JP2001512762A - Releasable adhesive containing a binder containing a di- or polysulfide bond as a basic component - Google Patents

Abstract

  (57) [Summary] According to the present invention, a releasable adhesive composition can be formulated based on a binder containing at least one structural component containing di- or polysulfide bonds. These adhesives can be cured according to a conventional method as a two-component adhesive or a one-component thermosetting adhesive. Adhesive compositions of this type can be dissociated again using a cleavage agent based on a mercapto compound or a reducing agent to which a swelling agent is optionally added. This allows the structural components bonded together to be separated again by chemical means at the joint.

Description

DETAILED DESCRIPTION OF THE INVENTION

TECHNICAL FIELD The present invention relates to an adhesive composition based on a binder containing disulfide or polysulfide bonds, which is suitable for forming a releasable adhesive layer. The invention also relates to a cleaving agent for releasing the adhesive layer and a method for forming and releasing the adhesive layer.

BACKGROUND OF THE INVENTION In many industrial fields, particularly in the metalworking industry (eg, the motor industry),
The same or different metal and non-metallic substrates are increasingly joined together by adhesives or sealants in the automotive and related raw material supply industries, or in the manufacture of machines and household appliances, and in the construction industry. .
This method of joining structural components is increasingly replacing conventional joining methods (e.g., riveting, screwing or welding) because bonding / sealing offers many technical advantages. In contrast to conventional joining methods (eg, welding, riveting, screwing), the problems of dissociation of the adhesive layer and separation of the bound components have not been sufficiently solved.

[0003] EP-A-735121 describes an adhesive film profile for a residue-free and damage-free detachable adhesive bond, consisting of a double-sided adhesive film having gripping tabs projecting from the adhesive film. (The adhesive bond can be separated by pulling in the plane direction at the tab). However, this method is only applicable when the adhesive layer of the adhesive film is a contact adhesive. Unfortunately,
The adhesive bond obtained by this method has very low tensile strength and peel strength,
This method can only be used to secure small items (such as hooks) in the home.

[0004] DE-A-4 230 116 describes adhesive compositions containing a mixture of an aliphatic polyol and an aromatic dianhydride. The adhesive composition is prepared in a water / alkali system, more specifically in a soda solution or an alkali hydroxide,
It is possible to release the adhesive layer. According to this document, these water / alkali soluble adhesives are suitable for the efficient production of magnetic components and other small parts, and this adhesive is used for temporary bonding during material processing. Only used. A very similar adhesive is also known as a label adhesive,
Labels can be removed from beverage bottles and similar containers in aqueous or aqueous / alkaline media.

[0005] German Patent Application No. 4238108 describes an adhesive for floor coverings and a method for removing bonded floor coverings using microwave energy. For this purpose, the adhesive is said to be conductive and can be softened by the microwave unit. Solvent-free contact adhesives based on (aqueous) polymer dispersions containing copper or aluminum powder are specifically mentioned. According to the teachings of this document, the adhesive securing the floor covering piece by softening the adhesive layer by application of a microwave unit and manually removing the floor covering piece after softening of the adhesive layer. The layers can be dissociated.

[0006] WO 94/12582 describes a contact adhesive based on aqueous polymer dispersions, adhesives dissolved in organic solvents, tackifiers and finishes. This contact adhesive has a constant adhesive strength over a wide temperature range, and can mechanically separate the adhesive layer. According to this document, this adhesive is
Suitable for bonding decorative surface components and / or insulators, such as insulating materials or plastic films.

European Patent Application Publication No. 521825 describes a releasable adhesive layer when the parts to be joined together are joined by a piece of adhesive applied between them. The adhesive strip includes a flat thermoplastic separating element. When the adhesive layer is heated by electric current or heat, this thermoplastic separating layer softens and allows the parts joined together to be mechanically separated. According to this document, these detachable adhesive layers are suitable for direct glass window mounting in automobile manufacture.

