Abstract:
A composition comprising a trifunctional polysilazane and a polysiloxane having at least one hydrolyzable group and an optional fluoroalkyl group is effective for treating substrates to render their surface water repellent, oil repellent, and anti-fouling.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a surface treating agent for treating the surface of glass, glass lenses, mirrors, plastics, plastic lenses, metals, ceramics, porcelain, and pottery for forming anti-fouling substances which are tack-free, anti-dust-sticking, water repellent, and oil repellent. 
     2. Background Art 
     It is known to impart anti-fouling and water repellent properties to optical lenses such as eyeglass lenses and camera lenses by forming cured coatings of silicone or fluorocarbon polymers as the outermost surface layer. The treating agent used to this end is proposed in U.S. Pat. No. 4,678,688, for example, as comprising a trifunctional polysilazane such as C 8  F 17  C 2  H 4  Si(NH) 3/2  or C 4  F 9  C 2  H 4  Si(NH) 3/2  or polysiloxazane. When an article is treated with such a trifunctional silicon compound alone, its surface is covered solely with a polymer having a three-dimensional structure. This coating is soft or tacky and thus has the drawback that dust will deposit and stick thereto and fingerprints are left after the coating is touched with fingers. 
     JP-A 233535/1990 discloses a glass surface treating agent comprising a perfluoro group-bearing silane, an organopolysiloxane, an acid and an organic solvent. This agent is not fully satisfactory in water repellent and anti-fouling properties. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a surface treating composition capable of forming anti-fouling substances having water repellent, tack-free, and anti-dust-sticking properties. 
     We have found that when glass, glass lenses, mirrors, plastics, plastic lenses, metals, ceramics, porcelain, and pottery are treated on their surface with a composition comprising two organic silicon compounds of the formulas (1) and (2) defined below, anti-fouling substances which are tack-free, anti-dust-sticking, water repellent, and oil repellent are left on the surface. 
     The present invention provides a surface treating composition comprising first and second organic silicon compounds. The first organic silicon compound has the following general compositional formula (1): 
     
         Rf--R.sup.1 Si(NH).sub.3/2                                 (1) 
    
     wherein Rf is a perfluoroalkyl group of 1 to 10 carbon atoms and R 1  is a divalent hydrocarbon group of 2 to 10 carbon atoms. The second organic silicon compound has the following general formula (2): ##STR1## wherein R 2  independently represents monovalent hydrocarbon groups of 1 to 10 carbon atoms; R 3  is a hydrolyzable group of the following general formula (3) or (4): ##STR2## wherein R 6  is a divalent hydrocarbon group of 2 to 10 carbon atoms or oxygen atom, R 7  is a monovalent hydrocarbon group of 1 to 10 carbon atoms, R 8  is a divalent hydrocarbon group of 2 to 10 carbon atoms, X is a halogen atom, acyloxy group of 2 to 10 carbon atoms, or alkoxy group of 1 to 10 carbon atoms, and letter a is an integer of 0 to 2; R 4  is a monovalent hydrocarbon group of 1 to 10 carbon atoms which may contain fluorine atoms; R 5  represents R 3  or R 4 , the R 5  groups may be identical or different; letter k is an integer of 0 to 100, m is an integer of 0 to 100, n is an integer of 0 to 5, with the proviso that at least one R 5  group is R 3  when n is 0. 
     DETAILED DESCRIPTION OF THE INVENTION 
     As defined above, the surface treating composition of the invention contains two types of organic silicon compounds as essential components. 
     The first organic silicon compound has the following general compositional formula (1). 
     
         Rf--R.sup.1 Si(NH).sub.3/2                                 (1) 
    
