KR100685318B1 - Positive-Acting Photoresist Composition and Imageable Element - Google Patents

Abstract

The present invention relates to a positive-acting thermosensitive composition for coating on a lithographic base or a printed circuit board. The composition contains a water soluble thermosensitive resin, a novolak adhesion promoter and a radiation absorber (dye or pigment). Only good film forming polymers containing acetal units suspended directly on the polyvinyl alcohol backbone can be used as binder resins. The coating formed using the composition has a considerably high solubility in an alkaline developer where the area exposed to the near infrared laser beam is weak, so that a high resolution pattern of an etch resistant material can be obtained on a printed circuit board or a lithographic printed board. The composition may be applied in a liquid state or laminated in the form of a dry film. In addition, by adding a photosensitizer to the composition, the composition may have a sensitivity to radiation.

Positive action, lithography, laser, printed circuit board, thermosensitive composition, polyvinyl alcohol, acetal monomer, novolac, radiation absorber

Description

Positive-Acting Photoresist Composition and Imageable Element

FIELD OF THE INVENTION The present invention relates to the field of imaging, in particular to resist imaging, more particularly to thermal resist imaging, and very particularly to laser direct imaging. The present invention discloses a novel positive action dermal resist composition, a dermal resist member, a dermal resist process, a dermal resist system, and a novel synthetic method for forming the resist material.

The advantages of Laser Direct Imaging (LDI) have long been recognized in the printing field for the manufacture of offset printed plates and in the field of printed circuit boards (PCBs). LDI offers potential benefits such as better line quality, timely production, improved manufacturing yield, and elimination of membrane costs. In the direct imaging method, the coating composition must be changed in order to expose only selected areas of the thermosensitive coating using a moderately focused energy source. See, for example, the disclosures of US Pat. No. 4,724,465, US Pat. No. 5,641,608 (McDermid), and US Pat. No. 5,713,287 (Gelbart).                         

The thermosensitive image forming member is classified into a composition that responds to exposure to an appropriate amount of thermal energy and absorbs the energy to change chemically. Thus chemically altered by heat, the composition may be removed, or the solubility of the composition in a particular developer may change, or the thickness of the thermosensitive layer surface may change, or the layer surface The hydrophobicity or hydrophilicity of can be changed. As such, selectively exposing a predetermined region of a film or layer of thermosensitive composition to heat, directly or indirectly, a suitably imaged pattern used as a resist pattern in PCB fabrication or lithographic printing plate fabrication. Can be obtained.

Similar to the case of photoresist, the thermosensitive composition can have a positive action or a negative action. In the case of positive action thermosensitive compositions, selectively exposing the membrane to a suitably focused beam of light that can generate the required thermal energy may result in (a) removal of the exposed composition, or (b) the exposed composition having a particularly high solubility in a suitable solvent. Will have In the case of (a), a desired graphic pattern is obtained directly, which represents a portion of the remaining film which is not exposed to the focused heat energy, and in the case of (b), a latent image is formed on the film. This can be obtained. By this latent image, a portion exposed to heat of the film is dissolved, and a portion not exposed to heat is left in an undissolved state, whereby a desired pattern is obtained. In the case of the negative acting composition, if the film is selectively exposed to a moderately focused beam of required thermal energy, the exposed portion will have a lower solubility in a suitable developer, thereby not being exposed to the heat upon contact with the developer. The portion is dissolved away and the portion exposed to the heat remains in the desired pattern.

Through the use of the thermosensitive image forming component, it is possible to greatly increase the ability to form a pattern on the substrate surface by direct image forming without using an optical device, which is a wavelength required for the direct image formation of the photoresist This is because, in contrast to the narrow band focused radiation source of, only moderately focused rays of the required thermal energy are required for imaging, as can be formed from low cost solid state lasers. Focused thermal energy sources such as infrared laser beams are more suitable for use in commercial scale processes in terms of cost, lifetime and reliability compared to the UV light required for direct imaging of many photosensitive compositions. In addition, the thermosensitive composition, which should undergo only a change by heat rather than a change by light, has a less complicated direct image forming process than the photosensitive composition. As such, thermally sensitive compositions required for industrial purposes, such as PCB fabrication, can be manufactured at an economical cost, and the compositions can act in room light or daylight because of their simpler action and can exhibit better storage stability. .

Positive action photosensitive compositions based on novolac-diazoquinone resins are the major image forming materials in the computer chip industry (R, R. Dammel, "Diazonaphthoquione-based Resists", Tutorial text No. 11, SPIE Press, Bellingham, WA. 1993).

In addition, the composition of the photosensitive novolak-diazoquinone resin is widely used in the production of printing plates. The photosensitive diazonaphthoquinone derivative (DNQ) added to the novolak resin (phenol-formaldehyde condensation polymer) delays the dissolution of the resin, and the exposed membrane (photoinductive decomposition composition of the DNQ) It dissolves somewhat faster than the rock membrane. Recently, a modified molecular mechanism of novolak-DNQ phase forming material has been published (A. Reiser, Journal of Imaging Science and Technology, Volume 42, Number 1, January / Febrary 1998, pp 15-22). The document indicates that the basic feature of the phase formation phenomenon in the novolak-diazonaphthoquinone composition is that it inhibits the dissolution of the resin. This inhibition is based on the formation of phenolic strings by the interaction of the OH groups of the resin with strong hydrogen acceptors that act as solubility inhibitors. Upon exposure, the phenol string is cleaved from its anchor by thermal effects (wolf displacement) and photolysis of the diazoquinone portion of the subsequent inhibitor molecule. This displacement is not only very fast but also very exothermic (delta H ° = -66 kcal / mol). A sudden phenomenon at the solubility inhibitor site with this degree of thermal vibration results in a temperature rise of about 220 ° C. or less. At these high temperatures, the DNQ of the phenol string is no longer held together by the inducing effect of the solubility inhibitors and is therefore cleaved from its anchors to inactivate (dispersion).

From this model it can be explained that a wide range of thermosensitive compositions based on novolak resins containing different types of inhibitors have appeared in the patent literature and commercial literature. For example, positive action direct laser injection printing compositions using phenolic resin precursors that are sensitive to UV, visible and / or infrared light have been disclosed (US Pat. No. 4,708,925 (Newman, 3M), US Pat. No. 5,372,907 (Haley et al.). , Kodak), US Pat. No. 5,491,046 (DeBoer et al., Kodak). In US Pat. No. 4,708,925, the solubility of phenolic resins in alkaline solutions is reduced using onium salts instead of DNQ, the natural solubility of the resins being restored upon photolysis of the onium salts. The onium salt is inherently sensitive to UV radiation and may further be sensitive to infrared radiation. US Pat. Nos. 5,372,907 and 5,491,064 increase the solubility of the resin upon exposure using a direct positive functional system based on the radiation-inducing composition of the hidden Bronsted acid. The three compositions disclosed above can be further used as negative action systems by further treatment after imaging and predevelopment.

WO 97/39894 (Horsell) discloses thermosensitive compositions and methods for producing lithographic printing plates using laser scanning imaging (LDI). The composition contains a complex of a phenolic resin and a strong hydrogen acceptor containing inhibitor. Examples of such receptors are heterocyclic compounds containing at least one nitrogen atom that is quaternized. In addition, a series of carbonyl-containing compounds known as inhibitors contained in the UV-sensitive compositions of phenolic resins have been identified as inhibitors for the thermosensitive compositions. This is not surprising given the above mentioned model (A. Reiser). The compositions disclosed in WO 97/39894 (Horsell) are judged to be insensitive to UV and visible light, unlike compositions based on the onium salts or Bronsted acid decompositions mentioned above.

WO 97/39894 discloses radiation absorbing compounds which can absorb incident radiation and convert it into heat. The above document uses, for example, a dye selected from the group consisting of squarylium, cyanine, merocyanine, pyryllium and the like. In addition, organic or inorganic pigments such as carbon black or phthalocyanine pigments can also be used as radiation absorbing materials that convert the absorbed light into heat.

WO 99/08879 (Horsell) discloses radiation sensitive compositions for use in coatings for the manufacture of printed circuits and their electronic components and for the manufacture of masks. Such coating compositions contain phenolic resins with insufficient mechanical properties.

WO 99/01795 (Horsell) discloses a method for forming a predetermined mask pattern, for example on a printed board, a circuit board or a mask. The method is characterized by the use of new polymeric materials having functional groups that are insoluble in developer but can dissolve in developer upon exposure to radiation. The functional group is not a diazide group as in a conventional system but is a group having a hydrogen bonding ability without releasing nitrogen upon exposure to radiation. Examples of such groups are 2-naphthylsulfonyloxy, 2-thienylsulfonyloxy, dasyloxy, p-toluenesulfonyloxy, benzyloxy and n-butylsulfonyloxy.

WO 99/21725 (Horsell) discloses novolak resin based compositions used in the manufacture of lithographic printing plates. The solubility of the heating zone of the composition in the aqueous developer is increased. The composition contains a compound which increases the resistance of the non-heated region of the thermosensitive composition to development (dissolution) in an aqueous developer. The composition comprises A) poly (alkylene oxide) units; B) silane monomers; C) compounds such as amides of esters, ethers and polyhydric alcohols.

WO 98/42507 (Kodak Polychrome Graphics) discloses a positive action thermosensitive composition that can be imaged using an infrared laser without the need for post-exposure heat treatment steps and flooding exposure steps. Such compositions contain phenolic resins, infrared absorbing compounds, and dissolution inhibitors. The dissolution inhibitor is non-photosensitive and is capable of providing the phenol portion of the resin at the hydrogen bonding site.

WO 99/08157 (Kodak Polychrome Graphics) discloses an infrared imaging composition containing two essential components: a non-basic infrared absorbing material (eg carbon black) and a phenolic resin. The phenol resin is one that is mixed or reacted with a diazonaptoquinone derivative. Such compositions are useful for positive action or negative action imaging as in the case of lithographic printing plates.

