HK1068359B - Process for the production of polyol blends - Google Patents

Description

Process for producing polyol blends

Background

The present invention relates to a process for the in situ production of a blend of polyether polyols, in particular to a process for the in situ production of a blend of one or more polyether monols and one or more polyether polyols, and to an in situ formed blend of one or more polyether monols and one or more polyether polyols. The invention also relates to a process for producing viscoelastic foams from these blends, and to the resulting viscoelastic foams. The process of the present invention requires a Double Metal Cyanide (DMC) catalyst. The process uniquely uses a monol as the initial starting material for epoxidation and then produces a blend of a high equivalent weight polyether monol and a very low equivalent weight polyether polyol in a single reactor batch by continuously feeding the polyfunctional starting material and continuously adding the epoxide at the later stage of the polymerization. Blends of these in situ formed polyether monols and polyether polyols are suitable for producing viscoelastic polyurethane foams.

Double Metal Cyanide (DMC) complexes are highly effective catalysts for the preparation of polyether polyols by epoxide polymerization. Recent improvements have resulted in DMC catalysts having particular activity. See, for example, U.S. patent No. 5,470,813.

Although IDMC catalysts have been known since the sixties of the twentieth century, the commercialization of polyols produced from these catalysts has been a recent event, and most commercial polyether polyols are still produced using potassium hydroxide. One reason for the delayed commercialization of DMC polyols is that conventional polyol starters, such as water, propylene glycol, glycerol, trimethylolpropane, and the like, have very low, if any, activity for initiating DMC-catalyzed epoxide polymerizations, especially in typical batch polyol production processes. Typically, the polyol starter and DMC catalyst are charged to a reactor and heated with a small amount of epoxide to activate the catalyst, and the remaining epoxide is then continuously added to the reactor to complete the polymerization.

In a typical batch process for making polyols using KOH or DMC catalysts, all of the polyol starter is initially charged to the reactor. When KOH is used as a catalyst, it is well known to those skilled in the art that continuous addition of a starting material (typically a low molecular weight polyol such as glycerol or propylene glycol) with an epoxide will produce a polyol having a broader molecular weight distribution than the product produced by initially adding all of the starting material. This is true because the rate of alkoxylation using KOH is essentially independent of polyol molecular weight. If low molecular weight substances are introduced continuously, the molecular weight distribution of the polyalkoxylated product will be broadened.

It has been recognized by those skilled in the art that continuous addition of starter in DMC-catalyzed polyol synthesis will also produce polyols having broader molecular weight distributions. Thus, DMC polyol synthesis technology teaches almost exclusively the initial charging of all starter to the reactor, and the continuous addition of epoxide during polymerization.

One exception is U.S. Pat. No. 3,404,109. This reference discloses a small scale process for making polyether diols using a DMC catalyst and water as starting materials. The process describes adding the DMC catalyst, all of the epoxide to be used and water to a beverage bottle and then heating the capped bottle and contents to polymerize the epoxide. U.S. Pat. No. 3,404,109 further discloses that "when large amounts of water are used to produce low molecular weight telomers, it is preferred to add water gradually, since large amounts of water reduce the rate of the telomerization reaction". (see column 7) incremental addition of starting material (i.e., water) was used to obtain a "practical" reaction rate. Thus, the' 109 patent initially charges all of the epoxide to the reactor, but gradually adds the starting materials.

Interestingly, U.S. Pat. No. 3,404,109 also discloses that incremental addition of water "can also be used to produce telomers having a broader molecular weight distribution than all the water is added at the beginning of the reaction". In other words, the expected results for the DMC-catalyzed process are the same as those obtained by the KOH-catalyzed process: that is, continuous or incremental addition of starting materials results in polyols having a broad molecular weight distribution. Thus, one of ordinary skill in the art, after reading the' 109 patent, would believe that incremental addition of starter in a DMC-catalyzed epoxide polymerization would result in a polyol having a broader molecular weight distribution than the product obtained if all of the starter was initially charged.

Us patent 5,114,619 discloses a process for making polyether polyols which comprises continuously feeding water and an epoxide to a reaction mixture containing a barium or strontium oxide or hydroxide catalyst. DMC-catalyzed processes are not disclosed. The process of the 619 patent produces polyols having reduced unsaturation. The effect of continuous addition of water in the presence of a barium or strontium catalyst on the molecular weight distribution of the polyol is not discussed. The' 619 patent further teaches that the continuous addition of low molecular weight diols, triols and polyoxyalkylene glycols, unlike water, does not reduce the unsaturation of the polyol. Furthermore, no improvement was obtained by using KOH instead of barium or strontium catalyst.

One of the consequences of initially charging all of the starting materials, as is the case in typical batch polyether polyol synthesis, is that the reactor must generally be used inefficiently. For example, to produce 4000 molecular weight polyoxypropylene diol (4K diol) from 2000 molecular weight polyoxypropylene diol (2K diol) "starting material", the reactor was almost half charged at the beginning of the reaction; to produce 50 gallons of product, we needed to start with 25 gallons of 2K diol starting material. A valuable process would overcome such "built ratio" limitations and would make efficient use of the reactor regardless of the molecular weight of the starting materials or the desired product. For example, it would be valuable if 5 gallons of 2K diol starting material could be charged in a 50 gallon reactor and still produce 50 gallons of 4K diol product.

In addition to the difficulties of DMC-catalyzed processes, the industrial acceptance of DMC-catalyzed polyols has also been hindered by the variability of polyol handling and properties, especially in the production of flexible and molded polyurethane foams. DMC-catalyzed polyols generally cannot be used "directly" in formulations designed for KOH-catalyzed polyols because of the different processing properties of the polyols. DMC-catalyzed polyols generally lead to too high or too low a foam stability. Batch-to-batch variability of polyols makes foam formulation unpredictable. The reasons for this unpredictability in foam formulations using DMC-catalyzed polyols are not well understood and consistent results are not obtained.

