INTEGRAL LAYERED ARTICLES AND THEIR METHOD OF MANUFACTURE

Abstract

An integral modified polyolefin resin/silicone elastomer layered article is provided together with a method for its production. The integral polyolefin-based resin/silicone elastomeric material article comprises a shaped layer of a polyolefin-based copolymer or grafted polyolefin. It contains silyl trialkoxy groups, carboxylic acid groups and/or —OH groups. A silicone elastomeric material layer is subsequent to being cured from a hydrosilylation curable silicone elastomer composition comprising one or more adhesion promoters.

Claims

1. An integral polyolefin-based resin/silicone elastomeric material article comprising: a shaped layer of a polyolefin-based copolymer or grafted polyolefin, which polyolefin-based copolymer or grafted polyolefin contains silyl trialkoxy groups, carboxylic acid groups and/or —OH groups; and a silicone elastomeric material layer chemically bound to the shaped layer, which silicone elastomeric material layer is cured from a hydrosilylation curable silicone elastomer composition comprising at least one adhesion promoter.

2. An integral polyolefin-based resin/silicone elastomeric material article obtainable or obtained by the steps of: preforming a polyolefin-based copolymer or grafted polyolefin into a shaped layer, which polyolefin-based copolymer or grafted polyolefin contains silyl trialkoxy groups, carboxylic acid groups and/or —OH groups; contacting the shaped layer with a hydrosilylation curable silicone elastomer composition; and curing the hydrosilylation curable silicone elastomer composition causing the composition to chemically bind with the shaped layer at a temperature below the softening point of the polyolefin-based copolymer or grafted polyolefin to form the integral polyolefin-based resin/silicone elastomeric material article.

3. The integral polyolefin-based resin/silicone elastomeric material article in accordance with claim 1, wherein the polyolefin is selected from the group consisting of polyethylene, polypropylene, polyisobutylene, polybutylene, and combinations thereof.

4. The integral polyolefin-based resin/silicone elastomeric material article in accordance with claim 1, wherein the polyolefin-based copolymer is formed by copolymerization of an olefin monomer and an alkylene vinyl alcohol monomer or oligomer.

5. The integral polyolefin-based resin/silicone elastomeric material article in accordance with claim 1, wherein the grafted polyolefin containing silyl trialkoxy groups, carboxylic acid groups and/or —OH groups is a polyolefin grafted with a silicon-containing compound containing one or more of the aforementioned groups.

6. The integral polyolefin-based resin/silicone elastomeric material article in accordance with claim 1, wherein the hydrosilylation curable silicone elastomer composition comprises: (i) one or more polydiorganosiloxane polymer(s) having a viscosity of from 1000 to 500,000 mPa.Math.s at 25° C. and containing at least two alkenyl groups and/or alkynyl groups per molecule; (ii) a reinforcing filler, optionally treated with at least one filler treating agent; (iii) an organohydrogenpolysiloxane having at least two, optionally at least three, silicon-bonded hydrogen atoms per molecule; (iv) a hydrosilylation catalyst; and (v) one or more adhesion promoter(s).

7. The integral polyolefin-based resin/silicone elastomeric material article in accordance with claim 6, wherein the hydrosilylation curable silicone elastomer composition further comprises one or more cure inhibitor(s).

8. The integral polyolefin-based resin/silicone elastomeric material article in accordance with claim 1, wherein the adhesion promoter is selected from a mixture and/or reaction product of: A′) nonanediol diacrylate, 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane, trimethylsiloxy-terminated methylhydrogen siloxane, glycidoxypropyltrimethoxysilane, hydroxy-terminated dimethyl-methylvinyl siloxane, and zirconium acetylacetate; B′) glycidoxypropyltrimethoxysilane, hydroxy-terminated dimethyl-methylvinyl siloxane, and zirconium acetylacetate; or C′) trimethylsiloxy-terminated methylhydrogen siloxane, glycidoxypropyltrimethoxysilane, hydroxy-terminated dimethyl-methylvinyl siloxane, and zirconium acetylacetate.

9. The integral polyolefin-based resin/silicone elastomeric material article in accordance with claim 1, adapted for automotive applications, medical applications, consumer and industrial applications, electronic applications and/or 3-D printing applications.

