JPS60190223A - Emulsion and dispersion stabilizer - Google Patents

Abstract

PURPOSE:To obtain a stabilizer excellent in emulsifying and dispersing stability, by saponifying multi-branched polvinyl ester by a solvent mixture containing methanol and having dielectric constant of 18-27 (C.G.S.e.s.u). CONSTITUTION:A polyvinyl ester type polymer of which the branching degree (the polymerization degree of polyvinyl ester/that of perfectly saponified polyvinyl alcohol obtained by perfectly saponifying polyvinyl ester-1) is 1 or more, such as vinyl formate, vinyl acetate or vinyl propionate is saponified in a solvent mixture, which is prepared by mixing methanol and a solvent (benzene, toluene, xylene) in a wt ratio of 40/60-90/10 at 10-70 deg.C. NaOH, KOH or LiOH is used as a saponification catalyst.

Description

Detailed Description of the Invention A Technical Field of the Invention The present invention is directed to aqueous polyvinyl alcohol-based emulsion polymerization stabilizers, suspension polymerization stabilizers, and hydrophobic compound emulsion dispersion stabilizers with excellent emulsion dispersion stability. This invention relates to an emulsion dispersion stabilizer.

In recent years, stable emulsions have been created by emulsion polymerization of ethylenically unsaturated monomers, such as vinyl acetate, alone or together with ethylene, acrylic esters, etc. in an aqueous medium in the coexistence of water-bathable emulsion-stable vesicle colloids. It is widely used in applications such as agents, paints, and paper processing agents. As a water-soluble protective colloid, a large amount of partially saponified PvA is used in polyvinyl alcohol polymer (PVA, sometimes abbreviated) to create an emulsion with good adhesiveness and excellent mechanical performance. .

However, the current PVA-based emulsion polymerization stabilizers do not necessarily have sufficient emulsion polymerization stabilizer ability, and it is desired to have a high stability performance that can provide stability with a smaller amount.

Furthermore, PVA, particularly partially saponified PVA, is used as a suspension polymerization stabilizer when ethylenically unsaturated monomers such as vinyl chloride and styrene are suspended in an aqueous medium. The role of suspension polymerization stabilizer in suspension polymerization is very important.
A stabilizer with better stability performance is desired. In particular, it has excellent dispersion stability performance as a stabilizer during suspension polymerization of vinyl chloride, has excellent demerization properties from vinyl chloride resin powder, has excellent plasticizer absorption, has uniform porosity, and has granular properties. There is a need for a suspension polymerization stabilizer that can be used to replace large-diameter vinyl chloride resin particles.

In many cases, lipophilic water-insoluble substances are emulsified and dispersed in an aqueous medium.

In this case, low-molecular surfactants are generally used as emulsifying and dispersing agents. Although it is possible to obtain a somewhat stable emulsion by appropriately selecting a low-molecular-weight surfactant, it is difficult to obtain a stable emulsion with high viscosity, and the stability at low temperatures or when mechanical shearing force is applied is poor. However, the development of polymeric surfactant-based emulsification and dispersion stability is awaited. Since conventional PVA does not necessarily have a sufficiently high surfactant ability, many difficulties arise when it is used as an emulsion dispersion stabilizer.

As described above, PVA is widely used as an emulsion polymerization stabilizer, suspension polymerization stabilizer, and emulsion stabilizer for lipophilic water-insoluble substances by utilizing its surface-active properties, but the quality requirements in these fields are not met. Because of the need for sophistication, cost reduction, etc.::IIi, a PVA-based stabilizer with better surfactant performance is desperately needed.

■3 Prior art and its problems The PVA conventionally used as an emulsion dispersion stabilizer is a polyvinyl ester obtained by radical solution polymerization of vinyl ester monomers such as vinyl acetate in methanol, after the residual monomers are separated and removed. A typical example is water-soluble PVA saponified in methanol with an alkali catalyst such as sodium hydroxide.

PV, a parameter indicating the performance of an emulsion dispersion stabilizer
The surface tension of the aqueous solution, the emulsification brim of the vinyl acetate monomer, the protective colloidal properties, etc. are superior to partially saponified products with a lower degree of saponification than to completely saponified products with a higher degree of saponification.
Partially saponified products are mainly used as emulsion dispersion stabilizers.

However, PVA with a low saponification degree has a high saponification degree P
It has various problems such as lower water resistance than VA, becoming insoluble in water if the degree of saponification becomes too low, and showing a cloud point phenomenon in which it is soluble in water at low temperatures but precipitates at high temperatures.
It is difficult to extremely lower the degree of saponification.

