KR20170081117A - Manufacturing method for Fiber reinforced Composite sheet and The Fiber reinforced Composite sheet - Google Patents

Abstract

The present invention relates to (S1) a fiber supplying step of supplying fibers on a bundle or a fabric; (S2) immersing the supplied fibers in a polyamide slurry in which spherical polyamide resin fine particles and a dispersant are dispersed in water, followed by drying; And (S3) heating and fusing the dried fiber to impregnate the fiber with the polyamide resin. The present invention relates to a method for producing a fiber-reinforced composite sheet, will be.

Description

TECHNICAL FIELD [0001] The present invention relates to a fiber reinforced composite sheet and a fiber reinforced composite sheet,

The present invention relates to a method for producing a fiber-reinforced composite sheet and to the fiber-reinforced composite sheet.

Compostie means a material that artificially blends or combines materials with different ingredients and properties to maximize the properties of each material or to have new properties that are not expressed in a single material. Composite materials are basically excellent in properties such as strength, corrosion resistance, fatigue life, abrasion resistance, impact resistance, light weight and electrical insulation compared to conventional materials. Therefore, they are used in aerospace sector, sporting goods, ships, construction, It is a representative 21st century industrial material that has been attracting attention in various fields ranging from to.

The composite material is generally made of a reinforced material that is responsible for the load applied to the material, and a matrix that transmits the load to the reinforcement in combination with the reinforcement. The reinforcing material is usually glass fiber, carbon fiber, aramid Fiber reinforced materials such as fibers are widely used. As the base material, a thermosetting resin including phenol resin, epoxy resin, etc., or a thermoplastic resin including polyvinyl chloride (PVC), polyethylene, .

Among them, thermosetting resin composite materials which can not be reprocessed once hardened according to the thermal properties of the matrix polymer resin are difficult to be formed in spite of excellent mechanical strength and physical properties, are disadvantageous to mass production, and are expensive, The thermoplastic resin composite material which is mainly used in the leisure field and which can be repeatedly thermoformed is advantageous in mass production and reusable.

Polyamide 6 resin among thermoplastic resin composites has acid-amide bond (-CONH-) as a main chain and is excellent in impact resistance, abrasion resistance, chemical resistance, oil resistance, and also excellent in heat resistance among engineering plastics. It is also widely used in parts. It is mainly used for engine covers around engines, radiator tanks and so on.

The method for producing a thermoplastic resin composite material using such a thermoplastic resin is produced by various methods such as a melting method (hot melt method), a solvent method, a resin film impregnation method, a powder method, etc. according to a resin impregnation method.

Among them, the melting method is a method of melting a thermoplastic resin in an extruder and passing continuous fibers through a molten bath to impregnate the resin with the resin. The advantage of this method is that it has less facility investment, low energy consumption, and no environmental problems, but the higher the molecular weight and the higher the melt viscosity, the higher the heat resistance and the higher the mechanical strength of the polymer resin. do. As a result, bubbles are intrinsically incorporated between the resins to lower the physical properties of the composite material, and it is very difficult to produce a smooth surface, and only a thermoplastic resin having a low melt viscosity can be used.

In addition, the solvent method is a method in which a high-quality prepreg can be obtained by impregnating reinforcing fibers into a solution in which a resin (mainly amorphous resin) is dissolved in a solvent, and a prepreg having a wide width can be obtained. However, There is a problem that environmental problems and solvent removal and recovery are difficult.

In the resin film impregnation method, the resin film and the reinforcing fiber are melt-impregnated with a resin by a double belt press. The advantage of this method is that it is possible to obtain a prepreg with smooth surface, but it is very difficult to press uniformly over the entire width by the double belt method, so it is difficult to manufacture a wide or thin product having a width exceeding 1 m. In addition, since the available resin is limited and an expensive press apparatus is required, there is a disadvantage that the cost is high.

On the other hand, powder scattering is a method of attaching powdered resin to reinforcing fibers to melt impregnate the powder heated in the next step, and there are mainly dry powder coating method and powder suspension method. The dry powder coating method is a method in which the dried powder is electrostatically charged or dispersed in a fluidized bed to be attached to the reinforcing fiber, and then heated in an oven to melt and impregnate the powder. The powder suspension method is a method in which a powder is adhered to a reinforcing fiber in a bath in which resin powder is uniformly dispersed in water or a solvent (acetone or ethanol), and then the powder is melted and impregnated by heating. As described above, when a composite material is produced using a powdered resin, the impregnation property and impregnation content of the resin with respect to the fiber are poor, and the mechanical properties of the final product are low.

