KR100525486B1 - Aqueous ceramic slurry containing acrylic emulsion as a binder agent - Google Patents

Abstract

The present invention relates to the production of a ceramic slurry containing water as a solvent and an aqueous binder, a method for producing a ceramic tape using the same, and a ceramic tape prepared using the same. That is, the present invention is characterized by using water as a solvent and mixing acrylic emulsion and HPMC as a binder, water-based ceramic slurry for mixing them with a glass-alumina composite powder, dispersant, plasticizer and the like and mixing, defoaming, molding drying The present invention relates to a ceramic tape manufacturing method comprising:

Description

Aqueous ceramic slurry containing an acrylic emulsion as a binder {AQUEOUS CERAMIC SLURRY CONTAINING ACRYLIC EMULSION AS A BINDER AGENT}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of water-based ceramic tapes, which are free from environmental pollution, harmless to the working environment and excellent in economic efficiency in the manufacturing process of ceramic substrates for laminated ceramic components, in particular, low temperature co-fired ceramic (LTCC) components. The manufacture of ceramic tapes is divided into aqueous and non-aqueous by the solvent used for tape casting.

Until now, most ceramic tapes have been manufactured by non-aqueous process, which has good volatility, fast drying speed, and easy dispersion of ceramic powder. The problems have been pointed out, and a lot of research and production facilities have been invested in the manufacture of ceramic tapes by water-based processes.

However, the aqueous process has problems such as low binding strength of the aqueous binder, slow drying speed, and difficulty in dispersing the ceramic powder. Thus, there is no clear research and development in the manufacture and lamination process of the ceramic tape. For example, looking at 75 US patents relating to LTCC, most of the patents are related to the lamination method of LTCC plates, the synthesis of ceramic powders, and the application of electrodes to substrates and the related post-treatment, which are described in US Pat. No. 6,147,019. Patents have been filed, but this also relates to a highly volatile non-aqueous solvent. In the manufacture of multilayer ceramic components for LTCC electronic components, there is no state regarding the manufacture of ceramic tapes by water.

Accordingly, the present invention relates to a structure of a ceramic slurry for producing a water-based ceramic tape which is free from environmental pollution and that is harmless to a human body in the manufacturing process of the multilayer ceramic component, in particular, an LTCC component, and to a tape manufacturing method using the slurry. Is a technical challenge. To this end, the present invention provides a water-based ceramic slurry prepared by appropriate mixing of an acrylic emulsion and a cellulose in a water-based binder and control of the composition of other additives, a method of manufacturing a ceramic tape using such a slurry, and a ceramic tape manufactured as such. It aims to do it.

The present invention relates to the preparation of an aqueous ceramic slurry made by mixing an aqueous binder and an additive with a metal oxide powder using water as a solvent and an aqueous ceramic tape using the same. More specifically, the present invention is an aqueous ceramic slurry containing a metal oxide powder, water, a binder, a plasticizer, a dispersant and the like in an appropriate ratio; Mixing process for preparing the ceramic slurry by mixing the metal oxide powder, water, binder, plasticizer, dispersant, etc. in an appropriate ratio, degassing process to remove the bubbles in the mixed slurry and at the same time to obtain the optimum viscosity conditions for tape casting, desorption A water-based ceramic tape manufacturing method comprising a molding step of molding the slurry is completed to a ceramic tape of a constant thickness and a drying step of removing the solvent from the molded ceramic tape; And ceramic tapes prepared therefrom.

First, the present invention provides an aqueous ceramic slurry comprising a metal oxide powder, water as a solvent, a mixture of an aqueous acrylic emulsion as a binder and HPMC, a plasticizer and a dispersant. More specifically, the aqueous ceramic slurry of the present invention is 0.1 to 3.0 parts by weight of dispersant, 15 to 50 parts by weight of water, 5 to 20 parts by weight of binder and 3 to 15 parts by weight of metal oxide powder and 100 parts by weight of the metal oxide powder. Plasticizers.