In an attempt to obtain PVA with higher emulsion dispersion stability at the same saponification degree, polyvinyl acetate obtained by ordinary methanol solution polymerization was used as a solvent during saponification, and a mixed solvent was prepared by mixing solvents such as methyl acetate and benzene with methanol. It is known to saponify in the system. It has been shown that the partially saponified PVA obtained by this method has a lower surface tension in its aqueous solution than that saponified with methanol alone, making it possible to produce an emulsion dispersion stabilizer with better surfactant ability. .

However, the increase in surfactant ability is still not sufficient, and there is currently a need for a PVA-based emulsion dispersion stabilizer having higher surfactant ability and emulsion-protecting colloidal performance.

C fII structure, purpose and effect of the present invention As a result of intensive studies in view of the above situation, the present inventors unexpectedly found that a specific highly branched polyvinyl acetate polymer (hereinafter referred to as PVAc polymer) with a degree of branching of 1 or more Polyvinyl esters such as (sometimes abbreviated as "coalescence") are mixed with methanol and a solvent with a small dielectric constant to give a dielectric constant of 18 to 27 (C, G, S, e,
s, u; Units are omitted hereafter) Water-soluble partially saponified PVA with a saponification degree of 50 to 95 molar obtained by saponification in a specific mixed solvent system prepared is a normal, less-branched PVA with a degree of branching of less than 1. It is an excellent emulsion dispersion stabilizer that has much superior surfactant ability and emulsion-protecting colloidal performance compared to the partially saponified PVA obtained by saponifying the PVA c-based polymer in the above-mentioned mixed solvent system. Heading Developing the Invention.

By using the emulsion dispersion stabilizer such as the water-soluble partially saponified PVA of the present invention, emulsion polymerization or suspension polymerization can be carried out stably, and excellent emulsions and particulate polymers can be obtained. Furthermore, a stable aqueous dispersion emulsion can be obtained by emulsifying a hydrophobic substance using the water bathable emulsion dispersion stabilizer made of partially saponified PVA of the present invention.

D More detailed description of the present invention The emulsion dispersion stabilizer of the present invention is produced by saponifying a specific highly branched polyvinyl ester polymer with a degree of branching of 1 or more in a mixed solvent system containing methanol and having a dielectric constant of 18 to 27. The degree of saponification of the vinyl ester moiety obtained by
It consists of 95% water-soluble, partially saponified PVA.

The degree of branching here indicates the average degree of branching of the polyvinyl ester polymer, and is expressed by the following formula.

Degree of branching = (degree of polymerization of polyvinyl ester/polymerization of fully saponified polyvinyl alcohol obtained by completely saponifying polyvinyl ester) -1 The degree of polymerization in the above formula means that for polyvinyl ester, the intrinsic viscosity at 30°C in acetone, completely For saponified PVA, the intrinsic viscosity at 30°C in water was measured, and the so-called tangent method (Ichi Sakurada et al.: Industrial Chemistry Magazine ■, 135-137 (19
It was celebrated in April.

Of course, the highly branched polyvinyl ester of the present invention is unsuitable if it has a degree of branching of 1 or more, preferably 2 or more as shown in the above formula, and is insoluble in a combined solvent system.

Polyvinyl ester with a high degree of branching can be produced by increasing the polymerization rate to a high polymerization rate, but polymerization using the suspension '21 method or emulsion polymerization method is
Highly branched polyvinyl esters are preferred because they can easily be used. Particularly preferred is suspension polymerization.

As vinyl esters, individual polymerizable and saponifiable vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, etc. can be used, but especially vinyl acetate is used industrially. It is preferred because it can be obtained at low cost and has good polymerization and saponification properties.

A suspension polymerization method or a suspension polymerization stabilizer such as a vinyl ester such as vinyl acetate in an aqueous solution containing a partially saponified PVA and a radical polymerization initiator sparingly soluble in water such as azobisisobutyronitrile or lauryl peroxide. This is carried out by adding an initiator such as benzoyl peroxide, stirring, and heating and polymerizing the suspension. In order to obtain a highly branched polyvinyl ester with a degree of branching of 1 or more, the polymerization rate should be set to 5.
It is desirable to increase the height to 0 inches or more, preferably 70 inches or more.

The degree of polymerization of polyvinyl ester can be lowered by adding a chain transfer agent during polymerization.

