JPS6234043B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a saponified product of an olefin-vinyl ester copolymer without coloring, and specifically, the coloring that occurs during the saponification reaction is prevented by adding an organic peroxide after the saponification reaction. It's a method. In general, saponified ethylene-vinyl acetate copolymers have higher softening temperatures and melting points, as well as higher tensile modulus and hardness, than ethylene-vinyl acetate copolymers. It also has excellent gas barrier properties. Furthermore, it has excellent adhesion to various materials. It also has excellent properties such as low swelling when immersed in various solvents and extremely low permeation of gasoline, and is used in packaging materials, molded products, adhesives, heat sealing materials for textile fibers, glass container coating materials, etc. Used in a wide range of fields. However, when used in these fields, variations in quality due to the coloring of the resin cause problems. Therefore, it is essential to create a saponified product without coloring. Conventionally, many methods have been proposed for saponifying a non-colored ethylene-vinyl acetate copolymer. Broadly speaking, they can be divided into the following two types.
One method is to prevent coloring by adding additives before the saponification reaction or by performing the saponification reaction under special conditions, and the other method is to add additives after the saponification reaction is completed. This is a method for treating colored substances produced by saponification reactions. For example, an example of the former is a method of extremely low copolymer concentration in the saponification reaction (U.S. patent
2386347, Japanese Patent Publication No. 44-27902), and there is also a method of adding ketone compounds such as acetone and higher aldehydes such as butyraldehyde to the saponification reaction system in an amount of 0.1 to 10% by weight based on the alcohol used (Japanese Patent Publication No. 44-27902). 49-17433) etc. However, these methods have low productivity in the saponification reaction, and the cost required for the reaction is extremely high.
Furthermore, the treatment of the solvent generated when recovering the saponification reaction product becomes complicated, and the cost required for this becomes extremely high, which is industrially disadvantageous. Furthermore, examples of preventing (decolorizing) coloring by post-treatment with the latter additive include methods of irradiating ultraviolet rays (Japanese Patent Publication No. 51-35505), chlorine-based oxidizing agents (Japanese Patent Publication No. 51-68693), and Chlorine (JP-A-51-49293
There is a method of adding (No.), but it is industrially disadvantageous because it is expensive and there are problems such as corrosion of the manufacturing equipment. The present inventor has conducted intensive research to solve the coloring problem associated with the saponification of olefin-vinyl ester copolymers such as ethylene-vinyl acetate copolymers using an industrially advantageous method. It has been discovered that coloring can be effectively prevented by applying an organic peroxide after the completion of the reaction, and the present invention has been achieved. According to the invention, the vinyl ester content is between 10 and 50
In a method for producing a saponified product of an α-olefin-vinyl ester copolymer in a proportion of % by weight, an α-olefin-vinyl ester copolymer is mixed with a hydrocarbon solvent,
Saponification is carried out in a system containing a low-boiling point alcohol and an alkali catalyst, and the remaining catalyst is deactivated by adding it to the saponification reaction mixture, and saponification copolymerization is carried out to this reaction mixture or to the reaction mixture from which low-boiling point components have been removed. A non-crosslinked product that prevents coloring, which consists of reacting with 0.05 to 1.0 parts by weight of an organic peroxide, decomposing the organic peroxide, and finally separating the saponified copolymer as a precipitate from the reaction mixture. A method for producing a saponified olefin-vinyl ester copolymer is provided. The α-olefin-vinyl ester copolymer used in the present invention is a copolymer of at least one α-olefin and at least one vinyl ester. Examples of α-olefins include ethylene, propylene, butene, and pentene, and examples of vinyl esters include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl benzoate. The vinyl ester content in the copolymers of the present invention should not be particularly limited since the present invention is essentially concerned with the coloring problem that commonly occurs in the saponification of vinyl ester units, but may not be particularly limited in the reaction. If the resulting polymer can be used as packaging materials, molded containers, adhesives, heat-sealing materials for fibers, coating materials for glass containers, etc., it is preferably 10 to 50% by weight. The saponification reaction in the present invention is carried out in a system consisting of a hydrocarbon solvent, a low-boiling alcohol, and an alkali catalyst. Of course, a small amount of water can be present in these systems. As a low-boiling alcohol, C _1
