MXPA00013026A - Polymer polyols and a process for the production thereof - Google Patents

Abstract

Polymer polyols and a process for their production are disclosed. The process requires the selection of specified free radical polymerization initiators and amounts thereof to produce a polymer polyol having desired properties including a Brookfield Viscosity of equal to or less than (a e[(0. 051)(b)]) where"a"is the viscosity of the carrier polyol and"b"is the [(weight fraction of solids)(100)].

Description

POLYMER POLYOLES AND A PROCESS FOR THEIR PRODUCTION The present invention relates to polymer polyols and to a process for their preparation. Polyol polyols suitable for the preparation of polyurethane foams and elastomers are well known and are widely used on a commercial scale. Polyurethane foams made from polymer polyols have a wide variety of uses. The two main types of polyurethane foams are sheet or plate material and molded foam. Foams of plate material or polyurethane sheets are used in carpet, furniture and mattress applications. Molded polyurethane foams are used in the automotive industry for a variety of applications. The polymer polyols are produced by polymerizing one or more ethylenically unsaturated monomers, dissolved or dispersed in a polyol, in the presence of a free radical catalyst, to form a stable dispersion of polymer particles in the polyol. Initially polymer polyols were prepared which produced polyurethane foams with higher load-bearing properties than those produced from unmodified polyols, using acrylonitrile monomer; however, many of those polymer polyols had undesirably high viscosity. Presently, polyurethane foams having high load-bearing properties are predominantly produced, using polymer polyols which are prepared using a monomer mixture with a high styrene content (for example, from 65 to 75 percent styrene). However, polymer polyols produced from this monomeric mixture with high styrene content, often do not meet the increasing needs of the industry, including the requirements of acceptable viscosity, strict stability and increased load bearing properties. The stability and low viscosity of polymer polyols are becoming increasingly important for polyurethane foam manufacturers, due to the development of sophisticated, high speed and high volume equipment and systems to handle, mix and react the ingredients polyurethane formers Polymer polyols must meet certain minimum polymer particle size requirements to avoid plugging filters, pumps and other parts of such foam processing equipment, or failing for relatively short periods of time. Numerous attempts have been made to produce polymer polyols that satisfy the foam processing and load-bearing properties necessary for the polyurethane foam industry. International application PCT / EP95 / 04149 (Fogg) describes stable polymer polyols, of relatively low viscosity, prepared by free radical polymerization of a composition comprising a polyol; a preformed stabilizer which is the reaction product of a polyol, a precursor stabilizer obtainable by reacting a silicon compound with a polyether polyol, at least one ethylenically unsaturated monomer and a free radical polymerization initiator; at least one ethylenically unsaturated monomer; a free radical polymerization initiator and, optionally, a chain transfer agent. U.S. Patent No. 5,196,476 (Simroth) discloses: (a) a preformed, high-potency stabilizer; (b) the use thereof in the manufacture of polymer polyols having high solids content, lower viscosity and excellent product stability; and (c) a polyurethane made using said polymer polyol. The preformed stabilizer is the product of free radical polymerization of at least one monomer ethylenically unsaturated, polymerizable with free radical, and at least one adduct of polyhydric alcohol, comprising a polyhydric alcohol residue and a residue of a compound having fumaric or maleic unsaturation. U.S. Patent No. 5,364,906 (Critchfiel et al. co-inventors) describes a method for producing a stable, low viscosity polymer polyol, with a modified seed method, by the steps of (1) producing a first reaction product by polymerizing a first feed in a first continuous reactor in the presence of an initiator, including the first feed less than 50 percent by weight of a total proportion «^ .. ^^ ^ -,. The amount of monomer in at least 50 percent of a proportion of total base polyol, optionally in the presence of a precursor stabilizer which is prepared by reacting a polyol. CD? maleic anhydride; and (2) producing a second reaction product by polymerizing a second feed in a continuous reactor, in the presence of an initiator; the second feed comprising (a) the first reaction