CA1298522C

CA1298522C - Aziridine-treated articles

Info

Publication number: CA1298522C
Application number: CA000510965A
Authority: CA
Inventors: George Canty; Robert E. Jones
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1985-06-14
Filing date: 1986-06-06
Publication date: 1992-04-07
Anticipated expiration: 2009-04-07
Also published as: US5057371A; EP0206669A2; AU5791886A; DE3650693T2; EP0206669A3; EP0206669B1; JPS61293279A; ATE169951T1; DE3650693D1; AU587029B2

Abstract

ABSTRACT

An article having an aziridine-modified surface is provided. Functional layers may be applied to the modified surface. Such layers exhibit good adhesion to the article.

Description

AZIRIDINE-TP~EATED ARTICLES
.

Technical Field The present invention concerns the treatment of organic and inorganic surfaces. More specifically i-t concerns articles which have a surface that has been treated so as to improve the adhesion of various subse-quently applied materials.

Background Art Many techniques have been employed to treat surfaces for the purpose of improving the adhesion of various subsequently applied materials. Such techniques include subjecting sur~aces to high energy (e.g., corona discharge, electron beam discharge, flame treatment and the like) and chemically modifying surfaces by chemical etching and the li~e. Such techniques require the use of expensive equipment and may expose the operator to high energy radiation or dangerous chemicals.
Parachlorophenol has been used as a surface treatment. This material provides only minimal improvement in adhesion compared to the present lnvention and suffers from the major disadvantage that it is hazardous to human health.
Surfaces have also been coated with primers in an effort to enhance the adhesion of subsequently applied coatings. Primers frequently must be cured after application. This adds additional time and expense to the manufacturing process. Additionally, the substrate often must be treated in some way (e.g., subjected to high energy) in order that the primer will exhibit suf~icient adhesion to it. Primers are also frequently compounded to meet the needs of a specific coating or class of such coatings. For these and other reasons, the use of primers has not proven entirely satisfactory.

Yet another approach is to incorporate aziridine-containing materials in-to functional coatings which contain groups reactive with the aziridine functionality. These coatings are then applied to a substrate. See, for example, U.S. Patent Nos.
~,017,280; 4,167,414; 4,181,528; and ~,241,169.
These references disclose that the substrate and the functional coatings must each contain yroups reactive with the aziridine group so that the aziridine essentially acts as a tie layer to better anchor the functional coatings to the substrate through crosslinXing reactions. They also generally disclose that substrates which do not inherently contain the requisite surface functionally to react with the aziridine (i.e., inert materials) must undergo prior modification by oxidative treatment to incorporate that functionality. Such substrates include, for example, conventional polyesters such as poly(ethylene terephthalate), aonventional polyolefin films such as polyeth~lene, polypropylene and polystyrene.
U.S. Patent No. g,~18,164 discloses coating aramid filaments with polyfunckional aziridines. The coated filaments are used as reinforcing fibers in unsakurated polyester matrices wherein they are totally encased in the matrices.
Disclosure of the Invent,ion The present invention is directed to articles havin~ at least one essentially flat surface which has been treated with a composition consis~ing essentially of a compound having at least one aziridine funckionality. The treatmen~ renders the surface more adherent ~o subsequenkly applied layers. The present invention is also directed to processes for modifying such B

2a 60557-3053 surfaces.
Accordlng to one aspect o~ the lnventlon there is provlded a flat sheet-llke article havlng a thln, azirldine-modified surface thereon, said surface comprising the product resultlng from the interacti.on between said sheet and a treatment composltlon consisting essentially of an azlridlne-contalnlng compound, wherein sald azlridine-containiny compound ls present ln an amount sufflclent to permit lnteraction between said sheet and sald azlridine~containing compound, and said compositlon ls essentlally free of any other component that would prevent said lnteraction.
According to a further aspect o~ the present invention there ls provlded a flat sheet-like artlcle comprlslng a substrate havlng at least one essentially flat ma~or surface and a functional material at~ached to said surface, wherein the lnterface between sald surface and sald functlonal materlal has been modl~ied by lnteractlon between sald substrate an~ a composltlon conslstlng essentially of a compound contalnlng at least one azlrldine group, whereln sald azlrldlne group has the formula , R
-~N - ~ ~R
\
~3 \ R4 wherein Rl, R~, R3 and R4 are lndependently selected from hydrogen and lower alkyl groups.

