KR20230002288A - Hydrophobic silica gel for polishing energy ray curing type paint - Google Patents

Abstract

The present invention is a hydrophobic silica gel surface-treated with silicone oil, with a pore volume measured by nitrogen adsorption and desorption in the range of 0.6 to 2 ml / g, an M value in the range of 5 to 40 vol%, and a pressure of 260 MPa. The ratio of the pore volume with a pore radius of 109 nm or less after compression to the pore volume with a pore radius of 109 nm or less before compression (pore volume after compression / pore volume before compression) is in the range of 0.8 to 1.5, energy ray curing type paint gloss It relates to hydrophobic silica gel for removal. According to the present invention, in addition to matting performance, it is possible to provide a hydrophobic silica gel for matting energy ray curable paints having excellent chemical resistance, scratch resistance and sedimentation stability.

Description

Hydrophobic silica gel for polishing energy ray curing type paint

The present invention relates to a hydrophobic silica gel for removing gloss of energy ray curable paint. More specifically, the present invention relates to a hydrophobic silica gel surface-treated with silicone oil used as a matting agent for paints cured by energy rays such as ultraviolet rays (UV) and electron beams (EB).

CROSS REFERENCES OF RELATED APPLICATIONS

This application claims priority from Japanese Patent Application No. 2020-079708 filed on April 28, 2020, the entire description of which is specifically incorporated herein as a disclosure.

Energy ray curing type paints have advantages such as excellent coating film strength and rapid curing properties, and low solvent reduction, so their use has increased in recent years instead of conventional paints using solvents.

A silica matting agent in a conventional paint using a solvent has a large difference in film thickness between coating and film formation after solvent volatilization to form irregularities on the surface to achieve a matting effect. However, in the case of an energy ray curing type paint, there is little decrease in film thickness during coating and film formation. Therefore, a sufficient matting effect could not be exhibited with the conventionally used silica matting agent.

As a solution to this problem, WAX treated silica has been proposed. The wax-treated silica described in Patent Literature 1 is silica having a pore volume of at least 1.5 cm 3 /g and 5.6 to 15% by weight of wax having a melting point of less than 85°C, which is surface-treated. The wax-treated silica described in Patent Literature 2 is silica having a median particle diameter of 2 to 12 µm and surface-treated with 15 to 30% by weight of WAX. All exhibit high matting performance and excellent sedimentation stability in energy ray curing type paints.

JP H11-512124 A (WO97/08250) JP 2003-522219 A (WO01/004217) All descriptions of Patent Literatures 1 and 2 are specifically cited as disclosure in this specification, respectively.

With the rapid spread of energy ray curing type paints in recent years, the demand for performance other than gloss removal performance is also increasing. In particular, matting coatings containing silica are often used for electronic equipment, home appliances, and flooring topcoats to realize a high-quality appearance while protecting the surface by hiding uneven formation or damage of the base. In this application, improvement in chemical resistance and scratch resistance has been required in addition to matting performance.

However, the WAX treated silica of Patent Documents 1 and 2 had insufficient chemical resistance and scratch resistance. When the above-mentioned wax-treated silica is blended into a paint, when the temperature of the paint rises, the wax elutes and deteriorates the appearance. Alternatively, when the paint is stored for a long period of time, WAX is eluted, and there is concern about the deterioration of the coating film properties and appearance.

Therefore, the inventors of the present invention intensively studied hydrophobic silica gel, which was excellent in chemical resistance and scratch resistance in addition to matting performance, as a matting agent suitable for energy ray curing type paints.

As a result, it was found that the problem of scratch resistance of the coating film can be solved by using silica gel having a strong secondary particle aggregation structure. On the other hand, since such a silica gel had a problem in chemical resistance, an attempt was made to solve the problem by hydrophobizing the surface of the silica gel with silicone oil. The film thickness of the coating film formed using the energy ray curing type paint is usually about 5 to 40 μm, and the particle size of the silica gel is, for example, 5 to 20 μm so that the matting performance can be exhibited with the coating film having this film thickness. Adjust to the order of μm.

However, hydrophobic silica gel surface-treated with silicone oil has fewer surface silanol groups than untreated silica gel. Therefore, other problems inherent to the coating material such as not forming flocculation in the solvent and poor sedimentation stability and forming a hard cake arose. It was also found that this point can be improved by controlling the hydrophobic treatment conditions within a predetermined range, and a balance between chemical resistance and sedimentation stability can be obtained.

