CS198822B1 - Method of crosslinking organosiliceous resins - Google Patents

Description

The invention relates to a process for curing organosilicon resins using complex compounds.

Complex compounds containing a hexacoordinated silicon atom have been known for some time, but have been studied primarily from academic point of view and little attention has been paid to their practical use (Eaborn: Organosilicon Couponds, Butterworth Scientific Publications, London 1960; Prague 1973). In British Pat. No. 1,077,925 discloses the possibility of using some hexacoordinated silicon complexes as catalysts for epoxy resins and silicone rubbers.

Research has now found that certain complex compounds containing a hexo-coordinated silicon atom can be advantageously applied as catalysts for the polymerization of organosilicon resins. The process for curing the organosilicon resins according to the invention is characterized in that the organosilicon resin having the parameters R / Si = 0.7 and Ph / Me = 0.4 to 1.8, wherein R = phenyl + methyl is mixed with a catalyst of the general formula

198 822

198 822 in an amount of 0.1 to 3 wt. on a resin wherein A is a cation of formula

O

B is an unprotonated amine of formula (II) (III), is an aromatic o-dihydroxy compound residue

H ₂ N (CH ₂ ) _r NH ₂ (IV), where r = 2 to 6, n - 0 to 2, and curing is performed after application at a temperature of 120 ° C to 250 ° C.

An advantage of the process for curing the organosilicon resins of the invention over known methods described, for example, in British Patent 683,905; 768,961; NSR Pat.958,702; 1,907.017; 2,255,576; US Pat. 3,070,559; 3,264,260; No. 3,627,729, is that the new catalysts are highly latent at normal temperature and even briefly heated up to 90 ° C, operate quickly at temperatures above 120 ° C and are easy to prepare.

The organosilicon resin polymerization catalyst of the present invention can be prepared by reacting an organic amine, an aromatic o-dihydro compound, and a tetraalkoxysilane, for example according to British Patent 1,077,939. As the amine, a primary, secondary or tertiary aliphatic amine or polyamine, a quaternary ammonium base, or heterocyclic compounds such as pyridine, etc. can be used. A complex catalyst containing a hexacoordinated silicon atom can be prepared using an aromatic compound containing two hydroxyl groups attached to ortho, for example 1,2-dihydroxybenzene, 1,2 dihydroxynaphthalene, 2,3-dihydroxydiphenyl, 3,4-dihydroxybenzoic acid, etc. For the preparation of the catalyst, tetraalkoxysilane Si (OR) 2, where R is methyl or ethyl, may be advantageously used. The complex catalyst is added according to the invention in an amount of 0.1 to 3% by weight. on resin. • Type B compounds have not been applied to cure organosilicon resins yet.

The process according to the invention can cure organosilicon resins in a wide range of parameters R / Si = 0.7 to 1.8 (R = methyl + phenyl) and Ph / Me = 0.4 to 1.8 (Ph and Me are phenyl and methyl respectively) groups bonded to silicon atoms) prepared by cosdrolysis of the respective methyl and phenylchlorailanes, for example according to the '

New complex catalysts can be homogenized with an organosilicon resin in solution or without solvent, for example on calenders or kneaders in plastic

198 822 elevated temperatures, for example 60 ° C to 90 ° C. The catalysed resins are stable for a long time, even in solutions whose viscosity increases only very slowly, and during the homogenization in the plastic state there is no undesirable polymerization of the resin at elevated temperatures up to 90 ° C.

The process for curing the organosilicon resins of the invention can be applied using such resins in, for example, reinforced materials, paints and the like.

The examples illustrate the curing process of the invention as well as the practical application of the process.

Example 1

Preparation of the catalyst

By reaction of tetraethoxysilane, pyrocatechin and ethylenediamine a complex (h ₃ n ch ₂ ch ₂ nh ₃ ) of the network (c ₆ h ₄ o ₂ ) ₃ (h ₂ nch ₂ ch ₂ nh ₂ ) was prepared.

