JP6795514B2 - Conductive compositions, processes and applications - Google Patents

Description

The present invention relates to conductive compositions based on conductive particles and their use in conductive meshes. The conductive composition according to the present invention can be used for a touch screen.

The touch screen sensor detects the position of an object (eg, a finger or stylus) in contact with the surface of the touch screen display, or the position of an object placed near the surface of the touch screen display. These sensors detect the position of an object along the surface of the display, eg, in the plane of a flat rectangular flat display. Examples of touch screen sensors include capacitance sensors, resistance sensors, and projected capacitance sensors. Examples of such a sensor include a conductive element that is superimposed on the display. These elements are combined with electronic components that use electrical signals to explore the element to locate objects near or in contact with the display.

In the field of touch screen sensors, there is a need for better control over the electrical properties of touch screen sensors without compromising the optical quality of the display. In general, optical quality can be represented by visible light transmission, haze, and sensor visibility. The quality is determined by observing the sensor with the human eye when assembled as a touch screen. Generally, in a metal mesh touch sensor, a transparent micropatterned conductive portion contains a metal mesh structure, which is used as a touch screen sensor. The micropatterned mesh structure depends on parameters such as, but not limited to, the width and height of the mesh traces (sometimes referred to as "lines") used in the micropattern, the density of the lines, and the uniformity of the density of the lines. Can be specified. Micropatterns typically have a line width of less than 5 μm (such thin lines are invisible to the human eye), a trace height of less than 5 μm, and an aperture ratio of 95% to 99.99%. The voids (transmission areas) between mesh lines are typically hundreds of microns to millimeters. In this way, extremely high transparency of the touch screen sensor can be realized. The micropatterned mesh structure can be, for example, diamond-shaped, hexagonal-shaped or random-shaped. The electrical conductivity of a touch screen sensor is related to the density of the line and the shape of the line.

In one metal mesh technique, first of all, a mesh pattern consisting of grooves having an appropriate width and height is formed on the surface of the substrate. The groove is then filled with a conductive composition. All residual composition produced during the filling process is removed from the substrate surface during the cleaning step, followed by the conductive composition in the mesh grooves being cured or sintered at high temperatures to form a solid conductive metal mesh structure. Will be done. The ease and amount of cleaning of the residual composition on the surface is a crucial factor in determining the yield loss of the product due to visible defects on the surface caused by the excess residue.

The metal mesh structure can be made from a highly conductive metal or metal alloy consisting of metal particles having a micron or submicron particle size. In many cases, silver particles are used to form conductive mesh lines to ensure high conductivity of the mesh structure. However, the surface of hardened silver lines usually has high reflectance and its presence can be perceived by the human eye. This visibility compromises the optical quality of the touch screen sensor and, as a result, the display containing the touch screen sensor, which is one of the significant drawbacks of this technique.

It is known to apply a dark overlay with a black ink coating over the conductive metal mesh lines to reduce reflections on the surface of the metal mesh structure. Doing so creates additional process steps that stretch the entire process, thereby increasing processing time and cost. This additional step may lead to further yield reduction.

Another solution known in the prior art is to add a black dyeing material (eg, carbon black or organic black dye) to the conductive composition to reduce surface reflections on the surface of the cured metal mesh. However, this can result in a non-uniform color appearance if the dye is not evenly distributed. In addition, the conductivity of the hardened metal mesh will be reduced due to the insulation of the organic black dye material and the lower conductivity of carbon black than silver.

Therefore, there remains a need to provide a conductive composition that has the ability to be cured or sintered at relatively low temperatures, and has sufficient adhesion to the substrate after curing or sintering, high electrical conductivity and low reflectance. ing. Further, it is desirable that the residual composition can be easily removed from the surface of the substrate other than the grooves before curing.

The present invention relates to a conductive composition, wherein the composition is a) first particles having an aspect ratio of 1 or more and less than 2.0, such as spherical particles, faceted particles, prismatic particles, and these. First particle selected from a mixture of; or a mixture of the first particle and a second particle, which is a second particle and is a non-spherical particle having an aspect ratio greater than 2.0. Conductive particles to be formed; b) resin; and c) contain at least one organic solvent.

The present invention further relates to a method for preparing a transparent conductive mesh containing the conductive composition according to the present invention, and the obtained conductive mesh structure.

Furthermore, the present invention includes the use of conductive mesh structures in touch sensor technology.

Finally, the present invention includes a touch panel display comprising a conductive mesh on a substrate, the mesh comprising a cured or sintered composition according to the present invention.

The following sections describe the invention in more detail. Each such aspect may be combined with any other aspect (single or plural) unless a different meaning is explicitly indicated. In particular, any feature indicated as preferred or advantageous may be combined with any other feature (single or plural) indicated as preferred or advantageous.

In the present invention, the terminology used should be construed to follow the following definitions, unless the context indicates otherwise.

As used herein, the singular forms "a," "an," and "the" include both single and plural references unless explicitly stated in the context.

As used herein, the terms "comprising," "comprise," and "comprised of" are "including," "include," or "included." Synonymous with "containing", "contain", it is inclusive or open-ended and does not exclude additional, unlisted members, elements or method steps.

Numerical end point descriptions include all numerical and fractional values within their respective ranges, as well as the stated end points.

Unless otherwise indicated, all percentages, parts, ratios, etc. referred to herein are weight-based.

