JPS6240457B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a press-formable glass fiber reinforced thermoplastic resin sheet (hereinafter referred to as FRTP sheet).
The present invention relates to a method of manufacturing a glass fiber mat structure for use in a car. With the recent advances in press-molded FRTP sheets, products that were traditionally manufactured by press-molding metal, such as automobile hoods, trunk covers, front condo retainers, and seat frames, are being replaced by these molded products. The trend is becoming more and more active. These molded products have the advantages of being lightweight, being able to change the thickness of the cross section, and adding bosses or ribs freely during molding, as well as being able to shorten the pressing process. ing. The FRTP sheet is manufactured by laminated pressing or continuous lamination of thermoplastic resin and glass fiber mat, and these methods are described, for example, in JP-A-52-40588 and JP-A-48-80172. has been disclosed. obtained in such a way
The ERTP sheet is then heated and then made into a molded product by press-forming between cooled matte dies.
Disclosed in SAEpaper 720063, Plastic Age October issue (1971), pages 83-88. The above ERTP sheet to be press-formed is called a blank, and the blank is heated to a temperature above the softening point or melting point of its component thermoplastic resin, and then cooled to a temperature below the softening point or melting point. The material is transferred between molds, the molds are closed, and press molding is performed. During press forming, it is important that the heated blank be easy to handle when transferred to the press mold, and that the heated blank be non-adhesive and have excellent heat retention. can be given. If the heated blank is sticky, the component thermoplastic resin will adhere to gloves, a transfer jig, etc. when the blank is transferred to a press mold. Furthermore, if there is no heat retaining property, the thermoplastic resin, which is a component, will solidify during transportation before press molding. Furthermore, during press molding, the thermoplastic resin and glass fiber, which are one of the components of the blank, are required to move freely together without separating, and to flow well to the corners of the mold. It has become clear that such ease of handling and fluidity is due to the structure of the glass fiber mat, which is one of the components of the FRTP sheet. Blanks whose reinforcing component is a thermosetting resin binder such as commercially available contained strand pine and chopped strand pine that maintains the pine shape are difficult to avoid because the glass fiber and thermoplastic resin separate during press molding. I don't like it because it stows away. Needle punching is well known to those skilled in the art as a method for maintaining the mat shape. As a result of the study, it became clear that a blank obtained from a FRTP sheet made of mat, which is made by mechanically bonding glass fibers by needle punching, has the above-mentioned excellent handling properties and fluidity. The blank is expanded by a heating operation prior to press molding, and a portion of the glass fibers are exposed on the surface. The reason for this is not clear, but
Glass fiber mats are inherently bulky, and some of the glass fibers are arranged in the thickness direction by needle punching, and they are under compression in the FRTP sheet, but the blank obtained from it is heated. It is presumed that this is due to the fact that the original bulkiness is regained. As a result, the heated blank has a non-adhesive surface, has good heat retaining properties due to expansion, and is easy to handle. Moreover, since the glass fibers in the blank are only mechanically entangled, they can easily flow together with the thermoplastic resin under pressure after heating. However, in the glass fiber mat obtained by needle punching, the glass fibers are oriented in the drawing direction of the mat during needle punching, and when the needle is inserted into the mat, the mat is expanded in the width direction (hereinafter referred to as diffusion). ), and there are drawbacks such as non-uniform distribution of glass fibers in the width direction of the mat.As a result, products obtained from FRTP sheets containing glass fiber mat as a reinforcing component are This results in a serious defect that the distribution is non-uniform and anisotropic. In view of the above, the present inventors have determined that the present invention does not have the above defects.
