JPS5876828A - Photosensitive resin composition - Google Patents

Abstract

PURPOSE:To obtain a flexographic printing plate having low hardness and rubber elasticity by using a compsn. consisting of a specific urethane prepolymer, a cross-linking agent and a photosensitizer. CONSTITUTION:A photosensistive resin compsn. is constituted of an urethane prepolymer A of 2,000-3,000 average mol.wt. of which the prepolymer main chains are drived from a polyole component contg. terminal hydroxy polyester of 500-3,000 average mol.wt. and a diisocyanate component consisting essentially of the component expressed by a formula (1), and of which both terminals are bound with said main chains by urethane bonds and have >=1 photopolymerizable double bonds, an urethane prepolymer B which is the same as said polymer except that one of both terminals is bound with said main chains by urethane bonds, a cross-linking agent C having >=1 photopolymerizable double bonds in the molecules, and a photosensitizer D.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photosensitive resin composition! ! In detail, a rubber elastic body is formed by forming a three-dimensional structure through the action of actinic rays, *
The present invention relates to a photosensitive resin composition that provides high quality flexographic printing plates.

The printing plates used in 7-Size printing are generally manufactured using rubber by hand engraving or casting methods. However, these methods require a great deal of time and effort.

In recent years, however, a method of producing a 7-inch printing plate using a photosensitive resin has been studied and proposed. However, when printing cardboard using conventional printing plates, the surface of the cardboard is generally rough and wavy, so corrugations are likely to occur in the printed matter, and there are considerable restrictions on the type of cardboard that can be printed, the ink that can be used, etc. There is the problem of receiving. In order to solve this problem, it is necessary to have a low hardness of 3s to 46 (Shore A) and rubber elasticity.

Conventionally, polyurethane-based plates using tolylene diisocyanate are known as low-hardness flexographic printing plates. However, this Incineration F is a 5% chemical substance under the so-called Safety and Health Act! Yes, corresponding pipe facilities are required for safety and health management.

The present inventors have developed a low-hardness type photosensitive resin that does not require the use of such special iso-/71-), a photosensitive resin composition that provides #7 Lexo printing plates with high tensile strength and low hardness. As a result of intensive research, we have arrived at the present invention.

That is, 1 the present invention provides (Al prepolymer main chain has an average molecular weight of 500 to &
It is derived from a polyol component containing a 000-stranded polyester and a diisocyanate component mainly consisting of a compound represented by the following formula % formula % (11), with both ends bonded to the main chain and the urethane bond. A urethane prepolymer having an average molecular weight of λ000 to &ooo and consisting of a group having at least one photopolymerizable double bond, CB1 Prepolymer main chain has an average molecular weight of 500 to &000
It is derived from a polyol component containing a 00-terminated HcI-oxypolyester and a diisocyanate component mainly containing a compound represented by the formula The group consists of a group having at least one double bond.

This is a photosensitive resin composition characterized by comprising a urethane prepolymer with an average molecule of *zooo to aooo, a crosslinking agent having at least one photopolymerizable double bond in the molecule, aiJlt, and a sensitizer.

Urethane prepolymer of component A used in the present invention [hereinafter referred to as
[referred to as urethane prepolymer A] is derived from a polyol component whose prepolymer main chain contains a terminal human-oxypolyester having an average molecular weight of 500 to zooo and a diincyanate acid component mainly consisting of a compound represented by the formula (11), The urethane prepolymer A is a urethane prepolymer having an average molecular weight of λooo-aooo. A polyol containing a terminal hydroxy polyester or its urethane-forming derivative is reacted with a diisocyanate mainly consisting of a compound represented by formula (11) to form a molecular main chain having free isocyanate groups at both ends, and then the free isocyanate group is formed. It can be produced by reacting with a compound having a hydroxyl group such as an incyanate group and containing a photopolymerizable double bond, particularly an ethylenic double bond.

The terminal hydroxy polyester of the bool is preferably a linear saturated polyester which is derived from a diol component and a dicarboxylic acid component and whose polyol ends are hydroxyl groups, or a 4IK or II saturated aliphatic polyester. For example, polyethylene 7-dipate.

Examples include polybutylene 7 dibate, polybentamethylene adipate, polyethylene-butylene 7 dibate, polyethylene diethylene adipate, and the like. Such polyester needs to have an average molecular weight of SOO to &OOO. If the average molecular weight falls outside of this range, the urethane prepolymer will not function as a soft segment, which is undesirable.

