JP2006063345A - Photocurable resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocurable resin composition which has excellent solvent resistance and scratch resistance, and which can give a photocured film having enough hardness from a practical viewpoint. <P>SOLUTION: The photocurable resin composition contains a methacrylic copolymer copolymerized with at least 25% by weight of methyl methacrylate and having unsaturated double bond groups on the side chains, a multi-functional unsaturated monomer, and a photocrosslinking initiator. The photocurable resin composition has enough hardness and moderate stretch from a practical viewpoint after photocured, and can be used effectively as a surface treating agent for various sheet materials, tubes, gaskets, packing, desks, or metal products, cover materials of sound insulating walls or the like. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photocurable resin composition. More specifically, the present invention relates to a photocurable resin composition capable of providing a photocured film having excellent solvent resistance and scratch resistance.

  For automobile exteriors, ABS resin, polypropylene resin, vinyl chloride resin, polymethyl methacrylate resin, polycarbonate resin, etc. have been used in the past, and for the purpose of surface decoration, substrate protection, etc., acrylic resin type, Solvent-based paints such as urethane resin systems and silicone resin systems are used, but non-solvent paints are required particularly from the viewpoint of preventing environmental pollution.

  In order to meet these demands, water-based paints, powder paints, etc. have already been put into practical use. However, water-based paints are inferior in drying properties, so not only drastic improvements in the drying process are required, Auxiliary equipment such as temperature and humidity control and wastewater treatment equipment is required. On the other hand, the standard thickness of powder coatings increases the amount of use, leading to an increase in price, as well as low temperature curability, paint appearance, There are problems such as weather resistance and flexibility, and none of them has completely surpassed solvent-based paints.

In contrast to conventional coating methods, it has been proposed to use a thermoplastic resin film that can be integrally formed with an exterior part from the viewpoint of no coating. This is because a thermoplastic resin film having a curable resin film formed on one side is produced, and this and the exterior component are integrally molded, and the thermoplastic resin is pressure-bonded to the surface of the exterior component, thereby It is intended to give the same coating properties as paint. However, this is inferior in deep drawability (workability) and has a disadvantage of large trimming loss, and is not satisfied as an alternative to solvent-based paints.
Japanese Patent Laid-Open No. 3-114719

  Furthermore, there is a method in which a composition comprising a photocurable monomer represented by a polyfunctional polyacrylate and a photopolymerization initiator is applied to an exterior part and then subjected to a curing reaction by light irradiation to form a resin. In some cases, there are practical problems such as low impact resistance of the cured product and poor flexibility.

Further, 100 parts by weight of an acrylic rubber having an unsaturated double bond group in the side chain, 0.05 to 20 parts by weight of a polyfunctional unsaturated monomer, 0.01 to 10 parts by weight of a photocrosslinking initiator, 10 to 100 parts of amorphous silica A photocrosslinkable acrylic rubber composition containing parts by weight (and 0.1 to 5 parts by weight of an aliphatic amine) has been proposed. The cured film of such an acrylic rubber composition has a hardness higher than that of a conventional coating film. Therefore, practically sufficient film performance cannot be obtained.
Japanese Patent Laid-Open No. 9-100303

  An object of the present invention is to provide a photocurable resin composition that is excellent in solvent resistance and scratch resistance and can provide a photocured film having practically sufficient hardness.

  The object of the present invention is to provide a methacrylic copolymer having at least 25% by weight of methyl methacrylate and having an unsaturated double bond group in the side chain, a polyfunctional unsaturated monomer, and a photocrosslinking initiator. This is achieved by the containing photocurable resin composition.

  Since the photocurable resin composition according to the present invention has a practically sufficient hardness and moderate elongation after photocuring, it can be used for various sheet materials, tubes, gaskets, packing, surface treatment agents for desks and metal products, and soundproof walls. It can be used effectively for applications such as cover materials.

  In particular, from the viewpoint of appearance such as solvent resistance, scratch resistance, abrasion resistance, and gloss of photocured products, ABS resin for automobiles, vinyl chloride resin, polymethyl methacrylate resin, polycarbonate resin exterior resin parts It can be suitably used as a surface coating material. Moreover, the film formed there does not pollute the environment and has film performance comparable to that of solvent-based paints.

