JP2018002765A - Ultraviolet curable resin composition for casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic ultraviolet curable resin composition used for making an accessory such as a brooch and a small object by oneself which can be cured even on a contact surface with a silicone resin-based molding die without showing stickiness even when placed in the molding die and cured, and prevents smoke generation by heat of reaction when cured.SOLUTION: An ultraviolet curable resin composition for casting contains polyfunctional isocyanurate-based urethane acrylate (A), a (meth)acrylate monomer (B), a thiol compound (C) and a photopolymerization initiator (D).SELECTED DRAWING: None

Description

  The present invention is an ultraviolet curable resin used for making accessories such as brooches and small items, and particularly when cured in a silicone resin mold, it does not cause stickiness on the contact surface with the mold. The present invention relates to an ultraviolet curable resin composition for casting which does not generate smoke due to reaction heat even when cured.

  Acrylic photocurable resins are used in many fields in order to give special performance to the surface of plastic films and plastic moldings. For example, hard coat films that are coated on a PET (polyethylene terephthalate) film and given high hardness are used in large quantities in touch panel products, and adhesive films that give viscosity to the film are flat panel display products that are final products. In addition, it is also used as a protective film in the manufacturing process.

  It is used as a resin for making accessories such as brooches and small items by making use of the hardness and transparency of acrylic resin even outside the field of applying special performance by applying a thin film on the plastic surface (Patent Literature) 1). In such applications, rather than using dedicated exposure equipment that is industrially used for photocuring, it uses sunlight or commercially available black light, so that it can be cured sufficiently with these light sources. Must have good curing properties. In addition, since it is used in general households, it is preferred that the odor is low, and since the cured product is thicker, after curing, there is also a demand for the property that deformation and yellowing due to curing shrinkage are small. However, when cured in a silicone resin mold having particularly high oxygen permeability, there is a problem that stickiness remains on the cured resin surface, and there is room for improvement.

Japanese Patent Laid-Open No. 10-264184

  The problem of the present invention is that the UV curable resin used to make accessories such as brooches and small items is sticky even on the contact surface with the mold, especially when placed in a silicone resin mold and cured. It is an object of the present invention to provide an ultraviolet curable resin composition for casting which can be cured without causing generation of smoke due to reaction heat when cured.

  The invention of claim 1 is for casting containing a polyfunctional isocyanurate-based urethane acrylate (A), a (meth) acrylate monomer (B), a thiol compound (C), and a photopolymerization initiator (D). An ultraviolet curable resin composition is provided.

The invention of claim 2 is the ultraviolet curable resin composition for casting described in claim 1, wherein (A) is a trifunctional isocyanurate-based urethane acrylate having a number average molecular weight of 500 to 10,000. Offer things.

The invention according to claim 3 is the ultraviolet curable resin composition for casting according to claim 1 or 2, wherein the (B) is a (meth) acrylate having a polar group, an alicyclic structure or an ether skeleton. Offer things.

Moreover, invention of Claim 4 provides the ultraviolet curable resin composition for casting as described in any one of Claims 1-3 whose said (C) is a tetrafunctional secondary thiol.

The composition of the present invention is excellent in curability and can be cured without stickiness even on the contact surface with the mold, especially when placed in a silicone resin mold and cured. It is useful as an ultraviolet curable resin composition for casting without generation of smoke due to.

The composition of the ultraviolet curable resin composition of the present invention is composed of a polyfunctional isocyanurate-based urethane acrylate resin (A), a (meth) acrylate monomer (B), a thiol compound (C), and a photopolymerization initiator (D). is there. In the present specification, (meth) acrylate includes both acrylate and methacrylate.

The polyfunctional isocyanurate-based urethane acrylate resin (A) used in the present invention is a main component that forms a cast resin body by reacting with the acrylate monomer (B). For example, it is produced by adding acrylate to the end of a compound obtained by addition reaction of isocyanurate and polyol, and has a plurality of acrylate groups in the molecule. Since it has an isocyanurate skeleton with high heat resistance, it has a characteristic that the reaction heat at the time of curing is low and deformation is difficult. In order to increase the strength of the cured product together with the curing speed, the number of functional groups is preferably 3 or more, which can form a network structure. This is not preferable.

The number average molecular weight is preferably 500 to 10,000, more preferably 1,000 to 8,000, and particularly preferably 2,000 to 5,000. If the molecular weight is less than 500, the resulting molded product is brittle because the cohesive force is small, and if it exceeds 10,000, the viscosity becomes high and the work is difficult, and the curability is also lowered. The number average molecular weight (hereinafter referred to as “Mn”) was calculated by measuring the molecular weight in terms of standard polystyrene using a gel hydrochromatography method using a tetrahydrofuran solvent in a styrene vinylbenzene-based column.

  The isocyanurate which is the skeleton of the (A) is a trimer of isocyanate, but the isocyanurate here forms a urethane bond by reaction with a polyol, and thus is generated from a trimerization reaction of diisocyanate. Examples of the diisocyanate used as a raw material include hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, diphenylmethane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, and hydrogenated xylylene diisocyanate. is there.