-C4 alcohols, especially methanol, ethanol, isopropanol, propanol, n-butanol, isobutanol, etc., are used; as alkali catalysts, alkali metal alcoholates, especially sodium methylate, sodium ethylate, potassium methylate, potassium - Ethylate and alkali metal hydroxides, especially sodium hydroxide, potassium hydroxide, etc., are used. Furthermore, as hydrocarbon solvents, aliphatic hydrocarbons having 6 to 12 carbon atoms such as hexane, heptane, octane, nonane, decane, dodecane, cyclohexane, cycloheptane, cyclononane, cyclodecane, methylcyclohexane, and ethylcyclohexane, and cycloparaffins. , benzene, toluene, xylene, ethylbenzene, isopropylbenzene,
Examples include aromatic hydrocarbons having 6 to 14 carbon atoms such as diethylbenzene, cymene, and butylbenzene. During the saponification reaction, the alkali catalyst is used in an amount of 0.001 to 0.5 times equivalent to the vinyl ester in the copolymer, especially
The low-boiling alcohol can be used in an amount of 0.005 to 0.2 equivalents, and is used in an amount that is at least equivalent to the amount of vinyl ester in the copolymer to be saponified, preferably in excess of the equivalent. The saponification reaction is desirably carried out at a temperature of room temperature to 80°C, particularly 30 to 60°C, for 10 minutes to 180 minutes, and the pressure can be increased from normal pressure to about 10 atmospheres. In the present invention, in order to prevent coloring of the saponified product, the saponified product treated with an organic peroxide must be used for the purpose of distilling off a low boiling point solvent etc. after the saponification reaction.
It may have undergone a thermal history at temperatures higher than 100°C. Further, the organic peroxide may be applied at a temperature higher than 100°C. Examples of the organic peroxide used in the present invention include hydrogen peroxide, methyl hydroperoxide, ethyl hydroperoxide, isopropyl hydroperoxide, t-butyl hydroperoxide, isobutyl hydroperoxide, n
-Hexyl hydroperoxide, p-methylbenzyl hydroperoxide, p-methane hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, cumene hydroperoxide, etc. Peroxides; diethyl peroxide, methyl isopropyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butyl peroxide) ) Hexane, dialkyl peroxides such as 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, α-α'bis(t-butylperoxy)diisopropylbenzene; peracetic acid, Percarboxylic acids such as propionic acid and perbenzoic acid; acetyl peroxide, decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, diisopropyl percarbonate, Diacyl peroxides such as di-2-ethylhexyne dicarbonate and acetylcyclohexane sulfonyl peroxide; t-butyl peracetate, t-butyl perisobutyrate, t-butyl perbivalate, t-butyl per2-ethylhexanoate, t-Butyl perbenzoate, t-
Peracid esters such as butyl ethyl percarbonate, t-butyl isopropyl percarbonate, diisopropyl perdicarbonate, diisopropyl perdicarbonate; ethyl methyl ketone peroxide, cyclohexanone peroxide, acetylacetone peroxide, 1.1
-bis(t-butylperoxy)-3,3,5-
Examples include alkylidene peroxides such as trimethylcyclohexane; and cyclic peroxides; organometallic peroxides; organophosphoric acid peroxides; and organic sulfur peroxides. Among these, hydroperoxides, dialkyl peroxides, percarboxylic acids, diacyl peroxides, peracid esters, and alkylidene peroxides are preferred. More preferably, the temperature at which the half-life is 10 hours is 40 to 120°C. These peroxides may be used alone or in a mixture of two or more. Further, these peroxides may be impregnated with a liquid, diluted with a solvent, or dispersed in a liquid, which is preferable from the standpoint of safety. It is generally desirable to use the organic peroxide while maintaining the saponified product in a solution, emulsion, or suspension state. Thus, after the saponification reaction,
Water is first added to the saponification reaction product to approximately deactivate the catalyst remaining at the end of the saponification reaction, and then an organic peroxide is added. According to this embodiment, the amount of organic peroxide used can be small, and the effect of preventing coloration is great. The amount of water added is preferably in a molar ratio of 0.2 to 20 to the alkali catalyst.
