WO2011075254A1

WO2011075254A1 - Isocyanatosilane-capped polyols

Info

Publication number: WO2011075254A1
Application number: PCT/US2010/056668
Authority: WO
Inventors: Zhizhong Wu; William A. Koonce
Original assignee: Dow Global Technologies Llc
Priority date: 2009-12-16
Filing date: 2010-11-15
Publication date: 2011-06-23

Abstract

Silylated polymers capped with isocyanatosilanes with a capping efficiency of less than 100% are provided. The reduced capping efficiency provides the silylated polymers with improved elastic properties relative to the same polymers capped with the same isocyanatosilanes with a capping efficiency of 100%. In particular, the present silylated polymers can have improved elongation at break and/or tensile strengths relative to their 100%-capped counterparts. The silylated polymers are well-suited for use in adhesives, sealants and coatings.

Description

ISOCYANATOSILANE-CAPPED POLYOLS

BACKGROUND

[0001] Polymers made from organosilane capped polyols are useful for adhesive and sealant applications. Unfortunately, these polymers frequently lack satisfactory or optimal mechanical properties in terms of their tensile strengths and elongation at break. Therefore, organosilane-capped polyols having improved mechanical properties are desired.

SUMMARY

[0002] One aspect of the invention provides silylated polymers comprising a polyol capped with one or more isocyanatosilanes with an isocyanatosilane capping efficiency of no greater than 95%. The polymers have an elongation at break that is at least 15% greater than that of a silylated polymer comprising the polyol capped with the one or more isocyanatosilanes with a capping efficiency of 100%. In some embodiments, the polyols have a weight average molecular weight of at least 8000. In some embodiments, the silylated polymers have an isocyanatosilane capping efficiency in the range from 80% to 95%.

[0003] In some embodiments, the silylated polymers have an elongation at break that is at least 30% greater than that of a silylated polymer comprising the polyol capped with the isocyanatosilanes with a capping efficiency of 100%. This includes embodiments in which the silylated polymers have an elongation at break that is at least 40% greater than that of a silylated polymer comprising the polyol capped with the isocyanatosilanes with a capping efficiency of 100%.

[0004] In some embodiments, the silylated polymers have a tensile strength that is at least 3% greater than that of a silylated polymer comprising the polyol capped with the isocyanatosilanes with a capping efficiency of 100%. This includes embodiments in which the silylated polymers have a tensile strength that is at least 5% greater than that of a silylated polymer comprising the polyol capped with the isocyanatosilanes with a capping efficiency of 100%.

[0005] In some embodiments, the polyol is a polyether polyol. In some embodiments, the polyether polyol is a poly(propylene oxide) polyol, the isocyanatosilane capping efficiency is in the range of 85% to 95%, and the polymer has an elongation at break that is at least 45% greater than that of a silylated polymer comprising the polyol capped with the isocyanatosilanes with a capping efficiency of 100%. In some of these embodiments, the silylated polymer has a tensile strength that is at least 4% greater than that of a silylated polymer comprising the polyol capped with the isocyanatosilanes with a capping efficiency of 100%. In such embodiments, the isocyanatosilane can be (isocyanatomethyl)-methyl- dimethoxy silane.

[0006] In other embodiments, the polyol is a polyester polyol.

[0007] Another aspect of the invention provides methods for making a silylated polymer. The methods comprise reacting a polyol with one or more isocyanatosilanes to provide an isocyanatosilane-capped polyol, wherein the ratio of isocyanatosilane to polyol in the reaction mixture is sufficiently low to provide an isocyanatosilane capping efficiency of no greater than 95%. In some embodiments of the methods, the ratio of isocyanatosilane to polyol in the reaction mixture is sufficiently to provide an isocyanatosilane capping efficiency in the range from 80%> to 95%.

[0008] In some embodiments, the methods provide a silylated polymer having an elongation at break that is at least 30%> greater than that of a silylated polymer comprising the polyol capped with the isocyanatosilanes with a capping efficiency of 100%».

[0009] In some embodiments of the methods, the polyol is a poly ether polyol. In such embodiments, the polyether polyol can be a poly(propylene oxide) polyol, the isocyanatosilane capping efficiency can be in the range of 85% to 95%, and the polymer can have an elongation at break that is at least 45% greater than that of a silylated polymer comprising the polyol capped with the isocyanatosilanes with a capping efficiency of 100%.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 shows the stress-strain curves for silylated poly(propylene oxide) polyols having isocyanatosilane capping efficiencies of 100% (top curve), 90% (middle curve) and 80% (bottom curve).