WO 99/11458 (Kodak Polychrome Graphics) discloses phenolic resins (or suspended hydroxy, carboxylic acids, amides, nitric acids or mixtures thereof) and infrared absorbing compositions. The imaging layer may also contain a second polymer that is a bonded hanging group, and the hanging groups include 1,2-naphthoquinone diazide, hydroxy, carboxylic acid, sulfonide, nitrile, and the like. . The phase forming layer may also contain a solubility inhibitor or a visible dye or both.

Many heat induction compositions for use as thermal print recording materials are disclosed in GB 1,245,924 (Agfa). The solubility of the imageable layer in a given solvent can be increased by heating the layer using short term high density visible and / or infrared light transmitted or reflected from the background portion of the graphics placed in contact with the recording material. . The systems disclosed in this document operate according to many different mechanisms and utilize a variety of developers, from water to chlorinated organic solvents. The composition which can be developed in an aqueous state includes a novolak resin. The patent discloses that a coating made of such a resin exhibits increased solubility upon heating. The composition may contain an endothermic compound such as carbon black or Milori Blue (C.I. Pigment Blue 27), which material additionally colors the image for use as a recording medium.

As the inventors of the present invention know, there are several positive action thermosensitive compositions that are directly related to the fabrication of printed circuit boards using LDI. Compositions of this type are disclosed in US Pat. No. 5,641,608, but the coating composition on the copper surface of the printed circuit board was initially scanned using a UV laser and later only using an infrared laser. Another example of the positive acting dermal resist described in this patent contains no radiation absorbing material capable of converting infrared light into heat. In addition, it is not clear whether the composition which transmits IR light changes the chemical action (pyrolysis of t-butyloxy carbonyl protecting group) to provide a difference in the developer. In addition, when the negative acting composition does not contain a radiation absorbing material, the chemical action is not obvious even in the case of the negative acting composition exposed to infrared rays.

The advantages of positive acting photoresists used as monolayer dry films compared to negative acting dry resists in the manufacture of printed circuit boards are described in European Patent No. 0848290 (Morton) and in TAKoes and SHWheeler, IPC Expo 98 Proceedings. , S12-3-1.

An example of a thermosensitive negative acting resist composition is given in US Pat. No. 5,512,418 (Ma, Du Pont), where the energy required for polymerization of the phased regions is 600 mJ / cm ² and the time required for phase formation is It is very long and therefore does not meet the high yield requirements of the PCB industry.

Polyvinyl acetals, especially polyvinyl butyral, have been used as binders in various products because of their excellent film-forming properties and their excellent mechanical properties. These polymers are also known to have very good chemical resistance. One example of the use of such a polymer is a radiation sensitive composition, in which the polymer is used as a binder for the production of negative action printed plates and for the production of photoresists for printed circuit boards. The polyvinyl butyral or polyvinyl formals are classified as substances which cannot be dissolved in the aqueous developer used for the production of printed plates or printed circuit boards. Many different polymers have been proposed for use as binders of negative action UV-sensitive compositions that provide the required water solubility.

Particular advantages have been obtained for polymers having hydroxy or carboxyl groups in the acetal moiety.

Such binder polymers are disclosed in US Pat. Nos. 4,665,124, 4,940,465, 5,169,898, 5,169,897, 5,700,619. Photosensitive materials containing resin binders comprising aromatic diazonium salts with only one diazo group and vinyl polymers with phenolic hydroxy groups are disclosed in US Pat. No. 4,374,194. In addition, polymers containing p-hydroxybenzyl moieties are disclosed in US Pat. No. 5,792,823, which is a precursor of polymers used as chemically amplified positive action resists in microlithography. However, the hydroxybenzaldehyde acetal polymer is not used directly as a composition of the positive action resist layer. Japanese Patent No. 09,328,519 discloses a similar polyvinyl acetal used as an oxygen inhibitor.

The present invention provides novel positive acting compositions and members that can be imaged by heat. The thermally activatable positive action composition contains a specific class of thermosensitive polyvinyl acetals as endothermic component, adhesion promoter and resin binder component. Preferred imaging composition of the present invention is a thermosensitive composition containing, as a main component, a polymer whose solubility is changed by heat in a weak alkaline solution when near-infrared radiation is irradiated in a laser imaging apparatus.

Thus, according to the first embodiment, the composition of the present invention contains an acetal polymer having repeating units of formula (1) in the backbone:

In which R ₁ is —C _n H _{2n + 1} , wherein n = 1-12;

R ₂ is a phenol group, which may have no substituent or may have one substituent (preferably up to three) selected from the group consisting of —HO, —OCH ₃ , Br and —NO ₂ or —COCH, and A phenol group which may be at least partially represented by formula (2) or formula (3),

In formulas (2) and (3), R ₄ is -OH, R ₅ is -OH or -OCH ₃ or Br or O-CH ₂ -C≡CH, R ₆ is Br or NO ₂ ,

이고, R₇은 COOH, -(CH₂)₃-COOH, 또는 -O-(CH₂)₃-COOH이고, In formula (1), R ₃ is-(CH ₂ ) ₃ -COOH, -C≡CH, or

R ₇ is COOH, — (CH ₂ ) ₃ —COOH, or —O— (CH ₂ ) ₃ —COOH,

In the formula (1), m is 5-40 mol%, preferably 15-35 mol%, n is 10-60 mol%, preferably 20-40 mol%, o is 0-20 mol% , Preferably 0-10 mol%, p is 2-20 mol%, preferably 1-10 mol%, q is 5-50 mol%, preferably 15-40 mol%.

As represented by the formula (1), the acetal polymer of the present invention is a tetramer wherein the repeating unit contains a vinyl acetate moiety and a vinyl alcohol moiety and the first and second cyclic acetal groups, or It consists of a vinyl alcohol moiety, a vinyl acetate moiety and a pentamer containing first, second and third cyclic acetal groups. The three acetal groups are 6-membered ring acetal groups, one of which is substituted with an alkyl group, the other with hydroxy, or hydroxy and alkoxy, or nitro and Br groups, and the last one with acid, acid substitutions. It is substituted by an alkyl group or an acid substituted aryl group. A particularly possible advantage on the copper surface is obtained when R ₅ is -CH≡CH. Such special groups provide good adhesion to the copper surface, as described in detail herein.

One important component for the practice of the present invention is the thermosensitive polymer component selected for the positive action resist layer. As mentioned above, such acetal polymers have repeating units represented by the following formula (1) and should contain about 5 to 60 mole percent phenol groups in the polymer backbone:                     

[Formula 1]

In which R ₁ is —C _n H _{2n + 1} , wherein n = 1-12;

R ₂ is a phenol group, which may have no substituent or may have one substituent (preferably up to three) selected from the group consisting of —HO, —OCH ₃ , Br and —NO ₂ or —COCH, and A phenol group which may be at least partially represented by formula (2) or formula (3),

[Formula 2]

[Formula 3]

In formulas (2) and (3), R ₄ is -OH, R ₅ is -OH or -OCH ₃ or Br or O-CH ₂ -C≡CH, R ₆ is Br or NO ₂ ,

이고, R₇은 COOH, -(CH₂)₃-COOH, 또는 -O-(CH₂)₃-COOH이고, In formula (1), R ₃ is-(CH ₂ ) ₃ -COOH, -C≡CH, or

R ₇ is COOH, — (CH ₂ ) ₃ —COOH, or —O— (CH ₂ ) ₃ —COOH,

In the formula (1), m is about 5-40 mol%, preferably 15-35 mol%, n is 5-60 mol% or about 10-60 mol%, preferably 20-40 mol% o is 0-20 mol%, preferably 0-10 mol%, p is 2-20 mol%, preferably 1-10 mol%, q is 5-50 mol%, preferably 15- 40 mol%.

By varying the ratio of these groups, one skilled in the art can tailor the properties of the polymer to any particular requirements of the resist process used in the practice of the present invention. Use of these phenolic substituents in low proportions (eg 5-40%, 10-30%, 15-30%) yields more flexible and less brittle polymers, while higher proportions (eg 30-60%) 35-50%) gives a polymer that is readily soluble by thermal energy. It is within the scope of the present invention to further provide other bonding groups in the polymer thistle to suit the polymer for any application.

The term "containing polymer chain" is used in a non-limiting sense to indicate that other groups may be present in the polymer chain. When expressions such as "polymer chains consisting essentially of" or "polymer chains consisting of" are used, these expressions have the meaning of defining only repeating units of the general type on the polymer chain, and which define substituents on the polymer chain unit. It does not represent meaning. As mentioned above, such polymers are described in the patent literature and the inventors of the present invention have developed a novel method described herein which is believed to be advantageous for controlling the amount of phenolic substituents during the manufacturing process of the polymer.

As shown in the above formula (1), the acetal polymer of the present invention is a tetrameric acetal polymer or a pentameric polymer. In the case of the tetrameric polymer, the repeating unit contains the vinyl acetate moiety and the vinyl alcohol moiety and the first and second cyclic acetal groups as defined above. In the case of the pentameric polymer, the repeating unit contains a vinyl alcohol moiety, a vinyl acetate moiety, first, second and third cyclic acetal groups as defined above. All three of these available acetal groups are 6-membered cyclic groups, one of which is substituted with an alkyl group and the other is hydroxy, hydroxy and alkoxy, or hydroxy and optionally nitro, Br- And an aromatic group substituted with an acetylene C≡C- group, the last one being substituted with an acid group, an acid substituted alkyl group or an acid substituted aryl group. The endothermic component of the composition of the present invention may be selected from known materials that can absorb infrared radiation and convert it to heat. Examples of such materials are organic and inorganic dyes and pigments that absorb IR radiation and convert it to heat.

