JPH0137503B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thermoplastic synthetic resin composite sheet reinforced with glass fibers, and more specifically, a mat formed from a cotton-like body of opened glass discontinuous fibers to which thermoplastic synthetic resin powder is dispersed and adhered. Reinforced with glass fibers, which consists of heating to a temperature above the melting (softening) point of the thermoplastic synthetic resin, or after heating, and applying pressure until the gas in the mat ceases to exist or at least does not exist as continuous pores. The present invention relates to a method for producing a thermoplastic synthetic resin composite sheet. The term "spreading" as used herein refers to fiber bundles or strands in which tens to hundreds of single glass fibers are bundled together, or yarns in which a predetermined number of fibers are twisted together by twisting these strands. An operation in which an external force is applied to loosen the material. Furthermore, the term "opened glass fibers" also includes glass single fibers (filaments) produced as intermediate products during the production of strands and yarns. Conventionally, there are the following methods for manufacturing glass fiber-reinforced thermoplastic synthetic resin composite sheets. (a) A method in which cut glass fibers are kneaded with thermoplastic synthetic resin and formed into a sheet using an extruder or the like. (b) A method of bonding two molten thermoplastic synthetic resin sheets through the openings of a woven fabric made of glass fibers with a relatively low weave density (for example, a plain weave cloth). (c) A method of impregnating a glass fiber nonwoven fabric (for example, chopped strand pine, continuous strand pine, etc.) with a molten thermoplastic synthetic resin. However, each of the above conventional techniques has the following drawbacks. In method (a), glass fibers break during the kneading and sheet forming steps, making it difficult to obtain high-strength products. For example, a sheet made by kneading 6 mm long glass fibers (chopped strands) with thermoplastic synthetic resin in a Banbury mixer and molding them in an extruder has most of the glass fibers cut to 2 mm or less in length, and According to such a method, most of the glass fibers are oriented in the warp direction of the sheet, resulting in an imbalance in warp and warp strength. Method (b) does not have the disadvantages of method (a), but it is difficult to impregnate thermoplastic synthetic resin in a woven fabric with dense glass fibers, so thermoplastic synthetic resins with low melt viscosity, It is necessary to use glass fibers with a coarse weaving density. Such cloths are not only expensive, but because the amount of glass fiber used relative to the thermoplastic synthetic resin is kept low, it is difficult to obtain sheets with high strength. In method (c), strands with a small number of glass fiber bundles or chopped strands are generally used to improve impregnation with thermoplastic synthetic resin.
The impregnation process is easier than method (b), but it is still not sufficient, and it is extremely difficult to impregnate thick pine. For example, in order to manufacture a thick sheet of 2 mm or more, it is necessary to impregnate thin pine. It is necessary to laminate many layers of sheets. Furthermore, both methods (b) and (c) have a common drawback in that it is difficult to obtain a sheet with a smooth surface, but this is because both methods use fiber bundles with a considerable diameter, such as strands or rovings. This is because the resin melted and impregnated into the resin shrinks when it solidifies, causing a phenomenon called sink marks. The present inventors have arrived at the present invention as a result of intensive research into a method for manufacturing a glass fiber-reinforced thermoplastic synthetic resin sheet that comprehensively eliminates the above-mentioned drawbacks associated with the prior art. That is, in the present invention, 100 parts by weight of thermoplastic synthetic resin powder with a particle size of 1 mm or less is mixed with a fiber length of 2
A flocculent mat is prepared by mixing and stirring with 5 to 300 parts by weight of discontinuous glass fibers in the range of ~50 mm, or by mixing and stirring with the opened fibers to uniformly disperse the fibers. Smoothing characterized by applying pressure while heating to a temperature higher than the melting point or softening point of the thermoplastic synthetic resin, or after heating, until gas (air) in the mat ceases to exist or at least ceases to exist as continuous pores. This is a method for producing glass fiber reinforced thermoplastic synthetic resin sheets. The glass fiber reinforced thermoplastic synthetic resin sheet obtained by the method of the present invention has the following characteristics. (1) Because the opened discontinuous glass fibers are uniformly dispersed during the manufacturing process without being broken, the resulting sheet has a smooth surface, no unbalanced strength in the weft and weft, and is resistant to impact. Excellent mechanical strength such as strength and tensile strength. (2) Since the amount of the synthetic resin dispersed and adhered to the glass fibers can be varied over a wide range, the glass fiber content of the resulting sheet can also be varied over a wide range. For example, it is possible to mix 300 parts by weight of glass fiber with 100 parts by weight of synthetic resin.
