Activating surfaces for subsequent bonding

Abstract

A method of activating a surface of a plastics substrate formed from: (a) polyaryletherketone such as polyether ether ketone (PEEK) polyether ketone ketone (PEKK), polyether ketone (PEK); polyether ether ketone ketone (PEEKK); or polyether ketone ether ketone ketone (PEKEKK); (b) a polymer containing a phenyl group directly attached to a carbonyl group, for example polybutadiene terephthalate (PBT) optionally wherein the carbonyl group is part of an amide group, such as polyarylamide (PARA); (c) polyphenylene sulfide (PPS); or (d) polyetherimide (PEI); for subsequent bonding, the method comprising the step of exposing the surface to actinic radiation wherein the actinic radiation: includes radiation with wavelength in the range from about 10 nm to about 1000 nm; the energy of the actinic radiation to which the surface is exposed is in the range from about 0.5 J/cm.sup.2 to about 300 J/cm.sup.2. Hard to bond substrates are then more easily subsequently bonded for example using acrylic, epoxy or anaerobic adhesive.

Claims

1. A method of activating a surface of a plastics substrate formed from: (a) a polyaryletherketone; (b) a polymer containing a phenyl group directly attached to a carbonyl group, optionally wherein the carbonyl group is part of an amide group; (c) polyphenylene sulfide (PPS); or (d) polyetherimide (PEI); for subsequent bonding, the method comprising a step of exposing the surface to actinic radiation wherein the actinic radiation: includes radiation with wavelength in a range from about 10 nm to about 1000 nm; and energy of the actinic radiation to which the surface is exposed is in a range from 4 J/cm.sup.2 to about 300 J/cm.sup.2.

2. A method according to claim 1 wherein the exposing of the surface to actinic radiation is applied selectively to create areas of the surface that are activated for subsequent bonding and areas of the surface that are not activated for subsequent bonding.

3. A method according to claim 2, wherein a mask is used which has areas which transmit actinic radiation to create areas of the surface that are activated for subsequent bonding areas and areas which block actinic radiation to create areas of the surface that are not activated for subsequent bonding.

4. A method of activating a surface according to claim 1, the method comprising the step of treating the surface with a (meth)acrylate, prior to exposing the surface to actinic radiation, wherein the (meth)acrylate is selected from tetrahydrofurfuryl acrylate (THFA): methyl methacrylate (MMA); and isobornyl acrylate (IBOA) and any combination thereof.

5. A method according to claim 4 wherein: the plastics substrate is PPS; and/or the activating is carried out for subsequent bonding with acrylic adhesive; and/or the energy of the actinic radiation to which the surface is exposed is in the range from about 25 J/cm.sup.2 to about 240 J/cm.sup.2.

6. A method of activating a surface according to claim 1 wherein the polyaryletherketone (a) is selected from polyether ether ketone (PEEK); polyether ketone ketone (PEKK); polyether ketone (PEK); polyether ether ketone ketone (PEEKK); or polyether ketone ether ketone ketone (PEKEKK); and the actinic radiation includes radiation with wavelength in the range from about 200 nm to about 700 nm.

7. A method according to claim 1 wherein the energy of the actinic radiation to which the surface is exposed is in the range from 4 J/cm.sup.2 to about 240 J/cm.sup.2.

8. A method according to claim 1 wherein the duration of the exposure is from about 0.1 seconds to about 360 minutes.

9. A method of activating a surface according to claim 1 wherein the activating is carried out for subsequent bonding with an acrylic adhesive, optionally wherein the energy of the actinic radiation to which the surface is exposed is in the range from 4 J/cm.sup.2 to about 240 J/cm.sup.2.

10. A method according to claim 1 wherein: the energy of the actinic radiation to which the surface is exposed is in the range from 4 J/cm.sup.2 to about 100 J/cm.sup.2; and/or the substrate is PPS, polybutadiene terephthalate (PBT), polyarylamide (PARA) or PEI; and/or activating is carried out for subsequent bonding with acrylic adhesive.

11. A method according to claim 1 wherein: the energy of the actinic radiation to which the surface is exposed is in the range from 4 J/cm.sup.2 to about 240 J/cm.sup.2; and/or the substrate is PEEK, PEKK, PEK, PEEKK, PEKEKK, PPS, PBT or PEI; and/or activating is carried out for subsequent bonding with epoxy adhesive.

12. A method of activating a surface to claim 1, wherein the activating is carried out for subsequent bonding with an epoxy adhesive.

13. A method of activating a surface of a plastics substrate formed from: (a) a polyaryletherketone; (b) a polymer containing a phenyl group directly attached to a carbonyl group, optionally wherein the carbonyl group is part of an amide group; (c) polyphenylene sulfide (PPS); or (d) polyetherimide (PEI); for subsequent bonding, the method comprising a step of exposing the surface to actinic radiation wherein the actinic radiation: includes radiation with wavelength in a range from about 10 nm to about 1000 nm; and energy of the actinic radiation to which the surface is exposed is in a range from about 0.5 J/cm.sup.2 to about 300 J/cm.sup.2, the method comprising the step of treating the surface with copper acrylate, prior to exposing the surface to actinic radiation.

14. A method according to claim 13 wherein: the energy of the actinic radiation to which the surface is exposed is in the range from about 3 J/cm.sup.2 to about 240 J/cm.sup.2; and/or activating is carried out for subsequent bonding with anaerobic adhesive.

15. A method of activating a surface according to claim 13 wherein the activating is carried out for subsequent bonding with an anaerobic adhesive.

