CA1308225C - Process for the production of elastomeric molded articles based on polyisocyanate polyaddition products containing urea groups - Google Patents
Process for the production of elastomeric molded articles based on polyisocyanate polyaddition products containing urea groupsInfo
- Publication number
- CA1308225C CA1308225C CA000573499A CA573499A CA1308225C CA 1308225 C CA1308225 C CA 1308225C CA 000573499 A CA000573499 A CA 000573499A CA 573499 A CA573499 A CA 573499A CA 1308225 C CA1308225 C CA 1308225C
- Authority
- CA
- Canada
- Prior art keywords
- mold
- isocyanate
- reaction mixture
- reaction
- groups
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/30—Low-molecular-weight compounds
- C08G18/302—Water
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/08—Processes
- C08G18/10—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Polyurethanes Or Polyureas (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Molding Of Porous Articles (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
Abstract
PROCESS FOR THE PRODUCTION OF ELASTOMERIC MOLDED
ARTICLES BASED ON POLYISOCYANATE POLYADDITION
PRODUCTS CONTAINING UREA GROUPS
ABSTRACT OF THE DISCLOSURE
The present invention relates to a process for the production of elastomeric molded articles based on polyisocyanate polyaddition products containing urea groups by the reaction of a) a polyisocyanate component with b) compounds having a molecular weight of 500 to about 12,000 and containing at least two isocyanate reactive groups, c) water as chain lengthening agent and, optionally, d) organic compounds having a molecular weight of 60 to about 499 and containing at least two isocyanate reactive groups by the one-shot or prepolymer process, maintaining an isocyanate index of about 70 to 125, characterized in that (i) water is used in a quantity of at least 10 mole %
per equivalent of isocyanate groups in component a) and (ii) the reaction mixture prepared from the components is filled into an open mold by the casting process, the quantity introduced amounting to a least 95% of the volume of the molded, and the mold is subse-quently tightly closed so that the carbon dioxide produced by the reaction between water and isocyanate is virtually unable to cause expansion of the reaction mixture.
ted by the claims.
ARTICLES BASED ON POLYISOCYANATE POLYADDITION
PRODUCTS CONTAINING UREA GROUPS
ABSTRACT OF THE DISCLOSURE
The present invention relates to a process for the production of elastomeric molded articles based on polyisocyanate polyaddition products containing urea groups by the reaction of a) a polyisocyanate component with b) compounds having a molecular weight of 500 to about 12,000 and containing at least two isocyanate reactive groups, c) water as chain lengthening agent and, optionally, d) organic compounds having a molecular weight of 60 to about 499 and containing at least two isocyanate reactive groups by the one-shot or prepolymer process, maintaining an isocyanate index of about 70 to 125, characterized in that (i) water is used in a quantity of at least 10 mole %
per equivalent of isocyanate groups in component a) and (ii) the reaction mixture prepared from the components is filled into an open mold by the casting process, the quantity introduced amounting to a least 95% of the volume of the molded, and the mold is subse-quently tightly closed so that the carbon dioxide produced by the reaction between water and isocyanate is virtually unable to cause expansion of the reaction mixture.
ted by the claims.
Description
1 3082~
Mo-3050 LeA 25,384 PROCESS FOR THE PRODUCTION OF ELASTOMERIC MOLDED
ARTICLES BASED ON POLYISOCYANATE POLYADDITION
PRODUCTS CONTAINING UREA GROUPS
BACKGROUND OF THE INVENTION
5 Field of the Invention _ This invention relates to a new process for the production of elastomeric molded articles based on polyisoeyanate polyaddition products containing urea groups, in particular polyurethanes con~aining urea 10 groups and having a gross density above 1.0 g/cm3, wherein the urea groups required for obtaining the superior mechanical properties are primarily obtained by the reaction of organic polyisocyanates and water.
Description of the Prior Art The production of compact polyurethane elasto-mers containing urea groups by the two-stage process using water as chain lengthening agent is known (see, e.g. Kunststoff-Handbuch, Carl Hanser Verlag, 1966, Volume VII, pages 270-271). Due to the gaseous CO2 20 produced by the reaction of ~he isocyanate groups with water, production of these compact substances took place via the intermediate stage of the corresponding foams, which must first be compacted by rollers before they can be molded into noncellular elastomers.
As this process is very expensive due to the many individual steps involved, it is only suitable for products required for very speclal applications. One major disadvantage of this molding process is that i~
only enables plate goods or geometrically sîmple molded 30 parts to be produced.
At the same time, polyisocyanate polyaddition products which contain urea groups, in particular poly-LeA 25384-1 3~225 urethanes containing urea groups, have exceptionally desirable mechanical properties and the use of water as chain lengthening agen~ (instead of diamines) provides a particularly simple and inexpensive method of introduc-5 ing urea groups.
It was therefore an object of the present invention to provide a new process for the preparation of elastomeric polyisocyanate polyaddition products containing urea groups, in particular polyurethanes, 10 which makes use o the principle of using water as chain leng~hening agent without the disadvantages mentioned above.
This problem was solved by providing the process according to the invention described below, in 15 which elastomeric molded parts are produced by casting and water is used as chain lengthening agent. The molds, which are initially open, are filled to an extent of at least 95% and then tightly closed so that the reaction takes place under a sufficient pressure to 20 ensure that the gaseous carbon dioxide cannot cause the reaction mixture to foam up. It is surprisingly found that after ~he time required for curing, very flexible molded parts can be removed from the mold without undergoing any deformation due to the action of 25 dissolved carbon dioxide gas.
Although DE OS 3,407,931 discloses a process for the production of noncellular or microcellular molded articles based on polyurethanes containing urea groups, wherein organic polyisocyanates, compounds 30 containing isocyanate reactive groups and water are reacted together inside closed molds under a pre~sure preventing the formation of foam, this prior art process is carried out by the reaction inJectiOn molding ~ech-nique in which the starting components are mixed Mo 3050 _ ~ _ 1 30~225 together under a high pressure and introduced into a closed mold. The reaction injPction molding technique is one which is mainly used for the production of thin-walled molded par~s with short ~old residence 5 times. For the production of thick walled parts, the casting process using open molds has become established in prac~ice because large and bulky parts which are free from air bubbles in the interior can be produced much more easily by the casting process using reaction 10 mixtures which react slowly. It could not be deduced from the teaching of DE-OS 3,407,931 that the production of molded elastomer parts by the casting according to the process of the invention described below would be a suitable and feasible method of producing high quality 15 elastomers.
