CA1173227A

CA1173227A - Process for rendering substrates wettable

Info

Publication number: CA1173227A
Application number: CA000394842A
Authority: CA
Inventors: Bernhard Joos
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-01-29
Filing date: 1982-01-25
Publication date: 1984-08-28
Also published as: DE3276176D1; EP0057388A3; JPS57167725A; EP0057388A2; EP0057388B1; CH654319A5

Abstract

ABSTRACT OF THE DISCLOSURE

Difficultly wettable or non-wettable substrates, particularly substrates in the solid, gel-like or glass-like form, are rendered wettable in that at least one organo-metallic compound of an element of the fourth principal or secondary group of the periodic system of the elements, which serves as an active substance, causes an increase in energy of the substrate and is not soluble in the substrate, is added to the substrate in an amount causing an appreciable increase in energy and thus an increase of the surface tension of the substrate but no substantial change of the substrate structure and is homogeneously distributed in the substrate while form-ing finely divided punctiform aggregates whose particle size lies preferably in the range from 10-4 to 10-7cm. By means of this process substrates, particularly substrates which are subject to an intense mechanical stress, for example, vehicle tires as well as tool and machine parts, can be rendered wettable not only on the surface but throughout and thus permanently. Furthermore, with the aid of this process suspen-sions can also be stabilized permanently.

Description

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The present i~vention relates to a process for rendering substrates, particularly solid, gel-like or glass-like substrates wettable.
It is known that an equation of state F ( ~s~ ~f/ ~sf) exists between the interfacial-energy fundamental quantities, namely the surface tension of a substrate, for example, of a solid ~s, the surface tension of a liquid af, and the inter-facial tension Y sf between substrate and liquid. It is also known that the wettability of a substrate by a liquid depends on the ratio of the surface tensions of substrate and liquid and that the wettability of a substrate can be improved either }~y reducing the surface tension of the liquid or by increasing the surface tension of the substrate. The decrease of the surface tension of the liquid can be brought about, for example, by adding emulsifiers to the li~uid, a measure used in a large number of processes of the prior art. The increase of the surface tension of solids can be attained by a special surface treatment such as that ~lisclosed, for example, in Swiss Patent 397,237, German Patent 1,519,547, Canadian Patent 802,097, Italian Patent 731,137, French Patent 1,402,310, British Patent 1,079,391 and U. S. Pa-tent 4,139,660. However, the process mentioned last, which has proved to be excellent for the treatment of spectacle lenses and for the treatment of visors of diver's equipment, is not suitable for articles which are subject to mechanical stress, as for example, abra-sion! If the treated surface is eroded by abrasion, then the subadjacentnon-treated layer,which, like the ori~inal material, is wettable only with difficulty or not at all, i.s exposed.
This has the result that -the improvement of the we-ttability attained by the surface treatment is eliminate~ after short-~73Z;~
time mechanical stress and the surface treatment must be repeated.
Therefore, the present invention provides a process by means of which the wettability of substrates is permanently improved so that it is maintained even under mechanical stress.
According to the present invention there is provided a process for rendering a substrate wettable, which comprises incorporating into the substrate as active substance, at least one organo-metallic compouna of an element of the fourth main or secondary group of the Periodic system of the elements, which substance causes an increase in energy of the substrate and is not soluble in the substrate, in an amount, which causes an appreciable increase in energy and thus an increase of the surface tension of the substrate structure, said substance being homogeneously distributed in the substrate while form-ing finely divided punctiform aggregates.
An improvement of the wettability which is uniform within the entire substrate can be attained by this process so thatthe subadjacent layers, which are exposed as, the surface is worn off, have the same wettability as the original surface.
It is essential that the compounds serving as the active substance are applied not only to the surface of the substrate but that they are also distributed within the substrate. The efficiency of the active substance increases with the degree of distribution. This means that the more finely divided the active substance the greater will be the efficiency of the active substance. Therefore, particle sizes of approximately cm down to the colloidal distribution, i.e., to particle sizes of 10 to 10 7cm are recommended. It follows from what has been mentioned hereinbefore that the more finely divided the active substance the smaller will be the added amount of

