KR101865616B1 - Treatmenting method of natural fibers and composite comprising the same - Google Patents

Abstract

The present invention relates to a process for producing a modified natural fiber obtained by treating a natural fiber with a solution containing an oxidizing agent, a polymer composite composition containing the modified natural fiber, and a composite formed article made from the composition.

Description

TECHNICAL FIELD [0001] The present invention relates to a natural fiber treatment method and a composite material containing the same,

The present invention relates to a process for treating natural fibers, a polymer composite composition comprising the modified natural fibers obtained therefrom, and a composite material produced therefrom.

A polymer polymer used for automobiles and mechanical parts can not exhibit sufficient physical properties as such, thereby improving the physical properties of the polymer. By using an inorganic fiber or an inorganic material, a desired physical property can be achieved. Examples of such inorganic fibers or inorganic materials include carbon fibers, boron fibers, glass fibers, talc, mica, whiskers, etc., and a method of combining them with a polymer is used.

However, a method of manufacturing a composite material using an inorganic material has a problem that it is difficult to reduce the weight because of the high specific gravity of the inorganic material itself, and it is difficult to recycle it, thereby causing environmental pollution.

For example, in the production of automobile parts using polyolefin, polyolefins such as polypropylene and carbon fiber or glass fiber composite materials are used. However, in order to overcome limitations such as light weight of automobiles and improvement of fuel economy, Materials should be replaced.

One method to replace this is to use high strength synthetic fibers. However, when the above-mentioned synthetic fibers are used, they are not decomposable and cause environmental problems. Moreover, since the surface modification of the synthetic fibers is substantially difficult, compatibility between the synthetic fibers and the polymer matrix resin also becomes a problem, It is difficult to satisfy the physical properties of the conventional composite material.

Another method is to use natural fibers that are environmentally friendly and capable of exhibiting sufficient strength, but they still have the disadvantage of failing to satisfy the physical properties and have a problem that their compatibility with the matrix polymer resin is not very good. In addition, the composite material thus produced has a lower tensile strength and tensile elastic modulus than the composite material of an inorganic material and a polymer, and thus it is difficult to expect improvement of mechanical properties.

Therefore, studies have been made to increase the compatibility with natural fibers by pretreating them with polymers. For example, Korean Patent Publication No. 2010-0119018 discloses that lignocellulose biomass is pretreated with ammonia water at a high temperature (90 to 110 ° C), but the material used in the pretreatment process is expensive, The compatibility with the resin is increased and the mechanical properties such as tensile strength and flexural strength are limited.

Korean Patent Publication No. 2010-0119018 (2010.11.09.)

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a composite material excellent in compatibility with a high molecular polymer, Modified natural fibers obtained therefrom, a polymer composite composition prepared by using the modified natural fibers, and a composite formed body produced from the composition.

It is another object of the present invention to provide a polyolefin-based polymer composite composition obtained by compounding the modified natural fiber with polypropylene or the like.

Another object of the present invention is to provide a composite molded article produced using the polymer composite composition.

Therefore, the present invention can efficiently treat natural fibers, and can be applied to a variety of fields by replacing inorganic materials. Particularly, the present invention can dramatically improve the interfacial bonding force and dispersibility with the polymer matrix resin, A modified natural fiber obtained by the method, a polymer composite composition comprising the modified natural fiber, and a composite formed body produced from the composition.

According to an aspect of the present invention, there is provided a method for producing a modified natural fiber, which comprises preparing a modified natural fiber prepared from a modified oxidizing step of producing a chlorophyll by treating a chlorophyll with an oxidizing agent, a modified natural fiber, , A polymer composite composition containing the modified natural fibers, and a composite formed article (product) produced therefrom.

Another aspect of the present invention relates to a method for producing a silicone fiber, comprising the steps of: either an alkali treatment step of treating a natural fiber with an alkaline solution before treatment with an oxidizing agent, or a silane treatment step of surface treatment with a silicone polymer after the oxidizing agent treatment .