As a result of extensive research to obtain an FRTP sheet, we have developed an FRTP sheet for press molding that successfully overcomes the above defects by dispersing glass fibers on a thermoplastic plastic film and then needle-punching the film and glass fibers at the same time. The present inventors have discovered that a glass fiber mat structure for use in industrial use can be obtained, and have completed the present invention. That is, the present invention relates to a method for manufacturing a press-formable glass fiber mat structure for an FRTP sheet. The present invention will be explained in detail below. Preferred embodiments of the glass fiber mat used in the present invention are shown below. Each glass fiber has a diameter of 2μ
~30μ, preferably 5μ to 25μ, and the length is 1
It is continuous at least 1 cm, preferably 2 cm or more. Several or more of these glass fibers are bundled and dispersed on a thermoplastic film as chopped strands or continuous strands, and then needle punched.
The surface of the glass fiber can be surface-treated with a binder, lubricant, emulsifier, PH regulator, antistatic agent, coupling agent, etc. Examples of the thermoplastic film used in the present invention include polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene-butadiene-acrylonitrile copolymer,
Resins such as polyamide, polycarbonate, polysulfone, polyacetal, polymethyl methacrylate, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, and thermoplastic elastic bodies such as thermoplastic polyurethane and thermoplastic polyester, and two or more of these. It also includes mixtures of the above, with the addition of commonly used plasticizers, heat stabilizers, light stabilizers, nucleating agents, fillers, facial cleansers, processing aids, impact agents, fillers, short glass fibers, etc. However, when these are laminated together with glass fiber mat in the FRTP sheet, it is preferable to use a material that can flow during press molding of the blank obtained from the FRTP sheet, and is similar to or similar to the matrix resin of the FRTP sheet. The same one is best. If the film thickness is less than 5μ, the damage during needle punching will be severe and the purpose cannot be achieved, and if it is more than 500μ, the load on the needle punching machine will increase and the needle may break. This causes problems such as poor melt bonding of the sheet to the matrix resin.
The preferred film thickness is 10μ to 200μ. The density of needling when needle punching thermoplastic film and glass fiber can be selected as appropriate, but if this is expressed as N, then 0.1<
Preferably, a range of N<300 is selected. Here, N=b/a・n ₁・n ₂ (pieces/cm ² ) a: Movement distance of the strand mat per unit time (cm/min) b: Value of the needle in the feeding direction of the needling machine Length (cm) n ₁ : Needle density of needling machine (needle/cm ² ) n ₂ : Number of needling per unit time (times/cm 2 )
min) Next, the method for manufacturing the glass fiber mat structure of the present invention will be briefly described with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a manufacturing apparatus for a glass fiber mat structure according to the present invention. A glass fiber bundle 1 sent from a strand or roving (several to several hundred strands bundled) supply source (not shown) passes through gripping rolls 2 and 3, is cut by a cutter 4, and is placed on a belt 5. The thermoplastic film 6 is randomly oriented and deposited on the thermoplastic film 6 by rotation of the belt drive roll 7.
The mat 12 on which the and glass fibers 13 have been deposited are continuously and simultaneously sent to a needle punching machine 8, where they are both needle punched by a needle 9 and wound up onto a winding roll 10. glass fiber 1
The length of the cutter 3 can be changed by changing the pitch of the blades of the cutter 4 or by arbitrarily selecting the rotation ratio of the gripping roll 2 and the cutter 4. In the case of continuous glass fiber, a large number of cutter devices 11 are used instead of the cutter device 11. A device can be used to traverse the strands of glass to randomly deposit continuous glass fibers onto the film. A feature of the method of manufacturing a glass fiber mat structure according to the present invention is that the thermoplastic film 6 and the mat 12 dispersed and deposited on the film are needle-punched at the same time. The thermoplastic film 6 is
This film is useful for easily transferring the mat 12 on which the glass fibers 13 are deposited to the bed 14 of a needle punching machine, but the most important point is that when the mat 12 is needle punched, the glass fibers 13 are The aim is to suppress the glass fibers from spreading and from arranging the glass fibers in the direction in which the pine is taken up. The reason for this is not completely understood, but it is thought to be roughly as follows. FIG. 2 is a cross section of the mat on the belt 5 before being needle punched, and FIG. 3 is a cross section of the mat after being needle punched. In Figure 2,
Although the individual glass fibers 13 can move freely, the third
As shown, some of the glass fibers in the needle-punched mat are oriented in the thickness direction and these fibers pass through the holes 15 in the film punched by the needle punch.
