Patent Publication Number: US-2021187916-A1

Title: Silicone elastomer, and manufacturing method thereof

Description:
FIELD OF THE INVENTION 
     The present invention is related to a type of elastomer and manufacturing method thereof; particularly, a type of silicone elastomer applicable to hydrophilic or hydrophobic materials, anti-bacterial materials, conductive materials, as well as the fields of circuit printing, digital printing or film coating. 
     BACKGROUND OF THE INVENTION 
     German patent number DE102011086103A1 titled “Silicone rubber on hotmelt adhesive” discloses a double-layer film comprising: (A) a first layer of silicone rubber; and (B) a hot melt adhesive film. The conditions for said double-layer film are: (i) the adhesive force between (A) and (B) is at least 50N/5 cm; (ii) softening temperature of (B) is between 80-200° C., and (iii) the double-layer film being a double-layer product having elasticity of extension at break of at least 1% according to the standards of ISO 53530. 
     Although the aforementioned prior art discloses an adhesive force being at least 50N/5 cm; however, the adhesive force is still insufficient for actual industrial applications. Furthermore, the double-layer film disintegrates easily due to the characteristic of its physical structure, which is disadvantageous for the following manufacturing processes and applications. This drawback is needed to be remedied. 
     U.S. Pat. No. 5,147,725A discloses “Method for bonding silicone rubber and polyurethane materials and articles manufactured thereby”. The disadvantage of said patent resides in that halogen biproducts may be produced during the manufacturing process and may cause environmental contamination, which is not desirable for industrial applicability. 
     SUMMARY OF THE INVENTION 
     In order to resolve the above-mentioned problems in the prior arts, the present invention provides a silicone elastomer, comprising: a first layer, being polyurethane; a second layer, being silicone rubber; and an intermediate layer, coated on an end surface of the first layer and the second layer and provided between the first layer and the second layer. The intermediate layer undergoes an addition reaction respectively with the first layer and the second layer and undergoes curing, so the intermediate layer is respectively bonded firmly with first layer and the second layer. Another end surface of the first layer is combined with a substrate. The substrate is a textile material or a conductive material. The substrate may be hydrophilic, hydrophobic, anti-bacterial, or conductive and may be suitable for circuit printing, digital printing or film coating. 
     Preferably, the intermediate layer is cured via thermal curing or photo-curing. 
     Preferably, an adhesive force between the intermediate layer and the first layer, and an adhesive force between the intermediate layer and the second layer is respectively from 50N/5 cm to 300N/5 cm. 
     A manufacturing method for the silicone elastomer comprises the steps of: coating an intermediate layer on a first layer, the intermediate layer and the first layer being placed in a curing apparatus to cure the intermediate layer; the intermediate layer and the first layer undergoing an addition reaction to bond the first layer with the intermediate layer; stacking a second layer on the intermediate layer, curing the second layer in the curing apparatus; and the intermediate layer and the second layer undergoing an addition reaction to bond the second layer with the intermediate layer. 
     Preferably, the curing apparatus is a thermal curing apparatus or a photo-curing apparatus. 
     Preferably, the thermal curing apparatus is provided with a predetermined temperature, the predetermined temperature is from 80° C. to 200° C. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a structure schematic of the present invention. 
         FIG. 2  is a schematic of the present invention when in use. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in  FIG. 1  and  FIG. 2 , a silicone elastomer  1  in accordance with the present invention comprises a first layer  10 ; a second layer  20 ; and an intermediate layer  30 . 
     The first layer  10  is polyurethane, polyurethane (PU) having a functional group comprising: isocyanate group, or polyalcohol (hydroxyl Group). 
     The second layer  20  is a silicone rubber having a functional group comprising: SiH or —CH═CH 2 . An intermediate layer  30  is provided between the second layer  20  and the first layer  10 ; the intermediate layer  30  is self-crosslinking with: silane, acrylic acid, methyl acrylate, or acrylic acid ethyl ester. 
     The intermediate layer  30  is cured via thermal curing or photo-curing. The intermediate layer  30  respectively undergoes an addition reaction with the first layer  10  and the second layer  20 , so the intermediate layer  30  respectively bonds with the first layer  10  and the second layer  20  firmly. The adhesive force between the intermediate layer  30  and the first layer  10 , and the adhesive force between the intermediate layer  30  and the second layer  20  are respectively from 50 N/5 cm to 300 N/5 cm. 
     The double bond of C═N in the isocyanate functional group in the first layer  10  is highly active and can undergo autopolymerization to form a dimer or a trimer. The double bond can also undergo addition reaction with functional group containing active hydrogen such as water, alcohol, phenol, acid, or amine. The order activities of the chemicals in the functional group are as the following (Ar represents aryl functional group): 
       RNH 2 &gt;R 2 NH&gt;ArNH 2 &gt;RCH 2 OH&gt;H 2 O&gt;R 2 CHOH&gt;R 3 COH&gt;ArOH&gt;RCOOH&gt;RNCO 
     The first layer  10  contains isocyanate group; the intermediate layer  30  thus can crosslink with the first layer  10  via the aforementioned functional group. 