U.S. Pat. No. 5,777,177 describes an improved process for making DMC-catalyzed polyols. This process eliminates the need for separate synthesis of polyol starting materials by means of KOH catalysis and enables the use of simple starting materials such as water, propylene glycol and glycerol. The process also eliminates the problem of reactor fouling due to polyol gels, allows efficient use of the reactor, and overcomes the limitations of feed rates.

While U.S. Pat. No. 5,777,177 discloses the use of an initial starting material and the continuous addition of a second starting material to produce polyether polyols having a narrow molecular weight distribution, it does not disclose and/or suggest that this technique can be used to produce in-situ formed polyol blends having significantly different and narrower molecular weights in a single batch reactor. More specifically, it does not disclose the in situ production of high molecular weight polyether monols and very low molecular weight polyether polyols as disclosed and claimed in the present specification.

U.S. Pat. No. 5,689,012 discloses a continuous polyol production process that utilizes continuous feeding of one or more starting materials. However, as in U.S. Pat. No. 5,777,177, the intent of U.S. Pat. No. 5,689,012 is to produce polyols having narrower molecular weight distributions. The reference also does not disclose and/or suggest a process for the in situ production of blends of polyols (and especially polyether monols and polyether polyols) having substantially different molecular weights, wherein each component has a narrow molecular weight distribution. It is not clear from the disclosure of U.S. Pat. No. 5,689,012 that this continuous polyol process can be used to produce high molecular weight polyether monols and very low molecular weight polyether polyols as described herein in situ.

Co-pending U.S. application serial No. 09/495,192, commonly assigned at 31/1/2000, discloses a process for producing viscoelastic, slow-recovery polyurethane foams by reacting an isocyanate component with an isocyanate-reactive component at an isocyanate index of at least 90, wherein the isocyanate-reactive component comprises a high equivalent weight monohydric alcohol and a low equivalent weight polyol. According to the disclosure of this application, the monols and polyols used as isocyanate-reactive components are produced in separate reactions and no single batch process is disclosed in which the high molecular weight polyether monols and the low molecular weight polyether polyols are produced in situ.

U.S. patent 4,950,695 discloses the use of monofunctional alcohols or polyethers to soften flexible polyurethane foams. The formulation also contains a triol having a molecular weight of 2000 to 6500. No resilience values for the foams are reported. Thus, one of ordinary skill in the art would consider the foam to lack viscoelastic properties.

European patent application No. 0913414 discloses the preparation of viscoelastic polyurethane foams that may include polyether monols. Monohydric alcohols having a molecular weight of less than 1500 are used together with polyhydric alcohols having a molecular weight of greater than 1800. All examples show low-index (i.e. less than 90) foams.

Dispersion polyols suitable for the production of ultra soft (hypersoft) polyurethane foams are disclosed in U.S. patent 6,063,309. These polyoxyalkylene dispersion polyols comprise stable liquid-liquid dispersions of two different polyoxyalkylene polyols. The first polyol has an inner block of relatively high polyoxypropylene content and an outer block of high polyoxyethylene content; and the second polyol consists essentially of high ethylene oxide-containing blocks. These compositions form fine, liquid-liquid dispersions that resist separation and delamination, and are highly suitable for the preparation of ultra-soft polyurethane foams.

The present invention relates to a unique process wherein DMC-catalyzed epoxidation is used to simultaneously (in situ) produce a blend of a high equivalent weight monofunctional polyether, i.e., polyether monol, and a low molecular weight polyfunctional polyether, i.e., polyether polyol, in a single reactor batch. The in situ process eliminates the need to produce, store and blend separate polyethers, thus reducing the requirements for multiple tanks and increasing production efficiency. Surprisingly, the blends of polyether monols and polyether polyols produced in situ by this process, when used to produce viscoelastic foams, result in comparable or superior performance compared to blends made from polyether polyols produced separately (i.e., polyether monols and polyether polyols).

Disclosure of Invention

The present invention is a process for producing polyether polyol blends in situ, and more particularly for producing blends of one or more polyether monols and one or more polyether polyols in situ. The invention also relates to blends of polyether monols and polyether polyols polymerized in situ; to a process for producing a viscoelastic foam by reacting an isocyanate component with an isocyanate-reactive component, wherein a portion of the isocyanate-reactive component comprises a blend of said in situ polymerized polyether monol and a polyether polyol; and to the resulting viscoelastic foam.

The process comprises initially charging a monofunctional starter (S) over a Double Metal Cyanide (DMC) catalyst_j) And continuously added polyfunctional starting material (S)_c) The blend of polyether monol and polyether polyol is produced in situ by polymerizing one or more epoxides in the presence of a catalyst. Although conventional processes for making DMC-catalyzed polyols and polyol blends charge all of the starter used to the reactor at the beginning of the polymerization, the process is not limited to the use of a single catalyst, but rather to the use of a single catalyst, such as a single catalyst, and may be used in combination with a single catalyst, such as a single catalyst, or a combination of two or moreThe process of the present invention only begins with a monofunctional starting material (S)_i) Charging with DMC catalyst, feeding certain epoxides, and reacting the S_iAnd said epoxide, and uniquely reacting the epoxide with one or more multifunctional starter compounds (S)_c) Both are continuously added to the reaction mixture during the polymerization.

