JP4880249B2 - Photoradical crosslinking polymer and photocurable resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a photoradical crosslinking polymer for preventing strain and crack after curing and molding, a photocurable resin composition and to provide a method for producing the photoradical crosslinking polymer. <P>SOLUTION: The photoradical crosslinking polymer is a polymer containing a (meth)acryloyl group in a molecular structure, has 2,000-100,000 molecular weight and is crosslinkable by irradiation with energy rays. The photoradical crosslinking polymer is obtained by polymerizing a monomer component containing a functional group to be modified with (meth)acrylic acid to give a polymer and modifying the polymer with (meth)acrylic acid. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a polymer capable of three-dimensional curing by irradiation with ultraviolet rays and other active energy rays (light rays and radiation capable of generating active species), and a resin composition containing the same. In particular, the present invention relates to one that is three-dimensionalized by radical polymerization reaction between (meth) acryloyl groups. In this specification, terms such as photoradical crosslinking and photocurability are used, including the case where a crosslinking reaction is induced by active energy rays other than light.

Conventionally, as a method of forming a coating film, a thermosetting type or a solvent type is generally used. However, the thermosetting type is not suitable for a substrate having no heat resistance, and the solvent type is not suitable for the environment. There was a problem that the load was large. In recent years, a coating method using a resin curable by irradiation with energy rays has been developed in various fields as a method instead of these (JP-A-5-179156, etc.).
JP-A-5-179156

  However, in the photo radical polymerization type, there is a problem that the shrinkage at the time of curing is large and the cured product is distorted and distorted. Distortion and cracking after molding due to shrinkage during curing is particularly a problem in molded articles such as optical fibers. In light of the above, an object of the present invention is to provide a photoradical crosslinking polymer, a photocurable resin composition, and a method for producing the same that can prevent distortion and cracking after curing molding in a photocurable resin.

  As a result of intensive studies in view of these circumstances, the inventors of the present invention have found that curing shrinkage can be reduced by introducing a (meth) acryloyl group into a polymer molecular structure into a pendant type.

That photoradical crosslinked polymers of the present invention is to obtain a polymer by polymerization of a monomer component containing a styrene and epoxycyclohexylmethyl methacrylate, there the polymer in the photo-radical crosslinkable polymer that is obtained by modifying an acrylic acid And the molar ratio of styrene, epoxycyclohexylmethyl methacrylate and acrylic acid is 1.0: 1.0: 0.5, the molecular weight (Mn) is 5,600-56,000, It shall be crosslinkable.

Furthermore, the photocurable resin composition of the present invention comprises 1 part by weight of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator and methyl isobutyl ketone as a diluent with respect to 100 parts by weight of the photoradical crosslinking polymer of the present invention. It contains 100 parts by weight, and the volume shrinkage during three-dimensional crosslinking is 0.5% or less.

  According to the resin composition using the photoradical crosslinking polymer of the present invention, since the curing shrinkage is small, there is almost no problem of distortion and cracking of the cured product. Since the cured product has good transparency, it can be applied to the optical field.

  Moreover, the glass transition point of a resin composition can be adjusted with the combination and composition ratio of a structural monomer, and it can be made tack-free before hardening by making the glass transition point before hardening high. Therefore, there is an advantage that a dry film can be formed so as not to be dusty even in a state before curing.

  The polymer containing a (meth) acryloyl group, which is a photoradical crosslinking polymer of the present invention, can be obtained by polymerizing a monomer containing a (meth) acryloyl group-containing monomer capable of radical polymerization.

  Preferably, (1) a functional group that can be modified with (meth) acrylic acid, such as an epoxy group or a hydroxyl group, and a monomer having radical reactivity, and (2) (meth) acrylic acid It does not contain a functional group that can be modified, and is obtained by modifying a polymer obtained by polymerizing a monomer having radical reactivity with (meth) acrylic acid.

  The monomer (1) containing a functional group and radical reactivity that can be modified by (meth) acrylic acid, which is a polymerization component of the polymer, has 1 to 3 epoxy groups or hydroxyl groups and one radical reactive group. It has.

  Examples of such a functional group that can be modified with (meth) acrylic acid and a monomer (1) containing radical reactivity include (meth) acrylic acid esters containing an epoxy group, epoxy group containing Styrene derivatives, fumaric acid esters containing epoxy groups, vinyl compounds containing epoxy groups, (meth) acrylic acid esters containing hydroxyl groups, styrene derivatives containing hydroxyl groups, fumaric acids containing hydroxyl groups Examples include esters and vinyl compounds containing a hydroxyl group.

