MXPA99004665A - Two step procedure for the production of semi-hard solid polyurethane moulded bodies - Google Patents

Abstract

The invention relates to a procedure for the production of solid, transparent to translucent, polyurethane moulded bodies which can be used, for instance, as an alternative material to rubber on account of their elastic and optical properties.

Description

Two-step process for the production of semirigid solid polyurethane moldings The invention relates to a process for • production of solid polyurethane moldings, from transparent to translucent, which due to their elastic and optical properties can be used, for example, as an alternative material to rubber. For the production of transparent semi-rigid PU moldings, PUR reaction masses based on polyester polyols are usually used. They are especially suitable for the production of castings according to a casting process and / or the injection process, since with these good results are obtained, with a large interval in the variation of the system, in terms of hardness of the material and hardening time. I lie. In general, large requirements are not necessary in terms of machinery, filling, mold and mold closing techniques, although they may be necessary in some cases. The use of PUR reaction masses based on polyether polyols is also known, although in general they are not chosen because only a high degree of satisfactory and continuous transparency can be obtained with high requirements in terms of technical installations. For this purpose, only the production according to the RIM procedure with the reaction masses, which REF .: 30144 present reactive hydroxy and amine end groups, as well as the adoption of special molding and closing apparatuses, as described in EP 0 299 117 Al. Finally, the use of PUR molding compositions based on polyether polyols always offered only a small processing window, so that it was preferred instead to use PUR systems based on polyester-polyols. These are surprisingly also used, when it comes to applications in exposed areas, in which often only the hydrolytic-microbial decomposition of the ester components is prevented by the application of very expensive protective additives. It has now been surprisingly discovered that polyurethane-based PUR molding compositions can be processed in the same way to give transparent / translucent moldings, such as those based on esters, when in a first step of the process it is achieved that they have a molecular weight medium higher and with it a higher viscosity. As a step of the process of this type, the reaction with components having di- and / or polyfunctional isocyanate end groups to give the so-called OH-prepolymers is particularly suitable as described below. A reaction with di and / or polyfunctional carboxylic acids to ether / ester polyols of comparable length is also shown to be suitable. The object of the present invention is a two-step process for the production of compact and transparent PUR moldings according to the polyaddition process of polyisocyanates with a hardness of 40 to 90 Shore A through the reaction of a) organic and / or organic polyisocyanates modified with b) at least one high molecular weight compound with at least two reactive hydrogen atoms and optionally c) chain extenders and / or low molecular weight crosslinkers in the presence of d) catalysts and e) adjuvants and additives characterized in that as high molecular weight compound with at least two reactive hydrogen atoms, reacts at least (b) the reaction product of (I), a linear EO / PO polyetherpolyol with terminal EO groups and with an EO / PO ratio of between : 85 and 40:60, with an OH number between 56 and 28 and a functionality of 2.0, or (II) a mixture of a polyetherpolyol as mentioned in (I) with another polyetherpolyol of EP / PO, but with higher functionality and initiated for example with glycerin, trimethylolpropane, pentaerythritol or also sugar (EO / PO ratio between 15:85 to 40:60) with an OH index between 60 and 25 or (III) mixtures of several linear and branched polyether polyols, as described in (I) and (II), or (IV) reacts a poly-THF-ether (C4 ether) with an average molecular weight between 500 and 2000 as well as (V) combinations of (I), (II) ), (III) and (IV) with (A) TDI, (2,4-TDI to 2,6-TDI in any proportion), as well as the prepolymers that can be obtained from them, or (B) isocyanates TDI polynuclear, as well as the prepolymers that can be obtained from them, or (or MDI (4,4'-MDI, 2, 4"-MDI, 2, 2 '-MDI in any proportion), as well as the prepolymers that can be obtained from them, or (D) polynuclear isocyanates of MDI, as well as the prepolymers that can be obtained from them, (E) the rest of aromatic isocyanates that can be obtained on an industrial scale, with a functionality of at least 2 (NDI, p-PDI), as well as the prepolymers that can be obtained from them, (F) the rest of aliphatic isocyanates that can be obtained on an industrial scale, with a functionality of at least 2 (IPDI, HDI, H-MDI), as well as the prepolymers that can be obtained from them, O (G) the isocyanate mixtures of (A) to (F).