Carbon blacks that absorb light in the near infrared region, certain phthalocyanine pigments, squaraine dyes, squarylium dyes, cyanine dyes, macrocyanine dyes, pyryllium dyes, benzinedolium dyes, metal oxides and other classes of materials are known to those skilled in the art. Known. The amount of material present in the composition that absorbs infrared light and converts it into heat is generally specified in specifying the amount of heat desired, the intensity of the IR source, the duration of exposure (e.g. pulse length from the laser), and the sensitivity of the system. Selection is based on other factors considered. Generally, the endothermic component is 0.1 to 20% by weight, preferably 0.5 to 10% by weight, more preferably 0.8 to 8% by weight, most preferably 1 to 7% by weight, based on the weight of the composition Present in quantities. If more than this range is used, the physical properties of the resist layer may be affected. Lesser amounts than the above range may be used, but in this case an optimized laser device should be used.

The thermosensitive composition containing the polymer of the present invention provides a lithographic printing plate characterized by improved wear resistance and extended compression performance. In addition, such compositions provide important advantages in that they can be processed in alkaline aqueous solutions that do not contain organic solvents. A lithographic printing plate produced using the optimized composition according to the present invention is one that can be printed 500,000 times.

In addition, the thermosensitive composition containing the polymer of the present invention has excellent film forming properties and improved adhesion, which can provide a resist film with almost no defects at low thickness and low cost, Since the solubility difference is excellent, the etching resistance to an acidic or alkaline etching solution and the strippability in an alkaline aqueous solution are excellent, a high density printed circuit board having high resolution is provided.

Furthermore, according to another aspect of the invention, the composition of the invention has optimized thermal and mechanical properties, so that it can be applied in a liquid state or laminated in a dry monolayer on a substrate for the production of a printed circuit board. Advantage is obtained.

In order to increase the sensitivity of the thermosensitive composition of the present invention, a radiation absorbent is included which can absorb incident infrared rays and convert them into heat. Suitable radiation absorbers for the thermosensitive composition of the present invention can be selected from a wide range of organic and inorganic pigments such as carbon black, metal oxides, phthalocyanines and the like. Infrared absorbing dyes are also preferred endothermic agents that can be used in the compositions of the present invention. In particular, such dyes are those that absorb infrared light at wavelengths of 700 nm or more, such as about 700 to 1300 nm. Generally, materials are used that absorb near-infrared wavelengths of about 700 to 1000 nm.

The compositions of the present invention also contain a mixture of polyvinyl acetal resins and other polymers derived from aliphatic and aromatic aldehydes having hydroxy and / or other functional groups. Examples of such other polymers include acrylates, methacrylates, polyurethanes, styrene-maleic anhydride copolymers, phenols, polyvinyl ketones, alkylvinylethers, cellulose derivatives, epoxy resins, and the like. In addition, such other polymers may provide additional physical properties that are desirable for the formation of the resist coating of the present invention. For example, more lipophilic resins or compositions can be used to enhance the bonding properties of the lithographic member. By adding a thermosoftening polymer having better adhesion to a specific surface to the polyvinyl acetal resin used in the present invention, it is possible to improve the adhesion, especially when a dry film lamination resist is used. have.

According to another aspect of the present invention, a method for synthesizing the polymer is provided. By the process provided herein, the conversion of aldehydes is achieved at high levels while the acetalization of polyvinyl hydroxy groups with aromatic aldehydes having hydroxy groups is achieved at high levels.

According to another aspect of the present invention, a novel adhesion promoter of the resist composition of the present invention for improving the binding of the coating resist to at least the copper surface due to the affinity for the triple bond (acetylene bond) in the adhesion promoter to copper is Is provided.

The thermosensitive composition of the present invention is suitable for use as a thermosensitive positive action resist for producing printed circuit boards by heating phase forming and as a precursor for positive action printing imaged by a thermal laser. It shows a generally known advantage for liquid resists (Proceedings IPC Show 98, Ev, Halevy, Yossi Atiya). Another advantage of the compositions of the present invention is the ability to form films with improved adhesion and good mechanical properties to substrates such as anodized aluminum for printed circuit board manufacture and copper clads for printed circuit board manufacture. Still another advantage of the present invention is that the composition can be applied in a liquid state or as a dry film using hot roller lamination.

In addition, another advantage of the thermosensitive composition of the present invention is that the solubility difference between the exposed and unexposed areas in the developer using an aqueous developer that does not contain an organic solvent is obvious. And because of the insensitivity of the composition to white light, the coated product can be handled in white light.

The resist member of the present invention may be generally described as a positive-acting thermal resist element comprising a metal surface having a positive acting thermally resist layer attached to at least one surface of the substrate. The positive action dermal resist layer comprises an acetal polymer comprising 5-40 mole percent of an aliphatic acetal group and 10-60 mole percent of a phenol acetal group and 0.01 to 20% by weight or 30% by weight based on the weight of the resist layer. Contains infrared absorbing material. The resist layer is preferably 1 to 30 micrometers thick, but preferably 3 to 50 micrometers or 5-50 micrometers or 10-50 micrometers thick when applied to a dry thermal resist film. The solubility change achieved in the compositions of the present invention is sufficiently persistent that no instantaneous phenomenon is necessary. The latent image obtained by thermal imaging was found to last for several days.

Polyvinyl acetal polymers of the present invention include acetal polymers having repeating units of formula (1) in the polymer backbone:

[Formula 1]

In which R ₁ is —C _n H _{2n + 1} , wherein n = 1-12;

R ₂ is represented by the following formula (2) or formula (3),

[Formula 2]

[Formula 3]

In formulas (2) and (3), R ₄ is -OH, R ₅ is -OH or -OCH ₃ or Br or O-CH ₂ -C≡CH, R ₆ is Br or NO ₂ ,

이고, R₇은 COOH, -(CH₂)₃-COOH, 또는 -O-(CH₂)₃-COOH이고, In formula (1), R ₃ is-(CH ₂ ) ₃ -COOH, -C≡CH, or

R ₇ is COOH, — (CH ₂ ) ₃ —COOH, or —O— (CH ₂ ) ₃ —COOH,

In the formula (1), m is about 5-40 mol%, preferably 15-35 mol%, n is about 10-60 mol%, preferably 20-40 mol%, o is 0-20 Mol%, preferably 0-10 mol%, p is 2-20 mol%, preferably 1-10 mol%, q is 5-50 mol%, preferably 15-40 mol%.

As represented by the formula (1), the acetal polymer of the present invention is a tetramer of which the repeating unit contains a vinyl acetate moiety and a vinyl alcohol moiety and first and second cyclic acetal groups, or a repeating unit Is composed of a vinyl alcohol moiety, a vinyl acetate moiety and a pentamer containing first, second and third cyclic acetal groups. The three acetal groups are 6-membered ring acetal groups, one of which is substituted with an alkyl group, the other with hydroxy, or hydroxy and alkoxy, or nitro and Br groups, and the last one with acid, acid substitutions. It is substituted by an alkyl group or an acid substituted aryl group.

This thermosensitive polymer structure is selected because it is known to have excellent mechanical properties of a polymer containing a polyvinyl alcohol backbone, has excellent film forming properties, has excellent abrasion resistance, and excellent chemical resistance. Changing the polyvinyl alcohol can be easily carried out as a wide range.

The acetal unit containing the phenol group may cause a phase formation ability (thermal sensitivity), and such a unit may function similarly to the above-described novolak-based polymer. The hydroxy group is one capable of improving intermolecular or intramolecular hydrogen bonding with the acetal oxygen or oxygen of residual hydroxy groups from the backbone polymer molecule. This bond prevents the polymer from easily dissolving in the alkaline developer. When the material is exposed to an incident energy source, the radiation absorbing material converts the absorbed energy into heat. This heat breaks the H- bond formed in the coating to promote dissolution of the exposure area. Due to the breakdown of such bonds, there is a difference in solubility between the exposed and non-exposed areas in the aqueous alkaline developer. The difference in solubility between the exposed and non-exposed areas is an inherent feature of the polymer film, so it is possible to increase the solubility by attacking parts or bonds in the polymer chain, such as a heat generating material or diazonaphthoquinone (DNQ). There is no need to use a dissolution inhibitor. Such compounds may be present but are preferably not added as this increases the material and compounding cost of the resist layer. The solubility of the heated area is substantially increased by an amount useful for printed circuit board manufacture or lithographic printed plate manufacture. This solubility difference may increase slightly due to the formation of thermally brittle composites with absorbing pigments or dyes used in very small amounts to convert radiation energy into heat.

The suspended aliphatic acetal portion causes thermal properties (T ₈ ) and hydrophobicity (ink water solubility) when used in the manufacture of printed plates, and etch resistance when used in the manufacture of printed circuit boards.

It is believed that the aromatic group having a carboxyl functional group or the third acetal group containing the suspended carboxylic acid increases the solubility in the aqueous developer. Such third acetal groups are optional in the polymer structure. Thus, by optimizing the ratio between the acetal portion of the backbone polymer and the remaining hydroxy groups, polymers having desirable properties for various applications can be obtained. That is, by varying the ratio of the individual groups in accordance with the teachings of the documents showing the properties of the polymer, the sensitivity, thermal properties, mechanical properties, solubility inhibition in aqueous alkaline developers, etch resistance and hydrophilic / hydrophobicity balances are controlled. Can be.                     

The polyvinyl acetal polymers according to the invention whose solubility changes with heat in aqueous / alkaline developer can be prepared according to a novel synthesis method using cheap polymers used in large-scale techniques as starting materials. Starting materials for the preparation of the polymers according to the invention are vinyl acetate-vinyl alcohol copolymers containing at least 80% vinyl alcohol units and having an average molecular weight of at least about 2000 to 120000, preferably at about 8000 to 50000. The molecular weight is a number average or weight average molecular weight, and the exact molecular weight within this range is not critical to the practice of the present invention. Examples of suitable polyvinyl alcohols are the polyvinyl alcohols available under the trade names MOWIOL 3-83, MOWIOL 3-98, MOWIOL 4-88, etc. from Clariant GMBH, and the trade names AIRVOL 103, 203, 502, etc., from AIR PRODUCTS CORP. Polyvinyl alcohol.

