KR20000005547A - Process for radiation cross-linking polymers and radiation cross-linkable compositions - Google Patents

Abstract

PURPOSE: A radiation cross-linkable composition is provided especially those which combine polymerizable and nonpolymerizable radiation-activatable cross-linkers. CONSTITUTION: A method for radiation crosslinkage of polymer with various crosslinkage density and characteristic consisted of (a) a process for providing radiation crosslinkage compound containing radiation crosslinkage polymer with extraction hydrogen atom and radiation crosslinkage composition having non-polymerization radiation activation crosslinkage agent, (b) a process for providing monochromatic radiation light source with sufficient wave length to crosslinkage polymer and activate the crosslinkage agent, (c) a process for exposuring the radiation crosslinkage composition to crosslinkage the polymer to radiation emitted from monochromatic radiation light source for sufficient time.

Description

Radiation Crosslinking Methods and Radiation Crosslinkable Compositions of Polymers

This application is a partial continuing application of US patent application Ser. No. 08 / 635,276, filed April 19, 1996, which is incorporated herein by reference.

Field of invention

The present invention generally relates to a method of radiation crosslinking a polymer and more particularly to a method of radiation crosslinking a polymer using a monochromatic light source such as an excimer laser or lamp. The present invention relates to a radiation crosslinkable composition and more particularly to a composition comprising both a polymer having a radiation activated crosslinking group and a non-polymerizable radiation activated crosslinker.

Related technology

Crosslinked polymers (ie, polymer network structures) have very different mechanical and physical properties than their uncrosslinked linear or branched polymers. For example, crosslinked polymers can exhibit unique and highly desirable properties such as solvent resistance, high cohesive strength and elastic properties.

Crosslinking reactions can occur in situ during polymer formation. However, as the polymer often needs to be further processed, it is more common to take it out of a linear or branched polymer and then crosslink in the final processing step. The curing or crosslinking step is activated by moisture, thermal energy or radiation. Activation using radiation, in particular ultraviolet light as a light source, is widespread.

Ultraviolet lamps are commonly used as ultraviolet light sources for irradiating light treatable adhesives, coatings and the like. Usually lamps contain mercury element spheres and one or more additives may be used to enhance the specific spectral range or power of the lamp. Thus, the spectrum of light irradiated by the lamp is the spectrum of the element of mercury or the spectrum of element of mercury controlled by the additive. The spectrum obtained by the lamp has radiation over a relatively wide range of 240-2000 nm. Since the radiation is distributed over a wide range, the output of the lamp is relatively weak at any particular subsection of the output spectrum. However, in certain applications, it may be required that the strongest portion of the output radiation be within a narrow range. In addition, in the context of conventional ultraviolet light sources, a broad spectral distribution may require an exposure time of long exposures and may result in deterioration of surface properties due to photochemical decomposition of the polymer, which is an unwanted side reaction and overcure of the polymer surface.

Recently, new ultraviolet light sources have been introduced that can deliver certain monochromatic or narrow band outputs based on excimer formation that occurs in certain noble gases or rare gas / halogen mixtures when exposed to high energy. The wavelength emitted from these light sources depends on the gas used. For example, an excimer light source containing xenon gas emits light at a wavelength of 172 nm, a xenon chloride excimer light source emits light in a narrow band at 308 nm, and a chlorinated krypton excimer light source emits ultraviolet light at 222 nm. . The mechanisms by which these devices operate and the structure of these devices are described in Kitamura et al., Applied Surface Science, 79/80 (1994), 507-513, Turner et al. German Patent Application DE 4,302,555 Al. , And Kogelschatz et al., ABB Review, 3 (1991), 21-28.

Excimer lamps have been used for deformation of polymer surfaces and microstructural deformation and photodeposition of various coatings on metal, dielectric and semiconductor surfaces. Examples of such uses are described in Kozelschatz, Applied Surface Science, 54 (1992), 410-423 and Zhang et al., Journal of Adhesion Science and Technology, 8 (10) (1994), 1179-. 1210].

European patent application EP 604738 Al of Nohr et al. Coats a cationically curable adhesive composition on the surface of a first sheet and releases the adhesive composition from an excimer lamp having a narrow wavelength band in the range of about 260 to about 360 nm. The laminate manufacturing method including exposing to the ultraviolet-ray and contacting the surface with which the adhesive composition of the 1st sheet was apply | coated with the surface of a 2nd sheet is described. The adhesive composition comprises about 94 to about 60 weight percent cycloaliphatic diepoxide, about 1 to about 10 weight percent cationic photoinitiator and about 5 to about 30 weight 5 vinyl chloride-vinyl acetate-vinyl alcohol trimer (adhesive) By weight of the composition).

International patent application WO 94/14853 to Bloom et al. Describes a method of crosslinking a contact adhesive having the necessary photopolymerizable group using monochromatic radiation emitted from an excimer laser ultraviolet light source in the range of 180 to 400 nm. The contact adhesive is made of at least one comonomer containing an olefinically unsaturated monomer and a photopolymerizable group. Acetophenone, benzophenone, benzyl derivative, benzoin derivative, dialkoxy acetophenone, hydroxyalkyl phenone, α-acyl oxime ester, α-halogen ketone, thioxanthone, fluoronon derivative, anthraquinone derivative, iron-arene Photopolymerizable groups such as complexes, dibenzosuberon and mihira ketone are incorporated into the contact adhesive.

Since such crosslinkers are in close proximity and incorporated into the polymer backbone, copolymerization at concentrations suitable for the end use of the cured polymer provides effective crosslinking. See, for example, US Pat. No. 4,737,559 to Kellen et al., Which discloses aromatic ketone monomers (particularly para-acryloxybenzophenones) incorporating other acrylate and methacrylate monomers to reduce pressure. To form an adhesive copolymer. The incorporation of aromatic ketone monomers into the polymer backbone prior to crosslinking significantly increases the crosslinking efficiency by including monomers in the copolymer as compared to addition of aromatic ketone compounds that were not initially copolymerized into the copolymer. Because of the increased efficiency, only small amounts of aromatic ketone monomers are needed to obtain a useful degree of crosslinking.

However, there are some inherent limitations in making adhesives and other polymeric materials with radiation activated crosslinking groups from monomers containing photopolymerizable groups. For example, problems arise when trying to increase or decrease the degree of crosslinking of polymers containing copolymerized crosslinkers. The crosslinker concentration is predetermined during the formation of the polymer and therefore cannot be directly changed or adjusted. Photopolymerization conditions can also activate radiation-activated crosslinking groups, which can lead to unwanted crosslinking too quickly during polymer preparation. Such undesired crosslinking early can be particularly problematic when trying to achieve high levels of crosslinking.

Crosslinking of polymers containing radiation activated crosslinking groups can also be influenced by subsequent addition of other components such as oligomers or polymeric materials, such as flow control agents, plasticizers, tackifiers and the like. The addition of these components dilutes the concentration of incorporated crosslinking groups and reduces the likelihood of bonding to other sites on the same or different polymer chains to form crosslinks. Moreover, dilution can reduce the number of crosslinks per unit volume, thereby impairing the performance of the crosslinked polymer system. In addition, the added component absorbs the light necessary to activate the crosslinker, reacts with the activated crosslinker (if the added component contains extractable hydrogen atoms), and is not incorporated. Molecular weight fragments may be provided in the composition to reduce the performance of the incorporated crosslinkers. In all of these cases, the added components lower the crosslinking efficiency of the crosslinking groups incorporated into the polymer.

Otherwise, the non-polymerizable crosslinker provides some advantages to the copolymerizable crosslinking compound. Although usually more volatile and less efficient than their copolymerizable counterparts, non-polymerizable crosslinking compounds can be added to various polymer systems at desired levels before, during or after polymerization. Examples of non-polymerizable crosslinkers are anthraquinones, substituted anthraquinones, polyfunctional acetophenones, polyfunctional benzophenones and triazines.

Vesley et al., US Pat. Nos. 4,391,678 and 4,330,590, describe a class of fast curing non-polymerizable triazine photocrosslinkers mixed with acrylic monomers and optionally ethylenically unsaturated copolymerizable monomers. The triazine-containing polymerizable mixture is exposed to UV radiation to form crosslinked polyacrylates. Triazines are effective crosslinkers for polyacrylates, but can generate corrosive gases during polymerization and / or crosslinking.

U.S. Patent No. 5,407,971 to Eververas et al. Describes the use of radiation-activated multifunctional acetophenones and benzophenones as crosslinkers for elastomeric polymers. Compared with the use of conventional acetophenones, benzophenones and triazines, these radiation-activatable multifunctional acetophenones and benzophenone crosslinkers are less volatile, have increased compatibility, and are less sensitive to oxygen and thus toxic or corrosive byproducts. Release and discoloration of the final product can be avoided.

WO 96/05249 discloses syrups that can be cured with crosslinked viscoelastic material. The disclosed composition is based on a mixture of free radically polymerizable, ethylenically unsaturated monomers comprising a small amount of ethylenically unsaturated monomers having a radiation sensitive hydrogen extractor. This mixture is exposed to energy to partially polymerize the monomer mixture and form a coatable syrup. A radiation sensitive hydrogen extractor or ethylenically unsaturated monomer with polyethylene unsaturated monomer can then be added to the syrup. Exposing the syrup to energy again yields a crosslinked viscoelastic material.

Summary of the Invention

The first two sides of the invention generally relate to a method of radiation crosslinking a polymer. Radiation-activated crosslinking such as anthraquinone, substituted anthraquinone, (polyfunctional or copolymerizable) acetophenone, (polyfunctional or copolymerizable) benzophenone, and substituted triazine using a monochromatic radiation light source (e.g. excimer lamp or excimer laser) It has been found that elastomers and thermoplastic polymers combined with binders can be crosslinked. As a result, it is possible to obtain polymers that crosslink more effectively than conventional curing methods using high pressure, medium pressure or low pressure mercury vapor lamps. Thus, the term "radiation-activated crosslinker or group" in the context of the present invention may be activated when the crosslinker or group is exposed to radiation, in particular light emitted by a high pressure, medium or low pressure mercury vapor lamp or excimer lamp or laser. That is to say, that is, to become reactive.

