KR102136382B1 - Aramid composite and helmet comprising the same - Google Patents

Abstract

The aramid composite material according to the present invention includes an aramid fabric and a thermoplastic adhesive film laminated on one side of the aramid fabric, characterized in that the content of the thermoplastic adhesive film in the aramid composite material is 10 to 20% by weight.
The thermoplastic adhesive film is composed of an ethylene-vinyl acetate copolymer or a thermoplastic polyurethane resin.
The helmet according to the present invention is composed of an outer layer and an inner layer in which 1 to 3 aramid prepregs in which a phenol resin is dipped in an aramid fabric and an intermediate layer in which 15 to 20 aramid composites are stacked.
Since the aramid composite material of the present invention includes a thermoplastic adhesive film instead of a phenolic resin, it can solve the conventional problems of freezing in a freezing container during transportation to prevent curing, and also has excellent helmet formability.
The helmet of the present invention has excellent ballistic performance, while greatly improving light weight.

Description

Aramid composite and helmet comprising the same}

The present invention relates to an aramid composite material and a helmet including the same, and more specifically, an aramid composite material having significantly improved light weight while satisfying the level of bulletproof performance required by the industry without the need for freezer storage during transportation to prevent curing It is about the helmet to include.

Bulletproof products are products for protecting the human body from bullets and shells, and the bulletproof performance of bulletproof products depends largely on the material used.

Among these materials for bulletproof, high density polyethylene has a specific gravity of 0.98 lower than that of water, so it is widely used as a material for bulletproof.

However, high-density polyethylene may have a large deformation when subjected to a physical impact during use, and has weak heat characteristics. Particularly, when applied to a helmet, there was a limitation in obtaining excellent bulletproof performance by locally deforming the inner surface layer to the inside of the helmet during the impact of the bomb, resulting in a deformation greater than the allowable safety separation distance.

Among other ballistic materials, the wholly aromatic polyamide fibers, commonly referred to as aramid fibers, include para-aramid fibers having a structure in which benzene rings are linearly connected through an amide group (-CONH) and meta-aramid fibers that are not. do. Para-aramid fiber has excellent properties such as high strength, high elasticity, and low shrinkage. It is widely used for bulletproof applications because it has a strong strength enough to lift 2 tons of automobiles with a thin thread about 5 mm thick.

Bulletproof composite materials are usually prepared by using para-aramid fibers to produce aramid fabrics, and then immersing these aramid fabrics in resin to dry them to produce semi-cured aramid fabrics (aramid fabric prepregs) and several of these semi-cured aramid fabrics. After laminating in layers, it is cured to complete.

However, in the case of manufacturing a semi-cured aramid fabric using such an immersion process, it is impossible to obtain a semi-cured aramid fabric of uniform weight by varying the amount of the impregnated resin according to the concentration of the resin solution and the squeezing pressure. Since resin was impregnated on both sides, it was difficult to obtain an excellent lightweight semi-cured aramid fabric.

In addition, the phenolic resin widely used in the production of semi-cured aramid fabrics has a molecular weight of 3,000 to 4,000, which means that it has poor moldability due to its hard properties and does not strongly adhere to the aramid fabrics, thus providing excellent bulletproof performance.

On the other hand, in Korean Patent Publication No. 10-2011-0009441, an aramid composite material and a helmet made of the aramid fabric formed of a resin coating layer comprising phenolic resin and polyvinylbutyral (PVB) having a molecular weight of 50,000 to 60,000 on one side of the aramid fabric However, the prior art has a low molecular weight of polyvinyl butyral, and thus the resin coating layer is fragile, and when releasing the wound aramid composite material, the resin grains fall and workability decreases, and the performance of the manufactured bulletproof helmet decreases. There was a problem.

On the other hand, in Korean Patent Application No. 10-2013-0163819, an aramid composite material and a helmet made of a laminated film composed of a phenolic resin having a molecular weight of 500 to 2,000 and a polyvinyl butyral having a molecular weight of 80,000 to 120,000 are coated on one side of the aramid fabric. Although described, the prior art has solved the conventional problem that the film laminated to the aramid fabric is fragile because the molecular weight of the phenolic resin is low and the molecular weight of the polyvinyl butyral is high, but it is stored frozen during transportation to prevent curing of the phenolic resin. There was a hassle to do.

Accordingly, the present invention relates to an aramid composite material and a helmet including the same, which can prevent problems caused by limitations and disadvantages of the related art.