Furthermore, a vinyl ester copolymer obtained by copolymerizing a vinyl ester monomer and a comonomer copolymerizable with the vinyl ester monomer can also be used.

The method of emulsion polymerization using a water-soluble initiator with or without an emulsion stabilizer is also useful as a method to obtain a well-branched polyvinyl ester with a degree of branching of 1 or more, but the separation of the polymer is not easy. is disadvantageous compared to the suspension method.

The obtained polyvinyl ester polymer is saponified after removing and separating unpolymerized vinyl ester monomers. At that time, a mixed solvent containing methanol and having a dielectric constant of 18 to 27 is used as the saponification solvent. There is a need to turn it into a metal. By partially saponifying polyvinyl ester with a degree of branching of 1 or more using a specific mixed solvent system containing methanol with a dielectric constant of 18 to 27 at tTi, the significantly superior surfactant ability and emulsion-protecting colloid performance of the present invention can be obtained. As is clear from Comparative Example 3 below, ordinary polyvinyl ester with a low degree of branching of less than 1 is suspended with a methanol-containing mixed solvent thread having a dielectric constant of 18 to 27. Partially phosphorized PVA obtained by oxidation and highly branched polyvinyl ester with a degree of branching of 1 or more can be used with i! Partially saponified PVA obtained by saponification in methanol with a high ratio of 32.6 (Comparative Example 1) cannot provide an excellent emulsion dispersion stabilizer like the one of the present invention.

The dielectric constant of the mixed solvent system containing methanol of the present invention is 25
Means the value measured by the bridge method at a temperature of °C. (Units are C, G, S, e, s, u,) The dielectric constant of methanol is 32.6, and by mixing a solvent with a small percentage visit rate with methanol, a mixed solvent with a dielectric constant of 18 to 27 can be created. Can be adjusted.

Although a wide range of solvents can be used as the solvent to be mixed with methanol, it is desirable that the resulting mixed solvent be capable of dissolving polyvinyl ester.

For example, aromatic hydrocarbons such as benzene, toluene and xylene, esters such as methyl acetate and ethyl acetate fJJ, L4
Examples include solvents with a low dielectric constant of 10 or less, such as dioxane and ethyl ether. Particularly, aromatic hydrocarbons such as benzene, toluene, and xylene are preferable because partially saponified PvA exhibits excellent emulsion dispersion stability performance.

The mixing ratio of methanol and the solvent to be mixed is selected so that the resulting mixed solvent system has a dielectric constant of 18 to 27, but in order to obtain a significant mixing effect, methanol/methanol/ Solvent to mix = 40150-90/1
0 is preferable, more preferably 40/60 to 80/20, especially 50/! 50-70/30 is preferred.

Methanol is necessary for metathurisis in the saponification reaction and is consumed as methyl ester, so if the methanol content becomes too small, the saponification reaction will slow down, which is undesirable. Further, it is preferable that the amount of mixed solvent used is at least twice the amount of methanol required for saponification.

The saponification catalyst is preferably an alkaline catalyst such as sodium hydroxide, potassium hydroxide, lithium hydroxide, or sodium methylate. The degree of saponification can be adjusted by changing the amount of saponification catalyst used, and the amount used is determined as appropriate depending on the amount of water in the system. It is desirable to use 0.001 or more, preferably 0.002 or more in molar ratio to the vinyl ester unit. Saponification temperature is usually 10-70℃
Preferably, the temperature is selected from the range of 20 to 60°C. Not only anhydrous methanol but also a small amount of water-containing methanol can be used.

The 1'VA of the present invention needs to be a water-soluble, partially saponified PVA with a degree of saponification of vinyl ester units of 50 to 95 mol, preferably 60 to 90 mol.

Highly saponified PVA with a molar ratio exceeding 95 cannot achieve the emulsion dispersion stability that is a feature of the present invention;
On the other hand, if it is less than 50 molar, sufficient water solubility cannot be achieved, which is not preferable.

In addition, the water-soluble partially saponified PVA referred to in the present invention includes those that completely dissolve in water to those that disperse and dissolve in water.
Includes those that have emulsification and dispersion stability in water.

The degree of polymerization of the partially saponified PVA of the present invention is not particularly limited, but is preferably 50 to 5,000, preferably 100 to 3,000. The degree of polymerization can be determined by measuring the limiting viscosity in water at 30° C. and using the tangent equation described above.

