Process for stabilizing the viscosity of polyvinyl acetals using a buffer

Claim 2

A process for stabilizing the viscosity of polyvinyl acetal resins which process comprises incorporating into the polyvinyl acetal resin an effective amount of a buffer, which when prepared as an aqueous solution has a pH in the range of from 3 to 7, wherein the buffer is incorporated into the resin prior to fabricating the resin into a shaped article in order to minimize changes in the viscosity of the polyvinyl acetal resin, wherein at least one component of the buffer is at least a bidentate ligand with the ability to interact with a metal to form a chelated ring structure and wherein the buffer is substantially free from hydrochloric, nitric and sulfuric acid components.

Claim 3

A process as in claim 1 wherein the polyvinyl acetal resin is polyvinyl butyral.

Claim 4

A process as in claim 2 wherein the polyvinyl butyral is plasticized.

Claim 5

A process as in claim 3 wherein the amount of buffer used is in the range of from 50 to 1300 parts per million.

Claim 6

A process as in claim 3 wherein the buffer is selected from the group consisting of Clark and Lubs phosphate, citrate, phthalate and borate buffers.

Claim 7

A process as in claim 3 wherein the buffer is a MacIlvaine's citrate/phosphate buffer.

Claim 8

A process for stabilizing the viscosity of a plasticized polyvinyl butyral resin which process comprises incorporating into the polyvinyl butyral resin from 20 to 20,000 parts (dry basis) per million of a buffer, which when prepared as an aqueous solution has a pH in the range of from 3 to 7 wherein the buffer is incorporated into the resin in the form of an aqueous soltuion prior to fabricating the resin into a shaped article in order to minimize changes in the viscosity of the polyvinyl butyral resin, wherein at least one component of the buffer is at least a bidentate ligand with the ability to interact with a metal to form a chelated ring structure and wherein the buffer is substantially free from hydrochloric, nitric and sulfuric acid components.

Claim 9

A process for stabilizing the viscosity of a plasticized polyvinyl butyral resin which process comprises incorporating into the polyvinyl butyral resin from 20 to 20,000 parts (dry basis) per million of a buffer, which when prepared as an aqueous solution has a pH in the range of from 3 to 7 wherein the buffer is incorporated into the resin in the form of an aqueous soltuion prior to fabricating the resin into a shaped article in order to minimize changes in the viscosity of the polyvinyl butyral resin, wherein at least one component of the buffer is at least a bidentate ligand with the ability to interact with a metal to form a chelated ring structure and wherein the buffer is substantially free from hydrochloric, nitric and sulfuric acid components.

Claim 10

A process as in claim 7 wherein the amount of buffer used is in the range of from 50 to 1300 parts per million.

Claim 11

A process as in claim 7 wherein the buffer is selected from the group consisting of Clark and Lubs phosphate, citrate, phthalate and borate buffers.

Claim 12

A process as in claim 7 wherein the buffer is a MacIlvaine's citrate/phosphate buffer.

Claim 13

A process for stabilizing the viscosity of a plasticized polyvinyl butyral resin which process comprises incorporating into the polyvinyl butyral resin from 50 to 1300 parts (dry basis) per million of a buffer, which when prepared as an aqueous solution has a pH in the range of from 3 to 7 wherein the buffer is incorporated into the resin prior to fabricating the resin into a shaped article in order to minimize changes in the viscosity of the polyvinyl butyral resin, wherein at least one component of the buffer is at least a bidentate ligand with the ability to interact with a metal to form a chelated ring structure and wherein the buffer is substantially free from hydrochloric, nitric and sulfuric acid components; wherein the buffer is selected from the group consisting of Clark and Lubs phosphate, citrate, phthalate and borate buffers and MacIlvaine's citrate/phosphate buffers.

Claim 14

A process for stabilizing the viscosity of a plasticized polyvinyl butyral resin which process comprises incorporating into the polyvinyl butyral resin from 50 to 1300 parts (dry basis) per million of a buffer, which when prepared as an aqueous solution has a pH in the range of from 3 to 7 wherein the buffer is incorporated into the resin prior to fabricating the resin into a shaped article in order to minimize changes in the viscosity of the polyvinyl butyral resin, wherein at least one component of the buffer is at least a bidentate ligand with the ability to interact with a metal to form a chelated ring structure and wherein the buffer is substantially free from hydrochloric, nitric and sulfuric acid components; wherein the buffer is selected from the group consisting of Clark and Lubs phosphate, citrate, phthalate and borate buffers and MacIlvaine's citrate/phosphate buffers.

Claim 15

A polyvinyl acetal interlayer for laminated safety glass which is stabilized according to the process of claim 1.

Claim 16

A plasticized polyvinyl butyral interlayer for laminated safety glass which is stabilized according to the process of claim 7.

Claim 17

A plasticized polyvinyl butyral interlayer for laminated safety glass which is stabilized according to the process of claim 11.

Claim 18

A process as in claim 1 wherein the buffer is added to the resin in the form of an aqueous solution.

Claim 19

A process as in claim 11 wherein the buffer is added to the resin in the form of an aqueous solution.