TWI445741B - Acrylic fine particles and diffusing film including the same - Google Patents

Description

Acrylic particles and diffusion film containing the same

The present invention relates to acrylic fine particles and a diffusing film containing the same. More particularly, the present invention relates to such acrylic fine particles and a diffusion film containing the same, which have excellent compatibility with a binder and a solvent while maintaining high heat resistance and solvent resistance, and thus When the acrylic fine particles are applied to a diffusion film, excellent dispersibility is exhibited.

Acrylic microparticles are widely used as light diffusing agents, coating additives, various surface treating agents, carriers, and the like. In particular, acrylic particles are used as light diffusing agents to provide light diffusion effects for diffusion films, light diffusing panels, lighting devices, and billboards.

Acrylic microparticles are usually prepared by suspension polymerization and have a spherical bead shape.

In order to apply such acrylic fine particles to a diffusion film, the (spherical) beads are required to have solvent resistance (chemical resistance) to maintain processability and coating solution stability. For this purpose, a method for increasing the crosslinking density of acrylic fine particles has been proposed. That is, acrylic fine particles containing more crosslinking functional groups or more crosslinking agents are used to increase the crosslinking density. However, when acrylic particles having a higher crosslinking density and polyfunctional groups are used as a diffusing agent only in consideration of solvent resistance, the compatibility of the acrylic particles with the solvent is deteriorated, so that the acrylic particles are agglomerated into a block. . The acrylic microparticles do not coalesce in a non-polar solvent such as BTX used for the coating solution. However, since acrylic particles are less compatible with polar solvents such as methyl ethyl ketone (MEK), ethanol, methanol, etc., they coalesce. Thus, the quality of the product is not good because the diffusing agent cannot be uniformly dispersed and deposited.

Therefore, companies that coat and (film) films cannot conveniently select solvents according to the characteristics of various diffusion particles, and there are technical limitations in improving optical performance and efficiency.

The (some) aspects of the present invention provide acrylic fine particles which have excellent compatibility with a binder and a solvent while maintaining high crosslinking, and when applied to a diffusion film, significantly improve dispersibility and performance High heat resistance and excellent solvent resistance. Further, the (some) aspects of the present invention also provide a diffusion film containing acrylic fine particles and having excellent transmittance and diffusibility.

One aspect of the invention provides acrylic microparticles. The acrylic microparticles are formed by polymerizing a monomer and a crosslinking agent, wherein the monomer comprises a (meth) acrylate, and wherein the crosslinking agent comprises a first crosslinking agent having at least three (A) (meth)acryl groups, and at least one functional group in -OH and -COOH. The coefficient of variation (C.V.) of the acrylic fine particles is from 20% to 60%, preferably from 40% to 60%.

In one embodiment, the first crosslinking agent can be represented by Formula 1:

(Y) _i -R-(Q) _j ,

Wherein Y is a (meth) propylene oxirane group, R is a C1-C10 branched hydrocarbon, Q is -OH or -COOH, i is an integer of 3-5, and j is an integer of 1-5.

The acrylic microparticles may contain from 60 wt% to 90 wt% of the monomer and from 10 wt% to 40 wt% of the crosslinker. For example, the acrylic microparticles may contain from 60 wt% to 85 wt% of the monomer and from 15 wt% to 40 wt% of the crosslinker.

The (meth) acrylate-containing monomer may contain a C1-C10 alkyl (meth) acrylate and a monomer copolymerizable therewith.

The (meth) acrylate-containing monomer may contain 50 wt% to 100 wt% of a C1-C10 alkyl (meth)acrylate and 0-50 wt% of a copolymerizable monomer.

The copolymerizable monomer may contain an aromatic vinyl monomer, a cyanide vinyl monomer, a C6-C20 aromatic (meth)acrylate, a hydroxyl group-containing (meth) acrylate, an epoxy group-containing (A) At least one of an acrylate and an unsaturated carboxylic acid.

The crosslinking agent may include a first crosslinking agent having at least three (meth) acryloxy groups and at least one of -OH and -COOH, the second crosslinking agent, the second The crosslinking agent is selected from the group consisting of 1,4-butanediol di(meth)acrylate and 1,6-hexanediol di(meth)acrylate (1,6). -hexanediol di(meth)acrylate), 1,9-nonanediol di(meth)acrylate, ethylene glycol di(ethylene) di(meth)acrylate (meth)acrylate), propylene glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tris(methyl) a group of trimethylolpropane tri(meth)acrylate and ditrimethylolpropane tetra(meth)acrylate.

