JP2010070718A - Method for producing vinyl acetal polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a vinyl acetal polymer, whereby the vinyl acetal polymer having high degree of acetalization can be prepared, even by using a carbonyl compound that is insoluble in solvents or is bulky and has low reactivity. <P>SOLUTION: The method for producing the vinyl acetal polymer comprises: a first step of introducing nitrogen into a mixture of a vinyl alcohol polymer, a carbonyl compound and water in a kneader and kneading and reacting the vinyl alcohol polymer and the carbonyl compound in the nitrogen; and a second step of introducing carbon dioxide into the kneader and further kneading and reacting the vinyl alcohol polymer and the carbonyl compound in the carbon dioxide. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention provides a vinyl acetal polymer that can produce a vinyl acetal polymer having a high degree of acetalization even if a carbonyl compound that is insoluble in a solvent or bulky and has low reactivity is used. Regarding the method.

Vinyl alcohol polymers are used in films and the like because they have high water solubility and excellent film forming properties. However, the ceiling temperature and melting point are very close, the dehydration reaction easily occurs, and the resin is easily deteriorated by heat, so that the moldability is poor and the use is limited to fibers and films. Moreover, since the film of the vinyl alcohol polymer is mainly produced by a solution casting method, the productivity is remarkably inferior to the melt extrusion method.

On the other hand, vinyl acetal polymers obtained by acetalization reaction of vinyl alcohol polymers are used for interlayer films for laminated glass, printing inks, binders, adhesives, paints, etc. However, the range of denaturation is limited, so the application is limited.

Patent Documents 1 and 2 disclose vinyl acetal polymers obtained by acetalizing a vinyl alcohol polymer and a bulky carbonyl compound to improve heat resistance. However, a carbonyl compound having a bulky substituent has a very small common solvent with a vinyl alcohol polymer and there is no appropriate reaction system, or the reactivity is low due to the influence of steric hindrance. Only vinyl acetal polymers having a low degree of acetalization could be obtained. In particular, a vinyl alcohol polymer (ethylene-vinyl alcohol copolymer) having an ethylene unit in the main chain has a bulky substituent because the amount of solvent that can be dissolved becomes extremely small as the ethylene unit increases. It was very difficult to find a common solvent with the carbonyl compound.
JP 60-255805 A JP-A-62-141004

The present invention provides a vinyl acetal polymer that can produce a vinyl acetal polymer having a high degree of acetalization even if a carbonyl compound that is insoluble in a solvent or bulky and has low reactivity is used. It aims to provide a method.

The present invention is a first step of introducing nitrogen into a mixture of a vinyl alcohol polymer, a carbonyl compound and water in a kneader and kneading the vinyl alcohol polymer and the carbonyl compound in the nitrogen, This is a method for producing a vinyl acetal polymer having a second step of introducing carbon dioxide into a kneader and further kneading and reacting the vinyl alcohol polymer and the carbonyl compound in the carbon dioxide.
The present invention is described in detail below.

The inventor makes a kneading reaction between the vinyl alcohol polymer and the carbonyl compound in nitrogen in a kneader, and then further kneading the vinyl alcohol polymer and the carbonyl compound in carbon dioxide. In particular, when the carbonyl compound has a bulky substituent or when the vinyl alcohol-based polymer is an ethylene-vinyl alcohol copolymer, the solvent-free or solvent-free system is used. It has been found that a vinyl acetal polymer having a high degree of acetalization can be obtained, and the present invention has been completed.

In the method for producing a vinyl acetal polymer of the present invention, nitrogen is introduced into a mixture of a vinyl alcohol polymer, a carbonyl compound, and water in a kneader, and the vinyl alcohol polymer, the carbonyl compound, and And a second step of introducing carbon dioxide into a kneader and further kneading and reacting the vinyl alcohol polymer and the carbonyl compound in the carbon dioxide.