In particular, the lack of impregnation uniformity of the resin and thus the non-impregnated interfiber air retention can act as a cause of defects in the mechanical properties of the final product, and this effect is more pronounced as the number of supplied fibers increases and the final product becomes larger and larger It becomes remarkable. Accordingly, when the resin is impregnated with the resin, it is important that the resin is uniformly dispersed so as to permeate all portions of the fiber and uniform impregnation to the inside of the fiber.

Accordingly, the present invention provides a method for producing a fiber-reinforced composite sheet capable of uniformly dispersing a polyamide resin powder, that is, fine particles, into a fiber and having a high resin impregnation property and a high impregnation content and a low porosity, .

A method for manufacturing a fiber-reinforced composite material sheet according to the present invention comprises the steps of: (S1) supplying a fiber bundle or a fabric on a knit fabric; (S2) immersing the supplied fibers in a polyamide slurry in which polyamide resin fine particles and a dispersant are dispersed in water, followed by drying; And (S3) heating and melting the dried fiber to impregnate the fiber with the polyamide resin.

In this case, the polyamide resin fine particles in the step (S2) are substantially spherical particles having a circularity (R) of 0.9 to 1.0 as defined by the following formula 1, and the average particle diameter is 5 to 20 탆, (CV) of 25 to 40%.

<Formula 1>

Roundness R = 4 S _meas / π D _max ²

Where S _meas is the actual cross-sectional area of the particle, and D _max is the maximum diameter of the particle.

<Formula 2>

Particle size distribution (%) = (standard deviation of particle diameter / average diameter of particles) x 100

The fiber may be glass fiber (GF), carbon fiber (CF), or aramid fiber (AF).

If the fibers supplied in step (S1) are bundle fibers, the method of producing a fiber-reinforced composite material sheet of the present invention is characterized in that the fed bundle fibers are stretched in the width direction (S1-a), which is 3 to 10 times as large as the number of openings.

In this case, the fiber opening step (S1-a) may be a first opening step of preheating the supplied bundle-shaped fibers at a temperature of 150 to 200 DEG C and an air pressure of 0.3 to 0.7 MPa; A second opening step of causing the primary opened fibers to vibrate at a vertical amplitude of 5 to 15 mm per second at a temperature of 150 to 200 DEG C and an air pressure of 0.5 to 1 MPa; And a third opening step in which the second opened fiber is further vibrated at a temperature of 160 to 220 DEG C and a vertical amplitude of 5 to 15 mm per second under an air pressure of 0.8 to 1.5 MPa.

The present invention also provides a fiber-reinforced composite sheet comprising a polyamide resin and fibers impregnated in the polyamide resin, and having a porosity (V) of 2% or less as defined by the following formula do.

<Formula 3>

V (porosity: volume%) = (Td-Md) / Td

Td (theoretical composite density) = 100 / (R / D + r / d)

R = Resin weight%, r = Reinforcement weight%,

D = Density of resin, d = Density of reinforcement,

Md = measured composite density.

INDUSTRIAL APPLICABILITY According to the present invention, the polyamide resin fine particles can uniformly penetrate the fibers to improve the impregnating property and the impregnation content of the resin, thereby making it possible to produce a fiber-reinforced composite sheet having a very low porosity.

1 is a photograph of the morphology of the spherical polyamide fine particles of the present invention taken by an electron microscope
Fig. 2 is a photograph of a particle shape of a conventional non-spherical polyamide fine particle (ORGASOL (R) PA6 manufactured by Akema) by an electron microscope.
3 is a schematic diagram showing a criterion for evaluating roundness of particles according to the present invention.
4 is a schematic view showing a process for producing a fiber-reinforced thermoplastic composite sheet using bundled fibers according to an embodiment of the present invention.
5 is a schematic diagram showing a process for producing a fiber-reinforced thermoplastic composite sheet using fibers on a knitted fabric in accordance with an embodiment of the present invention.

The inventors of the present invention have found that the ultimate physical properties of a fiber-reinforced composite sheet can be improved by using fiber-reinforced polyamide resin fine particles in a resin-impregnated fiber, thereby completing the present invention.

