JP2020070315A - Composition for cast molding - Google Patents

Abstract

To provide a resin composition for cast molding which is an ultraviolet curable resin suitable for handicraft application of making by an accessory such as a brooch and a small article by oneself, is excellent in curability and has high hardness even when using an LED light source, and is excellent in reproducibility of a casting die because of small curing shrinkage.SOLUTION: A resin composition for cast molding contains a hydrogenated ketone resin (A), a hydroxyl group-containing monofunctional (meth)acrylate monomer (B), a photopolymerization initiator (C), and (D) a curing accelerator (D), in which a glass transition point of the simple polymer of the (B) is 0°C or higher.SELECTED DRAWING: None

Description

  TECHNICAL FIELD The present invention relates to an ultraviolet curable resin composition for a casting mold which has a high hardness, a small curing shrinkage, and an excellent molding precision.

  Acrylic photo-curable resins are used in many fields for imparting special properties to the surface of plastic films and plastic moldings. For example, a hard coat film applied on a PET (polyethylene terephthalate) film to impart high hardness is used in large quantities in touch panel products, and an adhesive film that imparts viscosity to the film is a final product in a flat panel display product. It is also used as a protective film in the manufacturing process.

  It is used as a resin for self-made accessories such as broaches and small articles by applying the hardness and transparency of acrylic resin, in addition to the field of applying a thin film to the surface of such plastics and imparting special performance (Patent Document 1). And in the past, the applicant has found that the polyether skeleton has a number average molecular weight of 1,000 to 7,000, a bifunctional urethane (meth) acrylate resin, a monofunctional methacrylate monomer or an aromatic acrylate monomer, or a fat having no polar group. A composition comprising a group acrylate monomer and a photopolymerization initiator is invented (Patent Document 2).

The present invention was excellent in that it was sufficiently cured without leaving tackiness even when cured with a black light source. However, when casting using a casting mold such as silicone, a slight gap occurs between the casting mold and the cured resin due to curing shrinkage, and in terms of faithful reproduction of the precision of the casting mold. There was room for improvement.

JP-A-10-264184 Japanese Patent No. 6335853

  The object of the present invention is an ultraviolet curable resin suitable for handicraft applications for making accessories such as broaches and small items by itself, and it has excellent curability even with an LED light source. Another object of the present invention is to provide a resin composition for a casting mold having excellent accuracy.

  The invention of claim 1 comprises a hydrogenated ketone resin (A), a hydroxyl group-containing monofunctional (meth) acrylate monomer (B), a photopolymerization initiator (C), and a curing accelerator (D). And a glass transition point (hereinafter Tg) of the polymer alone (B) is 0 ° C. or higher.

The invention of claim 2 provides the resin composition for a casting mold according to claim 1, wherein the (A) is a polycondensate of acetophenone and formaldehyde containing a hydroxyl group.

The invention of claim 3 provides the resin composition for a casting mold according to claim 1 or 2, wherein the hydroxyl value of (A) is 230 to 380 mgKOH / g.

The invention of claim 4 provides the resin composition for a casting mold according to any one of claims 1 to 3, wherein the (D) is a polyfunctional primary thiol.

INDUSTRIAL APPLICABILITY The composition of the present invention is excellent in curability even with an LED light source, has a very small curing shrinkage even though it has high hardness, and has excellent reproducibility of precision with respect to a casting mold. It is useful as an ultraviolet-curable composition for injection-molding.

The composition of the ultraviolet curable resin composition of the present invention comprises a hydrogenated ketone resin (A), a hydroxyl group-containing monofunctional (meth) acrylate monomer (B), a photopolymerization initiator (C), and a photocuring accelerator. (D). In addition, in this specification, (meth) acrylate includes both acrylate and methacrylate.

The ketone resin (A) used in the present invention is one of the main components constituting the cured film and is a hydrogenated, non-reactive resin inert to actinic rays. When a non-hydrogenated ketone resin is used, stickiness tends to remain on the surface of the cured product, and it cannot be used alone.

