KR20240002672A - Photosensitive resin composition, flexographic printing original plate, flexographic printing plate, method for producing cured product, method for producing flexographic printing plate, and printing method - Google Patents

Abstract

[Problem] To provide a photosensitive resin composition capable of producing a flexographic printing plate that has both excellent solvent resistance and flexibility at a high level.
[Solution] A photosensitive resin composition in which the cured product of light containing a wavelength of 360 nm satisfies the following <Condition 1> and <Condition 2>:
<Condition 1>
At 23°C, the elongation at break when a dumbbell-shaped test piece with a measuring portion of 1 mm in thickness, 30 mm in length, and 3 mm in width was tensile tested at a speed of 500 mm/min was 250% or more.
<Condition 2>
The mass increase rate when immersed in N-methyl-2-pyrrolidone (NMP) or γ-butyrolactone (GBL) for 24 hours is 25% by mass or less.

Description

Photosensitive resin composition, flexographic printing original plate, flexographic printing plate, manufacturing method of cured product, manufacturing method of flexographic printing plate, and printing method PRODUCING FLEXOGRAPHIC PRINTING PLATE, AND PRINTING METHOD}

The present invention relates to a photosensitive resin composition, a flexographic printing plate, a flexographic printing plate, a method for producing a cured product, a method for producing a flexographic printing plate, and a printing method.

Flexo printing using a flexo printing plate using a photosensitive resin composition exhibits excellent printing characteristics on uneven paper, non-woven fabric, and plastic films with high smoothness, so it is widely used in various industries such as cardboard printing and food packaging printing. (e.g., see Patent Documents 1 and 2).

In addition, since flexographic printing plates have a high degree of flexibility, they have recently been developed for printing on surfaces such as alkali-free glass plates for liquid crystals and semiconductor wafers where scratches cannot be tolerated.

In particular, for printing plates for printing on alkali-free glass plates for liquid crystals, and specifically for flexographic printing plates used for alignment film printing, large-sized plates and high precision of plate thickness and plate surface patterns within large sizes are required. It is becoming true.

The alignment film formed on the alkali-free glass plate for liquid crystals is made of an alignment film varnish in which polyimide or its precursor, polyamic acid, is dissolved in a polar solvent such as N-methyl-2-pyrrolidone (NMP) or γ-butyrolactone. It is obtained by printing using a flexo printing plate.

However, the polar solvent used to form the alignment film varnish swells the flexographic printing plate, and in order to achieve high printing quality (plate thickness precision and high precision of the plate surface pattern), the photosensitive solvent used to form the flexographic printing plate is used. There is a need to improve the solvent resistance of the resin composition.

In general, the photosensitive resin composition forming the flexo printing plate is a crosslinkable polymer, and thus the solvent resistance of the photosensitive resin composition has been improved conventionally by improving the crosslinking density.

However, when the crosslinking density of the photosensitive resin composition is improved, the flexibility of the final flexographic printing plate is impaired, and the elongation and toughness, which are durability indicators of the flexographic printing plate, tend to decrease. I have it. In the case of a flexographic printing plate, a single breakage causes total damage to the flexographic printing plate, so a larger flexographic printing plate requires durability greater than that of a small flexographic printing plate.

For example, Patent Documents 3 and 4 disclose technology related to a flexographic printing plate with improved solvent resistance.

However, there is a problem in that the printing quality required for large-sized flexographic printing plates, such as high precision in plate thickness and plate surface pattern, and solvent resistance are still insufficient, and there is room for improvement.

Patent Document 1: Japanese Patent Publication No. 11-92659 Patent Document 2: Japanese Patent Publication No. 2004-148309 Patent Document 3: Japanese Patent No. 3835867 Patent Document 4: Japanese Patent No. 5206434

As described above, a technology for improving solvent resistance by improving the crosslinking density of the photosensitive resin composition has been proposed in the past to improve printing quality, but this results in the loss of flexibility of the photosensitive resin composition and the durability of the flexo printing plate. There was a problem of deterioration.

Therefore, the purpose of the present invention is to provide a photosensitive resin composition that can produce a flexographic printing plate that has both excellent solvent resistance (low swelling) and flexibility (elongation, toughness) at a high level.

As a result of repeated intensive studies to solve the above-mentioned problems, the present inventors found that a photosensitive resin composition having predetermined physical properties can solve the above-mentioned problems, and completed the present invention.

That is, the present invention is as follows.

[One]

A photosensitive resin composition in which the cured product of light containing a wavelength of 360 nm satisfies the following <Condition 1> and <Condition 2>:

<Condition 1>

At 23°C, the elongation at break when a dumbbell-shaped test piece with a measuring portion of 1 mm in thickness, 30 mm in length, and 3 mm in width was tensile tested at a speed of 500 mm/min was 250% or more.

<Condition 2>

The mass increase rate when immersed in N-methyl-2-pyrrolidone (NMP) or γ-butyrolactone for 24 hours is 25% by mass or less.

[2]

The photosensitive resin composition according to [1], wherein the photosensitive resin composition contains a polyurethane prepolymer.

[3]

The photosensitive resin composition according to [2], wherein the polyurethane prepolymer has a hydrogenated polybutadiene structure.

[4]

With equipment,

The photosensitive resin composition according to any one of [1] to [3] above.

A flexographic printing plate having a .

[5]

With equipment,

A cured product of the photosensitive resin composition according to any one of [1] to [3] above with light containing a wavelength of 360 nm.

The cured product has an elongation at break of 250% or more under <Condition 1>, and 24% of N-methyl-2-pyrrolidone or γ-butyrolactone under <Condition 2>. A flexo printing plate with a mass increase rate of 25% by mass or less when immersed for a time.

[6]

A method for producing a cured product, comprising a step of irradiating light having a wavelength of 360 nm to the photosensitive resin composition according to any one of [1] to [3] above.

