KR100510765B1 - Aromatic Polyamide Pulp and Its Manufacturing Method - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to an aromatic polyamide pulp used in asbestos substitute and the like and a method for producing the same.

2. The technical problem to be solved by the invention

The present invention provides a method for preparing aromatic polyamide pulp having excellent physical properties such as wet volume and Canadian standard pristine value while maintaining hydrogen bonds between molecular chains in the polymer even after the final milling for pulping.

3. Summary of Solution to Invention

Aromatic polyamide polymers prepared by reacting aromatic diamines and aromatic dieside chlorides in the presence of a polymerization solvent are oriented, cleaved, and aged, and the first extraction of the polymerization solvent in the matured polymer is followed by the first grinding and the After the second extraction of the polymerization solvent, it is finally milled.

4. Important uses of the invention

The aromatic polyamide pulp of the present invention is used for gaskets, brake linings, resin reinforcing agents, and the like.

Description

Aromatic Polyamide Pulp and Method for Making the Same.

The present invention relates to aromatic polyamide pulp and a process for producing the same. In general, aromatic polyamide pulp is excellent in strength, elasticity, heat resistance, abrasion resistance, and electrical insulation, and thus is useful for composite materials, building materials, leisure, and sporting goods in the aircraft and automobile industries.

Aromatic polyamide polymers are prepared by reacting an aromatic diamine with an aromatic dieside chloride in an amide solvent, a urea solvent, or a mixed solvent thereof with an inorganic salt alone or a polymerization solvent in which an inorganic salt and a Lewis acid compound are added. The aromatic polyamide polymer thus polymerized is pulverized immediately after being oriented, cut and aged, or the polymerized solvent is extracted and then pulverized to prepare an aromatic polyamide pulp.

Conventional techniques for producing aromatic polyamide pulp include US Pat. No. 5, 028, 372 and Korean Patent Application No. 95-66480.

First, US Pat. No. 5, 028, 372 polymerizes an aromatic polyamide polymer by reacting an aromatic diamine and an aromatic dieside chloride in the polymerization solvent, and then aligns, cuts, and ages it, followed by grinding without undergoing extraction of the polymerization solvent. The aromatic polyamide pulp is prepared by separating the pulp and the polymerization solvent on a belt filter. However, this method does not extract the remaining polymerization solvent in the polymer after the aging process, and breaks the weak hydrogen bonds between the molecular chains of the polymers formed in the aging process by pulverizing the polymer with a large mechanical energy, thereby causing a wet volume and canadiane. There is a problem that pulp properties such as Canadian Standard Freeness (hereinafter referred to as CSF) are deteriorated.

Meanwhile, in Korean Patent Application No. 95-66480, before pulverizing the aromatic polyamide polymer polymerized, oriented, cleaved and aged as described above, 75% of the polymerization solvent remaining in the polymer is extracted with water and then pulverized to form an aromatic polyamide pulp. Manufacture.

In this method, since the polymerization solvent is first extracted before grinding, aromatic polyamide pulp having somewhat better physical properties than the method of US Pat. No. 5, 028, 372 can be prepared. However, even after the polymerization solvent extraction process, a large amount of polymerization solvent is present in the polymer. The problem of remaining and breaking hydrogen bonds in the polymer upon grinding is not fundamentally solved. As a result, the wet volume of the aromatic polyamide pulp and the physical properties such as C.S.F do not improve as much as desired.

In addition, in order to minimize the residual polymerization solvent in the polymer after the extraction process has been proposed a method of cutting the polymer into a small size and performing the extraction process for a long time, but such a method is not economical due to the long process time.

The present invention is to provide a method for producing an aromatic polyamide pulp having excellent physical properties such as wet volume and CSF by efficiently extracting the polymerization solvent present in the polymer before final grinding to maintain hydrogen bonds between the polymer molecular chains even after grinding. .

The present invention relates to an aromatic polyamide pulp having excellent physical properties and a method for producing the same. Specifically, it relates to an aromatic polyamide pulp having a wet volume of 700 ml or more and a Canadian Standard Prinis (C.S.F) value of 500 ml or less.

In addition, the present invention, the aromatic polyamide polymer prepared by reacting an aromatic diamine and an aromatic dieside chloride in a polymerization solvent is oriented, cleaved and aged, and the primary polymer is first extracted with water and then pulverized. The present invention relates to a method for producing an aromatic polyamide pulp by second extraction of a polymerized solvent in a pulverized polymer followed by final pulverization.