16. A method of bonding a first substrate formed from: (a) polyaryletherketone; (b) a polymer containing a phenyl group directly attached to a carbonyl group, optionally wherein the carbonyl group is part of an amide group; (c) polyphenylene sulfide (PPS); or (d) polyetherimide (PEI); to a second substrate comprising the steps of: (i) exposing the surface of the first substrate to actinic radiation to activate the surface for subsequent bonding wherein the actinic radiation includes radiation with wavelength in the range from about 10 nm to about 1000 nm; and the energy of the actinic radiation to which the surface is exposed is in the range from about 4 J/cm.sup.2 to about 300 J/cm.sup.2, (ii) subsequently, bonding the activated surface of the first substrate to the second substrate utilising adhesive.

17. A method of bonding a first substrate formed from: (a) a polyaryletherketone; (b) a polymer containing a phenyl group directly attached to a carbonyl group, optionally wherein the carbonyl group is part of an amide group; (c) polyphenylene sulfide (PPS); or (d) polyetherimide (PEI); to a second substrate comprising the steps of: (i) exposing a surface of the first substrate to actinic radiation to activate the surface for subsequent bonding wherein the actinic radiation includes radiation with wavelength in the range from about 10 nm to about 1000 nm; and the energy of the actinic radiation to which the surface is exposed is in the range from about 0.5 J/cm.sup.2 to about 300 J/cm.sup.2, (ii) subsequently, bonding the activated surface of the first substrate to the second substrate utilising adhesive, the method comprising the step of treating the surface with copper acrylate, prior to step (i) exposing the surface to actinic radiation.

18. A method of bonding according to claim 16, the method comprising the step of treating the surface with a (meth)acrylate, prior to exposing the surface to actinic radiation.

19. A method of activating a surface of a plastics substrate formed from: polyether ether ketone (PEEK) polyether ketone ketone (PEKK), polyether ketone (PEK); polyether ether ketone ketone (PEEKK); or polyether ketone ether ketone ketone (PEKEKK); for subsequent bonding, the method comprising the step of exposing the surface to actinic radiation wherein the actinic radiation: includes radiation with wavelength in the range from about 10 nm to about 1000 nm; and the energy of the actinic radiation to which the surface is exposed is in the range from 4 J/cm.sup.2 to about 40 J/cm.sup.2 for subsequent bonding with acrylic adhesive; or the energy of the actinic radiation to which the surface is exposed is in the range from about 4 J/cm.sup.2 to about 850 J/cm.sup.2 for subsequent bonding with epoxy adhesive.

20. A method of activating a surface of a plastics substrate formed from polyarylamide (PARA), for subsequent bonding, the method comprising the step of exposing the surface to actinic radiation wherein the actinic radiation: includes radiation with wavelength in the range from about 10 nm to about 1000 nm; and the energy of the actinic radiation to which the surface is exposed is in the range from about 10 J/cm.sup.2 to about 30 J/cm.sup.2 for subsequent bonding with acrylic adhesive.

21. A method of activating a surface of a plastics substrate formed from polyphenylene sulfide (PPS), for subsequent bonding, the method comprising the step of applying copper acrylate to the surface and then exposing the surface to actinic radiation wherein the actinic radiation includes radiation with wavelength in the range from about 10 nm to about 1000 nm; and the energy of the actinic radiation to which the surface is exposed is in the range from about 2 J/cm.sup.2 to about 240 J/cm.sup.2 for subsequent bonding with acrylic adhesive optionally wherein the surface is treated with (meth)acrylate, prior to exposing the surface to the actinic radiation, or the energy of the actinic radiation to which the surface is exposed is in the range from about 5 J/cm.sup.2 to about 312 J/cm.sup.2 for subsequent bonding with epoxy adhesive.

22. A method of activating a surface of a plastics substrate formed from polybutadiene terephthalate (PBT), for subsequent bonding, the method comprising the step of exposing the surface to actinic radiation wherein the actinic radiation: includes radiation with wavelength in the range from about 10 nm to about 1000 nm; the energy of the actinic radiation to which the surface is exposed is in the range from about 10 J/cm.sup.2 to about 30 J/cm.sup.2 for subsequent bonding with acrylic adhesive.

23. A method of activating a surface of a plastics substrate formed from polyetherimide (PEI), for subsequent bonding, the method comprising the step of exposing the surface to actinic radiation wherein the actinic radiation: includes radiation with wavelength in the range from about 10 nm to about 1000 nm; the energy of the actinic radiation to which the surface is exposed is in the range from 4 J/cm.sup.2 to about 10 J/cm.sup.2 for subsequent bonding with acrylic adhesive, or the energy of the actinic radiation to which the surface is exposed is in the range from about 6 J/cm.sup.2 to about 120 J/cm.sup.2 for subsequent bonding with epoxy adhesive.

24. A method of activating a surface of a plastics substrate formed from: a polyaryletherketone; for subsequent bonding, the method comprising the steps of treating the surface with copper acrylate, prior to exposing the surface to actinic radiation, exposing the surface to actinic radiation wherein the actinic radiation: includes radiation with wavelength in the range from about 10 nm to about 1000 nm; and the energy of the actinic radiation to which the surface is exposed is in the range from about 9 J/cm.sup.2 to about 240 J/cm.sup.2 for subsequent bonding with anaerobic adhesive.

25. A method of activating a surface of a plastics substrate formed from: polyarylamide (PPS) for subsequent bonding, the method comprising the steps of treating the surface with copper acrylate, prior to exposing the surface to actinic radiation, exposing the surface to actinic radiation wherein the actinic radiation: includes radiation with wavelength in the range from about 10 nm to about 1000 nm; and the energy of the actinic radiation to which the surface is exposed is in the range from about 14 J/cm.sup.2 to about 30 J/cm.sup.2 for subsequent bonding with anaerobic adhesive.