product; (b) at least 50 weight percent of the total monomer ratio; and (c) any residue, of the proportion of base polyol. European Patent No. 0 162 589 B1 (Cloetens and co-authors) discloses a non-aqueous dispersion stabilizer, which is the reaction product of a polyether polyol having an average molecular weight greater than 400 and a hydroxyl number on the scale of 20 to 280, the compound containing the silicon atom having at least one olefinically unsaturated functional group and at least one functional group attached to the silicon atom which is reactable with the hydroxyl groups in the polyether polyol. U.S. Patent No. 4,661,531 (Davis and co-inventors) discloses a process for preparing a polymer polyol in a continuous process, wherein the use of a chain transfer agent contributes to products having uniform viscosity. Another interesting prior art includes U.S. Patent No. Re. 32,733 (Simroth and coinventores); U.S. Patent No. 3,931,092 (Ramlow and co-inventors); U.S. Patent No. 4,014,846 (Ramlow and co-inventors); U.S. Patent No. 4,093,573 (Ramlow and co-inventors); U.S. Patent No. 4,148,840 (Shah); U.S. Patent No. 4,172,825 (Shook and co-inventors); U.S. Patent No. 4,342,840 (Kozawa and co-inventors); U.S. Patent No. 4,390,645 (Hoffman and co-inventors); U.S. Patent No. 5,394,491 (Hoffman), U.S. Patent No. 4,454,255 (Ramlow and co-inventors); U.S. Patent No. 4,458,038 (Ramlow and co-inventors) and U.S. Patent No. 4,745,153 (Hoffman). Although there has been progress in reducing viscosity and increasing the solids content of the polymer polyols, there is still a need for polymer polyols that have improved processing and load-bearing properties, and for alternative methods for forming said polyols from polymer. The present invention is directed to a process of low faults for the production of polymer polyols having a Brookfield viscosity that is equal to or less than (ae [(0 051> (?))) Where "a" is the viscosity of the carrier polyol and "b" is [(fraction by weight of solids) (100).] This process comprises the use of a free radical initiator comprising at least one active first peroxide, either alone or together with additional initiators, which may be a different active peroxide, or may be an azo compound.When said additional initiators are also active peroxides, said additional initiators have a longer half-life ^ J ^ that of the first active peroxide. For half a life it is meant the time necessary to reduce the concentration of initiator by half. The level of the first active peroxide is equal to or less than 0.6 percent by weight (based on the total monomer content). When the first active peroxide is used together with additional initiators, the total weight percentage (based on the total monomer content) of the initiators is not greater than 1.0 percent, as long as, in any case, the level of the The first active peroxide is equal to or less than 0.6 percent by weight (with based on the total monomer content). The invention is also directed to polymer polyols produced by said process and its use in the production of foams and the foams produced in that manner. The polymer polyols thus produced have convenient properties, which include a high polymer content and a high polymer content. product stability. In one aspect the present invention relates to a process for preparing a polymer polyol, comprising providing: (a) a polyol; (b) a preformed stabilizer; (c) at least one ethylenically unsaturated monomer; (d) an initiator of Free radical polymerization, comprising at least one first active peroxide at a level equal to or greater than 0.6 weight percent, based on the total monomer content; and (e) a chain transfer agent to a reaction zone maintained at a temperature, preferably 120 ° C to 140 ° C, sufficient to start a free radical polymerization, and under sufficient pressure ^ g = ^? ^ j ^^^^ í sj! J * ^^^^^ S ^^^ ^ »« -? - g ». * < B. to maintain only liquid phases in the reaction zone, for a period of time sufficient to react a larger portion of the ethylenically unsaturated monomer to form a heterogeneous mixture containing the polymer polyol and recover it from this heterogeneous mixture. In another aspect, the present invention relates to a polymer polyol composition having a polymer content of 30 to 60 weight percent, based on the total weight; a Brookfield viscosity that is equal to or less than (a et (0 ° 51) (b ') j where "a" is the viscosity of the carrier polyol and "b" is [(fraction by weight of solids) (100)] and product stability, so that essentially 100% passes through a 150 mesh screen and , preferably, up to 100% pass through a 700 mesh screen. Said polymer polyols can be produced by a Free radical polymerization