Silica composite

Abstract

To provide silica that is uniformly dispersed in a resin composition. [Solution] A silica composite for use as a paint additive, ink additive, or anti-blocking agent for resin films or sheets, comprising silica and at least one alcohol selected from the group consisting of monohydric alcohols and polyhydric alcohols and their derivatives, bonded to or adsorbed on the silica.

Description

[Technical Field]

[0001] This disclosure relates to silica composites, resin compositions, and resin films or resin sheets. [Background technology]

[0002] Silica is used in a variety of applications, including as an additive in paints or inks, as an antiblocking agent for resin films or sheets, and more. In some cases, silica is surface-treated with specific compounds to impart various properties to it. For example, Patent Document 1 describes surface-treating silica with wax to improve its precipitation behavior in paints. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Special Publication No. 51-31235 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, our research has shown that silica surface-treated with wax tends to aggregate in resin compositions. Therefore, for example, when silica is added as a matting agent to paint or ink, uneven irregularities may form on the surface of the formed coating or ink film, resulting in a matte finish that is not perfectly smooth. Also, for example, when silica is added as an antiblocking agent to a resin film or resin sheet, fisheyes or other defects caused by aggregates may appear on the surface of the formed resin film or resin sheet. In this case, the quality of the film, such as appearance and strength, will deteriorate.

[0005] One aspect of this disclosure is to provide silica that is uniformly dispersed in a resin composition. Another aspect of this disclosure is to provide a resin composition and a resin film or resin sheet containing said silica. [Means for solving the problem]

[0006] One aspect of the present disclosure is a silica composite for use as an additive in paints, an additive in inks, or an antiblocking agent for resin films or resin sheets. The silica composite comprises silica and at least one alcohol selected from the group consisting of monohydric alcohols, polyhydric alcohols and their derivatives, which is bound to or adsorbed on the silica.

[0007] In one aspect of this disclosure, the alcohols may include trihydric alcohols. In one aspect of this disclosure, the trihydric alcohol may include at least one selected from the group consisting of glycerol, trimethylolethane, and trimethylolpropane.

[0008] In one aspect of this disclosure, the trihydric alcohol may include at least one selected from the group consisting of trimethylolethane and trimethylolpropane. In one aspect of this disclosure, the alcohol content in the silica composite may be 0.1% by mass or more and 30% by mass or less.

[0009] In one aspect of this disclosure, the ratio of the BET specific surface area determined by the water vapor adsorption method to the BET specific surface area determined by the nitrogen gas adsorption method in the silica composite may be 15% or more and 45% or less.

[0010] In one aspect of this disclosure, the volume-average particle size of the silica composite may be 0.5 μm or more and 20 μm or less. In one aspect of this disclosure, silica may include wet silica.

[0011] One aspect of the present disclosure is a resin composition comprising the silica composite described above. One aspect of the present disclosure is a resin film or resin sheet comprising a silica composite for use as an antiblocking agent for the above-mentioned resin film or resin sheet. [Effects of the Invention]

[0012] According to one aspect of the present disclosure, silica uniformly dispersed in a resin composition is provided. Also according to one aspect of the present disclosure, a resin composition and a resin film or resin sheet containing said silica are provided. [Modes for carrying out the invention]

[0013] Hereinafter, a silica composite, a resin composition, and a resin film or resin sheet relating to one aspect of this disclosure will be described in order. <Silica composite> The silica composite comprises silica and at least one alcohol selected from the group consisting of monohydric alcohols, polyhydric alcohols and their derivatives, which is bound to or adsorbed on the silica. Such a silica composite can be suitably used as an additive in paints, an additive in inks, or an antiblocking agent for resin films or resin sheets.

[0014] Silica composites can be obtained by surface-treating silica with the alcohols mentioned above. It is thought that surface-treating silica with alcohols causes the hydroxyl groups of the alcohols to bond with the silanol groups on the silica surface, or the alcohols to be adsorbed onto the silica surface.

[0015] On the surface of such a silica composite, hydrophobic groups such as alkyl groups derived from alcohols and hydrophilic groups such as hydroxyl groups derived from alcohols and silanol groups on the silica surface are thought to be appropriately arranged. Because such a surface has a high affinity for resin components commonly found in paints, inks, or resin films or sheets, the silica composite is uniformly dispersed in the resin composition, and aggregation of the silica composites is suppressed.

