HK1106257B - Process for preparing polyurethane foams having reduced voc emissions - Google Patents

Description

Method for producing polyurethane foams with reduced VOC emissions

Background

Technical Field

The present invention relates generally to polyurethane foams having reduced Volatile Organic Compound (VOC) emissions. More particularly, the present invention relates to High Resilience (HR) flexible polyurethane foams with reduced VOC emissions using silicone-based surfactants.

Background

Polyurethane foams are typically produced by reacting an organic polyisocyanate with a compound containing two or more active hydrogens in the presence of a blowing agent, a catalyst, a silicone-based surfactant, and other auxiliaries. The active hydrogen-containing compounds are typically polyols, primary and secondary polyamines, and water. During the preparation of polyurethane foams, two main reactions, namely gelling and blowing, are promoted by the catalysts in the reactants. These reactions must be conducted simultaneously during the process and at a competitive equilibrium rate to produce polyurethane foams having the desired physical properties.

Polyurethane foams are used in a very wide range of fields because of their outstanding physical properties. A particularly important market for many types of polyurethane foams is the automotive industry. Polyurethane foams are commonly used in automobiles as headliners, for interior cladding of doors, for chiseling hoods, and for seating systems.

A problem associated with the production of molded foams is the tightness of the foam, which is generally worse in the case of fast curing foam formulations. A high proportion of closed cells results in tight foam when the molded foam part is removed from the mold. If left to cool in this state, the foam part will generally shrink irreversibly. If a foam with high resilience is desired, a higher proportion of open cells is required. Therefore, the cells must be physically opened by crushing the molded part or inserting it into a vacuum chamber. Some chemical and mechanical strategies have been proposed to minimize the number of closed holes upon demolding.

One strategy for providing foams with open cells is to use silicone-based surfactants to stabilize the foam until the product-forming chemical reaction is sufficiently complete that the foam is self-supporting and does not undergo objectionable collapse. In addition, the silicone surfactant should help to open the foam at the end of the foaming process, which is particularly critical when producing HR foams. An example of such a silicon-based surfactant is a short polydimethylsiloxane surfactant having from about two to about seven siloxane units. Such surfactants generally have a relatively low molecular weight and are mobile, and therefore can stabilize the foam without having a closed cell structure. A disadvantage associated with the use of such surfactants is that when polyurethane foams based on such surfactants are used to form parts such as foam seats, headliners, sun visors, etc., unreacted low molecular weight surfactants will evaporate from the polyurethane foam and subsequently deposit on, for example, vehicle windows as an oily film. Subsequently, it scatters light, resulting in poor lighting conditions for the driver of the vehicle.

In addition, in recent years the demands made by automotive manufacturers to their foam suppliers have become significantly more stringent, particularly with respect to emissions regulations. Although the past attention has focused only on the fogging properties of foams (DIN 75201, determination of the material fogging properties of the interior trim of a material car), the content of Volatile Organic Compounds (VOC) is now also determined analytically (for example Volkswagent permanent standard 55031 and Daimler Chrysler PB VWT 709). The Daimler-Chrysler method requires that emissions be measured for individual compounds in addition to the VOC and FOG values being quantitatively measured.

It is therefore desirable to use silicon-based surfactants that provide polyurethane foams with reduced VOC emissions while imparting excellent physical properties without closing (sealing) or substantially closing the cells of the polyurethane foam. It is also desirable to use such silicon-based surfactants to provide high resilience flexible polyurethane foams having reduced VOC emissions.

Disclosure of Invention

It is an object of the present invention to provide polyurethane foams having reduced VOC emissions and excellent physical properties, making them particularly suitable for automotive applications.

It is another object of the present invention to provide semi-flexible and high resilience flexible polyurethane foams having reduced VOC emissions and excellent physical properties, which are particularly useful in automotive applications.

It is another object of the present invention to provide silicon-based surfactants to semi-flexible and flexible polyurethane foams wherein the surfactants are non-volatile such that VOC emissions are significantly reduced while maintaining excellent physical properties, such as tensile strength.