Examples of suitable aldehydes for preparing the first cyclic acetal groups of the acetal polymers according to the present invention include propionaldehyde, n-butylaldehyde, n-valeraldehyde, n-caproaldehyde, n-heptaaldehyde, isobutylaldehyde, isovaleraldehyde , And mixtures thereof.

Examples of suitable aldehydes for preparing the second cyclic acetal groups of the acetal polymers according to the invention include 2-hydroxybenzaldehyde, 3-hydroxybenzaldehyde, 4-hydroxybenzaldehyde, 2-hydroxy-1-naphthaldehyde, 2,4-dihydroxybenzaldehyde, 3,5-dibromo-4-hydroxybenzaldehyde, 4-oxypropynyl-3-hydroxybenzaldehyde, vanillin, isovanillin, cinnamic aldehyde, and mixtures thereof. .

Examples of aldehydes useful for preparing the third acetal groups of the acetal polymers according to the invention include glyoxylic acid, 2-formylphenoxyacetic acid, 3-methoxy-4-formylphenoxy acid, propargyl aldehyde, and their Mixtures and the like.

Acetalization of the polyvinyl alcohols is described, for example, in US Pat. No. 4,665,124; 4,940,646; 5,169,898; 5,792,823; And known methods as described in Japanese Patent No. 09,328,529 and the like.

In general, such acetalization requires the addition of strong organic or inorganic catalytic acids. Examples of such catalytic acids are hydrochloric acid, sulfuric acid, phosphoric acid, or p-toluenesulfonic acid. In addition, strong acids such as perfluoroalkylsulfonic acid and other perfluoro-activated acids can be used. The catalyst can effectively cause protonation reactions, but should be used in an amount that does not significantly change the final product by causing unwanted hydrolysis of the acetal groups. The acetalization reaction temperature changes depending on the kind of acetal and the degree of substitution desired. The temperature of the boiling point of the solvent used from 0 degreeC can be used. Organic solvents and mixtures of these organic solvents with water are used. Examples of particularly suitable organic solvents are alcohols (eg methanol, ethanol, propanol, butanol, or glycol ethers), cyclic ethers (eg 1,4-dioxane) or dipolar aprotic solvents (eg N, N Dimethylformamide, N-methyl pyrrolidone or dimethyl sulfoxide). When the acetalization is carried out in an organic solvent or a mixture of the organic solvent and water, the reaction product remains in solution but the starting polyvinyl alcohol is not completely dissolved. Incomplete dissolution of the polyvinyl alcohol in organic solvents is a disadvantage that an unreproducible degree of conversion or different products can be obtained. Water or a mixture of water and organic solvent should be used to achieve complete dissolution and reproducible product of polyvinyl alcohol upon acetalization. The order of addition of the various acetalized materials is not critical and different preparation sequences can be used to obtain similar final products. To separate the final product into the solid state, the polymer solution is added to the nonsolvent with vigorous stirring, filtered and dried. As the non-solvent, water is particularly suitable.

The inventors of the present invention find that unwanted hydrolysis of acetal groups by acetalization with hydroxy-substituted aromatic aldehydes is much easier than with acetals obtained from aliphatic or unsubstituted aromatic aldehydes or from carboxy part containing aldehydes under the same synthetic conditions. It was confirmed. The presence of a small amount of water in the reaction mixture leads to reduced acetalization and incomplete conversion of aromatic hydroxy aldehydes. On the other hand, it was found that in the absence of water, the hydroxy-substituted aromatic aldehydes reacted immediately with the hydroxy groups of the alcohols to yield almost 100% conversion. Thus, the acetalization process of polyvinyl alcohol with hydroxy-substituted aromatic aldehydes to obtain the desired polyvinyl acetals according to the invention was carried out differently from known methods. The main difference of the present invention is the removal of water from the reaction mixture during synthesis. The main amount of water is removed by distillation under reduced pressure and replaced with an organic solvent. The inventors of the present invention have found that the water remaining in the reaction mixture can be removed by adding organic substances which react with it easily to produce volatile or inert compounds. Such materials may be selected from carbonates such as diethyl carbonate, trimethyl orthoformate, tetraethyl carbonate, detraethyl silicate, orthoesters of carbonic acid or carboxylic acid, silicon-containing compounds and the like. The addition of this material to the reaction mixture converts 100% of the aldehyde used, and to the inventors of the present invention, no water scavengers have been used in the preparation of conventional polymer acetals. Next Document [G. Saucy, R. Borer and D. P. Trullinger, J. Org. Chem., Vol. 42, No. 19, pp. 3206, 1977 mention the use of triethyl orthoformate in the synthesis of delta lactones. The process of the present invention for synthesizing polyvinyl acetal polymers involves the acetalization of polyvinyl alcohol using hydroxy-substituted aromatic aldehyde (s) and strong acid catalysts, followed by reaction with water to terminate the acetalization reaction and volatile And / or remove the water from the polyvinyl alcohol and hydroxy-substituted aromatic aldehyde (s) by adding a substance that produces an inert compound at a rate sufficient to effectively remove some of the water (reduce concentration, not complete removal). Thereby inhibiting hydrolysis of the acetal groups formed by the acetalization by reducing the amount of water present with the polyvinyl alcohol and the hydroxy-substituted aromatic aldehyde (s). For example, this method can use a material selected from the group consisting of organic carbonates, orthoesters of carbonic acid or carboxylic acid, and silicon-containing compounds as reactants with water. For example, the silicon-containing compound is selected from the group consisting of silicates and silanes such as orthosilicates, metasilicates, and ester group-containing silanes.

In the present invention, the preparation of the polymer begins with dissolving the starting polyvinyl alcohol in water at 80-90 ° C., cooling the solution to 60 ° C. and adding an acid catalyst dissolved in an organic solvent. Include. Solvents used in the present invention are alcohols or glycols, such as n-propanol, 2-methoxyethanol, or 1-methoxy 2-propanol (denoted as Dowanol ^TM PM, hereinafter "PM"). Next, a solution of the aromatic hydroxy-substituted aldehyde dissolved in the solvent is added, followed immediately by a solution of aliphatic aldehyde and / or carboxy substituted aldehyde or other aldehyde dissolved in the solvent and the reaction mixture is After reacting for 2 to 3 hours at temperature, the azeotropic mixture of water and organic solvent is removed by distillation and replaced with organic solvent. In this step, the conversion of aliphatic hydroxy is 95-98%. Next, the acid in the reaction mixture is neutralized and the mixture is combined with water to precipitate the polymer, and the polymer is filtered, washed with water and dried. A second method for 100% conversion of the aromatic formaldehyde to benzal is the addition of water-removing organic substances (eg carbonate, orthoformate, etc.) to the reaction mixture after addition of the aldehyde.

Suitable radiation absorbing materials for the thermosensitive composition of the present invention are selected from a wide range of organic and inorganic pigments such as carbon black, phthalocyanine or metal oxides. Examples of effective endothermic pigments include green pigments manufactured by BASF, namely Heliogen Green D8730, D9360, and Fanal Green D8330; Predisol 64H-CAB678, manufactured by Sun Chemicals; Black pigments, Predisol CAB2604, Predisol N1203, Predisol Black CB-C9558 manufactured by Sun Chemicals Corp. The amount of the pigment used in the composition is 3 to 20% by weight, preferably 3 to 7% by weight, based on the weight of the composition. Infrared absorbing dyes are preferred endothermic agents that can be used in the compositions of the present invention, which absorb wavelengths of 700 nm or more, such as about 700 to 1100 nm. Examples of such dyes are those manufactured by Epolin, Inc. and include Epolight IV-62A, IV-62B and IV-66X; ADS 830, ADS 835 and ADS 840, manufactured by American Dye Source Inc .; Hayashibara Biochemical Lab. NK-2911 and NK-4432 are manufactured by Inc., and the like. The amount of such infrared absorbing dye present in the composition is 0.1 to 5% by weight, preferably 0.1 to 1% by weight, based on the weight of the composition.

Because of the known affinity for copper of acetylene triple bond containing compounds (Jukes AE, Advanced in Organometallic Chemistry, Vol. 12, NY, 1974, pp. 215-322), the inventors of the present invention have described the compounds for copper surfaces. It was used as an adhesion promoter of the thermosensitive composition. To the knowledge of the present inventors, acetylene compounds have not been conventionally used for this purpose.

Adhesion promoters of the present invention include esters, sulfoesters, amides, polyesters, polycarbonates and polyurethanes containing the following triple or triple bond sequences:

R ₁ -XC (R ₃ , R ₄ ) -C≡CC (R ₃ , R ₄ ) -XR ₂ or R ₁ -XC (R ₃ , R ₄ ) -C≡CC (R ₃ , R ₄ ) -X -(Y) _m -XC (R ₃ , R ₄ ) -C≡CC (R ₃ , R ₄ ) -XR ₂ or R ₁ -XC (R ₃ , R ₄ ) -C≡CH. Wherein R ₁ and R ₂ are —C _n H _2n-1 , substituted aromatic or heterocyclic segments; R ₃ and R ₄ are H or alkyl; X is -OC (O)-, -OS (O)-, or -NH-C (O)-; Y is C _n H _2n-1 or substituted aromatic.