26. A method of activating a surface of a plastics substrate formed from: polyarylamide (PARA) or polybutadiene terephthalate (PBT) for subsequent bonding, the method comprising the steps of treating the surface with copper acrylate, prior to exposing the surface to actinic radiation, exposing the surface to actinic radiation wherein the actinic radiation: includes radiation with wavelength in the range from about 10 nm to about 1000 nm; and the energy of the actinic radiation to which the surface is exposed is in the range from about 10 J/cm.sup.2 to about 30 J/cm.sup.2 for subsequent bonding with anaerobic adhesive.

27. A method of activating a surface of a plastics substrate formed from: polyetherimide (PEI) for subsequent bonding, the method comprising the steps of treating the surface with copper acrylate, prior to exposing the surface to actinic radiation, exposing the surface to actinic radiation wherein the actinic radiation: includes radiation with wavelength in the range from about 10 nm to about 1000 nm; and the energy of the actinic radiation to which the surface is exposed is in the range from about 3 J/cm.sup.2 to about 30 J/cm.sup.2 for subsequent bonding with anaerobic adhesive.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 depicts a bar chart illustrating initial bond strength and aged bond strength of lap shears prepared and tested according to Example 14.

DETAILED DESCRIPTION

(2) Method for testing of specimen with Loctite AA V5004 (acrylic adhesive)

(3) Specimen (lap shears) size: 1 inch4 inch (2.54 cm10.16 cm) (WL)

(4) Overlap Size: Minch [ inch inch (2.54 cm0.635 cm) (WL)]

(5) Two-component adhesive (Loctite AA V5004) is applied to the bond area on one of the specimens to be bonded from 50 ml syringe via a static mixer nozzle with 16 mixing elements.

(6) Second specimen has no adhesive applied directly. The bonding area of the laps/test specimen are aligned and clamped together with inch overlap using spring loaded clamps. The adhesive is cured with clamps on at room temperature for 24 hours. Clamps removed once the adhesive is cured. Tested by pulling in shear mode on calibrated tensile testing machine at a rate of 2 mm/min until break. Strength recorded in MPa (N/mm.sup.2)

(7) Method for Testing of Specimen with Loctite HHD8540 (Acrylic Adhesive)

(8) Specimen (lap shears) size: 1 inch4 inch (2.54 cm10.16 cm) (WL)

(9) Overlap Size: inch [1 inch inch (2.54 cm0.635 cm) (WL)]

(10) Two-component adhesive (Loctite HHD8540) applied to the bond area on one of the specimen to be bonded from 50 ml syringe via a static mixer nozzle with 16 mixing elements.

(11) Second specimen has no adhesive applied directly. The bonding area of the laps/test specimen are aligned and clamped together with % inch overlap using spring loaded clamps. The adhesive is cured with clamps on at room temperature for 24 hours. Clamps removed once the adhesive is cured. Tested by pulling in shear mode on calibrated tensile testing machine at a rate of 2 mm/min until break. Strength recorded in MPa (N/mm.sup.2).

(12) Method for Testing of Specimen with Loctite 5189 Anaerobic Adhesive

(13) Specimen (lap shears) size: 1 inch4 inch (2.54 cm10.16 cm) (WL)

(14) Overlap Size: inch [1 inch inch (2.54 cm0.635 cm) (WL)]

(15) One-component adhesive applied to one of the specimen to be bonded from 50 ml bottle, no mixing required.

(16) Second specimen has no adhesive applied directly. The bonding area of the laps/test specimen are aligned and clamped together with % inch overlap using spring loaded clamps. The adhesive is cured with clamps on at room temperature for 96 hours. Clamps removed once the adhesive is cured. Tested by pulling in shear mode on calibrated tensile testing machine at a rate of 2 mm/min until break. Strength recorded in MPa (N/mm.sup.2). Loctite 5189 is a liquid anaerobic composition used as a flange sealant.

(17) All bond strength testing was carried out using standard procedure ASTM D3163. Note: All UV intensities are measured by a calibrated PowerPuck UV radiometer, UV bands as measured by PowerPuck are: UVC: 250-260 nm, UVB: 280-320 nm, UVA: 320-390 nm and UVV: 395-445 nm.

(18) One grade of polyphenylene sulfide (PPS) was used for all testing in all examples below, this grade is injection moulded Fortran 6165 PPS. One grade of Polyetherimide (PEI) was used for all testing in all examples below, this grade is Ultem TECAPEI. One grade of polyarylamide (PARA) was used for all testing in all examples below, this grade is injection moulded Kalix 9950. One grade Polyether ether ketone (PEEK) was used for all testing in all examples below, this grade is Victrex 450G which is an unreinforced semi crystalline PEEK. Where a Loctite UVALOC 1000 was used it was fitted with a Mercury D-type bulb (iron doped). For example it is used as a UV source in Examples 1, 2, 5, 6, 8, 9, 13, 15, 16, 17, 19 and 20 with intensities measured using a calibrated PowerPuck as mentioned above. In other examples, as indicated, a UV LED source was used.

(19) Method for Testing of Specimen with Loctite HHD3542 (Hot Melt Adhesive)

(20) Specimen (lap shears) size: 1 inch4 inch (2.54 cm10.16 cm) (WL)

(21) Overlap Size: inch [1 inch inch (2.54 cm0.635 cm) (WL)]

(22) Reactive Hot-melt adhesive (Loctite HHD3542) dispensed from hot melt dispenser applied to the bond area on one of the specimen to be bonded from 50 ml syringe.