of the composition comprising: (a) a polyol; (b) a preformed stabilizer; (c) at least one ethylenically unsaturated monomer; (d) a free radical polymerization initiator, comprising at least a first active peroxide at a level equal to or less than 0.6 percent by weight, based on the total monomer content; and (e) a chain transfer agent. In another aspect, the present invention relates to a polymer polyol composition, which has a content of polymer of 30 to 60 weight percent, based on the total weight, a Brookfield viscosity that is equal to or less than (a eI (0051) (b) l), where "a" is the viscosity of the carrier polyol and " b "is [(fraction sn weight of solids) (100)], and product stability, so that essentially 100% passes through a 150 mesh screen, produced by free radical polymerization of the composition polymer polyol former. Yet another aspect of the present invention relates to a polyurethane foam forming composition comprising the above polymer polyol composition, a polyurethane catalyst, an organic polyisocyanate, a silicone surfactant and a blowing agent. Yet another aspect of the present invention relates to a polyurethane foam made from the forming composition of previous polyurethane foam. The polymer polyol composition of the present invention has a polymer content of 30, preferably 40, up to 60 weight percent; the rest being liquid polyol. The Brookfield viscosity of the polymer polyol of the present invention is equal to or less than (to (0 051) < b > i)? where "a" is the viscosity of the carrier polyol and "b" is [(fraction by weight of solids) (100)]. The polymer polyol compositions of the present invention also show exceptional stability, so that essentially 100 percent passes through a '150 mesh screen. meshes, and significant amounts of polio! of polymer with high ^^! ^ ¿^ ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡^ ^^^ ||| »- 1« a. * AS & solids content, preferably essentially 100 percent, pass through a 700 mesh screen. The polymer polyol composition of the present invention is the reaction product of the composition comprising: (a) a polyol; (b) a preformed stabilized composition; (c) at least one ethylenic unsaturated monomer; (d) a free radical polymerization initiator, comprising at least one first active peroxide used at a level equal to or less than 0.6 percent by weight based on the total monomer; and (e) a chain transfer agent. The process for preparing the polymer polyols of the present invention comprises: providing a heterogeneous mixture of a polyol, a preformed stabilizing composition, at least one free radically polymerizable monomer, a free radical polymerization initiator, comprising at least a first active peroxide used at a level equal to or less than 0.6 weight percent based on the total monomer and a chain transfer agent, in a reaction zone maintained at a temperature sufficient to initiate a free radical polymerization reaction , preferably from 120 ° C to 140 ° C, inclusive, and under sufficient pressure to maintain only liquid phases in the reaction zone, for a period of time sufficient to react a high proportion of the at least one ethylenically unsaturated monomer, and recover the resulting polymer polyol Any known polyol, having a functionality of at least two and a molecular weight in excess of 400, preferably 1,000 to 15,000, more preferably, 2,000 to 8,000, and a hydroxyl number in the range of 20 to 280 can be used. , for the preparation of polymer polyols of the present invention. These polyols are well known and can be obtained commercially. Useful polyols may be, for example, polyether polyols, polyesters containing polyhydroxyl, polyurethane polymers terminated with polyhydroxyl, polyurethane polyether ethers and polytetrahydrofurans. Preferred polyols are polyether polyols. Most preferably, the polyether polyol should be a poly (oxyethylene) (oxypropylene) adduct of a hydroxy-functional initiator or a mixture of initiators having an average of at least two hydroxy groups per molecule; the initiator molecule or molecules are selected from water, glycerol, trimethylolpropane, diethylene glycol, propylene glycol, ethylene glycol; the isomers of butanetriol, pentanotriol and hexanotriol and pentaerythritol, sucrose, sorbitol and the like. The concentration of polyol in the polymer polyol-forming composition is not critical and can vary within wide limits. Typically, the concentration may vary from 40 to 80, preferably 45 to 70, more preferably, from 50 to 60 weight percent, based on the total feed to the reactor. The particular polyol used will depend on the final use of the polyurethane foam to be produced. A mixture of various useful polyols can be used, if is desired.

