WO2016082400A1 - Surface glaze of lead-free tableware ceramic and preparation method thereof - Google Patents

Abstract

A surface glaze of lead-free tableware ceramic and preparation method thereof, the glaze is used for being directly applied to the surface of the tableware ceramic body. The glaze is prepared from the following components in parts by weight: 15-30 parts of an intermediate temperature lead-free frit, 20-25 parts of potassium and sodium feldspar, 15-20 parts of quartz, 10-15 parts of calcium carbonate, 10 parts of an alkaline-earth metal compound, 10 parts of kaolin and 2-8 parts of a coloring oxide or a lead-free ceramic pigment. Checking the prepared lead-free tableware ceramic reveals a total lead content of lower than 90 ppm.

Description

Lead-free tableware porcelain surface glaze and preparation method thereof Technical field

 The invention belongs to the technical field of ceramics, in particular to a surface glaze of lead-free tableware porcelain and a preparation method thereof.

Background technique

The changes in the economic situation at home and abroad have made the already difficult ceramic enterprises worse. The increasingly harsh technical barriers abroad have increased the difficulty for Chinese ceramic companies to open up foreign markets.

In 2013, California updated the California Pro Proposal 65 (Proposition 65) standard, in addition to further limiting the lead and cadmium dissolution on the inner surface of ceramics in contact with food, non-food contact, and control of lead on the outer surface of non-food ceramics. In addition to the standard, the total lead content of the surface glaze of ceramic products used for storage or storage of food or beverages is not limited to 90 ppm.

According to the California Proposition 65, any person involved in the operation process, including retailers, importers, distributors, and overseas exporters, traders, and producers, is required to comply with the relevant regulations. If the person concerned violates the rules, the public or an environmental group can file a lawsuit on behalf of the public. The court can impose a fine of up to $2,500 on each product sold to California consumers in the past year. If the prosecution wins, lawyers who sue on behalf of the public can also recover the investigation fee in addition to the attorney's fees, which often amounts to as much as $1 million or more. Ceramic tableware is one of the targets of the California Proposition 65 (Proposition65).

It is necessary to seek a lead-free export tableware porcelain surface glaze in accordance with the "Proposition 65" standard and its preparation method.

technical problem

The invention solves the technical problem that the total lead content of the glaze of the existing tableware porcelain exceeds the standard, and provides a lead-free export tableware porcelain surface glaze conforming to the "Proposition 65" standard, so that the tableware porcelain can be smoothly put into the European and American markets. And a series of glaze effects of different colors can be obtained by adjusting the colored oxide or the lead-free ceramic colorant.

Technical solution

In order to solve the above technical problem, the present invention adopts the following technical solutions:

The surface glaze of lead-free tableware porcelain is used for directly applying to the surface of the porcelain body of the tableware. The components of the glaze are composed of the following weight ratios: 15-30 parts of medium temperature lead-free frit, 20~ 25 parts of potassium sodium feldspar, 15-20 parts of quartz, 10-15 parts of calcium carbonate, 10 parts of alkaline earth metal compound, 10 parts of kaolin, 2-8 parts of colored oxide or lead-free ceramic colorant.

Preferably, the colored oxide is copper carbonate and/or cobalt oxide; and the lead-free ceramic colorant is a lead-free rare earth colorant.

Preferably, the alkaline earth metal compound is cerium carbonate and/or calcined zinc oxide.

A method for preparing a surface glaze of lead-free tableware porcelain comprises the following steps:

a, preparation of glaze: 15 ~ 30 parts of medium temperature lead-free frit, 20 ~ 25 parts of local potassium sodium feldspar, 15 ~ 20 parts of Xianyou quartz, 10 ~ 15 parts of calcium carbonate, 10 parts of alkaline earth metal compounds, 10 parts Kaolin, 2-8 parts of colored oxide or lead-free ceramic color mixture are mixed to form a mixture, and then the mixture is mixed according to the weight ratio: water=1:0.75~0.85, water is added, and the glaze is obtained by ball milling.

b. Glazing: Applying a layer of the above glaze to the surface of the porcelain body.

c. Firing: The glazed tableware porcelain body is sent to the tunnel kiln for firing, and the kiln is cooled to obtain the finished product.

Preferably, said step a further comprises passing the prepared glaze through a 220 mesh screen.

Preferably, the firing temperature in the step c is 1250 to 1270 ° C, and the firing time is 11 to 12 hours.

Preferably, the tunnel kiln of step c is a 54 m or 66 m automatic energy efficient tunnel kiln.

Preferably, the colored oxide is copper carbonate and/or cobalt oxide; and the lead-free ceramic colorant is a lead-free rare earth colorant.

Preferably, the alkaline earth metal compound is cerium carbonate and/or calcined zinc oxide.

