EP0496771A1

EP0496771A1 - Quick-acting joint sealing compounds

Info

Publication number: EP0496771A1
Application number: EP90915439A
Authority: EP
Inventors: Helmut Loth; Bernhard Knop; Tore Podola; Klaus Helpenstein
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 1989-10-19
Filing date: 1990-10-10
Publication date: 1992-08-05
Also published as: EP0423613A1; MX170856B; CN1051380A; US5118732A; WO1991005825A1; KR920702398A; BR9007763A; JPH05501273A; CA2070639A1; CA2070639C

Abstract

Matériaux pour garnitures de joints susceptibles d'être exposés prématurément à l'eau de pluie et résistant à celle-ci, contenant: des dispersions polymère aqueuses (I), des éthers cellulosiques non ioniques (II) appartenant au groupe comprenant l'hydroxyéthylcellulose, l'hydroxyéthylméthylcellulose, l'hydroxypropylméthylcellulose et l'hydroxypropylcellulose, et, le cas échéant, des adjuvants courants, tels que charges, pigments, agents de ramollissement, diluants, épaississants, agents anti-mousse, auxiliaires dispersants, régulateurs de pH et agents de conservation et d'anti-vieillissement, préparées par mélange intime de (I) avec les autres constituants. Afin de pouvoir incorporer (II) en des quantités se situant au-dessus de la limite de solubilité, les matériaux pour garnitures de joints sont caractérisés en ce que (II) sous forme retardée est mis en suspension dans de petites quantités d'eau et ajouté et incorporé après mise en suspension.Materials for sealings liable to be prematurely exposed to and resistant to rainwater, containing: aqueous polymer dispersions (I), nonionic cellulose ethers (II) belonging to the group comprising hydroxyethylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose and hydroxypropylcellulose, and, where appropriate, common adjuvants, such as fillers, pigments, softening agents, diluents, thickeners, defoamers, dispersing aids, pH regulators and conservation and anti-aging, prepared by intimate mixing of (I) with the other constituents. In order to be able to incorporate (II) in quantities which are above the solubility limit, the materials for sealings are characterized in that (II) in delayed form is suspended in small quantities of water and added and incorporated after suspension.

Description

Early waterproof footing compounds

The invention relates to early rainproof joint sealants containing aqueous polymer dispersions (I) non-ionic cellulose ethers (II) from the group formed by hydroxyethyl, hydroxyethylmethyl, hydroxypropyl ethyl and hydroxypropyl cellulose, and, if appropriate, customary additives such as fillers, pigments, plasticizers , Extenders, thickeners, defoamers, dispersing aids, pH regulators and preservatives and anti-aging agents and can be produced by intimately mixing (I) with the other constituents, and a process for producing such jointing compound and their use.

Joint sealants are known to the person skilled in the art and have proven themselves in practice. The use of joint sealant in areas where there is a possibility or risk that

• • • the joint sealant is exposed to water pollution, e.g. splash water or rain, before it hardens. For example, many of the jointing compounds that have also been used in the exterior have been wholly or partially washed out by a heavy downpour that started shortly after they were applied. DE 3814078-A1 discloses the use of non-ionic cellulose ethers in joint sealants or sealants based on acrylate dispersions. The use of certain cellulose ethers in these compositions is said to improve the washout behavior through the action of water such as rainwater and the smoothing behavior. The amounts of the specified cellulose ether types used there are based on the solids content of the acrylate dispersion. No explicit statement is made about the ratio of "free" water to the cellulose ethers. Although the examples show that the components listed there for the production of a joint sealant were produced in a planetary mixer, there is no information about the form and sequence in which the individual components are mixed with one another.

However, it has been found in practice that the addition of the individual constituents and their shape is not arbitrary in the case of such early rainproof joint sealing compounds. Thus, for example, the cellulose ethers mentioned can be sprinkled and dissolved in small amounts in some polymer dispersions on a laboratory scale, but not on a production scale and not in amounts which are too large to be complete in relation to the "free" water Achieve solution. Such an attempt inevitably leads to lump formation or breakage of the dispersion. Even if it is sometimes possible to homogenize the cellulose ether lumps again, it is not feasible to redisperse dispersion particles once coagulated. Furthermore, DE 3814078-Al does not offer the person skilled in the art any indication that such early rain-resistant joint sealing compounds can be combined with other aqueous gene polymer dispersions can be produced as the acrylic dispersions specified there.