     In formula (1), Rf represents perfluoroalkyl groups of 1 to 10 carbon atoms, preferably 4 to 10 carbon atoms, for example, C n  F 2n+1  groups (n=1 to 10, preferably 4 to 10) such as CF 3  -, C 4  F 9  -, and C 8  F 17  - groups. R 1  represents divalent hydrocarbon groups of 2 to 10 carbon atoms, for example, alkylene groups such as ethylene, propylene, butylene, hexylene, and octylene, cycloalkylene groups such as cyclohexylene, and arylene groups such as phenylene, with the ethylene, propylene and phenylene being especially preferred. 
     The second essential component of the surface treating composition according to the invention is an organic silicon compound having the general formula (2). ##STR3## 
     In formula (2), R 2 , which may be the same or different, represents monovalent hydrocarbon groups of 1 to 10 carbon atoms, for example, alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, octyl, and decyl; cycloalkyl groups such as cyclohexyl; alkenyl groups such as vinyl, allyl, propenyl, butenyl, and hexenyl; aryl groups such as phenyl and tolyl; and aralkyl groups such as benzyl and phenylethyl, with the methyl, ethyl, phenyl, and phenylethyl being especially preferred. 
     R 3  is a hydrolyzable group of the general formula (3) or (4). ##STR4## 
     R 6  represents divalent hydrocarbon groups of 2 to 10 carbon atoms or oxygen atom, examples of the divalent hydrocarbon group being as described for R 1 . R 7  represents monovalent hydrocarbon groups of 1 to 10 carbon atoms, examples of which are as described for R 2 . R 7  is preferably methyl. X represents halogen atoms, acyloxy groups of 2 to 10 carbon atoms, or alkoxy groups of 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms. Chlorine is a typical halogen atom. Examples of the acyloxy and alkoxy groups are given below. ##STR5## Letter a is an integer of 0, 1 or 2, and preferably equal to 0 or 1. ##STR6## 
     Herein R 8  represents divalent hydrocarbon groups of 2 to 10 carbon atoms, examples of which are as described for R 1 . R 7  and a are as defined above. 
     In formula (2), R 4  represents monovalent hydrocarbon groups of 1 to 10 carbon atoms, examples of which are as described for R 2 . In these hydrocarbon groups, some or all of the hydrogen atoms attached to carbon atoms may be replaced by fluorine atoms. Such substituted hydrocarbon groups are as described for R 2 , for example, trifluoropropyl. 
     R 5  represents R 3  or R 4 , and the R 5  groups may be identical or different, with the proviso that at least one R 5  group is R 3  when n is 0. 
     Letter k is an integer of 0 to 100, preferably 0 to 60, m is an integer of 0 to 100, preferably 0 to 60, and n is an integer of 0 to 5. As described just above, at least one R 5  group is R 3  when n is 0. This means that the compound of formula (2) is a siloxane which contains at least one hydrolyzable group represented by R 3  in its molecule and optionally, a fluoroalkyl group. 
     In the surface treating composition of the invention, the first and second organic silicon compounds of formulas (1) and (2) may be mixed in any desired ratio although the weight ratio of the first to second organic silicon compound is preferably from 1:0.1 to 0.1:1, and especially from 0.5:1 to 1:0.5. In this regard, a too low content of the first organic silicon compound of formula (1) would fail to provide oil repellency whereas a too low content of the second organic silicon compound of formula (2) would allow the treated surface to be tacky. In either case, the desired anti-fouling properties would be lost. 
     On use, the surface treating composition of the invention is previously dissolved in suitable solvents. The solvent used is not critical as long as both the first and second organic silicon compounds of formula (1) and (2) are soluble therein. For example, fluorinated compounds such as m-xylene hexafluoride, pentafluorodichloropropane, and octadecafluorooctane are preferred solvents. The concentration of the organic silicon compounds of formula (1) and (2) combined may be determined as appropriate depending on the treating method. Concentrations of more than 0.1% by weight are desirable in order to provide sufficient water repellent and anti-fouling functions. 
     No particular limits are imposed on the type of substrate to be treated with the surface treating composition of the invention. Exemplary substrates include inorganic substrates such as glass, glass lenses, mirrors, metals, ceramics, porcelain, and pottery, organic materials such as rubber and plastics, and optical functional materials such as plastic lenses and liquid crystal display filters. 
     Also the treating method is not critical. For example, the surface of a substrate is wiped with a piece of fabric impregnated with the surface treating composition. Other useful methods include brush coating, dipping, spin coating, curtain coating, and vacuum deposition. 
    