[0016] As a result, for example, when the silica composite is added as a matting agent for paints or inks, uniform irregularities are formed on the surface of the formed paint film, and a smooth, matted and pleasant surface can be obtained. In particular, when the silica composite is added as a matting agent for inks, printed matter with high resolution can be obtained. Further, for example, when silica is added as an anti-blocking agent for a resin film or a resin sheet, fish eyes, unevenness, streaks, etc. are less likely to occur in the obtained resin film or resin sheet.

[0017] In addition, when a paint of a silica composite surface-treated with wax or the like is overcoated, there may be a phenomenon in which the overcoated paint is repelled. This is considered to be because the surface state of the paint film changes due to factors such as the organic substances such as wax on the silica surface mixing with a resin component having better compatibility and separating from the silica.

[0018] On the other hand, even when a paint of a silica composite surface-treated with the above-mentioned specific alcohols is overcoated, the overcoated paint is less likely to be repelled. Hereinafter, the silica composite will be described in detail.

[0019] As the silica, porous silica is preferable because it is suitable for use as an additive for paints, an additive for inks, and an anti-blocking agent for resin films or resin sheets. Examples of the porous silica include wet silica produced by a wet method. Specific examples of the wet silica include precipitated silica, silica gel, and the like. As the silica, silica gel is preferable because it is suitable for use as an additive for paints, an additive for inks, and an anti-blocking agent for resin films or resin sheets.

[0020] As the alcohols, as described above, monohydric alcohols, polyhydric alcohols, and derivatives of polyhydric alcohols can be mentioned.

[0021] Examples of monohydric alcohols include monohydric saturated or unsaturated aliphatic alcohols and monohydric aromatic alcohols. Examples of monohydric alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, isobutyl alcohol, s-butanol, t-butanol, 1-pentanol, 2-pentanol, 3-methyl-1-butanol, 1-hexanol, 2-hexanol, 2-ethyl-1-butanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, cyclohexanol, pinacollyl alcohol, benzyl alcohol, isopentenyl alcohol, 3,3-dimethylallyl alcohol, clotyl alcohol, β-methallyl alcohol, and sorbyl alcohol. The number of carbon atoms in the monohydric alcohol is preferably 1 to 10, and more preferably 1 to 4.

[0022] Examples of polyhydric alcohols include ethylene glycol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 1,2-hexanediol, 2-methyl-2,4-pentanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, pinacol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, tripropylene glycol, glycerol, diglycerol, triglycerol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, sorbitol, sucrose, and the like. The number of carbon atoms in the polyhydric alcohol is preferably 2 to 10, and more preferably 3 to 7.

[0023] Examples of polyhydric alcohol derivatives include compounds in which some of the hydroxyl groups of a polyhydric alcohol are alkyl etherified. Examples of polyhydric alcohol derivatives include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, carbitol, ethyl carbitol, butyl carbitol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, and tripropylene glycol monomethyl ether.

[0024] Among these, trihydric alcohols are preferred. Compared to monohydric or dihydric alcohols, trihydric alcohols are thought to have more hydroxyl groups present on the surface of the silica composite that do not participate in bonding or adsorption with silica. As a result, the balance between hydrophobic and hydrophilic groups on the surface of the silica composite becomes appropriate, so that the silica composite is dispersed more uniformly in the resin composition. Among trihydric alcohols, at least one selected from the group consisting of glycerol, trimethylolethane, and trimethylolpropane is preferred, and at least one selected from the group consisting of trimethylolethane and trimethylolpropane is more preferred.

[0025] The alcohol content in the silica composite is preferably 0.1% by mass or more, and more preferably 2% by mass or more, in order to ensure that the silica composite is more uniformly dispersed in the resin composition. Furthermore, since there is a limit to the amount of alcohol that can be bound to or adsorbed onto silica, the alcohol content in the silica composite is preferably 30% by mass or less, and more preferably 15% by mass or less.

