JP2021088650A - Ultraviolet-curable resin composition - Google Patents

Abstract

To provide a resin composition for injection molding, excellent in curability even when an LED light source is used and excellent in storage stability, which is an ultraviolet-curable resin suitable for handcrafted accessories such as brooches and small articles.SOLUTION: An ultraviolet-curable resin composition is provided, comprising a polyfunctional urethane acrylate oligomer having at least two functional groups, a (meth)acrylate monomer, a photopolymerization initiator, a phosphate, a thiol having four or more functional groups, and a stabilizer, in which the compounding amount of the thiol is 1.0 to 15 pts.wt. and the compounding amount of the stabilizer is 0.01 to 3 pts.wt. relative to total 100 pts.wt. of the urethane acrylate oligomer and the (meth)acrylate monomer.SELECTED DRAWING: None

Description

The present invention relates to a resin composition that is ultraviolet curable and has excellent storage stability.

Acrylic-based photocurable resins are used in many fields to impart special performance to the surfaces of plastic films and plastic moldings. For example, hard coat films that are applied on PET (polyethylene terephthalate) film to give high hardness are used in large quantities in touch panel products, and adhesive films that give viscosity to the film are final products of flat panel display products. It is also used as a protective film in the manufacturing process.

Acrylic resin is used as a casting resin for making accessories such as brooches and small items by taking advantage of its hardness and transparency, even outside the field of applying a thin film to the plastic surface to give it special performance. (Patent Document 1). In the past, applicants have used bifunctional urethane (meth) acrylate resins with a polyether skeleton with a number average molecular weight of 1,000 to 7,000 and monofunctional methacrylate monomers or aromatic acrylate monomers or polar groups for the same purpose. He has invented a composition comprising an aliphatic acrylate monomer which does not have and a photopolymerization initiator (Patent Document 2).

The present invention was excellent in that it was sufficiently cured without leaving stickiness even when cured with a black light light source. However, it is not sufficient in terms of storage stability, and there is a problem that it is easy to thicken even in a high temperature environment. Even an LED light source has high curability, and it is difficult to thicken even in a high temperature environment. There was room for improvement in terms of achieving both the different required performances of high LED.

Japanese Unexamined Patent Publication No. 10-264184 Japanese Patent No. 6335583

The subject of the present invention is an ultraviolet curable resin suitable for a casting type such as making accessories such as brooches and small items by oneself, which has excellent curability even when the ultraviolet irradiation light source is an LED, and is hard to thicken even in a high temperature environment and is stable in storage. It is an object of the present invention to provide a resin composition having excellent properties.

The invention of claim 1 comprises a polyfunctional urethane acrylate oligomer (A) containing at least a bifunctionality, a (meth) acrylate monomer (B), a photopolymerization initiator (C), a phosphoric acid ester (D), and 4 (F) contains 1.0 to 15 parts by weight of (E) with respect to 100 parts by weight of the total of (A) and (B), which contains a functional or higher thiol (E) and a stabilizer (F). Provided is an ultraviolet curable resin composition characterized by a blending amount of 0.01 to 3 parts by weight.

The invention of claim 2 is characterized in that the (meth) acrylate monomer of (B) contains a monofunctional (meth) acrylate monomer containing a hydroxyl group and / or a bifunctional linear skeleton (meth) acrylate monomer. The photocurable resin composition according to claim 1 is provided.

The photocurable according to claim 1, wherein the blending amount of (A) with respect to the total of (A) and (B) is 50% by weight or more. A resin composition is provided.

The invention of claim 4 further provides the photocurable resin composition according to any one of claims 1 to 3, further comprising a polymerization inhibitor (G).

The invention of claim 5 provides the photocurable resin composition according to any one of claims 1 to 4, characterized in that it is a injection-forming resin.

The composition of the present invention has excellent curability even when the ultraviolet irradiation light source is an LED, is hard to thicken even in a high temperature environment, and has excellent storage stability, and is suitable for handicraft use for making accessories such as brooches and accessories. It is useful as a curable injection-forming composition.

The composition of the ultraviolet curable resin composition of the present invention comprises a polyfunctional urethane (meth) acrylate oligomer (A), a (meth) acrylate monomer (B), a photopolymerization initiator (C), and a phosphoric acid ester (D). , A tetrafunctional or higher thiol (E), and a stabilizer (F). In addition, in this specification, (meth) acrylate includes both acrylate and methacrylate.

