DD279582A3 - PROCESS FOR THE PRODUCTION OF POLYURETHANE SYSTEMS WITH LONG USE - Google Patents

Abstract

The invention is used for the production of non-cellular tough and non-cellular hard polyurethane compositions. The object and task is to extend the reaction between the polyol component, the isocyanate component and optionally the auxiliaries and additives by adding a suitable Verzoegerungsmittels in the production of polyurethane systems and thus to achieve a sufficient Lagerstabilitaet, versatility and long service life for manual processing. The polyurethane compositions produced are non-cellularly hard or non-cellularly hard and have improved mechanical properties compared to the prior art. They do not have a corrosive effect on metal parts. The object is achieved according to the invention by adding, based on the polyol component thereof, from 5 to 40% of polypropylene glycol as a delaying agent which has an average molecular weight of at least 1,000.

Description

Field of application of the invention

The invention is used for the production of noncellular tough and non-cellular hard polyurethane compositions.

Characteristic of the known technical solutions

It is known to prepare polyurethane compositions by a polyaddition reaction between a polyol component and an isocyanate component. Depending on the choice of starting materials, elastic, tough or hard polyurethane compounds are produced. The present invention relates to tough and hard polyurethane compositions. Since the transition between elastic polyurethane compositions on the one hand and hard and tough on the other hand fluid and exact delimitation is difficult to tough and hard polyurethane compositions in the sense of this invention description should be those which are prepared using a polyol whose average hydroxyl number is at least 150 mg KOH / g ,

As the isocyanate component for such polyurethane compositions it is preferred to use those which at least partially contain diphenylmethane diisocyanate and / or its reaction products. Polyurethane compositions based on diphenylmethane diisocyanate have good mechanical and electrical properties. The toxicological problems are comparatively low in their processing. A disadvantage of these polyurethane compositions is that these reaction mixtures of the Polyolkomponenie and the isocyanate component due to the relatively high reactivity of Diphenylmethandiisocyanates have relatively short service lives (pot life), which is particularly disadvantageous in the hand processing such Polyurethanmischunoen. As a useful life in this sense, the period between mixing of the starting components and the achievement of an undesirably high viscosity of the polyurethane mixture (limit of processability) is defined.

To delay the reaction between Pol / oil and isocyanate component according to R.Vieweg, A.Höchtlen, Polyurethane, Carl Hanser Verlag Müchen 1966, p 102,103 the addition of acids or acid-releasing compounds, such. Hydrochloric acid, acid chlorides, phosphoric acid, phosphoric esters known. A disadvantage of this method is that the acidic constituents in the production and storage of the polyurethane raw materials and their processing cause corrosion problems and remain as foreign components in the cured polyurethane and thus cause deterioration of the properties, in particular the electrical.

According to DE-OS 159525 and DD-PS 115913 the addition of amines to tin-containing or of tin compounds to amine-containing polyurethane mixtures is also known to delay the reaction between polyol and isocyanate component. This method is based on the mutual inhibiting effect between amines and tin compounds and is only applicable to catalytic reaction mixtures which, because of their relatively short service life, are in any case unsuitable for hand processing. Moreover, these mixtures are not sufficiently stable on storage, i. the period of use is subject to significant changes during the storage period.

The same disadvantages have those polyurethane mixtures which are amine-catalyzed according to DD-PS 109162 and DD-PS 109163 and the delay either reaction residues of the acetoacetate or substituted pyrone or substituted thiopyrone are added.

It is also known that according to DE-OS 2439276 Polyestersralkohole be reacted for the purpose of delaying the reaction with polyisocyanates partially with monoepoxides. Part of this process is that it is limited to polyester alcohols and requires an upstream reaction step at elevated temperature.

Object of the invention

The aim of the invention is to produce polyurethane systems economically. Sm should be sufficiently storable, versatile and suitable for a long service life for the Handvcrardeitung. The polyurethane compositions produced therefrom are said to be non-cellular tough or non-cellular, and have improved mechanical properties over the prior art. These polyurethane compounds must not be corrosive to metal parts.