The emulsion dispersion stabilizer made of water-soluble partially saponified PVA of the present invention is characterized by having significantly superior surfactant ability and emulsion-reflecting colloidal performance compared to conventional PVA-based emulsion dispersion stabilizers. be. Therefore, it is useful as an emulsion polymerization stabilizer for vinyl monomers such as vinyl esters, and has good stability during emulsion polymerization of vinyl acetate, etc., and the resulting emulsion has a small particle size and can be converted into a stable emulsion with high viscosity. . It can also be used as an emulsion polymerization dispersion stabilizer for polymerization of acrylic, styrene, vinyl chloride, styrene-butadiene, etc.

A further characteristic feature is that the water-soluble partially saponified PV of the present invention
The emulsion dispersion stabilizer consisting of A has excellent emulsion dispersion stability and is useful as a suspension polymerization stabilizer for vinyl monomers such as vinyl chloride and styrene. In particular, when used as a suspension polymerization stabilizer for vinyl chloride, more uniformly porous vinyl chloride resin particles can be obtained, and it also has excellent characteristics in terms of demonomer properties and plasticizer absorption properties.

It can also be used as an emulsion dispersion stabilizer when preparing an aqueous dispersion of lipophilic water-insoluble substances. For example, spindle oil
Lubricating oils such as gear oil, petroleum products such as paraffin wax, liquid paraffin, and asphalt, plasticizers such as dioctyl sebacate and dibutyl phthalate, tar products such as creosote oil and coal tar, turpentine oil, rosin, etc. It can be widely used for emulsifying and dispersing lipophilic water-insoluble substances such as natural drugs, synthetic polymers and oligomers such as polyethylene, polypropylene, polybutene, liquid polybutadiene, and liquid polyimprene.

For use as an emulsion polymerization or suspension polymerization stabilizer, or as an emulsion dispersion stabilizer for lipophilic water-insoluble substances, etc., known methods are employed.

The proportion of PVA of the present invention used as an emulsion dispersion stabilizer is not particularly limited and may be determined as appropriate, but since it has superior emulsion dispersion stability performance compared to conventional PVA, the amount used can be reduced.

The PVA of the present invention may also be used with other known unmodified or modified PV.
There is no problem in using A and surfactants or other types of additives together as long as the purpose of the present invention is not impaired.

The present invention will be explained in more detail below using Examples, but the present invention is not limited to these in any way. Note that parts and parts in the examples are based on weight unless otherwise specified.

Example 1 Synthesis of polyvinyl acetate with a degree of branching of 1 or more In a reaction tank equipped with a stirrer and a cooler, Kuraray Bovar 220E (m
This time = 2050, saponification degree 88 mol qb) 0.05%
To 15,000 parts of an aqueous solution of vinyl acetate monomer (VA
2,790 parts of azobisisobutyronitrile (abbreviated as c), 5.6 parts of azobisisobutyronitrile as an initiator, and 19.5 parts of acetaldehyde as a chain transfer agent for controlling the degree of polymerization were added. After purging the inside of the tank with nitrogen, the internal temperature was raised to 60° C. while stirring, and suspension polymerization was carried out for 5 hours.

The beaded polymer was deliquified and separated, then dried under reduced pressure to remove unreacted monomers and attached water. The obtained peas are dissolved in methanol and methanol vapor is completely blown in to drive out and remove a small amount of unreacted VAc remaining, producing polyvinyl acetate (hereinafter abbreviated as FPVAC) that does not substantially contain residual VAc.
A methanol solution was obtained. The PVAc concentration i was 40%, the TE solution nt was 4900 parts, and the nail base rate of VAc was 70%.

The methanol was removed from the methanol solution of PVAc, the PVAc was taken out, and the acetone solution was heated at 30°C.
The degree of polymerization (PAC) determined by the intrinsic viscosity is 6320
Met.

On the other hand, this methanol solution was heated to 40° C., and then a methanol solution of sodium hydroxide was added to 2 so that the alkali molar ratio to vinyl ester units was 0.1 to completely saponify it. The degree of polymerization (PA) of the completely saponified PVA obtained by washing, purifying and drying the polymer powder was estimated from the intrinsic viscosity of the aqueous solution at 30°C, and the PA was 1,650.

In other words, by calculating according to the above formula, the degree of branching is -2.83
A highly branched PVAc was seen.

