JP2018058716A - Borosilicate glass, composite powder material, and composite powder material paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To create a glass that can be sintered at a temperature lower than or equal to 900°C without containing PbO, has low reactivity with an electrode such as an Ag external electrode, and can contribute to improvements in the wear resistance and surface smoothness of a coating layer.SOLUTION: A borosilicate glass according to the present invention is characterized by having a glass composition comprising, in mol%, SiO20-40%, BO25-45%, CaO 3-15%, SrO+BaO+ZnO 5-30%, ZrO0-6%, AlO0-8%, CuO 0-1%, with the molar ratio (SiO+CaO)/(BO+SrO+BaO+ZnO) of higher than 0.50.SELECTED DRAWING: None

Description

  The present invention relates to a borosilicate glass, a composite powder material, and a composite powder material paste. .

  In the thermal printer, for example, by heating the thermal paper while feeding it in one direction, the thermal dye in the thermal layer provided on the thermal paper is colored to form an image.

  The printing unit of the thermal printer includes a thermal print head for heating the thermal paper and a pressure roller for feeding the thermal paper in one direction while pressing the thermal paper toward the thermal print head. The thermal print head has a laminated basic structure in which, for example, a heat storage layer, a line-shaped resistor layer, an electrode layer, a covering layer (protective layer), and the like are formed on a ceramic substrate such as alumina.

The coating layer of the thermal print head is formed for the purpose of protecting the electrode and the resistor from contact with the thermal paper. For example, an Au lead electrode, an Ag external electrode, or the like is formed as an electrode, and a RuO ₂ resistor, for example, is formed as a resistor.

Japanese Patent Publication No. 04-002533 JP 2008-150269 A

  The coating layer is generally formed by firing a powder material (glass powder). And the firing temperature is limited to 900 ° C. or less in order to prevent a situation in which the characteristics of the electrodes and the like are deteriorated. Therefore, the powder material is required to be calcined at a temperature of 900 ° C. or lower.

  The powder material is also required to have low reactivity with the Au lead electrode and the Ag external electrode. If the reactivity with the Au lead electrode or the Ag external electrode is high, the electrode may be disconnected after firing.

  Furthermore, the coating layer of the thermal print head repeatedly contacts the thermal paper. Therefore, the powder material is also required to easily produce a coating layer with high wear resistance and surface smoothness.

Conventionally, PbO—SiO ₂ -based glass has been used as a powder material that satisfies these required characteristics (see Patent Document 1).

In recent years, from the viewpoint of environmental protection, reduction of environmentally hazardous substances, for example, reduction of PbO has been promoted, and various lead-free glasses have been proposed in place of PbO—B ₂ O ₃ —SiO ₂ based glass. Yes. For example, Patent Document 2 describes ZnO—B ₂ O ₃ —BaO-based glass.

However, the ZnO—B ₂ O ₃ —BaO-based glass described in Patent Document 2 has a problem of high reactivity with Ag external electrodes and the like.

  Therefore, the present invention has been made in view of the above circumstances, and its technical problem is that it can be fired at a temperature of 900 ° C. or less and does not contain PbO and is reactive with an electrode such as an Ag external electrode. Is to create a glass that is low and that can contribute to the improvement of wear resistance and surface smoothness of the coating layer.

As a result of various experiments, the present inventor has found that the above technical problem can be solved by adopting a predetermined borosilicate glass as the glass system, and proposes the present invention. That is, the borosilicate glass of the present invention has a glass composition of mol%, SiO ₂ 20-40%, B ₂ O ₃ 25-45%, CaO 3-15%, SrO + BaO + ZnO 5-30%, ZrO ₂ 0. It is characterized by containing ˜6%, Al ₂ O ₃ 0-8%, CuO 0-1% and having a molar ratio (SiO ₂ + CaO) / (B ₂ O ₃ + SrO + BaO + ZnO) larger than 0.50. Here, “SrO + BaO + ZnO” is the total amount of SrO, BaO and ZnO. “(SiO ₂ + CaO) / (B ₂ O ₃ + SrO + BaO + ZnO)” indicates a value obtained by dividing the total amount of SiO ₂ and CaO by the total amount of B ₂ O ₃ , SrO, BaO and ZnO.

Borosilicate glass is generally highly reactive with an Ag external electrode. However, in the borosilicate glass of the present invention, the content of SiO ₂ is regulated to 20 mol% or more, the content of B ₂ O ₃ is 45 mol% or less, and the content of CaO is regulated to 3 mol% or more. The reactivity with the Ag external electrode is low.

