JP2006284615A - Method for producing photosensitive elastomer composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently producing a photosensitive elastomer composition excellent in smoothness and flow resistance of a sheet surface and having low tackiness, the photosensitive elastomer composition, a composition for preparing a photosensitive elastomer composition suitable for use in the production of the above composition, and a flexographic plate obtained by exposing the composition. <P>SOLUTION: The method for producing the photosensitive elastomer composition includes (1) a step of mixing a thermoplastic elastomer and a plasticizer and (2) a step of mixing the mixture obtained at the step (1), a photosensitive ethylenically unsaturated compound and a photopolymerization initiator. The photosensitive elastomer composition is obtained by the producing method. The composition for preparing a photosensitive elastomer composition contains a thermoplastic elastomer and a plasticizer. The flexographic plate is obtained by exposing the above photosensitive elastomer composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a photosensitive elastomer composition, a photosensitive elastomer composition, a composition for preparing a photosensitive elastomer composition, and a flexographic plate.

  Plastic containers, cartons, plastic bags, boxes and envelopes are usually flexographically printed on the surface. As a flexographic plate used for flexographic printing, a photolithographic plate composition formed by exposing a photosensitive flexographic composition containing an elastomer, a photosensitive ethylenically unsaturated compound, and a photopolymerization initiator is frequently used.

  The composition for photosensitive flexographic plates is usually formed into a sheet shape, a sheet having a multilayer structure, in which a flexible sheet serving as a support is provided on one side and a protective film is provided on the other side. Supplied as The multilayer sheet is irradiated with light from the support side to be cured to a specific thickness of the photosensitive flexographic composition layer. Next, the protective film is peeled off, the negative film is brought into close contact with the surface, and then light is irradiated from above the negative film. The composition for photosensitive flexographic plates where light is transmitted is cured, and the uncured portion is removed with an organic solvent or an aqueous solvent to form a flexographic plate having an uneven structure.

  The composition for photosensitive flexographic plates has the property of forming a smooth surface when formed into a sheet shape (smoothness of the sheet surface) for the purpose of facilitating the formation of precise uneven surfaces, and the sheet-shaped photosensitive flexo plate. When the plate composition is stored, a property (flow resistance) is required in which the sheet thickness hardly changes due to its own weight or a load from above the sheet. Moreover, low adhesiveness is calculated | required by the composition for photosensitive flexographic plates for the purpose of making it easy to peel off a protective film, without making a surface state rough. Furthermore, in order to perform high quality printing, it is required to provide a flexographic plate having excellent resolution of fine lines in a negative film.

  For example, Patent Document 1 discloses a composition for a photosensitive flexographic plate comprising a block copolymer composition, an ethylenically unsaturated monomer, and a photopolymerization initiator, wherein the block copolymer composition is a fragrance. Aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having an aromatic vinyl monomer unit amount of 5 to 25% by weight, and aromatic vinyl-conjugated diene block having a weight average molecular weight of 1,000 to 35,000 A photosensitive flexographic composition comprising a copolymer is disclosed. However, such a composition can provide a flexographic plate having excellent resolution of fine lines, but may have poor sheet surface smoothness and flow resistance, or may have a high adhesiveness and cause problems. It was.

In addition, although patent document 1 has description that a plasticizer may be contained in this composition, there is no description about how to contain a plasticizer.
Special table 2002-519465 gazette

  The object of the present invention is to efficiently produce a photosensitive elastomer composition that is excellent in the smoothness of the surface of the sheet and the flow resistance, in particular, the flow resistance when there is a load from the surface direction of the sheet and has low adhesion. A photosensitive elastomer composition obtained by the method, a photosensitive elastomer composition preparation suitably used for producing the composition, and a flexographic plate obtained by sensitizing the photosensitive elastomer composition It is to provide.

  As a result of intensive studies to solve the above problems, the inventors of the present invention obtained a mixture by preliminarily mixing a thermoplastic elastomer as one component and a plasticizer when obtaining a photosensitive elastomer composition. After that, it is found that a photosensitive elastomer composition having desired properties can be obtained by mixing a photosensitive ethylenically unsaturated compound, which is another component of the composition, and a photopolymerization initiator into the mixture. The invention has been completed.

That is, the present invention
[1] (1) A step of mixing a thermoplastic elastomer and a plasticizer, and (2) a step of mixing the mixture obtained in step (1), a photosensitive ethylenically unsaturated compound and a photopolymerization initiator,
A method for producing a photosensitive elastomer composition having
[2] The method for producing a photosensitive elastomer composition according to [1], wherein the step (1) is performed under a temperature condition of 180 to 300 ° C.
[3] The method for producing a photosensitive elastomer composition according to [1], wherein the step (1) is performed by dissolving and mixing a thermoplastic elastomer and a plasticizer in a solvent and removing the solvent from the obtained solution. ,
[4] A photosensitive elastomer composition obtained by the method for producing a photosensitive elastomer composition according to any one of [1] to [3],
[5] A composition for preparing a photosensitive elastomer composition comprising a thermoplastic elastomer and a plasticizer, and [6] a flexographic plate formed by exposing the photosensitive elastomer composition according to [4] above,
Is to provide.

  According to the present invention, it is possible to efficiently produce a photosensitive elastomer composition that is excellent in the smoothness of the sheet surface and the flow resistance, in particular, the flow resistance when there is a load from the surface direction of the sheet and has low adhesion. can do. Further, an excellent flexographic plate can be obtained by the composition.

  Hereinafter, a method for producing a photosensitive elastomer composition, a photosensitive elastomer composition, a composition for preparing a photosensitive elastomer composition, and a flexographic plate of the present invention will be described in detail. In addition, each component or component used in the present invention may be used alone or in combination of two or more as appropriate.