  The number average molecular weight (hereinafter Mn) of (A) is preferably 800 to 5000, and more preferably 1000 to 3000. When it is 800 or more, a cured product having a sufficient hardness can be obtained, and when it is 5000 or less, it becomes easy to adjust the viscosity suitable for workability. In addition, Mn was measured and calculated by gel permeation chromatography using a column using a packing material of a styrene-divinylbenzene base material and using a tetrahydrofuran eluent to measure a molecular weight in terms of standard polystyrene.

  The (A) preferably contains a polar functional group from the viewpoint of improving the cohesive force after curing, and more preferably contains a hydroxyl group. The hydroxyl value is preferably 230 to 380 mgKOH / g, more preferably 300 to 350 mgKOH / g. Examples of such a ketone resin include a hydrogenated product of a polycondensate obtained by reacting acetophenone and formaldehyde, and a commercially available product is TEGO Variplus SK (trade name: manufactured by Evonik, hydroxyl value 325 mgKOH / g, Mn.1000). ~ 1500).

The amount of the compound (A) to be added to the entire composition is preferably 15 to 65% by weight, more preferably 20 to 60% by weight. When it is 15% by weight or more, the tackiness and curing shrinkage of the cured product can be suppressed to a low level, and when it is 65% by weight or less, sufficient curability can be secured.

The monofunctional (meth) acrylate monomer (B) used in the present invention is a monomer having a hydroxyl group that has a high compatibility with (A) and is incorporated for the purpose of improving the curability of the composition. Tg is 0 ° C. or higher. For example, there are 2-hydroxypropyl methacrylate (Tg: 26 ° C.), 2-hydroxyethyl methacrylate (Tg: 55 ° C.) and the like, and they can be used alone or in combination of two or more kinds. If Tg is less than 0 ° C., the curability decreases and the surface of the cured product becomes sticky, so that it cannot be blended alone. Further, even if Tg is 0 ° C. or higher, when it is polyfunctional, curing shrinkage tends to be large, and it is impossible to mix it alone.

The blending amount of the (B) composition with respect to the whole composition is preferably 25 to 70% by weight, and more preferably 30 to 65% by weight. When the amount is 25% by weight or more, sufficient curability can be secured, and when the amount is 70% by weight or less, sufficient hardness of the cured product can be secured.

The photopolymerization initiator (C) used in the present invention produces a radical upon irradiation with ultraviolet rays or electron beams, and the radical triggers the polymerization reaction. Benzyl ketal-based, acetophenone-based, phosphine oxide-based For example, 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-diphenylethan-1-one is used as a benzyl ketal system, and 1-hydroxy-cyclohexyl-phenyl-ketone and 1- [4- (2- Hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one is a 2-amino-1- (4-methylthiophenyl) -2-morpholinopropan-1 as α-aminoacetophenone system. -One includes 2.4.6-trimethylbenzoyl-diphenyl-phosphine oxide and bis (2.4.6-trimethylbenzoyl) -phenylphosphine oxide as an acylphosphine oxide system, which may be used alone or in combination of two or more. Can be used in combination.

Among the above-mentioned (C), it is preferable to include an α-hydroxyacetophenone type that does not easily turn yellow and an acylphosphine oxide type that is excellent in internal curability. In particular, when thickening the cured film to 100 μm or more, it is effective to use an acylphosphine oxide-based compound in combination. Examples of commercially available products include α-hydroxyacetophenone-based OMNIRAD 184 and phosphine oxide-based OMNIRADTPO (trade name: manufactured by iGM).

The blending amount of (C) is preferably 5 to 35 parts by weight, more preferably 10 to 32 parts by weight, and particularly preferably 12 to 30 parts by weight, based on 100 parts by weight of the radically polymerizable component. By blending within this range, the composition can be efficiently cured.