~' 3,~
2b According to another aspect of the present lnvention there is provided a fla~ sheet-like article having at least one essentially flat major sur:Eace, a solven~ resistant treatment layer on saicl major surface comprising the interaction product between saicl surface and a composition consisting essenkially of a compound having at least one aziridine functionality, and a functional layer on said treatment layer.
According to a still further aspect of the present invention there is provided a method of modifying the surface of a flat sheet-like article having at least one essentially flat ~urface comprising the steps of (a) preparing a composition consisting essentially of an aziridine-contclinincJ compound, (b) applyincl said composition to said essentially flat surface, (c) subjecting said article to a temperature and for a time sufficient to cause interaction between said ~lat surface and said aziridine-contclining material to provide an aziridine-modified surface.
~0 According to another aspect of the present invention there i5 provided a method pf modifying the surface of a flat sheet-like article comprising the steps of (a) orienting said sheet-like article in a first dire~tion, (b) applying a composition consisting essentially of a compound having at least one aziridine functionality to an essentially flat major surface of said article, (c~ processing said surface at a temperature and for a 2c major surface, (cl) orientiny said sheet-like article in a second direction which is at an angle of 90Q to said first direction.
It has been found that the adhesion of a variety of functional coatings to a surface can be improved if, prior to applyillg the c~oating, the surface is first ~ r~
.~

5'~

treated with an aziridine-containing compound. Surprisingly this improvement is achieved on a wide variety of inorganic and organic surfaces including metals, glass, ceramics and polymers. These surfaces include normally inert materials such as the polyesters and polyolefins discussed above. Even more surprising is the fac-t that the improvement is achieved even though the surface has not undergone oxidative treatment.
The articles of the invention have the highly desirable characteristic that a variety of subsequently applied functional materials adhere well to the modified surface. Such functional materials include magnetic recording medium (e.g., particulate materials in a binder), gelatin and other layers used in photographic film, adhesive coatings (e.g., pressure sensitive, heat activated, solvent activated, etc.), radiation sensitive compositions (e.g., diazo systems, photo-reactive polymers, etc.) silane coatings, etc~
The articles of the invention can comprise any flexible or rigid substrate having at least one essentially flat surface. Included in this definition are sheet-li]ce articles such as tapes, ribbons, films, discs, and the like. Sheet like materials may have opposed parallel surfaces and are generally substantially thinner than they are either wide or long. However, also included in this definition are articles which are substantially thicker and which need not have opposed parallel surfaces.
The articles of the invention demonstrate excellent room temperature shelf stability as there is no measurable reduction in their ability to anchor subsequently applied coatings even though the articles have been stored for extended p`eriods of time.

Detailed Description The aziridine-containing compounds useful in the invention include any compound containing at least one aziridine functionality, and preferably 2 or more aziridine functionalities.
Th~ aziridine-containing compound may also contain other Eunctional groups. Preferably these groups are not reactive with the aziridlne functionality but are reactive with functional groups contained in the subsequently applied layer. Thus, for example, the aziridine-functional compound may also contain one or more hydroxyl groups. Such an aziridine-functional compound is particularly useful where the subsequently applied layer contains isocyanate groups.
The aziridine-functional compounds useEul in the present invention may be represented by -the formula A ~ / ~
\C /

R n wherein A i9 an n valent organic or inorganic group, n is a whole number of at least one (preferably 2 to 4), and E~l, R2, R3 and R4 may be the same or different and are individually selected from the group consisting of hydrogen and lower alkyl (branched or straight chain) groups containing from 1 to 3 (preferably from 1 to 4) carbon atoms.
The nitrogen atom of the aziridine group is preferably linked to an atom having a valence of 4 or 5 (most preferably C or P). Preferably, E~ , R and R3 are each hydrogen and R is selected from hydrogen and alkyl containing from 1 to 4 (most preferably 1 to 2) carbon atoms.
A may be an aliphatic, aromatic or alicyclic organic radical which may contain atoms such as oxygen, sulfur, nitrogen, etc. A may also be an inorganic radical, such as -P-O or -P=S.
A pxeferably is R5-~ ~ or R5 ~N

