WO1991008240A1

WO1991008240A1 - Silane modified resin

Info

Publication number: WO1991008240A1
Application number: PCT/GB1990/001865
Authority: WO
Inventors: Leslie Phillip Martin; Michael Edward Slevin; Colin Beveridge
Original assignee: Swift Adhesives Limited; Aei Cables Limited
Priority date: 1989-11-29
Filing date: 1990-11-29
Publication date: 1991-06-13
Also published as: GB9209552D0; GB2256432A; GB8927003D0; GB2256432B

Abstract

Silane-modified tackifier resins and tack modifying waxes are disclosed. The compounds are particularly useful in the formulation of adhesive compositions, especially hot melt adhesive compositions.

Description

Silane modified resin

The present invention relates to silane- modified, cross-linkable resins and waxes, to processes for their production, to their use for example in adhesive compositions and to materials comprising such resins cross-linked to each other or to other compatible substances.

Silane modified medium to high molecular weight homo- and copolymers are widely used for the preparation of cable jacketing, wire insulation and piping and have been suggested for use as spacers in laminate materials and more recently as the basis for sealants and for adhesive compositions, in particular hot melt and pressure sensitive adhesives.

In all these applications, the cross-linked polymers provide the overall structural matrix for the cured compositions.

Such cross-linked matrices can of course hold other components of the uncured compositions, such as fillers colorants, plasticizers, etc and indeed the use in coating or adhesive compositions based on silane modified homo- or copolymers of fillers, colorants and plasticizers which contain groups which condense with silanols has also been suggested in International Patent Application No PCT/GB89/00534 where it is explained that such materials may thereby be bound more intimately into the cross-linked matrix of the cured compositions. The properties of an adhesive or sealant composition depend upon the contributions made by its various components. A pressure sensitive adhesive composition for example will comprise a relatively high molecular weight elastomer or rubbery polymer together with a low molecular weight tackifier resin - the elastomer providing an elastic matrix for the viscous, adhesion-effecting resin. Tack modifying waxes by contrast serve to reduce the tack of adhesive or sealant compositions. Thus by appropriate choice of components such as the medium to high molecular weight " atrix- forming" polymer, the tackifier resin and the tack modifier wax the desired performance profiles of an adhesive composition in form in which it is applied and the form which it adopts after application, e.g. after drying, cooling or curing, may be selected, e.g. in terms of wetting, strength, adhesion, flexibility, temperature resistance etc.

As mentioned above, the use of cross-linkable silane modified polymers as the matrix forming polymers in adhesive and sealant compositions is known, e.g. from GB-A-2197326.

It has however now been recognized that silane modification of the low molecular weight tack controlling components, i.e. the use of silane-modified, cross-linkable tackifier resins or tack modifier waxes, in particular the use of silane modified tackifier resins, offers a particularly useful option in the design of cross-linkable adhesive compositions, sealant compositions, and the like.

Thus in one aspect the invention provides a silane- modified tackifier resin containing at least two silanol or protected silanol groups in the resin molecule. In a further aspect the invention also provides a silane- modified tack modifying wax containing at least two silanol or protected silanol groups in the wax molecule. By silane-modified it is meant that the resin or wax has a molecular structure incorporating silane groups, e.g. as a result of silane grafting of a silane- free resin or wax.

The silane-modified tackifier resins of the invention may conveniently be silane group carrying analogues of conventional tackifier resins, such as those described in for example Chapter 16 of the "Handbook of Pressure-sensitive adhesive technology", "Tackifier resins" by J.A. Schlademan, (Van Nostrand Reinhoid, 1982) .

Tackifier resins generally fall into two categories, those based on rosins and rosin derivatives and those based on hydrocarbon resins. The second category itself includes aliphatic, aromatic and diene resins as well as mixed hydrocarbon resins and, for the purposes of sealant and hot melt and pressure sensitive adhesive formulation, the polyterpene, aliphatic and styrenic resins are of particular interest due to their lack of acidic or hydroxyl groups which might give rise to premature reactions. Rosin derivative and terpene- phenolic resins are also of particular interest in this regard and other tackifier resins, such as the coumarone-indene resins, are of interest in connection with the manufacture of solvent based adhesives or for use in moulding compositions for example for tyre manufacture. The rosin and rosin derivatives which may be silane modified according to the invention are materials which are generally derived from pine trees. Chemically they are abietic or pimaric type acids (e.g. abietic, neoabietic, palustric, dihydroabietic, dehydroabietic, pimaric and isopimaric acids) or derivatives thereof, e.g. esters, condensation or polymerization products, disproportionation products, and hydrogenation products thereof, such as glycerol, ethylene glycol, diethylene glycol, methanol or pentaerythritol esters or phenol or maleic anhydride condensation products, etc.

