READY-MIXED DRYING-TYPE JOINT COMPOUNDS CONTAINING pH BUFFER SYSTEMS

1 . A ready-mixed, drying-type joint compound comprising a mixture of joint compound components and water;

the joint compound components comprising:

a filler at about 50 wt. % to about 98 wt. % of the joint compound on a dry basis,

a binder at up to about 15 wt. % of the joint compound on a dry basis;

a polymeric thickener at up to about 3 wt. % of the joint compound on a dry basis;

a pH buffer system comprising a weak acid and a conjugate base of the weak acid, at about 0.01 wt. % to about 1.0 wt. % of the joint compound on a dry basis; and

an additive up to about 10 wt. % of the joint compound on a dry basis, wherein optionally the additive comprises an accelerator and/or a rheology modifier;

wherein weight ratio of the water to the dry joint compound components is about 1:6 to about 3:1,

wherein at least one of the joint compound components is alkali sensitive.

2 . The joint compound of claim 1 , wherein the pH buffer system comprises sodium carbonate and sodium bicarbonate.

3 . The joint compound of claim 1 , wherein the pH buffer system comprises K 2 HPO 4 and K 3 PO 4 .

4 . The joint compound of claim 1 , wherein the pH is 9-11.

5 . The joint compound of claim 1 , wherein the pH buffer system comprises ammonia and ammonia chloride.

6 . The joint compound of claim 1 , wherein the alkali sensitive component comprises one or more of the rheology modifier, the binder, and the additive.

7 . The joint compound of claim 1 , wherein the alkali sensitive component comprises the rheology modifier.

8 . The joint compound of claim 1 , wherein the alkali sensitive component comprises the binder.

9 . The joint compound of claim 1 , wherein the alkali sensitive component comprises the additive.

10 . The joint compound of claim 1 , wherein:

the filler is at about 50 wt. % to about 93 wt. % of the joint compound on a dry basis;

the binder is up to about 8 wt. % of the joint compound on a dry basis;

the polymeric thickener is up to about 2 wt. % of the joint compound on a dry basis;

the pH buffer system is at about 0.025 wt. to about 0.15 wt. % of the joint compound on a dry basis; and

the additive is up to about 10 wt. % of the joint compound on a dry basis wherein optionally the additive comprises an accelerator and/or a rheology modifier;

wherein the weight ratio of the water to the dry joint compound components about 1:6 to about 3:1.

11 . The joint compound of claim 1 , wherein:

the filler is at about 65 wt. % to about 93 wt. % of the joint compound on a dry basis;

the binder is up to about 4 wt. % of the joint compound on a dry basis;

the polymeric thickener is about 0.1 wt. % to about 2 wt. % of the joint compound on a dry basis;

the pH buffer system is at about 0.05 wt. to about 0.10 wt. % of the joint compound on a dry basis;

the additive is about 0.1 wt. % to about 10 wt. % of the joint compound on a dry basis, wherein optionally the additive comprises an accelerator and/or a rheology modifier; and

wherein the weight ratio of the water to the dry joint compound components is about 1:3 to about 1:1.

12 . The joint compound of claim 1 , wherein the filler comprises calcium carbonate, calcium sulfate dihydrate, talc, glass micro bubbles, mica, perlite, pyrophyllite, silica, calcium sulfate anhydrite, diatomaceous earth, clay, resin microspheres, or mixtures thereof.

13 . The joint compound of claim 1 , wherein the joint compound has a pH of 8-12 for 120 days or more at 75° F. (23.9° C.) in a sealed container.

14 . The joint compound of claim 1 , further comprising up to 0.1 wt. % biocide.

15 . The joint compound of claim 1 , comprising:

Calcium carbonate,

Clay,

Perlite,

Hydroxyl ethylcellulose,

Sodium nitrite,

Starch,

Polyvinyl alcohol,

hydroxyl propyl methyl cellulose,

Bleach solution,

latex,

preservative,

plasticizer,

PEG 750,

Water and

the pH buffer system.

16 . The joint compound of claim 15 , wherein the pH buffer system comprises Na 2 CO 3 *10H 2 O and NaHCO 3 .

17 . The joint compound of claim 1 , wherein the pH buffer system is at about 0.01 wt. % to about 0.25 wt. % of the joint compound on a dry basis.

18 . The joint compound of claim 1 , wherein the pH buffer system is at about 0.025 wt. % to about 0.5 wt. % of the joint compound on a dry basis.

19 . A method of using the joint compound of claim 1 , comprising applying the joint compound to one or more of the group consisting of boards, joint tape, and another layer of the joint compound.

20 . A method of making the joint compound of claim 1 , comprising combining the at least one filler, the binder, the polymeric thickener, the pH buffer system, and the additive.