JP6708692B2 - Spherical gap agent - Google Patents

Description

The present invention relates to a spherical gap agent having a relatively large particle size.

Conventionally, in-plane spacers for liquid crystal display elements, seal spacers for liquid crystal display elements, EL display element spacers, touch panel spacers, gap holding materials and the like capable of uniformly holding gaps between various substrates such as ceramics and plastics Spacers for maintaining the gap distance and particles used in the technical field such as conductive fine particles have a substantially uniform particle shape, high particle size accuracy, and a shape close to a true sphere so as not to damage the substrate surface etc. Gap agents are widely used.

Particles made of an inorganic material, an organic material, an organic-inorganic composite material, or the like are known as particles for such a gap agent, and there are many small particles having a particle diameter of 10 μm or less. Particles having a relatively large particle size are also disclosed (see, for example, Patent Documents 1 to 4).

JP2012-248531A JP, 2004-123454, A JP, 2010-90213, A JP, 10-95812, A

In the application of these gap agents, the gap agent is often dispersed in a binder and placed between two substrates (or between panels) facing each other to give an appropriate gap for each application, but the gap is uniform. It is also important that the gap agent does not physically damage the contact surface with these substrates. Therefore, the gap agent used in the technical field is required to have flexibility under a compressive load, and further, to have a recovering force that returns to its original shape when the compression is released. Uses a gapping agent having a small particle size, and only an insufficient gapping agent has been known for an application requiring a large gap.

In particular, a gap agent having a relatively large particle size has a larger surface area than a conventional gap agent having a small particle size, so that the stress from the binder is large, the gap agent is easily deformed, and the contact area is wide. Therefore, there is a problem that the substrate is easily damaged.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a gap agent having a relatively large particle size, which has flexibility and recovery power.

The spherical gap agent of the present invention is characterized by having an average particle diameter of 15 to 150 μm and a 10% compression deformation recovery rate of 50 to 80%.

The coefficient of variation (CV value) of the particle diameter is preferably 10% or less.

The content of coarse particles having a particle diameter of 2 times or more in the spherical gap agent is preferably 1000 ppm or less on a number basis.

The spherical gap agent is preferably obtained by a seed polymerization method.

Since the spherical gap agent of the present invention has a relatively large particle size and has flexibility and recovery power, it is difficult to damage the substrates even when forming a relatively large gap between the substrates, and it is necessary to force the binder dispersion. Dimples are unlikely to occur even in a typical stirring environment.

The spherical gap agent of the present invention has an average particle diameter of 15 to 150 μm. The average particle diameter is a number-based average dispersed particle diameter, 15 μm or more, preferably 20 μm or more, more preferably 25 μm or more, 150 μm or less, preferably 120 μm or less, more preferably 100 μm or less, further preferably 80 μm or less. Is. When the average particle diameter of the gap agent is within the above range, it can be suitably used as a gap agent having a relatively large particle diameter.

The spherical gap agent of the present invention has a 10% compression deformation recovery rate of 50 to 80%. It is preferably 50% or more, more preferably 52% or more, preferably 80% or less, more preferably 75% or less. When the 10% compressive deformation recovery rate of the gap agent is within the above range, the substrate is less likely to be damaged and the particles are unlikely to be dented even under a forced stirring environment such as when the binder is dispersed.

Incidentally, the compression deformation recovery rate is an index of the elasticity of the polymer particles, a certain load is applied to the polymer particles, when removing this, particles of the polymer particles before and after the load loading It is obtained by the amount of displacement of the diameter. Specifically, a specific measuring method of the 10% compression deformation recovery rate will be described in Examples described later.

The gap agent of the present invention is spherical. In the present invention, the term “spherical” means a sphericity of 0.70 to 1.00, and a sphericity of 0.80 to 1.00 is more preferable. Further, the gap agent of the present invention is preferably spherical in terms of maintaining the gap, and the sphericity is preferably 0.90 to 1.00, more preferably 0.95 to 1.00. When the sphericity of the gap agent is within the above range, high gap accuracy can be maintained.

The coefficient of variation (CV value) of the particle diameter is preferably 10% or less, more preferably 8% or less. In this way, the gap agent having a small variation coefficient of particle diameter can maintain high gap accuracy.

The content of coarse particles having a particle diameter of 2 times or more in the spherical gap agent is preferably 1000 ppm or less on a number basis, more preferably 500 ppm or less, and further preferably 200 ppm or less. When the content of coarse particles of the gap agent is within the above range, high gap accuracy can be maintained.

The constituent components of the gap agent will be described below. First, the gap agent may be particles composed only of an organic material such as a vinyl polymer, or an organic material such as a material containing a vinyl polymer and a polysiloxane skeleton (composite material, etc.). It may be particles composed of an inorganic composite material. For example, a gap agent composed of a material containing a vinyl polymer has an organic skeleton formed by polymerizing a vinyl group and has high flexibility, which is excellent in that it does not damage the substrate surface as a gap agent. ing. On the other hand, a gap agent made of a material containing a polysiloxane skeleton has excellent gap retention. Therefore, the gap agent composed of the material in which the polysiloxane skeleton and the vinyl polymer are combined has both the protection of the substrate surface and the gap retention property.

As a monomer component constituting the gap agent, a vinyl-based monomer may be used to form an organic skeleton, and a silane-based monomer may be used to form a polysiloxane skeleton. Here, the vinyl-based monomer is divided into a vinyl-based crosslinkable monomer and a vinyl-based non-crosslinkable monomer, and the silane-based monomer is a silane-based crosslinkable monomer and a silane-based non-crosslinkable monomer. It is divided into a quantity and a quantity.