     One of the mechanisms for cross-linking the intermediate layer  30  with the second layer  20  is as follows: an addition reaction is carried between the SiH functional group and the double bond; the reaction condition and speed is controlled by the usage of platinum catalyst; therefore, the second layer  20  can cross-link with the intermediate layer  30  via SiH functional group or double bond functional group. 
     According to the silicone elastomer  1  of the present invention, when used, an end surface of the first layer  10  is attached to a substrate  40  via thermal lamination (but not limited to this method). The substrate  40  is, but not limited to, textile material or conductive material. And the substrate may be hydrophilic or hydrophobic materials, anti-bacterial materials, or conductive materials, and may be suitable for circuit printing, digital printing, or film coating. 
     A method for manufacturing silicone elastomer comprises the following steps: coating an intermediate layer  30  on a first layer  10 , the intermediate layer  30  and the first layer  10  being placed in a curing apparatus to cure the intermediate layer  30 , meanwhile, the intermediate layer  30  and the first layer  10  undergoing an addition reaction in the curing apparatus to bond the first layer  10  with the intermediate layer  30 ; taking out the intermediate layer  30  and the first layer  10  and stacking a second layer  20  on the intermediate layer  30 ; curing the second layer  20  in the curing apparatus; and the intermediate layer  30  and the second layer  20  undergoing an addition reaction to bond the second layer  20  with the intermediate layer  30 . 
     After completing the addition reaction between the intermediate layer  30  and the first layer  10  in the curing apparatus, another side of the intermediate layer  30  is still adhesive and is able to bond with the second layer  20 . The intermediate layer  30  and the second layer  20  are cured again in the curing apparatus. 
     The curing apparatus is a thermal curing apparatus or a photo-curing apparatus. When the thermal curing apparatus is used, thermal curing apparatus is provided with a predetermined temperature, the thermal curing apparatus is heated with predetermined temperature of 80° C. to 200° C. 
     More specifically, the present invention can be obtained from the following methods. 
     In one embodiment, the present invention utilizes siloxane functional group condensation polymerization to achieve self-crosslinking reaction of the intermediate layer  30 . 1% and 25% of trimethoxy(vinyl) silane (CAS:2768-02-7) and (3-Glycidyloxypropyl) triMethoxysilane (CAS:2530-83-8) are respectively dissolved in an organic solution. Appropriate and small amount of cross-linking catalysis is added to complete preparing the intermediate layer  30  original solution. The intermediate layer  30  original solution is diluted with appropriate ratio and coated on the first layer  10 . The first layer  10  is baked in the curing apparatus with preheated temperature of 90° C. for 5 minutes to complete the addition reaction of the intermediate layer  30  and the first layer  10 ; and to evaporate the solvent in the intermediate layer  30 . The second layer  20  is stacked on the intermediate layer  30 ; the second layer  20  and the intermediate layer  30  is baked in the curing apparatus with preheated temperature of 110° C. for 3 minutes to complete the addition reaction of the intermediate layer  30  and the second layer  20 , and to cure the second layer  20 . The adhesive force between the intermediate layer  30  and the first layer  10 , and the adhesive force between the intermediate layer  30  and the second layer  20  are respectively from 55N/5 cm to 65N/5 cm. 
     In a preferred embodiment, the present invention utilizes siloxane functional group condensation polymerization to achieve self-crosslinking reaction of the intermediate layer  30 . 3% and 25% of trimethoxy(vinyl) silane (CAS:2768-02-7) and (3-Glycidyloxypropyl) triMethoxysilane (CAS:2530-83-8) are respectively dissolved in an organic solution. Appropriate and small amount of cross-linking catalysis is added to complete preparing the intermediate layer  30  original solution. The intermediate layer original solution is diluted with appropriate ratio and coated on the first layer  10 . The first layer  10  is baked in the curing apparatus with preheated temperature of 130° C. for 5 minutes to complete the addition reaction of the intermediate layer  30  and the first layer  10 , and to evaporate the solvent in the intermediate layer  30 . The second layer  20  is stacked on the intermediate layer  30 ; the second layer  20  and the intermediate layer  30  is baked in the curing apparatus with preheated temperature of 110° C. for 3 minutes to complete the addition reaction of the intermediate layer  30  and the second layer  20 , and to cure the second layer  20 . The adhesive force between the intermediate layer  30  and the first layer  10 , and the adhesive force between the intermediate layer  30  and the second layer  20  are respectively from 90N/5 cm to 110N/5 cm. 
     Although particular embodiments of the present invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the present invention. Accordingly, the present invention is not to be limited except as by the appended claims.