[0008] DE-A 19 526 351 describes a release gel for lacquers, paints and adhesives based on organic solvents containing additives consisting of wetting agents, thickeners and other customary auxiliaries. Is described. The use of gels as removers in the removal of two-component lacquers is mentioned as a specific application. This mixture is
Although it is described that it can be used for a component adhesive, there is no specific reference to the release of the adhesive layer.

A paper entitled “Reversible Crosslinking in Epoxy Resins” [Journal of Applied Poly
Mer Science, 39 , 1429-1457 (1990)], VR Sastri and GC Tesoro describe epoxy resins having various epoxy equivalents crosslinked with 4,4'-dithioaniline. It has been described. It is described that the crosslinked resin is ground into particles having a size of 600 μm. The resulting fine particle powder is then refluxed in a solution of diglyme, hydrochloric acid and tributylphosphine until the ground resin has dissolved. There is no specific reference in this document to a detachable adhesive layer.

The detachable adhesive layers described in the prior art documents mentioned above all have very narrow fields of application. In particular, there is no adhesive composition that combines easy and quick release or easy removal of the adhesive layer with high bonding strength and stability against external influences. Accordingly, it is an object of the present invention to provide an adhesive composition that allows the adhesive layer to be quickly released, while at the same time ensuring high strength and stability of the bond during the service life of the bonded part. Met.

DISCLOSURE OF THE INVENTION [0011] The solution to the above problems provided by the present invention is defined in the claims, but essentially comprises a bond containing at least one disulfide or polysulfide bond per molecule. It is an object of the present invention to provide an adhesive composition based on an agent and a cleaving agent which can cleave disulfide or polysulfide bonds to separate the bonded parts.

[0012] The present invention also relates to a method for forming and releasing an adhesive layer comprising substantially the following steps. Assembling and joining parts using an adhesive composition comprising a binder containing at least one structural component containing at least one disulfide or polysulfide bond per molecule. The adhesive composition can be a one-component system that can be used directly by a user without mixing the components. However, it can also consist of two or more components stored independently of one another and mixed together only immediately before use. -Cure the adhesive at room temperature. That is, in the case of a multi-component system, the individual components are allowed to react with one another, or in the case of a one-component system, by curing with atmospheric moisture and / or atmospheric oxygen. The adhesive can also be cured by heat, UV light or electron beam. The specific curing method used is
It is governed by the crosslinking mechanism of the components. -Dissociate the bond by application of the cleaving agent or by immersion in the cleaving agent. -If desired, the dissociation process of the bond can be further accelerated by heating the bonded component or adhesive layer. If desired, a mechanical load can be applied to the adhesive layer to further facilitate the separation of the joined components.

(Best Mode for Carrying Out the Invention) That is, an important component of the structural component of the binder according to the present invention is a compound containing at least one disulfide or polysulfide bond represented by the following general formula:

Embedded image XR ¹ —S _x —R ² —Y (I) wherein R ¹ and R ² are branched alkyl and / or aryl groups, ie in many simple cases C _{2 -8 is an} alkylene group or a bifunctional aromatic group, such as 1,2-, 1,3- or 1,4-phenylene, diphenylene, naphthylene or a similar aromatic group; Independently of one another, may be any reactive functional group, preferably a primary or secondary amino group, a hydroxyl group, a carboxyl group, and X and Y are mercapto groups, epoxy groups, isocyanate groups, alkoxy groups It may be a silyl group or even an olefinic double bond, in which case R ¹ and / or R ² may be substituted by a covalent bond, and x is an integer from 2 to 8 In a particularly preferred embodiment It has a value of 2].

Examples of structural components of formula I containing an olefinic double bond can be prepared as follows. That is, in the first step, dithiodialcohol or dithiodiamine is reacted with diisocyanate to generate an isocyanate-terminated disulfide compound. That is, the diisocyanate component is used in a larger amount than the stoichiometric amount with respect to the dithiodialcohol or dithiodiamine component. In a second step, these NCO-terminated disulfide compounds are reacted with hydroxyalkyl acrylate or hydroxyalkyl methacrylate to form (meth) acrylate-terminated disulfide bonds. Suitable hydroxyalkyl (meth)
Examples of acrylates are the corresponding ethyl, propyl or butyl compounds. The resulting (meth) acrylate-terminated disulfide compound can be combined, as usual, with the corresponding copolymerizable compound and can be cured by a radical or ionic mechanism. Examples of these known copolymerizable compounds can be found in German Patent No. 19545123, column 5, lines 24-47. The comonomers listed in this document are an essential part of the present invention.