In US-PS 4,416,844 a process is described for the production of puncture-proof tires which are filled with an elastic reaction mass which is substantially free from bubbles, using water as chain lengthening 20 agen~. In this process, the formation of bubbles by the liberation of carbon dioxide gas is prevented by inject-ing the reaction mass into the tire carcass until the mass has built up a pressure of at least 25 psi (=1.7 bar) against the elasticity of the carcass. The 25 said prior publication gives no indication of the feasibility of carrying out the process according to the invention described below for the production of elastomeric molded parts by casting since in the prior publication the reaction mass remains in a pressure 30 stable cavity (carcass). Questions concerning the manufacture of the molded parts are not discussed.
SUMMARY OF THE INVENTION
The presen~ invention relates to a process for the production of elastomeric molded articles based on Mo 3050 - 3 -1 30~225 polyisocyanate polyaddition products containing urea groups by the reaction of a) a polyisocyanate component with b) compounds having a molecular weight of 500 to about 12,000 and containing at least two isocyanate reactive groups, c) water as chain lengthening agent and, optionally, d) organic compounds having a molecular weight of 60 to about 499 and con~aining at least two isocyanate reactive groups by the one-shot or prepolymer process, main~aining an isocyanate index of about 70 to 125, characterized in that ~i) water is used in a quantity of at least 10 mole %
per equivalent of isocyanate groups in component a~ -and (ii) the reaction mixture prepared from the components is filled into an open mold by the casting process, the quantity introduced amounting to a least 95Z of the volume of the molded, and the mold is subse-quently tightly closed so that the carbon dioxide produced by the reaction between water and isocya-nate is virtually unable to cause expansion of the reaction mixture.
DETAILED DESCRIPTION OF THE INVENTION
In the context of the present invention "poly-isocyanate polyaddition products" mean both pure poly-ureas and polyurethanes containing urea groups. The products of the process according to the invention are 30 preferably polyurethanes containing:urea groups.
The "one-shot process" is unders~ood in the context of the present invention to be a procedure in which components b), c) and d) are added together to form a "reactive component" which is then mi~ed with Mo-3050 - 4 -polyisocyanate component a) and brought to react in a single stage. Any auxiliary agents and additives used may be incorporated both with polyisocyanate component a) and with the "reactive component." The auxillary 5 agents and additives e) are preferably added to the "reactive component."
In the context of the present invention "prepol~mer process" means a procedure wherein polyiso-cyanate component a) is reacted with at least a portion 10 of component b) and optionally with a portion or all of component d) to provide a "prepolymer" containing isocyanate groups, which is then reacted with a mixture of component c), the remaining quantity of component b) and optionally component d). Different compounds within 15 the scope of components b) and d) may be used for the preparation of the prepolymer and for the chain extender mixture. In this variation of the process according to the invention, the optional auxiliary agents and additives e) may again be incorporated either with the 20 prepolymer or wi~h the aforesaid mixture, the latter variation being preferred.
"Isocyanate index" means the number of isocyanate groups present in the reaction mixture introduced into the mold per 100 isocyanate reactive 25 groups, water being included in the calculation as a difunctional compound.
The starting materials a) include any organic polyisocyanates having a molecular weight of up to 600, preferably up to 300. Aromatic diisocyanate~ are 30 preferably used. Examples of suitable polyisocyanates include 1,5-diisocyanatonaphthalene, 2,4'- and/or 4,4i-diisocyanatodiphenylmethane, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 2,4'-diisocyanatotoluene and commerciaI mixtures thereof with 2,6-diisocyanato-Mo-3050 - 5 -toluene, 1,4-diisocyanatobenzene and diisocyanates corresponding to the following formulae:
OCN- ~ (CH2)2 ~ NCO, OCN- ~ O-C ~ NCO
OCN - ~ C~2-CH2 ~ NCO and H3C - ~ NH-C- ~ 3 NCO NCO
(Cyclo)aliphatic diisocyanates such as isophorone diisocyanate, 1,6-diisocyanatohexane, trans- -1,4-cyclohexanediisocyanate, 4,4'-diisocyanato-dicyclo-10 hexylmethane or p-xylylenediisocyanate may also be used.
Carbodiimide- (uretoneimine-), isocyanurate-, urea-, urethane- and/or allophanate-modified derivatives of such diisocyanates are also suitable although they are generally less preferred.
Particularly suitable starting components b) include polyester and polyether polyols having a molecular weight of 500 to about 12,000, preferably about 900 to 6000 ~calcula~ed from the functionality and the hydroxyl group content) and any mixtures of such cOmpounds.
The polyhydroxyl compounds are preferably difunctional although they may be ba~ed on mixtures Mo-3050 - 6 -1 3f)~225 containing small proportions of higher functional polyhydroxyl compounds such that the average func-tionality of the mixtures is at most 2.5, preferably at most 2.3.
Suitable polyester polyols are obtained, for example, by the reaction of excess quantities of polyhydric alcohols with polybasic, preferably dibasic carboxylic acids or carboxylic acid anhydrides. The compounds mentioned in US-PS 4,218,543, column 8, lines 27 to 52, are examples of suitable carboxylic acids, carboxylic acid anhydrides and low molecular weight, polyhydric alcohols.
Polyether polyols suitable for the process according to the invention may be obtained, for example, by the known method of alkoxylating suitable starter molecules, in particular using ethylene oxide and/or propylene oxide, optionally as mixtures or in any sequence. Water, ethylene glycol, 1,2-dihydroxypropane, trimethylolpropane, and glycerine and any mixtures are examples of suitable starter molecules. Poly(oxytetra-methylene)glycols are also suitable. The particulars given above concerning the average functionality of the polyether polyols are also applicable here so that when trifunctional starter molecules such as trimethylol-25 propane or glycerine are used, the resulting trifunc-tional polyether polyols merely are mixed with difunc-tional polyether polyols.
In addition to or instead of the above mentioned polyester and/or polyether polyols, other relatively high 30 molecular weight compounds in the above~mentioned molecular weight range containing isocyanate reactive groups may be used as component b) in the process according to the invention~ Such M~-3050 - 7 -1 30~2~5 compounds include polyesters based on lactones ~such as poly--caprolactones) or ~-hydroxyalkane carboxylic acids (such as ~-hydroxycaproic acid), polycarbonate polyols, polyester amides and hydroxyl group-containing 5 polyacetals.
Polyether amines which are equally suitable as component b) may be prepared from the above mentioned polyether polyols by known processes, for example, by the process of cyanoalkylation of polyoxyalkylene 10 polyols followed by hydrogena~ion of the resulting nitrile (US-PS 3,267,050) or the amination of polyoxyalkylene polyols with amines or ammonia in the presence of water and catalys~s (DE-AS 1,215,373).
