NO742885L - - Google Patents

Description

Sealants, as well as methods for their production.

The invention relates to sealants, especially such products which are applied in semi-liquid form and harden to form a rubbery, elastic material. Such preparations, which are sometimes referred to as water locks, are frequently used to fill cracks at the joints in certain constructions, e.g.

in building materials. At these joins or joints, mechanical and thermal movements cause the dimensions of the cracks to vary considerably, and therefore the demands on the cured sealant in terms of adhesion and elasticity at temperatures that vary within wide limits are high.

A satisfactory sealant is therefore in a semi-liquid or paste-like form when applied, and in order for it to fill the cracks completely, it should also have good flow properties, it should cure or dry to a non-tacky state within a few hours, and throughout curing should be complete, within a few days to form, without much shrinkage, a durable, elastic filling material that is resistant to water and preferably also to other external influences.

Drying or hardening of a drawing agent can find

place by evaporation of a solvent and by means of a chemical polymerization reaction, e.g. moisture heat curing or ultraviolet curing. A disadvantage of solvent-hardening sealants is that, due to the evaporation, considerable shrinkage often occurs, moe which i.a. causes cracking. Moisture-heat curing systems generally show, after rapid surface curing, too slow curing of the inner material.

It has now been shown that certain mixtures containing

an unsaturated polyester resin, a rubber, unsaturated monomeric material, an extender oil, a photosensitizer, and possibly other components such as e.g. a cure accelerator, a filler, thixotropic agent, pigment, dye, tackifying agent are excellent ultraviolet radiation induced free radical curing sealants.

The unsaturated polyester resin used in products according to the invention is generally based on one or more

'i Cj-Cg diols l,. e.g. a propylene glycol, and a mixture of C^-C^Q dicarboxylic acids/comprising at least maleic acid or an isomer thereof and preferably a phthalic acid. Naturally, the polyester resin can be prepared from the diol and the acid as well as from functional derivatives thereof such as e.g. the acid anhydride or a lower alkyl ester. The molar ratio between maleic acid and another dicarboxylic acid is generally in the range 0.3 to 5:1, preferably in the range 5:1 to 3:1. The unsaturated polyester resin generally contains terminal hydroxy groups and is therefore then prepared from a stoichiometric excess of up to 10% glycol. Furthermore, the polyester should have a molecular weight below approx. 5,000.

The relative amount of unsaturated polyester, by weight, in the drawing agent is dependent on the amount of other components. For the sake of convenience, the amounts of polyester below are calculated as 100 parts. Up to 60% by weight of this polyester can be replaced by a

-rnn

in libisphenol Aj -based polymethacrylic acid ester.

The rubber used in products according to the invention should provide good workability and good mechanical properties and should be compatible with the other components. The rubber must swell with extender oil. Synthetic rubber types used should generally not have too high a molecular weight. Certain, essentially saturated synthetic rubber types, e.g. ethylene/Rinyl acetate and ethylene/propylene copolymers and terpolymers as well as nitrile rubber, e.g. acrylic-nitrile-butadiene or isoprene copolymers have proven suitable. The weight ratio between rubber and polyester resin in the sealant

should be in the range from, |3:1 to l:2^7^-v.s. that per 100 parts by weight of polyester are used 300 - 50 parts of rubber, preferably 100 - 200 parts.

The unsaturated monomeric material used in products

according to the invention, is generally a copolymerizable unsaturated compound, e.g. PsÆyrene, divinylbenzene, diallyph thalate, vinyl toluene, methyl acrylate, methyl methacrylate and triallyl cyanurate in. The amount of unsat.

The extender oil used in products according to the invention is generally a hydrocarbon oil, e.g. a paraffinic oil, a naphthenic oil or an alkylaromatic compound or a mixture of such compounds. The extender oil must be inert and compatible with the rubber used. Alkylbenzenes containing 6-18 carbon atoms in the alkyl group are preferred. A suitable, commercially available extender oil is dodecylbenzene which is essentially one mixture of different isomeric compounds in which the degree of branching in the dodecyl group varies. Experience has shown that extender oil of technical, good quality can be used without difficulty. However, the use of poor quality extender oil has occasionally led to unsatisfactory results. The amount of extender oil calculated on the amount of unsaturated monomer,

by weight, generally varies from 2:1 to 1:4, preferably between 1:1 and 1:2.

