WO1992016573A1

WO1992016573A1 - Method for preparing halogen-free hard foam substances containing urethane groups and predominantly isocyanurate groups

Info

Publication number: WO1992016573A1
Application number: PCT/EP1992/000524
Authority: WO
Inventors: Rolf Wiedermann; Gerhard Heilig; Martin Hoppe; Stephan Wendel; Wolfgang Schmitz
Original assignee: Bayer Aktiengesellschaft
Priority date: 1991-03-20
Filing date: 1992-03-10
Publication date: 1992-10-01
Also published as: DE4109076A1; ZA922003B

Abstract

Halogen-free hard foam substances containing urethane groups and predominantly isocyanurate groups are prepared by reacting a) polyisocyanates with b) compounds having a molecular weight of 400 to 10'000 and containing at least two hydrogen atoms which react with isocyanates and c) possibly compounds having a molecular weight of 32 to 399 and containing at least two hydrogen atoms which react with isocyanates in the presence of d) trimerization catalysts and e) water and/or hydrocarbons as foaming agents and f) phosphorylated fireproofing materials, possibly in the presence of g) additional foaming agents and additional process materials and additives, at a characteristic number of 80 to 400, preferably 100 to 300. All chemical compounds used, in particular the fireproofing materials and foaming agents, are halogen free. The compounds so prepared are used as insulating materials.

Description

Process for the production of urethane and predominantly isocyanurate halogen-free rigid foams and their use as dam materials.

The present invention relates to halogen-free, flame-retardant rigid foams which have urethane and predominantly isocyanurate groups.

As a rule, various halogen-containing compounds are used in the production of rigid polyurethane foams. This is e.g. fluorochlorohydrocarbons, which serve as blowing agents for the formation of cellular structures. Furthermore, halogen-containing chemical compounds are often used to increase the flame resistance of the rigid foams.

In general, however, the processing of such halogen-containing substances in rigid foams is discussed as problematic, since their disposal is made more difficult by recycling or by burning the old substances in waste incineration plants. It was therefore an object to find a process for the production of rigid foams which do not have these problems, but on the other hand the rigid foams have good insulation properties and flame retardant properties required for construction applications. Such products have already been described in EP-A 0 308 733. These are rigid PU foams with a range of 85 to 150, which are preferably driven by the carbon dioxide generated from the water-isocyanate reaction. In order to be able to process reliably, raw densities of not less than 40 kg / m ^{3 are} common with such rigid foams, since otherwise there is a risk of shrinkage or shrinkage. In addition, the foams show poor aging behavior of the thermal insulation properties, caused by the rapid diffusion of carbon dioxide from the cells, as well as the slow diffusion of air into the cells. With such foams, good long-term insulation is only possible if diffusion-tight cover layers are processed.

Halogen-free rigid foams are also described in EP-A 0 394 769. Pentane is used as the halogen-free but flammable hydrocarbon for the blowing reaction. Therefore, considerable efforts had to be made to ensure the flame retardancy required for building materials. This EP-A uses dimethyl methane phosphonate (DMMP), against which toxicological concerns have been raised, and its use should therefore be avoided. Flame retardants which are solid at room temperature are also used, but their processing poses technical problems.

Attempts have also been made to produce ecologically sound rigid foams by increasing the flame resistance by incorporating polyisocyanurate structures. Carbon dioxide is in turn generated as a blowing agent from the water-isocyanate reaction. As described above, however, carbon dioxide can only guarantee a permanently low coefficient of thermal conductivity when processing diffusion-tight cover layers.

In order to maintain a permanently low coefficient of thermal conductivity, it is therefore necessary to use a cell gas that remains permanently in the cell. Hydrocarbons have this property, but considerably impair the flame resistance of the rigid foams.

These so-called PIR foams often have the technical disadvantage that they generally require higher processing temperatures than PUR foams in order to ensure adequate adhesion to the cover layers used.

Surprisingly, it has now been found that with known halogen-free phosphorus compounds in formulations with key figures between 80 and 400, such rigid foams can be produced using hydrocarbons.

It can be surprising with those containing phosphorus

Flame retardants also around solid at room temperature Substances act when they can be brought into an easily processable form by the solution in the isocyanate. The solution in the isocyanate is preferable to that in the polyol, since the latter can lead to precipitation and crystal formation due to the lower solubility product.