Any ethylenically unsaturated monomer, which is polymerizable with free radical, can be used in the composition of this invention. It is preferred to use vinyl monomers. The preferred vinyl monomers are: styrene, acrylonitrile, methacrylonitrile and methyl methacrylate. The most preferred vinyl monomers are: styrene, acrylonitrile and mixtures thereof. When a mixture of styrene and acrylonitrile is used, the weight ratio of styrene can vary from 80 to 20 weight percent and the acrylonitrile, consequently, can vary from 80 to 20 weight percent of the mix. A ratio of styrene to acrylonitrile, in the monomer mixture, is preferred from 80:20 to 20:80, with the ratio of 70:30 to 50:50 being more preferred. Preformed stabilizers, useful in the present invention, are known in the art and include, without limitation,15 described in the references discussed here. Preferred preformed stabilizers include those discussed in PCT / EP95 / 04149; US Patent 4,148,840 (Shah); and US Patent 5,364,906 (Critchfield). The preformed stabilizers are prepared Particularly preferred using as stabilizer precursors stabilizing compounds obtained by reacting a compound containing silicon atom, of the formula: RnSIX4-nO RnSÍ ((- OSI (R1) 2X) 4-n where R groups are independently saturated hydrocarbyl groups or unsaturated, at least one group R is a group fc -? - u. «.as well», »¿a - j * -aEB8ttafc» MA A * .. **, *. «*« - -., Í ^^^ t? ^? ^ _ ^^ _ olefinically unsaturated hydrocarbyl; R1 is a hydrocarbyl group, X is an alkoxy group of 1 to 10 carbon atoms; n is an integer from 1 to 3 and p is an integer greater than zero; with a polyether polyol having an average molecular weight of more than 400, and a hydroxyl number in the range of 20 to 280. Particularly preferred precursor stabilizers are the reaction products of vinyltrimethoxysilane, vinyltriethoxysilane or vinyltripropoxysilane, having a polyether polyol a average molecular weight of more than 400 and a hydroxyl number in the range of 20 to 280. These precursor stabilizers and their preparation are described in European Patent No. 0 162 589 B1 (Cloetens and co-Inventors). The preferred preformed stabilizer used in this invention can be prepared as described in PCT / EP95 / 04149, where a preformed stabilizer is prepared by providing a polyol, a precursor stabilizer, a monomer and a free radical polymerization initiator, to an area of reaction maintained at a temperature sufficient to initiate a polymerization by free radical, and under sufficient pressure to maintain only liquid phases in the reaction zone, for a period of time sufficient to react essentially all of the precursor stabilizer and recover a heterogeneous mixture containing the preformed stabilizing composition. The polyols used in the composition for preparing the preformed stabilizer composition of this invention may be, for example, polyether polyols, polyesters containing polyhydroxyl, polyurethane polymers terminated with polyhydroxyl, polyhydric polythioethers and polytetrahydrofurans. These polyols are well known and commercially available. The preferred polyols are polyether polyols. The polyether polyol used should have a number average molecular weight of more than 400, preferably of 3,000, more preferably, of 5,000 and a hydroxyl number in the range of 20 to 280. Most preferably, the polyether polyol deoe be a poly (oxyethylene) (oxypropylene) adduct of an alcohol selected from glycerol, trimethylolpropane, diethylene glycol; the isomers of butanetriol, pentanotriol and hexanotriol and pentaerythritol, sucrose and sorbitol. A mixture of polyols can be used, if desired. The concentration of polyol in the preformed stabilizer forming composition is not critical and can vary within wide limits. Typically, the concentration can vary from 5C to 90 percent by weight or even more, preferably, 60 to 70 percent by weight, based on the total feed to the reactor. A mixture of various useful polyols, if desired. Any ethylenically unsaturated monomer, which is polymerizable with free radical, can be used as component (iii) in the preformed stabilizer forming composition of this invention. It is preferred to use vinyl monomers. The preferred vinyl monomers are: styrene, acrylonitrile, methacrylonitrile and methyl methacrylate. The most preferred vinyl monomers are styrene, acrylonitrile and mixtures thereof. Typically, a mininel of 2 to 20 weight percent of an ethylenically unsaturated monomer is used in the preformed stabilizer forming composition. When a mixture of styrene and acrylonitrile is used, the weight ratio of styrene can vary from 20 to 80 weight percent and, consequently, the acrylonitrile can vary from 80 to 20 weight percent of the mixture. A ratio of styrene to acrylonitrile in the monomer mixture of 80:20 to 20:80 is preferred, with the ratio of 70:30 to 50:50 being very preferred. The free radical polymerization initiator useful in the preparation of the preformed stabilizer of this invention can be any compound that is routinely used to effect the grafting of an ethylenically unsaturated polymer to a polyol, including peroxides, perborates, persulfates, percarbonates and azo compounds. Typical examples of such free radical initiators include alkyl and aryl hydroperoxides, dialkyl and diaryl peroxides, dialkyl peroxydicarbonates and azobis (nitriles). Preferred free radical initiators are terbutylperoxydiethyl acetate and tert-butyl peroctoate. The concentration of free radical initiator in the preformed stabilizer forming composition is not critical and can vary within wide limits. Typically, the concentration can vary from 0.01 to 2.0 percent by weight or even more, preferably 0.05 to 0.2 percent by weight, based on the total feed to the reactor. The particular concentration of the free radical initiator will usually be an optimal value, considering all factors, including cost.