The hydrocarbon resin tackifying resins which may be silane modified according to the invention include in particular the C-5, C-9 and (C-5)₂ resins, i.e. those based on monomer units containing on average 5,9 or (5x2) carbons; these are generally produced by polymerization of crude monomers obtained from wood, coal or petroleum. Indene, styrene, methylindenes, ethylstyrenes, piperylenes, isoprene, 2-methylbut-2- ene, dicyclopentadiene, methyldicyclopentadienes, pinenes and dipentene are particularly commonly used monomers. The hydrocarbon resins may also be modified, e.g. hydrogenated, alkylated, phenol-modified, acid modified, etc, as is conventional in the field of tackifier resins.

The tackifier resins suitable for silane modification according to the invention and the silane modified resins according to the invention preferably are liquid at ambient temperature or have relatively low softening points, for example of 5-190°F (-15 to 88"C), especially 10-150°F (-12 to 66"C) particularly 40-135°F (4 to 57°C). The resins conveniently have relatively low molecular weights, thus for example the resins which are silane modifiable according to the invention conveniently have number average molecular weights of about 250-2500, especially 300-2000, particularly 400 to 1500, more particularly 500 to 1100. Many tackifier resins are available commercially and can be silane modified according to the invention. In this regard particularly mention may be made of Escorez 5380 (a hydrocarbon resin available from Exxon) , Unitack R100 (a rosin ester available from Union Camp Corp.), Dertophene T (a terpene phenolic resin available from DRT) , Krystalex F100 and FR75 (α-methyl styrene polymers available from Hercules, Inc.), Piccotex 120 (a vinyl-toluene/α-methyl styrene modified hydrocarbon resin available from Hercules, Inc.), Staybelite (a hydrogenated rosin available from Hercules, Inc.), and Nirez 1085 (a terpene resin available from Reichhold Chemicals) .

As mentioned earlier, although the invention is primarily directed at the silane modification of tackifying resin it does more generally relate to both tack enhancing and tack suppressing components, i.e. to tack modifying waxes as well as to tackifier resins. The tack modifying waxes which can be silane modified according to the invention are generally long chain aliphatic hydrocarbons with no side chains or with relatively short side chains. They are crystalline, low molecular weight materials although the degree of crystalinity can vary. The waxes suitable for silane modification according to the present invention are particularly preferably low molecular weight waxes such as paraffin waxes, microcrystalline waxes and Fischer- Tropsch waxes and, less preferably, higher molecular weight waxes such as polywaxes and A-C polythenes. In general, the waxes silane modified according to the invention will have number average molecular weights of 300-2000, preferably 300-1000, especially 350-800. The waxes suitable for silane modification will generally have melting points above ambient temperature, e.g. above 90°F (32^βC), preferably of 110-230°F (43 to 110°C), particularly of 120-190^βF (49 to 88"C) .

Many waxes are available commercially and may be silane modified according to the invention. In this regard, particular mention may be made of paraffin wax 150/155"F (66/68^βC) and microcrystalline wax 175"F (79°C) (both available from Astor Chemicals), Fischer Tropsch waxes (available from Sasol) , AC6 polythenes (available from Allied Colloids), and Polywax 2000 (available from Baseco) .

The silane groups may be present in a monomer which is (co)polymerized to produce the silane modified resins or waxes of the invention or alternatively the silane modification of the tackifier resins or tack modifying waxes to produce the silane modified resins and waxes according to the invention may be performed analogously to the conventional silane grafting of higher molecular weight, matrix-forming polymers, e.g. as described in US-A-3646155, GB-A-1286460, GB-A-1347426, GB-A-1406680, GB-A-1450934 and GB-A-1542543. Thus silane grafting may be effected by reaction of the unmodified resin or wax with an unsaturated silane, e.g. vinyl triethoxysilane, in the presence of a catalyst, e.g. a peroxide initiator, to produce a silane modified resin or wax respectively. Generally, the silane group introduced in this way will be a protected silanol group which can be deprotected by hydrolysis enabling it to engage in a catalysed silanol condensation (cross-linking) reaction with other silanol groups or with other groups reactive with silanols, e.g. alcohol, thiol or amine groups.

Expressed in general terms therefore the silane modified resins and waxes according to the invention may be represented by formula I

where R is the residue of the unmodified resin or wax; n is an integer of at least 2, preferably 2-10, especially 2-8; A is a bond or a divalent linking group, e.g. an optionally substituted divalent organic radical such as an alkylene, alkyleneoxy, alkylenephenylene or alkyleneoxyalkylene group; Y is a blocking group not displaceable by hydrolysis, e.g. a G,.₄ alkyl group; m is 1,2 or 3, preferably 2 or 3; and X is a leaving group displaceable by hydrolysis, conveniently a halogen atom (e.g. chlorine) or a group ZO or ZCOO where Z is a C_,_₁₀, preferably C_,_₄, alkyl or alkoxyalkyl group.

