Ceramic binder, ceramic slurry and ceramic chip

Abstract

The invention provides a ceramic binder, which comprises a polymer, and the polymer contains a polar structure unit, a hard structure unit and a flexible structure unit, the glass transition temperature Tg of the flexible structural unit is below 0 DEG C, and the weight-average molecular weight of the flexible structural unit is 1000-4000; moreover, the flexible structural unit contains a straight chain structure containing an oxygen element. The ceramic binder is used for the borate-containing ceramic powder, and the prepared ceramic wafer is high in tensile strength and good in flexibility.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-temperature co-fired ceramics, and particularly relates to a ceramic binder, a ceramic slurry, and a ceramic sheet. Background Art

[0002] Low Temperature Co-fired Ceramics (LTCC), as an important branch in the field of modern electronic packaging, plays an irreplaceable role in the construction of high-frequency, high-speed, and high-density electronic systems due to its excellent electrical properties, mechanical strength, thermal stability, and processability.

[0003] The manufacturing process of LTCC generally includes the following steps: First, the ceramic powder is subjected to ball milling and dispersion treatment, and then a plasticizer and a binder are added, followed by continued ball milling and mixing. After degassing treatment, a ceramic slurry composition with appropriate viscosity is obtained. Then, tape casting is carried out using equipment such as a doctor blade or an inverse roll coater. After removing volatile components such as solvents by heating and other means, the ceramic sheet is peeled off from the base film. A conductive paste for forming internal electrodes is coated on the obtained ceramic sheet by screen printing. The coated ceramic sheets are alternately overlapped in multiple layers and heated and pressed to form a laminate. Subsequently, the adhesive resin components in the laminate are subjected to thermal decomposition treatment (i.e., debinding treatment) to remove these components. Thereafter, through a firing process, a ceramic sintered body is obtained, and external electrodes are sintered on its end faces, and finally a multilayer ceramic capacitor is manufactured.

[0004] In the field of LTCC technology, the glass / ceramic composite system is currently the most widely used system. Among them, the borate glass system mainly composed of B2O3 - SiO2 has attracted much attention because it can significantly reduce the sintering temperature. In the traditional preparation process, the binder generally selects Polyvinyl Butyral Resin (abbreviated as PVB). However, the key properties such as the tensile strength of the ceramic sheet prepared using the existing PVB binder are insufficient. Summary of the Invention

[0005] In order to solve the problem of insufficient key properties such as the tensile strength of the ceramic sheet prepared by the existing ceramic binder, the present invention provides a ceramic binder, a ceramic slurry, and a ceramic sheet.

[0006] The object of the present invention is achieved by the following technical solutions.

[0007] In a first aspect, the present invention provides a ceramic binder, the ceramic binder comprising a polymer, the polymer containing polar structural units, hard structural units and flexible structural units; the flexible structural units have a glass transition temperature Tg below 0 °C and a weight average molecular weight of 1000 to 4000; and, in the flexible structural units, there is a straight-chain structure containing oxygen element.

[0008] Preferably, the straight-chain structure containing oxygen element in the flexible structural units is a straight-chain polyether structure.

[0009] Preferably, the flexible structural units include polyether acrylate structural units, and / or the glass transition temperature Tg of the polyether acrylate structural units is -10 to -90 °C.

[0010] Preferably, the flexible structural units are selected from one or more of methoxypolyethylene glycol acrylate structural units, ethoxypolyethylene glycol acrylate structural units, methoxypolyethylene glycol methacrylate structural units, ethoxypolyethylene glycol methacrylate structural units, and methoxypolypropylene glycol methacrylate structural units.

[0011] Preferably, the glass transition temperature Tg1 of the hard structural units is 80 °C or higher.

[0012] Preferably, the polar structural units include any one or a combination of at least two of hydroxyl-containing structural units, carboxylic acid structural units, amide structural units, and sulfonic acid structural units; the hard structural units include any one or a combination of at least two of acrylate structural units, aromatic vinyl structural units, and nitrile structural units.