Alternatively, after the reaction is complete, the saponified product produced can be precipitated by adding a non-solvent such as methanol or water, and after being taken out, it can be dissolved or dispersed in the solvent again and the peroxide can be applied in this state. can. The amount of organic peroxide added varies depending on the remaining amount of the catalyst, but generally speaking, it is preferably in the range of 0.05 to 1.0% by weight based on the saponified copolymer. The temperature of the saponified product system when adding the organic peroxide is preferably in the range of 30 to 100°C, especially 40 to 80°C. The treatment is preferably carried out at a temperature of 80 to 150°C until the organic peroxide is completely decomposed. Furthermore, if you only want to prevent the saponified product from discoloring, it is also possible to add the organic peroxide at a temperature of 100°C or higher and allow it to act at that temperature. These series of treatments are preferably performed in the presence of an inert gas. In this way, the polymer can be recovered from the mixture obtained by saponification and decolorization by cooling the mixture or by adding low-boiling alcohol or water to the mixture and cooling it to a fine powder. Alternatively, a method in which the mixture is precipitated as a fine powder, a method in which the solvent is distilled off while introducing an inert gas into the mixture under heating, or a method in which the solvent is cooled and powdered when a portion of the solvent remains, a method in which the mixture is heated A method in which a part of the solvent is distilled off while introducing an inert gas, water or water containing a surfactant is added, and the mixture is cooled and powdered. Powderize the polymer by a method such as turning it into a suspension and cooling it,
This can be achieved by separating, washing and drying. EXAMPLES The effects of the present invention will be described in detail below with reference to Examples, but these are for illustrative purposes only and are not intended to limit the scope of the present invention. Example 1 A 20 stainless steel reactor was equipped with a stirrer, a condenser, a thermometer, and a nitrogen inlet tube. The system was flushed with N ₂ gas until the reaction started, and the inside of the reactor was completely replaced with N ₂ gas. 7912 parts of xylene and ethylene-vinyl acetate copolymer (vinyl acetate content 28% by weight, MI400g/10min) in the reactor
4,600 parts were added and heated to 60-70°C to make a homogeneous solution. Lower the internal temperature to 60℃, add 1916 parts of methanol,
Furthermore, the internal temperature was maintained at 45-50°C. Add 269.6 parts of 24% sodium methoxide-methinol solution,
After reacting for 60 minutes at 45 to 50°C with stirring, 64.8 parts of water was added and stirred for 1 hour to stop the reaction. The reaction solution thus obtained was divided into four equal parts, and each was divided into four parts using a stirrer,
10 with condenser, thermometer and _N2 inlet tube
After putting it in a four-necked glass flask, add the following 4
The process was carried out in two ways. Comparative Example 1 After the saponification reaction, 1765 parts of methanol was added to the reaction mixture to precipitate the saponification product. The product was collected by filtration, washed once with the same amount of methanol, and then dried under vacuum. Example 1 After the saponification reaction, the reaction mixture was kept at 40 to 60°C and 3.5 parts of BPO (benzoyl peroxide) was added.
After adding and dissolving it uniformly, heat at 120℃ under a _N2 stream.
Most low-boiling solvents and xylene are heated to 1
After distilling off part of the mixture, the mixture was further heated and stirred at 120°C for 30 minutes, and then the internal temperature was cooled to 60°C, and 1765 parts of methanol was added to precipitate the saponified product. The product was collected by filtration, washed once with an equivalent amount of methanol, and then dried in vacuo. Example 2 After the saponification reaction was completed, the reaction mixture was heated to 120°C under a stream of _N2 gas, most of the low boiling point solvent (methanol, methyl acetate, etc.) and a part of the xylene were distilled off, and then BPO3.5 30% at 120°C.
After heating and stirring for a minute, the internal temperature was cooled to 60° C., and 1,765 parts of methanol was added to precipitate the saponified product. The product was collected by filtration, washed once with the same amount of methanol, and then dried under vacuum. Table 1 summarizes the results of the above treatment and the properties of the saponified ethylene-vinyl acetate copolymer.

