CA1319776C - Process for the production of images - Google Patents

Abstract

3-16052/+/ARL 373 ABSTRACT
PROCESS FOR THE PRODUCTION OF IMAGES

A process for the production of an image on a substrate having an electrically conductive surface comprises (i) applying a radiation-polymerisable film to said surface by electrodeposition from a composition comprising a solution or dispersion in an electrodeposition medium of a solid radiation polymerisable resin having, per average molecule, more than one radiation-polymerisable ethylenically unsaturated group, a photoinitiating residue which initiates polymerisation of said polymerisable group on exposure to radiation and a salt-forming group which is present at least partially in ionised form, (ii) subjecting the film to radiation in a predetermined pattern, thereby polymerising exposed areas of the film, and (iii) removing areas of the film not exposed in stage (ii).
Typical radiation-polymerisable resins-are obtained by reacting an epoxide resin with a stoichiometric deficiency of 1-benzoylcyclohexanol, reacting the resulting product with methacrylic acid and reacting the product, through alcoholic hydroxyl groups thereof, with ethylenediaminetetracetic acid anhydride.

Description

~ 3 1 9 7 7 ~ 3-16052/+/ARL 373 PROCESS FûR THE_PRODUCTION OF IMAGES

This invention relates to a process for producing images and compositions suitable for use in this process.
Conventionally, images are produced on substrates by coating the substrate with a negative photoresist comprising a photopolymerisable material, irradiating the coating with actinic radiation through a negative, so that the parts of the coating struck by the radiation become photopolymerised and less soluble, whilst those parts shielded from the radiation remain substantially unaffected, then dissolving away the unirradiated, non-photo-polymerised parts of the coating by means of a suitable solvent that does not dissolve the photopolymerised parts. This last stage is known as development. Where the surface of the substrate coated with the photoresist is metallic, the surface exposed on development may be etched to form a printing plate or printed circuit. The photopolymerised coating may then be removed, either chemically by means of a solvent, or mechanically by means of brushes etc., or, more usually, by a combination of both methods.
Both liquid and dry film negative photoresists have been used in conventional image-forming processes. The liquid photoresists are usually solutions of film-forming photopolymerisable materials in organic solvents, which have to be evaporated in the formation of a photoresist film on a substrate. Apart from the environmental - - : - ~

. : , ~ .

- 2 - ~ 3~ ~ 7 7 6 problems associated with such use of organic solvents, it is difficult, using these liquid resists, to form uniform photoresist films which are free from pinholes. When used in the production of printed circuit boards with m~tal-plated through-holes or vias, blocking of the holes and poor coating of the edges of the holes are common problems. In order to avoid the disadvantages of liquid photoresists, dry film photoresists have been used. These, however, have poor adhesion to metal surfaces unless the metal is subjected to a special pretreatment,and cannot be used successfully on irregular surfaces. The use of dry film photoresists also entails cutting of the film to the dimensions of the surface to be coated, giving rise to a considerable amount of waste film.
The problems encountered in using conventional liquid and dry film photoresists can be avoided by electrodepositing a suitable photoresist on an electrically conductive surface.
European Patent Publication No. 0 176 356, for example, proposes the electrodeposition of a photoresist film from an aqueous solution or emulsion containing a mixture of a positively or negatively charged polymer, a multifunctional acrylate or methacrylate as photocrosslinking monomer and a photoinitiator. While use of an electrodeposition bath containing such a mixture can initially give satisfactory images, after a small number of electrodepositions have been carried out the electrodeposited film does not form a satisfactory image, even on exposure to radiation for considerably `

~3~776 longer than the initially deposited film. Furthermore, the electrodeposited films obtained from such a mixture tend to flow during heat-drying prior to imagewise exposure, giving rise to non-uni~orm photoresist films.
It has now been found that images suitable for use in printed circuits and printing plates can be formed with good reproducibility from photoresist films showing little tendency to flow on heating obtained by electrodeposition from an electrodeposition medium containing a film-forming resin having in the same molecule radiation-polymerisable groups, a photopolymerisation-initiating residue for those groups and a salt or salt-forming group.
Accordingly, the present invention provides a process for the production of an image on a substrate having an electrically conductive surface which comprises (i) applying a radiation-polymerisable film to said surface by electrodeposition from a composition comprising a solution or dispersion in an electrodeposition medium of a solid radiation polymerisable resin having,per average molecule, more than one radiation-polymerisable ethylenically unsaturated group, a photoinitiating residue which initiates polymerisation of said polymerisable group on exposure to radiation and a salt-forming group which is present at least.partially in ionised form, (ii) subjecting the film to radiation in a predetermined -.

.... - :
~ . ~
' -pattern, thereby polymerising exposed areas of the film, and (iii) removing areas of the film not exposed in stage (ii) .
The radiation-polymerisable groups in the resin are usually vinyl groups, preferably acrylic groups, including acrylate and alpha-substituted acrylate, for example, methacrylate groups and acrylamido and methacrylamido groups, with acrylate and methacrylate groups being particularly preferred. The photoinitiating residue may be in the backbone of the resin, in which case it is linked to the remainder of the resin molecule through at least two linkages.
For most classes of photoinitiating residue, the photoinitiating residue is preferably attached to the backbone of the resin, i.e.
it is connected to the remainder of the resin molecule through only one linkage. The radiation-polymerisable resin may contain one or many such photoinitiating residues.
Photoinitiating residues which initiate polymerisation of radiation-polymerisable groups are well known. For ethylenically unsaturated groups, suitable photoinitiating residues are those which produce free radicals either by photolytic dissociation or by a reaction, usually hydrogen transfer, with another molecule.
Thus suitable photoinitiating residues include benzophenone, ;~ ketocoumarin, benzil, anthraquinone, phenanthraquinone, alpha-substituted acetophenone, acylphosphine oxide, O-acylated alpha--. ~ . .
.

_ 5 _ 1319776 oximinoketone, xanthone or thioxanthone residues connected to the remainder of the resin molecule through one or more linkages. Amongst these, benzophenone, alpha-substituted acetophenone and thioxanthone residues are preferred. The benzophenone residues may be in the backbone of the resin, being linked to the remainder of the molecule through 2 tD 4 linkages, or attached to the backbone of the resin.
The substituted acetophenone and thioxanthone linkages are preferably attached to the backbone.
In preferred radiation-polyme~isable resins, the photoinit.iating residue is selected from (a) a benzophenone residue of one of the formulae -Ar1-CO-Ar2 IA

_Ar1_co-Ar1- IB

-Ar1-CO-Ar3 IC

_ Ar3_co-Ar3- ID

(b) an alpha-substituted acetophenone residue of one of the fDrmulae : :

- 6 _ 13tg77~

oR1 -Ar1-CO-C-Ar2 II

oR1 Ar2-CO-C-Ar oR1 Ar2-CO-~-Ar2 IV
R --Ar1-CO-C-R6 ' V

Ar2-CO_c_ VI
R

or ~: :
(c) a thioxanthone residue of formula :, ~ `

:
:
' ..... , : :
:

: ~ :

_ 7 _ 131977g ~ ~ VII

the photoinitiating residue being linked to the remainder of the resin molecule through the indicated free valency, where Ar denotes a phenylene group which may be substituted by 1 to 3 substituents R7, Ar2 denotes 2 phenyl group which may be substituted by 1 to 3 substituents R7, Ar3 denotes a benzene triyl group which may be substituted by 1 to 3 substituents R7, R1 denotes a hydrogen atom or a group -CH2R8, R2 denotes a hydrogen atom, -OCH2R8, or -CH20R8.
R3 denotes a C1 to C20 alkylene group, which may be interrupted by one or more oxygen atoms, RA and R5 each denote a hydrogen atom or a monovalent aliphatic, cycloaliphatic or araliphatic group or, together with the attached carbon atom, denote a cycloalkylene group, R6 denotes -OH, amino or an alkylated or silylated hydroxyl or amino group, R denotes a halogen atom, C1 to C20 alkyl, C1 to C20 haloalkyl, C1 to C20 alkoxy, C6 to C12 aryloxy, C2 to C20 acyloxy; C2 to C20 - , .

: : : . . .

. --31977~
alkoxycarbonyl, C7 to C13 aracyloxy, C2 to C40 dialkylamino, Cto C20 alkylthio, C6 to C12 arylthio or cyano, R8 denotes a hydrogen atom, -OH, C1 to C8 alkyl, C1 to C4 alkoxy, C2 or C3 alkenyl, C7 to Cg aralkyl, C8 or Cg aralkenyl or (CH2 )aR
R9 denotes halogen, -OH, C1 to C4 alkoxy, C1 to C4 alkylthio, phenoxy, phenylthio, C2 to C8 acyloxy, C7 to C12 aracyloxy or C2 to C8 alkoxycarbonyl, and a denotes 1, 2 or 3.