[0013] Preferably, in the polymer, the mass ratio of the polar structural units, the flexible structural units to the hard structural units is (1 to 5):(35 to 65):(35 to 65).

[0014] Preferably, the glass transition temperature Tg2 of the polymer is 0 to 30 °C; and / or the weight average molecular weight of the polymer is 150,000 to 300,000.

[0015] In a second aspect, the present invention provides a ceramic slurry, comprising ceramic powder and the ceramic binder as described above; the content of B2O3 in the ceramic powder is 20 wt% to 40 wt%; in the ceramic slurry, the content of the flexible structural units of the ceramic binder is 15% to 35% of the content of B2O3.

[0016] In a third aspect, the present invention provides a ceramic sheet prepared from the ceramic slurry as described above.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention provides a ceramic binder suitable for borate-containing materials. The polymer contains polar structural units, hard structural units and flexible structural units; the glass transition temperature Tg of the flexible structural unit is below 0 °C, and the weight average molecular weight is 1000-4000; moreover, in the flexible structural unit, there is a straight-chain structure containing oxygen element. Through a large amount of research and analysis, the inventors of the present invention found that when this ceramic binder is used in a ceramic slurry, and the content of B2O3 in the ceramic powder is 20 wt% - 40 wt%; in the ceramic slurry, when the content of the flexible structural unit of the ceramic binder is 15% - 35% of the B2O3 content, the flexible structural unit with a specific structure in the above ceramic binder can have a good Lewis acid-base interaction with B2O3 in the ceramic powder, improving the compatibility between the ceramic binder and the ceramic powder, which is beneficial to improving the tensile strength and elongation at break of the ceramic sheet. Specific Embodiments

[0019] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the following further elaborates on the present invention in conjunction with specific embodiments. It should be understood that the embodiments described herein are some, rather than all, of the embodiments of the present invention, and are only used to explain the present invention, not to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0020] In a first aspect, the present invention provides a ceramic binder. The ceramic binder includes a polymer, and the polymer contains polar structural units, hard structural units and flexible structural units; the glass transition temperature Tg of the flexible structural unit is below 0 °C, and the weight average molecular weight is 1000-4000; moreover, in the flexible structural unit, there is a straight-chain structure containing oxygen element.

[0021] In the present invention, the glass transition temperature Tg of the flexible structural unit is below 0 °C, and the weight average molecular weight is 1000-4000; moreover, in the flexible structural unit, there is a straight-chain structure containing oxygen element. When this ceramic binder is used in borate-based ceramic powder with a specific B2O3 content (20 wt% - 40 wt%), by controlling the content of the above flexible structural unit to be 15% - 35% of the B2O3 content, the flexible structural unit with a specific structure in the above ceramic binder can have a good Lewis acid-base interaction with B2O3 in the ceramic powder, improving the compatibility between the ceramic binder and the ceramic powder, which is beneficial to improving the tensile strength and elongation at break of the ceramic sheet.

[0022] In the present invention, the glass transition temperature Tg of the flexible structural unit is below 0 °C. More preferably, the glass transition temperature Tg of the flexible structural unit is -10 to -90 °C, and further preferably -30 to -70 °C.

[0023] Preferably, the straight-chain structure containing oxygen element in the flexible structural unit is a straight-chain polyether structure. According to the present invention, as a preferred case, the above flexible structural unit includes a polyether acrylate structural unit. Specifically preferably, the flexible structural unit is selected from one or more of a methoxypolyethylene glycol acrylate structural unit, an ethoxypolyethylene glycol acrylate structural unit, a methoxypolyethylene glycol methacrylate structural unit, an ethoxypolyethylene glycol methacrylate structural unit, and a methoxypolypropylene glycol methacrylate structural unit.

[0024] To further improve the tensile strength and elongation at break of the ceramic sheet, the weight-average molecular weight of the flexible structural unit is 1500 to 3500. Specifically, it can be 1500, 2000, 2500, 3000, 3500, etc.; more preferably 2000 to 3000.

