MXPA01002711A - Preblend and expansion of polymeric microspheres - Google Patents

Abstract

The present invention relates to a process for producing a dispersion of polymeric microspheres in a polyol comprising expanding 1 to 70%by weight of polymeric beads in a polyol with a twin screw extruder to simultaneously mix and expand the beads to create a uniform dispersion of the microspheres in the polyol such that the wetting of the microspheres by the polyol is maximized.

Description

PREMEZCLA AND EXPANSION OF POLYMERIC MICROSPHERES BACKGROUND OF THE INVENTION Rigid foams made with filled polyols are known. Such foams are typically produced by reaction of a polyisocyanate with an isocyanate-reactive material, such as polyol, in the presence of an insufflating agent.

In recent years, substantial increases in the cost of basic materials used to make foam have encouraged the development and use of filler materials to reduce the amount of basic materials used and the weight of finished materials. One of the filler materials and the insulating materials su-geridos uses hollow microspheres. High loads of inert and / or inorganic fillers pose several limitations on the conventional rigid flexible foams processing methods: 1) high intrinsic viscosity, 2) it is difficult to completely soak particles and 3) unstable dispersion results in agglomeration and / or deposition. High filler loads, however, offer some very interesting potential benefits: 1) they are cheap, 2) they offer the ability to encapsulate additives, ^^ tógsjá ^ 3) improve the resistance to compression and 4) alter the capacity of energy absorption. The use of hollow polymeric microspheres as filler in polyol for stock of rigid boards is described in the USA. Serial No. 08 / 909,447. Due to the extremely high viscosities when using fillers, the polyol levels that contain significant levels of these fillers can not be processed with conventional equipment for mixing and dosing board stock.

