BACKGROUND OF THE INVENTION
Because of their widely ranging mechanical properties and their ability to be relatively easily machined and formed, plastic foams and elastomers have found wide use in a multitude of industrial and consumer applications. In particular, urethane materials, such as foams and elastomers, have been found to be well suited for many applications. Automobiles, for instance, contain a number of components, such as cabin interior parts, that are comprised of urethane foams and elastomers. Urethane foams are also used as carpet backing. Such urethane foams are typically categorized as flexible, semi-rigid, or rigid foams with flexible foams generally being softer, less dense, more pliable, and more subject to structural rebound subsequent to loading than rigid foams.
The production of urethane foams and elastomers are well known in the art. Urethanes are formed when isocyanate (NCO) groups react with hydroxyl (OH) groups. The most common method of urethane production is via the reaction of a polyol and a diisocyanate, which forms the backbone urethane group. A cross-linking agent and/or chain extender may also be added. Depending on the desired qualities of the final urethane product, the precise formulation may be varied. Variables in the formulation include the type and amounts of each of the reactants and additives.
In the case of a urethane foam, a blowing agent is added to cause gas or vapor to be evolved during the reaction. The blowing agent is one element that assists in creating the size of the void cells in the final foam, and commonly is a solvent with a relatively low boiling point or water. A low boiling solvent evaporates as heat is produced during the exothermic isocyanate/polyol reaction to form vapor bubbles. If water is used as a blowing agent, a reaction occurs between the water and the isocyanate group to form an amine and carbon dioxide (CO2) gas in the form of bubbles. In either case, as the reaction proceeds and the material solidifies, the vapor or gas bubbles are locked into place to form void cells. Final urethane foam density and rigidity may be controlled by varying the amount or type of blowing agent used.
A cross-linking agent is often used to promote chemical cross-linking to result in a structured final urethane product. The particular type and amount of cross-linking agent used will determine final urethane properties such as elongation, tensile strength, tightness of cell structure, tear resistance, and hardness. Generally, the degree of cross-linking that occurs correlates to the flexibility of the final foam product. Relatively low molecular weight compounds with greater than single functionality are found to be useful as cross-linking agents.
Catalysts may also be added to control reaction times and to effect final product qualities. The catalysts generally effect the speed of the reaction. In this respect, the catalyst interplays with the blowing agent to effect the final product density. Preferably, for foam urethane production, the reaction should proceed at a rate such that maximum gas or vapor evolution coincides with the hardening of the reaction mass. The catalyst may also effect the timing or speed of curing so that a urethane foam may be produced in a matter of minutes instead of hours.
Polyols currently used in the production of urethanes are petrochemicals being generally derived from propylene or ethylene oxides. Polyester polyols and polyether polyols are the most common polyols used in urethane production. For flexible foams, polyester or polyether polyols with molecular weights greater than 2,500, are generally used. For semi-rigid foams, polyester or polyether polyols with molecular weights of 2,000 to 6,000 are generally used, while for rigid foams, shorter chain polyols with molecular weights of 200 to 4,000 are generally used. There is a very wide variety of polyester and polyether polyols available for use, with particular polyols being used to engineer and produce a particular urethane elastomer or foam having desired particular final toughness, durability, density, flexibility, compression set ratios and modulus, and hardness qualities. Generally, higher molecular weight polyols and lower functionality polyols tend to produce more flexible foams than do lower molecular weight polyols and higher functionality polyols. In order to eliminate the need to produce, store, and use different polyols, it would be advantageous to have a single, versatile, renewable component that was capable of being used to create final urethane foams of widely varying qualities.
Currently, one method employed to increase the reactivity of petroleum based polyols includes propoxylation or ethoxylation. When propoxylation or ethoxylation is done on conventional petroleum based polyols, current industry practice is to employ about 70% propylene oxide by weight of the total weight of the polyol and propylene oxide to complete the reaction. Due to the large amount of alkyloxide typically used, the reaction if the alkyloxide and the petroleum based polyol is extremely exothermic and alkyloxides can be very expensive to use, especially in such high volumes. The exothermic nature of the reaction requires numerous safety precautions be undertaken when the process is conducted on an industrial scale.