O
or R5 ~ (CH2)XO ~ C (CH2 ~ m where R is an m-valent aliphatic, aromatic or alicyclic radical whlch may contain atoms other than carbon, e.g., oxygen, nitrogen or sulfur, m is a whole number of at least 1, and x and y are individually 0, 1 or 2.
Specific examples of useful aziridine-containing materials include ~
A. "CX-100" available from Polyvinyl Chemical Industries and believed to have the Eormula _ _ CH3CH2C- CH2O2CCH2CH2N \ ¦ (FORMULA A) (Trimethylol-tris[~-(N~methylaziridinyl])]-propionate) ~ B~ "XAMA-7" available from Cordova Chemical Company and believed to be a mixture of 20C ~ H2O2CCH2CH2N / ¦ ~ and (~ORMULA Bl) 2C ~CH2o2~cH2cH2N \ ~ FORMULA B2) ~ rf~ f~

C H~C O O CH
I/N-C~C N/ 1 2 (FORMULA C) (1,1'-~1,3-phenylenedicarbonyl)bis[2-methyl aziridine]) 2C~ 7H3 /CH2 ¦ N-C-C-CH -fH-CH -C-N ¦ (FORMULA Dl) CIH2 f 2 :

H2C \ fH3 CH3 /CH2 S ¦ N-C-C-CH -C-CH -C-N ¦ (FORMULA D2) lH2 CIH2 (l,l'--trimethyladipoyl bis[2-ethylaziridine]) E- H2C \ 1l R /CH2 ¦ / N-C~CH2~7C- N\ ¦ ( FORMULA E) HC fH

(l,l'-azelaoyl his[2-methyl aziridine]) f ~ < fH (FORMULA F) f 2 C=O fH2 CH3 / N \ CH3 : CIH2 : CH3 (1,1',1"-(1,3,5-benzenetriyltricarbonyl)-- tris[2-ethylaziridine]) 5~

G. / CH2 HOCH2CH2OCCH2CH2- N ~ ¦ (FORMULA G) O CH

(2~hydroxyethyl-3~2-methyl aziridinyl)-propionate) H. CH
C2H5OC2H40c2H40lclc~2cH2-N / ¦ ~FORMULA H) O CE~

(Ethoxy ethoxy ethyl-3~2-methyl aziridinyl)-pxopionate) I. O O CH
Il ll / 2 H2C=CCCH2CH2NHCN ~ ~FORMULA I) CEl3 CH

2-methyl aziridinyl-2~2-methyl propenoyloxy) ethyl urea The amount of aziridine-containing material needed to provide the modified surface must be sufficient to permit interaction between the aziridine and the surface to be modified. The interaction may be the chemical reaction between the aziridine group~s) and functional groups present at -the surface, mechanical interlocking between fissures or openings in the surface and the aziridine-containing material, or entrainment of the azlrldine-containing group in the treated surface. Entrain-ment may occur by swelling of ~he surface due to contact with~either a solvent or the aziridine-containing material fol~lowed by subsequent penetration of the aziridine-con-taining material into the surface to be treated. Combina-tions of these interactions may also occur.

.
.

5~

As noted, both organic and inorganic surfaces can be modified in the practice of -the invention. Examples of organic surfaces include polyesters (e.g., saturated and unsaturated, linear and branched) such as poly(ethylene terephthalate), poly(l,4-cyclohexylenedimethylene terephthalate), poly(ethylene naphthalate), polymers of maleic anhydride and ethylene glycol, polymers prepared from ethylenically unsaturated monomers such as poly-ethylene, polypropylene, polymethylmethacrylate, polyvinyl fluoride, polyvinylidene fluoride, polystyrene, polyvinyl chloride, polyvinyl acetate, polymethylmethacrylate, copolymers of ethylene and acrylic acid, copolymers of ethylene and vinyl acetate, polycarbonates such as the Lexan M series of materials available from General Electric, polyimides such as the Kapton series of materials available from DuPont, polyamides such as the DartekT series of nylon materials available from DuPont, cellulose acetates, polydimethylsiloxanes and the like. Oriented and unoriented organic surfaces may be used in the practice of the invention.
Examples of useful inorganic surfaces include metals (such as aluminum, copper, etc.), glass and ceramic.
The layer provided by the aziridine treatment may be continuous, intermittent, smooth, rough, textured, etc. Moreover, it may vary in thickness if desired.
Normally, suitable adhesion promotion is achieved if the aziridine treatment provides a layer at least 0.005 microns (~) thick. Preferably this layer is from 0.01 to 5~ thick and most preferably from 0.02 to 0.5 thick.
Treatment may be easily accomplished. For example~ the surface to be treated is first preferably cleaned to remove dirt and grease. Known cleaning techniques may be used. The surface is then contacted with a composition containing an aziridine-containing compound using a variety of techniques such as brushing, spraying, s~