(23) Second specimen has no adhesive applied directly. The bonding area of the laps/test specimen are aligned and clamped together with % inch overlap using spring loaded clamps. The adhesive is cured with clamps on at room temperature for 24 hours. Clamps removed once the adhesive is cured. Tested by pulling in shear mode on calibrated tensile testing machine at a rate of 2 mm/min until break. Strength recorded in MPa (N/mm2).

Example 1: PEEK+UV for Acrylic Bonding

(24) Without UV treatment of the lap shears to be bonded, Loctite HHD8540 (acrylic adhesive) bonds unreinforced semi crystalline PEEK, such as Victrex 450G PEEK, lap shears, with a bond strength of 2.7 MPa at which value bond failure occurs.

(25) Exposure of identical PEEK lap shears to UV radiation110 mW/cm.sup.2 from a 375 nm LED lamp for 1 minute before utilising Loctite HHD8540 (acrylic adhesive) to bond the lap shears gave a significantly higher bond strength of 4.7 MPa, again with bond failure occurring at that value.

Example 2: PEEK+UV for Acrylic Bonding

(26) Without UV treatment of the lap shears to be bonded, Loctite AA V5004 (acrylic adhesive) bonds unreinforced semi crystalline PEEK, such as Victrex 450G PEEK, lap shears, with a bond strength of 3.4 MPa at which value bond failure occurs.

(27) Exposure of identical PEEK lap shears to UV radiation110 mW/cm.sup.2 from a 375 nm LED lamp for 2 minutes before utilising Loctite AA V5004 (acrylic adhesive) to bond the lap shears gave a significantly higher bond strength of 7.8 MPa, this time with substrate failure occurring at that value.

(28) Exposure of unreinforced semi crystalline PEEK, such as Victrex 450G PEEK to UV radiation @110 mW/cm.sup.2 from a 375 nm LED lamp for 4 minutes gave a bond strength using Loctite V5004 (acrylic adhesive) of 4.4 MPa with bond failure.

(29) It will be noted that both exposure times (2 minutes and 4 minutes) give better results than without exposure to UV. However it is noted that the exposure can be optimised. For example exposure for a period from about 10 seconds to about 2 minutes may be optimum for any aspect of the present invention.

(30) Exposure of unreinforced semi crystalline PEEK, such as Victrex 450G PEEK to UV radiation from a Loctite UVALOC 1000 UV Cure Chamber (UVA radiation @124 mW/cm.sup.2, UVB radiation @109 mW/cm.sup.2, UVC radiation @20 mW/cm.sup.2, and UVV radiation @76 mW/cm.sup.2) for 2 minutes gave a bond strength utilising Loctite AA V5004 (acrylic adhesive) of 7.3 MPa with bond failure.

(31) Use of a 375 nm LED handheld source (33 mW/cm.sup.2) on unreinforced semi crystalline PEEK, such as Victrex 450G PEEK resulted in bonds strengths of 4.5 MPa after 2 minutes of exposure and 4.1 MPa after 4 minutes of exposure, when bonded with Loctite AA V5004, both exhibiting bond failure.

Example 3: PARA UV for Acrylic bonding

(32) Lap shears made of a 50% glass fibre reinforced polyarylamide (PARA) (e.g. Kalix 9950) was bonded with Loctite AA V5004 (acrylic adhesive) without exposure to UV light gave a bond strength of 5.67 MPa at which value bond failure was observed.

(33) Identical lap shears were bonded with Loctite AA V5004 (acrylic adhesive) after exposure to UV radiation @110 mW/cm.sup.2 from 375 nm LED lamp for 2 minutes. A bond strength of 7.52 MPa was achieved at which value bond failure was observed.

(34) Identical lap shears were bonded with Loctite AA V5004 (acrylic adhesive) after exposure to UV radiation @110 mW/cm.sup.2 from 375 nm LED lamp for 4 minutes. A bond strength of 7.92 MPa was achieved at which value bond failure was observed.

(35) LOCTITE AA V5004 (acrylic adhesive) is a two-part methacrylate composition. Loctite HHD8540 is a two-part methacrylate composition.

Example 4: PEEK+Primer UV for Anaerobic Bonding

(36) Loctite 5189 (anaerobic adhesive) does not bond unreinforced semi crystalline PEEK, such as Victrex 450G PEEK, lap shears, as the adhesive does not cure in the bond line.

(37) Treating the area of each of the PEEK lap shears that is to be bonded with 1% (w/w) copper acrylate in acrylic acid with subsequent exposure of the treated area of the PEEK to UV radiation @115 mW/cm.sup.2 from 375 nm LED lamp for 2 or 4 minutes and then removal of the excess 1% copper acrylate in acrylic acid solution by wiping, and then bonding the lap shears with Loctite 5189 (anaerobic adhesive) gave bond strengths of 4.9 and 4.4 MPa respectively, both with bond failure.

(38) By comparison applying the 1% copper acrylate in acrylic acid solution to the same kind of PEEK lap shears and not exposing the treated surface to actinic radiation gave a bond strength of 2.52 MPa with bond failure.

(39) So this example shows that without pre-treatment with copper acrylate or UV exposure no bonding occurs. It also shows that with pre-treatment bonding occurs.

Example 5: PEEK+Primer UV for Anaerobic Bonding

(40) Loctite 5189 (anaerobic adhesive) does not bond unreinforced semi crystalline PEEK, such as Victrex 450G PEEK, lap shears, as the adhesive does not cure in the bond line.