[7]

A step of laminating the photosensitive resin composition according to any one of [1] to [3] above on a substrate to obtain a flexographic printing plate,

A process of photocuring the photosensitive resin composition by irradiating light having a wavelength of 360 nm to the flexographic printing plate,

Development process for removing unexposed areas in the photocuring

Having a method for producing a flexo printing plate.

[8]

A process of manufacturing a flexographic printing plate by the method of manufacturing a flexographic printing plate described in [7] above,

an ink attachment process of attaching ink to the flexo printing plate;

Transfer process for transferring the ink

A printing method with .

[9]

The printing method described in [8] above, which is a method of printing a liquid crystal alignment film used for manufacturing a liquid crystal display element.

[10]

The ink is N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolidinone, γ-butyrolactone (GBL), γ- Butyrolactam, N,N-dimethylformamide, N,N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxy Propionate, Diethylene glycol monomethyl ether, Diethylene glycol monoethyl ether, Diethylene glycol monomethyl ether acetate, Diethylene glycol monoethyl ether acetate, Isoamyl propionate, Isoamyl isobutylate, diisopentyl ether , ethylene carbonate, propylene carbonate, cyclohexane, 1-octanol, ethylene glycol monobutyl ether, and tetrahydrofuran. How to print.

According to the present invention, it is possible to provide a photosensitive resin composition capable of producing a flexographic printing plate that has both excellent solvent resistance and flexibility at a high level.

Hereinafter, the mode for carrying out the present invention (hereinafter referred to as “this embodiment”) will be described in detail.

In addition, the following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following content. The present invention can be implemented with appropriate modifications without departing from its gist.

[Photosensitive resin composition]

The photosensitive resin composition of this embodiment is,

A cured product of light containing a wavelength of 360 nm satisfies the following <Condition 1> and <Condition 2>.

<Condition 1>

At 23°C, the elongation at break when a dumbbell-shaped test piece with a measuring portion of 1 mm in thickness, 30 mm in length, and 3 mm in width was tensile tested at a speed of 500 mm/min was 250% or more.

<Condition 2>

The mass increase rate when immersed in N-methyl-2-pyrrolidone (NMP) or γ-butyrolactone for 24 hours is 25% by mass or less.

By having the above structure, it is possible to obtain a photosensitive resin composition capable of producing a flexographic printing plate that has both excellent solvent resistance and flexibility at a high level.

(Elongation at break of cured product of photosensitive resin composition)

The photosensitive resin composition of the present embodiment is a resin composition having photocurability, and the breaking elongation in the above <Condition 1> of the cured product by light containing a wavelength of 360 nm is 250% or more. Preferably it is 250% or more and 1000% or less, more preferably 300% or more and 900% or less, and even more preferably 350% or more and 800% or less.

By setting the breaking elongation of the cured product under the above <Condition 1> to 250% or more, excellent flexibility can be obtained, and when handling flexographic printing plates, specifically, the winding process to the plate body during printing, the attaching and detaching process, and printing. It tends to have sufficient durability against mechanical external forces that cause damage during the post-cleaning process. In particular, when the cured product of the photosensitive resin composition of the present embodiment has an area of 0.5 m ² or more, the breaking elongation is preferably 300% or more from the viewpoint of ease of handling. Moreover, when the cured product of the photosensitive resin composition of this embodiment is large and has an area of 3 m ² or more, the breaking elongation is preferably 350% or more.

As for the photosensitive resin composition of this embodiment, since a photoreaction progresses by exposure like a general photocuring reaction, the hardening reaction can be controlled by adjusting the exposure amount. By adjusting the exposure amount, the breaking elongation of the cured product can be controlled within the above numerical range. However, regarding toughness, it is necessary to always maintain it at 50 kgf×mm or more.

The breaking elongation of the cured product of the photosensitive resin composition of this embodiment can be measured by the method described in the Examples described later.

As a method of increasing the breaking elongation, reducing the density of the chemical or physical crosslinking points of the resin is effective, and can be controlled to the above numerical range by adjusting the resin composition or curing method used in the photosensitive resin composition of this embodiment.

Specifically, the resin composition of the photosensitive resin composition is preferably one that contains a polymer component that is liquid at a temperature of 23°C, an ethylenic monomer component having a radically reactive group, and an initiator component that starts the reaction of the ethylenic monomer. As the polymer component that is liquid at the temperature of 23°C, for example, a polyurethane prepolymer that is liquid at 23°C can be used, and as the initiator component, a radical photopolymerization initiator can be used, for example. At this time, the content of the ethylenic monomer is set to 40 parts by mass or less and 10 parts by mass or more based on 100 parts by mass of the polyurethane prepolymer, and 0 parts by mass of the ethylenic monomer having two or more radical reactive functional groups per 100 parts by mass of the ethylenic monomer. It is preferable to contain it in an amount of 30 parts by mass or less. Condition 1 can be satisfied by molding this photosensitive resin composition to a thickness of 1 mm and irradiating it with light containing 360 nm. As a curing method, Condition 1 can be satisfied by, for example, exposing the front and back to light with an illuminance of 0.5 to 500 mW/cm ² for 0.05 to 60 minutes each.

(Solvent resistance of cured product of photosensitive resin composition)

The photosensitive resin composition of the present embodiment is a resin composition having photocurability, and the cured product is immersed in N-methyl-2-pyrrolidone (NMP) or γ-butyrolactone for 24 hours with light containing a wavelength of 360 nm. The mass increase rate when applied is 25% by mass or less.

Specifically, the cured product of light containing a wavelength of 360 nm was cut into sample pieces with a thickness of 1 cm The mass increase rate when immersed in Yaku 99.0+% (Capillary GC)) or γ-butyrolactone (GBL: Tokyo Kasei > 99.0% (GC)) at a temperature of 23°C (humidity 50%) for 24 hours is It is 25% by mass or less.