The vinyl-based crosslinkable monomer is one having a vinyl group and capable of forming a crosslinked structure, and specifically, a monomer (monomer) having two or more vinyl groups in one molecule. (1)) or a monomer having one vinyl group and a functional group other than vinyl group in one molecule (protonic hydrogen-containing group such as carboxyl group and hydroxy group, terminal functional group such as alkoxy group) (Monomer (2)) may be mentioned. However, in the case of the monomer (2), in order to form a crosslinked structure as a vinyl-based crosslinkable monomer, a reaction (bonding) of a carboxyl group, a hydroxy group, an alkoxy group, etc., which the monomer (2) has, It is necessary that the counterpart group be present in another monomer.

In the present invention, the term "vinyl group" means not only a carbon-carbon double bond, but also a polymerizable carbon group such as (meth)acryloyl group, allyl group, isopropenyl group, vinylphenyl group, isopropenylphenyl group. It also includes a substituent having a carbon double bond. Further, in the present specification, “(meth)acryloyl group”, “(meth)acrylate” and “(meth)acryl” mean “acryloyl group and/or methacryloyl group”, “acrylate and/or methacrylate” and “acryl and /Or methacryl".

Examples of the monomer (1) among the vinyl-based crosslinkable monomers include, for example, allyl (meth)acrylates such as allyl (meth)acrylate; ethylene glycol di(meth)acrylate, 1,4-butane. Diol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,3-butylene di(meth) ) Alkanediol di(meth)acrylates such as acrylates; diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, decaethylene glycol di (Meth)acrylate, pentadecaethylene glycol di(meth)acrylate, pentacontaethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth) Di(meth)acrylates such as polyalkylene glycol di(meth)acrylates such as acrylates; Tri(meth)acrylates such as trimethylolpropane tri(meth)acrylate; Tetra (meth) such as pentaerythritol tetra(meth)acrylate Acrylates; hexa(meth)acrylates such as dipentaerythritol hexa(meth)acrylate; aromatic hydrocarbon crosslinking agents such as divinylbenzene, divinylnaphthalene, and their derivatives (preferably styrene-based polyfunctional such as divinylbenzene) Monomers); N,N-divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfonic acid, and other heteroatom-containing crosslinking agents; and the like. Among these, (meth)acrylates having two or more (meth)acryloyl groups in one molecule (polyfunctional (meth)acrylate) and styrene-based polyfunctional monomers are preferable, and polyfunctional (meth)acrylate is more preferable. .. Among the polyfunctional (meth)acrylates, (meth)acrylates having two or more (meth)acryloyl groups in one molecule are preferable, and among them, two (meth)acryloyl groups are contained in one molecule. The di(meth)acrylate which it has is preferable, and also the alkanediol di(meth)acrylate is preferable.

Among the styrenic polyfunctional monomers, a monomer having two vinyl groups in one molecule such as divinylbenzene is preferable. The monomer (1) may be used alone or in combination of two or more kinds.

Examples of the monomer (2) among the vinyl-based crosslinkable monomers include, for example, a monomer having a carboxyl group such as (meth)acrylic acid; 2-hydroxyethyl (meth)acrylate, 2- Monomers having hydroxy groups such as hydroxy group-containing (meth)acrylates such as hydroxypropyl (meth)acrylate and 2-hydroxybutyl (meth)acrylate, and hydroxy group-containing styrenes such as p-hydroxystyrene; 2-methoxy Alkoxy group-containing (meth)acrylates such as ethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, and alkoxy groups such as alkoxystyrenes such as p-methoxystyrene. And the like. The monomer (2) may be used alone or in combination of two or more kinds.

The vinyl-based non-crosslinkable monomer may be a monomer having one vinyl group in one molecule (monomer (3)) or a vinyl group other than the vinyl group contained in the monomer (2). Examples of the monomer (2) include the case where another monomer having a group that reacts with a functional group does not exist in the monomer component.

Examples of the monomer (3) among the vinyl-based non-crosslinkable monomers include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate. , Isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, stearyl Alkyl (meth)acrylates such as (meth)acrylate and 2-ethylhexyl (meth)acrylate; cyclopropyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclooctyl (meth)acrylate, cycloundecyl Cycloalkyl (meth)acrylates such as (meth)acrylate, cyclododecyl (meth)acrylate, isobornyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate; phenyl (meth)acrylate, benzyl (meth)acrylate, Aromatic ring-containing (meth)acrylates such as tolyl (meth)acrylate and phenethyl (meth)acrylate; styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, pt-butylstyrene. And the like, and styrene-based monofunctional monomers such as halogen-group-containing styrenes such as o-chlorostyrene, m-chlorostyrene and p-chlorostyrene; Among these, it is preferable to use a methacrylate monofunctional monomer, and methyl methacrylate is more preferable. Of the styrenic monofunctional monomers, it is preferable to use styrene. The monomer (3) may be used alone or in combination of two or more kinds.

The vinyl polymer preferably has an embodiment containing the vinyl-based crosslinkable monomer (1) as a constituent, and among them, the vinyl-based non-crosslinkable monomer (3) and the vinyl-based crosslinkable monomer. An embodiment including (1) is preferable. Specifically, an embodiment containing a monomer having two or more (meth)acryloyl groups in one molecule as a constituent is preferable, and a monomer having one (meth)acryloyl group in one molecule is more preferable. An embodiment containing a monomer and a monomer having two or more (meth)acryloyl groups in one molecule is preferable.