The crosslinking agent may contain from 60 wt% to 100 wt% of the first crosslinker and from 0 to 40 wt% of the second crosslinker.

The weight ratio of the first crosslinking agent to the second crosslinking agent may be from 1.5:1 to 10:1.

The acrylic microparticles were placed in methyl ethyl ketone at 25 ° C for 4 hours, and the swelling ratio was less than 10%.

Another aspect of the invention provides a diffusing film comprising acrylic microparticles.

Yet another aspect of the invention provides a method of making acrylic microparticles. The method comprises preparing a monomer mixture solution by mixing a (meth) acrylate-containing monomer with a crosslinking agent and an initiator, and suspending polymerization of the monomer mixture solution.

The above and other aspects, features and advantages of the present invention will become apparent from the Detailed Description.

Embodiments of the invention will be described in detail below. It should be noted that these embodiments are for illustrative purposes only and are not to be construed as limiting the invention in any way. The scope of the invention should be limited only by the scope of the appended claims and their equivalents.

Unless otherwise defined, the term "(meth)acrylate" is collectively referred to as both acrylate and methacrylate. Further, "(meth)acrylic acid" is collectively referred to as both acrylic acid and methacrylic acid. Moreover, "(meth)acrylamide" is collectively referred to as both acrylamide and methacrylamide.

The acrylic fine particles according to the present invention are formed by polymerizing a monomer and a crosslinking agent, wherein the monomer includes a (meth) acrylate, and wherein the crosslinking agent includes a first crosslinking agent. The first crosslinking agent includes at least three (meth) acryloxy groups and at least one functional group of -OH and -COOH.

In one embodiment, the acrylic microparticles may contain from 60 wt% to 90 wt% of the monomer and from 10 wt% to 40 wt% of the crosslinker. In particular, the acrylic microparticles may contain from 60 wt% to 85 wt% of the monomer and from 15 wt% to 40 wt% of the crosslinker. Within this range, high solvent resistance can be obtained.

The monomer may include a C1-C10 alkyl (meth)acrylate and a monomer copolymerizable therewith.

In one embodiment, the monomer may contain from 50 wt% to 100 wt% of a C1-C10 alkyl (meth)acrylate and optionally 50 wt% or less of a copolymerizable monomer. In particular, the monomer may contain from 60 wt% to 100 wt% of a C1-C10 alkyl (meth)acrylate and from 0 to 40 wt% of a copolymerizable monomer. Within this range, excellent dispersibility can be obtained.

Examples of the C1-C10 alkyl (meth)acrylate may include: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, ( Isobutyl methacrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, and the like. In particular, methyl (meth)acrylate can be used.

Examples of copolymerizable monomers may include, but are not limited to, aromatic vinyl monomers such as styrene, p-methylstyrene, m-methylstyrene, p-ethylstyrene, m-ethylstyrene, p-chlorostyrene , m-chlorostyrene, p-chloromethylstyrene, m-chloromethylstyrene, vinyltoluene, and vinylnaphthalene; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; (meth)acrylic acid C6 -C20 aromatic esters such as phenyl (meth) acrylate, benzyl (meth) acrylate, 2-phenylethyl (meth) acrylate, 3-phenylpropyl (meth) acrylate, (meth) acrylate 4 - phenylbutyl ester, 2-2-methylphenylethyl (meth)acrylate, 2-methylphenylethyl (meth)acrylate, and 2-methylbenzene (meth)acrylate Ethyl ester; hydroxyl group-containing (meth) acrylate such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (A) 2-hydroxybutyl acrylate, 6-hydroxyhexyl (meth) acrylate, 1,4-cyclohexane dimethanol mono (meth) acrylate; epoxy group-containing (meth) acrylate, such as Glycidyl acrylate and glycidyl methacrylate; Unsaturated carboxylic acids such as acrylic acid and methacrylic acid; and the like. These monomers may be used alone or as a mixture.

In one embodiment, the acrylic microparticles may contain 90 wt% or more, preferably 92 wt% to 100 wt% of methyl methacrylate as a monomer component. Within this range, the acrylic fine particles as a diffusing agent may have a suitable refractive index of 1.35 to 1.55 while maintaining solvent resistance.

In one embodiment, the crosslinking agent can include only the first crosslinking agent.

Alternatively, the crosslinking agent can comprise a mixture of a first crosslinking agent and a second crosslinking agent.

In one embodiment, the crosslinking agent may include from 60 wt% to 100 wt% of the first crosslinker and optionally 40 wt% or less of the second crosslinker. Within this range, excellent solvent resistance and polymerization stability can be obtained. In particular, the crosslinking agent may contain from 65 wt% to 95 wt% of the first crosslinker and from 5 wt% to 35 wt% of the second crosslinker.