It is another object of the present invention to provide silicone-based surfactants that are extremely effective and provide polyurethane foams that do not crack and have the desired cell structure and size, as well as provide high resilience molded foams with excellent stability.

In accordance with these and other objects of the present invention, there is provided a semi-flexible or flexible polyurethane foam having reduced VOC emissions, wherein the foam is obtained from a polyurethane foam-forming reaction mixture comprising an effective amount of a stabilizer for the foam, wherein the stabilizer comprises a silicone-based surfactant composition comprising a first silicone having from about 2 to about 205 silicone repeat units, wherein the silicone repeat units include at least one isocyanate-reactive group, such as a hydroxyl group, as a terminal substituent. Preferably, such silicones can be represented by the general formula:

M^* _tD_xD^* _yM_u (I)

wherein M is^＊Is R¹ ₂RSiO_0.5(ii) a D is R¹ ₂SiO；D^＊Is R¹RSiO; m is R¹ ₃SiO_0.5；R¹Which may be the same or different, may be an aromatic or saturated aliphatic hydrocarbon group; r is a divalent hydrocarbon moiety, optionally interrupted by methoxy or ethoxy groups, and linked to a hydroxyl end group, t and u are integers from 0 to 2; t + u is 2; x + y is 1-200 and t + y is at least 1. The surfactant composition may have the first siloxane as defined above as its sole component. Alternatively, the first siloxane may be used in combination with at least one silicone oil or siloxane copolymer.

Further in accordance with the present invention, there is provided a process for preparing a semi-flexible or flexible polyurethane foam having reduced VOC emissions comprising the step of reacting a polyisocyanate with an active hydrogen-containing component and an effective amount of a foam stabilizer comprising the above silicone-based surfactant composition in the presence of a blowing agent, water and a suitable catalyst and under conditions sufficient to form a polyurethane foam.

A particularly preferred embodiment of the present invention is a semi-flexible or flexible polyurethane foam having reduced VOC emissions and improved physical properties, wherein the foam is obtained from a polyurethane foam-forming reaction mixture comprising an effective amount of a stabilizer for the foam, the stabilizer comprising a silicone-based surfactant of the general formula:

wherein R is¹May be the same or different and may be an aromatic or saturated aliphatic hydrocarbon radical, R²Which may be the same or different, and are selected from at least one divalent hydrocarbon moiety, optionally separated by methoxy or ethoxy groups, and x is an integer from 2 to about 12.

By utilizing the above-described silicone-based surfactant compositions as foam stabilizers in the production of semi-flexible and flexible polyurethane foams, the resulting polyurethane foams have reduced VOC emissions, making them particularly suitable for use in automotive interiors.

Detailed Description

The present invention relates broadly to a method of producing polyurethane foams having reduced VOC emissions. The present invention is particularly useful for producing semi-flexible and flexible polyurethane foams using one-shot, quasi-prepolymer and prepolymer processes. Accordingly, the present invention provides semi-flexible and flexible polyurethane foams obtained from a polyurethane foam-forming reaction mixture in the presence of a blowing agent, water and a catalyst and optionally a crosslinker, wherein the reaction mixture comprises an isocyanate component, an active hydrogen-containing component and a silicone-based surfactant composition as a stabilizer for the foam.

The production process of the polyurethanes of the present invention generally includes reacting an isocyanate component (e.g., an organic polyisocyanate), and a polyol (e.g., a polyol having a hydroxyl number of from about 15 to about 700, preferably from about 15 to about 70) to form a flexible polyurethane foam. In addition to the materials previously indicated, semi-flexible and flexible polyurethane foam formulations (hereinafter simply referred to as flexible polyurethane foams) generally include: water; optionally an organic low-boiling auxiliary blowing agent or optionally an inert gas; silicone-based surfactant compositions as stabilizers for foams; a catalyst, and optionally a crosslinking agent.