Since these glass fibers are intertwined with the holes in the film, the glass fibers 13 are inhibited from spreading in the width direction and from arranging in the direction of taking the mat as soon as the mat begins to receive the needle. The resulting glass fiber mat structure has a uniform GF in the width direction.
are dispersed and have no anisotropy. The thermoplastic film 6 can be wound up on the take-up roll 16 after needle punching, or it may be taken up on the take-up roll 10 together with the reinforced glass fiber mat structure 17. An additional film 6' may be added as shown in FIG. 1 to further suppress the spread of the glass fibers in the width direction and the orientation of the mat in the drawing direction. Similarly, film 6'
After needle punching, the material is wound onto a take-up roll 16'. The glass fiber mat structure obtained by the present invention is laminated with a thermoplastic resin by a known method such as pressing or extrusion lamination, or integrated by a method such as impregnating the thermoplastic resin into the glass fiber mat. It is said to be a press-formable FRTP sheet. Next, the sheet is cut into an appropriate size to be made into a molded product, and heated using infrared rays or a heating plate to a temperature above the melting point or softening point and below the decomposition temperature of the thermoplastic resin that is the matrix of the FRTP sheet. The FRTP sheet is press-molded in a mold that is cooled below the melting point or softening point of the thermoplastic resin that forms the matrix of the FRTP sheet. Using the glass fiber mat structure according to the present invention
The FRTP sheet expanded in the thickness direction when heated before press forming, had excellent heat retention properties and was non-adhesive, and was easy to handle when transferring the heated sheet to the press mold. Furthermore, during press molding,
The thermoplastic resin and glass fiber, which are components of the FRTP sheet, flowed to every corner of the mold without separating, and a molded product with almost no anisotropy was obtained. Examples are shown below to further clarify the present invention, but this is not intended to limit the scope of the present invention. Example 1 Glass fiber (hereinafter abbreviated as GF) chopped strands (#712/66 roving manufactured by PPG, USA) cut to approximately 5 cm on a polypropylene (FL8012 manufactured by Sumitomo Chemical) film with a thickness of 50 μm and a width of 30 cm. (obtained by cutting with a chopped strand cutter) was randomly deposited at 900 g/m ² to a width of 18 cm, with a punch density of 100 times/m ² and a needle depth of 2.
A continuous GF pine structure was obtained by needle punching under cm conditions. The obtained GF mat structure had a width of about 20 cm, and there was almost no diffusion of GF in the width direction. The weight distribution of GF in the cross section in the width direction is shown in 1 of FIG. Next, both ears of the obtained GF mat structure were cut by 1 cm each to have a width of 18 cm and a length of 23 cm.
As shown in the figure, two mat structures and a polypropylene sheet 1 (surface layer 0.07
cm, middle layer 0.16 cm, Sumitomo Chemical W501) are laminated and pressed to a width of 18 cm, a length of 23 cm, and a thickness of 0.38 cm.
A reinforced polypropylene sheet was obtained. Next, the sheet was heated to about 210°C in an infrared oven, and a pressed metal die was used to form a small rectangular tray (long plate) into the molded product shown in the cross-sectional view of Fig. 6 (schematic diagram) and Fig. 7. Length 25cm, Width 20cm, Height 1cm Average inner thickness
2.6cm) was obtained. The sheet expanded after heating, and GF was embossed on the surface and was non-adhesive. Adhesion was determined by visually observing the amount of polymer component adhering to the leather glove when the heating sheet was manually transferred to a matted metal die. Furthermore, since the heating sheet has sufficient heat retention during this transfer,
The polypropylene did not solidify. Further, in the obtained molded product, GF was well flowing even to the edges, and the GF content was measured by cutting out parts C and D in Fig. 6 by incineration method. Both C and D parts
The GF content was 38%, and the GF was uniformly dispersed. The tensile strengths of test pieces A and B cut out from the molded product in arrow directions A and B are 1000 Kg/cm ² , respectively.