Thus, in the first two-sided embodiment of the present invention,

(a) (i) a radiation crosslinkable polymer having extractable hydrogen atoms (hereinafter referred to simply as " radiation crosslinkable polymer "); And

(ii) providing a radiation crosslinkable composition comprising a non-polymerizable radiation activated crosslinker;

(b) providing a monochromatic radiation light source having a wavelength sufficient to activate the crosslinker and crosslink the polymer; And

(c) exposing the radiation crosslinkable composition to radiation emitted by a monochromatic radiation light source for a time sufficient to crosslink the polymer.

Radiation crosslinkable polymers include polyolefins, polystyrenes, vinyl plastics, polyacrylates, polymethacrylates, poly (vinyl esters), polyamides, polycarbonates, polyketones and at least one monomer from which the polymers can be derived. It may be a thermoplastic polymer selected from the group consisting of a copolymer comprising a polymerization product of a copolymerizable comonomer. Otherwise, the radiation crosslinkable polymer may be polyurethane, polydiorganosiloxane, ABA type block copolymer, synthetic rubber, natural rubber, ethylene-vinyl monomer polymer, poly (vinyl ether), poly (vinyl ester), polyacrylate , Polymethacrylates and elastomers selected from the group consisting of copolymers comprising at least one monomer from which the polymers can be derived and a polymerization product of a copolymerizable comonomer. In either case, it is desirable that the radiation crosslinkable polymers (except crosslinkers) do not substantially absorb radiation emitted by the monochromatic radiation light source.

Monochromatic radiation light sources can be excimer lasers or excimer lamps, but excimer lamps are preferred. The monochromatic radiation light source preferably emits radiation having a wavelength of 270 to 370 nm, more preferably emits radiation having a wavelength of about 300 to 360 nm, and emits radiation having a wavelength of about 300 to 340 nm. Much more desirable. Most preferred monochromatic radiation light sources are XeCl excimer lamps that emit radiation having a wavelength of about 308 nm.

In another embodiment of the first two sides of the invention, the radiation activated crosslinker is polymerizable (i.e., the crosslinker is copolymerized with a monomer that polymerizes to form a polymer), or is non-polymerizable (i.e. forms a polymer). The polymer and the crosslinking agent are combined or the monomer and the crosslinking agent are mixed (not reacting with the monomer) before the polymerization, or both are combined, and the monochromatic radiation light source is an excimer lamp.

In another embodiment of the first two sides of the present invention, the radiation crosslinkable composition may be a pressure sensitive adhesive after crosslinking. Thus, the present invention also

(a) backing the flexible pressure-sensitive adhesive tape to provide a suitable flexible web;

(b) (i) a radiation crosslinkable polymer having extractable hydrogen atoms; And

(ii) providing a radiation crosslinkable pressure sensitive adhesive composition comprising a radiation activated crosslinker;

(c) applying the radiation crosslinkable pressure sensitive adhesive composition to at least a portion of one or more surfaces of the flexible web;

(d) providing an excimer lamp capable of activating the crosslinker and emitting monochromatic radiation having a wavelength sufficient to crosslink the polymer; And

(e) exposing the radiation crosslinkable pressure sensitive adhesive composition to radiation emitted by the excimer lamp for a time sufficient to crosslink the polymer and form a pressure sensitive adhesive tape. Provide a method.

The second two sides of the present invention are radiation comprising a radiation crosslinkable polymer having a radiation activated crosslinking group capable of extracting hydrogen when activated and a non-polymerizable radiation activated crosslinker capable of extracting hydrogen atoms when activated. A crosslinkable composition is disclosed. The non-polymerizable radiation activated crosslinking agent is preferably selected from the group consisting of anthraquinones, substituted anthraquinones, polyfunctional acetophenones and polyfunctional benzophenones. In principle, triazine can also be used as a non-polymerizable radiation activated crosslinker, but when activated it can release corrosive gases such as HCl and undesired premature activation during UV-radiation induced polymerization. It is preferable not to use it on the 2nd both surfaces of this invention. The polymer is preferably poly (meth) acrylate. The polymer is more preferably poly (meth) acrylate in the form of beads prepared by suspension polymerization, in particular in the form of suspension polymerized beads. The second two-sided compositions of the present invention are particularly suitable for use with monochromatic radiation sources such as excimer lamps or lasers, but they can also be cured by other visible or ultraviolet light sources, including broader spectrum ultraviolet light sources such as medium pressure mercury lamps and the like. have.

The first two sides of the present invention are directed to a method of radiation crosslinking a polymer, and more particularly a method of radiation crosslinking a polymer using a monochromatic radiation light source. Monochromatic radiation light sources are light sources that emit a narrow spectral range of radiation, for example, radiation having a half width of about 50 nm or less, preferably about 5 to 15 nm. Any source of monochromatic radiation can be used for the first both sides of the present invention, but the radiation source is preferably an excimer laser or an excimer lamp. Excimer lamps (ie, pulsed light sources with no grains) are particularly preferred, and are preferred over excimer lasers (ie, pulsed light sources with no grains) because they have many advantages. Excimer lamps are more efficient than excimer lasers, and therefore can reduce operating costs. The lamp system can be miniaturized and easily operated. It is easier to control the wavelength of radiation emitted by a lamp than a laser. In addition, excimer lamps are more effective at delivering uniform radiation in a wider physical area than lasers.

An excimer light source is usually identified or referred to as the wavelength at which the maximum intensity of radiation appears (hereafter also according). The wavelength of the monochromatic radiation should be useful for crosslinking the polymer and will generally be about 270 to 370 nm, preferably about 300 to 360 nm, more preferably about 300 to 340 nm. Monochromatic radiation with a wavelength of about 308 nm has been found to be particularly useful. The wavelength of the emitted radiation is determined by the excimer light source. Various inert gas-halogen mixtures are known and can be used as excimer light sources, but most preferred is based on xenon chloride (XeCl) in which maximum intensity radiation is emitted at about 308 nm. The intensity of light will generally be about 5 to 20,000 mW / cm 2, more preferably 10 to 10,000 mW / cm 2 and most preferably about 50 to 2,000 mW / cm 2.

Excimer radiation light sources are available from Heraeus Noblelight of Hanau, Germany, and are described in various patent documents, including International Patent Application WO 94/14853 and German Patent Application DE 4,302,555 A1, and Kitamura et al. Applied Surface Science, 79/80 (1994), 507-513, Coselschatz et al. [ABB Review, 3 (1991), 21-28], Cozelschaats, Applied Surface Science, 54 (1992), 410 -423, and in Journal of Adhesion Science and Technology, 8 (10) (1994), 1179-1210.

The monochromatic radiation light source is used in combination with a radiation crosslinkable composition, more preferably consisting essentially of at least one radiation crosslinkable polymer and at least one radiation activated crosslinker. The polymers (except radiation activated crosslinkers) contain extractable hydrogen atoms and do not substantially absorb radiation emitted by the monochromatic radiation light source. "No substantially absorbing radiation" means that a small amount of radiation (less than 10%, preferably less than 1%) can be absorbed by the polymer and is absorbed because it is not used for crosslinking Silver deteriorates the efficiency of the system, so it is desirable not to absorb radiation. It also prevents unwanted photochemical reactions that can impair the performance of the polymer if it absorbs monochrome radiation.

The extractable hydrogen atoms may be present in the backbone and / or side chains of the polymer in an amount sufficient to crosslink the polymer to the desired level when the crosslinker / polymer composition is exposed to a monochromatic radiation light source. In general, hydrogen atoms are most easily extracted from tertiary carbon atoms, allyl and benzyl groups, hydrogens of carbon atoms in the alpha position relative to oxygen or nitrogen atoms and hydrogens attached to terminal or pendant mercapto groups.

Extractable hydrogen atom containing polymers that may be used on the first two sides of the present invention include thermoplastic polymers and elastomers (“elastomers”). Thermoplastic polymers are macromolecular materials capable of melting and repeating solidification by heating and cooling in a characteristic temperature range without exhibiting chemical changes during the conversion process. Examples of useful extractable hydrogen atom containing thermoplastic polymers include polyolefins such as polyethylene, polypropylene, polymethylpentene, polybutylene and ethylene-vinyl alcohol copolymers; polystyrene; Vinyl plastics such as polyvinyl chloride, polyvinylidene chloride and polyvinyl chloride chloride; Polyacrylates and polymethacrylates having high glass transition temperatures such as poly (methyl methacrylate); Poly (vinyl esters) with high glass transition temperatures such as poly (vinyl acetate); Polyamides; Polycarbonates; Polyimide; Polyketones such as polyetheretherketone; And a copolymer obtained by the polymerization of at least one monomer from which the polymers can be derived and a copolymerizable comonomer (which may also be a monomer from which the polymers are derived), which copolymer contains an extractable hydrogen atom. Can be mentioned.

However, it can be used more preferably on the first both sides of the present invention is an elastomer that is subjected to mild stress followed by release of the stress to substantially deform the ASTM D 1456-86 ("Standard Test Method For Rubber Property-Elongation At Specific Stress ") is defined as a macromolecular material that quickly returns to its nearly initial size and shape. Examples of extractable hydrogen atom containing elastomers useful in the present invention include polyurethanes; Polydiorganosiloxanes (eg, polydimethylsiloxanes); A-B-A type block copolymers such as styrene-isoprene-styrene block copolymer (SIS) and styrene-butadiene-styrene block copolymer (SBS); Various synthetic rubbers such as ethylene-propylene-diene monomer rubber (EPDM), styrene-butadiene rubber (SBR), polyisobutylene, synthetic polyisoprene, polybutadiene, acrylonitrile-butadiene copolymer and polychloroprene; caoutchouc; Ethylene vinyl monomer polymers such as ethylene-vinyl acetate; Poly (α-olefin); Poly (vinyl ether); Poly (vinyl ester); Polymethacrylate and polyacryllate, such as poly (methyl methacrylate); And a copolymer obtained by the polymerization of at least one monomer from which the elastomers can be formed and a copolymerizable comonomer (which may also be the monomer from which the polymers are derived) (these copolymers contain extractable hydrogen atoms). Can be mentioned. Preferred elastomers for use in the first two sides of the present invention are polyacrylates, natural rubber, polybutadiene, polyisoprene, SBS block copolymers and SIS block copolymers.