The term "alkylated amino group" as used in the definition of R includes groups in which one or both hydrogen atoms of the amino group are replaced by an optionally substituted alkyl group and groups in which both hydrogen atoms are replaccd by an alkylene group, which may contain an oxygen or nitrogerl atom in the chain thereof, forming a heterocyclic ring together .with the nitrogen aLom of the amirlo group.
In formulae IA to VI, Ar preferably denotes a phenylene group wnich is urwubstituted or substituted by one group R7,.especially an unsubstituted phenylene group, Ar preferably denotes a phenyl group which is unsubstituted or substituted by one group R7, especially an unsubstituted phenyl group, Ar preferably denotes a benzenetriyl group which is : unsubstituted or substituted by one group R7, especially an unsubstituted benzene triyl group, : R preferab.ly denotes a hydrogen atom or a group -CH2R8.
R2 preferably denotes a hydrogen atom, -OCH2R8 or -CH20R8, ~` ~ R3 preferab.ly denotes a C1 to C10 alkylene group,especially ~: ; a methylene, ethylene or 1,2-propylene group, : ~

~ ~ :

~ - , :: -- , : - :
~, : ., : ~ : : ' -::
: :, : : :

_ 9 _ R4 and R5 preferably each denote a hydrogen atom, a C1to C8 alkyl group or, together with the attached carbon atom, denote a cyclohexylene group, especially a methyl or ethyl group or, together with the attached carbon atom, a cyclohexylene group, R6 preferably denotes a group of formula -N(R10)R11, where R10 and R11, which may be the same or different, each denote a C1 to C4 alkyl group, which may be substituted by a hydroxyl group, or R1U and R11, together with the nitrogen atom to which they are attached, denote a heterocyclic ring containing 4 to 5 carbon atoms, and,optionally, one oxygen atom or further nitrogen atom in the ring, R6 especially denoting a N,N-di(hydroxyethyl)amino group, a N-piperidinogroup or a N-morpholino group, R7 preferably denotes a halogen atom, C1 to C10 alkyl, Cz to C8 dialkylamino, C1 to C4 alkoxy or C1 to C4 alkylthio, especially a chlorine or bromine atom, or a methyl, isopropyl, tert.butyl, methoxy or methylthio group, R8 pre~erably denotes a hydrogen atom, -OH, C1 to C4 alkyl, C1 to C4 alkoxy or -(CH2)aR9, especially a hydrogen atom, -OH or methoxy, R9 preferably denotes -OH, C1 to C4 alkoxy or C1 to C4 alkylthio, especially methoxy or methylthio, and a preferably denotes 1 or 2, especially 1.
The residues of formulae I to VII may be linked to the remainder of the resin molecule through any linking group derived . ~ ,.. ~
,:
, ~ ' .
., ~:

1 o - i 3 1 ~ 7 ~ 6 from a reactive group attached to said residue. Thus suitable linking groups include those of Formulae -O-, -OCO-, -OSO~ , -OCH2-, -OCH2CH(OH)CH2-, -OCONH-, -O(CH2-CR12)bO_, -O(CH2-CR12)bOCO-, -O(CH2-CR12)bO502-, -O(CH2-CR12)bOCH2-, -O(CH2-CR 2)bOCONH-, -COO-, -COS-, -COOCH2CH(OH)CH2-, -CONH-, -SO20-, -SO25-, -CH2-, -CH20-, -CH25-, -NHCOO-, -NHCO-, -NHCOS-, -P(=o)(oR13)O-, P(=o)(oR13)ocH2cH(oH)cH2-~ -SCH2CH(OH)CH2-, -SCONH-9 -SCO-, -SS02-, -SCH2-, -S(CH2CR12)bO-, -S(CH2CR12)bOCO-, -S(CH2CR12)bOS02-, -S(CH2CR12)bOCH2-, or -S(CH2CR12)bOCONH-, the left hand free valency of each group corresponding to the indicated free valency in formulae I to VII, where R12 denotes -H or -CH3, R13 denotes C1 to C4 alkyl and b denotes 1 to 4. Preferred among the above linking groups are -O-, -OCO-, -OCH2CH(OH)CH2-, -COO-, -COOCtl2CH(OH)CH2-, -P(=O)(OCH2CH3)0-, -P(=O)(OCH2CH3)0CH2CH(OH)CH2-~rld -SCH2CH20CO-In one especially preferred class of radiation-polymerisable resin, the photoinitiating residue is of Formula ID where Ar3 denotes an unsubstituted benzene triyl group. In a second especially preferred class, the photoinitiating residue is of formula IV where R1 denotes a hydrogen atom and R3 denotes a methylene group. In another especially preferred class of radiation-polymerisable resin, the photoinitiating residue is of formula V where R4 and R5 each denote a methyl group and R6 denotes a N-morpholino group. In a further especially preferred class of radiation-polymerisable resin, the photoinitiating residue is of formula VI where R4 and R5, together . - , .
~: ' , ' .- ' ~ ' ' , : .
. .

11 13~776 with the carbon atom to which they are attached, denote a cyclohexylene group.
The salt-forming group in the radiation-polymerisable resin may be an acidic group such as a carboxyl or sulphonic acid group or a basic group such as a secondary or tertiary amino group or a quaternary ammonium group.
Suitable resins having ethylenically unsaturated radiation-polymerisable groups, a photoinitating residue and a salt-forming group as hereinbefore described are reaction products of (A) a substance having at least one said radiation-polymerisable group and at least one reactive functional group X with (B) a compound having said photoinitiating residue and at least one group Y which is reactive with the group X, or products of reaction of ~he rracLion product of (A) and (B) with at least one further substance (C) to increase the molecular weight thereoF, the salt-Porming group being present in (A), (B) or (C) or being introduced into the reaction product of (A) and (B) or the reaction product thereof with (C). The reactants (A) and (B), their proportions and the reaction conditions can be chosen to give reaction products which are solid, film-forming resins or as indicated, the reaction product of (A) and (B) can be reacted with at least one other substance to increase the molecular weight thereof, thereby converting a liquid reaction product of (A) and (B) into a solid, film-forming resin. Thus, for example, where Lhe reaction product of (A) and (B) contains, on average, more than one primary or secondary hydroxyl group per molecule, it can be , :: :
: , , ;: '~ ,' -'' . ' :
.

`, . . ~ . . .
- . .
.

- `~

- 12 - ~3~ 9776 subjected to a polycondensation reaction with a substance having at least 2 acyl halide groups or a polyaddition reaction with a substance having at least 2 isocyanate groups or carboxylic acid anhydride groups. The further reaction to increase the molecular weight can bea reaction which introduces a salt-forming group, as illustrated by the hydroxyl-anhydride reaction described above, which results in formation of carboxyl groups. This further reaction can also be used to form resins having two or more radiation polymerisable groups from reaction products of (A) and (B) having only one such group by, in effect, linking two or more molecules of the reaction product of (A) and (B) together.
Where (A) has more than one group X and (B) has more than one group Y, for example where (A) is a diepoxide and (B) is a dihydric phenol, the reaction product can be a resin having the photoinitiating residue in the backbone thereof. As described above, for most classes of photoinitiating residue preferred radiation-polymerisable resins are those having the photoinitiating residue attached to the backbone therecf, such resins being reaction products of (A) and (B) formed by reaction of one group X with one group Y, optionally further reacted with another substance (C) as hereinbefore described.
Suitable combinations of reactive groups X and Y wilI be apparent to those skilled in the art of making radiation-polymerisable Fesins. Thus suitable reactants (A) and (B) include those where :

.. , . .. : - .
.