The process of the present invention has surprising and valuable advantages. First, the process provides an efficient way to produce a high equivalent weight monofunctional polyether component in a reactor. It has been found that DMC catalysts readily initiate epoxidation of monofunctional starters, and that the high activity of the catalysts facilitates polymerization to high equivalent weights, which is desirable for the intended application. More traditional methods involving strong base catalysis require time-consuming steps of dissolving the catalyst in the monohydric alcohol, removing excess water, and the use of such catalysts requires long reaction times associated with slow epoxidation rates. This process is particularly time consuming for the production of monohydric alcohols having equivalent weights greater than about 1,800 due to the low reaction rates in base catalyzed processes and the formation of undesirable low molecular weight monofunctional starting materials due to the isomerization of propylene oxide to allyl alcohol.

Second, the continuous addition of the polyfunctional starting material to the preformed polyether monol provides a means to generate a low equivalent weight polyfunctional polyether in situ in a high equivalent weight monol. The above process is facilitated by the unique ability of the DMC catalyst to promote the preferential addition of epoxide monomers to the lowest equivalent weight polyol chain. Surprisingly, by carefully controlling the addition rates of the starter and epoxide, low molecular weight polyether polyols having a narrow molecular weight distribution can be produced in higher equivalent weight monools.

Third, the polymerization can be carried out in a single batch process that is staged sequentially, which does not require significantly longer cycle times than standard single product reactions such as in U.S. Pat. nos. 5,689,012, 5,777,177, and 5,919,988. The use of an initial starting material and a continuously fed second starting material allows the feed ratio to be adjusted to the reactor used, thereby maximizing the utilization and production capacity of the reactor.

Fourth, the in situ production of polyether monols and polyether polyols in a single reactor batch process provides significant efficiency and cost advantages over producing the polyether monols and polyether polyols separately and then blending them together. No storage tank for each of the two components and a third storage tank for the blend are required, which requires only a tank for the blend. In addition, inventory is also substantially reduced because it is not necessary to maintain intermediate polyether monols and polyether polyols for blending. In addition, the time and expense of blending the product is eliminated.

Fifth, by controlling the epoxide feed composition at different stages of the reaction, the composition of the polyether monol and the polyether polyol can be varied in an almost independent manner, even though they are produced in situ in a single reactor. For example, propylene oxide may be fed during the polymerization of polyether monols to produce a less reactive component, followed by a mixture of ethylene oxide and propylene oxide during the continuous addition of higher functionality starting materials to produce a more reactive component. Because the epoxide is preferentially added to the lower equivalent weight polyether polyol, the polyether monol will remain predominantly poly (propylene oxide), whereas the polyether polyol may have a higher poly (ethylene oxide) content.

Finally, it has also been unexpectedly found that these in situ produced blends provide comparable or superior performance in the production of viscoelastic foams as compared to blends made from polyether monols and polyether polyols produced separately.

Drawings

FIGS. 1-6 are Gel Permeation Chromatography (GPC) analysis results of blends of polyether monols and polyether polyols produced in situ by the process of the present invention. These six (6) GPC diagrams correspond to, and are more fully described in, examples 1-6, respectively, of the present application.

Detailed Description

The process of the present invention comprises a process for the in situ production of a polyether polyol blend, in particular a blend of one or more polyether monols and one or more polyether polyols, which process comprises: in a Double Metal Cyanide (DMC) catalyst, an initially charged monofunctional starter (S)_i) And a continuously added polyfunctional starting material (S)_c) In the presence of an epoxide, polymerizing the epoxide.

In particular, the process for the in situ production of these blends of the invention comprises:

A) charging a reaction vessel with a mixture comprising:

(1) initial starting Material (S)_i) A monofunctional compound (i.e., a monohydric alcohol) having an equivalent weight of at least about 200;

and

(2) DMC (double metal cyanide) catalysts;

B) in the presence of a DMC catalyst and S_iIn the reaction vessel of

(i) An epoxide comprising propylene oxide and ethylene oxide in a weight ratio of 100: 0 to 20: 80 (preferably 100: 0 to 40: 60 and more preferably about 100: 0 to 55: 45);

C) by feeding epoxide, the epoxide mixture and S_i(monofunctional starting material) until the equivalent weight of the monofunctional compound has increased by at least 10% by weight (based on the initial equivalent weight) and the equivalent weight reaches a value of between about 1,500 and about 6,000, preferably a value of between about 2,000 and 4,000;

D) continuously feeding the epoxide mixture into the reaction vessel while continuously feeding

(1) Continuous starting material (S) comprising one or more polyols_c) An average functionality of from about 2.0 to about 8, preferably about 3, and an equivalent weight of from about 28 to about 400 (S, preferably glycerol)_c)；

E) Complete the continuous starting material (S)_c) Adding (1);

and

F) continuously polymerizing the mixture in a reaction vessel until the resulting polyether monol and polyether polyol blend has a total equivalent weight of from about 350 to about 750 (preferably from about 450 to about 700), an average functionality of from about 2 to about 4 (preferably from about 2.2 to about 2.8), and comprises:

(1) from about 25 to about 75% by weight, based on 100% by weight of F) (1) and F) (2), of a polyether monol having an equivalent weight of from 1,500 to 6,000;

and

(2) from about 25 to about 75 weight percent, based on 100 weight percent of F) (1) and F) (2), of a polyether polyol having an average functionality of from about 2.0 to about 8 and an equivalent weight of from 200 to 500.

In general, any epoxide which can be polymerized by means of DMC catalysis can be used in the process according to the invention for the in situ production of polyether monols and polyether polyol blends. Preferred epoxides are ethylene oxide, propylene oxide, butylene oxide (e.g., 1, 2-butylene oxide, 1-dimethylethylene oxide), styrene oxide, and the like, and mixtures thereof. The polymerization of epoxides using DMC catalysts and hydroxyl group containing starters to produce polyether polyols is well known in the art.