More specifically, the method for producing a fiber-reinforced composite sheet of the present invention comprises: (S1) a fiber supplying step of supplying fiber on a bundle or a knitted fabric; (S2) immersing the supplied fibers in a polyamide slurry in which polyamide resin fine particles and a dispersant are dispersed in water, followed by drying; And (S3) heating and melting the dried fiber to impregnate the polyamide resin with the fiber.

Particularly, in the step (S2) of the present invention, the polyamide resin fine particles are preferably spherical particles having a roundness (R) of 0.9 to 1.0 as defined by the following formula (1) for improving the final physical properties of the fiber-reinforced composite sheet.

<Formula 1>

Roundness R = 4 S _meas / π D _max ²

Where S _meas is the actual cross-sectional area of the particle, and D _max is the maximum diameter of the particle.

The term &quot; spherical particles &quot; in the present invention means particles close to a spherical phase in which the surface is smooth and the distance from the center of the sphere to the surface is almost constant as shown in FIG. 1, It may be a concept that contrasts with an &quot; non-image &quot; in which irregular irregularities are formed on the surface or an elongated shape such as a rugby ball and does not satisfy the roundness. At this time, the concept of roundness can be more clearly understood through FIG.

That is, when the spherical polyamide resin particles are used as shown in FIG. 1, the flowability of the fine particles is better than that of the non-spherical polyamide resin particles shown in FIG. 2, It can be uniformly filled. As a result, when the spherical polyamide resin fine particles are used, the impregnation of the resin becomes high, and the physical properties of the final composite material can be improved.

Further, the polyamide resin fine particles of the present invention preferably have a particle average diameter (d50: median diameter (median diameter) of 50% of the cumulative value of particle distribution, described in ISO 9276-2: 2001) It is preferable that the particle size distribution (CV) defined by 2 is 25 to 40%.

<Formula 2>

Particle size distribution (%) = (standard deviation of particle diameter / average diameter of particles) x 100

If the average diameter of the polyamide resin particles is less than 5 mu m, the particles may be too fine to disperse the particles and the dispersant in water, or it may be difficult to control the flowability of the particles. Mu m, the space between the fibers may not be completely filled.

Further, it is preferable that the particle size distribution (C.V.) is 25 to 40% from the viewpoint that small particles are closely packed between large particles and can be uniformly impregnated into the fibers. If the particle size distribution of the polyamide resin particles is less than 25%, it may be difficult to uniformly disperse the fibers between the fibers because there are many particles having similar sizes. If the particle size distribution is more than 40%, particles with excessively small sizes and large particles are stretched The resin flowability and the rate of impregnation of the resin between fibers may be reduced.

The spherical polyamide resin fine particles of the present invention may be prepared by adding a lactam having 6 to 8 carbon atoms or an amicarboxylic acid monomer having 6 to 8 carbon atoms as a dispersed phase together with an inert solvent having a viscosity of 0.1 to 10 mPa · sec, Heating the mixture to 100 to 180 ° C, stirring the mixture, raising the temperature further to 215 ° C to 260 ° C, adding a polymerization initiator, and polymerizing the mixture for 4 hours to 6 hours.

The lactam having 6 to 8 carbon atoms is specifically caprolactam, heptaram and octaractam, and the aminocarboxylic acid having 6 to 8 carbon atoms is specifically 6-aminocaproic acid, methyl 6-aminocaproate, ethyl 6- Amino (N, N-dimethyl) caproamide, 6-amino (N-ethyl) caproamide, and 6-aminocaproamide.

Above all, when the polymerization is carried out in an inert solvent having a viscosity of 0.1 to 10 mPa · sec, it is easy to prepare as spherical spherical particles. In this case, the inert solvent plays a role of preventing aggregation between the fine particles without participating in the reaction at the time of the polyamide polymerization reaction, and can be very easy to manufacture spherical particles. At this time, if the viscosity of the inert solvent is too low, aggregation of the particles may occur. If the viscosity of the inert solvent is excessively high, it may be difficult to manufacture the particles in a spherical shape, and size control may be difficult.

Useful inert solvents include aliphatic hydrocarbons including n-hexane, isohexane, t-octane, petroleum ether and kerosene; Aromatic hydrocarbons including benzene, toluene and xylene; And at least one selected from halogenated hydrocarbons including chloroform, dichloromethane and chloromethane.