roll coating, curtain coating, knife coating, etc., and then processed at a time for a temperature so as to cause interaction between the surface and the aziridine group(s).
A wide range of processing temperatures may be used to bring about the desired interaction. The particular temperature employed must be sufficient to permit interaction between the aziridine-containing compound and the substrate but not so high as to degrade either the surface being treated or the aziridine functionality. Typical processing temperatures range from 15 to 250C. PreEerably the treated surface is processed at a temperature of from 70 to 140C.
The resulting coating comprises a thin dry, preferably solvent~resistant layer on the surface of the subs-trate. This layer is most preferably insoluble in common solvents for the substrate. Thus, for example, after being formed on a polyester surface, the layer cannot be dissolved in common solvents for polyester.
The treatment composition may comprise either the aziridine compound alone or, alternatively, a water or solvent solution or dispersion of the aziridi.ne.
Such liquid treatment cornpositions typically comprise from 0.01 to 15 (and preferably from 0.2 to 1) percent by weight of the aziridine. Examples of organic solvents useful in such compositions include acetone, dichloroethane, butyl cellosolve, methyl ethyl ketone, toluene, heptane, xylene, ethyl acetate, etc.
If water is employed as the liquid vehicle, it is preferred that a surfactant material also be included in the treatment composition~ The surfactant may comprise up to 2.5 times the weight of the aziridine component in the treatment composition. Anionic, cationic, non-ionic, or amphoteric surfactant materials may be employed.
Examples of useful surfactants include octylphenoxy polyethoxy ethanol, alkylaryl polyethersulfonates, ethoxylated fluorochemical alcohols, fluoroaliphatic polyesters, etc.

In certain instances it has been found that surfaces treated with a composition comprising water, aziridine and op-tionally surfactant is textured, i.e., it has clus-ters of pronounced surface irregularities separated from one another by areas of smooth surface.
The clusters, which may be seen as projections from a replicated surface when viewed under 32,000X magnification using a transmission electron micrograph, are not present when an organic solvent is used as the liquid vehicle.
While the treatment composition employed in the present invention consists essentially of the aziridine compound, it is permissible to employ other ingredients such as binders, surfactants, slip agents, colorants (e.g., dyes and pigments), antioxidants, UV light stabilizers and the like. These ingredients are essentially non-reactive with the aziridine under normal conditions, that is they do not react with the aziridine functionality.
I~ reactive ingredients are employed, they must be present in insignificant amounts so that they do not prevent interaction between the substrate suxface and the aziridine group.
Within these guidelines, varying amounts of inert other ingredients may be employed. For example, binders may comprise up to 50 percent by weight of the treatment composition. Slip agents, colorants, antioxidants and UV light stabilizers may comprise up to 5 percent by weight of the treatment composition.
The articles of the invention are uniquely suited to being prepared by continuous in-line manufacturing processes. The treatment composition may be applied to either unoriented, partially oriented, or fully oriented websO Treated unoriented or partially oriented webs may be further oriented if desired. Conventional orientation conditions may be used in such processes. Thus, the web may be stretched in the lengthwise direction by known techniques and subsequently stretched in the crosswise 1~- 1 , 5~, direction using known techniques. Alternatively, biaxially stretched in both directions at the same time~
A particularly useful manufacturing process comprises the steps of stretching the web in the lengthwise direction at 80-95C, applying the treatment composition to the uniaxially orien-ted web, stretching the treated, uniaxially oriented web at 100-120C in the crosswise direction, and then heat setting the biaxially oriented web at 200-250C. Typically webs are oriented by being stretched to from 1 to 5 times their original dimension wherein the length to width stretch ratio may vary from 1:1 to 1:5 and from 5:1 to 1:1. Other stretch ratios may be used if desired.
After the surface has been treated, a layer of functional material may be applied thereto using known techniques. The phrase "functional material" means any material subsequently applied to the treated surface.
These materials include, as noted above, a magnetic recording medium, an adhesive, a radia-tion sensitive composition, and a silane coating. The functional layer is attached at an interface which has been modified by interaction between the surface and the aziridine-con-taining compound. The functional layer may be smooth, rough textured, continuous, intermittent the the like.
Moreover, it may vary in thickness if desired.
The present invention will be further explained by reference to the following examples wherein all percents are percents by weight unless otherwise specified. These examples serve to further illustrate the present invention and do not limit it.