A "one shot" process for producing polyurethane foam is a one-shot process in which all of the ingredients necessary (or desired) to produce a foamed polyurethane product, including the polyisocyanate, organic polyol, water, catalyst, surfactant, optional blowing agent, etc., are simply mixed together, poured onto a moving conveyor or into a mold of suitable construction, and cured. The one-shot process differs from the prepolymer process in that a liquid prepolymer adduct of a polyisocyanate having terminal isocyanate groups and a polyol is first prepared without using any foam-generating components, and then the prepolymer is reacted with water in the presence of a catalyst in a second step to form a solid urethane polymer.

The use of silicone-based surfactant compositions in technologies such as one-shot foaming surprisingly results in the production of High Resilience (HR) flexible polyurethane foams with little to no VOC emissions. It is believed that by utilizing an effective amount of the inventive silicone-based surfactant composition, the silicone-based surfactant composition will react with the polyisocyanate during polyurethane formation such that the surfactant is linked to the resulting polyurethane polymer network, thereby achieving little to no volatility. In this manner, VOC emissions of polyurethane foam are significantly reduced. Another advantage of using a silicone-based surfactant is that the stabilizing action of the surfactant results in the production of a foam that is stable and has more or more open cells. This quality is demonstrated by reduced crushing Force (FTC). Producing a foam with more open or more easily open cells results in a foam that exhibits a lower amount of shrinkage.

The silicone surfactants useful in the present invention are preferably linear, although for example, the presence of branched moieties in the surfactant is also within the scope of formula (I) above. The R groups can be introduced into the molecule from hydrido-functional siloxanes using suitable hydrosilation reactions known to those skilled in the art and as needed at R¹Introducing variants into the base. The hydrido-functional siloxanes may be represented by the general formula:

M^* _tD_xD^* _yM_u (II)

wherein M' is R¹ ₂HSiO_0.5(ii) a D is R¹ ₂SiO；D^＊Is R¹HSiO; m is R¹ ₃SiO_0.5And R¹T, x, y and u have the above meanings. In the above general formulae (I) and (II), R¹Which may be the same or different from each other,and is an aromatic or saturated aliphatic hydrocarbon radical, wherein for the siloxanes of the general formula (II) at least one R is¹The radical has a hydrocarbon group attached to a hydroxyl end group. Specific examples include methyl, ethyl, propyl, octyl, decyl, dodecyl, stearyl, phenyl, methylphenyl, dimethylphenyl, phenethyl, cyclohexyl, methylcyclohexyl, and the like. Preferably R¹The radical being an alkyl radical, most suitably a methyl radical, optionally with a relatively small amount of C₆-C₂₂An alkyl group. Through corresponding C₆-C₂₂The hydrosilation of olefins introduces longer alkyl groups. R is a divalent hydrocarbon moiety, optionally separated by an oxyalkylene group (methoxy or ethoxy), and linked to a hydroxyl end group. The divalent hydrocarbon moiety can be a saturated or unsaturated hydrocarbon moiety of 1 to 20 carbon atoms, including but not limited to a linear aliphatic hydrocarbon moiety, a branched aliphatic hydrocarbon moiety, an alicyclic hydrocarbon moiety, or an aromatic hydrocarbon moiety. In addition, R can be, for example, a linear or branched alkylene of 1 to about 20 carbon atoms and preferably 1 to about 10 carbon atoms, a cycloalkylene of 4 to about 10 carbon atoms, an arylene, an alkylarylene, or an alkylarylene of about 6 to about 20 carbon atoms.

Particularly preferred silicone-based surfactant compositions for use herein as stabilizers have the general formula:

wherein R is¹Which may be identical or different and may be an aromatic or saturated aliphatic hydrocarbon radical as defined above, R²Which may be the same or different and are selected from at least one divalent hydrocarbon moiety, optionally interrupted by methoxy or ethoxy groups, as described above, and x is from 2 to about 12, preferably from 4 to 8.

