AU631488B2

AU631488B2 - Inhomogenous laminating compositions

Info

Publication number: AU631488B2
Application number: AU73730/91A
Authority: AU
Inventors: Christopher Michael Andrews
Original assignee: Ciba Geigy AG
Current assignee: Novartis AG
Priority date: 1990-03-23
Filing date: 1991-03-22
Publication date: 1992-11-26
Anticipated expiration: 2011-03-22
Also published as: AU7373091A; GB9006537D0; JPH04222803A; EP0448516A1

Description

r 9 631 S F Ref: 155898 FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Class Int Class Complete Specification Lodged: Accepted: Published: Priority: Related Art: Name and Address of Applicant: Address for Service: Ciba-Geigy AG Klybeckstrasse 141 4002 Basel

SWITZERLAND

Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South ales, 2000, Australia Complete Specification for the invention entitled: "Inhomogeneous Laminating CompositionS The following statement Is a full description of this invention, including the best method of performing it known to me/us 5845/3 1- K-18003/A/MA 1992 ABSTRACT OF THE DISCLOSURE "Inhomogeneous Laminating

COMPOSITIONS.

A composition, suitable for use in bonding two or more substrates, at least one of which is permeable to ultra-violet radiation, comprising A) a film-forming copolymer of an olefin S with a polar monomer, B) a photopolymerizable acrylic monomer; and C) a photoinitiator S for photo-polymerization of acrylic groups the total composition, while transparent to light, exhibiting partial incompatibility between the components A) and B).

004 0 t 9 0 0 0 0 o S 0a 0 1 I -DLsF~W.

1A K-18003/A/MA 1992 The present invention relates to new compositirns for use in the lamination of substrates.

Thermoplastic polyvinyl butyral resins have been used in the intermediate layers of laminated substrates, especially laminated glass products e.g. automobile glass components such as windows and windscreens.

Such thermoplastic resins are disadvantageous in several respects the operation for adhesion of the substrates must be effected at a temperature above the softening point of the resin; the substrates can move, or bubbles may form in the resin as a result of the heating step, but the substrates cannot be separated to rectify these faults; and the adhesive power of the resin is impaired with time due to the adsorption of water by the resin.

In US Patent Specification No. 4317862, a laminated (sandwich) glass is described comprising glass plates, between which is interposed an intermediate layer formed by photosetting a photosensitive resin comprising mainly a mixture of a) a high polymer having groups containing acryloyloxy or methacryloyloxy groups of formulae:

CH

2

C(R)-COO-

CH

2

C(R)-COO-(CH

2 or

CH

2

C(R)-COO-[(CH

2 in which R is hydrogen or methyl, n is 2, 3, 4 or 5, m is 1, 2, 3 or 4 and 1 is a positive integer of 1 to 30; and b) acrylic acid, methacrylic acid or their derivatives.

Advantages of such laminates over the polyvinyl butyral-based laminates are, e.g. that the resin does not cure until irradiated with light, so that the glass plates are readily separated prior to irradiation if foreign bodies or bubbles are observed in the resin; and, even when water is present in it, the resin maintains its adhesion strength over long periods of time.

The high polymer and monomer used in forming the intermediate layer of the laminated I- -2glasj of US 4317862, form primary bonding with each other so that the layer is homogeneous.

We have now found that by using an inhomogeneous laminating resin comprising A) a film-forming copolymer of an olefin with a polar comonomer and B) a photopolymerizable monomer, resins can be obtained in which the components A) and B) are sufficiently incompatible that one component wets out the surface of a substrate to which it is applied. As a result, the resin exhibits little adhesion to the substrate surface, until irradiation of the resin is effected, thereby greatly facilitating any necessary improvement of the resin composition e.g. by removing foreign bodies or bubbles, or any adjustment of the disposition of the substrate in a laminated structure. Moreover, the wetting out phenomenon ensures excellent adhesion between the resin and substrates to which it is applied.