The lactam having 6 to 8 carbon atoms or the aminocarboxylic acid monomer having 6 to 8 carbon atoms is preferably added in an amount of 30 to 50 parts by weight based on 100 parts by weight of the inert solvent. When the content of the lactam or aminocarboxylic acid monomer is 100 When the amount is less than 30 parts by weight, the particle diameter after the polyamide polymerization reaction is less than 5 占 퐉, which is not preferable. When the amount exceeds 50 parts by weight, the particle diameter increases to 20 占 퐉 or more and it is difficult to appropriately control the average diameter and particle size distribution.

The basic catalyst used in the fine particle production method is added as a catalyst for the condensation polymerization together with the hydrolysis of the nitrile group, and is preferably added in an amount of 0.1 to 1.0 part by weight based on 100 parts by weight of the inert solvent. When the content of the basic catalyst is excessively less than the above range, it is difficult to efficiently produce fine particles because the rate of the condensation polymerization is low and the yield is low, which is undesirable. When the amount of the basic catalyst is excessively increased, It is difficult to generate fine particles and an irregular gel is produced, which may not be appropriate.

The basic catalyst may be an alkali metal hydroxide including potassium hydroxide, sodium hydroxide, and lithium hydroxide; Alkaline earth metal hydroxides including calcium hydroxide and barium hydroxide; Alkali metal carbonates including potassium carbonate and sodium carbonate; And at least one member selected from the group consisting of monomethylamine, dimethylamine, monoethylamine, diethylamine, ethylenediamine and amines including ammonia.

The dispersant is added in order to lower the interfacial free energy between phase-separated phases to control the average particle diameter and facilitate the control of the particle diameter of the domain and the inter-domain distance in the dispersion structure. Potassium, sodium stearate, and sodium laurate. It is preferable that the fatty acid salt is at least one selected from the group consisting of potassium, sodium stearate and sodium laurate.

At this time, the dispersant is preferably added in an amount of 0.1 to 2.0 parts by weight based on 100 parts by weight of the inert solvent. If the content of the dispersant is excessively less than the above range, it may be difficult to control the average diameter and the particle size distribution when the polyamide particles are excessively added.

Further, the polymerization initiator is added in order to initiate the polyamide polymerization reaction, and it is preferable to use a phosphorus polymerization initiator such as phosphorus trichloride. The polymerization initiator is preferably added in an amount of 0.1 to 1.0 part by weight based on 100 parts by weight of the inert solvent. If the content of the polymerization initiator is out of the above range, if too little is added, the polyamide polymerization reaction will not proceed, The size of the particles may be rather small because the reaction sites are often formed.

The prepared precursor polyamide resin fine particles of the present invention may have a weight average molecular weight measured by GPC (Gel Permeation Chromatography) of 500,000 to 5,000,000 and a melting point of 210 to 230 ° C, It is not.

Meanwhile, in the method for manufacturing a fiber-reinforced composite material sheet of the present invention, in order to further increase the resin impregnation rate, when the fiber supplied in the step (S1) is a bundle of fibers, And a fiber opening step (S1-a) of opening the fed bundle fibers three to ten times in the width direction.

If the opening is less than 3 times in the width direction, filaments of the filaments do not uniformly spread and the filaments overlap, so that the resin fine particles are difficult to locate between the filament filaments. In this case, the impregnation property may be lowered when the resin is melted, and the width of the fiber is narrow, so that the produced sheet is thick, but the resin can not penetrate deeply and the physical properties may be significantly deteriorated. On the other hand, if it exceeds 10 times, the filaments of the filament are excessively unfolded, so that the filament tends to be poured in a specific direction, which may cause irregular spacing between the filament and the filament.

Herein, the term &quot; spreading &quot; means that the bundle is unfolded, meaning that a plurality of filaments are bundled in a bundle shape and are unwound widely in the width direction. This can also be described as spreading throughout the specification, the opening step can also be described as a spreading process, and the carding device can be described as a spreader.

In the present invention, the fiber opening step (S1-a) includes a first opening step of preheating the supplied bundled fibers at a temperature of 150 to 200 DEG C and an air pressure of 0.3 to 0.7 MPa; A second opening step of causing the primary opened fibers to vibrate at a vertical amplitude of 5 to 15 mm per second at a temperature of 150 to 200 DEG C and an air pressure of 0.5 to 1 MPa; And a third opening step in which the second opened fiber is further vibrated at a temperature of 160 to 220 DEG C and a vertical amplitude of 5 to 15 mm per second under an air pressure of 0.8 to 1.5 MPa.