[0025] According to the present invention, as a preferred embodiment, the degree of polymerization of the above flexible structural unit is 20 to 80. Specifically, it can be 20, 30, 40, 50, 60, 70, 80, etc.; more preferably 40 to 60.

[0026] In the present invention, preferably, the glass transition temperature Tg1 of the hard structural unit is above 80 °C, and more preferably 80 to 130 °C. Specifically, the hard structural unit includes any one or a combination of at least two of an acrylate structural unit, an aromatic vinyl structural unit, and a nitrile structural unit.

[0027] In some specific embodiments, the hard structural unit includes any one or a combination of at least two of a methyl methacrylate structural unit, a tert-butyl methacrylate structural unit, an isobornyl methacrylate structural unit, a styrene structural unit, an α-methylstyrene structural unit, an acrylonitrile structural unit, and a methacrylonitrile structural unit.

[0028] In the present invention, the polar structural unit includes any one or a combination of at least two of a hydroxyl-containing structural unit, a carboxylic acid structural unit, an amide structural unit, and a sulfonic acid structural unit. Preferably, it is any one or a combination of at least two of an amide structural unit and a carboxylic acid structural unit.

[0029] Specifically, the polar structural unit includes any one or a combination of at least two of a 2-hydroxyethyl acrylate structural unit, a 2-hydroxypropyl acrylate structural unit, an acrylic acid structural unit, a methacrylic acid structural unit, an acrylamide structural unit, a methacrylamide structural unit, and a 2-acrylamido-2-methylpropanesulfonic acid structural unit. More preferably, it is any one or a combination of at least two of an acrylic acid structural unit, a methacrylic acid structural unit, an acrylamide structural unit, a methacrylamide structural unit, and a 2-acrylamido-2-methylpropanesulfonic acid structural unit.

[0030] Preferably, in the polymer, the mass ratio of the polar structural unit, the flexible structural unit, and the hard structural unit is (1~5):(35~65):(35~65).

[0031] Specifically, the mass ratio of the polar structural unit, the flexible structural unit, and the hard structural unit can be 5:35:60, 5:40:55, 5:50:45, 5:60:35, 1:65:34, 2:55:43, 3:47:50, or 4:51:45, etc.

[0032] In the present invention, the above-mentioned polar structural unit, hard structural unit, and flexible structural unit are respectively obtained by polymerizing polar monomers, hard monomers, and soft monomers. Among them, the monomers exist in the polymerized polymer in the form of corresponding structural units. The glass transition temperature, mass ratio, molecular weight, etc. of the above various structural units are based on the glass transition temperature, mass ratio to each other, and molecular weight of their corresponding monomers.

[0033] The above various monomers can be obtained through commercial purchase. For example, for the aforementioned soft monomers, monomers with corresponding parameters can be selected and purchased according to the required molecular weight, number of straight-chain carbon atoms, degree of polymerization, and Tg.

[0034] In some specific embodiments, the glass transition temperature Tg2 of the polymer is 0~30°C.

[0035] Specifically, the glass transition temperature Tg2 of the polymer can be 0°C, 5°C, 10°C, 14°C, 18°C, 20°C, 25°C, or 30°C, etc.

[0036] In some specific embodiments, the weight-average molecular weight of the polymer is 150,000~300,000.

[0037] Specifically, the weight-average molecular weight of the polymer can be 150,000, 200,000, 225,000, 260,000, 280,000, or 300,000, etc.

[0038] The polymer of the present invention can be prepared by a conventional free radical polymerization method. For example, its preparation method can be:

[0039] Mix the polar monomer, soft monomer, and hard monomer in proportion, add an initiator and a solvent, react at 60-70 °C for 3-5 h, then raise the temperature to 75-80 °C and add the initiator again, and continue to react for 5-7 h to obtain the polymer of the ceramic binder. Among them, the initiator can be azobisisobutyronitrile, and the addition amount is 0.5-2% of the total mass of the monomers. The solvent can be ethyl acetate, and the addition amount is 1.5-2 times the total mass of the monomers.