Thus in a further aspect the invention provides a process for the preparation of silane modified resins or waxes according to the invention, said process comprising reacting a tackifier resin or tack modifier wax with an unsaturated silane of formula II

A'-Si(Y)₃__m(X)_m (II)

(where R,n,m,X and Y are as defined above and A¹ is an ethylenically unsaturated organic group corresponding to the divalent group A defined above) in the presence of a catalyst, e.g. a peroxide catalyst, for example using the reagents and conditions specified in the literature. The process of the invention may be represented by the general scheme

R(H)_n + n A'Si(Y)₃__ra(X)_m -R(A-Si(Y₃--₁)(X)_n)_n.

In formula II, A' conveniently represents a group of formula

CH₂ = C - (Y³)_p- Y²

where p is 0 or 1; Y² represents hydrogen or C_α_₄ alkyl; and Y³ represents a C^^ straight, branched or cyclic alkylene group, a phenylene group, a carbonyloxy group, a carbonyloxy (C_x.₁₀ alkylene) group, a

alkylene) carbonyloxy group or a (C_x_₁₀ alkylene) carbonyloxy (C_J._K, alkylene) group, optionally carrying pendant glycidoxy groups.

Such compounds are described by Dart Industries in GB-A-1347426.

Particularly preferably however A¹ represents a C₂_₅ monoalkenyl group, such as vinyl or allyl, or a (C₂_₃ alkenyl)carbonyloxy(C₂_₃ alkylene) group, such as a gamma-methacryloxypropyl group, and particularly preferred unsaturated silanes of formula II include vinyl trimethoxy silane, vinyl triethoxy silane and gamma-methacryloxypropyltrimethoxy silane. Unsaturated silanes of formula II are known or may be prepared by conventional methods.

Since the unmodified resins and waxes are of relatively low molecular weight, the silane side chains may constitute a relatively high proportion by weight of the silane modified resin or wax, e.g. 5 to 90%, generally 10 to 60%, preferably 20 to 50% and especially preferably 30 to 40%, and the ratio of unsaturated silane to resin or wax used in the grafting reaction, or alternatively the weight ratio of monomers where copolymerisation is used, should be chosen accordingly. In any event, the ratio of silane to wax or resin will be selected to ensure that an average at least 2, preferably 2-8, especially 3-5, silane groups are introduced per resin or wax molecule.

The catalyst used in the preparation of the silane grafted resins or waxes is preferably a free-radical generating compound such as for example benzoyl peroxide, dicumyl peroxide or other catalysts referred to in the literature, e.g. in US-A-3646155. The free radical generator may conveniently be used in a concentration of about 0.01 to 3% relative to the weight of resin or wax used.

The silane grafting reaction is conveniently effected at a temperature of at least 140°C, preferably between 150"C and 250°C, and may be performed in conventional apparatus such as a Ko-Kneader. A third method of producing the silane modified resins and waxes may be appropriate when the resin or wax contains groups or atoms which will prevent the conventional grafting reaction from working effectively, for example the acid groups in terpene phenolic or rosin derivative resins. This method will involve the use of an aminosilane of general formula III

H₂NA²Si(Y)3-_m(X)_m (III)

wherein A² is an optionally substituted divalent organic radical as defined above for A, and Y,X and m are as defined above. Reaction with amines of formula III will introduce silane side chains of formula

-NH-A²-Si(Y)₃__m(X)_m

If desired, such silane-amine grafted products can subsequently be further grafted using the conventional peroxide catalysed reaction scheme.

The novel silane modified cross-linkable resins and waxes according to the invention may be used in moulding, adhesive, coating and sealant compositions and the like compositions where tackifier resins and/or tack modifying waxes are conventionally used. In such compositions, the silane modified resins and waxes may wholly or particially replace unmodified resins or waxes. Preferably such compositions, where they contain tackifier resins and tack modifying waxes should contain silane modified resins and waxes according to the invention.

Besides performing as tack controlling agents in the uncured compositions, the silane modified waxes and, more particularly the silane modified resins may function as cross-linking agents for other materials, e.g. for the matrix forming polymer of such compositions. All that is required is that the matrix forming polymer should carry groups reactive with silanols, e.g. hydroxy, isocyanate, a ine, thiol and silanol (or more generally protected silanol) groups.

Cross-linking of the compositions occurs when the silane groups are hydrolysed, e.g. as follows:

/Vγ matrix forming A v\

OH polymer OH

Si(OCH₃)₃ H₂0 Si(OH)₃

R silane modified R

I tackifier resin |

Si(0CH₃)₃ Si(OH)₃

OH OH

polymer Stable Reactive

o i /°-

Si silanol | \ condensation R catalyst | /

Si l ^\ ₀.

