JP5061607B2 - Manufacturing method of nylon 6 resin - Google Patents

Description

  The present invention has a small amount of monomer and oligomer regeneration at the time of melt molding, can reduce the contamination of the mold of the molding apparatus, has a small dependence on the moisture content in the polymerization degree change of the resin at the time of melting, and has a stable moldability The present invention relates to a method for producing nylon 6 resin.

  Nylon 6 resin is produced by ring-opening and polymerizing ε-caprolactam and has excellent chemical, mechanical and thermal properties, so it is widely used as a fiber, engineering plastic, film, etc. Is also used as a food packaging film. The polymerization of ε-caprolactam is usually performed by heating ε-caprolactam to around 250 ° C. in the presence of water under a reduced pressure of about 50 Torr. Nylon 6 resin produced in this way contains about 10% of unreacted ε-caprolactam monomer and oligomer, but the product is removed by hot water to produce nylon 6 resin as a product. Yes.

  However, when molding the nylon 6 resin from which the monomers and oligomers have been removed, if the resin is heated and melted in the melt extrusion process, the monomers and oligomers are produced by an equilibrium reaction, and the die of the molding apparatus is contaminated due to their vaporization. Or they may remain in the product and cause quality degradation. As a technique for solving such a problem, a technique is known in which monocarboxylic acid and monoamine are added as end-capping agents to the reaction system during the ring-opening polymerization of ε-caprolactam to suppress the equilibrium reaction of monomers and oligomers. Yes (Patent Document 1 etc.).

Japanese Patent Laid-Open No. 8-231711

  However, although the invention disclosed in Patent Document 1 can obtain a nylon 6 resin in which an equilibrium reaction in which monomers and oligomers are generated during processing involving heating and melting is suppressed, the polymerization requires a reduced pressure of about 50 Torr. In order to secure pressure resistance, manufacturing equipment becomes expensive, and in the manufacturing process, the energy cost for decompression is high, and improvement is required.

  The present invention has been made against the background of the above prior art, and the equilibrium reaction in which monomers and oligomers are produced during processing involving heating and melting without reducing the reaction system in the polymerization in the polymerization apparatus is suppressed. Another object of the present invention is to provide a production method for producing a nylon 6 resin.

The method for producing a nylon 6 resin of the present invention is a nylon 6 resin in which a raw material composition containing at least ε-caprolactam and water is supplied to a polymerization apparatus equipped with a heating device and subjected to ring-opening polymerization to form a nylon 6 resin. A manufacturing method of
The raw material composition as terminal blocking agent contains at least one monocarboxylic acid compound with a primary monoamine compound, at least one secondary monoamine compound,
The polymerization apparatus is for producing a nylon 6 resin by heating and polymerizing the raw material composition to 240 ° C. or higher under normal pressure,
Having a preheating step of preheating the premixed raw material composition to 120 ° C. or more and 200 ° C. or less that can ensure the progress of the polymerization reaction in the polymerization device under normal pressure before supplying the raw material composition to the polymerization device. It is characterized by.
According to the manufacturing method of the said structure, the nylon 6 resin by which the equilibrium reaction which a monomer and an oligomer produce | generate at the time of the process accompanying a heating and a fusion | melting was suppressed without performing pressure reduction can be manufactured. Furthermore, the upper limit value of the preheating temperature is preferably 200 ° C. or less, and when the preheating temperature is less than 120 ° C., the polymerization reaction in the polymerization apparatus does not proceed sufficiently, and the polymerization apparatus needs to be depressurized.

Moreover, this invention performs in the supply piping which supplies the said preheating process to the said superposition | polymerization apparatus after storing in the stirrable storage apparatus introduce | transduced after the said raw material composition mixes previously. It is characterized by that.
Furthermore, the polymerization apparatus has a heat exchanger and a layered plate portion arranged in layers in a direction perpendicular to the downward movement flow path of the raw material composition, and the supplied raw material composition The heating is performed uniformly and the polymer is moved downward without causing turbulent flow.