The relative amounts of the sum of unsaturated monomer and extender oil to the sum of the amounts of polyester resin and rubber varies from 1:1 to 5:1, preferably below 3:1.

The sensitizer used in products according to the invention serves to absorb ultraviolet radiation and thereby induce free radical curing and accelerate drying or curing. In general, the suitable sensitizers are benzoin and its derivatives. Preferred are benzoin alkyl ethers, especially the ethers of secondary alcohols. The amount of sensitizer generally varies from 0.2 to 3 percent by weight, calculated on the amounts of the sum of unsaturated polyester resin and unsaturated monomer.

The curing accelerator, when used in products according to the invention, is a heavy metal compound, e.g. a cobalt, iron or copper salt, cobalt salts being preferred. Organic salts, e.g. the octoate or naphthenate, have proved well suited. The amount of hardening accelerator, calculated as metal, varies between 0.001 and 0.02 percent by weight, calculated on the [ total! amount of polyester and unsaturated monomer. For the sake of convenience, the hardening accelerator is generally used in the form of a diluted solution in styrene, e.g. in the form of a commercially available solution that contains one percent of the metal in the board.

Additional components that may possibly be present in the products according to the invention include fillers, i.e. generally inorganic compounds, e.g. kaolin, silica, general talc, calcium carbonate and the like; thixotropic agents, e.g. very finely divided silicon dioxide such as are available under the trade name "Aerosil',' from Degussa, Frankfurt, Germany; finely divided asbestos; bentones and "Thixcine" from Baker Castor Oil, Bayonne, N.J., U.S.A., pigments such as titanium dioxide, dyes and tackifiers, e.g. eg coumarone/indene resins which serve to improve adhesion.

With the exception of the fillers, the above-mentioned components contribute only a few percent by weight of the total composition. However, the amount of filler can vary from a few percent to approx. 30% by weight of the entire mixture.

The sealants according to the invention are usually produced at slightly elevated temperatures of 50 - 80°C by mixing and stirring the extender oil, the rubber and the unsaturated monomer,

so that a homogeneous system is achieved. The unsaturated polyester and the sensitizer are then introduced at the same temperature, which generally results in a drop in viscosity when the mixture becomes homogeneous again. The other components, e.g. fillers, thixotropic agents, etc., are suitably introduced in this step and stirred in while the mixture is allowed to cool. Alternatively, incorporate . the thixotropic agent in the polyester), possibly together with the sensitizer and the curing accelerator before addition to the rubber and the extender oil.

The photo-curing sealants according to the invention can be easily worked into cracks in construction materials and cured to an elastic filler with a Shore A hardness of at least 40-50 within a few days under the influence of diffused daylight. Within a few hours of application, the surface of the drawing medium becomes tack-free, and it was surprising to find that, especially when exposed to diffused daylight, curing of the inner material takes place more quickly than compared to curing under the influence of artificial ultraviolet radiation with high intensity. The sealants according to the invention possess excellent storage stability at different temperatures, they can be processed even at low temperatures and provide fillers or seals with good dimensional stability.

The invention shall be illustrated by means of examples.

Example 1.

150 parts "Levapren VPKA 8061" (an ethylene/vinyl acetate rubber (2:1) copolymer with melt index 9/10 min. 190°C; 2.16 Kgf) from Bayer Leverkusen, Germany), 200 parts styrene, 150 parts dodecylbenzene " EP-P" from Kettlitz Chemie G.m.b.H., Ebenhausen-Ingoldstadt, Germany, was stirred and mixed at 80 C until the gum was dispersed and a homogeneous mass was obtained. Then 100 parts by weight of a polyester resin, based on propylene glycol-1,2, maleic acid and ortho-phthalic acid in the molar ratio 1.7:1 (acid number approx. 25, OH number approx. 35, molecular weight approx. 2000), 3 parts of a cobalt octoate solution in styrene containing 1% by weight of the metal, and 6 parts of "Trigonal 15" from AKZO Chemicals, Deventer, which is essentially a mixture of various benzoin alkyl ethers, after which 150 parts of finely divided calcium carbonate ("Durcal" from Plusstaufer AG OftringerT; Switzerland) was stirred into the mixture.