1. Manufacturing method of photosensitive elastomer composition, photosensitive elastomer composition, and composition for preparing photosensitive elastomer composition The manufacturing method of the photosensitive elastomer composition of the present invention includes (1) mixing a thermoplastic elastomer and a plasticizer. And (2) mixing the mixture obtained in step (1), the photosensitive ethylenically unsaturated compound and the photopolymerization initiator. In step (1), the thermoplastic elastomer and plastic One major characteristic is that the agent is premixed (preliminarily mixed). Since it has such a configuration, according to the production method of the present invention, an excellent photosensitive elastomer composition having desired properties can be efficiently obtained.

  Although it does not specifically limit as a thermoplastic elastomer used at a process (1), The hardness of the sheet | seat (henceforth a sheet | seat) formed by shape | molding the photosensitive elastomer composition is reduced, and a softness | flexibility is improved. From the viewpoint, a polymer block (A) of an aromatic vinyl monomer (hereinafter sometimes referred to as polymer block (A)) and a polymer block (B) of a conjugated diene monomer (hereinafter referred to as polymer block ( B) may be contained in a composition (hereinafter referred to as a block copolymer composition).

  The block copolymer composition of the present invention may be hydrogenated. In that case, at least a part of the carbon-carbon double bond other than the aromatic part of the block copolymer is hydrogenated. The hydrogenation method is not particularly limited.

  The content of the block copolymer composition in the thermoplastic elastomer is preferably 20% by weight or more, more preferably 40% by weight or more, and further preferably 60% by weight or more.

  The weight average molecular weight of the entire block copolymer composition of the present invention is preferably 100,000 to 500,000, more preferably 150,000 to 400,000. If the weight average molecular weight is 100,000 or more, the hardness of the sheet is appropriate, and if it is 500,000 or less, the heat resistance of the sheet is good.

  In addition, the weight average molecular weight in this specification can be measured by a gel permeation chromatography (GPC) method using monodispersed polystyrene as a standard sample.

  The content of the aromatic vinyl monomer unit in the block copolymer composition of the present invention is preferably 5 to 35% by weight, more preferably 10 to 30% by weight, and particularly preferably 13 to 25%. % By weight. If the content of the aromatic vinyl monomer unit is 5% by weight or more, the flow resistance is good, and if it is 35% by weight or less, the hardness of the sheet is appropriate.

  The proportion of vinyl bond units (vinyl content) in the total amount of conjugated diene monomer units in the block copolymer composition of the present invention is usually 70% by weight or less, preferably from the viewpoint of maintaining good sheet flexibility. It is 3 to 60% by weight, more preferably 5 to 40% by weight.

  From the viewpoint of enhancing the sensitivity to light and the resolution of fine lines after photocuring, the thermoplastic elastomer of the present invention is preferably a transparent one. Therefore, the block copolymer composition of the present invention is obtained by the heat obtained. A block copolymer composition (hereinafter referred to as block copolymer composition 1) prepared by sequentially polymerizing a polymer block (A) and a polymer block (B) in that the transparency of the plastic elastomer becomes extremely high. And / or a block copolymer (AB) of the polymer block (A) and the polymer block (B), and a compound having two or more, preferably 2 to 4, functional groups that are the same or different. A block copolymer composition prepared by a coupling reaction used as a ring agent (hereinafter referred to as block copolymer composition 2) is desirable. In addition, when using the block copolymer composition 1 and the block copolymer composition 2 together, the mixing ratio of both is not specifically limited.

  Examples of the aromatic vinyl monomer constituting the polymer block (A) of the present invention include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethyl. Styrene, p-ethyl styrene, p-tert-butyl styrene, etc. are mentioned. Of these, styrene is preferred.

  The polymer block (A) is preferably a polymer block obtained by polymerizing only an aromatic vinyl monomer, but is copolymerized with another monomer copolymerizable with the aromatic vinyl monomer. It may be what you did. Examples of the other monomer include conjugated diene monomers such as 1,3-butadiene and isoprene. When other monomers are copolymerized, the proportion of the other monomer units in the polymer block (A) is preferably 10% by weight or less.

  Examples of the conjugated diene monomer constituting the polymer block (B) of the present invention include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3- Examples thereof include butadiene and 1,3-pentadiene. Among these, 1,3-butadiene and isoprene are preferable, and isoprene is more preferable.

  The polymer block (B) is preferably a polymer block obtained by polymerizing only a conjugated diene monomer, but is obtained by copolymerizing another monomer copolymerizable with the conjugated diene monomer. It may be. Typical examples of the other monomer include aromatic vinyl monomers such as styrene and α-methylstyrene. When other monomers are copolymerized, the proportion of the other monomer units in the polymer block (B) is preferably 10% by weight or less.

  The block copolymer composition 1 is not particularly limited. For example, an aromatic vinyl monomer and a conjugated diene monomer are sequentially polymerized using an alkyllithium compound as an initiator, and then an aromatic vinyl monomer. And a block copolymer composition obtained by polymerizing a conjugated diene monomer using a dilithium compound as an initiator and then sequentially polymerizing an aromatic vinyl monomer.

  Specifically, the block copolymer composition 1 is a composition comprising at least one selected from the group consisting of styrene-isoprene block copolymers, styrene-butadiene block copolymers, and hydrogenated products thereof. A composition comprising a styrene-isoprene block copolymer and / or a hydrogenated product thereof is more preferable.

  The block copolymer composition 2 is not particularly limited. For example, a block copolymer (A-B) of a polymer block (A) and a polymer block (B) can be prepared by a conventional method, a so-called living anion. Examples thereof include a block copolymer composition prepared by a polymerization method and prepared by a coupling reaction with a desired coupling agent.

  As the coupling agent, a coupling agent containing halogen or a coupling agent not containing halogen can be used. From the viewpoint of improving the transparency of the thermoplastic elastomer and enhancing the sensitivity to light and the resolution of fine lines after photocuring, a coupling agent containing no halogen is preferable.