Moreover, polyether glycol can be used as one component of the polyol. When polyether glycol is used in combination, the resin composition Kjlt Aqueous 41 can be given the property of being easily dispersed in an aqueous solution of an ionic surfactant. Therefore the use of polyether glycol and its proportions.

Required properties C of the resin composition (e.g., developability in aqueous solvents: swellability in water, aqueous inks, etc.).

When using polyether glycol in combination, which can be determined in consideration of the intended use, the polyether glycol component should be bound at an average rate of 1 molecule or less per molecule of the urethane prepolymer main chain, and at a ratio of 1lIKat-α7 molecules, and When the ratio of the molecular weight of the polyester to the molecular weight of the polyether glycol is in the range of aS to t, S, *, α8 to 13, the action of the polyether glycol is significantly expressed, so it is preferable 8. When the number of bonds is on average more than one in five molecules in the main chain of the urethane prepolymer.

Increased degree of swelling with water and water-based ink, water resistance,
Ink resistance decreases, and if there are fewer than three on one side, development with a hydrogen solvent becomes impossible, and development only with so-called organic solvents such as acetone, tritrethane, trichloroethylene, etc. is possible. Therefore, when a photosensitive resin composition containing polyether glycol is irradiated with actinic rays through a negative or positive film having a transparent image, and the unexposed areas are eluted and removed with a 3JL solution, when using a water-based solvent, the surfactant A dissolution image can be formed extremely easily with an aqueous solution of the agent, and the resulting resin plate exhibits excellent resolution.
Moreover, it has the characteristic of being excellent in water resistance.

Examples of such polyether glyfur include polyethylene glycol, polypropylene glycol, polybutylene glycol, oxyethylene-based oxypropyl copolymer, oxyethylene-oxybutylene copolymer, and the like. The molecular weight of this polyether glycol is K, which is the same as the above polyester.

It is preferably 1%00 to λ000.

! ! Furthermore, the polyol component constituting the main chain of the urethane prepolymer is the polyester.

Alternatively, a mixed component of the polyester and the polyether glycol is preferred, but any polyol conventionally used as a polyol component of polyurethane can be used as long as the object of the present invention is not impaired.

The diisocyanate used to form the main chain of the urethane prepolymer A in the present invention is a diisocyanate mainly containing a compound represented by the above formula +11. In the formula (1), R is 7enylene or cyclohexylene which may have a lower alkyl group, and the lower alkyl group also includes a lower alkyl group substituted with /\logen.

Such lower alkyl groups include methyl and ethyl.

Examples include cool methyl.

More specifically, the compound (diisocyanate) represented by the formula (11) can be represented by the following formula f21.+31.

Among these, those in which R' is a hydrogen atom are preferable.
Preferably, the methylene groups are in meta or para positions nlc to each other.

Various types of polyisocyanates are known, but the above type 1 12! (Those that do not contain the diisocyanate shown in 31 as the main component are undesirable in the next egg.)
For example, compositions using diphenylmethane (4'-diisocyanate) have somewhat low comparability and high viscosity, and their cured products have high hardness but relatively low tensile strength. Furthermore, in the case of isophorone diisocyanate, the viscosity of the composition is somewhat high (and the tensile strength of the photocured product is low), and in the case of hexamethylene diisocyanate, the low-temperature comparability of the composition is low.

However, these incyanates can be used as part of the diisocyanate component of the present invention as long as it does not contradict the purpose of the present invention.

The ethylenic double bond gold compound having a hydroxyl group used in the production of the urethane prepolymer A of the present invention includes 2-
Hydroxyethyl acrylate, 2-hydroxyethyl methacrylate.

2-hydroxypropyl acrylate), 2-hydroxypropyl methacrylate, polyethylene glyfur monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol heptanoacrylate, polypropylene glycol methacrylate, trimethylolpropane diacrylate , trimethylolpropane dimethacrylate, glycerin diacrylate, glycerin dimethacrylate, and the like. Among these, the first four (4IK) are preferred because they provide a photocured product with high tensile strength.