Preferably it is 1 mass% or more and 25 mass% or less, more preferably 1 mass% or more and 20 mass% or less, and even more preferably 1 mass% or more and 15 mass% or less.

If the mass increase rate of the cured product is 1% by mass or more, the wettability of the surface of the flexographic printing plate and the alignment film varnish becomes necessary and sufficient, and printing without stains tends to be possible.

In addition, by setting the mass increase rate to 25% by mass or less, excellent solvent resistance can be exhibited, deformation of the pattern formed on the surface of the flexographic printing plate during actual alignment film printing can be suppressed, and high definition can be achieved. There is a tendency to

In addition, especially when the area of the flexographic printing plate is 0.5 m ² or more, the mass increase rate is set to 15 mass% or less, and especially when the area of the flexographic printing plate is large 3 m ² or more, the mass increase rate is set to 10 mass% or less. By doing so, in-plane thickness unevenness due to the enlargement of the flexo printing plate can be suppressed.

The mass increase rate of the cured product of the photosensitive resin composition of this embodiment can be controlled within the above numerical range by adjusting the exposure amount when forming the cured product.

The mass increase rate of the cured product of the photosensitive resin composition of this embodiment can be measured by the method described in the Examples described later.

The mass increase rate can be reduced by densifying the chemical or physical crosslinking points of the resin, thereby improving solvent resistance. These can be controlled by adjusting the resin composition or curing method.

Specifically, it is a preferred embodiment that the resin composition of the photosensitive resin composition includes a polymer component with a hydrophobic unit structure, an ethylenic monomer component, and an initiator component that starts the reaction of the ethylenic monomer. As the hydrophobic unit structure, for example, a polyurethane prepolymer containing hydrogenated polybutadiene can be used, and as the ethylenic monomer component, for example, those having two or more radical reactive functional groups; Alternatively, an ethylenic monomer having only one radical reactive functional group can be used as a saturated cyclic compound that has high hydrophobicity and the glass transition temperature of the high molecular weight homopolymerized ethylenic monomer is 50° C. or higher, and the photosensitive resin composition can be used as a light-sensitive resin composition. It is preferable to contain a radical polymerization initiator. Condition 2 can be satisfied by molding this photosensitive resin composition to a thickness of 1 mm and irradiating it with light containing 360 nm. As a curing method, Condition 2 can be satisfied by, for example, exposing the front and back to light with an illuminance of 0.5 to 500 mW/cm ² for 60 minutes from 0.05, respectively.

(Toughness of cured product of photosensitive resin composition)

The photosensitive resin composition of the present embodiment preferably has a toughness of 50 kgf x mm or more and 300 kgf x mm or less when exposed to light having a wavelength of 360 nm. More preferably, it is 80 kgf×mm or more and 250 kgf×mm or less, and even more preferably, it is 100 kgf×mm or more and 220 kgf×mm or less.

By setting the toughness of the cured product to 50 kgf It is possible to suppress the occurrence of defective printed matter. Additionally, damage can be prevented in the winding process to the plate body during printing, and good work efficiency can be realized.

In addition, by setting the toughness of the cured product to 50 kgf Damage to the plate can be prevented and its good condition can be maintained for a long time.

On the other hand, since excessive toughness may cause deterioration of handling properties in plate making operations such as plate cutting, it is desirable to set it to 300 kgf × mm or less, and by satisfying these values, plate making workability and the balance of various physical properties described above can be maintained.

The photosensitive resin composition of this embodiment can control the toughness of the cured product by adjusting the exposure amount in photocuring. Additionally, by adjusting the composition of the photosensitive resin composition, the toughness of the cured product can be controlled within the above-mentioned numerical range.

Specifically, it is a preferred embodiment that the resin composition of the photosensitive resin composition contains a polymer component that is liquid at a temperature of 23°C, an ethylenic monomer component, and an initiator component that starts the reaction of the ethylenic monomer. As a polymer component that is liquid at a temperature of 23°C, for example, a polyurethane prepolymer that is liquid at 23°C can be used, and as an initiator component, a radical photopolymerization initiator can be used, for example. At this time, the content of the ethylenic monomer is preferably 40 parts by mass or less and 10 parts by mass or more with respect to 100 parts by mass of the polyurethane prepolymer. In addition, the ethylenic monomer is a monomer in which the glass transition temperature of the homopolymer of the ethylenic monomer is 50° C. or higher, and preferably contains an ethylenic monomer having a saturated cyclic structure and one radical reactive functional group as a functional group. . Furthermore, the photosensitive resin composition preferably contains a radical photopolymerization initiator. By molding this photosensitive resin composition to a thickness of 1 mm and irradiating it with light containing 360 nm, the toughness conditions described above can be satisfied. As a curing method, for example, the toughness described above can be satisfied by exposing the front and back to light with an illuminance of 0.5 to 500 mW/cm ² for 60 minutes from 0.05, respectively.

The toughness of the cured product of the photosensitive resin composition of this embodiment can be measured by the method described in the Examples described later.

(Constitutive materials of photosensitive resin composition)

It is preferable that the photosensitive resin composition of this embodiment contains a polyurethane prepolymer, an ethylenic monomer, and a photopolymerization initiator.

<Polyurethane prepolymer>

The polyurethane prepolymer preferably has hydrophobicity, and specifically, preferably has a repeating structure composed only of hydrocarbons without polar groups such as carbonyl groups and ether groups, and for example, it preferably has a polyolefin structure or a hydrogenated polybutadiene structure. . Specifically, the polyurethane prepolymer is a poly that is obtained by introducing at least one polymerizable ethylenic double bond at the end of a prepolymer precursor obtained by chain extending a hydroxyl compound at both ends having the above structure into a urethane bond with diisocyanate. It is preferable that it is a urethane prepolymer.

