Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L53/02—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers of vinyl-aromatic monomers and conjugated dienes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/07—Aldehydes; Ketones
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/17—Amines; Quaternary ammonium compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/36—Sulfur-, selenium-, or tellurium-containing compounds
  • C08K5/37—Thiols
  • C08K5/378—Thiols containing heterocyclic rings

Definitions

• the present invention relates to a UV-curable block copolymer composition. More specifically, the present invention relates to a UV-curable block copolymer composition for adhesives, sealants and coatings comprising an elastomeric block copolymer and at least one photoinitiator.
• a radiation curable rubber-based pressure-sensitive adhesive composition comprising at least one elastomeric rubber-based adhesive and a polythiol as the cross-linking agent.
• This composition can be cured by exposure to either electron beam radiation or UV irradiation. In the latter case, the additional presence of a photoinitiator is required.
• a cross-linking agent in particular a polythiol, is taught to be essential for obtaining a cured pressure-sensitive adhesive composition having good adhesion properties and elevated temperature shear.
• U.S. Patent No. 5,093,406 discloses a pressure-sensitive adhesive comprising a free radical cured product formed by e.g. UV curing of a mixture containing:
• an unsaturated elastomer component suitably comprising styrene-isoprene diblock and styrene-isoprene-styrene triblock copolymers,
• UV curing could be performed in an atmosphere, wherein oxygen is present in minor traces up to normal amounts, i.e. from about as little as 1 volume % to the normal value in air of about 21 volume %. From a commercial as well as an economical point of view it is highly attractive to operate in relatively oxygen rich atmospheres, as no expensive equipment and specific precautions are necessary to ensure an oxygen-free atmosphere.
• a block copolymer composition which can be effectively cured by exposure to UV radiation without using any cross-linking agent.
• a UV-curable hot melt adhesive, sealant or coating composition which does not require the presence of any cross-linking agent and which can be readily cured in an oxygen-containing atmosphere.
• the present invention relates to a UV-curable block copolymer composition
• a UV-curable block copolymer composition comprising:
• a block copolymer comprising at least one polymer block A derived from a monovinyl aromatic compound and at least one polymer block B derived from a conjugated diene, wherein: the content of monovinyl aromatic compound is in the range of from 5 to 50% by weight based on the total weight of block copolymer; each block A has an apparent molecular weight in the range of from 1,000 to 50,000; and each block B has an apparent molecular weight in the range of from 10,000 to 250,000; and
• Block copolymer is a multi-armed block copolymer and at least one photoinitiator is used containing a carbonyl group which is directly bonded to at least one aromatic ring structure.
• the block copolymer to be suitably used as component (a) in the composition according to the present invention in principle may be any block copolymer meeting the above mentioned requirements.
• Suitable block copolymers then include symmetric multi-armed block copolymers having a structure according to any one of the general formulas (AB) X, (BA) X, (ABA) X, (BAB) X as well as asymmetric or symetric multi-armed block copolymers of the general formula
• Common coupling agents are for instance divinyl benzene, silicon tetrachloride, gamma glycidoxy-propyl-trimethoxy-silane and dibromoethane.
• a preferred block copolymer has the general formula (AB) X with A and B as previously defined, n representing an integer in the range of from 3 to 20, preferably 4 to 12, and X representing a coupling agent residue, preferably the residue of divinyl benzene.
• the multi-armed block copolymers may be prepared by coupling living sequentially prepared intermediate polymer chains by using any conventional coupling techniques, such as e.g. disclosed in U.S. Patents Nos. 3,231,635; 3,431,323; 3,251,905; 3,390,207; 3,598,887 and 4,219,627. •
• the monovinyl aromatic compound may be selected from styrene, -methylstyrene, o-methylstyrene, p-methylstyrene, p-tert-butyl- styrene, 1,3-dimethy1styrene or mixtures thereof, of which styrene is most preferred.
• Suitable conjugated dienes to be used in the block copolymer of component (a) are 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene) , 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexa- diene or mixtures thereof, of which 1,3-butadiene, isoprene or mixtures thereof are the preferred monomers. Isoprene is most preferred.
