Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-09-28
2003-07-01
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S591000, C524S839000, C428S364000, C428S378000, C427S389700
Reexamination Certificate
active
06586523
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to self-crosslinking polyurethane, polyurethane-polyurea or polyurea dispersions, a process for the preparation of such dispersions, and to the use thereof.
BACKGROUND OF THE INVENTION
The use of polyurethane dispersions, e.g., for the preparation of glass fibre sizes is known, e.g., from U.S. Pat. No. 4,255,317. Similarly, the use of hardener components based on blocked polyisocyanates in combination with polyurethane dispersions is known, e.g., from EP-A 792 900. Self-crosslinking dispersions are not described therein.
Aqueous PU dispersions with isocyanate groups blocked with butanone oxime and with diamine mixed in, e.g., isophorone diamine, are described in U.S. Pat. No. 4,387,181, but not the use of said dispersions as size. Rather, a special preparation process is described wherein the dispersion, which contains the blocked isocyanate groups, undergoes chain extension, e.g., for 12 hours at 70° C. by reaction with the diamine. High molecular weight dispersions are thereby obtained in which no subsequent crosslinking is possible. The dispersions are less suitable for use in glass fibre sizes.
Paint dispersions are described in U.S. Pat. No. 5,563,208, wherein curing is carried out with a polyamine on the substrate. Relatively low molecular weight prepolymers with blocked isocyanate groups in an approximately trifunctional structure are described here, this being substantiated by the use of the polyisocyanates used by way of example such as crude MDI or isocyanurate group-containing paint polyisocyanates based on 1,6-diisocyanatohexane. No indication is given of the suitability of such products for sizes. In view of the considerable branching and high crosslinking density, the products are unsuitable for sizes and the reinforcing properties are insufficient.
U.S. Pat. No. 5,300,556 describes a process for the preparation of aqueous dispersions containing blocked polyisocyanates and polyhydroxyl compounds. A hydrophilic polyisocyanate is reacted with blocking agent in the presence of polyhydroxyl compounds in aqueous dispersion. It is necessary in this case to use blocking agents which have a greater reactivity than water and the polyhydroxyl compound. This means the opportunities for improvement are considerably restricted and also makes implementation on an industrial scale extremely difficult since an isocyanate-water reaction can never be ruled out altogether. Similarly, no indication of the suitability of such products for sizes is given.
SUMMARY OF THE INVENTION
Surprisingly, it has now been found that glass fibre sizes containing special self-crosslinking polyurethane, polyurethane-polyurea or polyurea dispersions exhibit markedly improved processability with sized glass fibres and improved mechanical properties of corresponding glass fibre-reinforced plastics.
The term self-crosslinking dispersions means those dispersions that contain polyurethanes, polyurethane-polyureas or polyureas with blocked isocyanate groups and reactive hydroxyl or amino groups in the same polymer and/or blocked isocyanate groups in the polymer and, in addition, diamines, polyamines and/or hydroxyamines. The presence of blocked isocyanate groups and reactive hydroxyl or amino groups in the same monomer leads, surprisingly, to improved properties as regards reinforcing properties and resistance to hydrolysis, and the processing properties such as, e.g., bulk density.
It was also found that such dispersions also offer some other advantages for the user. The expense of the separate storage of dispersion and hardener is dispensed with, problems or inadequate size properties which may arise due to inaccurate mixing of dispersion and hardener are avoided. No compatibility problems arise of the kind that can occur between different dispersions and hardeners either during the mixing stage or during the elevated temperatures during application.
The invention provides, therefore, self-crosslinking dispersions based on polyurethanes, polyurethane-polyureas or polyureas which contain blocked isocyanate groups bound to the polymer and, also bound to the polymer, reactive hydroxyl or amino groups and/or up to 10 wt. % of a reactive component comprising at least one diamine, polyamine or hydroxyamine having a molecular weight from 60 to 1000, are stable in storage up to 50° C. and react at 90 to 280° C. with crosslinking.
DETAILED DESCRIPTION OF THE INVENTION
For the sake of simplicity, the polyurethane, polyurethane-polyurea or polyurea dispersions according to the invention are also referred to below as polyurethane dispersions or as dispersions, in which case polyurethane, polyurethane-polyurea and polyurea dispersions are always included. The term dispersion also includes dispersions which contain dissolved polymer proportions. The proportion of dissolved polymers may be influenced, e.g., by the content of hydrophilic components.
The self-crosslinking dispersions according to the invention based on polyurethanes, polyurethane-polyureas or polyureas are reaction products, present in the dispersed or dissolved form, of
a) at least one polyol component,
b) at least one di-, tri- and/or polyisocyanate component,
c) at least one hydrophilic, nonionic or (potentially) ionic structural component comprising compounds with at least one group which is reactive towards isocyanate groups and at least one hydrophilic polyether chain, and/or compounds with at least one group capable of salt formation optionally present at least in the partially neutralised form, and at least one group which is reactive towards isocyanate groups,
d) at least one structural component which is different from a) to c) having a molecular weight from 32 to 500 with at least one group which is reactive towards isocyanate groups, and
e) at least one monofunctional blocking agent,
wherein c) is used in a quantity such that a stable dispersion is obtained, wherein either a component d) is used in such a way that the resulting dispersion contains, in addition to blocked isocyanate groups, reactive free hydroxyl and/or amino groups, and/or wherein a component F) comprising at least one reactive diamine, polyamine and/or hydroxyamine is contained in the resulting dispersion, wherein the proportion of reactive hydroxyl or amino groups from d) and/or F) may not be 0.
The dispersions according to the invention based on polyurethanes, polyurethane-polyureas or polyureas are preferably reaction products of
a) 30 to 90 wt. % of at least one polyol component having a hydroxyl value from 5 to 350,
b) 10 to 50 wt. % of at least one di-, tri- and/or polyisocyanate component,
c) 1 to 20 wt. % of at least one hydrophilic, nonionic or (potentially) ionic structural component comprising compounds with at least one group which is reactive towards isocyanate groups and at least one group capable of salt formation optionally present at least in the partially neutralised form, or a hydrophilic polyether chain,
d) 1 to 20 wt. % of at least one structural component different from a) to c) having a molecular weight from 32 to 500 with at least one group which is reactive towards isocyanate groups,
e) 0.2 to 7.5 wt. % of at least one monofunctional blocking agent,
wherein c) is used in a quantity such that a stable dispersion is obtained, wherein either a component d) is used in such a way that the resulting dispersion contains, in addition to blocked isocyanate groups, reactive free hydroxyl and/or amino groups in quantities from 0 to 4 wt. % based on the solids content of the dispersion, and/or wherein 0 to 10 wt. %, based on the solids content of the dispersion, of a component F) comprising at least one reactive diamine, polyamine and/or hydroxyamine are contained in the resulting dispersion, wherein the proportion of reactive hydroxyl or amino groups from d) and/or F) may not be 0.
Particularly preferred dispersions according to the invention based on polyurethanes, polyurethane-polyureas or polyureas are reaction products of
a) 35 to 75 wt. % of at least one polyol component having a hydroxyl value from 5 to 350,
b)
Blum Harald
König Eberhard
Naujoks Karin
Bayer Aktiengesellschaft
Gil Joseph C.
Gorr Rachel
Mrozinski, Jr. John E.
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