Other monomers that copolymerize with the epoxide in the presence of the DMC catalyst can be incorporated into the process of the present invention to produce other types of epoxy-based polymers. For example, U.S. Pat. No. 3,404,109, the disclosure of which is incorporated herein by reference, describes the copolymerization of epoxides with oxiranes to give polyethers, and U.S. Pat. Nos. 5,145,883 and 3,538,043, the disclosures of which are incorporated herein by reference, describe the copolymerization of epoxides with anhydrides to give polyesters or polyether esters.

The process of the present invention requires the initial charge of starting material (S)_i) Different from the starting material (S) continuously added_c). Initial charge of starting Material, S_iConsisting wholly or largely of one or more compounds having one active hydrogen per molecule which can act as sites for epoxide addition. Preferred starting materials are polyoxyalkylene monols formed by the addition of a large number of equivalents of epoxide to low molecular weight monofunctional starting materials such as methanol, ethanol, phenol, allyl alcohol, longer chain alcohols, and the like, and mixtures thereof. Suitable epoxides may include, for example, ethylene oxide, propylene oxide, butylene oxide, styrene oxide, and the like, and mixtures thereof. Epoxides can be polymerized using well known techniques and a variety of catalysts including alkali metals, alkali metal hydroxides and alkoxides, double metal cyanide complexes, and many others. Suitable monofunctional starting materials can also be produced, for example, by first producing a diol or triol and then converting all but one of the hydroxyl groups to an ether, ester, or other non-reactive group.

Preferred classes of polyoxyalkylene monool starting materials, S_iAnd consists of polyoxypropylene monols having an average equivalent weight of at least 200 and more preferably greater than about 1,000. These compounds facilitate DMC-catalyzed epoxide addition and provide suitable feed ratios for producing the preferred monol-polyol compositions of the present invention.

In the process of the invention, S is used_iThe amount of (A) depends on many factors including, for example, reactor size, S_iKind of (1), S_iEquivalent weight of (A) and target product, S_cEquivalent weight of (a) and other factors. Preferably, S_iBased on S_iAnd S_cIs in the range of from about 2 to about 75 mole%. Starting Material (S)_t) OfIn an amount equivalent to the amount of the continuously added starting material (S)_c) Added with the initial charge of starting material (S)_i) The sum of the amounts of (c). Thus, S_t＝S_c+S_i。

The catalyst is a Double Metal Cyanide (DMC) catalyst. Any DMC catalyst known in the art is suitable for use in the process of the present invention. These well known catalysts are the reaction product of a water soluble metal salt such as zinc chloride and a water soluble metal cyanide salt such as potassium hexacyanocobaltate. The preparation of suitable DMC catalysts is described in a number of references, for example, U.S. Pat. Nos. 5,158,922, 4,477,589, 3,427,334, 3,941,849, 5,470,813, and 5,482,908, the disclosures of which are incorporated herein by reference. A particularly preferred DMC catalyst is zinc hexacyanocobaltate.

The DMC catalyst comprises an organic complexing agent. As taught by the aforementioned references, a complexing agent is required for the active catalyst. Preferred complexing agents are water-soluble heteroatom-containing organic compounds that can be complexed with the DMC compound. Particularly preferred complexing agents are water-soluble aliphatic alcohols. Tert-butanol is most preferred. In addition to the organic complexing agent, the DMC catalyst may comprise a polyether, as described in U.S. patent 5,482,908.

Preferred DMC catalysts for use in the process are high efficiency catalysts such as those described in U.S. Pat. nos. 5,482,908 and 5,470,813, the disclosures of which are incorporated herein by reference. The high activity allows the catalyst to be used at very low concentrations, preferably at sufficiently low concentrations that the need to remove the catalyst from the final blend of polyether monol and polyether polyol product can be avoided.

The process of the invention also requires the continuous addition of the polyfunctional starting materials (S)_c). Conventional processes for the manufacture of polyether polyols, including KOH-catalyzed and DMC-catalyzed processes, charge the catalyst used and all starter materials to the reactor at the beginning of the polymerization, and then add the epoxide continuously. In contrast, the process of the present invention combines a DMC catalyst and an initial monofunctional starter(S_i) Is charged to the reactor, followed by the epoxide and polymerization until the monol reaches the desired equivalent weight. At this time, S is started_cFeeding, and at a continuous controlled rate relative to a continuous epoxide feed, until a continuous starting material (S) is completed_c) Adding the mixture. The epoxide feed is continued until the desired total OH number is reached. S_cIt can be mixed with the epoxide and added or, preferably, it is added as a separate stream.

S_cPreferably a low molecular weight polyol or a blend of low molecular weight polyols. In this application, the low molecular weight polyol is defined as having from about 2 to about 8 hydroxyl groups, preferably about 3 hydroxyl groups, and having an average equivalent weight of from about 28 to about 400, preferably from about 28 to about 100. Suitable low molecular weight polyols include, for example, the following compounds: glycerol, propylene glycol, dipropylene glycol, ethylene glycol, trimethylolpropane, sucrose, sorbitol, tripropylene glycol, and the like, and mixtures thereof. Preferred starting materials to be added continuously are glycerol and trimethylolpropane. Low molecular weight polyether polyols prepared by addition of a plurality of epoxides on these polyols or other starting materials having two or more active hydrogens can also be used as S_c。

S_cOther compounds having at least two active hydrogens per molecule are also possible, and are known suitable initiators for conventional DMC-catalyzed epoxide polymerizations, including, for example, the following compounds: alcohols, thiols, aldehydes and enolizable hydrogen-containing ketones, malonates, phenols, carboxylic acids and anhydrides, aromatic amines, acetylene, and the like, and mixtures thereof. Examples of suitable active hydrogen-containing compounds are found in U.S. Pat. Nos. 3,900,518, 3,941,849, and 4,472,560, the disclosures of which are incorporated herein by reference.