The polysiloxane skeleton is formed by hydrolyzing a silane-based monomer to generate a siloxane bond by a condensation reaction, and particularly when a silane-based crosslinkable monomer is used as the silane-based monomer, a crosslinked structure is formed. You can The crosslinked structure formed by the silane-based crosslinkable monomer is one that crosslinks an organic polymer skeleton (for example, a vinyl polymer skeleton) and the organic polymer skeleton (first form); a polysiloxane skeleton Examples thereof include those that crosslink with a polysiloxane skeleton (second form); those that crosslink with an organic polymer skeleton and polysiloxane skeleton (third form).

Examples of the silane-based crosslinkable monomer capable of forming the first form include dimethyldivinylsilane, methyltrivinylsilane, and tetravinylsilane. Examples of the silane-based crosslinkable monomer capable of forming the second form include tetrafunctional silane-based monomers such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane; methyltrimethoxy. Examples thereof include trifunctional silane-based monomers such as silane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane. Examples of the silane-based crosslinkable monomer capable of forming the third form include, for example, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryl Roxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltriethoxysilane, 3-methacryloxyethoxypropyltrimethoxysilane or the like having a (meth)acryloyl group; vinyltrimethoxysilane, Those having a vinyl group such as vinyltriethoxysilane and p-styryltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl Those having an epoxy group such as trimethoxysilane; those having an amino group such as 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; These silane-based crosslinkable monomers may be used alone or in combination of two or more.

Examples of the silane-based non-crosslinkable monomer include bifunctional silane-based monomers such as dialkylsilane such as dimethyldimethoxysilane and dimethyldiethoxysilane; trialkylsilane such as trimethylmethoxysilane and trimethylethoxysilane. Examples thereof include monofunctional silane-based monomers. These silane-based non-crosslinkable monomers may be used alone or in combination of two or more.

Particularly, the polysiloxane skeleton is preferably a skeleton derived from a polymerizable polysiloxane having a radically polymerizable carbon-carbon double bond (for example, a vinyl group such as a (meth)acryloyl group). That is, the polysiloxane skeleton has, as a constituent component, at least a silane-based crosslinkable monomer capable of forming a crosslinked structure of the third form (preferably having a (meth)acryloyl group, more preferably 3-methacryloxy). It is preferably a polysiloxane skeleton formed by hydrolyzing and condensing propyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, vinyltrimethoxysilane).

Further, the gap agent is, in addition to the above-described organic materials and organic-inorganic composite materials, for example, polyolefin vinyl polymers such as polyethylene, polypropylene, polyvinyl chloride, polytetrafluoroethylene, polyisobutylene, and polybutadiene; polyethylene terephthalate, Polyester such as polyethylene naphthalate; polycarbonate; polyamide; polyimide; phenol formaldehyde resin; melamine formaldehyde resin; melamine benzoguanamine formaldehyde resin; urea formaldehyde resin; silicone resin and the like.

In order to control the recovery rate of the gap agent to fall within the above range, for example, the monomer component constituting the gap agent is contained in 100% by mass of the total amount of the monomer components, and the crosslinkable monomer ( The vinyl-based crosslinkable monomer and the silane-based crosslinkable monomer are preferably contained in an amount of 15% by mass or more and 90% by mass or less. The proportion of the crosslinkable monomer with respect to the total amount of the monomer components of 100% by mass is more preferably 20% by mass or more, further preferably 25% by mass or more, and more preferably 85% by mass or less. It is preferably 80% by mass or less. When the content of the crosslinkable monomer in the total amount of the monomer components is within the above range, the gap agent is less likely to damage the substrate, and the particles are unlikely to have dents even under a forced stirring environment such as when the binder is dispersed.

Further, it is preferable that the monomer component constituting the gap agent contains 1% by mass or more and 70% by mass or less of the silane-based crosslinkable monomer in 100% by mass of the total amount of the monomer components. The proportion of the silane-based crosslinkable monomer relative to 100% by mass of the total amount of the monomer components is more preferably 3% by mass or more, more preferably 40% by mass or less, and further preferably 20% by mass or less. ..

Further, when the gap agent has a polysiloxane skeleton derived from inorganic particles (organic-inorganic composite material), in order to reliably control the compression deformation recovery rate of the gap agent within the above-mentioned range, the silicon in the gap agent is required. The content is preferably 20% by mass or less in terms of Si equivalent to 100% by mass of the gap agent. The content is more preferably 15% by mass or less, further preferably 10% by mass or less, particularly preferably 5% by mass or less, and the lower limit is preferably 0.1% by mass or more. When the silicon content is within this range, the substrate is less likely to be damaged and the particles are less likely to have dents even under a forced stirring environment such as when the binder is dispersed. The silicon content is calculated by calculating the mass corresponding to the Si content from the ash mass (this is the amount of SiO ₂ ) when the gap agent is fired at 1000° C. in an oxidizing atmosphere such as air. It can be determined by dividing the amount by the mass of the gap agent subjected to the firing treatment. The mass corresponding to the Si content can be calculated from the ash mass by multiplying the ash mass by 0.4672 (Si atomic weight/SiO ₂ formula weight).

