Patent Application
20070275227
The present invention is predicated on the discovery that improved urethane foam carpet backings can be prepared by substituting hydroxylated vegetable oils having a functionality of 1-4 for the vegetable oils and cross linkers employed products, compositions and methods of Pub-910. The inclusion of the hydroxylated vegetable oils in the formulations of the invention eliminates the necessity for including petrol-polyols in the mix ion order to achieve optimal results and properties. Moreover, the employment of the hydroxylated vegetable oils also removes the necessity for including cross linkers in the formulation.
The B-component is typically mixed in a standard mix tank and reacted with the A-component (in a one step process) just prior to the point of use. By varying the proportions of the reactants within the B-component and altering the mix with the quantity of A-component, flexibility, rigidity, density and hardness can be controlled (i.e. precoats, foams and laminates acquired). Thus, higher molecular weight and higher functionality isocyanates would result in a less flexible foam than the use of a lower molecular weight and lower functionality isocyanate with the same polyol.
Upon the combination of A-component and B-component reactants an exothermic reaction occurs which may reach completion in several minutes or several hours depending on the reactants and the concentrations used. The catalyst level is altered to accelerate or decelerate the reaction. Also, the blowing agent level is altered to affect the film structure thus forming a foam or polyurethane elastomer.
One embodiment of the invention relates to its utilization as a precoat layer for carpet. Traditionally a carpet can be broadloom, tile or rugs, woven or tufted into a primary substrate which is typically a woven or non woven, made of various fiber types such as polypropylene or polyester. A typical construction, for example, is a broadloom carpet tufted into a woven polypropylene primary. This construction is then percolated (knife over a roll, sprayed, etc.) on the back component with the biobased polyurethane composition of the invention. This is a very critical part of the process where both application and chemical formulation come together in order to accomplish:
After the point of precoat application, the biobased precoat is finish-cured, e.g., in a heated oven.
Another embodiment of the invention is its use as a coating over an already precoated carpet described in the above embodiment, in order to laminate thereto a secondary substrate. This substrate can be a woven, non-woven or a composite of both, made of various fiber types such as polypropylene, polyester or combinations thereof. After the introduction of the secondary into the biobased coating layer the composite is finished cured in a heated oven.
This laminated construction offers additional physical stability of the carpet composite through the manufacturing process. The laminated construction offers such additional attributes such as:
1) a bondable surface for direct adhesive installation;
2) physical strength needed during stretching in a direct glue installation; and
3) physical strength and integrity in a stretch-in over pins installation.
An additional embodiment of the invention is its utilization as a foam coating over the above-described precoated carpet. The carpet construction in then finished cured in a heated oven. The advantages of having applied foam to the carpet are:
1) comfort under foot,
2) insulation factors; and
3) carpet fiber/life retention increase.
A still further embodiment of the invention is its use as a foam coating over an already precoated carpet construction described above, followed by introducing a secondary into the foam structure. The secondary substrates that can be employed are described hereinabove. The carpet construction is then finish-cured in a heated oven.
Another embodiment of the invention is its employment as a precoat and laminate in a one step-application process.
The A-component comprises a polyisocyanate, and usually is based on diphenylmethane diisocyanate (“MDI”) or toluenediisocyanate (“TDI”). The particular isocyanate chosen will depend on the particular final qualities desired in the urethane. The B-component material is generally a solution of the hydroxylated vegetable oil, catalyst and blowing agent. A catalyst is also generally added to the B-component to control reaction speed and effect final product qualities.
It has been discovered, however, that flexible urethane foams of a high quality can be prepared by substituting the vegetable oils disclosed by Pub-910 with hydroxylated vegetable oils having a functionality of 1-4 and eliminating the multi-functional alcohol cross-linking agent The replacement is made on a substantially 1:1 weight ratio of vegetable oil for replaced petroleum-based polyol. The process of producing the urethane does not change significantly with the previously used vegetable oils and crosslinking agent replaced by the hydroxylated vegetable oil of the present invention; all of the other components and general methods being generally known in the art. The qualities of the final flexible or semi-rigid urethane foam produced using the hydroxylated vegetable oil are consistent with those produced using conventional high grade, expensive petrol-based polyol or mixtures thereof with the vegetable oils of Pub-910.
Further, it has surprisingly been discovered that with use of the hydrogenated vegetable oils of the invention, urethane foams of varying and selectable final qualities, including differing flexibilities, densities, and hardnesses, can be made by varying only the degree of hydrogenation. It would be difficult, if not impossible, to create such varied final foams using a single petroleum-based polyester or polyether polyol with the same variations in the remaining reactants. Instead, different petroleum-based polyols would be required to produce such varied results.
