KR950011714B1 - Method for manufacturing fiber reinforced thermoplastic composite - Google Patents

Abstract

The fiber-reinforced thermoplastic composite prepreg is manufactured by: (a) laminating a barium sulfate-dispersed low flowable polypropylene sheet(1), a non-oriented glass fiber mat(2), a woven mat(3) of a glass long fiber as a warp and a polypropylene fiber as a weft, a molten polypropylene resin(4), the mat(3), the mat(2) and the sheet(1) in order; (b) pressing the laminated makerial in the double belt press at 210 deg.C and 30 psi; and (c) cooling it. The composite prepreg has a good heat resistance and surface gloss property, and is used in the mfr. of vehicle parts and architectural form molds.

Description

Fabrication method of fiber reinforced thermoplastic composite prepreg

1 shows a lamination order for producing the thermoplastic composite prepreg of the present invention.

* Explanation of symbols for main parts of the drawings

1: low flow polypropylene sheet 2: non-oriented glass fiber mat

3: Mat using glass filament for ramp and polypropylene fiber for weft

4: polypropylene resin

The present invention relates to a method for producing a plate-shaped fiber-reinforced thermoplastic composite material, and more specifically, using a thermoplastic resin and a fibrous or mat-like glass fiber reinforcement, reusable, excellent mechanical strength, heat resistance, surface gloss, A method for producing a fiber-reinforced thermoplastic composite prepreg with excellent impregnation properties.

In general, a material reinforced with short glass fibers is developed as a fiber-reinforced plastic, but strength and rigidity are improved by cutting glass fibers in pellet manufacturing process and injection molding process, but impact resistance is not improved and glass fiber orientation is not improved. The dimensional stability of the molded product is lowered, the thermosetting composite resin is excellent in heat resistance, but the situation is a problem in productivity degradation and layer resistance by the curing time.

Therefore, the plate-shaped fiber-reinforced thermoplastics are light stamping molding (STAMPING MOLDING) that has the advantage of excellent mechanical strength and does not require a process such as curing, that is, by heating the plate-shaped prepreg above the melting temperature of the resin, A method of manufacturing an arbitrary molded article by advancing it into a heated mold, compressing the molded mold, and cooling the mold is being progressed.The thermoplastic composite resin produced by the stamping molding method is widely used for automobile parts, formwork for civil inspection, etc. I use it.

On the other hand, when forming a plate-like thermoplastic composite material, when prepreg is injected into a mold and compression molded to produce a flat product, the fibrous reinforcing material flows like a resin and fills the mold. Eggplant is generally used by needle punching (NEEDLE PUNCHING).

However, when the resin and the non-oriented glass fiber mat is used, the mechanical properties and the like are improved, but the surface properties are not good, and in particular, the molded article is subjected to a force in one direction, the mechanical properties are insufficient. In addition, the properties of the composite material are determined by the shape and content of the matrix (MATRIX) and the glass fiber mat, the arrangement state and the aggregation state, in particular, the interfacial adhesion between the substrate and the glass fiber mat and whether the resin is impregnated into the glass fiber mat This is important because it affects the property deterioration due to pore generation in the composite material.

The method for manufacturing plate-shaped composite prepregs proposed so far is suitable for glass fiber mats in US Pat. Nos. 3,664,909 and 3,684,645, and in US Pat. Nos. 3,883,333 and 3,664,909 for special processing of glass fiber mats. SIZING methods are described in US Pat. No. 3,849,148 and the like.

However, the above method relates to a method for producing a plate-shaped thermoplastic composite material, but it is possible to produce a composite material having excellent impact resistance and rigidity, but the impregnability of the resin is not sufficient, so the surface characteristics are poor. In addition, as a method for improving the impregnation of the resin, a method using high-flow polypropylene is proposed in EP 211,249, but the surface characteristics are poor and the molded part has a complicated shape when compressing the composite prepreg. In the case of having a shape such as ribs (RIB), there was a disadvantage in that only the resin was filled, thereby not showing the reinforcing effect.