Most preferred as a radiation crosslinkable polymer which is thermoplastic or elastomeric in the radiation curable composition of the present invention is poly (meth) acrylate, which is a polymerization product in which an acrylate or methacrylate monomer is copolymerized with an ethylenically unsaturated free radical polymerizable monomer. Can be obtained as

Acrylate and methacrylate monomers useful in preparing the radiation crosslinkable polymers of the present invention are those of the formula H ₂ C═CR ₁ COO-Y, wherein R ₁ represents —H or —CH ₃ , and Y is about 1 To monovalent straight chain alkyl, branched chain alkyl, or cycloalkyl groups having from about 24 carbon atoms). Examples of such acrylate and methacrylate monomers are methyl acrylate, methyl methacrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, isodecyl acrylate, 4-methyl-2- Pentyl acrylate, 2-methyl butyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, t-butyl acrylate, isobornyl acrylate, butyl methacrylate, ethyl acrylate, dode But are not limited to those selected from the group consisting of sil acrylate, octadecyl acrylate, cyclohexyl acrylate, and mixtures thereof.

Preferred acrylate monomers are isooctyl acrylate, isononyl acrylate, isoamyl acrylate, isodecyl acrylate, 2-ethylhexyl acrylate, isobornyl acrylate, n-butyl acrylate, sec-butyl acrylate and It includes those selected from the group consisting of mixtures thereof.

Ethylenically unsaturated free radical reactive monomers which can be readily copolymerized with acrylate and methacrylate monomers can also be used in the preparation of the preferred polyacrylates. Such monomers include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, sulfoethyl methacrylate, N-vinyl pyrrolidone, N-vinyl caprolactam, acrylamide, t-butyl acrylamide, dimethyl Including but not limited to amino ethyl acrylamide, N-octyl acrylamide, acrylonitrile, vinyl acetate, vinyl propionate, styrene, mixtures thereof, and the like. Preferred monomers include those selected from the group consisting of acrylic acid, methacrylic acid, N-vinyl pyrrolidone, styrene, vinyl acetate and mixtures thereof.

Some of the thermoplastic polymers and elastomers can be used more effectively on the first both sides of the present invention when the monomers from which they are derived are copolymerized with other thermoplastic polymers and monomers from which the elastomers are derived (monomers for thermoplastic polymers are copolymerized with monomers for elastomers) Can be).

In addition to the radiation crosslinkable polymer, the compositions used on the first two sides of the present invention comprise copolymerizable or non-polymerizable radiation activated crosslinkers, with non-polymerizable crosslinkers being preferred. In general, radiation activated crosslinkers useful for the first two sides of the invention absorb hydrogen having a wavelength of about 270 to 370 α, preferably about 300 to 360 α, more preferably about 300 to 340 α, followed by hydrogen extractor. To be.

Copolymerizable radiation activated crosslinkers are generally randomly incorporated into the backbone of the radiation crosslinkable polymer during polymerization of the polymer. As a result, the copolymerizable crosslinker is preferably compatible and miscible with the monomer from which the polymer is derived (ie there should be no overall phase separation upon mixing). Copolymerizable crosslinkers can promote more effective crosslinking than their non-polymerizable counterparts and minimize problems associated with the volatility of the crosslinkers.

Useful copolymerizable crosslinkers include copolymerizable anthraquinones, copolymerizable acetophenones, copolymerizable benzophenones, copolymerizable triazines and mixtures thereof. Copolymerizable crosslinkers useful in the present invention include US Pat. No. 4,737,559 to Kelen et al .; 5,073,611 to Boettcher et al .; No. 5,128,386 to Auchter et al .; No. 5,202,483 to Bot et al .; 5,248,805 to Boy et al .; 5,264,533 to Boy et al .; Nos. 5,294,688, for example Aucher, and No. 5,389,699, for Beauture. Preferred copolymerizable crosslinkers are acrylate-functional aromatic ketones, especially 4-acryloxybenzophenones, disclosed in US Pat. No. 4,737,559 to Kelen et al.

The non-polymerizable radiation activated crosslinker is mixed or reacted with the radiation crosslinkable polymer after polymerization of the polymer or with the monomer (s) of the polymer before the polymerization, provided that they do not react with the monomer (s). . Included in this class are multifunctional crosslinkers and graftable crosslinkers. The advantage of using non-polymerizable crosslinkers is that they are more circulating because they are added to the polymer in the polymerization water. In addition, the non-polymerizable type need not be compatible, compatible or reactive with the monomer from which the polymer is derived.

Preferred non-polymerizable crosslinkers are anthraquinones, substituted anthraquinones, polyfunctional acetophenones, polyfunctional benzophenones, suitable triazines and mixtures thereof. Specific examples of useful anthraquinone based non-polymerizable crosslinkers are anthraquinones, t-butyl anthraquinones and 2-ethyl anthraquinones. Particularly preferred as non-polymerizable radiation activated crosslinkers are polyfunctional acetophenones and benzophenones having the formula (I).

(Wherein

X is CH _3- ; Phenyl; Or substituted-phenyl;

W represents -O-, -NH- or -S-;

Z has no ester, amide, ketone, urethane, aliphatic, aromatic aralkyl, heteroaromatic and cycloaliphatic groups without ethers, thiols, aryl groups and hydrogen atoms inaccessible to the carbonyl groups of the above formula An organic spacer selected from the group consisting of benzyl groups;

n is 2 or more, Preferably it represents the integer of 2-6.)

Particularly preferred embodiments are X is phenyl, W is oxygen, Z is-(-CH ₂ -)- _2-12 and n is 2.

Specific examples of preferred multifunctional benzophenones include 1,5-bis (4-benzoylphenoxy) pentane, 1,9-bis (4-benzoylphenoxy) nonane and 1,11-bis (4-benzoylphenoxy) ound. There is a square.

Useful non-polymeric substituted triazine crosslinkers also include U.S. Patent Nos. 4,329,384 to Besley et al .; Besley No. 4,330,590; And Besley No. 4,379,201. Specific examples of substituted triazine crosslinkers include 2,4-bistrichloromethyl-6- (4-methoxyphenyl) -s-triazine and 2,4-bistrichloromethyl-6- (3,4-dimeth Oxyphenyl) -s-triazine.

Combinations of copolymerizable radiation activated crosslinkers and non-polymerizable radiation activated crosslinkers can also be used in the radiation crosslinkable compositions described above. This provides a second both sides of the present invention. As described above, copolymerizable crosslinkers are effective in many radiation curable compositions but are less useful in some situations. For example, the initial conditions used to form a polymer containing a certain level of polymerizable radiation activated crosslinker may also activate photoactive groups present in the incorporated crosslinker. The undesirable result obtained by activating the crosslinker during polymerization is premature gelation. Reducing the level of copolymerizable crosslinker can reduce or eliminate unwanted gelling, but this may reduce the degree of crosslinking if the polymer is later irradiated during the planned crosslinking process.

Hydrogen can be extracted when a non-polymerizable radiation activated crosslinker is activated, which can extract hydrogen when activated to balance the prevention of premature gelation during polymerization while maintaining sufficient degree of crosslinking in the cured product. Mixed with a radiation crosslinkable polymer having a radiation activated crosslinking group. In particular, a broad range of crosslinking levels can be obtained by adding this type of non-polymerizable radiation activated crosslinker to a radiation crosslinkable polymer comprising a radiation activated crosslinker capable of extracting hydrogen atoms when activated. Found.

Combinations of copolymerizable crosslinkers and non-polymerizable crosslinkers are also useful when curing radiation crosslinkable polymers diluted with certain oligomeric or polymeric additives. These additives can reduce the efficiency of the crosslinker incorporated into various mechanisms, including reducing the concentration of photoactive species in the diluted system and inhibiting the crosslinking reaction by impairing the energy required to activate the crosslinker. Additives with extractable hydrogen may inhibit or terminate the crosslinking reaction via a chain transfer or chain termination mechanism, resulting in lowering the level of crosslinking.

In such dilute systems, it may be advantageous to supplement the crosslinker incorporating a non-polymerizable crosslinker in an amount sufficient to make up for the inhibitory effect of the polymer or oligomer additive. The addition of a non-polymerizable crosslinker not only increases the concentration of the crosslinker that cures the diluted system, but also provides the experimenter with the flexibility to add a crosslinker having a different absorption or photoactive property than that incorporated in the radiation crosslinkable polymer. can do. The advantages mentioned later are particularly useful when the oligomers or polymer additives absorb UV radiation at wavelengths that inhibit the photoactivity of the incorporated crosslinkers.

Preference is given to poly (meth) acrylates for use as extractable hydrogen-containing radiation crosslinkable polymers on the second double side of the present invention. Poly (meth) acrylates can be prepared by a variety of polymerization methods, including emulsions, suspensions, solvents, solutions or bulk polymerizations. The polymerization method is G. Odian, Principles of Polymerization, 3rd edition, Wiley-Interscience: New York, 1981, pages 286-296. Poly9meth) acrylates prepared using suspension polymerization are particularly suitable for use on the second both sides of the present invention, see US Pat. No. 4,833,179 to Young et al .; 4,952,650 to Young et al .; And Young et al., 5,292,844. Suspension polymers are generally in the form of spheres or globules with diameters of at least 1 μm (possible to 1000 μm).

In general, the polymerization process involves first preparing a monomer premix. Premixes typically include acrylate and / or methacrylate monomers, optionally ethylenically unsaturated free radical polymerizable monomers, chain transfer agents and free radical initiators. Also, if used, a copolymerizable radiation activated crosslinker is added to the premix. The premix is then combined with an aqueous phase comprising suspending agent, water and optionally a surfactant. Modifiers such as hydrophobic silica, polystyryl methacrylate macromers, and / or reactive zinc salts may be added to the suspension mixture prior to, during or after the polymerization. Similarly, a non-polymerizable radiation activated crosslinker capable of extracting hydrogen when activated at any time prior to irradiation of the suspension polymer may also be added to the radiation crosslinkable polymer prepared according to the above method. .