Polyether amines containing aromatically bound 15 amino groups linked to the polyether chain by urethane or ester groups are also suitable for use as component b). The preparation of such compounds may be carried out, for example, by the processes described in EP~A-79,536, DE-OS 2,948,419, DE-CS 2,019,432, DE-OS
20 2,619,840, US-PS 3,808,250, US-PS 3,975,426 or US-PS
4,016,143.
Component c) is water, which may be introduced either as such or in the form of inorganic or organic compounds which split off water such as Na2SO4.122O, 25 pinacone hydrate, molecular sieve zeolites charged with water, or acetaldoxime. The water is preferably used as such in liquid form.
The organic compounds d) optionally used have molecular weights of 60 to 499, preferably 62 to about 30 350. They are preferably compounds carrying two or three isocyanate reactive groups. Suitable compounds of this type include polyhydric aliphatic alcohols such as ethylene glycol, 1,2-dihydroxypropane, 1,3-dihydroxy-propane, 1,4-dihydroxybutane, 1,6-dihydroxyethane, Mo-3050 - 8 -1 30~3)25 trimethylolpropane and glycerine, the low molecular weight alkoxylation products of the above mentioned polyhydric alcohols such as diethylene glycol, triethylene glycol, dipropylene glycol and tripropylene glyco]; and any mixtures of such low molecular weight chain lengthening agents or crosslinking agents. Amino alcohols and alkoxylation products of aliphatic amines or hydrazine may also be used as component d). Examples include athanolamine, diethanolamine, triethanolamine, propanolamine and hydrazinoethanol. Finally, organic diamines having a molecular weight of 62 to 499 and containing at least two primary and/or secondary amino groups may be used as starting component d). Examples include 1l2-dlaminoethanel 1,6-diaminohexane, 2,4-diaminotoluene, 4,4'-diaminodiphenylmethane and in particular, aromatic diamines containing sterically hindered amino groups such as those disclosed in DE-OS
2,916,~85, page 17, line 26 to page 18, line 9 (U.S.
Patent 4,298,701.
Since it was an object of the present invention to dispense with the use of chain lengthening agents and cross-linking agents of component d) as much as possible, the compounds of component d) are used in small quantities of up to about 25 mole %, based on the quantity of water used in the process, to assist in promoting a "rubber-like" solidification. When component d) contains amino yroups, an increase in the viscosity of the liquid reaction mixture before the main reaction sets in may be achieved, if desired, due to the reaction between isocyanate groups and amino groups ~hich sets in immediately. This is frequently advantageous for ease of handling of molds (sealing off of the split level and of the ejectors and core pullers).
Mo-3050 ~ 9 , 1 30~225 The auxiliary agents and additives e) optionally used include conventional emulsifiers, catalysts, lubricants, internal mold release agents, stabilizers, pulverulent or fibrous reinforcing fillers, flame retardants or plasticizers such as the type mentioned in DE-OS 3,147,736, Kunststoff-Handbuch referred to above on pages 96 et seq or in U.S. Patents 4, 218, 54 3 and 4 , 2 9 8 , 701.
In accordance with the present invention water is used as the main chain lengthening agent. Water is added in a quantity of at least about 0.10 mole, preferably about 0.15 to 0.45 mole per equivalent of isocyanate groups present in component a). The isocyanate groups which react with isocyanate-reactive groups when the monomeric polyisocyanates a) are used for preparing prepolymers with a portion of component b) are considered to be isocyanate groups when determining the amount of water to be used as chain lengthening agent.
The reactants are otherwise worked up in proportions correspondin~ to an isocyanate index of about 70 to 125, preferably about 85 to 115.
The process according to the invention is carried out by reacting the aforesaid starting components together by the casting process. When the one-shot 25 ~method is employed, components b) to e) are preferably combined to form a "reactive component" or "polyol component" which is mixed with polyisocyanate component a) either mechanically or manually. The apparatus described in Kunststof -Handbuch, Carl Hanser Verlag, 1966, Volume VII, page 144-166 may be used, for example.
The reaction mi~ture may alternatively be prepared by the the isocyanate prepolymer process as previously mentioned. In this case, the "isocyanate prepolymers" obtained from polyisocyanate component a) 35 and all or a portion of component b) (preferably less Mo-3050 - 10 -1 30~225 than 80% of component b)) and optionally all or a portion of component d) would constitute the "polyisocyana~e component" and the mixture of the remaining propor~ions of components b) to e) would 5 constitute the "polyol component." In this case the components are mixed as in ~he one-shot process.
The quantity of the polyisocyana~e component is generally about 10 to 95% by weight, preferably about 40 to 80% by weight, based on the total quantity of the 10 reaction mixture. High proportions by weight of isocyanate components may be present when isocyanate prepolymers semi-prepolymers are used as polyisocyanate components.
The starting components are generally at a 15 temperature of about 30 to 150C, preferably about 50 to 120C, before they are mixed together. When isocyanate prepolymers are used it is advantageous for their temperature to be in the upper position of this tempera-ture range.
The reaction mixture, which has preferably been prepared by adding the components together at low pressure and mixing them in a stirrer vessel, should be introduced by the casting process without any counter-pressure into an initially open mold (preferably made of 25 metal, more preferably steel) which has been adjusted to a temperature of about 30 to 140~C, preferably about 60 to 120C. The mold is filled with the reaction mixture to at least 95~ of its volume capacity, preferably completely, and is then tightly closed so that the 30 carbon dioxide produced in the reaction cannot cause e~pansion of the reaction mixture and, therefore, goes partially or completely into solution. The molds should preferably be filled and sealed before any significant amount of chemical reaction has taken place. It is Mo-3050 1 30~225 frequently advisable to coat the internal walls of the mold with a conven~ional mold release agent before the mold is filled.
When pressure stable molds are used, all that 5 is generally required is to seal the mold liquid-tightly after it has been filled. If the molds are of the type which are likely to undergo an increase in their internal volume under the pressure produced by the evolution of carbon dioxide, this increase in volume 10 should be prevented by application of external pressure.
Formulations giving rise to more rigid products tend in some cases to solidify by way of a waxy-brittle inter-mediate stage accompanied by premature shrinkage. In this phase, the internal CO2 pressure is liable to 15 expand the molded part into the space which has become free as a result of this shrinkage. This expansion, which takes place during the bri~tle intermediate stage before the mold is opened, may lead to damage of the molded part due to the formation of cracks (shell 20 cracks).