Such adhesion promoters are for example from propargyl alcohol or 2-butyne-1,4-diol, and suitable anhydrides of carboxy or sulfonic acids, or aliphatic or aromatic isocyanates or diisocyanates, or propargyl bromide or chloride or propargyl chloroform It can be obtained from the ate and a suitable polyol or by any other method known to those skilled in the art. 2-butyne-1,4-diol-di-chloroformate and the corresponding diols, i.e. triple bond from the HO-R-OH that, that - the _{n (CH 2 C≡C-CH 2} -OC (O) -ORO-) Polycarbonate containing it can be obtained. Wherein R is-(CH ₂ ) n where n = 2-6; -CH ₂ CH ₂ (OCH ₂ CH ₂ ) n where n = 1-4; -CH ₂ -CH = CH-CH _2- ; -CH ₂ -C≡C-CH ₂ ;

Or aromatic groups (e.g. = Ar = C ₆ H ₄ , -C ₁₀ H _6, etc.).

As can be seen from the above example, the acetylene bond may be present in the molecular structure or at the terminal of the molecule.

In addition, colorants, plasticizers, surfactants, additional metal adhesion promoters, labeling agents, other resin components, and the like may be added to the thermosensitive composition. Useful colorants include dyes well known in the resist and printing plate coatings, namely Methyl Violet, Ethyl Violet, Crystal Violet, Basic Sudan Black, Victoria Blue R, Methylene Blue, Nigrosine, and the like. The dye is preferably used in an amount of 0.01 to 2% by weight based on the weight of the thermosensitive composition. Useful coating aids include Zonyl's (DuPont) or fluorocarbon surfactants such as FC-430 or FC-431 (3M), or other anionic, cationic, nonionic surfactants, or mixtures thereof. The surfactant is preferably used in an amount of about 0.01 to 1% by weight based on the weight of the composition.

Examples of particularly useful plasticizers include Tweens (eg available from ICI), polyoxyalkylene plasticizers (eg polyethylene oxide / polypropylene oxide copolymers) and the like. Such plasticizers may be used in amounts of 0.1 to 15% by weight, based on the weight of the photosensitive polymer. Plasticizers are also known to promote the developability of the photosensitive polymer in the developing step.

In addition, fillers or extenders may be used in the compositions of the present invention, for example, to increase the solids content of the composition or to improve properties such as heat resistance or heat transmittance. The filler may be used to enhance the thickness of the coated thermally formable layer or to adjust the strength or physical properties of the layer. Such fillers are inert particles. Examples of particularly suitable inert fillers include starch, kaolin, titanium dioxide, silica, polytetrafluoroethylene, talc and the like.

The thermosensitive composition of the present invention is useful for the production of printed circuit boards, lithographic printing plates, and other thermosensitive members for laser scanning image forming. In addition, these thermosensitive compositions can provide high precision chemically ground metals. This use is due to good adhesion to a wide range of metals and alloys. In addition, additives can be added to improve the adhesion without adversely affecting the performance of the composition, the difference in solubility between the exposed and unexposed areas is obvious, and the etching resistance (especially for the widely used ferric chloride etchant) It is due to the fact that this is excellent and the residual composition is easy to peel off. Thus, the compositions can be used to make small medical parts such as stents and catheters using conventionally known methods of irradiation and development, such as in US Pat. No. 6,027,863.

In addition, the thermosensitive composition of the present invention may provide a thermally activated resist for use in the manufacture of a printing plate such as a gravure cylinder master. The composition of the present invention can exhibit excellent film forming properties, good adhesion to the gravure cylinder surface, and aqueous developability, and the rest of the composition can be easily removed after development and etching. In addition, the thermosensitive composition of the present invention may provide a screen printing stencil having high sensitivity to infrared laser light and excellent adhesion and peeling properties.

Suitable substrates include copper foil, inverted copper foil, drum side treated copper foil and double treated copper foil clad disposed on top of a plastic laminate used for the manufacture of a printed circuit board; And aluminum plates and sheets used in the manufacture of printing plates, and anodized aluminum plates and sheets. It is also possible to use substrates such as steel or polymers (eg, nylon, high density polyolefins, polycarbonates, polyacrylates, polyvinyl resins, etc.) to form screen printing stencils. In addition, chromium and copper substrates may be used to form gravure printing plates.

For the final treatment, a solution of the composition of the present invention dissolved in a suitable solvent is obtained, filtered to remove insoluble components, and known methods such as doctor blade, wire rod, spin coating, roller coating or dip coating, etc. are used. And apply in liquid state. The solvent used in the present invention is glycol ether, PM or 2-methoxyethanol. The solids content of the polymeric material in the solution varies with the desired dry thickness of the membrane, from 5 to 25% by weight.

Another application method is to coat and dry the thermosensitive composition on a suitable intermediate substrate (polyester or polyethylene) and then apply the film on the final substrate using hot press lamination.

After the applied coating is sufficiently dried, the printed substrate is exposed to light using a laser beam of CREO PLATESETTER 3244 to image. In the case of a printed circuit board, exposure is performed using a CREO DIAMOND 2028 imager. The exposed area is then developed using an alkali metal salt solution or a weak alkali hydroxide solution.

Hereinafter, the present invention will be described in more detail with reference to production examples and use examples.

Preparation Example 1

110 g of Mowiol ^TM 3-98 polyvinyl alcohol (98% hydrolyzed polyvinyl acetate with an average molecular weight of about 16000) was added to a closed reactor equipped with a water cooled condenser, dropping funnel and thermometer and containing 250 g of deionized water. did. With continued stirring, the mixture was heated to 90 ° C. for 1 hour to obtain a clear solution. The temperature was then adjusted to 60 ° C. and 3 g of concentrated sulfuric acid was added. A solution of 59.8 g of 4-hydroxybenzaldehyde and 1.4 g of 2,6-di-tert-butyl-4-methylphenol dissolved in 450 g of 2-methoxyethanol was added dropwise over 15 minutes. The reaction mixture was diluted in an additional 500 g of 2-methoxyethanol and 35.3 g of n-butylaldehyde dissolved in 500 g of 2-methoxyethanol were added dropwise. After the addition of the aldehyde was finished, the reaction was continued for 3 hours at 50 ° C. Water is distilled off from the reaction mixture and replaced with 2-methoxyethanol, with 0.3% or less water present in the solution. The reaction mixture was neutralized with sodium hydrogen carbonate to pH 7 ± 0.5 and then combined with 15 liters of water-ethanol (10: 1). The precipitated polymer was washed with water, filtered and dried in vacuo at 50 ° C.

178 g of polymer were obtained with a yield of 95.2% (calculated based on PVA) and 92% conversion of 4-hydroxybenzaldehyde. The structure of the polymer is consistent with Formula (1), wherein R ₁ group is derived from n-butylaldehyde, R ₂ group is derived from 4-hydroxybenzaldehyde, the value of m is 36 mol% and the value of n It was 37 mol%, the value of p was 2 mol%, and the value of q was 25 mol%. (Tg 63 ° C.).

Preparation Example 2

110 g of Mowiol ^TM 3-83 polyvinyl alcohol (83% hydrolyzed polyvinyl acetate with an average molecular weight of about 14000) was equipped with a water-cooled condenser, dropping funnel and thermometer and contained 110 g of deionized water and 110 g of methanol. Added to closed reactor. With continued stirring, the mixture was heated to 80 ° C. for 30 minutes to obtain a clear solution. The temperature was then adjusted to 60 ° C. and 3 g of concentrated sulfuric acid dissolved in 100 g of PM was added. A solution of 65 g of 3-hydroxybenzaldehyde and 1.4 g of 2,6-di-tert-butyl-4-methylphenol dissolved in 450 g of PM was added dropwise over 15 minutes. The reaction mixture was diluted with an additional 200 g of PM and 9.2 g of n-butylaldehyde dissolved in 200 g of PM was added dropwise. After the addition of the aldehyde was finished, the reaction was continued for 3 hours at 50 ° C. In this step, the conversion of the butylaldehyde was terminated, and the conversion rate of the 3-hydroxybenzaldehyde was close to 50%. 500 g of trimethyl orthoformate was added dropwise while stirring to the reaction mixture. After addition of the trimethyl orthoformate, the conversion of the 3-hydroxybenzaldehyde reached 100% (less than 0.1% water is present in the reaction mixture).

158 g of polymer were obtained in a yield of 96.8% (calculated based on PVA). The structure of the polymer is consistent with Formula (1), wherein R ₁ group is derived from n-butylaldehyde, R ₂ group is derived from 3-hydroxybenzaldehyde, the value of m is 12 mol%, the value of n It was 49 mol%, the value of p was 17 mol%, and the value of q was 22 mol%. (Tg 59 ° C.).

Preparation Example 3

110 g of Airvol ^™ 103 polyvinyl alcohol (98% hydrolyzed polyvinyl acetate with an average molecular weight of about 18000) was added to a closed reactor equipped with a water cooled condenser, dropping funnel and thermometer and containing 250 g of deionized water. With continued stirring, the mixture was heated to 90 ° C. for 1 hour to give a clear solution. The temperature was then adjusted to 60 ° C. and 3 g of concentrated sulfuric acid dissolved in 100 g of PM was added. A solution of 61 g of 2-hydroxybenzaldehyde (salicylaldehyde) and 1.4 g of 2,6-di-tert-butyl-4-methylphenol dissolved in 450 g of PM was added dropwise over 15 minutes. The reaction mixture was diluted with an additional 500 g of PM and 27 g of n-butylaldehyde dissolved in 500 g of PM was added dropwise. After the addition of the aldehyde was finished, the reaction was continued for 3 hours at 50 ° C. Water is distilled off from the reaction mixture and replaced with PM (wherein 10 g (1.5% or less) of water are present in the solution). 100 g of triethyl orthoformate was added to the reaction mixture with stirring. At this time, 0.1% water was identified in the reaction mixture, and the conversion rate of the salicylic aldehyde to benzal was quantitative. The reaction mixture was neutralized with sodium hydrogen carbonate to pH 7 ± 0.5 and then combined with 15 liters of water-ethanol (10: 1). The precipitated polymer was washed with water, filtered and dried in vacuo at 50 ° C.