The above silicone-based surfactant may be used by itself, or dissolved in a solvent such as glycol, soybean oil, or the like. For HR foams, the reaction mixture typically comprises from about 0.1 to about 3phpp siloxane-based surfactant, preferably from about 0.2 to about 1.5 phpp. The amount can be adjusted to obtain the desired cell structure and foam stability of the foam.

The polyisocyanate used in the polyurethane foam forming process of the present invention is an organic polyisocyanate compound containing at least two isocyanate groups and is generally any known aromatic or aliphatic polyisocyanate. Suitable organic polyisocyanates include, for example, hydrocarbyl diisocyanates, (e.g., alkylene diisocyanates and arylene diisocyanates), such as methylene diphenyl diisocyanate (MDI) and 2, 4-and 2, 6-Toluene Diisocyanate (TDI), as well as known triisocyanates and polymethylene polyphenylene polyisocyanates, which are also known as polymeric or crude MDI. For semi-flexible and flexible foams, the preferred isocyanates are typically, for example, mixtures of about 80% and about 20% by weight of 2, 4-toluene diisocyanate and 2, 6-Toluene Diisocyanate (TDI), respectively, and about 65% and about 35%, respectively; a mixture of TDI and polymeric MDI, preferably in a weight ratio of about 80% TDI and about 20% crude polymeric MDI to about 5% TDI and about 95% crude polymeric MDI; and all MDI type polyisocyanates.

The amount of polyisocyanate included in the foam formulation used relative to the amount of other materials in the formulation is described by the term "isocyanate index". "isocyanate index" means the actual amount of polyisocyanate used divided by the theoretical stoichiometry of the polyisocyanate required to react with all of the active hydrogens in the reaction mixture multiplied by one hundred (100) (see, e.g., Oertel, polyurethane handbook, Hanser Publishers, New York, NY. (1985)). The isocyanate index in the reaction mixture used in the process of the present invention is generally from 60 to 140. More typically, the isocyanate index is: for flexible TDI foams, typically 85 to 120; for molded TDI foams, typically 90 to 105; for molded MDI foams, most typically 70 to 90.

The active hydrogen-containing compound used with the above-described polyisocyanate in forming the polyurethane foam of the present invention may be any organic compound having at least two hydroxyl groups, such as a polyol. The polyols useful in the process of the present invention for producing polyurethane foams, particularly via the one-shot foaming process, are any of the types currently used in the art for preparing flexible slabstock foams, flexible molded foams and semi-flexible foams. Polyols (e.g., polyether polyols and polyester polyols) typically have hydroxyl numbers of from about 15 to about 700. The hydroxyl number is preferably from about 100 to about 300 for semi-flexible foams and from about 20 to about 60 for flexible foams. For flexible foams, it is preferred that the functionality of the polyol (i.e., the average number of hydroxyl groups per molecule of polyol) be from about 2 to about 4, most preferably from about 2.3 to about 3.5.

The polyols which may be used herein, alone or in mixtures, may be of any of the following non-limiting types:

a) polyether polyols derived from the reaction of a polyhydroxyalkane and one or more alkylene oxides such as ethylene oxide, propylene oxide, and the like;

b) polyether polyols derived from the reaction of high functionality alcohols, sugar alcohols, sugars and/or high functionality amines, if desired mixtures with low functionality alcohols and/or amines, with alkylene oxides such as ethylene oxide, propylene oxide and the like;

c) polyether polyols derived from the reaction of phosphoric and polyphosphoric acids with alkylene oxides such as ethylene oxide, propylene oxide, and the like;

d) polyether polyols derived from the reaction of a polyaromatic alcohol with an alkylene oxide such as ethylene oxide, propylene oxide, and the like;

e) polyether polyols derived from the reaction of ammonia and/or amines with alkylene oxides such as ethylene oxide, propylene oxide, and the like;

f) polyester polyols derived from the reaction of a polyfunctional initiator such as a diol with a hydroxycarboxylic acid or lactone thereof, such as hydroxycaproic acid or e-caprolactone;

g) polyoxamic polyol esters derived from the direct reaction of an oxalate ester and a diamine such as hydrazine, ethylenediamine, and the like in a polyether polyol;

h) polyurea polyols derived from the reaction of diisocyanates and diamines such as hydrazine, ethylenediamine, and the like directly in polyether polyols.

