DD297828A5 - METHOD FOR PRODUCING HOT-HOLDING POLYURETHANE-SOFT FORMULA SUBSTANCES - Google Patents

Abstract

Thermosetting polyurethane flexible foams are prepared by reacting a) polyisocyanates of the type of diphenylmethane diisocyanate and / or of tolylene diisocyanate and / or hexamethylene diisocyanate and / or isophorone diisocyanate with b) compounds having at least two isocyanate-active hydrogen atoms of molecular weight 400 to 10,000 and optionally c ) Chain extenders and crosslinkers having at least two isocyanate-active hydrogen atoms of molecular weight 32-399 in the presence of d) water as blowing agent in an amount of 5 to 15 parts by weight, preferably 6-12 parts by weight, based on 100 wt. Parts of component b) and optionally in the presence of e) other blowing agents, catalysts and other per se known auxiliaries and additives prepared in a closed form, wherein the reaction of all components at a ratio of less than 90, preferably 60-80 carried out becomes.

Description

Thermosetting polyurethane flexible foams are known to have a very widespread application and u. a. also used in the automotive sector and in the furniture industry. The quality of the customary as seat or backrest cushion polyurethane flexible foam is largely determined by their density. Regardless of the nature of the raw materials (polyols / isocyanates) which can be used for the production of hot-formed foams, a specific density level has proven to be expedient and practical for the various applications and the associated requirements, but in particular with regard to the most favorable permanent use properties.

For the raw density to be achieved, the water content of the combination of raw materials is mainly determining, with amounts of water of up to 5 (usually 2.5-3, E) parts by weight per 100 parts of polyol being considered typical, depending on the desired bulk density level.

As it turns out, the lower densities often desired for reasons of weight and cost savings, depending on the use of foam, can only be achieved in exceptional cases by increasing the water content beyond the indicated amounts. The reason for this lies in the fact that with increasing water content (> 3.5 parts by weight, per 100 parts by weight of polyol), the catalytic coordination of the chemical reactions (polymer formation / gas formation), which is indispensable for the foaming process, becomes more difficult and the overall processing latitude greatly reduced becomes. In addition to problems with skin texture (mold temperature / release agent) and foam stability results in particular an impairment (= limitation) of the performance index scope. For these reasons, desired or required reductions in the bulk density are preferably achieved by the use of physically acting blowing agents {ζ. Β.

HalogenkohL.v./hydrogen) realized. This procedure is state of the art and applies in principle to all hot-formed foams.

However, this method is allei dings also mainly for reasons of environmental protection to advocate.

Surprisingly, it has now been found that atypically high amounts of water of more than 5.0 parts by weight per 10 parts by weight of "base polyol" can be processed without problems and, as a consequence, densities of up to 15 kg / m ³ can be achieved with hot-curing polyurethane flexible foam. if, in deviation from the code range (95-105), which was previously considered to be the norm, a normally prohibitively low ratio of less than 90 is chosen for foaming.

Although GB-PS 892776 has already disclosed hard or semi-rigid polymer foams by reacting 10 parts by weight of a monomeric organic polyisocyanate with 1 to 30 parts by weight of water in the presence of a surface-active agent and a catalyst, preferably in the presence of 5 to 30 parts by weight of a polyfunctional compound having two or more than two isocyanate reactive groups. However, as can be seen from the claims and also from the examples of this GB-PS, it is in the "catalysts" are inorganic products of potassium acetate or sodium hydroxide, so that a predominantly determined by Trimerisierungsreaktionen foaming process is enforced and the principle of According to the invention to be observed low Kennzahln does not come to Trfigen.

Subject of the invention is a process for the preparation of thermosetting polyurethane flexible foams by reacting

a) polyisocyanates with

b) compounds having at least two isocyanate-active hydrogen atoms of molecular weight 400-10000 and optionally

c) chain extenders and crosslinkers having at least two isocyanate-active hydrogen atoms of molecular weight 32-399 in the presence of

d) water as blowing agent and optionally in the presence of

e) other blowing agents, catalyst, and other known auxiliary agents and additives in a closed form, which is characterized in that

1. as polyisocyanates a) those of the type of diphenylmethane diisocyanate and / or of tolylene diisocyanate and / or hexamethylene diisocyanate and / or isophorone diisocyanate, and

2. as Treibmitteid) water in an amount of 5 to 15 parts by weight, preferably 6-12 parts by weight, based on 100 parts by weight of component b)

be used, where

3. the implementation of all components at a ratio of less than 90, preferably 60-80, is performed.