  A feature of the present invention is that, as a copolymer having an unsaturated double bond group in the side chain which is a photocurable resin component, methyl methacrylate is at least about 25% by weight, generally about 30 to 80% by weight. Preferably, a methacrylic copolymer copolymerized by about 35 to 75% by weight is used.

  The acrylic rubber which is a photocurable component described in Patent Document 2 is used for introducing alkyl acrylate and / or alkoxyalkyl acrylate in an amount of 55 to 99.99% by weight and an unsaturated double bond as a crosslinking point into a side chain. It is said that 0.01 to 20% by weight of the monomer is essentially present, and 0 to 20% by weight of the monomer copolymerizable therewith can be copolymerized, and there is an alicyclic alcohol or aromatic alcohol. No description of methyl methacrylate is found.

  As can be seen from the results of Comparative Example 4 described later, the ethyl acrylate-dihydrodicyclopentadienyl monoacrylate (weight ratio 97: 3) copolymer has a very low hardness of the photocured film, and at least methyl methacrylate is present. Such a decrease in hardness is not observed in the methacrylic copolymer of the present invention copolymerized by about 25% by weight. However, when the copolymerization ratio of methyl methacrylate is about 80% by weight or more, scratch resistance is lowered, which is not preferable.

  The methacrylic copolymer of the present invention obtained by copolymerizing methyl methacrylate at such a ratio has an unsaturated double bond group in the side chain as a photocrosslinkable group.

  Introduction of an unsaturated double bond into the side chain is, for example, dicyclodihydropentenyl ester or α-β-unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid or dicyclodihydropentenyloxy. Ethyl ester, vinyl (meth) acrylate, allyl (meth) acrylate, 3-cyclohexenylmethyl (meth) acrylate, dicyclopentadiene, methyldicyclopentadiene, ethylidene norbornene, 1,1-dimethylpropenyl (meth) acrylate, 3 , 3-Dimethylbutenyl (meth) acrylate, vinyl 1,1-dimethylpropenyl ether, vinyl 3,3-dimethylbutenyl ether, 1- (meth) acryloyloxy-1-phenylethene, 1- (meth) acryloyloxy At least one such as -2-phenylethene is about 0.01-20% by weight, preferably about 0.1-10% by weight It is copolymerized at a ratio.

  In addition to the above essential copolymerization components, alkyl (meth) acrylates other than methyl methacrylate such as methyl acrylate, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, pentyl, isopentyl, hexyl, 2-ethylhexyl, octyl , Nonyl, decyl, lauryl, stearyl and the like and at least one of the corresponding methacrylic acid esters (excluding the methyl ester) in a proportion of about 30 to 70% by weight, preferably about 5 to 60% by weight. It can be polymerized.

  In addition to the above (meth) acrylic acid esters, vinyl monomers copolymerizable therewith, such as styrene, α-methylstyrene, halogenated styrene, vinyl toluene, vinyl pyridine, vinyl naphthalene, (meth) acrylonitrile, (Meth) acrylamide, N-methylolacrylamide, vinyl acetate, vinyl chloride, vinylidene chloride, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, and the like can be further copolymerized at a ratio of about 20% by weight or less.

The copolymerization reaction can be performed by any polymerization method such as suspension polymerization, emulsion polymerization, solution polymerization, and the polymerization rate is 90% or more, so the proportion of the comonomer used is almost as it is. The composition of the copolymer. The resulting methacrylic copolymer has a Mooney viscosity ML _{1 + 4} (125 ° C.) according to JIS K-6300 of about 10 to 100, preferably about 20 to 80.

  The methacrylic copolymer has about 1 to 200 parts by weight, preferably about 10 to 100 parts by weight of polyfunctional unsaturated monomer, about 0.01 to 20 parts by weight, preferably about 0.1 to 100 parts by weight per 100 parts by weight. 10 parts by weight of a photocrosslinking initiator is added, and further, if necessary, about 200 parts by weight or less, preferably about 10 to 100 parts by weight of amorphous silica is added to form a photocrosslinkable resin composition.

  Examples of polyfunctional unsaturated monomers include alkylene glycol diacrylates such as ethylene glycol diacrylate and propylene glycol diacrylate, polyalkylene glycol diacrylates such as polyethylene glycol diacrylate and polypropylene glycol diacrylate, and isocyanuric acid ethylene oxide modified Acrylic acid esters such as triacrylate, trimethylolpropane ethylene oxide modified triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, dimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, or the corresponding methacrylic acid esters, triaryl Rucyanurate, triallyl isocyanurate, N, N'- At least one type such as m-phenylene dimaleimide is used, and acrylate-based ones are preferably used from the viewpoint of reactivity to ultraviolet irradiation.