SUMMARY OF THE INVENTION The present invention relates to a process for producing a dispersion of polymeric microspheres in a polyol, consisting of expanding 1 to 70% by weight of polymer beads in a polyol with a double-screw extruder for mixing and expanding. simultaneously the beads and create a uniform dispersion of the microspheres in the polyol, in such a way that the wetting of the microspheres by the polyol is maximized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a micrograph of Sample No. 10, as discussed in the examples, where 50 percent by weight of ^^ gg ^ y ^^ i ^^^ the beads are expanded at a helix speed of 300 rpm and at drum temperatures of 100 ° C. FIG. 2 is a micrograph of Sample No. 1, as indicated in the examples, where 50 weight percent of the beads are expanded at a helix speed of 300 rpm and at a drum temperature of 25 ° C. FIG. 3 is a micrograph of Sample No. 5, as indicated in the examples, where 50 weight percent of the beads are expanded at a helix speed of 300 rpm and at a drum temperature of 155 ° C. FIG. 4 is a micrograph of Sample No. 6, as indicated in the examples, where 50 weight percent of the beads are expanded at a helix speed of 100 rpm and at a drum temperature of 100 ° C. FIG. 5 is a micrograph of Sample No. 8, as indicated in the examples, where 50 weight percent of the beads are expanded at a helix speed of 400 rpm and at a drum temperature of 100 ° C. FIG. 6 is a micrograph of Sample No. 9, as indicated in the examples, where 50 weight percent of the beads are expanded at a helix speed of 500 rpm and at a drum temperature of 100 ° C. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for the continuous processing of filled polyols containing microspheres for PUR / PIR foam. The term "PUR / PIR foam" refers to a polyurethane and / or isocyanurate foam produced by generation of gas bubbles during the reaction of the polymer matrix. In the process of the present invention, an extruder is used to mix and expand the polymer beads in a polyol in microspheres, where a uniform dispersion of microspheres in the polyol is produced. The dispersion is then mixed with other ingredients, such as an isocyanate, to produce a PUR / PIR foam. Preferably, a double helix extruder is used. Such technology, for example, is described in US Pat. No. 5,424,014. The dispersion contains between 1 and 70 weight percent polymeric beads and, preferably, between 10 and 60 weight percent polymeric beads. The hollow microspheres used herein are known. The microspheres are produced from polymeric beads formed by a polymer that melts below the decomposition temperature of the polyol of the present invention. Pearls that can be purchased commercially include WU-551 or Expancel DU551, from Expancel Inc., and Dualite ^ j ^ = - j __ ^ »a_- M6032AE, by Pierce & Stevens Corporation. The Expancel and Dualite type beads are both expandable to hollow microspheres consisting of a thin shell of a copolymer of polyvinyl chloride, polystyrene, vinylidene chloride 5 and / or acrylonitrile. The interior of the Microspheres of Expancel and Pierce & Stevens typically contains a volatile hydrocarbon, which contains isobutane, isopentane or cyclopentane, but could also be made from usual low-boiling solvents, if necessary. More preferably, the low-boiling hydrocarbons are isomers of butane or pentane or a combination of butane and pentane. In the example of a polymeric shell, when the pearl is heated, the polymer gradually softens and the volatile hydrocarbon evaporates, thus expanding the pearls to microspheres In a preferred embodiment, the crust of the microsphere is made of polyvinyl chloride, polystyrene, polyacrylonitrile or mixtures thereof. More preferably, the microsphere is made of a polyvinyl chloride / acrylonitrile copolymer. 20 It is typical of the available microspheres that a given sample contains a range of sizes. The microspheres provided in this invention are hollow spheres with an average diameter of between 80 and 200 microns, preferably of ^ g ^^^^^^^^^^^^ j ^^^^^^ fe ^^^^^^^^^ j ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ mieras The addition of the amount of beads is such that the percentage by weight of the beads with respect to the product of 5 puma is from 1 to 70 weight percent of the hollow microspheres. Preferably, the weight percentage of the microspheres is from 10 to 60 weight percent and, more preferably, from 20 to 60 weight percent. The foam of the present invention is a polyurethane foam or closed cell polyisocyanurate foam, such that the diameter of the cells of the foam is in a range of 0.01 to 60 microns. The production of the rigid foams of the present invention based on isocyanates is known per se and is disclosed, for example, in the German Patent Application Publications 1,694,142, 1,694,215 and 1,720,768, as well as in Kunststoff-Handbuch [Plastics Handbook], Volume VII, Polyoyethane, edited by Vieweg and Hochtlen, Cari Hanser Verlag, Munich, 1966, and in the new edition of this volume, edited by 20 G. Oertel, Carl Hanser Verlag, Munich , Vienna, 1983. These foams are mainly those consisting of urethane and / or isocyanurate and / or allophanate and / or uretdio- na and / or urea and / or carbodiimide. The following can be _____________ g ^^^^ ^^ S ^^^ g ^^^^^^^ L ^^ j ^ s ^^^^^^ ees for producing rigid foams based on isocyanates, using the microspheres according to the present invention. a) As starting components, aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates, such as those described, for example, by W. Siefken in Justus Liebigs Annalen der Chemie, 562, p. 75-136, for example those of formula Q (NCO) n, wherein n represents 2-4, preferably 2-3, and Q represents an aliphatic hydrocarbon radical of 2-18, preferably of 6-10 carbon atoms; a hydroalkylaminoaliphatic radical of 4-15, preferably 5-10 carbon atoms; an aromatic hydrocarbon radical of 6-15, preferably 6-13 carbon atoms; or an araliphatic hydrocarbon radical of 8-15, preferably 8-13 carbon atoms, for example polyisocyanates such as those described in DE-OS 2,832,253, p. 10-11. Particularly preferred are those polyisocyanates which are technically easily accessible, for example the 2,4- and 2,6-toluylene diisocyanate, as well as any mixture of these isomers ("DIT"); polyphenyl-limethylene-polyisocyanates, such as those obtained by a condensation of aniline-formaldehyde and subsequent treatment with phosgene ("crude DIM"), and polyisocyanates containing carbodiimide groups, urethane groups, allophanate groups, isocyanurate groups, urea groups or biuret groups ("modified polyisocyanates"), especially those modified polyisocyanates derived from 2,4- and / or 2,6- diisocyanate. toluene and 4,4'- and / or 2,4'-diphenylmethane diisocyanate. b) The starting components can also be compounds of a molecular weight usually from 400 to 10,000, which contain at least two hydrogen atoms reactive toward the isocyanates. These include, in addition to compounds containing amino, thio or carboxyl groups, preferably compounds containing hydroxyl groups, in particular compounds containing from 2 to 8 hydroxyl groups, especially those with a molecular weight of 1,000 to 6,000, preferably 2,000. to 6,000, for example polyethers and polyesters, as well as polycarbonates and polyester amides containing at least 2, usually 