  Examples of monocarboxylic acid compounds constituting the end-capping agent include acetic acid, propionic acid, valeric acid, caproic acid, enanthic acid, fubric acid, eralmonic acid, oleic acid, undecanoic acid, pelargonic acid, tridecanoic acid, myristic acid, myristic acid Aliphatic monocarboxylic acids such as streanic acid, palmitic acid, stearic acid, lauric acid, linoleic acid, arachidic acid, and behenic acid, cycloaliphatic carboxylic acid, cyclocyclohexyl carboxylic acid, methyl cyclohexyl carboxylic acid, benzoic acid, Aromatic monocarboxylic acids such as ethylbenzoic acid and phenylacetic acid can be mentioned. In addition, acid anhydrides that can play the same role as these monocarboxylic acids can also be used. Of these, the use of acetic acid is preferred because of its low cost and easy handling.

  Examples of the dicarboxylic acid compound constituting the end-capping agent include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecaneic acid. Like diionic acid, hexadecadionic acid, hexadecenedionic acid, aliphatic dicarboxylic acid like octadecadionic acid, alicyclic dicarboxylic acid like 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid And aromatic dicarboxylic acids and xylylene dicarboxylic acids.

  The primary or secondary monoamine constituting the end-capping agent includes butylamine, pentylamine, hexylamine, heptylamine, octylamine, 2-ethylhexylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecyl Examples include aliphatic monoamines such as amine, hexadecylamine, octadecylamine and octadecyleneamine, alicyclic monoamines such as cyclohexylamine and methylcyclohexylamine, and aromatic monoamines such as benzylamine and β-phenylethylamine. It is done. Among these, use of cyclohexylamine is preferable.

  The primary or secondary diamine constituting the end-capping agent is ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylene. Aliphatic diamines such as diamine, undecamethylenediamine, dodecamethylenediamine, cyclohexanediamine, methylcyclohexanediamine, alicyclic diamines such as bis- (4,4′-aminocyclohexyl) methane, xylylenediamine, toluenediamine, etc. Examples include aromatic diamines.

  In the method for producing nylon 6 resin of the present invention, after completion of the polymerization reaction, the obtained resin is heat-treated with water or water containing ε-caprolactam, so that ε-caprolactam in nylon 6 resin and its Cyclic dimers can be extracted.

In the method for producing the nylon 6 resin of the present invention, the amount of the end-capping agent added is the terminal amino group concentration [AEG] (meq / kg) and the terminal carboxyl group concentration [CEG] of the nylon 6 resin after the purification step. (Meq / kg) is
0.85 ≦ [AEG] / [CEG] ≦ 1.15
700 ≦ [AEG] × [CEG] ≦ 2500
Is preferably satisfied.

  By adopting such a configuration, the relative viscosity (RV) is about 2.6 to 3.5, excellent mechanical properties such as strength and processability at the time of molding, and regeneration of monomers and oligomers at the time of melt molding It is possible to produce a nylon 6 resin having a small amount, which can reduce the contamination of the die of the molding apparatus, has a small dependency on the moisture content with respect to a change in the polymerization degree of the resin at the time of melting, and has a stable moldability. When [AEG] × [CEG] is less than 700, the effect of suppressing the generation of monomers or oligomers by capping at the end increases, but it becomes difficult to produce economically. When [AEG] × [CEG] exceeds 2500, too many end groups decrease the mechanical properties of the nylon 6 resin, and more ε-caprolactam is generated during processing involving heat melting.

  The total number of terminals ([AEG] + [CEG]) of the linear polymer constituting the polyamide resin of the present invention obtained by the above method is 40 to 120 meq / kg, preferably 50 to 90 meq / kg. If this value is too small, there may be a problem in moldability. If it is too large, the physical properties of the molded product molded using the obtained nylon 6 resin will be insufficient, and monomer or cyclicity caused by melting and heating will be insufficient. The amount of oligomer generated increases.