Such a compound is bonded to both ends of the soap main chain by a reaction between a free isocyanate group remaining in the production of the prepolymer main chain and a hydroxyl group of the compound, that is, a urethanization reaction.
Both ends of prepolymer A are formed. In that case, 1. For example, when 2- and tokidiethyl acrylate are used, both ends of the prepolymer are each composed of a group having one photopolymerizable double bond, and when glycerin dimeta-7 acrylate is used, both ends of the prepolymer are each consists of a group having two photopolymerizable double bonds.

The urethane prepolymer c (hereinafter referred to as urethane prepolymer B) used in the present invention is a polyol component whose prepolymer main chain contains a terminal hydroxy polyester with an average molecular weight of SOO to &000, and a compound represented by formula (1). Derived from the main diisocyanate component,
One of its both ends is bonded to the main chain through a urethane bond, and furthermore, it consists of a group having at least one photopolymerizable double bond. - Average molecular weight λ000-3oo.

is a urethane prepolymer. Preferably, such urethane prepolymer B is produced simultaneously with the urethane prepolymer, for example, a polyol containing a terminal hydroxy polynisder or its urethane-forming alligator body, and a diisocyanate mainly containing a compound represented by formula (11). are reacted to form a molecular main chain having both terminal Ka incyanate groups, and then the free incyanate groups are converted into a molecule having a hydroxyl group and containing a photopolymerizable double bond, especially an ethylenic double bond. It can be produced by blocking the reaction with a mixture of a compound and a hydroxyl group-containing compound having no double bond.

As the polyol component, diisocyanate component, and compound having a hydroxyl group and containing a photopolymerizable double bond to be used in the production of urethane prepolymer B, each of the components described for urethane prepolymer A can be used. Furthermore, regarding the main chain of the prepolymer, what has been explained regarding the main chain of the urethane prepolymer A can be applied as is.

Urethane prepolymer B is different from urethane prepolymer A in that it has a terminal structure, that is, only one end of the prepolymer has fewer photopolymerizable double bonds (both have one group).
It can have a structure similar to that of .

One end of the urethane prepolymer B consists of a group having few (one) photopolymerizable double bond, while the other end consists of a group having no mirror photopolymerizable double bond.More preferably, free in The other terminal of the urethane prepolymer B, that is, the terminal consisting of a group without a photopolymerizable double bond, is formed by a hydroxyl group-containing compound having no double bond in the above production method. It can be formed by reacting with free incyanate groups in the prepolymer main chain. Hydroxyl group-containing compounds without such double bonds include ethyl alcohol, isopropyl alcohol, phthyl furfur, methyl cellosolve, diethyl cellosolve, and methyl cellosolve. - Monohydric alcohols such as bitol, ethyl carbitol, etc.; dihydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, etc.;
Examples include trihydric alcohols such as fy serine; high molecular weight polyols (eg, terminal hydroxypolyesters, polyether glycols, etc.). Wear.

Specific examples of the terminal hydroxypolyester and polyether glycol include those explained as the constituent components of prepoly-v-main s.

Both the ginrethane prepolymers A and B used in the present invention have an average molecular weight of λ000 to a, ooo, preferably &
00G ~7. 0 molecular weight which is Goo is zoo.

If it is less than that, both hardness and tensile strength will increase.

Reverse 211. When it is larger than ooo, the viscosity becomes high and it is not suitable for practical use.

The usage ratio of urethane prepolymer A and urethane prepolymer B is A/B (molecular ratio): a! 5 to 4,
More preferably, αS is 3. If this ratio is less than aZS, the hardness is high.

If it is larger than 4, the hardness will be low, but the tensile strength will be low and the elasticity will be poor. Further, the total amount of urethane prepolymers A and B is 40 to 90% by weight based on the total amount of the prepolymer and crosslinking agent.

Preferably it is go to 80% by weight. Prepolymer is 9
If it is more than 0% by weight, the viscosity of the composition will be high, and if it is less than 40% by weight, the elongation and softness will be low.

The urethane prepolymer used in the present invention can be prepared by a conventionally known method.

For example, a polyol block composition is synthesized in the presence of excess incyanate, and an ethylenic double bond gold compound having a hydroxyl group is reacted using the reactivity of the terminal incyanate.

Furthermore, the remaining incyanate is reacted with the same amount of polyol (C) to produce ink, which is simultaneously obtained in the main chain of the prepolymer.

In addition to the urethane prepoly 1-, the composition of the present invention contains, as component C, an additive having at least one photopolymerizable double bond and an ethylenic double bond within minutes ÷ i (1). .