The prepolymers mentioned in (A) to (G) are obtained by reaction of the isocyanates with an etherpolyol as described in (I) to (V) and are characterized by their terminal NCO reactive groups. It is also possible to react the polyols described in (I) to (V) instead of isocyanates with (AA) di and / or polyfunctional carboxylic acids, such as, for example, adipic acid, glutaric acid, succinic acid and other representatives of this class of substances, as well as their mixtures. In addition, "short-chain" reaction components, such as H20, di-OH and trifunctional compounds, OH-amines, di and triamines, etc. can be used. in a previous reaction and react them jointly, being able to selectively modify the characteristics of the polyurethane material that will react next. The course of the first step of the reaction to give the polyol, as described above, does not require a catalytic acceleration in the case of the reaction of the diol, etc., but after the addition of amines, metal salts, takes place with diisocyanate. , etc. considerably faster. In the case of the ether-ester reaction (AA), the typical ester catalysts (Sn and Ti derivatives) are preferred. The reaction temperatures are preferably between 20 and 100 ° C (Type A-G), although higher temperatures are also possible, being more advantageous in the situation (AA). The OH number resulting from the reaction product mentioned above is between 7 and 50 mg KOH / g, between 10 and 28 mg KOH / g is preferred. The viscosity of the starting material increases considerably with the process in the ranges of use of the usual temperatures from 20 to 50 ° C. Since, as mentioned, elements containing hydroxy terminal groups and low molecular weight amine, including H20, can be used in the above reaction described, the reaction can also be initiated with a higher content of OH or OH / groups. NHX It is possible to modify the viscosity correspondingly.

Examples 1. Example of prepol mero-OH Example table 1. 1 Realization: Once the components are placed with OH and the temperature adjusted to 50 ° C, the amount of Dabco is dissolved and then the isocyanate components are added. After about 2 hours, the viscosity is determined, which is at the same level without modification after 1 d and 7 d. Likewise, it is also possible to proportionally arrange the components with reactive OH, so that a concentrated reaction mixture is obtained to which the Dabco and the isocyanate component are also added at 50 ° C. After the reaction has been carried out, the rest of the components are added with reactive OH and a product prepared in the same manner as with procedure 1.1 is obtained.

Reaction example The unreacted base polyol (a) in Table 1 is reacted with the following coreactants: Component A: Polyol (a) 93.87 1, 4 -Butanodiol 6.00 DBTL 0.03 Dabco (crist) .) 0.10 Component B: MDI prepolymer of 4, 4 '- DI, CD demodor and etherpolyol (a) with an NCO content of 20% Temperature of the materials: each 35 ° C The mixture A: B in one 100: 38 ratio is processed with a usual low pressure machine and poured into a mold and closed. The molded part, with a material thickness of 5 mm and a density of 1100 kg / m3, can be removed from the mold after 4 minutes, although it is not transparent, but is cloudy white. 2.2 The reaction product of Example 1.1 is used in the previous recipe. Proceeding in the same way and taking into account the lower OH number of the prepolymer with OH that has been used here (A: B = 100: 36), a transparent molded part can be obtained after 4 minutes. 2.3. As a variant of the recipe for the process of direct formation of soles, the following variant is used: Component A: Polyol (a) 92.97 1, 4 -Butanodiol 6.00 Ethanodiol 0.50 DBTL 0.03 Dabco (crist. ) 1,00 Component B: (see example 2.1) Temperature of the materials: each 35 ° C The reaction mixture produced according to the Desma procedure by screw mixing (A: B = 100: 41) is taken to a mold with a temperature of approximately 50 ° C and the mold is closed according to the Desma procedure. After approximately 2.5 minutes, the mold is opened and a cloudy white molding is obtained, on which another PUR material can be injected in a subsequent step. As described in 2.3, when the polyol (a) is exchanged for the polyol (1.1) with a regulated mixing ratio afterwards (A: B = 100: 39) after 2.5 minutes a mold part can be removed from the mold. transparent on which another PUR material can also be injected in a subsequent step. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (1)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property:. Two-step process for the production of semirigid solid polyurethane moldings, which have a high transparency even with different thicknesses of the molded part, by reaction of a) (poly) organic and / or organic isocyanates modified with b) an ether polyol, as described in (I) - (V), which in a first step reacts with reactive OH reactants, as aromatic and aliphatic isocyanate derivatives, giving an OH prepolymer containing OH end groups, with c) chain extenders and / or low molecular weight crosslinkers in the presence of d) amine and / or metal catalysts and e) adjuvants and additives characterized in that the prepolymer OH (b) has an OH number of 7. at 56 mg KOH / g and does not contain any reactive NCO group. . Process according to claim 1, characterized in that component b) contains short chain reaction components, such as H0, di and trifunctional compounds-OH, OH-amines, di and triamines, which can also enter the reaction forming prepo-limeros- OH. Process according to claim 1, characterized in that the component b) is produced with the aid of amine catalysts and / or metal salts. Process according to claim 1, characterized in that component b) is the reaction product of an ether polyol and a di- and / or polyfunctional carboxylic acid, which does not contain free reactive carboxylic groups. Process according to claim 1 for the production of shoe soles, shoe soles elements, industrial sealing gaskets and rolling bodies subject to mechanical stress.