JPS6144966B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing polyamide bristles. Specifically, the present invention relates to a method for producing polyamide bristles with extremely excellent elastic recovery by using a specific polyamide copolymer. Polyamide has various excellent mechanical properties,
Because of its good transparency and surface gloss, it is widely used as an industrial material for fishing nets, strings, brushes, etc. Generally, such materials are produced by heating and melting nylon chips using an extruder, spinning them through a nozzle with a predetermined hole diameter, rapidly cooling them, stretching them in one or two stages in an atmosphere of hot water, steam, or heated air, and then stretching them in one or two stages. It is produced by heat treatment while under or relaxing. However, bristles made from ordinary polyamides (nylon 6, nylon 6-6, nylon 6-10, nylon 6-12, etc., and their copolymers) have a low elastic recovery rate, and they can However, it was not possible to significantly improve this. Elastic recovery rate is the recovery rate when polyamide bristles are deformed by external stress and then the stress is removed, and the quality of this is an important point in evaluating product quality. For example, if bristles with a poor elastic recovery rate are used in a fishing net, the mesh will become larger each time it is used, resulting in a reduction in the amount of fish caught. In addition, when used for brushes, they break easily and do not have good durability. Especially with brushes,
It is said that the value of elastic recovery rate after 20% elongation is correlated with durability, and it has been impossible to manufacture bristles with a high elastic recovery rate from conventional polyamide materials. The inventors of the present invention have made extensive studies in view of these circumstances and have arrived at the present invention. That is, the gist of the present invention is a method for producing polyamide bristles by two-stage drawing of substantially amorphous undrawn bristles of polyamide, in which the polyamide includes ε-caprolactam, an aliphatic diamine, and an aromatic dicarboxylic acid. Using a poly-ε-caproamide copolymer copolymerized with 0.5 to 20 mol% of a nylon salt consisting of
By performing the experiment at 4.0x magnification, the crystal structure is made into γ type,
Next, the second stage of stretching is carried out at a temperature of 200 to 280°C so that the total stretching ratio is 4.7 times or more, thereby making the crystal structure α-type, and producing polyamide bristles with an excellent elastic recovery rate. lies in the law. The present invention will be explained in more detail below. The polyamide used in the production method of the present invention is poly-ε-caproamide copolymer, that is, ε-
It is a copolymer of caprolactam and a nylon salt (hereinafter simply referred to as "nylon salt") consisting of an aliphatic diamine and an aromatic dicarboxylic acid. Any nylon salt to be copolymerized with ε-caprolactam can be used as long as it is obtained from aliphatic diamines as the diamine component and aromatic dicarboxylic acids as the dibasic acid component. From an industrial perspective, diamine components include hexamethylene diamine and ethylene diamine, while dibasic acid components include terephthalic acid,
Isophthalic acid is used. Among these, nylon salts made of combinations of hexamethylene diamine and terephthalic acid, ethylenediamine and terephthalic acid, or isophthalic acid are preferred. Thus, the nylon salt and ε-caprolactam were charged into a polymerization tank, and poly-ε-
A caproamide copolymer is obtained, in which the amount of nylon salt is from 0.5 to 20 mol%, preferably from 2 to 20 mol%, in the poly-ε-caproamide copolymer. That is, the amount of nylon salt is 20 mol%
If the amount is larger than this, the crystallinity and physical properties will be substantially reduced. Conversely, if it is less than 0.5 mol%, polyamide bristles with the desired high elastic recovery rate cannot be obtained. The poly-ε-caproamide copolymer thus obtained is extracted by a conventional method, that is, the poly-ε-caproamide copolymer is extracted until the content of residual monomers and oligomers is 0.5% by weight or less, and then Substantially amorphous polyamide bristles (hereinafter simply referred to as "undrawn bristles") are produced by heating to a temperature of 280°C or less using an extruder, extruding it from a nozzle in a molten state, and rapidly cooling it to a temperature of 0 to 60°C. ). In the present invention, the undrawn bristles are first stretched under stretching conditions such that the crystal structure after stretching exhibits a γ-type.
After stage stretching is performed, a second stage of stretching is subsequently performed at a temperature higher than the first stage stretching temperature and under conditions such that the crystal structure after stretching completely transforms into the α type. The appropriate stretching conditions such that the crystal structure of the stretched bristles after the first stage of stretching exhibits a γ-type are a stretching temperature of 80 to 150°C and a stretching ratio of 2.0 to 4.0 times. If the stretching temperature is lower than 80℃, the bristles will whiten or break,
If the temperature is higher than 150°C, stretching is possible, but breakage and netting occur during the second stage of stretching. As for the stretching conditions for the first stage, when the temperature is selected on the high temperature side, the stretching ratio may be selected low, and when the temperature is selected on the low temperature side, the drawing ratio may be selected high. Stretching at high temperature and high magnification tends to change the crystal structure to α type, so care must be taken. Further, if the stretching ratio is less than 2.0 times, stretching unevenness tends to occur during the second stage stretching. On the other hand, the stretching ratio
If it is 4.0 times or more, the crystal structure becomes almost α-type in this first stage of stretching, and even if the second stage of stretching is continued, the crystal structure will not be formed in the first stage of stretching as in the present invention. Once the structure is set to γ type, this is then changed to α type.
Compared to bristles obtained by second-stage stretching so as to transfer to the mold, the elastic recovery rate at 20% elongation is lower. The stretched bristles after the first stage of stretching continue to be 200 ~