For the preparation of the thermosetting Polyurathan soft foam foams are used according to the invention as starting components:

1. polyisocyanates of the type of diphenylmethane diisocyanate and / or of tolylene diisocyanate, z. Example, the 2,4- and 2,6-toluene diisocyanate, and any mixtures of the isomeric ("TOI"), 4,4'- and / or 2,4'-diphenylmethane diisocyanate ("MDI"), hexamethylene diisocyanate and / ocier isophorone diisocyanate , Polyphenyl polymethylene polyisocyanates, as prepared by aniline-formaldehyde condensation and subsequent phosgenation ("crude MDI"), furthermore by carbodiimide groups, urethane groups, allophanate groups, isocyanurate groups, urea groups or biuret-group-modified polyisocyanates which differ from the 2,4- and / or or 2,6-tolylene diisocyanate or derived from 4,4'- and / or 2,4'-diphenylmethane diisocyanate and / or hexamethylene diisocyanate and / or isophorone diisocyanate, further alkyl-substituted MDI types, as described for example in DE-OS 2935318, DE-OS OS 3032128 and DE-OS 3032358 are described.

Furthermore, the following TDI types preferably come into consideration according to the invention:

Toluene diisocyanate as a mixture of 2,4- and 2,6-isomers in the ratio 80:20 (T80)

Toluene diisocyanate as a mixture of the 2,4- and 2,6-isomers in the ratio 65:35 (T65)

- Toluylene diisocyanate prepolymers

- Blends of TOI with diphenylmethane diisocyanate and / or polyphenylpolymethylene polyisocyanates.

2. Compounds having at least two isocyanate-reactive hydrogen atoms of a molecular weight, usually 400-10000. This is understood as meaning, in addition to compounds having amino groups, thio groups or carboxyl groups, preferably hydroxyl-containing compounds, in particular two to eight hydroxyl-containing compounds, especially those of molecular weight 1000 to 6000, preferably 2,000 to 6,000, eg. B. at least two, usually two to eight, but preferably 2 to 6, hydroxyl-containing polyethers, polyesters, polycarbonates and polyester amides, as they are known per se for the preparation of homogeneous and cell-based polyurethanes and as such. B. in DE-OS 2832253, pages 11-18 described. Preferably, they have an OH number of 28 to 56.

3. If appropriate, compounds having at least two isocyanate-reactive hydrogen atoms and a molecular weight of from 32 to 399. In this case, too, are meant compounds having hydroxyl groups and / or amino groups and / or thiol groups and / or carboxyl groups, preferably compounds containing hydroxyl groups and / or amino groups which serve as chain extenders or crosslinkers. These compounds generally have from 2 to 8, preferably from 2 to 4, isocyanate-reactive hydrogen atoms. Examples of this are described in DE-OS 2832253, pages 10-20.

4. Water as blowing agent in an amount of 5 to 15 parts by weight, preferably 6 to 12 parts by weight, per 100 parts by weight of "base polyol" b)

5. Gagebenenfalls auxiliary and additive are used as well

a) volatile organic substances as further blowing agents,

b) reaction accelerator and reaction retarder of the type known per se in the quantities which are customary per se,

c) surface-active additives, such as emulsifiers and foam stabilizers,

cell regulators known per se such as paraffins or fatty alcohols or dimethylpolysiloxanes as well as pigments od> r dyes and flameproofing agents known per se »type, for example tris-chloroethyl phosphate, tricresyl phosphate, also stabilizers against aging and weathering, softeners and fungistatic and bacteriostatic substances and fillers such as barium sulfate, kieselguhr, soot or whiting.

These optionally used auxiliaries and additives have been described for example in DE-OS 2732292, pages 21-24.

Further examples of optionally used according to the invention surface-active additives and foam stabilizers and cell regulators, reaction retarders, stabilizers, flame retardants, plasticizers, dyes and fillers and fungistatic and bacteriostatic substances and details on the use and mode of action of these additives are published in the Plastics Handbook, Volume VII by Vioweg and Höchtlen, Carl-Hanser-Verlag, Munich 1966, eg described on pages 103-113.