[0040] In some specific embodiments, the tensile strength of the adhesive film of the ceramic binder prepared is 20-40 MPa, and the elongation at break is 50%-100%.

[0041] In a second aspect, the present invention provides a ceramic slurry, including ceramic powder and the ceramic binder as described above. Among them, the content of B2O3 in the ceramic powder is 20wt%-40wt%; in the ceramic slurry, the content of the flexible structural unit of the ceramic binder is 15%-35% of the content of B2O3. At this time, it is very beneficial to further improve the tensile strength and elongation at break of the ceramic sheet.

[0042] The preparation method of the ceramic slurry of the present invention:

[0043] a) Primarily ball-mill the ceramic powder, solvent, and dispersant for 2-4 h. The mass ratio of the raw materials (ceramic powder, solvent, dispersant) to the grinding medium is 1-3:1; the content of B2O3 in the ceramic powder is 20wt%-40wt%; the solvent is ethyl acetate, and its addition amount is 75-85% of the mass of the ceramic powder; the dispersant is oleic acid, and its addition amount is 0.5-2% of the mass of the ceramic powder;

[0044] b) Then add the ceramic binder and plasticizer prepared by the present invention. The addition amount of the ceramic binder (based on the amount of the polymer) is 10-20% of the mass of the ceramic powder. The plasticizer can be dioctyl phthalate, and its addition amount is 2-4% of the mass of the ceramic powder, and perform secondary ball-milling for 8-12 h to obtain the ceramic slurry.

[0045] In some specific embodiments, the solid content of the ceramic slurry prepared is 45%-60%, and the viscosity is 1000-8000 cp.

[0046] In a third aspect, the present invention provides a ceramic sheet, including the aforementioned ceramic slurry. Cast the ceramic slurry prepared by the present invention on a fully automatic casting machine to obtain a ceramic sheet.

[0047] In some specific embodiments, the tensile strength of the ceramic sheet prepared is 6-15 MPa, and the elongation at break is 6%-10%.

[0048] The following will further explain the specific implementation manners of the present invention through examples and comparative examples.

[0049] Unless otherwise specified, the reagents, materials, and instruments used in the following description are all conventional reagents, conventional materials, and conventional instruments, which can be obtained commercially. The reagents involved can also be obtained by conventional synthesis methods. The methods in the examples are all conventional methods in the art unless otherwise specified. The monomers conforming to the present invention can be obtained commercially.

[0050] The glass transition temperature can be detected by a differential scanning calorimeter (DSC) according to GB / T 19466.1-2004. The molecular weight of the polymer can be determined by gel permeation chromatography (GPC).

[0051] Example 1:

[0052] 1) Preparation of ceramic binder:

[0053] In a reaction kettle, 5 parts of acrylic acid, 40 parts of methoxypolyethylene glycol acrylate (Tg is -65°C, weight average molecular weight is 2000, and degree of polymerization is 40), and 55 parts of methyl methacrylate (Tg1 is 105°C) are mixed. 0.5 part of azobisisobutyronitrile and 200 parts of ethyl acetate are added, and the reaction is carried out at 70°C for 4 h; the temperature is raised to 75°C, and then 0.5 part of azobisisobutyronitrile is added, and the reaction is continued for 6 h to obtain a ceramic binder containing polymer. Among them, the glass transition temperature of the polymer is 15°C, and the weight average molecular weight is 15.8 w.

[0054] 2) Preparation of ceramic slurry

[0055] a) In a ball milling tank, the ceramic powder, solvent, and dispersant are initially ball milled for 3 h. The mass ratio of the raw materials (ceramic powder, solvent, and dispersant) to the grinding medium is 2:1; the mass ratio of B2O3:SiO2:Al2O3 in the ceramic powder is 3:4:3, and the content of B2O3 in the ceramic powder is 30 wt%; the solvent is ethyl acetate, and its addition amount is 85% of the mass of the ceramic powder; the dispersant is oleic acid, and its addition amount is 1% of the mass of the ceramic powder;