An example of how a radiation crosslinkable polymer having a radiation activated crosslinkable group can be effectively combined with a non-polymerizable radiation activated crosslinker is to crosslink a poly (meth) acrylate adhesive polymer diluted with a tackifier resin. Tackifier resins commonly used in poly (meth) acrylate adhesives are low molecular weight organic compounds derived from natural sources and are based on rosin acids, selected phenol modified terpenes and alka-pinene. Such resins promote adhesion but often damage the volume or cohesion of the adhesive.

When crosslinking a tackified poly (meth) acrylate adhesive using ultraviolet light, the tackifier resin can cause some of the adverse effects mentioned above in connection with oligomers and polymer additives (ie, the required crosslinking groups are required to activate the incorporated crosslinking groups). Absorption of energy, unwanted chain transfer or chain termination reactions, etc.). In order to solve these problems, it has been found that radiation-activated crosslinking groups can be effectively combined with non-polymerizable radiation-activated crosslinkers to obtain radiation crosslinkable compositions. Such formulations can enhance the performance of the adhesive compared to using only equivalent amounts of non-polymerizable radiation activated crosslinkers alone.

In a second aspect of the invention using a combination of a non-polymerizable radiation activated crosslinker and a radiation crosslinkable polymer having a radiation activated crosslinking group, it is understood that the radiation activated crosslinking group is derived from a radiation activated crosslinker having a polymerizable group. desirable. Polymerizable radiation activated crosslinkers useful for use in this embodiment include polymeric acetophenones, polymeric benzophenones, polymeric anthraquinones, and mixtures thereof. Polymeric crosslinkers useful in the present invention are further described in US Pat. No. 4,737,559 to Kelen et al .; 5,073,611 to Boy et al .; No. 5,128,386 to Auktor et al .; 5,202,483 to boats and the like; 5,248,805 to Boy et al .; 5,264,533 to Boy et al .; Nos. 5,294,688, for example Aucher, and No. 5,389,699, for Beauture. Preferred polymerizable crosslinkers are (meth) acrylate functional aromatic ketones, especially 4-acryloxybenzophenones, disclosed in US Pat. No. 4,737,559 to Kelen et al. Polymeric crosslinkers of the type mentioned below are particularly preferred for preparing poly (meth) acrylate polymers having radiation activated crosslinking groups which can extract hydrogen atoms when activated.

Preferred non-polymerizable crosslinkers for use on the second side of the invention are non-polymerizable anthraquinones, non-polymerizable polyfunctional acetophenones, non-polymerizable polyfunctionals, including non-polymerizable substituted anthraquinones. Benzophenone and mixtures thereof. Specific examples of useful anthraquinone based non-polymerizable crosslinkers are anthraquinones, t-butyl anthraquinones and 2-ethyl anthraquinones. Examples of useful non-polymerizable multifunctional acetophenones and benzophenones are the compounds of formula I described above.

Radiation-activated crosslinkers (on both sides of the invention), whether incorporated into a radiation crosslinkable polymer or of a non-polymeric type, are usually used alone or in combination in an amount sufficient to provide the desired ultimate properties. Meaning). For example, in the context of making an adhesive, the effective amount of crosslinking agent is an amount sufficient to crosslink the polymer so as to have a suitable cohesive force, but not so large that the polymer is overcured. Substantial amounts of crosslinking agents used include the use, type of polymer, type of crosslinking agent, ease of hydrogen extraction from the polymer, reactivity of the radicals formed, strength and duration of exposure of the composition to radiation, molecular weight of the polymer and the desired final properties of the material. Will change accordingly. Within these criteria the total amount of crosslinker is preferably from about 0.01 to 25% by weight, more preferably from about 0.1 to 10% by weight and most preferably from about 0.1 to 1.0% by weight based on the total weight of the polymer.

Other useful materials that may optionally be used on both sides of the present invention include thermally expandable polymer microspheres, glass microspheres, fillers, pigments, blowing agents, stabilizers, flame retardants and viscosity modifiers that do not interfere with light absorption and crosslinking. have.

Crosslinked polymers can be readily prepared according to the present invention. When using a copolymerizable radiation activated crosslinker, the crosslinker is blended or blended with other monomers that provide a polymer, wherein the crosslinker is miscible, compatible with and reacts with the monomers. The monomers are then polymerized in any conventional manner well known to those skilled in the art such as anionic, cationic and free radical techniques. In the case of a non-polymerizable radiation activated crosslinker, the crosslinker is dissolved in a solvent and mixed with the polymer previously formed by other suitable techniques of extruding with the polymer or combining the polymer with the non-polymerizable crosslinker. Otherwise, the non-polymerizable crosslinker may be combined with the monomer (s) prior to polymer formation but in this case does not react with the monomer (s).

In either case, once the crosslinker is blended with the polymer, the crosslinker / polymer composition is directly irradiated with light, or well known in the art as solvent coating, extrusion coating (e.g., hot melt extrusion coating), solvent free or aqueous coating. It can be applied to a substrate by known methods. The composition may be applied to at least a portion of one or more major surfaces of a suitable flexible or rigid substrate or surface. Useful flexible substrates or webs include plastic films such as paper, poly (propylene), poly (ethylene), poly (vinyl chloride), poly (tetrafluoroethylene), polyester (e.g. poly (ethylene terephthalate)). , Polyimide films such as DuPont's Kapton ™, cellulose acetate and ethyl cellulose The substrate may also be a fabric formed from yarns of synthetic or natural materials such as cotton, nylon, rayon, glass or ceramic materials, or natural Or non-woven fabrics such as synthetic fibers or air-laid webs of blended fibers thereof, and other suitable substrates may be formed of metal, metallized polymer films or ceramic sheet materials. Composite materials such as metals, treated metals (eg automotive and marine surfaces), polymers and fiber reinforced plastics. When applying the Dangerous to the substrate, the exposure for a time sufficient to crosslink the polymer to the desired level of the wavelength described above this radiation source (preferably H. thin monochromatic radiation light source).

Excimer lasers and excimer lamps both provide monochromatic radiation light sources, but excimer lamps are preferred for several reasons, including more effective radiation to larger physical areas. The excimer lamp comprises a single lamp or lamp array, and is preferably arranged to irradiate light to a somewhat larger area than the target substrate so as to irradiate light uniformly over the entire area. When using excimer lasers, it may be helpful to provide a lens system to distribute radiation over a larger physical area.

The radiation crosslinkable compositions described herein are useful in a variety of applications, including adhesives (particularly pressure sensitive adhesives and pressure sensitive adhesive coating articles such as tapes, sheets, labels, etc.), coatings, sealants, photoresists and hardcoats.

method of inspection

The following test procedure was used to evaluate the compositions prepared in the examples. The compositions were useful as adhesives.

Room temperature shear strength

Shear strength is a measure of the cohesion or durability of an adhesive. It is based on the amount of force required to pull the adhesive strip (tape) in a direction parallel to the surface from a flat reference surface on which the adhesive strip (tape) is attached at a constant pressure. The time required to pull the reference area of the adhesive coated sheet material from the stainless steel inspection panel under pressure of constant reference load is measured in minutes. This test follows the procedure described in ASTM D 3645 M-88: "Holding Power of Pressure Sensitive Adhesive Tapes".

The inspection was carried out at room temperature on adhesive coated sheet materials attached to stainless steel panels prepared and cleaned as described in Peel Adhesion Test of Glass Plates. The 0.127 dm X 0.127 dm portion of each strip was firmly bonded to the panel by one end of the tape freely. Secure the panel to the shelf so that the free end of the stretched adhesive coated strip and the panel with the adhesive coated strip are attached to the free end of the adhesive coated strip by hanging the weight of 1000 grams and pulling it tight. Let's do it. In order to more accurately measure the holding force of the adhesive to be inspected, the shear strength was neglected by ignoring any peeling force by less than 180 °. The time taken to remove each adhesive coated strip from the test panel was recorded as shear strength. The test was stopped after 10,000 minutes, a good shear strength value. The reported result is the average of two samples.

High temperature shear strength

Hot shear strength was measured as described in room temperature shear strength except that the test samples were first aged at 70 ° C. for 15 minutes and then tested at 70 ° C. The reported result is the average of two samples.

Gel formation

An amount of crosslinked polymer was placed in an excess of solvent capable of dissolving the polymer and dissolved for 24 hours and filtered. The recovered solid was dried and the amount measured. Gel content was determined as follows.

(Solid weight / initial weight of sample) X 100 (%)

The results are the mean of the two results and reported as approximate integers.

The following non-limiting examples further illustrate the invention. In the examples the following abbreviations are used.

ABP: 4-acryloxybenzophenone

C5EBP: 1,5-bis (4-benzoylphenoxy) pentane

C9EPB: 1,9-bis (4-benzoylphenoxy) nonane

C11EBP: 1,11-bis (4-benzoylphenoxy) undecane

TBA: t-butyl anthraquinone

TRIAZINE 2,4-bistrichloromethyl-6- (4-methoxyphenyl) -s-triazine

Example 1 Preparation of C5EBP

4-hydroxybenzophenone (3000 g; 15.15 mol), NaOH (608 g; 15.15 mol) and ethylene glycol (5500 g) were placed in a 12 L flask equipped with a condenser and a mechanical stirrer. The reaction mixture was stirred at 85 ° C. until 4-hydroxybenzophenone and NaOH were dissolved. The reaction mixture was then adjusted to 135 ° C. and 2000 g (8.6 mol) of 1,5-dibromopentane were added. Excess NaOH (80 g, 2.05 mol) was added in portions to maintain basic pH. After 1.5 hours of cooling, the reaction was essentially complete. 2500 g of water was added to cool the mixture and the precipitated product was filtered out of the ethylene glycol / water mixture. The product was then purified by mixing the dark brown solid precipitate with 3608 g of ethyl acetate. The ethyl acetate purification step was repeated and air dried to afford 2982 g of purified C5EBP.

Example 2-Preparation of C11EBP

C11EBP was prepared according to Example 1 by replacing 1,5-dibromopentane with an equivalent amount of 1,11-dibromoundane.