,, , -- 13 - ~3~ 9776 X denotes a hydroxyl group and Y denotes a carboxyl, esterified carboxyl, halocarbonyl, anhydride, sulphonic or phosphonic acid, halosulphonyl, halophosphonyl, halomethyl, epoxide or isocyanate group, or X denotes a carboxyl or phosphonic acid group and Y
denotes a hydroxyl, mercapto, epoxide, secondary amino or isocyanate group, or X denotes a halocarbonyl, halosulphonyl, halomethyl, esterified carboxyl, or anhydride group and Y denotes a hydroxyl, mercapto, secondary amino or epoxide group, or X denotes an epoxide group and Y denotes a hydroxyl, carboxyl, anhydride, phosphonic acid, secondary amino or mercapto group, or X denotes an isocyanate group and Y denotes a hydroxyl, carboxyl, mercapto, halomethyl or secondary amino group, or X denotes a secondary amino group and Y denotes a halo-carbonyl, halosulphonyl, carboxyl, esterified carboxyl, anhydride, halomethyl or isocyanate group, or X denotes a mercapto group and Y denotes an epoxide, isocyanate, carboxyl, esterified carboxyl, halocarbonyl, halosulphonyl, halomethyl or anhydride group.
Preferred reaction products of (A) and (B) are those in which (A) is a substance having at least one radiation-polymerisable ethylenically unsaturated group and (B) is a compound having a benzophenone, alpha-substituted acetophenone or thioxanthone photoinitiating residue, one of (A) and (B) having an epoxide group and the other having a hydroxyl, carboxyl, carboxylic acid anhydride , : : . :

.
: ~, . , ' :
- . . , 1319~7~

or phosphonic acid group. These preferred reaction pro~d~cts of (A) and (B), which contain secondary alcoholic hydroxyl groups, can be further reacted with (c) a dianhydride of a polycarboxylic acid to increase the molecular weight thereof and/or to introduce a salt-forming group or with a diisocyanate to increase the molecular weight thereof. Where the reaction products of (A) and (B) are already of sufficient molecular weight, they can be subjected to other reactions, for example reaction with a monoanhydride of a polycarboxylic acid, to introduce a salt-forming group where neither (A) nor (B) contains such a group or where it is desired to introduce a further salt-forming group.
Accordingly the present invention also provides a solid radiation-polymerisable resin suitable for use in the process of the invention which is a reaction product of (A) a substance having at least one radiation-polymerisable ethylenically unsaturated group and (B) a compound having a benzophenone, alpha-substituted acetophenone or thioxanthone photoinitiating residue, one of (A) and (B) having an epoxide group and the other having a hydroxyl7 carboxyl or phosphonic acid group, said reaction product optionally - being modified to increase the molecular weight thereof by reaction with at least one further substance (C) and said reaction product having a salt-forming group derived from (A), (B) or (C) or having a salt-forming group introduced therein by further reaction thereof.

.

:
':

: , ~
, ' ` " : . ', ' ' : ~

- 15 _ ~31977~

In one preferred class of reaction products of (A) and (B), (A) is (A1) a substance having at least one radiation-polymerisable ethylenically unsaturated group and at least one hydroxyl, carboxyl or phosphonic acid group and (8) is (B1) a compound having a benzophenone, alpha-substituted acetophenone or thioxanthone photoinitiating residue and at least one epoxide group. Suitable compounds (B1) for such reaction products include glycidyl ethers and glycidyl esters prepared by conventional glycidylation of compounds containing said photoinitiating residue and a hydroxyl, carboxyl or phosphonic acid group respectively. Preferred compounds (B1) for such reaction products are reaction products of an epoxide resin, that is a material having, on average, more than one epoxide group per molecule, with less than the stoichiometric amount of a compound having said photoinitiating residue and at least one hydroxyl group, carboxyl or phosphonic acid group. More preferred compounds (B1) for such reaction products are reaction products of an epoxide resin with less than a stoichiometric amount of a benzophenone of one of the formulae y1_Ar1_co-Ar2 VIII A

y1_Ar1_cO-Ar1-y1 VIII B

~ Ar3 CO Ar3 VIII C
y1 y1 ' ' ' :

131977~

or an alpha-substituted acetophenone of one of the formulae Ar2-CO-C-OH IX

Y -Ar1-CO_c_R6 X

oR1 Ar2-CO-C-Ar2 R3-Y3 Xl or a thioxanthone of formula o ~ y4 Xll where Ar1, Ar2, Ar3, R1, R3, R4, R5 and R6 are as hereinbefore defined, y1 denotes -OH or -COOH, y2 denotes y1 or -SCH2CH20H, Y3 denote y1 or -P(=O)(OCH2CH3)0H, ~ .
:

!

Y4 denotes y1 or -oCH2CH(oH)CH2N(R14)R15, and R14 and R15, which may be the same or different, each denote a C1 to C20 alkyl group, which may be substituted by a hydroxyl group, or R14 and R15, together with the nitrogen atom to which they are attached, denote a heterocyclic ring containing 3 to 5 carbon atoms and, optionally, one oxygen atom or sulphur atom or one further nitrogen atom in the ring.
Examples of suitable compounds of formulae VIIIA to XII
are compounds of formula VIIIA where Ar1 denotes an unsubstituted phenylene group, y1 denotes a hydroxyl or carboxyl group which is in a position ortho, meta or para to the indicated carbonyl group and Ar2 denotes an unsubstituted phenyl group; compounds of formula VIIIC where Ar denotes an unsubstituted benzentriyl group and each y1 denotes a carboxylic acid group; compounds of formula IX where Ar2 denotes an unsubstituted or 4-isopropyl-or 4-tert.butyl substituted phenyl group and R4 and R5 each denote a hydrogen atom, a C1 to C8 alkyl group or, together with the attached carbon atom, denote a cyclohexylene group; compounds of formula X where Ar1 denotes an unsubstituted phenylene group, y2 denotes a group of formula -SCH2CH20H, R4 and R5 each denote a C1 to C8 alkyl group or~ together with the attached carbon atom, denote a cyclohexylene group, and R6 denotes a group of formula -N(R10)R11 where R10 and R11 are as hereinbefore defined; compounds of formyla Xl where Ar~ denotes an unsubstitutsd phsnyl group, : :

' : ~

~197~6 R1 denotes a hydrogen atom or a group -CH2R8 where R8 is as hereinbefore defined, R3 denotes a C1 to C10 alkylene group and Y3 denotes a hydroxyl or carboxyl group or a group of formula -P(=O)(OCH2CH3)0H; and compounds of formula XII where Y4 denotes a hydroxyl or carboxyl group or a group of formula -oCH2CH(oH)CH2N(R16)R17 where R16 and R17, which may be the same or different, denote a C1 to C8 alkyl group which may be substituted by a hydroxyl group, any of said groups being in the 1-, 2-, 3- or 4-position on the thioxanthone ring.
Preferred compounds of formulae VIIIA to XII are compounds of formula VIIIA where Ar1 denotes an unsubstituted phenylene group, y1 denotes a hydroxyl or carboxyl group in the ortho position to the indicated carbonyl group and Ar2 denotes an unsubstituted phenyl group; compounds of formula VIIIC where Ar3 denotes an unsubstituted benzenetriyl group and the groups y1 denote carboxyl groups in the para and meta positions to the indicated carbonyl group; compounds of formula IX where Ar2 denotes an unsubstituted phenyl group and R4 and R5 each denote a methyl or ethyl group or, together with the attached carbon atom, denote a cyclohexylene group, compounds of formula X where Ar1 denotes an unsubstituted phenylene group, y2 denotes a group of formula -SCH2CH20H, R4 and R each denote a methyl or ethyl group or, together with the attached carbon atom, denote a cyclohexylene group, and R6 denotes -13~ 9776 a N,N-di(hydroxyethyl)amino, a N-piperidyl or a N-morpholino group;
compounds of formula XI where Ar2 denotes an unsubstituted phenyl group, R1 denotes a methyl group, R3 denotes -CH2CH2- or -CH2CH(CH3)-and Y3 denotes a carboxyl group or a group of formula -P(_Oj(OCH2CH3)oH;
and compounds of formula XII where Y4 denotes a hydroxyl or carboxyl group or a group of formula -OCH2CH(OH)CH2N(CH3)2 in the 2-position on the thioxanthone ring.
Especially preferred compounds of formulae VIIIA to XII
are o-benzoylbenzoic acid , alpha-methylolbenzoin, i.e. a compound of formula XI where Ar2 denotes an unsubstituted phenyl group, R1 denotes a hydrogen atom, R3 denotes a methylene group and Y3 denotes a hydroxyl group; alpha,alpha-d1methyl-alpha-N-morpholino-p-(2-hydroxyethylthio)acetophenone, i.e. a compound of formula X
where Ar1 denotes an unsubstituted phenylene group, y2 denotes a group of formula -SCH2CH20H, R4 and R5 each denote a methyl group and R6 denotes a N-morpholino group; and 1-benzoylcyclohexanol, i.e.
a compound of formula IX where Ar2 denotes an unsubstituted phenyl group and R4 and R5, together with the attached carbon atom, denote a cyclohexylene group.
Compounds of formulae VIIIA to XII are either commercially available or may be prepared by conventional reactions from commercially available starting materials. For example, many of th~ benzophencnes oF iormulae VIIIA to VIIIC are commeFcially available, while those that are not can be prepared by methods conventional for hydroxyl- and carboxyl-substituted aromatic compounds.
Compounds of formula IX where R4 and R5 are each methyl and Ar is phenyl, 4-isopropylphenyl or 4-tert.butylphenyl are available commercially, as also is 1-benzoylcyclohexanol. Other compounds of formula IX and compounds of formula X can be prepared by bromination of an alpha-substituted acetophenone of formula Ar-CO-CH(R4)R5, where Ar- denotes Ar2- or Y2-Ar1-, and Ar1,Ar2,R4,R5 and y2 are as hereinbefore defined, to give Ar-CO-CBr(R4)R5, followed by reaction with sodium methoxide to form an oxirane, and then opening the oxirane ring by reaction either with an acid (compounds of formula IX and of formula X where R6 denotes a hydroxyl or silylated hydroxyl group) or with an amine (compounds of formula X where R6 denotes an amino group, optionally alkylated or silylated).
Compounds of formula XI can be prepared from a benzoin alkyl ether of formula Ar2-CO-CH(OR1)-Ar2, where Ar2 and R1 are as hereinbefore defined, by reaction with formaldehyde or glyoxylic acid, or by a Michael addition reaction with a compound of formula R18Ya, where R18 denotes a C2 to C20 alkenyl group, optionally interrupted by oxygen, and ya denotes a group Y3 or a precursor group thereof such as an esterified hydroxyl or carboxyl group.
Compounds of formula XII where Y4 denotes a hydroxyl group in the 2-, 3-, or 4-position are commercially available and may ., ~ . :-. :