When the crosslinking agent comprises a mixture of the first crosslinking agent and the second crosslinking agent, the weight ratio of the first crosslinking agent to the second crosslinking agent may be from 1.5:1 to 10:1, preferably from 2 to 8:1. . Within this range, excellent solvent resistance and dispersibility can be obtained.

The first crosslinking agent may have at least three (meth) acryloxy groups and at least one functional group of -OH and -COOH.

In one embodiment, the first crosslinking agent can be represented by Formula 1:

(Y) _i -R-(Q) _j ,

Wherein Y is a (meth) propylene oxirane group, R is a C1-C10 branched hydrocarbon, Q is -OH or -COOH, i is an integer of 3-5, and j is an integer of 1-5.

Examples of the first crosslinking agent may include pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and the like, which may be used singly or as a mixture. In particular, pentaerythritol triacrylate can be used.

Examples of the second crosslinking agent may include: 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-bis(meth)acrylate Decylene glycol ester, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, di(three) Hydroxymethylpropane) tetra(meth)acrylate or the like. In particular, 1,6-hexanediol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate can be used.

The acrylic microparticles can be prepared by any polymerization method known in the art, for example, bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and the like. In particular, suspension polymerization can be used.

In one embodiment, the acrylic fine particles can be prepared by mixing a (meth) acrylate-containing monomer with a crosslinking agent, followed by adding a polymerization initiator and adding a suspension stabilizer to carry out polymerization. Here, the polymerization is carried out at 30 ° C to 120 ° C, preferably at 50 ° C to 90 ° C.

The polymerization initiator may be at least one selected from the group consisting of, but is not limited thereto: a peroxide compound such as benzamidine peroxide, laurel peroxide, o-chlorobenzidine peroxide, ortho-peroxide Oxybenzamide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate , dioctyl peroxide, and dioxane; and azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile) And 2,2'-azobis(2,4-dimethylvaleronitrile). The polymerization initiator may be present in an amount of from 0.1 part by weight to 20 parts by weight per 100 parts by weight of the mixture of the monomer and the crosslinking agent.

Suspension stabilizers may include, but are not limited to, water soluble high molecular weight molecules such as gelatin, starch, methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, polyvinylalkane Ether, polyvinyl alcohol, polyacrylic acid, polypropylene decylamine, polyethylene oxide, sodium polymethacrylate and polydimethyl siloxane/polystyrene block copolymer, barium sulfate, calcium lactate, carbonic acid Calcium, calcium phosphate, aluminum lactate, talc, clay, diatomaceous earth and metal oxide powder. The suspension stabilizer may be used in an amount of from about 0.01 part by weight to about 20 parts by weight based on about 100 parts by weight of the mixture of the monomer and the crosslinking agent.

The acrylic fine particles prepared as above may have a volume average size of from 1 μm to 50 μm, preferably from 10 μm to 30 μm, and a coefficient of variation of from 20% to 60%, preferably from 30% to 60%, more preferably from 40% to 60%.

In one embodiment, the acrylic microparticles have a swelling ratio of less than 10%, preferably less than 5%, more preferably less than 1% or less after 4 hours of placement in MEK at 25 °C.

In another aspect of the invention, a diffusing film comprising acrylic microparticles is provided.

The diffusion film can be prepared by mixing a transparent thermoplastic resin with acrylic fine particles. In one embodiment, the acrylic fine particles may be present in an amount of from 0.1 part by weight to 50 parts by weight, based on 100 parts by weight of the transparent thermoplastic resin, preferably from 10 parts by weight to 35 parts by weight.

Examples of the transparent thermoplastic resin may include, but are not limited to, a (meth)acrylic resin, a polycarbonate resin, a polyester resin, an aromatic vinyl resin, and the like.

A diffusion film using acrylic fine particles as a diffusing agent has excellent diffusibility and transmittance.

Hereinafter, the constitution and function of the present invention will be explained in more detail with reference to the following examples. These examples are provided for illustrative purposes only and are not to be construed as limiting the invention in any way.

Descriptions of details apparent to those skilled in the art will be omitted below.