Typically the polyol is used in an amount of 50 to less than 80 weight percent, the precursor stabilizer in an amount of 10 to less than 50 weight percent; the monomer in an amount of 5 to 15 weight percent, and the free radical polymerization initiator in an amount of 0.01 to 2 weight percent in the composition of the invention, preformed stabilizer former. The process for preparing the preformed stabilizer is similar to the process for preparing the polymer polyol. The temperature scale is not critical and can vary from 80 ° C to 150 ° C. The preferred temperature range is 110 ° C to 130 ° C. The mixing conditions used are those obtained using a backmixing reactor. Reactors of this type keep the reaction mixture relatively homogeneous and thus prevent high ratios of monomer to precursor stabilizer, such as occur in tubular reactors, where all monomer is added at the beginning of the reactor. The free radical polymerization initiator useful in the preparation of the polymer polyol comprises peroxides. Said active peroxides include alkyl and aryl hydroperoxides. Such active peroxides can be used or can be used in conjunction with other initiators, such as the different active peroxides or the azo compounds. When other active peroxides are used, they are selected so that they have a half life less than the first active peroxide used in the process.

Preferred free radical initiators include terbutylperoxydiethyl acetate and tertbutyl peroctoate, tertbutyl peroxyisobutyrate, tert-butylperoxy-3,5,5-trimethyl hexanoate, tertbutyl peroxybenzoate, tertbutyl peroxypivalate, teramyl peroxypivalate, tert-butyl peroxy-2-ethylhexanoate . The concentration of free radical initiator of the first active peroxide in the polymer polyol formadc composition is critical and less than 0.6 percent in weight, based on the total monomer. The concentration of the first active peroxide is greater than 0.1 weight percent and it is preferred that it be less than 0.6 weight percent, based on the monomer. When one or more initiators are used, in addition to the first active peroxide initiator, the total concentration of the initiators is less than or equal to 1.0 weight percent, based on the total monomer, provided that the concentration of the first active peroxide initiator is less than or equal to 0.6 percent by weight, based on the total monomer. Any known chain transfer agent can be used in the polymer polyoi-forming composition of the present invention. Preferred chain transfer agents include: isopropanol, diethylamine and n-dodecyl mercaptan. Preferred chain transfer agents are diethylamine and n-dodecyl mercaptan. The polymer polyol former composition is provided in the reactor, preferably a stirred, continuous backmixing reactor. The internal temperature of the reactor inside the a scale from 80 ° C to 150 ° C, preferably from 120 ° C to 140 ° C. The contents of the reactor are mixed well with a residence time of at least 5 minutes, preferably 15 to 45 minutes. The process of this invention results, advantageously, in low levels of reactor failure. The polymer polyol composition of the present invention is useful in the preparation of polyurethane foams. Said polyurethane foams have excellent properties (ie load bearing and tensile strength, without prejudice to other physical properties of foam. The polyurethane foams are prepared by reacting the polymer polyol composition of the present invention with a polyfunctional isocyanate, in the presence of a catalyst for the urethane-forming reaction, an agent blower and a foam stabilizer. The polyfunctional organic isocyanates that can be used for the preparation of the polyurethane foam are well known and commercially available. Illustrative examples of useful polyfunctional organic isocyanates include20 the toluene diisocyanates, especially 2,4- and 2,6-toluene diisocyanate (TDI), as well as any desired mixture of these isomers; 2,4'- and 4,4'-diphenylmethane diisocyanate (MDI), as well as any mixture of these isomers; oligomers of MDI (polymeric MDI), polymethylene polyphenyl polyisocyanates (referred to as commonly "crude MDI"), mixtures of TDI and polymeric MDI and mixtures of these polyisocyanates. The isocyanate prepolymers above (for example with polyether polyols, glycols or their mixtures) can also be used in the present invention. The preferred isocyanate is 80/20 TDI (a mixture of 80 percent 2,4-toluene diisocyanate and 20 percent 26-toluene diisocyanate). Polyfunctional isocyanates are used in amounts well known to those skilled in the art. Any of the blowing agents conventionally used in the production of polyurethane foams can be used. Suitable blowing agents include water, low molecular weight halogenated hydrocarbons, carbon dioxide and low boiling hydrocarbons. Blowing agents are used in amounts well known to persons skilled in the art. Any of the polyurethane catalysts normally used in the preparation of polyurethane foams may be used in the process of the present invention, including tertiary amines and organometallic compounds. The polyurethane catalyst is used in amounts well known to the skilled person. It is also possible to use mixtures of polyurethane catalysts in the process of the present invention. Any of the foam stabilizers or surfactants for cell stability, or other cell size control agents, normally used in the preparation of polyurethane foams can be used in the present invention.