Similarly, epoxy-functionalized disulfides or polysulfides can be prepared from NCO-terminated disulfide or polysulfide compounds by reaction with hydroxy-functional epoxy compounds. Examples of such hydroxy-functional epoxides are glycidol and various glycidyl ethers of bisphenol A, which usually have a free hydroxy group.

Similarly, an epoxy-functionalized disulfide or polysulfide compound can be
It can be obtained by reacting an OOH-terminated disulfide or polysulfide compound with a bifunctional or polyfunctional epoxy compound.

The corresponding alkoxysilane-terminated products can be prepared from NCO-terminated disulfides or polysulfides by reaction with amino-functional alkoxysilanes.

Particularly preferred structural components of the formula I are cystamine, dithiodiethanol and dithiodipropionic acid.

Another structural component of the adhesive composition of the present invention can consist of one or more compounds represented by the following general formula:

X—R ³ —Y (II) wherein X and Y may be the same as defined above, and R ³ is at least a difunctional organic group. The component of formula II is usually a so-called prepolymer compound,
It has a molecular weight in the range of 20,000, preferably 700 to 10,000.

Particularly preferred components of formula II are epoxy resins, isocyanate-containing polyurethane prepolymers, novolak resins, phenolic resins or unsaturated polyesters. However, it is also possible for the components of the formula II to be replaced by the above-mentioned copolymerizable olefinically unsaturated compounds.

Suitable epoxy resins are polyols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, pentane
-1,5-diol, hexane-1,2,6-triol, glycerol, 2,2-bis-
Various polyglycidyl ethers of (4-hydroxycyclohexyl) propane and polyalkylene glycols (eg, polypropylene glycol). Other suitable epoxy resins are aliphatic or aromatic polycarboxylic acids such as oxalic acid,
Polyglycidyl esters of succinic acid, glutaric acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid and dimer fatty acids. Other suitable epoxy compounds are
Polyphenols such as bisphenol A, 1,1-bis- (4-hydroxyphenyl) ethane, 1,1-bis- (4-hydroxyphenyl) isobutane, 1,5-dihydroxynaphthalene and polyglycidyl ether of novolak resin is there. Preferred epoxy compounds include relatively high molecular weight resins, such as chain-extended diglycidyl ethers of bisphenol A, diglycidyl ethers of bisphenol A with dimer fatty acids and bisphenol A glycidyl ether terminated polyether polyurethanes. Adducts of epoxy resins with carboxy, amino and / or hydroxy functional nitrile rubbers (Hycar type) can also be used as epoxy components.

[0022] Isocyanate-containing polyurethane prepolymers are prepared from aromatic, cycloaliphatic or aliphatic polyisocyanates and diols and / or polyols.

The following are examples of suitable aromatic polyisocyanates: any isomer of toluene diisocyanate (TDI) (in the form of a pure isomer or a mixture of several isomers), naphthalene -1,5-diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), diphenylmethane-2,4'-diisocyanate, and mixtures of 4,4'-diphenylmethane diisocyanate with the 2,4'-isomer or with these It is a mixture with a higher functional oligomer (so-called crude MDI). Examples of suitable cycloaliphatic polyisocyanates are the hydrogenation products of the above aromatic di isocyanate, for example, 4,4'-dicyclohexylmethane methane diisocyanate (H ₁₂ MDI), 1- isocyanatomethyl -3 -Isocyanato-1
, 5,5-Trimethylcyclohexane (isophorone diisocyanate, IPDI), cyclohexane-1,4-diisocyanate, hydrogenated xylylene diisocyanate (
H ₆ XDI), m- or p-tetramethylxylene diisocyanate (m-TMXD
I, p-TMXDI) and dimer fatty acid diisocyanates. Examples of aliphatic polyisocyanates include hexane-1,6-diisocyanate (HDI), 1,6-diisocyanato-2,2,4-trimethylhexane, 1,6-diisocyanato-2,4,4-
Trimethylhexane, butane-1,4-diisocyanate and 1,12-dodecane diisocyanate (C ₁₂ DI).

