Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2001-03-16
2002-09-10
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C524S779000, C528S064000, C528S076000, C528S077000, C528S078000, C264S328100
Reexamination Certificate
active
06448364
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a process for the production of a RIM part which exhibits improved mold release capabilities due to an internal mold release (IMR) agent and provides a molded part that is readily paintable. This process comprises reacting a specific reaction mixture which contains a polyisocyanate component with an isocyanate-reactive component, potassium halide, an internal mold release agent and a catalyst via the one-shot process as an isocyanate index of from 90 to 120.
Internal mold release agents used in the production of molded polyurethane and polyurea products are known. U.S. Pat. Nos. 4,201,847 and 4,254,228 describe an internal mold release which is the reaction product of an organic polyisocyanate and an active hydrogen containing fatty acid ester. U.S. Pat. No. 4,111,861 describes four different classes of internal mold releases; i) mixtures of aliphatic or aryl carboxylic acid and a polar metal compound; ii) carboxyalkyl-siloxanes; iii) aliphatic glyoximes; and iv) aralkyl ammonium salts. Other known release agents include salts of acids (such as oleic acid) and primary amines (see, U.S. Pat. No. 3,726,952), reaction products of long chain fatty acids and ricinoleic acid (see, U.S. Pat. No. 4,058,492), and salts of acids (such as oleic acid) and tertiary amines (see, U.S. Pat. No. 4,098,731).
Zinc carboxylates containing from 8 to 24 carbon atoms per carboxylate group have also been described (U.S. Pat. Nos. 4,519,965, 4,581,386, 4,585,803 and 4,764,537, and British Patent 2,101,140). Release agents containing zinc carboxylates in combination with primary or secondary amine compatibilizers and an organic material containing a carboxylic acid group, a phosphorous containing acid group or a boron containing acid group, are described in published European Patent Application 0,119,471.
U.S. Pat. No. 3,875,069 discloses lubricant compositions which are said to be useful in the shaping of thermoplastic materials, These lubricant materials comprise (A) mixed esters with hydroxyl and acid numbers of 0 to 6 and (a) alkane polyols, (b) a dicarboxylic acid, and (c) aliphatic hydrocarbon monocarboxylic acids, said mixed esters having a molecular weight of at least 524; and (B) esters selected from the group consisting of (1) esters of the dicarboxylic acids of (A)(b) and aliphatic monofunctional alcohols, (2) esters of aliphatic monofunctional alcohols and aliphatic hydrocarbon monocarboxylic acids, and (3) complete esters or partial esters of alkanepolyols and aliphatic hydrocarbon monocarboxylic acids, with the ratio of by weight of (A) to (B) being from 1:3 to 9:1.
U.S. Pat. Nos. 5,389,696 and 5,500,176 describe processes for the production of molded products using internal mold release agents. These processes comprise reacting a reaction mixture of an organic polyisocyanate, and at least one organic compound containing isocyanate-reactive hydrogen atoms, in the presence of a catalyst and the IMR in a closed mold. Suitable IMRs comprise a) mixed esters comprising the reaction product of i) aliphatic dicarboxylic acids, ii) aliphatic polyols, and iii) monocarboxylic acids with 12 to 30 carbon atoms in the molecule. In U.S. Pat. No. 5,389,696, the IMR may additionally comprise b) a compound comprising the reaction product of i) N,N-dimethylpropylene diamine with ii) a compound selected from the group consisting of tall oil, C
8
-C
20
monofunctionalic carboxylic acids, and mixtures of C
8
-C
20
monofunctional carboxylic acids; and c) a compound comprising the reaction product of oleic acid, adipic acid and pentaerythritol. In U.S. Pat. No. 5,500,176, the reaction mixture may additionally include a fatty acid such as oleic acid. Molded parts having a density of 0.25 to 1.25 g/cc are described by U.S. Pat. No. 5,389,696 and molded parts having a density of 1.3 to 2.0 g/cc are described by U.S. Pat. No. 5,500,176.