In the present invention, it is best in terms of physical properties to have both the alkaline treatment step of treating the natural fiber with an alkaline solution, the oxidative modification step and the silane treatment step of coating the surface with the silicone polymer.

The modified natural fiber according to the present invention is a modified natural fiber obtained by removing 50 to 95% of the content of lignin contained in the natural fiber before the treatment.

The natural fibers of the present invention are not particularly limited, and examples thereof include kenaf, jute, flex, hemp, ramie, sisal, sisal, pineapple, coir, kawan, cotton, dense, And may include at least one selected from the group consisting of gas, reed, corn, hardwood, conifer, and wood flour.

The polymer is not particularly limited as long as it is thermoplastic or thermosetting. Examples thereof include polyolefin polymers or copolymers such as polyethylene and polypropylene, polyester polymers, polyamides, acrylics, polyvinyl alcohols, And when it is combined with polyolefins such as polypropylene, the improvement of physical properties is particularly remarkable and the commercial demand is high, which is preferable.

In the present invention, the oxidizing agent used in the oxidative reforming step may be selected from the group consisting of hydrogen peroxide, sodium peroxide, sodium chlorate, sodium chlorite, sodium hypochlorite, hydrosulfide, sulfur dioxide, sodium bisulfite, potassium sulfite, sodium sulfite, And a peroxide group composed of an inorganic acid and a benzoyl peroxide, and any one or more selected from among hydrogen peroxide, sodium peroxide, sodium chlorate, sodium chlorite, and sodium hypochlorite may be more effective.

In the present invention, the alkali treatment step is not particularly limited and can be used as long as it is an alkali agent capable of imparting an alkali condition. The conditions for the alkali treatment are not particularly limited, but one example can be carried out under the conditions of 45 to 75 캜 and a pH of 7.7 to 12.

After the step of alkali treatment, it is sufficiently cleaned by washing or the like and then dried. It is not particularly necessary to adjust the drying temperature at the time of drying, but it is preferable to dry at 100 to 120 ° C, for example.

In the present invention, it is preferable that the natural fiber is pulverized, washed, and dried before the natural fiber is modified so that there is no impurity, and the modified fiber is smoothly softened. The pulverization can be carried out in various sizes, but pulverization with an average particle diameter of, for example, 50 to 2,000 mu m, preferably 100 to 1,000 mu m, more preferably 100 to 500 mu m, may shorten the time of the reforming reaction.

Further, another aspect of the present invention is to provide a polymer composite composition comprising the modified natural fibers.

Another aspect of the present invention is to provide a composite formed body produced using the polymer composite composition.

The modified natural fiber produced by the treatment method according to the present invention is compounded or compounded with a polymer such as polypropylene to have excellent compatibility with the polymer at the interface and increase the interfacial bonding strength with the polymer resin There is an advantage to be able to.

In addition, the polymeric resin composition containing the polymeric resin composition is not only lightweight and environmentally friendly, but also has excellent mechanical properties such as tensile strength and flexural strength, and is excellent in molding processability, workability and biodegradability, and can be applied to various fields.

Also, the natural fiber processing method according to the present invention is economical in that the process is simple and the process is performed at a low temperature condition that can save energy, so that the energy efficiency is excellent, the cost can be reduced, and the productivity can be improved .

Hereinafter, preferred embodiments of the modified natural fiber, the polymer composite composition containing the modified natural fiber, and the composite molded body produced from the modified natural fiber will be described in detail.

However, this is not intended to limit the scope of protection defined by the claims. In addition, technical terms and scientific terms used in the description of the present invention have the meanings as commonly understood by those of ordinary skill in the art to which the present invention belongs, unless otherwise defined.

The inventors of the present invention treated natural fibers with a specific chemical process to increase the crystallinity of the cellulose and at the same time reduce the inhibiting factors of the interfacial bonding strength. The modified natural fibers obtained through such modification can remarkably improve the mechanical properties such as tensile strength, flexural strength and dimensional stability of the fibers themselves compared with the natural fibers before modification.