  Moreover, as a functional group of a coupling agent, Preferably it is an alkoxyl group, More preferably, they are a methoxy group and an ethoxy group. When a coupling agent having such a functional group is used, the transparency of the thermoplastic elastomer is improved, and the sensitivity to light and the resolution of fine lines after photocuring are increased.

  Specific examples of the coupling agent containing halogen include bifunctional halogenated silanes such as dichlorosilane, monomethyldichlorosilane, and dimethyldichlorosilane; bifunctional halogenations such as dichloroethane, dibromoethane, methylene chloride, and dibromomethane. Alkane: Bifunctional tin halide such as dichlorotin, monomethyldichlorotin, dimethyldichlorotin, monoethyldichlorotin, diethyldichlorotin, monobutyldichlorotin, dibutyldichlorotin; Trifunctional halogenated alkane such as trichloroethane and trichloropropane A tetrafunctional halogenated silane such as tetrachlorosilane or tetrabromosilane; a tetrafunctional tin compound such as tetrachlorotin or tetrabromotin;

  Specific examples of the halogen-free coupling agent include organotin compounds such as tetramethoxytin, tetraethoxytin, and tetrabutoxytin; dimethyldimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, alkyltriphenoxysilane, Organic silicon compounds such as methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, bis (trimethoxysilyl) ethane; unsaturated nitriles such as ethylacrylonitrile; methyl formate, ethyl formate, Methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, amyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, ethyl trimethyl acetate, methyl caproate, capron Carboxylic acid esters such as ethyl, methyl benzoate, ethyl benzoate, phenyl benzoate, dimethyl adipate, diethyl adipate, dimethyl terephthalate, diethyl terephthalate, dimethyl phthalate, dimethyl isophthalate; trisnonylphenyl phosphite, Organophosphorus compounds such as trimethyl phosphite and triethyl phosphite; and divinylbenzene. Among these, organic silicon compounds are preferable, and tetramethoxysilane, tetraethoxysilane, and tetrabutoxysilane are more preferable.

  For example, a coupling reaction using a different coupling agent may be mixed, or a coupling reaction may be performed by appropriately mixing different compounds as a coupling agent. Absent.

  The coupling reaction may be performed according to a conventional method by adding a coupling agent to a predetermined polymer solution and, for example, at a temperature of 30 to 80 ° C. for about 1 minute to 24 hours.

  Although there is no limitation in particular as a composition prepared using the compound which has 2 functional groups as a coupling agent as the block copolymer composition 2, For example, the block copolymer represented by ABA The block copolymer composition which consists of these is mentioned. A represents a polymer block of an aromatic vinyl monomer, and B represents a polymer block of a conjugated diene monomer.

  Moreover, there is no limitation in particular as a composition prepared using the compound which has 3 or 4 functional groups as a coupling agent, For example, the following block copolymer compositions (P) are mentioned.

That is, the block copolymer composition (P) includes a block copolymer represented by the following general formula (a3), or a block copolymer represented by the general formula (a3) and the general formula (a2) and And / or a block copolymer composed of a block copolymer represented by the general formula (a4) [hereinafter collectively referred to as a block copolymer (a)] and the following general formula (b) The block copolymer (a) and the block copolymer (b) in the composition have a content of (a) 50 to 100% by weight and (b), respectively. The composition is 0 to 50% by weight.
(AB) ₂ X (a2)
(AB) ₃ X (a3)
(AB) ₄ X (a4)
A-B (b)

  In general formulas (a2), (a3), (a4), and (b), A represents a polymer block of an aromatic vinyl monomer, B represents a polymer block of a conjugated diene monomer, and X Represents a residue of a compound as a coupling agent. The residues of each coupling agent X in (a2), (a3), and (a4) may be the same or different. As the block copolymers represented by the general formulas (a2) to (a4), those obtained by bonding the polymer block (B) and the X are preferable.

  In the block copolymer composition (P), the content of the block copolymer (a) is usually 50 to 100% by weight, preferably 55 to 95% by weight from the viewpoint of improving the heat resistance of the sheet. %, More preferably 55 to 90% by weight.

  In the block copolymer composition (P) of the present invention, the content of the block copolymer (a2) is preferably 0 to 30% by weight, more preferably 0 to 26% by weight, particularly preferably 0 to 0%. 22% by weight. The content of the block copolymer (a3) is preferably 35 to 100% by weight, more preferably 40 to 95% by weight, and particularly preferably 40 to 85% by weight. The content of the block copolymer (a4) is preferably 0 to 50% by weight, more preferably 0 to 45% by weight, and particularly preferably 5 to 45% by weight. If the content of each block copolymer is within such a suitable range, the formability of the sheet and the smoothness of the sheet surface are good.

About the block copolymer (a) containing the coupling agent X, it is preferable that the average number of block copolymer (AB) couple | bonded with one coupling agent X is 2-3.8. That is, the content (% by weight) of each block copolymer represented by the general formulas (a2), (a3) and (a4) in the block copolymer composition (P) is W2, W3, respectively. And W4, it is preferable that the value of the following calculation formula (I) is in the range of 2 to 3.8.

(2 × W2 + 3 × W3 + 4 × W4) / (W2 + W3 + W4) (I)

  If the value of the formula (I) is 2 or more, the melt viscosity at the time of forming the sheet becomes appropriate, so that the sheet formability is excellent, while if it is 3.8 or less, the smoothness of the sheet surface is good. Become.

  The content of the aromatic vinyl monomer unit in the block copolymer (a) is preferably 5 to 50% by weight, more preferably 10 to 30% by weight, and particularly preferably 13 to 20% by weight. %. If the content of the aromatic vinyl monomer unit is 5% by weight or more, the hardness of the sheet is appropriate, and if it is 50% by weight or less, the heat resistance of the sheet is good.