Preferred specific examples of such crosslinking agents include polyethylene glycol diacrylate, polypropylene glycol diacrylate, polyethylene dalycol monoacrylate, polypropylene glycol heptanoacrylate, methoxypolyethylene glycol acrylate, ethoxypolyethylene glycol acrylate, polyethylene glycol monoacrylate, and polypropylene gel v3. - monoacrylates and their methacrylates, lauryl methacrylate.

Examples include N-methylacrylamide, diallyl phthalate, diallyl isophthalate, and the like.

The amount of such a crosslinking agent is 10 to 60% by weight based on the total amount of the urethane prepolymer and crosslinking agent of the present invention.

Preferably it is 20 to 50% by weight. If it is less than 10% by weight, the viscosity of the assembled product will increase.

If it exceeds 60% by weight, the elongation, softness, etc. of the cured product will decrease.

In addition to the key Pulpo 91- and crosslinking, the resin composition of the present invention includes, as component D,
Contains a photosensitizer. Preferred photosensitizers include benzoin, benzoin ethyl ether, benzoin isopropyl ether, dimethylbenzyl ketal, benzophenone, and anthraquinone, which are well known in the art.

Such a photosensitizer includes a urethane prepolymer and a crosslinking agent in a total amount of 1
It is preferable to contain 51 parts by weight based on 00 parts by weight.

Furthermore, the composition of the present invention may contain a polymerization inhibitor such as hydroquinone, methoxyphenol, N-nitrodiphenyl, etc. in addition to the photosensitizer.

In addition, in the photosensitive resin composition of the present invention, physical properties may be improved,
A variety of agents are available without any problems.

Softeners can be added. As an example.

Dioctyl chloride, polyester lubricant.

There are epoxy lubricants, polypropylene dalicol, etc.

When producing a -7 lexo printing plate using the photosensitive resin composition of the present invention, it is carried out as follows.

That is, after forming the photosensitive resin composition of the present invention to a certain thickness, active light having a wavelength of m0OOA to 7000 A is irradiated through a negative (or positive) film having a transparent image to form an image. That is, the non-image area is dissolved and removed with an aqueous solution of tricμloethane, tricloethylene, alcohol, and surface-active steel to form a printing plate, and after drying, a 7 lexo printing plate is obtained either as it is or after being lined with rubber or the like. In addition, after the relief treatment, actinic light may be further irradiated to promote curing of the resin.

The flexographic printing plate made of the photosensitive resin composition of the present invention exhibits low hardness, excellent rubber elasticity, and high tensile strength and elongation, as well as good water resistance, ink resistance, ink transferability, resolution, and printing durability. In good condition, it is possible to print, for example, 300,000 copies or more of flexible prints.

Furthermore, the photosensitive resin composition of the present invention can be used not only for flexible printing but also as various elastomers that are cured by active light.1 For example, paints.

It can be used for coating agents, adhesives, film sheet materials, impregnated materials, other molded products, etc. Examples of the present invention are shown below, but these are merely illustrative, and the scope of the present invention is not limited. It's not a thing.

Examples 1 to 3 and Comparative Examples 1 and 2 Terminal hydroxy polybutylene adipate (molecule i1@2
00G) 3000,9 (15 mol) k Hydrogenated m-xylylene diinocyanate C molecular weight 194) sszJF (3 mol) was added, and further oxyethylene-oxyethylene-oxyethylene-oxyethylene a pyrenebutsuuku copolyether C molecular weight approx. 2000) 1000
1 (o, t5 mol 1) was added and reacted at 7G for 2 hours.Then, the 1 reaction temperature was lowered to 70'ek: 1 reaction mixture.
Kl! After adding 2-hydroxypropyl methacrylate in an amount shown by IK, dibutyltin dilaurate in an amount of 05% α, and P-methoxyphenyl in an amount of 1% tFo and o, the mixture was allowed to react for 2 hours. Subsequently, warmed polyethylene diethylene adipate (molecular weight approximately 20
001 was added in an amount shown in the table s%c, and the reaction was further continued for 2 hours.

The properties of the obtained urethane prepolymer are shown in Table 1k.

Table 1 * 2HP is an abbreviation for 2-hydroxypropyl methacrylate ※ * PIDEA is an abbreviation for polyethylene diethylene adipate * ◆ Molecular weights of urethane preposimers A and H determined from the raw material charging ratio.