A considerable advantage of the solution of the flame retardants in the polyisocyanate is that the viscosity of the solutions is much lower than that of the pure isocyanates.

The consequence of this is that it is now possible for the first time to process highly viscous and highly functional ionic polyisocyanates using conventional high-pressure systems: - The reaction components are mixed with one another much more intimately, which leads to very fine cell structures. - The flow behavior of the ascending reaction mixture is more uniform. - The physical and fire technological property values of the rigid foams are improved. - The adhesion of the rigid foam to the top layers used is improved.

The invention relates to a process for the production of urethane and predominantly isocyanurate halogen-free rigid foams by reacting a) polyisocyanates with b) compounds with at least two isocyanate-active hydrogen atoms with a molecular weight of 400 to 10,000 and c) optionally compounds with at least two isocyanate-reactive hydrogen atoms and with a molecular weight of 32-399, in the presence of d) trimerization catalysts and e) water and / or hydrocarbons as blowing agents and f) phosphorus-containing flame retardants, if appropriate in the presence of g) further blowing agents and other auxiliaries and additives known per se with a code number of 80 to 400, preferably 100 to 300, characterized in that all the compounds used, in particular the flame retardants and blowing agents are halogen-free.

It is preferred according to the invention that pentane, isopentane, cyclopentane or mixtures thereof are used as hydrocarbon blowing agents, the phosphorus-containing flame retardants are liquid at room temperature,

- The additives containing phosphorus used

Are aryl, aralkyl or alkyl phosphates,

- as aryl or alkyl phosphate triphenyl phosphate,

Diphenyl cresyl phosphate or triethyl phosphate or mixtures thereof can be used

- The phosphorus-containing solid at room temperature

Additives in amounts of 1 to 50% by weight, preferably 5 to 30% by weight, are dissolved in the polyisocyanate,

- Benzyl-n-butyl phthalate used as an emulsifier

becomes,

- As an emulsifier containing hydroxyl groups

OH number 85 polyether made by

Ethoxylation of Nonyϊphenol is used.

The invention also relates to the use of the halogen-free rigid foams containing urethane and predominantly isocyanurate groups as insulating materials. The production of foams containing urethane and predominantly isocyanurate groups is known per se and e.g. in DE-PS 11 12 285, GB-PS 11 04 394, DE-OS 15 95 844 and 17 69 023 as well as in the plastics manual volume VII, Polyurethane, published by Vieweσ and Höchtlen, Carl Hanser Verlag Munich 1966 and in the new edition of this book, edited by G.Oertel, Carl Hanser Verlag Munich, Vienna 1983.

For the production of the foams are used As starting components, aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates, as described, for example, by W. Siefken in Justus Liebigs Annalen der Chemie, 562, pages 75 to 136, for example those of the formula

Q (NCO) _n n = 2-4, preferably 2-3, and Q is an aliphatic hydrocarbon radical with 2-18, preferably 6-C atoms, a cycloaliphatic hydrocarbon radical with 4-15, preferably 5-10 C atoms, are an aromatic hydrocarbon radical with 6-15, preferably 6-13 C atoms or an aromatic hydrocarbon radical with 8-15, preferably 8-13 C atoms, for example those polyisocyanates as described in DE-OS

28 32 253, pages 10-11. The technically easily accessible polyisocyanates, for example the 2,4- and 2,6-tolylene diisocyanate, and any mixtures of these isomers (“TDI”) are generally particularly preferred; Polyphenylpolymethylene polyisocyanates, such as those produced by aniline-formaldehyde condensation and subsequent phosgenation ("crude MDI") and carbodimide groups, urethane groups, Al lophanate groups, isocyanurate groups, urea groups or biuret groups-containing polyisocyanates ("modified polyisocyanates"), in particular those modified Polyisocyanates derived from 2,4-and / or 2,6-tolylene diisocyanate or from 4,4'-and / or 2,4'-diphenylmethane diisocyanate. b) Starting components are also compounds having at least two isocyanate-reactive hydrogen atoms with a molecular weight of generally 400-10,000. In addition to amino groups, thio groups or compounds having carboxyl groups, this is understood to mean compounds having hydroxyl groups, in particular 2 to 8 hydroxyl groups