  The weight average molecular weight of the block copolymer (A-B) portion of the block copolymer (a) is preferably 50,000 to 200, 200, because the balance between the smoothness of the sheet surface and the adhesiveness is good. 000, more preferably 55,000-150,000. Furthermore, since it is excellent in flow resistance, the weight average molecular weight of the polymer block (A) is preferably 5,000 to 50,000, more preferably 8,000 to 40,000.

The block copolymer (b) of the present invention is a block copolymer (A-B) comprising a polymer block (A) and a polymer block (B), but a single active block copolymer ( A block comprising a polymer block (A) and a polymer block (B) represented by the following general formula (1) or (2) obtained by reacting AB) with one molecule of a coupling agent A copolymer is also included in the block copolymer (b).
A-B-X (1)
X-A-B (2)

  The content of the block copolymer (b) is usually 0 to 50% by weight, preferably 5 to 45% by weight, more preferably 10 to 45% by weight in the block copolymer composition (P). is there. If the content is within such a range, the heat resistance of the sheet is good.

  The content of the aromatic vinyl monomer unit in the block copolymer (b) is preferably 5 to 50% by weight, more preferably 10 to 30% by weight, and particularly preferably 13 to 20% by weight. is there. If the content of the aromatic vinyl monomer unit is 5% by weight or more, the hardness of the sheet is appropriate, and if it is 50% by weight or less, the heat resistance of the sheet is good.

  The weight average molecular weight of the block copolymer (b) is preferably 50,000 to 250,000, and more preferably 55,000 to 200,000. If the weight average molecular weight is within such a suitable range, the melt viscosity at the time of sheet forming becomes appropriate, so that the sheet formability is excellent and the heat resistance of the sheet is also good.

  In the block copolymer (a) and the block copolymer (b), in particular, as A, a styrene polymer block is preferable, and as B, a butadiene polymer block, an isoprene polymer block, and hydrogen thereof. At least one selected from the group consisting of additives is preferable, and a polymer block of isoprene and / or a hydrogenated product thereof is more preferable.

  The block copolymer composition (P) of the present invention is produced by producing the block copolymers represented by the above general formulas (a2), (a3), (a4) and (b), respectively. The composition may be produced by mixing so as to satisfy the range, or a composition comprising a mixture of these block copolymers may be prepared in a series of polymerization operations, for example, according to the method described in WO 04/011551. You may manufacture by. The latter method is preferable in terms of excellent production efficiency.

  When hydrogenating the block copolymer contained in the block copolymer composition of the present invention, in accordance with a conventional method, for example, in a hydrogen atmosphere, a hydrogen-free block copolymer composition and a palladium catalyst are mixed. The hydrogenation reaction may be performed at room temperature to 250 ° C. for about 0.1 to 100 hours.

  As long as the effect of the present invention is not inhibited, the thermoplastic elastomer of the present invention includes, for example, known thermoplastic resins, fillers, reinforcing fibers, as components other than the block copolymer composition. Softener, antioxidant, flame retardant, antibacterial agent, light stabilizer, UV absorber, dye, pigment, lubricant, internal mold release agent, anti-blocking agent, slip agent, antistatic agent, crosslinking agent, crosslinking aid, Compounding agents such as a vulcanizing agent and a vulcanization accelerator may be appropriately contained. In that case, what is necessary is just to mix those components and a block copolymer composition suitably, and to obtain a thermoplastic elastomer.

  On the other hand, the plasticizer used in the step (1) is not particularly limited, but at least a plasticizer substantially compatible with the diene block contained in the thermoplastic elastomer is preferable.

  Known plasticizers can be used as appropriate. For example, hydrocarbon oils such as naphthene oil and paraffin oil; liquid polyolefins such as polybutylene and polybutene-1; liquid diene rubbers such as polyisoprene, liquid 1,2-polybutadiene and liquid 1,4-polybutadiene, and the like Liquid acrylonitrile-butadiene copolymer and its carboxylate; liquid styrene-butadiene copolymer and its carboxylate; low molecular weight polystyrene having a molecular weight of 3,000 or less; α-methylstyrene-vinyltoluene copolymer Examples include coalescence; petroleum resin; polyacrylate resin; polyester resin; polyterpene resin. The liquid state means a liquid state at least at room temperature (25 ° C.).

  Among them, as the plasticizer, liquid diene rubber is preferable because the swelling property by ink and the contamination property to the printing material are low when the photocured sheet is used for printing.

  The liquid diene rubber contains a conjugated diene monomer unit as a main constituent unit in the polymer chain, and the conjugated diene monomer unit content is preferably 80% by weight or more, What consists only of a body unit (100 weight%) is more preferable.

  The ratio (vinyl content) of vinyl bond units in the total amount of conjugated diene monomer units in the liquid diene rubber is not particularly limited, and is usually 50% by weight or less, preferably 20 from the viewpoint of maintaining good sheet flexibility. It is 5 weight% or less, More preferably, it is 5 to 10 weight%.

  The production method of the liquid diene rubber is not particularly limited, and generally known production methods can be employed. For example, a method of polymerizing a conjugated diene monomer using an anionic polymerization initiator in a polymerization solvent can be employed.

  Examples of the liquid diene rubber include those exemplified above, for example, butadiene-acrylonitrile copolymer, polychloroprene and the like. Of these, polyisoprene and polybutadiene are preferred, and polyisoprene is more preferred because of the low swellability with ink and low contamination to the printed material when the photocured sheet is used for printing.

  The weight average molecular weight of polybutadiene as a plasticizer is preferably 500 to 5,000. On the other hand, the polyisoprene has a weight average molecular weight of preferably 5,000 to 100,000, more preferably 10,000 to 50,000.