The polyfunctional urethane (meth) acrylate oligomer (A) used in the present invention is one of the main components constituting the cured film, and is further hydroxy at both ends of a compound obtained by reacting a polyol with a polyisocyanate, for example. Examples thereof include a structure produced by reacting (meth) acrylate and having two or more (meth) acryloyl groups and urethane bonds in one molecule. The number of functional groups includes a bifunctional urethane (meth) acrylate oligomer in that it has a good balance of reactivity, curing shrinkage, and storage stability.

Examples of the polyol include polyether-based, polyester-based, polycarbonate-based, and polydiene-based, and among these, polyether-based products having high elongation are preferable, and polytetramethylene glycol (hereinafter referred to as PTMG) is more preferable. Examples of the polyisocyanate include aromatics, aliphatics, and alicyclics. Among these, non-aromatics having excellent weather resistance are preferable, and isophorone diisocyanate (hereinafter, IPDI) capable of increasing hardness is further used. preferable.

The blending ratio of the bifunctional urethane (meth) acrylate oligomer in (A) is preferably 30 to 100% by weight, more preferably 80 to 100% by weight, and particularly preferably 90 to 100% by weight. preferable. When the content is 30% by weight or more, sufficient storage stability can be ensured, but when the content is 80% by weight or more, the stability can be further improved.

The weight average molecular weight (hereinafter referred to as Mw) of (A) is preferably 1000 to 20000, more preferably 1500 to 10000, and particularly preferably 1500 to 5000. When it is 1000 or more, a cured product having sufficient hardness can be obtained, and when it is 20000 or less, it becomes easy to adjust the viscosity to be suitable for workability. Mw was calculated by measuring and calculating the molecular weight in terms of standard polystyrene by gel permeation chromatography using a tetrahydrofuran eluent on a column using a filler based on styrenedivinylbenzene.

The blending amount of (A) is preferably 40 to 75% by weight, more preferably 45 to 70% by weight, based on the total solid content. When it is 40% by weight or more, sufficient curability can be ensured, and when it is 75% by weight or less, it becomes easy to adjust the viscosity to be suitable for workability.

The (meth) acrylate monomer (B) used in the present invention is blended as a reactive diluent for adjusting the viscosity to have good workability. As for the number of functional groups, it is preferable that the ratio of the bifunctional or less functional (meth) acrylate monomer accounts for 80% by weight or more with respect to the whole (B). If it is less than 80% by weight, the curability is lowered, stickiness tends to remain on the surface of the cured product, and the curing shrinkage tends to increase as the ratio of trifunctional or higher increases.

Examples of the bifunctional or lower (meth) acrylate monomer include (meth) such as a linear (branched) alkyl skeleton, an aliphatic cyclic skeleton, an ether skeleton, an aromatic ring-containing, a hydroxyl group-containing, an amino group-containing, and a heterocyclic skeleton. Examples thereof include acrylate monomers, which can be used alone or in combination of two or more. Among these, a hydroxyl group-containing (meth) acrylate monomer and a linear skeleton (meth) acrylate monomer are preferable in terms of good curability, and for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl ( Meta) acrylate, 2-hydroxybutyl (meth) acrylate, ethylene glycol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate , 1.4-Butanediol di (meth) acrylate, 1.6-hexanediol di (meth) acrylate and the like, and in particular 2-hydroxypropyl methacrylate, 1.6-hexanediol diacrylate, polyethylene glycol diacrylate and the like. (N <10) is preferable.

The blending amount of (B) is preferably 10 to 40% by weight, more preferably 15 to 35% by weight, based on the total solid content. When it is 10% by weight or more, it is easy to adjust the viscosity to be suitable for workability, and when it is 40% by weight or less, sufficient curability can be ensured.