The method for producing the gap agent of the present invention is not particularly limited, and is not particularly limited as long as it polymerizes the above-mentioned monomer components, but emulsion polymerization, suspension polymerization, dispersion polymerization, seed polymerization method, etc. Can be mentioned. In order to make the particle size of the gap agent within the above-mentioned predetermined range, for example, a method of synthesizing the gap agent by a seed polymerization method and then classifying it is preferably adopted. By adopting the seed polymerization method for the synthesis of resin particles, a gap agent having a small particle size distribution can be obtained. Furthermore, the average particle size can be adjusted to a desired range by classifying the gap agent after synthesis and removing coarse particles.

Among the above seed polymerization methods, the sol-gel seed polymerization method is preferable because the particle size distribution can be made particularly small. The sol-gel seed polymerization method is an aspect of the seed polymerization method, and means that the seed particles are synthesized by the sol-gel method. For example, the case where the polysiloxane particles obtained by the hydrolysis-condensation reaction of the silane-based monomer is used as the seed particles may be mentioned. Therefore, the seed polymerization method includes a case where the seed particles are made of an organic polymer and a case where the seed particles are made of a material in which an organic substance and an inorganic substance are combined (in the case of the sol-gel seed polymerization method).

The seed polymerization method is a method of obtaining a gap agent through a seed particle preparation step, an absorption step of allowing a seed particle to absorb a monomer component, and a polymerization step of performing a polymerization reaction of a monomer component absorbed by the seed particle. The method, conditions and the like in each step are not particularly limited as long as a known seed polymerization method is appropriately adopted, but the following methods are preferably adopted, for example. In the seed particle preparation step, when synthesizing a gap agent composed only of an organic material, using the vinyl monomer, the seed particles may be prepared by a method such as soap-free emulsion polymerization or dispersion polymerization. Good. In this case, it is preferable to use a styrene monofunctional monomer such as styrene as the vinyl monomer. On the other hand, when synthesizing particles composed of an organic material and a material having a polysiloxane skeleton, a solvent containing water (for example, alcohols, ketones, esters, ( The seed particles (polysiloxane particles) may be prepared by a method of hydrolysis and polycondensation in a mixed solvent of water with an organic solvent such as cyclo)paraffins and aromatic hydrocarbons. In this case, it is preferable to use a silane-based crosslinkable monomer having a radically polymerizable group as the silane-based monomer to prepare polymerizable polysiloxane particles. In the hydrolysis and polycondensation, a basic catalyst such as ammonia, urea, ethanolamine, tetramethylammonium hydroxide, alkali metal hydroxide or alkaline earth metal hydroxide can be preferably used as a catalyst. Further, if necessary, an anionic, cationic or nonionic surfactant or a polymer dispersant such as polyvinyl alcohol or polyvinylpyrrolidone can be used. By using a surfactant or a polymer dispersant in the seed particle preparation step, it is possible to stably produce monodisperse seed particles even with a relatively large particle diameter. Particularly when a polymer dispersant is used, a further stabilizing effect can be expected.

In the seed particle preparation step, the polymer dispersant is preferably added so as to have a concentration of 0 to 20 mass% with respect to the polysiloxane particles. It is more preferably 0.5 to 10% by mass, and further preferably 1 to 5% by mass. When the concentration of the polymer dispersant is within the above range, the coefficient of variation of the obtained gap agent can be reduced.

The method of absorbing the monomer component into the seed particles in the absorbing step is not particularly limited, and for example, the monomer component may be added to the seed particle dispersion liquid in which the seed particles are previously dispersed in the solvent. The seed particles may be added to the solvent containing the monomer component, but particularly in the former method, the reaction liquid obtained by polymerization or hydrolysis or condensation may be used as it is as the seed particle dispersion liquid. Is preferable from the viewpoints of simplification and productivity. The monomer component may be added alone, or may be added as a solution dissolved in a solvent, but in order to be efficiently absorbed by the seed particles, an emulsifier is used in advance to prepare water or an aqueous medium ( For example, it is preferable to emulsify and disperse in a water-soluble organic solvent such as alcohols, ketones and esters, or a mixed solvent of these and water, and add it as an emulsion.

When emulsifying and dispersing the monomer component with an emulsifier, examples of the emulsifier include an anionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, and sorbitan fatty acid ester. , Non-ionic surfactants such as polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxyethylene-oxypropylene block polymer, the dispersion state of the seed particles after the seed particles have absorbed the monomer component Is preferably used because it can also stabilize. The amount of water or aqueous medium used in the emulsification/dispersion is usually 0.3 to 10 times the mass of the monomer component.

In the absorption step, to determine whether or not the monomer component has been absorbed by the seed particles, for example, before adding the monomer component and after the end of the absorption step, observe the particles with a microscope, and It can be easily judged by confirming that the particle size is large. In order to obtain the gap agent of the present invention, the absorption capacity represented by the following formula is not particularly limited, but it is preferably 1.0 times or more and 50 times or less.
Absorption capacity=(total mass of monomer components to be absorbed)/(mass of seed particles)

The polymerization method adopted in the polymerization step is not particularly limited, and a known method such as a method using a radical polymerization initiator (for example, a peroxide type initiator, an azo type initiator, etc.) can be used. The reaction temperature for radical polymerization is preferably 40° C. or higher, more preferably 50° C. or higher, preferably 100° C. or lower, and more preferably 80° C. or lower. If the reaction temperature is too low, the degree of polymerization does not sufficiently increase and the mechanical properties of the composite particles tend to be insufficient, while if the reaction temperature is too high, aggregation between particles tends to occur during polymerization. There is. The reaction time for radical polymerization may be appropriately changed depending on the type of the polymerization initiator used, but is usually preferably 5 minutes or longer, more preferably 10 minutes or longer, and preferably 600 minutes or shorter. , And more preferably 300 minutes or less. If the reaction time is too short, the degree of polymerization may not be sufficiently increased, and if the reaction time is too long, aggregation tends to occur between particles. In such a polymerization step, when the seed particles are polymerizable polysiloxane particles, the absorbed monomer component and the radically polymerizable group of the polymerizable polysiloxane skeleton are polymerized in the polymerization step, The polysiloxane skeleton and the vinyl polymer form a composite.