Accordingly, the present invention provides a composition, suitable for use in bonding two or more substrates, at least one of which is permeable to ultra-violet radiation, comprising A) a film-forming copolymer of an olefin with a polar monomer, B) a photopolymerizable, acrylicf a and C) a photoinitiator for photo-polymerization of acrylic groups, the total composition, while transparent to light, exhibiting partial incompatibility between the components A) and B).

The present invention also provides a laminate comprising two or more substrates and, interposed between the substrates or adjacent pairs of substrates, a composition according to the present invention comprising components A) and as hereinbefore defined.

The present invention further provides a laminate comprising two or more substrates and, interposed between the substrates, or adjacent pairs of substrates, a composition according to the present invention, photopolymerized by irradiation with UV light.

Copolymer A) is preferably a copolym.'r formed from a C 2 -C4 straight or brancned olefin, especially ethylene and a polar monomer such as vinyl acetate or acrylic acid or an alkyl ester thereof, The respective proportions by weight of the olefin and polar monomer components are selected such that a copolymer is obtained which is transparent to light.

Preferred ratios of olefin to polar monomer range from 95/5 to 20/80 by weight, especially from 95/5 to 50/50 by weight.

III

While the preferred copolymer A) is an ethylene/vinyl acetate copolymer (commercially available in preferred molar ratios as Elvax from DuPont), other suitable copolymers (A) include those formed from ethylene and ethyl acrylate, as well as terpolymers of ethylene, vinyl acetate and acrylic acid.

The amount of the film-forming copolymer present in the composition according to the present invention may range from 1 to 95% by weight, but preferably ranges from to 80% by weight based on the total weight of the composition.

The photopolymerizable material B) may be a monoacrylic material containing one acryloyloxy or methacryloyloxy group together with a hydroxy or carboxyl group; a material containing, on average, more than one acryloyloxy or" methacryloyloxy group per molecule; or a mixture of two or more thereof.

Preferred monoacrylic materials for use as include hydroxyalkyl acrylates and hydroxyalkyl methacrylates such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, the corresponding methacrylates and mixtures of two or more thereof; carboxyalkyl acrylates and carboxyalkyl methacrylates such as 2-carboxyethyl acrylate (which is commercially available as a product prepared by dimerisation of acrylic acid containing 10 by weight of higher oligomers of acrylic acid) and 2-carboxy-2-methylethyl methacrylate (which can be prepared by dimerisation of methacrylic acid); and carboxyl group-containing adducts of a hydroxyalkyl acrylate or hydroxyalkyl methacrylate with a polycarboxylic acid anhydride such as maleic anhydride, succinic anhydride, tetrahydrophthalic anhydride or hexahydrophthalic anhydride.

Suitable materials having, on average, more than one acryloyloxy or methacryloyloxy group per molecule include esters of epoxide resins with acrylic or methacrylic acid or with a carboxyl group-containing adduct of a hydroxyalkyl acrylate or hydroxyalkyl methacrylate with a polycarboxylic acid anhydride hereinbefore mentioned and the reaction products of a hydroxyalkyl acrylate or hydroxyalkyl methacrylate with an isocyanate-terminated prepolymer derived from a polyol and a polyisocyanate. Examples of esters of epoxide resins include esters of acrylic acid or methacrylic acid with resins having, on average, more than one glycidyl group per molecule, preferably polyglycidyl ethers of polyhydric alcohols such as butane-1,4-diol, neopentyl glycol or polypropylene glycols, polyglycidyl ethers of polyhydnc phenol such as bisphenol F, bisphenol A or a novolak resin, and advancement reaction products of such polyglycidyl ethers with dihydric alcohols or phenols.

Preferred materials having, on average, more than one acryloyloxy or methacryloyloxy group per molecule are polyacrylate and polymethacrylate esters of polyhydric alcohols, including esters of dihydric alcohols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, other polyoxyalkylene glycols, and adducts of ethylene oxide or propylene oxide with polyhydric phenols such as bisphenol F or bisphenol A; esters of trihydric alcohols such as glycerol, 1,1,1-trimethylolpropane, adducts of these alcohols with ethylene oxide or propylene oxide, and tris-2-hydroxyethyl isocyanurate; and esters of polyhydric alcohols having four or more hydroxyl groups such as erythritol, pentaerythritol, xylitol and sorbitol. Many of these polyacrylate and polymethacrylate esters are available commercially. Those whicil are not may be readily prepared by reacting the alcohol with acrylic or methacrylic acid or, more usually, an esterifying derivative thereof such as acryloyl chloride or methacryloyl chloride, using conventional procedures.