If the quantity, concentration or other value or parameter is expressed in the form of a range, preferred range, or preferred upper and lower bounds, whether the resulting range is explicitly mentioned in the context. Regardless, it should be understood that any range obtained by combining any upper limit or preferred value with any lower limit or preferred value is specifically disclosed.

All references cited herein are incorporated herein by reference in their entirety.

Unless otherwise defined, all terms, including the technical and scientific terms used in the disclosure herein, have meanings commonly understood by those skilled in the art to which the present invention belongs. Further description includes definitions of terms for a better understanding of the teachings of the present invention.

The present invention provides a conductive composition, which is a) first particle having an aspect ratio of 1 or more and less than 2.0, such as spherical particles, faceted particles and mixtures thereof. A first particle selected from; or a mixture of the first particle and a second particle that is a second particle and is a non-spherical particle having an aspect ratio greater than 2.0. Conductive particles; b) resin; and c) contain at least one organic solvent.

The conductive composition according to the invention provides the ability to be cured or sintered at relatively low temperatures. The cured or sintered composition according to the present invention has sufficient adhesive strength to a substrate, high electrical conductivity and low reflectance. In addition, the residual composition can be easily removed from the surface of the substrate other than the grooves before curing.

Each essential component of the conductive composition according to the present invention will be described in detail below.

Conductive Particles The conductive composition according to the present invention is a first particle having an aspect ratio of 1 or more and less than 2.0, and is selected from spherical particles, faceted particles, prismatic particles, and a mixture thereof. First particle; or conductive particle selected from a mixture of the first particle and a second particle, which is a second particle and is a non-spherical particle having an aspect ratio greater than 2.0. including.

The particles according to the invention are characterized by particle shape and particle size. The particle size is measured by a particle size analyzer, and the particle shape is analyzed by a scanning electron microscope. In short, scattered laser light from particles is detected by a series of detectors. Theoretical calculations are performed to fit the measured scattered light intensity distribution. During the fitting process, the particle size distribution is estimated and values such as D10, D50, D90 are calculated accordingly. Particles according to the invention have a D50 of 10 nm to 500 nm and a D90 of less than 1 μm.

As used herein, the term "aspect ratio" means an image projection attribute that represents the proportional relationship between particle width and its height. The particle shape is observed by SEM, sized and averaged for its aspect ratio.

As used herein, the aspect ratio means the average aspect ratio of 50, preferably 100, particles of each filler, measured according to the measurement methods referred to below.

As used herein, aspect ratio relates to the ratio between dimensions of different dimensions of a three-dimensional object, more specifically the ratio of the longest side to the shortest side, eg, the ratio of length to width. Ball-shaped or spherical particles therefore have an aspect ratio of about 1, while fibers, needles or flakes tend to have an aspect ratio greater than 10. The reason is that they have the same small diameter or thickness corresponding to their length or length and width. The aspect ratio can be measured by scanning electron microscopy (SEM) measurements. As software, "Analysis pro" made by Olympus Soft Imaging Solutions GmbH can be used. Magnifications range from x250 to x1000, and aspect ratios are obtained by measuring the width and length of at least 50, preferably 100, particles on the image. In the case of relatively large, flaky fillers, SEM measurements can be obtained using a sample tilt angle of 45 °.

The first and second conductive particles according to the present invention are selected from the group consisting of metals, metal alloys, metal-containing composite materials, non-metal particles and mixtures thereof, preferably silver, gold, platinum, copper and nickel. , Aluminum, zinc, iron, copper-nickel, silver-copper, silver-nickel, copper-aluminum, silver-plated copper, silver-plated glass, silver-plated graphite, silver-plated fiber, graphite, carbon black, carbon nanotubes and mixtures thereof. Selected from the group consisting of, and more preferably, the conductive particles are silver particles.

Silver particles are preferred because of the ideal balance between their conductivity and price.

First Particle In one embodiment, the conductive composition according to the present invention comprises a first conductive particle having an aspect ratio of 1 or more and less than 2.0, and the aspect ratio is measured as described above. Will be done. The first particle has a spherical, faceted or pyramidal shape. The first particle may contain only one shape from a spherical, faceted or pyramidal shape. Alternatively, the first particle can be a mixture of any two shapes or a mixture of all three shapes.

The first particles according to the present invention preferably have an average particle size of 5 nm to 1 μm, more preferably 5 nm to 500 nm, and even more preferably 5 nm to 200 nm.

Groove widths in metal mesh applications are typically less than 5 μm for large size touch sensors and less than 2.5 μm for smaller sensors. The particle size needs to be adjusted to be smaller than the groove in the composition according to the invention in order to fit well into the groove and form the conductive line. Therefore, the preferred particle size range is ideal for metal mesh applications. In addition, silver particles with a smaller particle size have a darker lightness compared to silver particles with a larger particle size. In particular, particle sizes of 5 nm to 200 nm have a darker brightness than larger particles, which is beneficial in reducing the reflectance of conductive mesh patterns and is therefore less visible to the human eye.

The composition according to the invention comprises first particles from 5% to 85% by weight, preferably 60% to 75% by weight of the total weight of the composition.

If the composition contains less than 5% by weight of the first particles of the total weight of the composition, the composition may result in low conductivity. On the other hand, if the composition contains first particles in excess of 85% by weight of the total weight of the composition, the composition has insufficient adhesive strength and insufficient adhesive strength due to the absence of sufficient solvent or resin binder. It may result in too high viscosity. In the ideal range, 60-75% by weight of the total weight of the composition provides ideal conductivity as well as suitable fluid and mechanical properties for metal mesh applications.