Preferred diols and / or polyols are liquid polyhydroxy compounds containing 2 or 3 hydroxyl groups per molecule, for example 20
Difunctional and / or trifunctional polypropylene glycols having a molecular weight in the range from 0 to 6,000, preferably in the range from 400 to 3,000. Statistical and / or block copolymers of ethylene oxide and propylene oxide can also be used. Another group of preferred polyethers is polytetramethylene glycol, which is obtained, for example, by acid polymerization of tetrahydrofuran, whose molecular weight ranges from 200 to 6,000, preferably from 400 to 4,000.
Range.

Other suitable polyols are liquid polyesters, which include dicarboxylic or tricarboxylic acids (eg, adipic acid, sebacic acid, glutaric acid, azelaic acid, hexahydrophthalic acid or phthalic acid). Molecular weight diols or triols (eg, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, butane-1,4-diol, hexane-1,6-diol, decane-1,10-diol, glycerol Or trimethylolpropane).

Another group of polyols that can be used in accordance with the present invention are polyesters based on ε-caprolactone, also known as “polycaprolactone”.

However, it is also possible to use polyester polyols of oil chemistry origin. The oleochemical polyester polyols include, for example, the complete ring opening of epoxidized triglycerides of a fatty acid mixture comprising at least partially olefinically unsaturated fatty acids with one or more alcohols containing 1 to 12 carbon atoms, and Subsequent partial transesterification of the triglyceride derivative can be obtained by producing an alkyl ester polyol containing from 1 to 12 carbon atoms in the alkyl group (see, for example, DE-A-3626223). Other suitable polyols are polycarbonate polyols and dimer diols (Henkel KGaA) and castor oil and its derivatives. For example, a hydroxy-functional polybutadiene of the type marketed as "poly-bd" can be used as the polyol for the compositions of the present invention.

In addition, the low molecular weight hydroxy-functional (meth) acrylate polymers disclosed in EP-A-205846 can be used as polyols.

Suitable novolak resins or phenolic resins are the widely known condensation products of phenol and / or resorcinol with formaldehyde. Co-condensates with terpenes, ie terpene / phenolic resins, can also be used.

Basically, the adhesive composition of the present invention contains at least one structural component represented by the general formula I containing a disulfide or polysulfide bond and at least one structural component represented by the general formula II. These two components must, of course, be compatible with each other. The following are examples of useful combinations.

[Table 1]

However, a suitable combination of structural components of formulas I and II is sulfur and / or
Alternatively, the binder may be a liquid rubber-based binder polymerized using a vulcanization system containing a sulfur compound. Specific examples of liquid rubbers used for this purpose are listed on page 5 of International Patent Application Publication No. WO 96/36660. Suitable sulfur-containing vulcanizing agents for this purpose are disclosed in WO 96/36660, page 6, last paragraph to page 7, first paragraph.

[0032] The adhesive composition of the present invention may additionally contain a plasticizer. fundamentally,
Any conventional plasticizer can be used, including, for example, C _6-14 dialkyl esters of phthalic acid, alkyl benzyl esters of phthalic acid, benzoates of di- or trifunctional polyols, such as dipropylene glycol dibenzoate Phenol and cresol alkyl sulfonates, aryl phosphates, alkyl phosphates, C _6-14 diesters of aliphatic C _4-10 dicarboxylic acids and / or polymeric plasticizers based on diols and dicarboxylic acids and mixtures thereof.

The present adhesive composition may also contain a filler in an amount of 5 to 60% by weight. Examples of suitable fillers are limestone powder, natural ground chalk (calcium or magnesium carbonate), precipitated chalk, barite, talcum, mica, clay, carbon black and pigments, such as titanium dioxide or iron oxide. .

