Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Utility Patent
1999-05-14
2001-01-02
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S051000, C521S103000, C521S106000, C521S120000, C521S121000, C521S122000, C521S128000, C521S130000, C521S170000, C521S172000, C521S174000, C528S044000, C528S085000
Utility Patent
active
06169124
ABSTRACT:
Production of self-releasing, compact or cellular moldings which comprise polyisocyanate polyaddition products and may contain reinforcing material, and internal mold release agents for this purpose.
The present invention relates to a process for producing self-releasing, compact or cellular moldings which comprise polyisocyanate polyaddition products and may contain reinforcing material by reacting
a) organic or modified organic polyisocyanates with
b) compounds containing at least two reactive hydrogen atoms and having a molecular weight of from 62 to 10,000 and, if desired,
c) chain extenders and/or crosslinkers in the presence of
d) internal mold release agents and in the presence or absence of
e) catalysts,
f) blowing agents,
g) reinforcing materials and
h) auxiliaries
in an open or closed mold, wherein the internal mold release agents (d) used are diesters and/or monoesters of alkylsuccinic acids and/or diesters and/or monoesters of alkenylsuccinic acids, and the use of the alkylsuccinic and/or alkenylsuccinic diesters or monoesters as internal mold release agents for moldings comprising polyisocyanate polyaddition products.
The production of moldings comprising compact or cellular polyisocyanate polyaddition products which may contain reinforcing material, for example compact or cellular elastomers containing urethane and/or urea groups, known as polyurethane (PU) elastomers, and flexible, semirigid or rigid foams containing urethane and urea groups and possibly isocyanurate groups, known as PU or polyisocyanurate (PIR) foams, by reacting organic and/or modified organic polyisocyanates with relatively high molecular weight compounds containing at least two reactive hydrogen atoms, eg. polyoxyalkylenepolyamines and/or preferably organic polyhydroxyl compounds having molecular weights of, for example, from 500 to 12,000, and, if desired, low molecular weight chain extenders and/or crosslinkers in the presence or absence of catalysts, blowing agents, auxiliaries and/or additives in an open or closed mold is known from numerous patent and literature publications. Appropriate selection of the formative components, eg. the organic polyisocyanates, the relatively high molecular weight compounds containing hydrogen atoms which react with NCO groups and possibly chain extenders and/or crosslinkers enable elastic or rigid, compact or cellular moldings comprising polyisocyanate polyaddition products and also all modifications lying between these to be produced by this procedure.
An overview of the production of moldings comprising, for example, cellular or compact PU cast elastomers, PU elastomers, PU foams, PIR foams, etc., their mechanical properties and their use is given, for example, in the Kunststoff-Handbuch, Volume VII, “Polyurethane”, 1st edition, 1966, edited by Dr. R. Vieweg and Dr. A. Höchtlen, 2nd edition, 1983, edited by Dr. G. Oertel and 3rd edition, 1993, edited by Dr. G. W. Becker and Dr. D. Braun (Carl-Hanser-Verlag, Munich, Vienna) and “Integralschaumstoffe”, edited by Dr. H. Piechota and Dr. H. Rohr (Carl-Hanser-Verlag, Munich, Vienna, 1975).
Although the production of compact or cellular, elastic or rigid PU or PIR moldings has achieved extraordinary industrial importance, the processes described also have technical deficiencies owing, for example, to the excellent adhesion of polyurethanes to other materials. A particular disadvantage is that the PU moldings adhere to the molds and are therefore difficult to remove therefrom, which frequently leads to damage to the molding, in particular to its surface. To avoid this disadvantage, use is generally made of polished metal molds, and/or the internal surfaces of the molds are sprayed before production of the moldings with an external mold release agent, for example a product based on wax, soaps or oil or a silicone oil. This method is not only time-consuming and costly, but can also, particularly in the case of silicone-containing mold release agents, lead to considerable problems in applying a surface coating.
To improve the self-releasing properties in the production of PU moldings, particularly PU-polyurea moldings by the RIM technique, “internal” mold release agents have been developed.
According to EP-A-0 153 639 (U.S. Pat. No. 4,581,387), PU-polyurea moldings are produced by the RIM technique using internal mold release agents comprising carboxylic esters and/or carboxamides which are prepared by esterification or amidation of a mixture of montanic acid and at least one aliphatic carboxylic acid having at least 10 carbon atoms with at least difunctional alkanol-amines, polyols and/or polyamines having molecular weights of from 60 to 400.
According to U.S. Pat. No. 4,519,965, internal mold release agents used in reaction injection molding are mixtures of at least one zinc carboxylate having from 8 to 24 carbon atoms in the carboxyl radical and nitrogen-containing polymers which react with isocyanate groups to improve the compatibility of the zinc carboxylate with the formative components used for polyurethane-polyurea production.
EP-A-0 255 905 (U.S. Pat. No. 4,766,172) describes a mold release composition and a process for producing elastic moldings, which mold release composition comprises a solution which is liquid at room temperature of a zinc salt of a higher aliphatic carboxylic acid in selected tertiary amino compounds of the formula R
1
R
2
N(CH
2
)
m
NR(CH
2
)
n
NR
3
R
4
.
According to DE-A-36 31 842 (U.S. Pat. No. 4,764,537), internal mold release agents for producing moldings by the polyisocyanate polyaddition process comprise at least one ketimine, aldimine, enamine and/or a cyclic Schiff base, at least one metal salt of an organic carboxylic acid having from 8 to 24 carbon atoms and at least one organic carboxylic acid, organic sulfonic acid, mineral acid or amidosulfonic acid. These mold release compositions display excellent release properties in essentially compact moldings containing urethane and urea groups and rigid polyurethane integral foams produced by the RIM technique.
However, disadvantages are that the moldings containing urethane groups and produced using chain extenders based on low molecular weight polyhydric alcohols and/or polyoxyalkylene polyols cure relatively slowly and have to be treated with 1,1,3-trichloro-ethane vapor to remove the grease before application of a surface coating.
To eliminate this disadvantage, elastic, essentially compact polyurethane moldings as described in EP-B-0 262 378 and DE-A-39 04 810 and flexible moldings containing urethane groups and having a compact surface zone and a cellular core as described in DE-A-39 04 812 are produced using an internal mold release agent comprising a mixture of at least one organic amine and at least one metal salt of stearic acid or a mixture of at least one organic amine, at least one ketimine and at least one metal salt of stearic acid in combination with at least one organic monocarboxylic and/or dicarboxylic acid or anhydride. An advantage of these processes is that the PU moldings produced require no surface treatment with 1,1,3-trichloroethane vapor. However, it has the disadvantage that large-area moldings, in particular those having complicated three-dimensional shapes, can be produced only with difficulty since the flow path of the reaction mixture is relatively short so that large-volume molds, particularly those having thin hollow spaces and narrow flow channels, are frequently filled only insufficiently or not at all at certain points.
Selection of the optimum mold release agent in each case usually requires not only a knowledge of the starting materials in the PU or PU-polyurea formulation, eg. the presence or absence of zinc stearate, sterically hindered aromatic diamines, polyoxyalkylene-polyamines, blowing agents, etc., but also the type of mold material, the nature of its surface and the mold geometry and also the arrangement of the filling openings. In most cases, the selection of the best mold release agent requires experimental optimization.
Further external and/or internal mold release agents for
Horn Peter
H{umlaut over (a)}berle Karl
Kistenmacher Axel
Partusch Georg
Scherzer Dietrich
BASF - Aktiengesellschaft
Borrego Fernando A.
Cooney Jr. John M.
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