The photopolymerization initiator (C) used in the present invention generates radicals by irradiation with ultraviolet rays, electron beams, etc., and the radicals trigger a polymerization reaction, and is benzylketal-based, acetophenone-based, or phosphine oxide-based. A general-purpose photopolymerization initiator can be used. 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, 2.2-dimethoxy-1.2-diphenylethane-1-one as a benzyl ketal system, 1-hydroxy-cyclohexyl-phenyl-ketone and 1- [4- (2- (2- (2-)) as an α-hydroxyacetophenone system. Hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1-one is a 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1 as an α-aminoacetophenone system. -On includes 2.4.6-trimethylbenzoyl-diphenyl-phosphine oxide and bis (2.4.6-trimethylbenzoyl) -phenylphosphine oxide as acylphosphine oxide systems, alone or in combination of two or more. Can be used in combination.

In the above (C), it is preferable to contain an α-hydroxyacetophenone type that is hard to yellow and an acylphosphine oxide type that is excellent in internal curability. In particular, when the cured film is thickened to 100 μm or more as in the injection type, the acylphosphine oxide system is effective, and the combined use of both is preferable. Commercially available products include α-hydroxyacetophenone-based Omnirad 184 and phosphine oxide-based Omnirad TPO H (trade name: manufactured by iGM Resins).

The blending amount of (C) is preferably 1 to 25 parts by weight, more preferably 10 to 20 parts by weight, and particularly preferably 12 to 18 parts by weight with respect to 100 parts by weight of the radically polymerizable component. By blending in this range, the composition can be cured efficiently. When the α-hydroxyacetophenone system and the acylphosphine oxide system are used in combination, the blending ratio is preferably 20 to 60 parts by weight of the acylphosphine oxide system with respect to 100 parts by weight of the α-hydroxyacetophenone system.

The phosphoric acid ester (D) used in the present invention is blended in a role of suppressing an increase in viscosity during storage at a high temperature, for example, 60 ° C. It is preferable to have a photoreactive functional group such as a (meth) acryloyl group so that bleeding from the cured film is less likely to occur. Commercially available products include PM-2 (trade name: manufactured by Nippon Kayaku Co., Ltd.) and PM-21 (trade name: manufactured by Nippon Kayaku Co., Ltd.).

The blending amount of (D) is preferably 0.1 to 4.5 parts by weight, more preferably 0.3 to 4 parts by weight, based on 100 parts by weight of the total of (A) and (B). It is preferably 0.4 to 3.5 parts by weight, and particularly preferably 0.4 to 3.5 parts by weight. Within this range, it is possible to suppress an increase in viscosity even when stored at 60 ° C., and sufficient storage stability can be ensured.

The tetrafunctional or higher functional thiol (E) used in the present invention is blended in a role of accelerating the ultraviolet curing reaction, and is capable of an enthiol reaction capable of suppressing curing inhibition by oxygen. Is a very high thiol. For example, pentaerythritol tetrakis (3-mercaptopropionate) is used for 4-functionality, and dipentaerythritol hexa-3-mercaptopropionate is used for 6-functionality, which can be used alone or in combination of two or more. Thiols with less than tetrafunctionality do not have sufficient reactivity, and stickiness cannot remain on the surface of the cured product after irradiation with ultraviolet rays. Further, in terms of high reactivity, a primary thiol is preferable to a secondary thiol.

The blending amount of (E) is 1.0 to 15 parts by weight, preferably 1.5 to 12 parts by weight, and 2.0 to 5.0 parts by weight with respect to 100 parts by weight in total of (A) and (B). Parts by weight are more preferred. Curability can be improved at 1.0 part by weight or more to eliminate stickiness on the surface of the film after curing, and storage stability in a high temperature environment can be ensured at 15 parts by weight or less. Commercially available products include PEMP (trade name: manufactured by SC Organic Chemistry Co., Ltd., 4-functional) and DPMP (trade name: manufactured by the same company, 6-functional).

The stabilizer (F) used in the present invention is blended in a role of suppressing an increase in viscosity during high-temperature storage, as in the case of (D). Examples of stabilizers include light stabilizers and antioxidants. Specifically, UV absorbers typified by benzotriazoles and triazines, hindered amines, hindered phenols, phosphites, and thioethers. Antioxidants can be mentioned, and can be used alone or in combination of two or more.