  FIG. 1 is a schematic front view of a production apparatus suitable for carrying out the method for producing nylon 6 resin of the present invention. The manufacturing apparatus includes a mixing device 22 that mixes raw materials into a raw material composition, a storage device 24 that stores the raw material composition, a pipe 18 that sends the raw material composition stored in the storage device 24 to the polymerization device 10, and a polymerization device. 10. The polymerization apparatus is provided with a heating device such as a jacket (not shown). The mixing apparatus 22 is connected to a raw material supply pipe 21 for supplying raw material components, and has a stirring blade A1 and a motor M1 for driving the stirring blade A1. The storage device 24 also includes a stirring blade A2 and a motor M2 for driving the stirring blade A2. A plurality of mixing devices and storage devices may be provided. A plurality of raw material supply pipes 21 may be provided according to the number of supply components.

  The polymerization apparatus 10 heats the supplied raw material composition uniformly, and heat exchangers 13 and 15 and a layered plate arranged in layers in the vertical direction so that the polymer moves downward without causing turbulent flow. Portions 14 and 16 are provided. The pipe 18 is provided with a pipe heating device 20 so that the raw material composition passing through the pipe 18 can be heated. The configuration of the pipe heating device 20 is not particularly limited, and examples include an electric heater, a heat medium circulation, and steam heating. The length of the pipe heating device 20 is set in consideration of the preheating temperature of the raw material composition, the flow velocity, the inner diameter of the pipe, and the like.

  Preheating of the raw material composition that passes through the pipe 18 provided with the pipe heating device 20 is performed at 120 ° C. or higher. The upper limit of the preheating temperature is preferably 200 ° C. or less, more preferably 180 ° C. or less, and further preferably 160 ° C. or less. When the preheating temperature is less than 120 ° C., the polymerization reaction in the polymerization apparatus does not proceed sufficiently, and the polymerization apparatus needs to be depressurized.

  The raw material composition contains ε-caprolactam, water, and an end-capping agent, and contains additives required depending on the use of the nylon 6 resin to be produced. For example, fine particles of inorganic compounds are added for film use. The polymerization reaction proceeds in the form of a polycondensation reaction of ε-caproic acid generated by the reaction between ε-caprolactam and water. In the polymerization apparatus 10, the raw material composition supplied from above is heated to 240 ° C to 270 ° C, more preferably 250 to 260 ° C, and polymerization is performed. At this time, a part of water is refluxed to the polymerization apparatus by a condenser (not shown) provided in the upper part of the polymerization apparatus, and the remaining part is distilled off.

  The nylon 6 resin R having completed the polymerization reaction is taken out from the lower part of the polymerization apparatus 10. This nylon 6 resin contains about 10% by weight of ε-caprolactam monomer and cyclic dimer, and is extracted with water containing these monomers and cyclic oligomers in the next step as described above. Nylon 6 resin is produced which is removed and end-capped with the end-capping agent of the final product.

The evaluation described in the examples was measured by the following method.
<Quantification of the number of active terminal groups>
The amino end group amount [AEG] is obtained by dissolving the resin in a phenol / ethanol (volume ratio 4/1) solvent, adding a predetermined amount of 0.02N hydrochloric acid, and then back titrating with a 0.02N aqueous sodium hydroxide solution. It was. The carboxyl end group amount [CEG] was determined by dissolving the resin in benzyl alcohol at 180 ° C., adding a phenolphthalein indicator, and titrating with an ethanol solution of 0.02N potassium hydroxide.