Spherical and / or faceted and / or pyramidal particles in the adhesive composition according to the invention improve the optical properties, resulting in them reducing reflectance as a whole. In addition, spherical and / or faceted and / or pyramidal particles improve the removability of residual adhesive in locations other than grooves.

Second Particle In one embodiment, the conductive composition according to the present invention comprises a mixture of the first conductive particle and the second conductive particle, the second particle having an aspect ratio greater than 2.0. It is a non-spherical particle having a ratio.

If the conductive composition contains only the second (non-spherical) particles, good conductivity will be achieved, but the optical properties will not be ideal. The reason is that the reflectance of the composition seems to be extremely high.

Particles with an aspect ratio of 1 or more and 2 or less can be used in combination with non-spherical particles having an aspect ratio greater than 2 to improve the balance between conductivity and optical properties. The use of non-spherical and spherical and / or faceted and / or pyramidal particle mixtures can also improve the physical properties of the cured composition, especially the adhesion of the cured mesh structure to the substrate.

A second particle with an aspect ratio greater than 2.0 is defined as a non-spherical particle. The non-spherical particles according to the present invention can have, for example, flakes or rod-like shapes. The non-spherical particles according to the present invention preferably have an aspect ratio greater than 10.0.

Larger aspect ratios result in lower penetration thresholds and result in good conductivity. The lower penetration threshold due to the high aspect ratio (which means the filling amount of silver particles that forms continuous contact between silver particles and begins to form as much electrical continuous conduction path as possible) is conductive. It is the reason that underlies the rate. In this application, the tighter filling of the grooves also contributes to the improved conductivity. Finally, the lower contact resistance between the particles is another factor for achieving better conductivity.

The non-spherical particles according to the present invention preferably have an average particle size of 10 nm to 2 μm, more preferably 10 nm to 1 μm.

The groove width used in the metal mesh application according to the present invention is less than 5 μm for a large-sized touch sensor and less than 2.5 μm for a small touch sensor. The particle size needs to be optimized and adjusted in order to successfully fill the grooves with conductive particles and to obtain conductive lines. Therefore, the selective particle size range of the present invention is ideal for metal mesh applications.

The conductive composition according to the invention comprises a mixture of the first and second particles, the second particle being 10% to 85% by weight, preferably 30% by weight to 70% by weight of the total weight of the composition. It is present in% by weight and the first particles are present in 5-40% by weight of the total weight of the composition.

The selected combination of the first and second particles gives the ideal conductivity and has comparable brightness. It is preferable that the amount of the second particle is larger. The greater the amount of the first particles in the composition, the greater the decrease in conductivity of the composition will be. However, the brightness L ^* value has the opposite tendency. The higher the amount of the first particles in the composition, the darker the lightness. Therefore, in order to obtain good conductivity (VR <5E-05 ohm · cm) with brightness equivalent to L ^* <60%, the composition preferably contains a larger amount of second particles.

In a highly preferred embodiment, the weight ratio of the second particles to the first particles is 6: 1 to 1: 2, more preferably 3: 1 to 1: 1.

Resin The conductive composition according to the present invention contains a resin or a mixture of resins. The resin used in the present invention needs to have good solubility in the solvent used in the composition. In addition, the resin needs to have good solvent release properties during curing or sintering at high temperatures and to ensure complete drying at relatively low temperatures. The resin used in the present invention needs to have good compatibility with the selected particles. The resin also has good mechanical and fluid properties and needs to facilitate the groove filling process. As a bonding material interposed between the particles, the resin needs to have good conductivity. Finally, the resin needs to have good adhesion to the substrate, like polyethylene terephthalate (PET).

Preferably, the resin used in the composition according to the present invention is selected from the group consisting of halogenated thermoplastic resins, phenoxy resins, polyester resins, thermoplastic polyurethanes, polyvinyl acrylates, silicones and mixtures thereof, preferably resins. Is selected from the group consisting of polyvinyl chloride, polyvinyl chloride copolymers, phenoxy resin PKHH and mixtures thereof, and more preferably selected from the group consisting of polyvinyl chloride and polyvinyl chloride copolymers and mixtures thereof. To.

Thermoplastic resins suitable for use herein include vinyl copolymers, polyesters, polyurethanes and the like. In certain embodiments, suitable thermoplastic resins for use herein include halogenated thermoplastics.

In certain embodiments, the composition according to the invention comprises a polyvinyl chloride copolymer comprising a first monomer and a second monomer, wherein the first monomer is vinyl acetate, vinyl alcohol, vinyl chloride, vinylidene chloride. And selected from the group consisting of styrene, the second monomer is from a second vinyl acetate, a second vinyl alcohol, a second vinyl chloride, a second vinylidene chloride, a second styrene, an acrylic rate and a nitride. Selected from the group of

In certain embodiments, the first monomer is vinylidene chloride and the second monomer is vinyl chloride, acrylonitrile or alkyl acrylate.

In certain embodiments, the first monomer is vinylidene chloride and the second monomer is vinyl chloride (eg, polyvinylidene chloride). In certain embodiments, the first monomer is vinylidene chloride and the second monomer is an alkyl acrylate.

In certain embodiments, the compositions of the present invention are further thermosetting, selected from the group consisting of epoxy functionalized resins, acrylates, cyanate esters, silicones, oxetane, maleimides and mixtures thereof. Optionally contains resin.