Based on these findings, the inventors of the present invention have found that it is possible to provide a hydrophobic silica gel for matting energy ray curable paints that is excellent in chemical resistance, scratch resistance and sedimentation stability in addition to matting performance, and to complete the present invention. reached

This invention is as follows.

[1] A hydrophobic silica gel surface-treated with silicone oil,

The pore volume measured by the nitrogen adsorption and desorption method is in the range of 0.6 to 2 ml / g,

The M value is in the range of 5 to 40 vol%, and

The ratio of the pore volume having a pore radius of 109 nm or less after compression to the volume of pores having a pore radius of 109 nm or less before compression at a pressure of 260 MPa (pore volume after compression/pore volume before compression) is in the range of 0.8 to 1.5. Hydrophobic silica gel for pre-curing paint matting.

[2] The hydrophobic silica gel according to [1], wherein the hydrophobic silica gel has a volume average particle diameter D50 value measured by laser diffraction in the range of 5 to 20 µm.

[3] The hydrophobic silica gel according to [1] or [2], wherein the DBA adsorption amount is in the range of 30 to 180 mmol/kg.

[4] The hydrophobic silica gel according to any one of [1] to [3], wherein the hydrophobic silica gel has a maximum particle size in the range of 15 to 70 µm as measured by laser diffraction.

[5] The hydrophobic silica gel according to any one of [1] to [4], wherein the ratio of the D90 value to the D50 value measured by the laser diffraction method (D90/D50) is less than 1.8.

According to the present invention, in addition to matting performance, it is possible to provide a hydrophobic silica gel for matting energy ray curable paints having excellent chemical resistance, scratch resistance and sedimentation stability.

1 shows the mercury pore distribution of the hydrophobic silica gel of Example 1.
2 shows the mercury pore distribution of the hydrophobic silica gel of Comparative Example 1.

<Hydrophobic silica gel>

The present invention is a hydrophobic silica gel surface-treated with silicone oil,

(1) the pore volume measured by the nitrogen adsorption and desorption method is in the range of 0.6 to 2 ml / g;

(2) the M value is in the range of 5 to 40 vol%, and

(3) Energy rays in which the ratio of the pore volume of 109 nm or less after compression to the pore volume of 109 nm or less before compression at a pressure of 260 MPa (pore volume after compression/pore volume before compression) is in the range of 0.8 to 1.5 It relates to a hydrophobic silica gel for removing gloss of curable paint.

The hydrophobic silica gel of the present invention is a silica whose surface is treated with a silicone oil, and is obtained by treating the surface of the silica gel with a silicone oil. Silica gel is a known silica gel produced by a known method, and the silicone oil for surface treatment may also be a known silicone oil. However, the hydrophobic silica gel having the above characteristics (1) to (3) is a novel hydrophobic silica gel, and by satisfying these physical properties, it can be a silica suitable for matting of energy ray curable paint.

(1) The hydrophobic silica gel of the present invention has a pore volume measured by nitrogen adsorption and desorption in the range of 0.6 to 2 ml/g. By being within this range, excellent matting performance and scratch resistance are exhibited. When the pore volume is smaller than 0.6 ml/g, the pores of the silica are too small, and the matting performance is greatly reduced. When the pore volume increases, the pore size also tends to increase, and when the pore volume exceeds 2 ml/g, the pores become too large, the silica secondary particle aggregation structure weakens, and scratch resistance deteriorates. It is preferably in the range of 0.7 to 1.8 ml/g, more preferably in the range of 0.8 to 1.6 ml/g. The method for measuring the pore volume by the nitrogen adsorption and desorption method will be described in Examples.

(2) The hydrophobic silica gel of the present invention has an M value in the range of 5 to 40 vol%. The method for measuring the M value is explained in Examples, but the M value is an index indicating the degree of hydrophobicity of the hydrophobic silica gel by the methanol concentration of the methanol aqueous solution in which the hydrophobic silica gel can be suspended. When the M value is within this range, that is, when the degree of hydrophobicity is within this range, chemical resistance is excellent compared to the WAX-treated silica described in Patent Literatures 1 and 2, and it is difficult to hardcake and has excellent redispersibility. When the M value is less than 5 vol%, the desired chemical resistance is not obtained, and when the M value exceeds 40 vol%, it tends to precipitate over time, so redispersion becomes difficult. When the M value is 40 vol% or less, the remaining amount of silanol groups is large compared to conventional hydrophobic silica gels having an M value of more than 40 vol%, and aggregation is formed in the paint, so that it is difficult to hardcake. The M value is preferably 10 to 35 vol%, more preferably 15 to 30 vol%.