(41) Treating the area of each of the PEEK lap shears with 1% (w/w) copper acrylate in acrylic acid with subsequent exposure of the treated PEEK to UV radiation from a Loctite UVALOC 1000 UV Cure Chamber (UVA radiation @124 mW/cm.sup.2, UVB radiation @109 mW/cm.sup.2, UVC radiation @20 mW/cm.sup.2, and UVV radiation @76 mW/cm.sup.2) for respectively 30 seconds or 1 minute and then removal of the excess 1% copper acrylate in acrylic acid solution by wiping, and then bonding the lap shears with Loctite 5189 (anaerobic adhesive) gave bond strengths of 7.0 or 8.3 MPa respectively with bond failure.

Example 6: PEEK+Primer UV for Anaerobic Bonding

(42) Loctite 5189 (anaerobic adhesive) does not bond unreinforced semi crystalline PEEK, such as Victrex 450G PEEK, lap shears, as the adhesive does not cure in the bond line.

(43) Treating the area of each of the PEEK lap shears with 3% (w/w) copper acrylate in 2-methyltetrahydrofuran with subsequent exposure of the treated PEEK to UV radiation @UVA: 213 mW/cm.sup.2, UVB: 189 mW/cm.sup.2, UVC: 36 mW/cm.sup.2, UVV: 135 mW/cm.sup.2 from UV Mercury lamp with D-type bulb fitted for 2 or 4 minutes and then removal of the excess copper acrylate solution by wiping gave bond strengths of 5.3 MPa and 4.8 MPa (respectively) with bond failure.

(44) Applying the 3% copper acrylate in 2-methyltetrahydrofuran solution and bonding the PEEK without prior exposure to UV gave a bond strength of 0.89 MPa with adhesive failure.

Example 7: PEEK+Primer UV for Anaerobic Bonding

(45) Loctite 5189 (anaerobic adhesive) does not bond unreinforced semi crystalline PEEK, such as Victrex 450G PEEK, lap shears, as the adhesive does not cure in the bond line.

(46) Treating the area of each of the PEEK lap shears with 3% copper acrylate in acetone with subsequent exposure of the treated PEEK to UV radiation @115 mW/cm.sup.2 from 375 nm LED lamp for 2 or 4 minutes and then removal of the excess copper acrylate solution by wiping gave bond strengths of 3.5 MPa or 3.2 MPa (respectively) with bond failure.

(47) Applying the PEEK with 3% copper acrylate in acetone with subsequent exposure of the treated PEEK to UV radiation @1 W/cm.sup.2 from 375 nm LED lamp for 2 or 4 minutes and then removal of the excess copper acrylate solution by wiping gave bond strengths of 5.1 MPa and 4.1 MPa (respectively) with bond failure.

(48) Applying the 3% copper acrylate in acetone solution and bonding the PEEK without prior exposure to UV gave a bond strength of 0.96 MPa with bond failure.

Example 8: PARA+Primer UV for Anaerobic Bonding

(49) Loctite 5189 (anaerobic adhesive) does not bond PARA (Kalix 9950), as the adhesive does not cure in the bond line.

(50) Applying 3% copper acrylate in 2-methyltetrahydrofuran to the PARA with subsequent exposure of the treated PARA to UV radiation @UVA: 213 mW/cm.sup.2, UVB: 189 mW/cm.sup.2, UVC: 36 mW/cm.sup.2, UW: 135 mW/cm.sup.2 from UV Mercury lamp with D-type bulb fitted for 2 or 4 minutes and then removal of the excess copper acrylate solution by wiping gave bond strengths of 6.0 MPa and 8.1 MPa (respectively) with bond failure.

(51) Applying the 3% copper acrylate in 2-methyltetrahydrofuran solution and bonding the PARA without prior exposure to UV gave a bond strength of 5.5 MPa with adhesive failure.

Example 9: PPS+Primer UV for Anaerobic Bonding

(52) Loctite 5189 (anaerobic adhesive) without primer does not bond Fortran 6165 PPS, the adhesive does not cure in the bond line.

(53) Applying 3% copper acrylate in 2-methyltetrahydrofuran to the PPS with subsequent exposure of the treated PPS to UV radiation @UVA: 213 mW/cm.sup.2, UVB: 189 mW/cm.sup.2, UVC: 36 mW/cm.sup.2, UVV: 135 mW/cm.sup.2 from UV Mercury lamp with D-type bulb fitted for 2 or 4 minutes and then removal of the excess copper acrylate solution by wiping gave bond strengths of 5.2 MPa and 4.9 MPa (respectively) with bond failure.

(54) Applying the 3% copper acrylate in 2-methyltetrahydrofuran solution and bonding the PPS without prior exposure to UV gave a bond strength of 3.3 MPa with bond failure.

Example 10: PEEK+Primer UV for Anaerobic Bonding

(55) Loctite 5189 (anaerobic adhesive) without primer does not bond unreinforced semi crystalline PEEK, such as Victrex 450G PEEK, the adhesive does not cure in the bond line.

(56) Applying 3% copper acrylate in water to the PEEK with subsequent exposure of the treated PEEK to UV radiation @115 mW/cm.sup.2 from 375 nm LED lamp for 2 or 4 minutes and then removal of the excess copper acrylate solution by wiping gave bond strengths of 3.1 MPa and 4.3 MPa (respectively) with bond failure.

(57) Applying the 3% copper acrylate in water solution and bonding the PEEK without prior exposure to UV gave a bond strength of 0.4 MPa with bond failure.

Example 11: PPS+Primer UV for Acrylic Bonding

(58) Loctite AA V5004 (acrylic adhesive) bonds PPS in lap shear test at 7.4 MPa with adhesive failure.