The adhesives of the present invention include other auxiliaries and additives such as anti-gelling agents and stabilizers, flow aids such as fumed silica, bentone, castor oil derivatives, and catalysts, accelerators and If desired, a tackifier resin can be further contained.

The adhesive layer according to the present invention is dissociated using a cleavage agent. The function of the cleavage agent is to cleave disulfide or polysulfide bonds introduced into the polymer system.
The cleavage agent may be either a mercapto compound (optionally adding an inorganic or organic basic compound or other promoter) or a reducing agent (for reductive cleavage of the S--S bond of the adhesive). It is. The cleaving agent may optionally contain other auxiliaries, more particularly swelling agents, which facilitate and facilitate the action of the cleaving agent by softening the crosslinked polymer matrix of the adhesive system.

Specific examples of mercapto compounds suitable for use in accordance with the present invention include mercaptocarboxylic acids, esters or salts thereof, elemental sulfur, mercaptobenzoxazole, mercaptobenzothiazole, mercaptoamines such as 2-mercaptoethylamine, mercaptoalcohol, For example, 2-mercaptoethanol, dithiothreitol or sodium thiosulfate. Examples of basic compounds are alkali metal hydroxides such as sodium hydroxide, potassium hydroxide or organic amines. Specific examples of the reducing agent are trialkyl or triarylphosphine.

The swelling agent used is usually a solvent and / or a solvent for the above-mentioned cleavage agent and / or accelerator.
Or an organic solvent that can also act as a diluent. Examples of suitable organic solvents are alcohols such as methanol, ethanol, isopropanol or higher alcohols, alkyl acetates, more particularly ethyl acetate or butyl acetate. Other suitable solvents are polar solvents such as ethers, more particularly cyclic ethers such as 1,4-dioxane or tetrahydrofuran, and also glycol ethers or glycol ether esters, ketones, dimethylsulfoxide or N-methylpyrrolidone (NMP ). Basically, chlorinated hydrocarbons, preferably dichloromethane, are also suitable, but they are not as easy to use as before because of their toxicity and pollution control problems.

The release properties of the adhesive layer can be further improved by specially designed structural elements. This includes, for example, the insertion of gauze or other absorbent material into the adhesive layer.

In another embodiment, the cleaving agent can be added to the adhesive formulation in an inert form at room temperature. In this case, dissociation of the adhesive layer can occur after activating the cleavage agent at an elevated temperature.

Another embodiment of the detachable adhesive layer according to the invention is characterized by the use of conventional prior art adhesives for assembly and the use of detachable primers. It is well known that in many adhesive bonds, an adhesion promoting primer must be applied to at least one of the substrates to be joined. According to the invention, this primer can contain a structural component of the general formula I. In this way, the primer layer can be dissociated by the cleavage agent of the present invention, and the bonded parts can be separated according to the present invention without subjecting the adhesive itself to the cleavage reaction, on the same principle of operation as described above. .

The following examples are intended to illustrate the invention and do not limit the scope of the invention in any way. Commercially available adhesives or sealants were used directly in some of these examples. In other examples, only structural components of general formula I were added to commercially available adhesive components.

The test for examining the dissociation behavior according to the present invention was performed by two methods. In the first, an adhesive or sealant was applied to the steel sheet in layers, which were first cured. The cured material was then treated with various cleavage agents of the present invention and then tested for its effectiveness.

In another embodiment, the steel sheets were bonded using the releasable adhesives of the present invention, then the bond was cured and its tensile shear strength was tested. The dissociation test was performed by exposing the bonded steel sheet to the cleavage agent of the present invention. The test sample was placed in a 100 ml gas jar filled with the corresponding solution. The time for the bond to dissociate was measured. All amounts given are parts by weight unless otherwise indicated. Tensile shear strength was expressed in N / mm ² and the type of failure was also indicated (AF = adhesive layer failure).

Example Steel plate used DIN 1541 / ST 1203, format 1.5 mm × 25 mm × 100 mm
(Or sand blasting, or rubbed with emery cloth; degreased with CH ₂ Cl _2).

