Curable high hardness silicone composition and composite articles made thereof

Patent metadata

Field	Value
Publication number	US-10829640-B2
Application number	US-201716078370-A
Country	US
Kind code	B2
Filing date	Feb 21, 2017
Priority date	Feb 23, 2016
Publication date	Nov 10, 2020
Grant date	Nov 10, 2020

Abstract

A liquid curable silicone elastomer composition is disclosed. The composition comprises: an organopolysiloxane (A) comprising: an organopolysiloxane (A1) containing at least 2 alkenyl groups bonded to silicon atom per molecule and having a total alkenyl content of from 0.01 to 1.5 mmol/g, and an organopolysiloxane (A2) containing at least 2 alkenyl groups bonded to silicon atom per molecule and having a total alkenyl content of from 5.0 to 15.0 mmol/g; an organopolysiloxane (B) comprising an organopolysiloxane (B1) containing at least 2 silicon-bonded hydrogen atoms per molecule provided by siloxy units of the type (R2HSiO1/2)x where R is independently selected from hydrogen, an aliphatic a hydrocarbyl, an aromatic hydrocarbyl, or an organyl group and x≥2; a platinum based catalyst (C); an inhibitor (D) selected from the group consisting of acetylenic alcohols and their derivatives; and a silica filler (E).

First claim

The invention claimed is:

1. A liquid curable silicone elastomer composition, said composition comprising:
an organopolysiloxane (A) comprising;
an organopolysiloxane (A1) containing at least 2 silicon-bonded alkenyl groups per molecule and having a total alkenyl content of from 0.01 to 1.5 mmol/g, and an organopolysiloxane (A2) containing at least 2 silicon-bonded alkenyl groups per molecule and having a total alkenyl content of from 5.0 to 15.0 mmol/g;

an organopolysiloxane (B) comprising;
an organopolysiloxane (B1) containing at least 2 silicon-bonded hydrogen atoms per molecule, wherein the silicon-bonded hydrogen atoms are provided in the form of siloxy units of the type (R 2 HSiO 1/2 ) x where R is independently selected from hydrogen, an aliphatic hydrocarbyl, an aromatic hydrocarbyl, or an organyl group and x≥2, and optionally, an organopolysiloxane (B2) containing at least 2 silicon-bonded hydrogen atoms per molecule, wherein the silicon-bonded hydrogen atoms are provided in the form of siloxy units of the type (RHSiO 2/2 ) z where R is independently selected from hydrogen, an aliphatic hydrocarbyl, an aromatic hydrocarbyl, or an organyl group and z≥2, wherein the molar amount of silicon-bonded hydrogen in the form of siloxy units of the type (R 2 HSiO 1/2 ) x is >40 mol % of the total silicon-bonded hydrogen atoms content of organopolysiloxane (B);

a platinum based catalyst (C);
an inhibitor (D) selected from the group consisting of acetylenic alcohols and their derivatives; and
a silica filler (E);
wherein a silicone elastomer cured from the liquid curable silicone elastomer composition has a hardness >75 Shore A without post cure.

2. The liquid curable silicone elastomer composition of claim 1 , wherein the organopolysiloxane (A2) is selected from:
compounds having general formula (II)
(R 2 R″SiO 1/2 ) b (R 3 SiO 1/2 ) c (RR″SiO 2/2 ) d (R 2 SiO 2/2 ) e (R″SiO 3/2 ) f (RSiO 3/2 ) g (SiO 4/2 ) h   (II)

where R″ is an alkenyl functional group, and R is independently selected from hydrogen, an aliphatic hydrocarbyl, an aromatic hydrocarbyl, or an organyl group, and where the sum “b+c+d+e+f+g” provides for a total alkenyl content of from 5.0 to 15.0 mmol alkenyl/g; and/or
compounds having general formula (III)
(R 2 R″SiO 1/2 ) b (R 3 SiO 1/2 ) c (SiO 4/2 ) h   (III)

where R″ is an alkenyl functional group, and R is as described above, and where h≥1, b≥2, and c is an integer ≥0, provided b+c=4 when h=1, having a total alkenyl content of from 5.0 to 15.0 mmol alkenyl/g; and/or
cyclic compounds having general formula (IV)
(RR″SiO 2/2 ) d (R 2 SiO 2/2 ) e   (IV)

where R″ is an alkenyl functional group, and R is as described above, and where d≥3 and e≥0 having a total alkenyl content of from 5.0 to 15.0 mmol alkenyl/g; and/or
linear compounds having general formula (V)
(RR″SiO 2/2 ) d (R 2 SiO 2/2 ) e   (IV)

where R″ is an alkenyl functional group, and R is as described above, and where the sum “b+c +d+e” provides for a total alkenyl content of from 5.0 to 15.0 mmol alkenyl/g.

3. The liquid curable silicone elastomer composition in accordance with claim 2 , wherein the organopolysiloxane (A2) comprises at least one compound having the general formula (II).

4. The liquid curable silicone elastomer composition in accordance with claim 2 , wherein the organopolysiloxane (A2) comprises at least one compound having the general formula (III).