Therefore, a sheet having excellent strength can be easily obtained. (3) Thermoplastic synthetic resins must be in the form of powder, and there are no other limitations, so the resin can be used in a wide range of applications. (4) Commercially available relatively inexpensive rovings, strands, and chopped strands that have been cut in advance can be used as glass fibers, so
Economically advantageous. (5) Since it is a combination of glass discontinuous fibers and thermoplastic synthetic resin, the molded composite sheet can be further shaped into any desired shape by press molding (stamping molding). (6) Can be easily manufactured into any desired sheet, from thin sheets with a thickness of 1 mm or less to thick sheets with a thickness of 4 mm or more. The configuration of the present invention will be described in detail below. Commercially available products are used as the glass fibers used in the present invention. Among these, strands are made by pulling tens to hundreds of single glass fibers (filaments) together and bundled with a glue such as polyvinyl acetate, polyester, or epoxy resin, and winding several tens to dozens of these filaments. Preferably, the rovings are cut to a predetermined length. In addition, it is convenient to use commercially available chopped strands that are cut into various lengths. Alternatively, a yarn obtained by twisting the strands and twisting a predetermined number of yarns can also be used, but the former is preferable from the viewpoint of ease of opening. Since the product of the present invention is intended to be a sheet with a smooth, homogeneous surface and high strength, the bundled strands used need to be opened to loosen them as much as possible and make them fluffy. Therefore, it is preferable to use a so-called soft type strand that uses a small amount of sizing agent, and if the strand is tightly bundled, it is preferable to remove the sizing agent with a solvent beforehand. on the other hand,
In the present invention, it is also possible to cut and use filaments obtained as intermediate products during the production of strands, etc., which are not generally commercially available. When using these materials, it is preferable to pre-treat the surface with a silane-based or borane-based coupling agent in order to increase the bonding strength with the thermoplastic synthetic resin. The glass fibers used in the present invention are cut into relatively long lengths, and the length must be at least 2 mm, preferably 3 mm or more. The use of glass fibers with a length of less than 2 mm is undesirable because the strength of the glass fibers is comparable to that of conventional sheets obtained by kneading the glass fibers with a thermoplastic synthetic resin and molding them using an extruder. On the other hand, there is no clear limit on the upper limit of the length, but even if the length of the glass fiber exceeds 50 mm, the strength will not particularly increase. This is not preferable because it makes opening the fibers and dispersing the synthetic resin powder difficult. The thermoplastic synthetic resin used in the present invention is not particularly limited, and examples include polyolefin resins, polystyrene resins, polyvinyl chloride resins, polyacrylic acid resins, polyamide resins, polyester resins, and polycarbonate resins. used.
In order to further increase the bonding strength with glass fibers, these resins can be chemically modified and used. In order to increase the added value of the sheet obtained by the method of the present invention, for example, to impart twist resistance, flame retardant treatment is applied to the resin, and to impart heat resistance, thermally crosslinkable resin powder is applied to glass fibers. It is also possible to carry out treatments such as dispersion and adhesion and crosslinking during molding. In the present invention, powder is always used for the thermoplastic synthetic resin, and the particle size thereof is 1 mm or less, preferably
It is 0.5mm or less. If the particle size exceeds 1 mm or more,
The synthetic resin settles under its own weight and is not uniformly dispersed in the glass fiber floc. This synthetic resin powder may be machine-pulverized from general pellet-like, bead-like products, or molded product waste, but it is preferable to use powder obtained during the synthetic resin manufacturing process. This is the most advantageous in terms of economy. The amount of glass fiber used in the method of the present invention is 5 to 300 parts by weight per 100 parts by weight of the thermoplastic synthetic resin.