In this specification, the vinyl alcohol polymer means a polymer compound having a vinyl alcohol unit in the main chain. The vinyl alcohol polymer is not particularly limited, and examples thereof include polyvinyl alcohol, partially saponified polyvinyl acetate, and ethylene-modified polyvinyl alcohol.

The vinyl alcohol polymer used in the method for producing a vinyl acetal polymer of the present invention preferably contains an ethylene unit in the main chain. By containing an ethylene unit in the main chain, the high hygroscopicity and poor moldability of the vinyl alcohol polymer can be improved.

The degree of polymerization of the vinyl alcohol polymer is not particularly limited, but a preferred lower limit is 350. When the degree of polymerization of the vinyl alcohol polymer is less than 350, the strength of the resulting molded product may be inferior or the molding itself may be difficult when molded into a molded product such as a film. A more preferable lower limit of the degree of polymerization of the vinyl alcohol polymer is 500.

Although the carbonyl compound used in the manufacturing method of the vinyl acetal type polymer of this invention is not specifically limited, An aldehyde is suitable. Especially, since the obtained vinyl acetal polymer molecule has a high glass transition temperature and excellent heat resistance, it has an aromatic ring having a substituent, a cycloolefin ring having a substituent, or a substituent. An aldehyde having a saturated hydrocarbon ring is more preferred.

Although the compounding quantity of the said carbonyl compound is not specifically limited, A preferable upper limit is 20 equivalent with respect to the hydroxyl group amount which the said vinyl alcohol-type polymer has. When the amount of the carbonyl compound exceeds 20 equivalents, it may be difficult to remove the remaining carbonyl compound from the product, and the mixing efficiency may be reduced when kneading using a kneader. is there. The minimum of the compounding quantity of the said carbonyl compound is not specifically limited, What is necessary is just to determine suitably according to the target degree of acetalization. A more preferable upper limit of the amount of the carbonyl compound is 10 equivalents.
In addition, the said equivalent means ratio of the number of moles required for the acetalization calculated | required by the number of hydroxyl groups in the said vinyl alcohol-type polymer.

The amount of water used in the method for producing the vinyl acetal polymer of the present invention is not particularly limited, but the preferred lower limit is 50 parts by weight and the preferred upper limit is 400 parts by weight with respect to 100 parts by weight of the vinyl alcohol polymer. It is. If the amount of water is less than 50 parts by weight, the vinyl alcohol polymer may not be sufficiently plasticized. When the amount of the water exceeds 400 parts by weight, a hydrolysis reaction that is the reverse reaction of the acetalization reaction occurs, and the degree of acetalization may decrease.

The nitrogen and carbon dioxide have the role of advancing the acetalization reaction under conditions close to the solvent system by being impregnated into the vinyl alcohol polymer to plasticize it and further kneaded.
In addition, the method for producing a vinyl acetal polymer of the present invention greatly advances the acetalization reaction by having a second step of performing the kneading reaction in carbon dioxide after the first step of performing the kneading reaction in nitrogen. Can be made. While the carbon dioxide has a large plasticizing effect, it is considered that it interacts with the hydroxyl group of the vinyl alcohol polymer and inhibits the acetalization reaction. By allowing the acetalization reaction to proceed to some extent in the nitrogen in advance, the interaction between the carbon dioxide and the hydroxyl group can be suppressed, and the plasticizing effect of the carbon dioxide on the vinyl alcohol polymer is sufficient. It is considered that the acetalization reaction can be greatly advanced by exhibiting the above.

The supply position of the nitrogen and the carbon dioxide is not particularly limited, and examples thereof include a gas inlet provided in a heating barrel of a kneader described later, a hopper of the kneader, and the like.

The pressure at the time of introducing the nitrogen and the carbon dioxide is not particularly limited, but in order to increase the impregnation rate of the nitrogen and the carbon dioxide into the vinyl alcohol polymer, a high pressure state of 1 MPa or more, and a supercritical state It is preferable to do.