  Polyisoprene is preferably a homopolymer of isoprene, but is a copolymer of isoprene and other monomers copolymerizable with isoprene within a range that does not substantially impair the effects of the present invention. May be. Monomers that can be copolymerized with isoprene include conjugated diene monomers other than the above-mentioned aromatic vinyl monomers and isoprene. Examples of conjugated diene monomers include 1,2-butadiene, 1,3. -Butadiene and 1,3-pentadiene are preferred.

  The mixing method of the thermoplastic elastomer and the plasticizer in the step (1) is not particularly limited, but from the viewpoint of more uniformly dispersing the plasticizer in the thermoplastic elastomer, a method of kneading both components (kneading method), Alternatively, a method in which both components are dissolved in a solvent and mixed in a solution state and then the solvent is removed from the obtained solution (dissolution method) is preferable. From the viewpoint of further uniform dispersion, the dissolution method is More preferred.

  In the kneading method, the kneading may be performed using a known kneader, roll mill, Banbury mixer, single-screw or multi-screw extruder, preferably under an inert gas condition such as nitrogen. The temperature condition at the time of kneading is preferably 180 to 300 ° C, more preferably 185 to 280 ° C, and still more preferably 190 to 260 ° C, from the viewpoint of sufficient kneading of the thermoplastic elastomer and the plasticizer.

  In the dissolution method, first, a thermoplastic elastomer and a plasticizer are dissolved in the same or different solvents. Their dissolution order and dissolution method (for example, stirring, temperature conditions, etc.) are not particularly limited. When dissolved in the same solvent, mixing is performed by dissolving both components in the solvent. On the other hand, when dissolved in different solvents, mixing is performed by combining the solutions of the respective components. The solvent is then removed from the resulting solution. The concentration of the solute in the solution is usually 60% by weight or less, although it depends on the viscosity. The method for removing the solvent is not particularly limited. For example, the obtained solution is dropped into warm water (temperature is equal to or higher than the boiling point of the solvent) to volatilize the solvent, precipitate the solute, and dry the precipitate. The solvent may be removed from

  The solvent is not particularly limited as long as it can dissolve the thermoplastic elastomer and the plasticizer, but usually a volatile solvent such as toluene or cyclohexane is preferably used. In addition, when using a different solvent, it is preferable to use a solvent mutually compatible.

  By the step (1), a mixture of a thermoplastic elastomer and a plasticizer is obtained. The thermoplastic elastomer content in the mixture is preferably 50 to 98% by weight, more preferably 70 to 96% by weight, and still more preferably 85 to 94% by weight in terms of the amount of the block copolymer composition. The content of the plasticizer is preferably 2 to 50% by weight, more preferably 4 to 30% by weight, and still more preferably 6 to 15% by weight. The mixture may appropriately contain other components as described later as long as they do not inhibit the expression of the desired effect of the present invention.

  The plasticizer is generally used for the purpose of improving sheet formability, accelerating removal of an uncured portion, and adjusting the hardness of a photocured portion. In the mixture obtained in step (1) of the present invention, it is estimated that the plasticizer is sufficiently uniformly dispersed in the thermoplastic elastomer, and when used in the photosensitive elastomer composition, the smoothness of the sheet surface is improved. In addition to this, it can also improve properties such as flow resistance and low adhesion. Therefore, it can greatly contribute to the improvement of the performance of the photosensitive elastomer composition and is very useful for the preparation of the desired photosensitive elastomer composition. Therefore, as one embodiment of the present invention, there is provided a composition for preparing a photosensitive elastomer composition comprising a thermoplastic elastomer and a plasticizer. The suitable aspect regarding the thermoplastic elastomer and plasticizer which comprise the said composition is the same as that of the above.

  The composition for preparing a photosensitive elastomer composition of the present invention is produced by mixing a thermoplastic elastomer and a plasticizer as described above, for example, according to the method described in JP-A-2003-261740. By a series of polymerization operations, it can also be produced as a mixture of a thermoplastic elastomer [for example, a block copolymer composition (P)] and a plasticizer (for example, polyisoprene).

  In the step (2), the mixture obtained in the step (1), the photosensitive ethylenically unsaturated compound, and the photopolymerization initiator are mixed.

  There is no limitation in particular as a photosensitive ethylenically unsaturated compound used at a process (2), What is necessary is just to use a well-known thing. Examples of the compound include diacrylates or dimethacrylates of dihydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, 1,4-butanediol, and 1,6-hexanediol. Triacrylate or trimethacrylate of trimethylolpropane; tetraacrylate or tetramethacrylate of pentaerythritol; N, N′-hexamethylenebisacrylamide, N, N′-hexamethylenebismethacrylamide, diacetone acrylamide, diacetone methacrylamide, Styrene, vinyl toluene, divinyl benzene, diallyl phthalate, triallyl cyanurate and the like can be mentioned.

  There is no limitation in particular as a photoinitiator used at a process (2), What is necessary is just to use a well-known thing. Examples of the initiator include benzophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, α-methylbenzoin, α-methylbenzoin methyl ether, α-methoxybenzoin methyl ether, benzoin phenyl. Ether, α-t-butylbenzoin, anthraquinone, benzanthraquinone, 2-ethylanthraquinone, 2-chloroanthraquinone, 2-2'-dimethoxyphenylacetophenone, 2,2-diethoxyphenylacetophenone, 2 , 2-diethoxyacetophenone, piperoin and the like.

