SK282185B6 - Heat-setting reactive mixture based on natural and/ or synthetic elastomers, its preparation method and use - Google Patents

Abstract

Heat-setting reactive compounds with a single component based on liquid rubber with reactive olefinic double bonds and optionally solid rubber and sulphur-based vulcanisation systems have a high acoustic loss factor maximum at the vulcanised state in a large range of use temperatures from about +10 DEG C to +40 DEG C. These compositions may also contain finely powdered thermoplastic polymers. These compositions are useful as acoustically attenuating adhesives, sealing or coating masses.

Description

Technical field

The invention relates to hot-curable reactive compositions based on natural and / or synthetic, olefinic double bonds containing elastomers and vulcanizing agents having acoustic buffering properties in the vulcanized state. The invention further relates to a process for the production of these compositions as well as to their use as adhesives, sealants and protective layers.

BACKGROUND OF THE INVENTION

Today, very thin-walled sheets are used almost exclusively in the manufacture of vehicles, machinery and equipment. Mechanically moving parts or running engines introduce these thin-walled sheets inevitably, which is often in the area of audibility by the human ear. In the form of sound in the solid, these oscillations spread further throughout the vehicle or vehicle. machine or apparatus, and may be emitted in the air as disturbing noise in distant locations. Therefore, in order to reduce the emission of noise and to dampen sound in solids, these sheets, in particular in the manufacture of automobiles and in the manufacture of household appliances, are provided with noise-damping coatings. anti-vibration coatings.

According to a conventional method, high density filler and bitumen mixtures are extruded onto films, from which the corresponding molded parts are then punched or cut. Thereafter, these films are adhered to the respective sheet metal parts and, if necessary, must be adapted to the shape of the sheet under heating. Although these bitumen films are still frequently used because of their low material cost, they are very fragile and tend to peel off from the sheet, especially at low temperatures. Even the frequently proposed elastomer additions provide little improvement, which is not sufficient for many applications. In addition, the application of preformed bitumen parts to difficult-to-form or difficult-to-access sheet metal parts of machines or vehicles, e.g. on the inner surfaces of the hollow spaces of motor vehicle doors is not possible at all. As a further disadvantage, in addition, a number of embossed parts are required for a single vehicle or apparatus in many cases, requiring costly storage.

Therefore, attempts have been made to eliminate the disadvantages of bituminous films by other polymer systems. Thus, e.g. have developed aqueous polymer dispersions of polyvinyl acetate or ethylene-vinyl acetate copolymers containing fillers which can be sprayed onto sheet metal parts with the required layer thickness. However, these systems are disadvantageous for industrial use with a high number of pieces to be manufactured, since, particularly at high layer thicknesses, water cannot be removed from the sprayed layer sufficiently quickly. A further disadvantage of these conventional noise attenuation methods is that these materials serve the sole purpose of attenuating noise.

In the manufacture of vehicles, machinery and equipment, efforts are now being made to simplify the complexity of production processes and thereby reduce production costs.

In addition, adhesives, sealants and protective coatings are used in the manufacture of vehicles, machinery and equipment. To date, adhesives and / or sealants have been selected mainly on the basis of their primary properties:

- strength, t. j. shear strength, peel resistance,

- elongation at break, flexibility,

- resistance to aging,

- easy handling.

Abrasion resistance is another criterion of choice for protective coatings, especially for protective coatings at the bottom.

Many efforts are being made to reduce the complexity of manufacturing vehicles, machinery and equipment, thereby reducing production costs. Therefore, there is a need for "multifunctional products"; j. e.g. there is a need for adhesives, sealants and / or protective layers which, in addition to their main function, solve other problems.

EP-A-358598 or DE-A-3444863 disclose plastisol formulations which fulfill the dual function of underbody protection (abrasion protection) and acoustic damping. DE-A-4013318 discloses a two-layer bottom protection which fulfills the functions of bottom protection and noise absorption from impacting particles (stones, gravel, water, etc.). While these products / processes satisfactorily satisfy the combination of bottom protection and sound attenuation, there is a particular need to combine the function of adhesive and / or sealant with noise attenuation. This is particularly desirable for those parts of a car, machine or apparatus that do not need any abrasion protection, such as e.g. the luggage compartment cover, the bonnet, the door or the front of the vehicle.

Adhesive and sealant materials for these parts are normally used in the production process early in the so-called "rough assembly". The sheets used are coated with corrosion protection oils and drawing oils in an amount of more grams per m ² , so that the adhesive / sealing material used must have the ability to absorb these oils. Although plastisols, in particular PVC plastisols, are used in rough assembly, those plastisols mentioned in EP-A-358598 or DE-A-3444863 are not suitable as adhesive / sealant materials for rough assembly. Plastisol formulations that have been developed especially for rough assembly have no or almost no soundproofing properties.