Urethane Bre 1 polymer (mixture of urethane prepolymer A and urethane prepolymer B) obtained above
Polypropylene glycol monomethacrylate C molecular weight approximately 400) as a lK crosslinking agent! OII, dibutylene glycol dimethacrylate 3JI and diallyl phthalate 7JI were added, and penzoin imp apylether α8JF as a photosensitizer and P-methoxyphenol ao1JL were added as a stabilizer, and the mixture was stirred at 60°C for 30 minutes. A photosensitive resin composition was manufactured by III.

The photosensitive resin composition was then applied onto a tzoA polyethylene terephthalate film coated with a Haley silane prevention layer on the back side of the support paste.

Apply a uniform layer of 12μm to a thickness of a8cm.
Covered with a polyethylene terephthalate film, a negative film with a dumbbell shape for measuring physical properties was tightly placed on top of it, and the unexposed area of the 0th order was exposed to light through the negative film for 6 minutes with a SOW Kelcal lamp. % Rakkuru 1 It was removed with a developer of an aqueous solution of sodium sulfate, dried in hot air in the UK, and then peeled off in relief in the shape of a dumbbell from the support paste to measure its physical properties. Shore hardness was measured by stacking S sheets of these dumbbells and placing them on rubber having a Shore A hardness of 4 aim. The results are shown in Table 2.

Table 2 From Table 2, Examples 1 to 3 exhibit low hardness and excellent rubber elasticity, while Comparative Example 1 has high strength.

It can be seen that Comparative Example 2 has low hardness, low strength, and poor elasticity.

Examples 4-G and Comparative Example 3.4 Terminal hydroxy polyethylene adipate (molecular weight approximately 20
00) Add 30G, 9 (18 mol) Km-xylylene diisocyanate C molecular weight 188) 564.9 (3 mol), and further add oxyethylene self-oxybutylene copolyether C molecular weight approximately 1800) 900.9 (o, 5 mol) was added and reacted for 2 hours using Thea G"C.

The reaction temperature was then lowered by 70'CK to the reaction mixture! 1
After adding 2-hydroxyethyl methacrylate in the amount shown in 3, dibutyltin dilaut in an aO5 amount, and P-methoxyphenyl in an α01% amount, the mixture was allowed to react for 2 hours. Subsequently, polyols of the type and amount shown in Table 3 which had been heated to 70°C were added, and the mixture was allowed to react for an additional 2 hours.

Characteristics of the obtained urethane prepolymer! ! Shown in 3.

In Table 4, Comparative Example 3 is a case where 10 times the mole of K PUMA was used in place of urethane prepolymer B in Examples 4 to 6. From the results in Table 4, it can be seen that the comparative example has high hardness and low expansion and opening, which is not preferable.

Examples 7 to 10 and Comparative Example 5 Polyethylene-butylene adipate C in the amount shown in 116
m-xylylene diisocyanate (molecular weight 2000)
rs41 (s mol) was added, and polyether glycol of the type and amount shown in Table SK was added, and the mixture was reacted at 70°C for 2 hours.

The reaction mixture was then reduced to 2-hydroxypropyl methacrylate! 1llj(
L! After adding αOs% of dibutyltin dilaurate and α01% of P-methoxyphenyl, the mixture was allowed to react for 2 hours. Pull/continue! ? 7G'CKmil
polyethylene butylene: /7 dihye) (molecular weight 10
00) 11s001ICasmol) was added and allowed to react for an additional hour.

Table 5 shows the properties of the obtained urethane prepolymer.

Table 5 PL44 is the abbreviation for oxyethylene-oxypropylene block copolyether (molecular weight approximately gooo) ◆ * UCDC is oxyethylene oxybutylene copolyether C molecular weight approximately...! The urethane prepolymer 6577 obtained above was used as the urethane prepolymer (1510G); Examples 1 to 3 except that the developer shown in 6 was used.
A photosensitive resin composition was obtained in the same manner as above, and a photocured product was obtained in the same manner as in Examples 1 to 3 using this composition. This photocured product is shown in Table 6VC.

Table 6 Example 7.8 is an example of development with trichloroethane,
Examples 9 and 10 are developed using an aqueous surfactant solution.