Use of petrochemicals such as, polyester or polyether polyols is disadvantageous for a variety of reasons. As petrochemicals are ultimately derived from petroleum, they are a non-renewable resource. The production of a polyol requires a great deal of energy, as oil must be drilled, extracted from the ground, transported to refineries, refined, and otherwise processed to yield the polyol. These required efforts add to the cost of polyols and to the disadvantageous environmental effects of its production. Also, the price of polyols tends to be somewhat unpredictable. Their price tends to fluctuate based on the fluctuating price of petroleum.
Also, as the consuming public becomes more aware of environmental issues, there are distinct marketing disadvantages to petrochemical based products. Consumer demand for “greener” “bio-based” products continues to grow. The term “bio-based” or “greener” polyols for the purpose of this application is meant to be broadly interpreted to mean all polyols not derived exclusively from non-renewable resources. Petroleum and bio-based copolymers are also encompassed by the term “bio-based”. As a result, it would be most advantageous to replace polyester or polyether polyols, as used in the production of urethane elastomers and foams, with more versatile, renewable, less costly, and more environmentally friendly components.
The difficulties in the past that occurred due to the use of vegetable oil as the polyols to produce a urethane product include the inability to regulate the functionality of the polyol resulting in variations in urethane product where the industry demands relatively strict specifications be met and the fact that urethane products, in the past, outperformed vegetable oil based products in quality tests, such as carpet backing pull tests.
An unresolved need therefore exists for an improved functionality, vegetable oil based polyol of increased and selectable functionality for use in manufacturing a urethane materials such as, elastomers and foams. Also needed is a method of producing such urethane materials using the improved functionality, vegetable oil based polyol based on a reaction between isocyanates alone or as a prepolymer, in combination with the improved functionality polyol or a blend of the improved functionality polyol and other polyols including petrochemical based polyols. The products and methods of the present invention are particularly desirable because they relate to relatively inexpensive, versatile, renewable, environmentally friendly materials such as, vegetable oil, more particularly blown soy oil, transesterified with a saccharide, polysaccharide, or a sugar alcohol to form a polyol of increased and selectable functionality that can be a replacement for soy or petroleum based polyether or polyester polyols typically employed.
SUMMARY OF THE INVENTION
This invention generally relates to a new vegetable oil based polyol of increased and selectable functionality and the method of producing the new polyol by oxylation of a vegetable oil based polyol. The invention also generally relates to the use of the oxylated vegetable oil based polyol in all urethane products such as foams, elastomers, or rigid plastics.
These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A new vegetable oil based polyol having increased and selectable functionality has been developed. A two-stage transesterification process produces the new vegetable oil based polyol as the reaction product of a multifunctional alcohol and a multifunctional component, subsequently reacted with a vegetable oil. In the first step in the two-stage transesterification process, glycerin, a suitable multifunctional alcohol, or other suitable multifunctional alcohol is heated to about 230° F., and advantageously also stirred; however, a catalyst may be used instead of or in addition to heat. Next, a multifunctional component having at least two hydroxyl groups preferably includes a saccharide compound, typically a monosaccharide, disaccharide, a polysaccharide, sugar alcohol, cane sugar, honey, or mixture thereof is slowly introduced into the glycerin until saturated. Currently, the preferred saccharide components are fructose and cane sugar. Cane sugar provides greater tensile strength and fructose provides greater elongation of the carbon chain of the polyol. Preferably, 2 parts of the saccharide compound is added to 1 part of the multifunctional alcohol, by weight. Glycerin is a carrier for the saccharide compound component, although it does add some functional hydroxyl groups. The saccharide component is slowly added until no additional saccharide component can be added to the glycerin solution.
It is believed that the multifunctional alcohol and the saccharide component undergo an initial transesterification to form new ester products (precursors). As such, the functionality of the new polyol is selectable. The greater the functionality of the alcohol, the greater the functionality of the final new polyol.
Next, from about 200 to 300 grams (experimental amount) of vegetable oil, preferably soy oil, and most preferably blown soy oil, is heated to at least about 180° F. However, the temperature may be any temperature from about 180° F. until the oil is damaged. Blown soy oil provides superior results to regular vegetable oil; however, any vegetable oil or blown vegetable oil will work. Other vegetable oils that may be utilized in the present invention include, but should not be limited to, palm oil, safflower oil, sunflower oil, canola oil, rapeseed oil, cottonseed oil, linseed, and coconut oil. When these vegetable oils are used, they too are preferably blown. However, the vegetable oils may be crude vegetable oils or crude vegetable oils that have had the soap stock and wax compound in the crude oil removed.