185.8 g of polymer were obtained with a yield of 97.6% (calculated based on PVA) and a 2-hydroxybenzaldehyde conversion of 100%. The structure of the polymer is consistent with Formula (1), wherein R ₁ group is derived from n-butylaldehyde, R ₂ group is derived from 2-hydroxybenzaldehyde, R ₃ group is derived from glyoxylic acid, and the value of m Is 30 mol%, the value of n is 41 mol%, the value of p is 2 mol%, and the value of q is 20 mol%. (Tg 68 ° C.).

Preparation Example 4

110 g of Airvol ^TM 502 polyvinyl alcohol (88% hydrolyzed polyvinyl acetate with an average molecular weight of about 16000) was equipped with a water-cooled condenser, dropping funnel and thermometer and contained a closed reactor containing 110 g of deionized water and 110 g of methanol. Added to. With continued stirring, the mixture was heated to 90 ° C. for 1 hour to give a clear solution. The temperature was then adjusted to 60 ° C. and 3 g of concentrated sulfuric acid dissolved in 100 g of PM was added. A solution of 61 g of 3-hydroxybenzaldehyde and 1.4 g of 2,6-di-tert-butyl-4-methylphenol dissolved in 450 g of PM was added dropwise over 15 minutes. The reaction mixture was diluted with an additional 200 g of PM and 18.2 g of n-butylaldehyde and 8.1 g of propargyl aldehyde dissolved in 500 g of PM were added dropwise. After the addition of the aldehyde was finished, the reaction was continued for 3 hours at 50 ° C. Water was distilled off from the reaction mixture and replaced with PM. At this time, 0.2% water was identified in the reaction mixture, and the conversion of m-hydroxybenzaldehyde to benzal was quantitative. The reaction mixture was neutralized with sodium hydrogen carbonate to pH 7 ± 0.5 and then combined with 15 liters of water-ethanol (10: 1). The precipitated polymer was washed with water, filtered and dried in vacuo at 50 ° C.

177.8 g of polymer were obtained with a yield of 97.6% (calculated based on PVA) and an m-hydroxybenzaldehyde conversion of 100%. The structure of the polymer is consistent with Formula (1), wherein R ₁ group is derived from n-butylaldehyde, R ₂ group is derived from 3-hydroxybenzaldehyde, R ₃ group is derived from propargyl aldehyde, and the value of m Is 21 mol%, the value of n is 43 mol%, the value of p is 2 mol%, the value of o is 10 mol% and the value of q is 24 mol%. (Tg 65 ° C.).

Preparation Example 5

110 g of Airvol ^™ 103 polyvinyl alcohol (98% hydrolyzed polyvinyl acetate with an average molecular weight of about 18000) was added to a closed reactor equipped with a water cooled condenser, dropping funnel and thermometer and containing 250 g of deionized water. With continued stirring, the mixture was heated to 90 ° C. for 1 hour to give a clear solution. The temperature was then adjusted to 60 ° C. and 3 g of concentrated sulfuric acid dissolved in 100 g of PM was added. 33 g 2-hydroxybenzaldehyde (salicyl aldehyde) dissolved in 450 g PM, 38 g 3-methoxy-4-hydroxybenzaldehyde (vanillin) and 1.4 g 2,6-di-tert-butyl-4 A solution of methylphenol was added dropwise over 15 minutes. The reaction mixture was diluted with an additional 200 g of PM and 35.3 g of n-butylaldehyde dissolved in 500 g of PM was added dropwise. After the addition of the aldehyde was finished, the reaction was continued for 3 hours at 50 ° C. Water was distilled off from the reaction mixture and replaced with PM (at which time 15 g (2% or less) of water was present in the solution). 80 g of trimethyl orthoformate was added to the reaction mixture with stirring. At this time, 0.1% of water was identified in the reaction mixture, and the conversion rate of the salicylic aldehyde and vanillin to benzal was quantitative. The reaction mixture was neutralized with sodium hydrogen carbonate to pH 7 ± 0.5 and then combined with 15 liters of water-ethanol (10: 1). The precipitated polymer was washed with water, filtered and dried in vacuo at 50 ° C.

186 g of polymer were obtained with 94% yield (calculated based on PVA) and salicylic aldehyde and vanillin conversion of 100%. The structure of the polymer is consistent with Formula (1), wherein the R ₁ group is derived from n-butylaldehyde, the R ₂ group is derived from a 1: 1 mixture of 2-hydroxybenzaldehyde and vanillin, and the value of m is 38 moles. %, The value of n was 42 mol%, the value of p was 2 mol%, and the value of q was 18 mol%. (Tg 71 ° C.).

Preparation Example 6

110 g of Airvol ^TM 203 polyvinyl alcohol (88% hydrolyzed polyvinyl acetate with an average molecular weight of about 18000) was fitted with a water-cooled condenser, dropping funnel and thermometer and contained 110 g deionized water and 110 g methanol Added to. With continued stirring, the mixture was heated to 80 ° C. for 1 hour to give a clear solution. The temperature was then adjusted to 60 ° C. and 3 g of concentrated sulfuric acid dissolved in 100 g of PM was added. A solution of 32 g 4-hydroxybenzaldehyde, 30 g 2-hydroxy-1-naphthaldehyde and 1.4 g 2,6-di-tert-butyl-4-methylphenol dissolved in 500 g of PM was added for 15 minutes. I fell over. The reaction mixture was diluted with an additional 200 g of PM and 21.4 g of n-butylaldehyde dissolved in 500 g of PM was added dropwise. After the addition of the aldehyde was finished, the reaction was continued for 3 hours at 50 ° C. Water was distilled off from the reaction mixture and replaced with PM. At this time, 0.21% of water was identified in the reaction mixture, and the conversion rate of the aromatic aldehyde to benzal was quantitative. The reaction mixture was neutralized with sodium hydrogen carbonate to pH 7 ± 0.5 and then combined with 15 liters of water-ethanol (10: 1). The precipitated polymer was washed with water, filtered and dried in vacuo at 50 ° C.

170 g of polymer were obtained in 96% yield (calculated based on PVA) and 100% 4-hydroxybenzaldehyde and 2-hydroxy-1-naphthaldehyde conversion. The structure of the polymer is consistent with formula (1), wherein R ₁ group is derived from n-butylaldehyde, R ₂ group is derived from a mixture of 4-hydroxybenzaldehyde and 2-hydroxy- ₁ -naphthaldehyde, The value of m was 25 mol%, the value of n was 38 mol%, the value of p was 12 mol%, and the value of q was 26 mol%. (Tg 74 ° C.).

Preparation Example 7

120 g of Airvol ^TM 502 polyvinyl alcohol (88% hydrolyzed polyvinyl acetate with an average molecular weight of about 16000) was equipped with a water-cooled condenser, dropping funnel and thermometer and contained a closed reactor containing 110 g of deionized water and 110 g of methanol. Added to. With continued stirring, the mixture was heated to 90 ° C. for 1 hour to give a clear solution. The temperature was then adjusted to 60 ° C. and 12.4 g of concentrated hydrochloric acid dissolved in 100 g of PM was added. A solution of 40.3 g of formylphenoxyacetic acid, 30.8 g of 2-hydroxybenzaldehyde and 1.5 g of 2,6-di-tert-butyl-4-methylphenol dissolved in 750 g of PM was added dropwise over 30 minutes. did. The reaction mixture was diluted with an additional 200 g of PM and 34.2 g of isovaleraldehyde dissolved in 500 g of PM was added dropwise. After the addition of the aldehyde was finished, the reaction was continued for 3 hours at 50 ° C. Water was distilled off from the reaction mixture and replaced with PM. At this time, less than 0.1% of water was identified in the reaction mixture, and the conversion rate of the 2-hydroxybenzaldehyde and 4-formylphenoxyacetic acid into benzal is quantitative. The reaction mixture was neutralized to pH 7 ± 0.5 with ammonium carbonate and then combined with 15 liters of water-ethanol (10: 1). The precipitated polymer was washed with water, filtered and dried in vacuo at 50 ° C.

194 g of polymer were obtained in a yield of 92.6% (calculated based on PVA). The structure of the polymer is consistent with Formula (1), wherein R ₁ group is derived from isovaleraldehyde, R ₂ group is derived from 2-hydroxybenzaldehyde, R ₃ group is derived from 4-formylphenoxyacetic acid, The value of m was 16 mol%, the value of n was 10 mol%, the value of p was 12 mol%, the value of o was 18 mol%, and the value of q was 44 mol%. (Tg 65 ° C.).

Preparation Example 8

Add 110 g of Mowiol ^TM 3-98 polyvinyl alcohol (98% hydrolyzed polyvinyl acetate with an average molecular weight of about 16000) to a closed reactor equipped with a water cooled condenser, dropping funnel and thermometer and containing 250 g of deionized water. did. With continued stirring, the mixture was heated to 90 ° C. for 1 hour to give a clear solution. Next, the temperature was adjusted to 60 ° C. and 6 g of p-toluenesulfonic acid was added. A solution of 152 g of 3,5-dibromo-4-hydroxybenzaldehyde and 1.4 g of 2,6-di-tert-butyl-4-methylphenol dissolved in 750 g of PM was added dropwise over 15 minutes. The reaction mixture was diluted with an additional 500 g of PM and 12.3 g of n-butylaldehyde dissolved in 500 g of PM was added dropwise. After the addition of the aldehyde was finished, the reaction was continued for 3 hours at 50 ° C. Water was distilled off from the reaction mixture and replaced with PM (up to 1% water was present in the solution). 100 g of triethyl orthoformate was added to the reaction mixture. At this time, less than 0.1% of water was detected in the reaction mixture, and the conversion rate of 3,5-dibromo-4-hydroxybenzaldehyde was quantitative. The reaction mixture was neutralized with sodium hydrogen carbonate to pH 7 ± 0.5 and then combined with 15 liters of water-ethanol (10: 1). The precipitated polymer was washed with water, filtered and dried in vacuo at 50 ° C.