Non-ionic cellulose ethers are also known as constituents of coating compositions and paints, e.g. those based on aqueous dispersions of organopolysiloxanes as described in DE 1284007 or those based on vinyl acetate / maleic acid dibutyl ester dispersions as described in DE 21 08365. However, the person skilled in the art cannot derive any indication that such cellulose ethers are also suitable for joint sealants based on the same polymer dispersion and lead to the desired effects.

The specialist magazine Resin Review 35.2 describes a roof coating ace that contains a polyacrylate dispersion as a binder and, in addition to fillers and other auxiliaries, also contains hydroxyethyl cellulose as a thickener. This coating composition is advertised as being particularly resistant to washing out. However, this property is attributed to the specific setting behavior of the polyacrylates ulsioneπ, which have been specially developed and used for such coating compositions. It was therefore not obvious to a person skilled in the art to use hydroxyethyl cellulose in joint sealants to improve the early rain strength.

In addition, coating compounds do not meet the requirements placed on joint sealing compounds. These are in particular requirements such as those required by DIN 52456 "Determining the Processability of Sealants" and DIN 52454 "Stability".

In particular when it comes to durability, joint sealants must have the property of one in relation to the coating compounds with this mass filled U-profile, which is put into the vertical after filling, not or only slightly. Coating compositions are generally of low viscosity, since on the one hand they should be able to be applied by spraying or rolling and on the other they should show a certain course for leveling the composition. Although joint sealants and coating compounds can in principle be produced from the same constituents, it should also be possible to produce a reasonably usable coating compound by diluting a joint sealant, but conclusions cannot necessarily be drawn in the reverse manner.

From Ullmann, Encyclopedia of Industrial Chemistry, 4th edition, Volume 9, Verlag Chemie, Weinheim / Bergstrasse 1974, pages 208-209, it is known that nonionic cellulose ether derivatives such as hydroxyethyl cellulose (HEC), hydroxyethyl methyl cellulose (HEMC) and hydroxy - Propyl-methylcellulose (HPMC) can be used in plastic plasters and emulsion paints, among other things, to improve water retention, open time, wet grip and thickening and setting behavior. However, the person skilled in the art cannot derive any indication that such cellulose ethers in joint sealing compounds lead to an improvement in the spreadability, the smoothing behavior and the splash water resistance of the as yet unhardened surfaces of these compounds. Furthermore, paints such as emulsion paints and plastic mortars represent another area of technology that is not comparable to joint sealants. Thus, plastic plasters can possibly be used to fill joints, but generally have no pronounced sealing properties and, in contrast to joint sealing compounds, can be portioned and processed with a trowel when they are applied. The object of the invention is to provide joint sealants based on polymer dispersions which, in addition to good smoothing behavior, have an early rain resistance of the uncured compositions without other desired properties such as modulus of elasticity, elongation at break and resilience, and resistance to migration and coagulum and Speck freedom can be adversely affected. It was also an object of the invention to provide a method which makes it possible to produce such compositions.

The object was achieved by early rain-resistant joint sealants containing aqueous polymer dispersions (I) non-ionic cellulose ethers (II) from the group formed by hydroxyethyl, hydroxyethylmethyl, hydroxypropylmethyl and hydroxypropyl cellulose and, if appropriate, customary additives such as fillers, pigments, plasticizers, Extenders, thickeners, defoamers, dispersing aids, pH regulators as well as preservatives and anti-aging agents and can be produced by intimately mixing (I) with the other constituents, characterized in that (II) in retarded form in small amounts Slurried water and added after mixing and mixed.

The individual components of the joint sealant are known to the person skilled in the art as such, for example from DE 38 14078-Al. Further suitable polymer dispersions for the production of joint sealants are commercially available and / or are known to the person skilled in the art from the patent and specialist literature, for example from E. Flick, Construction and structural adhesives and sealants, Noyes Publications, Park Ridge 1988 or E. Flick , Adhesives and sealant compound formulations, Noyes Publications, Park Ridge 1978. Particularly advantageous jointing tion aces contain dispersions of film-forming polyacrylates and / or acrylate copolymers. Also advantageous are joint sealants according to the invention which are selected from dispersions of polymers or copolymers capable of film formation from those of ethylene / vinyl acetate, butadiene / styrene, vinyl acetate / maleic acid ester, silicone, urethane, vinyl acetate methacrylic acid / chloroprene and isoprene -Polymers or copolymers based group. Different polymer dispersions can be combined. Polysulfide dispersions have also proven to be particularly suitable in connection with polymers capable of film formation. For the sake of simplicity, the following text speaks only of polymer dispersions.