The second stage of stretching is carried out at a stretching temperature of 280°C and a total stretching ratio of 4.7 times or more. If the stretching temperature is lower than 200°C, it is likely to break during stretching, and if it is higher than 280°C, it will be likely to melt and break in the stretching tank, which will not only impair operability but also deteriorate the mechanical properties of the stretched product. Furthermore, the stretching ratio in the second stage of stretching must be such that the total stretching ratio is 4.7 times or more at the above temperature. If the total stretching ratio is less than 4.7 times, it is difficult to completely transform the crystal structure of the drawn product into the α-type, and the γ-type crystals from the first stage of stretching still remain, resulting in the elastic recovery rate of the drawn bristles. cannot be improved. The above-described stretching operation is carried out using a conventional stretching device for producing nylon bristles, and for example, a stretching device as shown in FIG. 1 is used. That is, the unstretched bristles 1 are guided in numerical order to the right in the figure through a presser roller 2, and are stretched. 3, 6, 9, 12 are roll stands, 2, 5,
8 and 11 are presser rollers, 4 and 7 are stretching tanks, and the desired stretching ratio is set by adjusting the rotational speed of the roll stand at the front and back of each stretching tank. The bristles that have been drawn in two stages through the drawing tank 7 are then heat treated in a heat treatment tank 10 in order to improve their heat resistance. The heating medium used in the drawing tanks 4 and 7 and the heat treatment tank 10 can be any medium that can uniformly heat the bristles, such as hot water, hot air, steam, or mineral oil, but it is usually economically inexpensive. Hot water and hot air baths are preferred since they do not require washing and removing the heating medium adhering to the bristles after drawing. The drawn and heat-treated bristles 13 are wound onto a bobbin 14 to form a product. As detailed above, in order to obtain polyamide bristles having a high elastic recovery rate and excellent mechanical properties, a nylon salt consisting of an aliphatic diamine and an aromatic dicarboxylic acid is added to ε-caprolactam.
A poly-ε-caproamide copolymer copolymerized with 0.5 to 20 mol% is melt-extruded and rapidly cooled, and the resulting amorphous undrawn bristles are subjected to a first drawing under specific conditions. This can only be achieved by generating a γ-type crystal structure and then performing a second-stage stretching at a temperature higher than the first-stage stretching temperature to completely transform it into an α-type crystal structure. It is possible to produce bristles with α-type crystal structure and good mechanical properties such as strength and elongation by applying appropriate stretching conditions to ordinary poly-ε-caproamide polymers. However, it has not been possible to produce polyamide bristles that have an extremely excellent elastic recovery rate at 20% elongation, as is the objective of the present invention. The details of the manufacturing method of the present invention have been explained above, but
According to the present invention, polyamide bristles can be obtained that have a high elastic recovery rate and have properties suitable as raw materials for fishing nets, brushes, and various other materials. Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless it departs from the gist thereof. In addition, the meanings and measurement methods of various terms in the examples are as follows. Tensile properties (strength g/d, elongation %): JIS L-
Value determined according to 1070 20% elongation elastic recovery rate: Referring to JIS L-1073,
It was measured as follows. First, the obtained bristles were attached to an Instron tensile tester under a standard initial load (value of 1/30 of the sample denier) with a grip interval of 200 mm, and then the bristles were tested at a tensile speed of 20 mm/min at a standard initial load (1/30 of the sample denier). Stretch by 20% of the length when a load is applied. i.e.
Stretch it by 40mm (this value is l). Next, the load was removed by immediately returning the gripping interval to 200mm at a speed of 20mm/min, and in this state
After standing for a minute, the standard initial load was applied again to measure the residual elongation l ₁ (min) of the sample, and the 20% elongation elastic modulus was determined using the following formula and expressed as the average value of 10 times. (l-l ₁ )/l x 100 (%) Here l...Elongation at 20% elongation (40mm) l ₁ ...Residual elongation (mm) Total stretching ratio: 1st stage stretching ratio x 2nd stage stretching ratio Stretching ratio of stage x (1-relaxation rate during heat treatment/100) Example 1 Using 98% concentrated sulfuric acid, 95 mol% of ε-caprolactam with a relative viscosity (ηrel) of 4.0 at 25°C,
As the nylon salt, a poly-ε-caproamide copolymer (hereinafter referred to as "nylon 6/6T") consisting of 5 mol% of hexamethylene diammonium terephthalate salt was used.
) was melted using an extruder with a cylinder temperature of 260°C, extruded through a nozzle with a hole diameter of 2 mm, and then introduced into a water bath filled with cold water at 4°C to rapidly cool it, resulting in substantially amorphous undrawn bristles. I got it. Next, the undrawn bristles were drawn using the drawing apparatus shown in FIG. For the first stage stretching
Two-stage stretching was performed by 3.5 times and 1.5 times using a hot water bath at 98°C and a hot air bath at 260°C for the second stage stretching, followed by heat treatment with 10% relaxation in a hot air bath at 260°C. The film was then stretched so that the total stretching ratio was 4.7. The final winding speed was 80 m/min. The crystal structure of the bristles after the first stage drawing was γ-type, but by the second stage stretching, it completely transformed to the α-type structure, and as shown in Table 1, the crystal structure of the bristles was γ-type.
The elongation elastic recovery rate reached an extremely high value that could not be achieved with conventional polyamide bristles. Comparative Example 1 Using the same unstretched bristles as in Example 1, stretching was carried out under the same conditions as in Example 1, except that the second stage stretching temperature was changed to 220°C and the second stage stretching ratio was changed to 1.3. (Total stretching ratio: 4.1) After the second stage stretching, the crystal structure was a mixture of α type and γ type, and the elastic recovery rate of the stretched bristles at 20% stretching decreased significantly. The results are also listed in Table-1. Comparative Examples 2 and 3 Using the same undrawn bristles as in Example 1, an attempt was made to obtain α-type drawn bristles at once by increasing the stretching ratio in the first stage, but the crystal structure of the drawn bristles was similar to that of γ-type. The elastic recovery rate at 20% elongation was not as high as that of Example 1. (Comparative Example 2) Even if the first stage drawing bath was changed to a 150° C. hot air bath (Comparative Example 3), a complete α-type structure could not be obtained. (The elongation of the stretched bristles was below 20%, making it impossible to measure the elastic recovery rate after 20% stretching.)
(Comparative Example 3) Both results are also listed in Table-1.