Examples of polyols to be reacted with isocyanurate include polyether polyols, polyester polyols, polycarbonate polyols, polybutadiene polyols, and the like, which can be used alone or in combination of two or more. Examples of the (meth) acrylate added to the terminal include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1 , 4-cyclohexanedimethanol monoacrylate, 4-hydroxycyclohexyl (meth) acrylate, and the like.

The blending amount with respect to the total composition of (A) is preferably 40% by weight to 90% by weight. When it is 40% by weight or more, a sufficient cohesive force can be secured, and when it is 90% by weight or less, a viscosity suitable for workability can be obtained.

  The acrylate monomer (B) used in the present invention is a reactive diluent for the urethane acrylate resin (A) and at the same time is a main component for forming a polymer. If the reactivity is too high, white smoke is generated or heat deformation occurs due to the heat generated by the resin, and therefore it is preferably trifunctional or lower. From the viewpoint of compatibility with the urethane acrylate resin (A), a (meth) acrylate monomer having a polar group, an alicyclic structure or an ether skeleton is preferred.

Examples of monofunctional (meth) acrylate monomers include 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate as those having polar hydroxyl groups, and acryloylmorpholine as those having polar amino groups. , Methacrylamide, N, N-dimethylmethacrylamide, N-isopropylmethacrylamide have an alicyclic structure, isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, dicyclopentenyl methacrylate, adamantanyl methacrylate, Examples of those having an ether skeleton include ethoxydiethylene acrylate, methoxytriethylene glycol acrylate, and phenoxyethyl acrylate. It can be used in combination Germany or two or more kinds.

 Examples of the bifunctional and trifunctional (meth) acrylate monomers include 2-hydroxy-3-acryloyloxypropyl methacrylate, pentaerythritol diacrylate, and pentaerythritol triacrylate, which have polar hydroxyl groups. Those having a structure include tricyclodecane dimethanol diacrylate and dicyclopentanyl diacrylate, and those having an ether skeleton include hexanediol diacrylate, nonanediol diacrylate, polyethylene glycol diacrylate, and the like. The above can be used in combination.

  Among these, 2-hydroxypropyl methacrylate, isobornyl methacrylate, pentaerythritol triacrylate, polyethylene glycol diacrylate, and acryloylmorpholine are preferable from the viewpoints of viscosity and dilutability. The blending amount of (B) in the total composition is preferably 3% by weight to 90% by weight. By setting it as this range, the viscosity suitable for workability | operativity can be ensured.

 The thiol compound (C) used in the present invention plays a role as an ultraviolet curing aid, suppresses polymerization inhibition due to oxygen by an ene-thiol reaction, and can obtain high curability and light transmittance. In particular, a polyfunctional secondary thiol that can prevent thermal addition reaction to the monomer and suppress gelation during storage due to steric hindrance around the thiol group is preferable. Examples of the polyfunctional secondary thiol include pentaerythritol tetrakis (3-mercaptobutyrate), 1,4-bis (3-mercaptobutyryloxy) butane, 1,3,5-tris (3-mercaptobutyryloxyethyl). ) -1,3,5-triazine-2,4,6 (1H, 2H, 5H) -trione and the like, and tetrafunctional pentaerythritol tetrakis (3-mercaptobutyrate) having high curability is particularly preferable.

In the case of casting with a silicone resin mold having high oxygen permeability, curing inhibition due to the permeated oxygen tends to occur at the resin interface in contact with the silicone mold. High curability can be obtained without causing inhibition, and stickiness can be eliminated. The blending amount with respect to the total photocurable component is preferably 0.5% by weight to 8% by weight, and more preferably 1% by weight to 5% by weight. Oxygen polymerization inhibition can be suppressed by setting it as 0.5 weight% or more, and sufficient storage stability can be ensured by setting it as 8 weight% or less.

  The photopolymerization initiator (D) used in the present invention may be a general-purpose photopolymerization initiator because radicals are generated by irradiation with ultraviolet rays or electron beams, and the radicals trigger a polymerization reaction. By using together with the (C), it is possible to firmly cure from the resin surface to the inside of the solid material. By arbitrarily selecting the light absorption wavelength of the polymerization initiator, curability can be imparted over a wide wavelength range from the ultraviolet region to the visible light region. Specifically, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one, 1-hydroxy-cyclohexyl-phenyl -Ketone, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy)- Phenyl] -2-hydroxy-2-methyl-1-propan-1-one, etc., which can be used alone or in combination of two or more. It is preferable to mix 1 to 10% by weight with respect to the radically polymerizable component.

In the composition of the present invention, a plasticizer, an antioxidant pigment, a dye, a light stabilizer, a photosensitizer, an antifoaming agent, a thickener, an ultraviolet absorber, etc. Various additives may be included.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, a specific example is shown and it does not specifically limit to these. In addition, when there is no description, it measured on the conditions of 25 degreeC relative humidity 65% of room temperature.