Compounds, especially those with a molecular weight of 1000 to 6000, preferably 2000 to 6000, for example at least 2, usually 2 to 8, but preferably 2 to 6, hydroxyl-containing polyethers and polyesters and polycarbonates and polyester amides, such as those used for the production of homogeneous and cellular polyurethanes are known per se and as described, for example, in DE-0S 28 32 253, pages 11-18. c) Where appropriate, further starting components are compounds having at least two isocyanate-reactive hydrogen atoms and a molecular weight of 32 to 399. In this case too, this means hydroxyl groups and / or amino groups and / or thiol groups and / or carboxyl group-containing compounds, preferably hydroxyl groups and / or Compounds containing amino groups which serve as chain extenders or crosslinking agents. These compounds generally have 2 to 8, preferably 2 to 4, compared to isocyanates

reactive hydrogen atoms. Examples of this are described in DE-OS 28 32 253, pages 19-20. d) According to the invention, those known per se

Trimerization catalysts also used. e) According to the invention, phosphorus-containing,

Halogen-free flame retardants such as triphenyl phosphate, triethyl phosphate, diphenyl cresyl phosphate, or mixtures thereof, red phosphorus are used. f) Water and / or hydrocarbons, preferably C ₃ -C ₇ -alkanes, particularly preferably pentane, isopentane and cyclopentane or mixtures thereof, are used as blowing agents. g) If necessary, auxiliaries and additives

also used as - other volatile organic substances as additional blowing agents. - Additional catalysts of the type known per se in amounts of up to 10% by weight, based on the amounts of component b). - Surface-active additives, such as emulsifiers and foam stabilizers. - 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, furthermore stabilizers against

Aging and weather influences, plasticizers and fungistatic and bacteriostatic substances as well as fillers such as barium sulfate, diatomaceous earth, carbon black or sludge chalk.

If necessary, these auxiliary and

Additives are, for example, in DE-OS

27 32 292, pages 21-24. Further examples of surface-active additives and foam stabilizers to be used according to the invention, as well as cell regulators, reaction retarders, stabilizers, flame-retardant substances, plasticizers, dyes and fungistatic and bacteriostatic substances, as well as details on the use and mode of action of these additives are published in the plastics manual, Volume VII, by Vieweg and Hδchtlen, Carl-Hanser-Verlag, Munich 1966, e.g. described on pages 103-113.

Carrying out the process for producing the foams:

The reaction components are according to the known one-step process, the prepolymer process or brought the semiprepolymer process to implementation, often using machine facilities, such as those described in US Pat. No. 2,764,565. Details on processing devices that are also possible according to the invention are described in the plastics manual, volume VII, edited by Vieweg and Hochtlen, Carl-Hanser-Verlag, Munich 1966, for example on pages 121 to 205.

Of course, foams can also be produced by block foaming or according to the known method

Double conveyor belt processes are manufactured.

The products obtainable according to the invention are used, for example, as insulation boards for roof insulation, sheet steel composite elements or block foam material.

Examples

The following mixtures were produced:

Polyol component A 100 parts by weight of CGT) of a polyol mixture of OH number 265 with a viscosity of 3100 mPa.s at 20 ° C, consisting of:

1. 20 pbw of a polyether of OH number 375, prepared by prep ationing a mixture of sugar,

Propylene glycol and water.

2. 30 pbw of a polyester of OH number 210 based on adipic anhydride, phthalic anhydride, glycerol and propylene glycol

3. 4 pbw of a polyester with OH number 685, prepared by reacting phthalic anhydride with

Diethylene glycol

4. 5 pbw of a polyether with OH number 640, produced by reacting ethylenediamine with a

Mixture of ethylene oxide and propylene oxide 5. 6 pbw of a polyether of OH number 185, produced by ethoxylation of propylene glycol

6. 3 parts by weight of glycerin 7. 30 parts by weight of diphenyl cresyl phosphate as a flame retardant 8. 1.5 GT of a commercially available. Polyether polysiloxane foam stabilizer (Tegostab B8421, Goldschmidt AG, Essen)

9. 0.5 pbw of a commercially available polyether-polysiloxane chaura-stable isator (Tegostab B8443, Goldschmidt AG, Essen)