Most of the ingredients are commercially available. Both retarded and non-retarded cellulose ethers are commercially available. Retarded cellulose ethers are understood to mean those that swell in water after a delay compared to the unretarded substances. This will e.g. achieved by crosslinking with glyoxal on the surface of the cellulose ether particles, as described, for example, in DE 2415556. While it was previously customary to introduce the cellulose ethers mentioned already in aqueous solution or in amounts which can be readily dissolved in the "free" water already contained in the composition, the joint sealing compounds according to the invention are characterized by a new production process with regard to the introduction the cellulose ether.

The cellulose ethers suitable according to the invention are slurried in small amounts of water. In this context, small amounts of water are understood to mean that the amount of water is insufficient to smoothly dissolve the cellulose ethers introduced. The aqueous slurry must be added and mixed immediately after slurrying. Immediate in this context means that the slurry should be added before a clear one Increasing viscosity or even gelling occurs. The swelling process of the cellulose ethers slurried in water must therefore not have started yet or should not yet be very advanced. Times under 15 minutes, especially under 10 minutes, may be practical under production conditions. This period is known to the person skilled in the art as the swelling delay.

The aqueous dispersions contained in the joint sealants of the invention preferably have solids contents of 40 to 75, in particular 45 to 65% by weight. Their pH value can be at least 6, in particular 7 to 9, and is adjusted to these values if necessary.

The cellulose ethers contained in the jointing compounds according to the invention preferably have Brookfield viscosities of at least 5,000 mPas as a 2% strength aqueous solution at 20 ° C. Those with a value of at least 25,000 mPas, for example medium-viscosity hydroxyethyl celluloses, are preferred. So-called highly viscous cellulose ether types which have a corresponding value of at least 70,000 mPas are particularly suitable, e.g. highly viscous hydroxyethyl cellulose. Commercial high viscosity hydroxyethyl cellulose e.g. as a 2% solution at 20 ° C a viscosity of 100,000 mPas.

According to the manufacturer's instructions, complete solutions can no longer be achieved with hydroxyethyl cellulose, for example with Natrosol 250 HHR at a viscosity above 200,000 mPas. With the less hydrophilic cellulose ethers which can be used according to the invention, this limit is even lower, for example with hydroxypropyl cellulose around 150,000 mPas or with hydroxypropyl methyl cellulose around 100,000 mPas. With a higher concentration, gel-like masses increasingly form. However, this seems to play a special role in the early rain resistance of the joint sealing compounds according to the invention play. Even if the exact relationships have not been clarified, it can nevertheless be assumed that if this solubility limit is exceeded, an increasing build-up of a gel-like structure contributes to the fact that, even in the uncured state, the masses are not or only slightly washed out by water pollution such as rain .

In this context, the ratio of the amounts of cellulose ether to "free" water is obviously important, which is decisive for whether this solubility limit is exceeded or not. "Free" water is understood here to mean the water content of the sealing compound which is available to the cellulose ethers in order to dissolve in it. This means that the total water content of the joint sealant cannot be used for a corresponding calculation. Rather, it must be taken into account that the other constituents likewise require a certain amount of water or bind more or less firmly. So-called water values are known for most fillers. In the case of heavy spar, for example, this is 11 g of water per 100 g of heavy spar. For silica e.g. For the HDK V 15 type from Wacker-Chemie, values between 350 and 400 g water per 100 g silica can be determined. Values of this type provide the person skilled in the art with an indication of the amounts of “bound” water that he has to subtract from the total water content of the sealant in order to obtain the amount of “free” water. It is therefore preferred that this amount of "free" water in relation to the amount of the cellulose ether type used in each case results in a ratio which is above the respective solubility limit.