[0045] by the joint sealing compound thioglycolic acid methyl ester, the dissociation terrorism stat (Terostat) 1SE junction sealing compound based on polysulfide (GSC), was applied to a steel plate by a spatula at the recirculation air drying cabinet 2 Cured at time / 150 ° C. and left at room temperature for 4 days. The following materials dissociated the cured material (paste-like after 1-2 minutes)
: Thioglycolic acid methyl ester / ethyl acetate in a ratio of 1: 1, 1:10 and 1: 100.

Modification of Epoxides with Epoxy Adhesive Telostat (Epoxy Formula I) A mixture of Epikote 828 and Telostat 998R or 998B in a 1: 1 and 10: 1 ratio was prepared using a 5% catalyst [DMP: 2 , 4,6-Tris- (dimethylaminomethyl) phenol] at room temperature for 24 hours. All samples dissociated minutes after the addition of thioglycolic acid methyl ester. Tributylphosphine had a slightly weaker effect.

Bond dissociation by introducing a cleavage agent into the adhesive formulation before curing (epoxy formulation II) 2% and 10% of the cleavage agent (2-mercaptobenzothiazole, 2-mercaptobenzoxazole, mercapto Succinic acid, sulfur, sodium thioglycolate) were added to a 1: 2: 3 mixture of Thiokol LP3, Capcure 3-800, ChemRes E20 (with 5% DMP as catalyst). ). After curing (24 hours / room temperature), changes were observed on a Kofler heating bench. The adhesive containing 10% added sulfur softened at 110-120 ° C and the other adhesive mixtures became brittle.

Bond dissociation by epoxy / dithiodipropionic acid (Epoxy formulation III) Chemless E20 (3.6 g) and dithiodipropionic acid (2.1 g) are mixed in an aluminum dish and the resulting mixture is used. The steel plates were bonded (bonding area 20 mm × 25 mm). The adhesive layer was adjusted to 0.67 mm with the inserted copper wire. The steel sheets are held together with clothespins and the adhesive is applied in a recirculating air drying cabinet for 30 minutes /
Cured at 180 ° C. The bond was dissociated in ethanol containing 4% triethylamine (blank solution) and ethanol / thiodiglycolic acid methyl ester 90/10 containing 4% triethylamine (bond dissociation solution). The blank sample dissociated after about 20 days, after 2 hours in the reagent solution and after 5 minutes under peel stress.

Detachable epoxy-based adhesive-acid / heat-cured (epoxy formulation IIIa) Chemless E20 (1 mole) is mixed with dithiodipropionic acid (1 mole),
Cured for 30 minutes at 180 ° C. Tensile shear strength in bonding steel sheets is about 5N /
It was mm ^2. The Shore A hardness (contact time 60 seconds) was 95. After treatment with the cleavage agent, the adhesive became brittle or viscous. The measuring needle penetrated the dissociated adhesive.

The dicyanodiamide dissociable epoxy adhesive cured with imidazole curing (epoxy coordination compound IIIb) prepolymer I (structural components I) of 6.84 g 0.20 g of dicyanodiamide 0.03 g: 40 Min / 140 ° C. Preparation of prepolymer I: Dithiodipropionic acid is reacted with Chemless E20 in a molar ratio of 1: 2 (2 hours / 120 ° C .; 0.25% triphenylphosphine as catalyst). The tensile shear strength / bond dissociation behavior (after curing and storage: 7 days at room temperature) was as follows.

[Table 2]

The dicyanodiamide dissociable epoxy adhesive cured with (epoxy coordination compound IIIc) DGEBA alkyl phenyl glycidyl ether 0.67g of 0.2 g (diglycidyl ether / bisphenol A adduct) Ke Seamless E20 0.3 g of butanediol glycidyl ether 5.95 g of prepolymer I 0.52 g of dicyanodiamide 1.73 g of Muskovit, mica quartz 0.5 g of Aerosil R805 0.03 g of N, N -Dimethyl-N'-phenylurea 0.1 g of carbon black Curing agent component: epoxy prepolymer with dithiopropionic acid (structural component I) The tensile shear strength / bond dissociation behavior was as follows.

