KR100233303B1 - Process for making polyester mono-filament for toothbrush - Google Patents

Abstract

The present invention relates to a method for producing a polyester monofilament suitable for tooth brush by reducing the m-cresol solution.

Description

Manufacturing method of polyester monofilament for brush head

1 (a) is a graph showing the molecular weight distribution during polyester solid-state polymerization.

(b) is a graph showing the polyester solid-state polymerization conditions.

2 is a schematic view showing a cross section of the monofilament before weight loss.

3 is a schematic cross-sectional view of the monofilament after weight loss in the present invention.

4 (a), (b), (c) is a schematic diagram showing the cross section of the monofilament before overweight.

The present invention relates to a method for producing a polyester monofilament suitable for tooth brush by reducing the m-cresol solution.

In general, when the bristles are manufactured using the polyester monofilament manufactured by extrusion molding, the bristles of the teeth are cleaned well, the softness does not damage the gums, and the elasticity can be used for a long time and has excellent color. .

In the present invention, by reducing the amount of both ends of the polyester monofilament using the m-cresol solution, there is an object to produce a polyester monofilament for bristle with excellent softness and elasticity.

Hereinafter, the present invention will be described in detail.

The present invention is to reduce the monofilament made of polyethylene terephthalate or polybutylene terephthalate resin to produce a monofilament for tooth brush hair, the weight loss treatment by immersing the monofilament in m-cresol solution during the weight loss It relates to a method for producing a polyester monofilament for toothbrush hair.

Referring to the present invention in more detail as follows.

In the present invention, a polyester having an intrinsic viscosity of 0.9 to 1.0 is produced in a medium-weight through solid state crystallization, and then vacuumed for 20 to 30 hours at a temperature of 180 to 210 ° C. in a vacuum dryer process. By maintaining the molecules in the base chip (polymer) in the solid state to cause the polymerization in the solid state to bond the molecules in the polymerization chip to reduce the number of terminal groups to increase the molecular weight gradually. Such molecular weight distribution is shown in FIG. 1 (a).

Temperature and vacuum degree are important factors in solid phase polymerization for shifting the molecular weight distribution to the right. Polymerization at low temperature may cause reverse reaction, and intrinsic viscosity is not improved well. Viscosity improvement at too high temperature may result in lumping chips due to melting of chip surface, resulting in good quality chips. There will be no.

Also, depending on the degree of vacuum, the higher the conditions, the higher the rate of solid-state polymerization. This serves to draw out the by-products coming out of the polymerization with a high vacuum and to facilitate the reaction.

The degree of polymerization according to temperature and vacuum conditions during solid state polymerization is shown in FIG. 1 (b).

At this time, if the rate of solid-state polymerization is slower than the thermal decomposition rate, the holding time increases and the desired viscosity is not obtained, and the processing time becomes longer. This causes a decrease in productivity due to a decrease in the amount of chips produced per unit time.

Therefore, when the optimum conditions are set at the most appropriate temperature (190 ~ 205 ℃) and vacuum degree (745 ~ 755㎜Hg), it is possible to obtain a high viscosity polyester suitable for the toothbrush brush of IV (1.7: 1.8). have.

Reference examples of the high viscosity PBT production conditions are shown in Table 1, and the results are shown in Table 2.

TABLE 1

TABLE 2

In preparing the high viscosity PBT prepared by the solid state polymerization conditions in the above-described comparative example and the reference example as a monofilament for toothbrush hair, the aqueous solution of alkaline solution, which is a conventional weight loss solvent, is a weight loss site due to capillary phenomenon between the monofilaments in the bundle. As the monofilament for brush heads, the weight loss length and degree were inadequate.

In the case of brush head, the monofilament itself is more difficult to remove foreign substances as the weight difference between the tip and the inner part of the brush head increases. Therefore, when the weight loss treatment was performed by neutralizing m-cresol, the capillary phenomenon was less likely to be obtained.

The characteristics for the solvent cresol are as follows.

Cresol: three isomers of methylphenol, hydroxy toluene and cresolic acid (o-cresol, m-cresol, p-cresol)

◈ Toxicity to human body

US working environment concentration is 5ppm (22㎜ / ㎥)

Oral toxicity is the largest of the three isomers o-cresol,

least m-cresol.

◈ Physical and chemical properties

Colorless, acid, toxic, flash point 86 ℃

When dissolved in 40 times H ₂ O, it corrodes metals and alcohols in alcohol and organic solvents.

