MXPA00006108A - Dimensional stabilizing, cell opening additives for polyurethane flexible foams - Google Patents

Abstract

A method for preparing a polyurethane flexible foam by reacting an organic polyisocyanate with a polyol in the presence of urethane catalyst, water as a blowing agent, optionally a silicone surfactant, and a cell opener characterized in that the cell opener comprises the reaction product of a C1-C20 hydrocarbyl group-containing organic acid anhydride and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, optionally reacted in the presence of a tertiary amine urethane catalyst.

Description

ADDITIVES FOR OPENING CELLS THAT STABILIZE THE DIMENSIONS FOR FLEXIBLE POLYURETHANE FOAMS DESCRIPTION OF THE INVENTION The invention relates to making flexible polyurethane foams using cell openers / dimension stabilizers. Flexible molded polyurethane foams require mechanical crushing to open the foam cells and prevent shrinkage and to improve the dimensional stability of the foam pad. The common mechanical methods for open cells consist mainly of crushing, vacuum interruption or graduated decompression. When unmolding, the mechanical crushing and I the breaking of the cells of the polyurethane foam facilitate that the polyurethane foam is more dimensionally stable. Another method of breaking the cells is the interruption of the vacuum that involves causing a vahío in the finished polyurethane foam causing a rupture of the cells. The full effect of these methods is reduced, to the shrinkage of the foam. Other mechanical attempts have been made for Alean Izar doing it in 4 minutes will dramatically improve dimensional stability. However, this can lead to deformation, tearing or distortion of the polyurethane foam due to a sub-curing. Another method for producing dimensionally stable foam is graduated decompression (TPR). The PRT comprises opening the mold during the curing process to release the internal pressure and then to close it again for a period equal to the duration of the curing time. The sudden release of internally generated pressure causes the cell windows to explode, thus obtaining a foam with an open cell. The effect of TPR can vary by performing the TPR in different stages of the curing process and varying the length of time in which the mold is open before closing it again. This pressure release is carried out only once during the curing time of each polyurethane foam. This process can cause corner burst, surface defects, and dimensional distortions and, if the defect is severe enough, a waste polyurethane foam will result. These discrepancies are considered minor compared to the effect of the TPR and their ability to open the foam. In addition, when demolishing, the foam must also be subjected to mechanical or vacuum crushing since the TPR does not fully provide the necessary energy to fully open the cells in the foam. Mechanical methods usually result in opening inconsistent or incomplete cells and require a flexible molded foam producer to invest in additional machinery. A chemical method for cell openings would be preferable. US 4,929,646 describes the preparation of flexible polyurethane foam using certain high molecular weight, high functionality poly (oxyethylene) compounds such as cell openers and softeners. US 4,751,253 discloses a dimensional stabilizing additive for opening cells for making flexible polyurethane foams whose additive comprises a reaction product of a long chain acid with polyethylene glycols or polypropylene and / or containing free acid to provide the acid value wanted. US 4,701,474 describes the use of acid grafted polyether polyols, such as polyalkylene oxides grafted with acrylic acid, as controllers of the reactivity in the production of the polyurethane foam. US 4,785,027 describes the preparation of polyurethane foams in the presence of mono or diacid polyethers, with the acid functional groups at the end of the polymer chain. Such polyether acids, supposedly retard the range of the initial reaction without increasing the narrowness of the ^^^ ^ & j ^^^^^^^^^^^^^^^^^ foam. US 5,489,618 discloses a polyurethane foam prepared in the presence of a salt of a tertiary amine and a carboxylic acid having hydroxyl functionality as a catalyst. Supposedly, the flexible foams produced are more dimensionally stable and have a decreased tendency to shrink. US 5,179,131 discloses that the addition of mono- or dicarboxylic acids to polyurethane foam formulations made using polyisocyanate polyaddition (PIPA) polymer dispersions results in a reduction in foam shrinkage. The functional groups attached to the acid are either alkyl or alkylene. US 4,211,849 describes a process for making cross-linked foams with open cells, using as the crosslinking agent, a crystalline polyhydroxy material having at least three hydroxy groups. EP 471 260A describes the use of organic acids or their alkali salts for the production of polyurethane foams with open cells. It is established that the incorporation of these materials provides the foam with values forced to crush, notably lower. WO 9506673 describes as catalysts alkali metal and alkali metal salts and alkenyl and alkylsuccinic acids for the production of - ¿zA .. i * ear, * Z. polyurethane and / or polyurea foam. The invention provides a method for preparing flexible polyurethane foams using certain organic esters as cell stabilizers. The method comprises reacting an organic polyisocyanate and a polyol in the presence of a catalyst composition, a blowing agent, optionally a cell-stabilizing silyone surfactant and as an agent for opening cells that stabilize the dimensions, a composition which is the product of the ester reaction of an organic acid anhydride and of 2, 2,4-trimethyl-1,3-pentanediol monoisobutyrate. The use of these ester reaction products in making polyurethane foams provides the following advantages: • Polyurethane foams (flexible molding and flexible bar material) exhibit reduced shrinkage which provides improvement in dimensional stability • A significant Reduction in the force required to crush the recently unmolded flexible foam without adversely affecting the physical properties of the foam.