    
     EXAMPLES 
     Examples of the invention are given below by way of illustration and not by way of limitation. All parts are by weight. 
     Examples 1-17 &amp; Comparative Examples 1-4 
     Surface treating compositions in solution form were prepared by mixing a solution containing 5 parts of a first organic silicon compound 1-1 or 1-2 in 95 parts of the solvent shown in Table 2 and a solution containing 5 parts of a second organic silicon compound 2-1 to 2-5 in 95 parts of the solvent shown in Table 2, and diluting the mixture with the solvent so as to give the concentrations of organic silicon compounds shown in Table 2. Several substrates were treated with these solutions by the following procedure. The treated substrates were examined for a contact angle and fingerprint wiping. The results are shown in Table 2. 
     Substrate 
     Glass: float glass plate which had been previously cleaned on the surface with acetone 
     Plastic lens: polycarbonate lens having a hard coat on its surface and silica evaporated thereon. 
     Polycarbonate: polycarbonate plate which had been previously cleaned on the surface with acetone 
     PET: PET film having silica evaporated thereon 
     Treating Procedure 
     The substrate was dipped in the surface treating solution for 5 minutes, taken out of the solution, dipped twice in the same solvent as used in the solution, each for 1 minute, for cleaning, and then dried at 100° C. for 10 minutes. 
     Structure of Compound 
     Organic silicon compound of formula (1) 
     organic silicon compound 1-1: C 4  F 9  C 2  H 4  Si(NH) 3/2   
     organic silicon compound 1-2: C 8  F 17  C 2  H 4  Si(NH) 3/2   
     Organic silicon compound of formula (2) ##STR7## 
     
                       TABLE 1______________________________________R.sup.2  R.sup.3 R.sup.4   R.sup.5-1                          R.sup.5-2                                k   m    n______________________________________2-1 CH.sub.3      HDLZ1   --      CH.sub.3                            CH.sub.3                                  50  0    3  2-2 CH.sub.3 -- -- CH.sub.3 HDLZ1 30 0 0  2-3 CH.sub.3 -- -- HDLZ1 HDLZ1 30 0 0  2-4 CH.sub.3 -- -- CH.sub.3 HDLZ2 30 0 0  2-5 CH.sub.3 -- -- CH.sub.3 HDLZ3 30 0 0  2-6 CH.sub.3 -- --C.sub.2 H.sub.4 CF.sub.3 HDLZ1 HDLZ1 10 10  0______________________________________ HDLZ1: hydrolyzable group --C.sub.2 H.sub.4 SiCl.sub.3 ##STR8## HDLZ3: hydrolyzable group --OSi(OCH.sub.3).sub.3 -  Tests 
    
     Contact Angle 
     Contact angles of the treated surface with water and hexadecane were measured by means of a contact angle meter CA-X150 by Kyowa Kaimen Kagaku K. K. 
     Fingerprint Wiping 
     A thumb was pressed onto the treated substrate. After 1 hour, the fingerprint was wiped 10 strokes with tissue paper. After wiping, the surface was visually observed. 
     A: no fingerprint left 
     B: some fingerprint left 
     C: fingerprint left substantially intact 
     
                                           TABLE 2__________________________________________________________________________  Organic  Organic  silicon silicon  compound of compound of  formula (1) formula (2)  Contact angle      Blend    Blend                 (°)                                               Finger-      amount   amount                     Hexa-                                               print  No. (%) No. (%) Solvent Substrate Water decane wiping__________________________________________________________________________Example  1 1-1 3 2-2 3 1,1,1,2,2- glass 100.2 69.2 A  pentafluoro-3,3-  dichloropropane  2 1-1 3 2-5 3 1,1,1,2,2- glass 98.1 68.9 A  pentafluoro-3,3-  dichloropropane  3 1-2 3 2-1 3 m-xylene glass 102.8 71.5 A  hexafluoride  4 1-2 3 2-2 3 m-xylene glass 104.5 72.3 A  hexafluoride  5 1-2 3 2-3 3 m-xylene glass 103.8 71.9 A  hexafluoride  6 1-2 3 2-4 3 m-xylene glass 102.9 70.3 A  hexafluoride  7 1-2 3 2-5 3 m-xylene glass 100.5 69.8 A  hexafluoride  8 1-2 3 2-6 3 m-xylene glass 105.1 76.5 A  hexafluoride  9 1-2 1 2-2 1 m-xylene glass 103.1 73.9 A  hexafluoride  10   1-2 4 2-2 2 m-xylene glass 105.8 76.1 A  hexafluoride  11  1-2 2 2-2 4 m-xylene glass 96.6 66.5 B  hexafluoride  12  1-2 3 2-2 3 m-xylene plastic lens 105.2 76.1 A  hexafluoride  13  1-2 3 2-2 3 m-xylene polycarbonate 103.2 72.1 B  hexafluoride  14  1-2 3 2-2 3 m-xylene PET film 104.7 75.9 A  hexafluoride  15  1-2 3 2-5 3 m-xylene plastic lens 103.6 73.1 B  hexafluoride  16  1-2 3 2-5 3 m-xylene polycarbonate 103.2 72.1 B  hexafluoride  17  1-2 3 2-5 3 m-xylene PET film 104.7 75.9 B  hexafluoride  Comparative  Example  1 1-1 3 -- -- m-xylene glass 103.9 74.6 C  hexafluoride  2 1-2 3 -- -- m-xylene glass 105.1 76.6 C  hexafluoride  3 -- -- 2-2 3 m-xylene glass 95.6 62.1 C  hexafluoride4      C.sub.8 F.sub.17 C.sub.2 H.sub.4 Si(OCH.sub.3).sub.3                2%  isopropyl alcohol                             glass   101  64.5 C   -                                                   2% ##   -  0.1N-HCl 0.10%__________________________________________________________________________ 
    