(3) In the hydrophobic silica gel of the present invention, the ratio of the pore volume of 109 nm or less after compression to the pore volume of 109 nm or less before compression at a pressure of 260 MPa (pore volume after compression/pore volume before compression) is 0.80 to 1.5. When hydrophobic silica gel is compressed by a press machine, the secondary particle aggregation structure of the silica particles collapses depending on the type of silica and compression pressure, and the large pores disappear first. When the hydrophobic silica gel of the present invention is compressed at a pressure of 260 MPa, the ratio of the pore volume of 109 nm or less after compression to the pore volume of 109 nm or less before compression is within the above range. The pore volume of 109 nm or less represents the surface or internal pore structure of the secondary particle aggregate of silica, and the higher the value, the larger the number of voids in the secondary particle aggregate. As the pore volume of silica increases, the density per silica secondary particle decreases, and the number of silica secondary particles per unit weight increases. That is, when the same amount of silica having the same particle diameter is blended into the paint, matting performance increases as the pore volume of the silica increases. On the other hand, as the pore volume increases, the number of contact points between the silica primary particles decreases, so the secondary particle aggregation structure becomes weaker.

By setting the compression pressure to 260 MPa, the strength of the secondary particle aggregation structure constituting the pores of 109 nm or less can be evaluated. The pore volume of 109 nm or less is measured when the pressure is increased from 0 MPa to 400 MPa by the mercury porosimetry. The method for measuring the pore volume of 109 nm or less by the mercury porosimetry method is explained in Examples.

The pore volume ratio before and after compression of 0.8 to 1.5 indicates that the secondary particle aggregation structure of the silica particles is maintained even after compression of 260 MPa and is strong. That is, hydrophobic silica gel having a pore volume ratio of 0.8 to 1.5 before and after compression has excellent scratch resistance. The lower limit of the pore volume ratio before and after compression is preferably 0.85, more preferably 0.9. The upper limit of the pore volume ratio before and after compression is 1.5, and it is practically difficult to provide a hydrophobic silica gel exceeding 1.5. The upper limit of the pore volume ratio before and after compression is preferably 1.4, more preferably 1.3, still more preferably 1.2, and most preferably 1.1.

(4) The hydrophobic silica gel of the present invention preferably has a D50 value in the range of 5 to 20 µm as measured by laser diffraction. When the D50 value measured by the laser diffraction method is in the range of 5 to 20 μm, it is possible to impart a suitable unevenness to the coating film and exhibit matting performance with respect to the film thickness of a general coating film. A method for measuring the volume average particle diameter by laser diffraction is explained in Examples. Hydrophobic silica gel with a D50 value of less than 5 μm tends to have low matting performance, and when it is larger than 20 μm, the surface of the coating film becomes rough and the design is damaged, so it may not be suitable for matting applications.

(5) The hydrophobic silica gel of the present invention preferably has a DBA adsorption amount in the range of 30 to 180 mmol/kg. When the amount of DBA adsorbed is within the above range, it is possible to control precipitation in the paint while improving chemical resistance, which is a characteristic of hydrophobic silica gel. When it is less than 30 mmol/kg, there are few silanol groups on the surface of the hydrophobic silica gel, and since aggregation of silica is not produced, it precipitates and cannot be redispersed. When it is greater than 180 mmol/kg, the hydrophobic state of the hydrophobic silica gel is weak and the effect of improving the chemical resistance is reduced. The amount of DBA adsorbed is preferably 40 to 170 mmol/kg, more preferably 50 to 160 mmol/kg, and still more preferably 60 to 140 mmol/kg.

(6) The hydrophobic silica gel of the present invention preferably has a maximum particle diameter in the range of 15 to 70 µm as measured by laser diffraction. When the maximum particle size is within this range, suitable unevenness can be imparted to the matting coating film. When the maximum particle diameter measured by the laser diffraction method is less than 15 μm, the matting performance tends to be low. When it is larger than 70 μm, the surface of the coating film becomes rough and the design is damaged, so it may not be suitable for matting applications. The maximum particle diameter measured by the laser diffraction method is more preferably in the range of 15 to 65 μm.