Various epoxy functionalized resins such as liquid bisphenol A epoxy resin, solid bisphenol A epoxy resin, liquid bisphenol F epoxy resin, phenol novolac resin polyfunctional epoxy resin, dicyclopentadiene type resin, naphthalene type epoxy resin and These mixtures are suitable for use herein.

Representative epoxy functionalized resins suitable for use in the present invention include alicyclic alcohol diepoxides, hydrogenated bisphenol A, functional alicyclic glycidyl esters of dihexahydrophthalic acid anhydride, and mixtures thereof. Can be mentioned.

Suitable acrylates used in the present invention are well known in the art.

（式中、RはHまたはメチルであり、Xは、（a）8〜24個の範囲の炭素原子を有するアルキル基、または（b）

（式中、RはHまたはメチルであり、R’はHまたはメチルから独立に選択され、xは2〜6の整数である）から選択される）を有する化合物が挙げられる。 Examples of (meth) acrylates suitable for use in the present invention include the following general structure I:

(In the formula, R is H or methyl and X is (a) an alkyl group having 8 to 24 carbon atoms, or (b).

(In the formula, R is selected from H or methyl, R'is selected independently of H or methyl, x is an integer of 2-6).

Preferably, the (meth) acrylate is tridecyl methacrylate, 1,6-hexanediol dimethacrylate, 1,10-decanediol diacrylate, 1,10-decanediol dimethacrylate, 1,12-dodecanediol diacrylate, 1 , 12-Dodecanediol dimethacrylate and mixtures thereof are selected.

Suitable cyanide esters used in the present invention are well known in the art.

Suitable cyanate ester monomers for use in the present invention contain two or more ring-forming cyanate (-O-C = N) groups, which are cyclotrimerized to form substituted triazine rings upon heating. To do. The curing reaction is called addition polymerization because no leaving group or volatile by-product is formed during the curing of the cyanate ester monomer. Preferably, the polycyanic acid ester monomers that may be used in the present invention are 1,1-bis (4-cyanatophenyl) methane, 1,1-bis (4-cyanatophenyl) ethane, 2,2-bis ( 4-Cyanatophenyl) Propyl, Bis (4-Cyanatophenyl) -2,2-Butane, 1,3-Bis 2- (4-Cyanatophenyl) Propylbenzene, Bis (4-Cyanatophenyl) Ether, 4,4'-Disianatodiphenyl, bis (4-cyanato-3,5-dimethylphenyl) methane, tris (4-cyanatophenyl) ethane, noborak cyanide, 1,3-bis 4-cyanatophenyl-1 It is selected from the group consisting of − (1-methylethylidene) benzene, phenol cyanide-diclopentadiene adducts and mixtures thereof. The polycyanic acid ester monomer used in the present invention can be easily prepared by reacting a suitable divalent or polyhydric phenol with cyanogen halide in the presence of an acid receptor.

Suitable silicones used in the present invention are well known in the art.

Suitable silicone-based adhesive formulations for use in the present invention include substantially stoichiometric mixtures of H-terminated polysiloxanes (s) and vinyl-terminated polysiloxanes (s). .. A typical H-terminal polysiloxane for use herein is H-terminal polydimethylsiloxane. A typical vinyl-terminated polysiloxane for use herein is divinyl-terminated polydimethylsiloxane.

Suitable resins for use in the present invention are also oxetane containing monomers and / or oligomers.

The conductive composition according to the present invention contains 1% to 10% by weight, preferably 1% to 8% by weight, more preferably 2% to 6% by weight of the resin based on the total weight of the composition.

If the composition contains less than 1% by weight of the total weight of the composition, the adhesive strength will be extremely poor. On the other hand, if the composition contains a resin in excess of 10% by weight of the total weight of the composition, the composition may result in insufficient conductivity, which is not ideal for metal mesh applications.

Preferably, the volume ratio of the conductive particles to the resin is 1.5 to 3.5, preferably 2.0 to 3.0.

The volume ratio is calculated based on the weight of the resin and the conductive particles added to the composition. Volume = weight / density, assuming the density of particles and resin is known.

This volume ratio range is ideal and meets conductivity requirements (<5E-05 ohm cm).

Solvent The conductive composition according to the present invention contains at least one organic solvent. Various known organic solvents can be used in the present invention. The solvent used in the present invention is not particularly limited as long as it has good compatibility with both the resin and the conductive particles according to the present invention. Preferred solvents have a relatively low evaporation rate at room temperature to ensure sufficient treatment time and a relatively high evaporation rate at healing temperature to ensure sufficient binder shrinkage during curing and drying. Should be.

Suitable organic solvents for use in the present invention are preferably dipropylene glycol methyl ether (DPM), 3-methoxy-3-methyl-1-butanol (MMB), butyl glycol acetate (BGA), diethylene glycol, ethylene glycol. Monobutyl ether, DBE, mixture of dimethyl glutarate and dimethyl succinate (DBE-9), mixture of dimethyl adipate and dimethyl glutarate (DBE-3), succinic acid dimethyl ester (DBE-4), glutaric acid dimethyl ester ( It is selected from the group consisting of DBE-5), dimethyl adipate (DBE-6), propylene glycol methyl acetate (PMA), butyl carbitol (BC), butyl carbitol acetate (BCA) and mixtures thereof, more preferably DBE. It is selected from the group consisting of -9, DPM, PMA, BC, BGA and mixtures thereof.