Once the blown soy oil has been heated, it is slowly reacted with the heated glycerin/saccharide ester, the first transesterification reaction product. The vegetable oil and the first transesterification product undergo a second transesterification reaction that increases the functionality of the resulting polyol. Lowering the amount of the saccharide component added to the vegetable oil lowers the number of functional groups available to be cross-linked with an isocyanate group when the polyol produced using the two-stage transesterification process outlined above is used to create a urethane product. In this manner, functionality of the final polyol produced by the transesterification process of the present invention may be regulated and engineered. Therefore, more rigid urethane products are formed using a polyol produced by the present invention by using increased amounts of a saccharide component. In addition, as discussed above, the higher functionality of the multifunctional alcohol may also increase the functionality of the urethane products formed using the new polyol.
Also, polyols having increased functionality can not only be made by the transesterification process discussed above alone, but a further increase in functionality of a vegetable oil based polyol may also be achieved by oxylation (propoxylation, butyoxylation, or ethoxylation). The addition of propylene oxide (propoxylation), ethylene oxide (ethoxylation), butylene oxide, (butyloxylation), or any other known alkene oxides to a vegetable oil, a crude vegetable oil, a blown vegetable oil, the reaction product of the saccharide (multifunctional compound) and the multifunctional alcohol, or the final vegetable oil based, transesterified polyol produced according to the transesterification process discussed above will further increase the functionality of the polyol thereby formed.
Applicants currently believe that bio-based oxylation substances, such as, tetrahydrofuran (TMF), tetrahydrofurfuryl, tetrahydrofurfural, and furfural derivatives as well as tetrahydrofurfuryl alcohol may be used instead of or in addition to alkyloxides in the present invention.
Moreover, Applicants believe that any substance containing an active hydrogen may be oxylated to any desired degree and subsequently transesterified. Once transesterified with the vegetable oil, a compound whose active hydrogens were not fully oxylated may be further oxylated. Some active hydrogens include OH, SH, NH, chorohydrin, or any acid group. Compounds containing these active hydrogens, such as ethylene diamine, may be partially (because it contains more than one active hydrogen) or fully oxylated and then transesterified with the multifunctional alcohol, a crude vegetable oil, a blown vegetable oil, the reaction product of the saccharide (multifunctional compound) and the multifunctional alcohol, or the final vegetable oil based, transesterified polyol produced according to the transesterification process discussed above will further increase the functionality of the polyol thereby formed.
When propoxylation or like reactions are done to the vegetable oil or the transesterified polyol, an initiator/catalyst is typically employed to start and, throughout the reaction, to maintain the reaction of the propylene oxide and the vegetable oil to the transesterified polyol. The resulting reaction is an exothermic reaction. Initiators/catalysts that may be employed in the propoxylation, ethyoxylation, or butyloxylation reaction include triethylamine, trimethylamine, or other suitable amines as well as potassium hydroxide or other suitable metal catalyst.
Significantly, while about 70% by weight of alkyloxides is typically used to fully oxylate a petroleum based polyol, when oxylation of crude, blown, or transesterified vegetable based polyols is conducted, only about 5% to about 10% of the oxylation compound is necessary. As a result, Applicants have found that, in experimental amounts, the reaction is not nearly as exothermic as a “typical” oxylation reaction using a petroleum based product. As a result, Applicants believe this will be a significant safety benefit when done at production scale. Applicants have suprisingly found that adding heat to the oxylation reaction employing a vegetable based polyol is preferred. On an industrial scale, this may provide the additional benefit of regulating reaction time. Obviously, since significantly less oxylation raw material is used when oxylation is done to the vegetable based polyol of the present invention, significant cost savings result as well. Additionally and probably most significantly, oxylation of the vegetable based polyols of the present invention, either blown or transesterified, results in a vegetable oil based polyol with improved reactive and chemical properties.
In practice, the alkyloxide or bio-based oxylation compound and a suitable catalyst/initiator are added to a vegetable oil, preferably a blown or transesterified vegetable oil and mixed. The resultant mixture is then heated until the temperature reaches about 100° C. The temperature is held at about 100° C. for about one to about two hours. The mixture is then cooled to ambient temperature while pulling a vacuum to remove any excess alkyloxide or bio-based oxylation compound.