(59) Exposing the same substrate to UV radiation (375 nm UV LED, 115 mW/cm.sup.2 for 4 minutes) and then bonding with the same adhesive gave no improvement in bond strengths obtained.

(60) The area of each of the PPS lap shears was treated with methacrylic acid and exposed to varying intensities of UV radiation at 375 nm from an LED source for various times. The table below shows the times, intensities and bond strengths achieved.

(61) TABLE-US-00001 Intensity of UV radiation Time Exposed to Average bond strength at 375 nm (mW/cm.sup.2) radiation for (s) achieved (MPa) 0 0 9.5 115 120 7.4 115 240 10.2 1000 10 8.9 1000 20 10.6 1000 30 12.9 1000 60 12.9 1000 120 11.6 1000 240 12.1

(62) These results show that priming with methacrylic acid alone increases the bond strength obtained, but the combination of a correct amount (dose) of actinic radiation such as UV together with the methacrylic acid significantly improve the bond strengths obtained using a 2K acrylic on PPS. Provided that there is a minimum exposure to actinic radiation of greater than 14 Joules/cm.sup.2, for example greater than about 15 Joules/cm.sup.2, such as greater than about 17 Joules/cm.sup.2, for example greater than about 18 Joules/cm.sup.2 such as greater than 19 Joules/cm.sup.2 desirably greater than about 20 Joules/cm.sup.2.

(63) The present inventors believe that the drop in bond strengths to 7.4 MPa and 8.9 MPa seen in two of the results in the table immediately above does signify a change (reaction) happening on the surface. Without being limited to any specific mode of action it is thought that a change (reaction) needs to reach a certain state before the benefit of actinic radiation, such as UV, utilised in combination with the methacrylic acid, is seen. Accordingly exposure to the actinic radiation for a time sufficient to see the benefit is required.

Example 12: PPS+Primer UV for Acrylic Bonding

(64) The area of the PPS lap shears to be bonded were respectively pre-treated with *THFA, MMA and IBOA, then exposed to UV radiation at an intensity of 1 W/cm.sup.2 at 375 nm from an LED source for varying times. These activated substrates were then bonded with Loctite AA V5004 (acrylic adhesive). The table below shows the material used for pre-treatment and the corresponding time of UV exposure and the bond strengths achieved.

(65) TABLE-US-00002 Average Strength Primer/pre-treatment* (MPa) Brushed with THFA, no UV exposure 11.92 Brushed with THFA and then UV for 30 s 16.22 Brushed with THFA and then UV for 1 min 13.34 Brushed with MMA, no UV exposure 12.30 Brushed with MMA and then UV for 30 s 13.73 Brushed with MMA and then UV for 1 min 15.81 Brushed with IBOA, no UV exposure 12.46 Brushed with IBOA and then UV for 30 s 15.06 Brushed with IBOA and then UV for 1 min 18.17

(66) These results show that priming with a (meth)acrylate alone increases the bond strength obtained, but the combination of UV and (meth)acrylate significantly improve the bond strengths obtained using a two-part acrylic on PPS.

(67) *THFA: tetrahydrofurfuryl acrylate; MMA: methyl methacrylate; IBOA: isobornyl acrylate

Example 13: PPS+Primer UV for Acrylic Bonding

(68) The area of the PPS lap shears to be bonded were pre-treated with IBOA, then exposed to UV from a Mercury D-bulb for 30 seconds or 1 minute at the following intensity (measured by a calibrated Power Puck): 109 mW/cm.sup.2 UVV (395-445 nm), 184 mW/cm.sup.2 UVA (320-390 nm), 169 mW/cm.sup.2 UVB (280-320 nm) and 30 mW/cm.sup.2 UVC (250-260 nm). These were then left at room temperature for 2 weeks and then bonded with Loctite AA V5004 (acrylic adhesive) to give the following average bond strengths.

(69) Exposure time 30 seconds: bond strength 16.8 MPa

(70) Exposure time 1 minute: bond strength 11.4 MPa.

(71) These results show that the priming effect can be obtained with actinic radiation such as UV of varying wavelengths and that the resulting primed surface is stable for at least 2 weeks after priming. It also shows that there is an optimum exposure. So even though the bond strength after 1 minute is lower than the bond strength after 30 seconds there is still an overall positive impact on the bond strength after 1 minute.

Example 14: PPS+Primer UV for Acrylic Bonding

(72) The area of the PPS lap shears to be bonded were treated with IBOA, then exposed to UV radiation at an intensity of 1 W/cm.sup.2 at 375 nm from an LED source for 1 minute. These primed substrates were then bonded with Loctite AA V5004 (acrylic adhesive). The some of the laps were tested initially and then some of the bonded items were then subjected to aging at 65 C./95% relative humidity and 600C dry for two weeks. Also, while the aging cycle was being undertaken some of the bonded laps were left at room temperature for the same period. The results are in FIG. 1.

(73) These results indicate that this priming method is stable to the ageing cycles carried out.

Example 15: PEEK UV for Epoxy Bonding

(74) Loctite EA 9492 without UV treatment bonds PEEK (Victrex 450G) at 4.5 MPa with adhesive failure. Loctite EA 9492 is a high temperature resistant, two component epoxy adhesive.

(75) Exposing the area to be bonded to UV radiation from a Mercury D-type bulb at 193 mW/cm.sup.2 in UVA, 183 mW/cm.sup.2 in UVB, 35 mW/cm.sup.2 in UVC, 136 mW/cm.sup.2 in UVV for varying times gave the following results.

