KR20220052576A - Plastic composite having improved mechanical properties and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a high-strength plastic composite with improved mechanical strength by adding a fiber-reinforcing material and tannic acid and, more specifically, to a high-strength plastic composite with better mechanical strength than a conventional fiber-reinforced plastic by adding a fiber reinforcing material such as aramid fiber, carbon fiber, glass fiber, and tannic acid which is a kind of polyphenol extracted from nature, such as a gall or a gallnut, chestnut, oak ash, and valonia, to plastic, and a manufacturing method thereof.

Description

Plastic composite having improved mechanical properties and method of manufacturing the same

The present invention provides a plastic composite with improved mechanical strength and a method for manufacturing the same. Specifically, unlike conventional fiber-reinforced plastics, tannic acid, a natural additive, is added to improve affinity and dispersibility between plastics and fibers used as reinforcing materials to provide higher mechanical strength. A high-strength plastic composite exhibiting strength and a manufacturing method thereof.

Fiber reinforced plastic (FRP), in which fibers such as glass fibers are mixed with plastic resin, is widely used as a method of reinforcing the mechanical strength of plastics. Most general reinforced plastics are widely used enough to be considered fiber-reinforced plastics. Fiber-reinforced plastics improve the mechanical strength of plastics like the relationship between reinforcing bars and concrete, and additionally, can dramatically improve heat resistance, water resistance, and chemical resistance. Recently, it has been used extensively in various facilities and equipment and in the chemical industry, replacing metals.

Korean Patent Publication No. 10-1777446 (2017.09.05.) relates to a glass fiber reinforced polyamide resin composition and plastic molded article, and polyhexamethylene adipamide (nylon 6, 6) and polycaprolactam (nylon 6) resins It is a glass fiber-reinforced polyamide resin composition comprising 30 to 70 wt% of glass fibers.

In addition, Korean Patent Publication No. 10-0761944 (2007.09.19.) relates to a method for manufacturing a composite plastic recycled material with improved mechanical strength by adding glass fibers to the recycled material film.

As such, the prior art uses fibers to increase the mechanical strength by adding fibers to the plastic, but as the amount of fibers used increases, the expression of the physical properties of the plastic itself decreases. is required

Korean Patent Publication No. 10-1777446 (2017.09.05) Korean Patent Publication No. 10-0761944 (2007.09.19)

Accordingly, an object of the present invention is to provide a method for manufacturing a reinforcing plastic in which the amount of a reinforcing material used for reinforcing mechanical strength is reduced in order to solve the above problems.

In order to solve the above problems, the present invention provides a high-strength plastic composite with improved mechanical strength as a high-strength plastic composite, characterized in that the plastic contains a fiber reinforcement and tannic acid.

In one embodiment of the present invention, the content of the fiber reinforcement in the composite may be 5 to 25 wt%, tannic acid 0.1 to 5 wt%.

In one embodiment of the present invention, the plastic is a thermoplastic or thermosetting resin, characterized in that the melting point is 260 ℃ or less.

In one embodiment of the present invention, the fiber reinforcement is characterized in that at least one selected from glass fiber, carbon fiber, aramid fiber and polyethylene fiber.

The present invention also comprises the steps of (a) adding and mixing tannic acid and a fiber reinforcement to molten plastic to obtain a plastic composite; (b) molding the plastic composite into a desired shape; provides a method for producing a high-strength plastic composite comprising improved mechanical strength.

In one embodiment of the present invention, in the step (a), tannic acid is first mixed with the molten plastic, and then the fiber reinforcement is mixed.

In one embodiment of the present invention, the molding temperature in step (b) is characterized in that it is maintained at about 20 ~ 30 ℃ lower than the melting temperature in step (a).

The high-strength plastic composite of the present invention and its manufacturing method are possible by a simple method of adding tannic acid during the manufacturing process of the existing fiber-reinforced plastic without an additional process such as modifying the surface of the fiber-reinforced material. Since the process is unnecessary, it is possible to increase productivity and reduce costs by simplifying the process and reducing the manufacturing time.