Comparison of three isomers o-cresol, m-cresol and p-cresol

In the present invention, the high viscosity PBT resin has a melting temperature of 220 to 250 ° C., an intrinsic viscosity of 1.2 to 2.5 (phenol / TEC method), and a melt flow index of 6.0 to 20 (measurement condition: 250 ° C., 2,160 g, Φ 2 mm). In the spinning machine, spinning is performed in 240 ~ 300 ℃ with a certain shape and thickness.

When extruded high-viscosity PBT monofilament is handled and bundled in good condition during weight loss processing, it is a bristle monofilament that is cut to a length that can be double-sided, so that both sides of the bundle are immersed at a constant dipping depth in the weight loss solution. Weight loss processing

Neutralization solution of m-cresol solution (injection amount: 108.14) is mainly applicable to the solution used for weight reduction, and it is appropriate to use alkaline aqueous solution because only small amount of the end of monofilament should be reduced due to the characteristics of the monofilament for toothbrush hair. Can't get it.

Therefore, the cut high-viscosity PBT monofilament is subjected to weight loss processing for m-cresol neutralization solution under constant temperature for a certain time. Important points in this method are the concentration of m-cresol solution, temperature, immersion time of monofilament, and immersion depth. Since these conditions are performed on both sides, it is impossible to obtain a product that satisfies the softness and elasticity of the bristles when such conditions are not accurate.

High-viscosity PBT chisel hair monofilament according to the present invention can be prepared under the following conditions, namely temperature 700 ~ 100 ℃, m-cresol solution concentration 10 ~ 40%, immersion time 0.5 ~ 1 hour tablets, preferably double-sided surface Immersion depth of the can be adjusted but mainly 1 ~ 2㎜ is appropriate. In this case, it is preferable to use the m-cresol solution that is neutralized with an alkali solution such as KOH or NaOH.

As the product, the weight loss portion after weight loss is most preferably 0.5 to 1 mm.

The length and shape of the weight loss are important as the monofilament for toothbrush hair. When the weight reduction is a cylindrical shape, only the edge of the rim should be slightly processed, so if the temperature is low, the weight loss time is long. If the temperature is low or the concentration is too low, the required product cannot be obtained because the weight loss is low. If the temperature is too high or the concentration is too high, the tip of the monofilament for toothbrush hair is not softened, so the touch is not soft and cannot be applied as a product. Depth affects the shape and elasticity of the product's weight loss.

In addition, if the immersion time is too short, the weight loss is made less, if the immersion time is too long, a lot of weight loss occurs that can not be applied to the product. Therefore, the harmony between these conditions is very important.

As described above, it is possible to obtain elasticity and softness of a suitable use for the bristles according to the present invention, and to obtain a polyester monofilament having excellent competitiveness in productivity and price.

Hereinafter, the present invention will be described in more detail with reference to Examples as follows, but the present invention is not limited by the Examples.

Example 1

First, a PBT resin having a melt viscosity of 225 ° C. and an intrinsic viscosity of 1.8 was produced by extruding a circular type monofilament with a diameter of 0.70 mm using a single screw extruder, and bundled into a bundle and cut into 30 mm lengths.

As shown in Table 3, the final 28 mm long bristles of both sides were produced at different concentrations and temperatures of the m-cresol solution at different immersion times and immersion depths.

The high viscosity PBT bristle monofilament thus obtained was washed and rinsed to remove dissolved sludge and m-cresol solution from the product, followed by hot air for 12 hours at 55 ° C. The weight loss state, the total length of the product, and the length of the weight loss site were measured.

The results are shown in Table 4 below.

[Comparative Examples 1-6]

After performing the same as in the above Example, but produced under the conditions shown in Table 3, the results are shown in Table 4 below.

TABLE 3

TABLE 4

Claims (3)

To reduce the monofilament made of polyethylene terephthalate or polybutylene terephthalate resin to produce a monofilament for toothbrush hair, the weight loss treatment by immersing the monofilament in m-cresol solution when the weight loss Method for producing ester monofilament. The method of claim 1, wherein the m-cresol solution is a method for producing a polyester monofilament for toothbrushes, characterized in that 10 to 40% solution neutralized with NaOH or KOH. The method of claim 1, wherein the conditions of the weight loss treatment is a treatment liquid temperature of 70 ~ 100 ℃, immersion time 0.5 ~ 1 hour, immersion depth 1 ℃ 2mm method for producing a polyester monofilament for brush hair.