For flexible foams, the preferred type of alkylene oxide adduct of a polyhydroxyalkane is an ethylene oxide and propylene oxide adduct of an aliphatic trihydroxyalkane.

In addition to standard polyols, graft or polymer polyols are widely used to produce flexible foams, which is a preferred class of polyols for use in forming the polyurethane foams of the present invention. The polymer polyol is a polyol comprising a stable dispersion of a polymer, for example, dispersed in the above polyols (a) to (e), more preferably a polyol of type (a). Other polymer polyols that may be used in the process of the present invention are polyurea polyols and polyoxometalate polyols.

Water is commonly used as a reactive blowing agent in flexible foams. In producing flexible slabstock foams, water may typically be used at a concentration of, for example, about 1.5 to about 6.5 parts per hundred parts polyol (phpp), more typically about 2.5 to about 5.5 phpp. For TDI molded foams, the water content is typically, for example, from about 3 to about 4.5 phpp. For MDI molded foams, the water content is more typically, for example, from about 2.5 to about 5 phpp. However, as will be readily appreciated by those skilled in the art, the water content is typically set according to the desired foam density. Suitable blowing agent contents are known to the skilled worker. For example, for high density semi-flexible polyurethane foams, the water content may be as low as about 0.2 phpp. Physical blowing agents, such as those based on volatile hydrocarbons or halogenated hydrocarbons and other non-reactive gases, may also be used to produce the polyurethane foams of the present invention. In the production of flexible slabstock foam, water is the primary blowing agent; however, other blowing agents may be used as auxiliary blowing agents. For flexible slabstock foams, the preferred auxiliary blowing agents are carbon dioxide and methylene chloride (methylene dichloride). Other blowing agents such as fluorocarbons, for example chlorofluorocarbons (CFCs), dichlorodifluoromethane, and trichloromonofluoromethane (CFC-11), or non-fluorinated organic blowing agents such as pentane and acetone may also be used.

Flexible molded foams generally do not use inert auxiliary blowing agents, in any case less auxiliary blowing agents are introduced than slabstock foams. However, there is a great interest in using carbon dioxide in certain molding techniques. MDI molded foams in Asia and some developing countries use methylene chloride, CFC-11 and other blowing agents. The amount of blowing agent varies depending on the desired foam density and foam hardness, as known to those skilled in the art. When used, the amount of hydrocarbon blowing agent can be, for example, from trace amounts up to about 50 parts per hundred parts polyol (phpp), with carbon dioxide, for example, from about 1 to about 10%.

Catalysts that may be used to produce the polyurethane include, but are not limited to, delayed action catalysts, non-reactive (fugitive) and reactive tertiary amines, and the like. Reactive amine catalysts are compounds that contain one or more active hydrogens and, therefore, can react with isocyanates and become chemically incorporated into the polyurethane polymer matrix. For the production of flexible slabstock and molded foams, the preferred amine catalysts are bis (N, N-dimethylaminoethyl) ether and 1, 4-diazabicyclo [2.2.2] octane. Metal salt catalysts, which are commonly used in polyurethane foam formulations, may also be used. For flexible slabstock foams, it is generally preferred that the metal salt be stannous octoate. The metal salt catalysts are typically used in minor amounts in polyurethane formulations, for example from about 0.001phpp to about 0.5 phpp.

A variety of additives may also be used to prepare the foam, which are used to provide different properties. A cross-linker or chain extender having at least two hydrogen atoms, capable of reacting with isocyanates, such as compounds having hydroxyl and/or amino and/or carboxyl groups, may be added to the reaction mixture. Fillers such as clay, calcium sulfate, barium sulfate, ammonium phosphate, and the like may be added to reduce cost and impart specific physical properties. Dyes may be added for dyeing and glass or synthetic fibers may be added for strength. In addition, plasticizers, deodorants, foam stabilizers, pigments, anti-aging and weathering stabilizers, flame retardants, mold inhibitors and bacteriostats may be added.

