Method for making elastomeric articles

Patent metadata

Field	Value
Publication number	US-12370753-B2
Application number	US-202017634929-A
Country	US
Kind code	B2
Filing date	Aug 11, 2020
Priority date	Aug 13, 2019
Publication date	Jul 29, 2025
Grant date	Jul 29, 2025

Abstract

A method for molding shaped silicone elastomeric articles from room temperature curable silicone compositions, which are practically not suited to being processed using extrusion techniques, is provided. The method enables the room temperature curable silicone composition to cure in a predefined shape ( 6 ) into which it is introduced to form a shaped silicone elastomeric article. The articles may be, for the sake of example, suitable for use as spacers for insulating glass units (IGUs).

First claim

The invention claimed is:

1. A method for molding elongate shaped silicone elastomeric articles from room temperature curable silicone compositions, the method comprising:
(i) draping a film ( 2 ) over a mold ( 4 ) comprising two or more predefined shapes ( 6 ) to establish an evacuatable volume ( 8 ) between the film ( 2 ) and each predefined shape ( 6 ) in the mold ( 4 );
(ii) applying suction to the evacuatable volume ( 8 ) between a first predefined shape ( 6 a ) of the mold ( 4 ) and the film ( 2 ) to establish an at least partial vacuum within the evacuatable volume ( 8 ) of said first predefined shape ( 6 a ), such that the film ( 2 ) forms a filmic inner lining conforming to the first predefined shape ( 6 a ) of the mold ( 4 );
(iii) additionally, applying suction to the evacuatable volume ( 8 ) between a second predefined shape ( 6 b ) of the mold ( 4 ) and the film ( 2 ), which second predefined shape ( 6 b ), is adjacent to the first predefined shape ( 6 a ), to also establish an at least partial vacuum within the evacuatable volume of said second predefined shape ( 6 b ) and consequently also forms a filmic inner lining conforming to the second predefined shape ( 6 b ) of the mold ( 4 );
(iv) sequentially repeating step (iii) until each predefined shape ( 6 ) in the mold ( 4 ) has an at least partial vacuum within the evacuatable volume ( 8 ) thereof and the film ( 2 ) forms a filmic inner lining conforming to each respective predefined shape ( 6 ) of the mold ( 4 );
(v) introducing room temperature curable silicone composition onto the filmic inner lining conforming to one or more predefined shapes ( 6 ) of the mold ( 4 ), which composition is designed to flow sufficiently to conform to the predefined shape ( 6 ) in the mold ( 4 ) into which it has been introduced; and
(vi) enabling the room temperature curable silicone composition to cure in the predefined shape ( 6 ) into which it was introduced to form an elongate shaped silicone elastomeric article;
wherein the elongate shaped silicone elastomeric articles are suitable for use as spacers in the manufacture of insulated glazing units.

2. The method in accordance with claim 1 , wherein the predefined shapes ( 6 ) are elongate channels having a base and a first wall and a second wall, which first and second wall are substantially parallel to each other and perpendicular to the base.

3. The method in accordance with claim 2 , wherein the parallel walls have round edges and are designed to be greater in depth than the depth of the elastomeric article to be cured in the mold ( 4 ).

4. The method in accordance with claim 2 , wherein a guide ( 16 ) is inserted at each extremity of the channels to guide the film ( 2 ) into its respective channel ( 6 ) and/or to adjust the length of one or more channels ( 6 ) in the mold ( 4 ).

5. The method in accordance with claim 1 , wherein the film ( 2 ) is fixed to one edge of the mold ( 4 ).

6. The method in accordance with claim 5 , wherein the film ( 2 ) is clamped at either one extremity of the mold ( 4 ), or along a wall of a channel not located near the extremity of the mold ( 4 ).

7. The method in accordance with claim 5 , wherein the fixing is achieved by clamping the film ( 2 ) using a single clamp ( 12 ) along the length of the mold ( 4 ) or using a bar ( 13 ) fixed in place by a series of clamps ( 12 ) positioned equidistant from each other along the length of the mold ( 4 ).

8. The method in accordance with claim 1 , wherein the mold ( 4 ) is a one part unit or is in two detachable parts, a top or mold part ( 4 a ) and a bottom or vacuum part ( 10 ) in each case adapted such that vacuum can be effectively drawn through holes in the base and/or walls of the predefined shape ( 6 ).