This may be counteracted by reducing the volume of the mold by an amount corresponding to the shrinkage during the solidification phase as described in EP-A-0 024 610. This "after-pressure technique" can 25 very easily be carried out with so-called immersion edge molds (see, for example, "Kunststoff-Handbuch, Carl Hanser Verlag, Munich 1973. Volume VIII, "Polyester"
page 488"). Apparatus which enable this after-pressure technique to be applied to molds without immersion edges 30 are described in EP-A-0 0~4 610.
Thermal expansion of the reaction mixture may also be utilized to compensate for the shrinkage occurring during the reaction by complPtely filling a very hot mold with a reaction mixture, which is at a Mo-3050 - 12 -1 30~225 rela~ively low temperature, and then sealing the mold.
This means that before the mold is filled, it i8 set at a higher tempera~ure than that of the rea~tion mixture.
The internal pressur~s produced in the mold in 5 the process according to the inven~ion range from about 10 to 180 bar, preferably about 40 to 150 bar, depending upon ~he quantity of water used. At these pressures, the CO2 evolved remains in solu~ion, provided the mold is comple~ely filled. To ensure that this will in fact 10 take place, the raw materials mus~ be thoroughly degassed and free from air before they are introduced into the mold since air and ni~rogen are not soluble in the polymer under the given operating conditions.
Bubbles are therefore liable to form if the materials 15 have not been sufficiently degassed, and these bubbles may in turn cause cracking in the molded par~, usually after release from the mold due to the parts high internal pressure.
The freshly molded parts generally cannot be 20 tempered immediately at a high temperature, e.g. 110C, as is customary when glycols or amines are used for cross-linking. Exposure to such a temperature would result in a sharp increase in the internal pressure of the freshly molded article due to the very rapid change 25 of the dissolved CO2 to the gaseous state, with a corresponding build-up of pressure.
If the mo-lded articles are stored at room temperature, they gradually give up the CO2 dissolved in them by diffusion. Most of the CO2 has disappeared 30 after 12 hours' storage at room temperature. The parts may then be safely tempered at an elevated tempera~ure, e.g. 110C. If earlier tempering is required, the temperature must be raised in steps, starting from 50 to 60C.
Mo-3050 - 13 -` 1JO~225 The process according to the invention enables high quality polyurethane-polyurea elastomer molded articles to be obtained within a hardness range of about 60 Shore A to about 60 Shore D.
The invention is further illustrated but is not intended to be limited by thP following examples in which all parts and percentages are by weight unless otherwise specified.
EXAMPLES
The following raw ma~erials are used in the examples:
Polyisocyanate 1:
An isocyanate prepolymer with an isocyanate content of 3.9% prepared by the reaction of 2.14 mole of 15 1,5-diisocyanatonaphthalene with 1 mole of a polyesterdiol having a molecular weight of 2000 and obtained from adipic acid and ethylene glycol.
Polyisocyanate 2:
An isocyanate prepolymer having an isocyanate 20 content of 19.5% prepared by the reaction of 13 mole of 4,4'-diisocyanatodiphenylmethane with 1 mole of a polyesterdiol having a molecular weight of 2000 and obtained from adipic acid and a mixture of ethylene glycol and butane-1,4-diol in a ratio by weight of 25 70:30.
The other components are combined in a single component referred to as "Polyol mixture":
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OperatinR conditions The formulations containing low proportions of water could be worked up by mixing them manually but since air bubbles could also be stirred in when a manual 5 procedure was adopted, a low pressure dosing apparatus with mechanical stirrer was used in all cases with the exception of Example 1. After preparation of the reaction mixture, the mold was always filled to lOOZ of its volume. Before the molds were filled, the internal 10 walls were coated with a commercial mold release agent (PURA* 1 of H.W. Hapke GmbH, D-2000 Norderstedt, Post Box 5108).
Example 1 2-7 Temperature of raw materials Polyol mixture 50 50-60 C
Polyisocyanate 130 50-60 C
Temperature of mold 100 80 C
20 Molded part: Plate mold Wall thickness 30 6 mm External dimensions 18x18 18x18 cm Mold residence time 30 45 min 25 Tempering 24 h / 110C
The mold, which was completely open during casting of the reaction mixture, was sealed absolutely tight after it had been filled with reaction mixture by 30 applying an elastomer plate to the mold and then keeping the mold shut in a press under a holding pressure of 100 bar. Tempering was carried out at 110C for 24 hours after the article removed from ~he mold had been stored.
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Mo-3050 - 17 -1 3~)~2~5 Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by 5 those skilled in the art without departing from the spirit and scope of the invention except as it may be limi Mo-3050 ~ 18 -
Mo-3050 LeA 25,384 PROCESS FOR THE PRODUCTION OF ELASTOMERIC MOLDED
ARTICLES BASED ON POLYISOCYANATE POLYADDITION
PRODUCTS CONTAINING UREA GROUPS
BACKGROUND OF THE INVENTION
5 Field of the Invention _ This invention relates to a new process for the production of elastomeric molded articles based on polyisoeyanate polyaddition products containing urea groups, in particular polyurethanes con~aining urea 10 groups and having a gross density above 1.0 g/cm3, wherein the urea groups required for obtaining the superior mechanical properties are primarily obtained by the reaction of organic polyisocyanates and water.
Description of the Prior Art The production of compact polyurethane elasto-mers containing urea groups by the two-stage process using water as chain lengthening agent is known (see, e.g. Kunststoff-Handbuch, Carl Hanser Verlag, 1966, Volume VII, pages 270-271). Due to the gaseous CO2 20 produced by the reaction of ~he isocyanate groups with water, production of these compact substances took place via the intermediate stage of the corresponding foams, which must first be compacted by rollers before they can be molded into noncellular elastomers.
As this process is very expensive due to the many individual steps involved, it is only suitable for products required for very speclal applications. One major disadvantage of this molding process is that i~
only enables plate goods or geometrically sîmple molded 30 parts to be produced.
At the same time, polyisocyanate polyaddition products which contain urea groups, in particular poly-LeA 25384-1 3~225 urethanes containing urea groups, have exceptionally desirable mechanical properties and the use of water as chain lengthening agen~ (instead of diamines) provides a particularly simple and inexpensive method of introduc-5 ing urea groups.
It was therefore an object of the present invention to provide a new process for the preparation of elastomeric polyisocyanate polyaddition products containing urea groups, in particular polyurethanes, 10 which makes use o the principle of using water as chain leng~hening agent without the disadvantages mentioned above.