• the block copolymer is a multi-armed styrene(S)-isoprene(I) or styrene- butadiene(B) block copolymer having a styrene content in the range of from 5 to 25% by weight.
• S-I block copolymer is KRATON D-1320X (KRATON is a trade mark) .
• the photoinitiator component (b) in the block copolymer composition according to the present invention may be composed of one or a combination of two or more photoinitiators.
• At least one of the photoinitiators used must be a compound containing a carbonyl group which is directly bonded to at least one aromatic ring structure. It is preferred that this photoinitiator is selected from the group consisting of: (1) at least one benzophenone of the general formula (I)
• R to R independently represent hydrogen or an alkyl group having from 1 to 4 carbon atoms, preferably methyl
• R and/or R represent in addition alkoxy of 1 to 4 carbon atoms and wherein n has a value of 0, 1 or 2, optionally in combination with at least one tertiary amine,
• R , R , R each may represent hydrogen, alkyl of 1-4 carbon atoms or an alkylthio group, having 1 to 4 carbon atoms, and
• ESACURE TZT 2,4,6-trimeth lbenzophenone
• IRGACURE 651 2,2-dimethoxy-l,2-diphenylethan-l-one
• UVECRYL 7100 UVECRYL is a trade mark
• Category (2) embraces compounds such as e.g. 2-methyl-l- [4- (methylthio)phenyl] -2-morpholinopropanone-l, commercially available as IRGACURE 907 (IRGACURE is a trade mark).
• An example of suitable mixtures is a mixture of 15% by weight of a mixture of 2-isopropylthioxanthone and 4-isopropylthioxanthone, and 85% by weight of a mixture of 2,4,6- trimethylbenzophenone and 4-methylbenzophenone.
• This mixture is commercially available under the trade name ESACURE X15.
• Photoinitiators of any one of the above categories (1), (2) and (3) may also be used in combination with other photoinitiators, such as e.g. UVECRYL P115. Particularly useful is a combination of benzophenone and said UVECRYL P115.
• the photoinitiator is selected from the group consisting of (i) benzophenone, (ii) a mixture of benzophenone and a tertiary amine containing a carbonyl group which is directly bonded to at least one aromatic ring, and (iii) 2-methyl-l- [4-(methylthio)phenyl] -2- morpholinopropanone-1. Of these 2-methyl-l- [4-(methylthio)phenyl] - 2-morpholinopropanone-l is most preferred.
• the photoinitiator should be present in an amount of from 0.5 to 30 parts by weight per 100 parts by weight of block copolymer (phr) to ensure sufficient cross-linking upon exposure to UV irradiation. It is preferred that the photoinitiator is present in an amount of from 5 to 20 phr.
• the UV irradiation used for cross-linking the block copolymer composition of the present invention in principle may be any UV source having an output spectra showing one or more peaks at wavelengths between 200 and 500 nanometer (nm) .
• Particularly suitable UV sources are Fusion bulb lamps (Fusion is a trade mark) having output maxima at 260-270 nm, 320 nm and 360 nm ("H" bulb), at 350-390 nm ("D" bulb) or at 400-430 nm (“V” bulb). Combinations of these Fusion bulb lamps may also be used.
• H and D bulb lamps linear power 300 W/inch are particularly useful, while a combination of D bulb and H bulb can also be suitably applied.
• the exposure to UV irradiation may be performed by any known method.
• a suitable method for instance is exposing a sample either in a layer obtained from a hot melt or in a layer obtained by solvent coating to UV irradiation by passing said sample at a certain speed (expressed in meters per minute, m/min) underneath the UV source.
• the exposure to irradiation may be repeated one or more times, e.g. by repeatedly passing the sample underneath the UV source or by passing the sample underneath two or more lamps positioned in series, in order to accomplish sufficient curing.
• the UV curable block copolymer composition according to the present invention can be suitably applied in hot melt as well as solvent adhesive compositions, sealants and coatings.
• common additives such as a tackifying resin, a softening oil and an antioxidant may also be present.
• a suitable hot melt adhesive composition may comprise in addition to the block copolymer composition of the present invention:
• Suitable poly(conjugated diene) compatible resins are tackifying resins and liquid resins, such as e.g. polyterpene resins, polyindene resins, rosin esters, hydrogenated rosins, alpha-pinene resins, beta-pinene resins, hydrocarbon resins of petroleum origin and phenolic resins.
• tackifying resins and liquid resins such as e.g. polyterpene resins, polyindene resins, rosin esters, hydrogenated rosins, alpha-pinene resins, beta-pinene resins, hydrocarbon resins of petroleum origin and phenolic resins.
• examples are REGALITE R91, R101, R 125 and S260 (REGALITE is a trade mark), ESCOREZ 1310 and 5380 (ESCOREZ is a trade mark) , WINGTACK 95 (WINGTACK is a trade mark), FORAL 85 and 105 (FORAL is a trade mark), PICCOL
