodegradable Polymer Materials: Rationale, Drivers, and Technology Exemplars”, presented at American Chemical Society Symposium, San Diego 2005; American Chemical Society Publication #939, June 2006. The Biobased Content is defined as the amount of biobased carbon in the material or product as fraction weight (mass) or percent weight (mass) of the total organic carbon in the material or product. ASTM D6866 (2005) describes a test method for determining Biobased Content. Theoretical Biobased Content was calculated for the resultant polyester resins in Table 2 and Table 3.
In one embodiment, the Biobased Content is at least 20% by weight. In another embodiment, the Biobased content is at least 50% by weight. In still another embodiment, the Biobased content is at least 75% by weight. The higher the Biobased Content the “greener” the product. The Biobased Content may be at least 25% by weight or at least 10% by weight or at least 5% by weight, particularly when the polyester resin is a blend of two or more resins.
In another embodiment, the thermoplastic polyester resin can comprise aromatic diacid components and aliphatic diol components. The aromatic acid components may include but are not limited to phthalic acid (anhydride), isophthalic, or terephthalic acids. In some cases an amount of trimellitic anhydride can also be used.
In another embodiment, the thermoplastic polyester resin may comprise aliphatic diacid and aromatic diacid components reacted with various aliphatic diols.
The thermoplastic polyester resin may also be branched. For example, utilizing aliphatic alcohols that have more than two functional groups, such as glycerin, or aromatic acids having more than two functional groups such as trimellitic anhydride may be used to produce branched polyesters.
Although, the above diacid components are described, it is understood that their simple diesters such as from methanol or ethanol can be used to prepare the thermoplastic polyester resin via known transesterification techniques.
Depending upon the diacid and diol selected, the polyester resin can be amorphous or crystalline/semi-crystalline materials. In one embodiment, the polyester resin is amorphous. Table 2 shows some examples of amorphous polyester resins of the invention and their % by weight renewable components.
In another embodiment, the polyester resin is crystalline and comprises a Tg below about 25° C. and a crystalline melting temperature Tm greater than about 25° C. In yet another embodiment, the polyester resin has a Tg at or below about 25° C. and a Tm between about 25° C. and about 200° C. Table 3 shows some examples of polyester resins having a Tg at or below about 25° C. and Tm above about 25° C. Tg and Tm were determined by standard Differential Scanning Calorimetry (DSC) techniques. The polyester compositions include modifying essentially 100% renewable aliphatic polyester resin by the addition of an amount of aromatic diacid, such as terephthalic acid, to help control crystalline regions and Tm. Example 3 describes tile flooring comprising blends of polyester resins, including a commercially available polyester resin, Ecoflex FBX7011, sold by BASF Plastics. Ecoflex FBX7011 is a high molecular weight, biodegradable, aliphatic-aromatic copolyester based on butanediol, adipic acid, and terephthalic acid exhibiting a Tg of about −25° C. and a Tm of about 115° C.
The blend of polyester resins allow processing in low intensity mixers typically used for VCT Tile manufacturing. Also, a desired Tg can be obtained by blending two or more polyester resins.
The polyester resin may be prepared by several known methods. One method involves esterification of a diacid and a diol components at elevated temperature. Typically, an excess of diol is employed (see Procedure 1A). After the acid functional groups have essentially reacted, a high vacuum is applied and excess diol is stripped off during transesterification, thereby increasing molecular weight. In some embodiments, 1,3-PDO is the diol of choice to build high molecular weight in this step of the process.
We have also found that polyester resin can be made by esterification of a diacid and diol at elevated temperature using an excess of diacid (See Procedure 1B). After all the hydroxyl groups are reacted, a high vacuum is applied to build molecular weight. The mechanism by which high molecular weight is achieved is not clear. Table 4 shows some examples of polyester resins comprising renewable components and the number average molecular weights obtained from the processes of Procedure 1.
Another method for obtaining high molecular weight polyester resin involves the co-reaction of a renewable polyester resin with recycle polyester resin such as PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PPT (polypropylene terephthalate) or other polyester resins. In these co-reactions, an aliphatic polyester resin comprising renewable ingredients was first prepared as described in Procedure 1. The recycle polyester resin was then mixed with the aliphatic polyester resin and transesterification between the two polyesters was accomplished at high temperature and preferably under high vacuum. In one embodiment, the polyester resin co-reaction product had a Tm at or below about 150° C. that allowed processing with in low intensity mixers. It is obvious that these transesterification reactions may be carried out on virgin PET, PPT or PBT resin if desired.