In the method for producing a vinyl acetal polymer of the present invention, an acid catalyst that acts on an acetalization reaction between a vinyl alcohol polymer and a carbonyl compound may be used for the purpose of further improving the reaction efficiency.
The acid catalyst is not particularly limited, and examples thereof include sulfuric acid, hydrochloric acid, nitric acid, and paratoluenesulfonic acid.

The temperature at which the vinyl alcohol polymer and the carbonyl compound are kneaded and reacted in the nitrogen and carbon dioxide is not particularly limited, but the preferred lower limit is 50 ° C. and the preferred upper limit is 200 ° C. If the temperature during the kneading reaction is less than 50 ° C., the reaction efficiency may deteriorate and a vinyl acetal polymer may not be obtained. If the temperature during the kneading reaction exceeds 200 ° C., the vinyl alcohol polymer may be thermally deteriorated.

The kneader used in the method for producing the vinyl acetal polymer of the present invention is not particularly limited as long as the resin can be kneaded by heating and has pressure resistance. Extruder, plast kneader And an autoclave with a kneading function. However, when an extruder is used, the discharge port is set so that the nitrogen and the carbon dioxide are introduced and the pressure in the extruder can be sufficiently increased when the vinyl alcohol polymer and the carbonyl compound are kneaded and reacted. It must be sealed with a stopper.

The vinyl acetal polymer produced by the method for producing a vinyl acetal polymer of the present invention is also one aspect of the present invention.

The vinyl acetal polymer of the present invention is not particularly limited, and examples thereof include vinyl acetal polymers represented by the following general formulas (1) to (5). For example, the vinyl acetal polymer of the present invention represented by the general formula (5) introduces nitrogen into a mixture of vinyl alcohol polymer, substituted 2-naphthaldehyde having a substituent and water in a kneader, The vinyl alcohol polymer and the 2-naphthaldehyde having the substituent are kneaded and reacted in nitrogen, and then carbon dioxide is introduced into the kneader, and the vinyl alcohol polymer and the substituent are introduced in the carbon dioxide. It is obtained by further kneading and reacting with 2-naphthaldehyde having benzene.

In formulas (1) to (5), R ^{1 to} R ⁴ represent a substituent such as a hydrogen atom or an alkyl group, and at least one of R ^{1 to} R ³ is an alkyl group.

The alkyl group is not particularly limited, but an alkyl group having a branched structure such as a tert-butyl group is preferable. The alkyl group may be directly bonded to an aromatic ring, a cycloolefin ring, or a saturated hydrocarbon ring, or may be bonded via an ester bond, an ether bond, an amide bond, or the like.

The vinyl acetal polymer as shown in the above general formulas (1) to (5) is excellent in transparency, and has a bulky substituent derived from the carbonyl compound used in the reaction, thereby giving a vinyl acetal polymer molecule. Since the rotation of the main chain is hindered, the glass transition temperature is increased and excellent heat resistance can be exhibited.

The degree of acetalization of the vinyl acetal polymer of the present invention is not particularly limited, but a preferred lower limit is 50 mol% and a preferred upper limit is 90 mol%. If the degree of acetalization is less than 50 mol%, sufficient heat resistance may not be obtained for the vinyl acetal polymer of the present invention. If the degree of acetalization exceeds 90 mol%, the solvent resistance of the vinyl acetal polymer of the present invention may deteriorate. However, the upper limit is not limited as long as the solvent resistance and heat resistance required for the application are satisfied. A more preferable lower limit of the degree of acetalization is 60 mol%.
In this specification, the method for calculating the degree of acetalization is determined using the amount of hydroxyl groups reacted with respect to the total amount of hydroxyl groups. That is, the total hydroxyl group amount is the sum of the hydroxyl group amount present in the vinyl acetal polymer and the acetalized hydroxyl group amount, and the reacted hydroxyl group amount is the acetalized hydroxyl group amount. The total amount of hydroxyl groups and the amount of reacted hydroxyl groups can be determined using, for example, ¹ H-NMR.