Further, by compounding with a polymer matrix resin, the interfacial bonding force with the matrix resin can be increased to maximize the compatibility, and at the same time, the performance such as moldability and handleability can be realized.

In addition, it has been found that inorganic or inorganic fibers can be substituted in various fields, and at the same time, light weight is achieved, which is excellent in economy, and the present invention has been completed.

Hereinafter, the present invention will be described in detail.

In order to accomplish the above object, one aspect of the present invention is to provide a method for producing a modified natural fiber produced from an oxidative modification step of treating a chlorophyll with an oxidizing agent, a modified natural fiber, a polymer composite composition containing the modified natural fiber, And a composite molding (article) produced from the composite molding.

Another aspect of the present invention is a method for producing a silicon carbide thin film, which comprises either one of the steps selected from the alkali treatment step of treating with the alkaline solution before the oxidative modification step or the silane treatment step of surface treatment with the silicon based polymer after the oxidative modification step do.

In the present invention, it is best in terms of physical properties to have both the alkali treatment step of alkaline treatment of natural fibers, the oxidative modification step and the silane treatment step of coating the surface with the silicone polymer.

The modified natural fiber according to the present invention is a modified natural fiber obtained by removing 50 to 95% of the content of lignin contained in natural fibers before treatment.

The natural fiber of the present invention means a cellulosic biomass, and biomass containing cellulose can be used without being limited to a large extent. Specific examples include bast fibers such as kneaf, jute, flex, hemp, ramie, and the like, with leaf fibers, sisal, henequen and pineapple. Fruit / seed fibers include coir, kapok, cotton and the like. stalk fibers include wheat straw, rice straw, and oat. The grass fibers include bagasse, reed, corn, Wood fibers such as hardwood, softwood, and wood flour. It is more preferable to use natural fibers having a high content of cellulose.

In the present invention, the polymer (polymer) is not particularly limited, such as thermoplastic or thermosetting property. For example, polyolefin polymer or copolymer such as polyethylene and polypropylene, polyester polymer, polyamide, acrylic, polyvinyl alcohol, A polyurethane system and the like, and when it is combined with a polyolefin system such as polypropylene, improvement of physical properties is remarkable and commercial preference is preferable.

In the present invention, the oxidative modification step of the natural fiber with the oxidizing agent is carried out by immersing the natural fiber in a solution containing an oxidizing agent, for example, an aqueous solution. In the oxidation reforming step of the present invention, it is possible to remove a certain amount of components such as pectin and wax contained in the natural fiber by an oxidizing agent, and to remove a certain amount of the lignin component. Accordingly, not only the crystallinity of the natural fiber is enhanced but also the color is further brighter and the quality of the natural fiber is improved. Therefore, the coloring can be facilitated while increasing the mechanical strength of the natural fiber.

In the present invention, it is particularly preferable to remove 50 to 95% by weight, preferably 55 to 90% by weight, of the delignification rate, And the lignin is reduced as the mechanical properties are increased.

Specific examples of the oxidizing agent include inorganic chlorine, organic chlorine, inorganic oxide, organic peroxide and the like. Specific examples thereof include hydrogen peroxide, sodium peroxide, sodium chlorite, sodium hypochlorite, hydrosulfide, sulfur dioxide, sodium bisulfite, Potassium sulfite, sodium sulfite and benzoyl peroxide, acetic acid, propionic acid, butyric acid and hydrofluoric acid.

In the present invention, a surfactant may be further added to the oxidizing agent.