S used_cThe amount of (a) is at least about 25 mole percent of the total amount of starting materials used.

As previously mentioned, various epoxides may be used in the process of the present invention. Propylene oxide and ethylene oxide are preferred epoxides. The process of the invention is characterized in that the composition of the epoxide can be varied to control the composition of the polyether monol and the polyether polyol component in the final product. For example, propylene oxide can be added continuously during the polymerization of the monoalcohol, starting material S_cIs added separately before addition. At S_cAfter the addition is initiated, the blend of ethylene oxide and propylene oxide may be fed to produce a high functionality polyether polyol comprised of a poly (ethylene oxide-propylene oxide) copolymer. Because the oxide addition by DMC catalysis is predominantly on the lower equivalent weight polyether polyol, the polyether monol component can remain predominantly poly (propylene oxide). By reversing these sequences, polyether monols and polyether polyols having a higher poly (ethylene oxide) content can be produced which may be predominantly poly (propylene oxide).

The epoxide composition may also be during the initial polymerization of the monool and/or at S_cAt some point during the joining and/or at S_cThe addition is followed by a change. This provides flexibility in controlling the distribution of ethylene oxide or propylene oxide within the polyether monol and polyether polyol, and enables control of the primary and secondary hydroxyl functionality of the polyether monol and polyether polyol to some extent, and thus the relative reactivity of the components in the final composition. In this way, the product can be designed to meet the reactivity and performance requirements of the intended application, such as polyurethane foam.

The blends of in situ polymerized polyether monols and polyether polyols produced by the process of the present invention are characterized by: the total equivalent weight is from about 350 to about 750, preferably from about 450 to about 700, and the average functionality is from about 2 to about 4, preferably from about 2.2 to about 2.8. These in situ polymerized blends comprise:

(1) from about 25 to 75% by weight, based on 100% of the total weight of (1) and (2), of a polyether monol having an equivalent weight of from about 1,500 to about 6,000, preferably from about 2,000 to about 4,000;

and

(2) from about 25 to 75% by weight, based on 100% of the total weight of (1) and (2), of a polyether polyol having an equivalent weight of from about 200 to about 500 (preferably from about 300 to about 400) and an average functionality of from about 2.0 to about 8 (preferably from about 2.5 to about 3.5, more preferably about 3).

It has been found that these in situ polymerized polyether monol and polyether polyol blends produced by the above described process can be used to produce slow recovery "viscoelastic" foams. Such foams have found wide utility in the production of pillows, mattress toppers, ergonomic (ergonomic) cushions, sports equipment, and the like. It has been surprisingly found that blends produced in situ have comparable or even superior properties to similar polyether monols and polyether polyols produced separately and blended together. The production of such viscoelastic foams is described in detail in U.S. application serial No. 09/495,192, filed on the united states patent office at 31.1.2000, which is commonly assigned and the disclosure of which is incorporated herein by reference.

The commercial production of viscoelastic foams involves mixing together a suitable polyisocyanate, a blowing agent, and an isocyanate-reactive component or mixture in the presence of a surfactant, one or more catalysts, and various other compounds known in the art of polyurethane chemistry to be suitable for preparing viscoelastic foams. In addition to the in situ formed polyether monol and polyether polyol blends described above, other isocyanate-reactive compounds used are well known in the art of polyurethane chemistry. These include higher molecular weight compounds such as polyether polyols, polyester polyols, polymer polyols, amine-terminated polyethers, polythioethers, polyacetals, and polycarbonates, as well as various low molecular weight chain extenders and/or crosslinkers, both of which may contain hydroxyl groups and/or amine groups capable of reacting with the isocyanate groups of the isocyanate component.

As used herein, the term nominal equivalent weight refers to the polyol starting material (S) once the feed is initiated continuously_c) Assuming that the epoxide is added exclusively to the low equivalent weight polyol component, the expected molar weight per reactive hydroxyl group. The nominal molecular weight is the nominal number average equivalent weight multiplied by the functionality of the starting material. The nominal hydroxyl number is equal to 56,100 divided by the nominal equivalent weight.

The following examples further illustrate details of the process of the present invention. The invention disclosed above is not to be limited either in spirit or scope by these examples. Those skilled in the art will readily appreciate that known variations of the conditions of the following procedures may be used. Unless otherwise indicated, all temperatures are degrees Celsius and all parts and percentages are parts by weight and percentages by weight.

Examples

Example 1:

polyols having two different molecular weights are produced in situ by a double metal cyanide-catalyzed process for the production of polyoxyalkylene polyols as described in U.S. Pat. nos. 5,689,012 and 5,777,177, the disclosures of which are incorporated herein by reference.

The reactor was charged with a 35 hydroxyl value (1600Da equivalent weight) monohydric alcohol having a polyoxyalkylene portion containing about 100% by weight of propylene oxide moieties. Zinc hexacyanocobaltate tert-butanol complex catalyst is added to the reactor in an amount of 60 to 90ppm based on the weight of the product polyol and the alkoxylation is started with propylene oxide. When the alkoxylation proceeded to a hydroxyl number of 24. + -.2, the glycerol co-feed was started. The oxygenate feed contained 6.7 weight percent glycerol. It is calculated by the following formula: [ (glycerol weight) × 100/(glycerol weight + oxide weight) ]. The feed was continued until a hydroxyl number of 82 was reached. The resulting product is a mixed functional polyol blend consisting of a high equivalent weight polyether monol (nominally 2340Da, and 24 hydroxyl numbers) and a low equivalent weight polyether triol (nominally about 510Da, and 110 hydroxyl numbers) having a nominal molecular weight of 1530 Da. The high equivalent weight polyether monols comprise about 30 weight percent of the product. The different molecular weight distributions of the two components of the blend produced by this method are shown in figure 1 by GPC (gel permeation chromatography) techniques as described below. Polyether monols have a peak molecular weight of 2058 and polyether triols have a peak molecular weight of 1338.