(b) PVAcO partial saponification The highly branched fcP with a degree of branching of -2.83 seen above
1 part methanol to 100 parts 40% methanol solution of VAc
5 parts and 80 parts of benzene were added, mixed well, and heated to 50°C. On top of this, add 0% sodium hydroxide while stirring.
．． 52 parts (molar ratio of PVAc to V Ac units 0
．． A solution containing 028) and 5 parts of methanol was added and stirred well. (The saponification solvent system is methanol/benzene-
The dielectric constant is 5o15o (iHt ratio) and 20. )7
After 2 seconds, the whole was gelled and solidified. After 5 minutes, the gel was pulverized with a pulverizer, washed with methanol, and then heated in a mixture of methanol: methyl acetate; water = io:a:o5 (70
~80°G)L, the residual alkali was neutralized with phenolphthalein until the color disappeared. The neutralized polymer was dried at 70°C. Analysis of the polymer revealed that the degree of phosphization was 88.6 molar, and the degree of polymerization was 17290, partially saponified P.
I found out that Koushichi is a VA.

Comparative Example 1 PV with branching degree = 2.83 obtained in Example 1 above
Add 9 parts of methanol to 1xoo parts of 40% methanol solution of A c.
A solution containing 0.3 parts of sodium hydroxide and 5 parts of methanol was further mixed at 50° C., and the mixture was saponified using methanol as a single solvent without benzene. (Dielectric constant of methanol sole solvent system -32.6) Post-treatment was carried out in the same manner as in Example 1 to obtain partially saponified PVA with a degree of saponification of 87.5 molar and a degree of polymerization of 1720.

Comparative Example 2 PV A with branching degree = 2.83 obtained in Example 1 above
Add 2 methanol to 100 parts of 40 timemethanol solution of c.
3 parts and 73 parts of acetone were added and mixed well.

The temperature was raised to 50°C, and a solution containing 0.74 parts of sodium hydroxide and 5 parts of methanol was added and thoroughly stirred for saponification. That is, saponification was performed using a mixed solvent system of methanol/acetone-55/45 (weight ratio), which has a high dielectric constant of 29. Post-treatment was carried out in the same manner as in Example 1 to obtain partially saponified PVA with a saponification degree of 88.8 molar and a polymerization degree of 1715.

Comparative Example 3 260 parts of methanol, 740 parts of VAc, and 0 parts of azobisisobutyronitrile were placed in a polymerization tank equipped with a stirrer and a cooler.
．． After addition of 025 parts of nitrogen, the temperature was raised to 60° C. and solution polymerization was carried out for 3 hours while stirring. After cooling the content solution and stopping polymerization,
While adding methanol, evaporate under reduced pressure to remove unpolymerized monomers by azeotropic distillation with methanol, and further concentrate to obtain PV.
PVA c-methanol solution with Ac concentration 40% 10
I got 20 copies. The polymerization rate was 55%. P of PVAc
When AC and PA were measured in the same manner as in Example 1, P
AC=3030, PA=1700, branching degree is 0.7
8, and it was PVAc with not many branches.

Using this PVAc, partially saponified PVA with a saponification degree of 88.6 molar and a polymerization degree of 1750 was saponified in a mixed solvent system (dielectric constant = 20) of methanol/benzene = 50150 (weight ratio) under the same conditions as in Example 1. I got it.

Next, in order to evaluate the emulsion dispersion stability performance of the partially saponified PVA obtained in Example 1 and Comparative Examples 1 and 2.3, the surface tension of the PVA aqueous solution as an index of surfactant ability and the index of protective colloid performance were evaluated. The specific viscosity of the V Ac monomer and PVA aqueous solution mixed emulsion system was measured. The results are shown in Table-1.

Note that the surface tension was measured at 20°C for a 0.2% PVA aqueous solution, and the specific viscosity was measured using VAc-
The specific viscosity (ηsp) of the PVA aqueous solution mixed system was determined from the following formula.

ηEM ηsp = −−1 ηPV−OH However, ηEr, l' VAc and the viscosity of the PVA aqueous solution mixed emulsion (20°C1VAc7.87 volume ratio, P
V A 7.5% by weight aqueous solution) ηPV-OH: P
V A Viscosity of 7.5% by weight aqueous solution (20°C)7. / / / /'' , / / /'□' As is clear from Table 1, the PVA of the present invention is extremely excellent in emulsion dispersion stability performance, and the PVA of the present invention is highly branched with a degree of branching of 1 or more. It can be seen that an emulsion dispersion stabilizer with extremely excellent emulsion dispersion stability performance can only be obtained by saponifying the above in a specific mixed solvent system containing methanol and having a dielectric constant of 18 to 27.