In addition, elastomers such as polyurethane prepolymer and SBS, which have polar functional groups in the unit structure, do not have a problem in terms of imparting mechanical properties such as elongation at break or toughness to the cured product of the photosensitive resin composition, but because they are highly polar, There is an aspect that is said to be undesirable from the viewpoint of providing solvent resistance to the cured product of the photosensitive resin composition. Therefore, the polyurethane prepolymer preferably has a hydrophobic unit structure such as a polyolefin structure or hydrogenated polybutadiene.

The polyurethane prepolymer can be synthesized by known methods.

For example, the reaction of introducing at least a polymerizable ethylenic double bond at the terminal of the prepolymer precursor obtained by chain extending the above-mentioned hydrogenated polybutadiene compound with a urethane bond using diisocyanate is urethanization of tertiary amines, tin compounds, etc. It can be carried out in the presence or absence of a catalyst. Additionally, the reaction temperature at this time is preferably 40 to 100°C.

As the diisocyanate, aliphatic, alicyclic, and aromatic diisocyanate are used. Although not limited to the following, for example, hexamethylene diisocyanate (HMDI), trimethylhexamethylene diisocyanate (TMDI), 2,6- and/or 2,4-tolylene diisocyanate (2,6- and/or 2,4- TDI), paraphenylene diisocyanate, diphenylmethane diisocyanate (MDI), hydrogenated 2,6- and/or 2,4-TDI, hydrogenated MDI, dicyclohexyldimethylmethane diisocyanate, isophorone diisocyanate, etc. there is.

In order to obtain the polyurethane prepolymer, the method of introducing at least one ethylenic double bond into the terminal of the prepolymer precursor is not particularly limited, and a known method can be used. For example, a method of reacting diisocyanate with the terminal hydroxyl group of a polymer precursor in advance to introduce an isocyanate group at the terminal, and then reacting with a compound having a functional group having an active hydrogen such as an ethylenic double bond and a hydroxy group, or a method of reacting the terminal hydroxyl group with an ethylenic double bond. A method of esterifying with a carboxylic acid having .

Compounds having an ethylenic double bond and a functional group having an active hydrogen such as a hydroxyl group used to introduce an ethylenic double bond are not limited to the following, but examples include hydroxyalkyl (meth)acrylate and polyoxyalkylene. Glycol mono(meth)acrylate, etc. can be mentioned.

The hydroxyalkyl (meth)acrylate is not limited to the following, but examples include hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate.

Polyoxyalkylene glycol mono(meth)acrylate is not limited to the following, but examples include polyethylene glycol mono(meth)acrylate (Mn=300 to 1,000) and polypropylene glycol mono(meth)acrylate (Mn=300 to 1,000). 1,000), 1:1 addition reaction product between glycolic acid and glycidyl (meth)acrylate, 1:1 addition reaction product between glyceric acid and glycidyl (meth)acrylate, glycerin di(meth)acrylate, etc. I can hear it.

The content of polyurethane prepolymer in the photosensitive resin composition is preferably 40 to 95 parts by mass, more preferably 65 to 85 parts by mass, with respect to 100 parts by mass of the total photosensitive resin composition, from the viewpoint of high solvent resistance and high flexibility of the flexographic printing plate. .

When the amount is 40 parts by mass or more, the high solvent resistance and flexibility exhibited by the polyurethane prepolymer can be sufficiently exhibited, and when the amount is 95 parts by mass or less, an increase in viscosity can be suppressed and good workability can be obtained.

<Ethylenic monomer>

Known ethylenic monomers can be used, and are not limited to the following, but examples include alkyl (meth) such as 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate. acrylate; Hydroxyalkyl (meth)acrylates such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate; Polyoxyalkylene glycol mono(meth)acrylates such as polyethylene glycol mono(meth)acrylate (Mn=300 to 1,000) and polypropylene glycol (meth)acrylate (Mn=300 to 1,000); Caprolactone (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, isoboronyl (meth)acrylate, (meth)acrylamide, N-substituted or N,N' - Alkylene glycol di(meth)acrylates such as substituted (meth)acrylamide and tetraethylene glycol di(meth)acrylate; Polyoxyalkylene glycol di(meth)acrylates such as polyethylene glycol di(meth)acrylate (Mn=300 to 1,000) and polypropylene glycol di(meth)acrylate (Mn=300 to 1,000); Trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, etc. are mentioned.

These ethylenic monomers may be used individually, or in combination of two or more, depending on the purpose.

The amount of ethylenic monomer added is preferably 5 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the polyurethane prepolymer. When the addition amount of the ethylenic monomer is 5 parts by mass or more with respect to 100 parts by mass of the polyurethane prepolymer, the viscosity of the photosensitive resin composition can be made appropriate, and the mechanical properties of the resulting flexographic printing plate are well balanced. In addition, by adding the ethylenic monomer in an amount of 200 parts by mass or less with respect to 100 parts by mass of the polyurethane prepolymer, it is possible to prevent excessive curing shrinkage during photocuring, and the thickness accuracy of the target flexographic printing plate is good. It is possible to obtain a flexo printing plate with sufficient mechanical properties.

From the viewpoint of the balance of workability and mechanical properties in a plate making device of the photosensitive resin composition, it is more preferable that the amount of ethylene monomer added is 15 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the polyurethane prepolymer. Preferably it is 30 parts by mass or more and 70 parts by mass or less.

Among the above ethylene monomers, it is preferable to add at least one ethylenic monomer that has high hydrophobicity and whose glass transition temperature of the ethylenic monomer homopolymer is 50 or higher. Examples of such ethylenic monomers include cyclohexyl (meth)acrylate, isoboronyl (meth)acrylate, dicyclofentanyl (meth)acrylate, 1-ethylcyclohexyl (meth)acrylate, and 1-adamantyl. Saturated (meth)acrylate, 2-methyladamantyl (meth)acrylate, 2-isopropyl-2-(meth)acryloyloxyadamantane, 2-cyclohexylpropan-2-yl methacrylate, etc. and cyclic compounds. These are particularly preferable because they are effective in improving the solvent resistance and providing flexibility of the flexographic printing plate, and it is preferable that they contain at least one type of the above-mentioned ethylenic monomer. The addition amount of these ethylenic monomers is preferably 5 parts by mass or more and 80 parts by mass or less, and more preferably 10 parts by mass or more and 50 parts by mass or less, with respect to 100 parts by mass of the polyurethane prepolymer.