An object of the present invention is to provide an aramid composite material and a helmet including the same, which significantly improves lightweight while satisfying the level of bulletproof performance required by the industry.

Another object of the present invention is to provide an aramid composite material and a helmet including the same, which can solve the conventional problem that must be stored frozen during transportation to prevent curing of the semi-cured film laminated to the aramid composite material.

Still other features and advantages of the invention are described below, and will be apparent in part from such techniques. Or, other features and advantages of the present invention may be understood through the practice of the present invention. The objects and other advantages of the present invention will be realized and attained by the structure specified in the detailed description and claims of the invention.

In order to achieve the above problems, the present invention includes an aramid fabric and aramid composite material comprising a thermoplastic adhesive film laminated to one side of the aramid fabric, the content of the thermoplastic adhesive film in the aramid composite material is 10 to 20% by weight Provides

In addition, in the present invention, the aramid fabric is composed of an outer layer and an inner layer in which 1 to 3 aramid prepregs laminated with phenol resin are stacked, and an intermediate layer in which 15 to 20 aramid composites are stacked, and the total weight is 1400 g or less, and MIL -Provides helmets with average speed (V50) of 610~660m/s measured according to STD662F.

According to the aramid composite material of the present invention, by coating the resin on only one side of the aramid fabric using a laminating process, the resin content can be significantly lowered, providing excellent light weight, and uniformly coating the resin to provide excellent bulletproof performance can do.

Since the aramid composite material of the present invention includes a thermoplastic adhesive film instead of a phenolic resin, it can solve the conventional problems that must be stored frozen in a refrigerated container during transportation to prevent curing, and has excellent helmet formability.

The helmet of the present invention has excellent ballistic performance while greatly improving light weight.

It will be apparent to those skilled in the art that various changes and modifications of the present invention are possible without departing from the spirit and scope of the present invention. Accordingly, the present invention includes all modifications and variations falling within the scope of the invention and equivalents described in the claims.

The aramid composite material according to the present invention comprises an aramid fabric and a thermoplastic adhesive film laminated on one side of the aramid fabric, characterized in that the content of the thermoplastic adhesive film in the aramid composite compared to the total weight of the aramid composite material is 10 to 20% by weight.

If the content of the thermoplastic adhesive film is less than 10% by weight, the adhesion between the aramid composites during lamination decreases, and if it exceeds 20% by weight, the ballistic performance decreases and the weight of the ballistic helmet increases, which is not preferable.

The thermoplastic adhesive film is composed of an ethylene-vinyl acetate copolymer or a thermoplastic polyurethane resin.

Since the aramid composite material adheres the thermoplastic adhesive film to only one side of the aramid fabric by using a laminating process, the amount of resin impregnation in the aramid fabric can be lowered, resulting in improved light weight and uniform resin impregnation, thereby improving ballistic resistance.

In addition, since the aramid composite material uses the thermoplastic resin instead of the conventional phenolic resin, it is possible to solve the conventional hassle that must be stored frozen to prevent curing during transportation.

Hereinafter, an example of implementation of the method for manufacturing the aramid composite of the present invention will be described in detail.

The aramid composite material of the present invention includes the steps of manufacturing an aramid fabric and laminating a thermoplastic adhesive film on one side of the aramid fabric.

First, a method of manufacturing the aramid fabric will be described.

The aramid fiber used for the production of the aramid fabric is produced by the following method. An aromatic polyamide polymer is prepared by polymerizing an aromatic diamine and an aromatic dieside chloride in a polymerization solvent, and then spinning a spinning dope containing the aromatic polyamide polymer through a spinneret and solidifying to prepare an aramid fiber.

It is preferable that the aramid fiber has a total fineness in the range of 600 to 3,000 denier. If the total fineness is less than 500 denier, the density may have to be increased after weaving, so productivity may decrease, whereas when the total fineness exceeds 4,000 denier, weaving processability may decrease.

It is preferable that the aramid fiber has a tensile strength of 20 g/d or more, and if aramid fiber having a low tensile strength is used, it is difficult to obtain bulletproof performance as required by the industry.

The aramid fabric serving as a support for the aramid composite material can use various types of fabric, but it can use an aramid fabric that provides excellent bulletproof performance and is relatively easy to manufacture.