This problem was solved by providing the process according to the invention described below, in 15 which elastomeric molded parts are produced by casting and water is used as chain lengthening agent. The molds, which are initially open, are filled to an extent of at least 95% and then tightly closed so that the reaction takes place under a sufficient pressure to 20 ensure that the gaseous carbon dioxide cannot cause the reaction mixture to foam up. It is surprisingly found that after ~he time required for curing, very flexible molded parts can be removed from the mold without undergoing any deformation due to the action of 25 dissolved carbon dioxide gas.
Although DE OS 3,407,931 discloses a process for the production of noncellular or microcellular molded articles based on polyurethanes containing urea groups, wherein organic polyisocyanates, compounds 30 containing isocyanate reactive groups and water are reacted together inside closed molds under a pre~sure preventing the formation of foam, this prior art process is carried out by the reaction inJectiOn molding ~ech-nique in which the starting components are mixed Mo 3050 _ ~ _ 1 30~225 together under a high pressure and introduced into a closed mold. The reaction injPction molding technique is one which is mainly used for the production of thin-walled molded par~s with short ~old residence 5 times. For the production of thick walled parts, the casting process using open molds has become established in prac~ice because large and bulky parts which are free from air bubbles in the interior can be produced much more easily by the casting process using reaction 10 mixtures which react slowly. It could not be deduced from the teaching of DE-OS 3,407,931 that the production of molded elastomer parts by the casting according to the process of the invention described below would be a suitable and feasible method of producing high quality 15 elastomers.
In US-PS 4,416,844 a process is described for the production of puncture-proof tires which are filled with an elastic reaction mass which is substantially free from bubbles, using water as chain lengthening 20 agen~. In this process, the formation of bubbles by the liberation of carbon dioxide gas is prevented by inject-ing the reaction mass into the tire carcass until the mass has built up a pressure of at least 25 psi (=1.7 bar) against the elasticity of the carcass. The 25 said prior publication gives no indication of the feasibility of carrying out the process according to the invention described below for the production of elastomeric molded parts by casting since in the prior publication the reaction mass remains in a pressure 30 stable cavity (carcass). Questions concerning the manufacture of the molded parts are not discussed.
SUMMARY OF THE INVENTION
The presen~ invention relates to a process for the production of elastomeric molded articles based on Mo 3050 - 3 -1 30~225 polyisocyanate polyaddition products containing urea groups by the reaction of a) a polyisocyanate component with b) compounds having a molecular weight of 500 to about 12,000 and containing at least two isocyanate reactive groups, c) water as chain lengthening agent and, optionally, d) organic compounds having a molecular weight of 60 to about 499 and con~aining at least two isocyanate reactive groups by the one-shot or prepolymer process, main~aining an isocyanate index of about 70 to 125, characterized in that ~i) water is used in a quantity of at least 10 mole %
per equivalent of isocyanate groups in component a~ -and (ii) the reaction mixture prepared from the components is filled into an open mold by the casting process, the quantity introduced amounting to a least 95Z of the volume of the molded, and the mold is subse-quently tightly closed so that the carbon dioxide produced by the reaction between water and isocya-nate is virtually unable to cause expansion of the reaction mixture.
DETAILED DESCRIPTION OF THE INVENTION
In the context of the present invention "poly-isocyanate polyaddition products" mean both pure poly-ureas and polyurethanes containing urea groups. The products of the process according to the invention are 30 preferably polyurethanes containing:urea groups.
The "one-shot process" is unders~ood in the context of the present invention to be a procedure in which components b), c) and d) are added together to form a "reactive component" which is then mi~ed with Mo-3050 - 4 -polyisocyanate component a) and brought to react in a single stage. Any auxiliary agents and additives used may be incorporated both with polyisocyanate component a) and with the "reactive component." The auxillary 5 agents and additives e) are preferably added to the "reactive component."
In the context of the present invention "prepol~mer process" means a procedure wherein polyiso-cyanate component a) is reacted with at least a portion 10 of component b) and optionally with a portion or all of component d) to provide a "prepolymer" containing isocyanate groups, which is then reacted with a mixture of component c), the remaining quantity of component b) and optionally component d). Different compounds within 15 the scope of components b) and d) may be used for the preparation of the prepolymer and for the chain extender mixture. In this variation of the process according to the invention, the optional auxiliary agents and additives e) may again be incorporated either with the 20 prepolymer or wi~h the aforesaid mixture, the latter variation being preferred.
"Isocyanate index" means the number of isocyanate groups present in the reaction mixture introduced into the mold per 100 isocyanate reactive 25 groups, water being included in the calculation as a difunctional compound.
The starting materials a) include any organic polyisocyanates having a molecular weight of up to 600, preferably up to 300. Aromatic diisocyanate~ are 30 preferably used. Examples of suitable polyisocyanates include 1,5-diisocyanatonaphthalene, 2,4'- and/or 4,4i-diisocyanatodiphenylmethane, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 2,4'-diisocyanatotoluene and commerciaI mixtures thereof with 2,6-diisocyanato-Mo-3050 - 5 -toluene, 1,4-diisocyanatobenzene and diisocyanates corresponding to the following formulae:
OCN- ~ (CH2)2 ~ NCO, OCN- ~ O-C ~ NCO
OCN - ~ C~2-CH2 ~ NCO and H3C - ~ NH-C- ~ 3 NCO NCO
(Cyclo)aliphatic diisocyanates such as isophorone diisocyanate, 1,6-diisocyanatohexane, trans- -1,4-cyclohexanediisocyanate, 4,4'-diisocyanato-dicyclo-10 hexylmethane or p-xylylenediisocyanate may also be used.
Carbodiimide- (uretoneimine-), isocyanurate-, urea-, urethane- and/or allophanate-modified derivatives of such diisocyanates are also suitable although they are generally less preferred.
Particularly suitable starting components b) include polyester and polyether polyols having a molecular weight of 500 to about 12,000, preferably about 900 to 6000 ~calcula~ed from the functionality and the hydroxyl group content) and any mixtures of such cOmpounds.
The polyhydroxyl compounds are preferably difunctional although they may be ba~ed on mixtures Mo-3050 - 6 -1 3f)~225 containing small proportions of higher functional polyhydroxyl compounds such that the average func-tionality of the mixtures is at most 2.5, preferably at most 2.3.
Suitable polyester polyols are obtained, for example, by the reaction of excess quantities of polyhydric alcohols with polybasic, preferably dibasic carboxylic acids or carboxylic acid anhydrides. The compounds mentioned in US-PS 4,218,543, column 8, lines 27 to 52, are examples of suitable carboxylic acids, carboxylic acid anhydrides and low molecular weight, polyhydric alcohols.
