JP7159649B2 - Photocurable composition using thiol group-containing polyurethane and cured product thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photocurable composition and cured product capable of forming an inexpensive and tough coating film and having excellent hardness, elongation, heat resistance and flexibility after curing.

In recent years, photocurable resins that are cured by light irradiation such as ultraviolet rays are used in a wide range of applications from medicine and pharmacy to the chemical industry, and radical polymerization acrylic resins and cationic polymerization epoxy resins are commercially available. Among them, there are many types of radical polymerizable acrylic resins such as monofunctional monomers, polyfunctional monomers, oligomers, and polymers. Urethane acrylate is one of them. Many structures have also been proposed.

Cured products of urethane acrylate compositions are used for paints and coatings, and therefore require physical properties such as hardness, elongation, and flexibility. In particular, in the fields of coating applications, sheets and films, there is a need for cured products of urethane acrylate compositions that are more excellent in heat resistance and toughness.

Polyols used in urethane prepolymers include polyester polyols, polyether polyols, polycarbonate polyols, and the like. It is necessary to select a polyol suitable for

However, urethane acrylate compositions using polyether polyols have the problem of insufficient heat resistance and toughness, although they are flexible. Further, a urethane acrylate composition using a polyester polyol has a problem of being inferior in hydrolysis resistance although a coating film having average toughness and heat resistance can be obtained. Further, the urethane acrylate composition using polycarbonate polyol has heat resistance and strength, but has a problem of insufficient elongation.

For example, Patent Document 1 discloses a urethane acrylate obtained by treating a urethane prepolymer composed of a difunctional or trifunctional polyol and a diisocyanate with 2-hydroxyethyl acrylate. was not sufficient in toughness and heat resistance.

Further, Patent Document 2 discloses a urethane acrylate obtained by treating a thiourethane prepolymer composed of polythiol and diisocyanate with 2-isocyanatoethyl acrylate. Sex wasn't enough.

Japanese Patent No. 5886090 Japanese Patent Publication No. 2003-514933

In view of the above problems, an object of the present invention is to provide a photocurable composition capable of forming a cured film having excellent toughness and heat resistance.

The photocurable composition according to the present invention contains a thiol group-containing polyurethane obtained by using a polythiol as a chain extender, a polyfunctional acrylic acid ester and a photopolymerization initiator, wherein the polythiol is 1, 2, 3 - propane tristhiol .

Moreover, the cured product according to the present invention is obtained by curing the above composition.

According to the present invention, it is possible to form a cured product having excellent toughness that satisfies strength and elongation at the same time, and a cured film having excellent heat resistance can be produced because a reactive group can be introduced into the polymer. can provide.

The photocurable composition according to the present invention is a composition comprising a thiol group-containing polyurethane obtained by using a polythiol as a chain extender, a polyfunctional acrylic acid ester, and a photopolymerization initiator. According to the photocurable composition using the thiol group-containing polyurethane according to the present invention, the thiol group-containing polyurethane is applied to a substrate film or the like, dried by heating, and then irradiated with ultraviolet rays to form a cured product. The formed cured product can be used for paints, coating materials, self-supporting films, and the like. Moreover, according to the photocurable composition using the thiol group-containing polyurethane according to the present invention, a cured film having excellent heat resistance can be formed from a tough cured product that satisfies strength and elongation at the same time.

A photocurable composition using a thiol group-containing polyurethane according to the present invention comprises a polyurethane prepolymer comprising at least a polyol having a plurality of hydroxyl groups in one molecule and a polyisocyanate having a plurality of isocyanate groups in one molecule, It contains a thiol group-containing polyurethane chain-extended with a polythiol having multiple thiol groups in one molecule, a polyfunctional acrylic acid ester and a photopolymerization initiator, and optionally a solvent and an organic or inorganic additive.

Examples of polyols having multiple hydroxyl groups in one molecule include polymer compounds such as polyester polyols, polycarbonate polyols, and polyether polyols, aliphatic diols, aliphatic polyols, and alicyclic diols. It is not particularly limited.

Polyester polyols that can be used include, for example, a polyester diol composed of a dibasic acid such as adipic acid and a diol such as 1,6-hexanediol, and a polyester triol composed of a hydroxycarboxylic acid obtained by modifying trimethylolpropane with caprolactone and a polyol. etc. Examples of polyester triols composed of trimethylolpropane and caprolactone include Plaxel 305 (manufactured by Daicel, "Plaxel" is a registered trademark), but are not particularly limited.