[0011] FIG. 2 shows the dynamic mechanical relaxation (Ε', relaxation modulus) of silylated poly(propylene oxide) polyols having isocyanatosilane capping efficiencies of 100%, 90% and 80%.

[0012] FIG. 3 shows the dynamic mechanical relaxation (tan delta) of the silylated poly(propylene oxide) polyols of FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0013] One aspect of the present invention provides silylated polymers capped with isocyanatosilanes with a capping efficiency of less than 100%. The reduced capping efficiency provides the silylated polymers with improved elastic properties relative to the same polymers capped with the same isocyanatosilanes with a capping efficiency of 100%. In particular, the present silylated polymers can have improved elongation at break and/or tensile strengths relative to their 100%-capped counterparts. The silylated polymers are well- suited for use in adhesives, sealants and coatings.

[0014] In some embodiments, the silylated polymers are capped with a capping efficiency of 80 to 95%. This includes silylated polymers capped with a capping efficiency of 85 to 95% and further includes silylated polymers capped with a capping efficiency of 88 to 92%. As used herein, the "isocyanatosilane capping efficiency" = [100 x ((number of - OH groups on the polyol capped by the isocyanatosilane)/(total number of -OH groups on the polyol that were initially available for capping by the isocyanatosilane)].

[0015] As used herein, "polyol" refers to an organic molecule having an average of greater than 1.0 hydroxyl groups per molecule. It may also include other functionalities, that is, other types of functional groups. Suitable polyols useful in the preparation of the silylated polymers include, for example, polyether polyols, polyester polyols, poly(alkylene carbonate)polyols, hydroxyl-containing polythioethers, and mixtures thereof.

[0016] Polyether polyols can be made by reacting alkylene oxides, such as ethylene oxide or propylene oxide, in the presence of an active hydrogen-containing initiator compound. Polyether polyols include, for example, polyoxyethylene, polyoxypropylene. polyoxybutylene, and polytetramethylene ether diols and triols which are prepared by reacting an unsubstituted or halogen- or aromatic-substituted alkylene oxide with an initiator compound containing two or more active hydrogen groups such as water, ammonia, a polyalcohol, or an amine. Such methods are described, for example, in U.S. Pat. Nos. 4,269,945; 4,218,543; 4,374,210; and 5,672,652 which are hereby incorporated by reference in their entirety. Preferable alkylene oxides include ethylene oxide, propylene oxide, butylene oxides, styrene oxide, epichlorohydrin, epibromohydrin, and mixtures thereof. Preferable initiator compounds include water, ethylene glycol, propylene glycol, butanediol, hexanediol, glycerin, trimethylol propane, pentaerythritol, hexanetriol, sorbitol, sucrose, hydroquinone, resorcinol, catechol, bisphenols, novolac resins, phosphoric acid, amines, and mixtures thereof.

[0017] Polyester polyols can be formed by condensation or step-growth polymerization of polyhydric alcohols and polycarboxylic acids (or their derivatives). Examples of polycarboxylic acids include succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, maleic acid, trimellitic acid, phthalic acid anhydride, tetrahydrophthalic acid arthydride, hexahydrophthallc acid anhydride, tetrachlorophthalic acid anhydride, endomethylene tetrahydrophthalic acid anhydride, maleic acid anhydride, glutaric acid anhydride, fumaric acid, and mixtures thereof. Examples of polyhydric alcohols include ethylene glycols, propane diols, butane diols, 1,6-hexanediol, 1,8-octanediol, neopentylglycol, glycerol, trimethylol propane, pentaerythritol, quinitol, mannitol, sorbitol, methyl glycoside, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols, polypropylene glycols, and mixtures thereof.

[0018] The polyols used to make the silylated polymers are desirably high molecular weight polyols. Therefore, in some embodiments, the polyol has a weight average molecular weight of about 2,000 or greater. This includes embodiments in which the polyol has a weight average molecular weight of about 4,000 or greater, further includes embodiments in which the polyol has a weight average molecular weight of about 8,000 or greater and still further includes embodiments in which the polyol has a weight average molecular weight of about 10,000 or greater, or even 12,000 or greater.