<Photopolymerization initiator>

The photopolymerization initiator may be any known photopolymerization initiator, and is not limited to the following. For example, benzoin (dimethyl ether) such as benzoin, benzoin ethyl ether, benzoin-n-propyl ether, benzoin-isopropyl ether, and benzyl dimethyl ketal. ) Alkyl ethers; Benzyl, diacetyl, diphenyl sulfide, dimethylacetophenone, etc. are mentioned.

The mixing amount of these photopolymerizable initiators is preferably 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total amount of the polyurethane prepolymer and the ethylenic monomer.

<Other materials>

Depending on the purpose, the photosensitive resin composition of the present embodiment may contain, in addition to the polyurethane prepolymer, ethylenic monomer, and photopolymerization initiator, for example, a thermal polymerization inhibitor, an ultraviolet absorber, a light stabilizer, a dye pigment, a lubricant, an antioxidant, an inorganic filler, and a surfactant. , plasticizers, process oil, liquid paraffin, liquid rubber, etc. can be added.

〔Flexo printing original plate〕

The flexographic printing original plate of this embodiment has a base material and the photosensitive resin composition of this embodiment.

The flexo printing original plate of this embodiment can be manufactured by laminating a layer of the photosensitive resin composition of this embodiment on a substrate.

According to the flexographic printing plate of this embodiment, a flexographic printing plate that has both excellent solvent resistance and flexibility at a high level can be manufactured.

[Flexo printing plate]

The flexographic printing plate of this embodiment has a base material and a cured product of the photosensitive resin composition of this embodiment with light containing a wavelength of 360 nm, and this includes one that is further processed with a laser or the like after curing. The cured product has a breaking elongation of 250% or more under <Condition 1>, and is immersed in N-methyl-2-pyrrolidone or γ-butyrolactone for 24 hours under <Condition 2>. The mass increase rate is 25% by mass or less.

According to the flexographic printing plate of this embodiment, excellent solvent resistance and flexibility can be achieved at a high level.

[Method for producing hardened product]

The method for producing a cured product of the present embodiment includes a step of irradiating light containing a wavelength of 360 nm to the photosensitive resin composition of the present embodiment described above.

In the method for producing the cured product of the present embodiment, an uncured resin recovery process for removing the uncured resin after curing, a washing process, and a post-exposure process can be additionally performed.

A fluorescent lamp or LED light can be used as a light source of light containing a wavelength of 360 nm, which is the irradiated light.

Regarding the irradiation time, select a time that allows curing by irradiating an exposure amount that is more than the exposure amount that can produce the desired thickness. The irradiation environment can be cured without major restrictions.

[Manufacturing method of flexo printing plate]

The manufacturing method of the flexographic printing plate of this embodiment includes the steps of laminating the photosensitive resin composition of this embodiment on a substrate to obtain a flexographic printing original plate,

A process of photocuring the photosensitive resin composition by irradiating light having a wavelength of 360 nm to the flexographic printing plate,

There is a development process for removing unexposed areas in the photocuring.

Specifically, a negative film is placed on a glass plate, the top is covered with a thin protective film, and the photosensitive resin composition of this embodiment is laminated thereon. With the base film (substrate) serving as a support attached, a glass plate is placed on the base film so that the thickness of the photosensitive resin composition layer becomes a preset constant value. Next, a short-time back exposure is performed using the upper actinic light source to form a uniform thin resin layer, that is, a back exposure layer, on the entire surface of the support. Next, image formation exposure is performed by irradiating light with a wavelength of 360 nm from a lower actinic light source to form a relief. Then, a development step of washing and removing the photosensitive resin composition of the unexposed portion in the uncured process is performed. Next, the entire plate obtained is further irradiated with actinic light in water or air (post-exposure) to ensure more complete curing, and then drying is performed to obtain a flexographic printing plate.

Examples of active light sources used for exposure in the manufacturing process of the flexographic printing plate include high-pressure mercury lamps, ultra-high pressure mercury lamps, ultraviolet fluorescent lamps, carbon arc lamps, and xenon lamps. Additionally, the transparent image carrier used to form a relief image is mainly a negative or positive film for photoengraving using a silver salt image.

For example, water, aqueous alkaline solution, aqueous surfactant solution, solvent, etc. are used as cleaning liquids for uncured resin.

The photosensitive resin composition of this embodiment can also be used for plate making such as flexographic printing plates and stamp plates.

Printed materials used in printing such as flexographic printing plates and stamp plates include, in addition to glass plates, wafers; Polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyurethane, polylactic acid, Teflon, ABS resin, AS resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polyimide, polyacetal, polycarbonate, modified polyphenyl ether. , polyethylene terephthalate, polybutylene terephthalate, cyclic polyolefin, polyphenylene sulfide, polytetrafluoroethylene, polysulfone, polyethersulfone, liquid crystal polymer, polyetheretherketone, methacrylic resin, polyether, polyphenylene. Resins containing one or more types of sulfide and polyarylate, steel, stainless steel, aluminum, magnesium, titanium, copper, lead, zinc, nickel, chromium, tungsten, gold, silver, platinum, and alloys containing two or more types thereof can be used. You can.

〔Printing method〕

The printing method of this embodiment includes a process of manufacturing a flexographic printing plate by the above-described method of manufacturing a flexographic printing plate, an ink adhesion process of attaching ink to a convex part of the flexographic printing plate, and transferring the ink. It has a transfer process.

The printing method of this embodiment is suitable as a method of printing, for example, a liquid crystal alignment film used in the manufacture of a liquid crystal display element on a substrate.