Hereinafter, a method of manufacturing an aramid fabric will be described. After producing the inclined beam by applying the aramid fiber produced by the above-described method as a slope, the aramid fabric is completed by installing the inclined beam on a loom and applying the aramid fiber as a weft to weave. At this time, the aramid fabric is preferably plain weave, or basket weave structure. Since such a plain or basket weave structure is formed while the warp and the weft yarns form a certain bend, it can provide excellent bullet-proof performance by dispersing the external force uniformly over the entire fabric when receiving an external force such as a bullet.

In addition, it is preferable that the aramid fabric has a density of 150 to 520 g/m 2. If the density is too low, space may be generated in the fabric, and thus the bulletproof performance may be deteriorated. If the density is too high, the production efficiency may be greatly reduced because the fabric is not easy to manufacture.

Next, a method for manufacturing the aramid composite material will be described.

The aramid composite is completed by sequentially performing a step of attaching a thermoplastic adhesive film to the aramid fabric prepared by the above-described method, pressing the aramid fabric to which the thermoplastic adhesive film is attached, and drying the pressurized aramid fabric. .

The step of attaching the thermoplastic adhesive film to the aramid fabric may be performed through a continuous process or a non-continuous process. In the continuous process, the aramid fabric and the thermoplastic adhesive film are respectively supplied simultaneously by separate supply rollers, and then the aramid fabric and the thermoplastic adhesive film are attached to each other. In the non-continuous process, after preparing the aramid fabric of a certain size and the thermoplastic adhesive film, the aramid fabric of the constant size and the thermoplastic adhesive film are sequentially aligned and attached.

The step of pressing the aramid fabric to which the thermoplastic adhesive film is attached may be performed continuously using a pressure roller or discontinuously using a pressure plate.

The step of drying the pressurized aramid fabric may be performed continuously using a chamber or the like, or discontinuously using a heating plate.

On the other hand, the helmet according to the present invention, the outer layer of the aramid fabric is aramid fabric pre-preg 1 to 3 sheets of phenolic resin is laminated, aramid composite on the one side of the aramid fabric laminated aramid composite material 15 to 20 sheets intermediate layer and The aramid fabric is composed of 1 to 3 aramid prepregs laminated with phenolic resin layered inside.

The bulletproof helmet has an average speed (V50) measured according to MIL-STD-662F regulations of 610 to 660 Hz, thereby providing excellent bulletproof performance. In this case, the average speed is measured from the average value of the speed at the time of complete penetration and the speed at the time of partial penetration using Cal.22-diameter fragment simulation (FSP).

In addition, the bullet-proof helmet has an overall weight of 1400 g or less. If the total weight exceeds 1400g, the combat power of the soldiers is significantly reduced.

Looking at the implementation example of manufacturing the helmet, a phenolic resin-doped aramid prepreg 1 to 3 sheets are stacked in a helmet manufacturing mold, and then 15 to 20 aramid composites are stacked thereon, and then again On the aramid fabric, 1 to 3 aramid prepregs with dipping of phenolic resin are stacked, and then heat-treated at high temperature to apply high pressure to produce a helmet.

Hereinafter, the present invention will be described in detail through examples and comparative examples. However, the following examples are only to aid the understanding of the present invention, so the scope of the present invention should not be limited.

Example One

Aromatic diamine para-phenylenediamine and aromatic diacid chloride terephthaloyl dichloride were polymerized in an N-methyl-2-pyrrolidone polymerization solvent to prepare a poly paraphenylene terephthalamide polymer, and then the polymer Was dissolved in a concentrated sulfuric acid solvent to prepare a spinning dope, and the spinning dope was spun through a spinneret and solidified to prepare 3,000 denier wholly aromatic aramid fibers.

Thereafter, the aramid fibers were respectively applied to warp and weft yarns and woven into plain weaves to prepare aramid fabrics having a density of 450 g/m 2.

Next, an aramid composite material was prepared by laminating a thermoplastic adhesive film made of an ethylene-vinyl acetate copolymer on one side of the aramid fabric prepared as described above.

At this time, the content of the thermoplastic adhesive film in the aramid composite compared to the total weight of the aramid composite was set to 10% by weight.

Meanwhile, an aramid fabric prepreg impregnated with phenol resin was prepared by dipping the aramid fabric prepared as above into a phenol resin solution.

Next, three aramid fabric prepregs impregnated with phenolic resin were stacked in a mold for manufacturing a helmet, and then 17 aramid composites prepared as above were stacked thereon, and then phenolic resin was continuously impregnated thereon. After stacking the three aramid fabric prepregs, a helmet was manufactured by pressure-molding for 20 minutes under a pressure of 160 bar and a temperature of 150°C.