Crosslinkers that can be used to produce polyurethane foams are typically small molecules; typically less than 350 molecular weight, which contains active hydrogens that react with isocyanate. The functionality of the crosslinking agent is greater than 3 and preferably from 3 to 5. The amount of cross-linking agent used may be from about 0.1phpp to about 20phpp, adjusted to achieve the desired foam stability or foam hardness. Examples of the crosslinking agent include glycerol, diethanolamine, triethanolamine and tetrahydroxyethyl ethylenediamine.

The chain extender is preferably selected from the group consisting of 1, 4-butanediol, 1, 6-hexanediol, 1, 8-octanediol, 1, 9-nonanediol, 1, 10-decanediol, 1, 4-cyclohexanedimethanol, p-xylene glycol, 1, 4-bis (2-hydroxyethoxy) benzene and 1, 12-dodecanediol, particularly preferably 1, 4-butanediol.

As will be appreciated by those skilled in the art, the temperature used to produce the polyurethane will vary depending on the type of foam and the particular method of production. Flexible slabstock foams are typically produced by mixing the reactants at ambient temperatures of from about 20 ℃ to about 40 ℃. The conveyor belt that produces and cures the foam is essentially at ambient temperature, which can vary significantly depending on the geographic region in which the foam is produced and the time of year. Flexible molded foams are typically produced by mixing the reactants at a temperature of from about 20 ℃ to about 30 ℃. The mixed raw materials are generally fed into the mold by pouring. Preferably, the mold is heated to a temperature of from about 20 ℃ to about 70 ℃, more typically from about 40 ℃ to about 65 ℃. Preferred processes for producing the flexible slabstock and molded foams of the present invention are the "one shot" process or the quasi prepolymer process, wherein the raw materials are mixed and reacted in one step.

The basic procedure for mixing the reactants and preparing the laboratory foam pad for evaluating foam performance is as follows:

1. the formulation ingredients were weighed and added to a suitable mixing container (cardboard cup) in the order of preparation.

2. A pre-mix of water, catalyst and optionally crosslinker is prepared in a suitable vessel.

3. The polyol was thoroughly mixed with the optional aperturing agent (for MDI formulations), premix and silicone surfactant in a cardboard cup using a stand-up drill at 2000 rpm.

4. The isocyanate is added and mixed with the other reactant components.

5. The reaction mixture was poured into a 30X 10cm aluminum mold. The mold temperature was controlled at 60 ℃ (TDI) or 50 ℃ (MDI) using a hot water circulation controlled oven. The mold lid has vent holes at four corners.

Table III provides data on the subsurface cell structure of the foam to compare different silicone-based surfactants used in the following examples. Table V provides a comparison between the silicone-based surfactants of the present invention and silicone surfactants that are commercially known for use in MDI foams.

Table I gives the meanings of the terms and abbreviations used in the following examples:

TABLE I

Meaning of terms or abbreviations

Reactive triols having polyether polyol OH 28 with 28 OH numbers

Blend of TDI 80/20 toluene diisocyanate and isomers thereof

MDI methylene diphenyl diisocyanate and blends thereof

A33% solution of Niax Catalyst A-33 TEDA in Diphenylguanidine (DPG) (available from Crompton)

Corporation, Middlebury, CT)

A blend of Niax Catalyst C-174 tertiary amine catalysts (available from Crompton Corporation,

middlebury, CT acquisition)

Niax Catalyst UAX-1172 zero emission amine Catalyst (available from Crompton Corporation,

middlebury, CT acquisition)

Niax Catalyst UAX-1188 zero emission amine Catalyst (available from Crompton Corporation,

middlebury, CT acquisition)