  More specifically, epoxy cyclomethyl acrylate, epoxy cyclohexyl methyl methacrylate, glycidyl acrylate, glycidyl methacrylate, [(4-ethenylphenyl) methyl] oxirane, 4- (glycidyloxy) styrene, 4-vinyl epoxycyclohexane, Examples include diglycidyl fumarate, diepoxycyclohexylmethyl fumarate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate.

  As the monomer (2) having no functional group that can be modified with (meth) acrylic acid used as a polymerization component of other polymers, various known monomers can be used. For example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, (Meth) acryloylmorpholine, (meth) acrylamide, dicyclohexyl fumarate, dibenzyl fumarate, dibutyl fumarate, vinyl caprolactam, vinyl pyrrolidone, vinyl acetate, styrene and the like.

  When such a monomer having no functional group that can be modified with (meth) acrylic acid is used, the (meth) acrylic acid in the total number of moles of the radical polymerizable monomer ((1) + (2)) The mole fraction of the monomer (1) having a functional group that can be modified, that is, (the number of moles of the monomer having a functional group that can be modified by (meth) acrylic acid) / (total of radical polymerizable monomers) The number of moles) is preferably 0.2 to 0.75.

  Further, the molar fraction when the functional group of the polymer synthesized as described above is modified with (meth) acrylic acid, that is, ((meth) acrylic acid mole number) / (polymer functional group mole number) is 0.1 to 0.1. 1.0 is preferable. From such copolymerization and (meth) acrylic acid-modified molar fraction, the physical properties of the cured product can be easily adjusted to a preferable one.

  When the resin composition of the present invention is made into a paint, it can be diluted with an organic solvent and monomers such as ethyl acetate and toluene, and when diluted with a monomer, the polymer in the sum of the polymer and the monomer can be diluted. The content is desirably 30% by weight or more.

  As the monomers used for the dilution, known and commonly used monomers such as vinyl ether compounds, propenyl ether compounds, styrene derivatives, epoxy compounds, lactone compounds, oxetane compounds can be used. These may be used independently and may use multiple types together.

  If necessary, a photopolymerization initiator is added to the energy ray-crosslinking resin composition of the present invention.

  The type of the photopolymerization initiator is not particularly limited, and known ones can be used. Typical examples include 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1-phenylpropane-1. -One, benzyl dimethyl ketal, benzoin isopropyl ether, benzophenone and the like. These may be used alone or in combination.

  Moreover, the addition amount in the case of using a photoinitiator is about 0.1 to 10 weight% with respect to the sum total of the (meth) acryloyl group containing polymer and the said monomer used as needed, about 1 ~ 5 wt% is preferred.

  Furthermore, the photoradical crosslinkable polymer of the present invention includes a light stabilizer, an ultraviolet absorber, a catalyst, a leveling agent, an antifoaming agent, a polymerization accelerator, an antioxidant, a flame retardant, an infrared absorber, if necessary. Etc. can be added.

  The energy ray source for curing the photoradical crosslinking polymer of the present invention is not particularly limited, and examples thereof include a high pressure mercury lamp, an electron beam, a γ ray, a carbon arc lamp, a xenon lamp, and a metal halide lamp.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to these Examples at all. In the following, the blending ratio and “%” are all based on weight unless otherwise specified.

[Example 1]
The flask was charged with 350 g of methyl isobutyl ketone and heated while introducing nitrogen to obtain a reflux temperature. 100-105 ° C. while dropwise adding 104 g (1.0 mol) of styrene, 205 g (1.0 mol) of epoxycyclohexylmethyl methacrylate, 30.9 g of α-methylstyrene dimer, and 15 g of lauroyl peroxide. To obtain a polymer A solution.

  To this polymer A solution, 36 g (0.5 mol) of acrylic acid, 3 g of triphenylphosphine, and 0.3 g of hydroquinone monomethyl ether were added and reacted at 90 to 110 ° C. until the acid value was 4 mgKOH / g or less. A polymer containing acryloyl groups was obtained. The obtained polymer was refine | purified with methanol, and the polymer containing the acryloyl group of molecular weight (Mn) 5600 (GPC styrene conversion) was obtained.