• The polyurethane cell structure exhibits a more uniform and consistent gradient within the "mass" of the polyurethane part. For purposes of this invention and as understood by many in the art, molded foams i-and-ife-flexible include microcellular foams such as those used in shoe soles and in steering wheels or steering wheels. The cell openers / ester stabilizers used in the preparation of flexible molded foams and flexible bar material are the product of the reaction of an organic acid anhydride and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate ( TP). The product of the ester reaction is used in the polyurethane foam composition at levels of 0.05 to 0.5, preferably about 0.2 parts by weight per 100 parts of polyol (pphpp). The reaction product of the ester can be expressed by the formula I X-Y-Z I wherein X represents hydrogen or preferably a saturated or unsaturated hydrocarbon group of 1 to 20 carbon atoms; Y represents a residue of organic acid anhydride terminally transported in the group X and having a free carboxylic acid or a carboxylate group; and Z represents a TPM residue bound through its Y oxygen atom by means of a functionality! of ester. The group X is preferably a chain of &3tfe "saturated or unsaturated aliphatic hydrocarbon having a molecular weight of about 15 to about 281 and especially about 113 to about 225. Therefore, the X group preferably contains at least 8 carbons and up to about 16 carbons and Examples of such groups are nonyl, decyl, decenyl, dodecyl, dodecenyl, hexadecyl, octadecyl, octadecenyl, and long alkyl chains such as those obtained for example by the polymerization copolymerization of monoolefins containing from 1 to 6 atoms. carbon, for example, ethylene, propylene, butene-1, butene-2 or isobutylene The preferred groups X are those derived from the polymerization of isobutylene or propylene.These polymers can be made by standard methods and are commonly called polymers. of alkyl (en) ilo. Such polymers have a terminal double bond that can be reacted with an anhydride. maleic drido, for example, to form substituted alkanol (suc) yl succinic anhydride derivatives by reaction in the presence of a standard condensation catalyst, for example a halogen such as bromine, to form a compound of formula II * j¡ f ^^ £! The unsubstituted anhydrides of alkyl (en) yl are commercially available and can be used in the form in which they are provided without further purification. Succinic polyisobutylene anhydride is commonly known as PIBSA, the sucproic anhydride (TPSA) of tetrapropenyl (C12), is a liquid product consisting of isomers and the succinic anhydride (DDSA) of docenyl (C12), is a solid material essentially free of isomer ^. When the group Y is a residue of aromatic anhydride, it is preferably derived from a phthalic anhydride and especially from an italic anhydride in which the group X is attached to the anhydride group in the relative position 4. It is preferred, however, that the group AND be a residue of succinic anhydride derivable from a group of succinic anhydride. When the Y is such a group, a divalent group of the formulas -C (O) -CH-CH2-C (0) 0H or HOC (O) -CH-CH2-C (O) -II which binds the group is preferred. X with the group Z. Group Z is the residue of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate. Suitable organic acid anhydrides for making the esters include, for example, maleic anhydride, phthalic anhydride, succinic anhydride and any of the foregoing substituted with a linear hydrocarbyl group <; or branched with a C1-C20, preferably C8-C16, such as an alkyl or alkenyl group. For example, the hydrocarbyl group of the succinic anhydride may be polybuobutenyl, dodecenyl or tetrcyropenilu. Preferred organic anhydrides are dodecenyl succinic anhydride (DDSA) (C12) and tetrapropenyl (C12) succinic anhydride (TPSA). The hydroxyl compound to be reacted with the anhydrides to form the ester cell openers is the 2,4,4-trimetho-, 1,3-pentanediol monoisobutyrate which is available from Eastman Chemical Co. I The anhydride and the TPM they can be reacted in a molar ratio of 1: 3 to 3: 1, preferably in a molar ratio of 1: 1. The opener / stabilizer of the cells can be prepared by adding TPM to the desired anhydride in a reaction vessel at elevated temperatures, for example 60-110 ° C. This mixture is stirred and must be continued until the reaction is complete after several hours.