Beneficial effect

Compared with the prior art, the invention has the beneficial effects of:

The lead-free export tableware porcelain surface glaze provided by the invention has a total lead content of less than 90 ppm according to the results of EPA-3052: microwave-assisted acid digestion of silicic acid and organic matrix and flame atomic absorption spectrometry (FLAA). The results of the 24-hour lead acetate solution test showed that the lead released from the food contact surface of flat ceramic tableware (such as a dish) was less than 0.226 ppm, and the lead released from the internal food contact surface of ceramic hollow tableware (such as teacup and cup) was concentrated. Less than 0.100ppm. According to the ASTMC-927 test results, the lead and cadmium released from the lip range of the product were also lower than 0.050 micrograms per milliliter and 4.00 micrograms per milliliter. In addition, if the lip area is not decorated and the NIOSH9100 swab test is performed on all decorative surfaces, the lead release is less than 1 microgram and the cadmium release is less than 4 micrograms.

The above test results are in full compliance with the newly promulgated California Pro Proposal 65 (Proposition 65) standard.

BEST MODE FOR CARRYING OUT THE INVENTION

The invention discloses a surface glaze for lead-free tableware porcelain and a preparation method thereof, and those skilled in the art can learn from the contents of the paper and appropriately improve the process parameters. It is to be understood that all such alternatives and modifications are obvious to those skilled in the art and are considered to be included in the present invention. The method and the application of the present invention have been described by the preferred embodiments, and it is obvious that the method and application described herein may be modified or appropriately modified and combined without departing from the scope of the present invention. The technique of the present invention is applied.

As a preferred embodiment of the present invention, the method for preparing a lead-free export tableware porcelain surface glaze comprises the following steps:

a) Preparation of glaze: 15~30 parts of medium temperature lead-free frit, 20~25 parts of local potassium sodium feldspar, 15~20 parts of Xianyou quartz, 10~15 parts of calcium carbonate, 10 parts of alkaline earth metal compound, 10 parts Kaolin, 2~8 parts of colored oxide or lead-free ceramic color mixture are mixed into a mixture, and then the mixture is made up of water: water=1:0.75~0.85, water is added, and glaze is obtained after ball milling; in this step The colored oxide of the foregoing glaze is preferably copper carbonate and/or cobalt oxide; the lead-free ceramic pigment is preferably various lead-free rare earth pigments; and the alkaline earth metal compound is preferably cesium carbonate and/or calcined zinc oxide.

b) Glazing: Apply a layer of the above glaze to the surface of the porcelain body.

c) Firing: The glazed tableware porcelain body is sent to the tunnel kiln for firing, and the kiln is cooled to obtain the finished product; the firing temperature is 1250~1270°C, and the firing time is 11-12 hours.

Four preferred glaze formulations using colored oxides are listed in Table 1:

Table 1

	plan 1	Scenario 2	Option 3	Option 4
Medium temperature lead-free frit	20	20	18	30
Local potassium sodium feldspar	25	twenty two	25	14
Xianyou quartz	20	20	20	18
Calcium carbonate	12	15	15	15
Barium carbonate	5	5	5	5
Calcined zinc oxide	5	5	5	5
Kaolin	10	10	10	10
Colored oxide	Copper carbonate	1.5	3	1.5
Cobalt oxide	-	-	0.2	3

Five preferred glaze formulations using lead-free rare earth pigments are listed in Table 2:

Table 2

	Option 5	Option 6	Option 7	Option 8	Option 9
Medium temperature lead-free frit	20	20	18	twenty four	30
Local potassium sodium feldspar	25	twenty two	25	twenty one	14
Xianyou quartz	20	20	20	20	18
Calcium carbonate	12	15	15	12	15
Barium carbonate	5	5	5	5	5
Calcined zinc oxide	5	5	5	5	5
Kaolin	10	10	10	10	10
Lead-free rare earth pigment	Yellow	-	3	-	-
Vanadium blue	2	5	-	-	-
Agate red	-	-	-	8	-
gray	-	-	8	-	-
Pink	-	-	-	-	6

According to the actual needs, the lead-free export tableware porcelain surface glaze ratio can be selected according to Table 1 and Table 2, and a series of glazes of different colors can be obtained by adjusting the weight ratio of the colored oxide or the lead-free ceramic colorant. effect.

Table 3 lists the chemical composition and percentage of the medium temperature lead-free frit described in this example.

table 3

chemical composition	Percentage (%)
Silica SiO 2	68.06
Al2O3 Al 2 O 3	6.14
Ferric oxide Fe 2 O 3	0.18
Titanium dioxide TiO 2	0.03
Calcium oxide CaO	14.64
Magnesium oxide MgO	1.96
Potassium oxide K 2 O	2.32
Sodium oxide Na 2 O	1.11
Zinc oxide ZnO	5.45
Loss on ignition L.O.I	0.06
Analysis total TOTAL	99.95

In addition, in the present embodiment, the local potassium-sodium feldspar is produced in the local potassium-sodium feldspar of Dehua County, and the Xianyou quartz is the quartz of Xianyou County.