10. A method for preparing the integral polyolefin-based resin/silicone elastomeric material article in accordance with claim 1, the method comprising the steps of: preforming a polyolefin-based copolymer or grafted polyolefin shaped layer, which polyolefin-based copolymer or grafted polyolefin contains silyl trialkoxy groups, carboxylic acid groups and/or —OH groups: contacting the polyolefin-based copolymer or grafted polyolefin shaped layer with a hydrosilylation curable silicone elastomer composition; and curing the hydrosilylation curable silicone elastomer composition causing the composition to chemically bind with the polyolefin-based copolymer or grafted polyolefin shaped layer at a temperature below the softening point of the polyolefin-based copolymer or grafted polyolefin to form the integral polyolefin-based resin/silicone elastomeric material article.

11. The method in accordance with claim 10, wherein the polyolefin-based copolymer or grafted polyolefin shaped layer is either partially or completely covered with the hydrosilylation curable silicone elastomer composition in a sheet form or by coating/dipping and heating the coated preformed article to a suitable temperature to cure the silicone elastomer composition and thereafter form an integral grafted polyolefin or polyolefin co-polymer/silicone elastomer layered article.

12. The method in accordance with claim 10, wherein the hydrosilylation curable silicone elastomer composition is processed and/or applied on to the polyolefin-based copolymer or grafted polyolefin shaped layer by injection moulding, encapsulation moulding, press moulding, dispenser moulding, extrusion moulding, transfer moulding, press vulcanization, centrifugal casting, calendaring, bead application or blow moulding.

13. The method in accordance with claim 10, wherein the polyolefin-based copolymer or grafted polyolefin shaped layer has the hydrosilylation curable silicone elastomer composition applied to it and then the combination is heated and compressed for a pre-determined time and temperature.

14. The method in accordance with claim 10, wherein the polyolefin-based copolymer or grafted polyolefin injected into a mold cavity to form a desired shape and subsequently injecting the hydrosilylation curable silicone elastomer composition into the mold cavity and around the shape and curing to provide an integral layered article.

15. (canceled)

16. The integral polyolefin-based resin/silicone elastomeric material article in accordance with claim 1, in or adapted for housings with a silicone seal or gasket, plugs and connectors, components of sensors, membranes, diaphragms, climate venting components, masks, goggles, tubing and valves, catheters, ostomy appliances, respiratory appliances, feeding appliances, contact lenses, hearing aids, orthotics, prosthesis, shower heads, bakery ware, spatulas, home appliances, footwear, sports and leisure articles, diving masks, face masks, furniture, pacifiers, feeding accessories, seals and surfaces of white goods and other kitchen articles, mobile phone cover seals, mobile phone accessories, cell phone cases, precision electronic equipment, electrical switches and switch covers, watches and wristbands and/or wearable electronic devices.

Description

EXAMPLES

[0118] In the following examples several grafted polyolefins, polyolefin copolymers and ungrafted polyolefins and mixtures thereof were utilised for the examples and counter examples. It will be seen that these were a mixture of commercial/modified commercial and laboratory prepared materials.

TABLE-US-00001 TABLE 1 Copolymers and Grafted Polymers used in the Examples Si-Link ™ an ethylene vinyltrimethoxy silane copolymer DFDA-5451 NT polyethylene copolymer (Dow Chemical Company) PRIMACOR ™ a heat sealable ethylene acrylic acid (EAA) 1410 copolymer (Dow Chemical Company) Soarnol ™ an ethylene vinylalcohol copolymer having a 29 DT2904RB mol % ethylene content (Noltex, LLC) DOW ™ LDPE a low-density polyethylene (Dow Chemical 5011 Company) Developmental a developmental ethylene/a-olefin copolymer made ethylene/a-olefin using a transition metal catalyst in a solution copolymer 1 polymerization process having a nominal density (DC1) of 0.880 g/cm.sup.3 and a nominal melt index (I.sub.2 @ 190° C.) of 18 g/10 min. Developmental a developmental ethylene/α-olefin copolymer made ethylene/a-olefin using a transition metal catalyst in a solution copolymer 2 polymerization process having a nominal density (DC2) of 0.900 g/cm.sup.3 and a nominal melt index (I.sub.2 @ 190° C.) of 30 g/10 min. DC1/DC2 blend a 40/60 wt. %/wt. % blend of DC1 and DC2. Grafted DC1/ a 40/60 wt. %/wt. % blend of DC1 and DC2 to DC2 blend which trimethoxysilane groups have been grafted DC3 DC 1 with 1.26 wt. % of vinyl trimethoxysilane (VTMS) grafted thereto DC4 DC 1 with 2.27 wt. % of VTMS grafted thereto DC5 DC 1 with 3.12 wt. % of VTMS grafted thereto DC6 DC 1 with 3.87 wt. % of VTMS grafted thereto