The average speed (V50) of the manufactured helmet, the standard deviation showing the uniformity of the content of the resin impregnated in the aramid fabric, and the results of measuring the total weight of the helmet are shown in Table 1.

Example 2

Aromatic diamine para-phenylenediamine and aromatic diacid chloride terephthaloyl dichloride were polymerized in an N-methyl-2-pyrrolidone polymerization solvent to prepare a poly paraphenylene terephthalamide polymer, and then the polymer Was dissolved in a concentrated sulfuric acid solvent to prepare a spinning dope, and the spinning dope was spun through a spinneret and solidified to prepare 3,000 denier wholly aromatic aramid fibers.

Thereafter, the aramid fibers were respectively applied to warp and weft yarns and woven into plain weaves to prepare aramid fabrics having a density of 450 g/m 2.

Next, an aramid composite material was prepared by laminating a thermoplastic adhesive film made of a thermoplastic polyurethane resin on one side of the aramid fabric prepared as described above.

At this time, the content of the thermoplastic adhesive film in the aramid composite compared to the total weight of the aramid composite was set to 14% by weight.

Meanwhile, an aramid fabric prepreg impregnated with phenol resin was prepared by dipping the aramid fabric prepared as above into a phenol resin solution.

Next, two aramid fabric prepregs impregnated with phenolic resin were molded in a mold for manufacturing a helmet, and then 19 aramid composites prepared as above were stacked thereon, and then phenolic resin was continuously impregnated thereon. Two laminated aramid fabric prepregs were stacked, and then press-molded at a pressure of 160 bar and a temperature of 150° C. for 20 minutes to prepare a helmet.

The average speed (V50) of the manufactured helmet, the standard deviation showing the uniformity of the content of the resin impregnated in the aramid fabric, and the results of measuring the total weight of the helmet are shown in Table 1.

Example 3

Aromatic diamine para-phenylenediamine and aromatic diacid chloride terephthaloyl dichloride were polymerized in an N-methyl-2-pyrrolidone polymerization solvent to prepare a poly paraphenylene terephthalamide polymer, and then the polymer Was dissolved in a concentrated sulfuric acid solvent to prepare a spinning dope, and the spinning dope was spun through a spinneret and solidified to prepare 3,000 denier wholly aromatic aramid fibers.

Thereafter, the aramid fibers were respectively applied to warp and weft yarns and woven into plain weaves to prepare aramid fabrics having a density of 450 g/m 2.

Next, an aramid composite material was prepared by laminating a thermoplastic adhesive film made of an ethylene-vinyl acetate copolymer on one side of the aramid fabric prepared as described above.

At this time, the content of the thermoplastic adhesive film in the aramid composite compared to the total weight of the aramid composite was set to be 17% by weight.

Meanwhile, an aramid fabric prepreg impregnated with phenol resin was prepared by dipping the aramid fabric prepared as above into a phenol resin solution.

Next, three aramid fabric prepregs impregnated with phenolic resin were stacked in a mold for manufacturing a helmet, and then 17 aramid composites prepared as above were stacked thereon, and then phenolic resin was continuously impregnated thereon. After stacking the three aramid fabric prepregs, a helmet was manufactured by pressure-molding for 20 minutes under a pressure of 160 bar and a temperature of 150°C.

The average speed (V50) of the manufactured helmet, the standard deviation showing the uniformity of the content of the resin impregnated in the aramid fabric, and the results of measuring the total weight of the helmet are shown in Table 1.

Example 4

Aromatic diamine para-phenylenediamine and aromatic diacid chloride terephthaloyl dichloride were polymerized in an N-methyl-2-pyrrolidone polymerization solvent to prepare a poly paraphenylene terephthalamide polymer, and then the polymer Was dissolved in a concentrated sulfuric acid solvent to prepare a spinning dope, and the spinning dope was spun through a spinneret and solidified to prepare 3,000 denier wholly aromatic aramid fibers.

Thereafter, the aramid fibers were respectively applied to warp and weft yarns and woven into plain weaves to prepare aramid fabrics having a density of 450 g/m 2.

Next, an aramid composite material was prepared by laminating a thermoplastic adhesive film made of an ethylene-vinyl acetate copolymer on one side of the aramid fabric prepared as described above.

