Toughness-increased phenolic resin and preparation thereof
View Patent ↗A phenolic resin that increases its toughness by polydimethylsiloxane and a process of preparing the same is provided. Polydimethylsiloxane is added as a coupling agent in a γ-glycidoxypropyltrimethoxysilane-modified phenolic resin to improve the compatibility between polydimethylsiloxane and the phenolic resin. Then, tetraethoxysilane is added to conduct hydrolysis condensation and obtain tougher and thermally stable phenolic resin.
1. A phenolic resin which has an increased toughness due to including therein a polydimethylsiloxane, and which is a hydrolysis condensation product of a first precursor, a second precursor and tetraethoxysilane,
wherein the first precursor includes a phenolic resin and γ-glycidoxypropyltrimethoxysilane in which hydroxyl groups of the phenolic resin are grafted onto an epoxy group of the γ-glycidoxypropyltrimethoxysilane, and
wherein the second precursor includes a coupling agent and an hydroxyl-terminated polydimethylsiloxane in which hydroxyl groups of the polydimethylsiloxane are grafted at a first terminal of the coupling agent and a second terminal of the coupling agent has a branched siloxane structure.
2. The phenolic resin of claim 1 , wherein the phenolic resin is a novolac resin.
3. The phenolic resin of claim 1 , wherein the coupling agent is γ-glycidoxypropyltrimethoxysilane.
4. The phenolic resin of claim 1 , wherein the coupling agent is 3-isocyanato-propyltriethoxysilane.
5. The phenolic resin of claim 1 , wherein the coupling agent is tetraethoxysilane.
6. The phenolic resin of claim 5 , wherein the second precursor is obtained by using potassium acetate in ethanol solution as the coupling agent and a catalyst used for polydimethylsiloxane.
7. The phenolic resin of claim 1 , wherein the polydimethylsiloxane has a weight average molecular weight of 400-700.
8. A process of preparing a phenolic resin having an increased toughness due to including therein a polydimethylsiloxane, the process comprising the steps of:
performing a ring opening reaction on a novolac resin by using γ-glycidoxypropyltrimethoxysilane to form a first precursor;
reacting a coupling agent with an hydroxyl-terminated polydimethylsiloxane to form a second precursor; and
using the first precursor, the second precursor and tetraethoxysilane for hydrolysis condensation to form the phenolic resin having an increased toughness due to including therein a polydimethylsiloxane.
9. The process of claim 8 , wherein the phenolic resin is a novolic resin.
10. The process of claim 8 , wherein the molar ratio of the coupling agent and polydimethylsiloxane is 2.1:1.
11. The process of claim 8 , wherein the coupling agent is γ-glycidoxypropyltrimethoxysilane.
12. The process of claim 8 , wherein the coupling agent is 3-isocyanato-propyltriethoxysilane.
13. The process of claim 8 , wherein the coupling agent is tetraethoxysilane.
14. The process of claim 13 , wherein during reacting to farm the second precursor a catalyst is used which is potassium acetate in ethanol solution.
15. The process of claim 8 , wherein the polydimethylsiloxane has a weight average molecular weight of 400-700.