[0119] DC 3-6 were prepared by reactive extrusion using a Coperion ZSK-26 twin-screw extruder having 26 mm diameter twin-screws with a length to diameter ratio of the extruder is 44:1; a loss-in-weight feeder (K-Tron model KCLQX3) used to feed the DC 1 copolymer, an ISCO pump (model 1000D) for injecting a solution of VTMS and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane into the extruder. A devolatilizing system was utilised for removing unreacted VTMS and any formed by-products. A Gala underwater system utilizing a two-hole die with 3 mm diameter was subsequently used to pelletize the produced silane-grafted high-density polyethylene.

[0120] 1) Method to prepare the layered article: [0121] Modification of the polyolefin resin in the melt using for example twin-screw extruders or Haake mixers. Production of ethylene-based copolymers via a high pressure process in the gas-phase and in the presence of a thermal radical initiator. [0122] Injection molding of the modified polyolefin to produce a molded plaque

[0123] Preformed parts of the polyolefin-based materials as described in Table 1 and prepared as described above were injection molded using an injection molding machine from Toyo Machinery & Metal Co Ltd of Japan (“Toyo”). The Toyo injection molding machine utilised is a 110 ton press equipped with a 32 mm diameter single-screw plasticator which has an L/D (length to diameter) ratio of 20:1. The screw utilised in the press was an Eagle mixing screw supplied by Westland Corp. The feed and transition sections of the Eagle mixing screw were of standard design e.g., like a general purpose screw. The metering section of the Eagle mixing screw possessed a mixing section comprised of two spiral in-flow and two spiral out-flow channels. This mixing flight contained within the mixing section of the screw possessed an undercut that provided a degree of dispersive mixing. This mixing flight also contained bypass channels that provided a degree of distributive mixing. Plaques with a dimension of 101.6×152.4 mm were prepared for each polyolefin-based material sample by injection molding using the above with the conditions indicated in Tables 2a-2d below which were set on the machine.

TABLE-US-00002 TABLE 2a Injection molding conditions for the polyolefin-based materials used Barrel temp. (zones 1 to 4, nozzle Mold Hold Hold Cooling straight temp. time pressure time Material profile (° C.) (° C.) (sec) (MPa) (sec) Si-Link ™ DFDA- 215 43 15 44.81 18 5451 NT Grafted DC1/DC2 215 43 15 44.81 18 blend DC1/DC2 blend 215 43 15 44.81 18 PRIMACOR ™ 1410.sup.a 215 43 15 44.81 18

TABLE-US-00003 TABLE 2b Injection molding conditions for the polyolefin-based materials used Barrel temp. (zones 1 to 4, nozzle Mold Hold Hold Cooling straight temp. time pressure time Material profile (° C.) (° C.) (sec) (MPa) (sec) Blend of Soarnol ™ 215 43 15 44.81 18 DT2904RB/DOW ™ LDPE 5011 (20/80 wt. %/wt. %) DOW ™ LDPE 5011 215 43 15 44.81 18 Soarnol ™ DT2904RB.sup.b 215 43 15 44.81 18 DC3 215 43 15 44.81 18 DC4 215 43 15 44.81 18 DC5 215 43 15 44.81 18 DC6 215 43 15 44.81 18
Sample was dried at 80° C. for 24 hours (h) apart from in the case of when using Soarnol™ DT2904RB which was dried at 110° C. for 24 h for both the blend and alone.