     Examples 18-29 &amp; Comparative Example 5 
     Surface treating compositions in solution form were prepared by mixing a solution containing 5 parts of the first organic silicon compound 1-1 or 1-2 (the same as used in Examples 1-17) in 95 parts of the solvent shown in Table 4 and a solution containing 5 parts of a second organic silicon compound 2-7 to 2-10 in 95 parts of the solvent shown in Table 4, and diluting the mixture with the solvent so as to give the concentrations of organic silicon compounds shown in Table 4. Several substrates were treated with these solutions by the same procedure as in Examples 1-17. The treated substrates were examined for a contact angle and fingerprint wiping. The results are shown in Table 4 where the results of Comparative Examples 1, 2 and 4 are reproduced. 
     Organic silicon compound of formula (2) 
     
                       TABLE 3______________________________________  #STR10##   - R.sup.2 R.sup.4   R.sup.5-1                         R.sup.5-2                               k    m    n______________________________________2-7  CH.sub.3        --        CH.sub.3                         CH.sub.3                               50   0    3  2-8  CH.sub.3 -- CH.sub.3 R.sup.3 30 0 0  2-9  CH.sub.3 -- R.sup.3 R.sup.3 30 0 0  2-10 CH.sub.3 --C.sub.2 H.sub.4 CF.sub.3 R.sup.3 R.sup.3 10 10______________________________________                                         0 ##STR11## - 
    
     
                                           TABLE 4__________________________________________________________________________  Organic  Organic  silicon silicon  compound of compound of  formula (1) formula (2)  Contact angle      Blend    Blend                 (°)                                               Finger-      amount   amount                     Hexa-                                               print  No. (%) No. (%) Solvent Substrate Water decane wiping__________________________________________________________________________Example  18 1-1 3 2-7 3 1,1,1,2,2- glass 103.2 70.2 A  pentafluoro-3,3-  dichloropropane  19 1-1 3 2-8 3 1,1,1,2,2- glass 102.1 73.4 A  pentafluoro-3,3-  dichloropropane  20 1-2 3 2-8 3 m-xylene glass 104.1 73.1 A  hexafluoride  21 1-2 2 2-8 4 m-xylene glass 103.4 68.3 B  hexafluoride  22 1-2 4 2-8 2 m-xylene glass 104.2 73.7 B  hexafluoride  23 1-2 1 2-8 1 m-xylene glass 103.4 72.3 A  hexafluoride  24 1-2 3 2-8 3 m-xylene plastic lens 106.8 73.9 A  hexafluoride  25 1-2 3 2-8 3 m-xylene polycarbonate 100.1 70.5 A  hexafluoride  26 1-2 3 2-8 3 m-xylene PET film 107.1 74.8 A  hexafluoride  27 1-2 3 2-9 3 m-xylene glass 102.8 71.1 A  hexafluoride  28 1-2 3 2-9 3 m-xylene plastic lens 106.9 72.9 A  hexafluoride  29 1-2 3  2-10 3 m-xylene glass 104.1 74.5 A  hexafluoride  Comparative  Example   1 1-1 3 -- -- m-xylene glass 103.9 74.6 C  hexafluoride   2 1-2 3 -- -- m-xylene glass 105.1 76.6 C  hexafluoride   5 -- -- 2-8 3 m-xylene glass 95.6 62.1 C  hexafluoride 4     C.sub.8 F.sub.17 C.sub.2 H.sub.4 Si(OCH.sub.3).sub.3                2%  isopropyl alcohol                             glass   101  64.5 C   -                                                   2% 2##   -  0.1N-HCl 0.1%__________________________________________________________________________ 
    
     After surface treatment with the compositions of the invention, substrates become highly water and oil repellent and improved in wiping-off of stain. 
     Japanese Patent Application Nos. 303552/1997 and 303553/1997 are incorporated herein by reference. 
     Although some preferred embodiments have been described, many modifications and variations may be made thereto in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.