Table 6 shows that the one using PL44 becomes slightly cloudy and disperses in water, whereas the one using UCDC becomes cloudy and opaque and disperses in water. It can be seen that development is possible with an aqueous surfactant solution.

Comparative Example 5 is an example in which the amount of polyether glycol is outside the range of the present invention, and the water absorption rate is abnormally high.

Example ■ and Comparative Examples 6 and 7 Polyethylene/butylene adipate (molecular weight approximately 2000
) 32001i (Lfa mol) K1 Add diincyanate shown in Table 7, and further add oxyethylene/oxypropylene block copolyether C molecular weight approximately 2000) 800
J7 (α4 mol) was added and reacted at 70°C for 2 hours.

Then, the reaction temperature was lowered to 70°C and the fL reaction mixture-Kts
s# (his moles) of 2-hydroxyethyl methacrylate and αOs% amount of digtyltin dilaurate and α
After adding 0.1% of P-methoxyphenyl, the mixture was reacted for 2 hours. Polyethylene diethylene adipate C molecular weight approximately 11,500) 825 which was subsequently heated to 70°C
1 mol of ICαI) was added and the reaction was continued for an additional 2 hours.

Table 7 shows the properties of the obtained urethane prepolymer.

Table 7 **'MXDI is an abbreviation for m-xylylene diisocyanate** Abbreviation for diphenylmethane-44'-diisocyanate *IPDI is an abbreviation for inphoron diisocyanate As a urethane prepolymer, 70 g of the urethane prepolymer obtained above was further crosslinked. Polypropylene glyco) monomethacrylate (molecular weight approximately 400) as an agent
A photosensitive resin composition was obtained in the same manner as in Examples 1 to 3 except that ,) lyethylene glycol dimethacrylate all and di7lyl isophthalate) 10Jj were used, and the composition was further used in the same manner as in Examples 1 to 3. to obtain a photocured product. Table 8 shows the properties of this photocured product.

Table 8 Viscosity of Comparative Example 6 compared to Example 11 from SS.

The hardness is high (and the tensile strength is low and not good, and Comparative Example 1
It can be seen that the viscosity is somewhat high and the tensile strength is low, so it is not good.

Patent applicant: Teijin Ltd.: '°1, agent: Patent attorney: N Hiroshi I';1
,・−: °−′ −・j

Claims (1)

[Claims] L(2) Prepolymer main chain has an average molecular weight of 5OO-ae
It is derived from a polyol component containing a terminal ester of oo and a diisocyanate component mainly containing a compound represented by the following formula % formula % (1), and both ends are connected to #l main chain and urethane bond. and photopolymerizable double bonds at least! Consists of individual groups. Urethane prepolymer with average molecular weight Boon~&OO@, 1) Prepo UW-raw chain has average molecular weight 0~zoo
A polyol component containing a terminal layer of humanized polyester of s and a diisocyanate component mainly consisting of a compound represented by the above formula (2), one of the two ends of which is bonded to the main chain through a urethane bond, and is photopolymerizable. consisting of a group having at least ! double bonds, average molecular weight zoooo~&
OGO's urethane prepolymer. 0 At least a photopolymerizable double bond in the molecule! 1. A photosensitive resin composition comprising a crosslinking agent and a photosensitizer. 2 The ratio of the key record A component and B component is t i:t in the molecular number ratio
The set paraboloid according to claim 8, wherein the ratio is ˜4:1. The bool component constituting the prepolymer main chain in the A component of 1tIIl contains a polyether glycol segment, and the polyether glycol component is present in an average of one molecule or less per molecule of the scissor main chain, and the polyether glycol The composition according to claim 11 or 2, characterized in that the ratio of the molecular weight of the polyester to the molecular weight of the polyester is in the range from aS to 1.5. Table: The polyol component constituting the Brevo II ff main chain in the component B contains a polyether glycol component, and the polyether glycol component is present on average at less than one molecule per molecule of the main chain, and # The ratio of the molecular weight of the polyester to the molecular weight of the polyether glycol Ii is a! I-1,5 range 2! 3. A composition according to claim 1 or 2, characterized in that: 1.翫 The urethane prepolyole of component B is composed of a group having at least one photopolymerizable double bond at one end of the molecule, and a residue of a compound having no photopolymerizable double bond and a hydroxyl group at the other end. Claim 1, characterized in that it is a urethane prepolymer consisting of a group consisting of: The composition according to item 2 or CB4.