Polyether polyols suitable for the process according to the invention may be obtained, for example, by the known method of alkoxylating suitable starter molecules, in particular using ethylene oxide and/or propylene oxide, optionally as mixtures or in any sequence. Water, ethylene glycol, 1,2-dihydroxypropane, trimethylolpropane, and glycerine and any mixtures are examples of suitable starter molecules. Poly(oxytetra-methylene)glycols are also suitable. The particulars given above concerning the average functionality of the polyether polyols are also applicable here so that when trifunctional starter molecules such as trimethylol-25 propane or glycerine are used, the resulting trifunc-tional polyether polyols merely are mixed with difunc-tional polyether polyols.
In addition to or instead of the above mentioned polyester and/or polyether polyols, other relatively high 30 molecular weight compounds in the above~mentioned molecular weight range containing isocyanate reactive groups may be used as component b) in the process according to the invention~ Such M~-3050 - 7 -1 30~2~5 compounds include polyesters based on lactones ~such as poly--caprolactones) or ~-hydroxyalkane carboxylic acids (such as ~-hydroxycaproic acid), polycarbonate polyols, polyester amides and hydroxyl group-containing 5 polyacetals.
Polyether amines which are equally suitable as component b) may be prepared from the above mentioned polyether polyols by known processes, for example, by the process of cyanoalkylation of polyoxyalkylene 10 polyols followed by hydrogena~ion of the resulting nitrile (US-PS 3,267,050) or the amination of polyoxyalkylene polyols with amines or ammonia in the presence of water and catalys~s (DE-AS 1,215,373).
Polyether amines containing aromatically bound 15 amino groups linked to the polyether chain by urethane or ester groups are also suitable for use as component b). The preparation of such compounds may be carried out, for example, by the processes described in EP~A-79,536, DE-OS 2,948,419, DE-CS 2,019,432, DE-OS
20 2,619,840, US-PS 3,808,250, US-PS 3,975,426 or US-PS
4,016,143.
Component c) is water, which may be introduced either as such or in the form of inorganic or organic compounds which split off water such as Na2SO4.122O, 25 pinacone hydrate, molecular sieve zeolites charged with water, or acetaldoxime. The water is preferably used as such in liquid form.
The organic compounds d) optionally used have molecular weights of 60 to 499, preferably 62 to about 30 350. They are preferably compounds carrying two or three isocyanate reactive groups. Suitable compounds of this type include polyhydric aliphatic alcohols such as ethylene glycol, 1,2-dihydroxypropane, 1,3-dihydroxy-propane, 1,4-dihydroxybutane, 1,6-dihydroxyethane, Mo-3050 - 8 -1 30~3)25 trimethylolpropane and glycerine, the low molecular weight alkoxylation products of the above mentioned polyhydric alcohols such as diethylene glycol, triethylene glycol, dipropylene glycol and tripropylene glyco]; and any mixtures of such low molecular weight chain lengthening agents or crosslinking agents. Amino alcohols and alkoxylation products of aliphatic amines or hydrazine may also be used as component d). Examples include athanolamine, diethanolamine, triethanolamine, propanolamine and hydrazinoethanol. Finally, organic diamines having a molecular weight of 62 to 499 and containing at least two primary and/or secondary amino groups may be used as starting component d). Examples include 1l2-dlaminoethanel 1,6-diaminohexane, 2,4-diaminotoluene, 4,4'-diaminodiphenylmethane and in particular, aromatic diamines containing sterically hindered amino groups such as those disclosed in DE-OS
2,916,~85, page 17, line 26 to page 18, line 9 (U.S.
Patent 4,298,701.
Since it was an object of the present invention to dispense with the use of chain lengthening agents and cross-linking agents of component d) as much as possible, the compounds of component d) are used in small quantities of up to about 25 mole %, based on the quantity of water used in the process, to assist in promoting a "rubber-like" solidification. When component d) contains amino yroups, an increase in the viscosity of the liquid reaction mixture before the main reaction sets in may be achieved, if desired, due to the reaction between isocyanate groups and amino groups ~hich sets in immediately. This is frequently advantageous for ease of handling of molds (sealing off of the split level and of the ejectors and core pullers).
Mo-3050 ~ 9 , 1 30~225 The auxiliary agents and additives e) optionally used include conventional emulsifiers, catalysts, lubricants, internal mold release agents, stabilizers, pulverulent or fibrous reinforcing fillers, flame retardants or plasticizers such as the type mentioned in DE-OS 3,147,736, Kunststoff-Handbuch referred to above on pages 96 et seq or in U.S. Patents 4, 218, 54 3 and 4 , 2 9 8 , 701.
In accordance with the present invention water is used as the main chain lengthening agent. Water is added in a quantity of at least about 0.10 mole, preferably about 0.15 to 0.45 mole per equivalent of isocyanate groups present in component a). The isocyanate groups which react with isocyanate-reactive groups when the monomeric polyisocyanates a) are used for preparing prepolymers with a portion of component b) are considered to be isocyanate groups when determining the amount of water to be used as chain lengthening agent.
The reactants are otherwise worked up in proportions correspondin~ to an isocyanate index of about 70 to 125, preferably about 85 to 115.
The process according to the invention is carried out by reacting the aforesaid starting components together by the casting process. When the one-shot 25 ~method is employed, components b) to e) are preferably combined to form a "reactive component" or "polyol component" which is mixed with polyisocyanate component a) either mechanically or manually. The apparatus described in Kunststof -Handbuch, Carl Hanser Verlag, 1966, Volume VII, page 144-166 may be used, for example.
The reaction mi~ture may alternatively be prepared by the the isocyanate prepolymer process as previously mentioned. In this case, the "isocyanate prepolymers" obtained from polyisocyanate component a) 35 and all or a portion of component b) (preferably less Mo-3050 - 10 -1 30~225 than 80% of component b)) and optionally all or a portion of component d) would constitute the "polyisocyana~e component" and the mixture of the remaining propor~ions of components b) to e) would 5 constitute the "polyol component." In this case the components are mixed as in ~he one-shot process.
The quantity of the polyisocyana~e component is generally about 10 to 95% by weight, preferably about 40 to 80% by weight, based on the total quantity of the 10 reaction mixture. High proportions by weight of isocyanate components may be present when isocyanate prepolymers semi-prepolymers are used as polyisocyanate components.
The starting components are generally at a 15 temperature of about 30 to 150C, preferably about 50 to 120C, before they are mixed together. When isocyanate prepolymers are used it is advantageous for their temperature to be in the upper position of this tempera-ture range.