Polyol component B

100 pbw of a polyol mixture of OH number 265 with a viscosity of 340 mPa.s at 20 ° C corresponding to the

Polyol component A, in which the flame retardant

Diphenyl cresyl phosphate by the same amount of

Flame retardant triethyl phosphate has been replaced. The polyol components A and B thus produced were processed in accordance with the recipes listed in the table with various key figures to give rigid polyurethane foams with polyisocyanurate structures. Polyol component C

100 pbw of a polyol mixture of OH number 185 with a viscosity of 1900 mPa.S at 25 ° C, consisting of: 1. 50 pbw of a polyester of OH number 370 based on phthalic anhydride, adipic acid, oleic acid and

Trimethylolpropane

2. 15 pbw of benzyl n-butyl phthalate

3. 35 pbw of diphenyl cresyl phosphate as a flame retardant 4. 1.6 pbw of a commercially available polyether polysiloxane foam stabilizer (Tegostab B 8443, Goldschmidt AG, Essen)

Polyol component D

100 pbw of a polyol mixture of OH number 185 with a viscosity of 200 at 25 ° C. corresponding to polyol component C, in which the flame retardant diphenyl cresyl phosphate was replaced by the same amount of the flame retardant triethyl phosphate.

The polyol components A and B represent typical mixtures that are used for the production of insulation boards and composite elements on double conveyor belt systems. The formulations C and D represent typical ones

Mixtures as they are used to manufacture block foam.

The results of the tables show that regardless of the type of flame retardant, the rigid foams with a key figure above 200 meet the requirements for classification B2 according to DIN 4102 (small burner test). In contrast, rigid foams with a key figure below 200 can only be classified in class B3.

Foaming according to the examples given in the tables was carried out in a manner known per se by the one-shot method using the recipes given.

The following polyol mixtures were also produced: Polyol component A

100 parts by weight (GT) of a polyol mixture of OH number 386 with a viscosity of approx. 7,000 mPa.s at 20 ° C, consisting of:

1. 15 pbw of a polyether of OH number 460, prepared by reacting o-toluenediamine with ethylene oxide and propylene oxide.

2. 10 pbw of a polyether of OH number 620, prepared by reacting ethylenediamine with propylene oxide. 3. 15 pbw of a polyether with OH number 435, produced by reacting phthalic anhydride, sorbitol and diethylene glycol with propylene oxide.

4. 10 pbw of a polyether with an OH number of 300, produced by reacting phthalic anhydride, diethylene glycol and ethylene oxide.

5. 10 pbw of a polyether of OH number 210, prepared by reacting diethylene glycol, adipic acid and phthalic anhydride.

6. 10 pbw of a polyether of OH number 380, produced by reacting adipic acid, phthalic anhydride, oleic acid and trimethylolpropane. 7. 12 pbw of a polyether of OH number 380, produced by reacting trimethylolpropane with propylene oxide.

8. 3 pbw of glycerin.

9. 5 pbw of n-butylbenzyl phthalate

10. 10 pbw of diphenyl cresyl phosphate as a flame retardant. Polyol component B

100 pbw of a polyol mixture of OH number 155 with a viscosity of. approx. 550 mPa.s at 25 ° C, consisting of: 1. 55 pbw of a polyether with OH number 45, produced by reacting trimethylolpropane with propylene oxide and ethylene oxide.

2. 15 pbw of a polyether with OH number 865, produced by reacting trimethylolpropane with propylene oxide.

3. 15 pbw n-butylbenzyl phthalate 4, 15 pbw diphenyl cresyl phosphate as a flame retardant. Polyol component C

100 pbw of a polyol mixture of OH number 203 with a viscosity of approx. 600 mPa.s at 25 ° C, consisting of:

1. 30 pbw of a polyether of OH number 45, prepared by reacting trimethylolpropane with propylene oxide and ethylene oxide.

2. 30 pbw of a polyether of OH number 56, produced by reacting propylene glycol with propylene oxide.

3. 20 pbw of a polyether of OH number 865, produced by reacting trimethylolpropane with propylene oxide.

4. 20 pbw of diphenyl cresyl phosphate as a flame retardant.

