JPS6366849B2 - - Google Patents

Description

Claim 1 a. 85 to 95 parts by weight of a preformed polyether polyisocyanate containing a glycol having 2 to 6 carbon atoms, further having a plurality of terminal -NCO groups, and having a number average molecular weight of about 800 to 2,500; b. 5 to 15 parts by weight of a diol having a number average molecular weight of about 2000 to 3000, provided that the total weight of the preformed polyether polyisocyanate and the diol together is 100 parts; and c. of the active hydrogen in the curing agent. polyamine curing agent in proportions such that the equivalent ratio per isocyanate group is from 0.9 to 1.2, with the proviso that a, b and c react simultaneously when curing the composition. A polyether polyurethane composition characterized by improved resistance to crevice growth and to cracking in bending. 2. The proportion is 87 to 92 parts by weight of the preformed polyether polyisocyanate and 8 to 92 parts by weight of the diol.
A composition according to claim 1, wherein the composition is 13 parts by weight. 3. The composition of claim 2, wherein the preformed polyether polyisocyanate is poly(tetrahydrofuran) diisocyanate. 4. The composition according to claim 3, wherein the polyether diol is poly(tetrahydrofuran) diol. 5. The composition of claim 4, wherein the preformed polyether polyisocyanate has a number average molecular weight of 1000 to 3000. 6. The composition of claim 5, wherein the polyether diol has a number average molecular weight of about 2000. 7. A composition according to claim 5, wherein the polyamine curing agent is in the form of an alkali metal halide complex. 8. The composition according to claim 7, wherein the alkali metal halide is NaCl. 9. The composition of claim 8, wherein the NaCl complex has 3 molecules of diamine per molecule of NaCl. 10. The composition of claim 9, wherein the complex has three molecules of methylene dianiline per molecule of NaCl. 11. The composition of claim 10, wherein the complex is dispersed in dioctyl phthalate. 12. Claims 3, 4, wherein the polyether polyisocyanate is a reaction product of 2 moles of aromatic diisocyanate per mole of polyether diol.
5, 6, 7, 8, 9, 10 or 11. 13. A composition according to any one of claims 3, 4, 5, 6, 7, 8, 9, 10 or 11, wherein the polyether polyisocyanate is a reaction product of 2 moles of toluene diisocyanate per mole of polytetrahydrofuranol. . 14. The composition according to claim 12 at least
14. A composition according to claim 13, which is heated to a temperature of 100<0>C. 15. The composition of claim 13, wherein the composition is heated to a temperature of at least about 120°C. TECHNICAL FIELD The present invention relates to the production of elastomeric polyurethane compositions. More particularly, the present invention provides a polytetrahydrofuran diol prepared by adding a controlled amount of polytetrahydrofuran diol of a particular molecular weight range to a prepolymer comprising a polyether diisocyanate, followed by reaction with a diamine chain extending agent. The present invention relates to polyurethanes having improved resistance to crack and cut growth due to bending. BACKGROUND OF THE INVENTION Many attempts have been made to improve the resistance of polyurethane elastomers to breaking and growing nicks during bending and folding.
However, improvements in such properties
There is generally an accompanying loss of other properties such as tensile strength and modulus strength. U.S. Pat. No. 3,798,200 discloses that diisocyanates, such as toluene diisocyanate, are
and has at least two peaks in the molecular weight distribution curve, and at least one of the peaks has an average molecular weight of
Producing polyurethane elastomers by reacting with polyether glycols in which one of the peaks is located in the high molecular weight range of the polyether and at least the other peak is located in the low molecular weight range. He advocates methods for improving resistance. The same patentee, who recently obtained U.S. Pat. Claims improved resistance to crack growth and bending cracking by producing a polyurethane from a polyether glycol, both of which have one peak in the lower part of this range and at least one peak in the higher part of this range. are doing. Although the molecular weight distribution is described above, the various examples show that the polyether glycol comprises a typical mixture, e.g., one polyether glycol has a weight molecular weight of 8,500 to 11,000, and all present indicates that the proportion of glycol is such that the average molecular weight of the mixture as a whole is 4500 or less. The patentee describes