<Examples 3-8>

90% by weight of isooctyl acrylate, 10% by weight of acrylic acid and 0.1% by weight of carbon tetrabromide (CBr ₄ ) in ethyl acetate according to the method of U.S. Patent Re 24,906 to Ulrich, which is incorporated herein by reference. Now a series of acrylate pressure sensitive adhesives have been prepared. The inherent viscosity of each of the resulting adhesives was 0.64 dl / g in 27 ° C. ethyl acetate.

The non-polymerizable radiation activated crosslinkers of the type and amount specified in Table 1 below were dissolved in a 40 wt% solution of each adhesive in ethyl acetate (the amount of crosslinker reported for Example 3-5 is based on the weight of the polymer Weight 5. The amount reported for Example 6-8 is the weight percent calculated based on molar equivalents used in comparison to Example 3-5). The mixture was then knife coated onto a 38 μm thick aziridine-primed poly (ethylene terephthalate) film and dried at 65 ° C. for 15 minutes to give a 25 μm thick coating. The coated film was passed through a curing chamber equipped with a 308 nm XeCl excimer lamp (Model Excimer Lamp 308, available from Heraeus Noble, Hanau, Germany) approximately 2.5 cm high above the conveyor belt system. Table 1 shows the total energy investigated in each example. (All excimer energy herein was measured in the UVB (280-320 nm) range) The cured samples were stored for 24 hours at constant room temperature maintained at 22 ° C. and 50% relative humidity. Gel formation in each example was measured as described above using ethyl acetate as solvent. Room temperature shear strength was also measured as described above. Gel formation and shear strength data for each example are listed in Table 1.

Example Crosslinker Energy dose (mJ / ㎠) Room temperature shear strength (min) Gel formation (%) type Volume (wt%) 3 C5EBP 0.1 80 228 7 3 C5EBP 0.1 160 1861 34 3 C5EBP 0.1 320 8089 41 4 C5EBP 0.2 80 10,000 56 4 C5EBP 0.2 160 10,000 66 4 C5EBP 0.2 320 10,000 70 5 C5EBP 0.4 80 10,000 77 5 C5EBP 0.4 160 10,000 83 5 C5EBP 0.4 320 10,000 84 6 C11EBP 0.118 80 229 14 6 C11EBP 0.118 160 4812 39 6 C11EBP 0.118 320 10,000 42 7 C11EBP 0.236 80 10,000 60 7 C11EBP 0.236 160 10,000 71 7 C11EBP 0.236 320 10,000 72 8 C11EBP 0.472 80 10,000 80 8 C11EBP 0.472 160 10,000 86 8 C11EBP 0.472 320 10,000 87

In the above embodiment, it can be seen that the shear strength performance increases as the radiation-activated crosslinker increases or the radiation dose increases. Increasing the radiation dose provides good shear strength even with relatively small amounts of crosslinker. Using an appropriate amount of crosslinker, very good shear strength is obtained immediately. Examples 3 and 6, which showed less than 10,000 minutes of shear strength, had poor cohesion (ie, adhesive residue remained on both the test panel and the sheet material).

<Example 9-11>

The following examples crosslink the acrylate pressure sensitive adhesives of Examples 3-8 using different amounts of C5EBP ql-polymerizable crosslinkers and different adhesive thicknesses as shown in Table 2 and using an XeCl excimer laser. To illustrate. The mixture was knife coated on a 38 μm thick flexible aziridine primed poly (ethylene terephthalate) web, dried at 65 ° C. for 15 minutes, with a maximum intensity at 308 nm and a maximum pulse frequency of 150 Hz. Göttingen) cured using a 300i series XeCl excimer laser. The beam was optically dispersed using quartz optics to cover an area of 0.03 dm high and 1.52 dm wide with an average energy per pulse of about 100 mJ / cm 2. The sample to be irradiated with light was attached to the platform of the xy-shift stage located in the orthogonal orientation, and the sample passed through the excitation pulse incidentally occurring in the normal pulse at various speeds. The radiation dose was adjusted mainly by changing the speed of the substrate. Table 2 shows the total amount of energy investigated in each example. Gel formation of each example was measured as described above using ethyl acetate as solvent and the results are shown in Table 2.

Example C5EBP Crosslinker Weight% Coating thickness (㎛) Energy dose (mJ / ㎠) Gel formation (%) 9 0.10 25 414 3 9 0.10 25 829 8 9 0.10 25 1243 7 9 0.10 50 414 2 9 0.10 50 829 5 9 0.10 50 1243 3 9 0.10 75 414 4 9 0.10 75 829 2 9 0.10 75 1243 2 10 0.20 25 414 12 10 0.20 25 829 42 10 0.20 25 1243 35 10 0.20 25 2487 62 10 0.20 50 414 7 10 0.20 50 829 30 10 0.20 50 1243 38 10 0.20 75 414 6 10 0.20 75 829 32 11 0.40 25 205 10 11 0.40 25 414 54 11 0.40 25 829 70 11 0.40 25 1243 57 11 0.40 50 205 6 11 0.40 50 414 21 11 0.40 50 829 53 11 0.40 50 1243 55 11 0.40 50 205 5 11 0.40 75 409 29 11 0.40 75 414 39 11 0.40 75 829 41

As can be seen in Table 2, the composition incorporated by varying the amount of non-polymerizable crosslinker can be crosslinked using an excimer laser as a monochromatic radiation light source.

<Example 12-15>

An emulsion polymerized acrylic pressure sensitive adhesive comprising 94.5 parts of isooctyl acrylate and 5.5 parts of acrylic acid having an intrinsic viscosity of 2.05 dl / g in ethyl acetate at 27 ° C. was prepared according to U.S. Patent No. Re 24,906. The adhesive was dried and then dissolved in 70/30 toluene / isopropanol solvent mixture (25% by weight solid) according to the amount and type of non-polymerizable crosslinker specified in Table 3. The formulation was then knife coated onto a 38 μm thick flexible aziridine primed poly (ethylene terephthalate) film and dried at 65 ° C. for 15 minutes to give a 15 μm thick dried coating. The coated sample was cured using the XeCl excimer lamp system of Examples 3-8 with the total energy dosage reported in Table 3. Gel formation (in ethyl acetate) and room temperature shear strength obtained by the method described above are also described in Table 3.

Example Crosslinker Energy dose (mJ / ㎠) Room temperature shear strength (min) Gel formation (%) type Volume (wt%) 12 C5EBP 0.10 0 60 36 12 C5EBP 0.10 80 535 45 12 C5EBP 0.10 160 10000 61 12 C5EBP 0.10 320 10000 72 13 Anthraquinone 0.05 0 57 34 13 Anthraquinone 0.05 80 511 50 13 Anthraquinone 0.05 160 723 58 13 Anthraquinone 0.05 320 1696 63 14 Anthraquinone 0.10 0 56 35 14 Anthraquinone 0.10 80 10000 58 14 Anthraquinone 0.10 160 5881 67 14 Anthraquinone 0.10 320 10000 74 15 Anthraquinone 0.20 0 53 32 15 Anthraquinone 0.20 80 2783 74 15 Anthraquinone 0.20 160 2968 71 15 Anthraquinone 0.20 320 3979 77

Examples with shear strengths of less than 10,000 minutes showed at least some flocculation failure. When the amount of crosslinking agent was constant, increasing the irradiation amount of excimer radiation increased gel formation and room temperature shear strength.

<Example 16-19>

Examples 16-19 illustrate the benefits obtained when using a copolymerizable crosslinker (ABP) alone and in combination with a non-polymerizable crosslinker (C5EBP) in a radiation crosslinkable polyacrylate pressure sensitive adhesive. . In this example, 90 parts of isooctyl acrylate, 10 parts of acrylic acid, 0.15% Irgacure 651 (photoinitiator available from Ciba-Geigy), 0.025% chain transfer agent (% of photoinitiator and chain transfer agent is Based on the combined amount of acrylate and acrylic acid) to prepare a partially polymerized pre-adhesive composition. The mixture was irradiated with low intensity ultraviolet light until the partially polymerized pre-adhesive composition achieved a coatable viscosity. To the partially polymerized pre-adhesive composition 0.35% Iragacure 651 photoinitiator, 0.025% CBr ₄ , 0.1% ABP (Examples 16-19) and 0.1% C5EBP (Examples 17 and 19) were combined and thoroughly mixed.

The composition was knife coated 2.5 mm thick between two 0.005 mm thick UV-permeable polyester films coated with a silicone release layer. The coated sandwich structure was passed through two irradiation zones where total energy 750 mJ / cm 2 was released. In Zone 1, light having a light intensity of 0.4 mW / cm 2 was emitted at an energy of approximately 187 mJ / cm 2. In Zone 2, light with a light intensity of 2.0 mW / cm 2 was emitted at an energy of approximately 563 mJ / cm 2. During irradiation, the coated sandwich structure was cooled by air impingement to remove heat of polymerization. After passing through two exposure zones, the polyester sheet was removed from the sandwich structure, the polymerized composition was placed in a hot melt coater / extruder, and the molten composition was 51 μm on a release liner treated with silicone (Examples 16 and 17). ) Or 127 μm (Examples 18 and 19) and then laminated onto a 38 μm thick flexible aziridine primed poly (ethylene terephthalate) film. The coated samples were then cured by providing the total energy dosages listed in Table 4 using the system described in Examples 3-8. Gel formation (in ethyl acetate) and shear strength (room temperature and high temperature) were measured as in the examples described above and the results are shown in Table 4.