(76) TABLE-US-00003 Exposure time Bond Strength (sec) (MPa) 75 8.26 90 9.46 105 10.06 120 11.33 135 12.38 150 8.17 165 6.71 180 8.00

(77) These results show that with enough exposure there are significant gains in observed bond strength but also that too much exposure can decrease this effect (although still better than without any UV exposure).

Example 16, PEEK UV for Epoxy Bonding

(78) Loctite EA9696 without UV treatment bonds PEEK (Victrex 450G) at 4.5 MPa with adhesive failure. Loctite EA9696 is a modified epoxy film adhesive.

(79) Exposing the area to be bonded to UV radiation from a Mercury D-type bulb at 193 mW/cm.sup.2 in UVA, 183 mW/cm.sup.2 in UVB, 35 mW/cm.sup.2 in UVC, 136 mW/cm.sup.2 in UVV for 130 seconds gave 11.45 MPa bond strengths.

(80) Loctite EA9696 bonds Carbon Fibre Reinforced (CFR) PEEK (Tencate Cetex TC1200) without UV treatment at 16.43 MPa with adhesive failure. Exposing the area to be bonded to UV radiation from a Mercury D-type bulb at 1801 mW/cm.sup.2 in UVA, 502 mW/cm.sup.2 in UVB, 65 mW/cm.sup.2 in UVC, 2322 mW/cm.sup.2 in UVV for 5 seconds gave 38.34 MPa bond strengths with mixed cohesive and adhesive failure modes seen.

(81) Tests have indicated that when the surface of the CFR-PEEK is activated using this method it remains active for bonding for at least 4 weeks.

Example 17, PEEK UV for Epoxy Bonding

(82) Loctite EA9394 without UV treatment bonds PEEK (Victrex 450G) at 3.4 MPa with adhesive failure. Loctite EA9394 is a two-part epoxy structural paste adhesive.

(83) Exposing the area to be bonded to UV radiation from a Mercury D-type bulb at 193 mW/cm.sup.2 in UVA, 183 mW/cm.sup.2 in UVB, 35 mW/cm.sup.2 in UVC, 136 mW/cm.sup.2 in UVV for 130 seconds gave 8.8 MPa bond strengths.

(84) Loctite EA9394 bonds Carbon Fibre Reinforced (CFR) PEEK (Tencate Cetex TC1200) without UV treatment at 2.5 MPa with adhesive failure. Exposing the area to be bonded to UV radiation from a Mercury D-type bulb at 1801 mW/cm.sup.2 in UVA, 502 mW/cm2 in UVB, 65 mW/cm.sup.2 in UVC, 2322 mW/cm.sup.2 in UVV for 25 seconds gave 29.86 MPa bond strengths with adhesive failure.

Example 18: PEI and PPS UV for Epoxy Bonding

(85) Loctite EA 9492 (epoxy adhesive) without UV treatment bonds PEI at 11.9 MPa and PPS at 12.2 MPa with adhesive failure.

(86) Exposure of the PEI to UV radiation @1 W/cm.sup.2 from 375 nm LED lamp for 1 minute and bonding with Loctite EA 9492 (epoxy adhesive) gave a bond strength of 19.5 MPa with substrate failure on PEI and 17.4 with adhesive failure on PPS.

Example 19: PPS UV for Epoxy Bonding

(87) Loctite EA 9492 (epoxy adhesive) without UV treatment bonds PPS at 12.2 MPa with adhesive failure.

(88) Exposure of the PPS to UV radiation from a UVALOC 1000 fitted with a Mercury D bulb (UVA@213 mW/cm.sup.2, UVB@189 mW/cm.sup.2, UVC@36 mW/cm.sup.2 and UW:135 mW/cm.sup.2, as measured with a calibrated PowerPuck and bonding with Loctite EA 9492 (epoxy adhesive) gave a bond strength greater than 18 MPa with structural failure of the substrate.

(89) Loctite EA9394 (epoxy adhesive) bonds carbon fibre reinforced (CFR) PPS (Tencate Cetex TC1100) without UV treatment at 5.3 MPa with adhesive failure. Exposing the area to be bonded to UV radiation from a Mercury D-type bulb at 1653 mW/cm.sup.2 in UVA, 436 mW/cm.sup.2 in UVB, 61 mW/cm.sup.2 in UVC, 2275 mW/cm.sup.2 in UW for 20 seconds gave 39.0 MPa bond strengths with adhesive failure.

(90) Loctite EA9696 bonds CFR PPS (Tencate Cetex TC1100) without UV treatment at 8.17 MPa with adhesive failure. Exposing the area to be bonded to UV radiation from a Mercury D-type bulb at 1870 mW/cm.sup.2 in UVA, 703 mW/cm.sup.2 in UVB, 96 mW/cm.sup.2 in UVC, 2548 mW/cm.sup.2 in UVV for 10 seconds gave 31.83 MPa bond strengths with mixed cohesive and adhesive failure modes seen and increasing that time to 40 seconds at the same intensities gave 40.29 MPa bond strengths with mixed cohesive failure of the adhesive and structural failure of the substrate.

(91) Tests have indicated that when the surface of the CFR-PPS is activated using this method it remains active for bonding for at least 4 weeks.

Example 20: PPS UV for Epoxy Bonding

(92) PPS laps were exposed to UV radiation from a UVALOC 1000 fitted with a Mercury D bulb (UVA@213 mW/cm.sup.2, UVB@189 mW/cm.sup.2, UVC@36 mW/cm.sup.2 and UW:135 mW/cm.sup.2, as measured with a calibrated PowerPuck) for 1 minute.