Next, the performance of the partially saponified PVA obtained in Example 1 and Comparative Example 1.2.3 as an emulsion polymerization stabilizer was evaluated by emulsion polymerization of VAc. The results are shown in Table-2. The emulsion polymerization was carried out under the following conditions.

Partially saponified P obtained in Example 1 and Comparative Example 1.2.3
To a solution in which 40 parts of VA was dissolved in 800 parts of ion-exchanged water, 160 parts of VAc was added and the temperature was raised to 68° C. while stirring and mixing, and 1.6 parts of persulfuric acid (IJ) was added and emulsion polymerization was carried out under heating for 3 hours. The polymerization rate was determined by analyzing the residual VAc monomer and the solid content, and the appearance and viscosity of the emulsion particles were measured by microscopic observation to evaluate the performance as an emulsion polymerization stabilizer.

Table 2 As is clear from Table 2, partially saponified PVA of the present invention
However, compared to the comparative example, there were no coarse particles at all, and an emulsion with stable viscosity was obtained, indicating that it is an excellent emulsion polymerization stabilizer.

Example 2 PVAc with a branching degree of -2.83 obtained in Example 1 was prepared in the same manner as in Example 1 except that the amount of sodium hydroxide in Example 1 was changed to 0.58 and the alkali molar ratio was changed to 0.031. Saponified under the same conditions. As a result, partially saponified PVA with a saponification degree of 91.7 molar and a polymerization ratio of 1725 was obtained. The surface tension of the observed 0.2 aqueous solution of partially saponified PVA is 52 d.
yne 7cm 1 The specific viscosity (ηsp) is 25, and the saponification degree is 4.
Although it was high, it was found that the emulsion dispersion stability was excellent.

Example 3 PVAc with a degree of branching = 2.83 obtained in Example 1,
Methyl acetate was used to replace benzene in Example 1, and the mixing ratio with methanol was methanol/methyl acetate = 58/42.
Saponification was carried out under the same conditions as in Example 1 except that (R amount ratio) (dielectric constant of mixed solvent system = 26). As a result, partially saponified PVA with a saponification degree of 87.4 molar and a polymerization degree of 1720 was obtained.
It was observed. The surface tension of the observed 0.2% aqueous solution of partially saponified PVA was 50 dyne/cm, and the specific viscosity (η8p
) was found to be an excellent emulsion dispersion stabilizer.

Example 4 PVAc with a degree of branching = 2.83 obtained in Example 1 was prepared using 1,4-dioxane instead of benzene in Example 1,
Saponification was carried out under the same conditions as in Example 1, except that the mixing ratio (weight ratio) of methanol and 1,4-dioxane was 55/45 (dielectric constant of the mixed solvent system -26).

As a result, partially saponified PVA with a saponification degree of 88.4 molar and a polymerization degree of 172° was obtained. 0.2 of PVA obtained
The aqueous solution had a surface tension of 49.5 dyne/α and a specific viscosity (ηsp) of 32, and was found to be an excellent emulsion dispersion stabilizer.

Example 5 PVAc having a degree of branching of 2.83 obtained in Example 1 was saponified under the same conditions as in Example 1 except that xylene was used instead of benzene. (Dielectric constant of mixed solvent system -20) As a result, degree of saponification is 88.5 molar, degree of polymerization is 1
730 partially saponified PVA was obtained. obtained PVA
The surface tension of a 0.2% aqueous solution of is 49 dyne/ly
n and specific viscosity (ηsp) of 37, it was found to be an excellent emulsification and dispersion stabilizer.

Example 6 PVAc with a branching degree of -2.83 obtained in Example 1 was mixed with the benzene mixture ratio of methanol/benzene -7 in Example 1.
0/30 (weight ratio) (dielectric constant of mixed solvent system = 26.5)
Saponification was carried out under the same conditions as in the example except for the following. As a result, partially saponified PVA with a saponification degree of 88.7 molar and a polymerization degree of 1725 was found. The surface tension of the obtained 0.2-inch aqueous solution of PVA is 50.5 dyne/c1n, and the specific viscosity (ηs
p) = 10, it was found to be an excellent emulsion dispersion stabilizer.