Example Crosslinker Energy dose (mJ / ㎠) Coating thickness (㎛) Room temperature shear strength (min) ^* High temperature shear strength (min) ^* Gel formation (%) type Volume (wt%) type Volume (wt%) 16 ABP 0.1 C5EBP - 400 51 1542 14 31 16 ABP 0.1 C5EBP - 800 51 10000 1080 43 16 ABP 0.1 C5EBP - 1200 51 10000 10000 55 17 ABP 0.1 C5EBP 0.1 400 51 10000 10000 71 17 ABP 0.1 C5EBP 0.1 800 51 10000 10000 78 17 ABP 0.1 C5EBP 0.1 1200 51 10000 10000 81 18 ABP 0.1 C5EBP - 400 127 958 11 41 18 ABP 0.1 C5EBP - 800 127 4088 40 47 18 ABP 0.1 C5EBP - 1200 127 10000 76 55 19 ABP 0.1 C5EBP 0.1 400 127 5051 62 57 19 ABP 0.1 C5EBP 0.1 800 127 10000 10000 79 19 ABP 0.1 C5EBP 0.1 1200 127 10000 10000 82 * Examples with strength less than 10,000 minutes fail to aggregate

In the above examples it has been demonstrated that copolymerizable crosslinkers can be used in the practice of the present invention. In addition, the addition of a non-polymerizable crosslinker to the elastomeric adhesive composition comprising a copolymerizable crosslinker increased the degree of crosslinking as can be seen by comparing Examples 18 and 20 and Examples 19 and 21, respectively. It has also been demonstrated in this example that the excimer light source and the radiation activated crosslinker can be used effectively to cure a relatively thick film of elastomeric material without overcuring the material surface.

<Example 20-22>

The emulsion polymerization acrylic pressure sensitive adhesives of Examples 20-22 were prepared and inspected following the procedure described in Examples 12-15 except that the adhesive was dried to a thickness of 25 μm. The amount of crosslinker reported in Example 20 represents weight percent based on the weight of the polymer. Table 5 lists the total energy dosage, gel formation, and room temperature shear strength values used in each example.

Example Crosslinker Energy dose (mJ / ㎠) Room temperature shear strength (min) Gel formation (%) type Volume (wt%) 20 C5EBP 0.2 0 48 36 20 C5EBP 0.2 80 1858 45 20 C5EBP 0.2 160 10000 61 20 C5EBP 0.2 320 10000/6266 72 21 C11EBP 0.236 0 53 34 21 C11EBP 0.236 80 454 50 21 C11EBP 0.236 160 6859 58 21 C11EBP 0.236 320 10000,7819 63 22 Anthraquinone 0.118 0 40 35 22 Anthraquinone 0.118 80 4500 58 22 Anthraquinone 0.118 160 4300 67 22 Anthraquinone 0.118 320 5019 74

The room temperature shear strength values reported the mean value of both samples if both samples failed 10,000 minutes ago and the value of each sample if only one sample failed 10,000 minutes ago. All samples with shear strength of less than 10,000 minutes all showed at least some aggregation failure. The sample shows that the method of the present invention is an effective means of crosslinking the radiation crosslinkable polymer. The above examples did not overcure the polymer surface because they lasted longer than 10,000 minutes or showed at least some degree of flocculation failure in room temperature shear strength tests.

<Example 23-40>

Examples 23-40 illustrate the use of excimer lamps to crosslink various elastomers (polybutadiene, polyisoprene and triblock copolymers) combined with various radiation activated crosslinkers. Polybutadiene with an average molecular weight of 119,000 and polyisoprene with an average molecular weight of 263,000 were prepared using standard anionic polymerization techniques in cyclohexane with sec-butyl lithium as initiator. Kraton (trade name) 1107 is a styrene-isoprene-styrene triblock copolymer available from Shell Co. The elastomer was dissolved in toluene and combined with non-polymerizable crosslinkers of the amounts and types specified in Pouch 6. These 20 wt% solids blends were coated onto a 38 μm thick flexible primed poly (ethylene terephthalate) film and dried at 65 ° C. for 15 minutes to dry to the coating thicknesses listed in Table 6. The coated sample was then crosslinked using the XeCl excimer lamp system described in Examples 3-8. The total amount of energy irradiated to each sample was 800 mJ / cm 2. Table 6 describes the gel formation (in toluene) of each example measured by the method described above.

Example Elastomer Crosslinker Coating thickness (㎛) Gel formation (%) type Volume (wt%) 23 Polybutadiene C5EBP 0.13 13 28 23 Polybutadiene C5EBP 0.13 38 15 24 Polybutadiene C5EBP 0.26 13 29 24 Polybutadiene C5EBP 0.26 38 18 25 Polybutadiene TBA 0.14 13 53 25 Polybutadiene TBA 0.14 38 53 26 Polybutadiene TBA 0.28 13 77 26 Polybutadiene TBA 0.28 38 84 27 Polybutadiene TRIAZINE 0.12 13 50 27 Polybutadiene TRIAZINE 0.12 38 63 28 Polybutadiene TRIAZINE 0.23 13 78 28 Polybutadiene TRIAZINE 0.23 38 84 29 Polyisoprene C5EBP 0.10 13 41 29 Polyisoprene C5EBP 0.10 38 24 30 Polyisoprene C5EBP 0.20 13 67 30 Polyisoprene C5EBP 0.20 38 69 31 Polyisoprene TBA 0.11 13 77 31 Polyisoprene TBA 0.11 38 82 32 Polyisoprene TBA 0.23 13 77 32 Polyisoprene TBA 0.23 38 91 33 Polyisoprene TRIAZINE 0.09 13 33 33 Polyisoprene TRIAZINE 0.09 38 65 34 Polyisoprene TRIAZINE 0.18 13 79 34 Polyisoprene TRIAZINE 0.18 38 87 35 Kraton 1107 C5EBP 0.21 13 5 35 Kraton 1107 C5EBP 0.21 38 2 36 Kraton 1107 C5EBP 0.42 13 53 36 Kraton 1107 C5EBP 0.42 38 25 37 Kraton 1107 TBA 0.24 13 37 37 Kraton 1107 TBA 0.24 38 39 38 Kraton 1107 TBA 0.4 13 60 38 Kraton 1107 TBA 0.47 38 78 39 Kraton 1107 TRIAZINE 0.19 13 44 39 Kraton 1107 TRIAZINE 0.19 38 62 40 Kraton 1107 TRIAZINE 0.38 13 73 40 Kraton 1107 TRIAZINE 0.38 38 85

The above examples demonstrate that the methods of the present invention can be coated in various thicknesses for use in radiation crosslinkable compositions comprising varying amounts of various elastomers and various crosslinkers.

<Example 41 and Comparative Examples C-1 and C-2>

These examples compare the use of unsubstituted atraquinones, acetophenones and benzophenones as crosslinkers and a monochromatic radiation light source. A solvent based acrylic pressure sensitive adhesive was prepared, formulated with a crosslinker of the type and amount specified in Table 7 and knife coated to a dry thickness of about 25 μm on a 35 μm thick aziridine-primed poly (ethylene terephthalate) film And cured using the XeCl excimer lamp system following the procedure described in Examples 3-8. Room temperature shear strength was measured as described above and the results are shown in Table 7 below.

Example Crosslinker Energy dose (mJ / ㎠) Room temperature shear strength (min) type Volume (weight% 0 41 Anthraquinone 0.17 830 10000 41 Anthraquinone 0.17 1200 10000 41 Anthraquinone 0.17 1675 10000 C-1 Acetophenone 0.10 830 20 C-1 Acetophenone 0.10 1200 21 C-1 Acetophenone 0.10 1675 25 C-2 Benzophenone 0.15 830 21 C-2 Benzophenone 0.15 1200 22 C-2 Benzophenone 0.15 1675 25

Samples with shear strengths less than 10,000 minutes showed agglomeration failure. Although acetophenone and benzophenone are well known radiation activated crosslinkers, when used in the process of the invention, they result in minimal crosslinking as evidenced by low shear strength values. Anthraquinones, on the other hand, were very effective crosslinkers.

<Example 42>

Example 42 illustrates crosslinking a thermoplastic composition, poly (vinyl acetate) using a monochromatic radiation light source. Poly (vinyl acetate) having an average molecular weight of 500,000 was obtained from Aldrich Chemical Company and dissolved in chloroform to give a solution of 25% solids. The solution was then knife coated onto a 38 μm thick aziridine-primed poly (ethylene terephthalate) film and dried at 65 ° C. for 15 minutes to obtain a 25 μm thick coating, but did not adhere well to the film. The coated sample was then cured by stopping for 15 seconds under the output of the 308 nm XeCl excimer lamp mentioned in Examples 3-8. Total energy dose was 889 mJ / cm 2.

Gel formation was measured following the test procedure described above using chloroform as solvent. Gel formation was 0% and 16% in the control (ie no radiation exposure) and Example 42, respectively. This example demonstrates the usefulness of the method of the present invention for crosslinking thermoplastic polymers.

<Comparative Examples C-3 and C-4>

Comparative Examples C-3 and C-4 illustrate the use of conventional mercury lamp ultraviolet light sources to process compositions similar to Examples 20-22. Emulsion polymerized acrylic pressure sensitive adhesives were prepared using the types and amounts of non-polymerizable crosslinkers specified in vy 8 and following the procedures described in Examples 20-22. The coated sample was then cured using a Fusion Systems UV processor with full output of the "H" bulb, conveyor speed 22.9 m / min. The total energy irradiated to each sample is listed in Table 10 (measured in the UVA (320-390 nm) range), as well as the gel formation and room temperature shear strength measured by the method described above. All of the shear failures were essentially adhesive (ie, adhesive samples fell clean from the test panel), except for the examples that did not irradiate failed aggregation (energy dose = 0 mJ / cm 2).

Example Crosslinker Energy dose (mJ / ㎠) Room temperature shear strength (min) Gel formation (%) type Volume (wt%) C-3 C5EBP 0.2 0 64 29 C-3 C5EBP 0.2 160 666 77 C-3 C5EBP 0.2 320 449 83 C-3 C5EBP 0.2 480 1599 85 C-4 TBA 0.11 0 70 32 C-4 TBA 0.11 160 674 61 C-4 TBA 0.11 320 656 72 C-4 TBA 0.11 480 380 77

Compared to the examples treated with a monochromatic radiation light source, these comparative examples with similar gel formation demonstrated a significant reduction in shear strength and a change in shear failure modality. The decrease in shear strength may be due to undesirable luminescence, which is inherent to the mercury bulb with the typically broad spectral output used to make this example.