  The photocrosslinking initiator is a compound that is easily decomposed by light irradiation to give a radical, and is not particularly limited. For example, acetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, p-dimethylamino Acetophenones such as propylacetophenone, p-tert-butyltrichloroacetophenone, benzophenone, 2-chlorobenzophenone, p, p'-dichlorobenzophenone, benzophenones such as p, p'-bisdimethylaminobenzophenone, benzyl, benzoin, benzoin n Benzoin ethers such as -propyl ether, benzyl ketals such as benzyldimethyl ketal and benzylmethyl ketal, benzoylbenzoate, and α-acyloxy esters such as benzyl (o-ethoxycarbonyl) α-monooxime It is needed.

  Furthermore, the amorphous silica added as necessary may be either dry silica or wet silica, such as precipitated silica, airgel silica, fumed silica, and surface-treated silica obtained by treating these surfaces with an organic silyl group or the like. At least one type is used.

  In addition to these components, ultraviolet absorbers for improving weather resistance, antioxidants, lubricants for improving processability, plasticizers, various pigments for adjusting the color of coatings, polyfunctional unsaturated mono-monomers. A composition can be prepared by appropriately blending a polymerization inhibitor or the like for suppressing premature polymerization of the monomer.

  The photocurable resin composition is prepared using a closed kneader such as an open roll mixer or a kneader, a single screw extruder, a twin screw extruder, an extrusion kneader, or the like. Alternatively, the composition can also be prepared by adding a necessary compounding agent to a latex of a methacrylic copolymer obtained by suspension polymerization or emulsion polymerization or a solution-polymerized methacrylic copolymer solution and drying. .

  The photocurable resin composition thus prepared is formed into a film by a hot roll, etc., pelletized by a pelletizer, etc., and then formed into a thin film by an open roll, tube formation by an extruder, sheet insert molding, multilayer injection After adhesion molding on various substrate surfaces such as metal, plastic, electric wire, glass, etc. by molding, etc., it is photocured by irradiation with ultraviolet rays, visible light, etc., and various sheet materials, tubes, gaskets, packing, surface coating materials, etc. To form.

  Next, the present invention will be described with reference to examples.

Reference example 1
In a 3 L separable flask equipped with a stirrer, thermometer, nitrogen gas inlet tube and decompression device, 250 g (50% by weight) of methyl methacrylate, 235 g (47% by weight) of n-butyl acrylate, and 3-cyclohexenylmethyl After charging 15 g (3% by weight) of monomethacrylate, 27.5 g of sodium lauryl sulfate and 750 ml of water, repeating degassing and nitrogen gas replacement to sufficiently remove oxygen in the system,
Sodium hydrosulfite 0.05g
Sodium formaldehyde sulfoxylate 0.01g
Tertiary butyl hydroperoxide 0.025g
The polymerization initiator which consists of was added, and the polymerization reaction was started at room temperature.

Thereafter, the reaction at 50 ° C. was continued for 6 hours until the polymerization conversion rate reached 93.4%, and the resulting aqueous latex was salted out, washed with water and dried to obtain a methacrylic acid having a Mooney viscosity ML _{1 + 4} (125 ° C.) of 71. 467 g of copolymer A was obtained.

This copolymer was pressed under the conditions of 150 ° C, 200Kg / cm ² G, 1 minute to form a film with a thickness of 0.5 mm, and when Wallace hardness (Hw) was measured, a value of 90 was obtained. Further, when the elongation elongation (based on JIS K-6301; elongation speed: 500 mm / min) was measured, a value of 345% was obtained.