The reaction mixture, which has preferably been prepared by adding the components together at low pressure and mixing them in a stirrer vessel, should be introduced by the casting process without any counter-pressure into an initially open mold (preferably made of 25 metal, more preferably steel) which has been adjusted to a temperature of about 30 to 140~C, preferably about 60 to 120C. The mold is filled with the reaction mixture to at least 95~ of its volume capacity, preferably completely, and is then tightly closed so that the 30 carbon dioxide produced in the reaction cannot cause e~pansion of the reaction mixture and, therefore, goes partially or completely into solution. The molds should preferably be filled and sealed before any significant amount of chemical reaction has taken place. It is Mo-3050 1 30~225 frequently advisable to coat the internal walls of the mold with a conven~ional mold release agent before the mold is filled.
When pressure stable molds are used, all that 5 is generally required is to seal the mold liquid-tightly after it has been filled. If the molds are of the type which are likely to undergo an increase in their internal volume under the pressure produced by the evolution of carbon dioxide, this increase in volume 10 should be prevented by application of external pressure.
Formulations giving rise to more rigid products tend in some cases to solidify by way of a waxy-brittle inter-mediate stage accompanied by premature shrinkage. In this phase, the internal CO2 pressure is liable to 15 expand the molded part into the space which has become free as a result of this shrinkage. This expansion, which takes place during the bri~tle intermediate stage before the mold is opened, may lead to damage of the molded part due to the formation of cracks (shell 20 cracks).
This may be counteracted by reducing the volume of the mold by an amount corresponding to the shrinkage during the solidification phase as described in EP-A-0 024 610. This "after-pressure technique" can 25 very easily be carried out with so-called immersion edge molds (see, for example, "Kunststoff-Handbuch, Carl Hanser Verlag, Munich 1973. Volume VIII, "Polyester"
page 488"). Apparatus which enable this after-pressure technique to be applied to molds without immersion edges 30 are described in EP-A-0 0~4 610.
Thermal expansion of the reaction mixture may also be utilized to compensate for the shrinkage occurring during the reaction by complPtely filling a very hot mold with a reaction mixture, which is at a Mo-3050 - 12 -1 30~225 rela~ively low temperature, and then sealing the mold.
This means that before the mold is filled, it i8 set at a higher tempera~ure than that of the rea~tion mixture.
The internal pressur~s produced in the mold in 5 the process according to the inven~ion range from about 10 to 180 bar, preferably about 40 to 150 bar, depending upon ~he quantity of water used. At these pressures, the CO2 evolved remains in solu~ion, provided the mold is comple~ely filled. To ensure that this will in fact 10 take place, the raw materials mus~ be thoroughly degassed and free from air before they are introduced into the mold since air and ni~rogen are not soluble in the polymer under the given operating conditions.
Bubbles are therefore liable to form if the materials 15 have not been sufficiently degassed, and these bubbles may in turn cause cracking in the molded par~, usually after release from the mold due to the parts high internal pressure.
The freshly molded parts generally cannot be 20 tempered immediately at a high temperature, e.g. 110C, as is customary when glycols or amines are used for cross-linking. Exposure to such a temperature would result in a sharp increase in the internal pressure of the freshly molded article due to the very rapid change 25 of the dissolved CO2 to the gaseous state, with a corresponding build-up of pressure.
If the mo-lded articles are stored at room temperature, they gradually give up the CO2 dissolved in them by diffusion. Most of the CO2 has disappeared 30 after 12 hours' storage at room temperature. The parts may then be safely tempered at an elevated tempera~ure, e.g. 110C. If earlier tempering is required, the temperature must be raised in steps, starting from 50 to 60C.
Mo-3050 - 13 -` 1JO~225 The process according to the invention enables high quality polyurethane-polyurea elastomer molded articles to be obtained within a hardness range of about 60 Shore A to about 60 Shore D.
The invention is further illustrated but is not intended to be limited by thP following examples in which all parts and percentages are by weight unless otherwise specified.
EXAMPLES
The following raw ma~erials are used in the examples:
Polyisocyanate 1:
An isocyanate prepolymer with an isocyanate content of 3.9% prepared by the reaction of 2.14 mole of 15 1,5-diisocyanatonaphthalene with 1 mole of a polyesterdiol having a molecular weight of 2000 and obtained from adipic acid and ethylene glycol.
Polyisocyanate 2:
An isocyanate prepolymer having an isocyanate 20 content of 19.5% prepared by the reaction of 13 mole of 4,4'-diisocyanatodiphenylmethane with 1 mole of a polyesterdiol having a molecular weight of 2000 and obtained from adipic acid and a mixture of ethylene glycol and butane-1,4-diol in a ratio by weight of 25 70:30.
The other components are combined in a single component referred to as "Polyol mixture":
Mo-3050 - 14 -1 3~225 r~ I o u, ~ oo o , o , U~
C~l ~1 $ U~ , U) o , Cl ~ ~
U~ I o o U~ , ~ ~ o , ~, C~
I g o Ln ~
~ o , o , , C~, ~1 $ U~ , ~! , , o i o I I
C~ o ~
;~1l o u~ , ~ , , ~ ~
~ ~ O I o I I AO a)4~
~ -~ o ~1o , ~ , ~ ~ I o o I I
o ~ a Cl , t~
.~ .~ ~
g!~ 8 ~ ~ 5 Mo-3050 - 15 ~
OperatinR conditions The formulations containing low proportions of water could be worked up by mixing them manually but since air bubbles could also be stirred in when a manual 5 procedure was adopted, a low pressure dosing apparatus with mechanical stirrer was used in all cases with the exception of Example 1. After preparation of the reaction mixture, the mold was always filled to lOOZ of its volume. Before the molds were filled, the internal 10 walls were coated with a commercial mold release agent (PURA* 1 of H.W. Hapke GmbH, D-2000 Norderstedt, Post Box 5108).
Example 1 2-7 Temperature of raw materials Polyol mixture 50 50-60 C
Polyisocyanate 130 50-60 C
Temperature of mold 100 80 C
20 Molded part: Plate mold Wall thickness 30 6 mm External dimensions 18x18 18x18 cm Mold residence time 30 45 min 25 Tempering 24 h / 110C
The mold, which was completely open during casting of the reaction mixture, was sealed absolutely tight after it had been filled with reaction mixture by 30 applying an elastomer plate to the mold and then keeping the mold shut in a press under a holding pressure of 100 bar. Tempering was carried out at 110C for 24 hours after the article removed from ~he mold had been stored.
* Trade-mark Mo-3050 - 16 -G.q~ .