O ^ W

Cross linked-product

The materials which the silane modified resins and waxes of the invention can serve to cross-link can be any of a wide range of natural or synthetic polymers or macromolecules which contain or have been modified to introduce groups (hereinafter "reactive groups") which condense with silanols.

While particular mention should be made of silane modified polymers (such as for example those referred to in GB-A-2197326, PCT/GB89/00533, PCT/GB89/00536, PCT/GB89/00535, EP-A-240044, JP-A-59102931, JP-A- 58132032 and British Patent Application No. 8924619.3, and the documents mentioned therein) , materials containing reactive groups other than silanes may advantageously be cross-linked using the silane modified resins and waxes of the invention. Thus for example hydroxyl reactive groups occur on a variety of polymers , and macromolecules such as polyvinyl alcohol, polyvinyl acetate, polysaccharides, starch, cellulose and derivatives thereof and hydroxyl groups may conveniently be introduced onto hydroxyl group free polymers or macromolecules by conventional grafting or copolymerization techniques. Other materials which may be cross-linked by the silane modified cross-linking agents of the invention include isocyanate, amine, carboxylic acid, halogen and thiol group containing materials, e.g. polyisocyanates, acid modified polymers or rubbers (such as the aleic anhydride modified SEBS available from Shell Chemical Co. under the trade name Kraton FG1901X or maleic anhydride modified ethylene- acrylic acid or ethylene-vinyl acetate copolymers available from Cdf - Chemie) , polyamines such as polyallylamine or polylysine, polyvinyl chloride, polychloroprene and possibly also polyesters and polyamides.

Polymers having a wide range of molecular weights may be silane grafted to produce matrix forming polymers for the preparation of the compositions of the present invention; in general polymers having melt flow indices (MFIs) of forming 1 to 2800 may be used and MFIs of 2- 1000, especially 5-800 and particularly 150-800, are preferred. Where the matrix forming polymer is formed by silane grafting a polar copolymer, e.g. ethylene vinyl acetate, ethylene methyl acrylate, ethylene butyl acrylate or ethylene acrylic acid, the polar comonomer content is preferably 14-40%, especially 18-33%. By blending polymers having different pre-silane grafting MFIs and indeed by blending grafted polymers having different monomer make-up the performance profile of the final composition, for example in terms of wetting, strength, adhesion, flexibility, and ease of application, may be adjusted to suit its intended end use.

The matrix forming polymer component preferably forms up to 90%, conveniently 10-40%, and especially preferably about 30%, of the composition.

The silane modified resin or wax cross-linking agents according to the invention may be formulated in preprepared cross-linkable compositions, e.g. moulding, sealant, adhesive or coating compositions, or they may be added to materials which are to be crosslinked.

Thus viewed from a further aspect, the present invention provides a cross-linkable composition comprising: a reactive group-containing polymer or macromolecule; a silane modified resin according to the invention and/or a silane modified wax according to the invention; and, optionally packaged separately from said resin or wax, a silanol condensation catalyst.

In one preferred embodiment, the composition of the invention is a one-part composition containing both the silane modified component(s) and the silanol condensation catalyst mixed in together. In this event, the composition of the invention is preferably packaged in a water-tight container, preferably together with a desiccant, e.g silica gel. In another preferred embodiment the composition of the invention is in the form of a multipart (e.g. 2 part) system with the condensation catalyst packaged separately from the silane modified component(s) , the different parts of the composition being brought together when cross-linking of the overall composition is desired.

In the cross-linking of the compositions of the invention the hydrolysis of the silane groups and the subsequent cross-linking by reaction with other reactive groups is catalysed by the condensation catalyst. Many such materials are known to the art. Thus suitable catalysts include, for example, metal carboxylates, e.g. dibutyl tin dilaurate, organometallics, e.g. tetrabutyl titanate, organic bases, e.g. ethylamine, and mineral and fatty acids. Several such compounds are identified in for example US-A-3646155. Among suitable , condensation catalysts, organotin compounds, such as dibutyl tin dilaurate are preferred. The catalyst, conveniently makes up from 0.005-0.2%, preferably about 0.02%, of the composition as a whole (excluding volatile solvents) .

The nature and content of any further components in the compositions of the invention will depend upon the intended end use of the composition. Thus for example where the composition is to be used as a hot melt adhesive it may contain conventional hot melt adhesive components (such an antioxidants, diluents, fillers, colorants, and conventional tack and viscosity modifiers) in conventional or near conventional concentrations. Further discussion herein of compositions according to the invention will for the most part be in respect of sealant and adhesive compositions: it is however to be understood that the compositions of the invention may take other forms, e.g. coating or moulding compositions, and in these forms may contain components conventional to such forms in concentrations conventional or near conventional to such forms.

Where such components themselves contain reactive groups, curing of the composition will lock the components into the cross-linked structure so preventing them from bleeding out under the influence of heat, solvents, weather etc.