Reference Examples 2-7
In Example 1, the monomer composition was variously changed, and the results shown in Table 1 below were obtained.
Table 1
Reference example
1 2 3 4 5 6 7
[Monomer composition; wt%]
Methyl methacrylate 50 50 50 50 100 50
Ethyl acrylate 97
n-Butyl acrylate 47 45 47 49 50
3-Cyclohexenylmethyl 3 5
Monomethacrylate dihydrodicyclopentadi 3 3
Anyyl acrylate Allyl methacrylate 1
[Methacrylic copolymer]
Abbreviation ABCDEFG
Polymerization rate (%) 93.4 90.6 99.0 97.1 94.0 96.6 98.1
Mooney viscosity ML _{1 + 4} 71 65 70 34-51 42
[Film characteristics]
Hardness (Hw) 90 92 89 81 100 81 30
Elongation (%) 345 360 315 125 0 395 850

Example 1
To a kneader with an internal volume of 250 ml,
Methacrylic copolymer A 120 g (75 parts by weight)
Trifunctional acrylate oligomer 40g (25 parts by weight)
(Toa Gosei product Aronix M-315)
Photoinitiator 2.6g (1.625 parts by weight)
(Novartis Japan Product Irgacure 184)
After kneading for 1 hour, the film was formed into a 4-inch open roll heated to 120 ° C. to form a thin film having a thickness of 0.5 mm.

This thin film was irradiated with ultraviolet light for 10 seconds, 30 seconds or 60 seconds under the conditions of a UV intensity of 56 mw / cm ² and an irradiation distance of 24 cm using a high pressure mercury lamp manufactured by Ushio Electric to carry out a photocuring reaction. The obtained cured thin film was measured for Wallace hardness (Hw) and elongation elongation in the same manner as in Reference Example 1, and the following test was performed to confirm the degree of curing of the cured thin film.
Surface rubbing test with xylene [Test I]:
Press 10 layers of gauze impregnated with xylene onto the cured thin film and visually observe the cured thin film surface after 8 reciprocating rubbing. No abnormalities ○, scratches, whitening etc., small △, large × Scratch resistance test evaluated as dissolution XX [Test II]:
Press the turtle scourer against the cured thin film surface in running water and visually observe the cured thin film surface after 20 reciprocating rubs. No abnormality ○, small scratch △, large ×, scratch large and opaque Was evaluated as xx

Example 2
In Example 1, instead of methacrylic copolymer A, the same amount of methacrylic copolymer B was used.

Example 3
In Example 1, instead of methacrylic copolymer A, the same amount of methacrylic copolymer C was used.

Example 4
In Example 1, instead of methacrylic copolymer A, the same amount of methacrylic copolymer D was used.

Comparative Example 1
Measurements and tests similar to those in Example 1 were carried out on the methacrylic copolymer E alone in the heat press and the ultraviolet irradiated product.

Comparative Example 2
Measurements and tests similar to those in Example 1 were carried out for the methacrylic copolymer F alone heat-pressed and ultraviolet irradiated material.

Comparative Example 3
In Example 1, instead of methacrylic copolymer A, the same amount of methacrylic copolymer F was used.

Comparative Example 4
In Example 1, instead of methacrylic copolymer A, the same amount of methacrylic copolymer G was used.

The measurement results in the above examples and comparative examples are shown in the following Table 2.
Table 2
Measurement / Test UV Irradiation Examples Comparative Example
Item (seconds) 1 2 3 4 1 2 3 4
Hardness (Hw) 10 96 98 96 95 100 82 97 60
30 99 99 98 98 100 85 99 65
60 99 99 99 99 100 88 99 66
Elongation (%) 10 80 60 70 55 0 390 140 100
30 10 10 25 25 0 420 110 40
60 0 0 0 0 0 450 20 20
Test I 10 × △ × × ×× ×× ×× ×
30 △ ○ △ △ ×× ×× ×× △
60 △ ○ △ △ ×× ×× ×× △
Test II 10 × △ × × × × × ×
30 △ ○ △ △ × × × △
60 ○ ○ ○ ○ × × △ △

From the above results, the following can be said.
(1) From the comparison between each example and Comparative Examples 1 and 2, it was confirmed that the xylene rubbing property was improved as compared with known thermoplastic resins, and that it had sufficient scratch resistance. The
(2) From the comparison between each Example and Comparative Example 3, the oxyethylene chain introduced into the copolymer side chain and the C = C bond were reacted with the polyfunctional acrylate to improve the xylene rubbing property Is confirmed.
(3) From the comparison between each Example and Comparative Example 4, it can be seen that the copolymer composition having a specific configuration is effective in increasing the hardness of the ultraviolet cured product and improving the scratch resistance.

Claims (2)

  Photocurability comprising a methacrylic copolymer having at least 25% by weight of methyl methacrylate and having an unsaturated double bond group in the side chain, a polyfunctional unsaturated monomer and a photocrosslinking initiator Resin composition.   2. The photocurable resin composition according to claim 1, further comprising amorphous silica.