JP5715535B2 - Binder composition for firing - Google Patents

Description

  The present invention relates to a binder for firing used to form a sintered body of inorganic powder.

  Binders for firing used to form a sintered body of inorganic powder are conventionally used in various fields, such as electrodes, conductor wiring, and multilayer capacitors in various electronic devices. (See Patent Document 1).

  A mixture (baking paste) of such a binder for baking and an appropriate inorganic powder is applied, followed by preheating if necessary to remove the binder, and further baking to burn the inorganic powder. As a result, appropriate elements as described above are produced.

  As such a binder for baking, ethyl cellulose is widely used. Ethyl cellulose has favorable properties as a binder for a paste for baking, such as good applicability and easy removal by thermal decomposition.

  However, there are problems that ethyl cellulose is expensive to obtain and is uneasy to supply because it is a plant-derived component. For this reason, a binder that replaces ethyl cellulose is being demanded.

  One of the binder candidates that can replace such ethyl cellulose is an acrylic polymer.

  However, there is a problem in compatibility between the acrylic polymer and ethyl cellulose, and therefore there is a problem that the storage stability of the binder composition containing these and the baking paste containing this binder is poor. On the other hand, when only an acrylic polymer is used as a binder, there arises a problem that the applicability of the baking paste is deteriorated.

JP 2006-160791 A

  The present invention has been made in view of the above-mentioned reasons, and provides a binder composition for firing having good coating properties and excellent storage stability while containing an acrylic polymer and ethyl cellulose as a binder. With the goal.

The binder composition for baking according to the present invention contains ethyl cellulose and an acrylic polymer,
The acrylic polymer is synthesized by polymerization of an acrylic monomer in the presence of the ethyl cellulose,
The acrylic monomer contains a monofunctional acrylic monomer and a polyfunctional acrylic monomer.

In firing the binder composition according to the present invention, the proportion of the polyfunctional acrylic monomer with respect to the total acrylic monomers, area by der of 0.1 to 5 mass%.

In firing the binder composition according to the present invention, with the acrylic polymer and the cellulose, the former pair latter weight ratio of from 9: 1 to 1: 9 area by der of.

  In the binder composition for firing according to the present invention, it is preferable that the monofunctional acrylic monomer contains methyl methacrylate and 2-ethylhexyl methacrylate.

  ADVANTAGE OF THE INVENTION According to this invention, the binder composition for baking which has favorable applicability | paintability and is excellent in storage stability is obtained, containing an acrylic polymer and ethylcellulose as a binder.

  The binder composition for baking by this embodiment is a composition which functions as a binder in the paste for baking, and contains ethyl cellulose and an acrylic polymer.

  Although it does not specifically limit as ethylcellulose, For example, the product names Etcelle STD-7, STD-20, STD-45, STD-100 etc. by Dow Chemical Company are used individually or in combination of 2 or more types. .

  The acrylic polymer is synthesized by polymerization of an acrylic monomer in the presence of ethyl cellulose. Further, the acrylic monomer contains a monofunctional acrylic monomer having only one ethylenically unsaturated bond per molecule and a polyfunctional acrylic monomer having a plurality of ethylenically unsaturated bonds per molecule.

  The monofunctional acrylic monomer is not particularly limited. For example, methyl methacrylate, hydroxyethyl methacrylate, butyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, ethyl methacrylate, glycerin monomethacrylate, 2-hydroxypropyl Methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 1,4-cyclohexanedimethanol monoacrylate, 2-hydroxy-2-methylpropyl methacrylate, polypropylene glycol monomethacrylate (n≈4 to 13), etc. Or two or more types are used in combination.

  The monofunctional acrylic monomer in the baking binder composition preferably contains at least one of methyl methacrylate, 2-ethylhexyl methacrylate, and a hydroxyl group-containing monomer. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl methacrylate and glycerin monomethacrylate. In these cases, the compatibility between the acrylic polymer and ethyl cellulose is particularly improved. Further, the monofunctional acrylic monomer is preferably composed of methyl methacrylate and 2-ethylhexyl methacrylate. In this case, the ratio of methyl methacrylate to 2-ethylhexyl methacrylate is preferably in the range of 6: 4 to 4: 6. In this case, the compatibility between the acrylic polymer and ethyl cellulose is further improved. Moreover, the smoothness of the coating film formed when the paste containing the binder composition for baking is applied is increased.