- 21 - i3~ 9~76 be used for the preparation of compounds where Y4 denotes -CH2CH(oH)CH2N(R14)R15 by glycidylation of the hydroxyl group followed by reaction of the glycidyl group with an amine of formula HN(R14)R15.
In this preferred class of reaction products of (A) and (B), the ethylenically unsaturated group in (A1) is preferably a vinyl group, particularly an acrylic group such as an acrylate, methacrylate, acrylamido or methacrylamido group. Preferred substances (A1) are acrylic acid, methacrylic acid and adducts of a hydroxyalkyl ester of acrylic or methacrylic acid, such as 2-hydroxyethyl acrylate or 2-hydroxypropyl acrylate, with a polycarboxylic acid anhydride such as succinic, glutaric, maleic, hexahydrophthalic or phthalic anhydride. Particularly preferred substances (A1) are acrylic and methacrylic acids.
In another preferred class of reaction products of (A) and (B), (A) is (A2) a substance having at least one radiation-polymerisable ethylenically unsaturated group and at least one epoxide group and (B) is (B2) a compound having a benzophenone, alpha-substituted acetophenone or thioxanthone photoinitiating residue and at least one hydroxyl? carboxylic acid anhydride, carboxyl or phosphonic acid group, preferably a compound of formula YIIIA, VIIIB, VIIIC, IX, X, XI, or XII as hereinbefore defined. SUitA le, prsferred and especially preferred compo~nds ' :.. ,.. .. : . . .
' ' ~ `,~ ' '' ., , - .

- . :

- 22 _ 13~ ~7 ~ ~

of formulae VIIIA to XII are as hereinbefore described. In this preferred class, (A2) is suitably a reaction product of an epoxide resin with a stoichiometric deficiency of a compound having said unsaturated group and at least one hydroxyl or carboxyl group. The unsaturated group is preferably a vinyl group, particularly an acrylic group. Preferred substances (A2) are reaction products of an epoxide resin with a stoichiometric deficiency of acrylic or methacrylic acid or an adduct of a hydroxyalkyl ester oF acrylic or methacrylic acid, such as one of those mentioned above, with a polycarboxylic acid anhydride such as one of those mentioned above.
Amongst these preferred substances, reaction products of an epoxide resin with acrylic or methacrylic acid are particularly preferred.
It will be apparent that preferred reaction products of both the preferred classes hereinbefore described can be prepared by reacting (P) an epoxide resin with, in either order or simultaneously, (Q) acrylic or methacrylic acid or an adduct of a hydroxyalkyl ester thereof with a polycarboxylic acid anhydride and (R) a compound of formula VIIIA, VIIIB, VIIIC, IX, X, XI or XII as hereinbefore defined. The reactions can be carried out using conventional procedures for epoxide-carboxylic acid or epoxide hydroxyl reactions; these usually involve heating the reactants in the presence of a tertiary amine or salt thereof, or a quaternary mmmonium salt, as cmtalyst.

. . :
, ':

- 23 - 131~77~

Epoxide resins suitable for use as a starting material for the preparation of the radiation-polymerisable resin include polyglycidyl ethers of polyhydric alcohols such as 1,3-propanediol, 1,4-butanediol and polyoxyethylene and polyoxypropylene diols and triols; polyglycidyl ethers of polyhydric phenols such as bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane and halogen-substituted derivatives thereof, and phenolic novolak resins derived from a phenol, particularly phenol itself, and an aldehyde, particularly formaldehyde; poly(N-glycidyl) derivatives, including those of aromatic amines, such as aniline and bis(4-aminophenyl) methane, isocyanuric acid and hydantoins such as 5,5-dimethylhydantoin, polyglycidyl esters of polycarboxylic acids, including aliphatic acids such as succinic, adipic and maleic acids, cycloaliphatic acids such as tetrahydrophthalic acid and aromatic acids such as phthalic acid; and cycloaliphatic epoxide resins such as vinyl-cyclohexene dioxide, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane-carboxylate and ethylene glycol bis(3,4-epoxycyclohexanecarboxylate).
Preferred epoxide resins are diglycidyl ethers of bisphenols, particularly 2,2-bis(4-hydroxyphenyl)propane, and advanced resins prepared by reacting such diglycidyl ethers with a bisphenol, particularly 2,2-bis(4-hydroxyphenyl)propane, or with a hydantoin, particularly 5,5-dimethylhydantoin.
Where the two preferred classes of reaction products of (A) and (P) hereinbefore described are solid, for example where ' ' ~ 24 - 131~77~

they are derived from advanced epoxide resins, they need not be reacted further to increase their molecular weight. Where they are liquid, they are reacted further, via their secondary alcoholic hydroxyl groups, with (C) a diisocyanate, a compound having two acyl halide groups or, preferably, a dianhydride of a polycarboxylic acid, to form solid resins. Suitable dianhydrides include those of pyromellitic acid, benzophenone-3,3',4,4'-tetracarboxylic acid, cyclopentane-1,2,4,5-tetracarboxylic acid and, preferably, ethylenediaminetetracetic acid. Ethylene-diaminetetracetic acid dianhydride is preferred because it gives resins having both amino and carboxyl salt-forming groups which can be neutralised with an acid or base respectively to give cationic or anionic electrodepositable resins respectively.
A third preferred class of reaction products of (A) and (B) is that where (A) is (A3) glycidyl acrylate or glycidyl methacrylate and (B) is (B3) a carboxyl-containing resin prepared by reacting an epoxy resin with a compound of formula VIIIA, VIIIB, VIIIC, IX, X, XI or XII and reacting the resulting product, through secondary alcoholic hydroxyl groups thereof, with a dianhydride of a polycarboxylic acid. Suitable and preferred epoxy resins, and suitable, preferred and especially preferred compounds of formula VIIIA to XII are as hereinbefore described.
The dianhydride may be of any of those mentioned above, with that of ethylenediaminetetracetic acid again being preferred, (B3) ::

... .