TABLE-US-00004 TABLE 2c Injection molding conditions for the polyolefin-based materials used Back Screw Injection Shot pressure rotation speed size Transfer Material (MPa) (rpm) (cm.sup.3/sec) (cm.sup.3) (cm.sup.3) Si-Link ™ DFDA- 4.48 85 36 65 12 5451 NT Grafted DC1/DC2 blend 4.48 85 36 65 12 DC1/DC2 blend 4.48 85 36 65 12 PRIMACOR ™ 1410.sup.a 4.48 85 36 65 12

TABLE-US-00005 TABLE 2d Injection molding conditions for the polyolefin-based materials used Back Screw Injection Shot pressure rotation speed size Transfer Material (MPa) (rpm) (cm.sup.3/sec) (cm.sup.3) (cm.sup.3) Blend of Soarnol ™ 4.48 85 36 65 12 DT2904RB/DOW ™ LDPE 5011 (20/80 wt. %/wt. %) DOW ™ LDPE 5011 4.48 85 36 65 12 Soarnol ™ DT2904RB 4.48 85 36 65 12 DC3 4.48 85 36 65 12 DC4 4.48 85 36 65 12 DC5 4.48 85 36 65 12 DC6 4.48 85 36 65 12

[0124] A single liquid silicone rubber formulation was used throughout the examples. It was prepared by mixing two masterbatches and several components together. The LSR composition was stored in two parts prior to use to prevent premature cure. In this instance this was particularly important given the example compositions do not contain any hydrosilylation cure inhibitors. The vinyl content was determined by titration and silicone bonded hydrogen (Si—H) values provided were determined by quantitative infrared analysis in accordance with ASTM E168. Viscosity values of siloxane polymers (e.g., component (i)) were measured using a Brookfield® rotational viscometer using Spindle (LV-4) for viscosities in the range between 1,000-2,000,000 mPa.Math.s and adapting the speed according to the polymer viscosity and all viscosity measurements were taken at 25° C. unless otherwise indicated.” The compositions of the two masterbatches used are provided in Table 3 below:

TABLE-US-00006 TABLE 3 LSR Masterbatches utilised MB 1 MB 2 (wt. %) (wt. %) Dimethylvinyl terminated dimethyl Siloxane 69.19 63.14 having a viscosity of 55,000 mPa .Math. s and a vinyl content of 0.09 wt. % Hexamethyldisilazane 4.72 5.55 CAB-O-SIL ® MS-75 Fumed silica 25.15 29.54 tetramethyldivinyldisilazane 0.0 0.3 HO[Si(Me).sub.2—O].sub.2[Si(methylvinyl)-O]—H 0.0 0.37 Water 0.94 1.1 Total 100 100 CAB-O-SIL ® MS-75 Fumed silica is commercially available from the Cabot Corporation

[0125] Table 4 below describes the Part A and Part B compositions of the 2-part LSR composition used in all examples and comparative examples described below.

TABLE-US-00007 TABLE 4 Part A and Part B compositions used in the following Examples Part A Part B (wt. %) (wt. %) MB 1 17.68 17.27 MB 2 70.72 69.08 Dimethylvinyl terminated dimethyl Siloxane 6.17 4.60 having a viscosity of 55,000 mPa .Math. s and a vinyl content of 0.09 wt. % Dimethylvinyl terminated dimethyl methylvinyl 4.25 5.48 siloxane copolymer having a dp of about 145 and a vinyl content of 1.09 wt. % Platinum catalyst 0.58 MQ silicone resin with Si—H groups on the M unit 2.98 having an Si—H content of 9600 ppm HO[Si(Me).sub.2—O[.sub.2[Si(methylvinyl)-O]—H 0.60 0.60 Total wt. % 100 100

[0126] The MQ resin utilised as a cross-linker was done so with a view to help reduce the cure temperature required for the liquid silicone rubber composition given the need to cure at a temperature below the melt temperature of the polyolefin-based material on to which it is being cured. No inhibitor was included in the Part B composition.