[0026] In silica composites, the ratio of the BET specific surface area determined by the water vapor adsorption method to the BET specific surface area determined by the nitrogen gas adsorption method is preferably 15% to 45%, more preferably 25% to 42%, and even more preferably 25% to 40%. This ratio is an index representing the degree of hydrophilicity / hydrophobicity of the measured substance, with a higher value indicating higher hydrophilicity. Hereinafter, this ratio will be referred to as the "hydrophilic surface ratio." In silica composites, the more silanol groups, hydroxyl groups derived from alcohols, and ether bonds derived from alcohol derivatives there are on the silica surface, the higher the value of the hydrophilic surface ratio. When the hydrophilic surface ratio is within the above range, the degree of hydrophilicity / hydrophobicity of the surface of the silica composite is appropriate, and the silica composite is dispersed more uniformly in the resin composition.

[0027] In silica composites, the BET specific surface area determined by nitrogen gas adsorption is 50 m². 2 / g or more 800m 2 It is preferable that it be less than or equal to / g, and 100m 2 / g or more 550m 2 It is more preferable that it be less than or equal to / g, and 200m 2 / g or more and less than 350 m 2 It is even more preferable that the BET specific surface area is less than or equal to / g. Silica composites having a BET specific surface area in this range are suitable for use as additives in paints, additives in inks, and antiblocking agents for resin films or sheets.

[0028] Furthermore, the pore volume of the silica composite is 0.3 cm³. 3 / g or more 2.2cm 3 It is preferable that it be less than or equal to / g, and 0.5cm3 2.0 cm or more per g 3 It is more preferably 2.0 cm or less per g. The pore volume here is the value obtained by converting the amount of nitrogen gas adsorbed at a relative pressure of 0.99 in the nitrogen gas adsorption isotherm into liquid.

[0029] In addition, the average pore diameter of the silica composite is preferably 2 nm or more and 75 nm or less, and more preferably 5 nm or more and 30 nm or less. The average pore diameter can be calculated from the above-mentioned pore volume and the BET specific surface area determined by the above-mentioned nitrogen gas adsorption method

[0030] The volume average particle diameter of the silica composite is preferably 0.5 μm or more and 20 μm or less, more preferably 1 μm or more and 15 μm or less, and still more preferably 2 μm or more and 8 μm or less. When the volume average particle diameter is within such a range, for example, irregularities of an appropriate size can be formed on the surface of a coating film, an ink film, or a resin film or resin sheet. Generally, such silica with a relatively small volume average particle diameter tends to aggregate, but aggregation can be suppressed by surface-treating silica with the above-mentioned alcohols. The volume average particle diameter here is the value measured using a laser diffraction scattering method particle size distribution measuring device in an aqueous solution.

[0031] The method for producing the silica composite is not particularly limited. For example, a paste-like mixture obtained by mixing silica and a solution containing alcohols is dried and pulverized to obtain a silica composite. Also, for example, a predetermined amount of alcohols may be added in advance to a slurry solution of silica during the wet method process, and the obtained mixed slurry solution may be spray-dried to obtain a silica composite. Also, for example, a slurry solution of silica obtained by the wet method and alcohols may be mixed using a high-speed flow mixer or the like, and the mixture may be dried and pulverized to obtain a silica composite.

[0032] The amount of alcohol used relative to silica is preferably 0.5 parts by mass or more, and more preferably 2.0 parts by mass or more, per 100 parts by mass of silica. When the amount of alcohol used is 0.5 parts by mass or more per 100 parts by mass of silica, the silica composite is more uniformly dispersed in the resin composition. Furthermore, the amount of alcohol used relative to silica is preferably 12.0 parts by mass or less, and more preferably 6.0 parts by mass or less, per 100 parts by mass of silica. This is because even if the amount of alcohol used is greater than 12.0 parts by mass per 100 parts by mass of silica, the effect of improving dispersibility does not increase significantly.

[0033] As described above, silica composites can be suitably used as additives for paints, inks, or as antiblocking agents for resin films or sheets. Here, "additive" refers to anything added to a paint or ink for any purpose. For example, in the case of paints, additives may include matting agents, and in the case of inks, matting agents, pigments, etc.

[0034] <Resin composition> The resin composition contains the silica composite described above. Examples of resin compositions include paints, inks, resin films, or resin sheet formation compositions. A resin film or resin sheet formation composition refers to a raw material for forming a resin film or resin sheet. Examples of resin composition forms include paste, pellets, plates, granules, and liquids.

