Patent Application
20220381376
This application is a national application filed under 35 U.S.C. 111(a) which claims priority to European patent application number 21176779.3, filed May 31, 2021, the entire contents of which is incorporated herein by reference.
The invention concerns in general to methods for making a silicone hoses and hoses made thereby, where the hose includes at least a reinforced silicone rubber layer and a polyolefin heat shrinkable material covering the reinforced silicone rubber layer and which is applied prior to curing the hose.
The state of the art describes curable silicone compositions which are used in a variety of reinforced hose applications which ranges from the automotive industry to medical devices. Such compositions are used to form a hose in so called in the wrapped silicon hose manufacturing. In a wrapped silicon hose manufacturing process, a taping subprocess is used for ensuring adhesion between silicone layers during a later vulcanization curing process. To generate adhesion between the silicone layers, layers of binder tape (i.e. cellulose tape) are applied on the hose surface to consolidate the silicone layers preform. This process step is required for all preforms made without set-cured materials. After curing, to extract the hose, the plies of cellulose must be de-taped, or otherwise removed. The used tape is then discarded.
Also, the taping process is performed by using “orbital winders”, which is time and work consuming. Furthermore, only highly trained and skilled operators are typically required to complete such a complex task. In addition to orbital winders, other requisite specialized equipment/personal includes tape wetting machines/operators, operators for de-taping and extraction, as well as chucks for holding the mandrels used in the wrapping process. Additionally, once the hoses have completed the curing cycle, they must be cooled and soaked in a tank of water. The water bath is required to rehydrate the cellulose acetate binder tape so that it easily releases from the hose surface, as well as for ease to cut.
The goal of the invention is to use a silicon hose manufacturing process which avoids the use of a taping subprocess, and other related subprocesses, while still providing a cured reinforced silicon hose. Such goal is achieved by using industrial grade shrink tubes/sleeves, such as polyolefin shrink sleeves, (collectively “shrink sleeves”) for tightening the wrapped reinforced silicon layers together, in place of using layers of adhesive tape. Such a manufacturing method will be referred to herein as a “shrink tension method” or “ST method”.
Some advantages of the shrink tension method process include less time consumption in comparison to a traditional the taping process, as well as lower manpower requirements. The shrink tension method also provides easier recyclability and significantly less waste. Less specialized equipment is required, as well as a reduction in the possibility of human error. The shrink tension method eliminates the requirement of hose forming with cellulose tape and de-taping. Lastly, the ST method is feasible for shaped hoses and linear hoses.
A wrapped silicon hose manufacturing process using a shrink tension method according to this inventive disclosure includes first cutting a calendared silicone rubber/reinforcement material to length, thus creating blank reinforced silicone sheets, hereinafter also referred to as “blanks”. Then preforming is achieved by wrapping up a plurality of blanks on a mandrel with a specific diameter and shape, thus creating a preform. A shrink sleeve is pulled over the preform and is preheated in order to enable a tight/snug fit of the shrink sleeve over the preform. In some aspects, the pulling on the mandrel of the preform and the shrink sleeve may be done while these materials are still warm or hot and flexible. Also, the shrink sleeve may be used to control the shape of the uncured hose, and provides necessary pressure for vulcanization.
In some cases, after vulcanization and extracting the hose from the forming mandrel, it is not necessarily required to remove the shrink sleeve, as the shrink sleeve and outermost reinforced silicon layer are bonded together, thus adding mechanical and abrasive protection. The vulcanized semi-finished product may then be cut to the right length/shape, printed with the necessary labels, assembled and then checked.
Any conventionally known silicone rubbers are usable as the silicone rubber for the sheets. Some non-limiting examples of silicone rubbers useful to prepare the reinforced silicone sheets, include silicone rubbers of high temperature vulcanizable type (HTV), silicone rubbers of room temperature vulcanizable type (RTV) and liquid silicone rubbers of low temperature vulcanizable type (LTV). The silicone rubber composition may have a Mooney viscosity of 60 to 120, or even 60 to 100, at 50° C. in the unvulcanized state after being kneaded for the production of the sheets.
A reinforcement layer, such as a textile material, is embedded between a first silicone rubber layer and a second silicone rubber layer in the sheet. This may be formed by any suitable process, such as a calendaring process for example. The reinforcement layer is composed of a knit, in particular based on a textile material, in particular in turn composed of yarns. The materials relevant here can be a polyamide (PA), a polyimide (PI), an aramid, a para-aramid, a meta-aramid, a polyvinyl acetal (PVA), polyvinyl alcohol (PVAL), cotton (CO), modal (CMD), rayon (CV), a polyetheretherketone (PEEK), a polyester, in particular polyethylene therephthalate (PET) or polyethylene 2,6-naphthalate (PEN), a polysulfone (PSU), a polyoxadiazole (POD), polybenzoxazole (PBO), polyphenylene, a polyphenylene derivative, steel, or even brass. Hybrid designs, for example in the form of a mixed yarn can also be used.
The hose may further include an inner layer in some cases. The inner layer may be formed from unblended ethylene-acrylate rubber (AEM), an AEM blend, unblended acrylate rubber (ACM), an ACM blend, fluororubber, or silicone rubber. The inner layer may be the innermost layer of the hose, and a lumen of the hose is defined therein.
The silicone rubber hose produced according to the disclosure can have inner diameter of from about 30 mm to about 100 mm and a thickness of about 2 mm to about 12 mm. In some cases, the silicone rubber hose has an inner diameter of about 30 mm to about 70 mm and a thickness of about 3 mm to about 10 mm. Hoses according to the disclosure include, but are not limited to, air induction hoses, charge-air hoses, coolant hoses, and the like.
The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings, where
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After building the desired number of plies 16 on mandrel 14, a shrink sleeve 20 is then pulled in direction L to cover the outer surface of plies 16. The hose 22 is then cured, typically in a vulcanization oven.
With reference to
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| Number | Date | Country | Kind |
|---|---|---|---|
| 21176779.3 | May 2021 | EP | regional |