[0127] In the Examples which follow 3 alternative adhesion promoter packages were used in the examples and counter examples the content of these were as follows:

Adhesion Promoter Package A:

[0128] nonanediol diacrylate (1 wt. %) [0129] 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane (1 wt. %) [0130] trimethylsiloxy-terminated methylhydrogen siloxane (2 wt. %) [0131] glycidoxypropyltrimethoxysilane (0.5 wt. %) [0132] hydroxy-terminated dimethyl-methylvinyl siloxane (0.5 wt. %) [0133] and zirconium acetylacetate (1 wt. %).

Adhesion Promoter Package B

[0134] glycidoxypropyltrimethoxysilane (0.5 wt. %) [0135] hydroxy-terminated dimethyl-methylvinyl siloxane (0.5 wt. %) [0136] and zirconium acetylacetate (1 wt. %).

Adhesion Promoter Package C

[0137] trimethylsiloxy-terminated methylhydrogen siloxane (2 wt. %) [0138] glycidoxypropyltrimethoxysilane (0.5 wt. %) [0139] hydroxy-terminated dimethyl-methylvinyl siloxane (0.5 wt. %) [0140] zirconium acetylacetate (1 wt. %).

[0141] The compositions were made by mixing Part A and Part B compositions in a 1:1 ratio. The adhesion promoter packages were added after the mixing of Part A and Part B and the wt. % values above are relative to the wt. % of the total composition of Part A and Part B, hence 1 wt. % of nonanediol diacrylate means 1 wt. % of the total of Part A:Part B after mixing. The amount of each other ingredient in the adhesion promoter package used is calculated in the same way before introduction. The adhesion promoter package may be pre-mixed before addition into the Part A+Part B composition or each ingredient of the adhesion promoter package may be introduced into the Part A/Part B composition as is preferred. Unless otherwise indicated the adhesion promoter package utilised in the Examples was adhesion promoter package A.

[0142] For the present examples the liquid silicone rubber (LSR) composition was prepared as follows: [0143] 1) Each of the components of liquid silicone rubber Part A were introduced into a speedmixer cup. The resulting composition was then mixed for 3 times at 2200 rpm for 60 s with hand mixing in between.

[0144] Each of the components of liquid silicone rubber Part B were introduced into a speedmixer cup. The resulting composition was then mixed for 3 times at 2200 rpm for 60 s with hand mixing in between 3) 1:1 mix of Part A and Part B (as prepared respectively in 1 and 2 above) were mixed together and each ingredient of the selected adhesion promoter package was introduced individually into the Part A/Part B mixture individually and then the whole composition was mixed 3 times at 2200 rpm for 60 s with hand mixing in between.

[0145] In order to show that the LSR composition depicted in Table 4 provides the physical properties expected for a typical LSR several standard physical properties were determined and are shown in Tables 5a and 5b below for the LSR in Table 4 and also the LSR of Table 4 with adhesion package A introduced. Two samples were tested for each property and the values provided are the average of the two. Cure time values and scorch rate values were measured using a Monsanto MDR 2000 moving die rheometer. After mixing as described above samples were cured at the respective mold temperatures and times indicated in Table 7 below prior to testing the physical properties indicated.

TABLE-US-00008 TABLE 5a LSR physical properties Durometer Tensile Elongation 100% Modulus (shore A) strength (MPa) (%) (MPa) (ASTM ASTM D412 ASTM D412 ASTM D412 D2240) (Die C) (Die C) Die C) LSR 48.0 10.4 482.00 1.6 LSR + 45.0 7.0 659.00 1.2 adhesion promoter package A

TABLE-US-00009 TABLE 5b LSR physical properties Tear Strength (Die B) Cure Time Scorch time (ASTM D624) (kN/m) (t 90) (s) TS 2 (s) LSR 29.4 370.53 85.20 LSR + 32.8 2128.05 661.20 adhesion promoter package A

Adhesion Examples

[0146] For all the following examples identical samples of the LSR compositions depicted in Table 4 with the appropriate adhesion promoter package added (where required) were used for application to a variety of modified polyolefin plaque. Tables 6a and 6b list the modified polyolefin plaques utilised as well as the adhesion promoter package added into the LSR.