2 to 8, preferably 2 to 6, hydroxyl groups; These compounds are known per se for the preparation of homogeneous and cellular polyurethanes and are described, for example, in DE-OS 2,832,253, p. 11-18. Preferably, any typical polyalcohol can be used, insofar as there are no contaminants or additives that can dissolve, char or in some other way attack the polymer beads and thus alter their expansion to microspheres. c) Where appropriate, compounds containing at least two hydrogen atoms reactive towards 5 isocyanates and of a molecular weight of 32 to 399 can be used as other starting components. Furthermore, in this case, it is understood that the compounds containing hydroxyl groups and / or amino groups and / or thiol groups and / or carboxyl groups, preferably compounds containing hydroxyl groups and / or amino groups, are those that are used as chain extenders or cross-linking agents. These compounds usually have from 2 to 8, preferably from 2 to 4, hydrogen atoms reactive towards isocyanates. Appropriate examples are described in DE-OS 2,832,253, pp. 19-20. D) The blowing agents that can be used in the process of the present invention include water and / or easily volatile inorganic or organic substances and other auxiliary volatile blowing agents typically used for insufflating PUR / PIR foams. The insufflating agents organic include acetone; ethyl acetate; halogen-substituted alkanes, such as methylene chloride, chloroform, ethylidene chloride, vinylidene chloride, monofluorotrichloromethane, chlorodifluoromethane, dichlorodifluoromethane, g ^ ^^^^^^^^^ _ ^^ _ ^^ ___ ^^^^^^^^^^^^ __ ^^^ _____________________________ ^^^^^^^^^^ rf ^^^^ ^^^^^^ i chlorodifluoroethane, dichlorotrifluoroethane; also butane, I * - # hexane, heptane or diethyl ether. Specific examples of such insufflating agents include: 1,1,1,4,4,4-hexafluorobutane (HFC-356); tetrafluoroethanes, such as 1, 1, 1, 2 -tetrafluoroethane (HFC-134a); pentafluoropropanes, such as 1, 1, 2, 2, 3-pentafluoropropane (HFC-245ca), 1, 1, 2, 3, 3-pentafluoropropane (HFC-245ea), 1,1,1,2,3-pentafluoropropane (HFC-245eb) and 1,1,1,3,3-pentafluoropropane (HFC-245fa); hexafluoropropanes, such as 1,1,2,2,3,3-hexafluoropropane (HFC-236ca), 1, 1, 2, 2, 3-hexafluoropropane (HFC-236cb), 1, 1, 1, 2, 3, 3-hexafluoropropane (HFC-236ea), 1, 1, 1, 3, 3, 3-hexafluoropro-pano (HFC-236fa); the pentafluorobutanes, such as 1,1,1,3,3-pentafluorobutane (HFC-365), and the difluoroethanes, such as 1,1-difluoroethane (HFC-152a). The inorganic blowing agents are, for example, air, C02 or N20. An insufflating effect can also be obtained by adding compounds that decompose at temperatures above room temperature by emitting gases, such as azodicarbonamide or azoisobutyronitrile. Other examples of insufflating agents can be found in Kunststoff-Handbuch, Volume VII, of Vie Eg and Hochtlen, Cari-Hanser-Verlag, Munich, 1966, on pages 108 and 109, 453 to 455 and 507 to 510. e) When appropriate, can be used at the same other auxiliary agents and additives, such as: water and / or other highly volatile organic substances as propellants; additional catalysts of the type known per se in amounts of up to 10% by weight, based on component b); surfactant additives, such as emulsifiers and foam stabilizers, and reaction retarders, for example acidic substances such as hydrochloric acid or organic acid halides, also cell regulators of the type known per se, such as paraffins or fatty alcohols or dimethylpolysiloxanes , as well as pigments or dyes and other flame retardants of the type known per se, for example tricresyl phosphate, also stabilizers against the effect of aging and weathering, plasticizers and fungistatics and bacteriostats, as well as fillers, such as barium sulfate, diatomaceous earth, carbon black or white from Spain. Other examples of surfactant additives are described, ^^^ g ^ g < foam stabilizers, cell regulators, reaction retarders, stabilizers, flame retardants, plasticizers, colorants, fillers, fungistatics and bacteriostats which can be used at the same time, if appropriate, as well as details concerning the use and action of these additives in Kunststoff-Handbuch [Plastics Handbook], Volume VII, edited by Vieweg and Hochtlen, Cari Hanser Verlag, Munich, 1966, for example on pages 103-113. Isocyanate-based foams can be prepared in a manner known per se. The preparation of polyurethane plastics can be carried out, for example, as follows: the reagents are caused to react by the single-step process known per se, the pre-filler process or the semipre-polymer process, making frequent use of plant machinery, for example that described in US Pat. 2,764,565. The details concerning the processing plant, which are equally important according to the invention, are described in Kunststoff-Handbuch, Volume 20 VII, edited by Vieweg and Hochtlen, Cari Hanser Verlag, Munich, 1966, for example on pages 121-205. Due to the inherently high viscosities of the formulations containing high microsphere charges, it is necessary to consider MÜÜ ^ ii_ £ ___? ¡_______________? tfMa_a_d_J_______M____? dl _____ l ____ Í ________ l_______ additional processing deeds. A commercial solution is the use of an extruder to mix and dose the suspension containing the microspheres. Said technology is described, for example, in U.S. Pat. No. 5,424,014. The design and speed of the propeller, the performance and the temperature of the extruder drum of the present invention are adjusted in such a way that the temperature of the polyol is maintained between a T? Nicia? and a Tmax for the chosen polymer of the bead. TiniC? A? it is defined as the temperature at which the expansion of the bead to a microsphere begins and Tmax is defined as the upper limit to prevent the bursting of the microsphere. Such temperatures are generally known in the art. It is seen that the Tmax is generally in the range of 110 to 200 degrees C. The products that can be obtained according to the present invention can be used, for example, as energy absorbing foams, as insulation for household appliances, as laminated boards. for external wall elements, such as insulating roofing boards, as interior walls, as insulated doors, etc. EXAMPLES The following examples were processed using a double helix extruder ZSK30 from erner-Pfleiderer GmbH. The design of the propeller was selected based on the viscosity and performance of the following examples. Consequently, if other viscosities or 5 performances were required, the design would be changed / optimized. The polyalcohol used was Stepanpol 2352 (Stepan Chemical) and is a polyester alcohol based on italic anhydride, which is typically used in the production of PUR / PIR foams. The polymeric beads used were U-551, from Expancel Corlo poration, and are composed of polyvinyl chloride / acrylonitrile copolymer swollen with isobutane. These beads were chosen for their low cost and appropriate melting point of approximately 100 degrees Celsius. Two measures were used to determine the degree of expansion of polymer beads to microspheres. The density of the resulting dispersion was measured using a volume displacement method with a pincometer. A reduction in dispersion density would be an indication of successful expansion. Visual confirmation of the expansion was also obtained using electronic micrographs.