5. The liquid curable silicone elastomer composition in accordance with claim 2 , wherein the organopolysiloxane (A2) comprises at least one compound having the general formula (IV).

6. The liquid curable silicone elastomer composition in accordance with claim 2 , wherein the organopolysiloxane (A2) comprises at least one compound having the general formula (V).

7. The liquid curable silicone elastomer composition in accordance with claim 1 , wherein the organopolysiloxane (B1) is a branched polymer having general formula (VI)
(R 2 HSiO 1/2 ) x (R 3 SiO 1/2 ) y (RHSiO 2/2 ) z (R 2 SiO 2/2 ) p (RSiO 3/2 ) q (HSiO 3/2 ) v (SiO 4/2 ) r   (VI)

where R is independently selected from hydrogen, an aliphatic hydrocarbyl, an aromatic hydrocarbyl, or an organyl group, and H is hydrogen, and where x ≥2, y ≥0, z ≥0, p ≥0, v ≥0, and at least one of q or r ≥1.

8. The liquid curable silicone elastomer composition in accordance with claim 1 , wherein the organopolysiloxane (B2) is present and has general formula (VII)
(R 2 HSiO 1/2 ) x (R 3 SiO 1/2 ) y (RHSiO 2/2 ) z (R 2 SiO 2/2 ) p (RSiO 3/2 ) q   (VII)

where R is independently selected from hydrogen, an aliphatic hydrocarbyl, an aromatic hydrocarbyl, or an organyl group, and H is hydrogen, and where x ≥0, y ≥0, z ≥2, p ≥0, q ≥0.

9. The liquid curable silicone elastomer composition in accordance with claim 1 , wherein the inhibitor (D) is selected from the group consisting of 1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol, 3-butyn-1-ol, 3-butyn-2-ol, propargylalcohol, 2-phenyl-2-propyn-1-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclopentanol, 1-phenyl-2-propynol, 3-methyl-1-penten-4-yn-3-ol, and mixtures thereof.

10. The liquid curable silicone elastomer composition in accordance with claim 1 , wherein the silica filler (E) contains at least one alkenyl group covalently bound to its surface.

11. The liquid curable silicone elastomer composition in accordance with claim 1 , comprising:
35 to 75 weight % (wt %) of the organopolysiloxane (A1);
0.5 to 10 wt % of the organopolysiloxane (A2);
1 to 15 wt % of the organopolysiloxane (B1);
0.1 to 15 wt % of the organopolysiloxane (B2);
0.1 to 500 weight-ppm (parts per million) of platinum atom in the catalyst (C) based on the total weight of reactive organopolysiloxanes (A) and (B);
10 to 10,000 weight-ppm of the inhibitor (D); and
10 to 40 wt % of the silica filler (E);
except for catalyst (C), on the total weight of the composition.

12. A process for preparing a cured silicone elastomer, said process comprising:
1) forming a mixture of the liquid curable silicone elastomer composition according to claim 1 ; and
2) curing the mixture at a temperature of from 100 to 220° C.;
optionally, wherein the mixture is formed by providing at least 2 separate compositions.

13. A silicone elastomer cured from the liquid curable silicone elastomer composition according to claim 1 .

14. The silicone elastomer of claim 13 , having a hardness >75 Shore A, optionally a hardness >80 Shore A, optionally a hardness >85 Shore A.

15. An article cured from the liquid curable silicone elastomer composition according to claim 1 .

16. The article of claim 15 , selected from the group consisting of sports products, diving masks and gears, feeding bottle nipples and rubber teats, pacifiers, switch covers, spark-plug connectors, medical products and devices, single-wire seals, plug connector seals, tubing and valves, automobile components, and electric and electronic parts.

17. A composite part comprising a first silicone elastomer cured from a first liquid silicone rubber composition, and a second silicone elastomer cured from a second liquid silicone rubber composition which is different from the first liquid silicone rubber composition, wherein the first liquid silicone rubber composition is the liquid silicone rubber composition according to claim 1 , and wherein the second silicone elastomer has a hardness <75 Shore A.

18. The composite part of claim 16 , selected from the group consisting of housings with a silicone seal or gasket, plugs and connectors,

Assignees

• Dow Silicones Corp

Inventors

• Beyer Patrick
• Chen Yusheng
• Wang Shaohui
• Wolf Hans Peter

Classifications

• C08G77/20

  containing silicon bound to unsaturated aliphatic groups · CPC title

• B33Y80/00

  Products made by additive manufacturing · CPC title

• C08G77/12

  containing silicon bound to hydrogen · CPC title

• C08L2205/035

  containing four or more polymers in a blend · CPC title

• A61M25/00

  Catheters; Hollow probes (dilators A61M29/00; {peritoneal catheters A61M1/285; tracheal tubes A61M16/04; for drainage A61M27/00; for uterus, vagina or rectum A61M31/00} ; for measuring or testing A61B; {materials for catheters A61L29/00}) · CPC title