248 g of polymer were obtained in a yield of 95.2% (calculated based on PVA). The structure of the polymer is consistent with Formula (1), wherein R ₁ group is derived from n-butylaldehyde, R ₂ group is derived from 3,5-dibromo-4-hydroxybenzaldehyde, and the value of m is 14 Mol%, the value of n was 44 mol%, the value of p was 2 mol%, and the value of q was 40 mol%. (Tg 73 ° C.).

Example 1

The polymer of Preparation Example 1 was dissolved in PM to prepare a thermosensitive composition having the composition of Table 1 below.

ingredient weight% Acetal Polymer 1 13.2 Pigment (Predisol ^TM N1203 *) 0.8 Surfactants 0.05 Dowanol ^TM 85.95

*: Sun Chemicals

The composition was ball milled for 12 hours, filtered and coated onto a 0.5 oz. Clean and microetched plain copper clad surface placed on an 8 mil glass-epoxy laminate. After drying at 130 ° C. for 3 minutes, the resulting plate has a coating of 5.5 g / m ² dry thickness. The plate was imaged in a Cero Diamond ^™ 2028F imager. The energy density required to obtain a very good phase was 200 mJ / cm ² . The plate was developed for 60 seconds in 5% sodium metasilicate dissolved in water to obtain a phase with a line to space ratio of 2 mils. The developed plate was etched using a conventional copper chloride etching solution to obtain a printed circuit having a sharp edge of the conductor and a line-to-space ratio of 2 mils.

Example 2

The polymer of Preparation Example 2 was dissolved in Dowanol ^™ PM and used to prepare a thermosensitive composition having the composition of Table 2 below:

ingredient weight% Acetal Polymer 2 16.0 Adhesion Promoter-1,3,5-tris [propargyloxycarbonyl] benzene 0.05 Pigment Heliogen Green D-8330 * One Surfactants 0.05 Dowanol ^TM PM 82.9

*: BASF

The composition was ball milled for 12 hours, filtered and coated onto a 1 oz. Prewashed and inverted copper clad surface disposed on a 20 mil glass-epoxy laminate. After drying at 130 ° C. for 4 minutes, the resulting plate has a coating of 9.5 g / m ² dry thickness. The plate was imaged in a Cero Diamond ^™ 2028F imager. The energy density required to obtain a very good phase was 300 mJ / cm ² . The plate was developed for 50 seconds in a 0.75% sodium hydroxide solution dissolved in water to obtain a phase with a line to space ratio of 2 mils. The developed plate was etched using a conventional copper chloride etching solution to obtain a printed circuit having a sharp edge of the conductor and a line-to-space ratio of 2 mils.

Example 3

The polymer of Preparation Example 3 was dissolved in Dowanol ^™ PM and used to prepare a thermosensitive composition having the composition of Table 3 below:

ingredient weight% Acetal Polymer 3 15.0 Adhesion Promoter-2,4,6-tris (2-propynyloxy) -1,3,5-triazine 0.03 IR Dye-NK 2911 * 0.08 Colorant-Methylene Blue 0.05 Surfactants 0.05 Dowanol ^TM PM 84.57

*: Hayashibara Biochemical Lab. Inc.

The components of the composition were dissolved in PM, filtered and coated onto a 0.25 oz. Prewashed and microetched copper clad surface disposed on an 8 mil glass-epoxy laminate. After drying at 130 ° C. for 3 minutes, the resulting plate has a coating of 6.5 g / m ² dry thickness. The plate was imaged in a Cero Diamond ^™ 2028F imager. The energy density required to obtain a very good phase was 250 mJ / cm ² . The plate was developed for 60 seconds in a 0.9% sodium hydroxide solution dissolved in water to give a phase with a line to space ratio of 0.75 mil. The developed plate was etched using a normal alkaline etching solution to obtain a printed circuit having a sharp edge of the conductor and a line-to-space ratio of 0.75 mils.

Example 4

The polymer of Preparation Example 4 was dissolved in PM to prepare a thermosensitive composition having the composition of Table 4 below.

ingredient weight% Acetal Polymer 4 16.0 IR Dye-NK4432 * 0.1 Surfactants 0.05 Colorant-Crystal Violet 0.05 Dowanol ^TM PM 83.8

*: Hayashibara Biochemical Lab. Inc.

The components of the composition were dissolved in PM, filtered and coated onto a 0.5 oz. Of unwashed copper clad surface disposed on a 12 mil glass-epoxy laminate. After drying at 130 ° C. for 3 minutes, the resulting plate has a coating of 6 g / m ² dry thickness. The plate was imaged in a Cero Diamond ^™ 2028F imager. The energy density required to obtain a very good phase was 250 mJ / cm ² . The plate was developed for 60 seconds in a 0.7% sodium hydroxide solution dissolved in water to obtain a phase with a line-to-space ratio of 1 mil. The developed plate was etched using a conventional copper chloride etching solution to obtain a printed circuit having a sharp edge of the conductor and a line-to-space ratio of 1 mil.

Example 5

The polymer of Preparation Example 4 was dissolved in Dowanol ^™ PM and used to prepare a thermosensitive composition having the composition of Table 5 below:

ingredient weight% Acetal Polymer 4 15.0 Polyvinylacetate-Crotonic Acid ** 3 IR Dye-NK2911 * 0.08 Colorant-Crystal Violet 0.05 Surfactants 0.05 Dowanol ^TM PM 81.82

*: Hayashibara Biochemical Lab. Inc.

**: Aldrich

The components of the composition were dissolved in PM, filtered and coated onto a 0.5 oz. Of unwashed copper clad surface disposed on a 12 mil glass-epoxy laminate. After drying at 130 ° C. for 4 minutes, the resulting plate has a coating of 9.5 g / m ² dry thickness. The plate was imaged in a Cero Diamond ^™ 2028F imager. The energy density required to obtain a very good phase was 300 mJ / cm ² . The plate was developed for 60 seconds in a 0.75% sodium hydroxide solution dissolved in water to obtain a phase with a line-to-space ratio of 1 mil. The developed plate was etched using a conventional copper chloride etching solution to obtain a printed circuit having a sharp edge of the conductor and a line-to-space ratio of 1 mil.

Example 6

The composition was prepared using the same composition and preparation as in Use Example 5, except that the polymethylmethacrylate-methacrylic acid copolymer (Aldrich) was used instead of the polyvinyl-crotonic acid. After drying at 130 ° C. for 4 minutes, the resulting plate has a coating of 9.5 g / m ² dry thickness. The plate was imaged in a Cero Diamond ^™ 2028F imager. The energy density required to obtain a very good phase was 250 mJ / cm ² . The plate was developed for 60 seconds in a 0.8% sodium hydroxide solution dissolved in water to obtain a phase with a line-to-space ratio of 1 mil. The developed plate was etched using a normal alkaline etching solution to obtain a printed circuit having a sharp edge of the conductor and a line-to-space ratio of 1 mil.

Example 7

The polymer of Preparation Example 4 was dissolved in Dowanol ^™ PM and used to prepare a thermosensitive composition having the composition of Table 6 below:

ingredient weight% Acetal Polymer 4 20.0 IR Dye-ADS 830 * 0.1 Colorant-Crystal Violet 0.2 Surfactants 0.05 Dowanol ^TM PM 79.65

*: American Dye Source Inc.                     

The solution was coated on a 1 mil thick corona treated polyester liner and dried at 120 ° C. for 5 minutes. The coating dry thickness of the obtained resist film is 12 microns. The membranes were hot laminated (rollers heated to 100 ° C.) on an unprecleaned 0.5 oz. Drum-side treated copper clad surface disposed on an 8 mil glass-epoxy laminate. The polyester cover was removed and the plate was imaged in a Cero Diamond ^™ 2028F image forming apparatus. The energy density required to obtain a very good phase was 300 mJ / cm ² . The plate was developed for 60 seconds in a 0.9% sodium hydroxide solution dissolved in water to obtain a phase with a line to space ratio of 1 mil. The developed plate was etched using a common copper chloride etching solution to obtain a printed circuit having a sharp edge of the conductor and a line-to-space ratio of 1 mil. No signs of adhesion failure were identified.

Example 8

The polymer of Preparation Example 5 was dissolved in PM to prepare a thermosensitive composition having the composition of Table 7 below.

ingredient weight% Acetal Polymer 5 15.0 Adhesion Promoter-Polyurethane * 0.35 IR Dye-NK2911 ** 0.08 Colorant-Methylene Blue 0.05 Surfactants 0.05 Dowanol ^TM PM 84.57

**: Hayashibara Biochemical Lab. Inc.                     

*: Polyurethane derived from 43 g 2-butyne-1,4-diol and 58 g oligomeric diphenylmethane diisocyanate (Bayer) in the presence of 0.12 g dibutyltin dilaurate in THF solution.

The components of the composition were dissolved in PM, filtered and coated onto a 0.5 oz. Pumice cleaned copper clad surface disposed on a 20 mil glass-epoxy laminate. After drying at 130 ° C. for 4 minutes, the resulting plate has a coating of 8 g / m ² dry thickness. The plate was imaged in a Cero Diamond ^™ 2028F imager. The energy density required to obtain a very good phase was 250 mJ / cm ² . The plate was developed for 60 seconds in a 2% sodium metasilicate solution dissolved in water to obtain a phase with a line to space ratio of 1 mil. The developed plate was etched using a normal alkaline etching solution to obtain a printed circuit having a sharp edge of the conductor and a line-to-space ratio of 1 mil.

Example 9

The polymer of Preparation Example 7 was dissolved in PM to prepare a thermosensitive composition having the composition of Table 8 below.

ingredient weight% Acetal Polymer 7 18.0 Adhesion Promoter-2,4,6-tris (2-propynyloxy) -1,3,5-triazine 0.02 IR Dye-ADS 830 * 0.08 Colorant-Methylene Blue 0.05 Surfactants 0.05 Dowanol ^TM PM 81.8

*: American Dye Source, Inc.