  The curing accelerator (D) used in the present invention is blended with the above (C) in the role of improving the photopolymerizability of (B). A polyfunctional thiol compound capable of an enethiol reaction capable of suppressing curing inhibition by oxygen is preferable, and a primary thiol having high reactivity is more preferable.

Examples of the above (D) include 1,4-bis (3-mercaptobutyryloxy) butane for bifunctional, trimethylolpropane tris-3-mercaptopropionate for trifunctional, and pentaerythritol tetrakis (for tetrafunctional). 3-mercaptobutyrate) and pentaerythritol tetrakis (3-mercaptopropionate), and hexafunctional dipentaerythritol hexa-3-mercaptopropionate, etc., which may be used alone or in combination of two or more. it can. Among these, pentaerythritol tetrakis (3-mercaptopropionate) is preferable from the viewpoint of improving the surface curability, and PEMP (trade name: manufactured by SC Organic Chemical Co., Ltd.) is a commercially available product.

The blending amount of (D) is preferably 1 to 15 parts by weight, more preferably 2 to 12 parts by weight, particularly preferably 3 to 10 parts by weight, based on 100 parts by weight of the radically polymerizable component. When the amount is 1% by weight or more, sufficient reactivity can be secured even if the amount of (C) is reduced, and when the amount is 15% by weight or less, stable storage stability can be secured.

The viscosity of this composition at 25 ° C. is preferably 100 to 35,000 mPa · s, and more preferably 200 to 30,000 mPa · s. When it is 100 mPa · s or more, the workability is improved and the casting work is facilitated, and when it is 35,000 mPa · s or less, the reproducibility of the casting mold and the bubble removal are good.

The composition of the present invention contains a reactive oligomer, a plasticizer, a tackifier, an antioxidant pigment, a dye, a light stabilizer, an antifoaming agent, a thickener, an ultraviolet absorber, if necessary, within a range that does not impair the performance. , And various additives such as a wettability adjusting agent may be included.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, which are specific examples and are not particularly limited thereto. Unless otherwise noted, room temperature was measured at 25 ° C. and 65% relative humidity. Moreover, the compounding quantity shows a weight part.

Example 1
In a light-shielding bottle, TEGO Variplus SK (trade name: manufactured by Evonik, hydroxyl value 325 mg KOH / g, Mn. 1000 to 1500) as the (A) and light ester HOP (N) (trade name: Kyoeisha) as the (B). Chemical (2-hydroxypropylmethacrylate), (C) as Omnirad184 (iGM, α-hydroxyacetophenone type) and Omnirad TPO H (iGM, acylphosphine oxide type), (D). As PEMP (trade name: pentaerythritol tetrakis (3-mercaptopropionate) manufactured by SC Organic Chemical Co., Ltd.), the amount shown in Table 1 was added, and the mixture was stirred for 15 minutes or more until uniform using a stirring and defoaming machine. The resin composition 1 was prepared.

Examples 2-5
In addition to the materials used in Example 1, GE-610 (trade name: 2-hydroxyethyl methacrylate manufactured by Mitsubishi Chemical Co., Ltd.) is used as the (B), and SUA-023 (manufactured by Asia Manufacturing Co., Ltd.) is used as a reactive oligomer. (Skeleton urethane acrylate) was used and the composition shown in Table 1 was used to stir for 15 minutes or more using a stirring and defoaming machine to prepare a resin composition of Examples 2 to 5.

