FR2501215A1 - MANUFACTURE OF RIGID POLYURETHANE FOAMS FROM POLYAROMATIC POLYHYDROXYL COMPOUNDS - Google Patents

Abstract

THE INVENTION CONCERNS THE MANUFACTURE OF RIGID FOAMS BASED ON POLYURETHANES. THE REACTIVE COMPOSITIONS INCLUDE A POLYETHERPOLYOL, A POLYISOCYANATE, AN EXPANSION AGENT AND, IN ADDITION, A POLYHYDROXYL POLYAROMATIC COMPOUND. FOAM BODIES OBTAINED FROM SUCH COMPOSITIONS ARE PARTICULARLY INTENDED FOR APPLICATIONS REQUIRING GREATER RESISTANCE TO COMPRESSION EFFORTS.

Description

MANUFACTURE OF RIGID POLYURETHANE FOAMS

  FROM POLYAROMATIC POLYHYDROXYL COMPOUNDS

  The subject of the invention is a process for manufacturing rigid polyurethane foam bodies having properties

mechanical improvements.

  It is known to manufacture polyurethane rigid foam bodies from reactive polyurethane compositions.

  containing one or more polyether polyols, one or more poly-

  organic isocyanates as well as various additives such as

  lysers, blowing agents, flame retardants and tensio-

  assets. The polyether polyols commonly used in this application

  are composed of polyaddition compounds of

  on polyhydroxy compounds containing at least three hydroxyl groups per molecule, such as sucrose, their

  hydroxyl number is most often of the order of 350 to 500.

  The rigid polyurethane foam bodies thus obtained

   J5 have satisfactory mechanical properties in applications

  where they are not subject to relatively large compression efforts. However, in certain applications such as the insulation of floors of industrial buildings or refrigerated trucks it has been found desirable to obtain polyurethane foam bodies having increased resistance to

compression efforts.

  It is known to introduce in the polyurethane reactive compositions mentioned above, reagents consisting of

  aliphatic compounds with a molecular weight of less than 300

  as many molecules per molecule hydroxyl and / or amine. The compounds of this type most commonly used are chosen from glycerine, sorbitol, ethylene glycol, triethanolamine, ethylenediamine, diethylenetriamine, or from compounds

  by polyaddition of propylene oxide and / or ethylene oxide

  It binds to the above hydroxylated and / or aminated compounds. These

  In at least one embodiment, the hydroxyl values of which are commonly between 700 and 1800 are used in proportions of the order of 5 to 10% by weight of all the compounds which react with organic polyisocyanates. These repellents lead to rigid foam bodies of

  polyurethane which has a slightly higher compressive strength

  However, they have various drawbacks: they lead to a greatly increased consumption of organic polyisocyanates. Hydroxylated reagents are by their nature very reactive towards isocyanate groups and amine reactifiers strongly catalyze

  the formation of polyurethanes; therefore, the reaction compositions

  Polyurethane fibers containing these reagents can easily lead to picking phenomena that are too fast, resulting in poor filling of the volumes to be filled or stretching.

  at the end of the expansion which leads to a clear weakening of the resistance

  mechanical direction in directions perpendicular to the direction of expansion. This weakening is likely to cause the

  spontaneous deformation of these foams.

  It has now been found that the addition of

  polyhydroxy polyaromatic compounds, such as dihydroxydiphenylalkyl

  nes, makes it possible to obtain rigid polyurethane foam bodies

  having improved mechanical properties, without having to

  the disadvantages mentioned above. It has, on the contrary, been observed that the implementation of the polyurethane reactive compositions according to the invention is facilitated, since the reactions which lead to the formation of the foams are more gradual and the

  filling of the molds is improved. In addition, it was found that

  sence of so-called "grid-to-core" phenomena and cracking even in large bodies (eg 3 m x 1 m x

  lm), and even when the bodies have a density, relative to

  high (eg greater than 60 kg / m3).

  The subject of the invention is therefore a process for manufacturing rigid polyurethane foam bodies from a reactive polyurethane composition comprising polyether polyols, expansion agents and organic polyisocyanates, these compositions also containing from 3 to 100% by weight and preferably from 5 to% by weight, based on polyether-polyols, of one or more

  polyhydroxy polyaromatic compounds.