Essence of the invention

The object of the invention to achieve the object rugrunde, in the preparation of the polyurethane systems, the reaction.! Wischen the polyol component, the isocyanate component and optionally extend the auxiliaries and additives by adding a suitable retarder.

According to the invention the object is achieved in that based on the polyol component thereof 5 to 40% polypropylene glycol as a retarding agent having an average molecular weight of at least 1000, are added. Although, according to the prior art, sufficient work has been done on the problem of delay in response, it has not been possible to achieve satisfactory solutions which meet the objective set in accordance with this invention. Therefore, it is completely surprising that the objective is achieved by using this delay means.

For the delay agents admixed by the process according to the invention, it is possible to use all known processes by polyaddition of propylene oxide to glycols or water, oligomeric polypropylene glycols having an average molecular weight of at least 1000. Lower molecular weight polyols are practically unsuitable because of insufficient retarding effect. The incorporation into the Polyuretlianstruktur affects according to the invention particularly advantageous in contrast to other non-installable retarders on the final properties of the formed molding material. The amount of polypropylene glycol used depends on the starting reactivity of the polyurethane mixture and the desired rate of retardation of the service life and is between 5 and 40% based on the polyol component. For the purposes of this invention, the term "polyol component" means the sum of the liquid constituents in the polyurethane reaction mixture which carry isocyanate-reactive groups. The concomitant use of inventive polypropylene glycol often also leads to an improvement in the toughness of the cured polyurethane molding material. For the polyol component for tough and hard polyurethanes a variety of compounds known per se and mixtures thereof can be used which carry isocyanate-reactive groups. In the case of hydroxyl-containing compounds, these are in particular short-chain diols and higher-functional compounds, synthetic polyethers and polyester alcohols and hydroxyl-containing natural substances or their reaction products with hydroxyl-containing compounds. The polyol component can also include compounds with other isocyanate-reactive groups, such as. B. triol or amino groups.

To obtain non-cellular tough and non-cellular hard polyurethanes, the polyol component should have an average hydroxyl number of at least 150 mg KOH / g. To determine the average hydroxyl number, all isocyanate-reactive groups are to be calculated as OH groups. Polyol blends having an average hydroxyl number of about 159 to 250 mg KOH / g and / or low degree of branching give toughened polyurethanes. Those having a higher hydroxyl number and / or a higher degree of branching give hard polyurethanes, the transition being fluid, and therefore a precise delineation can not be made.

The isocyanate component used for the process according to the invention are those which at least partially contain diphenylmethane diisocyanate and / or its reaction products. Diphenylmethandiisocyanathaltige isocyanate components are known to be prepared by phosgenation of condensation products of aniline and formaldehyde, wherein the phosgenation still further process steps, such. As purification steps, reactions with reactive compounds, thermal aftertreatments or mixing with other isocyanates and additives can be followed. The polyurethane mixtures may be added to the economic design of the process and to adjust certain properties, where appropriate known per se auxiliaries and additives. These are z. As fillers, dyes, solvents, plasticizers, catalysts, stabilizers, thixotropic agents, flame retardants, drying agents, adhesives, release agents, defoamers.

For the process of the invention, it is irrelevant whether the individual starting materials are premixed and processed in the form of two-component systems or multicomponent and whether the application is carried out at room temperature at higher or lower temperatures

 The invention will be explained in more detail below with reference to some embodiments:

embodiments Exemplary embodiment 1

The polyurethane raw materials of the positions I to 5 listed in Table 1 below are premixed according to the parts by weight according to Examples 1 to 6 to one component. After addition of the isocyanate component (position 6), the service lives indicated in Table 1 are measured.