[Example 2]
A flask is charged with 150 g of methyl isobutyl ketone, 104 g (1.0 mol) of styrene, 205 g (1.0 mol) of epoxycyclohexylmethyl methacrylate and 3 g of lauroyl peroxide, and is introduced for 8 hours under conditions of 75 to 80 ° C. while introducing nitrogen. The polymer B solution was obtained by reacting.

  To this polymer B solution, 300 g of methyl isobutyl ketone, 36 g (0.5 mol) of acrylic acid, 3 g of triphenylphosphine, and 0.3 g of hydroquinone monomethyl ether were added, and the acid value was reduced to 4 mgKOH / g or less at 90 to 110 ° C. The reaction was continued until a polymer containing an acryloyl group was obtained. The obtained polymer was refine | purified with methanol, and the polymer containing the acryloyl group of molecular weight (Mn) 56000 (GPC styrene conversion) was obtained.

[Comparative Synthesis Example 1]
504 g (1 mol) of isocyanurate type trimer of hexamethylene diisocyanate, 0.47 g of hydroquinone monomethyl ether, 429 g (3.3 mol) of 2-hydroxypropyl acrylate, and the residual isocyanate concentration is 70 to 80 ° C. It was made to react until it became 0.1%, and urethane acrylate was obtained.

[Comparative Synthesis Example 2]
380 g (1 mol) of bisphenol A diglycidyl ether (standard type), 144 g (2 mol) of acrylic acid, 0.26 g of hydroquinone monomethyl ether and 2.62 g of tetrabutylammonium bromide are charged, and the acid value is 90 to 100 ° C. Was reacted until 5 mgKOH / g or less was obtained, to obtain an epoxy acrylate.

[Examples 1 and 2, Comparative Examples 1 and 2]
The polymer obtained in the above synthesis example and the urethane acrylate and epoxy acrylate obtained in the comparative synthesis example were cured in the following manner, and the physical properties and the like were measured and evaluated. The results are shown in Table 1.

Curing conditions A resin composition blended and uniformly dissolved in the ratio (parts by weight) shown in Table 1 was applied onto a glass plate with a 200 μm applicator bar, dried at 110 ° C. for 1 hour in a vacuum dryer, Ultraviolet rays with an integrated illuminance of 340 mJ / cm ² were irradiated using a 80 W / cm high-pressure mercury lamp.

-Tackiness After volatilizing the solvent, the surface was touched with a finger, and the presence or absence of tack was evaluated according to the following criteria.
○: No stickiness.
X: There is stickiness.

・ Curing property (gelation rate)
The cured film was immersed in methylene chloride for 18 hours to extract an uncured part and dried at 105 ° C. for 3 hours. From the weight before methylene chloride immersion and the weight after drying, the gelation rate was determined by the following formula.
Gelation rate (%) = (weight after drying / weight before immersion) × 100

・ Curing shrinkage (volumetric shrinkage)
The specific gravity at 20 ° C. before and after curing of the resin cured under the following conditions was measured with a pycnometer, and the volume shrinkage was obtained by the following formula.
Volume shrinkage (%) = [(specific gravity after curing−specific gravity before curing) / specific gravity after curing] × 100

・ Glass transition point (before curing)
It calculated | required from the inflection point of the baseline of differential scanning calorimetry (DSC).

・ Glass transition point (after curing)
It was determined from the maximum point of tan δ of the rheograph.

-Transparency The transparency of the cured product was visually determined according to the following criteria.
○: Transparent.
X: There is turbidity.

  According to the photoradical crosslinkable polymer of the present invention, since the curing shrinkage is small, there is almost no problem of distortion and cracking of the cured product. Since the glass transition point before curing is high, it can be tack-free before curing. Therefore, it can be used for forming various molded bodies and coating films.

Further, since it has good transparency, it can be applied to the optical field.

Claims (2)

To obtain a polymer by polymerization of a monomer component containing a styrene and epoxycyclohexylmethyl methacrylate, the polymer a photo radical-crosslinkable polymer that is obtained by modifying the acrylic acid, the styrene, epoxycyclohexylmethyl methacrylate and acrylic A photoradical characterized in that the molar ratio of acid is 1.0: 1.0: 0.5, the molecular weight (Mn) is 5,600-56,000, and can be crosslinked by irradiation with energy rays. Cross-linked polymer.   3 parts cross-linking containing 1 part by weight of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator and 100 parts by weight of methyl isobutyl ketone as a diluent with respect to 100 parts by weight of the photoradical crosslinking polymer according to claim 1 A photocurable resin composition having a volumetric shrinkage at the time of 0.5% or less.