Where the compositions of the invention are to be bonded to substrates, e.g. as is the case with sealants, adhesives and coating compositions, the silane groups in the composition components, e.g. waxes, resins or matrix forming polymers, will enhance binding of the cured compositions to many surfaces, especially metal or glass surfaces.

Where an adhesive composition according to the invention is to be solvent based it will have the advantage of cross linking at room temperature while nonetheless being a one part formulation. Conventional solvent based adhesives are either cured by heating or must be two part formulations using a chemical curing process. The solvent based adhesive compositions according to the present invention have significant advantages in terms of convenience of application and curing.

As suitable solvents particular mention may be made of aromatic and aliphatic hydrocarbons, chlorinated hydrocarbons, nitroparaffins, and oxygenated solvents such as ketones and esters, e.g. hexane, toluene, methyl ethyl ketone, acetone or (for flammable adhesives) methylene chloride or mixtures thereof. Solvent based adhesives may conveniently contain tackifier resins as up to 90% of the total solids content, plasticisers (up to 80% of solids) , fillers (up to 80% of solids) and colourants and stabilisers (generally not more than 10% of solids) . The total level of solids in the solvent can conveniently range from about 10% for a sprayable adhesive to about 95% in sealants.

Where the composition of the invention is a hot melt adhesive composition it will preferably contain a silane modified tackifier resin but it may also contain an unmodified tackifer resin, for example a resin or resin mixture conventional for hot melt adhesives. The unmodified resin or resin mixture should however be selected to achieve the desired balance between compatibility with the silane modified component(s) and the other components of the adhesive, the melt flow properties of the adhesive as a whole and the specific adhesion to the substrates intended to be bonded with the adhesive. In this respect, suitable non silane modified tackifying resins may include: aromatic modified resins such as α-methyl styrene homopolymers or copolymers, e.g. Krystalex F100 (α-methyl styrene polymer) , Krystalex FR75 (a modified α-methyl styrene copolymer) or Piccotex ( a vinyl toluene-α-methyl styrene copolymer) , all three available from Hercules Chemical Co.; aliphatic petroleum hydrocarbon resins; styrene-modified hydrocarbon resins; and, particularly preferably, alicyclic hydrocarbon resins, e.g. Escorez 5300 (available from Exxon) .

The tackifier resin will conveniently make up from 5 to 40% by weight, prefrably 10-40%, and especially preferably about 30-35%, of the adhesive, preferably with 10 to 100%, especially 50 to 100% being silane modified tackifier resin.

Hot melt adhesive compositions according to the invention preferably contain at least one antioxidant. In this respect, conventional adhesives antioxidants, such as butylated hydroxytoluene (BHT) may be used. A preferred antioxidant is pentaerythritol-tetrakis-3- (3,5-di-tert.butyl-4-hydroxyphenyl)-propionate, which is available under the trade name Irganox 1010 from Ciba- Geigy UK Ltd. of Manchester. The antioxidant will generally be present in the adhesive at about 0.1-2.5% by weight, preferably 0.5-1%.

Adhesive compositions according to the invention preferably also comprise a further polymer or polymer mixture besides the matrix forming polymer which contains the reactive groups. The further polymer or polymer mixture will be selected to achieve, inter alia, a balance between compatibility with the catalyst and the other components of the adhesive and the viscosity and tack characteristics of the adhesive. Where the matrix forming polymer is based on a (co)polymer deriving from polar (co)monomers, the further polymers are preferably selected from compatible (co) olymers also deriving from polar (co)monomers, e.g. ethylene copolymers such as EVA, ethylene-methy1 acrylate (EMA) , ethylene-ethyl acrylate (EEA) and ethylene butyl acrylate (EBA) , conveniently copolymers having polar comonomer residue contents of 12-40%, preferably 18-35% and especially preferably about 28% and MFIs of 1 to 2800, conveniently 5-800, preferably 20-500 and most preferably 150-400. Where the matrix forming polymer is based on a polymer deriving from apolar monomers, the further polymers are preferably selected from homo- and copolymers of apolar monomers, such as for example polyethylene, polypropylene, polybutylene, and SEBS (for example low crystallinity range molecular weight homo-or copolymers, such as that available under the trade name Vestoplast 608 from Hύls (UK) Limited of Manchester, or low molecular weight polyethylene, such as polyethylene AC6 or AC8 available from Allied Cheical Corporation International NV SA of Birmingham) . Conveniently polymers having MFIs of 1 to 2800, particularly 5-800, preferably 20-500 and most preferably 150-400 are used. The further polymer conveninetly constitutes up to 15%, preferably 1 to 10%, and especially preferably about 5%, of the adhesive of the invention and generally will be present at about half the concentration of the matrix forming polymer.