The use of only hydroxylated vegetable oil in the urethane forming reaction also realizes a significant cost savings. Vegetable oils are abundant, renewable, and easily processed commodities, as opposed to polyols, which are petroleum derivatives and which entail significant associated processing costs. As such, they may currently be acquired for a cost of approximately half that of average grade petroleum-based polyester or polyether polyols, and approximately one quarter the cost of high-grade petroleum-based polyester or polyether polyols. Also, as polyols derived from petroleum, they are not renewable and carry a certain environmental cost with them. There is a distinct marketing advantage to marketing products that are based on environmentally friendly, renewable resources such as vegetable oils.
As is well known in the art, functionality=the average number of isocyanate reactive sites per molecule. It is calculated according to the following formula:
Average functionality=(Total moles OH)/(Total moles polyol)
The hydoxyl number is a measure of the amount of reactive hydroxyl groups available for reaction. This value is determined by a wet analytical method and is reported as the number of milligrams of potassium hydroxide equivalent to the hydroxyl groups found in one gram equivalent of the sample:
OH number=(56.1×1000)/equivalent weight
The particular hydroxylated vegetable oil employed depends upon the desired characteristics in the resulting product (generally, the higher the functionality, the harder the compound). Hydroxylated soy oils having, but limited to, the following functionalities may be employed in the practice of the invention:
The hydroxylated vegetable oils suitable for use in the present invention are known in the art as shown in the examples. Alternatively, they may be prepared according to the methods of synthesis disclosed in U.S. Pat. Nos. 4,742,112 and 6,583,302; United States Patent Application Publication nos. 2006004115, 20060041156, 20030232956; 20040010095 and 20060041155; Okieimen et al, European Journal of Lipid Science and Technology, Volume 107, Issue 5, Pages 330-336; UK Patent GB2278350B;
http://www.mii.vt.edu/MACRO%202002/MACROP41.htm.
Suitable oils that may be hydroxylated for use according to the present invention include, e.g., soy, corn, safflower, sunflower, palm, cottonseed and the like.
The A-component isocyanate reactant of the urethane of the invention is preferably comprised of a isocyanate chosen from a number of suitable isocyanates as are generally known in the art. Different isocyanates may be selected to result in different final product properties. The A-component reactant of the urethane of the invention preferably comprises diphenylmethane diisocyanate (MDI).
The B-component reactant of the urethane reaction includes at least the hydroxylated vegetable oil and a blowing agent. It is believed that the isocyanate reacts with the fatty acids of the vegetable oil to produce the polymeric backbone of the urethane.
The hydroxylated vegetable oils that are suitable for use are available from Biobased Technologies and described in US application publication no. 20060041155, the entire contents and disclosure of which is incorporated herein by reference. The preferred vegetable oil is soy oil, although it is contemplated that other vegetable oils, such as rapeseed oil (also known as canola oil) and palm oil can be used in accordance with the present invention. Except for the preliminary blowing step where air is passed through the oil to remove impurities and to thicken it and hydroxylation to the desired functionality, the soy oil is otherwise unmodified. It does not require esterification as is required for some urethane products of the prior art.
Except for the use of the preferred unmodified, blown hydroxylated soy oil replacing the polyol, the preferred B-component reactant used to produce the foam of the invention is generally known in the art. Accordingly, preferred blowing agents for the invention are those that are likewise known in the art, and may be chosen from the group comprising 134A HCFC refrigerant available from Dow Chemical Co., Midland Mich., methyl isobutyl ketone (MIBK), acetone and methylene chloride. These preferred blowing agents boil to create vapor bubbles in the reacting mass. Should other blowing agents be used that react chemically, such as water, to produce a gaseous product, concentrations of other reactants may be adjusted to accommodate the reaction.
In addition to the B-component's soy oil and blowing agent, one or more catalysts may be present. Preferred catalysts for the urethanes of the present invention are those that are generally known in the art, and are most preferably tertiary amines chosen from the group comprising DABCO 33-LV (containing 33% of 1,4-diaza-bicyclco-octane and 67% dipropylene glycol) a gel catalyst available from Air Products Corporation; DABCO BL-22 blowing catalyst available from the Air Products Corporation; and POLYCAT 41 trimerization catalyst available from the Air Products Corporation.
Also, as known in the art, the B-component reactant may further comprise a silicone surfactant which functions to influence liquid surface tension and thereby influence the size of the bubbles formed and ultimately the size of the hardened void cells in the final foam product. This can effect foam density and foam rebound (index of elasticity of foam). Also, the surfactant may function as a cell-opening agent to cause larger cells to be formed in the foam. This results in uniform foam density, increased rebound, and a softer foam.
A molecular sieve may further be present to absorb excess water from the reaction mixture. The preferred molecular sieve of the present invention is available under the trade name L-Paste.
The preferred flexible and semi-rigid foams of the invention will have greater than approximately 60% open cells. The preferred flexible foam of the invention will also have a density of from 1 to 45 lb. per cubic foot and a Shore hardness of durometer from 20/70 and 20/95.