, J? W ~ > "*«. * - - »-,« gS v The tertiary amines can be used to catalyze the reaction as is well known in the art of organic synthesis.The reaction product can be used as it is or the ester can be isolated for the use by common purification techniques, the cell openers / stabilizers according to the invention are used in the manufacture of polyurethane flexible polyurethane foams and polyether foams in the manner known in the art.When producing polyurethane foams using these cell openers, one or more polyethers or polyether polyols are employed to be reacted with a polyisocyanate and provide the urethane linkage Such polyols have an average of typically 2.0 to 3.5 hydroxyl groups per molecule. The polyurethane composition is polyalkylene ether and polyether polyols, polyalkylene ether polyols include poly mers of poly (alkylene oxide), such as polymers and copolymers of poly (ethylene oxide) and poly (propylene oxide) with terminal hydroxyl groups derived from polyhydric compounds, including diols' and triols; for example, among others, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, pentaerythritol, glycerol, diglycerol, trimethylolpropane and similar low molecular weight polyols. In the practice of this invention, a single high molecular weight polyether polyol can be used. Also, mixtures of di and trifunctional materials and / or materials of different chemical compositions or of different molecular weight can be used. Useful polyester polyols include those produced by the reaction of a dicarboxylic acid with, an excess of a diol, for example, adipic acid with an ethylene glycol or butanediol, or by reacting a lactide with an excess of a diol such as caprolactone with propylene glycol. In addition to the polyether and polyester polyols, the masterbatches, or premixed compositions, often contain a polymer polyol. The polymer polyols are used in the flexible polyurethane foam to increase the foam's resistance to deformation, that is to increase the properties, of the foam's load support. Currently, two different types of polymer polyols are used to achieve improved load support. The first type, described as an infected polyol, consists of a triol in which the vinyl monomers are graft copolymers. Styrene and acrylonitrile are the usual monomers of choice. The second type, a polyurea modified polyol, is a polyol containing a polyurea dispersion formed by the reaction of a diamine and TDI. Since the TDI is used in excess, some of the TDI can react with either either the polyol or the polyurea. This second type of polymer polyol has a variant called PIPA polyol which is activated by the in situ polymerization of TDI and of alkanolamine in the polyol. Depending on the load bearing requirements, the polymer polyols may comprise from 20 to 80% of the polyol portion of the masterbatch. The polyurethane products are prepared using any suitable organic polyisocyanate well known in the art including, for example, hexamethylene diisocyanate, phenylene diisocyanate, toluene diisocyanate (TDI) and 4,4'-diphenyl methane diisocyanate (MDl) . Especially suitable are 2,4- and 2,6-TDI individually or together in their commercially available mixtures. Other suitable isocyanates are mixtures of diisocyanates commercially known as "unpurified MDl", also known as PAPI, which contains about 60% MDl together with other higher isomeric and analogous polyisocyanates. Also suitable are the "prepolymers" of these polyisocyanates comprising a partially pre-reacted mixture of a polyisocyanate and a polyether or a polyester polyol. Suitable urethane catalysts useful for making flexible polyurethane foams are all those well known to the skilled worker and include tertiary amines, such as triethylenediamine, N-methylimidazole, 1,2-dimethylimidazole, N-methylmorpholine, N-methylmorpholine, triethylamine, tributylamine, triethanolamine, dimethylethanolamine and bis (dimethylaminoethyl) ether and organotins such as octoacto stannous, stannous acetate, stannous oleate, stannous laurate, dibutyltin dilaurate and other tin salts. Other typical agents found in polyurethane foam formulations include chain extenders such as ethylene glycol and butanediol; crosslinkers such as diethanolamine, diisopropanolamines, triethanolamine