DE4017940A1 - Alpha, omega-di:functional prepolymers with thiol end-gps. - by reaction of di:isocyanate(s) with di:thiol(s), opt. in presence of catalyst - Google Patents

Abstract

Prepolymers (I) are produced by reaction of di-isocyanates (II) with dithiols (III) in the mol. ratio (1:10)-(9.5:10), pref. (5:10)-(9:10). In (I) x = 0.11-20 (average); R, R' = opt. substd. aliphatic, aromatic, cycloaliphatic or other difunctional residue (e.g. ether or ester) which can combine with 2 NCO or 2 SH gps.. Mixts of different (II) and/or different (III) are used and reaction effected in bulk or in the presence of solvent or diluent and/or catalysts e.g. tert. amines or metal complexes. Pref. (III) is e.g. of formula HSCH2CH2OCH2CH2OCH2CH2SH. USE/ADVANTAGE - (I) are useful as intermediates for the prodn. of linear and crosslinked polymers, casting resins, composites, laminates, adhesives, coatings and paints, and as starting materials for the prodn. of high-mol. wt. thermoplastics. Process provides a simple, solvent-free process for the prodn. of (I) in high yield. (4pp)

Description

The invention relates to a process for the preparation of difunctional Prepolymers with thiol end groups, used as intermediates for the production of linear polymers, networks, Casting resins, composites, laminates, adhesives, coatings, Varnishes and as starting products for the production of thermoplastic can serve high molecular weight materials and through a solvent-free simple reaction produced in high yield can be. They are compounds of the following Type:

The chemical and physical properties of these prepolymers can vary by the structure and molecular weight of P. will.

The use of prepolymers for the production of polymer products has the advantage over the use of monomers that Reduced toxicity and volatility of the reaction components are, part of the heat of reaction has already been removed and that a significantly lower volume contraction occurs. Across from the high polymers, prepolymers have the advantage of a low one Viscosity, lower flow and melting ranges and a better one Solubility.

Prepolymers with thiourethane structural members and two thiol end groups are not known.

The object of the invention is to prepare prepolymers, the two reactive thiol end groups in the average molecule  wear and thus a large field of application as intermediate products for the production of new prepolymer secondary products open. Furthermore, an easy-to-use solvent-free Synthesis aimed for the target products in high yields results.

According to the invention, α, ω-difunctional prepolymers with two Obtain thiol end groups in that diisocyanates with dithiols in a molar ratio of 1.0: 10.0 and 9.5: 10.0, preferably in a molar ratio between 5:10 and 9:10 are implemented, wherein x represents an average value between 0.11 and 20 and R and R ′ substituted or unsubstituted aliphatic, araliphatic, aromatic, cycloaliphatic or other difunctional radicals such as ethers or esters, which are two isocyanate groups or can connect two thiol groups.

It was further found that the reactions according to the invention proceed according to equation (1) and that in most cases the prepolymers have an average degree of polymerization P _n which follows the formula (2), provided that the reaction leads to the isocyanate groups being virtually completely consumed becomes.

Equation (1):

Equation (2):

For example, the reaction of 5 moles of an isocyanate with 10 moles of a dithiol results in a prepolymer of structure A with an average degree of polymerization P _n = 3 and x = 1. In this example, r = 0.5. The process can also be carried out in such a way that mixtures of different diisocyanates and / or different dithiols are used.

The prepolymer formation without solvents or diluents is advantageous at room temperature or in the temperature range 50 to 100 ° C, optionally in the presence of a catalyst such as tert. Amines or metal complexes performed. After complete Turnover of the isocyanate groups, the prepolymers have a certain number average molecular weight, which is determined by the molar ratio r Reaction components is specified.

The prepolymers according to the invention consist of a series of Oligomers (x = 1, 2, 3, 4...), Often with dithiol compounds remain (x = 0).

The prepolymer formation can also be carried out in inert solvents such as Dioxane, THF, DMSO, benzene, toluene, ethyl acetate can be carried out. For example, a transparent, colorless, viscous Prepolymer with α, ω-difunctional SH end groups from a mixture of 1 mol of trimethylhexamethylene diisocyanate and 2 Moles of triglycol dithiol by reaction for 48 hours at room temperature produced. The prepolymer formed is in CHCl₃ / CH₃OH (Vol.- 4: 1), dioxane, THF, benzene soluble. It is beneficial, too soluble in reactive, unsaturated monomers such as Methyl methacrylate, diethylene glycol bis methacrylate, bisallyl esters such as B. Phthalic acid bisallyl ester.