In the present invention, the lead-free export tableware porcelain surface glaze prepared according to the components and ratios provided in Table 1, Table 2 and Table 3 above, according to EPA-3052: microwave assisted acid digestion of silicic acid and organic matrix As a result of flame atomic absorption spectrometry (FLAA), the total lead content was less than 90 ppm. The results of the 24-hour lead acetate solution test showed that the lead released from the food contact surface of flat ceramic tableware (such as a dish) was less than 0.226 ppm, and the lead released from the internal food contact surface of ceramic hollow tableware (such as teacup and cup) was concentrated. Less than 0.100ppm. According to the ASTMC-927 test results, the lead and cadmium released from the lip range of the product were also lower than 0.050 micrograms per milliliter and 4.00 micrograms per milliliter. In addition, if the lip area is not decorated and the NIOSH9100 swab test is performed on all decorative surfaces, the lead release is less than 1 microgram and the cadmium release is less than 4 micrograms.

The above test results are in full compliance with the newly promulgated California Pro Proposal 65 (Proposition 65) standard.

Embodiments of the invention

The surface glaze of lead-free tableware porcelain is used for directly applying to the surface of the porcelain body of the tableware. The components of the glaze are composed of the following weight ratios: 15-30 parts of medium temperature lead-free frit, 20~ 25 parts of potassium sodium feldspar, 15-20 parts of quartz, 10-15 parts of calcium carbonate, 10 parts of alkaline earth metal compound, 10 parts of kaolin, 2-8 parts of colored oxide or lead-free ceramic colorant. The colored oxide is copper carbonate and/or cobalt oxide; the lead-free ceramic colorant is a lead-free rare earth colorant. The alkaline earth metal compound is cerium carbonate and/or calcined zinc oxide.

Industrial applicability

The lead-free export tableware porcelain surface glaze provided by the invention has a total lead content of less than 90 ppm according to the results of EPA-3052: microwave-assisted acid digestion of silicic acid and organic matrix and flame atomic absorption spectrometry (FLAA). The results of the 24-hour lead acetate solution test showed that the lead released from the food contact surface of flat ceramic tableware (such as a dish) was less than 0.226 ppm, and the lead released from the internal food contact surface of ceramic hollow tableware (such as teacup and cup) was concentrated. Less than 0.100ppm. According to the ASTMC-927 test results, the lead and cadmium released from the lip range of the product were also lower than 0.050 micrograms per milliliter and 4.00 micrograms per milliliter. In addition, if the lip area is not decorated and the NIOSH9100 swab test is performed on all decorative surfaces, the lead release is less than 1 microgram and the cadmium release is less than 4 micrograms. The above test results are in full compliance with the newly promulgated California Pro Proposal 65 (Proposition 65) standard, which has good industrial applicability.

Claims (9)

1. A surface glaze for lead-free tableware porcelain, the glaze is used for directly applying to the surface of the porcelain body of the tableware, characterized in that the components of the glaze are composed of the following weight ratios: 15-30 parts of medium temperature lead-free melting Block, 20-25 parts of potassium sodium feldspar, 15-20 parts of quartz, 10-15 parts of calcium carbonate, 10 parts of alkaline earth metal compound, 10 parts of kaolin, 2-8 parts of colored oxide or lead-free ceramic color.
2. The surface glaze of lead-free tableware porcelain according to claim 1, wherein the colored oxide is copper carbonate and/or cobalt oxide; and the lead-free ceramic coloring material is a lead-free rare earth coloring material.
3. A surface glaze for lead-free tableware porcelain according to claim 1 or 2, wherein the alkaline earth metal compound is cerium carbonate and/or calcined zinc oxide.
4. A method for preparing a surface glaze of a lead-free tableware porcelain, comprising the steps of:

   a, preparation of glaze: 15 ~ 30 parts of medium temperature lead-free frit, 20 ~ 25 parts of local potassium sodium feldspar, 15 ~ 20 parts of Xianyou quartz, 10 ~ 15 parts of calcium carbonate, 10 parts of alkaline earth metal compounds, 10 parts Kaolin, 2-8 parts of colored oxide or lead-free ceramic color mixture are mixed to form a mixture, and then according to the weight ratio of the mixture: water = 1: 0.75 ~ 0.85 with water, after ball milling to obtain a glaze;

   b. glazing: applying a layer of the glaze on the surface of the porcelain body;

   c. Firing: The glazed tableware porcelain body is sent to the tunnel kiln for firing, and the kiln is cooled to obtain the finished product.
5. A method for preparing a surface glaze of a lead-free tableware porcelain according to claim 4, wherein the step a further comprises passing the prepared glaze through a 220 mesh sieve.
6. The method for preparing a surface glaze for a lead-free tableware porcelain according to claim 4, wherein the firing temperature in the step c is 1250 to 1270 ° C, and the firing time is 11 to 12 hours.
7. The method for preparing a surface glaze of a lead-free tableware porcelain according to claim 4, wherein the tunnel kiln of the step c is an automatic high-efficiency energy-saving tunnel kiln of 54 meters or 66 meters.
8. The method for preparing a surface glaze of a lead-free tableware porcelain according to claim 4, wherein the colored oxide is copper carbonate and/or cobalt oxide; and the lead-free ceramic color material is lead-free rare earth color material.
9. A method of preparing a surface glaze for a lead-free tableware porcelain according to claim 4, wherein the alkaline earth metal compound is cerium carbonate and/or calcined zinc oxide.