More specifically, if the preheating temperature is lower than 150 ° C in the primary carding step, it may not be easy to spread the bundle-type fiber yarn widely. If the temperature exceeds 200 ° C, damage to the surface treatment agent on the bundle- And it is preferable that the air pressure is 0.3 to 0.7 MPa so that the bundle-type fiber yarn can be widely spread.

In addition, the secondary and tertiary opening stages imparting vibration are divided into two stages in order not to apply a high temperature and pressure to the fiber rapidly, and when the temperature and the pressure range do not satisfy the above conditions, It is not easy to uniformly spread the fiber yarns in a line or damage of the surface treatment agent on the fiber surface may occur.

In this case, in the secondary and tertiary opening stages, vibration can be imparted to the fibers at a vertical amplitude of 5 to 15 mm per second. When the vertical amplitude is less than 5 mm, the width of the opened fibers can be narrowed and thickened, The width of the opened fibers becomes too wide, and the space between the fibers may be widened, resulting in a void space. The vibration application may be controlled through operation temperature and air flow rate, but is not limited thereto.

In the present invention, the fiber yarn is preferably glass fiber (GF), carbon fiber (CF), or aramid fiber (AF) for the impregnation temperature and physical properties. However, It is not.

When the production method of the present invention is applied, since a large amount of polyamide resin particles can be uniformly distributed between the fibers and thus impregnation can be performed well, the porosity of the produced fiber-reinforced composite sheet is drastically reduced . Accordingly, the present invention provides a fiber-reinforced composite sheet having a polyamide resin and a fiber yarn impregnated in the polyamide resin and having a porosity (V) of 2% or less as defined by Formula (3).

<Formula 3>

V (porosity%) = (Td-Md) / Td

Td (theoretical composite density) = 100 / (R / D + r / d)

R = Resin weight%, r = Reinforcement weight%,

D = Density of resin, d = Density of reinforcement,

Md = measured composite density.

That is, since the porosity of the fiber composite material sheet can be adjusted to 2% or less, the influence of the pores existing in the interior of the final composite material sheet adversely affecting the physical properties of the composite material sheet is lowered, It is possible to maximize improvement in mechanical properties such as bending strength and impact strength.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for the purpose of illustrating the present invention more specifically, and the present invention is not limited thereto.

< Manufacturing example >

After adding 200 g of n-hexane (H1303, P3), 2 g of caprolactam (CAPRO), potassium hydroxide (93%, DC chemical) and 2 g of stearate were added to a 500 ml four-necked flask equipped with a thermometer, a stirrer and a nitrogen gas inlet. 5.5 g of potassium potassium (OPK-1000, HallStar) was added and stirred while heating to 170 캜. 2 g of phosphorus trichloride (purity: 98%, Toki Chemical) was added at the time when the temperature of the solution reached 240 캜 (the melting point of the polyamide resin) while raising the temperature, and polymerization was carried out for 4 hours.

After completion of the polymerization, the reaction solution was cooled to room temperature, and the reaction product was passed through a 200-mesh wire mesh. The reaction product was washed several times with water to remove the catalyst and reaction by-products, thereby obtaining a cake-like powder. This was dried in a hot air circulating drier at 105 DEG C for 4 hours to finally prepare fine particle polyamide resin particles.

< Manufacturing example  2 to 4>

The polyamide resin fine particles were prepared in the same manner as in Example 1 except that the kind and content of the solvent were changed as shown in Table 1 below. At this time, Exxsol (TM) from ExxonMobil was used as the isohexane.

<Comparison Manufacturing example  1 to 2>

Polyamide resin fine particles were prepared in the same manner as in Example 1 except that liquid paraffin (PARACOS, Sejun Chemical Co., Ltd.) and isoparaffin (Soltrol (R) 130, Chevron Phillips) were used as a solvent.

< Measurement example  1>

The standard deviation of the maximum diameter, average diameter and diameter of the particles was measured using a particle size distribution analyzer (Multisizer 3, manufactured by Coulter Electronics Co., Ltd.) for the polyamide resin fine particles prepared in the above Production Examples and Comparative Production Examples. The particle size distribution (coefficient of variation, CV value) was obtained by the following formulas 1 and 2, respectively. The analytical results of the polyamide resin fine particles are shown in Table 1 below.