~': :

^~ `\

- 25 - ~- 31 ~ 7 76 thereby containing salt-forming groups which can be neutralised with acids and bases.
Other preferred reactions products of (A) and (B) are those in which (A) is (A4) a substance having at least one radiation-polymerisable ethylenically unsaturated group and a halocarbonyl, isocyanate or N-methylol group and (B) is (B4) a resin having a benzophenone, alpha-substituted acetophenone or thioxanthone photoinitiating residue and, on average, more than one hydroxyl group per molecule. The unsaturated group in (A4) is preferably a vinyl group, particularly an acrylic group. Suitable substances (A4) are the acid chlorides, isocyanatoalkyl esters and N-methylol amides of acrylic and methacrylic acid and of carboxyl-containing adducts of a hydroxyalkyl ester of acrylic or methacrylic acid with a polycarboxylic acid anhydride, for example those adducts hereinbefore described. Preferred substances (A4) include acryloyl chloride, methacryloyl chloride, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, N-methylolacrylamide and N-methylolmethacrylamide. Especially preferred substances (A4) are 2-isocyanatoethyl acrylate and 2-isocyanatoethyl methacrylate.
Suitable resins for use as (B4) are reaction products of an epoxide resin with a compound of formula VIIIA, VIIIB, VIIIC, IX, X, XI
or XII as hereinbefore defined. Suitable, preferred and especially preferred compounds of formulae VIIIA to XII, and suitable and ' ~--- 26 - ~319776 preferred epoxide resins, are as hereinbefore described. The secondary hydroxyl groups produced by reaction of the epoxide groups with the reactive groups in compounds of formulae VIIIA
to XII, and any hydroxyl groups present in the starting epoxide resin where, for example, it is an advanced epoxy resin, react with the halocarbonyl, isocyanate or N-methylol groups in (A4) under conventional conditions. Where the epoxide resin is reacted with a stoichiometric deficiency of the compound of formula VIIIA
to XII, remaining epoxide groups can be reacted with a secondary amine such as diethanolamine or with a suitable amino acid, either before or after the reaction with (A4), so that either (B4) or the reaction product of (A4) and (B4) has a salt-forming group introduced therein.
Further preferred reaction products of (A) and (B) are those where (A) is (A5) a substance having at least one radiation polymerisable unsaturated group and, on average, more than one hydroxyl group per molecule and (B) is (B5) a benzophenone tetracarboxylic acid dianhydride or a mixture thereof with another anhydride. The reaction between (A5) and (B5) is carried out under conventional conditions, preferably tD give a product of such molecular weight that it is solid, although liquid products can be reacted with an epoxide resin to form a solid resin. In (A5), the unsaturated group is preferably a vinyl group, particularly an acrylic group. Suitable substances (A5) are reaction products ::
.

~ :

- - , .: ~ .
" ~ , :
'; ' ~ ' ' - 27 - ~ 31 9 ~ 7 6 of an epoxide resin with a stoichiometric amount of acrylic or methacrylic acid, or a carboxyl-containirlg adduct of a hydroxyalkyl ester of acrylic or methacrylic acid with a polycarboxylic acid anhydride, for example the adducts hereinbefore described. Suitable and preferred epoxide resins are as hereinbefore described.
Preferred substances (A5) are reaction products of diglycidyl ethers of dihydric alcohols or phenols, especially a diglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane or an advancement reaction product thereof with 2,2-bis(4-hydroxyphenyl)propane, with acrylic or methacrylic acid. The dianhydride (B5) is preferably benzophenone 3,4,3',4'-tetracarboxylic acid dianhydride or a mixture thereof with another dianhydride such as pyromellitic dianhydride. An especially preferred dianhydride is a mixture of benzophenone 3,4,3',4'-tetracarboxylic acid dianhydride and ethylenediamine-tetracetic dianhydride, so that the reaction product of (A5) and (B5) contains salt-forming groups which can be-neutralised by acids and bases.
Yet further preferred reactions products of (A) and (B) are those where (A) is (A6) a substance having at least one radiation-polymerisable unsaturated group snd one hydroxyl group and (B) is (B6) a benzophenone tetracarboxylic acid dianhydride or a mixture thereof with another dianhydride, the reaction product of (A6) and (B6) being further reacted with an epoxy resin to increase the molecular weight thereof. In (A6), the - 2B - 1~19776 unsaturated group is preferably a vinyl group, particularly an acrylic group. Suitable substances (A6) are hydroxyalkyl esters of acrylic or methacrylic acid or a carboxyl-containing adduct of a hydroxyalkyl acrylate or methacrylate with a polycarboxylic acid anhydride, for example the adducts hereinbefore described.
Preferred substances (A6) are 2-hydroxyethyl and 2-hydroxypropyl esters of acrylic and methacrylic acid, with 2-hydroxyethyl methacrylate being especially preferred. The dianhydride (B6) is preferably benzophenone 3,4,3',4'-tetracarboxylic acid dianhydride. Suitable and preferred epoxide resins for reaction with the reaction product of (A6) and (B6) are as hereinbefore described. The reaction with the epoxide resin may be carried out to give an epoxy-terminated product, so that at least some of the epoxy groups can then be reacted with a secondary amine such as diethanolamine or an amino acid such as 3- or 4-dimethyl-aminobenzoic acid to introduce a salt-forming group.
Where the preferred classes of reaction products (A), (B) and, optionally, (C) contain salt-forming groups derived from (A), (B) or (C~, they need not be subjected to further reaction to introduce a salt-forming group. Otherwise, where, as in most cases, they contain a hydroxyl group, they can be rèacted with a carboxylic acid anhydride such as succinic, glutaric, tetrahydro-phthalic, hexahydrophthalic, maieic, or phthalic anhydride to introduce ~ carboxyl g~oup. ~Ihere they col~tairl residuE1 epoxy groups, they can be reacted with a secondary amine ': . - -~ .
.-: .
- .. .
- . ~
.
:
. . .
~ ' ' ' ~ ' ' - 29 - ~ 31 9 ~7 6 such as diethanolamine, diisopropanolamine; diethylamine, di-n-butylamine, piperidine, or morpholine to in~roduce a tertiary amino group. Other reactions which can be used to introduce a salt-forming group include a Michael addition reaction of part of the unsaturated group content with a secondary amine,such a9 those specified above for reaction with residual epoxy groups.

The radiation-polymerisable resin containing the salt-forming group may be neutralised, at least partially, before dissolution or dispersion in the electrodeposition medium to canvert the salt-forming group, at least partially,into ionised form. Preferably, however, this neutralisation is effected by the addition of a suitable acid or base to the electrodeposition medium in which the resin containing the salt-forming group is ~dissolved or dispersed.
Where the radiation-polymerisable resin contains a basic salt-forming group, electrodeposition in step (i) is preferably effected from a solution or dispersion thereof in an aqueous medium together with an acid which at least partially neutralises the basic group. Where the radiation-polymerisable resin contains an acidic salt-forming group, electrodeposition in step (i) is preferably effected from a solution or dispersion thereof in an aqueous medium together with a base which at least partially neutralises the acidic group. When the radiation-polymerisable resin contains~both acidic and basic groups, electrodeposition in ; stage (i) can be effected from a solutiwl or dispersion thereof .

, .

~ . ' .

~3~7~6 in an aqueous medium together with an acid or base. For the preferred radiation-polymerisable resins hereinbefore described which are derived from the dianhydride of ethylenediaminetetracetic acid, neutralisation with an acid is preferred. The aqueous rnedium may contain a water-miscible organic solvent to assist dissolution or dispersion of the radiation-polymerisable resin.
Suitable arganic solvents include ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, alcohols such as ethanol, 2-methoxyethanol, 2-ethoxyethanol, 2-n-butoxyethanol, diethylene glycol monobutyl ether, and esters such as 2-methoxypropyl acetate and 2-ethoxyethyl acetate.
The electrodeposition medium generally contains from 2 to 60nO by weight of the radia~ion-po.lymer.~isab1e r.~esin, preferably From 5 to 20a by weight.
Accordingly, the present invention also provides a composition suitable for carrying out the process of the invention as hereinbefore described, which composition comprises a solution or dispersion in an aqueous solvent of a radiation-polymerisable resin having a salt-forming group as hereinbefore described and an acid or base which at least partially neutralises the salt-forming group. Conventional additives such as dyes, pigments, fillers, plasticizers and surfactants can be included in t`lC
composition.

Suitable acids for effecting neutralisation are organic and inorganic acids such as acetic, lactic, trichloroacetic, methane~ulphonic, glycolic, p-toluenesulphonic, hydrochloric and , - . .

~ ~ . . ..

- :
.