The situation becomes somewhat more complicated if the person skilled in the art has to take into account a water requirement which arises when the dispersed polymers contain groups capable of salt formation. If there is such an additional water requirement, the person skilled in the art may have to consult the corresponding manufacturer's information, estimate this need on the basis of empirical values or by approximate simple manual tests. If a joint sealing compound is to be produced in which the solubility limit mentioned is exceeded, the cellulose ethers cannot be added in the usual way - ie as a solution. The method according to the invention shows a way of producing such joint sealing compounds.

Furthermore, fillers can be contained in the joint sealants of the invention in an amount of 0 to 60, in particular 2 to 60% by weight, based on the total mass of the joint sealants. Such compositions have a high degree of transparency if they contain little or no fillers. Low filler contents can be present, in particular, in those compositions in which the fillers have an additional thickening effect, such as silica. If only fillers are used which do not have this additional effect, their content is usually between 35 and 60% by weight. One speaks here of highly filled masses.

According to a further advantageous embodiment of the invention, the jointing compounds contain chlorinated hydrocarbons, in particular chlorinated paraffins, as plasticizers, and nonionic surfactants as wetting agents. Commercial chlorinated paraffins with a chain length of about 10 to 18 carbon atoms and a chlorine content of about 40 to 70% by weight are preferred.

In a preferred embodiment, the joint sealants contain

25 - 90 wt .-% polymer dispersion, with highly filled

Joint sealants, in particular 25-40% by weight of polymer dispersion, 0-60% by weight, in particular 2 to 60% by weight of fillers, 0-1% by weight, in particular 0.3 to 0.5% by weight of wetting agent 0-20% by weight, in particular 5 to 15% by weight, and 0-10% by weight, in particular 4 to 6% by weight, of other customary ones

Additives such as thickeners, defoamers and

Pigments and up to

1.5% by weight of cellulose ether -% by weight in each case based on the total amount -

The cellulose ether content should not be much less than 0.1% by weight. Good results are shown in particular in the case of joint sealants in which, taking into account the general parameters such as cellulose ether type and free water content, the cellulose ether content is in a range from about 0.1 to 0.5% by weight of the total amount.

As already mentioned, in a preferred embodiment, the cellulose ethers are slurried in small amounts of water before the addition in the production of the joint sealant according to the invention. This ratio of cellulose ether to liquid is preferably in a range from 1: 2 to 1: 4, in particular approximately 1: 3. Furthermore, it is preferred that the pH regulators, in particular the bases, are added during production only after the cellulose has been added ¬ to make ether. This is of particular advantage in the case of retarded cellulose ethers, since the retardation is eliminated more quickly in the basic region. On the other hand, a neutral to basic setting of the joint sealants can have a favorable effect on their stability, in particular on their shear stability.

The polymer dispersion is usually initially taken in the preparation of the joint sealing compounds according to the invention. In a preferred form of the process, the usual additives with the exception of the pH regulators are then added and mixed in. Subsequently it is mixed with the cellulose ethers slurried in water and, after the fillers have subsequently been mixed in, the pH regulators are mixed in.

It can also prove to be advantageous if the filler is only added after the pH regulator has been added.

To avoid stirring in air and the formation of air bubbles in the product, stirring can be carried out under vacuum.

The joint sealants are preferably used as intended. They are particularly suitable for use in areas in which they are exposed to splash water, rain or other early water pollution.

The invention is explained in more detail below on the basis of preferred exemplary embodiments.

B e i s p i e l e

The masses described in the examples and further masses produced for comparison purposes were subjected to a washout test, a sprinkling apparatus according to DE 38 14078-A-1 FIG. 1 being used; the same apparatus is shown in side view in FIG.

The irrigation equipment consisted of a housing made of transparent plastic with the dimensions: height 70 cm, width 60 cm and depth 60 cm. It comprised a housing 1, a shower head 2, a sample bowl 3, a pump 4, a floor drain 5 and a shut-off valve 6 for the drain. The sample pan consisted of a vessel measuring 7 x 7 cm and had a depth of 2.5 cm. The shower head was a conventional hand shower as used for body care and was set so that the sample was irrigated evenly. The distance between sample 3 and shower head 2 was 30 cm.

The apparatus was operated with de-mineralized water, the pump generating an excess pressure of approximately 0.4 bar. The water flow rate was 300 l / h. The spraying with water was carried out 5 minutes, in each case 1 minute after filling and smoothing the surface of the masses to be tested. The washout (in% by weight) was determined by differential weighing before and after sprinkling.