The surfactant used is not particularly limited, but it is better to use a nonionic surfactant. Examples of the nonionic surfactant include polyoxyethylene alkyl ethers, fatty acid alkanolamines, amine oxides, phosphine oxides, alkyl polyglucosides ), Methyl polyethylene alkyl ether, sugar ether, glycerin ester, sorbitan ester, propylene glycol ester, sugar ester, fatty acid alkanolamide, polyoxyethylene fatty acid amide, polyoxyethylene alkylamine , Amine oxides and the like, and ether-based nonionic surfactants are more preferable, but are not limited thereto. When the nonionic surfactant is used, the content in the oxidizing agent solution is not limited to a great extent, but it is preferably 0.01 to 1% by weight from the viewpoint of economy and the like.

In the present invention, the oxidative modification step is not particularly limited as long as it oxidizes the natural fiber by immersing it in the oxidizing agent solution for several hours. Of course, it is not necessary to stir in a state of being immersed, but the meaning of the stirring may be used to mean that the immersed state is not stirred.

As a specific example of the oxidation reforming step, natural fibers are put into an aqueous 15% hypochlorous acid solution at about 100 to 150 g / l, and the mixture is immersed and stirred for dechlorination, acidic substances such as acetic acid are added to the acidic atmosphere , And drying in a drying oven at 100 to 120 캜 for 1 hour to 3 hours.

The alkali treatment step which is a treatment step of another embodiment of the natural fiber modification method according to the present invention will be described. That is, in the present invention, the modified natural fiber having better physical properties can be produced by first performing the alkali treatment step of alkali treatment of the natural fiber before the oxidative modification step.

The alkali treatment method relates to a step of mixing natural fibers with an alkaline solution and immersing them in an alkali solution for treatment.

The step of alkali treatment may be carried out by adding natural fibers to an aqueous alkaline solution, for example an alkaline metal hydroxide or an alkaline earth metal hydroxide, for example, an aqueous solution of sodium hydroxide solution at a concentration of 8 to 20% Deg.] C to 75 [deg.] C and a pH of 7.7 to 12. [ The high-speed immersion agitation can be carried out, for example, by stirring at a speed of 1,000 to 1,500 rpm using an impeller (diameter: 16 cm) in a rotary drum type stirrer.

At this time, unlike the conventional cellulose extraction method in which the above conditions are satisfied and the reaction is performed at a high temperature of 160 ° C using a high concentration of an alkali solution, the process of alkali treatment can prevent the loss of cellulose and, at the same time, And energy consumption can be lowered efficiently, which is economically advantageous. In addition, according to the present process, the lignin component and the like are partially removed, thereby further increasing the purity of the cellulose. The temperature range is preferably 50 to 70 ° C. However, the present invention is not limited thereto.

The alkaline solution may be selected from a hydroxide of an alkali metal or a hydroxide of an alkaline earth metal, though not particularly limited. For example, sodium hydroxide, potassium hydroxide, magnesium hydroxide, lithium hydroxide, beryllium hydroxide, Or in combination. Preferably, sodium hydroxide is better in terms of pH control and concentration control.

In addition, the alkaline solution may include a metal salt. Examples of the metal salt include a halide, a sulfide, and a nitride of at least one metal selected from the group consisting of an alkali metal, an alkaline earth metal, a transition metal, and a combination thereof. The metal salt may be added so that an alkaline solution having a low concentration can serve as a high alkaline solution. This is because the metal salt functions as a Lewis acid and is easy to dissolve even at a low concentration due to interaction with a large amount of carbonyl groups contained in lignin, which is better in terms of lignin removal efficiency. Moreover, metal salts make it easier to separate lignin.

The concentration of the alkaline solution is not limited, but is preferably 1 to 40%, more preferably 5 to 20%. Within the above range, the mechanical properties of the natural fibers can be better secured while maintaining the yield and purity of the cellulose.

After the alkali treatment, the natural fiber may be washed to remove remaining impurities, and then dried. The washing and drying are not particularly limited. At this time, it is possible to carry out the step of immersing and stirring the caustic soda or the sodium carbonate before the washing at a concentration of 3 to 8% of the aqueous solution. This is because the degradation performance can be further improved by decomposing sugars such as monosaccharides, disaccharides and polysaccharides remaining after alkali treatment.