Preferably it is 10 to 200 parts by weight. If this amount is less than 5 parts by weight, almost no reinforcing effect by the glass fibers will be observed, and if it exceeds 300 parts by weight, it will not be possible to obtain a sheet in which the glass fibers are completely wrapped in the synthetic resin. Next, an embodiment of the method for producing a glass fiber-reinforced thermoplastic synthetic resin composite sheet of the present invention will be described. The method of the present invention involves cutting continuous glass fibers,
After opening, thermoplastic synthetic resin powder is attached,
Alternatively, cut glass fibers are mixed and stirred with thermoplastic synthetic resin powder while being opened, and the thermoplastic synthetic resin powder is dispersed and adhered to the cotton-like material, which is shaped into a pine-like material with almost uniform thickness, and then heated. This is a method in which the plastic synthetic resin is heated to a temperature higher than its melting (softening) point, pressurized until at least continuous air pores no longer exist, and then cooled. Glass fibers, such as chopped strands that have been opened in advance, or cut strand yarns that have been opened, are charged into a mixer such as a twin-screw ribbon blender, and thermoplastic synthetic resin powder is added to the mixer. Add the resin powder and mix and adhere while stirring, or mix and stir chopped strands and synthetic resin powder at the same time.
The thermoplastic synthetic resin powder is dispersed and adhered to the flocculent body by a method in which the synthetic resin powder is gradually mixed and adhered to the chopped strands during the opening process. In this way, the mechanism by which the thermoplastic synthetic resin powder is uniformly distributed and adhered to the glass fiber flocculent body is due to the effect that the synthetic resin powder is wrapped in the entanglement of the fibers of the glass fiber flocculent body. It is also assumed that electrostatic force generated by friction during mixing is acting. Therefore, the use of glass fibers treated with antistatic agents in the present invention should be avoided. Next, the mat in which thermoplastic synthetic resin powder is dispersed and adhered to the obtained glass flocculent is heated to a temperature higher than the melting (softening) point of the synthetic resin, or is pressed after heating. The degree of pressurization at this time is preferably as high as possible, and in practice, the gas (air) existing in the pine is completely expelled and no longer exists in the pine, or at least no longer exists as continuous pores. The material is melted and pressurized until it loses air permeability. Since the voids (independent pores) remaining in the sheet deteriorate the physical properties of the sheet, that is, the mechanical strength, it is preferable to carry out melting and pressing at as high a temperature and pressure as possible. The above-mentioned method of forming a flocculent body of glass fiber in which synthetic resin powder is dispersed and adhered into a mat shape, heating and pressurizing it to form a sheet can be carried out by either a batch method or a continuous method. When using the batch method, a mold of a predetermined size is filled with flocculent glass fibers in which synthetic resin powder is dispersed and adhered, heated and pressurized from the outside, and then cooled and taken out. Ru. When using a continuous method, for example, a flocculent body of glass fibers is continuously fed onto a belt conveyor to form a mat, which is then temporarily compressed with an endless belt placed above it while being heated from the outside, or several fibers are The method used is to compress the material through heating rolls, form it into a sheet, cool it with cooling rolls, and then take it off. As detailed above, the glass fiber-reinforced thermoplastic synthetic resin composite sheet obtained by the method of the present invention has a smooth, homogeneous surface and high mechanical strength, so it can be used widely as a plate material. In addition, since the discontinuous glass fibers are uniformly dispersed, it can be used as a raw material that can be further thermoformed into products of various shapes using matted metal dies, that is, stampable sheets. It can also be served. The present invention will be specifically described below with reference to Examples. Example 1 Polypropylene (product name:
"Mitsui Noblen JHH (G)" manufactured by Mitsui Toatsu Chemical Co., Ltd.)
Using 100 parts by weight of powder (particle size of 20 mesh or less) and 20 parts by weight of chopped glass fiber with a length of 6 mm (trade name "CS6PE-612", manufactured by Nitto Boseki Co., Ltd.), both were combined. When the chopped strands were placed in a beaker and stirred and mixed using two stirring rods while applying frictional force to the chopped strands, the chopped strands were gradually opened into a cotton-like material, into which polypropylene powder was added. A mixture was obtained in which the particles were almost uniformly dispersed and adhered. Next, 135 g of the mixture was piled up in a mat shape of approximately the same thickness in a metal frame with a long side of 250 mm, a short side of 150 mm, and a depth of 3.5 mm, and the top and bottom of the pile was covered with two pressing iron plates. Load it into a 100 ton hydraulic press,
Preheat at 220℃ for 5 minutes, then heat at 220℃ for 5 minutes at 100℃.