- 31 - 131977~

sulphuric acids. Suitable bases for effecting neutralisation are organic and inorganic bases such as triethylamine, triethanolamine, pyridine, morpholine, sodium or potassium hydroxide, sodium or potassium carbonate or sodium or potassiu~ ethoxide.
Electrodeposition of the radiation-polymerisable resin may be carried out using conventional electrodeposition procedures for resinous materials. Voltages up to 200 volts for periods of up to 5 minutes are generally used, but the precise conditions for particular radiation-polymerisable resins, substrates and desired thicknesses may be readily determined by those skilled in the art of electrodepositing resinous materials.
The substrate on which the radiation-polymerisable resin is deposited may be of an electrically conductive plastics material, for example a thermoset resin containing electrically conductive particles distributed therein or, preferably, it is of a metal such as copper or aluminium, either as a solid metal sheet or as a metal-clad laminate which may have metal-lined through-holes or vias.
Subjection of the electrodeposited film to radiation in a predetermined pattern may be achieved by exposure through an image-bearing transparency consisting of substantially opaque and substantially transparent areas, or by means of a computer-controlled laser beam. Electromagnetic radiation having a wavelength of 200-600 nm is generally used, and suitable sources include carbon arcs, mercury vapour arcs, fluorescent lamps with phosphors emitting ultra violet .
- :~ '.' ' ,, - ' , :
,' ~
: -' ' ' - - ' , ' ' : ~
~:

light, argon and xenon glow lamps, tungsten lamps, and photographic flood lamps; of these, mercury vapour arcs and metal halide lamps are the most suitable. The exposure time required depends on such factors as the nature of the radiation-polymerisable resin, the thickness of the electrodeposited film, the type of radiation source, and its distance from the film. Suitable exposure times can readily be found by routine experimentation.
After irradiation, areas of the film not exposed to the irradiation are removed, preferably by treating the film with an aqueous or organic solvent or a mixture thereof as developer, leaving the exposed, polymerised areas. Suitable aqueous solvents include aqueous bases such as aqueous sodium or potassium hydroxide or carbonate or disodium hydrogen phosphate solutions for use with acid group-containing radiation-polymerisable resins and aqueous acids such as aqueous acetic, lactic, glycolic or p-toluenesulphonic acid for use with basic group-contain ng radiation-polymerisable resins. Suitable organic solvents include ketones such as acetone,:
methyl ethyl ketone and cyclohexanone, alcohols such as ethanol, 2-ethoxyethanol and 2-n-butoxyethanol, hydrocarbons such as toluene and xylene and ethers such as tetrahydrofuran and dioxan. Further suitable solvents for use as developers are mixtures of water with an organic solvent selected from those mentioned above which is water-miscible, for example a mixture of water and 2-n-butoxyethanol.

-, ~, .
-_ 33 _ 13~ 9 77 6 The process of the invention is useful in the production of printing plates or printed circuits.
After exposure and development, when the substrate surface is metallic, it may be etched, either to remove metal from unexposed areas in the formation of a printed circuit, or to increase the depth of the image and hence increase its differentiation, the polymerised film in the exposed areas protecting the underlying substrate from attack~ Suitable etching procedures, e.g., usiog ferric chloride or ammonium persulphate solutions on copper substrates, are well known. The remaining film can then, if desired, be removed by treatment with a more powerful solvent than that used for development or with a similar solvent under more severe conditions, to expose the metallic surface below.
In another post-development procedure when the surface of the substrate is metallic, it is plated with a metal such as copper, tin, lead or nickel, the polymerised film in the exposed areas is removed, for example by treatment with a solvent as described above, and the metal thereby bared is etched as hereinbefore described.
The process of the invention is useful in the preparation of buried via-hole printed circuit boards, i.e. multilayer boards made using rigid laminates which have through-hDle plated via holes that interconnect the conductive tracking on their two sides.
The inv~ntion i, illustreted by the following Examples in ' ' ~' ' ~ ' : ~ .

:

:~ ' _ 34 _ ~3 1 97 7 ~

which, unless stated otherwise, all parts are by weight.
Resins used in the Examples are as follows:
Resin I

This denotes a diglycidyl ether of 2,2-bis(4-hydroxyphenyl) propane having an epoxide content of 5.2 equivs./kg.
Resin II

_ This denotes a diglycidyl ether of 2,2-bis(4-hydroxyphenyl) propane having an epoxide content of 5.32 equivs./kg.

Resin III

A 2,2-bis(4-hydroxyphenyl)propane-based epoxy resin having an epoxide content oF 1.6 equivs/kg (100 9) and 2,6-di-tert.butyl-4-methylphenol (0.1 9) are heated until molten, stirred together and heated to 130C. To this mixturs there is slowly added, over 30 minutes, a mixture of acrylic acid (10.7 9), chromium (III) tris octanoate (0.05 9) and 2,6-di-tert.butyl-4-methylphenol (0.2 9).
On complete addition the mixture is stirred at 130~C for a further 2 hours and cooled. The product has a negligible epoxide content.
Resin IV
2,2-Bis(4-glycidyloxyphenyl)propane, having an epoxide content of 5.1 equivalents/kg (100 9), and 2,6-di-tert.butyl-4-methylphenol (0.1 9) are stirred together and heated to 100C.
To this mixture is added slowly, over 1- hours, a mixture of acrylic ,.,.. ... ~ . , "' -.
.

- 35 - 1 ~ 1 9 7 ~ ~

acid (19.1 9), chromium (III) tris octanoate (0.05 9) and 2,6-di-tert.butyl-4-methylphenol (0.2 9). On complete addition the mixture is stirred at 100~C for a further 7 hours and cooled.
The product has a negligible epoxide content.

. ~ :

' - 36 - ~31 97 7 ~

A mixture of a diglycidyl ether of 2,2-bis(4-hydroxyphenyl)-propane having an epoxide content of 5.2 equivs./kg (Resin I) (100.0 9), 1-benzoylcyclohexanol (5.0 9) and diethylamine hydrochloride (0.1 9) is heated at 120C for 4 hours. The resulting mixture, having an epoxide content of 4.77 equivs./kg, is cooled to 60C
and a solution containing methacrylic acid (43.0 9) and 2,6-di-tert.butyl-4-methylphenol (0.2 9) is added over 1 hour.
The mixture is heated for a further 6 hours at 60C and then for 16 hours at 80C, after which time the epoxide content has fallen to 0.28 equiv./kg. Ethylenediaminetetracetic acid dianhydride (5.0 g) is added and the mixture is heated for 2 hours at 120C and then cooled to ambient temperature. The product is a salt-forming group-containing, radiation-polymerisable resin.
To part of the above product (35 9) are added 2-n-butoxy-ethanol (50 9), lactic acid (1.07 g) and water (37.5 9) to give an electrolytic solution. A copper-clad laminate and a stainless steel sheet are immersed in the solution as cathode and anode respectively. An electric current is passed through the solution at 50 volts for 1 minute to deposit a resinous film on the laminate. The laminate is removed from the solution and dried at 90C for 5 minutes, after which the electrodeposited film is a tack-free solid layer having a thickness of 3 to 7 micrometres.
The dried film 19 irradiated through a negative using a 5000w metal .~ ~
.
- :

.

- 37 - 13 1 9 7 7 ~

halide lamp at a distance of 75 cm for 2 minutes. Development of the irradiated film with a mixture of water and 2-n-butoxyethanol (volume ratio 9:1) gives a clear negative image.

A mixture of Resin II (100 parts), 1-benzoylcyclohexanol (5.4 parts) and diethylamine hydrochloride (0.1 part) is heated at 120C for 6 hours. The resulting mixture, having an epoxide content of 4.8 equivs/kg, is conled to 100C and a solution of acrylic acid (37.1 parts), 2,6-di-tert.butyl-4-methylphenol (0.24 part) and chromium (III) trisoctanoate (0.1 part) is added over 45 minutes. The heating at 100C is continued for a further 6~
hours to give a mixture having an epoxide content of 0.11 equiv/kg.
Ethylenediaminetetracetic acid dianhydride (1 .3 parts) is added and the mixture is heated for a further 3l hours at 100C. On cooling, a resinous solid is formed.
To part of the resinous solid (20 parts) are added 2-n-butoxy-ethanol (20 parts), lactic acid (1.28 parts) and water (13 parts) to give an electrolytic solution. A resinous film is electrodeposited from the solution onto a copper-clad laminate as described in Example 1 and dried at 90C for 5 minutes to give a tack-free solid layer having a thickness of 10 micrometres. The dried film is irradiated through a negative using a 5000w metal halide lamp at a distance of 75 cm for 30 seconds. Development of the irFadlated film w-th a mixture oi water and 2-n-butoxyethanol -, .
:, :

- 38 - 131 ~7 7 6 (volume ratio 9:1) gives a clear negative image.

Example 2 is repeated but passing a current at 100 volts ~or 1 minute, instead of 50 volts for 1 minute. After drying at 90C for 5 minutes, the electrodeposited film has a thickness of 10-15 micrometres. The dried film is irradiated through a negative using a 5000w metal halide lamp at a distance of 75 cm for 20 seconds. Development of the irradiated film with a mixture of water and 2-n-butoxyethanol (volume ratio 85:15) gives a clear negative image.