The conductive composition according to the present invention is at least one organic of 10% to 50% by weight, preferably 15% to 40% by weight, more preferably 20% to 35% by weight of the total weight of the composition. Contains solvent. The amount of solvent is meant herein to include the sum of the solvent and possible co-solvents.

The term co-solvent means an additional solvent that goes into the composition with other reagents, or, for example, a solvent used to obtain particle dispersion.

If the amount of solvent and co-solvent is too high in the composition, the effective solids content will be reduced in the composition, which will produce a thinner film after curing, resulting in less conductivity. Bring. On the other hand, if sufficient solvent is not present in the composition, the composition will develop too high a viscosity, which can result in workability problems during the manufacturing process.

Additives In addition to the above components, the conductive composition according to the invention further comprises 0.01% to 5% by weight, preferably 0.05% to 2% by weight of the total weight of the composition. May include.

Additives may be selected from the group consisting of fluidity modifiers, conductivity modifiers, pigments and mixtures thereof.

The conductivity modifier is a very preferred additive and is particularly preferred when the composition according to the invention contains only the first particles. A large amount of the first particles in the composition according to the invention may, in some cases, reduce the conductivity of the composition. Therefore, it is preferable to use an additional conductivity modifier to improve the conductivity of the composition.

The conductivity modifier is different from the conductive particles (different from the first and second particles). Examples of suitable conductivity modifiers for use in the present invention are organic dibasic acids, for example acids containing compounds such as glutaric acid; phosphate-containing organic compounds such as phosphoric acid 2-hydroxyethyl methacrylate; metal-containing. Complexes and organic metal compounds such as silver acetylacetonate and palladium methacrylate.

Examples of pigments suitable for use in the present invention are dyes such as Clariant RLSN, Clariant GLX; inorganic materials such as carbon black, nickel oxide, cobalt oxide, silver oxide; organometallic compounds such as silver acetylacetonate. And dye materials such as palladium methacrylate.

The fluidity modifier is a highly preferred additive and is particularly preferred when the composition according to the invention contains only the first particles. The use of the first particles in the composition reduces the fluidity profile of the composition in order to increase the adhesiveness and / or adhesive strength of the composition. Therefore, it is desirable to adjust the fluidity of the composition.

Examples of suitable fluidity modifiers for use in the present invention are, for example, Disperbyk-111, Disperbyk-180, Disperbyk-145, and BYK-W980 by BYK-Chemie.

In a preferred embodiment, the conductive composition according to the invention is a first conductive particle having an aspect ratio of 1 or more and less than 2.0, such as spherical particles, faceted particles, pyramidal particles and these. Contains a first particle selected from a mixture of, resin, and at least one organic solvent.

In another preferred embodiment, the conductive composition according to the invention comprises conductive particles, which are a mixture of the first and second particles, as well as the particles, a resin, and at least one organic solvent. The particle 1 has an aspect ratio of 1 or more and less than 2.0, and the first particle is selected from spherical particles, faceted particles, prismatic particles and a mixture thereof, and the second particle is selected from these. Is a non-spherical particle having an aspect ratio greater than 2.0.

In a preferred embodiment, the conductive composition according to the invention is a first conductive particle having an aspect ratio of 1 or more and less than 2.0, such as spherical particles, faceted particles, prismatic particles and these. Contains a first particle selected from a mixture of, a resin, and at least one organic solvent and at least one conductivity modifier.

In a preferred embodiment, the conductive composition according to the invention is a first conductive particle having an aspect ratio of 1 or more and less than 2.0, such as spherical particles, faceted particles, pyramidal particles and these. Contains a first particle selected from a mixture of, a resin, and at least one organic solvent and at least one fluidity modifier.

In a preferred embodiment, the conductive composition according to the invention is a first conductive particle having an aspect ratio of 1 or more and less than 2.0, such as spherical particles, faceted particles, prismatic particles and these. Contains a first particle selected from a mixture of, a resin, at least one organic solvent, at least one conductivity modifier, and at least one fluidity modifier.

In another preferred embodiment, the conductive composition according to the invention comprises conductive particles that are a mixture of first and second particles, as well as particles, resin, at least one organic solvent and at least one conductivity. Containing a rate modifier, the first particle has an aspect ratio of 1 or more and less than 2.0, and the first particle is from spherical particles, faceted particles, prismatic particles and mixtures thereof. The second particle selected is a non-spherical particle having an aspect ratio greater than 2.0.

In another preferred embodiment, the conductive composition according to the invention comprises conductive particles that are a mixture of first and second particles, as well as particles, resin, at least one organic solvent and at least one conductivity. The first particle has an aspect ratio of 1 or more and less than 2.0, and the first particle is a spherical particle, a faceted particle, which contains a regulator and at least one fluidity regulator. Selected from prismatic particles and mixtures thereof, the second particle is a non-spherical particle with an aspect ratio greater than 2.0.

The conductive composition according to the present invention can be prepared in several ways by mixing all the components together.

In one embodiment, the composition is prepared by mixing all particles, resin, organic solvent (s) and any necessary additives using a high shear mixer until the composition is uniform. It is made.

The conductive composition according to the invention can be cured and / or sintered.

The normal temperature for sintering silver particles is above 180 ° C. However, due to the plastic base material used in the touch screen, the sintering temperature cannot be raised very much due to the properties of the plastic base material. Therefore, a low curing temperature is required. The process according to the invention allows curing at 150 ° C. by selecting suitable conductive particles. If a conductivity modifier is used in the composition, the temperature can be further reduced. The standard curing or sintering profile according to the invention is 150 ° C. for 30 minutes.