If the vinyl acetal polymer of the present invention is used, a molded product having extremely high transparency and excellent heat resistance can be obtained, and such a molded product can be suitably used for optical applications.
The vinyl acetal polymer of the present invention is excellent in compatibility with currently widely used resins such as polyvinyl butyral and ethylene-vinyl alcohol copolymer. It is also useful as a modifier for performing Furthermore, it is also useful as a compatibilizing agent when mixing polyvinyl butyral or ethylene-vinyl alcohol copolymer with another resin. For example, the vinyl acetal polymer of the present invention is mixed with polyvinyl acetate, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl butyral resin, and derivatives thereof. The heat resistance of the resin can be improved and the optical properties can be improved. Moreover, polarity can be provided to polyolefin resin by mixing with polyolefin resin, such as polyethylene and a polypropylene.

According to the present invention, a vinyl acetal polymer that can produce a vinyl acetal polymer having a high degree of acetalization even when a carbonyl compound that is insoluble in a solvent or bulky and has low reactivity is used. The manufacturing method of can be provided.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
To 10 g of polyvinyl alcohol having a saponification degree of 99% and a polymerization degree of 500, 20 g of 2-naphthaldehyde and 0.1 g of paratoluenesulfonic acid were added and mixed to obtain a mixed sample. The discharge port of the extruder was sealed with a stopper, and the obtained mixed sample was charged from a hopper. Further, 10 g of water was charged with a liquid pump, and the screw was rotated while impregnating nitrogen to start kneading. The cylinder temperature of the kneading reaction part of the extruder was 120 ° C., and the pressure was 2 MPa. Two minutes later, water and nitrogen were extracted from the vent part, and then water was charged with a liquid pump, carbon dioxide was impregnated with a pressure pump while maintaining the pressure at 2 MPa, and a kneading reaction was performed. Three minutes later, the rotation of the screw was stopped, and the vinyl acetal polymer was recovered from the discharge port of the extruder.
The obtained vinyl acetal polymer was dissolved in dimethyl sulfoxide, precipitated in water three times and sufficiently dried, then redissolved in deuterated dimethyl sulfoxide, and the degree of acetalization was determined by ¹ H-NMR measurement. As a result, it was 63 mol%.

Further, the glass transition temperature of the obtained vinyl acetal polymer was measured by using a differential scanning calorimeter (TA Instruments, “DSC 2920 Modulated DSC”) during a temperature rising process of 10 ° C./min. Was 147 ° C.

(Example 2)
0.1 g of paratoluenesulfonic acid was added to and mixed with 10 g of polyvinyl alcohol having a saponification degree of 99% and a polymerization degree of 500 to obtain a mixed sample. The discharge port of the extruder is sealed with a stopper, and the obtained mixed sample is put in from a hopper, and the screw is rotated while injecting 10 g of water and 10 g of cuminaldehyde with a liquid pump, impregnating with nitrogen and kneading. Started. The cylinder temperature of the kneading reaction part of the extruder was 120 ° C., and the pressure was 2 MPa. After 2 minutes, water, unreacted cuminaldehyde, and nitrogen were removed from the vent, and 10 g of water and 10 g of cuminaldehyde were then added using a liquid pump, and carbon dioxide was supplied to the pressure pump while maintaining the pressure at 2 MPa. Impregnation, and further kneading reaction was performed. Three minutes later, the rotation of the screw was stopped, and the vinyl acetal polymer was recovered from the discharge port of the extruder.
When the obtained vinyl acetal polymer was measured by the same method as in Example 1, the degree of acetalization was 65 mol% and the glass transition temperature was 132 ° C.