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active substance. For sufficiently fine distribution, for example, for particle sizes < 10 cm, the result aimed for can be attained with added amounts of 3 to 5% by weigh~, rela~
tive to the weight of the substrate. The added amount of active substance usually depends on the degree of distribution and on the kind of substance, particularly on its properties and intended use. The upper limit of the added amount is determined by the effect on the mechanical properties of the substrate. It is generally true that the active substance may be added only in amounts such that its presence does not substantially change the structure of -the suhstrate and that its mechanical properties, particularly its strength, are not impaired so that i-ts suitability for the intended use is not detrimentally affected.
Among the compounds of elements of the fourth principal or secondary group of the Periodic system of elements which can be used as the activesubstance acetyl acetonate such as zirconium acetyl acetonates and tin dlchloride di(acetylaceton-ate) are particularly preferred.
For the selection of the compounds serving as the active substance it is essential that said compounds are not soluble in the substrate but that they are incorporated in the substrate in the form of finely divided punctiform aggre-gates. In this connection the definition of"punctiform" is not to be interpreted as a description of the shape of the aggregates but is merely intended to indicate the contrast to . , a continuous distribution.
The compounds serving as the active substance can be added to the substrate in the form of solutions, particularly in organic solvents~ or as suspensions or in the solid form.
The manner in which the active substance is added depends primarily on the type of substrate to be treated. The active 73~7 substance can be incorporated by means of conventional mixing processes. It is only important that a distribution of the active substance as finely divide~ in the substrate as possible is attained. Thus, in specific cases it can be advantageous to treat an iner~ carrier material, for example, a highly dispersed silica, with the active substance and to incorporate the carrier material loaded with active substance in the sub-strate. In this manner an extremely fine and homogeneous distribution of the active substance in the substrate is attained, especially since a mono- or bimolecular covering of the particles of the carrier material with the active substance is ade~uate. This procedure is recommended particularly in the cases where the substrate is a plastic material to which an inert carrier is added in any case in order to improve the mechanical properties of the substrate.
When treating a substrate formed by two or more components the procedure can be such that only one component is treated with the active substance, whereupon ~he treated component is mixed with the other components.
When applying the process to substrates of polymer materials such as homo- or co-polymers the active substance can be incorporatedin thepolymerization when required.
The improvement of the wettability of textiles con-sisting entirely or partially of synthetic fibres can be attained by adding the ac-tive substance to the material serving for the production of the fibres prior to the melt spinning and by dis-tributing it in said material. The wettability of textiles consisting of natural fibres, for example, cotton, wool and silk can be improved by treating the fibres or the fabric produced therefrom.
Yurthermore when the .substrates are porous or in the _~ ~} q ?"J'3 ~JLY~'~
form of highly dispersed aggregates, the substrates can be treated with a solution of the active substance or the active substance can be absorbed by the substrate. These processes are suitable particularly for highly dispersed aggregates which are to be used for the production of suspensions. ~n this manner a substantial improvement of the stability of the suspension can be attained.
The fact that in practically all the fields of technology problems resulting from the deficient wettability of substrates are encountered opens a wide and diversified field of application.
The most important applications include:
(a) Rendering substrates of polymexs, such as polyethyl-ene, polypropylene, polyvinyl cllloride, Teflon (a trademark~
and numerous other homo- and co-polymers wettable. This includes, for example, rendering vehicle tires and tool and machine parts of plastics wettable;
(b) Rèndering substrates of rubber and rubber-li~e - materials wettable, for example, those of vehicle tires;
(c) Rendering substrates of glass-like produc-ts wettable, such as those of optical instruments, vehicle windows as well as of tool and machine parts;
(d) Rendering building materials, particularly cement and concrete products wet-table;
(e) Rendering road surfaces wettable;
(f) Rendering textiles we-ttable, i.e., those consisting of natural fibres and those consisting entirely or partially of synthetic fibres, in order to improve their wearing proper-ties; and (g) Stabiliæing suspensions, particularly in dye chemis-try, for example, for improving the dyeing properties and for - ~7~3~