Adhesive compositions according to the invention may contain components such as diluents or modifiers, conveniently as about 5-40%, preferably about 30%, of the total adhesive. These components may serve to regulate the viscosity and setting speed of the adhesive and may be included to enhance the wieking of the adhesive into the substrates to be bonded. In this respect, the use as diluents of silane modified waxes according to the invention is preferred although conventional unmodified waxes (e.g. petroleum waxes such as paraffin waxes or microcrystalline waxes such as Okerin 8981 from Astor Chemicals of West Drayton, Middlesex, low molecular weight polyethylene, and synthetic waxes, such as Fischer-Tropsch waxes) may be used.

Where waxes are used as diluents, they should conveniently have softening temperatures in the range of 50-120°C. Of the unmodified waxes, microcrystalline waxes, Fischer-Tropsch waxes and paraffin waxes having softening temperatures in the ranges of 65 to 94°C (e.g. 79°C), 110 to 120°C and 54 to 72°C respectively, and mixtures of low molecular weight polyethylene (such as polyethylene AC6 or AC8) and a microcrystalline wax having a softening temperature of about 90°C (such as Micro 549 available from Holmes Chemical Company of Uxbridge) are particularly suitable.

Where the adhesive is formulated as a two part system, the silane modified component(s) and the catalyst being separately packaged, the other components can appear in one or both of the separate componsitions; the silane modified component containing compositions will however preferably contain the matrix forming polymer and any unmodified or modified tackifier resin and an antioxidant and the catalyst-containing composition will preferably contain a further polymer; the plasticizers and other unmodified diluents etc. may be in either or both compositions. In a two composition system, the catalyst containing composition particularly conveniently comprises about 99% of a polymer compatible with the matrix forming polymer (e.g. EVA, EMA, EEA, EBA, polyethylene, polypropylene or SEBS) and 1% of acatalyst (e.g. dibutyl tin dilaurate) .

Where the adhesive of the invention is formulated as a single composition it will advantageously be packaged in water-tight containers, for example aluminium cartridges, which containers advantageously will also include a desiccant, for example a sachet of silica gel at the end of a cartridge for a hot melt adhesive applicator.

Besides the components discussed above, it may be desirable to incorporate into the compositions of the invention a colouring agent, for example a whitener such as titanium dioxide. For hot melt adhesive compositions such colouring agents are particularly readily dispersed within the adhesive if introduced as solid dispersions in an polymer compatible with the matrix forming polymer.

In use, the hot melt adhesive compositions according to the present invention will be heated to melting, generally to 100-200°C preferably about 110- 170^βC, mixed (e.g. in a cartridge loaded applicator or by the mixing in a mixer head of the two compositions of a two composition system) and applied to the substrates to be bonded, generally in a film thickness up to about 3mm, preferably up to about 1mm, although this can be achieved by applying a larger amount and scraping off the excess. The adhesive characteristics of the system should be sufficient to maintain a bond between the substrates while cross-lkinking occurs.

For the hydrolysis of the silane modified component(s) in the compositions of the invention, water is required. In general, the necessary water can be supplied by ambient moisture. However, if desired, the composition may contain further components which gradually release moisture into the system, for example fillers with surface-bound moisture or moisture filled polymer microspheres such as those sold as paint opacifiers by Rohm and Haas Company under the trade name ROPAQUE OP-62 (see EP-A-119054 of Rohm and Haas) .

Hot melt adhesive compositions according to the invention may be used in most applications where hot melt adhesives have been used and where full bonding strength is not required immediately after the application of the adhesive. The adhesive compositions of the invention are thus particularly suited to use in product assembly (for example in the furniture and automobile industries) , packaging and labelling.

As mentioned above, because of the silane cross- linking reaction, the compositions of the invention are capable of chemically bonding to the surfaces of many substrates. Thus the compositions of the present invention are particularly suitable for bonding to or coating of cellulosic and silicaceous substrates, for example paper and glass.

By the use according to the invention of silane modified tackifier resins and/or tack modifying waxes capable of reacting with reactive groups on the matrix forming polymer it may also be possible to produce compositions, especially moulding, jacketting or insulating compositions, which may be processed at lower temperatures than would be possible using unmodified resins or waxes. This is of particular interest for compositions which also contain moisture releasing components as by the use of lower processing temperatures premature moisture release can be reduced.

The silane modified and catalyst components in the compositions of the present invention may be selected to achieve particular desired characteristics, for example rate or controlability of curing, and by varying the monomer make-up and the MFI of the matrix forming polymer, and by utilizing blends of polymers the formulation characteristics (such as viscosity, softening point, wetting ability, etc.), for the compositions may be controlled to give a readily processable material.

As mentioned above, the silane modified waxes and resins according to the invention may be used in moulding compositions and thus in a yet still further aspect the invention also provides cross-linked, e.g. cured, silane modified resins and waxes or compositions thereof and articles made therefrom.