(7) The hydrophobic silica gel preferably has a ratio D90/D50 of the D90 value and the D50 value of the particle diameter measured by laser diffraction in a range of less than 1.8. When D90/D50 is in the range of less than 1.8, it has a sharp particle size distribution and the matting performance becomes better. When the ratio D90/D50 of the D90 value and the D50 value of the particle diameter measured by the laser diffraction method is 1.8 or more, the particle diameter is broad and the matting performance is relatively low. More preferably, D90/D50 is in the range of less than 1.7.

<Energy ray curing type paint>

Hydrophobic silica gel is known in fields other than for energy ray curable coating materials. However, since these conventional hydrophobic silica gels have a large particle diameter and strong secondary particle aggregation structure, they precipitate in a relatively short time, especially in paints containing a pharmaceutical solvent having a polar group or a reactive monomer. Therefore, conventional hydrophobic silica gel has not been used for energy ray curable paints.

The energy ray curable paint in the present invention is a paint containing a reactive monomer, an organic solvent and a photopolymerization initiator. Regarding the reactive monomer, the organic solvent, and the photopolymerization initiator, there is no limitation, and known materials may be used. Furthermore, components other than a reactive monomer, an organic solvent, and a photoinitiator can also be contained suitably.

A reactive monomer is, for example, a reactive monomer having a polar group, and as a reactive monomer having a polar group, methyl carbitol acrylate, 2-ethylhexyl acrylate, phenyl acrylate, C9-phenyl acrylate, 1,9-no and nondiol diacrylate, tripropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate.

Organic solvents are representative examples of medicinal solvents having a polar group, such as esters such as ethyl acetate and butyl acetate, alcohols such as ethanol and methanol, ketones such as acetone and methyl ethyl ketone, dimethyl ether, and diethyl and ethers such as ether.

The greatest feature of the present invention is that a favorable precipitated state is maintained even in an energy ray curable coating material by imparting an optimal hydrophobic state to silica particles having a large particle diameter and a strong secondary particle aggregation structure.

The hydrophobic silica gel for matting energy ray curable paints of the present invention is suitably used as a matting agent for energy ray curable paints. Among them, the effect is high in energy ray curing type paints containing low viscosity and easily precipitated weak solvents, but it is not limited thereto.

<Silicone Oil>

The silicone oil for surface treatment for the hydrophobic silica gel of the present invention is not particularly limited as long as it can be mixed with silica gel. It is common to use commercially available dimethyl silicone oil (common name: straight silicone oil) having only methyl groups and phenyl groups, but other modified silicone oils having organic substituents on silicon atoms can also be used. Examples of substituents include polyethers, epoxies, amines, and carboxyl groups, and many modified silicone oils are commercially available. As a modified type silicone oil, the following products are mentioned, for example.

<Modified silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.>

KF-868, 865, 859, 393, 250, 889, 2001, 2004, 99, 9901, 8010, 8012, 8008, 105, 6000, 6001, 6002, 6003, 6123, 2200, 9701, 05, 801, 801, 8012 858, 351A, 353, 354L, 355A, 945, 640, 642, 643, 644, 6020, 6204, 6011, 6015, 6017, 412, 413, 414, 4003, 4917, 7235B, 50, 55, 4SS X-22-343, 2000, 2046, 4741, 4039, 4015, 161A, 161B, 9490, 163, 163A, 163B, 163C, 169AS, 169B, 164, 164AS, 164A, 164B, 164C, 4 1652E, 4 1654E 167b, 167c, 162c, 5841, 2445, 1602, 168AS, 168A, 168B, 173BX, 173dx, 170bx, 170dx, 176dx, 176GX, 174ASX, 174BX, 2426, 2475, 3710, 2516, 821, 822, 7322 3265

<Modified silicone oil manufactured by Tore Dow Corning>

SF 8417, BY 16-205, BY 16-213, BY 16-871, BY 16-893, SF 8411, BY 16-880, SF 8427, BY 16-201, SF 8428, BY 16-846, SF 8419, FS 1265, SH 510, SH 550, SH 710, SH 8400, FZ-77, L-7604

<Modified silicone oil manufactured by Momentive Performance Materials>

TSF4440, 4441, 4445, 4446, 4452, 4460, 4700, 4701, XF42-B0970

<Modified silicone oil manufactured by Wacker Chemie AG>

L03, 033, 066, L653, 655, 656, 662, WT1250, 65000VP, AP100, 150, 200, 500, AR20, 200

When a silicone oil having a high viscosity is used, it is necessary to dilute it with a solvent or the like, so a silicone oil having a kinematic viscosity of about 1 to 500 centistokes (St) is generally suitably used. Silicone oils having a kinematic viscosity of 1 to 500 centistokes (St) include, for example, the following products.

<Silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.>

KF-96-1cs, 1.5cs, 2.0cs, 5.0cs, 10cs, 20cs, 30cs, 50cs, 100cs, 200cs, 300cs, 350cs, 500cs

<Silicone oil manufactured by Tore Dow Corning>

SH200-1cs, 1.5cs, 2cs, 3cs, 5cs, 10cs, 20cs, 50cs, 100cs, 200cs, 350cs, 500cs

<Silicone oil manufactured by Momentive Performance Materials Japan>

TSF451-5A, 10, 20, 30, 50, 100, 200, 300, 350, 500

<Silicone oil manufactured by Wacker Chemistry>

AK 1, 10, 35, 50, 100, 350, 500

<Silica gel>

The manufacturing method of the raw material silica gel of the hydrophobic silica gel of this invention is demonstrated. The pore structure of the silica gel used in the present invention is controlled by a process of preparing silica gel by drying the silica hydrogel in order to provide a hydrophobic silica gel having a desired pore volume and pore volume after compression/pore volume before compression. First, the silica hydrogel used in the production method of the present invention may be obtained by a conventional method. That is, an aqueous solution of an alkali metal silicate salt such as sodium silicate, potassium silicate, or lithium silicate is reacted with a mineral acid such as sulfuric acid, hydrochloric acid, or nitric acid in an acid excess to obtain a uniform silica hydrosol. Then, after gelation of the obtained silica hydrosol, it is pulverized and washed with water. In the water washing step, a hydrothermal treatment may be performed by adding and heating sodium hydroxide or an aqueous ammonia solution for the purpose of removing by-product salts and, if necessary, lowering the specific surface area.

For drying, a stationary dryer, a band dryer, a paddle dryer, a fluidized dryer, etc. are generally used, but it is not limited thereto. The drying temperature is not particularly limited, but when performing uniform drying at an average drying rate within the above range, it is appropriate to perform at 100 to 300°C.

The drying of the silica hydrogel is performed in consideration of the viewpoint of controlling the pore structure to provide a hydrophobic silica gel having a desired pore volume and pore volume after compression/pore volume before compression. From this point of view, it is preferable to dry the silica hydrogel by using a dryer capable of controlling the drying speed represented by a stationary dryer or a fluidized dryer to obtain silica gel. The moisture content of the silica gel after drying is suitably in the range of, for example, 3 to 10% (based on mass).

The silica gel obtained in this way can be pulverized and classified for the purpose of further adjusting the average particle diameter. Grinding can be performed by a known method, for example, a method using a roll mill, a ball mill, a hammer mill, a pin mill, a jet mill, or the like. In addition, the silica gel having a desired average particle diameter can be obtained by performing the classification using an air classifier such as a micron separator or a centrifugal classifier. At this time, although it is not necessary to match the target average particle size, by bringing it close to the target particle size, the particle size control after hydrophobization becomes easy.

As a method for surface treatment of silica gel with a surface treatment agent for obtaining the hydrophobic silica gel for matting of energy ray curable paint of the present invention, a method using a high-speed flow mixer such as a Henschel mixer is preferable for uniform treatment. However, it is not limited to this method. The amount of the surface treatment agent used for the treatment of silica gel is adjusted so that a desired M value is obtained. In addition, also for adjusting the amount of DBA adsorbed, the amount of the surface treatment agent used for treating the silica gel is adjusted.

After mixing the surface treatment agent and silica gel, hydrophobicity is performed by heat treatment under conditions of 200 to 600°C. The method of heat treatment is not limited as long as it can perform uniform heat treatment for a certain period of time. As the heat treatment time, a desired hydrophobized state may be obtained, but 1 to 24 hours are exemplified as a target. After the heat treatment, grinding and classification may be performed if necessary.