and tripropanolamine; blowing agents such as water, liquid carbon dioxide, CFCs, HCFCs, HFCs, pentane, and the like; especially water or water and HCFC ,, and cell stabilizers such as silicones. A flexible molded polyurethane general foam having a density of 16-48 kg / m3 (1-3 lb / ft3) (e.g. seats for automotive vehicles) containing a cell opener / stabilizer according to the invention will comprise the following components in parts by weight (pbw): Flexible Foam Formulation pbw Polyol 20-100 Polyol Polyol 80-0 Silicon Surfactant 1-2.5 Cell Opener / Stabilizer 0.05-3 Water 1-8 Auxiliary Blowing Agent 0 -4.5 Reticulating Agent 0.5-2 Catalyst Composition 0.1-5 Isocyanate Index 70-115 (preferably TDI) In the present invention the preferable blowing agent for making flexible molded foams is water of 1 to 8 parts by weight per one hundred polyols (pphp), especially from 3 to 6 pphp, optionally with other blowing agents. Other additives may, of course, be employed to impart specific properties to flexible foams. Examples are materials such as flame retardants, colorants, fillers and hardness modifiers. The polyurethane foams of this invention can be formed in accordance with any of the technical processes known in the art, such as, in particular, the "in a single cycle" technique. According to this method, the products made of foam are provided by carrying out the reaction of the polusocyanate and the polyol simultaneously with the operation of foaming. Sometimes it is convenient to add the cell / stabilizer opener to the reaction mixture as a premix with one or more of the blowing agents, the polyol, water and catalyst components. The following materials were used in the examples:? A succinic anhydride (Aldrich Chemicals) DDSA - dodecenylsuccinic anhydride (Aldrich Chemicals) TPSA - tetrapropenylsuccinic anhydride (Heico Chemical) PA - italic anhydride (Aldrich Chemicals) TPM - 2, 2 onoxsobutyrate , 4, t? Met? L-1, 3-pe? ILand? Ol (Eastman Chemical) DabcoO silicone surfactant DC5043 IAII ProducLs and Chemicals, Inc.) Catalyst of Dabco 33-LV © (Air Products and Chemicals, Inc.) Dabco Catalyst © BL-17 (Air Products and Chemicals, Inc.) Polycat © Catalyst (Air Products and Chemicals, Inc.) Examples AD Cell Opener A - One liter reaction flask with three necks it was conditioned with an agitator, an additional funnel, a reflux condenser and a method for providing a layer of nitrogen on the reaction mass. The tetrapropenylsuccinic anhydride (TPSA) (294.8 q; 1.1 aSr Ai M & $ éri ^^ moles) was placed in the flask and heated to 100 ° C under a nitrogen blanket. The 2,2,4 tr? Meth? -1- 1.3 pentandiol monoisobutyrate (216 g, 1.0 mol) was added to the TPSA for 1 hour with continuous agitation. After the addition was completed, the reaction mass was maintained at 100 ° for three hours. The material was cooled to room temperature and removed from the flask. B-cell opener - Using the described procedure to make the Cell Opener A and slightly modified the temperature (70 ° C for 3 hours greater than 100 ° C), the dodecemyl succinic anhydride (DDSA) was reacted (13.3 g; 0.05 moles) with the TPM (10.7 q, 0.10 moles) .i Cell Opener C - Using the method described to make the A Cell Opener, the TDP (216 g, 0.5 moles) was charged to the flask followed by the succinic anhydride ( SA) (50.2 g, 0.5 moles). The addition was carried out with vigorous agitation until the SA was suspended in the TPM. The material was heated to approximately 100 ° C for 1 hour. Stirring and heating was continued for 2 hours after the last dissolved SSA. The product was cooled to room temperature. Cell Opener D - The italic anhydride (? A) (23.6 g, 0.16 moles) was mixed with TPM (34.4 I g, 0.16 moles) and dimethyl-laurilamma (41.9 g, 0.2 moles). The mixture was heated in a microwave oven to melt the PA .J? T? S * atl &al! * MJ * & '~ -' - m "a'a¿ #; -lfT and start the reaction The reaction mass was held at 70 ° C for 4 hours In the following examples the number of cell openers added to the formulations is in ppppp Examples 1-8 AD Cell Openers were evaluated using a standard foam formulation (Formulation A) molded in an electrically heated and ventilated mold of 30.5x30.5x10 cm (12xl2x4 inches).