[Table] Example 2 Extrusion stretching was carried out under the same conditions as in Example 1, except that nylon 6/6T having a relative viscosity of 3.5 was used. For comparison, drawn bristles were produced under the same molding conditions as in Example 1 using ordinary nylon 6 (Novamid 1020A, manufactured by Mitsubishi Chemical Industries, Ltd.) with a relative viscosity of 3.5. This was designated as Comparative Example 4. The physical properties of each were measured and the results are shown in Table 2.

[Table] The crystal morphology of the stretched bristles was α-type structure for both 6/6T and nylon 6, and no difference was observed, but the elastic recovery rate of nylon 6 bristles at 20% elongation was significantly inferior. Example 3 Using the same undrawn bristles as in Example 2, they were stretched under various stretching conditions as shown in Table 3, and the correlation between the crystal structure and the physical properties of the drawn bristles was investigated. The results are shown in Table-3. Comparative Examples 5 and 6 Stretching was carried out under the conditions shown in the Comparative Examples column of Table 3, and the measurement results of the crystal structure and physical properties are also listed in Table 3.

[Table] Example 4, Comparative Example 7 Table 4 shows the results of stretching the same unstretched bristles as in Example 2 under the stretching conditions shown in Table 4.

【table】

[Table] The bristles with an excellent elasticity recovery rate after 20% elongation were obtained in Example 3.
This is a case where the film exhibits a γ type after the first stage stretching and an α type after the second stage stretching, as shown in FIG.

[Brief explanation of the drawing]

FIG. 1 is a schematic illustration of the apparatus used to carry out the present invention. 1... Undrawn bristles, 2, 5, 8, 11... Press roller, 3, 6, 9, 12... Roll stand, 4, 7... Stretching tank, 10... Heat treatment tank, 14
...Bobbin.

Claims (1)

[Claims] 1. A method for producing polyamide bristles by drawing undrawn bristles of substantially amorphous polyamide in two steps, wherein the polyamide comprises ε-caprolactam, an aliphatic diamine, an aromatic dicarboxylic acid and Using a poly-ε-caproamide copolymer copolymerized with 0.5 to 20 mol% of a nylon salt consisting of 1
The crystal structure is made into a γ type by stretching the stage at a temperature of 80 to 150°C and a magnification of 2.0 to 4.0 times, and then 2
The stage stretching is done at a temperature of 200 to 280℃ and the total stretching ratio is 4.7.
A method for producing polyamide bristles with an excellent elastic recovery rate, which is characterized by making the crystal structure α-type by stretching the bristles to more than double the size. 2. The method for producing polyamide bristles according to claim 1, wherein the aliphatic diamine is hexamethylene diamine diamine or ethylene diamine. 3. The method for producing polyamide bristles according to claim 1, wherein the aromatic dicarboxylic acid is terephthalic acid or isophthalic acid.