White glass container and method for producing same

A method for producing a white glass container having at least a neck portion and a body portion and derived from a phase separation phenomenon of a halogen-free glass composition,

• wherein the glass composition includes, as ingredients, at least 45-65% of SiO2, 2-8% of P2O5, 5-9% of Al2O3, 1-13% of B2O3, 5-12% of R2O, 3-10% of ZnO and 3-12% of CaO based on weight percent on the basis of the total amount, R being at least one selected from Na and K, or at least 45-65% of SiO2, 2-8% of P2O5, 5-9% of Al2O3, 1-13% of B2O3, 5-12% of R2O, 3-10% of MgO and 3-12% of CaO based on weight percent on the basis of the total amount, R being at least one selected from Na and K,
• the degree of whiteness in the neck portion as measured according to JIS Z 8730 is adjusted to a value of 40 or more and below 80,
• the degree of whiteness in the body portion as measured according to JIS Z 8730 is adjusted to a value of 80 or more,
• at least a portion of the neck portion and at least a portion of the body portion comprise a white multilayer structure configured to successively include, in a direction from outer surface sides of the neck portion and the body portion toward inner surface sides of the neck portion and the body portion, a white transparent layer of relatively low white coloration and a white opaque layer of relatively high white coloration,
• the content of P2O5 in the white transparent layer is smaller than the content of P2O5 in the white opaque layer, and
• the method comprises the following Step 1 and Step 2:
• Step 1:
• a step of preparing a composition for glass having, as ingredients, at least SiO2, P2O5, Al2O3, B2O3, R2O, ZnO and CaO, R being at least one selected from Na and K, or at least SiO2, P2O5, Al2O3, B2O3, R2O, MgO and CaO, R being at least one selected from Na and K, and melting the composition for glass;
• and
• Step 2:
• a step of molding the molten composition for glass by a one-press method using a mold and a plunger, and also slowly cooling the composition for glass, so as to obtain a white glass container comprising, in a least a portion of the neck portion and in at least a portion of the body portion, a three-layer structure derived from a phase separation phenomenon of the glass composition.

A method for producing a white glass container having at least a neck portion and a body portion and derived from a phase separation phenomenon of a halogen-free glass composition,

• wherein the glass composition includes, as ingredients, at least 45-65% of SiO2, 2-8% of P2O5, 5-9% of Al2O3, 1-13% of B2O3, 5-12% of R2O, 3-10% of ZnO and 3-12% of CaO based on weight percent on the basis of the total amount, R being at least one selected from Na and K, or at least 45-65% of SiO2, 2-8% of P2O5, 5-9% of Al2O3, 1-13% of B2O3, 5-12% of R2O, 3-10% of MgO and 3-12% of CaO based on weight percent on the basis of the total amount, R being at least one selected from Na and K,
• the degree of whiteness in the neck portion as measured according to JIS Z 8730 is adjusted to a value of 40 or more and below 80,
• the degree of whiteness in the body portion as measured according to JIS Z 8730 is adjusted to a value of 80 or more,
• at least a portion of the neck portion and at least a portion of the body portion comprise a white multilayer structure configured to successively include, in a direction from outer surface sides of the neck portion and the body portion toward inner surface sides of the neck portion and the body portion, a white transparent layer of relatively low white coloration and a white opaque layer of relatively high white coloration,
• the content of P2O5 in the white transparent layer is smaller than the content of P2O5 in the white opaque layer, and
• the method comprises the following Step 1′ and Step 2′:
• Step 1′:
• a step of preparing a composition for glass having, as ingredients, at least SiO2, P2O5, Al2O3, B2O3, R2O, ZnO and CaO, R being at least one selected from Na and K, or at least SiO2, P2O5, Al2O3, B2O3, R2O, MgO and CaO, R being at least one selected from Na and K, and melting the composition for glass;
• and
• Step 2′:
• a step of molding the molten composition for glass by a blow method using a mold and cooling air, and also slowly cooling the composition for glass, so as to obtain a white glass container comprising, in a least a portion of the neck portion and in at least a portion of the body portion, a two-layer structure derived from a phase separation phenomenon of the glass composition.