Another group of adhesive / sealant materials suitable for use in rough assembly is rubber based, in particular vulcanizable mixtures based on 1,4-polybutadiene and / or 1,4-polyisoprene. These compositions preferably comprise low molecular weight liquid polydienes, sulfur and optionally accelerators for sulfur vulcanization. In addition, these compositions may contain a high molecular weight, so-called " the solid rubber, wherein the liquid polydienes and / or the solid rubber may contain functional groups such as hydroxyl groups, carboxyl groups, anhydride groups or epoxy groups. This group of rubber-based adhesive / sealing materials is described in a number of patent applications, e.g. EP-A-97394, EP-A-309903, DE-A-309904, DE-A-3834818, DE-A-4120502, DE-A-4122849, EP-A-181441 and EP-A-356715.

DE-A-4122849 discloses that the bonding of sheets for rough assembly of cars has an o.i. aim to dampen emerging oscillations. Although this document does not provide any further details, it can be assumed that these oscillations are low-frequency oscillations outside the area of audibility to human ears, which arise e.g. for vibration of bonnets, luggage compartments and doors, when these do not have suitable antiflutter adhesive frames.

EP-A-181441 discloses two-component thermally crosslinkable compositions and a process for producing cold crosslinking compositions wherein one binder contains hydroxyl groups and the other binder contains carboxyl groups, respectively. acid anhydride groups. Immediately in use, the two components must be mixed together, either by curing either hot to form esters between hydroxyl groups and carboxylic acid groups, or by cold curing requiring the addition of catalysts. It is stated that these compositions can be used o.i. as vibration damping or noise damping materials. Further data, in particular on the effectiveness of this damping, respectively. which substrates are to be damped are missing in this specification.

Not yet published European application 93120384.8 discloses the use of 3,4-polyisoprene in combination with other curable or non-curable, liquid and / or solid rubbers and the use of these mixtures to form single-component, hot-vulcanizable adhesive / sealant materials with acoustic damping properties.

SUMMARY OF THE INVENTION

It has now been found that one-component, hot-vulcanizable adhesive / sealant materials based on liquid rubbers and possibly solid rubbers can be modified such that the use of the hardly available 3,4-polyisoprene is unnecessary, yet very good acoustic attenuation.

For the purposes of the present invention, acoustically effective or vibration damping is to be understood as damping sound in a solid, which, as is known, causes a reduction in the humming of sheet metal structures.

The acoustic damping performance of the compositions according to the invention is evaluated in accordance with the oscillating bending test according to Part 3 of DIN 53440. Thereafter, the layers of the compositions according to the invention are applied to the steel sheets. they predominate in the manufacture of vehicles for the curing of various paint systems, i.e. in the range between 130 ° C and 220 ° C, they cure. The oscillating bending experiment is then performed at 200 Hz and at different temperatures in order to assess the effective acoustic damping effect of these mixtures in the " use temperature range " j. between about 0 ° C and + 40 ° C. Acoustically effective within the meaning of the present invention should be all hot-curable (vulcanizable) compositions which, in an oscillating bending experiment according to DIN 53440, Part 3, have extremely high damping, i. a sheet metal loss factor with a d (combi) coating of > 0.1, preferably 0.2 or more.

The compositions of the present invention comprise the following:

a) up to 10 wt. one or more solid rubbers having a relative molecular weight of 100000 or more, selected from the group consisting of cis-1,4-polybutadiene, styrene-butadiene rubber, natural rubber, ethylene-propylene-diene rubber, nitrile rubber, butyl rubber, acrylic rubber and acrylic rubber .

b) 5 to 50 wt. one or more liquid polyenes with a relative molecular weight below 20000,

(c) a vulcanization system selected from the group consisting of

- sulfur and one or more organic accelerators and one or more metal oxides, the sulfur content of which is at least 3% by weight; total blend, -peroxide vulcanization systems,

-quinones, quinone dioximes or dinitrozobenzene, optionally in combination with organic accelerators and / or one or more metal oxides,

(d) at least one other additive selected from the group consisting of

- thermoplastic polymers in the form of fine powders,

- fillers,

- tackifiers and / or adhesives,

- extender oils,

- anti-aging means,

- Theological aids or mixtures thereof, wherein the sum of components a) to d) is added to 100% by weight.