Example 7 (a) Synthesis of PVAc with a degree of branching of 1 or more The amount of acetaldehyde used was 70% in the same manner as in Example 1.
suspension polymerization was carried out under the same conditions as in Example 1 except that the amount of azobisisobutyronitrile was changed to 8.5 parts and the amount of azobisisobutyronitrile was increased to 8.5 parts.

'Xll''AC=9,050, PA=600, degree of branching 1
A 60-thimethanol solution of 4.1-branched PVAc was obtained. The polymerization rate of PVAc was 91%.

(b) Saponification of PV Ac 25 parts of methanol and 70 parts of benzene were added and mixed to 100 parts of the above 60 timemethanol solution of PVAc, and the mixture was heated to 40°C. Next, 0.54 parts of potassium methoxide and 5 parts of methanol were added and stirred thoroughly for saponification. (The saponification solvent system was methanol/benzene-50150 (weight ratio), and its dielectric constant was 20.) Post-treatment was carried out in the same manner as in Example 1 to obtain partially saponified PVA. The obtained PVA has a degree of saponification of 87.5 mol% and a degree of polymerization of 620, the surface tension of its 0.2% aqueous solution is 45 dyne 7 cm, and the specific viscosity (ηs
p) was found to be an excellent emulsion dispersion stabilizer at 38.

Example 8 PVAc with a degree of branching = 14.1 obtained in Example 7 was saponified under the same conditions as Example 7 except that the amount of potassium methylate used in Example 7 was changed to 0.29 parts. degree 75
Partially saponified PVA with a molar ratio and a polymerization degree of 6250 was obtained.

Comparative Example 4 PVAC with a degree of branching of -0.52 obtained by solution polymerizing VAc at 60°C with a methanol concentration of 60°C using azobisinobutyronitrile as an initiator to a polymerization rate of 50° was used in Example 8 above.
Saponified under the same conditions as , saponification degree 76 molar, polymerization degree 6
30 partially saponified PVA were obtained.

Partially saponified PVA found in Example 8 and Comparative Example 4 above
When vinyl chloride was subjected to suspension polymerization using PVA as a suspension polymerization stabilizer, as shown in Table 3, □ Partially saponified PVA of the present invention
Compared to the case of Comparative Example 4, this resin is a highly porous vinyl chloride resin with easy removal of vinyl chloride monomers, excellent plasticizer absorption, and is an excellent suspension polymerization stabilizer. Understood. The suspension polymerization of vinyl chloride was carried out under the following conditions.

101 Glass-lined autoclave with deionized water 4
0 parts, 0175 parts of the 2-weight multi-aqueous solution of the partially saponified PVA obtained in Example 8 and Comparative Example 4, and 0.009 parts of the 50-weight toluene solution of diisopropyl peroxydicarbonate were charged, and the autoclave was heated to 50 mR.
After degassing to remove oxygen until P was removed, 30 parts of vinyl chloride 7-mer was charged, and the temperature was raised to 57° C. with stirring to carry out polymerization.

Ten hours after the start of polymerization, the polymerization was stopped, unreacted vinyl chloride monomer was purged, and the contents were taken out and dehydrated and dried. The observed performance of vinyl chloride resin is shown in Table 3.

Table 3 Note (1) Uniformity of particle porosity: 100 parts of vinyl chloride resin, 50 parts of plasticizer (DOP dioctyl phthalate), 1 part of diptyltin malate, 1 part of cetyl alcohol, 0.2 s B of titanium white ( (A mixture of 0.1 part of carbon blank was kneaded with a roll at 150°C for predetermined times of 3 minutes, 5 minutes, and 7 minutes to create a sheet with a wall thickness of 0.2 #I11,
Light was transmitted through this and the number of fish eyes contained in each 100 sheets was counted.

The more the fish eyes disappear in a short time, the more uniform the particle porosity is. 100 parts of vinyl chloride resin and 50 parts of DOP (dioctyl phthalate) were put into a container, and while stirring, the kneading torque was recorded at each hour, and the time at which the kneading torque decreased was expressed as an example of the mixing time. The smaller the number, the better the plasticizer absorption.

Note (8) Residual chloride and vinyl monomer: A certain amount of vinyl chloride resin was dissolved in tetrahydrofuran, and the vinyl chloride monomer content in the vinyl chloride resin was determined by gas chromatography.

Example 9 50 parts of water and VAClO were added to a polymerization tank equipped with a cooler and a stirrer.
%, versatility”) phosphoric acid chloride = /l/ (VeoVa.