Further, in the borosilicate glass, when the content of SiO ₂ is large, if the content of SrO, BaO and ZnO is increased, feldspar crystals will precipitate during firing, making it difficult to ensure the desired surface smoothness. There is a case. Therefore, the borosilicate glass of the present invention suppresses precipitation of feldspar crystals by regulating the molar ratio (SiO ₂ + CaO) / (B ₂ O ₃ + SrO + BaO + ZnO) to more than 0.50.

Second, the borosilicate glass of the present invention has a glass composition of mol%, SiO ₂ 25-40%, B ₂ O ₃ 25-40%, CaO 5-15%, SrO 0.1-10%. BaO 0.1 to 10%, ZnO 5 to 15%, ZrO ₂ 0.1 to 4%, Al ₂ O ₃ 0.1 to 7%, CuO 0.005 to 0.09%, molar ratio (SiO ₂ + CaO) / (B ₂ O ₃ + SrO + BaO + ZnO) is 0.55 or more and is preferably used for coating a thermal print head.

Thirdly, borosilicate glass of the present invention has a glass composition, in _{mol%, SiO 2 25~40%, B} 2 O 3 25~40%, CaO 5~15%, SrO 1~10%, BaO 1 to 10%, ZnO 5 to 15%, ZrO ₂ 0.5 to 4%, Al ₂ O ₃ 1 to 7%, CuO 0.01 to 0.09%, molar ratio (SiO ₂ + CaO) / (B ₂ O ₃ + SrO + BaO + ZnO) is 0.55 or more and is preferably used for coating a thermal print head.

Fourthly, it is preferable that the borosilicate glass of the present invention does not substantially contain PbO and Bi ₂ O ₃ in the glass composition. Here, “substantially free of PbO” means that PbO is allowed to be mixed in at an impurity level, but avoids aggressive introduction. Specifically, the content of PbO in the glass composition Is less than 1000 ppm (less than 0.1 mol%). Further, "substantially does not contain Bi ₂ O _3" and, although allowing incorporation of Bi ₂ O ₃ at an impurity level, it is intended to avoid aggressive introduced, in particular glass composition in This refers to the case where the content of Bi ₂ O ₃ is less than 1000 ppm (less than 0.1 mol%).

  Fifth, the composite powder material of the present invention is a composite powder material containing a glass powder composed of the above borosilicate glass and an alumina powder, and the content of the glass powder is 60 to 90% by volume, the alumina powder. The content of is preferably 10 to 30% by volume.

  Sixth, the composite powder material of the present invention preferably has a softening point of 650 to 850 ° C. Here, the “softening point” refers to the temperature at the fourth inflection point measured with a macro-type differential thermal analyzer (DTA).

  Seventh, the composite powder material paste of the present invention is preferably a composite powder material containing the composite powder material and a vehicle, wherein the composite powder material is the composite powder material described above.

As described above, the borosilicate glass of the present invention has a glass composition of mol%, SiO ₂ 20 to 40%, B ₂ O ₃ 25 to 45%, CaO _{3 to} 15%, SrO + BaO + ZnO 5 to 30%, ZrO. _It contains _{20 to} 6%, Al ₂ O ₃ 0 to 8%, CuO 0 to 1%, and the molar ratio (SiO ₂ + CaO) / (B ₂ O ₃ + SrO + BaO + ZnO) is larger than 0.50. . The reason why the content range of each component is regulated as described above will be described below. In addition, in description of the containing range of each component,% display means mol%.

SiO ₂ is a component that forms a glass skeleton and a component that suppresses reactivity with the Ag external electrode. The content of SiO ₂ is 20 to 40%, preferably 25 to 40%, more preferably 27 to 38%. When the content of SiO ₂ is reduced, the reactivity with the Ag external electrode is increased. On the other hand, when the content of SiO ₂ is increased, the softening point is unduly increased, and it becomes difficult to fire at a temperature of 900 ° C. or lower.

B ₂ O ₃ is a component that forms a glass skeleton and widens the vitrification range, but when its content increases, the reactivity with the Ag external electrode increases. Therefore, the content of B ₂ O ₃ is 25 to 45%, preferably 25 to 40%, more preferably 27 to 38%.

  CaO is a component that stabilizes the glass and suppresses reactivity with the Ag external electrode. The content of CaO is 3 to 15%, preferably 5 to 15%, more preferably 6 to 14%. When the content of CaO is increased, feldspar crystals are likely to precipitate, and the surface smoothness of the coating layer is likely to be reduced.