Elementary analysis:

calculated 55,67% C, 6,37% H, 11.81% N, 5.92 % Si found 55,13% C, 6.86% H, 11.84% N, 5.49 % Si. Neutralization equivalent: calculated 117 found 118

266 ° C (dec.)

Note:

The neutralization equivalent is the amount of the complex in grams that neutralizes one mole of the standard acid.

Resin curing

To a 60.0% methylphenylsiloxied resin solution (R / Si = 1.15, Ph / Me = 0.80, acid number 0.02 mg KOH / g, SiOCHp content 3.61% by weight) in acetone + ethylene glycol monoethyl ether (weight ratio 1: 1) complex (H ₃ N CH ₃ CH ₃ CH ₂ N 4) [SiCl ₃ H ₃ O ₂ O] 2 (H ₃ N CH ₃ CH ₃ CH ₃ NH 4) was added. After homogenization, gelling times were measured according to Gough and Smith (J.Appl. Polymer Sci. 2,362,660) (Table I).

Table I

konc.katal. % by weight of resin gelation time (s) storage time (days) T = 108 ° C; T = 136 ° C Mp: 153 ° C 2.00 362 97 64 7 0.75 9650 1122 191 45

198 822

A significant difference in the curing speed at 108-153 ° C is apparent from Table 1, which suggests an advantageous rapid crosslinking of the organosilicon resin at a high temperature while maintaining latency at low temperatures. The shelf life of the catalysed resin solutions is very good. By storage time is meant here the time interval from the catalysis of the resin to the rapid increase in lacquer viscosity.

Example 2

The reaction of pyrocatechin, ethylenediamine and tetraethoxysilane was prepared according to Brit.

pat.1,077.925 complex (HjN CH ₂ CH ₂ NH ₃ ) s (c ₆ h ₄ o ₂ ) ₃ (H ₂ NCH ₂ CH ₂ NH ₂ ) _{1/5 <}

Elementary analysis:

calculated H, 6.54; H, 6.54; N, 12.66 found H, 6.97; H, 6.97; N, 12.77 Neutralization equivalent: calculated 110 found 110

Melting point: 296 ° C (and decomposition)

5.77% Si) 5.75% Si.

The properties of the organosilicate resin + system using a procedure analogous to Example 1.

said complex catalysts are

Example 3

320 g of methylphenylsiloxane resin prepared according to the author's certificate No. 158093 of the parameters as in example 1, freed from solvent by distillation under pressure

2.6 kPa and a maximum of 383 K and pulverized, were mixed with 770 g of ground fused silica having a particle size of max.0.040 mm, and 0.5 g of inactive carbon black. The mixture was homogenized on a plasticizer with 6.8 g of complex (H 2 N CH 3 CH 3 CH 3 NH 3) [Si (C 3 H 4 O 3) 4] (H 3 N CH 3 CH 3) at 65-75 ° C for 5 minutes. After cooling, the mass was ground and used for the preparation of test rods by means of an overpressure technique. Pressing was carried out at 170 ° C under a pressure of 6 MPa, pressing time 6 minutes. The bars were cured for 2 hours at 200 ° C and their bending strength was 53 MPa.

Claims (1)

SUBJECT OF THE INVENTION Process for curing organosilicon resins having parameters R / Si = 0.7 to 1.8, where R is the sum of the phenyl and methyl groups bonded to the silicon atom, Ph / Me = 0.4 to 1.8, where Ph and Me are phenyl and methyl groups attached to silicon atoms, characterized in that the organosilicon resin is mixed in an amount of 0.1 to 3% by weight on the resin with a catalyst of the formula 198 822 A Ú R Si <2 \ / ⁰ θ-J wherein A is a cation of the formula [H ₂ N (CH _{2) r} -NH _3] ⁺ or P ₃ N (CH _{2) r} -NH _3] (I), (II), ( III), where r = 2 to 6, m = 1 or 2, R 1 is a 1,2-dihydroxybenzene residue, B is the amine of the general formula θ non-proton H ₂ N (CH ₂ ) _r NH ₂ (IV), where r = 2 to 6, n = 0 to 2, and curing is performed after application at 120 250 ° C.