The present invention also provides a method of making an aqueous ceramic tape using water as a solvent and using an aqueous binder. Manufacturing method according to the invention,

(a) A ceramic slurry is prepared by mixing 0.1 to 3.0 parts by weight of a dispersant, 15 to 50 parts by weight of water, 5 to 20 parts by weight of a binder, and 3 to 15 parts by weight of a plasticizer, based on 100 parts by weight of the metal oxide powder and the metal oxide powder. Mixing process,

(b) a ball-defoaming process of the prepared ceramic slurry, followed by stirring at a constant speed in a vacuum atmosphere to remove residual bubbles in the slurry and to reach the slurry at an appropriate viscosity; and

(c) forming the degassed slurry into a sheet of constant thickness.

Hereinafter, the components of the ceramic slurry according to the present invention will be described in detail.

Metal oxide

In the present invention, the metal oxide used for the manufacture of the LTCC ceramic tape may be a mixed powder in which a glass powder and alumina composed of B ₂ O ₃ and SiO ₂ are mixed. At this time, the average particle diameter of the mixed powder is preferably 1.8 ㎛ or 2.4 ㎛. In addition, the mixing ratio of the mixed powder is preferably 30:70 to 60:40 (glass powder: alumina) in weight ratio.

Dispersant

The dispersing agent suppresses agglomeration of the powder and evenly disperses the powder in the solvent, when the metal oxide powder is mixed with water, which is a solvent, so that the ceramic tape exhibits uniform characteristics. It serves to enable the manufacture of substrates with excellent properties. In one embodiment of the present invention used as a dispersant polycarboxylic acid (polycarboxylic acid), in addition to ammonium polyacrylate salt (ammonium polyacrylate salt), polymetha-acrylic acid (polymetha-acrylic acid), ether (ether) Aqueous dispersants, such as a system, can be used.

In order to suppress aggregation of the powder and maximize dispersion of the powder, the amount of the dispersant added is preferably 0.1 to 3.0 parts by weight based on 100 parts by weight of the metal oxide. If the amount of the dispersant added is less than this, dispersing of the metal oxide is not easy. If the amount of the dispersant is larger than this, it is not preferable because aggregation of the powder by the dispersant occurs.

Binder

The binder binds the particles of the metal oxide, improves the physical strength of the molded ceramic tape, and serves to prevent cracking and warping of the ceramic tape occurring after the molding and drying processes. Typically, a binder of vinyl, cellulose, acrylic, or the like is used alone or in combination to prepare an aqueous ceramic slurry. In the present invention, an acrylic acrylic binder (acrylic emulsion) in the emulsion state and HPMC (Hydroxypropylmethyl cellulose) in the cellulose binder may be mixed and used as the binder. By using the acrylic emulsion, problems such as slow drying speed when using other aqueous binders and deterioration of physical properties of the ceramic tape due to the atmosphere can be solved.The emulsion state is excellent in the process having low viscosity, and the glass transition temperature ( Low Tg) can improve the flexibility and adhesion of ceramic tapes (see A. Kristoffeersson and E. Roncari, and C. Galassi, "Comparison of Different Binder for Water-based Tape Casting of Alumina" J. Eur. Ceram. Soc ., 18, 2123-31 (1998).

However, in particular, in order to manufacture the ceramic tape for LTCC, the thickness of the ceramic tape should be 100 μm or less. When only the acrylic binder is used alone, the thickness of the ceramic tape can be controlled only to 350 μm or more. Therefore, in the manufacture of the LTCC ceramic tape, it is impossible to mold the ceramic tape to a thickness of 350 µm or less by using only the acrylic binder, and thus it is impossible to manufacture the ceramic tape for the LTCC substrate. In order to compensate for this problem, when cellulose-based HPMC is additionally mixed as a binder when the ceramic slurry is mixed, the cellulose-based binder serves as a thickness regulator in the manufacture of the ceramic tape (see: Federation of Societies for Coating Technology). , Surface Coatings Technology; pp. 268-329.The Educational Source for the Coating Industry, 1997). However, the cellulose type has a very low binding force and high viscosity, making it difficult to use a single agent or a large amount of mixed agent in the manufacture of ceramic tapes. Therefore, when the acrylic binder and the cellulose binder are mixed in an appropriate ratio, it is possible to form a ceramic tape for LTCC of 100 μm or less, and a ceramic slurry capable of manufacturing a ceramic tape that maintains adhesiveness and flexibility to perform a lamination process. Can be obtained.