Gel Permeation Chromatography (GPC) technique:

polyether polyol samples were analyzed by gel permeation chromatography using HPLC grade chloroform as the elution solvent (flow rate ═ 1 mL/min). A Waters Alliance 2690 liquid chromatograph was used with a Pigel 3iLim MIXED-E column (Polymer Laboratories) and a refractive index detector (output in millivolts).

The instrument was calibrated using polyethylene glycol standards (Scientific Polymer Products) with peak molecular weights of 320 to 19,000 Da. The peak molecular weights of the reported examples are based on these calibration standards. The actual molecular weight may differ slightly from the measured value due to differences in composition and functionality from the standard sample.

Example 2:

the procedure as described in example 1 was substantially repeated except for the following changes. When the alkoxylation proceeded to a hydroxyl number of the polyether monol of 20. + -.2, the glycerol cofeed was started. The co-feed used had a slightly higher proportion of glycerol (approximately 8.6%) continuously added to the feed and the feed continued until the hydroxyl number of the polyether product reached 92. The product is a mixed functional polyol consisting of a nominal 20 hydroxyl number (about 2800Da equivalent weight) polyether monol and a nominal 130 hydroxyl number (about 430Da equivalent weight, 1290Da molecular weight) polyether triol. The polyether monol comprises about 40 weight percent of the product. The different molecular weight distributions of the two components of the blend produced by this method are shown in figure 2 by GPC techniques as described above. The polyether monol has a peak molecular weight of 2378 and the polyether triol has a peak molecular weight of 1118.

Example 3:

the procedure as described in example 2 was substantially repeated except for the following changes. The alkoxylation of 36 hydroxyl value monools was started with a feed comprising propylene oxide and ethylene oxide in a weight ratio of 80: 20. Alkoxylation was accomplished using a feed comprising propylene oxide and ethylene oxide in a weight ratio of 100: 0 as the last 5 weight percent feed. A slightly higher proportion of continuously added glycerol (approximately 8.9%) was used in the feed and the feed was continued until the product hydroxyl number reached 93. The product is a mixed functional polyol consisting of a polyether monol having an ethylene oxide rich end and a nominal 20 hydroxyl number (about 2800Da equivalent weight) and a polyether triol having a polyoxyalkylene portion, a propylene oxide rich end and a nominal 140 hydroxyl number (about 400Da equivalent weight, 1200Da molecular weight). The polyether monol comprises about 40 weight percent of the product. The different molecular weight distributions of the two components of the blend produced by this method are shown in figure 3 by GPC techniques as described above. Polyether monols have a peak molecular weight of 2501 and polyether triols have a peak molecular weight of 1110.

Example 4:

the procedure as described in example 2 was substantially repeated except for the following changes. Alkoxylation was started with a feed comprising propylene oxide and ethylene oxide in a weight ratio of 84: 16, with glycerol co-feed starting when the hydroxyl number was 18 ± 2 and continuing until the hydroxyl number reached 85. The product is a mixed functional polyol consisting of a polyether monol having ethylene oxide rich ends and a nominal 18 hydroxyl number (about 3120Da equivalent weight) and a polyether triol having a mixed polyoxyalkylene and a nominal 140 hydroxyl number (about 400Da equivalent weight, 1200Da molecular weight). The polyether monol comprises about 45 weight percent of the product. The different molecular weight distributions of the two components of the blend produced by this method are shown in figure 4 by GPC techniques as described above. The polyether monol has a peak molecular weight of 2618 and the polyether triol has a peak molecular weight of 1089.

Example 5:

the procedure as described in example 4 was substantially repeated except for the following changes. Alkoxylation started with an 80: 20 weight ratio of propylene oxide to ethylene oxide, the feed used a slightly higher ratio of continuously added glycerol, and the feed continued until a hydroxyl number of 94 was reached. The product is a mixed functional polyol consisting of a polyether monol having ethylene oxide rich ends and a nominal 18 hydroxyl number (about 3120Da equivalent weight) and a polyether triol having a mixed polyoxyalkylene and a nominal 170 hydroxyl number (about 330Da equivalent weight; 990Da molecular weight). The polyether monol comprises about 50 weight percent of the product. The different molecular weight distributions of the two components of the blend produced by this method are shown in figure 5 by GPC techniques as described above. The polyether monol has a peak molecular weight of 2637 and the polyether triol has a peak molecular weight of 926.

Example 6:

the procedure as described in example 5 was substantially repeated except for the following changes. After alkoxylation, the feed used a higher proportion (approximately 16.6%) of continuously added glycerol and continued until the hydroxyl number reached 130. The product is a mixed functional polyol consisting of a polyether monol having ethylene oxide rich ends and a nominal 18 hydroxyl number (about 3120Da equivalent weight) and a polyether triol having a mixed polyoxyalkylene and a nominal 240 hydroxyl number (about 235Da equivalent weight, 705Da molecular weight). The polyether monol comprises about 50 weight percent of the product. The different molecular weight distributions of the two components are shown in figure 6. The polyether monol has a peak molecular weight of 2570 and the polyether triol has a peak molecular weight of 664.

The following components were used to prepare viscoelastic foams.

MS-1: a blend of monofunctional alcohols having an average molecular weight of about 200; neodol 25 is available from Shell Chemical

MS-2: 35 OH number polyether monols, formed by propoxylation of MS-1 in the presence of DMC catalysts (no ethylene oxide co-feed was used).