The polyols were premixed to form a homogeneous mixture and the silicone surfactant and an opener! of cells were added to the premix. A second mixture of diethanolamine, water and the amine catalysts were »M8t? - ís- ^. flita'asa.-. then added. The mold (155 F; 68 C) was sprayed with a fixed solvent releasing agent. The TDI was added to the polyol mixture and mixed for 5 seconds. The spill was continued until 14 seconds after the mixture began. The mold was closed. At the end of 3.5 minutes, the foam pad was removed from the mold, weighed and placed in a Crush Force Apparatus (FTC). This apparatus mimics the Indentation Strength Deflection Test of ASTM D-3574, and provides a numerical value of softness1 or initial hardness of the recently demolded foam. Forty-five seconds after demolling, the first compression cycle was started. (Even though 10 compression cycles were carried out, only the data of the first three are reported in the tables.) The initial value is reports as the FTC value for the foam; the lower the values of the FTC the more open the foam. Additionally, the lower the FTC values, the smaller the dimensional distortions observed in the cured pad. The results of the evaluation | show in the following tables. Table 1 Example 3 Formulation A A A A A No cell opener & r * síí¡Ér¡g ~ * & iá &- JR < 3t??.? Tl ?? - The results of the FTC in Table 1 show the Cell Opener A facilitated a 59% reduction in the force required to compress the foam. That is, an excellent answer from the cell opener. The 5 Cell Opener C which is the product of the reaction of TPM and DDSA, the substituted succinic anhydride dodecenyl, gave a 36% reduction in strength, a substantial reduction in the force needed to compress the foam but not as good as that obtained from the Cell Opener A. 10 The effect of the cell openers of the TPM and TPSA components used to make the A Cell Opener were evaluated for the effects of opening cells with the results also reported. in Table 1. Example 4 shows that the TPM produces a slight reduction of the effect of opening cells of approximately 16%, well below its product of ? & 3 &t? * Aeií * Jßé¿. - ^^^ ¡& ^^ £ ¡gig¿k ^ TPSA reaction, namely the Cell Opener A that produced a 59% reduction. Example 5 shows that the TPSA gave a FTC reduction of 17%, again well below 59% of the cell opener A. Therefore, it can be concluded that the reaction product of the ester is a much more cell opener. efficient than any of its components. The foams were made a couple of days later than the first group using Cell Openers B and D and, as sometimes happens, the control of the foams was more open than in the other occasions. Table 2 presents the results. The Cell Opener B, which is similar to the Cell Opener A in that the succinic anhydride has a 12-carbon substituent, produced a 50% reduction in the FTC value when compared to the control of Example 6. Table 2 The Cell Opener D that was the reaction product of the phthalic anhydride ester and the TPM was also a very potent cell opener that produced a 71% FTC reduction compared to the control Example 6. The invention provides a method for making flexible polyurethane foams blown with water that improves the openings of the cells. afr > - «- > ü «fci • y ^ aai-lj-Sfca-w ^ JJj ^ Siaa