the process as a one-step reaction comprising (a) simultaneously reacting a polyether diol or polyether glycol with a polyfunctional isocyanate and a curing agent; or (b) first reacting a polyfunctional isocyanate with a curing agent. The method is described as a two-step reaction in which a polyisocyanate is reacted with a mixture of polyether glycols to produce a prepolymer, and the prepolymer is subsequently reacted with a curing agent to produce a cured elastomer. However, greater improvements in resistance to bending fracture and nicking are still desired without sacrificing other physical properties. DETAILED DESCRIPTION According to the present invention, further improvements against bending fracture and cut growth, without further sacrificing other physical properties, are achieved by first refining one diisocyanate prepolymer of a polyether glycol or diol. This can be accomplished by subsequently adding further polyether glycol or polyether glycols to this diisocyanate polyether preprimer and simultaneously reacting with a curing agent to produce a cured elastomer. That is, the prepolymer, further polyol and curing agent react simultaneously when the mixture is cured. The diisocyanate polyether prepolymer advantageously has a number average molecular weight of about 800 to 2500, preferably about 1000 to 2500. The preparation of the diisocyanate prepolymer from one of the polyether glycols by reaction of 2 moles of an aromatic diisocyanate, such as toluene diisocyanate, with a polyether glycol or diol, preferably a polyether diol, can be carried out using a number average of about 1000 to 4000. The subsequent addition of a molecular weight polyether diol and simultaneous curing with an agent such as an aromatic polyamine provides a cosmetic improvement when the cured elastomer is prepared. The polyether diisocyanate prepolymer advantageously contains about 100 parts based on the total weight of prepolymer and polyether diol.
The amount of polyether diol is 85 to 95 parts by weight, preferably 87 to 92 parts, and the polyether diol is 5 to 15 parts by weight, preferably 8 to 13 parts. Aromatic polyamine curing agents are preferably used in proportions of about 10 to 20%, depending on the equivalent weight. Preferably, the equivalent ratio of active hydrogen of the curing agent is in the range 0.9 to 1.2 per isocyanate group of the polyfunctional isocyanate. Polyether diols Suitable polyether diols or glycols for use in preparing diisocyanate prepolymers or for use as diols added to diisocyanate prepolymers have the formula HO−R ⁰ −OH, where R ⁰ is Carbon number 2-10, preferably 2-6
is an aliphatic group of ] or the corresponding polyether diol derived from the alkylene oxide. These polyether glycols or diols have the formula HO(-R ⁰ O)- _x H, where x is an integer of sufficient value to provide the aforementioned molecular weight. Typical R ⁰ groups of such polyethers are −CH ₂ CH ₂ −;−
CH ₂ CH ₂ CH ₂ −;−CH(CH ₃ )CH ₂ −;−
(CH ₂ ) ₄ −;−CH(CH ₃ )CH ₂ CH ₂ −;−(CH ₂ ) ₅
−;−(CH ₂ ) ₆ −;−CH(C ₃ H ₇ )CH ₂ −;−CH
( _CH3 ) _CH2CH ( _CH3 )-; suitable
The R ⁰ group is -(CH ₂ ) ₄ - found in 1,4-butylene diol or tetramethylene glycol and in polymers derived from tetrahydrofuran. Suitable aromatic diisocyanates are, for example, tolylene-2,4-diisocyanate, tolylene-2,4-diisocyanate,
2,6-diisocyanate, naphthalene-1,5
-diisocyanate, diphenyl-4,4'-diisocyanate, benzophenone-4,4'-diisocyanate, diphenyl ether or diphenyl sulfide-4,4'-diisocyanate and its substituted with alkyl, alkoxy, halogen or nitro groups; derivatives such as 3,3-dimethyldiphenyl-4,4'-diisocyanate or 3,3'-
Dichlorodiphenylmethane diisocyanate, mixtures thereof, and the like. The following diisocyanates are suitable: tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, naphthalene-2,4-diisocyanate.
1,5-diisocyanate, diphenyl-4,
4'-diisocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dichlorodiphenylmethane diisocyanate, 1,6
-hexamethylene diisocyanate, 1,3- and 1,4-cyclohexyl diisocyanate, methylene bis(4-cyclohexyl diisocyanate), and 1,3- and 1,4-xylene diisocyanate. Mixtures of two or more of these diisocyanates can also be used. Curing agents suitable for use in the present invention are disclosed in U.S. Pat.
No. 4075150, No. 3900447, No. 3899438 and
No. 3,876,604. Suitable aromatic polyamines are, for example, 4,4'-methylene-dianiline, methylenebis(ortho-chloroaniline), 2,2',5-trichloro-4,
4'-methylene dianiline, naphthalene-1,5-
Diamines, ortho-, meta- and para-phenylenediamine, tolylene-2,4-diamine, dichlorobenzidine, diphenyl ether-4,4'-
Diamine, formula below [In the formula, _R is _-CH3 , _-C2H5- , _{-C3H7 , -C4H9 ,}
−C ₈ H ₁₇ ,