A satisfactory sealant with fairly good workability at 10°C, without sticking after 1 hour and which gave good, elastic filling or drawing, was obtained. Shore A hardness was 22 after 1 day exposure to diffused daylight and 45 after 2 days, 50 and 5 days and 60 after 7 days exposure. The conditions of the exposure were:

1) daytime temperature: max. 26°C

night temperature: max. 15°C

After 5 days it was instead Shore A hardness of 50

measured a hardness of 45 under the following conditions:

2) daytime temperature: approx. 4°C

night temperature approx. 0°C.

Influence of the sensitizer.

Without sensitizer, the Shore A hardness was less than 5 (after 5 days of exposure under condition (1) as stated above) (contraction and cracking).

Influence of the board.

All styrene was replaced by xylene: After 5 days of exposure under condition (1) as stated above, the Shore A hardness was less than 5 (contraction and cracking).

In an accelerated storage stability test at 100°C, the stability was approx. 6 hours. A non-stick inner material in a 1/2 cm layer was achieved within a week. Stability at room temperature was more than 6 months.

Example 2.

This example was identical to Example 1 except that the curing accelerator (cobalt octoate) was omitted, and after 5 days a Shore A hardness of 25 was obtained under the influence of diffused daylight (exposure condition (1) in Example 1).

Example 3.

In a similar manner to that described in Example 1, using the same starting materials, a sealant was prepared from 100 parts of polyester, 150 parts of rubber, 275 parts of styrene, 150 parts of extender oil and 150 parts of calcium carbonate, followed by 4 parts of the cobalt salt solution and 7 parts of the sensitizer was added and mixed. Workability was good,

and elasticity quite good. The Shore A hardness was measured as 14 (after one day exposure to diffused daylight), 43 (after 2 days) and 55 (after 5 days) (exposure condition 1) in Example 1).

Example 4.

In a similar manner as described in Example 1, using the same starting materials, a drawing agent was prepared from 100 parts polyester, 150 parts rubber, [315 parts styrene, .185 parts extender oil and 150 parts calcium carbonate. 4 parts of the cobalt salt solution and 8 parts of the sensitizer were mixed in.

The workability of the sealant was good, and the elasticity of the sealant quite good. The Shore A hardness was measured at (after one day exposure to diffused daylight), .pOj (after 2 days) and [40") (after 5 days) (exposure condition"^) in Example 1).

Example 5.

In a similar manner to that described in Example 1, using the same starting materials, a sealant was prepared from 100 parts polyester, 150 parts rubber, V215 parts styrene, 200 parts 'dodecylbenzeneH<(1?om described in Example 1) and 150 parts calcium carbonate. 4 parts of the cobalt salt solution and 1/7 parts of the sensitizer were mixed in.

The workability of the sealant and the elasticity of the seal obtained were good. The Shore A hardness was 40 after two days of exposure to diffused daylight and 50 after 5 days (exposure condition(1) in Example 1).

Example 6.

This example was similar to example 5, but instead of the polyester resin based on maleic acid/o-phthalic acid with a molar ratio of 1.7:1, a similar polyester resin where this molar ratio was 3:1 was used in the same relative amounts. This sealant showed good workability at 10°C, and the sealant showed a Shore A hardness after two days of curing under diffused daylight of 50.

(exposure condition (1) in example 1).

Example 7.

A sealant was prepared from 100 parts polyester resin, based on propylene glycol-1.2, maleic acid/o-phthalic acid ratio 1.7:1, 150 parts "Levapren VPKA 8061" and 45 parts "EPDM" rubber "BBUNA AP 447" from Chemische Werke Hi, Mari, Germany,

which is an ethylene/propylene/ethylidene/norbornene rubber with. a Mooney plasticity of 85), 380 parts styrene, 270 parts dodecylbenzene (as described in Example 1), 6 parts "Trigonal 15" sensitizers, 3 parts of a solution of cobalt naphthenate in styrene, which contained 1 percent by weight of the metal, and 150 parts calcium carbonate. In this case, the polyester sensitizer and cure accelerator were premixed before the rubber and extender oil were introduced under gentle heating. After 4 days of curing under diffused daylight, the Shore A hardness was 80 (exposure condition (1) in Example 1).