In addition, in order to improve the inner properties and mechanical properties in one direction, US Patent No. 4,691,375 and European Patent No. 434,846, etc. have been proposed, but impregnation of resin becomes a problem where glass fibers are arranged in one direction. The disadvantage of poor surface properties due to the oriented glass fiber mat.

Accordingly, an object of the present invention is to provide a method for producing a fiber-reinforced thermoplastic composite prepreg that is reusable, has excellent mechanical strength, and particularly has excellent heat resistance, surface properties, impregnation, and mechanical properties in one direction.

In order to achieve the above object as well as yet another object that can be easily expressed in the present invention (1) used a low-flow polypropylene sheet in which barium sulfate is dispersed on both sides, (2) an unoriented glass fiber mat In order to align the glass fibers in one direction, a mat using a long glass fiber and a polypropylene fiber as a weft yarn was needle-punched with an unoriented glass fiber mat, and (3) between two needle-punched glass fiber mats by melting with an extruder. It was possible to improve the surface properties, impregnability, and mechanical properties in one direction by laminating using polypropylene resin, thermal melting impregnation in the atmosphere above the melting temperature of the resin, and cooling.

The present invention will be described in more detail as follows.

First, as shown in FIG. 1, a low-flow polypropylene sheet (1) / orientated glass fiber mat (2) in which barium sulfate is dispersed / a mat using glass filament as a warp yarn and a polypropylene fiber as a weft yarn (3) / Polypropylene resin melted with extruder (4) Mat (3) / Oriented glass fiber mat (2) / Low-flow polypropylene sheet (1) ) And hot melt impregnated in an atmosphere above the melting temperature of the resin, followed by cooling to prepare a prepreg of the thermoplastic composite material of the present invention.

The low-flow polypropylene resin used in the present invention is obtained by sheeting a polypropylene resin having a melt index (MELT INDEX) in the range of 1.5 to 6 g / min, measured at a load of 230 ° C. and 2,16 kg based on ASTM D1238. The thickness of the sheet was adjusted so that the polypropylene resin used for the thermoplastic composite material was in the range of 50 to 70 wt% of the total weight. When the polypropylene resin is 50 wt% or less of the total weight, the fluidity is lowered, and when it is 70 wt% or more, physical properties such as strength decrease.

In addition, the polypropylene resin was modified by a conventional method using maleic acid, acrylic acid, etc. to improve adhesion to glass fibers, and 1 to 20wt% of barium sulfate in the polypropylene sheet used on both sides to improve surface gloss. More preferably, 5-10 wt /% was added and used. At this time, it is preferable to use the barium sulfate whose particle diameter is 1-15 micrometers, More preferably, 3-10 micrometers. When the barium sulfate is used at 1wt% or less, the surface gloss is poor, and when it is used at 20wt% or more, the surface state of the final product is uneven.When the particle size is 1um or less, the surface gloss is poor, and when the particle size is 15um or more, the impregnation of the resin There was this bad issue.

The reinforcing material was used by needle punching the non-oriented glass fiber mat, the inclined glass long fiber, and the weft yarn using a polypropylene fiber. In this case, the diameter of the glass fiber in the mat of the non-oriented glass fiber is preferably 10 to 25um, more preferably 17 to 22um, 100 to 500 glass fiber monofilaments, more preferably 300 to 400 focusing It is effective to use a glass fiber non-oriented glass fiber mat which has been made and surface treated with an organosilane compound, and is preferably used in an amount of 10 to 30 wt%, more preferably 15 to 20 wt%, based on the total weight of the composite material.

When the diameter of the glass fiber is less than 10um, there is a disadvantage that the impregnation of the resin is not good. If the diameter of the glass fiber is more than 25um, there is a problem that the strength of the composite material is lowered. There is a drawback, and when the concentration is more than 500, there is a disadvantage that the resin is not impregnated well, when the non-oriented glass fiber mat is used in less than 10wt%, there is a problem in flowability and impregnation, when used in more than 30wt% There was a problem that the strength to the furnace was lowered.