  SrO, BaO and ZnO are components that stabilize the glass. The total amount of SrO, BaO and ZnO is 5 to 30%, preferably 10 to 25%. The SrO content is preferably 0 to 12%, more preferably 0.1 to 11%, still more preferably 1 to 10%, and particularly preferably 3 to 9%. The content of BaO is preferably 0 to 12%, more preferably 0.1 to 10%, still more preferably 1 to 10%, and particularly preferably 3 to 8%. The content of ZnO is preferably 0 to 15%, more preferably 1 to 15%, still more preferably 3 to 15%, still more preferably 5 to 14%, and particularly preferably 6 to 12%. When the content of SrO, BaO and ZnO is increased, feldspar crystals are likely to be precipitated, and the surface smoothness of the coating layer is likely to be reduced.

ZrO ₂ is a component that enhances wear resistance. The content of ZrO ₂ is 0 to 6%, preferably 0.1 to 5%, more preferably 0.5 to 4%, and particularly preferably 1 to 4%. When the content of ZrO ₂ decreases, the wear resistance tends to decrease. On the other hand, when the content of ZrO ₂ is increased, the softening point is unreasonably raised and it becomes difficult to fire at a temperature of 900 ° C. or lower.

Al ₂ O ₃ is a component that improves wear resistance. The content of Al ₂ O ₃ is 0 to 8%, preferably 0.1 to 7%, more preferably 1 to 7%, and further preferably 2 to 6%. When the content of Al ₂ O ₃ is reduced, the wear resistance is likely to be lowered. On the other hand, when the content of Al ₂ O ₃ increases, feldspar crystals are likely to precipitate, and the surface smoothness of the coating layer tends to be reduced.

  CuO is a component that remarkably suppresses the reactivity with the Ag external electrode. The CuO content is 0 to 1%, preferably 0.005 to 0.09%, and more preferably 0.01 to 0.08%. If the CuO content is increased, feldspar crystals are likely to precipitate, and the surface smoothness of the coating layer is likely to be reduced.

The molar ratio (SiO ₂ + CaO) / (B ₂ O ₃ + SrO + BaO + ZnO) is greater than 0.50, preferably 0.55 or more, more preferably 0.60 or more. When the molar ratio (SiO ₂ + CaO) / (B ₂ O ₃ + SrO + BaO + ZnO) is small, feldspar crystals are likely to precipitate and the surface smoothness of the coating layer is likely to be reduced.

  In addition to the above components, for example, the following components may be introduced.

In addition to the above components, various components may be introduced as long as the characteristics of the thermal print head are not significantly impaired. For example, in order to lower the softening point, Cs ₂ O, Rb ₂ O, or the like may be introduced in a total amount or independently of 5%, particularly 1%. In order to stabilize the glass, Y ₂ O ₃ , La ₂ O ₃ , Ta ₂ O ₅ , SnO ₂ , TiO ₂ , Nb ₂ O ₅ , P ₂ O ₅ , CeO ₂ , V ₂ O _5, etc. are combined. It may be introduced up to 10%, in particular up to 1%, alone or in amount.

PbO and Bi ₂ O ₃ are components that lower the softening point, but are also environmentally hazardous substances, so it is preferable to avoid substantial introduction.

  The composite powder material of the present invention is a composite powder material containing a glass powder made of the above borosilicate glass and an alumina powder, wherein the glass powder content is 60 to 90% by volume, and the alumina powder content is It is preferable that it is 10-30 volume%.

  Glass powder is a material for melting during firing to form a coating layer. The glass powder can be produced, for example, by forming molten glass into a film and then crushing and classifying the obtained glass film.

  The content of the glass powder is preferably 60 to 90% by volume, preferably 70 to 88% by volume, and more preferably 76 to 85% by volume. When the content of the glass powder decreases, it becomes difficult to form a dense coating layer, and it becomes difficult to ensure desired surface smoothness. On the other hand, when the content of the glass powder is increased, the content of the alumina powder is relatively decreased, so that the wear resistance and the thermal conductivity of the coating layer are easily lowered.

The average particle diameter _{D 50} of the glass powder is preferably 2.0μm or less, the maximum particle diameter _{D max} is preferably 10μm or less. If the particle size of the glass powder is too large, the surface smoothness of the coating layer tends to be lowered, and large bubbles tend to remain in the coating layer. Here, the “average particle diameter D ₅₀ ” refers to a value measured with a laser diffractometer, and in an accumulated particle size distribution curve based on volume when measured by a laser diffraction method, the accumulated amount is accumulated from the smaller particle. The particle diameter is 50%. “Maximum particle size D _max ” refers to a value measured by a laser diffractometer, and in the volume-based cumulative particle size distribution curve measured by the laser diffraction method, the accumulated amount is accumulated from the smaller particle. The particle size is 99%.