Implementation of the method according to the invention:

The reaction components are brought according to the invention according to the known one-step process, the prepolymer process or the Semipräpolymerverfahren to implement, which is often used mechanical equipment, eg. Such as those described in US Pat. No. 2,764,565. Details of processing equipment, which also come under the invention, are in the Plastics Handbook, Volume VII, published by Vieweg and Höchtlen, Carl Hanser Verlag, Munich 1966, z. On pages 121-205. The implementation of all components according to the invention is carried out at a ratio below 90, preferably at a ratio of 60-80.

The index, a term used very frequently in the production of polyurethane foams, says something about the degree of crosslinking of a foam. It is customary to regard that foam as having the characteristic number 100, in which the stoichiometric ratio or the theoretically necessary amount of isocyanate was used. With the help of the key figure, it is thus possible to define the degree of under- or over-crosslinking in more detail. The key figure is calculated according to the general formula as follows:

measure

* 1U0

isocyanate amount (, _h , o "ti, chi

According to the invention, the foaming is carried out in closed molds. The reaction mixture is introduced into a mold. As a molding material is metal, z. As aluminum or plastic, for. As epoxy resin, in question. In the mold, the foamable reaction mixture foams and forms the molding. According to the invention, it is possible in this connection to proceed by introducing into the mold so much foamable reaction mixture that the foam formed just fills the mold. But you can also work so that one enters more foamable reaction mixture into the mold, as is necessary for filling the mold interior with foam. In the latter case, "overcharging" is thus used, such a method being known, for example, from US Pat. Nos. 3,178,490 and 3,182,104 The inventively available hot-curing polyurethane flexible molded foams are used, for example, as dashboards, armrests (including car seats), Lying and seating, headrests, seats in transport, preferably in the car.

embodiments Polyether A a glycerol-initiated trifunctional Jr. long-chain PO / EO polyexherfca. 15% EO), OH = 36; MG 4800 Polyether B a glycerol-initiated trifunctional, long-chain PO / EO-polyeth, ir (about 10% EO), OHZ = 50; MG 3900 Catalyst 1 bis-N, N'-dimethylamino-diethyl ether (30%), dipropylene glycol (70%) Catalyst 2 stannous octoate T80 toluene diisocyanate, mixture of 2,4- and 2,6-isomers in a weight ratio of 80: 20%

All components are mixed together intensively and foamed in a closed form (22cm χ? 2cm χ 7cm).

PolyetherA Polyether B

water

Foam stabilizer OS32

(Bayer Ag) (polyetherpolysiloxane)

Catalyst 1 Catalyst 2

TDI80

KennzahlRohdichte

compressive strength

(at 40% deformation)

example 1 Example 2

70Gew. parts 65 parts by weight 30 parts by weight 35Gew.-Tei! E 7.0 parts by weight 8.0 parts by weight 1,5Gew. parts 1.5 parts by weight 0.2 parts by weight 0.2 parts by weight 0.4 parts by weight 0.4 parts by weight X * X " 80 75 24 kg / m ³ 22 kg / m ³ 3.2 kPa 3,4KPa

* Quantity according to each measure

Claims (3)

Process for the preparation of thermosetting polyurethane flexible foams by reaction of a) polyisocyanates with b) Compounds with at least two isocyanate-active hydrogen atoms of molecular weight 400 to 10,000 and optionally c) chain extenders and crosslinkers having at least two isocyanate-active hydrogen atoms of molecular weight 32-399 in the presence of d) water as blowing agent and optionally in the presence of e) other blowing agents, catalysts and other known auxiliaries and additives in a closed form, characterized in that 1. as polyisocyanates a) those of the type of diphenylmethane diisocyanate and / or of tolylene diisocyanate and / or hexamethylene diisocyanate and / or isophorone diisocyanate, and 2. as propellant d) water in an amount of 5 to 15 parts by weight, preferably 6-12 parts by weight, based on 100 parts by weight of component b) be used, where 3. the implementation of all components at a ratio of less than 90, preferably 60-80, is performed.