The ink used in the printing method of this embodiment includes N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolidinone, and Highly polar solvents such as γ-butyrolactone (GBL), γ-butyrolactam, N,N-dimethylformamide, N,N-dimethylacetamide, and other solvents such as 4-hydroxy-4-methyl -2-pentanone, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxy propionate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene Glycol monoethyl ether acetate, isoamyl propionate, isoamyl isobutylate, diisopentyl ether, ethylene carbonate, propylene carbonate, cyclohexane, 1-octanol, ethylene glycol monobutyl ether, and tetrahydrofuran. Solvents containing the above can be mentioned.

According to the printing method of this embodiment, since the flexographic printing plate of this embodiment is excellent in flexibility and solvent resistance, high quality and long-term printing can be achieved.

Example

Hereinafter, the present embodiment will be described in detail with reference to specific examples and comparative examples, but the present invention is not limited in any way by the following examples and comparative examples.

[Manufacture example 1 of polyurethane resin (PU-1), which is an elastomer species constituting the photosensitive resin composition of Examples 1 to 7 and Comparative Examples 1 to 2]

300 g of terminal hydroxyl group hydrogenated polybutadiene and 20.7 g of tolylene diisocyanate were stirred and mixed at 40°C for 30 minutes, then reacted at 80°C for 5 hours, then 11 g of 2-hydroxypropyl methacrylate, 0.3 g of hydroquinone, and 0.6 g of dibutyltin dilaurate were added and reacted at 80°C. The reaction was stopped when the NCO group characteristic absorption disappeared in the infrared absorption spectrum chart, and a polyurethane prepolymer was obtained.

[Manufacture example 2 of polyurethane resin (PU-2), which is an elastomer species constituting the photosensitive resin compositions of Examples 8, 9, and 11]

300 g of terminal hydroxyl polyolefin and 20.7 g of tolylene diisocyanate were stirred and mixed at 40°C for 30 minutes, then reacted at 80°C for 5 hours, then 11 g of 2-hydroxypropyl methacrylate, 0.3 g of hydroquinone, and dibutyl A mixed solution of 0.6 g of tin dilaurate was added and reacted at 80°C. The reaction was stopped when the NCO group characteristic absorption disappeared in the infrared absorption spectrum chart, and a polyurethane prepolymer was obtained.

[Examples 1 to 11], [Comparative Examples 1 to 6]

The abbreviations of the compounds used in Examples 1 to 11 and Comparative Examples 1 to 2 and the material composition of the photosensitive resin composition are shown in Table 1 below.

The photosensitive resin compositions of Examples 1 to 11 and Comparative Examples 1 to 2 were prepared by adding the polyurethane prepolymer prepared in Production Example 1, the ethylenic monomer, photopolymerization initiator, and polymerization inhibitor shown in Table 1.

The abbreviations of the compounds shown in Table 1 are explained below.

PU-1: Prepolymer prepared in Preparation Example 1: Elastomer

PU-2: Prepolymer prepared in Preparation Example 2: Elastomer

SLMA: Lauryl methacrylate: Ethylenic monomer

HP: 2-hydroxypropyl methacrylate: ethylenic monomer

AP-400: Polyoxypropylene monoacrylate: Ethylenic monomer

KH: 2-hydroxyethyl methacrylate: ethylenic monomer

GMGA: Glycerin monomethacrylate: Ethylenic monomer

CH: Cyclohexyl methacrylate: Ethylenic monomer

IBX: Isobornyl methacrylate: Ethylenic monomer

IBX-A: Isobornyl acrylate: Ethylenic monomer

MADMA: 2-methyladamantane-2-yl methacrylate

FA-512M: Dicyclopentenyloxyethyl methacrylate

HOP(N): 2-hydroxypropyl methacrylate: ethylenic monomer

513AS: Dicyclopentanyl acrylate: ethylenic monomer

TMPT: Trimethylolpropane trimethacrylate: Ethylenic monomer

6EO: Trimethylolpropane EO6 mol modified triacrylate: ethylenic monomer

A-DPH: Dipentaerythritol hexaacrylate: Ethylenic monomer

Z4: 2-(1-methylethoxy)-1,2-diphenylethanone, benzoin isopropyl ether: photopolymerization initiator

Z7: 2,2-dimethoxy-2-phenylacetophenone: photopolymerization initiator

Z8: Benzophenone: Photopolymerization initiator

I13: 2,6-di-t-butyl-4-methylphenol: polymerization inhibitor

I14: 3,9-bis-{1,1-dimethyl-2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propienoloxy]ethyl}-2,4,8, 10-Tetraoxaspiro(5,5)undecane: Polymerization inhibitor

In Comparative Example 3, Asahi Kasei Co., Ltd. brand name "K-11" was used as the photosensitive resin composition.

In addition, “polyurethane resin” in Tables 2 to 3 means not the polyurethane resin (polyurethane prepolymer) of Production Example 1, but a polyurethane resin, which is a general polymer classification.

In Comparative Example 4, the brand name "KS-80" manufactured by Asahi Kasei Co., Ltd. was used as the photosensitive resin composition.

In addition, “polyurethane resin” in Tables 2 to 3 means not the polyurethane resin (polyurethane prepolymer) of Production Example 1, but a polyurethane resin, which is a general polymer classification.

In Comparative Example 5, the brand name "SH" manufactured by Asahi Kasei Co., Ltd. was used as the photosensitive resin composition.

As shown in Table 3, the binder polymer used in the above “SH” is an elastomer SBS resin.

In Comparative Example 6, Asahi Kasei Co., Ltd. brand name “F-900” was used as the photosensitive resin composition.

In addition, “polyurethane resin” in Tables 2 to 3 means not the polyurethane resin (polyurethane prepolymer) of Production Example 1, but a polyurethane resin, which is a general polymer classification.