  The term "polyhydroxy polyaromatic compound" refers to a compound having at least two aromatic rings and two hydroxyl groups. In the formula of these compounds, aromatic rings can be condensed, or linked by a single valency

  or by a radical free of reactive sites vis-à-vis the constituents

  of the composition, for example an aliphatic radical having

from 1 to 3 carbon atoms.

  The polyhydroxy polyaromatic compounds used in

  preferably comprise from two to five aromatic rings and possess

  at least one hydroxyl group per aromatic ring, these hydroxyl groups being able to be attached to the aromatic rings or connected thereto by aliphatic radicals. Compounds

  Preferred polyaromatic polyhydroxy compounds are polyhydroxy

  droxypolyphenylalkanes, such as bis (p.hydroxyphenyl) methane or bis (p.hydroxyphenyl) -2,2-propane. Such compounds can be

  obtained by condensation of two molecules of phenol on a molecule

  formaldehyde or isopropanone.

  The polyether polyols used are chosen from polyether polyols used in the manufacture of foams.

  rigid polyurethane. These polyether polyols preferably have

  hydroxyl value between 300 and 1000, and preferably

  between 350 and 500. They are prepared in a known manner by

  o polyaddition of propylene oxide and possibly of ethylene oxide

  binds to mobile hydrogen compounds such as

  polyols, oses, glucosides, alkanolamines or poly-

  amides, these compounds may have, depending on the case, 3 to 8 hydrogen atoms capable of reacting with the alkylene oxides. The polyaddition is most often carried out in the presence of a compound

  alkali, such as potassium hydroxide, until the amount

  desired content of the alkylene oxide (s) is added. The composition

  The alkaline solution is then removed, for example, by neutralization of

  this compound by means of an acid and then by filtration of the salt formed.

  When the polyether polyols are prepared from ethylene oxide and propylene oxide, these alkylene oxides can be fixed separately or as a mixture to the mobile hydrogen atom compounds, or alternatively between these two modes of fixation. The chosen mode of attachment influences the responsiveness of

  3 polyether polyols with respect to polyisocyanates.

  The organic polyisocyanates are advantageously chosen

  among the aromatic polyisocyanates, such as tolylene

  diisocyanate commonly referred to as "TDI" or diphenylmethane 4-4 '

  diisocyanate, commonly referred to as "MDI". These organic polyisocyanates

  are preferably selected from aromatic polyisocyanates

  such as crude TDIs, which are obtained by the reaction of phosgene with a crude tolylenediamine containing various isomers and condensed amines, or the crude MDIs which result from the condensation of phosgene with the unpurified product of the reaction between aniline and formaldehyde. The organic polyisocyanates are used in amounts such that the isocyanate index A is between 1.00 and 3.50 and preferably between 1.05 and 1.15. The isocyaate index, mentioned above, is equal to the ratio of the number of isocyanate groups of the polyisocyanates

  organic to that of mobile hydrogen atoms of polyethers-

  polyols, polyhydroxy polyaromatic compounds and, where appropriate,

  appropriate, water used as blowing agent.

  The blowing agents are volatile organic compounds such as monofluorotrichloromethane or methylene chloride. These volatile organic compounds can be

  0 used in amounts up to 30% by weight of the polyesters

  ethers polyols. It is also possible to use, as a complementary expansion agent, small quantities of water, of the order of, for example, 0.5% by weight relative to all the

  polyether polyols and polyhydroxy polyaromatic compounds.

  When the foaming mixture contains polyethers

  Polyols prepared from amine compounds, it is generally not necessary to implement catalysts, because these polyether polyols have a high reactivity vis-à-vis the organic polyisocyanates. If the reactivity of the foaming mixture with respect to the polyisocyanates is insufficient, it may be useful to use catalysts, in particular amine catalysts, especially tertiary amines such as triethylenediamine, dimethylethanolamine, triethylamine, triethanolamine,

  dimethylcyclohexylamine or mixtures of these amines. These catalysts

  They are used in amounts generally less than 3% by weight relative to the total of the polyhydroxy compounds. Although this is not essential, it is possible to combine these o0121S '

  amine catalysts with metal catalysts such as oc-

  stannous toate, dibutyltin dilaurate or zinc octoate, in particular to increase the reaction rate of the constituents

of the reaction mixture.

  It is generally useful to also introduce into the foaming mixture emulsifiers, such as silicone emulsifiers resulting from the condensation of alkylene oxides with silanes or siloxanes. These emulgators are generally used in proportions of between 0.3 and 1% by weight relative to

At 0 foaming mixture.