The liquid rubbers or elastomers can be selected from the following group of homo- and / or copolymers:

Polybutadienes, especially 1,4- and 1,2-polybutadiene, polybutene, polyisobutylene, 1,4-polyisoprene, styrene-butadiene copolymers, butadiene acrylonitrile copolymers, these polymers may have terminal and / or (statistically separated) side functional groups. Examples of such functional groups are hydroxyl groups, carboxyl groups, carboxylic acid anhydride groups or epoxy groups. The relative molecular weight of these liquid rubbers is typically below 20000, preferably between 900 and 10000. The proportion of liquid rubber in the entire mixture depends on the desired rheology of the uncured mixture and the desired mechanical and acoustic buffer properties of the cured mixture. The proportion of liquid rubber or elastomer normally varies between 5 and 50% by weight. of the whole formulation.

Preferred solid rubbers, respectively. elastomers usually have a considerably higher relative molecular weight than liquid rubbers (100,000 or greater), examples of suitable rubbers are polybutadiene, preferably with very high 1,4-cis double bonds (typically above 95%), styrene-butadiene rubber, butadiene acrylonitrile rubber, or natural isoprene rubber, butyl rubber or polyurethane rubber.

The addition of fine thermoplastic polymer powders can cause a significant improvement in acoustic damping when the thermoplastic polymer has a glass transition temperature in the range between 5 ° C and 50 ° C. Examples of suitable thermoplastic polymers are polypropylene, polyethylene, thermoplastic polyurethanes, methacrylate copolymers, styrene copolymers, polyvinyl chloride, polyvinyl acetal, and in particular polyvinyl acetate and its copolymers.

Fillers may be selected from a variety of materials, in particular chalk, natural ground or precipitated calcium carbonates, calcium magnesium carbonates, silicates, barium sulfate and soot. Foliar fillers, such as e.g. vermiculite, mica, talc or similar layered silicates. In some formulations, such foliar fillers have substantially improved the acoustic damping effect. Alternatively, it may be expedient if at least a portion of the fillers are surface-treated, in particular with various calcium carbonates or, in the case of various calcium carbonates. chalking has proven to be an effective coating with a layer of stearic acid. The total proportion of fillers in the formulation may vary between 10 and 70% by weight, the preferred range being between 25 and 60% by weight.

Hydrocarbon resins, phenolic resins, terpene-phenolic resins, resorcinol resins or derivatives thereof, modified or unmodified bituminous acids, and the like, can be used as tackifiers and / or adhesives. esters (abietic acid derivatives), polyamines, polyaminoamides, polyepoxy resins, anhydrides and anhydride-containing copolymers. Type and amount of tackifiers, respectively. The adhesive ingredients depend on the polymer composition of the adhesive / sealing material or the adhesive composition. the coating composition, the strength of the cured composition and the substrate to which the composition is applied. Typical Tackifier resins, such as e.g. terpene-phenolic resins or resin acid derivatives are normally used in concentrations between 5 and 20 wt%, typical adhesion additives such as polyamines, polyaminoamides or resorcinol derivatives are used in the range between 0.1 and 10 wt%.

The compositions of the present invention preferably do not contain plasticizers, in particular phthalic acid esters or builder oils. However, it may be necessary to influence the Theology of the uncured mixture and / or the mechanical properties, and / or the acoustic damping of the cured mixtures by the addition of so-called cured mixtures. extender oils, i. j. aliphatic, aromatic or naphenic oils. However, this is preferably done by adding low molecular weight polybutenes, polyisobutylenes, or using low molecular weight liquid rubbers. When extender oils are used, amounts between 5 and 20% shall be used.

Suitable curing resp. the vulcanizing agents, accelerators or catalysts depend on the reactive and / or functional groups of the selected polymers. For the curing reaction through olefinic double bonds (vulcanization) of liquid and / or solid rubbers, free-radical vulcanization systems, in particular based on organic and inorganic peroxides, sulfur-based vulcanization systems, in particular in combination with organic vulcanization accelerators, and optionally zinc compounds are suitable. however, vulcanization systems are also quinone, dioxime or dinitrozobenzene.

Particularly preferred are sulfur powder vulcanization systems, particularly in combination with vulcanization accelerators such as e.g. mercaptobenzothiazole, dithiocarbamates, sulfenamides, disulfides such as e.g. dibenzothiazole disulfide and / or thiuram disulfide, aldehyde amine accelerators, guanidines and metal oxides such as e.g. zinc oxide. In addition, typical rubber vulcanizing agents such as e.g. fatty acids (e.g. stearic acid). The sulfur content can be varied over a wide range, it can be up to 5% by weight, preferably up to about 10% by weight, and the lower limit should preferably not be below 3% by weight. . In addition, the maximum loss factor as well as the usable temperature range of a sufficiently high loss factor can be influenced by the sulfur content. The content of vulcanization accelerators may vary between 0 and about 10% by weight. Also the content of metal oxides is in the range between 0 and 10% by weight.