The foam stabilizers, the surfactants for cell stability or other cell control agents are used, in amounts well known to the skilled person. Mixtures of one or more stabilizers and / or one or more surfactants can also be used. Suitable surfactants include the various silicone surfactants, preferably those which are block copolymers of a polysiloxane and a polyoxyalkylene, as described in U.S. Patent No. 3,629,308. Known interleavers can also be used in the process of the invention to modify the properties of polyurethane foam. These interleavers are used in quantities well known to the skilled person. In addition to the materials mentioned above, you can Also use in the process of the present invention any number of a variety of additives conventionally used in the production of polyurethane foams, such as, for example, fire retardants, defoamers, antioxidants, mold release agents, dyes, pigments and loads. These additives are used in the quantities known to the skilled person. The following designations, the following symbols, terms and abbreviations, are used in the examples that follow. CP-3040 is a polyol initiated with glycerin, which has a hydroxyl number on the scale of 54 to 59 and an average molecular weight of 3,000 and a viscosity at 25 ° C of 490 cps, obtainable from The Dow Chemical Company under the trademark VORANOL CP-3040. CP-4735 is a polyol initiated with glycerin, having a hydroxyl number in the range of 33 to 38 and an average molecular weight of 4,700 and viscosity at 25 ° C of 820 cps, obtainable from The Dow Chemical Company under the trademark VORANOL CP -4735. DNC-635.04 is a polyol initiated with sorbitol, having a hydroxyl number of 30 and an average molecular weight of 7,000. VTMSP precursor stabilizer modified with vinyltrimethoxysilane, prepared according to example 3 of EP-0 162589 B1. Trigonox 42S is a free radical polymerization initiator, containing terbutyl peroxy-3,5,5-trimethylhexanoate, sold by Akzo Chemie under the brand name Trigonox 42S.

Trigonox 121 is a free radical polymerization initiator containing teramyl peroxy-2-ethylhexanoate, sold by Akzo Chemie under the trademark TRIGONOX 121 Trigonox 27 is a free radical polymerization initiator containing terbutyl peroxydiethyl acetate, sold by Akzo Chemie under The brand TRIGONOX 27 Vazo 67 is a polymerization catalyst of 2,2'-azobis (2-methylbutanonitrile), prepared by DuPont de Nemours and Co. Dabco 33LV a 33 percent solution of triethylene diamine in dipropylene glycol, sold by Air Products and Chemicals Inc., under the brand name DABCO 33LV. Niax A-107 is a block-form block acid formula of 70% bis (2-dimethylaminoethyl) ester / 30% dipropylene glycol amine, obtainable from Union Carbide Corp., under the trademark NIAX A-107 DEOA is diethanolamine DC-5164 is a silicone surfactant, sold by Dow Corning Corporation NDM is n-dodecyl mercaptan IPA is isopropanol TDI-80 is an 80:20 mixture of the 2,4- and 2,6-toluene diisocyanate isomers, sold by The Dow Chemical Company under the brand VORANATE T80 index is the reason for the number of groups &SSbS. The amount of reactive isocyanate in the reaction mixture, divided by the amount of active hydrogen groups in the reaction mixture, multiplied by 100. 5 STN is styrene. CAN is acrylonitrile Preformed stabilizer is a preformed stabilizer prepared according to example 1 of PCT / EP95 / 04149 (Fogg). The properties of the polymer polyol composition and polyurethane foams given in the examples that follow are determined according to the following test methods: Air flow (l / sec) It is measured according to the method of ISO 7231 test (on the AMSCOR foam porosity instrument) Density is measured according to test method DIN 53420. CFD 40% (kPa) is the deflection by compression force, determined in accordance with DIN 53577. IFD 25% (N) is the 25% deflection by indentation force, determined in accordance with ASTM D-3574, test B1 and B2. IFD 40% (N) is the deflection at 40% by force of 25 indentation, determined in accordance with ASTM D-3574, test B1 and B2. IFD 65% (N) is the 65% deflection by indentation