Instance

Examples 1 and 2 and Comparative Examples 1-3: Preparation of Acrylic Microparticles

Example 1

70 parts by weight of methyl methacrylate (MMA), 20 parts by weight of pentaerythritol triacrylate as a first crosslinking agent, and 10 parts by weight of trimethylolpropane triacrylate as a second crosslinking agent (TMPTA) mixing. To the mixture, 1 part by weight of benzammonium peroxide (BPO) as a polymerization initiator was added to prepare a monomer mixture solution. 0.5 wt% of polyvinyl alcohol (PVA) as a suspension stabilizer was dissolved in 400 parts by weight of deionized water as a dispersion medium to prepare a suspension, and then the monomer mixture solution was added to the suspension, followed by high speed. The homogenizer was homogenized at 8,000 rpm for 5 minutes to prepare an emulsion. Then, the emulsion was subjected to a reaction in a 4-necked flask at 65 ° C for 6 hours under a nitrogen atmosphere, followed by heating to 75 ° C and polymerization for 4 hours. The synthesized polymer was filtered and washed with water and an aqueous ethanol solution, and then dried in a vacuum oven for 1 day to give a white odorless spherical polymer powder. The obtained acrylic fine particles were identified by SEM to evaluate their dispersibility in a solvent, and an SEM image of the acrylic fine particles is shown in FIG.

Example 2

Acrylic fine particles were prepared in the same manner as in Example 1 except that 30 parts by weight of pentaerythritol triacrylate as the first crosslinking agent was used, and the second crosslinking agent was not used. The obtained acrylic fine particles were identified by SEM to evaluate their dispersibility in a solvent, and an SEM image of the acrylic fine particles is shown in FIG.

Comparative example 1

Acrylic fine particles were prepared in the same manner as in Example 1 except that 30 parts by weight of ethylene glycol di(meth)acrylate (EGDMA) was added as a crosslinking agent. The obtained acrylic fine particles were identified by SEM to evaluate their dispersibility in a solvent, and an SEM image of the acrylic fine particles is shown in FIG.

Comparative example 2

Acrylic fine particles were prepared in the same manner as in Example 1 except that 1,6-hexanediol di(meth)acrylate (HDDA) was used instead of pentaerythritol triacrylate as the first crosslinking agent. The obtained acrylic fine particles were identified by SEM to evaluate their dispersibility in a solvent, and an SEM image of the acrylic fine particles is shown in FIG.

Comparative example 3

Acrylic fine particles were prepared in the same manner as in Example 1 except that 30 parts by weight of 1,6-hexanediol di(meth)acrylate (HDDA) was added as a crosslinking agent. The obtained acrylic fine particles were identified by SEM to evaluate their dispersibility in a solvent, and an SEM image of the acrylic fine particles is shown in FIG.

Comparative example 4

Acrylic fine particles were prepared in the same manner as in Example 2 except that 5 parts by weight of pentaerythritol triacrylate and 95 parts by weight of methyl methacrylate (MMA) were used as the first crosslinking agent.

Physical property assessment

(1) Solvent resistance

15 g of MEK and 2 g of acrylic microparticles were placed in a 20 ml vial and allowed to stand for 4 hours, and then the difference in swelling was evaluated. The swelling ratio is calculated as follows:

Hb: particle height after 4 hours in solvent

Ha: initial particle height

(2) Dispersibility in solvent

10 g of ethanol was mixed with 1 g of acrylic fine particles, stirred for 10 minutes, and dropped onto a glass slide, and the dispersibility was evaluated by SEM analysis. The results are shown in Figures 1 to 5. The samples in Example 1 and Comparative Example 1 were measured at 50 times magnification using an optical microscope (BX51, Olympus), and the results are shown in Fig. 6.

(3) coefficient of variation

Place 18 g water, 0.5 g acrylic microparticles and 3 g dispersant solution (ethanol: toluene = 5:5) in a vial, treat in an ultrasonic device for 10 minutes, then use LS 13 320 (Beckman Coulter) to 1.49 The refractive index was measured at 25 °C. Then, the coefficient of variation is calculated according to formula 1;

Where M is the mean volume size of the particles and σ is the standard deviation.

(4) Appearance of the film

25 parts by weight of the obtained fine particles, 30 parts by weight of MEK, 15 parts by weight of toluene, and 30 parts by weight of an acrylic adhesive (AA-910T, Aekyung Chemical Co., Ltd.) were mixed and left for 1 day to prepare a coating solution. . The coating solution was deposited on a PET film using a #10 bar, and dried at 120 ° C for 1 minute to prepare a film sample. The film sample was cut into 5 x 5 pieces and then observed using an optical microscope to evaluate the appearance of the film.