In the present invention, the amount of the binder added is preferably 5 to 20 parts by weight based on 100 parts by weight of the metal oxide. If the amount of the binder added is less than this, the bonding strength of the metal oxide is low, so that the manufacturing process after drying is difficult. If the amount of the binder is more than this, the physical properties of the binder are reduced due to the excess binder after sintering.

In the binder in which the acrylic emulsion and HPMC are used in the present invention, the mixing ratio (acrylic emulsion: HPMC) of the acrylic emulsion and HPMC is preferably 45:55 to 65:35 by weight. When the HPMC is 35 or less, as described above, the molding of the ceramic tape becomes impossible, and when the acrylic binder is 45 or less, the bonding strength of the tape is low, which makes it difficult to form the tape.

The acrylic emulsion used in the present invention preferably has a solid body fraction of 60% or more by weight and a glass transition temperature (Tg) of -16 to -22 ° C in water as a solvent. When the glass transition temperature of the acrylic emulsion is lower than this, the adhesiveness and flexibility of the ceramic tape increase, but the strength decreases rapidly, making it difficult to maintain the shape of the ceramic tape.In the case of higher acrylic adhesives, the adhesiveness and flexibility decrease sharply and the laminated electronic component The manufacture of is difficult and not preferred. In addition, the solid component in the acrylic emulsion is 40 to 70 parts by weight of butyl acrylate (butyl acrylate), 10 to 40 parts by weight of methyl methacrylate (methyl methacrylate), 2-hydroxy ethyl methacrylate (2-hydroxy ethyl methacrylate) It is preferable to include 2 to 10 parts by weight and 10 to 20 parts by weight of methacrylic acid (methacrylic acid).

Plasticizer

In general, the role of plasticizer in ceramic tape casting is to impart flexibility and adhesion of the ceramic tape. In the present invention, a glycol system such as diethylene glycol dibenzoate-dipropylene glycol dibenzonate (diethylene glycol dibenzonate -dipropylene glycol dibenzonate) was used as a plasticizer, and in addition, TEG (tri-ethylene glycol) and PEG (polyethylene glycol) were used. ), Glycerin (glycerine) and the like can be used. The amount of the plasticizer added in the present invention is preferably 3 to 15 parts by weight based on 100 parts by weight of the metal oxide. The reason is that less than this makes it difficult to impart plasticity of the ceramic tape, and more than this reduces the amount of the binder relatively, thereby lowering the bonding strength of the ceramic tape.

menstruum

In preparing a ceramic slurry for producing a ceramic tape, a solvent is required to dissolve organic additives such as binders and plasticizers, and to disperse and mix metal oxide powder particles. In the present invention, purified solvent (distilled water), which has no problem of environmental pollution and is easily obtained, is used as the solvent. In the present invention, the amount of distilled water added is preferably 15 to 50 parts by weight based on 100 parts by weight of the metal oxide. If the amount of solvent is less than this, the dispersion efficiency decreases and the viscosity of the slurry increases, making it difficult to remove bubbles, which increases the possibility that these bubbles remain in the ceramic tape. It is not preferable because aggregation of the oxide powder may occur.

The ceramic tape manufacturing method of the present invention will be described in more detail as follows:

Mixing process

To the metal oxide powder, 0.1 to 3.0 parts by weight of dispersant, 15 to 50 parts by weight of water, 5 to 20 parts by weight of binder and 3 to 15 parts by weight of plasticizer are added and ball milled to mix these components sufficiently. To prepare a ceramic slurry. At this time, the metal oxide, dispersant, binder and plasticizer are as described above.

Defoaming process

Bubbles are generated by the vapor pressure of water caused by friction of air and balls introduced in the ball mill process, which is performed for mixing the components in the mixing process. If the bubbles thus generated are not removed prior to the molding process of the ceramic tape, cracking or warping of the ceramic tape may occur in the drying process, thereby degrading the physical properties of the ceramic tape. Therefore, in order to remove such residual bubbles, after ball milling for 18 hours, 0.1 to 0.5 g of a wax-based or silicon-based antifoaming agent is added to the ceramic slurry prepared in the mixing process under a vacuum atmosphere using a vacuum pump for about 2 hours. Stirring to remove residual bubbles and performing a defoaming process to reach the slurry to an appropriate viscosity. At this time, the ceramic slurry is stirred at a constant speed for uniform defoaming. The stirring speed is preferably in the range of 100 to 400 rpm, more preferably 250 rpm.