Diisocyanates which are very suitable for the purposes of the invention are Hexamethylene diisocyanate, 3-isocyanatomethyl-3,5,5-trimethyl  cyclohexyl isocyanate (IPDI), 2,2,4 (2,4,4) trimethylhexamethylene diisocyanate (TMDI), naphthylene diisocyanate-1,5, diphenylmethane diisocyanate, Toluene diisocyanate (2.4; 2.6 mixture or pure isomers).

Corresponding dithiols suitable for the production process of the formula HS-R'-SH may be mentioned:

HSCH₂CH₂OCH₂CH₂OCH₂CH₂SH

HS (CH ₂ ) _n SH n = 6, 8, 10

HSCH₂CH (SH) CH₂OH

HSCH₂COOCH₂CH₂OCH₂CH₂OCH₂CH₂OOCCH₂SH

HSCH ₂ COO (CH ₂ ) _n OOCCH ₂ SH n = 6.8

HSCH₂C₆H₄CH₂SH

HSCH₂COOC₆H₄OOCCH₂SH

HSCH₂COOC₆H₄CH₂C₆H₄OOCCH₂SH

The invention is illustrated in the following working examples explained in more detail.

example 1

7.29 g (40 mmol) of triglycol dithiol are mixed with 4.206 g (20 mmol) of 2,2,4 (2,4,4) trimethylhexamethylene diisocyanate and 0.011 g of pyridine with stirring. After 48 hours of reaction at room temperature, a viscous, colorless prepolymer is obtained which, for example, is soluble in CHCH₃OH (vol. Ratio 4: 1), dioxane, THF, acetone and contains two thiol end groups per average molecule. M _n (VPO): 637, n: 1.5342, η = 2299 mPas.

Example 2

5.469 g (30 mmol) of triglycol dithiol are mixed with 4.206 g (20 mmol) of 2,2,4 (2,4,4) trimethylhexamethylene diisocyanate and 0.0096 g of pyridine with stirring. After 48 hours of reaction at room temperature, a colorless, highly viscous prepolymer was obtained. M _n (VPO): 920, n: 1.5345, η = 10 143 mPas.

Claims (6)

1. A process for the preparation of α, ω-difunctional prepolymers with two thiol end groups, characterized in that diisocyanates with dithiols in a molar ratio of 1.0: 10.0 and 9.5: 10.0, preferably in a molar ratio between 5, 0: 10.0 and 9.0: 10.0 are implemented, where x represents an average value between 0.11 and 20 and R and R ′ represent substituted or unsubstituted aliphatic, aromatic, cycloaliphatic or other difunctional radicals such as ethers or esters, which can connect two isocyanate groups or two thiol groups: 2. The method according to claim 1, characterized in that mixtures various diisocyanates and / or various dithiol compounds be used. 3. The method according to claim 1 and 2, characterized in that the Reaction in the presence of solvents or diluents and / or of reaction catalysts such as tertiary amines or metal complexes is carried out. 4. The method according to claim 1 to 3, characterized in that the Implementation in bulk or without solvent or diluent is carried out. 5. The method according to claim 1 to 4, characterized in that as Diisocyanate prepolymers with two isocyanate groups used will. 6. The method of claim 1 to 5, characterized in that to be implemented as a dithiol compounds aliphatic, aromatic, araliphatic or cycloaliphatic dithiols, preferably HSCH₂CH₂OCH₂CH₂OCH₂CH₂SHHS (CH _{2) n} SH n = 6, 8, 10HSCH₂CH (SH) CH₂OHHSCH₂COOCH₂CH₂OCH₂CH₂OCH₂CH₂OOCCH₂SHHSCH ₂ COO (CH ₂ ) _n OOCCH ₂ SH n = 6, 8HSCH₂C₆H₄CH₂SH HSCH₂COOC₆H₄OOCCH₂SHHSCH₂COOC₆H₄CH₂C₆H₄OOCCH₂SH