Example 8.

A sealant was prepared from 100 parts polyester resin (propylene glycol-1.2, maleic acid/o-phthalic acid ratio 1.7:1), 90 parts "BUNA AP 447" rubber, 425 parts styrene, 150 parts dodecylbenzene (as described in Example 1) , 10 parts "Trigonal 15", n

5 parts of a solution of cobalt naphthenate in styrene, which contained

1 percent by weight of the metal, 115 parts of finely divided calcium carbonate and 20 parts of very finely divided silicon dioxide ("Aerosil" Transparent, from Degussa, Frankfurt, Germany). The mixing process was as described in example 7, whereby "Aerosil" was also incorporated into the polyester resin premix. The sealant showed good workability and the sealant showed a Shore A hardness of 90 after exposure to diffused daylight for 4 days (exposure condition (1)

in example 1).

Example 9.

A sealant was prepared from 100 parts polyester resin (propylene glycol-1.2, maleic acid/o-phthalic acid ratio 1.7:1), 105 parts "BUNA AP 447" rubber, 315 parts styrene, 265

parts dodecylbenzene (as described in Example 1), 8 parts "Trigonal 15", 4 parts of a solution of cobalt naphthenate in styrene, which contained" 1 percent by weight of the metal, 115 parts finely divided calcium carbonate and ' ZB~~" parts "Aerosil^Transparent ..as" described ITT^n [example_lTB^whereby~"Areosf 1" was also incorporated into the polyester resin premix. The sealant showed good workability and the sealant showed a Shore A hardness of 80 after exposure to diffused daylight for 4 days (exposure condition (1) in Example 1).

Claims (11)

1. Homogeneous mixture, for use as a sealant, characterized in that it comprises at least one unsaturated polyester resin, a rubber, an unsaturated monomeric material, an extender oil and a photosensitizer. 2. Sealant as specified in claim 1, characterized in that the weight ratio between polyester resin and rubber is from 100 parts to 50-300 parts by weight. 3. Sealant as stated in claim 1 or 2, characterized in that the amounts of an unsaturated monomer and extender, combined, in relation to the amounts of polyester resin and rubber, combined, vary 1:1 to 5:1 under the condition that the weight ratio between extender oil and unsaturated monomer varies from 2:1 to 1:4. 4. Sealant as specified in any one of claims 1-3, characterized in that the amount of sensitizer varies from 0.3 -3 percent, calculated on the weight of the sum of resin and unsaturated polyester. 5. Sealant as stated in any one of claims 1-4, characterized in that the unsaturated polyester resin has a molecular weight below 5000, based on a C^-Cg-diol and a mixture of C^-C^-dicarboxylic acids comprising a phthalic and maleic acid or isomers thereof. 6. Sealant as stated in any of the preceding claims, characterized in that the rubber is a substantially saturated synthetic rubber. 7. Sealant as stated in any of the preceding claims, characterized in that the unsaturated monomeric material is an ethylenically unsaturated material, which is copolymerizable with the unsaturated polyester. 8. Sealant as stated in any of the preceding claims, characterized in that the extender oil is an alkylbenzene containing 6-18 carbon atoms in the alkyl group. 9. Sealant as stated in any one of the preceding claims, characterized in that the photosensitizer is benzoin or a benzoin C 1 -C 2 -alkyl ether. 10. Sealant as stated in any one of the preceding claims, characterized in that the mixture also comprises a small amount of a transition metal salt. 11. Method for the production of a homogeneous paste by mixing an extender oil, a rubber and an unsaturated monomer at a temperature of 50-80°C, after which an unsaturated polyester and a photosensitizer and possibly further components are incorporated and the mixture is processed into a homogeneous pasta.