  The polyfunctional acrylic monomer is not particularly limited. For example, polyethylene glycol dimethacrylate (n≈2-13), polyethylene glycol diacrylate (n≈2-13), polypropylene glycol dimethacrylate (n≈2-13), Trimethylolpropane triacrylate, glycerin propoxytriacrylate, ethylene oxide modified bisphenol A dimethacrylate (m + n≈4-18), propylene oxide modified bisphenol A dimethacrylate (m + n≈4-18), ethylene oxide modified bisphenol A diacrylate (m + n≈4) To 18), ethylene oxide modified bisphenol F diacrylate (m + n≈4 to 18), propylene oxide modified bisphenol A diacrylate (m + n≈4 to 8), pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, glycerol dimethacrylate and the like, alone or in combination of two or more, is used.

  The ratio of the polyfunctional acrylic monomer to the entire acrylic monomer in the binder composition for baking is preferably 0.01% by mass or more, and particularly preferably in the range of 0.1 to 5% by mass. This ratio is preferably in the range of 0.2 to 3% by mass. Thus, when the ratio of the polyfunctional acrylic monomer is 0.1% by mass or more, the compatibility between the acrylic polymer and ethyl cellulose is particularly improved, and when the ratio is 0.2% by mass or more, the compatibility is achieved. Is further improved. Moreover, the applicability | paintability of the baking paste containing the binder composition for baking is improved especially that the ratio of a polyfunctional acrylic monomer is 5 mass% or less.

  The acrylic polymer blended in the firing binder composition is synthesized by the polymerization of the acrylic monomer in the presence of ethyl cellulose blended in the firing binder composition. That is, after the acrylic polymer is synthesized, the ethyl cellulose used for the synthesis of the acrylic polymer becomes a component constituting the binder composition for baking together with the acrylic polymer.

  The amount of ethyl cellulose used is not particularly limited, but from the viewpoint of improving the storage stability and coating properties of the binder composition for baking, the mass ratio of the former to the latter of the acrylic polymer and ethyl cellulose is from 9: 1 to 1. : 9 is preferable, and the mass ratio is more preferably 7: 3 to 5: 5.

  The acrylic monomer is polymerized by an appropriate polymerization method such as solution polymerization. Examples of the solution polymerization method include a method in which an acrylic monomer is heated and stirred in a suitable solvent in a nitrogen atmosphere in the presence of a polymerization initiator.

  A wide variety of solvents can be used as the solvent as long as both the acrylic monomer and ethyl cellulose can be dissolved or dispersed. Examples of the solvent include, but are not limited to, for example, phenylpropylene glycol, phenyl glycol, texanol, benzyl alcohol, phenyl diglycol, terpineol, dihydroterpineol, dihydroterpinyl acetate, cyclohexanone, cyclopentanone, ethylene glycol, 1,4- Butanediol, diethylene glycol, tetraethylene glycol, 1,3-butylene glycol, dipropylene glycol, tripropylene glycol, octanediol, 2,4-diethyl-1,5-pentanediol, diethylene glycol monobutyl ether, butyl carbitol acetate, etc. , Alone or in combination of two or more.

  The polymerization initiator is not particularly limited. For example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,4 Azo compounds such as (dimethyl-4-methoxyvaleronitrile); 4-dichlorobenzoyl peroxide, t-butyl peroxypivalate, o-methylbenzoyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide, Octanoyl peroxide, t-butylperoxy-2-ethylhexanoate, cyclohexanone peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, lauroyl peroxide, diisopropylbenzene hydroperoxide, t-butyl hydroperoxide Oxide, organic peroxides such as di -t- butyl peroxide and the like, alone, or two or more kinds in combination, may be used.

  From the viewpoint of controlling the molecular weight of the acrylic polymer, the polymerization of the acrylic monomer is preferably performed in the presence of an appropriate chain transfer agent. In addition, the use of a chain transfer agent contributes to maintaining good coating properties and thermal decomposability of the binder composition. This is presumed to be because the crosslink density of the polyfunctional acrylic monomer is appropriately adjusted by the chain transfer effect of the chain transfer agent, thereby suppressing the excess of crosslinking points in the acrylic polymer. Is done. The chain transfer agent is not particularly limited. For example, n-dodecyl mercaptan, 2,4-diphenyl-4-methyl-1-pentene, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid 2- Ethylhexyl, 2,3-dimercapto-1-propanol, etc. may be used alone or in combination of two or more.

  As described above, the acrylic monomer is polymerized in the presence of ethyl cellulose to obtain a mixture containing the acrylic polymer and ethyl cellulose. It is preferable that the weight average molecular weight of resin which combined the acrylic polymer and ethyl cellulose in such a mixture is the range of 5000-200000. Thus, when the weight average molecular weight of the resin is 5000 or more, the applicability of the baking binder composition and baking paste is particularly good, and the phase separation of the baking binder composition is further less likely to occur. The storage stability of the binder composition for use is further improved. In addition, when the weight average molecular weight is 200,000 or less, good compatibility between the acrylic polymer and ethyl cellulose is maintained, and good coatability is ensured. The weight average molecular weight of this resin is a value derived based on the measurement result by gel permeation chromatography. For example, Shodex GPC SYSTEM-21H manufactured by Showa Denko Co., Ltd. is used as a measuring machine, and tetrahydrofuran is used as an eluent. Measured.