It was 950Kg/cm ² and almost no anisotropy was observed. Note that A is the machine direction and B is the width direction.
The above results are shown in Table 1. Example 2 Instead of the GF chopped strand in Example 1, GF continuous strand (#712/66 manufactured by PPG, USA) was used.
Got it from roving. ) A reinforced polypropylene sheet was produced in exactly the same manner as in Example 1, except that the GF strands were swirl-deposited on a polypropylene film, and then a molded article was obtained. The results are shown in Table 1. Comparative Example 1 A GF mat structure was obtained in the same manner as in Example 1 except that the polypropylene film in Example 1 was not used. The obtained GF pine structure is
It was widely spread in the width direction, and was about 28 cm wide. The GF weight distribution in the cross section in the width direction is shown in Figure 4, 2. Next, both ears of the obtained GF mat structure were cut by 5 cm, and a reinforced polypropylene sheet was obtained in the same manner as in Example 1, and a press-molded product was obtained. The results are shown in Table 1. Comparative Example 2 Two commercially available GF continuous swirl mats (Asahi Glass Fiber CSM8600: 450 g/m ² ) were stacked for one GF mat structure of Example 1,
This and a polypropylene sheet were laminated in the same manner as in Example 1 to obtain a reinforced polypropylene sheet. Table 1 shows the properties and handleability of the molded product obtained from the sheet during molding. Comparative Example 3 A reinforced polypropylene sheet was prepared in the same manner as in Comparative Example 2, except that a commercially available GF chopped strand mat (Nittobo MC-450A: 450 g/m ² ) was used instead of the GF continuous swirl mat in Comparative Example 2. I got it. Table 1 shows the handling properties of the sheet during molding and the properties of the molded product. 【table】

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a manufacturing apparatus for a glass fiber mat structure according to the present invention. 1: Glass fiber bundle, 2;
3: Gripping roll, 4: Cutter, 5: Transfer belt, 6; 6': Thermoplastic film, 7: Belt drive roll, 8: Needle punching device, 9: Needle, 10: Winding roll, 11: Tip Dostrand cutter device, 12: glass fiber deposit, 13: glass fiber, 14: bed, 16;
16': Thermoplastic film winding roll, 17: Glass fiber mat structure, Figure 2 is a cross-sectional view of the glass fiber mat structure before being needle punched, and Figure 3 is the glass after being needle punched. A cross-sectional view of the fiber mat structure, 15: Holes created in the thermoplastic film by needle punching, Figure 4 shows the GF in the width direction of the glass fiber mat structure.
Distribution, 1: GF distribution according to the present invention, 2: GF distribution in comparative example, FIG. 5: Laminated product of thermoplastic resin and glass fiber mat structure, 1: Thermoplastic resin, 2: Glass fiber mat structure, Figure 6: Molded product, A: Tensile test piece in the A direction (pine pulling direction), B: Tensile test piece in the B direction (width direction), No. 7
Figure: A cross-sectional view of the molded product.

Claims (1)

[Claims] 1. After dispersing glass fibers on a thermoplastic film having a thickness in the range of 5 to 500 μm, the film and glass fibers are bonded together at a needling density N of 0.1.
A method for manufacturing a fiber mat structure for a fiber-reinforced thermoplastic resin sheet that can be press-formed without diffusion of glass fibers in the width direction, characterized by simultaneously needle punching in the range of <N<300. Here, N=b/a・n ₁・n ₂ (pieces/cm ² ) a: Distance traveled by the strand pine per unit time (cm/min) b: Needle placement in the feeding direction of the needling machine Length (cm) n ₁ : Needle density of needling machine (needle/cm ² ) n ₂ : Number of needling per unit time (times/cm 2 )
^cm2 )