[Example]

Hereinafter, the present invention will be described in more detail based on examples. However, the examples are examples of the present invention, and the present invention is not intended to be limited to the examples.

How to measure physical properties

M value

A mixed solution with water in which the concentration of methanol was changed at intervals of 5 vol% was prepared, and 5 ml of this solution was put into a test tube having a volume of 10 ml. Next, 0.1 to 0.2 g of a hydrophobic silica gel sample, which is a test powder, is put, shaken, and then the minimum methanol concentration at which the powder is suspended is observed, and this is referred to as M value.

DBA adsorption amount

A dry sample of 250 mg of the hydrophobic silica gel sample is precisely weighed, to which 50 ml of a N/500 di-n-butylamine solution (petroleum benzine solvent) is added, and allowed to stand at 20° C. for about 2 hours. To 25 ml of this supernatant, 5 ml of chloroform and 2 to 3 drops of indicator (crystal violet) were added, titrated with N/100 perchloric acid solution (acetic anhydride solvent) until purple turned blue, and the titration value at this time was A is called ml.

A blank was separately performed to obtain Bml, and the DBA adsorption amount was calculated by the following formula.

DBA adsorption amount (mmol/kg)=80(B-A)f

Where f is the titer of N/100 perchloric acid solution

Particle diameter (D50 value, D90 value, maximum particle diameter)

Using MicrotracBEL MT-3000II, a laser diffraction particle size distribution analyzer manufactured by MicrotracBEL, 50% of the integrated volume value (D50 value) and 90% of the value from the bottom (D90 value) in the particle size distribution of the hydrophobic silica gel sample and the maximum particle diameter detected (maximum particle diameter) was obtained. In addition, isopropyl alcohol (refractive index: 1.38) was used as a solvent.

Pore volume measured by nitrogen adsorption and desorption method

The total pore volume (V _P ) in the range of pore radius of 1.6 to 100 nm was measured by the Barrett-Joyner-Halenda method (BJH method) using a high-precision gas/vapor adsorption measuring device Belsorp max manufactured by Nippon Bell Co., Ltd. In addition, the measurement result is the pore volume (measured from the larger pore volume side) on the desorption side.

Pore volume measured by mercury porosimetry

Using a mercury porosimeter PASCAL440 manufactured by Thermo, the pressure was increased from 0 MPa to 400 MPa, and the pore volume was measured. The pressure and mercury introduction are measured and the respective values are output. The contact angle between mercury and silica was 140°. The pore volume with a pore radius of 109 nm or less was determined by the mercury porosimetry under these measurement conditions.

Sample preparation for mercury pore volume measurement (compression by press)

A briquetting press manufactured by MAEKAWA TESTING MACHINE MFG. Co., Ltd. was used.

Compression method by press machine

About 2 g of the hydrophobic silica gel sample was packed in a 40 mm diameter die, and a load of about 5 t was applied with a hydraulic press to perform pre-compression. The precompressed sample is taken out of the die and lightly ground in a mortar and pestle. A 31 mm diameter polyvinyl chloride frame was packed with the pulverized sample, a load of 20 t was applied and compressed for 10 seconds, and a hydrophobic silica gel sample after compression was obtained.

Film preparation method (UV paint test)

Table 1 shows the composition table of UV paints.

combination

Oligomer: NK oligo UA-1100H manufactured by Shin Nakamura Chemical Industry Co., Ltd.

Monomer: DPHA from Daicel Allnex

Photopolymerization initiator 1: Ormirad 184 manufactured by BASF

Photopolymerization initiator 2: Ormirad TPO H, manufactured by BASF

Leveling agent: BYK-UV-3570, a product of BYK Chemie

Mixer: Labo·Leution, a product of PRIMIX Corporation

Spray gun: Gravity type spray gun W-101-132G from ANEST IWATA Corporation

UV irradiation device: EYE GRANDAGE ECS-4011GX, a product of EYE GRAPHICS Co., LTD.

A mercury lamp was used as a light source.

blending order

(1) Among the formulations, (a) is weighed into a 200 ml disposable cup and mixed at 500 rpm for 5 minutes.

(2) The formulation (b) is weighed and introduced into (a) under stirring at 500 rpm.

(3) When the powder enters the paint, the rotational speed is increased to 1,000 rpm and stirred for 30 minutes.

painting order

(1) Fill the spray gun with the blended paint.