A mixture of Resin II (100 parts), 1-benzoylcyclohexano]
(5.4 parts) and diethylamine hydrochloride (0.1 part) is heated at 110C for 1 hour, then at 125C for 2 hours. The resulting mixture, having an epoxide content of 4.9 equivs/kg, is cooled to 100C and a solution of acrylic acid (37.1 parts), 2,6-di-tert.-butyl-4-methylphenol (0.24 part) and chromium (III) trisoctanoate (0.1 part) is added over 30 minutes. The heating at 100C is continued for a further 63/4 hours to give a mixture having an epoxide content of 0.11 equiv/kg. Ethylenediaminetetracetic acid dianhydride (28.6 parts) and 2-methoxypropyl acetate (100 parts) are added and the mixture is heated for a further 3 hours at 100C.
To part of the resulting solution (20 parts) are added 2-n-butoxyethanol (10 parts), lactic acid (2.0 parts) and water (10.5 parts) to give an electrolytic solution. A resinous film ~ ' ' , '. .
..

131977~
- 39 _ is electrodeposited from the solution onto a copper-clad laminate as described in Example 1, but passing a current at 100 volts for 1 minute instead of 50 volts for 1 minute, and dried at 90C
for 5 minutes to give a tack-free solid layer having a thickness of 10 micrometres. The dried film is irradiated through a negative using a 5000w metal halide lamp at a distance of 75 cm for 60 seconds. Development of the irradiated film with butyl digol (the monobutyl ether of diethylene glycol) gives a clear negative image.

.
Resin III (100 parts) is heated to 120C, ethylenediamine-tetracetic acid dianhydride (3 parts) is added and the mixture is stirr0d for 1 hour. Alpha-methylolbenzoin (4.8 parts) is added and the heating at 120C continued for a further 2 hours, by which time the epoxide content is zero. The mixture is diluted with 2-n-butoxyethanol (107 parts) and cooled to 60~C, at which temperature lactic acid (2.1 parts) is added and the mixture is stirred for 10 minutes. After cooling to ambient temperature, water (4û~parts) and cyclohexanone (40 parts) are added to give an electrolytic solution.
A resinous film is electrodeposited from the solution onto a copper-clad laminate as described in Example 1 and dried at 90C for 10 minutes to give a tack-free solid film 2-5 micrometres thick. The dried film is irradiated through a negative using a `:

:: , .
.

- ~ : ., ~
'~ . -: ' .

5000w metal halide lamp at a distance of 75 cm for 3 minutes.
A negative image is formed on development of the irradiated film by brushing with a mixture of water and 2-n-butoxyethanol (volume ratio 9:2).

Example 5 is repeated but passing a current at 200 volts for 1 minute, instead of 50 volts for 1 minute as in Example 5. The electrodeposited film is treated as in Example 5 to give a negative image under the same conditions.

Resin IV (100 parts), ethylenediaminetetracetic acid dianhydride (10 parts), benzophenone tetracarboxylic acid dianhydride (20 parts), cyclohexanone (50 parts), tetramethyl-ammonium chloride (0.2 part) and 2,6-di-tert.butyl-4-methylphenol (0.3 part) are heated together at 120C for 113/4 hours.
Cyclohexanone (100 parts) and benzyldimethylamine (0.5 part) are added and the heating at 120C continued for a further 2~ hours.
Infra-red spectral analysis showed no anhydride remaining in the resulting solution. Part of the solution (2~ parts) is mixed with lactic acid (0.9 part), water (16 parts) and 2-n-butoxyethanol (25 parts) to give an electrolytic solution.
A resinous film is electrodeposited from the solution onto a copper-clad laminate as described in Example 1 and dried at 90C
for 5 LinuteS to give a tack-free solid film Z-4 micrometres thick.

:

., .

- ~
~, ~ , - , ..

The dried film is irradiated through a negative using a 5000w metal halide lamp at a distance of 75 cm for 5 minutes. A
negative image is formed on development of the irradiated film in a mixture of water and 2-n-butoxyethanol (volume ratio 8:2).

Resin II (100 parts) and chromium (III) trisoctanoate (0.2 part) are heated together to 110C. A solution of acetic acid (28.6 parts) and alpha,alpha-dimethyl-alpha-N-morpholino-p-(2-hydroxyethylthio)acetophenone (16.4 parts) is added over 20 minutes. The heating at 110DC is continued for a further 83/4 hours, after which more acetic acid (2.8 parts) is added and the heating continued for a further 2~ hours, by which time the epoxide content is negligible. The mixture is heated to 120DC, ethylenediaminetetracetic acid dianhydride (14.5 parts) is added and the mixture is stirred at this temperature for 3 hours. Infra -red spectral analysis shows no anhydride remaining in the resulting mixture. Maintaining the temperature at 120DC, glycidyl acrylate (10.9 parts), chromium (III) trisoctanoate (0.1 part) and 2,6-di-tert.butyl-4-methylphenol (0.3 part) are added over 30 minutes.
The heating is continued for a further 3l hours, by which time the epoxide content is negligible. A resinous solid is formed on cooling.
Part of the resinous solid (2n parts) is mixed with 2-n-butoxy-ethanol (10 parts), lactic acid (2 parts) and water (10.5 parts) to give an electrolytic solution. A resinous film is electrodeposited ,.

, ~ :

13~977~

from the solution onto a copper-rlad laminate using the method of Example 1, but passing a current at 100 volts for 1 minute instead of 5û volts for 1 minute, and dried at 9ûC for 5 minutes to give a tack-free solid film 10 micrometres thick. The dried film is irradiated through a negative using a 5000w metal halide lamp at a distance of 75 cm for 1 minute. Development of the irradiated film in butyl digol gives a clear negative image.

~ mixture of Resin II (50 parts), alpha,alpha-dimethyl-alpha-N-morpholino-p-(2-hydroxyethylthio)acetophenone (5 parts) and tetramethylammonium chloride (0.1 part) is stirred at 12ûC
for 7 hours, by which time the epoxide content is 4.4 equivs/kg.
The mixture is cooled to 10ûC and a solution of acrylic acid (17.3 parts), 2,6-di-tert.butyl-4-methylphenol(0.2 part) and chromium (III) trisoctanoate (0.1 part) is added over 30 minutes. After heating for a further 3~ hours at 100C, when the epoxide content is reduced to 0.32 equiv/kg, ethylenediamine tetracetic acid dianhydride (7.3 parts) is added and the heating at 100C is continued for a further 3~ hours. Infra-red spectral analysis of the resulting mixture shows no anhydride remaining. A resinous solid is formed on cooling.
Part of the resinous solid (20 parts) is dissolved in 2-n-butoxyethanol (20 parts) and lactic acid (1.5 part) and water (16 parts) are added to give an electrolytic solution. A resinous ' 131977~

film is electrodeposited from the solution onto a copper-clad laminate using the method of Example 1, but passing the eurrent at 5û volts for 2 minutes instead of 1 minute, and dried at 90C for 5 minutes to give a tack-free solid film 6-8 micrometres thick. The dried film is irradiated through a negative using a 5000w metal halide lamp at a distance of 75 cm for 20 seconds.
Development of the irradiated film in a mixture of water and 2-n-butoxyethanol (volume ratio 9:1) gives a clear negative image.

' '

Claims (20)

1. A process for the production of an image on a substrate having an electrically conductive surface which comprises (i) applying a radiation-polymerizable film to said surface by electrodeposition from a composition comprising a solution or dispersion in an electrodeposition medium of a solid radiation polymerizable resin having, per average molecule, more than one radiation-polymerizable ethylenically unsaturated group, a photoinitiatirlg residue which initiates polymerization of said polymerizable group on exposure to radiation and a salt-forming group which is present at least partially in ionized form, (ii) subjecting the film to radiation in a predetermined pattern, thereby polymerizing exposed areas of the film, and (iii) removing areas of the film not exposed in stage (ii).

2. A process according to claim 1, in which the radiation polymerizable groups are acrylate or methacrylate groups.

3. A process according to claim 1, in which said photoinitiating residue is a benzophenone, ketocoumarin, benzil, anthraquinone, phenanthraquinone, alpha-substituted acetophenone, acylphosphine oxide, O-acylated alpha-oximinoketone, xanthone or thioxanthone residue connected lo the remainder of the resin molecule through one or more linkages.