_[ Formula] and represents a group selected from the group consisting of -CH( _CH3 )-( _CH2 ) _3CH3 , and R' is -H, _{-CH3 , -C4H9} and _{-C6H 13}
represents a group selected from the group consisting of] and [In the formula, R′ is −CH ₃ , −C ₂ H ₅ , −(CH ₂ ) ₂ CH ₃ , −
_{C4H9 ,}

[Formula] represents a group selected from the group consisting of -C ₁₈ H ₃₇ and -CH ₂ - CH (C ₂ H ₅ ) - (CH ₂ ) ₃ CH ₃ , and R'' represents -CH ₃ , -C ₂ H ₅ ,−
represents a group selected from the group consisting of C ₃ H ₇ , -C ₄ H ₉ and halogen residues] and derivatives and mixtures thereof. Suitable polyamines are methylenebis(orthochloroaniline), 4,4'-methylenedianiline, naphthalene-1,5-diamine, ortho-, meta- and para-phenylenediamine, tolylene-2,
4-diamine, dichlorobenzidine, and its complexes, especially with alkali metal halides such as sodium chloride, such as the methylene dianiline complex in a ratio of 3:1. Suitable polyols are, for example, ethylene glycol, 1,2- and 1,3-propylene glycol, 1,3- and 1,4-butanediol, pentanediol, hexanediol, decanediol, dodecanediol, trimethylolpropane, castor. oil, glycerin, pentaerythritol, sorbitol, 4,4'-dihydroxydiphenylmethane, resorcinol, thioglycol and the formula below [In the formula, n is an integer of 1 to 4] and mixtures thereof. Diols are preferred, among these are ethylene glycol, 1,3-propylene glycol,
There are glycols such as 1,3- and 1,4-butanediol, and mixtures thereof. Also suitable are high molecular weight diols, such as polytetrahydrofuran (THF) diol, sold under the tradename "Polymeg". The number of equivalents of active hydrogen of the curing agent per isocyanate group is selected from the range from 0.9 to 1.2, preferably from 0.95 to 1.1. When producing polyether diisocyanate prepolymers, standard equipment with suitable stirring means suitable for the reaction of the diisocyanate with the diol is used. Similar or identical equipment may be used for the subsequent reaction with further polyether diols. For reaction with a curing agent, suitable molding equipment may be used to mold the cured elastic product. There are many commercially available products that may be used as components to the methods and products of the present invention. For example, polyethers having diisocyanate end groups, such as polytetrahydrofuran (polyTHF) having triene diisocyanate end groups, are commercially available under the trade name "Adiprene." A particularly suitable curing agent is also known under the trade name “Caytur”.
It is commercially available as. For example, “Caytur21”
It comprised a 49.5% dioctyl phthalate (DOP) dispersion of a sodium chloride complex of methylene dianiline at 3 moles per mole of NaCl. This complex is preferred because it requires elevated temperatures for curing, advantageously at least 100°C, preferably at least 120°C, so that premature curing does not occur. The ingredients may be added sequentially with the final addition of additional toluene diisoanate. After suitable stirring, the mixture can be poured into a heated mold and the temperature raised to a degree suitable for activation of the complex to act as a curing agent. The methods used to measure Texas Flex, cut growth, and various physical properties are those commonly used for such purposes. For example, see ASTM Test Method D-638 for tensile properties. EXAMPLES The following examples illustrate the methods of the invention. These examples, including the best embodiments presently known, are given by way of illustration only and are not intended to limit the scope of the invention as to any manner or manner in which the invention may be practiced. Unless otherwise specified, parts and percentages are given as parts and percentages by weight;
Moreover, the molecular weight is a number average molecular weight. In these examples, the various materials identified by end group and molecular weight may be designated by trade name as indicated by the reference mark as follows: (a) NCO-terminated polyester of molecular weight 1320; THF is
“Adiprene” L-367 with NCO 6.4%; (b) NCO-terminated polyTHF with molecular weight 2000 is
“Adiprene” L-100 with NCO 4.1%; (c) NCO-terminated polyTHF with molecular weight 3000 is
(Adiprene” L-42) with 2.8% NCO; (d) NCO-terminated polyTHF with a molecular weight of 5600 is a laboratory-produced material; (e) HO-terminated polyTHF with a molecular weight of 1000 has a hydroxyl number 114.5 is “Polymeg” 1000; (f) HO-terminated polyTHF with a molecular weight of 2000 is “Polymeg” 2000 with a hydroxyl number of 57.7; (g) HO-terminated polyTHF with a molecular weight of 5000 is “Polymeg” with a hydroxyl number of 21.6. (h) toluene diisocyanate (TDI) is “Hylene”; and (i) a 49.5% dispersion of the NaCl complex of methylene dianiline (MDA) is manufactured by DuPont under the trade name “Caytur-21”. NaCl.3 (MDA) in dioctyl phthalate (DOP) commercially available as
It is.