stabilizing dispersion dyes, in the production of catalysts, making pesticides ready ~or use as well as in pharmaceutical chemistry.
The above l.st ls not limitative it is merely meant to illustrate the diversity o~ feasible uses.
For the use of the process of the present invention for rendering substrates of polymers wettable or for improving their wettability various methods are suitable, for example;
a) Incorporating the active substance in the polymer material prior to forming;
b) Treating the monomer or one of the monomers with the active substance prior to the polymerization and tl~us incorpor-ating the active substance in the polymerization and c) When fillers are used, treating the filler with the active substance and subsequently distributing the filler in the polymer.
The last mentioned method is suitable particularly for the production of vehicle tires of plastics or rubber. In this case it is advisable to treat the carbon blac~ used as filler with the active substance and -to add the carbon black thus treated prior to the forming operation, or in the case of rubber prior to the vulcanization, and to distribute the carbon black in the plas-ticsor rubber material.
When rendering building materials, particularly cement and concrete products wettable, the procedure is suit-ably such that the aggregates, for example, sand, are treated with the active substance prior to the mixing operation. The active substance can be applied in both the solid form and in solution form. Another possibility is that the ac-.ive substance is added to the mixing water. The amount of ac-tive substance should be approximately 5 to 20% by weigllt, relative to the total weight of the mixture. Not only can a higher density be attained for concrete in this manner but also an improved adhesion of the vehicle tires in the case of road coverings of concrete an~ an improved adhesion of plaster to buildings.
For road coveringSof asphalt or tar products an improvement of the wettability of the coveringsand~thus an improved adhesion of vehicle tires can be attained by treating the aggregates, for example, sand, with the active substance prior to mixing them with -the asphalt or tar products. The optimal amounts o addition can be easily determined by routine tests.
In order to attain a permanent improvement of the wettability and thus of the wearing comfort of textiles consist-ing entirely or partially of synthetic fibres, it is advisable to carry out the trea-tment with the active substance prior to or during the production of the flbres. The procedure is suit-ably such that prior to putting the polymers used for producing the fibres into the melt-spinning apparatus the pol~mers are treated with the active substance and intimately mixed there-with, whereupon the mixture thus obtained is subjected to melt-spinning. The product thus obtained has a subs-tantially improved wettability, which is permanent and retained even after a plurality of washing operations and after mechanical stress of the fabrics produced from the fibres. Therefore, with respect to the wearing comfort, textiles treated in this manner are superior to fabrics impregnated in the conventional manner.
For textiles made from natural fibres, for example, cotton, wool or silk, it is advisable to treat the fibres or the fabrics produced therefrom with solutions of t~le active 32~7 substance and then to wash the fibres or fabrics, when required, at elevated temperature, for example, at boiling temperature.
With regard to the special importance of the appli-cation of the process according to the present invention to the stabilization o~ suspensions the stabilizing effect attain-ed by the process according to the present invention will be explained hereafter by the description of tests carried out with carbon suspensions~ The results obtained in these tests can also be applied, without any difflculty, to other suspen-sions, for example, dye suspensions and catalyst suspensions.Furthermore, these results open new possibilities for readying pesticides for use.
Stabilization of Suspensions The stabilizing effect of a treatment according to the present invention was demonstrated with the aid of a sedi~
mentation test on suspensions of carbon black and active carbon in water. Several test series were carried out using -tindichloride di(acetylacetonate~ (referre~ to hereafter as SnA) and zirconium acetyl ac~tonate (referred to hereafter as Zr~) as the active substance. These compounds were added to the carbon black and to the active carbon in varying amounts in order to determine the most effective concentrations. The samples treated with a specific amount of active substance were compared with an untreated sample. The compounds serving as the active substance were used in the form of ethanolic solutions or suspensions. The treatment was carried out by boiling under reflux for 30 minutes, paying attention to inten-sive intermixing, for example, by rotating. The solvent was then evaporated in vacuo or by means of a rotary evaporator and the residue was dried over P205 or silica gel and then pulverized. The comparison samples were only treated with ethanol, freed from the solvent, dried and pulverized.