  It is possible, to increase the properties of self-explanatory

  the polyurethane rigid foam bodies obtained, to add in the reactive compositions flame retardant compounds that are inert or reactive with respect to the organic polyisocyanates, such as

  for example tris-chloroethylphosphate, tris-chloropropylphosphoric acid

  phate, tri (dibromopropyl) phosphate, antimony oxide, red phosphorus or phosphorus or phosphochlorine compounds such as products sold commercially as Phosgard

  C 22 R, Fyrol 6, Napiol R 104. These flame retardant compounds are generally

  implemented in proportions between 2 and 7 Z in

  weight relative to the reactive compositions.

  The method of the invention can be implemented by

  mixture of the constituents of the polyurethane reactive composition.

  thane, the organic polyisocyanates being preferably introduced last. It is convenient to use the polyhydroxy polyaromatic compounds in solution, for example in polyether polyols. Solutions of polyhydroxy compounds in polyether polyols are also one of the objects of the invention.

  The process of the invention can be carried out industrially

  molding by means of a multi-circuit machine leading to a mixing head, one of the circuits

  the separate introduction of the polyisocyanates into the mixing head.

  The constituents of the reactive compositions are generally used at a temperature of between 20 and 30 ° C. The mixture

  foaming is poured into a mold which is itself at a temperature

  the size determined according to the molding conditions and between 70 C and, in quantities such that the average density of the molded part is between 30 and 800 kg / m3 and preferably between 30 and 150 kg / m3. The mold is then closed for a few

  minutes, to allow the foam to expand and polymerize

riser.

  The moldings obtained by the process of the invention

  They have interesting mechanical properties, as the following examples show. At a substantially equal density, the molded parts have in particular a re-istance Ao compression called "parallel" significantly increased, a compression resistance called "perpendicular" improved and stability

dimensional best.

  EXAMPLE 1 AND COMPARATIVE EXAMPLES C and C 1-2 Polyurethane reactive compositions are prepared from the constituents shown in Table 1. It is observed that the crimping time of the compositions according to the invention is shorter than that of the compositions of the examples. C1 and C while the weather

of wire is substantially the same.

  Whereas the foams of Example 1 and Comparative Examples C and C2 have substantially the same density,

  it can be seen that that prepared according to the invention has a resistance

  "parallel" compression ratio has been significantly increased,

  that "perpendicular" compressive strength and stability

  dimensional units substantially improved. The values 2 preceded by the sign - indicate the dispersion of the measurements obtained on different samples taken from the same block of foam. It is observed that the mechanical properties are more homogeneous in the case of foams obtained according to the invention than in the case of

foams comparative examples.

  In the table, the marks (1), (2) and (3) have the following meanings:

  (1) = Compound of polyaddition of propylene oxide on a solution

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250121'5

Claims (8)

  A method of manufacturing rigid polyurethane foam body from a reactive polyurethane composition comprising polyether polyols, blowing agents and organic polyisocyanates, characterized in that these compositions additionally contain from 3 to 100% by weight, preferably 5 to 50% by weight, based on the polyether-polyols, of one or more   polyhydroxy polyaromatic compounds.   The method of claim 1, wherein the   polyhydroxylated polyaromatic compounds are polyhy-   hydroxypolyphenylalkanes such as bis (p.hydroxyphenyl) methane or   2,2-bis (p-hydroxyphenyl) propane.   3. The process according to claim 1, wherein the poly-   ether-polyols have a hydroxyl number of between 300 and 1000, and preferably between 350 and 500, and result from   polyaddition of propylene oxide and optionally of ethylene oxide   binds to compounds having 3 to 8 mobile hydrogen atoms.   4. The process according to claim 1, wherein the   polyhydroxy polyaromatic compounds are used in in polyether-polyols.   The method of claim 1, wherein the   organic polyisocyanates consist of tolylenediisocyanates   4-4'-diphenylmethane diisocyanate, with tolylenediiso-   crude cyanate or diphenylmethane 4-4 'crude diisocyanate.   6. The method of claim 1, wherein the index 2 i of isocyanate is between 1.00 and 3.50, and preferably between 1.05 and 1.15.   7. As new industrial products, the bodies   moldings obtained according to any one of claims 1   to 6 above and having an average density included between 30 and 800 kg / m3.   8. As a specific means of implementing the pro-   assigned according to claim 4, the solutions of polyhydro-   polyaromatic xyls in polyether polyols.