<Equation 1> Roundness R = 4 S _meas / π D _max ² (S _meas : actual cross-sectional area of particle, D _max : maximum diameter of particle)

 &Lt; EMI ID = 2.0 > Value (%) = (standard deviation of particle diameter / average diameter of particles) x 100

division
(Content: g) Manufacturing example Comparative Manufacturing Example One 2 3 4 One 2 Disperse phase Caprolactam 120 120 120 120 120 120 menstruum n-hexane 200 150 - 350 - - Isohexane 150 200 350 - - - Liquid paraffin - - - - 350 - Isoparaffin - - - - - 350 catalyst Potassium hydroxide 2 2 2 2 2 2 Dispersant Potassium stearate 5.5 5.5 5.5 5.5 5.5 5.5 Initiator Phosphorus trichloride 2 2 2 2 2 2 Particulate
Analysis Roundness 0.98 0.94 0.92 0.96 0.75 0.81 Average diameter
(탆) 10.2 20.5 24.2 16.0 30.5 42.0 CV value
(%) 36.8 34.2 47.6 33.9 20.5 18.0 shape Genesis Genesis Genesis Genesis Unoccupied Unoccupied

Example  One

Using the equipment of FIG. 4, the polyamide resin fine particles and the dispersing agent (DISPERBYK-2060, manufactured by Nisshin Chemical Industry Co., Ltd.) of the preparation example 1 were mixed while controlling the glass fiber (101, Owens Corning SE4121-2400TEX) surface-treated with a silane- BYK-Chemie GmbH) was continuously passed through a dispersed slurry tank and the fibers were immersed in a resin slurry. Thereafter, water is evaporated using the drying chamber 105, and then the resin is melted and cemented in a preheating chamber (at a temperature of 280 ° C) and a vacuum double belt press to finally impregnate the resin with the resin to form a one-direction (UD) thermoplastic composite Sheet.

Example  2

A glass fiber (Owens Corning SE4121-2400TEX) same as that used in Example 1 was weighed in a plain weave having a light and weft of 90 degrees and then applied to the equipment of Fig. 5, Sheet.

Example  3

The same procedure as in Example 1 was repeated except that the glass fiber of Example 1 was passed through a carding machine (103, Spreader), and the fibers were opened at a rate of 7 times the width and then dipped in a resin slurry. A material sheet was prepared. At this time, the fibers were preheated in the carding machine at a temperature of 160 ° C and an air pressure of 0.5 MPa, and the fibers were first opened and subjected to secondary opening by applying vibration at a vertical amplitude of 10 mm per second at a temperature of 180 ° C. and an air pressure of 0.7 MPa , At a temperature of 200 DEG C and an air pressure of 1.0 MPa, the glass fibers were thirdly opened by applying a vibration with a vertical amplitude of 10 mm per second.

Example  4

A unidirectional (UD) thermoplastic composite sheet was produced in the same manner as in Example 1, except that carbon fibers (Torayca Carbon Fiber T700SC-12000-50C, T700SC-24000-50C, Toray Advanced Material) were used as reinforcing fibers.

Example  5

Except that carbon fibers (Torayca Carbon Fiber T700SC-12000-50C, T700SC-24000-50C, manufactured by Toray Industries, Ltd.), which was the same as that used in Example 4, were weaved with a plain weave having a weft of 90 °. A thermoplastic composite sheet was prepared in the same manner.

Example  6

A unidirectional (UD) thermoplastic composite sheet was prepared in the same manner as in Example 3, except that carbon fibers (Torayca Carbon Fiber T700SC-12000-50C, T700SC-24000-50C, Toray Advanced Materials) were used as reinforcing fibers.

Example  7

A one-directional (UD) thermoplastic composite sheet was prepared in the same manner as in Example 1, except that the resin fine particles were replaced by Production Example 2.

Example  8

A one-direction (UD) thermoplastic composite sheet was prepared in the same manner as in Example 1, except that the resin fine particles were replaced by Production Example 3.

Example  9

A one-directional (UD) thermoplastic composite sheet was prepared in the same manner as in Example 1, except that the resin fine particles were replaced by Production Example 4.

Comparative Example  One

A unidirectional (UD) thermoplastic composite sheet was prepared in the same manner as in Example 1, except that the resin fine particles were replaced by Comparative Production Example 1.