The present invention produces aromatic polyamide pulp having excellent physical properties by extracting the polymerization solvent in the polymer in two stages before and after the first grinding, respectively, without breaking the hydrogen bonds in the molecular chain of the polymer during grinding.

The present invention will be described in more detail.

First, an aromatic polyamide polymer is prepared by reacting an aromatic diamine and an aromatic dieside chloride in a conventional manner in the presence of a polymerization solvent.

The polymerization solvent used in the present invention is an amide organic solvent, urea organic solvent, or a mixed solvent thereof in which an inorganic salt alone or a mixture of an inorganic salt and a small amount of a Lewis acid compound is added. After the polymerized aromatic polyamide polymer is oriented, cut and aged, the polymerization solvent in the matured polymer is first extracted.

At this time, it is preferable to use water as the extract used. In the primary extraction method, the polymerization solvent may be extracted for a predetermined time by introducing water and a polymer into a batch vessel, or may be extracted while continuously supplying the polymer and water in a cylindrical horizontal or upright washing tank.

The polymer and water are then brought into contact in countercurrent or cocurrent flow.

In the first extraction process, it is preferable to set the process conditions so as to extract about 75% of the polymerized solvent in the polymer. The polymer in which the primary extraction process of the polymerization solvent is completed is firstly ground. At this time, it is preferable to use a single disk mill (Single Disk Mill) as a mill, but the present invention does not specifically limit the type of mill. When using a single disc mill, the plate spacing of the mill is preferably at least 0.75 mm.

If the plate spacing is narrower than the above range, it is difficult to obtain the pulp physical properties of the present invention. The polymerization solvent remaining in the first milled polymer is secondarily extracted on a belt filter. At this time, the belt filter is preferably 12 or more stages for the extraction of the polymerization solvent. It is preferable to set the secondary extraction process conditions so that the residual polymerization solvent in the polymer after the secondary extraction process can be 2% or less. When the residual polymerization solvent in the polymer exceeds 2% after the secondary extraction process, hydrogen bonds between the molecular chains of the polymer are broken at the final milling, thereby making it difficult to obtain pulp properties of the present invention. It is preferable to use water also as an extract liquid of a secondary extraction process. The polymer subjected to the secondary extraction process is finally milled to produce aromatic polyamide pulp. As the grinder used for the secondary grinding, it is preferable to use a single disk grinder like the primary grinding, but the type of the grinder is not particularly limited.

The aromatic polyamide pulp of the present invention thus prepared is excellent in that the hydrobonding between the polymer molecular chains is maintained even after the final milling, so that the wet volume is 700 ml or more and the Canadian Standard Pristine (CSF) value is 500 ml or less. It has physical properties.

As described above, it is believed that the aromatic polyamide pulp of the present invention has excellent physical properties because the hydrogen-bonding present between the molecular chains of the polymer is maintained as it is after the final milling because the polymerization solvent in the polymer is efficiently extracted before the final milling.

In the present invention, various physical property evaluations are carried out as follows.

° Inherent Viscosity

_rel)/CIV (g / dl) = In (

_rel ) / C

_rel 은 30℃ 에서 모세관 점도계로 측정한 유동시간의 비이며, 용매는 95∼98% 의 농황산이다.Where C is the concentration of the polymer solution (solution obtained by dissolving 0.5 g of the polymer in 100 ml of 95-98% concentrated sulfuric acid) and the relative viscosity

_rel is the ratio of the flow time measured with a capillary viscometer at 30 ° C., and the solvent is 95-98% concentrated sulfuric acid.

° C.S.F (Canadian Standard Freeness)

The degree of freedom was measured by the method of ASTM-699-79.

° Floatation (wet volume of pulp)

1 g of the dried pulp is dissociated with 10,000 revolutions in 100 ml of water, and then put into a 1,000 ml volumetric cylinder to measure the volume of pulp after 2 minutes.

The content of the polymerization solvent contained in the polymer

10 g of the polymer was placed in 100 ml of methanol, extracted ultrasonically at 70 ° C. for 12 hours, and the polymerization solvent contained in the methanol extract was quantitatively analyzed by gas chromatography.

It will be described through the following Examples and Comparative Examples.

However, the present invention is not limited only to the examples.