Molecular weight of the polyester resins were determined by Gel Permeation Chromatography (GPC) using the following procedure. The polyester resin was dissolved into tetrahydrofuran (THF), quantitatively diluting to ˜30 mg/ml and filtering with a 0.45 micron filter. Two drops of toluene were added to each sample solution as an internal flow rate marker.
Samples soluble in THF were run by the following conditions. GPC analysis was run on the TriSec instrument using a four column bank of columns with pore sizes: 106, 2 mixed D PLGel and 500 Angstroms. Three injections were made for the sample and calibration standards for statistical purposes. Universal Calibration (UC) GPC was used to determine MW. UC is a GPC technique that combines Refractive Index (RI) detection (conventional GPC) with Intrinsic Viscometry (IV) detection. Advantages of UC over conventional GPC are:
1. MW is absolute (not relative only to standards).
2. Yields information about branching of molecules.
The mobile phase for the THF soluble samples was THF at 1.0 ml/min. The data was processed using the Viscotek OmniSec UC software. The instrument is calibrated using a series of polystyrene narrow standards. To verify calibration, secondary standards were run. They include a 250,000 MW polystyrene broad standard, and a 90,000 MW PVC resin. The calculated molecular weight averages are defined as follows:
Highly crystalline or some high molecular weight samples insoluble in THF were dissolved in a 50/50 (wt.) mixture of tetrachloroethylene (TTCE)/phenol. The column set is 104 and 500 Angstrom 50 cm Jordi columns. The mobile phase was 50/50 (wt.) mixture of TTCE/phenol at 0.3 ml/min. flow rate. The slower flow rate is due to the greater back pressure of the solvent system on the columns. The data was processed using the Viscotek UC OmniSec software.
Since MW data must be compared from one column set to the other, standards and selected samples were run on both column sets in THF for comparison. A calibration curve was made for each column set. There is good agreement of the standards between the two sets.
Flooring products having at least one layer comprising thermoplastic polyester resin binder may be manufactured by processing methods known in the art, including but not limited to calendering, extruding, casting, consolidating, and laminating. In one embodiment, a formulation comprising the polyester resin binder was melt mixed using low intensity “dough type” mixers traditionally utilized in the manufacturing of VCT tile (See Example 3). In another embodiment, the temperature of the melt mixing in the low intensity “dough type” mixers was in the range typically used in the manufacture of PVC based VCT Tile. In yet another embodiment, the formulation comprising the polyester resin binder was melt mixed using traditional extruder type mixers, including Farrell type mixers. These may be processed at higher temperatures than typically utilized in “dough type” mixers for the preparation of PVC based VCT Tile. Varied techniques may be utilized to form these melt mixed formulations into layers of flooring products. In one embodiment, the melt mixed formulation comprising the polyester resin binder was calendered into a layer. In another embodiment, the melt mixed formulation may be processed into chips or particles. Various techniques for consolidating these chips or particles into flooring layers are well known in the art. In another embodiment, the melt mixed formulation may be extruded into a flooring layer.
1A: This describes the general procedure utilized to make thermoplastic, high molecular weight polyesters from diacids and diols. A desired polyester formulation was developed based upon mole equivalent weight of the diacid and diol functional groups. An excess of diol of the most volatile diol component of the formulation was employed in the formulation. In one embodiment, 1,3-propanediol was the excess diol of choice. The diacid and diol ingredients were added into a stainless steel vessel of a RC1 automated reactor (Mettler-Toledo Inc, 1900 Polaris Parkway, Columbus, Ohio), stirred and heated under a continuous flow of pure, dry nitrogen. Typically, the ingredients were heated to 200° C. for 2 hours and temperature increased to 230° C. for an additional 4 to 6 hours until essentially all acid end groups were reacted and theoretical amount of water removed. Subsequently, the nitrogen was stopped and a high vacuum was applied. The mixture was heat and stirred under high vacuum for an additional 4 or more hours at 230° C. to 300° C. In some cases the temperature of the transesterification step was increased to 250° C. or higher. Depending upon the experiment, a vacuum in the range of 5 mm of mercury was utilized. Subsequently, the polymer was allowed to cool to 150° C. to 200° C. and physically removed from the reactor under a flow of nitrogen and allowed to cool to room temperature.