Especially preferred materials for use as are 2-hydroxyethyl methacrylate, tetrahydrofurfuryl acrylate, neopentyl glycol dimethacrylate, isobornyl acrylate, tripropyleneglycol diacrylate, tripropylene glycol dimethacrylate and mixtures of two or more thereof.

The amount of the photocurable acrylic component B) present in the composition according to the present invention may range from 1 to 95 but is preferably from 20 to 80 by weight, based on the weight of the total composition.

The relative proportions of components A) and B) are selected so that at the ambient temperature the composition of the invention is transparent to light and the components A) and B) aie partially mutually incompatible. Apart from control of the respective proportions of components A) and their mutual incompatibility can be influenced and controlled by varying their respective structures. For example, high olefin contents in copolymer A) leads to reduced compatibility .vith component B) at ambient temperature.

The composition according to the present invention may be prepared by hot-melt mixing of components and A film may then be cast from the hot-melt mixture and the film can either be used directly for the production of the laminates of the present invention, or the film can be removed and stored, in the absence of light, to be used for subsequent production of a laminate of the present invention.

In producing the laminates of the invention, the interlayer composition of the present invention is photocured by exposure to actinic radiation. To assist in the photocure the interlayer composition contains a photoimitiator for the photopolymerisation of acrylic groups. This can be any of the known initiators for the photopolymerisation of acrylic materials, used in a conventional amount, generally from 0.1 to 20 preferably 1 to by weight of the polymerisable acrylic material. Thus the photopolymerisation initiator may be an aromatic carbonyl compound, for example a benzoin, a benzoin alkyl ether such as the isopropyl or n-butyl ether, an alpha-substituted acetophenone, for S example a benzil ketal such as benzil dimethyl ketal, an alpha-haloacetophenone such as trichloromethyl p-tert.butylphenyl ketone, an alpha-aminoacetophenone such as dimethylaminomethyl phenyl ketone and morpholinomethyl phenyl ketone, a dialkyloxyacetophenone such as diethoxyacetophenone, or an alphahydroxyacetophenone such as 1-hydroxycyclohexylphenyl ketone or a benzophenone such as benzophenone itself and bis(4-dime'hylamino)benzophenone; a metallocene, for example a titanium metallocene such as bis(pi-methylcyclopentadienyl)bis-(sigma-pentafluorophenyl) titanium a Group IVA organometallic compound, for example a stannane such as trimethyl benzyl stannane, tributyl benzyl stannane or dibutyl dibenzyl stannane, together with a photoreducible dye, typically methylene blue or rose bengal, a quinone, such as anthraquinone or camphorquinone, together with an amine having hydrogen attached to an aliphatic alpha carbon atom, preferably a tertiary amine such as bis(4-dimethylamino)benzophenone and triethanolamine; a thioxanthone, for example an alkyl- or halogen-substituted thioxanthone such as 2-isopropylthioxanthone or 2-chlorothioxanthone; an acyl phosphine oxide; or a mixture of two or more thereof.

Preferably, the photopolymerisation initiator is an alpha-substituted acetophenone, a thioxanthone, a metallocene or v, mixture of two or more thereof. In particularly preferred embodiments, the initiator is a benzil dialkyl ketal or an alphahydroxyacetophenone. The interlayer composition, e.g. the film may also contain other additives conventionally included in adhesive compositions, for example polymerisation inhibitors such as hydroquinone and 2,6-di-tert.-butyl-4-methylphenol, adhesion promoters such as silanes, dyes or pigments, polymeric additives such as acrylatc polymers and copolymers, polyisobutylene, polyesters, polycarbonates, polyurethanes, polyvinyl formals and polyvinyl butyrals, and fillers such as silica flour or ground glass. Any filler used should r_ -6be sufficiently transparent to the radiation used that it does not prevent cure. Selection of a suitable filler is a routine matter for those skilled in the art of radiation polymerisation.