The step of alkali treatment in the present invention may further include carrying out a pulverization step before the alkali treatment step. Preferably, the average particle size of the natural fibers through the pulverizing process is 50 to 2,000 mu m, preferably 100 to 1,000 mu m, more preferably 100 to 500 mu m, in view of moldability, ease of modification, workability and mechanical properties It is better in terms of securing it.

Another embodiment of the natural fiber treatment method according to the present invention may further include a silane treatment step in which the natural fiber is mixed with the silicone polymer and subjected to the silane treatment after the oxidative modification step.

In particular, when the natural fiber after the oxidative modification step is complexed with the hydrophobic polymer resin, the interfacial bonding strength with the natural fiber is maximized to increase the compatibility, weaken the hydrogen bonding force inside the fibers, And may be performed by immersing and stirring the mixture using a silane compound or polymer in order to improve hygroscopicity.

The silane treatment step is preferably silane treatment with a siloxane-based compound such as polydialkylsiloxane.

At this time, the silane compound preferably has a concentration of 2 to 10%, preferably 3 to 9%, but is not limited thereto.

In addition, the process of modifying the natural fibers may further include a separation process such as various filtration, centrifugation, precipitation, recrystallization, etc., and may be carried out using a high-speed homogenizer or ultrasonic treatment have.

The present invention provides a composite material comprising the modified natural fibers produced by the above-mentioned modified natural fiber manufacturing method.

The composite material is made of a composition comprising a modified natural fiber having a lignin content reduction rate of 50 to 95% by weight, preferably 55 to 90% by weight, and a polymer matrix resin by a modified natural fiber production method.

In the present invention, the polymer composite composition may be used with various polymers, but particularly when it is combined with a polyolefin-based polymer resin, the market demand is much better.

Here, the polyolefin-based polymer resin is not particularly limited as long as it includes a polyolefin and a copolymer thereof, and examples thereof include an ethylene homopolymer, a propylene homopolymer, an ethylene-butene copolymer, and an ethylene-methacrylate copolymer , But are not necessarily limited thereto.

Further, the present invention provides a thermoplastic resin composition comprising the above-mentioned composite material.

Further, the present invention provides a molded article produced by including the above-mentioned thermoplastic resin composition. The molded article can be applied to various industrial fields such as automobiles, ships, airplanes, sports, leisure, aerospace, etc., and can maximize efficiency due to lightweight as well as advantages such as excellent mechanical property, dimensional stability and molding processability.

In the present invention, the polymer composite composition may contain 2 to 50 parts by weight, preferably 5 to 30 parts by weight, of modified natural fibers per 100 parts by weight of the polymer resin.

The polymer composite composition of the present invention may contain additives other than the above-mentioned main components, such as fillers, UV absorbers, flame retardants, thickeners, lubricants, antioxidants, compatibilizers and the like that are commonly added in the art.

Hereinafter, the present invention will be described in more detail with reference to the following examples. It is to be understood that the following examples do not limit the embodiments of the present invention.

[Example 1]

(Woody softwood) pulverized at 200 micrometers was immersed in an aqueous solution of sodium hydroxide at a concentration of 15% by weight at 60 DEG C and the mixture was stirred for 2 hours at a high speed immersion stirring (using an impeller (diameter 16 cm) in a rotary drum type stirrer And the mixture was stirred at a speed of 1,300 rpm). Then, the alkali-treated wood powder was sufficiently washed with water and then dried at 110 ° C.

Next, the alkali-treated and dried wood powder was immersed in an aqueous 15 wt% sodium chlorite solution at 80 ° C for 40 minutes and then dried at 110 ° C. Thereafter, the pH of the aqueous solution was adjusted to 3.5 using acetic acid, the remaining pectin or wax component was removed, and the solution was immersed in deicyl glucoside and water for 1 hour and then thoroughly dried at 110 ° C. At this time, 4 moles of decyl glucoside was used based on water.