[0019] In some embodiments, the polyols used in preparing the silylated polymers are high molecular weight polyols prepared by the process which comprises first, contacting one or more initiators with one or more alkylene oxides (e.g., propylene oxide) in the presence of a catalyst comprising calcium having counterions of carbonate and a C₆ to Cio alkanoate in a solvent which does not contain active hydrogen atoms as disclosed in U.S. Pat. No. 6,255,434 (incorporated herein by reference).

[0020] Particular isocyanatosilanes that are useful in the preparation of the silylated polymers include isocyanatomethyl-methyl-dimethoxysilane, 3-isocyanatopropyl-methyl- dimethoxysilane, 3-isocyanatopropyl-trimethoxysilane and 3-isocyanatopropyl- triethoxysilane. [0021] The silylated polymers are characterized by elongations at break and/or tensile strengths that are superior to those of the corresponding silylated polymers made with 100% isocyanatosilane capping efficiencies. For the purposes of this disclosure, a polyol can be considered to be capped with 100% capping efficiency even if it is capped at a slightly lower efficiency (e.g., at least 99.5%) due to the inability of the capping mechanism to achieve a the desired capping efficiency of 100%, provided said inability is not due to the failure to include a stoichiometric amount of isocyanatosilane in the reaction mixture. For the purposes of this disclosure, elongation at break and tensile strength are measured according to ASTM D638.

[0022] In some embodiments, the silylated polymers have an elongation at break that is at least 15%, at least 20%, at least 30%, at least 40% or at least 50% greater than the elongation at break of the same isocyanatosilane-capped silylated polymer having a 100% capping efficiency. For example, silylated poly(propylene oxide) polyols capped with isocyanatosilanes with a capping efficiency of less than 100%, in accordance with this invention, can have tensile elongations at break of 200%, at least 225%, or even at least 245%.

[0023] In some embodiments, the silylated polymers have a tensile strength that is at least 3%, at least 4%, or at least 5% greater than the tensile strength of the same isocyanatosilane-capped polymer having a 100% capping efficiency. For example, silylated poly(propylene oxide) polyols capped with isocyanatosilanes with a capping efficiency of less than 100%, in accordance with this invention, can have tensile strengths of 130 psi, at least 135 psi, or even at least 140 psi.

[0024] Another aspect of the invention provides compositions containing the silylated polymers, including adhesive compositions, sealant compositions and coating compositions. Such compositions include one or more of the silylated polymers and at least one additional ingredient. For example, the additional ingredient can be an additive common to such compositions. Such additives include plasticizers, resins, defoamers, UV stabilizers, viscosity controllers, fragrances, dyes, fillers, clays, preservatives, antioxidants, thixotropic agents and mixtures thereof.

[0025] Suitable fillers include carbon black, titanium dioxide, calcium carbonate, surface treated silica, titanium oxide, fumed silica, and talc. The reinforcing fillers can be used in sufficient amount to increase the strength of the composition and to provide thixotropic properties to the composition. For example, the reinforcing filler can be present in an amount of about 1 part by weight of the composition or greater, about 15 parts by weight or greater, or about 20 parts by weight or greater. In some embodiments, the reinforcing filler is present in an amount of about 40 parts by weight of the composition or less, about 35 parts by weight or less, or about 33 parts by weight or less.

[0026] Clays useful in the composition include kaolin, surface treated kaolin, calcined kaolin, aluminum silicates and surface treated anhydrous aluminum silicates. The clays can be used in any form which facilitates formulation of a pumpable composition. Clays can be used, for example, in an amount of about 0 part by weight of the composition or greater, about 1 part by weight or greater, or about 6 parts by weight or greater. The clays can be used, for example, in an amount of about 20 parts by weight or less of the composition.

[0027] Plasticizers can be used to modify the rheological properties of the compositions to a desired consistency. Suitable plasticizers include alkyl phthalates, such as dialkyl phthalate, partially hydrogenated terpene, commercially available as "HB-40"; trioctyl phosphate; epoxy plasticizers; toluene-sulfamide; chloroparaffins; adipic acid esters; castor oil; toluene; xylene; n-methylpyrolidinone; and alkyl naphthalenes. The preferred plasticizers are the phthalates. The amount of plasticizer in the composition is that amount which gives the desired rheological properties. In some embodiments, plasticizers are used in the compositions in an amount of about 0 part by weight or greater based on the weight of the composition, about 5 parts by weight or greater, about 10 parts by weight or greater, or about 20 parts by weight or greater. In some embodiments, the plasticizer is used in an amount of about 45 parts by weight or less based on the total amount of the composition, about 40 parts by weight or less, about 30 parts by weight or less , or about 25 parts by weight or less.