In addition, the composite produced by the method of the present invention can obtain higher mechanical strength than conventional fiber-reinforced plastics or reduce the amount of fiber reinforcement, and the chemical resistance, heat resistance, water resistance and scratch resistance of existing fiber-reinforced plastics It has the advantage of being able to keep the castle as it is.

1 is a molecular structure of tannic acid, which is one of the natural additives of the present invention.

Hereinafter, a glass fiber-reinforced plastic, which is a high-strength plastic composite having improved mechanical strength according to the present invention, will be described in detail. The terms or words used below should not be construed as being limited to conventional or dictionary meanings, and those having substantially the same configuration as the technical idea and achieving the same operational effects are included in the technical scope of the present invention. In addition, in the following description of the present invention, if it is determined that a detailed description of a related well-known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

Although plastic is lightweight, it is not suitable as a structural material due to its low modulus of elasticity. Therefore, it is possible to use a composite with a reinforcing material having a high modulus of elasticity such as glass fiber to increase mechanical strength. It is equivalent to reinforced concrete in that it is used as a practical material by combining the advantages of reversible and non-reversible materials.

There are two methods for mixing fibers as reinforcing materials, one in which finely cut fibers are arranged in equal directions to infiltrate into plastic, and one in which fiber is infiltrated into plastic with directionality. is manufactured in many

The present invention is based on the discovery of the fact that the addition of tannic acid to fiber-reinforced plastics significantly improves the mechanical strength of the plastics.

Hereinafter, the manufacturing method of the present invention will be described in more detail.

The method for producing a high-strength plastic composite with improved mechanical strength of the present invention comprises the steps of (a) adding tannic acid and a fiber reinforcement to molten plastic and mixing them to obtain a plastic composite; (b) molding the plastic composite into a desired shape; provides a method of manufacturing a plastic composite comprising a.

The fiber reinforcement in step (a) is a fiber with improved strength, and may be one or more selected from glass fiber, carbon fiber, aramid fiber, polyethylene fiber (dyneima), and the like.

The content of the fiber reinforcement may be 5 to 25 wt% of the total weight of the plastic composite. When the content of the fiber reinforcement is less than 5 wt%, the effect of increasing the strength is insignificant, and when it exceeds 25 wt%, the strength is rather reduced.

In step (a), tannic acid is added to the molten plastic. The tannic acid is a kind of polyphenol that exists in nature, such as quince or nutmeg, chestnut, oak wood, and valonia, and is a chemical substance that gives an astringent taste. The composition of the plastic composite according to the present invention contains 0.1 to 5 weight of the tannic acid. %, preferably 0.2 to 3 wt%, more preferably 0.3 to 2 wt%.

The plastic referred to in the present invention may be a thermoplastic or thermosetting resin other than rubber. However, since the melting point of the polymer resin is too high and thermal decomposition of tannic acid may occur, a polymer resin having a melting point of 260° C. or less, preferably a polymer resin having a melting point of 220° C. or less, is used. Of course, it can be applied to general-purpose plastics such as polypropylene, polyethylene, and nylon resins widely used in industry.

The order of adding tannic acid and fiber does not significantly affect the result, but in a continuous process, it can be added together with tannic acid and fiber reinforcement, or a method of adding tannic acid to molten plastic before fiber reinforcement.

The melting temperature for melting the plastic may be different depending on the type of plastic and processing equipment. The degree of melting is suitable to the extent that tannic acid and fiber reinforcement can be mixed. At too high a melting temperature, tannic acid and plastic may deteriorate and physical properties may be deteriorated. Therefore, it should be melted at a temperature at which deterioration does not occur. A suitable melting temperature may vary depending on the plastic used. For example, in the case of polypropylene in the range of 180 - 230 °C, in the case of polyethylene in the range of 130 - 180 °C.

After adding tannic acid and fiber reinforcement to the molten plastic, agitation is performed for dispersion. The stirring time varies depending on the processing equipment, but is generally dispersed for 5 to 60 minutes, preferably 7 to 15 minutes. If the dispersion time is short, the tannic acid does not form a sufficient chemical bond with the fiber reinforcement material and plastic, and the fiber reinforcement material is not well dispersed in the plastic composite, resulting in deterioration of physical properties. there is.