[Table 3]

Separable epoxy adhesive cured with cystamine (epoxy formulation IV) Chemless E20 (1.80 kg) and cystamine (0.38 g) were mixed and heated at 100 ° C.
For 1 hour. The tensile shear strength after 1 day was 11.4. After mixing and curing at room temperature for 7 days, the tensile shear strength was 6.1. The cured adhesive dissociated within 10 minutes after addition of thioglycolic acid methyl ester. This cystamine can be replaced by a mixture of cystamine dihydrochloride and NaOH.

Polyurethane adhesives PU formulations based on polyurethane prepolymers (urethane formulation I) Voranol CP455 / castor oil are reacted with the reaction product of dithiodiethanol / MDI [Lupranat MIS; dithiodiethanol with 2: Reacted at 60 ° C. for 3 hours in a molar ratio of 1] and cured at room temperature for 24 hours. The sample dissociated upon addition of the cleavage agent and became viscous within minutes.

[0054] The following ingredients releasable adhesives based on urethane prepared by mixing (urethane formulation II) 8.13 g of (0.53 mol) PPG1000 (polypropylene glycol) 1.94 g (0.45 mol) Boranol CP 455 (glycerol / PO adduct) 0.07 g (0.007 mol) of castor oil 2.43 g (1.05 mol) of 2,2'-dithiodiethanol 7.90 g (2.1 mol) of 2 , 4 '/ 4,4'-MDI isomer mixture (diphenylmethane diisocyanate) This was applied to a steel plate, polymerized by heating, applied high temperature and cured at room temperature for 5 days. The tensile shear strength was about 8 N / mm ² . The Shore A hardness (contact time 60 seconds) was 50. After treatment with the cleavage agent, the viscous mass spread immediately. The adhesive mixture can be thickened with 5% Aerosil or 10% Carbopol. Curing occurred at room temperature. The cured adhesive softened when contacted with thiodiglycolic acid methyl ester.

Examples of formulations in which the components are simply stirred together without preparing the prepolymer (amounts expressed in parts per mole; urethane formulation III)

[Table 4]

Examples of cleaving agent formulations : Ethanol / thioglycolic acid methyl ester containing 4% triethylamine 90/10 (bond dissociation solution I) NMP / thioglycolic acid methyl ester 90 containing 4% triethylamine
/ 10 (bond dissociation solution II) Ethanol / acetyl cystamine with triethylamine (15%) 8/2: Epoxy formulation IIIa: bond dissociated after 8 hours under mechanical loading Urethane formulation II: Bonds dissociate after 8 hours under mechanical load

Example of a thickened dissociation solution: ethanol (500 g) / carbopol 980 (12.5 g) / triethylamine (37.5 g) / thioglycolic acid methyl ester (50 g)

Bond dissociation at high and room temperature

[Table 5]

The following trade names were used in the examples. Epikote 828 (corresponding to ChemRes E20): epichlorohydrin / bisphenol A adduct, standard epoxy resin, epoxy equivalent 18
0-194, viscosity 8,000-14,000 mPas / 25 ° C Thiokol LP3: polysulfide polymer, average molecular weight 1,000
, 2% trifunctional monomer, average mercaptan content 2.06 mol / kg (data are from Int.
J. Adhesion and Adhesives, Vol. 12, No. 3, July 1992, p. 171) Capcure 3-800: Henkel Corp., trifunctional mercaptan terminated alkyl-PO -Adduct, mercaptan equivalent 240-270 Voranol CP455: glycerol-PO-adduct of Dow, equivalent about 144, OH number about 390 Lupranat MIS: BASF, 2,4 '-/ 4 , 4'-MDI isomer mixture, about 48% 4,4'-isomer and about 52% 2,4'-isomer Carbopol 980: polyacrylic acid, acid number 700-750, glass temperature 100-105 ° C., viscosity 15,000-30,000 mPas (0.2%) Terostat 1SE: Henkel Teroson, one-component FDM terrostat based on polysulfide polymer 998R / 998B: Henkel teroso , Based on polysulfide polymers bicomponent insulating glass adhesive