When the suspension polymerization method is adopted as the method for producing the gap agent of the present invention, the solvent used is not particularly limited as long as it does not completely dissolve the monomer component, but an aqueous medium is preferably used. .. These solvents can be appropriately used within a range of usually 20 parts by mass or more and 10000 parts by mass or less with respect to 100 parts by mass of the monomer composition. As a method for producing the gap agent, a method in which a suspension polymerization composition containing the vinyl monomer and a polymerization initiator is suspended in an aqueous solvent in which a dispersion stabilizer is dissolved or dispersed to polymerize is preferable. Is.

The polymerization temperature of suspension polymerization is preferably 50° C. or higher, more preferably 55° C. or higher, even more preferably 60° C. or higher, preferably 95° C. or lower, more preferably 90° C. or lower, further preferably Is 85° C. or lower. The polymerization reaction time is preferably 1 hour or longer, more preferably 2 hours or longer, even more preferably 3 hours or longer, and preferably 10 hours or shorter, more preferably 8 hours or shorter, and further preferably. 5 hours or less. Further, in order to control the particle size of the gap agent to be produced, it is preferable that the polymerization reaction is carried out after controlling the droplet size of the suspension polymerization composition or while controlling the droplet size. The regulation of the droplet diameter of the composition for suspension polymerization is performed by, for example, using a suspension prepared by dispersing the composition for suspension polymerization in an aqueous medium by T.S. K. It can be carried out by stirring with a high speed stirrer such as a homomixer or a line mixer. The gap agent generated by the polymerization reaction may be dried and, if necessary, subjected to a step such as classification. The drying is preferably performed at 150°C or lower, more preferably 120°C or lower.

The gap agent synthesized as described above is preferably subjected to classification so as to have a predetermined particle size. The classification method is not particularly limited and includes, for example, sieving with an electro-sieve, filtration using a filter such as a membrane filter, a pleated filter, and a ceramic membrane filter; a known device for classification by interaction of mass difference and fluid resistance difference ( Gravity classifier whose principle is a difference in gravity such as particle falling velocity, and (semi) free vortex centrifugal classification, which is based on the balance between centrifugal force and air drag due to free vortex or semi-free vortex, rotating classifying blade (rotor) And the like, which are based on the principle of balancing the centrifugal force generated by the rotational flow created and the drag force by air). Among these, classification using an electro-sieve is preferable from the viewpoint of classification accuracy and productivity.

After synthesis, the gap agent, which has been classified according to need, is usually dried, and optionally subjected to calcination. The drying temperature is not particularly limited, but is usually in the range of 50°C to 250°C.

The gap agent of the present invention can be dispersed in a binder resin to form a resin composition and then disposed between two opposing substrates (or between panels) to provide a gap suitable for each application.

The binder resin is not particularly limited, and examples thereof include acrylic resins, styrene resins, ethylene-vinyl acetate resins, thermoplastic resins such as styrene-butadiene block copolymers; monomers and oligomers having a glycidyl group, Curability of epoxy resin, oxetane resin, (meth)acrylic group-containing monomer or oligomer, reactive acrylic resin, cyanate ester resin, silicone resin, urethane resin, polyester resin, cyanoacrylate resin, etc. Resin; etc. can be mentioned.

The resin composition is not particularly limited in addition to the gap agent and the binder resin, and is (organic) solvent, curing agent, photoinitiator, thermal initiator, filler, dispersant, surfactant, plasticizer, coupling. Agents, antifoaming agents, antisettling agents, etc. may be included.

The content of the binder resin in the resin composition is preferably 50 to 99.99% by weight, more preferably 60 to 99.99% by weight, and particularly preferably 70 to 99.99% by weight. In addition, the content of the binder resin in the solid content of the resin composition excluding volatile components such as a solvent is preferably 60 to 99.9% by weight, more preferably 80 to 99.9% by weight, and 90 to 99.9% by weight is particularly preferred.

The content of the gap agent in the resin composition is preferably 0.01 to 30% by weight, more preferably 0.01 to 20% by weight, and particularly preferably 0.01 to 10% by weight. Further, the content of the gap agent in the solid content of the resin composition excluding volatile components such as a solvent is preferably 0.1 to 40% by weight, more preferably 0.1 to 20% by weight, and 0.1. 1 to 10% by weight is particularly preferred.

The gap agent of the present invention is a gap agent for cell gaps (or panel gaps) of liquid crystal display devices, plasma displays, display displays such as organic EL, touch panels, etc., and conductive materials such as anisotropic conductive materials for mounting micro devices. It can be applied to known applications such as various spacers, adhesives for temporary fixing, semiconductor encapsulation materials, organic device encapsulation materials, and optical parts, in which various gap agents can be used.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples, and is appropriately modified and implemented within a range compatible with the gist of the above and the following. It is also possible that they are all included in the technical scope of the present invention. In the following, "part" means "part by mass" unless otherwise specified.