(93) These UV activated PPS laps were bonded with Loctite 9514 (one-part epoxy) and gave bond strengths greater than 22 MPa with 100% substrate failure. Loctite 9514 is a toughened one-part heat curing epoxy adhesive.

Example 21: PPS and PEI UV for Epoxy Bonding

(94) PPS and PEI laps were exposure to UV radiation from a 375 nm LED flood system at 115 mW/cm.sup.2 for 2 minutes.

(95) The UV activated PPS bonded with Loctite EA 9492 (epoxy adhesive) was exposed to environmental aging at 600C (dry) and at 650C 95% relative humidity for two weeks.

(96) There was no significant change in bond strengths, with a 20% standard deviation in initial strengths and all changes after aging less than 10% from the original strength.

(97) The same tests were carried out with the UV activated PEI bonded with LoctiteEA 9492 (epoxy adhesive).

(98) There was no significant change in bond strengths, with an 8% standard deviation in initial strengths and all changes after aging less than 7% from the original strength

Example 22: PEEK UV and Acrylic Monomer for 2K Acrylic Bonding

(99) Loctite V5004 without UV treatment bonds PEEK (Victrex 450G) at 3.4 MPa with adhesive failure.

(100) Brushing the surface with methacrylic acid and then exposing the coated area to UV radiation at 110 mW/cm.sup.2 375 nm LED 4 minutes, gave 7.1 MPa bond with substrate failure being observed.

Example 23: PEI UV for 2K Acrylic Bonding

(101) Loctite V5004 without UV treatment bonds PEI (Tecapei Ultem) at 5.3 MPa with adhesive failure.

(102) Exposing the area to be bonded to UV radiation at 110 mW/cm.sup.2 375 nm LED 30 seconds, gave 6.4 MPa bond with adhesive failure.

(103) Exposing the area to be bonded to UV radiation at 110 mW/cm.sup.2 375 nm LED 1 minute, gave 9.3 MPa bond with adhesive failure.

Example 24: PEI UV+Copper Acrylate for Anaerobic Bonding

(104) Loctite 5189 (anaerobic adhesive) without primer does not bond PEI (Tecapei Ultem) the adhesive does not cure in the bond line.

(105) Applying 1% copper acrylate in Acrylic acid to the area of PEI to be bonded with subsequent exposure of the coated section of the PEI to UV radiation @115 mW/cm.sup.2 from 375 nm LED lamp for 30 seconds, 1 minute, 2 minutes or 4 minutes and then removal of the excess 1% copper acrylate in acrylic acid solution by wiping gave bond strengths of 3.4, 3.4, 3.2 and 4.7 MPa (respectively) with adhesive failure when bonded with Loctite 5189 (anaerobic adhesive).

(106) Applying the 1% Copper Acrylate in Acrylic acid solution and not exposing the coated surface gave a bond strength of 2.0 MPa with adhesive failure when bonded with Loctite 5189 (anaerobic adhesive).

Example 25, PEKK UV for Epoxy Bonding

(107) Loctite EA9394 without UV treatment bonds PEKK at 9.9 MPa with adhesive failure. Loctite EA9394 is a two-part epoxy structural paste adhesive.

(108) Exposing the area to be bonded to UV radiation @1 W/cm.sup.2 from 375 nm LED lamp for 60 seconds before bonding with Loctite EA9394 gave gave a bond strength of 30.8 MPa with adhesive failure.

(109) Exposing the area to be bonded to UV radiation from a Mercury D-type bulb at 3.5 W/cm.sup.2 for 10 seconds gave 34.6 MPa bond strength with adhesive failure. Exposing the area to be bonded to UV radiation from a Mercury D-type bulb at 3.5 W/cm.sup.2 for 30 seconds gave 37.5 MPa bond strength with mixed adhesive and cohesive failure.

Example 26 PBT+UV Activation for Hot Melt Adhesive Bonding

(110) Loctite HHD 3542 is a toughened, one component polyurethane reactive hot melt adhesive. Loctite HHD 3542 without UV treatment bonds PBT to PBT with a bond strength of 2.5 MPa. After five seconds of UV activation (28 J/cm.sup.2 measured using a PowerPuck), bond strength of 3.4 MPa was achieved. This is a 37% increase in bond strength.

Example 27: PBT+UV for Acrylic Bonding

(111) Loctite HHD 8540 without UV treatment bonds PBT to PBT with a bond strength of 3 MPa. After five seconds of UV activation (28 J/cm.sup.2 measured using a PowerPuck), bond strength of 9 MPa was achieved with cohesive failure of the adhesive and 11.4 MPa with substrate failure was achieved.

Example 28: PBT+UV for Anaerobic Bonding

(112) An anaerobic composition comprising (meth)acrylate monomers and oligomers without UV treatment bonds stainless steel to PBT with a bond strength of 2.8 MPa. After the PBT lap shear specimen underwent five seconds of UV activation (28 J/cm.sup.2 measured using a PowerPuck), and then bonded a bond strength of 8.5 MPa was achieved.

(113) An anaerobic composition comprising (meth)acrylate monomers and oligomers without UV treatment fails to bond stainless steel to PBT, failing adhesively to the PBT. After the PBT lap shear specimen underwent five seconds of UV activation (28 J/cm.sup.2 measured using a PowerPuck), and then bonded a bond strength of 4.4 MPa was achieved.

(114) The present inventor takes the view that when PBT is activated in this way, it remains activated. In other words, the activation will last at least weeks or months. There is reason to believe that this may be due to a permanent chemical change to the surface and therefore the activation does not significantly decreased over the extended period of time.

(115) The words comprises/comprising and the words having/including when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

(116) It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.