The components of the composition were dissolved in PM, filtered and coated onto a 0.5 oz. Pumice cleaned copper clad surface disposed on a 20 mil glass-epoxy laminate. After drying at 130 ° C. for 3 minutes, the resulting plate has a coating of 5 g / m ² dry thickness. The plate was imaged in a Cero Diamond ^™ 2028F imager. The energy density required to obtain a very good phase was 200 mJ / cm ² . The plate was developed for 40 seconds in a 2% sodium metasilicate solution dissolved in water to obtain a phase with a line to space ratio of 1 mil. The developed plate was etched using a normal alkaline etching solution to obtain a printed circuit having a sharp edge of the conductor and a line-to-space ratio of 1 mil.

Example 10

The polymer of Preparation Example 8 was dissolved in PM to prepare a thermosensitive composition having the composition of Table 9 below.

ingredient weight% Acetal Polymer 8 12.8 Adhesion Promoter-2,4,6-tris (2-propynyloxy) -1,3,5-triazine 0.03 IR Dye-ADS 830 * 0.05 Colorant-Crystal Violet 0.05 Surfactants 0.05 Dowanol ^TM PM 87.02

*: American Dye Source, Inc.

The components of the composition were dissolved in PM, filtered and coated onto a 0.5 oz. Precleaned drum-side treated copper clad surface disposed on a 12 mil glass-epoxy laminate. After drying at 130 ° C. for 3 minutes, the resulting plate has a coating of 9.5 g / m ² dry thickness. The plate was imaged in a Cero Diamond ^™ 2028F imager. The energy density required to obtain a very good phase was 300 mJ / cm ² . The plates were washed with hot water (45 ° C.) while developing for 60 seconds in a 2% sodium carbonate solution dissolved in water to give a phase with a line to space ratio of 1 mil. The developed plate was etched using a conventional acidic copper chloride etchant to obtain a printed circuit having a sharp edge of the conductor and a line-to-space ratio of 1 mil.

Use Example 11

The polymer of Preparation Example 6 was dissolved in Dowanol ^™ PM and used to prepare a thermosensitive composition having the composition of Table 10 below:

ingredient weight% Acetal Polymer 6 12.0 IR Dye-ADS 830 * 0.12 Colorant-Crystal Violet 0.05 Surfactants 0.03 Dowanol ^TM PM 87.8

*: American Dye Source Inc.

The solution of the composition was dissolved in PM, filtered and then coated on the anodized aluminum surface. After drying at 130 ° C. for 3 minutes, the resulting plate has a coating of 2.5 g / m ² dry thickness. The plate was imaged in a Cero Platesetter 3244 phase forming apparatus. The energy density required to obtain a very good phase was 250 mJ / cm ² . The plate was imaged in a Cero Diamond ^™ 2028F imager. The energy density required to obtain a very good image was 300 mJ / cm ² . The plates were developed for 80 seconds in 5.5% sodium metasilicate solution dissolved in water, washed with water and dried. The printing plate was printed 100,000 times using a sheet feed press and commercially available process black ink. No wear on the top was observed. Highlight dots of 150 lines / inch screen could be allowed.

As described above, the thermosensitive composition containing the polymer of the present invention provides a lithographic printing plate characterized by improved wear resistance and extended compression performance. In addition, such compositions have an important advantage in that they can be treated in an alkaline aqueous solution containing no organic solvent.                     

In addition, the thermosensitive composition containing the polymer of the present invention has excellent film forming properties and improved adhesion, which can provide a resist film free of defects at low thickness and low cost, and has a solubility between the irradiated and the exposed areas. Since the difference is excellent, the etching resistance to the acidic or alkaline etching solution and the strippability in the alkaline aqueous solution are excellent, a high density printed circuit board having high resolution is provided.

In addition, since the compositions of the present invention have optimized thermal and mechanical properties, the advantage is that they can be applied in a liquid state or laminated in a dry monolayer on a substrate for the production of a printed circuit board.

Another advantage of the compositions of the present invention is the ability to form films with improved adhesion and good mechanical properties to substrates such as anodized aluminum for printed circuit board manufacture and copper clads for printed circuit board manufacture. Still another advantage of the present invention is that the composition can be applied in a liquid state or as a dry film using hot roller lamination.

In addition, another advantage of the thermosensitive composition of the present invention is that the solubility difference between the exposed and unexposed areas in the developer using an aqueous developer that does not contain an organic solvent is obvious. And because of the insensitivity of the composition to white light, the coated product can be handled in white light.

In the above, the present invention has been described in detail with reference to preferred embodiments, it can be seen that various changes and modifications can be made within the spirit and scope of the invention.

Claims (16)

A positive acting resist element comprising a metal underlayer, an alloy underlayer or a printing plate comprising a substrate having one or more metal surfaces to which a positive-acting resist layer is attached, wherein the positive acting resist layer comprises: A positive acting resist member containing from 0.01 to 20% by weight of an infrared absorbing material based on the weight of the acetal polymer of formula (1) and the positive acting resist layer: [Formula 1]

In which R ₁ is —C _n H _{2n + 1} , wherein n = 1-12; R ₂ is represented by the following formula (2) or formula (3), [Formula 2]

[Formula 3]

In formulas (2) and (3), R ₄ is -OH, R ₅ is -OH or -OCH ₃ or Br or O-CH ₂ -C≡CH, R ₆ is Br or NO ₂ , In formula (1), R ₃ is-(CH ₂ ) ₃ -COOH, -C≡CH, or

R ₇ is COOH, — (CH ₂ ) ₃ —COOH, or —O— (CH ₂ ) ₃ —COOH, m is 5-40 mol%, n is 10-60 mol%, o is 0-20 mol%, p is 2-20 mol% and q is 5-50 mol%. The method of claim 1, wherein the positive action resist layer, An acetal polymer comprising 5-40% by molar aliphatic acetal group and 10-60% by mole phenolic acetal group, A positive acting resist member comprising 0.01 to 20% by weight of an infrared absorbing material based on the weight of the positive acting resist layer. The positive acting resist member according to claim 1 or 2, wherein the metal is selected from the group consisting of chromium, aluminum and copper. The positive acting resist according to claim 1 or 2, wherein the metal is selected from the group consisting of aluminum and copper, and the positive acting resist layer contains a compound having an acetylene bond in an amount that promotes adhesion. absence. The positive acting resist member of claim 1 or 2, wherein at least one hanging group in the acetal polymer has an acetylene bond containing group. 3. The positive acting resist member of claim 1 or 2 wherein the infrared absorbing material comprises an infrared absorbing pigment. 3. The positive acting resist member of claim 1 or 2 wherein the infrared absorbing material comprises an infrared absorbing dye. The positive acting resist member according to claim 1 or 2, wherein the positive acting resist layer is free of a photosensitive compound that changes developability upon irradiation with ultraviolet or visible light. 3. The positive acting resist member of claim 1 or 2, wherein the positive acting resist layer has an average thickness of 1 to 30 micrometers. A positive-acting thermal resist element comprising a copper-containing substrate having one or more surfaces to which a positive-acting dermal resist layer is attached, The positive acting resist layer has a thickness of 1-30 micrometers a) an acetal polymer comprising 5-40% (molar basis) of aliphatic acetal groups and 10-60% (molar basis) of phenolic acetal groups, b) a positive acting dermal resist member comprising 0.01-20% by weight of an infrared absorbing material based on the weight of said positive acting resist layer. A resist member having a peelable support having one or more surfaces removably attached to a positive acting dermal resist layer and capable of being stacked in the form of a dry film, The positive acting resist layer has a thickness of 3 to 50 micrometers, An acetal polymer comprising 5-40% by molar aliphatic acetal group and 10-60% by mole phenolic acetal group, A resist member comprising 0.01-20% by weight of an infrared absorbing material based on the weight of the positive acting resist layer. A method for synthesizing the polyvinyl acetal polymer of claim 1, a) polyvinyl alcohol resin is acetalized using hydroxy-substituted aromatic aldehyde (s) and a strong acid catalyst, Prior to terminating the acetalization reaction, the amount of water present in the polyvinyl alcohol and hydroxy-substituted aromatic aldehyde (s) by distilling off water from the polyvinyl alcohol and hydroxy-substituted aromatic aldehyde (s). Reducing the amount of hydrolysis of the acetal group formed by the acetalization reaction with the hydroxy substituted aromatic aldehyde (s), or b) acetalization of the polyvinyl alcohol resin with hydroxy-substituted aromatic aldehyde (s) and strong acid catalyst, Prior to terminating the acetalization reaction, water is removed from the polyvinyl alcohol and hydroxy-substituted aromatic aldehyde (s) by adding a substance that reacts with water to produce a volatile, inert, or volatile and inert compound. Reducing the amount of water present in the polyvinyl alcohol and the hydroxy-substituted aromatic aldehyde (s) by inhibiting the amount of hydrolysis of the acetal groups formed by the acetalization reaction with the hydroxy substituted aromatic aldehyde (s). How to. 13. The method of claim 12, wherein the material that reacts with water is selected from the group consisting of organic carbonates, orthoesters of carbonic acid or carboxylic acids, and silicon-containing compounds. A method of directly forming an image forming pattern on a surface of a printing plate, comprising the step of forming a printing plate comprising the positive action resist layer of claim 1, a) injecting a sufficient intensity of energy focused light rays into selected areas of the positive acting resist layer to change the solubility of the composition forming the positive acting resist layer by heat; b) contacting the positive acting resist layer with a developer effective to remove the irradiated area of the energy focused light beam. The method of claim 14, wherein the substrate surface comprises copper or aluminum. 15. The method of claim 14, wherein the composition forming the positive acting resist layer further contains a compound containing an acetylene bond in an amount that promotes adhesion.