Moreover, it has been contemplated that the above described transesterification process may be performed on crude or non-blown vegetable (soy) oil prior to blowing the vegetable (soy) oil to form a pre-transesterified vegetable (soy) oil. The pre-transesterified vegetable (soy) oil may then be blown, as known, to increase its functionality. Thereafter, the transesterification process discussed above may optionally be carried out again on the blown pre-transesterified vegetable (soy) oil.
A transesterification catalyst such as tetra-2-ethylhexyl titonate, which is marketed by DuPont® as Tyzor® TOT, may be used, instead of or in addition to heat. Also, known acids and other transesterification catalysts known to those of ordinary skill may also be used.
The preparation of urethanes is well known in the art. They are generally produced by the reaction of petrochemical polyols, either polyester or polyether, with isocyanates. The flexibility or rigidity of the foam is dependent on the molecular weight and functionality of the polyol and isocyanate used.
Petrochemical polyol based polyurethanes can be prepared when what is known in the art as an A-side reactant is combined with what is known in the art as a B-side reactant. The A-side reactant of the urethane of the invention comprises an isocyanate, typically a diisocyanate such as: 4,4′ diphenylmethane diisocyanate; 2,4 diphenylmethane diisocyanate; and modified diphenylmethane diisocyanate. Typically, a modified diphenylmethane diisocyanate is used. Mondur MR Light®, an aromatic polymeric isocyanate based on diphenylmethane-diisocyanate, and Mondur® MA-2903, a new generation MDI prepolymer, manufactured by Bayer® Corporation, are two specific examples of possible isocyanates that can be used. It should be understood that mixtures of different isocyanates may also be used. The particular isocyanate or isocyanate mixture used is not essential and can be selected for any given purpose or for any reason as desired by one of ordinary skill in the art.
The A-side of the reaction may also be a prepolymer isocyanate. The prepolymer isocyanate is the reaction product of an isocyanate, preferably a diisocyanate, and most preferably some form of diphenylmethane diisocyanate (MDI) and a vegetable oil. The vegetable oil can be any of the vegetables discussed previously or any other oil having a suitable number of reactive hydroxyl (OH) groups. Soy oil is particularly advantageous to use. To create the prepolymer diisocyanate, the vegetable oil, the transesterified vegetable oil or a mixture of vegetable oils and transesterified vegetable oils are mixed and allowed to react until the reaction has ended. There may be some unreacted isocyanate (NCO) groups in the prepolymer. However, the total amount of active A-side material has increased through this process. The prepolymer reaction reduces the cost of the A-side component by decreasing the amount of isocyanate required and utilizes a greater amount of inexpensive, environmentally friendly vegetable (soy) oil. Alternatively, after the A-side prepolymer is formed, additional isocyanates may be added
The B-side material is generally a solution of a petroleum based polyester or polyether polyol, cross-linking agent, and blowing agent. A catalyst is also generally added to the B-side to control reaction speed and effect final product qualities. As discussed infra, the use of a petrochemical such as, a polyester or polyether polyol is undesirable for a number of reasons.
It has been discovered that urethane materials of high quality can be prepared by substituting the petroleum based polyol in the B-side preparation with the increased and selectable functionality polyol produced by the transesterification process outlined above. Using Applicants' method permits substantial regulation of the functionality of the resulting polyol thereby making the polyols produced by Applicants' new process more desirable to the industry. Previously, the functionality of vegetable oil based polyols varied dramatically due to, for example, genetic or environmental reasons.
In addition to the increased and selectable functionality polyol produced by the transesterification process outlined above, the B-side of the urethane reaction may include a cross-linking agent. Surprisingly, a cross-linking agent is not required when using the new transesterified polyol to form a urethane product. Typically, a blowing agent and a catalyst are also used in the B-side of the reaction. These components are also optional, but are typically used to form urethane product, especially foams.