During the defoaming process, not only the bubbles in the slurry are removed but also water evaporates and the viscosity of the slurry becomes high. Since the viscosity of the slurry acts as an important factor in the molding process of the ceramic tape, it is important to perform the defoaming process to an appropriate viscosity. In the present invention, the viscosity of the slurry subjected to the defoaming process is preferably 500 to 2000 cps. If the viscosity of the slurry is lower than this, the amount of remaining solvent (water) is large, and the surface tension of the water causes the shrinkage of the ceramic tape during the drying process after the forming process, and it becomes difficult to control to the desired thickness. It is not preferable because it prevents the residual bubbles from escaping during the drying process after the process, thereby deteriorating the physical properties of the ceramic tape.

Molding process

The ceramic slurry having the optimum viscosity through the above defoaming process is molded into a ceramic tape using a doctor blade device. The thickness of the ceramic tape is controlled by using primary and secondary micrometers attached to the blade device, and in order to be used as the LTCC substrate, it is preferable to adjust the thickness in the range of 20 to 200 μm. For this purpose, it is preferable that the blade height at the shaping | molding process shall be 50-300 micrometers, and the casting speed shall be 10-50 cm / min. The manufacture of the ceramic tape of the present invention is not limited to the doctor blade method, and in addition, it can be manufactured using any known tape manufacturing technique such as a tape coater, a roll compaction, an extrusion molding method, or the like.

The present invention also provides a ceramic slurry for producing the ceramic tape or a ceramic tape manufactured using the ceramic tape manufacturing method. The ceramic tape may be used for manufacturing the substrate for LTCC, preferably having a thickness in the range of 20 ~ 200 ㎛.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

Example 1

Preparation of LTCC Ceramic Tape Using Metal Oxide Powder with Average Particle Diameter of 2,4 ㎛

LTCC glass-alumina powder (BS-003L, Nihon Yamamura Glass, Japan) with an average particle diameter of 2.4 µm was added to the alumina ball mill by adding dicarboxylic water as a solvent and polycarboxylic acid as a dispersant, and ball milling at 130 rpm at room temperature for 4 hours. Then, 55 parts by weight of HPMC and butyl acrylate as a binder, a diethylene glycol dibenzoate-dipropylene glycol dibenzoate mixture (Benzoflex 50, Velsicol Chemical Corp., USA) as a plasticizer, methyl methacrylate (Methyl methacrylate) ball mill for 1 hour at each stage by adding an acrylic emulsion containing 25 parts by weight, 5 parts by weight of 2-hydroxy ethyl methacrylate and 15 parts by weight of methacrylic acid Was added to prepare a slurry. When adding the binder, HPMC was added first, followed by acrylic emulsion. The composition of the ceramic slurry thus prepared is shown in Table 1.

ingredient Amount (g) Glass-alumina powder 100 Dispersant 0.25 water 19 Binder (Acrylic Emulsion) 5.23 Binder (HPMC) 5.23 Plasticizer 4.48

After the mixing is completed, a defoaming process was performed by stirring the slurry at a constant speed of 250 rpm to remove bubbles introduced or generated in the ceramic slurry with a vacuum pump and to remove the solvent to maintain the viscosity required for molding. The ceramic slurry subjected to the defoaming process as described above had a viscosity of 1500 cps, which was formed into a ceramic tape for LTCC by controlling blade height and casting speed using a doctor blade device.

The viscosity and molding conditions of the ceramic slurry subjected to the defoaming process are shown in Table 2.

Casting speed (cm / min) 30 Blade height (㎛) 100 Viscosity (cps) 1500

Example 2

Manufacture of Ceramic Tape for LTCC Using Metal Oxide Powder with an Average Particle Diameter of 1.8 ㎛