The blending amount of (F) is 0.01 to 3.0 parts by weight, preferably 0.05 to 2 parts by weight, and 0.08 to 1 by weight, based on 100 parts by weight of the total of (A) and (B). .5 parts by weight is more preferred. When it is 0.01 parts by weight or more, it has an effect of suppressing an increase in viscosity at a high temperature, and when it is 3.0 parts by weight or less, it is possible to suppress surface stickiness at the time of curing. Commercially available products include Tinuvin123 and Tinuvin249 (trade name: manufactured by BASF Japan) as hindered amines, Irganox1076 (trade name: manufactured by BASF Japan) as hindered phenols, and AO-503 (trade name: manufactured by Adeka) as thioethers. is there.

The composition of the present application preferably further contains a polymerization inhibitor (G) in a role of suppressing an increase in viscosity during storage at a high temperature. By adding a small amount of (G), the performances of (D) and (F) can be effectively brought out, and the blending amount thereof can be reduced. Specific examples thereof include dibutylhydroxytoluene, and the blending amount is preferably 0.03 to 0.3 parts by weight with respect to 100 parts by weight of the photoreactive component.

The composition of the present invention contains various additives such as a leveling agent, a plasticizer, a tackifier, a pigment, a dye, an antifoaming agent, a thickener, and a wettability adjusting agent as long as the performance is not impaired. It may be.

The viscosity of the composition at 25 ° C. is preferably 500 to 15000 mPa · s, more preferably 1000 to 10000 mPa · s. When it is 500 mPa · s or more, workability is improved and casting work becomes easy, and when it is 15000 mPa · s or less, the reproducibility of casting and air bubble removal are improved.

The storage stability of this composition can be determined by measuring the thickening rate in an environment of 60 ° C. as an accelerated test. Specifically, the viscosity of the composition after being left at 60 ° C. for 14 days preferably has an increase rate of 20% or less, more preferably 10% or less, based on the initial viscosity. If it is 20% or less, it is judged that the storage stability is sufficient for practical use.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but specific examples are shown, and the present invention is not particularly limited thereto. Unless otherwise specified, the measurement was performed under the conditions of room temperature of 25 ° C. and relative humidity of 65%. The blending amount indicates the part by weight.

Example 1
In the light-shielding bottle, as (A), a bifunctional urethane (meth) acrylate oligomer (reacting a hydroxy (meth) acrylate with a reaction product of PTMG and IPDI, Mw.3000) and a hexafunctional urethane (meth) acrylate oligomer (B). ) As light ester HOP (N) (trade name: Kyoeisha Chemical Co., Ltd., 2-hydroxypropyl methacrylate), and as (C), Omnirad184 (manufactured by iGM, α-hydroxyacetophenone type) and Omnirad TPO H (G) (iGM). (Acylphosphine oxide type) as (D), PM-21 (trade name: Nippon Kayakusha) as (D), PEMP (trade name: SC Organic Chemistry, pentaerythritol tetrakis) (3) -Mercaptopropionate)), Tinuvin249 (trade name: BASF Japan, hindered amine type) as (F), dibutylhydroxytoluene as (G), and KL-700 (trade name: Kyoeisha Chemical Co., Ltd.) as a leveling agent. The resin composition of Example 1 was prepared by adding the amount of polydimethylsiloxane (organic group-containing polydimethylsiloxane) shown in Table 1 and stirring with a stirring defoamer for 15 minutes or more until the mixture became uniform.

Examples 2 to 15
In addition to the materials used in Example 1, 1.6HX-A (trade name: manufactured by Kyoeisha Chemical Co., Ltd., 1.6 hexanediol diacrylate) and M-240 (trade name: manufactured by Toa Synthetic Co., Ltd.) as (B) above. Polyethylene glycol (n≈4) diacrylate), PM-2 (trade name: manufactured by Nippon Kayaku Co., Ltd.) as (D), and DPMP (trade name: SC organic chemical company, dipentaerythritol) as (E). Hexa-3-mercaptopropionate) as (F), Irganox 1076 (trade name: manufactured by BASF Japan) and AO-503 (trade name: manufactured by Adeca) are stirred and defoamed with the formulations shown in Table 2. The resin compositions of Examples 2 to 15 were prepared by stirring for 15 minutes or more until the mixture became uniform.