1. Physical property measurement methods Various physical properties were measured by the following methods.

<sphericity>
The ratio (DS/DL) of the major axis (DL) and the minor axis (DS) of any 50 particles was measured with a scanning electron microscope (SEM, manufactured by Hitachi: "S-4800"), The average value of them was calculated as the sphericity.

<Average particle size and coefficient of variation (CV value) of seed particles and spherical gap agent>
In the case of the spherical gap agent, 0.1 part of the spherical gap agent is mixed with polyoxyethylene alkyl ether sulfate ammonium salt (“Hitenol (registered trademark) N-08” manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) which is an emulsifier. A dispersion prepared by adding 20 parts of a 1% by mass aqueous solution and ultrasonically dispersing for 10 minutes was used as a measurement sample. In the case of seed particles, the dispersion obtained by hydrolysis and condensation reaction was treated with polyoxyethylene alkyl ether sulfate. A particle size distribution measuring device (“Coulter Multisizer III manufactured by Beckman Coulter, Inc.” was used as a measurement sample by diluting an ammonium salt (“Hitenol (registered trademark) N-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) with a 1 mass% aqueous solution. The particle diameter (μm) of 30,000 particles was measured by the “type”) to determine the number-based average dispersed particle diameter. In addition to the average dispersed particle diameter, the standard deviation of the particle diameter on a number basis was also obtained, and the coefficient of variation (CV value) of the particle diameter was calculated according to the following formula.
Coefficient of variation of particles (%)=100×(standard deviation of particle diameter/average dispersed particle diameter)

Furthermore, in the measurement range where the particle size corresponding to 0.8 times the average particle size is the minimum particle size and the particle size corresponding to 4.0 times the average particle size is the maximum particle size, the number-based coarse particles are calculated according to the following formula. The particle frequency was calculated.
Coarse particle frequency (ppm)=1,000,000×(number of particles more than twice the average particle size/total number of measured particles)

<10% compression deformation recovery rate of spherical gap agent>
Using a micro compression tester (“MCT-W500” manufactured by Shimadzu Corporation) at 25° C., a circular flat plate indenter (material: SKS material flat plate) with a diameter of 50 μm was used for one particle scattered on a sample table (material: SKS flat plate). (Diamond) is used to apply a load at a constant load speed (19.36 mN/sec) toward the center of the particle, and the load value when the compressive displacement is 10% of the particle diameter (10% compressive load value) ( mN) and the displacement amount (μm) at that time were measured. The measurement was performed on 10 different particles for each sample, and the averaged value was used as the measured value. Further, using a micro compression tester (“MCT-W500” manufactured by Shimadzu Corporation), at 25° C., a circular flat plate indenter having a diameter of 50 μm ( Material: Diamond) was used to compress the particles toward the center of the particle at a constant load speed (2.23 mN/sec) so that the 10% compressive load value obtained above was the maximum load, and the amount of displacement at that time ( μm) was measured, and this was taken as the maximum displacement amount L1. Next, the displacement amount (μm) from the maximum load to the minimum load when the load was reduced to the minimum load (0.49 mN) at a constant unloading speed (2.23 mN/sec) was measured. Is the recovery displacement amount L2. The measurement was performed on 10 different particles for each sample, and the averaged value was used as the measured value.
10% compression deformation recovery rate (%)=(L2/L1)×100

2. Preparation of Spherical Gap Agent (Example 1)
Into a four-necked flask equipped with a cooling tube, a thermometer, and a dropping port, 290 parts of ion-exchanged water and 0.8 part of 25 mass% ammonia water were put, and the monomer component (seed formation was performed from the dropping port under stirring. As a monomer), a mixed solution of 100 parts of 3-methacryloxypropyltrimethoxysilane and 103 parts of methanol is added, and hydrolysis and condensation reaction of 3-methacryloxypropyltrimethoxysilane are carried out to give a polymerizable polysiloxane having a methacryloyl group. A dispersion liquid of particles (seed particles) was prepared. The number-based average particle diameter of the polysiloxane particles was 20.8 μm, and the variation coefficient of the particle diameter was 8.9%. After confirming the particle size, 20 parts of a 10 mass% solution of polyvinyl alcohol (“Poval PVA-205” manufactured by Kuraray Co., Ltd.) was added. The concentration of polyvinyl alcohol in the obtained polysiloxane particle (seed particle) dispersion was 0.4% by mass.

Next, a mixed solution of 3909 parts of ion-exchanged water and 406 parts of methanol was added as a diluting solution to the polysiloxane particle (seed particle) dispersion, and the mixture was stirred. Further, 25 parts of a 20 mass% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt (“Hitenol (registered trademark) NF-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as an emulsifier was dissolved in 1000 parts of ion-exchanged water. 250 parts of styrene as a monomer component (absorbing monomer), 750 parts of ethylene glycol dimethacrylate, 2,2′-azobis(2,4-dimethylvaleronitrile) (Wako Pure Chemical Industries, Ltd. “V- 65") and 22 parts thereof were added and emulsified and dispersed to prepare an emulsion of the monomer component (absorption monomer). The obtained emulsion was added to the dispersion liquid of polysiloxane particles (seed particles) and further stirred. One hour after the addition of the emulsified liquid, the mixed liquid was sampled and observed with a microscope. As a result, it was confirmed that the polysiloxane particles absorbed the absorbing monomer and were enlarged.