C9 Niax Silicone-L-3001HR MDI Silicone oil with the general formula of MD_xLow molecular weight of M

Polydimethylsiloxane oils, where x is from 2 to 16, and no hydroxyl end groups (may be)

Available from Crompton Corporation, Middlebury, CT)

C10 Niax Silicone-L-3002HR MDI Silicone oil with the general formula of MD_xLow molecular weight of M

Polydimethylsiloxane oils, where x is from 2 to 16, and no hydroxyl end groups (may be)

Available from Crompton Corporation, Middlebury, CT)

C11 Niax Silicone-L-3003HR MDI and TDI/MDI Silicone oil with the general formula of MD_xM

Wherein x is 2 to 16 and is free of hydroxyl groups

Terminal radical (available from Crompton Corporation, Middlebury, CT)

FTC crushing force

kg kilogram

m meter

% by weight

phpp parts per hundred parts by weight of polyol

N newtons

While the scope of the invention is defined by the appended claims, the following non-limiting examples illustrate certain aspects of the invention and, more particularly, describe methods for evaluation. The examples are provided for illustrative purposes and are not to be construed as limiting the invention.

In the following examples, the materials used and the amounts thereof in all reactions are listed in table II. The silicone based surfactants listed in table III and their amounts were added to the formulations of table II. The formulations provided later in tables II and III are evaluation formulations commonly used to produce MDI/TDI High Resilience (HR) molded foams.

Examples 1 to 13

Table II set forth below shows the formulations used to prepare the foams of examples 1-13. Table III shows different silicone-based surfactants that were added with the ingredients of the formula of Table II to form polyurethane foams. The outer layer of the cut foam pad was about 1 cm thick. This allows the outer layer to be seen through and the cell structure of the bulk foam to be observed, and thus the subsurface structure thereof. The table demonstrates that the new siloxane structures can produce sufficient outer layer structure at low usage levels (thereby helping to achieve lower VOC emissions).

TABLE II

Formulation Phpp

Polyether polyol (OH 28) 100

Water 3.2

Niax Catalyst A-33 0.3

Niax Catalyst C-174 0.3

Siloxane surfactant variables

TDI 80/20 20.6

MDI 20.6

Density kg/m³ 47

Comparative examples A to C and examples 14 to 16

Table IV set forth below shows the formulation components used to prepare comparative examples A-C and examples 14-16 foams. Table V shows different silicone-based surfactants that were added with the formulation ingredients of Table IV to provide a polyurethane foam.

TABLE IV

Formulation Phpp

Polyether polyol (OH 28) 100

Cell opener 1.5

Water (total) 0.6

Niax Catalyst UAX-1172 1.0

Niax Catalyst UAX-1188 0.5

Siloxane surfactant variables

MDI (MDI index) 80

TABLE V

Comparative example surface phpp Density perforation Structure FTC (N)

EXAMPLES/EXAMPLES active Agents kg/m³)

A C90.551.3 Medium to Fine 350

14 C70.351.4 medium to fine 420

B C100.551.0 fine 706

15 C70.550.4 Fine 698

C C110.551.7 very fine 1105

16 C70.851.7 very fine 1101

Examples 14-16 show the use of the same silicone-based surfactant at different levels in a typical MDI formulation relative to the commercial Crompton silicone surfactant of comparative examples A-C. The data show that the siloxane-based surfactants of the present invention give similar stabilizing effect (measured by FTC) compared to siloxane-based surfactants outside the scope of the present invention, i.e., surfactants C9, C10, and C11. It is also important to note that the same cell structure, i.e., the foam properties of examples 14-16, correspond to a commercial product.

Volatile Organic Compounds (VOC)

Table VI shows the VOC emissions results tested according to the Mercedes Method (DaimlerChrylser AG Method PVWL 709). The data show that when siloxane-based surfactants within the scope of the present invention (i.e., surfactants C6 and C7) are used, substantially reduced emissions can be obtained compared to commercial siloxane surfactants.