In addition, the following isocyanate components were prepared by heating a commercial isocyanate to 50 ° C to 70 ° C, adding the appropriate amount of flame retardant and cooling the mixture:

Isocyanate component I

10 pbw of triphenyl phosphate are dissolved in 100 pbw of polyisocyanate ( ^® Desmodur 44V70; Bayer AG, Leverkusen). Isocyanate component II

10 pbw of triphenyl phosphate are dissolved in 100 pbw of polyisocyanate ( ^® Desmodur 44P75; Bayer AG, Leverkusen).

Isocyanate component III

10 pbw of triphenyl phosphate are dissolved in 100 pbw of polyisocyanate ( ^® Desmodur VP.PU 1194J Bayer AG, Leverkusen).

Isocyanate component IV

30 pbw of triphenyl phosphate are dissolved in 100 pbw of polyisocyanate ( ^® Desmodur VP.PU 1194. Bayer AG, Leverkusen).

The isocyanate components produced in this way had the following properties:

Compared to the commercially available isocyanates (Table 4), the isocyanate components according to the invention have considerably lower viscosities. The addition of triphenyl phosphate to the PU 1194 allows it to be processed on high-pressure systems for the first time.

Compared to the commercially available isocyanates, the solubility of pentane in the isocyanate components I to IV increases by 10 to 30%.

Polyol and isocyanate components as well as the commercially available isocyanates represent typical products such as those used for the production of rigid foam insulation boards or composite elements on double conveyor belt systems or for the production of block foams.

Foaming recipes, conditions and results are listed in Tables 5 to 8 below. These deal in detail with:

Table 5: Halogen-free, pentane-driven B2 rigid foams, index numbers approx. 130 and 150. Table 6: Halogen-free, water- (CO ₂ ) -driven B2 rigid foams, index approx. 250.

Table 7: Halogen-free, pentane-propelled B2 rigid foams, index approx. 250. Table 8: Halogen-free, pentane-propelled B2 rigid foams, index approx. 300.

The following appears from the tables: The flame retardant cannot be added to the polyol because the solid either does not dissolve at room temperature or - if dissolved in the heated polyol - crystallizes out again on cooling. Surprisingly, it was found that the solution of triphenyl phosphate in the isocyanate according to the invention is phase-stable.

From the results it can also be seen that the rigid foams produced according to the invention - regardless of the characteristic number - meet the requirements for the classification B2 according to DIN 4102 (small burner test). The comparative examples, however, can only be classified in class B3.

Claims

1. Process for the production of urethane and predominantly isocyanurate halogen-free rigid foams by reacting a) polyisocyanates with b) compounds with at least two

Isocyanate active hydrogen atoms of molecular weight 400 to 10,000 and c) optionally compounds with at least

two isocyanate-reactive hydrogen atoms and a molecular weight of 32-399, in the presence of d) trimerization catalysts and e) water and / or hydrocarbons as blowing agents and f) phosphorus-containing flame retardants, optionally in the presence of g) further blowing agents and others

known auxiliaries and additives with a characteristic number of 80 to 400, preferably 100 to 300, characterized in that all the compounds used, in particular the flame retardants and blowing agents, are halogen-free.

2. The method according to claim 1, characterized in that the phosphorus-containing additives used are aryl, aralkyl or alkyl phosphates.

3. The method according to claim 1 and 2, characterized in that triphenyl phosphate, diphenyl cresyl phosphate or triethyl phosphate or mixtures thereof are used as aryl or alkyl phosphates.

4. The method according to claim 1 to 3, characterized in that the solid phosphorus-containing additives at room temperature in amounts of 1 to 50 wt .-%, preferably 5 to 30 wt .-%, are dissolved in the polyisocyanate.

5. The method according to claim 1 to 3, characterized in that the phosphorus-containing flame retardants are liquid at room temperature.

6. The method according to claim 1 to 5, characterized in that as a hydrocarbon blowing agent

Pentane and / or isopentane and / or cyclopentane is used.

7. The method according to claims 1 to 6, characterized in that benzyl-n-butyl phthalate is used as an emulsifier.

8. Process according to Claims 1 to 6, characterized in that a polyether having OH number 85 and having hydroxyl groups is prepared as the emulsifier by ethoxylation of nonylphenol.

9. Use of the rigid foams obtainable according to claims 1 to 8 and predominantly isocyanurate groups containing rigid foams as dam materials.