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For carrying out the sedimentation test, samples of 0.3, 0.5, 0.6, 1.0 and 1.5g of carbon black or active carbon (treated and untreated) were mixed each with lOOml of water in a mixing cylinder (height l9cm), shaken for 10 minutes and then allowed to stand for a lenythy period for observation.
In some cases an additional preliminary treatment was carried out, as will be mentioned hereafter.
Test Series I
a) 0 7% (weight/weight) of SnA and ZrA lg of carbon black, which had been pretreated by washing with CHCQ3 and subsecluent drying and pulverizing, was mixed with lml of a solution containing 7mg of SnA in ~6~ ethanol and 7mg of ZrA
in 93% ethanol, diluted with 20ml of ethanol and allowed to rotate for 30 minutes at reflux temperature. The solvent was evaporated in vacuo and the residue was dried over phosphorus pentoxide in a desiccator. A comparison sample was treated with ethanol without adding active substance and further treat-ed in the same manner.
For carrying out the sedimentationtest portions 0.5g of the individual samples were mixed each with lOOml of water in a mixing cylinder (height 19cm) and allowed to stand, The change of the suspensions in the individua:L cylinders was observed visualLy. The results were as follows:

Time (min.) ' SnA (0.7%) ZrA (0.7%) Untreated 1 almost deposited almost deposited deposited 3 deposited deposited deposited b) 6.0% (weight/weight) of SnA and ZrA
The samples were produced in the sarne manller as those described under a), using each time lml of an ethanolic solu-tion of SnA or ZrA, which cont,ained 60mg of the cornpound.
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Furtherm~re, in the present case the test was not subjected to a preliminary treatment.
The sedi}nentation test was carried out in the manner described under (a) with samples containing each 0.5g in lOOml of water. The results were as follows:

Time (min.) SnA (6.0%) ZrA (6.0%) Untreated 0.5 nontransparent slightly one half black transparentdeposited 1nontransparent well three black transparentquarters deposited 2 faintly furtheralmost transparent settling,entirely still darkdeposited settling settlingdeposited completed, completed,clear twice as still a dark as for few suspended ZrA particles _ The repetition with 7.0% ~weight/weight~ of SnA and ZrA produced the same result.
c) 10% (weight/weight) of SnA and ZrA

Time (min.) SnA (]0%) ZrA (10%) Untreated___ _ _ _ _ _ 0.5one half black one half depositednontransparent deposited 1three quarters faintlythree quar-deposited transparentters deposited 2 almost upper almost completely margincompletely deposited brightdeposited threedeposited quarters clear deposi-ted still dark T _ Series II
a) 12% (weight/weight) of SnA
5g of carbon black were mixed with lOml of a 6%

~73~7 ethanolic SnA solution, whereupon the mixture was heated under reflux for 30 minutes. The solvent was then removed by means of a rotary evaporator and the residue was dried over silica gel in a desiccator. The sample obtained had a content of 12% (weight~weight) of SnA. For the production of ~he compar-ison sample 5g of carbon black were treated with lOml of ethanol in the manner described above and dried.
For carrying out the sedimentation test samples of 0.3g each (treated and untreated) with lOOml of water were each put into a mixing cylinder (height 19cm) and shaken for 10 minutes. The cylinders were allowed to stand while the change of the suspensions in the cylinders was visually observ-ed during the period defined above. The following results were obtained:

Time (min.) SnA (12%)Untreated 0.25 no changesettling (black, nontransparent) 1 no changemostly (~lack, deposited nontransparent) 3 no changeonly a few (black, suspended nontransparent) particles left , - This result is illustrated by the accompanying drawings in which the Figures are photographs 1 to 3.
Photograph 1 shows the suspension 0.25 minutes after mounting the cylinders;
Photograph 2 shows the suspension 1.0 minute after mounting the cylinders;
Photograph 3 sho~s the suspension 3 minutes after mounting the cylinders.