It is understood that removal of the volatile diol component during transesterification leads to high molecular weight. High molecular weight may be obtained faster if higher vacuum is utilized (below 1 mm of mercury). It is also known that as the melt viscosity increases due to increased molecular weight, the removal of diol becomes more difficult. The increase in molecular weight can become diffusion dependent because of the high viscosity of the molten polyester. This means that the released volatile diol from the transesterification reaction reacts back into the polymer before it can diffuse out of the melt, and be removed. Renewing the surface of the melt can facilitate the loss of diol and increase molecular weight. The polyesters obtained by this procedure generally have terminal hydroxyl end groups.
Although, diacid components are described above, it is understood that their simple diesters such as from methanol or ethanol can be used to prepare the thermoplastic polyester resin via known transesterification techniques. The polyesters from this procedure generally have ester terminated end groups.
1B: The same general procedure as in 1A is employed. A desired polyester formulation was developed based upon mole equivalent weight of the diacid and diol functional groups. An excess of about 0.01 to 0.5 mole excess of diacid was typically employed in the formulation. The ingredients were mixed and heated as in 1A above, except that the temperature was generally held below 200° C. to keep acid/anhydride from being removed until all hydroxyl groups were reacted. Subsequently, a high vacuum was applied as in 1A and the mixture heated to between 230° C. and 280° C. and stirred as in Procedure 1A. The resultant high molecular weight polyester was removed from the reactor and cooled as in 1A.
The mechanism of achieving high molecular weight is not clear. In some formulations containing phthalic anhydride, the phthalic anhydride was identified as being removed from the mixture. Using a nitrogen sparge below the surface of the molten polyester during the vacuum step also helped produce high molecular weight polyesters. The polyesters obtained by this procedure generally have terminal acid end groups.
Tables 5A to 5E provide examples of polyester resins having renewable components made according to the procedure of Procedure 1.
The following formulation was processed as per Procedure 1 to prepare the aliphatic polyester Ex-42 comprising 100% renewable components and a Biobased Content of 100%.
The aliphatic polyester Ex-42 was mixed with clear PET bottle recycle resin obtained from Nicos Polymers & Grinding of Nazareth, Pa., and catalyst added as listed below.
The mixture was heated and stirred under nitrogen at 265° C. for a period of about 3 hours, and a high vacuum applied as in Procedure 1 for an additional 3 hours at 265° C. Subsequently, the resultant polyester having 50% by weight renewable content and 50% by weight recycle content was shown to have a molecular weight Mn of 17,200 with a Tg of −9° C. and a Tm of 114° C. Molecular weight Mn of the starting PET recycle bottle resin was determined by GPC techniques described above and found to be 14,000. A sample of PET film obtained from Nicos Polymers & Grinding was also analyzed by GPC and molecular weight Mn determined to be 17,300.
This is an example of PCT tile flooring product prepared with a binder comprising a thermoplastic, high molecular weight polyester resin. Traditionally, VCT tile manufacturing processes have utilized low intensity “dough” type heated mixers to compound/melt mix the tile formulation which is subsequently calendered into a layer. Higher intensity mixers such as extruders or Farrell type mixers may also be employed, and these high intensity mixers may also be heated to higher temperatures to compound the tile formulation.
The following PCT tile formulations Table 6B-D, comprising amorphous, polyester resins GPa02176—of Table 5C and 5D, were mixed using a low intensity Baker Perkins heated mixer. The ingredients were added to the mixer which was heated to 325° F. The formulations were mixed and heated for approximately 7-11 minutes on average in the Baker Perkins mixer to a drop temperature of approximately 280° F. Depending upon the formulation, mixing time varied between 7-28 minutes and drop temperature varied between approximately 270° F. and 290° F. (See Table 6B-D).
The hot, mixed formulations were then dropped into the nip of a two roll calender. The rolls of the calendar were set at different temperatures—one roll hotter than the other. Typically, the hot roll was set at about 290° F. and the cold roll set at about 250° F. The nip opening between the calendar mill rolls were set to provide a final sheet thickness of about 125 mils. The processability of the formulations were evaluated using the key described in Table 6A.