The processability was measured according to DIN 52456. A 4 m bore, a pressure of 2 bar and a test volume of 200 ml were used.

The compositions described in the examples were also subjected to a test for their smoothness behavior. This test was carried out by 7 independently working people so that after applying a 30 cm long strand of mass to a smooth, flat, dark surface, the mass was smoothed with a spatula and fingers. The smoothness behavior was assessed on a scale from 1 (= very good) to 6 (= insufficient).

example 1

The following components were mixed intensively in a planetary mixer for a total of about 30 minutes:

1200 g commercial dispersion of an acrylic acid ester copolymer with approximately 55% by weight solid and free carboxy groups Trade name: Primal E 1785

200 g polybutene as an extender

20 g ethylene oxide adduct as a wetting agent

4 g commercially available halogenated preservative (AKTIZID TL 526)

200 g of butyl benzyl phthalate as a plasticizer

200 g water

80 g aliphatic low aromatic solvent (SHELLS0L D 60)

4 g highly viscous hydroxyethyl cellulose (NATR0S0L 250 HHR)

2040g uncoated chalk

40 g titanium dioxide and

12 g of 25% aqueous ammonia solution

Processability according to DIN 52456: 1000 g / min Smoothing behavior: good

Washout: 4.3% loss

The procedure was as follows, that the dispersion was introduced, then the polybutene, the ethylene oxide adduct, the preservative, the plasticizer and most of the water and solvent have been mixed intimately. The hydroxyethyl cellulose was slurried in a 1: 3 ratio in the remaining water and likewise added and mixed in and stirred for 5 minutes. Then the chalk and the titanium dioxide were incorporated and stirred for 10 minutes. After the ammonia had been added, stirring was continued for a further 15 minutes under vacuum at 40 mbar.

Example 2

The following components were mixed intensively in a planetary mixer for about 45 minutes:

1750 g of aqueous, commercially available dispersion based on a

Copolymers of vinyl acetate and ethylene (approximately 60% solids), with a pH of approximately 4.5 and a viscosity of approximately 1600 Pa.s at 20 ° C. (trade name: Vinnapas EP 17, from Wacker), 250 g chlorine paraffin (C12-C14, 49% chlorine), 2800 g barium sulfate (trade name: Schwerspat EW0), 100 g titanium dioxide (trade name: KR0N0S RN 56) 25 g sodium carbonate (technical, pure commercial goods), 25 g ethylene oxide adduct (approx. 9, 5 E0) of nonylphenol, 5 g of commercially available halogenated preservative, 37 g of hydroxyethyl cellulose with a viscosity of about

100,000 mPa.s of a 2% strength aqueous solution at 20 ° C. and a hydroxyethyl group content of 55% by weight (trade name: Natrosol 250 HHR).

The procedure was such that the polymer dispersion was initially introduced. The ethylene oxide adduct (emulsifier), the preservative, the titanium dioxide (pigment) and the chlorine paraffin were then added and mixed intimately. The hydroxyethyl cellulose was slurried in water in a ratio of 1: 3 and also added and the whole was mixed well. The sodium carbonate was then mixed in as a 10% aqueous solution. Finally, the barium sulfate (filler) was added and the mixture was stirred until smooth.

This mixture was filled into 310 ml cartridges and was stable for at least one year at temperatures up to 35 ° C.

Processability according to DIN 52456: 2300 g / min Smoothing behavior: good

Washout: 1% loss.

Example 3

The following components were mixed intensively in a planetary mixer for a total of about 40 minutes:

1400 g of aqueous, commercially available polybutyl acrylate dispersion

(approx. 62% solids), a pH of 6.0 - 6.5, a glass transition temperature Tg -50 ° C, a viscosity of about 250 mPas at 23 ° C and an average particle size of 0.4 μ, 200 g polybutene 12 g ethylene oxide adduct (approximately 9.5 E0) with nonylphenol, 8 g commercially available halogenated preservative, 10 g sodium carbonate (technically pure commercial goods) 146 g tap water 20 g hydroxyethyl cellulose with a viscosity of approximately 4000 mPas of 1%, aqueous solution at 20 ° C and a hydroxyethyl group content of 55 wt .-%, trade name: Natrosol 250 HHR 80 g titanium dioxide 1008 g barium sulfate (heavy spar EWO) 1096 g calcium carbonate (Omega BLP 3) 20 g hydrocarbons (with a KP of 180 ° C - 210 ° C like crystal oil 60)