As the polycarbonate polyol that can be used, for example, a polycarbonate diol composed of a low-molecular-weight diol and a carbonate ester is preferable from the viewpoints of hydrolysis resistance, heat resistance, flexibility, and the like. Low-molecular-weight diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6- hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,4-cyclohexanedimethanol, glycerin, trimethylolpropane, pentaerythritol, sorbitol and the like, but ethylene glycol , 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol and 1,4-cyclohexanedimethanol are preferred. Examples of the carbonate include dimethyl carbonate and diethyl carbonate, with dimethyl carbonate being preferred. Examples of polycarbonate diols include BENEBiOL (manufactured by Mitsubishi Chemical Corporation, "BENEBiOL" is a registered trademark), Duranol (manufactured by Asahi Kasei Corporation, "Duranol" is a registered trademark), and ETERNACOLL (manufactured by Ube Industries, Ltd., "ETERNACOLL" is a registered trademark). are trademarks), but are not particularly limited.

Polyether polyols that can be used include, but are not particularly limited to, alkylene glycols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol.

Aliphatic diols that can be used include, for example, ethylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexane. Diol, 1,9-nonanediol and the like can be used, but are not particularly limited.

Examples of usable aliphatic polyols include glycerin, trimethylolpropane, pentaerythritol, xylitol, and sorbitol, but are not particularly limited.

Examples of alicyclic diols that can be used include cyclohexanedimethanol and tricyclodecanedimethanol, but are not particularly limited.

In addition, bisphenol derivatives and the like can also be used as diols. Alkylene oxide modified products, (poly)caprolactone modified products and the like can also be used.

Polyisocyanates that can be used include, for example, aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates, but are not particularly limited.

Examples of aromatic polyisocyanates that can be used include 2,4- and 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, and the like, but are not particularly limited. do not have.

Examples of aliphatic polyisocyanates that can be used include tetramethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, and the like, but are not particularly limited.

Examples of usable alicyclic polyisocyanates include isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, cyclohexane diisocyanate, hydrogenated xylylene diisocyanate, and norbornane diisocyanate, but are not particularly limited.

Furthermore, as the polyisocyanate described above, biuret, adduct, allophanate, isocyanurate and mixtures thereof can be used as long as they can withstand use.

Among polyisocyanates, 4,4′-diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (H -MDI) and hydrogenated xylylene diisocyanate (H-XDI) are preferred.

In the present invention, examples of polythiol having multiple thiol groups in one molecule used as a chain extender include 1,2-ethanedithiol, 1,4-bis(3-mercaptobutyryloxy)butane, 1,2,3-propane tristhiol, trimethylolpropane tris(3-mercaptobutyrate), 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4 , 6(1H, 3H, 5H)-trione, pentaerythritol tetrakis(3-mercaptobutyrate), etc., and trifunctional or higher functional ones are desirable. The chain extender is not particularly limited as long as it is a polythiol having multiple thiol groups in one molecule.

The polyfunctional acrylic acid ester according to the present invention may be any polyacrylate having a bifunctional or higher acrylic group, such as ethylene glycol diacrylate, 1,6-hexanediol diacrylate, and other bifunctional acrylates. , glycerin triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate. .

In addition to the above, high-molecular-weight polyfunctional acrylates such as polyester acrylate, polyether acrylate, and urethane acrylate can also be used. In this specification, "acrylate" indicates both "acrylate" and "methacrylate".

The mixing ratio of each component of the photocurable composition according to the present invention is not particularly limited, but the thiol group-containing polyurethane is 10 to 80% by weight, the polyfunctional acrylic acid ester is 5 to 50% by weight, and the photopolymerization initiator. is particularly preferably about 0.1 to 10% by weight. Furthermore, in the photocurable composition according to the present invention, acrylic monomers, solvents and the like can be used as diluents depending on the application as long as the performance is not impaired.

Furthermore, the photocurable composition according to the present invention may contain additives such as acrylic resins, pigments, dyes, surfactants, dispersants, and light stabilizers, and inorganic compounds such as silicates, depending on the application, as long as the performance is not impaired. Compounds can also be used.