It is effective to incline the mat made of glass filament and weft polypropylene fiber, and the diameter of the glass filament monofilament is 15-25 um, more preferably 18-22 um, and the connection degree is 300-400. It was preferable to use one. The content of the glass fibers used as the warp is preferably in the range of 10 to 30% by weight, more preferably 20 to 25% by weight, based on the total weight of the composite material.

If the diameter of the glass filament monofilament is 15um or less, there is a problem in the impregnation of the resin, if it is 25um or more, there is a disadvantage that the strength in one direction is lowered, and when the collecting speed is 300 or less, the strength is reduced. If it is 400 or more, there is a problem in the impregnation of the resin, if the content of the glass fiber used as a slope is less than 10% by weight relative to the weight of the composite material, there is a disadvantage that the resin impregnation is lowered, if more than 30wt% the strength decreases in one direction There was a problem.

Oriented glass fiber mats and warp yarns are made of long filament fiber, and weft yarns are entangled with each other when needle balancing polypropylene mat. Needle punching makes glass fibers cut and short fibers are produced. It is effective to make the content of the glass fiber having a length of 30 cm or less, depending on the shape, the number of needle punching, etc., to be 1 to 30 wt%, more preferably 10 to 20 wt%, based on the total content of the unoriented glass fiber.

When the content of the produced short fibers is less than 1% by weight relative to the total amount of non-oriented glass fibers, there is a problem of fluidity of the composite material during molding, and when the content of the short fibers is 30% by weight or more, there is a problem in that the strength decreases. The content ratio of the non-oriented glass fiber mat and the inclined glass filament fiber and the weft yarn to the mat using polypropylene is preferably 40:60 to 60:40. If the content ratio is 40:60 or less, there is a problem in the impregnability and fluidity of the resin, and if 60:40 or more, there is a problem in that the strength in one direction is lowered.

The thermoplastic composite prepreg of the present invention prepared by the above-described method was particularly excellent in mechanical properties in the direction in which the glass fibers were arranged in the inclined direction, and impregnation and surface properties were also improved. It can be used for bumper beam of automobile parts by compression molding and can be used for various fields such as building materials and mechanical parts.

The following examples and comparative examples further illustrate the invention but do not limit the scope of the invention. The thermoplastic composite prepregs prepared in Examples and Comparative Examples were evaluated by the following method.

1) Tensile strength: evaluated by ASTM D638

2) Impact strength: evaluated by ASTM D256

3) Heat deflection temperature: evaluated by ASTM D746

4) Impregnation of resin

Density measurement of composite prepreg with automatic density meter

5) Liquidity

The composite prepreg is cut into 10 × 10 cm in width and length, preheated to 200 ° C. for 20 minutes in an infrared oven (OVEN), and then compressed to 85 kg / cm 2 pressure at a mold temperature of 70 ° C. and 10 × 50 cm in width. Molded. Since the flowability of the composite material was calculated by the following equation.

Example 1

The double-sided polypropylene sheet was a mixture of 8% by weight of barium sulfate having a diameter of 8 um mixed with a polypropylene resin grafted maleic acid by a conventional method as an initiator. The polypropylene resin between the mats using the fiber and the weft polypropylene fiber was laminated by extruding low flow polypropylene having a melt index of 4 g / 10 min and maleic acid grafted. A continuous strand surface-treated with methoxysilane, which has a weight of 450g / m2 per unit area, 20% by weight, based on the total weight of the thermoplastic composite prepreg. Matte, which is a polypropylene fiber, has a glass fiber content of 22% by weight relative to the total weight of the thermoplastic composite prepreg. The lower lamination is made of polypropylene sheet mixed with barium sulfate, non-oriented glass fiber mat, inclined fiberglass fiber, the weft is made of polypropylene fiber, and the mat / polypropylene sheet / warp is made of glass fiber, and the weft is polypropylene fiber. A low-flow polypropylene sheet in which woven mat / oriented glass fiber mat / barium sulfate was dispersed. At this time, the non-oriented glass fiber mat, the inclined glass fiber, and the weft yarn woven with polypropylene fiber, the needle punching was required eight times per square centimeter (1cm2).