Internal mold release systems for SRIM processes are also described by U.S. Pat. No. 5,670,553. These comprise (a) a carboxylic acid and (b) a compound selected from the group consisting of a fatty polyester, a fatty acid ester and a fatty amide. Suitable fatty polyesters comprise the reaction product of (i) aliphatic dicarboxylic acids, (ii) aliphatic polyols and (iii) fatty monocarboxylic acids wherein the monocarboxylic acid contains from about 12 to 30 carbon atoms. These preferably comprise (i) adipic acid, (ii) pentaerythritol, and (iii) oleic acid.
Improved thermal break systems utilizing a NCO prepolymer of a polyisocyanate and optimization of the % NCO or urethane content of the NCO prepolymer to obtain optimum impact properties or reduced brittleness of the final urethane are described by U.S. Pat. No. 5,137,788. This patent described homogeneously storable mixtures which produce shrink stable urethanes having good adhesion properties with respect to metal substrates. These homogeneously storable mixtures comprise a small quantity of a potassium halide in a mixture of (a) polyoxyalkylene polyols, polyolamines and/or polyamines having molecular weights of 400 to 12,000 and a functionality of at least about 2.0, with (b) low molecular weight polyols containing at least two hydroxyl groups and having a molecular weight of from 62 to 399. At least one compound in group (a) must have a functionality of at least about 3 in a quantity such that the total functionality of the polyol mixtures is at least about 3.
The present invention is directed to molded products made using the reaction injection molding (RIM) process. The materials are elastomeric in nature and comprise an IMR and stabilizing agents. The elastomer compositions are designed to exhibit extended gel times of 5-20 seconds. This reaction time is much longer than typical RIM elastomer systems, being 0.9 to 1.4 seconds. This reaction time allows longer pour times but also excludes the use of historically known IMRs for release improvements due to their negative effect on activity or release. Therefore, the objective of the present invention was to find a composition that would provide the same release performance as existing technology yet offer a greater processing window and larger molded part application opportunities with existing equipment. It has been found possible by the use of an isocyanate-reactive component capped with polyethylene oxide and an internal stabilizer IMR package which synergistically works together to give release performance comparable to historic performance while maintaining extended gel reactivities.
Advantages of the present invention include easier release of parts from a mold as well as multiple releases of parts without reapplication of external release agents between moldings while maintaining the extended reaction times the elastomer has with the use of this synergistic IMR package.
SUMMARY OF THE INVENTION
This invention relates to a process for the production of a polyurethane elastomer from a reaction mixture by the reaction injection molding process. Suitable reaction mixtures for this process comprise:
(A) an isocyanate-reactive component containing at least two isocyanate-reactive groups, having a molecular weight of from 400 to 12,000, a functionality of from about 2 to about 8, and being capped with from about 13 to about 21% by weight (based on 100% by weight of the alkylene oxide groups) of ethylene oxide, wherein said isocyanate-reactive groups being selected from the group consisting of hydroxyl groups, amine groups, and mixtures thereof;
(B) an isocyanate-reactive component comprising:
(1) an isocyanate-reactive component containing at least two hydroxyl groups and having a molecular weight of from 62 to 399, and
(2) an isocyanate-reactive component selected from the group consisting of:
(a) an isocyanate-reactive tertiary amine polyether having a functionality of at least two and a molecular weight of 62 to 399 and corresponding to the general formula:
R(NR
1
R
2
)
m
wherein:
R: represents a saturated or unsaturated C
2
-C
8
aliphatic or C
2
-C
8
aliphatic substituted with —OH, —SH, or —NHR
a
wherein R
a
i
Clatty Jan L. R.
Harasin Stephen J.
Wellman Michael T.
Bayer Corporation
Brown N. Denise
Gil Joseph C.
Gorr Rachel
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