Alternatively or additionally, UV irradiation can be used in the curing process.

Another aspect relates to a method of adjusting a transparent conductive mesh according to the method.
A step of forming a mesh pattern consisting of grooves having a width larger than −0 μm and a width smaller than 5 μm on the surface of the substrate, and
-The step of filling the groove with the conductive composition according to the present invention,
-The step of cleaning the residual composition from the surface of the substrate,
-Contains a step of curing or sintering the composition.

According to the present invention, a mesh pattern can be formed on the surface of the base material by various techniques. Suitable techniques used herein are, for example, imprinting processes, soft lithography methods and laser patterning methods. The imprinting process is the most preferred method.

A suitable substrate for use in the present invention is preferably selected from the group consisting of polyethylene terephthalate (PET), polymethylmethacrylate, polyethylene, polypropylene, polycarbonate, epoxy resin, polyimide, polyamide, polyester or glass, and is preferable. The base material is polyethylene terephthalate.

In the washing step, the residual composition is removed from the substrate by wiping with a wiper and solvent. It is important that as little residue as possible remains on the substrate surface after the filling and cleaning steps. Spherical and / or faceted and / or pyramidal particles are preferred over non-spherical / flaky particles. The reason is that the flaky particles tend to adhere more strongly to the surface of the substrate and are more difficult to remove.

According to the present invention, it is preferable to carry out the curing or sintering at a temperature of less than 150 ° C. or less than 130 ° C.

The composition according to the invention improves the efficiency of the cleaning step and at the same time removes excess adhesive other than the grooves.

In a further aspect, the invention relates to a conductive mesh prepared by the above method.

The conductive composition according to the invention has a volume resistivity of less than 5E-5 ohm · cm, preferably less than 3E-5 ohm · cm after drying and curing. Volume resistivity is measured by an Agilent 34401A multimeter using standard 4-wire resistivity measurements. Once the resistance value of the sample is measured and the dimensions of the sample are measured, the volume resistivity of the sample can be calculated based on them.

The conductive composition according to the invention has a reflection brightness value L ^* of less than 65%, preferably less than 60%, after drying and curing, as measured by CIELAB color space measurements using a Datacolor650 device. L ^* represents the lightness of the color. In the present invention, the brightness reflected from the sample surface is preferably as low as possible.

The conductive mesh according to the present invention has an adhesive force between the mesh and the substrate of at least level 5B as measured by a grid tape method according to ASTM standard test method D3359-97.

The conductive mesh according to the present invention is a flexible or rigid touch panel or OLED display or smart window or transparent heater or thin film photoelectric device or dye brightening electromotive device or organic photoelectromotive device or electromagnetic field interference shield or static electricity. Suitable for use in electro-discharge or thin film switches.

Accordingly, a further aspect of the invention provides a touch panel display comprising a conductive mesh on a substrate, the mesh comprising a cured or sintered composition according to the invention.

The Example composition is made by mixing particles, resin, organic solvent (s) and any necessary additives using a high shear mixer until the composition is substantially uniform. To.

In all compositions, a resin PVDC copolymer (Saran F-310 from DOW) and a solvent DBE-9 (Sigma-Aldrich) are used. The volume ratio of silver to the resin is kept constant at 2.43 (as well as in the comparative example). The presample is cured at 150 ° C. for 30 minutes. Volume resistivity and surface L ^* measurements are performed by the methods described above.

Unless otherwise specified, the additive is added in a given weight% based on the total weight of the composition.

Unless otherwise specified, the base material used in the examples is a PET base material. The adhesive strength of the cured mesh structure to the PET substrate is tested by a standard crosshatch test (test method described above).

The amount of residual composition on the surface of the substrate can be measured by visual inspection and / or SEM.

Example 1
Compositions 1-6 according to the present invention

Composition 1 contains spherical silver particles together with faceted particles having an average particle size of about 0.3 μm. As a result, the L ^* of the cured mesh structure is further reduced to about 62% and has an acceptable volume resistivity. Furthermore, after cleaning, it has been clarified that there are less residual silver particles in the substrate as compared with Comparative Example 2.

Composition 2 contains a mixture of faceted silver particles (average particle size of about 0.3 μm) and spherical silver particles (average particle size of about 100 nm) in a weight ratio of 6: 1. As a result, the L ^* of the cured film mesh structure is further reduced to about 65% and has a volume resistivity slightly smaller than that of composition 3. Furthermore, after cleaning, it has been clarified that there are fewer residual silver particles as compared with Comparative Example 2.

Composition 3 contains a spherical silver particle containing faceted silver particles (average particle size of about 0.3 μm) and a mixture of spherical silver particles (average particle size of about 100 nm) having a weight ratio of 3: 1. As a result, the L ^* of the cured mesh structure is further reduced to about 62% and still has a volume resistivity of less than 5E-5 ohm cm. Furthermore, after cleaning, it has been clarified that there are fewer residual silver particles as compared with Comparative Example 2.

The composition 4 contains 0.2% by weight (total composition) of a conductivity accelerator (2-hydroxyethyl methacrylate phosphate) in addition to the same basic components as the above composition 3. It has been clarified that the volume resistivity decreases from 1.27E-5 to 7.7E-6 ohm · cm, although the L ^* value hardly changes. Therefore, the conductivity was improved and at the same time the low reflectance of the mesh structure was maintained. Furthermore, after cleaning, it has been clarified that there are fewer residual silver particles as compared with Comparative Example 2.