[0056] b) Then, the ceramic binder and plasticizer prepared by the present invention are added to the ball milling tank. The addition amount of the ceramic binder (based on the amount of the polymer) is 15% of the mass of the ceramic powder, and the plasticizer is dioctyl phthalate, and its addition amount is 3% of the mass of the ceramic powder. Secondary ball milling is carried out for 10 h to obtain a ceramic slurry. The flexible structural unit in the ceramic binder is 20% of the mass of B2O3 in the ceramic slurry; the solid content of the ceramic slurry is 58.3%, the initial slurry viscosity is 1213 cp, and the viscosity after standing for 24 h is 1219 cp.

[0057] 3) Preparation of ceramic sheets:

[0058] The ceramic slurry prepared in the present invention is cast on a full-automatic casting machine to obtain a ceramic sheet with a thickness of 50 μm.

[0059] Example 2:

[0060] The ceramic binder, ceramic slurry and ceramic sheet are prepared according to the method of Example 1. The main difference between Example 2 and Example 1 is that in the preparation of the ceramic binder, 5 parts of methacrylic acid, 40 parts of polyethylene glycol monomethyl ether acrylate (Tg is -63 °C, weight-average molecular weight is 1500, degree of polymerization is 30), and 55 parts of tert-butyl methacrylate (Tg1 is 104 °C) are selected; the glass transition temperature of the ceramic binder is 18 °C, and the weight-average molecular weight is 168,000.

[0061] The remaining operation steps are the same.

[0062] Example 3:

[0063] The ceramic binder, ceramic slurry and ceramic sheet are prepared according to the method of Example 1. The main difference between Example 3 and Example 1 is that in the preparation of the ceramic binder, 5 parts of acrylamide, 40 parts of polyethylene glycol monomethyl ether acrylate (Tg is -68 °C, weight-average molecular weight is 4000, degree of polymerization is 80), and 55 parts of isobornyl methacrylate (Tg1 is 110 °C) are selected; the glass transition temperature of the ceramic binder is 20 °C, and the weight-average molecular weight is 243,000.

[0064] The remaining operation steps are the same.

[0065] Example 4:

[0066] The ceramic binder, ceramic slurry and ceramic sheet are prepared according to the method of Example 1. The main difference between Example 4 and Example 1 is that in the preparation of the ceramic binder, 2 parts of methacrylamide, 50 parts of polypropylene glycol monomethyl ether methacrylate (Tg is -66 °C, weight-average molecular weight is 3000, degree of polymerization is 60), and 48 parts of isobornyl methacrylate (Tg1 is 110 °C) are selected; the glass transition temperature of the ceramic binder is -4 °C, and the weight-average molecular weight is 268,000.

[0067] The remaining operation steps are the same.

[0068] Example 5:

[0069] Prepare the ceramic binder, ceramic slurry and ceramic sheet according to the method of Example 1. The main difference between Example 5 and Example 1 is that: in the preparation of the ceramic binder, 4 parts of acrylamide, 50 parts of polyethylene glycol monoethyl ether acrylate (Tg is -62 °C, molecular weight is 1000, degree of polymerization is 20), 26 parts of styrene (Tg1 is 100 °C) and 20 parts of acrylonitrile (Tg1' is 125 °C) are selected; the glass transition temperature of the ceramic binder is 0 °C, and the molecular weight is 284,000.

[0070] The remaining operation steps are the same.

[0071] Example 6:

[0072] Prepare the ceramic binder, ceramic slurry and ceramic sheet according to the method of Example 1. The main difference between Example 6 and Example 1 is that: in the preparation of the ceramic slurry, the ceramic binder (based on the amount of polymer) is 20% of the mass of the ceramic powder, the mass ratio of B2O3:SiO2:Al2O3 in the ceramic powder is 2.5:4.5:3, and the content of B2O3 in the ceramic powder is 25 wt%; the flexible structural unit in the ceramic binder is 32% of the mass of B2O3 in the ceramic slurry; the solid content of the ceramic slurry is 60%.