At this time, the content of the thermoplastic adhesive film in the aramid composite compared to the total weight of the aramid composite was set to 20% by weight.

Meanwhile, an aramid fabric prepreg impregnated with phenol resin was prepared by dipping the aramid fabric prepared as above into a phenol resin solution.

Next, two aramid fabric prepregs impregnated with phenolic resin were molded in a mold for manufacturing a helmet, and then 19 aramid composites prepared as above were stacked thereon, and then phenolic resin was continuously impregnated thereon. Two laminated aramid fabric prepregs were stacked, and then press-molded at a pressure of 160 bar and a temperature of 150° C. for 20 minutes to prepare a helmet.

The average speed (V50) of the manufactured helmet, the standard deviation showing the uniformity of the content of the resin impregnated in the aramid fabric, and the results of measuring the total weight of the helmet are shown in Table 1.

Comparative Example One

Aromatic diamine para-phenylenediamine and aromatic diacid chloride terephthaloyl dichloride were polymerized in an N-methyl-2-pyrrolidone polymerization solvent to prepare a poly paraphenylene terephthalamide polymer, and then the polymer Was dissolved in a concentrated sulfuric acid solvent to prepare a spinning dope, and the spinning dope was spun through a spinneret and solidified to prepare 3,000 denier wholly aromatic aramid fibers.

Thereafter, the aramid fibers were respectively applied to warp and weft yarns and woven into plain weaves to prepare aramid fabrics having a density of 450 g/m 2.

Next, an aramid composite material was prepared by laminating a resin film composed of 65% by weight of a phenolic resin having a molecular weight of 550 and 35% by weight of a polyvinylbutyl resin having a molecular weight of 90,000 on one side of the aramid fabric prepared as described above.

Next, 23 sheets of the aramid composite were laminated in a mold for manufacturing a helmet, and then press-molded at a pressure of 160 bar and a temperature of 150° C. for 20 minutes to manufacture a helmet.

The average speed (V50) of the manufactured helmet, the standard deviation showing the uniformity of the content of the resin impregnated in the aramid fabric, and the results of measuring the total weight of the helmet are shown in Table 1.

Comparative Example 2

Aromatic diamine para-phenylenediamine and aromatic diacid chloride terephthaloyl dichloride were polymerized in an N-methyl-2-pyrrolidone polymerization solvent to prepare a poly paraphenylene terephthalamide polymer, and then the polymer Was dissolved in a concentrated sulfuric acid solvent to prepare a spinning dope, and the spinning dope was spun through a spinneret and solidified to prepare 3,000 denier wholly aromatic aramid fibers.

Thereafter, the aramid fibers were respectively applied to warp and weft yarns and woven into plain weaves to prepare aramid fabrics having a density of 450 g/m 2.

Next, an aramid fabric prepreg impregnated with phenol resin was prepared by dipping the aramid fabric prepared as above into a phenol resin solution.

Next, 23 sheets of aramid fabric prepreg impregnated with phenolic resin were stacked in a mold for manufacturing a helmet, and then press-molded at a pressure of 160 bar and a temperature of 150°C for 20 minutes to prepare a helmet.

The average speed (V50) of the manufactured helmet, the standard deviation showing the uniformity of the content of the resin impregnated in the aramid fabric, and the results of measuring the total weight of the helmet are shown in Table 1.

Comparative Example 3

Aromatic diamine para-phenylenediamine and aromatic diacid chloride terephthaloyl dichloride were polymerized in an N-methyl-2-pyrrolidone polymerization solvent to prepare a poly paraphenylene terephthalamide polymer, and then the polymer Was dissolved in a concentrated sulfuric acid solvent to prepare a spinning dope, and the spinning dope was spun through a spinneret and solidified to prepare 3,000 denier wholly aromatic aramid fibers.

Thereafter, the aramid fibers were respectively applied to warp and weft yarns and woven into plain weaves to prepare aramid fabrics having a density of 450 g/m 2.

Next, an aramid composite material was prepared by laminating a thermoplastic adhesive film made of an ethylene-vinyl acetate copolymer on one side of the aramid fabric prepared as described above.

At this time, the content of the thermoplastic adhesive film in the aramid composite compared to the total weight of the aramid composite was set to 9% by weight.

Meanwhile, an aramid fabric prepreg impregnated with phenol resin was prepared by dipping the aramid fabric prepared as described above into a phenol resin solution.