In order to produce a laminate according to the present invention, a film of the resin composition of the present invention is placed between adjacent substrates. Pressure is then applied to the assembly to remove any air from the resin film. Finally, the resin is bonded to the substrates by irradiating the assembly using a source of ultraviolet light.

Substrates which can be conveniently bonded in this manner include those composed of glass, polyvinyl chloride, polyethylene terephthalate, polycarbonate or polymethylmethacrylate.

In the laminates of the present invention, it is possible to use a substrate which is opaque to the polymerising radiation, provided that the irradiation is effected through a substrate which is transparent to the radiation. Using mixed opaque and transparent substrates, glass or plastics may be bonded to metals such as aluminium or steel, wood or other cellulosics, or ceramics.

Multi-layer structures may be constructed provided that the polymerising radiation is enabled to have a clear pathway to the resin to be polymerised.

One particularly useful embodiment of the present invention is the provision of a laminate comprising two or more glass panels, interleaved between adjacent panels, with a layer of a resin composition of the present invention. Upon irradiation, the cured interlayer forms a toughening zone in the laminate. Such laminated glass assemblies resist impact damage.

Thus, although the glass may shatter as a result of severe impact of an object upon it, the fragments of glass are not dispersed, rather they are retained by the effect of their strong bonding to the interlayer, so that the form of the assembly is broadly maintained.

Penetration of an object through the laminated assembly is also inhibited.

The following Examples further illustrate the present invention.

In the Examples, the following polymers are utilised.

I m I I Polymer I: A copolymer of ethylene and vinyl acetate containing 39-42 by weight of vinyl acetate and having a melt flow index of 48-66 dg/min and a ball and ring softening point of 104 0 C (ELVAX® 40 W of Du Pont).

Polymer II: A copolymer of ethylene and acrylic acid containing 20 of wheight of acrylic acid (Catalog No. 18, 104-8 of Aldrich Chemical Co).

Polymer III: A copolymer of ethylene and vinyl acetate containing 32.8 by weight of vinyl acetate and having a melt flow index of 440 dg/min and ball and ring softening point of 74 0 C (ELVAX 140 W of Du Pont).

Polymer IV: A carboxylic acid-containing terpolymer of ethylene, vinyl acetate and an unsaturated acid having a vinyl acetate content of 24-26 by weight a melt flow index of 420-580 dg/min and a ball and ring softening point of 83 0 C (ELVAX 4310 of Du Pont).

Example 1: Polymer I (200 2-hydroxyethyl methacrylate (150 g) and benzil dimethyl ketal (8 g) are heated to 130 0 C, mixed and poured out on to a glass panel measuring 200x200x3 mm. A second glass panel, of the same dimensions, is pressed on to the molten mass and excess of the mass allowed to escape until a uniform 1.5 mm interlayer is formed. On cooling the glass can be removed and the interlayer removed as a self supporting elastic material with a slightly moist feel. If this sheet of polymer is again placed between two pieces of glass it can be seen to wet the surface. Upon irradiation with a 5000 W metal halide lamp, for 2 minutes from a distance of 30 cm; a strong bond is formed.

Example 2: A piece of the 1.5 mm film produced in Example 1, after removing glass is cut to shape and placed between two pieces of unplasticised polyvinyl chloride, measuring 100x25x0.75 mm.

After irradiation for 1 minutes from a 5000 W metal halide lamp at a distance of 30 cm, a strong bond is formed and a force of 7 N/mm is required to pull the bond apart.