To the glass-alumina powder for LTCC (TCL-K6A, ThinkCera, Korea) with an average particle diameter of 1.8 µm, distilled water as a solvent and polycarboxylic acid as a dispersant were added to an alumina ball mill and ball milled at 130 rpm at room temperature for 4 hours. , Diethylene glycol dibenzoate-dipropylene glycol dibenzoate mixture (Benzoflex 50, Velsicol Chemical Corp., USA) as a plasticizer and 55 parts by weight of HPMC and butylacrylate as binders, 25 parts by weight of methyl methacrylate, 2- An acrylic emulsion in which 5 parts by weight of ethyl methacrylate and 15 parts by weight of methacrylic acid was mixed was added sequentially, and a ball mill was added for 1 hour for each step to prepare a ceramic slurry. The composition of the slurry thus prepared is shown in Table 3.

ingredient Amount (g) Glass-alumina powder 100 Dispersant 0.4 water 40 Binder (Acrylic Emulsion) 5.7 Binder (HPMC) 5.7 Plasticizer 4.88

After the mixing was completed, the degassing process was performed by stirring the slurry at a constant speed of 250 rpm in order to maintain the viscosity required for molding by removing the solvent by removing a bubble inlet or generated in the vacuum pump. The ceramic slurry subjected to the defoaming process as described above had a viscosity of 1000 cps, which was formed into a ceramic tape for LTCC by controlling blade height and casting speed using a doctor blade device.

The viscosity and molding conditions of the slurry after degassing are shown in Table 4.

Casting speed (cm / min) 30 Blade height (㎛) 100 Viscosity (cps) 1000

BACKGROUND OF THE INVENTION Field of the Invention In the manufacture of multilayered electronic components, in particular, ceramic tapes for the manufacture of substrates for LTCC, environmental pollution, hazard of working environment, recovery facilities by non-aqueous solvents by use of non-aqueous solvents and non-aqueous binders The present invention relates to a method for producing a ceramic slurry using water as a solvent, which can solve problems such as an increase in investment cost, and an aqueous binder, and a method of manufacturing a ceramic tape using the same. As described above, the present invention relates to the production of a slurry for producing a water-based ceramic tape using water as a solvent, which is environmentally friendly, free from risk of contamination, and innocuous in the working environment, in the manufacture of multilayer electronic material components, in particular, ceramic tape for LTCC. By providing the tape casting method using the same, it is possible to replace the manufacturing process by the conventional non-aqueous process. Therefore, by replacing the non-aqueous binder, which depends on the total amount of imports, with domestic aqueous acrylic binder, the binder can be applied to the production of other three-dimensional products as well as the effect of inhibiting the import.

Claims (17)

A ceramic slurry comprising 0.1 to 3.0 parts by weight of a dispersant, 15 to 50 parts by weight of water, 5 to 20 parts by weight of an aqueous binder and 3 to 15 parts by weight of a plasticizer, based on 100 parts by weight of the metal oxide powder and the metal oxide powder. The metal oxide powder is a mixed powder of alumina and a glass powder composed of B ₂ O ₃ and SiO ₂ , The dispersant is selected from the group consisting of polycarboxylic acid (polycarboxylic acid), polyacrylate salt (ammonium polyacrylate salt), polymetha-acrylic acid and an ether system, The aqueous binder is a mixture of acrylic emulsion and HPMC (Hydroxypropylmethyl cellulose), The plasticizer is selected from the group consisting of diethylene glycol dibenzonate-dipropylene glycol dibenzonate (TE), tri-ethylene glycol (TEG), polyethylene glycol (PEG) and glycerin (glycerine) sign, Water-based ceramic slurry. The ceramic slurry according to claim 1, wherein the metal oxide powder is mixed with a glass powder composed of B ₂ O ₃ and SiO ₂ and alumina in a mixing ratio of 30:70 to 60:40 (glass powder weight: alumina weight). delete The ceramic slurry of claim 1, wherein the mixing ratio of the acrylic emulsion and HPMC in the binder is 45:55 to 65:35 (acrylic emulsion: HPMC) by weight. 5. The ceramic slurry of claim 4 wherein the solids fraction of the acrylic emulsion is at least 60% by weight and the glass transition temperature (Tg) is in the range of -16 to -22 ° C. According to claim 5, wherein the solid component in the acrylic emulsion is 40 to 70 parts by weight of butyl acrylate (buthyl acrylate), 10 to 40 parts by weight of methyl methacrylate (methacrylic acid) 10 to 20 parts by weight Parts and 2 to 10 parts by weight of 2-hydroxy ethyl methacrylate. delete delete delete delete delete delete delete delete delete delete delete