The following Examples are provided to illustrate the present invention further without limiting the scope of protection sought therefor (all percentages and parts referred to herein are by weight unless otherwise specified) :

Example 1

Silane modified tackifier resins

Silane grafting of the tackifier resins listed in Table I below is performed by reacting 100 parts by weight of the resin with up to 100 parts by weight of vinyl trimethoxy silane (to achieve a resin: silane molar ratio of 1:2) and using 7 parts by weight of dicumyl peroxide as the free radical generator. 0.5 parts by weight of Flectol H (available from Monsanto) may be added in as an antioxidant and the reaction may be effected in heated vessel provided with a stirrer.

TABLE I

Resin Type Source

Escorez 5380 hydrocarbon Exxon Unitack R100 rosin ester Union Camp Corp Dertophene T terpene phenolic DRT Piccotex 120 α-methylstyrene- vinyl toluene Hercules Inc

Nirez 1085 terpene Reichhold Chemicals Staybelite hydrogenated rosin Hercules Inc

Example 2

Silane modified tack modifying waxes

Silane grafting of the waxes listed in Table II below is effected analogously to Example 1

TABLE II

Wax Source

Paraffin wax 150/155 Astor Microcrystalline wax 175 Astor Fischer-Tropsch wax Sasol

Example 3

Hot melt packaging adhesive

Hot melt packaging adhesives are prepared having the following formulations (the tabulated figures are parts by weight) :

TABLE III

Component Formulation

30 30' 30 30^J 30^**

20⁷ 25^c 30⁸ 0 30^e

10^s - 10 11

0 30 0

20 l-i 15 15 0 30 13 14 20

10 12 15 16 30 17 0 10 18

1. 7 1.7 1. 7 1.7 1. 7

1. Silane grafted 28-400 ethylene vinyl acetate (EVA)

2. Silane grafted 18-800 ethylene butyl acrylate (EBA)

3. Silane grafted 24-150 ethylene methyl acrylate (EMA)

4. Silane grafted 33-800 EVA

5. Silane grafted 28-400 EBA

6. Silane grafted Escorez 5380 (Example 1)

7. Silane grafted Unitack R100 (Example 1)

8. Silane grafted Dertophene T (Example 1)

9. Unitack R100

10. Dertophene T

11. Escorez 5380

12. Paraffin wax 150/155

13. Silane grafted paraffin wax 150/155 (Example 2)

14. Silane grafted microcrystalline wax 175 (Example 2)

15. Silane grafted Fischer-Tropsch wax (Example 2)

16. 1:1 mixture of microcrystalline wax 175 and Fischer Tropsch wax

17. Microcrystalline wax 175

18. Fischer-Tropsch wax 19. 1% dibutyl tin dilaurate in 28-800 EVA

The silane grafted matrix forming polymers are reaction products of vinyl trimethoxy silane and unmodified polymer prepared with a silane content of about 2-3% using the procedure described in British Patent Application No. 8924619.3 or that of US-A- 3646155.

Example 4

Two part hot melt packaging adhesive

Two part hot melt adhesives are prepared having the following formulations:

Part 1

50 parts by weight of silane grafted matrix forming polymer (EVA, EMA or EBA as used in Example 3 or 24-400 ethylene acrylic acid (EAA) silane grafted in an analogous fashion)

50 parts by weight tackifier resin (silane grafted

Escorez 5380, Dertophene T or Unitack R100 as in Example 1) or, where the matrix forming polymer is silane grafted EBA, of ungrafted Escorez 5380 (or Dertophene T or Unitack R100) )

Part 2

100 parts by weight of silane grafted wax

(microcrystalline wax, paraffin wax or Fischer- Tropsch wax as in Example 2) _r 8 parts catalyst (1% dibutyl tin dilaurate in 28-800 EVA)

Parts one and two are mixed at a temperature of 110 to 160°, preferably 140-160°C.

The hot melt adhesive compositions of Examples 3 and 4 may conveniently contain other additives such as polywaxes, AC polythenes, plasticizers, antioxidants, colorants and fillers, e.g in the following percentages by weight relative to the total of the components already specified:

Antioxidant (Irganox 1010) 1%

Plasticizer (Hyvis 30) 30%

Filler (China clay or 10% polyethylene glycol

PEG 8000)

Polywax (Polywax 2000) 10%

AC Polythene (AC6) 10%

Example 5

Pressure sensitive adhesive compositions

Pressure sensitive adhesive compositions are prepared having the following formulations:

TABLE IV Component Formulation

1. Silane grafted Kraton 1102 (SBS)

2. Silane grafted Kraton 1107 (SIS)

3. Silane grafted Kraton 1652 (SEBS)

4. Silane grafted Stereon (Firestone 840)

5. Silane grafted Escorez 5380 (Example 1)

6. Silane grafted Unitack R100 (Example 1)

7. Silane grafted Dertophene T (Example 1)

8. Silane grafted Piccotex 120 (Example 1)

9. Piccotex 120

10. Wingtack 10 (from Goodyear)

These adhesive compositions may be mixed and applied in melt form.