Example 3: The method and composition of Example 1 is repeated except that the glass panels are not separated. The laminate is irradiated with a 5000 W metal halide lamp from a distance of 30 cm, and the resulting substantially clear laminate is subjected to the following impact test. A 250 g steel ball is dropped from a height of 4.5 metres to impact j -8on the laminate. Although the glass shatters, all the fragments produced remain bonded to the polymer interlayer and the shape of the specimen remains substantially the same. The steel ball does not penetrate the laminate and, indeed, it requires 12 such impacts before penetration occurs. A piece of standard laminated glass, prepared by hotmelt bonding with plasticised polyvinyl butyral, is penetrated after only 8 impacts.

Example 4: The method of Example 1 is repeated except that a mixture of polymer I (200 tetrahydrofurfuryl acrylate (100 N-vinyl pyrrolidone (60 neopentyl glycol dimethacrylate (20 g) and benzil dimethyl ketal (8 g) is used. A piece of the resulting film is used to bond unplasticised polyvinyl chloride in the manner of Example 2. A pulling S force of 6.5 N/mm is required to separate the bond.

Example 5: A mixture of polymer I (2 2-hydroxyethyl methacrylate (1 2-ethylhexyl acrylate (0.5 g) and benzil dimethyl ketal (0.08 g) is prepared by melting the components together at 130°C. A film of 1 mm thickness is cast between two glass slides measuring 75x25x1 mm. On cooling to ambient temperature (21 0 the glass slides can easily be separated. If the film is placed between two fresh slides, wetting of the surface of the glass can be seen and, after irradiation from a distance of 1 cm, using a 4 W hand held UVlamp, a strong bond is formed and the glass slides can not be separated. On striking the laminate with a hammer, the glass shatters but all of the fragments are retained by the polymer layer, and the shape of the specimen is substantially retained.

Example 6: Example 5 is repeated but using a mixture of polymer I (2 2-hydroxyethyl methacrylate (0.75 tripropyleneglycol dimethacrylate (0.75 and benzil dimethyl ketal (0.08 The resulting clear laminate shows good retention of fragments, and retains its general shape when the glass is shattered by a hammer blow.

Example 7: Example 6 is repeated but using a mixture of polymer I (2 2-hydroxyethyl methacrylate (0.75 glycidyl methacrylate (0.75 g) and benzil dimethyl ketal (0.08 g).

The resulting clear laminate shows good retention of fragments and retains its general shape when the glass is shattered by a hammer blow.

Example 8: A piece of the film produced in Example 1 is used to bond a strip of UIBAK UB241 plasticised PVC, measuring 40x10x0.75 mm, to a piece of glass measuring 100x25x3 mm.

~IIU( I_ -9- After exposure to sunlight for 20 minutes a strong bond is formed such that the flexible PVC can be stretched to an extent of 100 with no loss of adhesion.

Example 9: Example 5 is repeated but using a mixture of Polymer I (1 Polymer II (1 g), 2-hydroxyethyl methacrylate (1.5 g) and benzil dimethyl ketal (0.08 The resulting clear laminate shows good retention of fragments and retains its general shape when the glass is shattered by a hammer blow.

Example 10: Example 2 is repeated but using a mixture of Polymer I (200 tripropylene glycol diacrylate (150 g) and 1-hydroxycyclohexyl phenyl ketone (8 A clear laminate is obtained which is tested for impact resistance with a single impact from a 250 g steel ball, from a height of 4.5 metres. Penetration is resisted, retention of glass fragments is excellent and the specimen retains its general shape.

Example 11: Example 2 is repeated but using a mixture of Polymer II (150 g), 2-hydroxyethyl methacrylate (150 isobornyl acrylate (40 g) and berizil dimethyl ketal (8 The resulting clear laminate resists impact in the manner indicated in previous Examples.

Example 12: Example 2 is repeated but using a mixture of Polymer IV (200 isobornyl acrylate (150 g) and benzil dimethyl ketal (8 The resulting clear laminate resists impact in the manner indicated in previous Examples.

Claims

1. A composition, suitable for use in bonding two or more substrates, at least one of which is permeable to ultra-violet radiation, comprising A) a film-foing copolymer of an olefin with a polar monomer, B) a photopolymerizable acrylic ~onomev; and C) a photoinitiator for photo-polymerization of acrylic groups,the total composition, while transparent to light, exhibiting partial incompatibility between the components A) and B).