Example 1 A dispersion of 50 weight percent of d_M__É ___ i polymeric beads WU 551 at a speed of 300 rpm and the temperature of the drum was varied: Example 2 A dispersion of 50 weight percent WU 551 polymer beads was processed at a drum temperature of 100 ° C and the speed of the screw was varied: Example 3 w «m» > .- ___ a * ___ l__a _______- to < fa__ -, - aaaJS, • > - * «___-.

At a helix speed of 300 rpm and a drum temperature of 100 ° C, the weight percentage of WU 551 polymer beads was varied in a dispersion: Examples 1 and 2 clearly show a drum temperature and an optimum helix speed for the 50 percent dispersion, in this case Sample # 10, shown in Fig. 1. If the temperature is too low. Sample # 1, the beads do not expand and the density of the dispersion is the theoretical limit, as shown in Fig. 2. At higher temperatures, the microspheres are overexpanded and melted, for example Sample # 5, such as it can be seen in Fig. 3. The total energy for the expansion, however, does not proceed just from the temperature of the drum, but additional shear energy is introduced into the system from the rotation of the double helix. At 100 ° C, if the speed of the propeller and, therefore, the shear energy, is low, very little expansion of the beads occurs; see the Sample ^^^^^^ g ^^^^^^^^^^^^^^ j ^^^^^^ ^ g ^ j ^^^^ • * - * - - * > ** & * < **** # 6, as seen in Fig. 4. If the speed of the helix is too high, the microspheres begin to collapse, Sample # 8, as seen in Fig. 5, and eventually melt , Sample # 9, as seen in Fig. 6. It is clear, from Example 3, that these optimum conditions will change as the charge of the polymer beads increases. Certainly, these optimum conditions would also logically need to be redefined for different drum diameters, drum configurations, polyalcohol type, polymer type and desired total throughput. Said reoptimization must consider the temperature of the drum, the speed of the helix and the interaction of the temperature, the design of the helix and the speed to ensure the filling and the complete in situ expansion of the beads to microspheres. While particular embodiments of this invention have been described herein for illustrative purposes, it will be apparent to those skilled in the art that numerous variations can be made in detail without departing from the invention as described in the appended claims. ^^^^

Claims (8)

Claims

1. A process for producing a dispersion of polymeric microspheres in a polyol, consisting of expanding 1 to 70% by weight of polymer beads in said polyol with a double-helix extruder, to simultaneously mix and expand the beads and create a dispersion uniformly said microspheres in said polyol, in such a way that the wetting of said microspheres by said polyol is maximized.

2. A process according to Claim 1, wherein said microspheres are produced from said polymer beads consisting of a polymer melting below the decomposition temperature of said polyol.

3. A process according to Claim 2, wherein said polymer is selected from the group consisting of polyvinyl chloride, polyvinylidene chloride, polystyrene, polyacrylonitrile or mixtures thereof.

4. A process according to Claim 3, wherein said polymer is polyvinyl chloride / acrylonitrile copolymer.

5. A process according to Claim 2, wherein said microsphere contains a low boiling hydrocarbon as an insufflating agent.

6. A process according to Claim 5, wherein said low boiling hydrocarbon is selected from the group consisting of isomers of butane or pentane or both butane and pentane.

7. A process according to Claim 1, wherein said dispersion contains between 10 and 60% by weight of polymeric beads.

8. A process according to Claim 7, wherein said dispersion contains between 20 and 50% by weight of polymeric beads.