As a result of analyzing the components of the treated natural wood powder, cellulose was increased from 44.0 wt% to 48.5 wt%, and hemicellulose increased from 33.6 wt% to 45.0 wt%, as shown in Table 1 below, Respectively. Also, the content of lignin was reduced from 12.0 wt% to 5.5 wt%, and 0.9 wt% of pectin and 0.9 wt% of wax were completely removed and the remaining water was removed to 1.0% level.

[Table 1] Changes in natural wood powder before and after oxidative reforming

Next, the modified wood powder after the oxidative reforming step was immersed in silane (SA6112C, manufactured by KCC) at a concentration of 1.1 wt% for 10 minutes and agitated thoroughly at 100 DEG C to prepare final modified wood fiber.

(Melt index (230 占 폚 / 2.16 kg): 30 g / 10 min) of SK Company and CB 5290 (milk index (230 占 폚 / 2.16 kg): 100 g / 10 min). 8 wt% of talc (2000 mesh), 0.4 wt% of antioxidant (BASF, Iganox), 8 wt% of polypropylene grafted with maleic anhydride as a compatibilizer (Lotte Chemicals, PH-200) , 0.4 wt% of antistatic agent (Kamco Precision Co., ES1000) and 0.7 wt% of antistatic agent (Tinuvin), 0.4 wt% of anti-scratch agent (Kamco Precision Co., ER840) Respectively. The results are shown in Table 3 below.

[Example 2]

Example 1 was carried out in the same manner as in Example 1, except that the alkali treatment and the silane treatment were not carried out.

As a result, as shown in Table 2, in the modified natural fibers prepared, the cellulose increased from 44.0 wt% to 56.0 wt% in the wood powder before the pretreatment, and the hemicelluloses increased from 33.6 wt% to 38.0 wt% And it was found that cellulose of high purity was formed. In addition, the content of lignin was reduced from 12.0 wt.% To 6.0 wt.%, Pectin and wax were completely removed, and the remaining moisture was also removed.

[Table 2] Changes in natural wood powder before and after the oxidative reforming step

[Comparative Example 1]

The same physical properties as in Example 1 were used, except that the same natural fibers as in Example 1 were used, but no modified fiber was used. The results are shown in Table 3 below.

[Example 3]

Except that the silane treatment step in Example 1 was not carried out.

[Table 3] Comparison of physical properties of composite molding

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Various modifications and variations are possible in light of the above teachings.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (12)

Polyolefin-based resins and
A particle size of 50 to 2,000 탆 and a particle size of from 50 to 2,000 탆 and a particle size of from 5 to 20 μm and a particle size of from 5 to 10 μm, , A softwood material, and a wood powder.
Wherein the modified natural fiber powder is oxidatively modified after alkali treatment.
The method according to claim 1,
Wherein the modified natural fiber powder has a reduction ratio of the lignin content of 50 to 95% with respect to the lignin content of the natural fiber powder before the treatment, and does not contain a pectin component.
delete delete The method according to claim 1,
Wherein the polyolefin-based resin comprises polypropylene or a copolymer thereof.
A particle size of 50 to 2,000 탆 and a particle size of from 50 to 2,000 탆 and a particle size of from 5 to 20 μm and a particle size of from 5 to 10 μm, , A softwood material and wood powder, with an alkaline solution to alkali treatment, and
An oxidation reforming step of treating the alkaline-treated natural fiber powder with a solution containing an oxidizing agent
≪ / RTI >
delete The method according to claim 6,
Further comprising a silane treatment step of coating with the silane compound after the oxidative modification step.
delete delete The method according to claim 6,
The oxidizing agent is selected from the group consisting of hydrogen peroxide, sodium peroxide, sodium chlorate, sodium chlorite and sodium hypochlorite, hydrosulfide, sulfur dioxide, sodium bisulfite, potassium sulfite and sodium sulfite. Organic peroxides, and organic acids or inorganic acids.
A composite formed article produced from the polymer composite composition of any one of claims 1, 2, and 5.