4. A process according to claim 3, in which the photoinitiating residue is (a) a benzophenone residue of one of the formulae -Ar1-CO-Ar2 IA

-Ar1-CO-Ar1- IB

IC

ID

(b) an alpha-substituted acetophenone residue of one of the formulae II

III

IV

V

VI

or (c) a thioxanthone residue of formula VII

the photoinitiating residue being linked to the remainder of the resin molecule through the indicated free valencies, where Ar1 denotes a phenylene group which is unsubstituted or substituted by 1 to 3 substituents R7, Ar2 denotes a phenyl group which is unsubstitutr3d or substituted by 1 to 3 substituents R7, Ar3 denotes a benzene triyl group which is unsubstituted or substituted by 1 to 3 substituents R7, R1 denotes a hydrogen atom or a group -CH2R8, R2 denotes a hydrogen atom, -OCH2R8, or -CH2OR8 R3 denotes a C1 to C20 alkylene group, which may be interrupted by one or more oxygen atoms, R4 and R5 each denote a hydrogen atom or a monovalent aliphatic, cycloaliphatic or araliphatic group or, together with the attached carbon atom, denote a cycloalkylene group, R6 denotes -OH, amino or an alkylated or silylated hydroxyl or amino group, R7 denotes a halogen atom, C1 to C20 alkyl, C1 to C20 haloalkyl, C1 to C20 alkoxy, C6 to C12 aryloxy, C2 to C20 acyloxy, C2 to C20 alkoxycarbonyl, C7 to C13aracyloxy, C2 to C40 dialkylamino, C1 to C20 alkylthio, C6 to C12 arylthio or cyano, R8 denotes a hydrogen atom, -OH, C1 to C8 alkyl, C1 to C4 alkoxy, C2 to C3 alkenyl, C7 to C9 aralkyl, C8 or C9 aralkenyl or -(CH2)aR9, R9 denotes halogen, -OH, C1 to C4 alkoxy, C1 to C4 alkylthio, phenoxy, phenylthio, C2 to C8 acyloxy, C7 to C12 aracyloxy or C2 to C8 alkoxycarbonyl, and a denotes 1, 2 or 3.

5. A process according to claim 4, in which the photoinitiating residue is of formula 10 where Ar3 denotes an unsubstituted benzene triyl group, of formula IV where R1 denotes a hydrogen atom and R3 denotes a methylene group, of formula V where R4 and R5 each denote a methyl group and R6 denotes a N-morpholino group, or is of formula VI, where R4 and R5, together with the carbon atom to which they are attached, denote a cyclohexylene group.

6. A process according to claim 1, in which the radiation-polymerizable resin is a reaction product of (A) a substance having at least one said radiation-polymerizable group and at least one reactive functional group X with (B) a compound having said photoinitiating residue and at least one group Y which is reactive with the group X, or a product of reaction of the reaction product of (A) and (B) with at least one further substance (C) to increase the molecular weight thereof, the salt-forming group being present in (A), (B) or (C) or being introduced into the reaction product of (A) and (B) or the reaction product thereof with (C).

7. A process according to claim 6, in which (A) is a substance having at least one radiation polymerizable ethylenically unsaturated group and (B) is a compound having a benzophenone, alpha-substituted acetophenone or thioxanthone photoinitiating residue, one of (A) and (B) having an epoxide group and the other having a hydroxyl, carboxyl, carboxylic acid anhydride or phosphonic acid group.

8. A proccss according to claim 7, in which (A) is (A1) a substance having at 1east one radiation-polymerizable ethylenically unsaturated group and at least one hydroxyl, carboxyl or phosphonic acid group and (B) is (B1) a compound having a benzophenone, alpha-substituted acetophenone or thioxanthone photoinitiating residue and at least one epoxide group.

9. A process according to claim 8, in which (B1) is a reaction product of an epoxide resin with less than a stoichiometric amount of a compound having said photoinitiating residue and at least one hydroxyl, carboxyl or phosphonic acid group.

10. A process according to claim 7, in which (A) is (A2) a substance having at least one radiation-polymerizable ethylenically unsaturated group and at least one epoxide group and (B) is (B2) a compound having a benzophenone, alpha-substituted acetophenone or thioxanthone photoinitiating residue and at least one hydroxyl, carboxyl, carboxylic acid anhydride or phosphonic acid group.

11. A process according to claim 7, in which the radiation-polymerizable resin is a reaction product of (P) an epoxide resin with, in either order or simuitaneously, (Q) acrylic or methacrylic acid or an adduct of a hydroxyalkyl ester thereof with a polycarboxylic acid anhydride and (R) a compound selected from the group consisting of a benzophenone of one of the formulae Y1-Ar1-CO-Ar2 VIIIA

Y1-Ar1-CO-Ar1-Y1 VIIIB

VIIIC

or an alpha-substituted acetophenone of one of the formulae IX

X

XI

or a thioxanthone of formula XII

where Ar1, Ar2, Ar3, R1, R3, R4, R5 and R6 are as defined in claim 4, Y1 denotes -OH or -COOH, Y2 denotes Y1 or -SCH2CH2OH, Y3 denotes Y1 or P(=O)(OCH2CH3)OH, Y4 denotes Y1 or -OCH2CH(OH)CH2N(R14)R15, and R14 and R15, which are the same or different, each denote a C1 to C20 alkyl group, which is unsubstituted or substituted by a hydroxyl group, or R14 and R15 together with the nitrogen atom to which they are attached, denote a heterocyclic ring containing 3 to 5 carbon atoms, or 3 to 5 carbon atoms and one oxygen or sulfur atom or one further nitrogen atom, in the ring.

12. A process according to claim 11, in which (R) is o-benzoyl-benzoic acid; alpha-methylolbenzoin; alpha, alpha-dimethyl-alpha-N-morpholino-p-(2-hydroxyethylthio)acetophenone; or 1-benzoylcyclo-hexanol.

13. A process according to claim 7, in which a salt-forming group is introduced into the reaction product of (A) and (B) by reacting it with (C) a dianhydride of a polycarboxylic acid.

14. A process according to claim 13, in which the dianhydride is that of ethylenediaminetetracetic acid.

15. A process according to claim 7, in which (A) is (A3) glycidyl acrylate or glycidyl methacrylate and (B) is (B3) a carboxyl-containing resin prepared by (a) reacting an epoxide resin with a compound selected from the group consisting of a benzophenone of one of the formulae Y1-Ar1-CO-Ar2 VIIIA
Y1-Ar1-CO-Ar1-Y1 VIIIB

VIIIC

or an alpha-substituted acetophenone of one of the formulae IX
X

XI

or a thioxanthone of formula XII

where Ar1, Ar2, Ar3, R1, R3, R4, R5 and R6 are as defined in claim 4, Y1 denotes -OH or -COOH, Y2 denotes Y1 or -SCH2CH2OH, Y3 denotes Y1 or P(=O)(OCH2CH3)OH, Y4 denotes Y1 or -OCH2CH(OH)CH2N(R14)R15, and R14 and R15, which are the same or different, each denote a C1 to C20 alkyl yroup, which is unsubstituted or substituted by a hydroxyl group, or R14 and R15, together with the nitrogen atom to which they are attached, denote a heterocyclic ring containing 3 to 5 carbon atoms, or 3 to 5 carbon atoms and one oxygen or sulfur atom or one further nitrogen atom, in the ring, and (b) reacting the resulting product, through secondary alcoholic hydroxyl groups thereof, with a dianhydride of a polycarboxylic acid.

16. A process according to claim 6, in which (A) is (A5) a substance having at least one radiation-polymerizable unsaturated group and, on average, more than one hydroxyl group per molecule and (B) is (B5) a benzophenone tetracarboxylic acid dianhydride or a mixture thereof with another anhydride.

17. A process according to claim 1, in which the radiation-polymerizable resin contains a basic salt-forming group and electrodeposition in step (i) is effected from a solution or dispersion thereof in an aqueous medium together with an acid which at least partially neutralizes the basic group, or the radiation-polymerizable resin contains an acidic salt-forming group and electrodeposition in step (i) is effected from a solution or dispersion thereof in an aqueous medium together with a base which at least partially neutralizes the acidic group.

18. A process according to claim 1, in which step (ii) is effected using electromagnetic radiation of wavelength 200 to 600 nm.

19. A composition suitable for carrying out a process according to claim 1 comprising a solution or dispersion in an aqueous solvent of a radiation-polymerizable resin having a salt-forming group as specified in claim 1, and an acid or base which at least partially neutralizes the salt-forming group.

20. A solid radiation-polymerizable, salt-forming group-containing resin suitable for use in a process according to claim 1 which is a reaction product of (A) a substance having at least one radiation-polymerizable ethylenically unsaturated group and (B) a compound having a benzophenone, alpha-substituted acetophenone or thioxanthone photoinitiating residue, one of (A) and (B) having an epoxide group and the other having a hydroxyl, carboxyl or phosphonic acid group, or said reaction product modified to increase the molecular weight thereof by reaction with at least one further substance (C), said reaction product having a salt-forming group derived from (A), (B) or (C) or having a salt-forming group introduced therein by further reaction thereof.