After lamination as described above, the resin was cooled by heating and pressing under a condition of 210 ° C. and 30 psi by a double belt press (DOUBLE BELT PRESS) to prepare a thermoplastic composite material prepreg of 3.7 mm.

Table 1 shows the results of physical properties of the prepared glass fiber composite prepreg.

Example 2

An unoriented glass fiber mat is used at 18% by weight based on the total weight of the thermoplastic composite prepreg, and the glass fiber content is thermoplastic composite in a mat having a glass fiber having a warp diameter of 22 um and a collecting speed of 350 and a weft yarn of polypropylene fiber. Except for using 24% by weight relative to the total weight of the material prepreg was carried out in the same manner as in Example 1, and the physical properties results are shown in Table 1.

Example 3

Except that the barium sulfate in the polypropylene sheet on both sides of 10wt% of the polypropylene resin was carried out in the same manner as in Example 1, and the physical properties results are shown in Table 1.

Example 4

It was carried out in the same manner as in Example 1 except that the inclined diameter 22um, glass filament 300 of the collecting speed and the weft yarn is a polypropylene fiber mat, the physical properties are shown in Table 1.

Comparative Example 1

Instead of using a mat of inclined glass filament and weft polypropylene fiber, a reinforcement material was punched using an unoriented glass fiber mat in which only one direction of glass filament having a diameter of 20 um and a focal length of 350 was arranged in one direction. Except that was carried out in the same manner as in Example 1, the physical properties are shown in Table 1.

Comparative Example 2

The non-oriented glass fiber mat is 20% by weight based on the total weight of the thermoplastic composite prepreg, and the glass fiber content of the thermoplastic composite material is 40 Except for using 22% by weight relative to the total weight of the material prepreg was carried out in the same manner as in Example 1, and the physical properties results are shown in Table 1.

Comparative Example 3

The polypropylene sheet on both sides was carried out in the same manner as in Example 1 except that barium sulfate was not mixed, and the physical property results are shown in Table 1.

TABLE 1

Claims (6)

Low flow polypropylene sheet (SHEET) / barreled glass fiber mat / slope with dispersed barium sulphate, glass filament for weft, polypropylene resin / slope melted with mat / extruder woven from polypropylene fiber, A method of manufacturing a fiber-reinforced thermoplastic composite prepreg, characterized in that the weft is laminated in the order of a low-flow polypropylene sheet dispersed in a mat / non-oriented glass fiber mat / barium sulfate woven from polypropylene fibers. The method of claim 1, wherein the non-oriented glass fiber mat and the inclined glass filament and the weft yarn are laminated by needle punching the mat woven from polypropylene fiber. The method of manufacturing a fiber-reinforced thermoplastic composite prepreg according to claim 1, wherein the barium sulfate dispersed in the low induction polypropylene sheet has a particle diameter of 1 to 15 µm and is dispersed by 1 to 20% by weight based on the weight of the polypropylene sheet. . The method of claim 1, wherein the polypropylene resin has a melt index of 1 to 6 g / min and a content of 50 to 70% by weight based on the total weight of the thermoplastic composite prepreg. . The method of claim 1, wherein the inclined glass fiber, the weft yarn in a mat woven of polypropylene fiber, the diameter of the glass fiber of the warp is 18 to 22wt%, the focusing speed is used to concentrate 300 to 400 monofilament Method for producing a fiber-reinforced thermoplastic composite prepreg, characterized in that. The total content of the glass fiber is 30 to 50wt%, the non-oriented glass fiber mat and the inclined glass filament, the weft yarn content ratio of the mat woven from polypropylene fiber is 40: 60 to 60: 40 Method for producing a fiber-reinforced thermoplastic composite material prepreg characterized in that.