Claims (14)

1. CLAIMS 1. A method for preparing a flexible polyurethane foam comprising reacting an organic polyisocyanate with a polyol in the presence of a urethane catalyst, a blowing agent, optionally a silicone surfactant cell stabilizer and a cell opener, the improvement is characterized in that it comprises both the cell opener and the reaction product of the ester of an organic acid anhydride and of 2,2,4-10-trimethyl-1,3-pentanediol monoisobutyrate. The method according to claim 1, characterized in that the anhydride of the organic acid is maleic anhydride, phthalic anhydride, succinic anhydride or succinic anhydride substituted with a hydrocarbyl group of
2. 15 C1-C20.
3. 3. The method according to claim 1, characterized in that the anhydride of the organic acid is succinic anhydride substituted with a C8-C16 hydrocarbyl group.
4. 4. The method according to the claim

   1, characterized in that the anhydride is phthalic anhydride.
5. 5. The method according to claim 1, characterized in that the anhydride is succinic anhydride.
6. 6. The method according to claim 25, characterized in that the anhydride is dodecenyl anhydride

   succimco.
7. 7. The method according to claim 1, characterized in that the anhydride is tetrapropenylsuccinic anhydride.
8. 8. The method of compliance with the claim

   1, characterized in that the anhydride and the monoisobutyrate of 2,2,4-trimethyl-1,3-panthenol are reacted in the presence of a tertiary amine.
9. 9. The method according to claim 1, characterized in that the blowing agent comprises wick or water and HCFC.
10. 10. The method of compliance with the claim

    2, characterized in that the blowing agent comprises needle or water and HCFC.
11. 11. A method for preparing flexible polyurethane foam comprising reacting an organic polyisocyanate with a polyol in the presence of a urethane catalyst, a blowing agent comprising water or water and HCFC, optionally a silicone surfactant cell stabilizer and a cell opener, the improvement is characterized in that it comprises both the cell opener and the reaction product of a C1-C20 substituted hydrocarbyl succinic acid anhydride and 2, 2,4-trimethyl-1,3-pentanediol monoisobutyrate, optionally reacted in the presence of a tertiary amine urethane catalyst.
12. 12. The method in accordance with the claim

    11, characterized in that the hydrocarbyl group of the succinic acid anhydride is a C8-C16 hydrocarbyl group.
13. 13. A flexible polyurethane foam composition characterized in that it comprises the following components in parts by weight (pbw): Polyol 20-100 Polyol Polyol 80-0 Silicone Surfactant 1-2.5 Cell Opener / Stabilizer 0.05-3 Water I - 8 Auxiliary Blowing Agent 0-4.5 Reticulating Agent 0.5-2 Catalyst Composition 0.1-5 Isocyanate Index 70-115

    The cell / stabilizer opener comprises the product of the reaction of the ester of an organic acid anhydride and of the monoisobutyrate of 2,2,4-trimethyl-1,3-pentandol.
14. 14. The flexible foam composition according to claim 1, characterized in that read cell or stabilizer opener comprises the reaction product of a C1-C20 hydrocarbyl substituted succinic acid anhydride and 2, 2 monoisobutyrate; 4-tr? Met? L-1, 3-pentand? Ol, optionally reacted in the presence of a tertiary amine urethane catalyst.