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The cylinder on the left contains 0.3g of carbon black treated with SnA (SnA content 12% (weight/we~ght)) in lOOml of water and the cylinder on the right contalns the same amount of untreated carbon black.
b) The repetition of the sedimentation test using 1.5g of carbon black (treated as described under (a) and untreated~ in lOOml of water showed the same result.
c) 20% (weight/weight) of SnA
7.5g of carbon black were treated Wit}l 25ml of a 25% ethanolic SnA solution in the manner described under (a).
A product having an SnA content of 20% (weight/weight) was obtained. The comparison sample was produced in tne manner described under (a).
For carrying out the test sedimentation samples of lg of carbon black each (treated with SnA and untreated), each sample with lOOml of water were placed in a mixing cylinder (height 19cm) and mixed on the shaking machine for 5 minutes.
The cylinders were allowed to stand while the change of the suspensions in the cylinders was ohserved visually. The follow ing results were obtained:

Time SnA (20%)Untreated 2 minutes nontransparent coarse particles black (entirecompletely height)deposited 5 minutes unchangedonly a small number of suspended particles left 10 minutes unchangedminor amount of suspended particles 1 hour unchangedextremely small suspended particles, almost ~ clear 1 d y _ _ __ un h_n ed _ clearly depos~ted ~7 3i~d)7 The repetition of the sedimentation test with suspensions having a content of 0.3g o~ carbon black instead of l.Og showed the same result.
d~ In this case carbon black was replaced by active carbon ("Carboraffin") and 5g of active carbon were treated with 15ml of a 6% ethanolic SnA solution in the manner describ-ed under (a). The product obtained had an SnA content of 18%
(weight/weight). The comparison sample was also produced in the manner described under (a).
For carrying out the sedimentation test suspensions containing each 1.5g of active carbon in lOOml of water were produced. The suspensions were shaken in a mixing cylinder (height l9cm) for 10 minutes and then observed visually. The results were as follows:

Time (min.) SnA (lg~) Untrea_ed nontransparent, translucent black but intensely -turbid unchanged brighter but not clear 120 upper margin (lcrn) ; continues slightly translucent to settle These tests show that amounts as small as6.0% by weight of active substance have a stabilizing effect but -that with concentratlons of 10 to 15% by weight a substantially greater stabilizing effect is attained. Furthermore, it has also been found that the structure, particularly the porosity of the substrate and thus the bonding strength for -the active substance associated therewith influences tlle stabilizing effect. For the application of this process to otl~er suspen-sions the optimal amounts of addition of the active substance can be easily determined by prellm;nary -tests.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for rendering a substrate wettable, which comprises incorporating into the substrate as an active substance, at least one organo-metallic compound of an element of the fourth main or secondary groups-of the Periodic system of the elements, which substance causes an increase in energy of the substrate and is not soluble in the substrate, in an amount, which causes an appreciable increase in energy and thus an increase of the surface tension of the substrate but no substantial change of the substrate structure, said substance being homogeneously distributed in the substrate while forming finely divided punc-tiform aggregates.

2. A process according to claim 1, in which the active substance is so distributed in the substrate that the particle size of the punctiform aggregates lies in the range from 10-4 to 10-7 cm.

3. A process according to claim 1, in which the sub-strate is in solid, gel-like or glass like form.

4. A process according to claim 1, in which the sub-strate is a porous substrate.

5. A process according to claim 1, in which the active substance is applied in the form of a solution.

6. A process according to claim 5, in which the solution is in an organic solvent.

7. A process according to claim 1, in which the active substance is applied in the form of a suspension.

8. A process according to claim 1, in which the active substance is added in the solid form having a particle size of ap-proximately 10-4 cm.

9. A process according to claim 1, in which the active substance is adsorbed on an inert carrier and the inert carrier loaded with the active substance is incorporated in the substrate.