  The mixing method of the predetermined component in the step (2) is not particularly limited. Examples thereof include a method of kneading predetermined components using a kneader, a roll mill, a Banbury mixer, a single-screw or multi-screw extruder, and the like. The mixing temperature is not particularly limited, but is usually about 100 to 150 ° C. The mixture thus obtained is formed into a sheet-like molded article having a desired thickness by using a molding machine such as a single-screw or multi-screw extruder, a compression molding machine, or a calender molding machine, if desired. Also good. Such a sheet-like molded product is suitable as a flexographic plate composition. In the case of using a single-screw or multi-screw extruder, preparation of the photosensitive elastomer composition and molding into a sheet-like molded product can be performed simultaneously.

  Further, the mixing in the step (2) is carried out by dissolving a predetermined component in a solvent state such as cyclohexane, chloroform, carbon tetrachloride, trichloroethane, diethyl ketone, methyl ethyl ketone, benzene, toluene, tetrahydrofuran, and the like. You may carry out by evaporating a solvent from the obtained solution. For example, a sheet-like molded article suitable as a flexographic plate composition can be produced by injecting the obtained solution into a frame mold and evaporating the solvent.

  In addition, as thickness of the said sheet-like molded object, it is 0.1-20 mm normally, Preferably it is 1-10 mm.

  From the above, a photosensitive elastomer composition having desired properties is obtained, preferably as a sheet-like molded product. Such compositions are encompassed by the present invention. The composition preferably has a plasticizer content of 2 to 50% by weight, a photosensitive ethylenically unsaturated compound content of preferably 2 to 60% by weight, and a photopolymerization initiator. A composition having a content of preferably 0.1 to 5% by weight and the balance being a thermoplastic elastomer is suitable.

  In order to prevent the molded product from being contaminated or damaged during storage or operation, the surface of the molded product is a transparent sheet or film made of a resin such as polypropylene, polyethylene, or polyethylene terephthalate. You may provide as a sheet layer or a protective film layer.

  Furthermore, a thin covering material layer rich in flexibility may be provided on the surface of the sheet-like molded product in order to suppress the adhesiveness of the surface and to enable reuse of the negative film after light irradiation. . In this case, after the exposure of the sheet-like molded product is completed, when the unexposed portion is removed with a solvent, the coating material layer must also be removed at the same time. As the coating material layer, soluble polyamide, cellulose derivative and the like are usually used.

  When the above-mentioned photosensitive elastomer composition is used as a flexographic plate composition, the photosensitive elastomer composition includes, for example, a thermal polymerization inhibitor, an antioxidant, an ozone crack inhibitor, a dye as a component other than the above-described constituent components. , Pigments, fillers, additives exhibiting photochromism, reducing agents, agents for improving the relief structure, crosslinking agents, flow improvers, mold release agents and the like may be further included. Other components may be appropriately mixed with the predetermined component of the present invention in the mixing step of step (1) and / or (2) within a range not inhibiting the expression of the desired effect of the present invention.

  As described above, the photosensitive elastomer composition of the present invention is obtained by previously obtaining a mixture of a thermoplastic elastomer and a plasticizer, and further mixing the mixture, the photosensitive ethylenically unsaturated compound, and a photopolymerization initiator. It is obtained. Therefore, it is presumed that the photosensitive elastomer composition contains a thermoplastic elastomer and has a high viscosity, but nevertheless the plasticizer is in a sufficiently uniformly dispersed state throughout. Thereby, the photosensitive elastomer composition of the present invention exhibits excellent sheet surface smoothness and flow resistance, and has low adhesiveness. In addition, a flexographic plate having excellent fine line resolution can be provided.

2. Flexographic Plate The flexographic plate of the present invention is obtained by exposing a sheet-like molded product of the photosensitive elastomer composition of the present invention.

  The method for producing the flexographic plate is not particularly limited. For example, the flexographic plate is produced according to the following steps.

(1) It is cured by irradiating light from the base sheet side of a multilayer sheet comprising a protective film, a sheet-like photosensitive elastomer composition layer and a base sheet until reaching a specific thickness of the photosensitive elastomer composition layer. Let
(2) The protective film is peeled off, and a negative film is adhered instead, and the photosensitive elastomer composition layer is exposed by irradiating light with a wavelength of 230 to 450 nm, preferably 350 to 450 nm, from above the negative film. By this exposure, the light transmitting portion of the photosensitive elastomer composition layer is cured.
(3) Since the unexposed portion of the photosensitive elastomer composition layer is in an uncured state, the portion is removed (development).
(4) In (3), since the uncured portion is usually removed using a solvent, the solvent remaining in the flexographic plate is dried.
(5) Post-exposure if desired.

  In the development (removal of unexposed part) step (3), for example, the following solvents are preferably used.

  Examples of the solvent include aliphatic hydrocarbons or aromatic hydrocarbons such as n-hexane, n-heptane, octane, petroleum ether, naphtha, limonene, terpene, toluene, xylene, ethylbenzene, isopropylbenzene; acetone, methyl ethyl ketone, and the like. Ketones; ethers such as di-n-butyl ether and di-t-butyl ether; esters such as methyl acetate and ethyl acetate; halogens such as methylene chloride, chloroform, trichloroethane, tetrachloroethylene, dichlorotetrafluoroethane, and trichlorotrifluoroethane And hydrocarbons. Furthermore, a desired amount of an alcohol such as methanol, ethanol, isopropanol, or n-butanol can be added to the solvent and used.

  The development can be speeded up by applying a mechanical force using a brush or the like in the presence of the solvent.

  Since the flexographic plate of the present invention is excellent in the resolution of the fine line of the negative film and has an appropriate flexibility, according to the flexographic plate, it is not affected by the material and surface shape of the substrate, High-quality flexographic printing can be performed.

  Examples of the printed material include paper, cardboard, wood, metal, polyethylene film, polyethylene sheet, polypropylene film, polypropylene sheet, and the like. The flexographic plate of the present invention can be suitably used for various things.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited only to this Example. In the following, “part” and “%” are based on weight unless otherwise specified. Measurement and evaluation were performed as follows.