[Table] From Table 1, the addition of BPO clearly has a decolorizing effect. Each of the obtained samples was melt-extruded at 130°C using an extruder, and the properties of the saponified pellets are shown in Table 2.

[Table] As can be seen from Table 2, in Examples 1 and 2, coloring did not occur even when heated and melted. Also, comparative example 1
The degree of coloring increases by heating and melting. Example 2 6900 parts of xylene and ethylene-vinyl acetate copolymer (vinyl acetate content 8% by weight, MI 150g/10min) were placed in 20 reactors equipped with the same equipment as in Example 1.
Add 3450 parts, lower the temperature to 60-70℃, methanol,
1437 parts were added and the internal temperature was maintained at 45-50°C. After adding 202.2 parts of a 24% sodium methoxide-methanol solution and reacting at 45 to 50°C for 60 minutes with stirring, the reaction was stopped by adding 48.6 parts of water and stirring for 1 hour. The reaction solution thus obtained was divided into three equal parts, each of which was placed in a four-necked 10 glass flask similar to Example 1, and then subjected to the following treatment. Comparative Example 2 After the saponification reaction, the internal temperature was raised to 130°C while blowing N ₂ gas into the reaction mixture.
2661 parts of solvent was distilled off. The residual solvent is 30% by weight on a dry basis based on the theoretical yield of saponified product.
This viscous material is put into a condenser under pressure of _N2 gas,
Transfer to a 20 Henschel mixer equipped with an _N2 gas inlet tube and a thermometer, add 5040 parts of water, and mix at 510 rpm.
The system was heated while being stirred at a rotational speed of 100° C. to maintain the internal temperature at 90° C., and stirred for an additional 30 minutes to suspend the system. When this suspension was cooled by adding water to the jacket of a Henschel mixer and being stirred, the average particle size was 2 mm.
of granules were obtained. This material was collected by filtration and vacuum dried. Example 3 After the saponification reaction, the internal temperature was raised to 130°C while blowing N ₂ gas into the reaction mixture, and the reaction mixture was heated to 2661°C.
Part of the solvent was distilled off. After that, lower the internal temperature to 120℃, add 4.6 parts of BPO, dissolve it uniformly, and heat it to 120℃.
Stir for 30 minutes. The residual solvent is 30% by weight based on the theoretical yield of saponified product. After treating this viscous material in the same manner as in Comparative Example 2, the average particle size obtained was
The 1.5 mm one was vacuum dried. Example 4 Maintaining the reaction mixture at 60°C after saponification reaction yield
After adding 4.6 parts of BPO and dissolving it uniformly, the internal temperature was raised to 130℃ while blowing N ₂ gas.
2661 parts of solvent was distilled off. The residual solvent is 30% by weight on a dry basis based on the theoretical yield of the saponified product. This viscous material was treated in the same manner as in Comparative Example 2, and the resulting product with an average particle size of 1.7 mm was vacuum dried. Table 3 summarizes the results of the above treatment and the properties of the saponified product of the produced ethylene-vinyl acetate copolymer.

[Table] As can be seen from Table 3, coloring did not occur in Examples 3 and 4, but coloring occurred in Comparative Example 2.

Claims (1)

[Scope of Claims] 1. In a method for producing a saponified product of an α-olefin-vinyl ester copolymer having a vinyl ester content of 10 to 50% by weight, an α-olefin-vinyl ester copolymer is mixed with a hydrocarbon solvent, a low Saponification is carried out in a system containing a boiling point alcohol and an alkali catalyst, water is added to the saponification reaction mixture to deactivate the residual catalyst, and saponification copolymerization is carried out to this reaction mixture or to the reaction mixture from which low boiling point components have been removed. Body hit 0.05~
Non-crosslinked olefin-vinyl with prevented coloration, which consists of the action of 1.0 parts by weight of an organic peroxide, followed by decomposition of the organic peroxide and finally separation of the saponified copolymer as a precipitate from the reaction mixture. A method for producing a saponified ester copolymer. 2. The method according to claim 1, wherein the α-olefin-vinyl ester copolymer is an ethylene-vinyl acetate copolymer.