A treatment composition containing "CX-100"
available from Polyvinyl Chemical Industries and fluid media (Acetone) was prepared by combining the ingredients in a suitable mixing vessel and stirring them at 20C

s~

until the mixture was uniform. The treatment composition was then applied to the substrates using Meyer bar coating and dried in an air circulating oven to provide treated layers having various thicknesses.
The inorganic substratés were first scrubbed with a concentra-ted detergent solution using a camel hair brush, rinsed thoroughly in warm tap water, rinsed with delonized water, then dried ovexnight at room temper-ature before being treated.
A functional magnetizable coating was applied over the aziridine-treated surface and dried to provide a dry layer 3~ thick. The magnetizable coa-ting comprised 66 weight percent acicular iron oxide particles having an average length of 0.6 micrometer and an aspect ratio of 8:1. The binder comprised polyurethane elastomer, phenoxy resin and other ingredients substantially as described in the comparative example of U.S. Patent No. 4,210,703.
The functional coating was applied using a Meyer rod and dried in a forced air oven at 71C for one minute followed by 82C for one minute. The coated substrates were then aged for five days at room temperature and then tested for adhesion using the following scrape adhesion test.
The sample to be tested was fastened to a flat, solid, surface with the functional coating being exposed. A "BIC" disposable razor was placed on the coating such that the blade contacted the coating. While applying a force on the razor normal to the coating in excess of 5 kg. the razor was pushed away from the tester at a rate of 10-20 cm/min. The adhesion of the coating to the substrate was obs`erved and rated as follows:
~ r~ rl~

RATING OBSERVATION
Excel:Lent 100~ retention of coating on modified surface Good 90-100~ retention of coating on modified surface.
Fair 75-90% retention of coating on modified surface.
Poor Less than 75~ retention of coating on modified surface.

The trea-tment conditions and results are set forth in Table 1.

T~BLE 1 TREATMENT
DRY CONDITIONS LAYER
(TEMP( C)/TIMEtMin)) THICKNESS ADHESION
EX.No~ SUBSTRAI~ lST STAGE 2ND STAGE (~) RATING
.. .. ..
1 Polyester (biaxially oriented) 74/1 138/2 0.304 Excellent 2 Polypropylene (oriented) 74/1127/2 0.304 Excellent 3 Polyethy:Lene 74/193/2 0.304 Fair 4 Polyc~lrbonate 74/1121/2 0.304 Excellent Polyvinyl acetate 74/1 138/2 0.608 Excellent 6 Polystyrene 74/193/2 0.608 Excellent 7 Polyimide ("Kapton"
from DuPont) 74/1138/2 0.304 Excellent 8 Polyvinyl chloride 74/1 121/2 0.608 Excellent 9 Aluminum 74/1138/2 1.216 Excellent Copper^ 74/1138/2 1.216 Excellent 30 Il Plate glass 74/L~138/2 1.216 Excellent 12 ~ Ceramic tile 74/l138/2 0.304 Good .

~¢3~5~
- 14 ~

_ Trea-tment compositions were prepared using various aziridine-functional compounds and applied to biaxially oriented poly(ethylene terephthalate) film.
The aziridine employed and the adheslon results obtained are set out in Table 2.

___ MODIFIED
AZIRIDINB SURFACE ADHESION
EXAMPLE FORMULA THICKNESS(~) RATING

13 A 0.008 Excellent 14 A 0.015 Excellent A 0.031 Excellent 16 A 0.076 Bxcellent 17 A 0.13 Excellent 18 A 0.25 Excellent 19 A 0.5 Excellent A 1.216 Excellent 21 G 1.368 Excellent 22 F 0.076 Excellent Treatment compositions were prepared using various aziridine-functional compounds and applied to corona treated biaxially oriented poly(ethylene terephthalate). The aziridine used and the adhesion results obtained are set out in Iable 3.

:

.