[0035] The silica composite content in the resin composition can be appropriately determined considering the intended use of the silica composite, the required physical properties of the silica composite, and other factors. As an example, when the resin composition is a paint or ink, the silica composite content is preferably 0.5% by mass or more, and more preferably 1% by mass or more. When the silica composite content is 0.5% by mass or more, it is easier to achieve the desired physical properties, for example, the desired degree of mattification when used as a matting agent. As another example, the silica composite content is preferably 20% by mass or less, and more preferably 15% by mass or less.

[0036] As an example, when the resin composition is a composition for forming a resin film or resin sheet, the silica composite content is preferably 50 ppm (0.005 mass%) or more, and more preferably 100 ppm (0.01 mass%) or more. When the silica composite content is 50 ppm or more, the antiblocking effect is easily obtained. As another example, the silica composite content is preferably 10,000 ppm (1 mass%) or less, and more preferably 5,000 ppm (0.5 mass%) or less.

[0037] In particular, silica composites can be suitably used to improve the surface properties of the resulting coatings, inks, or resin films or sheets, specifically as a matting agent for paints, a matting agent for inks, or an antiblocking agent for resin films or sheets.

[0038] Paints, inks, or resin films or sheets may contain, in addition to a binder resin component, various components commonly used in paints, inks, or resin films or sheets. Examples of resin components used in paints or inks include acrylic resins, cellulose resins, urethane resins, alkyd resins, epoxy resins, and melamine resins. Examples of resin components used in compositions for forming resin films or sheets include acrylic resins, nylon resins, PET resins, PP resins, and PE resins. In addition, for resin components used in compositions for forming resin films or sheets, at least one selected from the group consisting of nylon resins, acrylic resins, and PET resins is preferred due to its high affinity with silica composites.

[0039] <Resin film or resin sheet> The resin film or resin sheet contains the silica composite described above. The resin film or resin sheet can be manufactured using the resin composition described above. The resin film or resin sheet may consist of a single layer or of multiple layers including other layers. [Examples]

[0040] An embodiment of this disclosure will be described below with reference to examples, but this disclosure is not limited to the following embodiments. (Example 1) 1. Preparation of silica composite A 1% by mass aqueous solution of trimethylolethane (TME) was prepared. 4 g of silica gel ("Silysia® 350", manufactured by Fuji Silysia Chemical Co., Ltd.) was added to 20 g of the 1% by mass aqueous solution of trimethylolethane and mixed to obtain a paste-like mixture. The resulting mixture was dried in a dryer at 110°C. The resulting dried material was then pulverized to obtain a silica-TME composite with a volume-average particle size of 3.9 μm.

[0041] 2. Preparation of paint 100g of acrylic resin paint (manufactured by SK Kaken Co., Ltd.) and 3g of silica-TME composite were placed in a bottle and stirred at 1000 rpm for 5 minutes using a homodisper (manufactured by Primix Co., Ltd.). The mixture was then allowed to stand for 1 hour to remove air bubbles.

[0042] In addition, paint prepared by changing the rotation speed to 3000 rpm was also prepared. (Example 2) A silica-TME composite and paint with a volume-average particle size of 3.9 μm were obtained in the same manner as in Example 1, except that the concentration of the trimethylolethane aqueous solution was 2% by mass.

[0043] (Example 3) A silica-TME composite and paint with a volume-average particle size of 3.9 μm were obtained in the same manner as in Example 1, except that the concentration of the trimethylolethane aqueous solution was set to 0.6% by mass.

[0044] (Example 4) A silica-TMP composite and a paint with a volume-average particle size of 3.9 μm were obtained in the same manner as in Example 1, except that trimethylolpropane (TMP) was used instead of trimethylolethane.

[0045] (Example 5) A silica-glycerol composite and a paint with a volume-average particle size of 3.9 μm were obtained in the same manner as in Example 1, except that glycerol was used instead of trimethylolethane.

[0046] (Example 6) A silica-TME composite and paint with a volume-average particle size of 6.2 μm were obtained in the same manner as in Example 1, except that silica gel ("Silysia® 440," manufactured by Fuji Silysia Chemical Co., Ltd.) was used instead of silica gel ("Silysia® 350," manufactured by Fuji Silysia Chemical Co., Ltd.).

[0047] (Comparative Example 1) Untreated silica gel ("Silysia® 350", manufactured by Fuji Silysia Chemical Co., Ltd.) was prepared. The paint was prepared in the same manner as in Example 1.