The composition 5 contains 0.2% by weight (total composition) of the black dye GLX (Clariant) in addition to the basic components of the composition 6. The L ^* value drops from 60.74% to 58.82% and the volume resistivity increases from 7.7E-6 to 1,27E-5 ohm cm, but this volume resistivity is still a requirement for the application. It is known to be within range. Furthermore, after cleaning, it has been clarified that there are fewer residual silver particles as compared with Comparative Example 2.

Composition 6 contains 0.5% by weight (total composition) of palladium methacrylate in addition to the basic components of composition 5. Although the L ^* value drops from 62% to 56%, volume resistivity is still known to be within the application requirements. Furthermore, after cleaning, it has been clarified that there are fewer residual silver particles as compared with Comparative Example 2.

Example 2
Compositions 7-9 according to the invention

Example 3
Comparative Example-Composition 10
Binder Resin Polyvinylidene Chloride (PVDC) Saran F-310 (Dow Chemicals) is dissolved in DBE-9 solvent at 30% solids weight percent (30% by weight PVDC and 70% by weight DBE-9). Then, this solution is used as a master resin solution. The silver particles used are non-spherical particles (N300 (Tokusen)) having an aspect ratio larger than 30 (average particle size is about 0.3 μm). The silver dispersion contains 90% by weight of silver particles and 10% by weight of DBE-9. An additional solvent (DBE-9) is added to adjust the final solid weight percent and viscosity accordingly. The volume ratio of silver to resin is kept constant at 2.43.

The conductivity of the hardened mesh structure is high enough, but the reflectance is too high, making the mesh structure grayish white and visible. It has also become clear that during the metal mesh structure manufacturing process, residual silver particles on the substrate need to be carefully removed and washed. Otherwise, the residual particles will appear as visible defects, which is not desirable for the final product yield.

Example 4
Comparative Example-Compositions 11-15
The Savinyl RLSN black dye produced by Clariant is added to composition 7 of Comparative Examples in amounts of 0.1% by weight, 0.5% by weight, 1% by weight and 2% by weight of the total weight of the composition. The measured L ^* and volume resistivity are shown in the table below.

The L ^* value can reach about 65.5%, but the volume resistivity correspondingly rises to a value too high above 5E-5 ohm cm. In addition, there is no change in the difficulty in cleaning the residual silver particles during the metal mesh structure manufacturing process.

Preferred embodiments of the present invention include:
[1] A conductive composition
a) A first particle having an aspect ratio of 1 or more and less than 2.0, which is selected from spherical particles, faceted particles, prismatic particles, and a mixture thereof, or the first particle. Conductive particles selected from a mixture of the particles of the second particle and the second particle, which is a second particle and is a non-spherical particle having an aspect ratio greater than 2.0.
b) Resin; and
c) At least one organic solvent
A conductive composition comprising.
[2] The conductive particles are selected from the group consisting of metals, metal alloys, metal-containing composite materials, non-metal particles and mixtures thereof, preferably silver, gold, platinum, copper, nickel, aluminum, zinc and iron. , Copper-nickel, silver-copper, silver-nickel, copper-aluminum, silver-plated copper, silver-plated glass, silver-plated graphite, silver-plated fiber, graphite, carbon black, carbon nanotubes and mixtures thereof. , More preferably, the composition according to [1], wherein the conductive particles are silver.
[3] The composition according to [1] or [2], wherein the spherical or faceted or pyramidal particles have an average particle size of 5 nm to 1 μm, preferably 5 nm to 500 nm, and more preferably 5 nm to 200 nm.
[4] The composition according to any one of [1] to [3], wherein the non-spherical particles preferably have an aspect ratio larger than 10.0.
[5] The composition according to any one of [1] to [4], wherein the non-spherical particles have an average particle size of 10 nm to 2 μm, preferably 10 nm to 1 μm.
[6] The composition is
-First particles from 5% to 85% by weight, preferably 60% to 75% by weight of the total weight of the composition, or
− 10% to 85% by weight of the total weight of the composition, preferably 30% to 70% by weight of the second particles, and 5% to 40% by weight of the first of the total weight of the composition. particle
The composition according to any one of [1] to [5], which comprises.
[7] The weight ratio of the second particle to the first particle is 6: 1 to 1: 2, preferably 3: 1 to 1: 1, according to any one of [1] to [6]. Composition.
[8] The resin is preferably selected from the group consisting of halogenated thermoplastic resins, phenoxy resins, polyester resins, thermoplastic polyurethanes, polyvinylidenes, silicones and mixtures thereof; more preferably PVDC polymers, PVDC copolymers, phenoxys. The composition according to any one of [1] to [7], which is selected from the group consisting of resins, polyvinylidenes and mixtures thereof; most preferably selected from the group consisting of PVDC polymers and PVDC copolymers and mixtures thereof. ..
[9] Contains 1% to 10% by weight, preferably 1% to 8% by weight, more preferably 2% to 6% by weight of the total weight of the composition [1] to [8]. ] The composition according to any one of.
[10] The composition according to any one of [1] to [9], wherein the volume ratio of the particles to the resin is 1.5 to 3.5, preferably 2.0 to 3.0.
[11] The at least one organic solvent is preferably dipropylene glycol methyl ether (DPM), 3-methoxy-3-methyl-1-butanol (MMB), butyl glycol acetate (BGA), diethylene glycol, ethylene glycol mono. Butyl ether, DBE, DBE-9, DBE-3, DBE-4, DBE-5, DBE-6, propylene glycol methyl acetate (PMA), butyl carbitol (BC), butyl carbitol acetate (BCA) and mixtures thereof. The composition according to any one of [1] to [10], which is selected from the group consisting of.
[12] A method for preparing a conductive mesh.
A step of forming a mesh pattern consisting of grooves having a width larger than −0 μm and a width smaller than 5 μm on the surface of the substrate, and
-The step of filling the groove with the composition according to any one of [1] to [11].
-The step of cleaning the residual composition from the surface of the substrate,
-With the steps of curing or sintering the composition
Including methods.
[13] The method according to [12], wherein the curing or sintering is carried out at a temperature of less than 150 ° C.
[14] A conductive mesh prepared by the method according to [12] or [13].
[15] A touch panel display comprising a conductive mesh on a substrate, said mesh comprising the cured or sintered composition according to any one of [1] to [11].