MODIFIED
AZIRIDINE SURFACE ADHESION
EXAMPLE FORMULA THICKNESS(~) RATING
23 A 2.432 Exeellent 24 C 0.038 Excellent C 0.076 Excellent 26 C 0.152 Excellent 27 C 0.500 Excellent 10 28 Dl/D2 0.038 Excellent 29 Dl/D2 0.076 Excellent Dl/D2 0.152 Exeellent 31 Dl/D2 0.500 Exeellent 32 E 0.038 Excellent 15 33 E 0.076 Excellent 34 E 0.152 Exeellent F 0.136 Good 36 H 1.368 Good Treatment eompositions comprising "CX-100", water and various surfactants were prepared and applied to one surface of a poly(ethylene terephthalate) surface.
The treated surfaees were dried in an air circulating oven at 74C for 1 minute and 138C for 2 minutes. The functional oxide coating described in Example 1 was applied to the dried surface as described in Example 1 and tested ~or adhesion. The results obtained are given in Table 3.
:

. .

MODIFIED
SURFACTANT SURFACE AD~IESION
EX. AZIRIDINE ~ % TYPE THICKNESS(~) RATING
37 2.3 0.7 "Triton" X-200( ) 0~152 Excellent 38 2.3 0.7 "Triton" X-200 0.044 Excellent 39 2.3 0.7 "Triton" X-200 0.076 Excellent 2.7 0.3 "FC-170"(2) 1.216 Excellent 41 2.3 0.7 "FC-170" 0.916 Excellent 42 2.7 0.3 "FC-430"(`3) 1.216 Excellent 43 2.3 0.7 "FC-430" 0.916 Excellent 44 2.3 0.7 "Triton" X-100( 1.216 Excellent ~5 2.3 0.7 "Triton" X-100 0.916 Excellent (1) Sodium salt of alkaryl polyether sulfonate available from Rohm ~ Haas.
(2) E'luorochemical surfactant available from Minnesota Mining and Manufacturing Company.
(3) Fluorochemical surfactant available from Minnesota Mining and Manufacturing Company.
(4) Octyl phenoxy polyethoxy ethanol available from Rohm and Hass.
The treated surfaces were replicated and the replications were examined under a transmission electron microscope at 32,000X. It was found that the treated surfaces comprised a discontinuous surface having clusters of surface irregularities projecting up-ward Erom the surface. Surfaces treated with organic solvent solutions of aziridines did not possess the clusters of projecting sites but comprised relatively smooth surEaces.

A treatment composition containing aziridine of formula Bl/B2 (4~ by weight in water) was prepared. An unoriented cast poly(ethylene terephthalate) web * Trade~mark was oriented in the length direction at 90C by stretching it to 3.5 times its original length. The treatme~t composition was applied to one surface of the uniaxially oriented web, and the treated web then oriented in the width direction at 110C by strétching it -to 3.5 times its original width. The biaxially oriented film was then heat se-t at 230C The treated surface provided a layer that was 0.122~ thick.
A functional oxide coating of the formula described in Example 1 was applied to the treated surface and dried as in Example l. The functional coating had excellent adhesion to the substrate.

.
Treatment compositions comprising 8 weight percent "CX-100", 71.4 weight percent water, 1.6 weight percent l'Triton" X-100 and 19 weight percent lN HCl were prepared and applied to one surface of an unoriented poly(ethylene tereph-thalate) web and dried at 72C for three minutes. The treated web was then conditioned for l.S minutes at 93C and then biaxially oriented by stretching it 3.5 x 3.5 times at 110C. The oriented film was then heat set at 230~245C.
A gelatin composition comprising the following materials was then applied to the modified surface of the biaxially oriented and heat set film:

LOUI~UI PARTS BY WEIGHT
Lana Perl ~ed Dye 0.023 Gelatin 9.9 Water g2.0 "Triton" X-200 0.01 Formaldehyde (37% in water) 0.08 H2SO4 0.125 ¢~5~

- 18 ~
The gelatin was applied as a warm solution at a coating thickness of 75ll. The coating was dried for four hours at 20C and then tested for adhesion to the modified surface. The dried gelatin layer was scribed using a cross-hatch template and a thin.rnetal tip. A section of No. 610 tape (available from Minnesota Mining and Manufacturing Company) was applied to the scribed area, pressed down and quickly removed. The quantity of gelatin retained on the modified surface was then recorded.
I'he results are given in Table 5.

MODIFIED
SURFACE ~ GELATIN
EXAMPLE THICKNESS (~) RETAINED

47 0.182 100 48 0.364 100 49 0.486 100 0.36~ 60-80 51 0.0~6 0-20 These resul-ts show that even at aziridine-modified surface thicknesses of as ].ow as 0.046~, there is still adhesion of the gelatin to the surface.