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Herbert Fischer Federal Republic of Germany Day 40229 Düsseldorf, Neustadter Weg 29 (72) Inventor Michael Hiltanmer Federal Republic of Germany Day-69251 Geiberg, Scheffelwei No. 1 (72) Inventor Hubert Schenkel Federal Republic of Germany Day-69207 Zandhausen, Robert-Schumann-Strasse 19/1 No. 1 (72) Inventor Manfred Schumann Federal Republic of Germany Day-69121 Heidelberg, Burgstrasse 24th F term (reference) 4J034 CA02 CA04 CA13 CA15 CA22 CA24 CA32 CA34 CB03 CB07 CB08 CC10 CC12 CC13 CC61 CC65 CC67 CD08 DA01 DB03 DB07 DF02 DF12 DF16 DF20 DF29 DG03 DG04 DG06 DG10 D G12 DH02 DH06 DH09 DJ02 DJ08 DK00 DK05 DK06 DK08 DP18 EA11 GA06 GA33 GA55 HA01 HA07 HB03 HC03 HC07 HC12 HC13 HC17 HC22 HC46 HC52 HC61 HC64 HC67 HC71 HC73 LA05 LA32 LA36 RA08 4J040 CA031 EC031 EC061 EC071 EF EF EF EF 181 EF EF EF321 GA20 GA24 GA31 HA046 HA256 HB05 HB09 HB12 HB15 HB19 HB31 HB43 HB46 HC01 HC22 HD03 HD05 HD07 HD09 HD15 HD22 KA16 KA23 KA43 LA01 PA42

Claims (6)

[Claims] 1. An adhesive composition based on at least one binder containing a disulfide or polysulfide bond for forming an adhesive layer, wherein the adhesive layer can be dissociated by a cleavage agent. Adhesive composition. 2. The binder according to claim 1, wherein the structural component of the binder is in combination with a di- or polymercaptan, a di- or polythioalkanol, a di- or polythiodicarboxylic acid or a di- or polythio-di- or polyamine or a mixture thereof containing disulfide / polysulfide bonds. Polyurethane systems prepared from epoxy resins, monomeric or prepolymer di- or polyisocyanates and di- or polythio-di- or polyamines, di- or polythio-di- and / or polyols, vulcanization systems containing sulfur and / or sulfur compounds The adhesive composition according to claim 1, wherein the adhesive composition is selected from the group consisting of a liquid polyene (liquid rubber). 3. A cleavage agent for releasing an adhesive layer based on the adhesive according to claim 1 or 2, comprising a mercaptocarboxylic acid, an ester and a salt thereof, sulfur, mercaptobenzoxazole, mercaptobenzothiazole, A cleavage agent comprising at least one compound from the group consisting of -mercaptoethylamine, 2-mercaptoethanol, dithiothreitol, sodium thiosulfate, trialkyl or triarylphosphine. 4. Cleavage agent according to claim 3, characterized in that it contains an additional accelerator and / or swelling agent. 5. A method for forming and releasing an adhesive layer essentially comprising the steps of: (a) the adhesive composition according to any one of claims 1 to 3, optionally before use (B) curing the adhesive at room temperature or by heating; and (c) a cleaving agent according to claim 3. Or by dipping the bonded part in a solution containing the cleavage agent according to claim 3; (d) then, if desired, heating the bonded part or adhesive layer (E) then, if desired, applying mechanical stress to the adhesive layer to separate the bonded components. 6. A method for forming and releasing an adhesive layer essentially comprising the steps of: (a) the adhesive composition according to any one of claims 1 to 3 (optionally before use); (Mixed from two or more components) to assemble and join the components, (b) cure the adhesive at room temperature or by heating, and (c) release the adhesive layer by heating ( Activates the added cleavage agent which is inert at room temperature), (d) then optionally applies mechanical stress.