• PICCOTAC 95E PICCOTAC 95E.
• resins having a low degree of unsaturation such as REGALITE R91, R101 or R 125, is preferred.
• plasticizer mineral oils both naphthenic and paraffinic oils, or low molecular weight polybutylene polymers may be used.
• suitable plasticizers are SHELLFLEX 371 and 451 and TUFFLO 6204 (naphthenic oils), TUFFLO 6056 (paraffinic oil) and the polybutylenes HYVIS 200, NAPVIS 30 and NAPVIS D-10.
• SHELLFLEX, TUFFLO, HYVIS and NAPVIS are trade marks. Also very useful are REGALREZ 1018 (REGALREZ is a trademark) , ONDINA 68 (ONDINA is a trade mark) and V-OIL 7047 (V-OIL is a trade mark) .
• any antioxidant commonly applied in adhesive formulations may be used.
• An example of such antioxidant is the phenolic compound IRGANOX 1010 (IRGANOX is a trade mark) .
• other additives such as endblock compatible resins, UV stabilizers, fillers, flame retarders and the like, may be present as well depending on the specific conditions under which the hot melt adhesive composition is to be used.
• Hot melt adhesive compositions, sealant compositions and coating compositions comprising the UV-curable block copolymer composition described hereinbefore also form part of the present invention. The same applies for cured compositions obtained by exposing said adhesive, sealant and coating compositions to UV irradiation.
• the photoinitiators used in the examples have been abbreviated as follows: TZT ESACURE TZT 1184 IRGACURE 184
• a formulation consisting of a multi-armed S-I block copolymer, two polyisoprene compatible resins and an antioxidant was prepared by intimately mixing:
• KRATON D-1320X is a multi-armed block copolymer consisting of S-I block copolymer arms.
• the coupling agent used is divinylbenzene. It has a polystyrene content of 10% by weight.
• the apparent molecular weight of each S-I arm is about 100,000 and the peak molecular weight of each polystyrene block is about 11,000.
• the total number of arms may vary from 6 to 100 and usually is between 6 and 40.
• Example 2 The same base formulation as used in Example 1 was employed for the evaluation of the effect on the SAFT values of the speed with which a formulation is passed underneath various UV sources.
• the photoinitiator used was IRGACURE 907 in an amount of 5 pbw per 100 pbw of block copolymer.
• D+V, D+H and D+D the exposure to the irradiation originating from the second lamp took place in air, so without applying a nitrogen flow.
• Table II the SAFT values listed are given in °C. TABLE II SAFT values after UV curing at different speeds and with different UV lamps
• the H and V bulb had a linear power of 300 W/inch (120 W/cm)
• Example 2 The same formulation as used in Example 2 was employed and exposed to irradiation using a Fusion H bulb lamp (F300) with and without a nitrogen flow. The formulation was exposed to irradiation by passing it at different speeds once and twice underneath the H bulb as well as by passing it once underneath two H bulb lamps positioned in series. The SAFT values (in °C) were measured after each pass. The results are listed in table V.
• compositions A to G were cured by passing them three times (lp, 2p, 3p) at a speed of 5 m/min underneath a Fusion D bulb lamp.
• the SAFT values, of some compositions the Holding Power at 95 "C (HP 95°C) and the peel adhesion 180° were determined after each pass. The results are listed in table VI.
• a formulation comprising: KRATON D-1320 X 100 phr
• IRGANOX 1010 1 phr was tested with irradiation from another UV-lamp, the H-bulb, which substantially emits the conventional mercury spectrum.
• M./Min. 1 pass 2 passes 1 pass with without 1with without without
• Adhesive Composition (3) (4) (5) (6)
• the photoinitiators IRGACURE 651 and 907 were both tested in compositions, containing the same other ingredients as specified in Table XII, i.e. formulation 4 is based on A oolymer with IRGACURE 651, formulation 5 is based on B polymer with IRGACURE 651, formulation 6 is based on B with IRGACURE 907.
• Copolymer (xlOOO) (xlOOO) (xlOOO) form styrene (1,2-add) of S of S-B content content block block
• films of 22 micron thickness were prepared from a solvent based formulation (40% in toluene) by casting.
• the films were irradiated under a Fusion D bulb lamp in 1 pass and 2 passes respectively with a speed of 5 m/min, and the gel content was analyzed.
• Photosensitive compositions were prepared from the block copolymer identified hereinbefore as A (100 parts by weight) , IRGANOX 1010 (1 part by weight) and varying amounts of photosensitizer IRGACURE 651, as listed in the Table XX.
• Films of 22 micron thickness were prepared from these compositions and the films were irradiated as described under
• Example 8(i) The percentage .gel after irradiation was determined.
• Composition block Copol./AO/PS 1 pass 2 passes