Next, three aramid fabric prepregs impregnated with phenolic resin were stacked in a mold for manufacturing a helmet, and then 17 aramid composites prepared as above were stacked thereon, and then phenolic resin was continuously impregnated thereon. After stacking three sheets of aramid fabric prepreg, a helmet was manufactured by pressure-molding at 160 bar and 150° C. for 20 minutes.

The average speed (V50) of the manufactured helmet, the standard deviation showing the uniformity of the content of the resin impregnated in the aramid fabric, and the results of measuring the total weight of the helmet are shown in Table 1.

Comparative Example 4

Aromatic diamine para-phenylenediamine and aromatic diacid chloride terephthaloyl dichloride were polymerized in an N-methyl-2-pyrrolidone polymerization solvent to prepare a poly paraphenylene terephthalamide polymer, and then the polymer Was dissolved in a concentrated sulfuric acid solvent to prepare a spinning dope, and the spinning dope was spun through a spinneret and solidified to prepare 3,000 denier wholly aromatic aramid fibers.

Thereafter, the aramid fibers were respectively applied to warp and weft yarns and woven into plain weaves to prepare aramid fabrics having a density of 450 g/m 2.

Next, an aramid composite material was prepared by laminating a thermoplastic adhesive film made of an ethylene-vinyl acetate copolymer on one side of the aramid fabric prepared as described above.

At this time, the content of the thermoplastic adhesive film in the aramid composite relative to the total weight of the aramid composite was set to 22% by weight.

Meanwhile, an aramid fabric prepreg impregnated with phenol resin was prepared by dipping the aramid fabric prepared as described above into a phenol resin solution.

Next, three aramid fabric prepregs impregnated with phenolic resin were stacked in a mold for manufacturing a helmet, and then 17 aramid composites prepared as above were stacked thereon, and then phenolic resin was continuously impregnated thereon. After stacking three sheets of aramid fabric prepreg, a helmet was manufactured by pressure-molding at 160 bar and 150° C. for 20 minutes.

The average speed (V50) of the manufactured helmet, the standard deviation showing the uniformity of the content of the resin impregnated in the aramid fabric, and the results of measuring the total weight of the helmet are shown in Table 1.

division Total weight (g) Standard Deviation Average speed (V50) Example 1 1,390 2.7 641 Example 2 1,385 2.8 642 Example 3 1,400 2.7 641 Example 4 1,410 2.8 642 Comparative Example 1 1,390 3.2 617 Comparative Example 2 1,400 12.3 563 Comparative Example 3 1,380 8.0 610 Comparative Example 4 1,480 3.5 580

The standard deviation and average speed (V50) in Table 1 were measured in the following manner.

Standard deviation measurement

The standard deviation, which indirectly indicates the degree of content uniformity of the resin impregnated in the aramid fabric, was measured by taking samples of 10 aramid composites and obtaining the weight per square meter, respectively.

Average speed( V50 ) Measure

The average velocity (m/s) indirectly indicating the degree of bulletproof performance of the aramid composites was partially penetrated with the velocity when fully penetrated by using Cal.22 caliber fragment simulation ball (FSP) according to MIL-STD-662F. The speed at the time was measured from the average value.

The aramid composites prepared in Example 1 and Example 2 were not cured even when stored at room temperature for 10 days without refrigeration treatment, but the aramid composites prepared in Comparative Example 1 and Comparative Example 2 were at room temperature without freezing treatment. Hardening occurred severely when stored for 10 days at.

Claims (4)

Aramid fabric with 1~3 aramid prepregs laminated with phenolic resin, outer layer with 1~3 laminated aramid composites, middle layer with 15~20 aramid composites stacked, and 1~3 aramid prepregs with phenolic resin dipped on aramid fabric Consists of an outer layer, the total weight is 1400g or less, and the average speed (V50) measured according to MIL-STD-662F is 641~660㎧,
The aramid composite material includes an aramid fabric and a thermoplastic adhesive film laminated on one side of the aramid fabric, the content of the thermoplastic adhesive film in the aramid composite compared to the total weight of the aramid composite material is 10 to 20% by weight, the thermoplastic adhesive film is ethylene-vinyl It is composed of one resin selected from acetate copolymers and thermoplastic polyurethane resins,
Helmet characterized in that the average speed was measured from the average value of the speed when fully penetrated and the partial penetration rate using Cal.22 caliber fragment grenade (FSP). delete delete delete