(Weight average molecular weight)
It was measured by gel permeation chromatography analysis using tetrahydrofuran as an eluent, and the weight average molecular weight was determined as a standard polystyrene equivalent value.

(Content of each block copolymer)
Measured by gel permeation chromatography analysis using tetrahydrofuran as an eluent. From the measurement chart, a styrene-isoprene diblock copolymer and two styrene-isoprene diblock copolymers were bonded via a coupling agent. Coupling body (two-branch body), coupling body (three-branch body) in which three styrene-isoprene diblock copolymers are bonded via a coupling agent, and four styrene-isoprene diblock copolymers are coupled The peak area corresponding to the coupling body (4-branched body) bonded through the agent was obtained, and the content of each block copolymer was calculated.

[Numerical calculation using formula (I)]
From the result of the above (content of each block copolymer), the contents of the bifurcated body, the 3-branched body and the 4-branched body in the block copolymer composition are W2, W3 and W4, respectively, and the calculation formula ( The value was calculated based on I).

(Styrene unit content)
The styrene unit content was determined by ¹ H-NMR analysis.

(Vinyl content)
The vinyl content was determined by ¹ H-NMR analysis.

(Smoothness of sheet surface)
Place the photosensitive elastomer composition in a sheet-shaped mold with a spacer thickness of 3 mm, sandwich the top and bottom with a polyester film (protective film) with a thickness of 0.1 mm, and heat-press at 110-130 ° C. for 10 minutes with a press machine The sheet was cooled to form a sheet having a thickness of 3 mm. Thereafter, the polyester film on the upper surface of the sheet was peeled off, and the surface state of the sheet after being allowed to stand at room temperature for 24 hours was observed with the naked eye, and the smoothness of the sheet surface was evaluated according to the following evaluation criteria. The number of samples in each composition was 10.
〔Evaluation criteria〕
5 points: The surface is smooth for all samples. 4 points: There is one sample having a small uneven surface shape. 3 points: There is one or more samples having an uneven surface shape. 2 points: Large uneven surface. There are one or more samples having a shape. 1 point: A clean sheet cannot be formed.

(Flow resistance under load)
The photosensitive elastomer composition was kneaded by a roll mill to form a sheet having a thickness of 2.3 mm. It was sandwiched between polyester films with a thickness of 100 μm, placed inside a spacer with a thickness of 2 mm, heated and pressed at 120 ° C. for 10 minutes with a press machine, and then cooled to form a sheet with a thickness of 2 mm. Five sheets obtained were stacked to 10 mm (initial value), and deformed and held to a thickness of 8 mm accurately. After leaving it to stand at room temperature for 22 hours, it was opened, and after standing for another 30 minutes, the thickness (measured value) of five sheets was measured. The following formula:

Deformation rate (%) = (Measured value−Initial value) ÷ (Initial value−8) × 100

Thus, the deformation rate was obtained. According to the obtained deformation rate, the flow resistance under load was evaluated according to the following evaluation criteria.
〔Evaluation criteria〕
○: Deformation rate is less than 15% and excellent in flow resistance ×: Deformation rate is 15% or more and inferior in flow resistance

(Sheet adhesion)
A sheet was obtained in the same manner as in the evaluation of (the smoothness of the sheet surface), and the polyester film on the upper surface was peeled off to expose the surface of the photosensitive elastomer composition. By touching the surface with a finger, the tackiness of the sheet was evaluated according to the following evaluation criteria.
〔Evaluation criteria〕
○: Adhesiveness has no problem in practical use Δ: Slightly sticky ×: Easy to stick in, practically problematic

Reference example 1
In a pressure-resistant reactor, 112 parts of cyclohexane, 0.0012 parts of N, N, N ′, N′-tetramethylethylenediamine (TMEDA) and 7.2 parts of styrene were added and stirred at 40 ° C. 0.0441 parts of butyl lithium was added, and polymerization was carried out for 1 hour while raising the polymerization temperature to 50 ° C. At this time, the polymerization conversion of styrene was 100%. A part of the reaction solution was collected, and the weight average molecular weight of the polystyrene block was measured. The results are shown in Table 1.

  Subsequently, 40.8 parts of isoprene were continuously added over 1 hour. After completing the addition of isoprene, polymerization was continued for an additional hour. The polymerization temperature was controlled to maintain 50-60 ° C. The polymerization conversion rate at this point was 100%. A part of the reaction solution was sampled, and the weight average molecular weight of a styrene-isoprene diblock copolymer (corresponding to the block copolymer (b)) was measured. The results are shown in Table 1.

  Next, 0.0254 parts of tetramethoxysilane was added as a coupling agent, and a coupling reaction was performed for 2 hours. A coupling body in which a styrene-isoprene diblock copolymer was bonded via a coupling agent [block copolymer Corresponding to (a)]. Thereafter, 0.0661 part of methanol was added as a polymerization terminator and mixed well to stop the reaction.

  Thus, a reaction solution containing a styrene-isoprene block copolymer composition (block copolymer composition) was obtained. A part of the reaction solution is collected to measure the weight average molecular weight of the entire block copolymer composition, the styrene unit content and the vinyl content in the composition, and the content and calculation of each block copolymer. The value of formula (I) was determined. The results are shown in Table 1.

  After adding 0.3 part of 2,6-di-t-butyl-p-cresol as an antioxidant to 100 parts of the solid content to the obtained reaction liquid, the solution is heated to 85 to 95 ° C. little by little. The solvent was volatilized by dropping into the warm water. The precipitate was pulverized and dried with hot air at 85 ° C. The obtained pulverized product was supplied to a single screw extruder equipped with an underwater hot cut device at the tip of the extruder to obtain pellets having an average diameter of 5 mm.