In step (b), the mixture obtained in step (a) is molded to prepare a desired shape. The molding temperature may be formed at an appropriate temperature depending on the type of plastic, but the temperature of the mold is generally preferably maintained at about 20 to 30° C. lower than the melting temperature in step (a).

The present invention also provides a high-strength plastic composite with improved tannic acid and fiber reinforcement, and a high-strength plastic composite containing tannic acid and fiber reinforcement.

The content of tannic acid in the high-strength plastic composite may be in the range of 0.1 to 5 wt%, and the fiber reinforcement may be in the range of 5 to 25 wt%.

The fiber reinforcing material is at least one selected from glass fiber, carbon fiber, aramid fiber, polyethylene fiber (Dyneima), etc., and the plastic as the base material of the high-strength plastic composite is a polymer resin having a melting point of 260° C. or less, preferably a melting point of 220° C. It may be a polymer resin of the following.

Hereinafter, examples will be given for a more detailed description of the present invention. However, the following examples are only preferred examples of the present invention, and the present invention is not limited thereto.

<Comparative Examples 1 to 10>

Put polypropylene in a kneader (twin screw internal mixer) preheated to 220 ° C. under the conditions described in Table 1 below and melt at 50 to 200 rpm for 3 minutes, and either fiber reinforcement or tannic acid is not added (Comparative Example 1 and 8) Alternately add fiber reinforcement or tannic acid (Comparative Examples 2 to 7, 9 and 10), melt at 50 to 200 rpm for 3 minutes, and mix for 6 to 9 minutes. Thereafter, the composite was molded by a hot-press preheated to 180° C. and cooled to room temperature.

The tensile strength of the obtained plastic composite was measured according to ASTM D638 (500KG, 500mm/min) method, and the results are shown in Table 1.

<Examples 1 to 6>

Put polypropylene into a kneader (twin screw internal mixer) preheated to 220 ° C under the conditions shown in Table 1 below, melt at 50 to 200 rpm for 3 minutes, add tannic acid, and mix for 3 minutes. Then, put the fiber reinforcement, melt for 3 minutes at 50 ~ 200 rpm, and mix for 6 ~ 9 minutes. Thereafter, the composite was molded by a hot-press preheated to 180° C. and cooled to room temperature.

The tensile strength of the obtained plastic composite was measured according to ASTM D638 (500KG, 500mm/min) method, and the results are shown in Table 1.

In Table 1, PP means polypropylene. Tannic acid was purchased from Sigma aldrich and used, PP was J320C from Lotte Chemical, and nylon-6 was purchased from BASF's B3L.

division plastic fiber reinforcement tannic acid
(wt%) The tensile strength
(MPa) Kinds Content (wt%) Kinds Content (wt%) Example 1 pp 89.5 fiberglass 10 0.5 32.02 Example 2 pp 85 fiberglass 10 5 26.87 Example 3 pp 79.5 fiberglass 20 0.5 27.07 Example 4 pp 89.5 carbon fiber 10 0.5 30.66 Example 5 pp 85 carbon fiber 10 5 26.77 Example 6 nylon-6 89.5 fiberglass 10 0.5 89.99 Comparative Example 1 pp 100 - - - 25.46 Comparative Example 2 pp 99.5 - - 0.5 26.01 Comparative Example 3 pp 95 - - 5 26.77 Comparative Example 4 pp 90 - - 10 23.91 Comparative Example 5 pp 90 fiberglass 10 - 27.21 Comparative Example 6 pp 80 fiberglass 20 - 19.85 Comparative Example 7 pp 90 carbon fiber 10 - 26.87 Comparative Example 8 nylon-6 100 - - - 66.33 Comparative Example 9 nylon-6 99.5 - - 0.5 66.42 Comparative Example 10 nylon-6 90 fiberglass 10 - 83.24

The fiber-reinforced plastic according to the present invention further enhances mechanical strength by adding tannic acid to the plastic in addition to the fiber reinforcement.

Example 1 of Table 1 shows that 10wt% of glass fiber and 0.5wt% of tannic acid were added to polypropylene, and the tensile strength was 32.02 Mpa, which was improved by 26% compared to the case of simple polypropylene alone (Comparative Example 1).