(2) Paint on the ABS resin board (black).

(3) Leave still (setting) at room temperature for 5 minutes.

(4) Dry in an oven at 80°C for 5 minutes.

(5) In a UV irradiation device, UV irradiation was performed twice under conditions of an output power of 2 kw, an irradiation distance of 200 mm, and a conveyor speed of 210 cm/min to cure the product, thereby obtaining a coating film having a coating film thickness of 15 µm.

Gloss value measurement

A gloss meter VG7000 manufactured by Nippon Denshoku Industries Co., Ltd. was used to measure the 60° gloss value. A 60 ° gloss value of 39 or less was judged as excellent, 40 to 49 as good, 50 to 59 as acceptable, and 60 or more as unacceptable.

transparency

By using the L* value of the coating film applied to the ABS board (black) using a spectrophotometer CM-5 manufactured by Konica Minolta, 13 or less is excellent, 13 or more and 15 or less is good, 15 or more and 18 or less are acceptable, Anything over 18 was considered unacceptable.

abrasion test

Using the Hakjin-style friction fastness tester AB-301 manufactured by Tester Industrial Co., Ltd., the state of the coating film after 5000 reciprocations was observed using a canvas No. 6 with a weight of 500 g. The Rz value (10-point average surface roughness) of the surface of the coating film before and after the abrasion test was measured at a magnification of 50 times using a VK8500 ultra-depth shape measuring microscope manufactured by Keyence. The Rz values before and after the abrasion test were measured at each of three locations, and the average difference in Rz was designated as |ΔRz|. It was judged that the smaller the difference (|ΔRz|) before and after the abrasion test, the less damage occurred, and it was judged that 0.5 or less was excellent, 0.5 and 1 or less was good, 1 and 1.5 or less was acceptable, and more than 1.5 was judged to be unacceptable.

chemical resistance

The state of the coating film after 2 hours of immersion in 5% NaOH was observed.

color difference measurement

ΔE of the coating film before and after the chemical resistance test was measured using a spectrophotometer CM-5 manufactured by Konica Minolta. The calculation formula of ΔE is shown in Equation 1.

The smaller the ΔE, the better the chemical resistance. 4.0 or less was judged acceptable, 4.0 to 3.5 or less was judged good, and 3.5 to 3 or less was judged to be excellent.

[Equation 1]

Redispersibility test

2 g of a hydrophobic silica gel sample was blended with 50 g of a solvent of ethyl acetate: toluene = 1:1, and 50 ml of the sample was placed in a 50 ml measuring cylinder and allowed to stand. After 30 minutes, redispersion was performed by inverting up and down at a rate of once per second, and the number of times required for the precipitate to be redispersed was measured. 10 times or less was excellent, 11 times or more and 30 times or less were good, 31 times or more and 50 times or less were acceptable, and those exceeding 50 times were made impossible.

Preparation of raw material silica gel

Sodium silicate (SiO ₂ concentration: 25 wt%, SiO ₂ /Na ₂ O molar ratio: 3.3) and sulfuric acid (H ₂ SO ₄ 2 wt%) are combined with sodium silicate at a flow rate of about 15 L/min and sulfuric acid in a silica hydrosol under conditions such that the excess sulfuric acid amount is 6 wt%. was mixed using a mixing nozzle to obtain a silica hydrosol. This hydrosol was subjected to hydrothermal treatment at pH 7.0 at 90°C for 3 to 5 hours, then washed with water, dried, and pulverized to obtain a BET specific surface area of 470 to 530 m/g and a D50 value of 10.4 measured by laser diffraction. to 15.1 μm of silica gel was obtained.

Example 1

Using silica gel having a BET specific surface area of 500 m2/g and a D50 value of 14.5 μm measured by laser diffraction method as the raw material silica, silicone oil (KF96-50cs manufactured by Shin-Etsu Chemical Co., Ltd.) was mixed with a BET specific surface area of 3.0 m/g based on 100 m2/g. It was added in such a way that it was added and homogenized by performing mixing for 10 minutes with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.). After mixing, the mixture was filled into a ceramic cluster having an internal volume of 10,000 cm 3 , and heat treatment was performed at 320° C. for 8 hours in a continuous heating furnace to obtain hydrophobic silica gel.