(Example 3)
0.1 g of paratoluenesulfonic acid was added to and mixed with 10 g of polyvinyl alcohol having a saponification degree of 99% and a polymerization degree of 500 to obtain a mixed sample. The discharge port of the extruder is sealed with a stopper, and the obtained mixed sample is charged from a hopper, and 10 g of water and 20 g of cuminaldehyde are injected with a liquid pump while rotating the screw, impregnating nitrogen and kneading. Started. The cylinder temperature of the kneading reaction part of the extruder was 120 ° C., and the pressure was 2 MPa. Two minutes later, carbon dioxide was newly impregnated with a pressure pump until the pressure reached 8 MPa, and a kneading reaction was further performed. Three minutes later, the rotation of the screw was stopped, and the vinyl acetal polymer was recovered from the discharge port of the extruder.
When the obtained vinyl acetal polymer was measured by the same method as in Example 1, the degree of acetalization was 68 mol% and the glass transition temperature was 133 ° C.

Example 4
To 10 g of ethylene-vinyl alcohol copolymer having a saponification degree of 99%, a polymerization degree of 500, and an ethylene content of 34 mol%, 20 g of 2-naphthaldehyde and 0.1 g of paratoluenesulfonic acid were added and mixed. A sample was obtained. The discharge port of the extruder was sealed with a stopper, and the obtained mixed sample was charged from a hopper. Further, 10 g of water was charged with a liquid pump, and the screw was rotated while impregnating nitrogen to start kneading. The cylinder temperature of the kneading reaction part of the extruder was 120 ° C., and the pressure was 2 MPa. Two minutes later, water and nitrogen were extracted from the vent part, and then water was charged with a liquid pump, carbon dioxide was impregnated with a pressure pump while maintaining the pressure at 2 MPa, and a kneading reaction was performed. Three minutes later, the rotation of the screw was stopped, and the vinyl acetal polymer was recovered from the discharge port of the extruder.
The obtained vinyl acetal polymer was dissolved in dimethyl sulfoxide, precipitated in water three times and sufficiently dried, then redissolved in deuterated dimethyl sulfoxide, and the degree of acetalization was determined by ¹ H-NMR measurement. As a result, it was 62 mol% and the glass transition temperature was 105 ° C.

(Comparative Example 1)
10 g of 2-naphthaldehyde and 0.05 g of p-toluenesulfonic acid are added to 50 g of a 10% by weight aqueous solution of polyvinyl alcohol having a saponification degree of 99% and a polymerization degree of 500, and the mixture is stirred for 5 minutes using a stirrer. Got. The resulting mixed solution was stirred at 80 ° C. for 3 hours to recover a vinyl acetal polymer dispersion.
The obtained dispersion was dehydrated and dried, and measured by the same method as in Example 1. As a result, the degree of acetalization was 14 mol%.

(Comparative Example 2)
10 g of 2-naphthaldehyde and 0.05 g of p-toluenesulfonic acid are added to 50 g of a 10% by weight aqueous solution of polyvinyl alcohol having a saponification degree of 99% and a polymerization degree of 500, and the mixture is stirred for 5 minutes using a stirrer. Got. The obtained mixed solution was put into an autoclave apparatus (manufactured by Pressure Glass Co., Ltd.), and the autoclave apparatus was heated to 120 ° C. with a heater while carbon dioxide was fed using a pressure pump until the inside of the autoclave apparatus reached 8 MPa. After heating for 30 minutes, it was cooled to 80 ° C., and after opening the pressure, a vinyl acetal polymer was recovered using a spatula.
When the obtained vinyl acetal polymer was measured by the same method as in Example 1, the degree of acetalization was 31 mol%.

(Comparative Example 3)
To 10 g of polyvinyl alcohol having a saponification degree of 99% and a polymerization degree of 500, 20 g of 2-naphthaldehyde and 0.1 g of paratoluenesulfonic acid were added and mixed to obtain a mixed sample. The discharge port of the extruder was sealed with a stopper, and the obtained mixed sample was charged from a hopper, and kneading was started by rotating the screw while 10 g of water was charged by a liquid pump. The cylinder temperature in the kneading reaction part of the extruder was 120 ° C. After 5 minutes, the rotation of the screw was stopped and the vinyl acetal polymer was recovered from the discharge port of the extruder.
When the obtained vinyl acetal polymer was measured by the same method as in Example 1, the degree of acetalization was 5 mol%.