,~
o ~ o ~ U ~ ~ ~ ~ ~
o l l ~ ~ ~ C~
s , ~ ~ 5 cn ~ cn O E ~ E
o ¦ c~ 3 3 ~ 3 3 Q .a 3~Jl `' 2 ~e ~ ~ ~ ~ ~ Q- I
or~
~ C~l C~
D ~ N
OQ LO N et ~
O ~ o~ ~ ~ $ ~ o ~D ~ ~D
I~ ~ N O O
O I N ~-1~ O n I I ~ II I
U~
~ ~O 1 o I C~ ~ ~ O 1 d' ¦ ~ ~--I I ClCn a) _I ~--I i~ I I el- ~ N N
U~ ~
C~ g O~ l O ~
~ ~ O
o I ~ o I ~ r~ O O
N¦ c~ I ~ C~J 1'~ 1 1 ~) ~) ~ O O
O O CO N ~D . . 1~ O O
O o~ I O00 ~ ~ ..
X V~
._ ., ~ ~ O ~
N X S ~ 1~ 0 c C '- ~ci a) ~ ~ ~ ~ ~ ~ o O X O n:~ ns a ~ ~ c ~ ~ ~ ~ _ ~ o z ~ o o c ~ ~ 2) ~ a~ ~ ~ O ~ O O
r-- _ r~ U~ ~ tCS ~ ~ O O C`J
E E ~ C ~ ~
0 a ~ ~ os_ c ~ o s~ Q a~ t ~ c X X O ~ ~o o , ~n ~ æ ~ LLI ~ ~ ~ ~ ~ ~ w ~
Mo-3050 - 17 -1 3~)~2~5 Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by 5 those skilled in the art without departing from the spirit and scope of the invention except as it may be limi Mo-3050 ~ 18 -
Claims (4)
1. A process for the preparation of an elasto-meric molded article based on a polyisocyanate poly-addition product containing urea groups which comprises 1) preparing a reaction mixture comprising a) a polyisocyanate component with b) a compound having a molecular weight of 500 to about 12,000 and containing at least two isocyanate reactive groups, c) water in a quantity of at least 10 mole % per equivalent of isocyanate groups in component a) and d) optionally organic compounds having a molecular weight of 60 to 499 and containing at least two isocyanate reactive groups by the one-shot or prepolymer process at an isocyanate index of about 70 to 125,
2) introducing the reaction mixture by the casting process into an open mold such that the quantity introduced amounts to at least 95% of the volume of the mold and
3) tightly closing the mold such that the carbon dioxide formed by the reaction between water and isocyanate is virtually unable to cause expansion of the reaction mixture.
2. The process of Claim 1 which comprises filling the mold completely and maintaining a temperature above the temperature of the reaction mixture.
3. The process of Claim 1 which comprises continuously reducing the mold in size such that the reaction pressure inside the mold is maintained until Mo-3050 - 19 -the molded product can be removed in order to compensate for shrinkage inside the mold during solidification of the reaction mixture.
2. The process of Claim 1 which comprises filling the mold completely and maintaining a temperature above the temperature of the reaction mixture.
3. The process of Claim 1 which comprises continuously reducing the mold in size such that the reaction pressure inside the mold is maintained until Mo-3050 - 19 -the molded product can be removed in order to compensate for shrinkage inside the mold during solidification of the reaction mixture.
4. The process of Claim 2 which comprises continuously reducing the mold in size such that the reaction pressure inside the mold is maintained until the molded product can be removed in order to compensate for shrinkage inside the mold during solidification of the reaction mixture.
Mo-3050 - 20 -
Mo-3050 - 20 -
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3725198.8 | 1987-07-30 | ||
| DE19873725198 DE3725198A1 (en) | 1987-07-30 | 1987-07-30 | METHOD FOR PRODUCING ELASTOMERIC MOLDED BODIES BASED ON POLYISOCYANATE POLYADDITION PRODUCTS HAVING UREA GROUPS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1308225C true CA1308225C (en) | 1992-10-06 |
Family
ID=6332666
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000573499A Expired - Lifetime CA1308225C (en) | 1987-07-30 | 1988-07-29 | Process for the production of elastomeric molded articles based on polyisocyanate polyaddition products containing urea groups |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0301342B1 (en) |
| JP (1) | JPH01163029A (en) |
| AT (1) | ATE77824T1 (en) |
| CA (1) | CA1308225C (en) |
| DE (2) | DE3725198A1 (en) |
| ES (1) | ES2032497T3 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3921861A1 (en) * | 1989-07-04 | 1991-01-31 | Bayer Ag | METHOD FOR PRODUCING HIGH-ELASTIC PLASTICS |
| US5070138A (en) * | 1990-07-13 | 1991-12-03 | E. R. Carpenter Company, Inc. | Polyurethane elastomer tire fill compositions and method of making same |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2137642B (en) * | 1980-12-23 | 1985-09-04 | Ransome J Wyman | Deflation-proof pneumatic tire and elastomeric fillings thereof |
| DE3407931A1 (en) * | 1984-03-03 | 1985-09-05 | Bayer Ag, 5090 Leverkusen | METHOD FOR PRODUCING MOLDED BODIES BASED ON POLYURETHANES HAVING UREA GROUPS |
| US4604445A (en) * | 1985-04-18 | 1986-08-05 | The Firestone Tire & Rubber Co. | Polyurethane prepolymer comprising the reaction product of at least two active hydrogen containing substances with polyisocyanate |
| US4699968A (en) * | 1986-04-18 | 1987-10-13 | The Firestone Tire & Rubber Company | Water as a partial extender in polyurethane formulations |
-
1987
- 1987-07-30 DE DE19873725198 patent/DE3725198A1/en not_active Withdrawn
-
1988
- 1988-07-18 AT AT88111498T patent/ATE77824T1/en not_active IP Right Cessation
- 1988-07-18 EP EP88111498A patent/EP0301342B1/en not_active Expired - Lifetime
- 1988-07-18 DE DE8888111498T patent/DE3872464D1/en not_active Expired - Lifetime
- 1988-07-18 ES ES198888111498T patent/ES2032497T3/en not_active Expired - Lifetime
- 1988-07-28 JP JP63187062A patent/JPH01163029A/en active Pending
- 1988-07-29 CA CA000573499A patent/CA1308225C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01163029A (en) | 1989-06-27 |
| ATE77824T1 (en) | 1992-07-15 |
| DE3872464D1 (en) | 1992-08-06 |
| EP0301342A3 (en) | 1989-12-06 |
| ES2032497T3 (en) | 1993-02-16 |
| EP0301342B1 (en) | 1992-07-01 |
| EP0301342A2 (en) | 1989-02-01 |
| DE3725198A1 (en) | 1989-02-09 |
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