Table 1

raw material 1 15 2 15 example 5 15 6 15 Based on polyether alcohol 3 4 position Sucrose, glycerol, parts by weight 1 propylene oxide, 15 15 OH number 470 mg KOH / g 85 80 55 45 castor oil OH number 162 mg KOH / g - 5 30 40 2 Polypropylene glycol with a 75 65 average molecular weight of 1 100 3 OH number 102 mg KOH / g 10 20

raw material 1 5 2 5 3 5 example -3- 5 5 279 582 5 Zeolite desiccant 0.1 0.1 0.1 4 0.1 0.1 acetylacetone 50 49 48 parts by weight 46 6 44 position Crude product of the diphenylmethane 5 4 diisocyanate C, 1 5 NCO equivalent weight 47 6 135g / Val characteristic value 208 205 202 188 181 Mean OH number of the polyol component (MgKOH / g) (Calculated) 85 100 140 195 240 360 Service life (dripping time) (Min) 160

Embodiment 2

The procedure is analogous to Example 1. Deviating from this, an isocyanate-containing reaction product of diphenylmethane diisocyanate, tolylene diisocyanate and dipropylene glycol having an isocyanate equivalent weight of 175 g / Val in an amount of 1.3 times that of Examples 1 to 6 is used as the isocyanate component (position 6). The measurement of the service life gave, in the order according to Examples 1 to 6, the following values (min): 105,120,140,155,170,190.

Exemplary embodiment 3

This embodiment shows the possibility of compensating for the flexibilizing effect of the polypropylene glycol of the invention without losing the desired effect of prolonging the service life. The polyurethane raw materials of position 1 to 5 listed in Table 2 below are premixed according to the parts by weight according to Examples 1 to 6 to one component. At the same time, as the proportion of the polypropylene glycol (position 3) according to the invention increases, the proportion of the highly branched polyether alcohol (position 1) is increased so that the OH number of the polyol component remains constant. After addition of the isocyanate component (position 6), the service lives indicated in Table 2 are measured, and test specimens are poured, at which, after curing, mechanical characteristics are determined.

Table 2

raw material 1 10.0 2 11.7 3 example 16.7 5 20.0 6 23.3 Polyether alcohol based on 4 position Sucrose, glycerol, parts by weight 1 propylene oxide, 13.3 OH number 470 mgKOH / g 90.0 83.3 63.3 50.0 36.7 castor oil OH number 162 mg KOH / g 0 5.0 20.0 30.0 40.0 2 Polypropylene glycol with a 76.7 average molecular weight 3 from 1930 OH number 58 mg KOH / g 5.0 5.0 10.0 5.0 5.0 5.0 Zeolite desiccant 0.1 0.1 0.1 0.1 0.1 acetylacetone 50.0 50.0 50.0 50.0 50.0 4 Crude product of the diphenylmethane 5.0 5 diisocyanate 0.1 6 NCO equivalent weight 135 g / Val 50.0 characteristic value 193 193 193 193 193 Mean OH number of the polyol component (mg KOH / g) (Calculated) 80 95 193 150 205 265 Service life (pot life) (Min) 45 48 44 41 39 Hardness Shore D 3.7 6.5 105 5.5 5.2 5.2 Bending stress (MPa) 45 5.4

-4- 279 S82

Embodiment 4

10COg of a commercially pre-prepared polyol additive component (component A) consisting of 200g castor oil, 200g synthetic Polyethfiralkohol (OH number 470mg KOH / g), 50g zeolite A4 powder, 48g color pigment (iron oxide red), 2g acetylacetone and 500g barytes with a average OH number of the polyol component of 315 mg KOH / g are mixed with 200 g of polypropylene glycol having an average molecular weight of 2000 (OH number 56 mg KOH / g). Using the commercial isocyanate component (component B) consisting of the crude product of diphenylmethane diisocyanate (NCO equivalent 135g / Val), the service life is determined in the mixing ratio of component A to component 3 as 3 to 1. The service life is 62 minutes. Without the addition of the polypropylene glycol according to the invention, the service life is only 37 minutes.

Claims (1)

Process for the preparation of polyurethane systems with long service life, consisting of a polyol component having an average hydroxyl value of at least 150 mg KOH / g and containing a retarding agent, an isocyanate component containing at least partially diphenylmethane diisocyanate and / or its reaction products, and - where appropriate, auxiliaries and additives are prepared and suitable for the production of non-cellular toughened or non-cellular hard polyurethane compositions, characterized in that ₍ based on the polyol component thereof ₍ 5 to 40% polypropylene glycol as a retarding agent having an average molecular weight of at least 1,000, are added.