[0073] The remaining operation steps are the same.

[0074] Example 7:

[0075] Prepare the ceramic binder, ceramic slurry and ceramic sheet according to the method of Example 1. The main difference between Example 7 and Example 1 is that: in the preparation of the ceramic slurry, the ceramic binder (based on the amount of polymer) is 8% of the mass of the ceramic powder, the mass ratio of B2O3:SiO2:Al2O3 in the ceramic powder is 2:4.5:3.5, and the content of B2O3 in the ceramic powder is 20 wt%; the flexible structural unit in the ceramic binder is 16% of the mass of B2O3 in the ceramic slurry; the solid content of the ceramic slurry is 45%.

[0076] The remaining operation steps are the same.

[0077] Example 8:

[0078] Prepare the ceramic binder, ceramic slurry and ceramic sheet according to the method of Example 1. The main difference between Example 8 and Example 1 is that acrylic acid is replaced by 2-hydroxyethyl acrylate.

[0079] The remaining operation steps are the same.

[0080] Comparative Example 1:

[0081] The difference between Comparative Example 1 and Example 1 is that: PVB resin is selected as the ceramic binder.

[0082] The remaining operation steps are the same.

[0083] Comparative Example 2:

[0084] The difference between Comparative Example 2 and Example 1 is that it does not contain methoxypolyethylene glycol acrylate.

[0085] The remaining operation steps are the same.

[0086] Comparative Example 3:

[0087] The difference between Comparative Example 3 and Example 1 is that the weight-average molecular weight of methoxypolyethylene glycol acrylate is 500, and the glass transition temperature Tg is -61 °C.

[0088] The remaining operation steps are the same.

[0089] Comparative Example 4:

[0090] The difference between Comparative Example 4 and Example 1 is that the weight-average molecular weight of methoxypolyethylene glycol acrylate is 6000, and the glass transition temperature Tg is -70 °C.

[0091] The remaining operation steps are the same.

[0092] Comparative Example 5:

[0093] The difference between Comparative Example 5 and Example 1 is that isooctyl acrylate with a glass transition temperature Tg of -70 °C is used to replace methoxypolyethylene glycol acrylate in Example 1.

[0094] The remaining operation steps are the same.

[0095] Comparative Example 6:

[0096] The difference between Comparative Example 6 and Example 1 is that in the preparation of the ceramic slurry, the ceramic binder (based on the amount of polymer) is 7.5% of the mass of the ceramic powder, the mass ratio of B2O3:SiO2:Al2O3 in the ceramic powder is 3:4:3, the content of B2O3 in the ceramic powder is 30 wt%; the flexible structural unit in the ceramic binder is 10% of the mass of B2O3 in the ceramic slurry.

[0097] The remaining operation steps are the same.

[0098] Comparative Example 7:

[0099] The difference between Comparative Example 7 and Example 1 is that in the preparation of the ceramic slurry, the ceramic binder (based on the amount of polymer) is 25% of the mass of the ceramic powder, the mass ratio of B2O3:SiO2:Al2O3 in the ceramic powder is 2:4.5:3.5, the content of B2O3 in the ceramic powder is 20 wt%; the flexible structural unit in the ceramic binder is 50% of the mass of B2O3 in the ceramic slurry.

[0100] The remaining operation steps are the same.

[0101] Performance test:

[0102] Perform performance tests on the ceramic binders, ceramic slurries, and ceramic sheets prepared in the above examples and comparative examples.

[0103]

Tensile strength

[0104]

Elongation at break

[0105] The performance test results are shown in Table 1.

[0106] Table 1:

[0107]

[0108] From the test results of Examples 1 to 3, 5 and Example 4, it can be seen that when the glass transition temperature of the polymer is above 0 °C, the tensile strength of the ceramic sheet is stronger.

[0109] From the test results of Examples 1 to 3, 6 and Example 7, it can be seen that when the addition amount of the ceramic binder is 10-20% of the mass of the ceramic powder, the tensile strength of the ceramic sheet is stronger.