<Example 43 and Comparative Example C-5>

50 parts by weight of natural rubber (CV-60 Malaysian rubber (SMR) natural rubber), styrene-butadiene rubber (SBR 1011A, available from Ameripol / Synpol), aliphatic hydrocarbon tackifier (Escorez 1304, 50 parts by weight available from Exxon Chemical Co.), 1 part by weight of Irganox 1010 (polyfunctional hindered phenolic antioxidant, available from Ciba-Geigy Corporation) and C9EBP crosslinker in toluene 0.1 parts were combined to prepare a 25 wt% solvent natural rubber based adhesive composition.

The C9EBP crosslinker was prepared as C5EBP described in Example 1 except that 1,5-dibromopentane was replaced with an equimolar amount of 1,9-dibromononane. The adhesive composition was coated onto the primed polyester film and dried to 25 μm thickness. In Example 43, the coated sample was crosslinked using the XeCl excimer lamp system described in Examples 3-8 and in Comparative Example C-5 the coated film was PPG high intensity UV processor (PPG, Inc.). , Pittsburgh, Pennsylvania, both lamps were set to standard and the conveyor speed was 18.3 m / min (60 ft / min). (The energy dosage of Example C-5 was measured in the UVA range, and Example 43 was measured in the UVB range.) The total amount of energy irradiated to each sample in Table 9 and the gel formation (in toluene) measured by the method described above. ) And room temperature shear strength of the adhesive.

Example Energy dose (mJ / ㎠) Shear strength (min) Gel formation (%) 43 250 723 24 43 500 1436 45 43 750 2476 52 C-5 100 94 51 C-5 200 21 61 C-5 300 19 59

This example illustrates the use of an excimer lamp to process a natural rubber based pressure sensitive adhesive composition. As a good percentage of gel formation, the excimer material exhibited superior adhesion properties compared to the sample exposed to the mercury bulb.

<Example 44-50 and Comparative Example C-6-C-12>

These examples illustrate the advantage of using a blend of crosslinkers copolymerized with radiation crosslinkable polymers (ABP) and non-polymerizable crosslinkers (C5EBP) in tackified, suspension polymerized polyacrylate pressure sensitive adhesive formulations. . Polyacrylate suspension pressure sensitive adhesives A1-A4 were prepared according to the following method in accordance with US Pat. No. 4,833,179 to Young et al.

Into a 2 L split reaction flask equipped with a condenser, a thermometer, a nitrogen inlet, a motor driven stirrer and a temperature controlled heating mantle was first added the dispersion medium components described in Table 10 below and heated to 58 ° C. The dispersion medium was kept at this temperature, stirred and purged with nitrogen for 1 hour to remove oxygen. At this time, an excellent suspension was obtained by adding the oily premix charge described in Table 10 to the reactor with vigorous stirring (700 rpm). The reaction mixture was continuously purged with nitrogen during the course of the polymerization. Once the reaction reached exotherm, the reaction was allowed to proceed again at 75 ° C. for 2 hours and then the batch was cooled to room temperature.

Glue A1 Glue A2 Glue A3 Glue A4 Dispersion medium Deionized water (g) 610 610 695 695 Methacrylic acid (g) 20 20 20 20 ZnO (g) 2.5 2.5 2.5 2.5 Nalcoag (brand name) 1042 ¹ (g) 4.4 4.4 4.4 4.4 Oil phase Isooctyl Acrylate (g) 480 480 480 480 ABP (g) 0 0.125 0.25 0.5 IOTG ² (g) 0.25 0.25 0.25 0.25 VaZo (brand name) 67 ³ (g) 2.5 2.5 2.5 2.5 IV ⁴ (㎗ / g) 1.12 1.19 1.12 1.07 1 Colloidal silica available from Nalco Chemical Co. 2 isooctyl thioglycolate 3 2,2'-azobis (2-methylbutanenitrile), e. children. Thermal initiators available from E. I. du Pont de Nemours Company 4 inherent viscosity in ethyl acetate at 27 ° C

The reaction mixture was then dried to remove the suspension medium and the dried suspension polyacrylate was dissolved in 30% ethyl acetate concentration. 230 parts of polyacrylate solution were blended with 30 parts of Foral 85 (a rosin ester tackifying resin available from Hercules Inc.) and further amounts specified in Table 11 for Examples 43-49. C5EBP non-polymerizable crosslinker was blended. The tackified polyacrylate blend was coated with a dry thickness of 25 μm on a 38 μm thick aziridine primed poly (ethylene terephthalate) film and cured with a PPG high intensity UV processor (PPG Inc., Pittsburgh, Pennsylvania), Both lamps were set to standard and the conveyor speed was 18.3 m / min (60 ft / min). The total energy irradiated for each Example was 275 mJ / cm <2>. The room temperature shear strength and the high temperature shear strength of each sample cured by the method described above were measured except that the high temperature shear strength was measured by hanging a 500 g weight.

Example glue ABP (% by weight) C6EBP (% by weight) Shear strength (22 ℃, 1kg) Shear strength (70 ℃, 500 g) C-6 A1 0 0.096 384 384 44 A2 0.025 0.05 596 596 C-7 A1 0 0.146 386 386 45 A2 0.025 0.1 602 602 C-8 A1 0 0.246 205 205 46 A2 0.025 0.2 540 540 C-9 A1 0 0.142 362 362 47 A3 0.05 0.05 606 606 C-10 A1 0 0.192 248 248 48 A3 0.05 0.1 790 790 C-11 A1 0 0.292 183 183 49 A3 0.05 0.2 605 605 C-12 A1 0 0.284 270 270 50 A4 0.1 0.1 1552 10000 * Examples with shear strength less than 10,000 fail to agglomerate

Examples C-6 and 44, C-7 and 45, C-8 and 46, C-9 and 47, C-10 and 48, C-11 and 49, and C-12 and 50 are tackified suspension polymerized poly It has been demonstrated that the shear strength is greatly increased when the blend of polymerizable crosslinker and non-polymerizable crosslinker is used to cure the acrylate pressure sensitive adhesive formulation. In each example pair, the blend containing only the non-polymerizable crosslinker had lower shear strength than the corresponding example using equimolar amounts of the blended crosslinker. In addition, increasing the amount of non-polymerizable crosslinker without copolymeric crosslinker (C-12 in Comparative Example C-6) increases and may reduce shear strength. In contrast, the shear strength is increased when a relatively small amount of non-polymerizable radiation activated crosslinker is incorporated into the polymer.

<Example 51-59 and Comparative Example C-13-C-15>

Method of U.S. Patent No. Re 24,906 in Ulrich using 90 wt% isooctyl acrylate, 10 wt% acrylic acid, 0.1 wt% carbon tetrabromide and a copolymerizable crosslinker (ABP) in the amounts specified in Table 12 in ethyl acetate According to a series of acrylate pressure-sensitive adhesives (adhesives C-13-C-15).

Examples 51 to 59 were prepared by adding the C5EBP non-copolymerizable radiation activated crosslinker in the amounts specified in Table 12 to the corresponding comparative examples to dissolve in a 40 wt% solution of each adhesive in ethyl acetate. Then all examples were combined with 30 parts of Foral (trade name) 85 (rosin ester tackifying resin available from Hercules Inc.) per 100 parts of adhesive solution, and 38 μm thick aziridine primed poly (ethylene terephthalate) Knife coating on the film and drying at 65 ° C. for 15 minutes yielded a 25 μm thick coating. The coated sample was then cured using a Fusion Systems UV processor with full output of the "H" bulb, conveyor speed 30.5 m / min (100 ft / min). Three different amounts of UV radiation were irradiated to each sample and the total energy irradiated to each sample (measured in the UVA (320-390 nm) range) and room temperature shear strength measured by the method described above are listed in Table 12.

Example ABP (% by weight) C5EBP (% by weight) Shear strength (100 mJ / ㎠, 22 ° C, 1kg) Shear strength (300 mJ / ㎠, 22 ° C, 1kg) Shear strength (600 mJ / ㎠, 22 ° C, 1kg) C-13 0.025 0 18 20 27 51 0.025 0.05 20 27 41 52 0.025 0.1 22 37 74 53 0.025 0.2 26 86 770 C-14 0.05 0 22 30 45 54 0.05 0.05 24 41 74 55 0.05 0.1 28 72 252 56 0.05 0.2 29 127 3337 C-15 0.1 0 33 90 358 57 0.1 0.05 37 199 1149 58 0.1 0.1 40 355 10000+ 59 0.1 0.2 42 906 10000+

From the table it can be seen that adding a relatively small amount of non-polymerizable radiation activated crosslinker to a composition having a radiation crosslinkable polymer comprising a radiation activated crosslinker group can substantially increase the shear strength of the crosslinked system. have. Thus, the addition of non-polymerizable radiation activated crosslinkers in varying amounts to compositions with radiation crosslinkable polymers having radiation activated crosslinkable groups makes it easier and advantageous to crosslinked polymers having different crosslink density and properties. It can manufacture.

Appropriate variations and modifications are possible from the above disclosure without departing from the spirit or scope of the invention as defined in the claims.