As can be seen from a formulation and processing datasheet Tables 6B-6D, the formulation based upon high molecular weight polyesters processed very similar to a standard PVC formulations. Formulations of Tables 6B-6D are based on blends of Armstrong amorphous polyesters of Tables 5C-5D with Ecoflex FBX7011 polyester sold by BASF. Ecoflex FBX7011 is a high molecular weight, biodegradable, aliphatic-aromatic copolyester based on butanediol, adipic acid, and terephthalic acid exhibiting a Tg of about −25° C. and a Tm of about 115° C. The tiles exhibited acceptable physical properties, with a significant improvement in breaking load strength.
It is important to note that formulations based only on Ecoflex FBX7011 in pellet form could not be adequately mixed in the low intensity mixer. There was not enough heat transfer and shear within the mix to breakdown the pellet form of the Ecoflex 7011. The addition of the amorphous polyester resin changed the physical nature of the mix allowing the Ecoflex 7011 to be incorporated.
Tile and sheet formulations may also contain other ingredients such as processing aids, tackifiers, hydrophobic agents, stabilizers, colorants and other known additives. Of particular interest, the tile formulations may also contain up to 30% by weight of one or more additional polymers and sheet formulations may also contain up to 50% by weight of one or more additional polymers. These additional polymers may assist in processing in low intensity mixers, and also may assist in achieving improved physical properties. These polymers may consist of acid functionalized polymers including EAA, EMA, and partially neutralized versions thereof (ionomers), Surlyn, or other (methacrylic) acrylic acid, or maleic acid (anhydride) copolymers to obtain desired process and physical properties.
The use of recycle fillers in these formulations also allows for the flooring product having at least one layer comprising the high molecular weight polyester binder to achieve at least one point within the LEED System.
High molecular weight polyester of the composition in table 5E was prepared as per Procedure 1. The high molecular weight polyester was formulated into a PCT tile formulation and processed as in Example 3. The datasheet Table 7 describes the conditions used to make the tile. The tile exhibited acceptable physical properties, with a significant improvement in breaking load strength.
High molecular weight polyesters comprising the compositions of Table 8A were made according to Procedure 1.
The polyesters of Table 8A, were each mixed with recycle PET bottle resin obtained from Nicos Polymers & Grinding of Nazareth, Pa., and 0.1% T-20 catalyst added and transesterification conducted as per Example 2. In some examples, transesterification was also carried out on PBT resin Celanex 1600A obtained from Ticona (formerly Hoechst Celanese Corp.), Summit, N.J. Table 8B shows some of the resultant polyester co-reaction products and their Tm. It is obvious that these transesterification reactions may be carried out on virgin PET or PBT type resin.
The melting points listed in Table 8B were determined using an “Optimelt” automated unit. Higher Tm co-reacted polyesters may be produced by using less aliphatic polyester than described in the Table 8B above.
Formulations based on the polyester reaction products of Table 8B were developed to allow processing in low shear Baker Perkins heated mixers and VCT type calendaring processing. The formulations in Table 8C and Table 8D include EAA (ethylene acrylic acid copolymer) and an acrylic processing aid. The use of EAA not only effect processing in the Baker Perkins and through the calendar, but the polymer also imparts stiffness and some improved properties.
A high molecular weight polyester comprising the composition in Table 9A was prepared as per Procedure 1.
PCT tile formulations based on the polyester of Table 9A were developed to allow processing in low shear Baker Perkins heated mixers and VCT type calendaring processing. The formulations in Table 9B include EAA (ethylene acrylic acid copolymer) and an acrylic processing aid. The use of EAA not only effect processing in the Baker Perkins and through the calendar, but the polymer also imparts stiffness and some improved properties.
The use of different sized limestone filler yields better processibility and improved performance.
A high molecular weight polyester comprising the composition Table 10A was prepared according to Procedure 1.
PCT tile formulations based on the high molecular weight polyester of Table 10A were developed to allow processing in low shear Baker Perkins heated mixers and VCT type calendaring processing as per Example 3. The formulation datasheets in Table 10B include the use of a hydrocarbon tackifier, epoxidized soybean oil and Surlyn ionomer additives. Surlyn ionomer may not only effect processing in the Baker Perkins and through the calendar rolls, but Surlyn may also impart some improved properties to the finished tile. In cases where ESO or other epoxidized oils are also used in combination with acid functionalized polymers, these may react with each other (dynamic cross-linking) during processing of the formulation at elevated temperature.