TABLE-US-00010 TABLE 6a The modified polyolefin plaques and adhesion promoter package used in comparatives 1 to 5 Example Polyolefin Resin Adhesion Promoter Comp 1 DC1/DC2 blend A Comp 2 DOW ™ LDPE 5011 A Comp. 3 Si-Link ™ DFDA-5451 NT ½ amount A Comp. 4 Si-Link ™ DFDA-5451 NT B Comp. 5 Si-Link ™ DFDA-5451 NT C

TABLE-US-00011 TABLE 6b The modified polyolefin plaques and adhesion promoter package used Examples 1-10 Example Polyolefin Resin Adhesion Promoter Ex. 1 Si-Link ™ DFDA-5451 NT A Ex. 2 Si-Link ™ DFDA-5451 NT A Ex. 3 Grafted DC1/DC2 blend A Ex. 4 PRIMACOR ™ 1410a A Ex. 5 Blend of Soarnol ™ DT2904RB/DOW ™ A LDPE 5011 (20/80 wt. %/wt. %) Ex.6 Soarnol ™ DT2904RB A Ex. 7 DC3 A Ex. 8 DC4 A Ex. 9 DC5 A Ex. 10 DC6 A

[0147] Modified polyolefin plaques were prepared having the size 101.6×154.4×3.17 mm. The modified polyolefin plastic plaque was cut into strips of 25.4×101.6×3.17 mm dimension. Each strip was then placed into a 25.4×152.4×6.35 mm channel within a 254×254 mm aluminum chase that is placed upon a 254×254 mm aluminum support plate. Part of the strip was then covered with a polytetrafluoroethylene coated sheet, leaving a 25.4×72.6 mm area of modified polyolefin plaques uncovered. The liquid silicone rubber composition containing adhesion promoter package A (in this group of tests) was applied on top of the strip, filling the channel. A 25.4×152.4 mm wire mesh screen was then placed on top of the liquid silicone rubber composition layer and a 254×254 mm polytetrafluorethylene coated sheet was placed on the mesh screen and a 254×254 mm aluminum backer plate was placed thereover.

[0148] The chase and backer plates were then placed into a Greenard Hydrolair hot press (Greenerd Press & Machine Co. of New Hampshire USA) already heated to the desired mold temperature (as indicated in Table 7 below) and then pressed at a molding pressure of 11.37 MPa for a desired mold time (as indicated in Table 7 below). After the desired period of time, the chase was removed from the hot press, cooled rapidly in a Wabash Genesis Press type cold press (Wabash MPI, Wabash Ind., USA). Once the chase had cooled to the touch, it was removed from the cold press. The backer plates were removed, and the polytetrafluoroethylene coated sheets were peeled off. The combined polyolefin/silicone layered articles were removed from the chase. Each article was then tested for adhesion by a 180° peel test on a TechPro tensiTECH Load Frame. The liquid silicone rubber layer was peeled from the plastic at 180° at a rate of 0.05 m/min and the adhesion strength is measured as an average over the entire test.

TABLE-US-00012 TABLE 7 Mold Temp. Mold time (° C.) (min) Peel strength (N/mm) Comp. 1 90 180 0.0 Comp. 2 90 180 0.3 Comp. 3 90 60 0.5 Comp. 4 90 60 0.3 Comp. 5 90 90 0.5 Ex. 1A 90 180 4.7 @ 0 h 6.0 @ 24 h 4.4@ 168 h Ex. 1B 90 120 5.7 Ex. 2 90 40 4.3 Ex. 3 90 180 4.2 Ex. 4 90 180 3.3 Ex. 5 90 180 0.8 Ex. 6 120 20 5.8 Ex. 7 65 960 2.9 Ex. 8 65 960 3.5 Ex. 9 65 960 3.9 Ex. 10 65 960 4.7

[0149] It will be appreciated that all the comparative examples had peel strength results of 0.5 N/mm or less and that all the examples had values of at least 0.8 N/mm and in most cases the peel strength was greater than 2.9 N/mm which is significantly improved over the comparative examples. Regarding the 0.8 value measured in example 5 it is to be noted that Soarnol™ DT2904RB is an ethylene vinylalcohol copolymer and as such when analysed in pure form works very well with a peel strength of 5.8 (Example 6). However, when diluted in low density polyethylene in the example 5 blend the available —OH are much diluted (20% EVOH/80% LDPE) resulting in the comparatively lower peel strength value of example 5.