As shown in Table 1 and Figures 1-5, the acrylic fine particles according to Example 1 and Example 2 had excellent film appearance, solvent resistance, and dispersibility. However, the acrylic fine particles according to Comparative Example 1 produced a coalesced film appearance, and the solvent resistance was lowered. According to the acrylic fine particles of Comparative Example 2 and Comparative Example 3, the film appearance was excellent, but the solvent resistance was lowered. According to the acrylic fine particles of Comparative Example 4, in which an excessive amount of monomers were used, the average particle diameter and the coefficient of variation were undetectable, resulting in a coalescence of the appearance of the film, and exhibited a significantly reduced solvent resistance.

Although a few embodiments have been disclosed herein, it will be understood by those skilled in the art Therefore, the scope of the invention should be limited only by the scope of the appended claims and their equivalents.

1 is a scanning electron microscope (SEM) image for evaluating the dispersibility of acrylic fine particles prepared in Example 1 in a solvent;

2 is an SEM image for evaluating the dispersibility of the acrylic fine particles prepared in Example 2 in a solvent;

3 is an SEM image for evaluating dispersibility of acrylic fine particles prepared in Comparative Example 1 in a solvent;

4 is an SEM image for evaluating dispersibility of acrylic fine particles prepared in Comparative Example 2 in a solvent;

5 is an SEM image for evaluating dispersibility of acrylic fine particles prepared in Comparative Example 3 in a solvent;

6 is an optical microscope image for evaluating the dispersibility of the acrylic fine particles prepared in Example 1 in a solvent, and the dispersibility of the acrylic fine particles prepared in Comparative Example 1 in a solvent.

Claims (14)

An acrylic fine particle formed by polymerization of a monomer including a (meth) acrylate, the crosslinking agent including a first crosslinking agent, and the first crosslinking agent There are at least three (meth) acryloxy groups, and at least one functional group of -OH and -COOH, and the acrylic fine particles have a coefficient of variation (CV) of 20% to 60%. The acrylic fine particles according to claim 1, wherein the acrylic fine particles have a coefficient of variation of 40% to 60%. The acrylic fine particle according to claim 1, wherein the first crosslinking agent is represented by Formula 1: (Y) _i -R-(Q) _j , wherein Y is (meth) propylene An oxo group, R is a C1-C10 branched hydrocarbon, Q is -OH or -COOH, i is an integer from 3-5, and j is an integer from 1 to 5. The acrylic microparticles of claim 1, wherein the acrylic microparticles comprise from 60 wt% to 90 wt% of the monomer; and from 10 wt% to 40 wt% of the crosslinker. The acrylic microparticles of claim 1, wherein the acrylic microparticles comprise 60 wt% to 85 wt% of the monomer and 15 wt% to 40 wt% of the crosslinker. The acrylic fine particles according to claim 1, wherein the monomer comprises a C1-C10 alkyl (meth)acrylate and a monomer copolymerizable therewith. The acrylic microparticles of claim 6, wherein the monomer comprises 50 wt% to 100 wt% of the C1-C10 alkyl (meth)acrylate, and 50 wt% or less. The copolymerizable monomer. The acrylic fine particle according to claim 6, wherein the copolymerizable monomer comprises an aromatic vinyl monomer, a vinyl cyanide monomer, a C6-C20 aromatic (meth)acrylate, and a hydroxyl group. At least one of (meth) acrylate, epoxy group-containing (meth) acrylate, and unsaturated carboxylic acid. The acrylic microparticles of claim 1, wherein the crosslinking agent further comprises a second crosslinking agent selected from the group consisting of 1,4-butane di(meth)acrylate Alcohol ester, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, di(meth)acrylic acid A group consisting of propylene glycol ester, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and bis(trimethylolpropane)tetra(meth)acrylate. The acrylic fine particle according to claim 9, wherein the crosslinking agent comprises 60 wt% to 100 wt% of the first crosslinking agent, and 40 wt% or less of the second Crosslinker. The acrylic microparticles of claim 10, wherein the weight ratio of the first crosslinking agent to the second crosslinking agent is from 1.5:1 to 10:1. The acrylic fine particles according to claim 1, wherein the acrylic fine particles have a swelling ratio of less than 10% after being placed in methyl ethyl ketone at 25 ° C for 4 hours. A diffusion film containing the acrylic fine particles according to any one of claims 1 to 12. A method of preparing acrylic microparticles, comprising: preparing a monomer mixture solution by mixing a monomer including a (meth) acrylate, a crosslinking agent, and an initiator, the crosslinking agent including a first crosslinking agent, The first crosslinking agent has at least three (meth) acryloxy groups, and at least one functional group of -OH and -COOH, or a combination thereof; and suspension polymerization of the monomer mixture solution.