Example 1
(A) RUA-051 (trade name: manufactured by Asia Kogyo Co., Ltd., isocyanurate-based urethane acrylate, trifunctional, Mn. 2,600), (B) light ester HOP (N) (trade name: Kyoeisha Chemical Co., Ltd.) Made of 2-hydroxypropyl methacrylate) as (C) and Karenz MT PE-1 (trade name: manufactured by Showa Denko KK, pentaerythritol tetrakis (3-mercaptobutyrate)), and (D) as Irg 184 (trade name: The resin composition of Example 1 was prepared by mixing and defoaming in a light-shielding bottle according to the formulation shown in Table 1 until it was uniformly dissolved.

Examples 2-9
In addition to the materials used in Example 1, (A) RUA-048 (trade name: manufactured by Asia Kogyo Co., Ltd., isocyanurate-based urethane acrylate, trifunctional, Mn. 3,100) and (B) TMPTA (trade name) : BASF Japan, trimethylolpropane triacrylate) and light acrylate 9EG-A (trade name: manufactured by Kyoeisha Chemical Co., PEG # 400 diacrylate) and light ester IB-X (product name: manufactured by Kyoeisha Chemical Co., Ltd., Isobol) Nyl methacrylate) and light acrylate PO-A (trade name: manufactured by Kyoeisha Chemical Co., Ltd., phenoxyethyl acrylate) and ACMO (trade name: KJ Chemicals, acrylic morpholine) and put in a light-shielding bottle according to the formulation shown in Table 1. Each resin composition of Examples 2 to 9 was prepared by stirring and defoaming until it was uniformly dissolved.

Comparative Examples 1-5
In addition to the materials used in Examples 1 to 9, SUA-024 (bifunctional, Mn. 1,300, manufactured by Asia Industries) as a polyether-based urethane acrylate, and TE-2000 (trade name: Polybutadiene-based urethane acrylate) Nippon Soda Co., Ltd., bifunctional, Mn. 2,000) is used as epoxy acrylate, EBECRYL 3700 (trade name: manufactured by Daicel Ornex Co., Ltd., bifunctional, Mn. 550), and aliphatic urethane acrylate is used as EBECRYL 8254 (trade name: Daicel).・ Ornex Co., 6-functional, Mn. 1,500), blended as shown in Table 1, stirred and defoamed until dissolved uniformly in a light-shielding bottle, and each resin composition of Comparative Examples 1-5 Prepared.

Production of cured product 2 g of UV curable resin was put into a silicone mold having a diameter of 26 mm and a depth of 10 mm, and from a height of 5 cm from the resin surface, a black light irradiation device Super Resin UV crystal lamp made by Anju was used. It was cured by irradiating with a light intensity of 2 to 4 mW / cm 2 at a wavelength of 365 nm for 5 minutes. Thereafter, the cured product was taken out from the silicone mold and left at 23 ± 2 ° C. for 30 minutes to prepare.

Table 1

The evaluation method was as follows.

Viscosity: Measured at a cone angle of 3 ° R17.65 at 25 ± 1 ° C and a rotation speed of 0.5-50 rpm using a cone plate viscometer RC-550 manufactured by Toki Sangyo Co., Ltd., 200 mPa · s to 20,000 mPa · s was marked with ◯, and when it was off, it was marked with ×.

  Surface curability: The degree of stickiness of the cured product on the surface irradiated with black light was confirmed by touch.

  Silicone contact surface curability: The degree of stickiness of the cured product on the silicone-type contact surface was confirmed by finger touch.

  Smoke generation: When producing the cured product, the presence or absence of generation of white smoke was visually confirmed.

  Formability: When producing the cured product, the shape change before and after curing was visually confirmed.

The evaluation results are shown in Table 2.
Table 2

  All the evaluation results of the ultraviolet curable resin compositions of the examples were good.

On the other hand, in Comparative Examples 1 to 4 in which an oligomer other than (A) was blended, the silicone contact surface was sticky, and in Comparative Examples 1 to 3, the surface curability was also poor. Further, Comparative Example 5 in which (C) was not blended was inferior in curability of the surface and the silicone contact surface, and none of them was suitable for the present invention.

The present invention is an acrylic ultraviolet curable resin composition that can be cured without stickiness on the surface, and does not generate smoke due to reaction heat when cured, particularly when placed in a silicone resin mold. Useful as.

Claims (4)

An ultraviolet curable resin composition for casting containing a polyfunctional isocyanurate-based urethane acrylate (A), a (meth) acrylate monomer (B), a thiol compound (C), and a photopolymerization initiator (D). .   The ultraviolet curable resin composition for casting according to claim 1, wherein (A) is a trifunctional isocyanurate-based urethane acrylate having a number average molecular weight of 1,000 to 10,000.   The ultraviolet curable resin composition for casting according to claim 1 or 2, wherein (B) is a (meth) acrylate having a polar group, an alicyclic structure or an ether skeleton. The ultraviolet curable resin composition for casting described in any one of claims 1 to 3, wherein (C) is a tetrafunctional secondary thiol.