Comparative Example  2

A one-direction (UD) thermoplastic composite sheet was prepared in the same manner as in Example 2, except that the resin beads were replaced by Comparative Production Example 1.

Comparative Example  3

A unidirectional (UD) thermoplastic composite sheet was produced in the same manner as in Example 3, except that the resin fine particles were replaced by Comparative Production Example 1.

Comparative Example  4

A unidirectional (UD) thermoplastic composite sheet was prepared in the same manner as in Example 4, except that the resin fine particles were replaced by Comparative Production Example 2.

Comparative Example  5

A unidirectional (UD) thermoplastic composite sheet was produced in the same manner as in Example 5, except that the resin fine particles were replaced by Comparative Production Example 2.

Comparative Example  6

A unidirectional (UD) thermoplastic composite sheet was produced in the same manner as in Example 6, except that the resin fine particles were replaced by Comparative Preparation Example 2.

Comparative Example  7

A unidirectional (UD) thermoplastic composite sheet was prepared in the same manner as in Comparative Example 3, except that the fibers were opened twice.

Comparative Example  8

A one-direction (UD) thermoplastic composite sheet was prepared in the same manner as in Comparative Example 3, except that the fibers were opened at 15 times.

Resin fine particles Reinforced fiber Fibrous Whether it is open or not
(Canine ratio) Example 1 Production Example 1 Glass fiber bunch X Example 2 Production Example 1 Glass fiber Knitted fabric - Example 3 Production Example 1 Glass fiber bunch O (7 times) Example 4 Production Example 1 Carbon fiber bunch X Example 5 Production Example 1 Carbon fiber Knitted fabric - Example 6 Production Example 1 Carbon fiber bunch O (7 times) Example 7 Production Example 2 Glass fiber bunch X Example 8 Production Example 3 Glass fiber bunch X Example 9 Production Example 4 Glass fiber bunch X Comparative Example 1 Comparative Preparation Example 1 Glass fiber bunch X Comparative Example 2 Comparative Preparation Example 1 Glass fiber Knitted fabric - Comparative Example 3 Comparative Preparation Example 1 Glass fiber bunch O (7 times) Comparative Example 4 Comparative Production Example 2 Carbon fiber bunch X Comparative Example 5 Comparative Production Example 2 Carbon fiber Knitted fabric - Comparative Example 6 Comparative Production Example 2 Carbon fiber bunch O (7 times) Comparative Example 7 Comparative Preparation Example 1 Glass fiber bunch O (2 times) Comparative Example 8 Comparative Preparation Example 1 Glass fiber bunch O (15 times)

< Measurement example  2>

The UD and woven polyamide composite sheets prepared through the above Examples and Comparative Examples were made into sheets having a thickness of 4T and then subjected to the physical properties test according to the following test methods. The results are shown in Table 3 below.

Porosity: To measure the resin impregnation property of the uniaxial (UD) thermoplastic composite material and the woven type thermoplastic composite prepared through the above Examples and Comparative Examples, the void volume content was measured according to the following formula (2) ASTM-792).

(Equation 3)

V (porosity%) = (Td-Md) / Td

Td (theoretical composite density) = 100 / (R / D + r / d)

R = Resin weight%, r = Reinforcement weight%,

D = Density of resin, d = Density of reinforcement,

Md = measured composite density.

- Tensile Strength: A test piece (length 250 mm, width 15 mm, thickness 1.0 mm) was stretched at a tensile rate of 0.05 inch / min, a sampling rate of 10 Hz, and an ambient temperature of 22 ° C using an Instron tensile tester according to ASMT D 3039 , And 65% RH. At this time, the samples were tested in equilibrium at a temperature of 22 ° C and 65% RH in a standard laboratory condition.

- Flexural Strength and Elastic Modulus: Flexural strength and elastic modulus were measured at 23 ℃ according to ASTM D 790 using universal testing machine (Model SFM-10) manufactured by United Co. of USA. , Thickness 4.0mm) was measured at a constant speed until the plastic sample was destroyed or reached a pre-determined value when a load was applied at 3 or 4 points.