10. A process according to claim 1, in which the sub-strate is formed by at least two components, one of said com-ponents being treated with the active substance and the component thus treated being then mixed with the other components.

11. A process according to claim 1, 2 or 3, in which the active substance is added prior to moulding, intimate mixing being brought about and the substrate being then given the desired shape.

12. A process according to claim 1, 2 or 3, in which the substrate is formed of homo- or co-polymers, the active sub-stance being polymerized into the substrate,

13. A process according to claim 4, in which the por-ous substrate is treated with a solution or suspension of the active substance until a practically complete absorption within the substrate is attained.

14. A process according to claim 1, 2 or 3, in which the active substance is added in an amount of 1 to 50% by weight, relative to the weight of the substrate.

15. A process according to claim 1, 2 or 3, in which the active substance is added in an amount of approximately 10% by weight, relative to the weight of the substrate.

16. A process according to claim 1, 2 or 3, in which the active substance is an acetyl acetonate of an element of the fourth main or secondary group of the Periodic system of elements.

17. A process according to claim 1, 2 or 3, in which the-active substance is zirconium acetyl acetonate or tin dichloride di(acetylacetonate).

18. A process according to claim 1, in which the sub-strate is formed of plastic materials.

19 A process according to claim 1, 2 or 3, in which the substrate is formed of plastics or rubber.

20. A process according to claim 1, 2 or 3, in which the substrate is a textile.

21. A process according to claim 1, 2 or 3, in which the substrate is a textile formed entirely or partially of synthetic fibres.

22. A process according to claim 1, 2 or 3, in which the substrate is a building material.

23. A process according to claim 1, 2 or 3, in which the substrate is cement or a concrete product.

24. A process according to claim 1, 2 or 3, in which the substrate is a road surface covering.

25. A process according to claim 1, 2 or 3, in which the substrate is in the form of a suspension, which is stabilized.

26. A process according to claim 1, 2 or 3, in which the substrate is in the form of a dye suspension, which is stabi-lized.

27. A process according to claim 1, 2 or 3, in which the substrate is in the form of a dispersion aye suspension which is stabilized.

28. A process according to claim 1, 2 or 3, in which the substrate is in the form of a catalyst suspension which is stabilized.

29. A wettable substrate having homogeneously dis-tributed therein in the form of finely divided punctiform aggre-gates as an active substance, at least one organo-metallic com-pound of an element of the fourth main or secondary group of the Periodic system of the elements, which substance causes an increase in energy of the substrate and is not soluble in the substrate, in an amount, which causes an appreciable increase in energy and thus an increase of the surface tension of the substrate but no substantial change of the substrate structure.

30. A substrate according to claim 29, in which the active substance is present in an amount of 1 to 50% by weight, relative to the weight of the substrate.

31. A substrate according to claim 29, in which the active substance is present in an amount of approximately 10%
by weight, relative to the weight of the substrate.

32. A substrate according to claim 29, 30 or 31, in which the active substance is an acetyl acetonate of an element of the fourth main or secondary group of the Periodic system of elements.

33. A substrate according to claim 29, 30 or 31, in which the active substance is zirconium-acetylacetonate or tin dichloride di(acetylacetonate).

34. A substrate according to claim 29, 30 or 31, formed of plastic materials.

35. A substrate according to claim 29, 30 or 31, formed of plastics or rubber.

36. A substrate according to claim 29, 30 or 31, which is a textile formed at least partially of synthetic fibres.

37. A substrate according to claim 29, 30 or 31, which is a building material.

38. A substrate according to claim 29, 30 or 31, which is cement or concrete.

39. A substrate according to claim 29, 30 or 31, which is a road surface covering.

40. A substrate according to claim 29, 30 or 31, which is in the form of a suspension.

41. A substrate according to claim 29, 30 or 31, which is in the form of a dispersion dye.

42. A substrate according to claim 29, 30 or 31, which is in the form of a catalyst suspension.