force, determined in accordance with ASTM D-3574, tests B1 and B2. SAG factor is 65% deflection by indentation force, divided by 25% deflection by indentation force. Tensile strength (kPa) is determined in accordance with ASTM D-3574. Elongation (%) is determined in accordance with ASTM D-3574, test E. Tear strength (N / m) is determined in accordance with ASTM D-3574. Possibility of filter is the filtration impediment determined by diluting one part by weight of sample (eg, 470 g) of polymer polyol with two parts by weight of anhydrous isopropanol (eg, 960 g) to eliminate any limitations imposed by viscosity , and using a fixed amount of material in relation to the fixed cross-sectional area of the sieve, so that all the polymer polyol solution and isopropanol pass through gravity through a 150-mesh or 700-mesh sieve. The 150 mesh screen has a square mesh, with an average mesh opening of 105 microns, and is a "Tyler Norma" 150 square mesh screen. The 700 mesh screen is made with a mixed twill fabric. The actual sieve used had a nominal aperture of 30 microns. The amount of sample passing through the screen within 3000 seconds is reported as a percentage, a value of 100 percent indicates that more than 99 weight percent passed through the screen. Viscosity is measured using a Brookfield viscometer, spindle # LVVT3, speed 12, according to ASTM D-4874. The following examples are given to illustrate the invention and should not be construed as limiting it in any way. Unless stated otherwise, all parts and percentages are given by weight.

EXAMPLES 1 TO 11 PREPARATION OF POLYMER POLYOL COMPOSITION The polymer polyol of the present invention was prepared using a continuous polymerization system, which uses a tank reactor equipped with deflectors and impeller. In the examples, The polymeric polyol composition was fed to the reactor continuously by the feed components after passing through an in-line mixer to ensure complete mixing of the feed components before the feed. enter the reactor. The contents of the reactor were mixed well. The internal temperature of the reactor was controlled within 1 ° C. The product was flowed out from the upper end of the reactor and raced a second non-stirred reactor, also controlled within 1 ° C. The product from the second reactor was then flowed out continuously through a back pressure regulator that had been adjusted to approximately 310 kPa of pressure in both reactors. The crude polymer polyol product was then flowed through a cooler into a collection vessel. The weight percentage of the polymer polyol was determined from the analysis of the amount of unreacted monomers present in the crude product. The crude product was removed in vacuo to remove the volatiles, before the test. All polymer polyols produced stable compositions. The polymer polyol feed compositions, the preparation conditions and the polymer polyol properties are shown in the following table 1. » w »» > . «N & fc ... migija í £ g ** ^ g ^ sKáÉ & Sjj ^ á ^^^ TABLE 1 TABLE 1 (CONTINUED) S ^^^ j ^^^^^^^^^? ^ J ^^ HJH ^^^ X EXAMPLES 12 TO 13 PREPARATION OF POLYURETHANE FOAMS Polyurethane foams were produced by pouring 5 foam formulations shown in the following table 3, in a 4-hole, aluminum 16-liter vent mold (40 x 40 x 10 cm). ), heated to a temperature of approximately 60 ° C, using an Admiral DHF-I high pressure pouring machine and Krauss Maffei MK12-12 / 16-UL-2K Dx mixing head, which allows to raise the foam and cure it. The time of demolding the foam was 5 minutes. The Klüber 918 / 9K moover agent (sold by Klüber AG) was used as the mold loosening agent. The pressure of the polyol component / isocyanate component tanks was 3 bar. Both the polyol component is supplied as the isocyanate components at approximately 150 bar of pressure. The polymer polyol used in the foam formulation shown in Table 2 is the polymer polyol produced in Examples 9 and 10 herein. They are shown in table 2 that follows foam formulations and foam properties. As can be seen from table 2 below, the polyurethane foams prepared in example 13, using the polymer polyol of the present invention exhibit high load bearing characteristics, with respect to those of example 12, without any significant loss in the other characteristics. íjij ¿jMámá ^^ ^ í? iaMUUi ?? íl ^^^^ ßm TABLE 3 ^, i ^, a ^ .. = ^., ^^ Makumi ama