Finally, 28 parts of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl 10 mass% solution (“Polystop 7010” manufactured by Hakutosha Co., Ltd.) and 550 parts of a 10 mass% aqueous solution of polyvinyl alcohol were added. The temperature of the reaction solution was raised to 65° C. in a nitrogen atmosphere and kept at 65° C. for 2 hours to carry out radical polymerization of the monomer component. The emulsion after radical polymerization was passed through a metal sieve having an opening of 160 μm, solid-liquid separation was performed, the obtained cake was washed with methanol, and then vacuum dried at 120° C. for 2 hours in a nitrogen atmosphere, A spherical gap agent (1) was obtained. The physical properties of the obtained spherical gap agent are shown in Table 1.

(Example 2)
Similar to Example 1 except that the amount of ion-exchanged water used was changed to 250 parts and the amount of methanol used was changed to 143 parts in preparing a dispersion liquid of polysiloxane particles (seed particles). Then, a dispersion liquid of polymerizable polysiloxane particles having a methacryloyl group (seed particles) was prepared. The number-based average particle diameter of the polysiloxane particles was 22.3 μm, and the coefficient of variation in particle diameter was 3.2%. Furthermore, in Example 1, the type and amount of absorption monomer were changed to 600 parts of methyl methacrylate and 400 parts of ethylene glycol dimethacrylate, and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1 was used during radical polymerization. A spherical gap agent (2) was obtained in the same manner as in Example 1 except that the 10 mass% oxyl solution was not added. The physical properties of the obtained spherical gap agent are shown in Table 1.

(Example 3)
Similar to Example 2 except that the amount of ion-exchanged water used was changed to 300 parts and the amount of methanol used was changed to 93 parts in preparing a dispersion liquid of polysiloxane particles (seed particles). Then, a dispersion liquid of polymerizable polysiloxane particles having a methacryloyl group (seed particles) was prepared. The number-based average particle diameter of the polysiloxane particles was 20.6 μm, and the variation coefficient of the particle diameter was 8.7%. Further, a spherical gap agent (3) was obtained in the same manner as in Example 2 except that the type and amount of the absorbing monomer used in Example 2 were changed to 600 parts of styrene and 400 parts of ethylene glycol dimethacrylate. The physical properties of the obtained spherical gap agent are shown in Table 1.

(Example 4)
In Example 3, the spherical gap agent (4) was used in the same manner as in Example 3 except that the types and amounts of the absorbing monomers were changed to 300 parts of styrene, 300 parts of methyl methacrylate, and 400 parts of ethylene glycol dimethacrylate. Got The physical properties of the obtained spherical gap agent are shown in Table 1.

(Example 5)
A spherical gap agent (5) was obtained in the same manner as in Example 3, except that the type and amount of the absorbing monomer used were changed to 800 parts of methyl methacrylate and 200 parts of ethylene glycol dimethacrylate. The physical properties of the obtained spherical gap agent are shown in Table 1.

(Example 6)
A spherical gap agent (6) was obtained in the same manner as in Example 1, except that the emulsion after radical polymerization was not passed through a metal sieve having an opening of 160 μm. The physical properties of the obtained spherical gap agent are shown in Table 1.

(Example 7)
A spherical gap agent (7) was obtained in the same manner as in Example 1 except that the addition amount of the 10 mass% polyvinyl alcohol solution was changed to 5 parts. At that time, the number-based average particle diameter of the polysiloxane particles was 21.0 μm, the coefficient of variation of the particle diameter was 30.2%, and the concentration of polyvinyl alcohol in the dispersion was 0.1% by mass. The physical properties of the obtained resin particles are as shown in Table 1.

(Example 8)
In Example 2, except that the amount of ion-exchanged water used was changed to 350 parts and the amount of methanol used was changed to 43 parts when preparing a dispersion liquid of polysiloxane particles (seed particles). Then, a dispersion liquid of polymerizable polysiloxane particles having a methacryloyl group (seed particles) was prepared. The number-based average particle diameter of the polysiloxane particles was 14.6 μm, and the coefficient of variation of particle diameter was 3.3%. Further, in Example 1, a spherical gap agent (8) was obtained in the same manner as in Example 2, except that the type and amount of the absorbing monomer were changed to 300 parts of methyl methacrylate and 200 parts of ethylene glycol dimethacrylate. .. The physical properties of the obtained spherical gap agent are shown in Table 1.

(Example 9)
Similar to Example 2, except that the amount of ion-exchanged water used was changed to 220 parts and the amount of methanol used was changed to 173 parts in preparing a dispersion liquid of polysiloxane particles (seed particles). The spherical gap agent (9) was obtained. At this time, the number-based average particle diameter of the polysiloxane particles was 31.3 μm, and the variation coefficient of the particle diameter was 10.2%. The physical properties of the obtained spherical gap agent are shown in Table 1.