M-1: blends of monofunctional polyether alcohols having an average hydroxyl number of 20 and formed by KOH propoxylation of MS-2

M-2: blends of monofunctional polyether alcohols having an average hydroxyl number of 20, an average polymerized ethylene oxide content of about 10% by weight, and prepared by DMC alkoxylation of MS-2 using propylene oxide and ethylene oxide

M-3: monofunctional polyether alcohols having an average hydroxyl number of 21 and an average polymerized ethylene oxide content of about 15% by weight and prepared by DMC-catalyzed alkoxylation of MS-2 using propylene oxide and ethylene oxide

MP-1: the in-situ formed blend of polyether monol and polyether triol prepared in example 2 above

MP-2: the in-situ formed blend of polyether monol and polyether triol produced in example 3 above

P-1: polyether triols having a hydroxyl number of about 135 and prepared by propoxylation of glycerol

P-2: polyether triols having hydroxyl numbers of about 135 and prepared by DMC-catalyzed alkoxylation of a 240 hydroxyl number initiator having a functionality of 3 (i.e., propoxylated glycerin) using a blend of propylene oxide and ethylene oxide (20% EO in product)

P-3: polyether triols having a hydroxyl number of about 150 and prepared by propoxylation of glycerol

PG: propylene glycol

Catalyst 1: amine catalyst blends available as NIAX C-183 from Osi Specialties

Catalyst 2: a stannous octoate catalyst; available as Dabco T-9 from Air Products

Surfactant 1: silicone surfactants, available as Niax Silicone L620 from Osi Specialties

Flame retardant: DE60F Special for, from Great Lakes Chemicals

TDI: a blend of 80% by weight of 2, 4-toluene diisocyanate and 20% by weight of 2, 6-toluene diisocyanate

The following general procedure was used to produce the viscoelastic foams of examples 7-12 below

A series of nominal 3lb/ft were prepared in the laboratory using a conventional bench foaming procedure³(PCF) free-rise tacky resilient foam. The ingredients were mixed thoroughly except Toluene Diisocyanate (TDI). Then, TDI (an industrial 80: 20% by weight mixture of the 2, 4-and 2, 6-isomers) was added and mixed briefly. The mixture was poured into a standard 14 inch (35.6cm) by 14 inch by 6 inch (15.2cm) cake (cake) box. The mixture was allowed to develop freely to full height, after which the degree of sedimentation (settling) was determined. The foam was oven cured at 145 ℃ for 30 min. After a minimum of 16 hours at room temperature, the shrinkage (if any) was recorded and a 12 inch (30 cm) by 12 inch by 4 inch (10 cm) sample was cut for physical testing. The formulations, processability and foam properties are shown in tables 1 and 2 below.

The polyol component of comparative examples 7, 9 and 11 consisted of polyether monol and polyether polyol produced separately and then blended into the foam formulation. The in situ polymerized blends of polyether monol and polyether polyol of examples 8, 10 and 12 have similar compositions and equivalent weights as the polyether monol and polyether polyol of comparative examples 7, 9 and 11, respectively. As shown in tables 1 and 2, both the separately prepared blends of polyether monol and polyether polyol and the in situ polymerized blends of polyether monol and polyether polyol give in each case good quality viscoelastic foams. It is also evident in each comparison (examples 7 to 8,9 to 10 and 11 to 12) that the blends produced in situ have improved compression set (90% compression set, 75% Humid Aged Compression Set (HACS) and 50% humid set) properties. The values listed show the rate of loss in height of the foam after being held in a compressed state at elevated temperatures. Higher compression set may indicate a tendency for the foam to lose height in service.

The 90% compression set and 75% HACS test methods are described in ASTM D3574. Height loss is measured as a percentage of the height of deflection without restoration (C)_dMethod). Condition J₁(3 hours at 105 ℃) was used as the wet aging condition. The 50% wet set was performed in a similar manner to the 90% compression set determination, except that the sample was compressed to 50% of its original height and held in this compressed state at 50 ℃ and 95% relative humidity for 22 hours. The height loss of the original sample was determined under standard laboratory conditions after a 30 minute recovery time.

Table 1: viscoelastic foams produced with blended mono-and triols and viscoelastic foams produced with in situ formed blends of mono-and triols

Foam formulations	Example 7	Example 8	Example 9	Example 10	Example 11	Example 12
							M-1	37
M-2			40
							M-3					40
MP-1		100
							MP-2				100		100
P-1	63
							P-2			60
P-3					60
							PG	1.0	1.0	1.0	1.0	0.5
Water (W)	1.9	1.9	1.9	1.9	1.9	1.9
							Catalyst 1	0.34	0.34	0.40	0.40	0.40	0.40
Catalyst 2	0.10	0.10	0.12	0.12	0.12	0.12
							Surfactant 1	0.5	0.5	0.4	0.4	0.4	0.4
Flame retardant	3.0	3.0
							TDI	34.5	34.2	34.0	34.6	32.0	32.3
Index of refraction	100	100	100	100	100	100
							Foam processing	Good taste	Good taste	Good taste	Good taste	Good taste	Good taste

Table 2: properties of the viscoelastic foams prepared in Table 1

Foam performance	Example 7	Example 8	Example 9	Example 10	Example 11	Example 12
							Density, pcf	2.81	2.81	2.79	2.89	2.75	2.73
Rebound rate of%	8	10	4	3	19	10
							Air velocity, scfm	1.30	0.75	0.48	0.03	1.55	0.75
IFD thickness	3.98	3.98	4.05	4.02	4.00	4.02
							25％IFD，lbs	13.85	14.75	12.28	12.83	13.35	14.20
65％IFD，lbs	28.g8	30.75	24.15	24.73	28.01	27.89
							25% recovery,%	77.83	77.02	77.77	77.32	81.87	79.30
65/25IFD	2.09	2.08	1.97	19.3	2.10	1.96
							Tensile Strength, psi	10.07	9.23	10.41	10.22	nd	nd
Elongation percentage of%	218	203	234	242	nd	nd
							Tear, pli	0.82	0.75	0.87	0.80	0.57	0.50
90% compression set%	6.45	4.86	6.53	5.01	8.77	5.45
							75％HACS，％	6.09	5.00	5.76	4.84.	nd	nd
50% wet permanent set%	3.07	2.26	2.76	2.61	4.28	2.91

Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.