TABLE VI

Formulation phpp phpp phpp

Polyether polyol (OH 28) 100100100

Cell opener 1.51.51.5

Water (Total) 0.60.60.6

Niax Catalyst UAX-1172 1 1 1

Niax Catalyst UAX-1188 0.5 0.5 0.5

Niax Silicone L-3001(C9) 0.8

C7 0.8

C6 0.8

MDI (MDI index) 808182

VOC 180134 in ppm

Although the present invention has been described in a preferred form with a certain degree of particularity, it is capable of numerous alterations and modifications as will become apparent to those skilled in the art upon reading the foregoing description. It is therefore to be understood that the invention may be practiced otherwise than as specifically described herein without departing from the spirit and scope of the present invention.

Claims (12)

1. A process for preparing a polyurethane foam having reduced volatile organic compound emissions comprising the step of reacting a polyisocyanate with an active hydrogen-containing component in the presence of a blowing agent and in the presence of a silicone-based surfactant composition as a stabilizer for foam in an amount of from 0.1 to 3 parts per hundred parts by weight polyol in the presence of a blowing agent and under conditions sufficient to form a polyurethane foam, the silicone-based surfactant composition comprising a first siloxane having from 3 to 202 siloxane repeating units, the first siloxane having the general formula:

M^* _tD_xD^* _yM_u

wherein

M^*Is R¹ ₂RSiO_0.5(ii) a D is R¹ ₂SiO；D^*Is R¹RSiO; m is R¹ ₃SiO_0.5；

R¹Is an aromatic or saturated aliphatic hydrocarbon group;

r is a divalent hydrocarbon moiety having a hydroxyl end group,

t and u are integers from 0 to 2; t + u is 2;

x+y＝1-200，

t + y is at least 1.

2. The method of claim 1, wherein R¹Is an alkyl group.

3. The method of any of claims 1-2, wherein the silicone-based surfactant composition further comprises a silicone oil.

4. The method of any of claims 1-2, wherein the first siloxane of the siloxane-based surfactant composition comprises 3 to 12 siloxane repeating units.

5. The method of any of claims 1-2, wherein the blowing agent is water, and wherein the reacting step is conducted in the presence of one or more polyurethane foam additives, wherein the polyurethane foam additives are selected from the group consisting of catalysts, crosslinkers, chain extenders and mixtures thereof.

6. A polyurethane foam obtained from a polyurethane foam-forming reaction mixture comprising a polyether polyol having at least 2 hydroxyl groups and from 0.1 to 3 parts per hundred parts by weight of polyol of a silicone-based surfactant composition as a stabilizer for foam, the silicone-based surfactant composition comprising a first siloxane having from 3 to 202 siloxane repeating units, the first siloxane having the general formula:

M^* _tD_xD^* _yM_u

wherein M is^*Is R¹ ₂RSiO_0.5(ii) a D is R¹ ₂SiO；D^*Is R¹RSiO; m is R¹ ₃SiO_0.5；R¹Is an aromatic or saturated aliphatic hydrocarbon group; r is a divalent hydrocarbon moiety having a hydroxyl end group, t and u are integers from 0 to 2; t + u is 2; x + y is 1-200 and t + y is at least 1.

7. The polyurethane foam of claim 6, wherein the polyurethane foam-forming reaction mixture further comprises a polyisocyanate and a blowing agent.

8. The polyurethane foam of any of claims 6-7, wherein R¹Is an alkyl group.

9. The polyurethane foam of any of claims 6-7, wherein the silicone-based surfactant composition further comprises a silicone oil.

10. The polyurethane foam of any of claims 6-7, wherein the first siloxane of the siloxane-based surfactant composition comprises from 3 to 12 siloxane repeating units.

11. The polyurethane foam of claim 7, wherein the blowing agent is water, and wherein the polyurethane foam-forming reaction mixture further comprises one or more polyurethane foam additives selected from the group consisting of catalysts, crosslinkers, chain extenders and mixtures thereof.

12. An article comprising the polyurethane foam of any of claims 6-11.