On the other hand, when 0.5wt% of tannic acid is simply added to polypropylene (Comparative Example 2), the tensile strength is 26.01 Mpa, which is only about 2% of the tensile strength enhancement effect compared to Comparative Example 1, and glass fiber is added to polypropylene by 10wt % added and tannic acid was not added (Comparative Example 5) shows the effect of enhancing the tensile strength to about 7%.

That is, the effect of improving mechanical strength according to the present invention is not the effect of simple summing the effects of tannic acid or fiber reinforcement alone, but shows a significant mechanical synergistic effect when tannic acid and fiber reinforcement are present at the same time.

When the content of tannic acid is changed without a fiber reinforcement (Comparative Examples 2 to 4), when the tensile strength of polypropylene is 5% of the content of tannic acid, the tensile strength is 26.77 MPa, which only brings about an increase of about 5% compared to Comparative Example 1. , it can be seen that the effect of the present invention cannot be obtained with tannic acid alone, even if it is seen that the tensile strength of polypropylene is rather decreased when the content of tannic acid is increased to 10%.

When the amount of glass fiber was increased to 20 wt% (Comparative Example 6), the tensile strength showed a tendency to decrease compared to pure polypropylene, indicating that an appropriate glass fiber content was present. It can be seen that the mechanical strength improvement effect of polypropylene is improved by the addition of tannic acid even when the content of is excessive (Example 3).

In addition, even when carbon fibers other than glass fibers are used (Example 4 and Comparative Example 7), the effect of increasing mechanical strength when tannic acid and carbon fibers are added together is a simple sum of the effect of adding each of tannic acid and carbon fibers. It can be seen that the effect is significantly increased.

In addition, in Example 2, in which the content of tannic acid was increased to 5 wt% in Example 1, the tensile strength was rather low. In addition, even in the case of carbon fibers other than glass fibers, when the content of tannic acid is increased from 0.5 to 5 wt% (Example 4 → Example 5), the tensile strength is reduced. On the other hand, in Comparative Examples 2 and 3, in which only tannic acid was added, the tensile strength slightly increased as the content of tannic acid increased from 0.5 wt% to 5 wt%. It can be predicted that the causes of the improvement of tensile strength when .

Even when nylon-6 was used by changing the type of plastic (Example 6 and Comparative Examples 8 to 10), the mechanical strength when tannic acid and fiber reinforcement were added together was significantly higher than when tannic acid or fiber reinforcement was alternatively added. show improvement. This is presumed to be the result of improving the mechanical strength of fiber-reinforced plastics by increasing the affinity between the fiber and the plastic substrate and dispersibility of the tannic acid.

As the specific parts of the present invention have been described in detail above, it will be clear to those of ordinary skill in the art that these specific descriptions are only preferred embodiments, and the scope of the present invention is not limited thereby. will be. Accordingly, it is intended that the substantial scope of the present invention be defined by the appended claims and their equivalents.

Claims (7)

As a high-strength plastic composite with improved mechanical strength,
High-strength plastic composite with improved mechanical strength, characterized in that the plastic contains fiber reinforcement and tannic acid
According to claim 1,
The high-strength plastic composite with improved mechanical strength, characterized in that the content of the fiber reinforcement comprises 5 to 25 wt%, and 0.1 to 5 wt% of tannic acid.
According to claim 1,
The high-strength plastic composite with improved mechanical strength, characterized in that the polymer resin has a melting point of 260° C. or less.
According to claim 1,
The fiber reinforcement is a high-strength plastic composite with improved mechanical strength, characterized in that at least one selected from glass fiber, carbon fiber, aramid fiber and polyethylene fiber.
(a) adding tannic acid and fiber reinforcement to molten plastic and mixing to obtain a plastic composite;
(b) molding the plastic composite into a desired shape; a method for producing a high-strength plastic composite with improved mechanical strength, comprising: a.
6. The method of claim 5,
In the step (a), the tannic acid is first mixed with the molten plastic, and then the fiber reinforcement is mixed thereafter.
6. The method of claim 5,
The molding temperature in step (b) is a method of manufacturing a high-strength plastic composite with improved mechanical strength, characterized in that it is maintained at about 20 to 30° C. lower than the melting temperature in step (a).

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