  Alumina powder is a material that increases the wear resistance of the coating layer, and a material that increases the thermal conductivity of the coating layer. The content of the alumina powder is preferably 10 to 30% by volume, preferably 15 to 23% by volume. When the content of the alumina powder is increased, feldspar crystals are likely to be precipitated, and the surface smoothness of the coating layer is likely to be lowered. Further, when the content of the alumina powder is increased, the proportion of the glass powder is relatively decreased, so that it is difficult to form a dense coating layer and it is difficult to ensure desired surface smoothness.

The average particle diameter _{D 50} of the alumina powder is preferably 2.0μm or less, the maximum particle diameter _{D max} is preferably 10μm or less. When the particle size of the alumina powder is too large, the surface smoothness of the coating layer tends to be lowered.

  In addition to the alumina powder, another ceramic powder may be introduced in an amount of 0 to 10% by volume, particularly 0 to 8% by volume. Various materials can be used as other ceramic powders. For example, zirconia, mullite, silica, cordierite, titania, tin oxide, etc. are used to adjust the thermal expansion coefficient and wear resistance of the coating layer. Of these, one or more can be added.

  In the composite powder material of the present invention, the softening point is preferably 650 to 850 ° C, more preferably 670 to 830 ° C, and further preferably 690 to 810 ° C. When the softening point is too high, it becomes difficult to form a dense coating layer at a firing temperature of 900 ° C. or lower, and it becomes difficult to ensure desired surface smoothness. On the other hand, if the softening point is too low, the reactivity with the Ag external electrode increases.

In the composite powder material of the present invention, the average thermal expansion coefficient in the temperature range of 30 to 300 ° C. is preferably 53 × 10 ⁻⁷ to 70 × 10 ⁻⁷ / ° C., more preferably 55 × 10 ^{−7 to} 68 × 10. ^-7 / ° C. This makes it easy to prevent warping of the alumina substrate after firing. Here, the “thermal expansion coefficient” is a value measured by a thermomechanical analyzer (TMA).

  The composite powder material paste of the present invention is a powder material paste containing a composite powder material and a vehicle, and the composite powder material is preferably the above composite powder material. Here, the vehicle is a material for dispersing the composite powder material into a paste, and is usually composed of a thermoplastic resin, a plasticizer, a solvent, and the like.

  The composite powder material paste can be prepared by preparing a composite powder material and a vehicle, and mixing and kneading them at a predetermined ratio.

  A thermoplastic resin is a component which improves the film | membrane intensity | strength after drying, and is a component which provides a softness | flexibility. The content of the thermoplastic resin in the composite powder material paste is preferably 0.1 to 20% by mass. As the thermoplastic resin, polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, ethyl cellulose and the like are preferable, and it is preferable to use one or more of these.

  The solvent is a component for dissolving the thermoplastic resin. The content of the solvent in the composite powder material paste is preferably 10 to 30% by mass. As the solvent, terpineol, diethylene glycol monobutyl ether acetate, 2,2,4-trimethyl-1,3-pentadiol monoisobutyrate and the like are preferable, and it is preferable to use one or more of these.

The coating layer of the thermal print head is formed by first applying a composite powder material paste on an alumina substrate on which an Au lead electrode, an Ag external electrode, a RuO ₂ resistor, etc. are formed, and forming a coating layer having a predetermined thickness. And dried to obtain a dry film. Thereafter, the dried film is baked at a temperature of 800 to 900 ° C. for 5 to 20 minutes to form a coating layer (baked film). If the firing temperature is too low or the firing time (holding time) is too short, the dried film will not sinter sufficiently, and the denseness and surface smoothness of the coating layer will tend to be reduced. On the other hand, if the firing temperature is too high or the firing time (holding time) is too long, the glass powder reacts with the RuO ₂ resistor, etc., and the characteristics of the resistor are likely to deteriorate, There is a possibility that the reactivity becomes high and the electrode is disconnected.

  Hereinafter, based on an Example, this invention is demonstrated in detail. The present invention is not limited to the following examples. The following examples are merely illustrative.

  Table 1 shows Examples (Sample Nos. 1 to 4) and Comparative Examples (Sample No. 5) of the present invention.

  Each sample was prepared as follows. First, raw materials were prepared and mixed uniformly so as to have the glass composition shown in the table. Then, after putting in a platinum crucible and melting at 1350 to 1450 ° C. for 2 hours, it was formed into a film.