Photopolymerization initiators that can be used in the photocurable composition according to the present invention include, for example, benzophenone, 1-hydroxycyclohexylphenyl ketone (IRGACURE 184 (manufactured by BASF, "IRGACURE" is a registered trademark)), 2 -hydroxy-2-methyl-1-phenylpropan-1-one (IRGACURE 1173 (manufactured by BASF)), 2-hydroxy-1-{1-[4-(2-hydroxy-2-methyl-propionyl)-phenyl ]-1,3,3-trimethyl-indan-5-yl}-2-methyl-propan-1-one (ESACURE ONE (manufactured by LAMBERTI)), 1-[4-(2-hydroxyethoxy)phenyl]- Alkylphenones such as 2-hydroxy-2-methylpropan-1-one (IRGACURE 2959 (manufactured by BASF)), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (IRGACURE TPO (manufactured by BASF)) and the like Examples include acylphosphine oxides, but are not particularly limited.

The main compounds used in the present invention have been described above. Next, the method for producing the photocurable composition according to the present invention and the method for producing films and sheets using the photocurable composition will be described.

The flow of the method for producing a photocurable composition according to the present invention will be described with examples of the steps for producing a polycarbonate diol, a step for producing an isocyanate-terminated urethane prepolymer, a chain elongation step, and a film and sheet production step. The manufacturing method is not limited to this.

(Manufacturing process of polycarbonate diol)
First, in N-ethylpyrrolidone, dimethyl carbonate and an excess amount of low-molecular-weight diol relative to the number of moles of dimethyl carbonate are reacted under predetermined conditions, and unreacted substances are removed to obtain a polycarbonate diol.

(Manufacturing process of isocyanate-terminated urethane)
Next, the polycarbonate diol obtained above and, if necessary, a low-molecular-weight diol that is the same as or different from the above-mentioned low-molecular-weight diol are mixed, and an excess amount of diisocyanate is added to the total number of moles of their hydroxyl groups. React under predetermined conditions, remove unreacted substances, and obtain an isocyanate-terminated urethane prepolymer.

(chain elongation step)
Next, a solvent is added to the isocyanate-terminated urethane prepolymer obtained above, an excess amount of polythiol is added to the total number of moles of the isocyanate groups, chain extension reaction is performed under predetermined conditions, and the unreacted product is and removing the solvent to obtain a thiol group-containing polyurethane.

(Composition manufacturing process)
Next, a photocurable composition using a thiol group-containing polyurethane can be obtained by adding a polyfunctional acrylate and a photopolymerization initiator to the thiol group-containing polyurethane obtained above.

(Manufacturing process of film and sheet)
The photocurable composition using the thiol group-containing polyurethane obtained by the method described above is applied onto the substrate film with a coater and dried under predetermined conditions. After drying, the film and sheet according to the present invention can be obtained by exposing the surface to light with an ultraviolet lamp in an _N2 atmosphere and then peeling off the base film.

The base film used in the present invention is not particularly limited, and for example, a resin can be used.

The coater used in the present invention is not particularly limited, and for example, a gravure coater, knife coater, curtain coater, bar coater, etc. can be used depending on the coating thickness.

The ultraviolet lamp used in the present invention is not particularly limited, and light sources such as high-pressure mercury lamps, low-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, carbon arcs, and xenon arcs can be used, particularly high-pressure mercury lamps and metal halide lamps. is desirable.

EXAMPLES The present invention will be specifically described below by way of Examples and Comparative Examples, but the present invention is not limited to these Examples.

[Example 1 Preparation of photocurable composition 1 using thiol group-containing polyurethane]
100 parts by weight of N-ethylpyrrolidone and 200 parts by weight of PTMG2000 (manufactured by Mitsubishi Chemical Corporation) are mixed in a reaction vessel, and then 80 parts by weight of 4,4'-dicyclohexylmethane diisocyanate is added and heated to 80°C. to obtain an isocyanate-terminated urethane prepolymer solution.

70 parts by weight of 1,2,3-propanetristhiol is added to the isocyanate-terminated urethane prepolymer solution obtained above to carry out a chain extension reaction, followed by distillation under reduced pressure to obtain a thiol group-containing polyurethane prepolymer. rice field.

To 30 parts by weight of the thiol group-containing polyurethane prepolymer, 70 parts by weight of NK Oligo UA-1280MK (manufactured by Shin-Nakamura Chemical Industry) and 5 parts by weight of IRGACURE 184 (manufactured by BASF) were added, and the thiol group-containing polymer of Example 1 was added. A photocurable composition 1 using polyurethane was obtained.