Particularly suitable as sulfur-free vulcanization systems are p-benzoquinone dioxime-based vulcanization systems, which mixtures may additionally contain said vulcanization accelerators and / or metal compounds in the indicated ranges of amounts.

Conventional stabilizers, such as, for example, can be used against thermal, thermo-oxidative or ozone degradation of the compositions of the present invention. sterically hindered phenols or amine derivatives, typical amount ranges for these stabilizers are 0.1 to 5% by weight.

Although the rheology of the compositions of the invention can normally be brought to the desired area by the choice of fillers and the ratio of the amounts of low molecular weight liquid rubbers, conventional rheological auxiliaries such as e.g. pyrogenic silicas, bentones or fibrillated or pulp short fibers in the range between 0.1 and 7%. In addition, other conventional adjuvants and additives may be used in the compositions of the present invention.

The present invention also provides a process for making a hot curable reactive composition which comprises mixing the components under high shear.

The acoustic damping performance of the composition of the present invention can be influenced according to the specific requirements for use with respect to the position of the maximum loss factor as well as the temperature range over which the extremely high acoustic damping will occur. The main influencing factors are the vulcanization system (sulfur content, vulcanization accelerator content) and the content and reactivity of rubbers, in particular liquid rubbers. As already mentioned, the addition of suitable thermoplastic polymer powders can positively affect both the maximum and the temperature range of effective acoustic damping. To some extent, the choice of the type and amount of fillers may also influence the acoustic properties. mica have a beneficial effect on the loss factor. In addition, the loss factor can be influenced by the thickness of the deposited layer. As is known, foam materials cause a higher loss factor, although this will not be applicable in those cases where high tensile shear strength is required for the adhesive. In most applications, it is desirable that the maximum loss factor lies at about room temperature (about 20 ° C) and that the high damping region (loss factor> 0.1) extends over the broadest possible temperature range. Curing conditions for adhesives / sealants, resp. The coating compositions of the present invention may be adapted to a specific application. As mentioned at the outset, one preferred field of application is coarse assembly in the automotive industry, so that the curing of the mixtures is to be carried out in a temperature range between 80 ° C and 240 ° C within 10 to 35 minutes. and 200 ° C. A decisive advantage of the compositions according to the invention over the plastisols of the prior art is their so-called "wash resistance" immediately after application of the adhesives, i. j. they do not require any pregelatinization as plastisols to be resistant in a variety of wash and phosphate baths for rough assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawing, a graph is shown showing the temperature dependence of acoustic damping d (combi) of 50% of Examples 1 to 3, as well as Comparative Example 4, which is less crosslinked.

DETAILED DESCRIPTION OF THE INVENTION

The following examples illustrate the invention in more detail, and the choice of examples is not intended to limit the scope of the invention in any way.

The acoustic damping properties of the mixtures were determined in the examples according to the Oberst ' ¹ method as described in DIN 53440, Part 3, by means of coated steel strips. Curing of the deposited layer was carried out in a conventional laboratory box dryer. Unless otherwise indicated, all parts in the following examples are by weight.

Example 1 Example 2 Example 3 Example 4 cis-4-polyisoprene 10,0 polybutadiene, solid (1) 5.0 3.0 3.0 polybutadiene, liquid (2) 5.0 18.0 polybutadiene, liquid (3) 15.0 9.0 23.0 polybutadiene, liquid (4) 20.0 polybutadiene, liquid (5) 10,0 polybutadiene, liquid _ 5.0 9.0

polybutadiene, liquid (7) 7.0 Zinc oxide, active 4.0 4.0 4.0 4.0 sulfur, powder 4.0 5.0 5.0 4.0 dibenzothiazyl disulfide (MBTS) 4.0 5.0 5.0 tetramethylthiuram disulfide (TMTD) 1.5 Diphenylguanidine (DPG) 3.0 polyvinyl acetate powder (8) 10,0 calcium carbonate 20.0 43.0 44.0 50.0 calcium oxide 5.5 2.5 2.5 5.0 mica 20.0 antioxidants 0.5 0.5 0.5 0.5 blacks 0.5