A currently preferred blown soy oil typically has the following composition; however, the amounts of each component vary over a wide range. These values are not all inclusive. Amounts of each components of the oil vary due to weather conditions, type of seed, soil quality and various other environmental conditions:
|100% Pure Soybean Oil Air Oxidized |
| ||Moisture ||1.15% || |
| ||Free Fatty Acid ||1-6%, typically ≈ 3% |
| ||Phosphorous ||50-200 ||ppm |
| ||Peroxide Value ||50-290 ||Meq/Kg |
| ||Iron ||≈6.5 ||ppm |
| || ||(naturally occurring amount) |
| ||Hydroxyl Number ||42-220 ||mgKOH/g |
| ||Acid Value ||5-13 ||mgKOH/g |
| ||Sulfur ||≈200 ||ppm |
| ||Tin ||<.5 ||ppm |
| || |
Blown soy oil typically contains a hydroxyl value of about 100-180 and more typically about 160, while unblown soy oil typically has a hydroxyl value of about 30-40. The infrared spectrum scans of two samples of the type of blown soy oil used in the present invention are shown in FIGS. 1 and 2. Blown soy oil and transesterified soy oil produced according to the present invention have been found to have a glass transition at about −137° C. to about −120° C. depending on the saccharide component used and whether one is used at all. The glass transition measures the first signs of molecular movement in the polymer at certain temperatures. The glass transition can be measured using a Dynamic Mechanical Thermal (DMT) analysis machine. Rheometric Scientific is one manufacturer of DMT machines useful with the present invention. Applicants specifically utilize a DMTA5 machine from Rheometric Scientific.
Applicants have also found that soybean oil and most other vegetable oils have C3 and C4 acid groups, which cause bitter smells when the vegetable polyols are reacted with isocyanates. In order to remove these acid groups and the resultant odor from the end use product, Applicants have also developed a way to effectively neutralize these lowering acids with the functionality of the polyol.
Applicants blow nitrogen (N2) through a solution of about 10% ammonium hydroxide. Nitrogen gas was selected because it does not react with the ammonium hydroxide. Any gas that does not react with the ammonium hydroxide while still mixing the ammonium hydroxide through the vegetable oil would be acceptable. The ammonium hydroxide neutralizes acid groups that naturally occur in the vegetable oil. The pH of transesterified, blown, and crude vegetable oil typically falls within the range of from about 5.9-6.2. Vegetable oil neutralized by the above-identified process has a typical pH range of from about 6.5 to about 7.2, but more typically from about 6.7 to 6.9. The removal of these C3 and C4 acid groups results in a substantial reduction in odor when the neutralized polyols are used to form isocyanates.
Except for the use of the transesterified polyol replacing the petroleum based polyol, the preferred B-side reactant used to produce urethane foam is generally known in the art. Accordingly, preferred blowing agents, which may be used for the invention, are those that are likewise known in the art and may be chosen from the group comprising 134A HCFC, a hydrochloroflurocarbon refrigerant available from Dow Chemical Co. of Midland, Mich.; methyl isobutyl ketone (MIBK); acetone; a hydroflurocarbon; cyclopentane; methylene chloride; any hydrocarbon; and water or mixtures thereof. Presently, a mixture of cyclopentane and water is preferred. Another possible blowing agent is ethyl lactate, which is derived from soybeans and is bio-based. At present, water is the preferred blowing agent when a blowing agent is used. The blowing agents, such as water, react with the isocyanate (NCO) groups, to produce a gaseous product. The concentrations of other reactants may be adjusted to accommodate the specific blowing agent used in the reaction.
As discussed above, when blown soy oil is used to prepare the transesterified polyol of the B-side, the chain extender (cross-linking agent) may be removed from the B-side of the urethane reactions and similar properties to urethane products produced using soy oil according to the teachings of WO 00/15684 and U.S. Pat. No. 6,180,686, the disclosures of which are hereby incorporated by reference, are achieved.
If cross-linking agents are used in the urethane products of the present invention, they are also those that are well known in the art. They must be at least di-functional (a diol). The preferred cross-linking agents for the foam of the invention are ethylene glycol; 1,4 butanediol; diethanol amines; ethanol amines; tripropylene glycol, however, other diols and triols or greater functional alcohols may be used. It has been found that a mixture of tripropylene glycol; 1,4 butanediol; and diethanol amines are particularly advantageous in the practice of the present invention. Dipropylene glycol may also be used as a cross-linking agent. Proper mixture of the cross-linking agents can create engineered urethane products of almost any desired structural characteristics.