2. A composition according to claim 1 wherein copolymer A) is formed from a Cz-C 4 straight- or branched olefin and a polar monomer. S

3. A composition according to claim 2 wherein the olefin is ethylene.

4. A composition according to claim 1 wherein the polar monomer is viny, acetate or acrylic acid or an alkyl ester of acrylic acid.

A composition according to claim 1 wherein the ratio of olefin to polar monomer in o copolymer A) ranges from 95/5 to 20/80 by weight.

6. A composition according to claim 1 wherein the copolymer A) is an ethylene/vinyl acetate copolymer, an ethylene/ethyl acrylate copolymer or a terpolymer of ethylene, vinyl acetate and acrylic acid,

7. A composition according to claim 1 wherein the photod ,itaterial B) is a monoacrylic material containing one acryloyloxy or methacryloyloxy group together with a hydroxy or carboxyl group; a material containing, on average, more than one acryloyloxy or methacryloyloxy group per molecule; or a mixture of two or more thereof,

8. A composition according to claim 7 wherein the monoacrylic material B) is a hydroxyalkyl acrylate or hydroxyalkyl methacrylate; a carboxyalkyl acrylate or carboxyalkyl methacrylate; or a carboxy group-containing adduct of a hydroxyalkyl acrylate or hydroxyalkyl methacrylate wih a pol carboxylic acid anhydride.

9. A composition according to claim 8 wherein the hydroxyalkyl acrylate or hydroxyalkyl methacrylate is 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl nacrylate or 4-hydroxybutyl acrylate, or the corresponding methacrylates or mixtures of two 1 11111~- 1~; -11 or more thereof.

A composition according to claim 8 wherein the carboxyalkyl acrylate or carboxyalkyl methacrylate is 2-carboxyethyl acrylate or 2-carboxy-2-methylethyl methacrylate.

11. A composition according to claim 8 wherein the polycarboxylic acid anhydride is maleic anhydride, succin.c anhydride, tetrahydrophthalic anhydride or hexahydrophthalic anhydride.

12. A composition according to claim 7 wherein the material having, on average, more than one acryloyloxy or methacryloyloxy group per molecule is a polyacrylate or polymethacrylate ester of a polyhydric alcohol. S

13. A composition according to an:y the preceding claims wherein the amount of each of the components A) and B) in the composition ranges from 1 to 95 by weight, based on the weight of the total composition.

14. A composition according to claim 1 wherein the photoinitiator for photo-poly- merisation of acrylic groups is present in amount of 0.1 to 20 by weight, based on the weight of the polymerisable acrylic material.

A composition according to claim 1 wherein the photoinitiator is an alpha-substituted acetophenone, a thioxanthone, a metallocene or a mixture of two or more thereof.

16. A laminate comprising two or more substrates and, interposed between the substrates, or between adjacent pairs of substrates, a composition according to claim 1.

17. A laminate according to claim 16 wherein the substrates are of glass, polyvinylchloride, poly(ethylene terephthalate), polycarbonate or poly(methylmethacrylate).

18. A laminate according to claim 16 wherein mixed UV-opaque and UV-transparent substrates are used.

19, A laminate according to claim 16 wherein the substrates are two or more panels of s glass.

I 12- A laminate comprising two o' ,ore substrates and, interposed between the substrates, or between adjacent pairs of substrates, a composition according to claim 1, photo- polymerized by irradiation with UV light.

21. A composition, suitable for use in bonding two or more substrates, at least one of which is permeable to ultra-violet radiation substantially as hereinbefore described with reference to any one of the Examples.

22. A method of bonding two or more substrates at least one of which is permeable to ultra-violet radiation, which method comprises placing a layer of a composition according to any one of claims 1 to 15 or 2,1 between said substrates and exposing said substrates and composition to ultra-violet radiation, DATED this TWENTY-SIXTH day of FEBRUARY 1991 Clba-Geigy AG Patent Attorneys for the Applicant SPRUSON FERGUSON ~iAL?~