(Comparative Example 4)
20 g of 2-naphthaldehyde and 0.1 g of paratoluenesulfonic acid were added to and mixed with 10 g of polyvinyl alcohol having a saponification degree of 99% and a polymerization degree of 500 to obtain a mixed sample. The discharge port of the extruder was sealed with a stopper, a sample was charged from a hopper, 10 g of water was charged with a liquid pump, and kneading was started by rotating the screw while impregnating carbon dioxide with a pressure pump. The cylinder temperature of the kneading reaction part of the extruder was 120 ° C., and the pressure was 2 MPa. After 5 minutes, the rotation of the screw was stopped and the vinyl acetal polymer resin was recovered from the discharge port of the extruder.
When the obtained vinyl acetal polymer was measured by the same method as in Example 1, the degree of acetalization was 47 mol%.

(Comparative Example 5)
To 10 g of polyvinyl alcohol having a saponification degree of 99% and a polymerization degree of 500, 20 g of 2-naphthaldehyde and 0.1 g of paratoluenesulfonic acid were added and mixed to obtain a mixed sample. The discharge port of the extruder was sealed with a stopper, and the obtained mixed sample was charged from a hopper. Further, 10 g of water was charged with a liquid pump, and the screw was rotated while impregnating carbon dioxide to start kneading. The cylinder temperature of the kneading reaction part of the extruder was 120 ° C., and the pressure was 2 MPa. After 2 minutes, water and carbon dioxide were extracted from the vent part, and then water was added with a liquid pump, impregnated with nitrogen, and further kneaded. Three minutes later, the rotation of the screw was stopped, and the vinyl acetal polymer was recovered from the discharge port of the extruder.
When the obtained vinyl acetal polymer was measured by the same method as in Example 1, the degree of acetalization was 43 mol%.

(Comparative Example 6)
20 g of 2-naphthaldehyde and 0.1 g of paratoluenesulfonic acid were added to and mixed with 10 g of polyvinyl alcohol having a saponification degree of 99% and a polymerization degree of 500 to obtain a mixed sample. The discharge port of the extruder was sealed with a stopper, a sample was charged from a hopper, 10 g of water was charged with a liquid pump, and kneading was started by rotating the screw while impregnating with nitrogen. The cylinder temperature of the kneading reaction part of the extruder was 120 ° C., and the pressure was 2 MPa. After 5 minutes, the rotation of the screw was stopped and the vinyl acetal polymer resin was recovered from the discharge port of the extruder.
When the obtained vinyl acetal polymer was measured by the same method as in Example 1, the degree of acetalization was 30 mol%.

According to the present invention, a vinyl acetal polymer that can produce a vinyl acetal polymer having a high degree of acetalization even when a carbonyl compound that is insoluble in a solvent or bulky and has low reactivity is used. The manufacturing method of can be provided.

Claims (5)

Introducing nitrogen into a mixture of a vinyl alcohol polymer, a carbonyl compound and water in a kneading machine, kneading and reacting the vinyl alcohol polymer and the carbonyl compound in the nitrogen, and kneading carbon dioxide A method for producing a vinyl acetal polymer, comprising a second step of introducing into a machine and further kneading and reacting the vinyl alcohol polymer and the carbonyl compound in the carbon dioxide. 2. The method for producing a vinyl acetal polymer according to claim 1, wherein nitrogen and carbon dioxide are in a high pressure state of 1 MPa or more, 50 ° C. to 200 ° C., or a supercritical state. The method for producing a vinyl acetal polymer according to claim 1 or 2, wherein the carbonyl compound is an aldehyde. 3. The vinyl acetal heavy compound according to claim 1, wherein the carbonyl compound is an aldehyde having an aromatic ring having a substituent, a cycloolefin ring having a substituent, or a saturated hydrocarbon ring having a substituent. Manufacturing method of coalescence. A vinyl acetal polymer produced by the method for producing a vinyl acetal polymer according to claim 1, 2, 3, or 4.