Processability according to DIN 52456: 2830 g / min Smoothing behavior: good

Leaching: 1.7% loss

The procedure was such that the polymer dispersion was initially introduced. Then the ethylene oxide adduct (emulsifier), the preservative, the titanium dioxide (pigment), the polybutene and the crystal oil were added and mixed intimately. The hydroxyethyl cellulose was slurried in 56 g of water and added immediately and the whole was mixed well. The sodium carbonate was then mixed in, dissolved in 90 g of water. Finally, the fillers barium sulfate and calcium carbonate were added and stirred until smooth.

Claims

Patent claims

1. Containing early rainproof joint sealants

- aqueous polymer dispersions (I)

- Non-ionic cellulose ethers (II) from the group formed by hydroxyethyl, hydroxyethylmethyl, hydroxypropylmethyl and hydroxypropyl cellulose and

- If necessary, customary additives such as fillers, pigments, plasticizers, extenders, thickeners, defoamers, dispersants, pH regulators and preservatives and anti-aging agents and can be prepared by intimately mixing (I) with the other constituents, characterized in that (II ) slurried in slow release in small amounts of water and added and mixed in after slurrying.

2. Joint sealing compounds according to claim 1, characterized in that they contain dispersions of polyacrylicates capable of film formation and / or acrylate copolymers.

3. Joint sealants according to claim 1, characterized in that they selected dispersions of film-forming polymers or copolymers selected from the group consisting of ethylene / vinyl acetate, butadiene / styrene, vinyl acetate / maleic acid ester, silicone, urethane, vinyl acetate methacrylic acid / Contains chloroprene and isoprene polymers or copolymers.

4. Joint sealing compounds according to one of the preceding claims, characterized in that they contain an aqueous dispersion of poly-sulfide poly.

5. Joint sealing compounds according to one of the preceding claims, characterized in that the aqueous polymer or copoly er dispersions have solids contents of 40 to 75% by weight, in particular 45 to 65% by weight.

6. Joint sealing compounds according to one of the preceding claims, characterized in that cellulose ethers are contained which, in 2% strength aqueous solution at 20 ° C., have Brookfield viscosities of at least 5000, in particular at least 25,000, preferably at least 70,000 mPas.

7. Joint sealing compounds according to one of the preceding claims, characterized in that the ratio of cellulose ethers to free water is selected such that a complete solution of the cellulose ethers can no longer be achieved.

8. Joint sealing compounds according to one of the preceding claims, characterized in that they

25 - 90 wt .-% polymer dispersion, with highly filled

Joint sealants, in particular 25 - 40% by weight polymer dispersion, 0 - 60% by weight, in particular 2 to 60% by weight, fillers 0 - 1% by weight, in particular 0.3 to 0.5% by weight of wetting agent 0 - 20 % By weight, in particular 5 to 15% by weight, and 0-10% by weight, in particular 4 to 6% by weight, of other customary ones

Additives such as thickeners, defoamers and pigments and up to

contain.

9. Joint sealing compounds according to one of the preceding claims, characterized in that the cellulose ethers in slurry form are used in a ratio of 1: 2 to 1: 4, in particular about 1: 3, to water in their production.

10. Joint sealing compounds according to one of the preceding claims, characterized in that, during their manufacture, the pH regulators, in particular bases, are added after the addition of the cellulose ethers.

11. A process for the preparation of jointing compounds according to the preceding claims, characterized in that the polymer dispersion is introduced, the usual additives with the exception of the pH regulators are mixed in, then the mixing is carried out with the cellulose ethers slurried in water and after subsequent mixing the fillers are added to the pH regulators.

12. The method according to the preceding claim, characterized in that the admixture of the delayed cellulose ether slurried in water is carried out before the swelling delay.

13. A method for producing joint sealants according to claims 9 to 11, characterized in that the addition of the filler takes place after the addition of the pH regulator.

14. Use of the joint sealants as such, particularly in areas in which the joint sealants can be exposed to splashing water or rain.