Reference example 2
Pellets were obtained in the same manner as in Reference Example 1 except that the types of styrene, n-butyllithium, TMEDA, isoprene, coupling agent (dimethyldichlorosilane) and amount, and the amount of methanol were changed as shown in Table 1. The results are shown in Table 1.

Reference example 3
In a pressure-resistant reactor, 112 parts of cyclohexane, 0.0036 parts of TMEDA and 0.134 parts of n-butyllithium were added, and 48 parts of isoprene were added over 1 hour while raising the polymerization temperature to 60 ° C. while stirring at 40 ° C. After completion of the addition, polymerization was further performed at 60 ° C. for 1 hour. The polymerization conversion rate of isoprene was 100%. Thereafter, 0.2 parts of methanol as a polymerization terminator was added to the reactor and mixed well to stop the reaction, and polyisoprene was obtained. Polyisoprene was liquid and its weight average molecular weight was 40,000.

Example 1
100 parts of pellets of Reference Example 1 (styrene-isoprene block copolymer composition) as a thermoplastic elastomer, 10 parts of liquid polyisoprene of Reference Example 3 as a plasticizer, and 2,6-di-t-butyl-p-cresol 2 parts are dissolved in cyclohexane and mixed in a solution state, and then the mixed solution is dropped little by little into warm water heated to 85 to 90 ° C. to volatilize the solvent, and the resulting precipitate is pulverized to 85 ° C. The solvent was removed by drying with hot air (premixing).

  To the obtained mixture, 5 parts of 1,4-butanediol diacrylate, 4 parts of hexanediol dimethacrylate, 0.01 part of methylhydroquinone and 0.8 part of benzoin isopropyl ether were added and kneaded at 130 ° C. An elastomer composition was obtained. Table 2 shows the evaluation results for the sheet surface smoothness, flow resistance under load, and sheet adhesiveness of the photosensitive elastomer composition.

Example 2
100 parts of the pellets of Reference Example 1, 10 parts of the liquid polyisoprene of Reference Example 3 as a plasticizer, and 2 parts of 2,6-di-t-butyl-p-cresol at 200 ° C. using a kneader-kneader. Kneaded (preliminary mixing).

  Subsequently, the kneading temperature is lowered to 130 ° C., 5 parts of 1,4-butanediol diacrylate, 4 parts of hexanediol dimethacrylate, 0.01 part of methylhydroquinone and 0.8 part of benzoin isopropyl ether are added and kneaded. A photosensitive elastomer composition was obtained. Table 2 shows the evaluation results for the sheet surface smoothness, flow resistance under load, and sheet adhesiveness of the photosensitive elastomer composition.

Example 3
A photosensitive elastomer composition was obtained in the same manner as in Example 1 except that the plasticizer was changed to liquid polybutadiene (manufactured by Nippon Soda Co., Ltd., NISSO-PB-B-1000). Table 2 shows the evaluation results for the sheet surface smoothness, flow resistance under load, and sheet adhesiveness of the photosensitive elastomer composition.

Example 4
A photosensitive elastomer composition was obtained in the same manner as in Example 1 except that the pellet of Reference Example 1 was changed to that of Reference Example 2. Table 2 shows the evaluation results for the sheet surface smoothness, flow resistance under load, and sheet adhesiveness of the photosensitive elastomer composition.

Comparative Example 1
100 parts of pellets of Reference Example 1, 10 parts of liquid polybutadiene as plasticizer, 2 parts of 2,6-di-t-butyl-p-cresol, 5 parts of 1,4-butanediol diacrylate, 4 parts of hexanediol dimethacrylate Then, 0.01 part of methylhydroquinone and 0.8 part of benzoin isopropyl ether were kneaded at 130 ° C. using a kneader kneader to obtain a photosensitive elastomer composition. Table 2 shows the evaluation results for the sheet surface smoothness, flow resistance under load, and sheet adhesiveness of the photosensitive elastomer composition.

Comparative Example 2
A photosensitive elastomer composition was obtained in the same manner as in Comparative Example 1 except that the plasticizer was changed to the liquid polyisoprene of Reference Example 3. Table 2 shows the evaluation results for the sheet surface smoothness, flow resistance under load, and sheet adhesiveness of the photosensitive elastomer composition.

  Table 2 shows the following. That is, the pre-mixing of the thermoplastic elastomer (block copolymer composition) and the plasticizer was not performed. In Comparative Examples 1 and 2, although the sheet surface was excellent in smoothness, the flow resistance under load and the sheet While inferior in adhesiveness, in Examples 1 to 4 in which premixing was performed, the smoothness of the sheet surface, the flow resistance under load and the adhesiveness of the sheet are all excellent.

According to the present invention, it is possible to efficiently produce a photosensitive elastomer composition that is excellent in the smoothness of the sheet surface and the flow resistance, in particular, the flow resistance when there is a load from the surface direction of the sheet and has low adhesion. can do. Further, an excellent flexographic plate can be obtained by the composition.

Claims (6)

(1) a step of mixing a thermoplastic elastomer and a plasticizer, and (2) a step of mixing the mixture obtained in step (1), a photosensitive ethylenically unsaturated compound and a photopolymerization initiator,
The manufacturing method of the photosensitive elastomer composition which has these.   The manufacturing method of the photosensitive elastomer composition of Claim 1 which performs a process (1) on 180-300 degreeC temperature conditions.   The method for producing a photosensitive elastomer composition according to claim 1, wherein the step (1) is performed by dissolving and mixing the thermoplastic elastomer and the plasticizer in a solvent and removing the solvent from the obtained solution.   The photosensitive elastomer composition obtained by the manufacturing method of the photosensitive elastomer composition in any one of Claims 1-3.   A composition for preparing a photosensitive elastomer composition comprising a thermoplastic elastomer and a plasticizer. A flexographic plate formed by exposing the photosensitive elastomer composition according to claim 4 to light.