Example 2

Using silica gel with a BET specific surface area of 530 m2/g and a D50 value of 13.6 µm measured by laser diffraction method as the raw material silica, silicone oil (KF96-50cs manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to a BET specific surface area of 100 m2/g of 3.4 m/g. It was added in such a way that it was added and mixed for 10 minutes with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) to make it homogeneous. After mixing, heat treatment was performed at 350°C for 4 hours in a stationary heating furnace to obtain hydrophobic silica gel.

Example 3

Using silica gel having a BET specific surface area of 470 m2/g and a D50 value of 15.1 µm measured by laser diffraction as the raw material silica, silicone oil (KF96-50cs manufactured by Shin-Etsu Chemical Co., Ltd.) was mixed with a BET specific surface area of 100 m2/g at 3.2 m/g. It was added in such a way that it was added and mixed for 10 minutes with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) to make it homogeneous. After mixing, heat treatment was performed at 380°C for 7 hours in a stationary heating furnace to obtain hydrophobic silica gel.

Example 4

Using silica gel having a BET specific surface area of 490 m2/g and a D50 value of 11.0 µm measured by laser diffraction as the raw material silica, silicone oil (KF96-50cs manufactured by Shin-Etsu Chemical Co., Ltd.) was mixed with a BET specific surface area of 100 m2/g of 3.1 It was added in such a way that it was added and mixed for 10 minutes with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) to make it homogeneous. After mixing, heat treatment was performed at 330°C for 6 hours in a stationary heating furnace to obtain hydrophobic silica gel.

Example 5

Hydrophobic gel silica was obtained in the same manner as in Example 1, using silica gel having a BET specific surface area of 500 m 2 /g and a D50 value of 10.4 μm measured by laser diffraction as the raw material silica. Thereafter, the obtained hydrophobic gel silica was pulverized and classified to adjust the particle size so that the D50 value of the particle size distribution by laser diffraction was 5.8 μm, and a hydrophobic silica gel was obtained.

Table 2 shows the measurement results of Examples 1 to 5. 1 shows the mercury pore volume distribution in Example 1 before compression and after compression.

Reference example 1

A hydrophobic silica gel was obtained by performing the treatment in the same manner as in Example 1 except that silicone oil (KF96-50cs manufactured by Shin-Etsu Chemical Co., Ltd.) was added in an amount of 5.0 parts per 100 m 2 /g of BET specific surface area. A hydrophobic silica gel having a high M value (55 vol%) in terms of large particle diameter was inferior in sedimentation stability.

Reference example 2

Commercial product Nipsil SS-50B (product of Tosoh Silica Co., Ltd.)

Since the particle diameter was small, the sedimentation stability was excellent, but the matting performance was inferior.

Comparative Example 1

Commercial product NIPGEL AY-460 (product of Tosoh Silica Co., Ltd.) WAX treated gel silica

This wax-treated silica was inferior to the hydrophobic silica gel of the present invention in transparency and chemical resistance.

Table 3 shows the measurement results of Reference Example and Comparative Examples 1 and 2. In addition, the mercury pore volume distribution of Comparative Example 1 before compression and after compression is shown in FIG. 2 .

The present invention is useful in the field of hydrophobic silica gel.

Claims (5)

As a hydrophobic silica gel surface-treated with silicone oil,
The pore volume measured by the nitrogen adsorption and desorption method is in the range of 0.6 to 2 ml / g,
The M value is in the range of 5 to 40 vol%, and
The ratio of the pore volume having a pore radius of 109 nm or less after compression to the pore volume of pore radius 109 nm or less before compression at a pressure of 260 MPa (pore volume after compression/pore volume before compression) is in the range of 0.8 to 1.5. Hydrophobic silica gel for pre-curing paint matting. The hydrophobic silica gel according to claim 1, wherein the hydrophobic silica gel has a volume average particle diameter D50 value measured by laser diffraction in the range of 5 to 20 μm. The hydrophobic silica gel according to claim 1 or 2, wherein the hydrophobic silica gel has a DBA adsorption amount in the range of 30 to 180 mmol/kg. The hydrophobic silica gel according to any one of claims 1 to 3, wherein the hydrophobic silica gel has a maximum particle diameter measured by laser diffraction in the range of 15 to 70 μm. The hydrophobic silica gel according to any one of claims 1 to 4, wherein the hydrophobic silica gel has a ratio of a D90 value to a D50 value measured by a laser diffraction method (D90/D50) of less than 1.8.

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