<Relative viscosity>
Sulfuric acid whose concentration is adjusted to 96% by weight is filled in the viscometer, and then the sulfuric acid is allowed to flow down to measure the time T1 that passes through a certain section of the viscometer (set as a blank). On the other hand, the passage time T2 is measured by the same procedure as described above for sulfuric acid (concentration 96% by weight) in which the polymer to be measured is dissolved to a concentration of 1% by weight.
Relative viscosity is the formula relative viscosity = T2 / T1
Determined by

<Residual monomer amount>
The nylon 6 resin to be measured is set in a Soxhlet extractor and extracted for 17 hours using water as a solvent. The extracted liquid is cooled, the value is read with a refractometer, and the extracted weight is calculated. The following calculation formula: Residual monomer amount (% by weight) = (weight of extract / measured polymer amount) × 100
The amount of residual monomer was determined by

[Example 1]
Nylon 6 resin was manufactured using the manufacturing apparatus having the configuration shown in FIG. The pipe 18 has an inner diameter of 27 mm, and the heating device 20 is a steam jacket. The heated pipe had an inner diameter of 34 mm and a length inside the jacket of 18 m. In the raw material composition, ε-caprolactam / water / acetic acid / cyclohexylamine is 97 / 2.4 / 0.07 / 0.1 (weight ratio). The piping was heated by supplying superheated steam at 120 ° C. The heating temperature of the polymerization apparatus was 280 ° C. ± 5 ° C. The relative viscosity (RV) of the nylon 6 resin obtained by washing the nylon 6 resin obtained by polymerization with water is in the range of 2.8 ± 0.2, and [AEG] = 41 (meq / kg) , [CEG] = 42 (meq / kg), [AEG] × [CEG] = 1720. The residual monomer amount of this nylon 6 resin was 0.8% by weight.

[Example 2]
Nylon 6 resin was prepared in the same manner as in Example 1 except that the blending ratio of ε-caprolactam / water / acetic acid / cyclohexylamine in the raw material composition was 97 / 2.4 / 0.17 / 0.17 (weight ratio). Manufactured. The relative viscosity (RV) of nylon 6 resin after monomer extraction with water is in the range of 2.8 ± 0.1, [AEG] = [CEG] = 30 (meq / kg), [AEG] × [CEG ] = 900. The residual monomer amount of this nylon 6 resin was 0.6% by weight.

[Comparative Example 1]
When the pipe was not preheated in Example 1, [AEG] = 52, [CEG] = 49, and [AEG] / [CEG] = 1.06, [AEG] × [CEG] = 2550. there were. The relative viscosity of the nylon 6 resin obtained by washing the nylon 6 resin obtained by the polymerization with water increased only to 2.5.

Schematic front view of a production apparatus suitable for carrying out the method for producing nylon 6 resin of the present invention

Claims (3)

A method for producing a nylon 6 resin, wherein a raw material composition containing at least ε-caprolactam and water is supplied to a polymerization apparatus equipped with a heating device and subjected to ring-opening polymerization to obtain a nylon 6 resin,
The raw material composition as terminal blocking agent contains at least one monocarboxylic acid compound with a primary monoamine compound, at least one secondary monoamine compound,
The polymerization apparatus is for producing a nylon 6 resin by heating and polymerizing the raw material composition to 240 ° C. or higher under normal pressure,
Having a preheating step of preheating the premixed raw material composition to 120 ° C. or more and 200 ° C. or less that can ensure the progress of the polymerization reaction in the polymerization device under normal pressure before supplying the raw material composition to the polymerization device. The manufacturing method of nylon 6 resin characterized by these. The preheating step is performed in a supply pipe that is supplied to the polymerization apparatus from the storage device after being stored in a stirrable storage device that is introduced after the raw material composition has been mixed in advance. Item 8. A method for producing a nylon 6 resin according to item 1. The polymerization apparatus has a heat exchanger and a layered plate portion arranged in layers in a direction perpendicular to a moving flow path below the raw material composition, and heats the supplied raw material composition. The method for producing nylon 6 resin according to claim 1 or 2, wherein the method is performed uniformly and the polymer is moved downward without causing turbulent flow .

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