In addition to the B-side's vegetable oil, the optional blowing agent(s), and optional cross-linking agents, one or more catalysts may be present. The 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® comprised of 33% 1,4 diaza-bicyclco-octane (triethylenediamine) and 67% dipropylene glycol, a gel catalyst available from the Air Products Corporation; DABCO® BL-22 blowing catalyst available from the Air Products Corporation; POLYCAT® 41 trimerization catalyst available from the Air Products Corporation; Dibutyltin dilaurate; Dibutyltin diacetate; stannous octane; Air Products' DBU® (1,8 Diazabicyclo [5.4.0] dibutyltin dilaurate); and Air Products' DBU® (1,8 Diazabicyclo [5.4.0] dibutyltin diacetate). Other amine catalysts, including any metal catalysts, may also be used and are known by those of ordinary skill in the art.
Also as known in the art, when forming foam urethane products, the B-side 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 a final urethane 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 urethane materials (products) of the present invention are produced by combining the A-side reactant with the B-side reactant in the same manner as is generally known in the art. Advantageously, use of the transesterified polyol 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 side reactants, an exothermic reaction ensues that may reach completion in anywhere from a few seconds (approximately 2-4) to several hours or days depending on the particular reactants and concentrations used. Typically, the reaction is carried out in a mold or allowed to free rise. The components may be combined in differing amounts to yield differing results, as will be shown in the Examples presented below.
A petroleum based polyol such as polyether polyol (i.e., Bayer corporation's Multranol® 3901 polyether polyol and Multranol® 9151 polyether polyol), polyester polyol, or polyurea polyol may be substituted for some of the transesterified polyol in the B-side of the reaction, however, this is not necessary. This preferred B-side formulation is then combined with the A-side to produce a urethane material. The preferred A-side, as discussed previously, is comprised of methylenebisdiphenyl diisocyanate (MDI) or a prepolymer comprised of MDI and a vegetable oil, preferably soy oil or a prepolymer of MDI and the transesterified polyol.
Flexible urethane foams may be produced with differing final qualities by not only regulating the properties of the transesterified polyol, but by using the same transesterified polyol and 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 transesterified polyol. Likewise, as discussed earlier, the higher the functionality of the polyol produced by the transesterification process, the more rigid the foam produced using it will be. Moreover, it has been contemplated that chain extenders may also be employed in the present invention. For example, butanediol, in addition to acting as a cross-linker, may act as a chain extender.
Urethane elastomers can be produced in much the same manner as urethane foams. It has been discovered that useful urethane elastomers may be prepared using the transesterified polyol to replace some of or all of the petroleum based polyester or the polyether polyol. The preferred elastomer of the invention is produced using diphenylmethane diisocyanate (MDI) and the transesterified polyol. A catalyst may be added to the reaction composition. The resulting elastomer has an approximate density of about 52 lb. to about 75 lb. per cubic foot.
The following examples are the preparation of transesterified polyol of the present invention, as well as foams and elastomers of the invention formed using the transesterified polyol. The examples will illustrate various embodiments of the invention. The A-side material in the following examples is comprised of modified diphenylmethane diisocyanate (MDI), unless otherwise indicated; however, any isocyanate compound could be used.
Also, “cure,” if used in the following examples, refers to the final, cured urethane product taken from the mold. The soy oil used in the following examples is blown soy oil. Catalysts used include “DABCO 33-LV®,” comprised of 33% 1,4-diaza-bicyclo-octane and 67% dipropylene glycol available from the Air Products Urethanes Division; “DABCO® BL-22,” a tertiary amine blowing catalyst also available from the Air Products Urethanes Division; “POLYCAT® 41” (n, n′, n″, dimethylamino-propyl-hexahydrotriazine tertiary amine) also available from the Air Products Urethanes Division; dibutyltin dilaurate (T-12); dibutyltin diacetate (T-1); and Air Products DBU® (1,8 Diazabicyclo [5.4.0]). The structures of the Air Products DBU®'s (1,8 Diazabicyclo [5.4.0]) used in the present invention are shown in FIG. 4.
A blowing catalyst in the following examples effects the timing of the activation of the blowing agent. Some of the examples may include “L-paste™,” which is a trade name for a molecular sieve for absorbing water. Some may also contain “DABCO® DC-5160” or “Air Products DC193®”, both are silicone surfactants available from Air Products Urethane Division.