  This mixture can be directly used as a binder composition for baking. Or the binder composition for baking can be prepared by adjusting the amount of the solvent in this mixture, or adding various additives as needed.

  This binder composition for baking has good coatability and hardly causes phase separation, and therefore has good storage stability. The reason why the binder composition for firing according to the present embodiment has such an effect is not clear. However, when the acrylic monomer is polymerized in the presence of ethyl cellulose and the polyfunctional acrylic monomer is contained in the acrylic monomer, the acrylic polymer has a structure appropriately entangled with ethyl cellulose, Further, it is presumed that the acrylic polymer is present in the solution so as to spread three-dimensionally so that the structure in which the molecule of the acrylic polymer is not folded becomes difficult. This is presumed that the binder composition for firing according to the present embodiment is one of the causes that the phase separation hardly occurs while maintaining good coatability.

  The viscosity of the binder composition for baking is preferably adjusted to a range of 1000 to 30000 mPa · s. In this case, the applicability of the firing paste containing the firing binder composition is particularly good.

  The binder composition for firing thus obtained has good coating properties as described above, and particularly suppresses the occurrence of a so-called stringing phenomenon in which the composition pulls yarn between the coating film and the applicator during coating. Is done. Moreover, as above-mentioned, the compatibility of an ethyl cellulose and an acrylic polymer becomes high, and both are hard to carry out phase separation, For this reason, the storage stability of the binder composition for baking becomes high. For this reason, the binder composition for baking by this embodiment has the characteristic which is inferior compared with the case where only ethylcellulose is used as a binder.

  The binder composition for baking according to the present embodiment is suitably used for preparing a baking paste. The firing paste contains a firing binder composition and an inorganic powder.

  As the inorganic powder, an appropriate powder according to the application is used. For example, as inorganic powder, gold, silver, copper, nickel, palladium, ITO, alumina, zirconia, titanium oxide, barium titanate, aluminum nitride, silicon nitride, boron nitride, various glass powders, inorganic phosphor, graphite powder, solder Powder etc. are used individually by 1 type or in combination of 2 or more types.

  The ratio of the binder composition for firing and the inorganic powder in the paste for firing maintains the good applicability of the firing paste and the good characteristics of various elements obtained by sintering the firing paste. Thus, although adjusted suitably, it is preferable that the ratio of the inorganic powder with respect to 100 mass parts of binder compositions for baking is the range of 20 mass parts-4000 mass parts, for example.

  When the firing paste is used, the firing paste is first applied on an appropriate object. The application method is not particularly limited, and examples thereof include a screen printing method, a dispensing method, a doctor blade method, and the like. According to this embodiment, the applicability of the baking paste is improved, a coating film having a certain thickness is easily formed, and a so-called stringing phenomenon is less likely to occur during application.

  Subsequently, if necessary, the baking paste is heated to volatilize the solvent in the baking paste, and part or all of the acrylic polymer and ethyl cellulose as the binder are thermally decomposed and removed. The Furthermore, by baking this baking paste, the binder remaining in the baking paste is removed and the inorganic powder is sintered. Thereby, appropriate elements such as electrodes and conductor wirings are formed.

[Example 1-14, Comparative Example 2-10]
A 1 L flask equipped with a stirrer, a cooler, a thermometer, a hot water bath, and a nitrogen gas inlet was prepared. To this flask, add the acrylic monomer and organic solvent shown in component A in the following table, and when using a chain transfer agent, add the chain transfer agent shown in component A in the following table to obtain a solution. Obtained.

  Then, when using ethyl cellulose, the ethyl cellulose shown to A component in the following table | surface was thrown into the obtained solution, and this was dissolved in the solution at 80 degreeC.

  Subsequently, dissolved oxygen in the solution was removed by bubbling the solution with nitrogen gas for 30 minutes.

  Subsequently, a polymerization reaction of the acrylic monomer was started by adding a phenyl propylene glycol solution of a polymerization initiator (2,2-azobisisobutyronitrile) to the solution. During the polymerization reaction, a phenyl propylene glycol solution of a polymerization initiator was additionally added to the solution. The polymerization was terminated after 7 hours from the start of the polymerization.