Claims (15)

1. A process for the in situ production of a blend of polyether monol and polyether polyol comprising:

A) introducing into a reaction vessel a mixture comprising:

(1) initial starting Material (S)_i) Which is a polyoxyalkylene monool and mixtures thereof, and

(2) a DMC (double metal cyanide) catalyst,

B) feeding in the reaction vessel

(1) An epoxide comprising propylene oxide and ethylene oxide in a weight ratio of 100: 0 to 20: 80;

C) reacting the epoxide mixture and the initial starting material (S)₁) Reacting and continuing the polymerization by feeding epoxide until the equivalent weight of the monofunctional compound increases by at least 10% by weight and reaches a value between 1,500 and 6,000;

D) continuously feeding (1) a low molecular weight starting material (S) into the reaction vessel while continuously feeding epoxide_c) A low molecular weight polyol or a mixture of low molecular weight polyols;

E) complete the continuous starting material (S)_c) Adding (1);

and

F) continuously polymerizing the mixture in the reaction vessel until a resulting blend of monohydric alcohol and polyhydric alcohol having a total average equivalent weight of from 350 to 750, an average functionality of from 2 to 4, and comprising:

(1) 25 to 75% by weight, based on 100% by weight of F) (1) and F) (2), of a polyether monol having an equivalent weight of 1,500 to 6,000;

and

(2) from 25 to 75% by weight, based on 100% by weight of F) (1) and F) (2), of a polyether polyol having an equivalent weight of from 200 to 500 and an average functionality of from 2.0 to 8.

2. The process of claim 1 wherein the weight ratio of propylene oxide to ethylene oxide in the epoxide continuously fed in step C) differs from the actual weight ratio of propylene oxide to ethylene oxide in the epoxide fed to the reaction vessel in step B) in that there is a higher average ratio of ethylene oxide to propylene oxide in step C).

3. The process of claim 1 wherein the weight ratio of propylene oxide to ethylene oxide in the epoxide continuously fed in step D) differs from the actual weight ratio of propylene oxide to ethylene oxide in the epoxide fed to the reaction vessel in step B) in that there is a higher average ratio of ethylene oxide to propylene oxide in step D).

4. The process of claim 3 wherein the weight ratio of propylene oxide to ethylene oxide in the epoxide continuously fed in step D) differs from the actual weight ratio of propylene oxide to ethylene oxide in the epoxide composition fed to the reaction vessel in step C) in that there is a higher average ratio of ethylene oxide to propylene oxide in step D).

5. The process of claim 1, wherein A) (1) the initial starting material (S)_i) Has an equivalent weight of at least 200.

6. The process of claim 1 wherein B) (1) the epoxide comprises propylene oxide and ethylene oxide in a weight ratio of from 100: 0 to 40: 60.

7. The process of claim 1, wherein in step C) the epoxide mixture and the initial starting material (S) are reacted_i) The reaction between (a) and (b) is continued until the equivalent weight of the polyether monol reaches a value between 2,000 and 4,000.

8. The process of claim 1, wherein D) (1) a low molecular weight starting material (S)_c) Having a functionality of 3 and an equivalent weight of 28 to 100.

9. The process of claim 8 wherein D) (1) a low molecular weight starting material (S)_c) Including glycerin.

10. The process of claim 1 wherein the mixture is continuously reacted in F) until a polyether monol and polyether polyol blend is obtained having a total average equivalent weight of from 450 to 700 and an average functionality of from 2.2 to 2.8.

11. An in situ polymerized polyether monol and polyether polyol blend characterized by a total equivalent weight of 350 to 750 and an average functionality of 2 to 4 and comprising:

(1) 25 to 75 weight percent, based on the total weight of the blend, of a polyether monol having an equivalent weight of 1,500 to 6,000;

and

(2) 25 to 75 weight percent, based on the total weight of the blend, of a polyether polyol having an equivalent weight of 200 to 500 and an average functionality of 2.0 to 8.

12. The in situ polymerized blend of claim 11, wherein the total equivalent weight is from 450 to 700 and the average functionality is from 2.2 to 2.8.

13. The in situ polymerized blend of claim 11, wherein

(1) The polyether monol has an equivalent weight of 2,000 to 4,000;

and

(2) the polyether polyol has an equivalent weight of 300 to 400 and an average functionality of 2.5 to 3.5.

14. The in situ polymerized blend of claim 13, wherein (2) said polyether polyol has an average functionality of 3.

15. A process for producing a viscoelastic polyurethane foam comprising reacting a polyisocyanate with an isocyanate-reactive mixture in the presence of at least one blowing agent, a surfactant and one or more catalysts at an isocyanate index of 90 to 120, wherein the isocyanate-reactive mixture comprises at least 50% by weight, based on 100% by weight of the isocyanate-reactive mixture, of a blend of one or more polyether monols and one or more polyether polyols formed in situ, the blend being characterized by an average equivalent weight of 350 to 750 and an average functionality of 2 to 4, wherein the in situ formed blend comprises:

(1) from 25 to 75 weight percent, based on 100 weight percent of (1) and (2), of a polyether monol having an equivalent weight of from 1,500 to 6,000;

and

(2) from 25 to 75% by weight, based on 100% by weight of (1) and (2), of a polyether polyol having an equivalent weight of from 200 to 500 and an average functionality of from 2.0 to 8.