Pressurized at a pressure of Kg/cm ² G, then transferred to another hydraulic press and heated at 35°C for 5 minutes at a pressure of 100 Kg/cm ² G.
It was cooled down. The obtained sheet is a polypropylene sheet (thickness 3.5 x length 250 x width 150 mm) in which opened glass fibers with a length of 6 mm are almost uniformly dispersed.
It was hot. Table 1 shows the tensile strength and Izod impact strength results measured for this sheet. Comparative Example 1 The same glass fibers and polypropylene as in Example 1 were charged into a Brabender plastograph mixer in the same ratio as in Example 1, and kneaded at 180°C for 5 minutes.
When the obtained kneaded product was press-molded in the same manner as in Example 1, a polypropylene sheet was obtained in which glass fibers cut into lengths of approximately 0.2 to 1 mm during kneading were uniformly dispersed. The tensile strength and Izod impact strength of this sheet are shown in Table 1, and both values were significantly inferior to those of Example 1. Example 2 100 parts by weight of the same polypropylene powder used in Example 1 and 67 parts by weight of chopped strands were stirred and mixed in the same manner as in Example 1.
A sheet was prepared in the same manner as in Example 1 using 160 g. The obtained sheet was a polypropylene sheet in which opened glass fibers having a length of 6 mm were almost uniformly dispersed. The tensile strength and Izot impact strength are shown in Table 1, and the values were somewhat higher than those of Example 1. Example 3 The same polypropylene used in Example 1
Using 100 parts by weight and 67 parts by weight of a chopped strand of glass fiber with a length of 25 mm (product name: "CS-25Z-700" manufactured by Nittobo Co., Ltd.) from which the sizing agent was removed with acetone, The mixture was stirred and mixed in the same manner as in Example 1, and a sheet was prepared in the same manner as in Example 1 using 160 g of the mixture. The obtained sheet was a polypropylene sheet in which opened glass fibers having a length of 25 mm were almost uniformly dispersed. The tensile strength and Izot impact strength are shown in Table 1, and both showed the highest values. Example 4 Thermoplastic synthetic resin and high-density polyethylene (product name: "Stafrene E-891", manufactured by Nippon Petrochemicals Co., Ltd.)
100 parts by weight of powder (particle size of 20 mesh or less) and the same chopped strand as used in Example 1
Using 100 parts by weight, the mixture was stirred and mixed in the same manner as in Example 1, and 180 g thereof was used to prepare a sheet in the same manner as in Example 1. The obtained sheet was a polyethylene sheet in which opened glass fibers having a length of 6 mm were almost uniformly dispersed. The tensile strength and Izot impact strength are shown in Table 1. Example 5 100 parts by weight of powder obtained by mechanically crushing a polystyrene molded product into a thermoplastic synthetic resin and passing it through a 20-mesh sieve, and 300 parts by weight of the same chopped strands used in Example 1 were used. The mixture was stirred and mixed in the same manner as in Example 1, and a sheet was prepared in the same manner as in Example 1 using 240 g of the mixture. The obtained sheet was a polystyrene sheet in which opened glass fibers having a length of 6 mm were almost uniformly dispersed.

[Table] Comparative Example 2 100 parts by weight of the same polystyrene powder as in Example 5 was uniformly placed on 300 parts by weight of commercially available glass fiber chopped strand mat (trade name "MC450A-104" manufactured by Nittobo Co., Ltd.). This was sandwiched between two iron pressing plates to produce a sheet under the same pressing conditions as in Example 1. Obtained sheet (thickness 0.4mm x 200
mm x 200 mm), the penetration of the polystyrene into the chopped strand pine was insufficient, and the glass fibers were exposed on the bottom surface.

Claims (1)

[Claims] 1 Thermoplastic synthetic resin powder with a particle size of 1 mm or less
100 parts by weight is mixed and stirred with 5 to 300 parts by weight of discontinuous glass fibers having a fiber length in the range of 2 to 50 mm while being opened, or mixed and stirred with the opened fibers to uniformly disperse the fibers. While heating the flocculent pine to a temperature equal to or higher than the melting point or softening point of the thermoplastic synthetic resin, or after heating, until the gas (air) in the pine ceases to exist or at least ceases to exist as continuous pores. A method for manufacturing smooth glass fiber reinforced thermoplastic synthetic resin sheets, which is characterized by pressurization.