Shell Chemical) o, t 6 parts, acetaldehyde 0
．． After adding 01 parts of nitrogen and replacing with nitrogen, 70.03 parts of ammonium persulfate was added.
and emulsion polymerization was carried out at 70 to 80° C. for 80 minutes while stirring.

After the reaction, the turbid solution was salted out, washed with water, dried, dissolved in methanol, and reprecipitated with water, which was repeated twice to purify and dry. The polymerization rate was 89%. As a result of analyzing the observed polymer, VAc-Ve containing 0.7 mol of VeoVa was found.
The degree of branching of the oVa copolymer was 6.5.

40 parts of the resulting copolymer was dissolved in 75 parts of methanol and 80 parts of benzene, the temperature was raised to 40°C, and 0.0% of sodium hydroxide was added.
A solution of 5 parts of methanol and 5 parts of methanol was added for saponification. (Dielectric constant of saponified mixed solvent system = 20) Post-treatment was carried out in the same manner as in Example 1 to obtain a polymer having a saponification degree of 87.5 molti and a polymerization degree of 1650.

Comparative Example 5 Branching degree obtained in Example 9; VAc-VeoV of 6.5
Copolymer a was saponified under the same conditions as in Example 9, except that the benzene of Example 9 was not mixed and dissolved in 155 parts of methanol alone, and the degree of saponification was 87.3 mol%.
A polymer with a degree of polymerization of 1630 was obtained.

In Example 9 and Comparative Example 5, as a result of nuclear magnetic resonance spectroscopy, the final polymers obtained in each case showed that VeoVa units remained unsaponified, and polyvinyl alcohol containing VeoVa units was found. It turned out to be a copolymer.

In order to evaluate the emulsion dispersion stability performance of the polyvinyl alcohol copolymers obtained in Example 9 and Comparative Example 5, 0.2
% aqueous solution and the dispersion specific viscosity (ηsp) of the VAc monomer, it was found that the emulsion dispersion stability of the present invention was significantly superior to that of Comparative Example 5, as shown in Table 4. It was done.

Table 4 Example 10 Example 10 PVAc was polymerized under the same conditions as Example 1 except that the polymerization time was 3 hours.
I got 1 or 2 PVAc. Perform this PVAc9IJ
When saponification was performed under the same conditions as in 1 using a methanol/benzene = 50150 mixed solvent system (dielectric constant of the mixed solvent system = 20), the degree of saponification was 88.7. Partial saponification with a degree of polymerization of 1770)
'VAi got it. This PvA 0.2 aqueous solution had a surface tension of 50.5 dyne 7 cm, a specific viscosity (ηsp) of 9, and exhibited emulsion dispersion stability superior to that of Comparative Example 3.

Sincerely, Kuraray Co., Ltd. Representative Patent Attorney Ken Honda

Claims (1)

[Scope of claims] (υ degree of branching (degree of branching = (degree of polymerization of polyvinyl ester/degree of polymerization of fully saponified polyvinyl alcohol obtained by completely saponifying polyvinyl ester) - 1) is 1 or more, and is highly branched. A saponification degree of 50 to 95 obtained by saponifying an ester in a mixed solvent system containing methanol and having a dielectric constant of 18 to 27 (C-G-S, e, s, u).
An emulsifying and dispersing stabilizer made of water-soluble partially saponified polyvinyl alcohol. (2) Emulsifying dispersion stabilizer 0 (81 mixture of methanol and aromatic hydrocarbons) according to claim 1, wherein the mixed solvent system containing methanol is a mixed solvent system of methanol and aromatic hydrocarbons. The emulsion dispersion stabilizer according to claim 2, wherein the mixing ratio of the solvent is methanol/aromatic hydrocarbon = 40/60 to 90/10 on a weight basis. (4) The aromatic hydrocarbon is benzene , toluene, and xylene. CB) The polyvinyl ester having one or more branches W is a polyvinyl ester obtained by suspension polymerization. Claim 1 Emulsification and dispersion stabilizer as described in section. (6) The emulsion dispersion stabilizer according to claim 1, wherein the polyvinyl ester having a degree of branching of 1 or more is a polyvinyl ester obtained by emulsion polymerization. (7) The emulsion dispersion stabilizer according to claim 1, wherein the emulsion dispersion stabilizer is a dispersion stabilizer for emulsion polymerization. (8) The emulsion dispersion stabilizer according to claim 1, wherein the emulsion dispersion stabilizer is a dispersion stabilizer for suspension polymerization.