The binder polymer used in the above “F-900” is an elastomer polyurethane resin, as shown in Table 3.

The elastomer species of the photosensitive resin compositions of Examples 1 to 11 and Comparative Examples 1 to 6 and their unit structures are shown in Tables 2 and 3 below.

In addition, in the elastomer species, the case of polyurethane resin was written as “○”, and the case of SBS resin was written as “×”.

In addition, regarding the unit structure of the elastomer species, the case of butadiene was described as "○", and the case of the unit structure containing ester or ether or styrene was described as "×".

〔Measurement method and evaluation method of characteristics〕

((1) Method of measuring swelling rate (mass increase rate))

The photosensitive resin compositions of Examples 1 to 11 and Comparative Examples 1 to 6 were sandwiched between two transparent resin plates with a thickness of 4 mm covered with a thin protective film, with a spacer having a thickness of 1 mm, and placed on the transparent resin plate. With a light source intensity of 2.0 mW/cm ² , the front and back were exposed using an irradiation lamp to produce a sample plate with a thickness of 1 mm.

This sample plate was cut into 1 cm x 5 cm sample pieces and immersed in N-methyl-2-pyrrolidone (NMP) or γ-butyrolactone (GBL) for 24 hours.

The mass of each sample piece before and after immersion was measured, and the mass increase rate (swelling rate (% by mass)) was calculated.

The swelling rate was evaluated according to the following criteria.

○: 25% by mass or less.

×: exceeded 25% by mass.

((2) Measurement method of breaking elongation and toughness)

A sample plate with a thickness of 1 mm was produced in the same manner as the swelling ratio measurement method.

Using a sample plate, a dumbbell-shaped sample with a measurement portion of 30 mm in height and 3 mm in width was produced and used as a test piece for measuring tensile elongation.

The tensile elongation was measured by pulling the test piece at a tensile speed of 500 mm/min at 23°C until it was broken using a tensile tester (AUTOGRAPH AG-AGS-X type: manufactured by Shimadzu Seisakusho) and measuring the elongation at break (%). ), toughness (kgf × mm) was obtained, and evaluated according to the following standards.

<Fadan believer>

○: 250% or more.

×: Less than 250%.

<Toughness>

○: 50 kgf×mm or more

×: Less than 50 kgf×mm

((3) Method of measuring change rate of 500 ㎛ independent line width before and after swelling)

Examples 1 to 11 and Comparative Examples 1 to 6 were obtained by sequentially going through a molding/exposure process, a developing process, a post-exposure process, and a drying process as shown below using a negative film forming a 500 ㎛ independent line. A flexo printing plate using a photosensitive resin composition was produced.

<1: Molding/exposure process>

Using an ALF-213E type plate making machine (manufactured by Asahi Kasei Co., Ltd.), curing was performed using a mask exposure amount and a relief exposure amount to achieve a thickness of 2.84 mm and R.D = 1.5 mm, to create a flexographic printing plate with independent lines of 500 ㎛. got it

<2: Development process>

After recovering the uncured photosensitive resin composition by a conventional method, an AL-400W type developer (drum rotation spray type, manufactured by Asahi Kasei Co., Ltd., drum rotation speed: 20 rotations/min, spray pressure: 0.15 Pa) APR (registered trademark) detergent type W-6 (manufactured by Asahi Kasei Co., Ltd.), which can emulsify the photosensitive resin composition: 4.5% by mass, and defoamer SH-4 (silicone mixture, Asahi Kasei Co., Ltd.) Note) Manufacture: An aqueous solution containing 0.18% by mass was prepared as a developing solution, and development was performed under the conditions of a liquid temperature of 40°C and a development time of 20 minutes.

After development, it was washed with tap water to the point where bubbles from the developer were removed.

<3: Post-exposure process>

Exposure was performed using an underwater exposure method using an AL-200UP type post-exposure machine (manufactured by Asahi Kasei Co., Ltd.) equipped with both an ultraviolet fluorescent lamp and a sterilizing lamp. Exposure was performed at an exposure time such that the exposure amount irradiated from each light source was 960 mJ/cm ² for ultraviolet fluorescent lamp and 1920 mJ/cm ² for sterilizing lamp on the surface of the cured photosensitive resin composition.

<4: Drying process>

Using ALF-DRYER (manufactured by Asahi Kasei Co., Ltd.), the post-exposed cured plate was dried for about 30 minutes or more until moisture on the surface disappeared, thereby obtaining a flexographic printing plate.

<5: Measurement of change rate of independent line width of 500 ㎛>

The plated 500 µm independent line was immersed under the same conditions as above ((1) Method for measuring swelling ratio).

After that, the sample was cut out, and the rate of change in line width before and after immersion was calculated.

Regarding the value of the change rate of the 500 ㎛ width before and after swelling, if it changes by more than 20%, it will adversely affect the printing quality, such as pattern starvation and deformation during printing. Therefore, it is said that it is practically preferable to be less than 20%, and the following criteria are used. evaluated by

○: Change rate is less than 20%

×: Change rate is 20% or more

((4) Hardness (Shore A hardness) measurement method)

A flexographic printing plate (thickness: 2.84 mm) having a solid surface was produced in the same manner as described above ((3) Method of measuring change rate of 500 μm independent line width before and after swelling).

After leaving the manufactured flexo printing plate in a constant temperature and humidity room with a temperature of 23°C and a relative humidity of 50% for one day, it was loaded with a JIS constant pressure loader GS-710 (manufactured by Techrock Co., Ltd., durometer GS-719GASTM: D2240A, JIS: K6253A). , ISO: 7619A), Shore A hardness was measured. The value 15 seconds after the load (mass 1 kg) on the solid surface was taken as Shore A hardness.

If the flexographic printing plate is too hard, it becomes impossible to obtain printed matter with a uniform solid surface. Therefore, it is said that it is practically desirable for the Shore A hardness of the flexographic printing plate to be 50° or less, and it was evaluated according to the following criteria.