[0028] Thixotropic agents include alumina, limestone, talc, zinc oxides, sulfur oxides, calcium carbonate, perlite, slate flour, salt (NaCl), and cyclodextrin. The thixotrope may be added to the composition in a sufficient amount to give the desired rheological properties. In some embodiments, the thixotrope is present in an amount of about 0 part by weight or greater based on the weight of the composition, and preferably about 1 part by weight or greater. In some embodiments, the thixotrope is present in an amount of about 10 parts by weight or less based on the weight of the composition and more preferably about 2 parts by weight or less.

[0029] Yet another aspect of the invention provides methods for making a silylated polymer. One basic embodiment of these methods includes the step of reacting a polyol with an isocyanatosilane to provide an isocyanatosilane-capped polyol, wherein the ratio of isocyanatosilane to polyol ratio in the reaction mixture is sufficiently low to provide an isocyanatosilane capping efficiency of no greater than 95%. This includes embodiments in which the isocyanatosilane to polyol in the reaction mixture is sufficiently low to provide an isocyantosilane capping efficiency of about 80 to 95%, about 85 to 95% or about 88 to 92%. The reaction may be facilitated by a catalyst that catalyzes the condensation of the silanol. Tin catalysts useful for the silanol condensation reaction include dialkyltin(IV) salts of organic carboxylic acids, such as dibutyl tin diacetate, dimethyl tin dilaurate, dibutyl tin dilaurate, dibutyl tin maleate or dioctyl tin diacetate. An example of a method of making a silylated poly(propylene oxide) polyol is illustrated in the example, below.

EXAMPLE

[0030] This example illustrates one embodiment of a silylated poly(propylene oxide) polyol and a method of making the same.

[0031] Silane-terminated polymers are prepared using (isocyanatomethyl)-methyl- dimethoxy silane and polypropylene oxide diol (PPO). Reactions between the isocyanatosilane and the polyol are carried out using 600 g of the PPO and sufficient (isocyanatomethyl)-methyl-dimethoxy silane to produce the desired level of capping. The reactor is flushed with Ar. PPO is transferred into the reactor and warmed up to 65 °C. The isocyanatosilane (14.50 g) is quickly added and mixed with the PPO. After complete homogenization, 1.0 g of dibutyl tin dilaurate catalyst is added using a syringe. The reaction mixture is stirred at 65 °C for 4 hours under nitrogen. The reaction is monitored by Fourier transform infrared (FT-IR) spectroscopy following the disappearance of the NCO peak (-2270 cm-1) and the appearance of the ureathane linkage (1710 cm^"1). Tack free time is checked and the silylated polymer is transferred into a bottle and stored under N₂.

[0032] The mechanical properties and dynamic mechanical behavior of moisture cured resins are given in FIGS. 1-3. FIG. 1 shows the stress-strain curves of the silylated polyols made from the PPO (12000 MW) with isocyanatosilane XL-42 ((isocyanatomethyl)-methyl- dimethoxy silane). (Top curve: capping efficiency is 100%; middle curve: capping efficiency is 90%; bottom curve: capping efficiency is 80%). As shown in this graph, both the tensile elongation at break and the tensile strength of the silylated polymer are increased when the isocyanatosilane capping efficiency is reduced from 100%.

[0033] FIG. 2 shows the dynamic mechanical relaxation (Ε', relaxation modulus) behavior of silylated polyols made from the PPO (12000 MW) with isocyanatosilane XL-42. FIG. 3 shows the dynamic mechanical relaxation (tan delta) behavior of silylated polyols made from PPO (12000 MW) with isocyanatosilane XL-42. Dynamic mechanical relaxation is a measurement of the modulus (i.e. stiffness) of the polymer across a temperature range. The flat plateau of this value for all of the compositions in FIG. 2 demonstrates that the polymer (even when using the lower capping levels), maintains its mechanical properties across the useful temperature range. This is important for sealant and adhesive applications.

[0034] All references to the Periodic Table of the Elements refer to the Periodic Table of the Elements published and copyrighted by CRC Press, Inc., 2003. Also, any references to a Group or Groups shall be to the Group or Groups reflected in this Periodic Table of the Elements using the IUPAC system for numbering groups. Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percents are based on weight and all test methods are current as of the filing date of this disclosure. For purposes of United States patent practice, the contents of any referenced patent, patent application or publication are incorporated by reference in their entirety (or its equivalent US version is so incorporated by reference) especially with respect to the disclosure of synthetic techniques, product and processing designs, polymers, catalysts, definitions (to the extent not inconsistent with any definitions specifically provided in this disclosure), and general knowledge in the art.