(Example 10)
In a four-necked flask equipped with a cooling tube, a thermometer, and a dropping port, 2 parts of polyoxyethylene styrenated phenyl ether sulfate ammonium salt (“Hitenol (registered trademark) NF-08” manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was added. 300 parts of dissolved ion-exchanged water and 10 parts of 3-methacryloxypropyltrimethoxysilane adjusted beforehand, 60 parts of methyl methacrylate, 40 parts of ethylene glycol dimethacrylate, 2,2′-azobis(2,4-dimethylvalero) Nitrile) (Wako Pure Chemical Industries, Ltd., "V-65") 1 part was mixed and emulsified to prepare an emulsion of a monomer component (absorption monomer), and further 500 parts of ion-exchanged water was added. Was added.
Then, the reaction solution was heated to 65° C. under a nitrogen atmosphere and kept at 65° C. for 3 hours to carry out radical polymerization of the monomer component. The emulsion after radical polymerization was passed through a metal sieve having an opening of 100 μm, solid-liquid separation was performed, the obtained cake was washed with methanol, and then vacuum dried at 120° C. for 2 hours in a nitrogen atmosphere, A spherical gap agent (10) was obtained. The physical properties of the obtained spherical gap agent are shown in Table 1.

(Comparative Example 1)
In Example 2, except that the amount of ion-exchanged water used was changed to 340 parts and the amount of methanol used was changed to 53 parts in preparing a dispersion liquid of polysiloxane particles (seed particles). Then, a dispersion liquid of polymerizable polysiloxane particles having a methacryloyl group (seed particles) was prepared. The number-based average particle diameter of the polysiloxane particles was 20.6 μm, and the variation coefficient of the particle diameter was 3.3%. Further, in Example 2, a spherical gap agent (11) was obtained in the same manner as in Example 2 except that the type and amount of the absorbing monomer used was changed to 1000 parts of ethylene glycol dimethacrylate. The physical properties of the obtained spherical gap agent are shown in Table 1.

(Comparative example 2)
In Example 2, except that the amount of ion-exchanged water used was changed to 320 parts and the amount of methanol used was changed to 73 parts in preparing a dispersion liquid of polysiloxane particles (seed particles), the same as in Example 2. Then, a dispersion liquid of polymerizable polysiloxane particles having a methacryloyl group (seed particles) was prepared. The number-based average particle diameter of the polysiloxane particles was 20.7 μm, and the variation coefficient of the particle diameter was 3.1%. Further, in Example 2, a spherical gap agent (12) was obtained in the same manner as in Example 2 except that the type and amount of the absorbing monomer were changed to 950 parts of methyl methacrylate and 50 parts of ethylene glycol dimethacrylate. .. The physical properties of the obtained spherical gap agent are shown in Table 1.

(Comparative example 3)
A spherical gap agent (13) was obtained in the same manner as in Comparative Example 2 except that the type and amount of the absorbing monomer used in Comparative Example 2 were changed to 1000 parts of methyl methacrylate. The physical properties of the obtained spherical gap agent are shown in Table 1.

3. Preparation and Evaluation of Gap Agent Particle-Containing Resin Composition Using the spherical gap agents obtained in Examples and Comparative Examples, gap agent particle-containing binders were prepared by the following methods, and their various physical properties were evaluated. The evaluation results are shown in Table 1.
(1) Evaluation of particle dents 1 part of spherical gap agent, 100 parts of epoxy resin (“JER828” manufactured by Mitsubishi Chemical) as a binder resin, and curing agent (“San-Aid (registered trademark) SI-150” manufactured by Sanshin Chemical Co., Ltd.) ) 2 parts and 100 parts of toluene were stirred and dispersed for 10 minutes using a triple roll to obtain a resin composition containing gap agent particles. Then, 1000 parts of toluene was added to the obtained resin composition containing gap agent particles, and suction filtration was performed to collect the gap agent particles. As for the dents of the particles, 50 particles were observed using a scanning electron microscope (SEM, manufactured by Hitachi, Ltd.: "S-4800"). When the particles did not have dents, "○" indicates that even one particle had dents. In some cases, it was evaluated as “x”.
(2) Evaluation of scratches on glass substrate The obtained gapping agent particle-containing resin composition was sandwiched between glass substrates, thermocompression-bonded under pressure bonding conditions of 0.1 MPa and 150° C., and tested by curing the binder resin. Got a piece. Then, the obtained test piece was observed with an optical microscope (manufactured by HiROX: "KH-8700") at a magnification of 500 for 50 fields of view, and in the case where the field of view on which the glass substrate was scratched was 0 field of view, "○", even 1 field of view was obtained. When it was scratched, it was evaluated as "x".
(3) Measurement of gap accuracy The cross section of each of the four corners of the test piece obtained in (2) was observed with a scanning electron microscope (SEM, manufactured by Hitachi: "S-4800") to determine the distance between the glass substrates. The measurement was performed. If the average value of the gaps at the four corners is 1.1 times or less with respect to the number average particle diameter, “◎”, more than 1.1 times, and with 1.5 times or less, “◯”, more than 1.5 times. The thing was evaluated as "x".

INDUSTRIAL APPLICABILITY The spherical gap agent of the present invention can be used as a gap agent for cell gaps (or panel gaps) such as a display and a touch panel, a conductive spacer such as an anisotropic conductive material for mounting micro devices, and the like.

Claims (4)

Has an average particle size of 20 to 150 μm,
10% compression recovery rate is 50-80%,
A spherical gap agent comprising a silane-based crosslinkable monomer having a (meth)acryloyl group and a vinyl-based crosslinkable monomer as a monomer component constituting the spherical gap agent. The spherical gap agent according to claim 1, wherein the coefficient of variation (CV value) of the particle diameter is 10% or less. The spherical gap agent according to claim 1 or 2 , wherein the content of coarse particles having a particle diameter of 2 times or more in the spherical gap agent is 1000 ppm or less on a number basis. The spherical gap agent according to any one of claims 1 to 3 , which is obtained by a seed polymerization method.