  The results of measuring the polymerization average molecular weight of the resin in the obtained solution are shown in the following table.

  Then, in the case of Comparative Examples 5-7, the phenylpropylene glycol solution of ethylcellulose shown to the B component in the following table | surface was added to the solution.

  This obtained the binder composition for baking. The resin solid content ratio of the binder for baking is shown in the following table.

[Comparative Example 1]
The mixed solution obtained by preparing ethyl cellulose and an organic solvent shown in the following table and mixing them was used as a binder composition for baking.

[Evaluation test]
The following evaluation test was implemented about the binder composition for baking in each Example and a comparative example. The results are shown in the table below.

1. Solution stability evaluation After preparing the binder composition for baking, this was stored at normal temperature for 4 weeks. Subsequently, the presence or absence of phase separation in the binder composition for firing was confirmed by visually observing the binder composition for firing. As a result, the case where phase separation was observed was evaluated as “◯”, and the case where phase separation was not observed was evaluated as “x”.

2. Application | coating property The binder composition for baking 5g was apply | coated on the glass substrate (dimensions 100 mm x 100 mm x 2 mm) using the 4-sided applicator (the product number No112 made from Dazai Equipment Co., Ltd.). When the coating film formed by this is observed, when the coating film does not show any unevenness or crater traces, “○”, in addition to the coating film showing no unevenness or crater traces, “◎” when a very smooth and uniform coating film is formed, “×” when the binder composition for baking sticks to the applicator, or when defects such as unevenness and crater marks are found on the coating film. ”Was evaluated.

3. Pyrolysis using a differential type differential thermal balance (manufactured by Rigaku Corporation, model number TG8120) while heating the binder composition for firing from room temperature to 500 ° C. at a temperature rising rate of 10 ° C./min. The weight change in the binder composition was measured.

  As a result, the case where the weight reduction amount of the binder composition for baking at the time of 400 ° C. was 95% or more was evaluated as “◯”, and the case where it was less than 95% was evaluated as “X”.

4). Using a 4-side applicator (manufactured by Dazai Equipment Co., Ltd., model No. 112), 5 g of the binder composition for firing was applied onto a glass substrate (dimensions 100 mm × 100 mm × 2 mm). In this case, when the applicator was lifted from the coating film, the time required from the start of the lifting until the stringing between the coating film and the applicator was cut was measured. As a result, the case where it was less than 1 second was evaluated as “◯”, and the case where it was 1 second or longer was evaluated as “x”.

In addition, A component in a table | surface is a component used at the time of superposition | polymerization of an acryl-type monomer, and B component is a component added after superposition | polymerization of an acryl-type monomer. The details of the components shown in the table are as follows.
MMA: methyl methacrylate, IBMA: isobutyl methacrylate, CHMA: cyclohexyl methacrylate, BMA: butyl methacrylate, HEMA: 2-hydroxyethyl methacrylate, EHMA: ethyl hexyl methacrylate, GLM: glycerol monomethacrylate, PDE-400: Polyethylene glycol dimethacrylate (manufactured by Nippon Oil & Fats Co., Ltd., part number Bremma-PDE-400)
M-260: polyethylene glycol diacrylate (manufactured by Toagosei Co., Ltd., product number M-260)
BP-4EA: Ethylene oxide modified bisphenol A diacrylate (manufactured by Kyoeisha Chemical Company, product number BP-4EA)
STD-100: Ethyl cellulose having a weight average molecular weight of about 180,000 (manufactured by Dow Chemical Co., Ltd., trade name Etcell STD-100)
STD-45: Ethyl cellulose having a weight average molecular weight of about 140,000 (manufactured by Dow Chemical Co., Ltd., trade name Etcell STD-45)
STD-7: Ethyl cellulose having a weight average molecular weight of about 60,000 (manufactured by Dow Chemical Co., Ltd., trade name Etcell STD-7)
Thiocalcol 20: n-dodecyl mercaptan, manufactured by Kao Corporation, product number thiocalcol 20

Claims (2)

Containing ethyl cellulose and an acrylic polymer,
The acrylic polymer is synthesized by polymerization of an acrylic monomer in the presence of the ethyl cellulose,
The acrylic monomer contains a monofunctional acrylic monomer and a polyfunctional acrylic monomer ,
The ratio of the polyfunctional acrylic monomer to the entire acrylic monomer is in the range of 0.1 to 5% by mass,
The binder composition for baking , wherein the mass ratio of the former to the latter of the acrylic polymer and the ethyl cellulose is in the range of 9: 1 to 1: 9 . The binder composition for firing according to claim 1, wherein the monofunctional acrylic monomer contains methyl methacrylate and 2-ethylhexyl methacrylate.