Porosity (%) The tensile strength
(MPa) Flexural strength
(MPa) Flexural modulus
(GPa) Example 1 1.3 540 620 28.7 Example 2 1.8 380 546 22.9 Example 3 0.7 772 910 33.0 Example 4 1.1 975 890 84.0 Example 5 1.3 820 840 75.2 Example 6 0.4 1130 900 90.5 Example 7 1.8 468 490 23.1 Example 8 1.9 410 450 20.2 Example 9 1.6 502 550 23.8 Comparative Example 1 3.1 390 485 16.5 Comparative Example 2 3.5 310 450 11.0 Comparative Example 3 2.7 580 725 21.0 Comparative Example 4 4.0 610 590 57.0 Comparative Example 5 5.8 480 510 48.0 Comparative Example 6 3.5 740 720 63.5 Comparative Example 7 2.9 450 580 18.5 Comparative Example 8 2.1 420 560 17.0

As can be seen from the results of Table 3, the composite sheets of Examples 1 to 6 using the spherical polyamide fine particles were different from the composite sheets of Comparative Examples 1 to 6 having the same conditions except for the fine particles, (Porosity is low), and thus the physical properties of tensile strength, flexural strength, and flexural modulus are remarkably excellent.

In addition, as can be seen from the results of Examples 7 to 9, although differences in physical properties slightly occur depending on the diameter and particle size distribution of the resin fine particles, in the case where the conditions do not deviate from the case of the present invention, It was found that the physical properties were superior to those using the fine particles. If the degree of carding is insufficient under the same conditions as in Comparative Example 3, the impregnation rate may be lowered and the physical properties may be lowered. If the carding degree is too high as in Comparative Example 3, impregnation may be improved, It can be confirmed that the physical properties can be deteriorated rather than being directed in a specific direction.

101: Roving Fiber 201: Fabric Fabric:
102: Tension unit 103: Spreader
104, 202: Slurry tank
105, 203: Drying chamber (Dry Chember)
106, 204: Preheating chamber
107, 205: puller
108, 206: Vacuum press part (Double belt Vacuum press)
109, 207: Cutter

Claims (7)

(S1) a fiber supplying step of supplying fibers on a bundle or a knitted fabric;
(S2) immersing the supplied fibers in a polyamide slurry in which polyamide resin fine particles and a dispersant are dispersed in water, followed by drying; And
(S3) heating and melting the dried fiber to impregnate the polyamide resin with the fiber,
Wherein the polyamide resin fine particles in step (S2) are true spherical particles having a circularity (R) of 0.9 to 1.0 as defined by the following formula (1): < EMI ID =
<Formula 1>
Roundness R = 4 S _meas / π D _max ²
Where S _meas is the actual cross-sectional area of the particle, and D _max is the maximum diameter of the particle.
The method according to claim 1, wherein the fibers supplied in the step (S1) are bundle-type fibers, and the bundle-type fibers supplied between the steps (S1) and (S2) &Lt; / RTI &gt; further comprising a step (S1-a).
The method as claimed in claim 2, wherein the fiber opening step (S1-a) comprises: a first opening step of preheating the supplied bundled fibers at a temperature of 150 to 200 DEG C and an air pressure of 0.3 to 0.7 MPa;
A second opening step of causing the primary opened fibers to vibrate at a vertical amplitude of 5 to 15 mm per second at a temperature of 150 to 200 DEG C and an air pressure of 0.5 to 1 MPa; And
And a third opening step of further vibrating the second opened fiber at a temperature of 160 to 220 DEG C and a vertical amplitude of 5 to 15 mm per second under an air pressure of 0.8 to 1.5 MPa. Gt;
The method for producing a fiber-reinforced composite material sheet according to claim 1, wherein the polyamide resin fine particles have an average particle diameter of 5 to 20 占 퐉 and a particle size distribution defined by the following formula 2: 25 to 40%.
<Formula 2>
Particle size distribution (%) = (standard deviation of particle diameter / average diameter of particles) x 100
The method of producing a fiber-reinforced composite material sheet according to claim 1, wherein the fiber is glass fiber (GF), carbon fiber (CF), or aramid fiber (AF).
A polyamide resin and a fiber impregnated in the polyamide resin, wherein a porosity (V) defined by the following formula (3) is 2% or less.
<Formula 3>
V (porosity%) = (Td-Md) / Td
Td (theoretical composite density) = 100 / (R / D + r / d)
R = Resin weight%, r = Reinforcement weight%,
D = Density of resin, d = Density of reinforcement,
Md = measured composite density.
The fiber-reinforced composite material sheet according to claim 6, wherein the fiber-reinforced composite material sheet is manufactured by the manufacturing method according to any one of claims 1 to 5.

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