Comparative Examples 1-9
In addition to the materials used in the examples, TEGO Variplus AP (trade name: Evonik, ketone formaldehyde condensation resin, non-hydrogenated) and TEGO Variplus CA (trade name: Evonik, ketone aldehyde condensation resin) are used as non-reactive polymers. , Non-hydrogenated) and TEGO AddBond LTH (trade name: manufactured by Evonik, special polyester resin) and B-14S (trade name: manufactured by Kuraray Co., polyvinyl butyral, having hydroxyl group) and Neocryl B-818 (trade name: manufactured by DSM). , EA / EMA copolymerized acrylic polymer, with hydroxyl group, 4-HBA (trade name: Osaka Organic Chemical Co., Ltd., 4-hydroxybutyl methacrylate, Tg: -32 ° C.) and MIRAMER M170 (commodity) as (meth) acrylate monomers. Name: Mi Won, ethoxyethoxyethyl acrylate, Tg: −56 ° C.) and light ester 4EG (trade name: Kyoeisha Chemical Co., Ltd., PEG # 200 diacrylate Tg: 51 ° C.) were used to stir and remove with the formulation shown in Table 1. The resin compositions of Comparative Examples 1 to 9 were prepared by using a foaming machine and stirring for 15 minutes or more until the mixture became uniform.

Preparation of cured product 3 g of the resin composition at room temperature was placed in a silicone mold (Silvell Motif RSSD-2, 20 mm x 32 mm x t5 mm, manufactured by Herbert Co., Ltd.), and LED irradiation was performed from a height of 4 cm from the resin surface. Using a machine SUN mini (manufactured by Parts Club), irradiation was performed at an output of 9 W, an illuminance of 6 mW / cm2 (365 nm), and 13 mW / cm2 (405 nm) for 2 minutes, and further irradiation was performed for 1 minute from the back surface to cure. After that, the cured product was taken out from the silicone mold and left standing at 23 ± 2 ° C. for 30 minutes to prepare.

Table 1

The evaluation method was as follows.

Viscosity: Cone plate type viscometer RC-550 manufactured by Toki Sangyo Co., Ltd., cone angle 3 ° R17.65, 25 ± 1 ° C., rotation speed is 50 rpm in viscosity range 500 mPa · s or less, 20 rpm in 500 to 2000 mPa · s. , 2000 to 5000 mPa · s was measured at 10 rpm, 5000 to 10000 mPa · s was measured at 5 rpm, 10,000 to 100000 mPa · s was measured at 1 rpm, and 100,000 to 1,000,000 mPa · s was measured at 0.1 rpm.

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

  Transparency: Transparency was confirmed by shining light on the cured product and visually observing the watermark. When transparent, it was marked with ◯, and when it was slightly clouded, it was marked with x.

  Hardness: The irradiated surface of the cured product was measured with a D-type hardness tester (weight of 5 kg).

  Curing shrinkage: The total of the distances contracted from each side in the state of being contained in the silicone mold was calculated, and the total value within 1.0 mm was evaluated as ◯, and the value exceeding 1.0 mm was evaluated as x.

Table 2 shows the evaluation results of the examples.
Table 2

  The resin compositions of Examples had good curability, transparency, hardness, and cure shrinkage.

 On the other hand, Comparative Examples 1 to 5 not containing (A) are inferior in curability, transparency and hardness, and Comparative Examples 6 to 8 not containing (B) are inferior in curability, and instead of (A). Comparative Example 9 containing the reactive oligomer had a large curing shrinkage, and all were not suitable for the present invention.

The composition for casting mold of the present invention is excellent in curability and has high hardness and little curing shrinkage, so that the reproducibility of the casting mold is high, and it is suitable for handicraft use for making accessories such as broaches and small items. It is also useful as a UV curable resin.

Claims (4)

  A hydrogenated ketone resin (A), a hydroxyl group-containing monofunctional (meth) acrylate monomer (B), a photopolymerization initiator (C), and a curing accelerator (D). A glass composition having a glass transition point of 0 ° C. or higher in a polymer alone, a resin composition for a casting mold.   The resin composition for a casting mold according to claim 1, wherein the (A) is a polycondensate of acetophenone and formaldehyde containing a hydroxyl group. The resin composition for a casting mold according to claim 1 or 2, wherein the hydroxyl value of (A) is 230 to 380 mgKOH / g. The resin composition for a casting mold according to claim 1, wherein the (D) is a polyfunctional primary thiol.