[0110] From the test results of Examples 1 to 8 and Comparative Example 1, it can be seen that compared with the traditional PVB resin, the tensile strength of the adhesive film of the ceramic binder of the present invention is stronger. After the ceramic binder is configured with the ceramic powder of the foregoing composition into a slurry and prepared into a ceramic sheet, the tensile strength and flexibility of the ceramic sheet are significantly improved.

[0111] From the test results of Examples 1 to 8 and Comparative Example 2, it can be seen that compared with the binder without a flexible structural unit, the tensile strength of the adhesive film of the ceramic binder of the present invention is stronger and the flexibility is better; the tensile strength and flexibility of the ceramic sheet prepared by the present invention are significantly improved.

[0112] From the test results of Examples 1 to 8 and Comparative Examples 3 to 4, it can be seen that when the molecular weight of the flexible structural unit is too low or too high, the tensile strength or elongation at break of the ceramic sheet will decrease.

[0113] From the test results of Examples 1 to 8 and Comparative Example 5, it can be seen that when the flexible structural unit does not include an oxygen-containing straight-chain structure, the tensile strength and elongation at break of the ceramic sheet will both decrease significantly.

[0114] From the test results of Examples 1 to 8 and Comparative Examples 6 to 7, it can be seen that when the content of the flexible structural unit of the ceramic binder is too low or too high relative to the content of B2O3 in the ceramic powder, the tensile strength or elongation at break of the ceramic sheet will decrease.

[0115] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the essence and scope of the present invention. Various modifications made by those of ordinary skill in the art to the above embodiments after reading this specification all fall within the scope protected by the present invention.

Claims

1. A ceramic binder, characterized in that: The ceramic binder includes a polymer, which contains a polar structural unit, a hard structural unit and a flexible structural unit; the glass transition temperature Tg of the flexible structural unit is below 0°C, and the weight average molecular weight is 1000-4000; and the flexible structural unit contains a straight chain structure containing an oxygen-containing element.

2. The ceramic binder according to claim 1, characterized in that The linear structure of the oxygen-containing element in the flexible structural unit is a linear polyether structure.

3. The ceramic binder according to claim 1, characterized in that The flexible structural unit includes a polyether acrylate structural unit, and / or the polyether acrylate structural unit has a glass transition temperature Tg of -10 to -90°C.

4. The ceramic binder according to any one of claims 1 to 3, characterized in that: The flexible structural unit is selected from one or more of polyethylene glycol monomethyl ether acrylate structural units, polyethylene glycol monoethyl ether acrylate structural units, polyethylene glycol monomethyl ether methacrylate structural units, polyethylene glycol monoethyl ether methacrylate structural units, and polypropylene glycol monomethyl ether methacrylate structural units.

5. The ceramic binder according to claim 1, characterized in that The glass transition temperature Tg1 of the hard structural unit is 80° C. or higher.

6. The ceramic binder according to claim 1, characterized in that The polar structural unit includes any one or a combination of at least two of a hydroxyl-containing structural unit, a carboxylic acid structural unit, an amide structural unit, and a sulfonic acid structural unit; The hard structural unit includes any one of an acrylic ester structural unit, an aromatic vinyl structural unit, and a nitrile structural unit, or a combination of at least two of them.

7. The ceramic binder according to claim 1, characterized in that In the polymer, the mass ratio of the polar structural unit, the flexible structural unit and the hard structural unit is (1-5): (35-65): (35-65).

8. The ceramic binder according to claim 1, characterized in that The glass transition temperature Tg2 of the polymer is 0-30° C.; and / or the weight average molecular weight of the polymer is 15w-30w.

9. A ceramic slurry, characterized in that: Comprising ceramic powder and a ceramic binder as claimed in any one of claims 1 to 8; The content of B2O3 in the ceramic powder is 20wt%~40wt%; in the ceramic slurry, the content of the flexible structural unit of the ceramic binder is 15%~35% of the content of B2O3.

10. A ceramic sheet, characterized in that: Prepared from the ceramic slurry described in claim 9.

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