The silane grafted rubbers are prepared as the reaction product of 100 parts of the basic rubber with 2-3 parts of vinyl trimethoxy silane using the procedures set forth in British Patent Application No. 8924619.3 and PCT/GB89/00533.

Example 6

Contact adhesive compositions

Contact adhesive compositions are formulated as follows:

Component Formulation

Silane grafted polychloroprene Ungrafted polychloroprene² Silane grafted tackifier resin³ Solvent^** Catalyst⁵

1. Neoprene AC from DuPont silane grafted with vinyltrimethoxysilane (2%) as described in PCT/GB89/00533

2. Neoprene AC

3. Silane grafted Nirez 1085 (Example 1)

4. MEK, methyl ethyl ketone

5. Dibutyl tin dilaurate

The polymer, polyterpene and catalyst (generally presented as a masterbatch in polymer) are disposed in the solvent in a Silverson mixer.

Example 7

Sealant Compositions

Sealant compositions are formulated as follows:

TABLE V

Component Formulation

Silane grafted

Catalyst 13 0.02 0.02 0.020.02 0.02 0.02 0.02 0.02 0.02

1. Silane grafted Kraton 1652 (SEBS) 2. Silane grafted Kraton 1107 (SIS)

3. Silane grafted Kraton 1102 (SBS)

4. Silane grafted Butyl rubber (Exxon Butyl 065)

5. Kraton 1652

6. Kraton 1107

7. Kraton 1102

8. Butyl 065

9. Silane grafted Staybelite (Example 1)

10. Shellflex 451 from Shell Chemicals

11. 17:10 ratio of soft clay and fibrous talc

12. 26:12 ratio of toluene and xylene

13. Dibutyl tin dilaurate, generally in a polymer masterbatch

14. Maleic anhydride modified SEBS - Shell Kraton FG 1901X

The silane grafted rubber may be prepared by reacting 100 parts of rubber with 2-3 parts of vinyl trimethoxysilane using the procedure of British Patent Application 8924619.3 and PCT/GB89/00533.

The fillers are mixed with the rubber in a Brabender internal mixer, chopped and then aded to the resin, plasticizer, solvents and catalyst in a Silverson mixer.

Formulation 1 is prefered for where weather resistance is required.

Claims

1. A silane-modified tackifier resin or tack modifying wax containing at least two silanol or protected silanol groups per molecule.

2. A silane-modified resin as claimed in claim 1 being a silane-modified rosin, rosin derivative, polyterpene resin, aliphatic resin, styrenic resin, or terpene- phenolic resin.

3. A silane-modified resin as claimed in claim 1 or claim 2 wherein the resin prior to silane modification has a number average molecular weight of 250-2500.

4. A silane-modified resin as claimed in any preceding claim wherein the resin prior to silane modification has a softening point of -15°C to 88^βC.

5. A silane-modified wax as claimed in claim 1 being a silane-modified paraffin wax, microcrystalline wax or Fischer-Tropsch wax.

6. A silane-modified wax as claimed in claim 1 or claim 5 wherein the wax prior to silane modification has a number average molecular weight of 300-2000.

7. A silane-modified resin or wax as claimed in any preceding claim wherein the silane group is of formula (I).

R[A-Si(Y)₃._ιn(X)_ra]_n (I)

_' where R is the residue of the unmodified resin or wax; n is an integer of at least 2, A is a bond or a divalent linking group, Y is a blocking group not displaceable by hydrolysis, m is 1,2 or 3, and X is a leaving group displaceable by hydrolysis.

8. A silane-modified resin or wax as claimed in claim 7 obtained by grafting with vinyl trimethoxy silane, vinyl triethoxy silane or ga ma-methacryloxypropyl- trimethoxy silane.

9. A cross-linkable composition comprising: a reactive group-containing polymer or macromolecule; a silane modified resin and/or a silane modified wax as claimed in any preceding claim; and, optionally packaged separately from said resin or wax, a silanol condensation catalyst.

10. A composition as claimed in claim 9 being a hot melt adhesive composition.

11. A hot melt adhesive composition as claimed in claim 10 comprising at least one further component selected from: unmodified tackifier resins; antioxidants; further polymers; and diluents and modifiers.

12. A hot melt adhesive composition as claim in claim 10 or claim 11 comprising from 5 to 40% by weight of the silane-modified tackifier resin.

13. A hot melt adhesive composition as claimed in any of claims 10 to 12 further comprising a moisture releasing agent.

14. Articles formed from a cross-linked silane-modified resin or wax as defined in any of claims 1 to 8 or a cross-linked composition as defined in claim 9.