(1) cis-1,4 especially. 98% (2) MW about 1800, vinyl about 40 to 50% (MW ~ molecular weight) (3) MW about 1800, cis-1,4 about 72% (4) MW about 1000, vinyl about 40 to 50% ( 5) MW about 900, trans-1.4 about 30 to 40% (6) polybutadiene-maleic anhydride adduct, MW about 1700 (7) OH-terminated polybutadiene, MW about 2800 (8) EVA copolymer, Tg about 23 ° C

Acoustic damping properties

A layer of the products of Examples 1 to 3 as well as Comparative Example 4 was applied to a 200 mm long section of 1 mm thick spring steel strips of 240 mm x 10 mm, then cured for 30 minutes. at 180 ° C. The determination (d-combi) of the acoustic damping was carried out in accordance with the bending experiment according to DIN 53440, Part 3, at 200 Hz. In this case, 50% of the applied weight was standardized. the weight of the applied acoustically damping / sealing material layer was 50% by weight of the sheet.

The graph shows the temperature dependence of acoustic damping d (combi) of 50% of Examples 1 to 3, as well as Comparative Example 4, which is less crosslinked.

In particular, Comparative Example 4 shows that the sulfur content of > 3% and accelerators without sufficient reactive rubber content do not lead to crosslinking according to the invention and thus to good acoustic attenuation.

Claims (10)

PATENT CLAIMS A hot curable reactive composition based on natural and / or synthetic elastomers, comprising olefinic double bonds and vulcanizing agents, characterized in that it comprises: a) up to 10 wt. one or more solid rubbers of a relative molecular weight of 100000 or more selected from the group consisting of s-1,4-polybutadiene, styrene-butadiene rubber, natural rubber, ethylene-propylene-diene rubber, nitrile rubber, butyl rubber, acrylic rubber rubber, b) 5 to 50 wt. one or more liquid polyenes with a relative molecular weight below 20000, (c) a vulcanization system selected from the group consisting of - sulfur and one or more organic accelerators and one or more metal oxides, the sulfur content of which represents at least 3% by weight of the total mixture, - peroxidic vulcanization systems, - quinones, quinone dioximes or dinitrozobenzene, where appropriate in combination with organic accelerators and / or one or more metal oxides, (d) at least one other additive selected from the group consisting of - thermoplastic polymers in the form of fine powders, - fillers, - tackifiers and / or adhesives, - extender oils, - anti-aging means, - Theological aids or mixtures thereof, wherein the sum of components (a) to (d) is calculated to be 100% by mass, wherein the maximum loss factor d (combi) of the vulcanized mixture in a bending test according to DIN 53440 at 200 Hz lies + 10 ° C to + 40 ° C, and is at least 0.1, preferably 0.2 or more. Mixture according to claim 1, characterized in that the at least one liquid polyene is selected from the group consisting of 1,2-polybutadiene, 1,4-polybutadiene, polyisoprene, polybutene, polyisobutylene, butadiene and / or isoprene copolymers. with styrene and / or acrylonitrile, copolymers of esters of acrylic acid with dienes, the relative molecular weight of the liquid polyene being in the range from 900 to about 10,000. A composition according to claim 2, characterized in that the one or more liquid polyenes additionally contain terminal and / or statistically distributed carboxyl groups, carboxylic anhydride groups, hydroxy, amino, mercapto or epoxy groups as functional groups. Composition according to at least one of the preceding claims, characterized in that it additionally comprises a thermoplastic polymer with a glass transition temperature between 5 ° C and 50 ° C. Composition according to claim 4, characterized in that the thermoplastic polymer comprises olefinic double bonds, hydroxy groups, carboxyl groups, epoxy groups, amino groups and / or mercapto groups as functional groups. A process for producing a hot curable reactive composition according to at least one of the preceding claims, characterized in that it comprises mixing the components under high shear. Use of the composition according to at least one of the preceding claims as an acoustically damping, one- or two-component adhesive, sealant or mass on the protective layer. 8. A method of joining metal parts and / or sealing gaps between metal parts, characterized in that: - a coating layer according to at least one of the preceding claims is applied to at least one surface of the part, - the parts to be joined are assembled together, and the assembled parts, optionally mechanically fixed, are heated to cure the reactive mixture. A method of applying layers to components by spraying or extruding mixtures according to at least one From claim 1 to 5 on the surface of the workpiece and heating the applied portion to cure the composition. Method for applying a layer to components, gluing and / or sealing them, characterized in that the extruded film, extruded cord or extruded strip made of the mixture according to at least one of claims 1 to 5 is laid on at least one structural component. The parts are optionally assembled together and then heated to cure the mixture.