As noted above, there is described in copending application Ser. No. 10/059,278 [publication no. 20030143910], a carpet backing comprising a textile having at least one adherent polyurethane backing, the backing being prepared from a polyurethane forming composition which comprises: (A) a polyisocyanate and (B) a mixture of a vegetable oil, a cross-linking agent comprised of a multi-functional alcohol present in a ratio to said vegetable oil such that there are at least 0.7 moles of OH groups per mole of bulk vegetable oil, a catalyst, and a blowing agent. Other disadvantages associated with, e.g., commercially available soy oils utilized for preparing the backings of that invention include:
1) The soy oils contain a significant amount of unreactables (approximately 25 percent), thereby limiting the amount that could be used in the formulation to a maximum of 50 parts.
2) Another issue encountered was that the functionality and hydroxyl content could not be determined exactly and obviously fluctuated from batch to batch because the physical films prepared therefrom would demonstrate various index's changes, although the calculations remained the same.
3) Chain extenders (i.e., dipropylene glycol, tripropylene glycol and ethylene glycol) were required to maintain physical stability.
4) The use of these oils resulted in very high emissions of Volatile Organic Chemicals.
The hydroxylated oils utilized in the practice of the present invention are vastly superior to those previously employed because:
1) They contain a low percentage of unreactants (approximately 5%)
2) The functionally and content of hydroxyls are easily controlled and verifiable.
3) There is no need for chain extenders in the composition.
4) Volatiles are very low to none existent, thereby contributing a very low amount if any to the finished product.
5) The hydroxylated oils utilized in the present invention can be formulated with higher parts of fillers. This attribute allows the formulation, for example of 100 parts Agrol, 100 to 600 pts filler loading and 40 parts ISO. The combination of the stability of soy pricing, the rapid renewable aspect, and the acceptance of filler loading allows the manufacturer to address pricing with acceptable quality where such could not be accomplished with the old system or any petro polyol.
The urethane foam of the present invention is produced by combining the A-component reactant with the B-component reactant in the same manner as is generally known in the art. Advantageously, use of the vegetable oil to replace the petroleum-based polyol does not require significant changes in the method of performing the reaction procedure. Upon combination of the A and B component reactants, a reaction ensues which generates heat, and which may reach completion in anywhere from several minutes to several hours depending on the particular reactants and concentrations used. Typically, the reaction is carried out in a mold so that the foam expands to fill the mold, thereby creating a final foam product in the shape of the mold.
The components may be combined in differing amounts to yield differing results, as will be shown in the Examples presented in the Examples below. Generally, however, the preferred flexible foam of the invention B-component mixture, when using the preferred components, is prepared with the following general weight ratios:
Flexible urethane foams may be produced with differing final qualities using the same vegetable oil by varying the particular other reactants chosen. For instance, it is expected that the use of relatively high molecular weight and high functionality isocyanates will result in a less flexible foam than will use of a lower molecular weight and lower functionality isocyanate when used with the same vegetable oil.
The blowing agent may comprise any conventionally employed in the art and include methyl isobutyl ketone, acetone, water, mechanically frothed air and the like.
The above brief description sets forth rather broadly the more important features of the present disclosure so that the detailed description that follows may be better understood, and so that the present contributions to the art may be better appreciated. There are, of course, additional features of the disclosure that will be described hereinafter which will form the subject matter of the claims appended hereto. In this respect, before explaining the several embodiments of the disclosure in detail, it is to be understood that the disclosure is not limited in its application to the details and the arrangements set forth in the following description. The present invention is capable of other embodiments and of being practiced and carried out in various ways, as will be appreciated by those skilled in the art. Also, it is to be understood that the phraseology and terminology employed herein are for description and not limitation.
The polyurethane coatings may be prepared and applied to textiles in the manner described in the U.S. patents described hereinabove as well as U.S. Pat. No. 6,180,686, the entire contents and disclosures of each of which are incorporated herein by reference.
In the following non-limiting examples, the formulas listed below were employed:
The equipment employed to conduct the method consisted of 1) a small batching system that could mix up to 600 lbs. of chemicals for trials (2) a blending head for mixing polyols, iso and side adds (3) an applicator station and (4) an oven to cure the products. It was found that by pre-heating the soy polyol to 150° F. that the viscosity dropped to 80 centipoise and the filler (coal fly ash) could be charged from 200 up to 600 parts.
It was also found that by maintaining temperature at 150° F., agitating and recirculating the compound that the suspension of high filler loads and stabilization of the compound could be maintained indefinitely. It was also advantageous to heat all of the piping from storage to the blending head to maintain the low viscosity of the compound while moving it from storage to process.
By adding the catalyst too soon in a heated compound the reaction was generally too fast for efficient processing. Accordingly, there was developed a mechanical injection system that would deliver the catalyst at the exit side of the blender and just prior to the mixed compound going on the carpet. This system solved three critical needs: 1) finished reaction was maintained 2) compound strength was maximized and 3) processability of mixed compound was managed.
It will be understood by those skilled in the art that any conventional equipment for forming polyurethane foams and applying them to carpets may be employed in the practice of the invention. Exemplary of such equipment is that disclosed in Pub-910.