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Macromonomer-Based Addition Polymer (AREA)
• Polymerisation Methods In General (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Paints Or Removers (AREA)
• Graft Or Block Polymers (AREA)

Priority Applications (9)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26133915

Family Applications (1)

Country Status (13)

Cited By (7)

Families Citing this family (4)

Citations (2)

Family Cites Families (1)

• 1994
  • 1994-07-12 CA CA002167185A patent/CA2167185A1/en not_active Abandoned
  • 1994-07-12 DE DE69413823T patent/DE69413823T2/de not_active Expired - Lifetime
  • 1994-07-12 AU AU74932/94A patent/AU688361B2/en not_active Ceased
  • 1994-07-12 BR BR9407055A patent/BR9407055A/pt not_active IP Right Cessation
  • 1994-07-12 JP JP50434695A patent/JP3420240B2/ja not_active Expired - Lifetime
  • 1994-07-12 WO PCT/EP1994/002314 patent/WO1995002640A1/en active IP Right Grant
  • 1994-07-12 MX MX9405293A patent/MX9405293A/es not_active IP Right Cessation
  • 1994-07-12 CN CN94192754A patent/CN1067416C/zh not_active Expired - Lifetime
  • 1994-07-12 DK DK94924758T patent/DK0708802T3/da active
  • 1994-07-12 ES ES94924758T patent/ES2122320T3/es not_active Expired - Lifetime
  • 1994-07-12 AT AT94924758T patent/ATE171972T1/de not_active IP Right Cessation
• 1996
  • 1996-01-11 NO NO19960130A patent/NO311137B1/no not_active IP Right Cessation
  • 1996-01-11 FI FI960137A patent/FI960137A0/fi unknown

Patent Citations (2)

Also Published As

Similar Documents

Legal Events