Subsequently, the above glass film was pulverized with a ball mill and then air-flow classified to obtain a glass powder having an average particle size D _{50 of} 2.0 μm or less and a maximum particle size D _{max of} 10 μm or less. Both were weighed so that the obtained glass powder was 80% by volume and the alumina powder was 20% by volume, and then sufficiently mixed to obtain a composite powder material. About the obtained composite powder material, the softening point and the thermal expansion coefficient were evaluated. The average particle diameter _{D 50} of the alumina powder is 2.0μm or less and a maximum particle diameter _{D max} were 10μm or less.

  The softening point is the temperature at the fourth inflection point measured with a macro-type differential thermal analyzer (DTA).

  The thermal expansion coefficient was determined by forming each composite powder material under pressure, firing it at (softening point + 10) ° C., processing to a diameter of 5 mm and a length of 20 mm, obtaining a measurement sample, It is an average value measured in a temperature range of 30 to 300 ° C. by TMA).

  Next, the composite powder and a vehicle (terpineol containing 5% by mass of ethyl cellulose and 3% by mass of tributyl acetylcitrate) were mixed and kneaded by a three-roll mill to obtain a composite powder material paste. Further, a composite powder material paste was applied by screen printing on an alumina substrate with a heat storage layer having an electrode layer (Ag external electrode layer) and a resistor layer. Firing was performed at a temperature of 20 ° C. for 20 minutes to obtain a fired film (coating layer) having a thickness of about 10 μm. About the obtained alumina substrate with a laminated film, the surface smoothness and the reactivity with an Ag external electrode were evaluated.

  The surface smoothness is evaluated by observing the surface of the fired film with a microscope, assuming that there is crystal precipitation as “x”, and no crystal precipitation as “◯”.

  The reactivity with the Ag external electrode was evaluated as “X” when yellowing was observed when the Ag external electrode after firing was observed, and “○” when yellowing was not observed. is there. Note that the yellowing of the Ag external electrode correlates with the reactivity with the Ag external electrode, and when yellowing occurs in the Ag external electrode, it can be said that the reactivity with the Ag external electrode is high.

As is clear from Table 1, sample No. In Nos. 1 to 4, since the glass composition of the glass powder was regulated within a predetermined range, the softening point was low, and the evaluation of surface smoothness and reactivity with Ag external electrodes was good. On the other hand, sample No. No. 5 had a low softening point, but the surface ratio was poor because the molar ratio (SiO ₂ + CaO) / (B ₂ O ₃ + SrO + BaO + ZnO) was small.

Claims (7)

As a glass composition, in _{mol%, SiO 2 20~40%, B} 2 O 3 25~45%, CaO 3~15%, SrO + BaO + 5~30% ZnO, ZrO 2 0~6%, Al 2 O 3 0~8 %, CuO 0 to 1%, and the molar ratio (SiO ₂ + CaO) / (B ₂ O ₃ + SrO + BaO + ZnO) is greater than 0.50. As a glass composition, in _{mol%, SiO 2 25~40%, B} 2 O 3 25~40%, CaO 5~15%, SrO 0.1~10%, BaO 0.1~10%, ZnO 5~15 %, ZrO ₂ 0.1-4%, Al ₂ O ₃ 0.1-7%, CuO 0.005-0.09%, molar ratio (SiO ₂ + CaO) / (B ₂ O ₃ + SrO + BaO + ZnO) The borosilicate glass according to claim 1, wherein the borosilicate glass is used for coating a thermal print head. As a glass composition, in _{mol%, SiO 2 25~40%, B} 2 O 3 25~40%, CaO 5~15%, SrO 1~10%, BaO 1~10%, 5~15% ZnO, ZrO 2 _{0.5~4%, Al 2 O 3 1~7} %, by containing 0.01 to 0.09% CuO, the molar ratio _{(SiO 2 + CaO) / (} B 2 O 3 + SrO + BaO + ZnO) is 0.55 or more The borosilicate glass according to claim 1, wherein the borosilicate glass is used for coating a thermal print head. The borosilicate glass according to any one of claims 1 to 3, wherein the glass composition does not substantially contain PbO and Bi ₂ O ₃ .   It is a composite powder material containing the glass powder consisting of the borosilicate glass according to any one of claims 1 to 4 and an alumina powder, wherein the content of the glass powder is 60 to 90% by volume, and the content of the alumina powder Is a composite powder material, characterized in that 10 to 30% by volume.   The composite powder material according to claim 5, wherein the softening point is 650 to 850 ° C.   A composite powder material paste comprising a composite powder material and a vehicle, wherein the composite powder material is the composite powder material according to claim 5 or 6.