Comparative Examples 1 to 6
In addition to the materials used in the examples, TMMP-LV (trade name: manufactured by SC Organic Chemistry Co., Ltd., trimethylpropantris (3-mercaptopropionate)) and TEMPIC (trade name: manufactured by SC Organic Chemical Co., Ltd.) as trifunctional thiols. , Tris-[(3-mercaptopropionyloxy) -ethyl] -isocyanurate), and stir for 15 minutes or more using a stirring defoamer with the formulation shown in Table 2 until uniform. A resin composition was prepared.

Preparation of cured product 3 g of the resin composition at room temperature was put into a silicone mold (manufactured by Herbert, silicone motif RSSD-2, 20 mm × 32 mm × t5 mm), and LED irradiation was performed from a height of 4 cm from the resin surface. Using a machine SUN mini (manufactured by Parts Club), the mixture was cured by irradiating with an output of 6 W and an illuminance of 6 mW / cm2 (365 nm) (13 W / cm2 (405 nm)) for 1 minute and further from the back surface for 1 minute. Then, the cured product was taken out from the silicone mold and left at 23 ± 2 ° C. for 30 minutes to prepare the product.

Table 1

Table 2

The evaluation method was as follows.

Viscosity: Using a cone plate type viscometer RC-550 manufactured by Toki Sangyo, the cone angle is 3 ° R17.65, 25 ± 1 ° C., the rotation speed is 20 rpm for 500 to 2000 mPa · s, and 10 rpm for 2000 to 5000 mPa · s. 5000-10000 mPa · s was measured at 5 rpm.

Curability: The degree of stickiness of the LED light irradiation surface of the cured product was confirmed by touching the finger, and was marked with ◯ when there was no stickiness and x when there was.

Appearance: The transparency and color of the cured product were visually confirmed, and colorless and transparent were marked with ◯, and abnormalities such as cloudiness and discoloration were marked with x.

Curing shrinkage: The presence or absence of warpage or air bubbles in the cured product was visually confirmed, and the case where there were no air bubbles and the warp was less than 2 mm was evaluated as ◯, and the case where there were air bubbles or the warpage was 2 mm or more was evaluated as x.

Preservation: Weigh 20 g of the resin composition in a 50 mL light-shielding bottle, store it in a constant temperature bath at 60 ° C for 14 days, measure the viscosity, and determine that the viscosity increase rate from the initial viscosity is 10% or less. 20% was marked with ◯, and over 20% was marked with x.

The evaluation results of the examples are shown in Table 2.
Table 3

The evaluation results of the comparative examples are shown in Table 4.
Table 4

The resin composition of the example had good viscosity, curability, appearance, curing shrinkage, and storage stability.

On the other hand, Comparative Example 1 not containing the bifunctional ureac and Comparative Example 5 not containing (F) are inferior in storage stability, and the amount of (E) blended is small. Comparative Examples 6 in which the amounts of Examples 3 to 4 and (F) were large were inferior in curability, and none of them was suitable for the present invention.

The ultraviolet curable resin composition of the present invention has excellent curability even when an LED light source is used, has a low viscosity increase rate at high temperatures, and has good storage stability. Therefore, accessories such as brooches and accessories are made by oneself. It is useful as a casting type resin suitable for handicraft applications.

Claims (5)

A polyfunctional urethane acrylate oligomer (A) containing at least bifunctionality, a (meth) acrylate monomer (B), a photopolymerization initiator (C), a phosphoric acid ester (D), and a tetrafunctional or higher functional thiol (E). And the stabilizer (F) is included, the blending amount of (E) is 1.0 to 15 parts by weight, and the blending amount of (F) is 0.01 with respect to 100 parts by weight of the total of (A) and (B). An ultraviolet curable resin composition characterized by being ~ 3 parts by weight. The photocurable resin according to claim 1, wherein the (meth) acrylate monomer of (B) contains a monofunctional (meth) acrylate monomer containing a hydroxyl group and / or a bifunctional linear skeleton (meth) acrylate monomer. Composition. The photocurable resin composition according to any one of claims 1 or 2, wherein the blending amount of (A) with respect to the total of (A) and (B) is 50% by weight or more. The photocurable resin composition according to any one of claims 1 to 3, further comprising a polymerization inhibitor (G). The photocurable resin composition according to any one of claims 1 to 4, wherein the resin is a casting type resin.