[Example 2 Preparation of photocurable composition 2 using thiol group-containing polyurethane]
In a reaction vessel, 100 parts by weight of N-ethylpyrrolidone and 90 parts by weight of ETERNACOL UM90 (1/1) (manufactured by Ube Industries) were mixed, then 80 parts by weight of 4,4'-diphenylmethane diisocyanate was added and the temperature was maintained at 80°C. to obtain an isocyanate-terminated urethane prepolymer solution.

60 parts by weight of 1,2,3-propanetristhiol is added to the isocyanate-terminated urethane prepolymer solution obtained above to carry out a chain extension reaction, followed by distillation under reduced pressure to obtain a thiol group-containing polyurethane prepolymer. rice field.

To 30 parts by weight of the thiol group-containing polyurethane prepolymer, 70 parts by weight of NK Oligo UA-1280MK (manufactured by Shin-Nakamura Chemical Co., Ltd.) and 5 parts by weight of IRGACURE 184 (manufactured by BASF) were added, and the thiol of Example 2 was added. A photocurable composition 2 using a group-containing polyurethane was obtained.

[Comparative Example 1 Preparation of Polyurethane Photocurable Composition 3]
To 30 parts by weight of NK Oligo UA-160TM (manufactured by Shin-Nakamura Chemical Co., Ltd.), 70 parts by weight of NK Oligo UA-1280MK (manufactured by Shin-Nakamura Chemical Co., Ltd.) and 5 parts by weight of IRGACURE 184 (manufactured by BASF) were added and compared. Polyurethane photocurable composition 3 of Example 1 was obtained.

[Comparative Example 2 Production of Polyurethane Photocurable Composition 4]
To 30 parts by weight of Shikou UV-7000B (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 70 parts by weight of NK Oligo UA-1280MK (manufactured by Shin Nakamura Chemical Co., Ltd.) and 5 parts by weight of IRGACURE 184 (manufactured by BASF) were added and compared. Polyurethane photocurable composition 4 of Example 2 was obtained.

Add 30 parts by weight of methyl ethyl ketone to 100 parts by weight of each photocurable composition obtained above and stir thoroughly, A4 size PET film (Lumirror T60: 50 μm thick, manufactured by Toray Industries, Inc., "Lumirror" is a registered trademark. ) with a wire bar to a dry thickness of 30 μm, and dried at 120° C. for 2 minutes to obtain each dry film.

Further, each dried film obtained above was cured by irradiating 400 mj/cm ² with a metal halide lamp in an N ₂ atmosphere, and then peeled off from the PET film to obtain each cured film.

The pencil hardness of the cured film obtained above was measured with a load of 750 g according to JIS K 5600 scratch hardness (pencil method).

Regarding the cured film obtained above, using a viscoelastic spectrometer (DMS) EXSTAR DMS5800 (manufactured by Seiko Instruments Inc.), deformation mode: tension, frequency: 1 Hz, measurement temperature: room temperature to 180 ° C., heating rate : The peak top temperature of the loss tangent tan δ was measured as the glass transition point (Tg) under the condition of 2°C/min.

Regarding the cured film obtained above, using a small desktop tester EZ-LX (manufactured by Shimadzu Corporation), MD × TD: 75 × 15 mm size, load cell: 1 kN, tensile speed: 5 mm / min, distance between chucks : The maximum stress and tensile elongation (=maximum elongation at break) were measured under the condition of 50 mm. Also, the value of maximum stress×tensile elongation was defined as toughness.

Table 1 shows the evaluation results.

Each of the compositions of Examples 1 and 2 provided tough films with sufficient pencil hardness, high Tg, and toughness. However, from the composition of Comparative Example 1, only a cured film having a low Tg and a small maximum tensile stress was obtained with less cross-linking due to less reactive functional groups. Moreover, from the composition of Comparative Example 2, only a cured film with a small tensile elongation was obtained.

The photocurable composition of the present invention can be easily prepared, and as is clear from Table 1, it has sufficient pencil hardness and can form a tough cured product with high heat resistance.

INDUSTRIAL APPLICABILITY The present invention can be used as a paint, coating material, and self-supporting film material because it can use commercially available polyols, can be easily prepared with a simple reaction, and can provide a highly heat-resistant and tough cured product.

Claims (2)

Containing a thiol group-containing polyurethane using polythiol as a chain extender, a polyfunctional acrylic acid ester and a photopolymerization initiator ,
The composition wherein said polythiol is 1,2,3-propanetristhiol . A cured product of the composition according to claim 1 .