[0048] (Comparative Example 2) Silica gel without surface treatment (“Silicia (registered trademark) 440”, manufactured by Fuji Silysia Chemical Ltd.) was prepared. The paint was prepared in the same manner as in Example 1.

[0049] (Comparative Example 3) Silica gel surface-treated with a wax-based organic substance (“Silicia (registered trademark) 446”, manufactured by Fuji Silysia Chemical Ltd.) was prepared. The paint was prepared in the same manner as in Example 1.

[0050] (Comparative Example 4) Silica gel surface-treated with a silylating agent (“Silophorbic (registered trademark) 200”, manufactured by Fuji Silysia Chemical Ltd.) was prepared. The paint was prepared in the same manner as in Example 1.

[0051] (Evaluation) The following evaluations were conducted. The evaluation results are shown in Table 1. For Examples 4 to 6 and Comparative Examples 2 to 4, the evaluation of the number of aggregated particles was not performed for the sake of simplicity.

[0052] <Measurement of BET specific surface area> Using a high-precision gas adsorption measurement device (“BELSORP (registered trademark)-max”, manufactured by Nippon Bell Co., Ltd. (currently Microtrac·Bell Co., Ltd.)), the relative pressure of nitrogen gas and the adsorption amount of nitrogen gas molecules at liquid nitrogen temperature (-196 °C), and the relative pressure of water vapor and the adsorption amount of water vapor molecules at 25 °C were measured. A BET plot was obtained from the obtained nitrogen gas adsorption isotherm and water vapor adsorption isotherm. The specific surface area was calculated from the slope of the straight line in the range of relative pressure 0.05 to 0.30 in the BET plot.

[0053] In addition, the ratio of the BET specific surface area obtained from the water vapor adsorption isotherm to the BET specific surface area obtained from the nitrogen gas adsorption isotherm (that is, the hydrophilic surface ratio) was calculated. <Number of aggregated particles> The adjusted paint was applied to a particle gauge (manufactured by Taisuke Kikai Co., Ltd.) with a groove depth of 0 μm to 100 μm, and the number of aggregated particles observed in the 40 μm to 100 μm portion was counted.

[0054] <Condition of the coating surface> Each of the prepared coatings was applied to a completely black opacity test paper using a 4 mil applicator, and the smoothness of the coating film was evaluated by visually observing the surface under a standard light source. The evaluation criteria were as follows:

[0055] A: It has a smooth surface with uniform, fine irregularities. B: Although there are some slightly larger irregularities, the surface is generally smooth with a uniform and fine pattern of irregularities. C: There are fine and somewhat larger bumps, and the surface is not very smooth. D: There are many small and somewhat large bumps, and the surface is not sufficiently smooth.

[0056] [Table 1]

[0057] (Consideration) The paints obtained in Examples 1 to 6 exhibited excellent surface smoothness, matte finish, and texture when applied as a finished coating.

[0058] On the other hand, the paints obtained in Comparative Examples 1 to 4 showed uneven surface irregularities caused by silica aggregation, particularly when prepared at a rotation speed of 1000 rpm. Furthermore, comparing Examples 1 to 3, Example 1 was superior to Example 3, and Example 2 was even superior in terms of the smoothness of the coating surface.

Claims

1. A silica composite for use as a matting agent for paints or inks, comprising silica and a polyhydric alcohol bound to or adsorbed to the silica, The silica composite wherein the ratio of the BET specific surface area determined by the water vapor adsorption method to the BET specific surface area determined by the nitrogen gas adsorption method is 25.9% or more and 34.1% or less.

2. A silica composite for use as a matting agent for paints or inks, comprising silica and a polyhydric alcohol bound to or adsorbed to the silica, A silica composite having a volume-average particle diameter of 0.5 μm or more and 20 μm or less.

3. The silica composite according to claim 1 or claim 2, wherein the polyhydric alcohol comprises at least one selected from the group consisting of glycerol, trimethylolethane, and trimethylolpropane.

4. The silica composite according to any one of claims 1 to 3, wherein the polyhydric alcohol comprises at least one selected from the group consisting of trimethylolethane and trimethylolpropane.

5. The silica composite according to any one of claims 1 to 4, wherein the content of the polyhydric alcohol in the silica composite is 0.1% by mass or more and 30% by mass or less.

6. The silica composite according to any one of claims 1 to 5, wherein the silica includes wet silica.

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