<Evaluation criteria>

○: 50° or less

×: greater than 50°

((5) Method of measuring notch crack resistance)

A flexographic printing plate (thickness: 2.84 mm) having a solid surface was produced in the same manner as above ((3) Method of measuring change rate of independent line width of 500 μm before and after swelling).

Three strip-shaped sample plates with a width of 2 cm and a length of 5 cm were cut from the solid surface area, and a cut root (notch) with a depth of 1.0 mm was inserted in the central part of the longitudinal direction with a cutter to prepare the sample plates.

The sample plate was left in a constant temperature and humidity room with a temperature of 23°C and a relative humidity of 50% for one day, and measurements were performed in the same room using the following operations.

Both ends of the sample plate in the longitudinal direction are slightly curved so that the notch is on the outside and lightly held with the fingers of one hand, and then the support located on the back side of the notch of the sample plate is placed on the notch. The finger of the other hand was placed on the support so that it could be bent directly below, and the sample plate was quickly bent to support it so that the supports maintained a close contact with each other. The time from the moment the sample plate was bent until the crack formed from the notch reached the support was measured in seconds.

Flexo printing plates have opportunities to bend, such as when attaching to the plate body or packaging. If there is a small flaw at that time, there is a risk that the flexographic printing plate will crack and the resin will be completely split. In order to prevent this, notch cracking resistance was evaluated according to the following criteria, considering that it is practically desirable to have 5 seconds or more.

<Evaluation criteria>

○: 5 seconds or more

×: Less than 5 seconds

((6) Print quality evaluation)

A flexographic printing plate having an independent line of 500 μm was produced in the same manner as ((3) Method of measuring the change rate of the independent line width of 500 μm before and after swelling), and printing was performed using this flexographic printing plate to determine the print quality. evaluated.

The printing press used was “FlexPress16S” (trademark, manufactured by Fischer & Krecke, Germany).

The ink used was an orientation film “SE-130” (manufactured by Nissan Chemical Co., Ltd.).

A milky white polyethylene film with a thickness of 45 μm was used as the printed material.

The number of anilox rolls was set to 900 (lpi), and the cell volume of the anilox rolls was set to 4 cc.

The printing speed was 200 m/min.

Printing evaluation was performed with the flexographic printing plate not immersed in NMP and the flexographic printing plate immersed in N-methyl-2-pyrrolidone (NMP) for 24 hours, and a 500 ㎛ independent line in each state was performed. Got a printout.

The line width of the printed matter printed using the flexo printing plate initially and after immersion was measured under a microscope, and the rate of change was calculated.

When printing an alignment layer for a liquid crystal display device using a flexographic printing plate, if the printing quality of the alignment layer is not uniform, it will lead to defects in the liquid crystal display device, so the printed matter before and after swelling the flexographic printing plate needs to be 500% larger. The value of the ㎛ width change rate was evaluated in the following manner, assuming that it is practically desirable to be within ±30%.

○: Within ±30%

×: Exceeded ±30%.

The measurement results and evaluation results described above are shown in Tables 2 to 5.

Examples 1 to 11 obtained flexo printing plates showing high flexibility.

Examples 1 to 11 obtained excellent solvent resistance.

The photosensitive resin composition of the present invention has industrial applicability in the field of flexo printing plate manufacturing.

Claims (10)

A photosensitive resin composition in which the cured product of light containing a wavelength of 360 nm satisfies the following <Condition 1> and <Condition 2>:
<Condition 1>
At 23°C, the elongation at break when a dumbbell-shaped test piece with a measuring portion of 1 mm in thickness, 30 mm in length, and 3 mm in width was tensile tested at a speed of 500 mm/min was 250% or more.
<Condition 2>
The mass increase rate when immersed in N-methyl-2-pyrrolidone (NMP) or γ-butyrolactone for 24 hours is 25% by mass or less. The photosensitive resin composition according to claim 1, wherein the photosensitive resin composition contains a polyurethane prepolymer. The photosensitive resin composition according to claim 2, wherein the polyurethane prepolymer has a hydrogenated polybutadiene structure. With equipment,
Photosensitive resin composition according to claim 1
A flexographic printing plate having a . With equipment,
A cured product of the photosensitive resin composition according to claim 1 with light containing a wavelength of 360 nm.
The cured product has an elongation at break of 250% or more under <Condition 1>, and 24% of N-methyl-2-pyrrolidone or γ-butyrolactone under <Condition 2>. A flexo printing plate with a mass increase rate of 25% by mass or less when immersed for a time. A method for producing a cured product, comprising a step of irradiating light having a wavelength of 360 nm to the photosensitive resin composition according to claim 1. A step of laminating the photosensitive resin composition according to claim 1 on a substrate to obtain a flexographic printing plate;
A process of photocuring the photosensitive resin composition by irradiating light having a wavelength of 360 nm to the flexographic printing plate,
Development process for removing unexposed areas in the photocuring
Having a method for producing a flexo printing plate. A process for manufacturing a flexographic printing plate by the method for manufacturing a flexographic printing plate according to claim 7,
an ink attachment process of attaching ink to the flexo printing plate;
Transfer process for transferring the ink
A printing method with . The printing method according to claim 8, which is a method of printing a liquid crystal alignment film used for manufacturing a liquid crystal display element. The method of claim 8, wherein the ink is N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolidinone, and γ-butyrolactone. (GBL), γ-butyrolactam, N,N-dimethylformamide, N,N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, butyl lactate, butyl acetate, methylmethoxyprop Cypionate, ethyl ethoxypropionate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, isoamyl propionate, isoamyl isobutyl. A printing method comprising at least one solvent selected from the group consisting of cyclohexane, diisopentyl ether, ethylene carbonate, propylene carbonate, cyclohexane, 1-octanol, ethylene glycol monobutyl ether, and tetrahydrofuran.