【table】

Table 1 In Table 1, the product of B shows a significant improvement in resistance to cut growth and in Texas Flex when compared to that of the control. Product B uses an HO-terminated polyTHF polymer with a molecular weight of 2000. *The equipment and methods used to conduct the Texas Flex test were provided by Rubber Chemistry and Technology;
Described in Vol. 38, No. 4, pp. 730-740, November 1965. EXAMPLE The method of the example was repeated by using a higher proportion of high molecular weight HO-terminated polyTHF.
The proportions, conditions and test results are shown in the table below.

【table】

[Table] Example High molecular weight HO-terminated _polyTHF
The method of the example was repeated by using the OH)/NCO ratio. The proportions, conditions and test results are shown in the table below.

【table】

[Table] In this case, as in the examples, the molecular weight
Product F, using 10 parts of the 2000 HO terminated polyTHF polymer product, had improved resistance to cut growth and Texas Flex compared to the control product. EXAMPLE The method of the example was repeated by using a higher proportion of high molecular weight HO-terminated polyTHF. The proportions, conditions and test results are shown in the table below.

【table】

Table: Products H and I using 2000 molecular weight HO-terminated polyTHF exhibited improved cut growth resistance and Texus Flex compared to the control. EXAMPLE The process of the example was repeated without the addition of free isocyanate by using similar amounts of high molecular weight polyTHF and comparable proportions of active hydrogen and isocyanate. A commercially available product (Flexol4-GO, polyethylene glycol di-(2-ethylhexoate)) was used in place of dioctyl phthalate. The proportions, conditions and test results are shown in the table below.

【table】

[Table] Warmth


100℃ 2
23 382 350

Again, the product (J) containing 2000 molecular weight polyTHF had improved resistance to cut growth and Texus Flex compared to the control. EXAMPLE The process of the example was repeated without the addition of free isocyanate by using a high molecular weight polyTHF of increasing molecular weight and a comparable ratio of active hydrogen to isocyanate. The proportions, conditions and test results are shown in the table below.

Table: Product L containing a diol with a molecular weight of 2000 was again superior in terms of resistance to crack growth and Texus Flex compared to the control. EXAMPLE The method of the example was repeated several times by substituting equivalent amounts of polyether made from trimethylene glycol and hexamethylene glycol of approximately equivalent molecular weight, respectively, in place of poly(THF) in the prepolymer and in the polyether diol. It was repeated and similar improvements were obtained. Examples Instead of the complexes, (a) NaCl.3(4,4-diaminodiphenyl) (b) NaCl.3(oxy-dianiline) (c) NaCl.3(4,4'-diaminodiphenyl-
Similar improvements were obtained when the method of the example was repeated several times by using an equivalent amount of a complex comprising 3,3-propane). Although polytetrahydrofuran is suitable as the polyether in polyether polyisocyanate prepolymers and in polyether diols, other ethers preferably have 2 carbon atoms.
It is also suitable to use that of glycols of ~6. Furthermore, instead of the preferred complexes of polyamines, it is also suitable to use polyamines in uncomplexed form, in which case the fixing, ie hardening, of the elastic body takes place at low temperatures. Other typical polyamine curing agents are listed above. While certain features of the invention have been described in detail with respect to various embodiments thereof, it will, of course, be obvious that other modifications may be made within the spirit and scope of the invention. It is not intended to be limiting to the precise details set forth above other than as provided herein.