[0035] Numerical ranges include all values from and including the lower and the upper values, in increments of one unit, provided that there is a separation of at least two units between any lower value and any higher value. As an example, if a compositional, physical or other property is from 100 to 1,000, then the intent is that all individual values, such as 100, 101, 102, etc., and sub ranges, such as 100 to 144, 155 to 170, 197 to 200, etc., are expressly enumerated. For ranges containing values which are less than one or containing fractional numbers greater than one (e.g., 1.1, 1.5, etc.), one unit is considered to be 0.0001, 0.001, 0.01 or 0.1, as appropriate. For ranges containing single digit numbers less than ten (e.g., 1 to 5), one unit is typically considered to be 0.1. These are only examples of what is specifically intended, and all possible combinations of numerical values between the lowest value and the highest value enumerated, are to be considered to be expressly stated in this disclosure.

[0036] Definitions:

[0037] "Polymer" means a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term polymer thus embraces the term homopolymer, usually employed to refer to polymers prepared from only one type of monomer, and also embraces the term interpolymer. "Interpolymer" means a polymer prepared by the polymerization of at least two different types of monomers. This generic term includes copolymers, usually employed to refer to polymers prepared from two different types of monomers, and polymers prepared from more than two different types of monomers, e.g., terpolymers, tetrapolymers, etc.

[0038] "Composition", "formulation" and like terms means a mixture or blend of two or more components.

[0039] The term "comprising" and its derivatives are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, any process or composition claimed through use of the term "comprising" may include any additional steps, equipment, additive, adjuvant, or compound whether polymeric or otherwise, unless stated to the contrary. In contrast, the term, "consisting essentially of excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability. The term "consisting of excludes any component, step or procedure not specifically delineated or listed. The term "or", unless stated otherwise, refers to the listed members individually as well as in any combination.

[0040] Although the invention has been described in considerable detail through the preceding description, drawings and examples, this detail is for the purpose of illustration. One skilled in the art can make many variations and modifications without departing from the spirit and scope of the invention as described in the appended claims.

Claims

CLAIMS What is claimed is:

1. A silylated polymer comprising a polyol capped with one or more

isocyanatosilanes with an isocyanatosilane capping efficiency of no greater than 95%, the polymer having an elongation at break that is at least 15% greater than that of a silylated polymer comprising the polyol capped with the one or more isocyanatosilanes with a capping efficiency of 100%.

2. The polymer of claim 1 , in which the polyol has a weight average molecular weight of at least 8000.

3. The polymer of claim 1 , having an elongation at break that is at least 30% greater than that of a silylated polymer comprising the polyol capped with the

isocyanatosilanes with a capping efficiency of 100%.

4. The polymer of claim 1 , having a tensile strength that is at least 3 % greater than that of a silylated polymer comprising the polyol capped with the isocyanatosilanes with a capping efficiency of 100%.

5. The polymer of claim 1, in which the polyol is a polyether polyol.

6. The polymer of claim 5, wherein the polyether polyol is a poly(propylene oxide) polyol, the isocyanatosilane capping efficiency is in the range of 85% to 95%, and the polymer has an elongation at break that is at least 45% greater than that of a silylated polymer comprising the polyol capped with the isocyanatosilanes with a capping efficiency of 100%.

7. The polymer of claim 1 , wherein the isocyanatosilane is (isocyanatomethyl)- methyl-dimethoxy silane.

8. A method for making a silylated polymer, the method comprising reacting a polyol with one or more isocyanatosilanes to provide an isocyanatosilane-capped polyol, wherein the ratio of isocyanatosilane to polyol in the reaction mixture is sufficiently low to provide an isocyanatosilane capping efficiency of no greater than 95%.

9. The method of claim 8, wherein the silylated polymer has an elongation at break that is at least 30% greater than that of a silylated polymer comprising the polyol capped with the isocyanatosilanes with a capping efficiency of 100%.

10. The method of claim 9, wherein the polyether polyol is a poly(propylene oxide) polyol, the isocyanatosilane capping efficiency is in the range of 85% to 95%, and the polymer has an elongation at break that is at least 45% greater than that of a silylated polymer comprising the polyol capped with the isocyanatosilanes with a capping efficiency of 100%.