JPS5936946B2 - Method for making polyvinyl alcohol polymer water resistant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyvinyl alcohol (hereinafter abbreviated as PVA) with good water resistance.

Since PVA forms a strong film, it is used in various films, and has a wide range of uses such as fiber pastes, paper processing agents, and adhesives. However, because it is a water-soluble polymer, its uses are limited, and many attempts have been made to improve its water resistance. A conventionally known method for making water resistant is to coat PVA with a coating of 160~
A method of heating to about 200° C., a method of adding a crosslinking agent or a crosslinking aid, and a method of acetalizing or esterifying PVA are known.

As a crosslinking agent or crosslinking aid, aldehydes such as formalin and gluoxal, N such as methylolmelamine, etc.
- Methylol compounds, divinyl sulfone, bis(β-hydroxyethyl) sulfone, disodium tris(β-
activated vinyl compounds such as (sulfoethyl) sulfonium, epoxy compounds such as epichlorohydrin, dicarboxylic acids such as dicarboxylic acid chlorides and acid anhydrides, disulfide compounds, imide compounds such as diisocyanates,
Complexing agents containing inorganic substances such as Cu, B, Al, Ti, Zr, Sn, V, and C are known.

However, since the method of heating the PVA film formed thereon requires a relatively high temperature, there is also a concern that the film may be colored.

In addition, the effects vary significantly depending on the degree of saponification, and PVA with a low degree of saponification cannot be expected to be very effective. The latter two require adjustment of the reaction conditions to make them water resistant, such as strong alkalinity or acidity, and many require relatively high reaction temperatures, and there is also concern about the volatilization and generation of toxic substances during the reaction. There are many things that are done.

Furthermore, even if the reaction conditions are relatively mild, the reaction with PVA proceeds as soon as it is added, causing a rapid increase in the viscosity of the system, which often becomes a hindrance to subsequent molding and processing.

Therefore, the present inventors discovered that water resistance occurs under mild conditions, and
Moreover, as a result of intensive research into a method that does not cause sudden changes in the viscosity of the system and does not cause concerns about the volatilization or generation of toxic substances during the reaction,
The present invention has now been accomplished.

That is, the feature of the present invention is that a premixed titanium compound and a zirconium compound are mixed with PV in the presence of water.
Water resistance can be imparted to PVA by simply mixing it with the A-based polymer and drying it in air or by heating, eliminating the need to control the pH of the system, add catalysts, etc., or take measures against changes in the viscosity of the stock solution over time. It is a point. Examples of the titanium compound used in the present invention include titanyl sulfate, α
-Titanic acid, potassium titanium oxalate, ammonium titanium oxalate, tetra-n-butyl titanate, titanium triethanolamine, etc., and examples of zirconium compounds include zirconium acid chloride, zirconyl ammonium carbonate, zirconyl ammonium acetate, and zirconium lactate. etc. can be exemplified.

The PVA-based polymer to be made waterproof in the present invention includes any copolymer having a vinyl alcohol unit as a main repeating unit, including PVA having any degree of polymerization or saponification.

The amount of the mixture of titanium compound and zirconium compound added to the PVA-based polymer and the mixing ratio of the titanium compound and zirconium compound are determined to what extent the PVA-based polymer is made water resistant or to what extent the system is thickened. The amount of the mixture to be added should preferably be 5 to 100 PHR to the PVA polymer, and the ratio of the titanium compound to the zirconium compound should be 1/1.5, although there is no particular limitation. ~1/10 is suitable.
It should be noted that it is difficult to obtain sufficient water resistance when the amount of the mixture added is less than 5 PHR, and that a relatively high proportion of titanium compound knobs in the mixture tends to rapidly increase the viscosity of the system. There is.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 PVA (saponification degree 99.9 mol%, polymerization degree 1700) 5
% aqueous solution, a 2% titanyl sulfate solution, a 35% zirconium acid chloride solution, and a mixed solution of these titanyl sulfate solutions and zirconium acid chloride solutions were added separately to make a homogeneous solution, and then placed on a glass plate. It was cast and air-dried.

1 molded colorless transparent film with a thickness of 0.111
Heat treatment was performed at 300C for 10 minutes without tension. Table 1 shows the results of measuring the properties of the film. Furthermore, PVA (
Saponification degree 99.9 mole? , degree of polymerization 1700) 10% titanyl sulfate solution in 5% aqueous solution, 35% zirconium acid chloride
solution, and a mixture of these with titanyl sulfate solution and zirconium acid chloride solution, and B8 at 25°C.
The solution viscosity was measured using an H-type viscometer (manufactured by Tokyo Keiki Co., Ltd.),
The results are shown in Table 1.

As shown in the table above, the poor moldability and processability due to gelation of PVA caused by titanyl sulfate alone, and the poor hot water resistance caused by zirconium oxychloride alone, can be significantly improved by adding a mixture of titanyl sulfate and zirconium oxychloride. You can see that it has been improved.

Example 2 PVA (saponification degree 99.9 mol%, polymerization degree 1
700) 5% aqueous solution, 10% titanyl sulfate solution, α-titanic acid 10% aqueous solution, 35% zirconium acid chloride solution,
A mixed solution of these titanyl sulfate solution and zirconium acid chloride solution was added, and the solution viscosity was measured at 25° C. using a B8H type viscometer.

As shown in the table above, it is clear that the addition of a pre-mixed titanium compound and zirconium compound prevents a rapid increase in the viscosity of the system, and this makes it easier to handle when the stock solution is used for various molding and processing purposes.

Example 3 PVA (saponification degree 99.9 mol%, polymerization degree 1700)5
% aqueous solution, 10 PHR of a mixed solution of 10% titanyl sulfate solution and 35% zirconium acid chloride solution was added, and the mixture was heated at 25°C.
The solution viscosity was measured using a B8H type viscometer.

As shown in the table above, when the proportion of titanium compounds in the mixture is relatively high, the viscosity of the system tends to increase rapidly, so care must be taken in molding and processing.

Claims (1)

[Claims] 1. A method for making a polyvinyl alcohol polymer waterproof, which comprises preparing a mixture of a titanium compound and a zirconium compound in advance, adding the mixture to a polyvinyl alcohol polymer in the presence of water, and then drying the mixture.