Claims (5)

1. CLAIMS 1.- A polymer polyol composition, characterized in that it has a polymer content of 20 to 60 weight percent, based on the total weight; a Brookfield viscosity that is equal to or less than (a e [(0 051> <b)])? where "a" is the viscosity of the carrier polyol and "b" is [(fraction by weight of solids) (100)], and product stability, so that essentially 100% passes through a 150 mesh screen and up to 100% passes through a 700 mesh sieve, produced by polymerization of the free radical of the composition, comprising: (a) a polyol (b) a preformed stabilizer, (c) at least one ethylenically unsaturated monomer, (d) a free radical polymerization initiator, comprising at least a first active peroxide; said active peroxide being present in an amount equal to or less than 0.6 weight percent, based on the total monomer; and (e) a chain transfer agent.
2. 2. A polymer polyol composition according to claim 1, further characterized in that the free radical polymerization initiator additionally comprises an additional, active peroxide initiator, different from the first active peroxide initiator, and having a half life greater than that of the first active peroxide.
3. 3. A polymer polyol composition according to claim 1, further characterized in that the free radical polymerization initiator further comprises an azo compound.
4. 4. A polymer polyol composition according to claim 1, claim 2 or claim 3, further characterized in that the free radical polymerization initiator of first active peroxide is selected from the group consisting of terbutylperoxydiethyl acetate, peroctoate of terbutyl, tertbutyl peroxyisobutyrate, tert-butyl peroxy-3,5,5-trimethylhexanoate, tertbutyl peroxybenzoate, tertbutyl peroxypivalate, teramyl peroxypivalate and tert-butyl peroxy-2-ethylhexanoate. 5. A polymer polyol composition according to claim 4, further characterized in that the chain transfer agent is n-dodecyl mercaptan. 6. A process for the preparation of the polymer polyol composition, characterized in that it comprises providing a composition comprising: (a) a polyol, (b) a preformed stabilizer, (c) at least one ethylenically unsaturated monomer, ( d) a free radical polymerization initiator, comprising at least a first active peroxide; the first active peroxide being present in an amount equal to or less than 0.6 percent by weight, based on the total monomer content; and (e) a chain transfer agent in a reaction zone maintained at a temperature sufficient to initiate a free radical polymerization, and under sufficient pressure to maintain only liquid phases in the reaction zone, for a sufficient period of time to reacting essentially at least the major portion of the at least one ethylenically unsaturated monomer, and recovering the polymer polyol. 7. A process according to claim 6, further characterized in that the reaction zone is maintained at a temperature of 120 ° C to 140 ° C. 8. A composition for the preparation of a polyurethane foam, where polymer polyol, a polyurethane catalyst, an organic polyisocyanate, a surfactant and a blowing agent are used; characterized in that the polymer polyol comprises a polymer polyol as claimed in any of claims 1 to 5. 9. A polyurethane foam, prepared from a composition as claimed in claim 8. 10.- A foam of polyurethane prepared from a polymer polyol composition as claimed in any of claims 1 to
5. 5. "-" -'- '- "• ^» - "" "- -« - a *** "*' - ^« - ^ -. ^. | RESU M EN Polyol polyols and a process for their production are described. The process requires the selection of specific free radical polymerization initiators, and their specific amounts, to produce a polymer polyol having the desired properties, including Brookfield viscosity equal to or less than (a et (or o 5i) (b )] ^ (jo nc | e «a» is the viscosity of the carrier polyol and "b" is [(fraction by weight of solids) (100)].