Claims

1. A flat sheet-like article having a thin, aziridine-modified surface thereon, said surface comprising the product resulting from the interaction between said sheet and a treatment composition consisting essentially of an aziridine-containing compound, wherein said aziridine-containing compound is present in an amount sufficient to permit interaction between said sheet and said aziridine-containing compound, and said composition is essentially free of any other component that would prevent said interaction.

2. An article according to claim 1 further comprising at least 0.1 part by weight of an organic resin per part by weight of said aziridine-containing compound.

3. All article according to claim 1 or 2 wherein said flat surface is an inorganic material.

4. An article according to claim 3 wherein said inorganic material is selected from glass, metal and ceramic.

5. An article according to claim 1 or 2 wherein said flat surface is an organic material.

6. An article according to claim 5 wherein said organic material is selected from polyester, polymers prepared from ethylenically unsaturated monomers, polycarbonate, polyamide, polyimide, polydimethyl siloxane and cellulose acetate materials.

7. An article according to claim 1 or 2 wherein said aziridine-containing material has the formula wherein A1 is an n valent organic or inorganic group; R1, R2, R3 and R4 are independently selected from hydrogen and lower alkyl groups; and n is a whole number of at least 1.

8. An article according to claim 7 wherein A1 is an inorganic group.

9. An article according to claim 8 wherein A1 is selected from -P=O or -P=S.

10. An article according to claim 7 wherein A1 is an organic group.

11. An article according to claim 1 or 2 wherein said product is the result of chemical reaction between functional groups present at the surface of said article and said aziridine-containing material.

12. An article according to claim 1 or 2 wherein said product is the result of mechanical interlocking between fissures in said surface and said aziridine-containing material.

13. An article according to claim 1 or 2 wherein said product is the result of entrainment of said aziridine-containing material in said surface.

14. An article according to claim 1 or 2 wherein said article further comprises a functional layer on said modified surface.

15. A rigid sheet-like article according to claim 1 or 2.

16. A flexible sheet-like article according to claim 1 or 2.

17. A flat sheet-like article comprising a substrate having at least one essentially flat major surface and a functional material attached to said surface, wherein the interface between said surface and said functional material has been modified by interaction between said substrate and a composition consisting essentially of a compound containing at least one aziridine group, wherein said aziridine group has the formula wherein R1, R2, R3 and R4 are independently selected from hydrogen and lower alkyl groups.

18. An article according to claim 17 wherein said functional material comprises a magnetic recording medium.

19. A rigid article according to claim 18.

20. A flexible article according to claim 18.

21. An article according to claim 17 wherein said functional material comprises an adhesive.

22. An article according to claim 17 wherein said functional material comprises a silane.

23. An article according to claim 17 wherein said functional material comprises gelatin.

24. An article according to claim 17 wherein said functional material comprises a radiation sensitive composition.

25. A flat sheet-like article having at least one essentially flat major surface, a solvent resistant treatment layer on said major surface comprising the interaction product between said surface and a composition consisting essentially of a compound having at least one aziridine functionality, and a functional layer on said treatment layer.

26. An article according to claim 25 wherein said treatment layer is solvent insoluble.

27. An article according to claim 26 wherein said substrate is polyester.

28. An article according to claim 1 wherein said aziridine-modified surface comprises a solvent resistant layer on said substrate.

29. An article according to claim 28 wherein said solvent resistant layer is solvent insoluble.

30. A method of modifying the surface of a flat sheet-like article having at least one essentially flat surface comprising the steps of (a) preparing a composition consisting essentially of an aziridine-containing compound, (b) applying said composition to said essentially flat surface, (c) subjecting said article to a temperature and for a time sufficient to cause interaction between said flat surface and said aziridine-containing material to provide an aziridine-modified surface.

31. A method according to claim 30 comprising the further step of applying a layer of a functional material to said aziridine-modified surface.

32. A method according to claim 30 comprising the further step of at least uniaxially orienting said article.

33. A method of modifying the surface of a flat sheet-like article comprising the steps of (a) orienting said sheet-like article in a first direction, (b) applying a composition consisting essentially of a compound having at least one aziridine functionality to an essentially flat major surface of said article, (c) processing said surface at a temperature and for a time sufficient to permit interaction of said compound with said major surface, (d) orienting said sheet-like article in a second direction which is at an angle of 90° to said first direction.