Claims (23)

a) A first particle having an aspect ratio of 1 or more and less than 2.0, which is selected from spherical particles, faceted particles, prismatic particles, and a mixture thereof, or the first particle. A conductive particle selected from a mixture of the second particle and the second particle, which is a second particle and is a non-spherical particle having an aspect ratio greater than 2.0.
b) Halogenated thermoplastics; and
c) A conductive composition containing at least one organic solvent, wherein the spherical particles or faceted particles or prismatic particles have an average particle size of 5 nm to 1 μm, and the composition is , look including the first particle 60 wt% to 85 wt% of the total weight of the composition, the halogenated thermoplastic resin is from the group consisting of poly two vinyl and polyvinyl dichloride chloride copolymers and mixtures thereof The conductive composition of choice . The composition according to claim 1, wherein the conductive particles are selected from the group consisting of metals, metal alloys, metal-containing composite materials, non-metal particles and mixtures thereof. The conductive particles include silver, gold, platinum, copper, nickel, aluminum, zinc, iron, copper-nickel, silver-copper, silver-nickel, copper-aluminum, silver-plated copper, silver-plated glass, and silver-plated graphite. The composition according to claim 2, selected from the group consisting of silver-plated fibers, graphite, carbon black, carbon nanotubes and mixtures thereof. The composition according to claim 2, wherein the conductive particles are silver. The composition according to any one of claims 1 to 4, wherein the spherical or faceted or pyramidal particles have an average particle size of 5 nm to 500 nm. The composition according to claim 5, wherein the spherical or faceted or pyramidal particles have an average particle size of 5 nm to 200 nm. The composition according to any one of claims 1 to 6, wherein the non-spherical particles, which are the second particles, have an aspect ratio larger than 10.0. The composition according to any one of claims 1 to 7, wherein the non-spherical particles, which are the second particles, have an average particle size of 10 nm to 2 μm. The composition according to claim 8, wherein the non-spherical particles, which are the second particles, have an average particle size of 10 nm to 1 μm. The composition
- said first particles of 60 wt% to 75 wt% of the amount of the total weight of the composition, or - the composition second particle element of at least 10 wt% of the total weight of the
Containing composition according to any one of claims 1 to 9. The composition comprises a second particle child over 30% by weight of the total weight of the composition, The composition of claim 10. The composition according to any one of claims 1 to 11 , further comprising a resin selected from the group consisting of phenoxy resins, polyester resins, thermoplastic polyurethanes, polyacrylates, silicones and mixtures thereof. The composition according to claim 12 , further comprising a resin selected from the group consisting of phenoxy resins, polyacrylates and mixtures thereof. The composition according to any one of claims 1 to 13 , wherein the halogenated thermoplastic resin is selected from the group consisting of a PVDC polymer, a PVDC copolymer, and a mixture thereof. The composition according to any one of claims 1 to 14, which comprises an amount of 1% to 10% by weight of the resin based on the total weight of the composition. The composition according to any one of claims 1 to 15 , wherein the volume ratio of the particles to the resin is 1.5 to 3.5. The composition according to claim 16 , wherein the volume ratio of the particles to the resin is 2.0 to 3.0. At least one organic solvent is dipropylene glycol methyl ether (DPM), 3-methoxy-3-methyl-1-butanol (MMB), butyl glycol acetate (BGA), diethylene glycol, ethylene glycol monobutyl ether, DBE, DBE- 9. Selected from the group consisting of DBE-3, DBE-4, DBE-5, DBE-6, propylene glycol methyl acetate (PMA), butyl carbitol (BC), butyl carbitol acetate (BCA) and mixtures thereof. The composition according to any one of claims 1 to 17 . The at least one organic solvent is a group consisting of DBE-9, dipropylene glycol methyl ether (DPM), propylene glycol methyl acetate (PMA), butyl carbitol (BC), butyl glycol acetate (BGA) and a mixture thereof. The composition according to claim 18 , which is selected from. A method of preparing a conductive mesh
A step of forming a mesh pattern consisting of grooves having a width larger than −0 μm and a width smaller than 5 μm on the surface of the substrate, and
-The step of filling the groove with the composition according to any one of claims 1 to 19 .
-The step of cleaning the residual composition from the surface of the substrate,
-A method comprising the steps of curing or sintering the composition. The method of claim 20 , wherein the curing or sintering is carried out at a temperature of less than 150 ° C. A conductive mesh prepared by the method according to claim 20 or 21 . Includes a conductive mesh on the substrate, the mesh comprising a cured or sintered composition according to any one of claims 1 to 19 touch panel display.