Claims (58)

(a) (i) a radiation crosslinkable polymer having extractable hydrogen atoms; And (ii) providing a radiation crosslinkable composition comprising a non-polymerizable radiation activated crosslinker; (b) providing a monochromatic radiation light source having a wavelength sufficient to activate the crosslinker and crosslink the polymer; And (c) exposing the radiation crosslinkable composition to radiation emitted by a monochromatic radiation light source for a time sufficient to crosslink the polymer. The method of claim 1 wherein said radiation crosslinkable polymer is a thermoplastic polymer. The method of claim 2, wherein the thermoplastic polymer is polyolefin, polystyrene, vinyl plastic, polyacrylate, polymethacrylate, poly (vinyl ester), polyamide, polycarbonate, polyketone and the polymers from which the polymers can be derived. And a copolymer comprising a polymerization product of at least one monomer and a copolymerizable comonomer. The method of claim 1 wherein the radiation crosslinkable polymer is an elastomer. The method of claim 4, wherein the elastomer is polyurethane, polydiorganosiloxane, ABA type block copolymer, synthetic rubber, natural rubber, ethylene-vinyl monomer polymer, poly (vinyl ether), poly (vinyl ester), polyacrylate , Polymethacrylate and copolymers comprising a polymerization product of at least one monomer from which the elastomers can be derived and a copolymerizable comonomer. The method of claim 1 wherein the radiation crosslinkable polymer, except for the radiation activated crosslinker, substantially does not absorb radiation emitted by a monochromatic radiation light source. The method of claim 1, wherein the non-polymerizable radiation activated crosslinker is selected from the group consisting of anthraquinones, substituted anthraquinones, polyfunctional acetophenones, polyfunctional benzophenones, triazines, and mixtures thereof. The method of claim 1, wherein the monochromatic radiation light source is an excimer laser. The method of claim 1, wherein the monochromatic radiation light source is an excimer lamp. 10. The method of claim 9, wherein the excimer lamp is an XeCl lamp that emits radiation having a wavelength of about 308 nm. The method of claim 1, wherein the monochromatic radiation light source emits radiation having a wavelength of about 300 to 360 nm. The method of claim 1 wherein said crosslinking radiation crosslinkable composition is a pressure sensitive adhesive. (a) (i) a radiation crosslinkable polymer having extractable hydrogen atoms; And (ii) radiation comprising a radioactive crosslinking agent selected from the group consisting of anthraquinones, substituted anthraquinones, (polyfunctional or copolymerizable) acetophenones, (polyfunctional or copolymerizable) benzophenones, substituted triazines and blends thereof Providing a crosslinkable composition; (b) providing an XeCl excimer lamp that emits monochromatic radiation having a wavelength of about 308 nm to activate the crosslinker and crosslink the elastomer (the elastomer substantially does not absorb radiation emitted by the XeCl excimer lamp) ; And (c) exposing the radiation crosslinkable composition to radiation emitted by the XeCl excimer lamp for a time sufficient to crosslink the elastomer. The method of claim 13, wherein said crosslinked radiation crosslinkable composition is a pressure sensitive adhesive. 15. The method of claim 14, wherein the radiation activated crosslinker is combined with a radiation crosslinkable elastomer after formation of the elastomer. (a) (i) a radiation crosslinkable polymer having extractable hydrogen atoms; And (ii) providing a radiation crosslinkable composition comprising a radiation activated crosslinker; (b) providing a monochromatic radiation light source having a wavelength sufficient to activate the crosslinker and crosslink the polymer; And (c) exposing the radiation crosslinkable composition to radiation emitted by an excimer lamp for a time sufficient to crosslink the polymer. The method of claim 16 wherein the radiation crosslinkable polymer is a thermoplastic polymer. 18. The method of claim 17, wherein the thermoplastic polymer is polyolefin, polystyrene, vinyl plastic, polyacrylate, polymethacrylate, poly (vinyl ester), polyamide, polycarbonate, polyketone and the polymers from which the polymers can be derived. And a copolymer comprising a polymerization product of at least one monomer and a copolymerizable comonomer. The method of claim 16, wherein the radiation crosslinkable polymer is an elastomer. 20. The method of claim 19, wherein the elastomer is polyurethane, polydiorganosiloxane, ABA type block copolymer, synthetic rubber, natural rubber, ethylene-vinyl monomer polymer, poly (vinyl ether), poly (vinyl ester), polyacrylate , Polymethacrylate and copolymers comprising a polymerization product of at least one monomer from which the elastomers can be derived and a copolymerizable comonomer. The method of claim 16, wherein the radiation crosslinkable polymer, except for the radiation activated crosslinker, substantially does not absorb radiation emitted by the excimer lamp. 17. The method of claim 16, wherein said radiation activated crosslinker is copolymerized with a monomer which polymerizes to form a radiation crosslinkable polymer. 23. The method of claim 22, wherein said radiation activated crosslinker is 4-acryloxybenzophenone. The method of claim 16, wherein the radiation activated crosslinker is combined with the radiation crosslinkable polymer after formation of the polymer, or without reaction with the monomer from which the polymer is derived. The method of claim 16 wherein the radiation activated crosslinker is from the group consisting of anthraquinone, substituted anthraquinone, (polyfunctional or copolymerizable) acetophenone, (polyfunctional or copolymerizable) benzophenone, substituted triazine and blends thereof The method chosen. The method of claim 16, wherein the excimer lamp emits radiation having a wavelength of about 300 to 360 nm. The method of claim 16, wherein the excimer lamp is an XeCl lamp that emits radiation having a wavelength of about 308 nm. 17. The method of claim 16, wherein said crosslinked radiation crosslinkable composition is a pressure sensitive adhesive. (a) providing a suitable flexible web with a backing for a flexible pressure sensitive adhesive tape; (b) (i) a radiation crosslinkable polymer having extractable hydrogen atoms; And (ii) providing a radiation crosslinkable pressure sensitive adhesive composition comprising a radiation activated crosslinker; (c) applying a radiation crosslinkable pressure sensitive adhesive composition to at least a portion of one or more surfaces of the flexible web; (d) providing an excimer lamp capable of emitting monochromatic radiation having a wavelength sufficient to activate the crosslinker and crosslink the polymer; And (e) exposing the radiation crosslinkable pressure sensitive adhesive composition to radiation emitted by an excimer lamp for a time sufficient to crosslink the polymer to form a pressure sensitive adhesive tape. . 30. The method of claim 29, wherein said radiation crosslinkable polymer is a radiation crosslinkable elastomer. 33. The method of claim 30, wherein the radiation crosslinkable composition is applied to the flexible web by hot melt extrusion. 32. The method of claim 31, wherein the excimer lamp is an XeCl lamp that emits radiation having a wavelength of about 308 nm. The method of claim 1, comprising a radiation activated crosslinking group capable of extracting hydrogen when the radiation crosslinkable polymer is activated and capable of extracting hydrogen atoms when the non-polymerizable radiation activated crosslinker is activated. . 34. The method of claim 33, wherein the non-polymerizable radiation activated crosslinker is selected from the group consisting of non-polymerizable anthraquinones, non-polymerizable benzophenones, non-polymerizable acetophenones and mixtures thereof. (a) a radiation crosslinkable polymer having an extractable hydrogen atom and a radiation activated crosslinking group capable of extracting the hydrogen atom when activated; And (b) a radiation crosslinkable composition comprising a non-polymerizable radiation activated crosslinker capable of extracting hydrogen atoms when activated. 36. The radiation crosslinkable composition of claim 35, wherein said non-polymerizable radiation activated crosslinker is triazine. 36. The radiation crosslinking according to claim 35, wherein the non-polymerizable radiation activated crosslinker is selected from the group consisting of non-polymerizable anthraquinones, non-polymerizable benzophenones, non-polymerizable acetophenones and mixtures thereof. Composition. 38. The radiation crosslinkable composition of claim 37, wherein said non-polymerizable radiation activated crosslinker is selected from the group consisting of anthraquinone, t-butyl anthraquinone and 2-ethyl anthraquinone. 36. The radiation crosslinkable composition of claim 35, wherein said non-polymerizable radiation activated crosslinker is a multifunctional acetophenone or benzophenone corresponding to formula (I). <Formula I> (Wherein X is CH _3- ; Phenyl; Or substituted-phenyl; W represents -O-, -NH- or -S-; Z has no ester, amide, ketone, urethane, aliphatic, aromatic aralkyl, heteroaromatic and cycloaliphatic groups without ethers, thiols, aryl groups and hydrogen atoms inaccessible to the carbonyl groups of the above formula An organic spacer selected from the group consisting of benzyl groups; n represents an integer of 2 or more) 40. The radiation crosslinking composition according to claim 39, wherein X is phenyl, W is -O-, Z is an alkylene group having 2 to 12 carbon atoms, and n is 2. 36. The radiation crosslinkable composition according to claim 35, wherein said radiation crosslinkable polymer is polyacrylate or polymethacrylate. 36. The radiation crosslinkable composition of claim 35, wherein the radiation crosslinkable composition is derived from a polymerizable radiation activated crosslinker capable of extracting hydrogen atoms when the radiation activated crosslinking group is activated. 43. The radiation crosslinkable composition of claim 42, wherein said polymerizable radiation activated crosslinker is selected from the group consisting of polymerizable acetophenones, polymerizable benzophenones, polymerizable anthraquinones, and mixtures thereof. 43. The radiation crosslinkable composition according to claim 42, wherein said polymerizable radiation activated crosslinker is an acrylate functional aromatic ketone or a methacrylate functional aromatic ketone. 45. The radiation crosslinkable composition of claim 44, wherein said polymerizable radiation activated crosslinker is 4-acryloxybenzophenone. 42. The radiation crosslinkable composition of claim 41, further comprising a tackifying resin. 47. The radiation crosslinkable composition of claim 46, wherein said radiation crosslinkable polymer is in the form of beads. 48. The radiation crosslinkable composition of claim 47, wherein said radiation crosslinkable polymer is a suspension polymer. 42. The radiation crosslinkable composition of claim 41, wherein said radiation crosslinkable polymer is in the form of beads. A pressure-sensitive adhesive obtained by crosslinking the radiation crosslinkable composition of claim 35. A pressure sensitive adhesive coated article comprising a flexible web and the pressure sensitive adhesive layer of claim 50 overlying the main surface of the web. An article comprising a substrate and the layer of radiation crosslinkable composition of claim 35 on the substrate. 17. The non-polymerizable polymer according to claim 16, comprising a radiation activated crosslinking group capable of extracting hydrogen atoms when the radiation crosslinkable polymer is activated and capable of extracting hydrogen atoms when the radiation activated crosslinker is activated. And a radiation activated crosslinker. 30. The non-polymerizable polymer according to claim 29, comprising a radiation activated crosslinking group capable of extracting hydrogen atoms when the radiation crosslinkable polymer is activated and capable of extracting hydrogen atoms when the radiation activated crosslinker is activated. And a radiation activated crosslinker. 55. The method of claim 54, wherein said radiation crosslinkable polymer is polyacrylate or polymethacrylate. 56. The method of claim 55, wherein said radiation crosslinkable pressure sensitive adhesive composition further comprises a tackifying resin. 55. The method of claim 54, wherein the radiation crosslinkable polymer is in the form of suspension polymerized beads. 36. A method of crosslinking a polymer comprising providing a radiation crosslinkable composition according to claim 35 and exposing the radiation crosslinkable composition to a wavelength sufficient to crosslink the polymer and to UV or visible light for a sufficient time. .