Example 1

A polymerization solvent was prepared by completely dissolving 80 Kg of CaCl ₂ in 1,000 Kg of N-methyl-2-pyrrolidone at 80 ° C. 48.67 Kg of P-phenylene diamine was added to this polymerization solvent to dissolve to prepare a premix. The premix is fed into a mixer at a temperature of 5 ° C. at a rate of 1128.67 g / min using a metering pump.

At the same time, molten terephthaloyl chloride is added to the mixer at a rate of 27.41 g / min and mixed. In this way a prepolymer is prepared.

The prepared prepolymer was cooled to 5 ° C. and introduced into a continuous mixer at a rate of 1156.08 g / min, and molten terephthaloyl chloride was simultaneously added at a rate of 63.95 g / min to prepare a polymer. At this time, the temperature of the continuous mixer is maintained at 5 ℃. The polymer thus prepared is introduced into an aligning machine, oriented and coagulated to make a polymer, cut into suitable sizes, aged for 2 hours in a 70 ° C. polymerization solvent, and then the cut polymer is added to a washing bath together with water, followed by 4 at 70 ° C. The treatment is carried out for a time to first extract the polymer solvent in the polymer. The polymerization solvent extracted in the primary extraction process is 75% of the total polymerization solvent in the polymer before extraction.

The polymer having been subjected to the first extraction process was first ground using a 12 inch single disk mill from Andritz Sprout Bauer. At this time, the distance of the grinder plate is adjusted to 0.75 mm. The first pulverized polymer is secondarily extracted from the polymer solvent remaining in the polymer on a 12-stage continuous belt filter.

The polymerization solvent extracted in the primary and secondary extraction processes is 98% of the total polymerization solvent in the polymer before extraction. The polymer after the second extraction was mixed with water to prepare a slurry of 1%, followed by two passes through a 12 inch single disk mill from Andritz Sprout Bauer, which was finally ground to prepare an aromatic polyamide pulp. At this time, the plate spacing of the first grinder and the plate spacing of the second grinder are adjusted to 0.25 mm.

The results of measuring the physical properties of the prepared aromatic polyamide pulp are shown in Table 1.

Examples 2 to 3

Aromatic polyamide pulp was prepared in the same manner as in Example 1 except that the extraction degree of the polymerization solvent and the grinder plate spacing during the first grinding were changed as shown in Table 1. The results of measuring the physical properties of the prepared aromatic polyamide pulp are shown in Table 1.

Comparative Examples 1 to 4

An aromatic polyamide pulp was prepared in the same manner as in Example 1 except that the first grinding step and the second extraction step were omitted and the degree of polymerization solvent extraction was changed as shown in Table 2. The amount of polymer solvent extracted in the primary extraction step and the physical properties of the produced aromatic polyamide pulp are shown in Table 2.

<Table 1> Manufacturing Conditions and Product Properties of Examples

<Table 2> Manufacturing conditions and product properties of the comparative example

The present invention is to extract the polymerization solvent in the polymer in two stages to minimize the remaining polymerization solvent in the polymer to maintain the hydrogen bond between the molecular chains of the polymer even after pulverization for pulping to maintain the aromatic poly-polypropylene excellent in physical properties such as wet volume and CSF Amide pulp can be prepared.

1 is a process schematic diagram of the present invention,

2 and 3 are process schematics of the prior art.

Claims (4)

The aromatic polyamide polymer prepared by reacting aromatic diamine and aromatic dieside chloride in the presence of a polymerization solvent is oriented, cleaved, and aged, and the first extraction of the polymerization solvent in the matured polymer is followed by primary grinding with a single disk mill. A method of producing an aromatic polyamide pulp, characterized in that the polymerized solvent in the pulverized polymer is secondly extracted and then finally pulverized in a single disk mill so that the residual polymerized solvent in the polymer is 2% or less. The method for producing an aromatic polyamide pulp according to claim 1, wherein the plate spacing of the single disc mill used for the primary milling is 0.75 mm or more. The method for producing an aromatic polyamide pulp according to claim 1, wherein the polymerized solvent in the polymer is secondarily extracted in a belt filter of 12 or more stages. The process for producing an aromatic polyamide pulp according to claim 1, wherein the polymerization solvent is an inorganic salt alone or an amide organic solvent, urea organic solvent or a mixed solvent thereof to which a mixture of an inorganic salt and a small amount of Lewis acid compound is added. Way.

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