9. The method in accordance with claim 1 , wherein plugs ( 24 ) are inserted into a channel ( 6 ) to prevent room temperature curable silicone composition from flowing or leaking out of the channel ( 6 ) in which it was introduced.

10. The method in accordance with claim 1 , wherein an insert is added into one or more channels ( 6 ):
(i) before introduction of the room temperature curable silicone composition;
(ii) after the room temperature curable silicone composition is introduced either before or during cure; or
(iii) after cure, wherein optionally a primer is utilised to enhance adhesion between the pre-cured elongate shaped silicone elastomeric article and the insert.

11. The method in accordance with claim 1 , wherein the film ( 2 ) has a thickness of from 20 to 70 μm.

12. The method in accordance with claim 1 , wherein the film ( 2 ) is selected from the group consisting of polyethylene (PE), low-density polyethylene (LDPE), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and fluorinated ethylene-propylene (FEP).

13. The method in accordance with claim 1 , wherein the film ( 2 ) used for molding the room temperature curable silicone compositions is also used as packaging of the elongate shaped silicone elastomeric articles.

14. The method in accordance with claim 1 , wherein the film ( 2 ) is treated by application of a coating or a surface treatment.

15. The method in accordance with claim 1 , wherein the room temperature curable silicone composition comprises:
(i) at least one condensation curable silyl terminated polymer having at least one, optionally at least 2, hydrolysable and/or hydroxyl functional groups per molecule;
(ii) a cross-linker selected from the group consisting of
silanes having at least 2, optionally at least 3, hydrolysable groups per molecule; and/or
silyl functional molecules having at least 2 silyl groups, each silyl group containing at least one hydrolysable group; and

(iii) a condensation catalyst selected from the group consisting of titanates and zirconates; wherein;
the molar ratio of hydroxyl groups to hydrolysable groups is between 0.1:1 to 4:1, and
the molar ratio of condensation catalyst (iii) M-OR functions to the hydroxyl groups is from 0.01:1 and 0.6:1, where M is titanium or zirconium and R is an aliphatic hydrocarbon group.

16. The method in accordance with claim 15 , wherein the elongate silicone elastomeric articles formed by the method are self-adherent, and optionally transparent, spacers suitable for use in the manufacture of insulated glazing units.

17. The method in accordance with claim 1 , wherein the elongate silicone elastomeric articles formed by the method have a rectangular cross-section, the rectangular cross-section being 7.5 to 25 mm wide and 5 to 25 mm deep, optionally wherein the elongate silicone elastomeric articles have a length of from 0.5 to 3 meters.

18. An elongate shaped silicone elastomeric article obtainable or obtained by the method in accordance with claim 1 .

19. An insulated glass unit comprising an elongate shaped silicone elastomeric article prepared by the method in accordance with claim 1 , wherein the elongate shaped silicone elastomeric article is a spacer in the insulated glass unit.

20. The method in accordance with claim 1 , further defined as a method of making insulated glazing units and further comprising:
(vii) providing a first pane of glass having a first major surface and a second pane of glass having a first major surface;
(viii) applying an elongate elastomeric article formed in step (vi) onto the first major surface of the first glass panel;
(ix) positioning the first major surface of the second glass panel onto the elongate elastomeric article which thereby serves as a spacer between

Assignees

• Dow Silicones Corp
• Dow Global Technologies Llc

Inventors

• Chambard Gregory
• Dei Santi Davide
• Davidian Thomas
• Gubbels Frederic
• Van Tiggelen Kevin
• Sandkuehler Peter Hermann Roland

Classifications

• B29C39/24

  Feeding the material into the mould · CPC title

• B29C33/68

  Release sheets · CPC title

• E06B3/66328

  of rubber, plastics or similar materials (E06B3/66314, E06B3/66323 and E06B3/66342 take precedence; transparent materials E06B3/66333) · CPC title

• C08K5/56

  Organo-metallic compounds, i.e. organic compounds containing a metal-to-carbon bond · CPC title

• C08G77/38

  Polysiloxanes modified by chemical after-treatment · CPC title