JPH04201420A - Manufacture of glass fiber reinforced resin molded article - Google Patents

Abstract

PURPOSE:To mold a unidirectionally reinforced glass fiber reinforced resin molded article very fluidly by a method wherein composition of unidirectionally orientated long glass fibers and thermoplastic resin and composition of short glass fibers having the predetermined length and thermoplastic resin are stamped at a predetermined weight ratio. CONSTITUTION:Bar-like strand composition A is prepared by bundling long glass fibers having the diameter of 5-20mum and impregnating with thermoplastic resin. When a bumper is molded, for example, the length of the strand is preferably the same as that of the bumper and the strand having 60% of more of the length of the bumper maybe allowably used. The preferable glass fiber content after the impregnation of the thermoplastic resin is 20-60wt.%. Said strand composition A is arranged in the mold of a bumper beam under the condition that the long direction of the fiber is set to the long direction of the bumper beam. After that, composition B of short glass fibers having the length of 2-25mm and thermoplastic resin is kneaded under heat with an extruder and supplied in the mold. At this time, the proper weight ratio of A/B is 10-45. Thus, stamping becomes possible very fluidly without lowering the strength and the like of a molded article.

Description

[Detailed Description of the Invention] [Industrial Application] The present invention is a glass suitable for parts that require impact resistance, strength, and heat resistance, such as automobile bumper beams, transmission members, radiator support members, and steering members. This article relates to a method for manufacturing fiber-reinforced resin molded products.

[Prior art]

Generally, molded products may be required to have strength or impact resistance in a specific direction. For example, in the case of a bumper beam, this is the length direction.

Up until now, bumper beams, transmission members, etc. have been made of high-strength steel. The present invention attempts to replace this with a glass fiber reinforced resin molded product from the viewpoint of weight reduction and economic efficiency.

Some glass fiber reinforced resin molded products are made by mixing short glass fibers and resin, but since the fibers are arranged in random directions, it is not possible to specifically strengthen only one direction.

It is also known that a glass mat is impregnated with a thermoplastic resin such as polypropylene and then stamped. However, since all the fibers of the glass mat are not arranged in one direction, the same problem as above still occurs.

[Problem to be solved by the invention]

As mentioned above, conventionally it has been difficult to manufacture molded products that are particularly reinforced in only one direction. Furthermore, stamping molding only of a composition of long glass fibers arranged in one direction and a resin results in poor fluidity, making it impossible to obtain molded products of various shapes. Moreover, even simple shapes tend to warp so much that they have no commercial value.

An object of the present invention is to provide a method for molding a glass fiber-reinforced resin molded product reinforced in one direction with good fluidity by stamping molding.

[Failure to solve the problem]

The present invention is characterized by using together a composition (A) of long glass fibers arranged in one direction and a resin, and a composition (B) of short glass fibers of a specific length and a resin. This allows for stamping molding with good fluidity while keeping the long glass fibers oriented in one direction.

The present invention will be explained in detail below.

The long glass fibers used in the present invention suitably have a diameter of 5 to 20 mm, preferably 8 to 13 mm. For example, about 2000 of these fibers are bundled and impregnated with a thermoplastic resin to obtain a rod-shaped strand composition (A).

The impregnation method may be a known pultrusion method. The length of the strand is determined by the target molded product.For example, if it is a bumper, strength in the longitudinal direction is required, so it is desirable that the strand length is the same as the length of the bumper, but 6096 or more is sufficient. The goal is achieved.

Suitable glass fiber content after impregnation is 20-60% by weight,
30 to 50% by weight is preferred.

Thermoplastic resins include polyolefin, polyester,
Polycarbonate, polybutylene terephthalate, noryl or a blend of noryl and polyamide are used. - The above polyolefins include (1) a homopolymer with a xylene soluble content of at most 5.0% by weight at a temperature of 30°C; (3) an ethylene-propylene random copolymer having a copolymerization ratio of 25 to 75% by weight and a copolymerization ratio of ethylene of 1 to IO;
Compositions of one or more propylene-ethylene random copolymers can be used, or ethylene-propylene random copolymers alone should be avoided to enhance synthesis. The melt flow rate of these thermoplastic resins is preferably in the range of 0.3 to 200 g/10 minutes, preferably in the range of 1 to 100 g/10 minutes at 230°C.

The short glass fibers of the composition of short glass fibers and resin have a length of 2 to 25+a+s. The thickness may be the same as the long fibers mentioned above. Further, the type and content of the resin are also the same. Therefore, this composition (B) can be prepared by cutting the long fiber composition into 2 to 25 pieces.

The molding is a known stamping method, for example, in the case of a bumper beam, the above strand composition (A) is arranged in a bumper beam mold with the length direction of the fibers aligned in the bumper beam length direction, and then placed on top of the strand composition (A). Add composition (B).

In this case, the composition (13) is heated and kneaded in an extruder,
It is supplied into the mold.

During this time, short fibers are cut and become short, especially 10 mu
If the length exceeds , it will be about half the original length.

(A) and (B) are determined at a predetermined ratio depending on the type of product, and stamping is performed. This ratio is generally (A)
/ (B) weight ratio of 1.0 to 45 is appropriate.

[For production]

In the present invention, composition CB) plays an important role and enables stamping molding with good fluidity without weakening the strength of the molded product. This composition (B) can be supplied to a mold for stamping molding using an extruder or the like while maintaining the reinforcing effect of glass fibers, and can impart fluidity to the entire system during stamping molding.

When the short glass fibers have a length of less than 2n, the reinforcing effect of the fibers is small. When a normal extrusion molding machine is used, the number of glass fibers in the two columns in the composition is about 0.31, or the practical reinforcing effect is maintained. On the other hand, if the number exceeds 25, composition (B)
It is difficult to feed the composition using an extruder, and the fluidity of the composition during stamping molding becomes poor.

[Forming and evaluation method] The prototype bumper beam has a length of 1500 m+s and a width of 25 mm.
0 matters. Its weight is approximately 4 kg (specific gravity 1.17).

The procedure for molding this is to place 3 kg of composition (A) lengthwise on a mold of a stamping machine, heat it to 215°C through an infrared heating furnace, and then apply composition (B) on top of it using a stamping machine. An extruder is used for melt extrusion under computer control. The mold is lowered to compress and flow.

The pressure at that time was loOkg/c- per unit area, and the total load was 200 tons. The collision test assumed that the vehicle body weighed 1000 kg, and the speed at the time of collision was 5 mph/h using a 1300 kg pensulum (collision jig).
I went to r. In addition, in this crash test using a molded product of the same torque, the material that can withstand the impact of a collision is the buckling load of the static load.
It has been empirically known that the amount exceeds O tons. Therefore, a crash test can be predicted by a buckling test under static load.

[Examples 1 to 6 A resin composition (A) of 1000 mm long glass fiber strands and a 13 mm long glass fiber strand (B) were prepared in a mold for forming a cobumper beam, and the same composition (B) of 13 mm was prepared in a mold for forming a cobumper beam. I did the molding. At that time, the weight ratio of both in Example 1 was (-
A)/(B) ='3/I and the glass content is (
Both ^) and (B) are 40x FF196. In a 5 mile/hr collision test of this molded product, no damage was observed due to impact in both frontal and side collisions. In addition, the static load test showed that the buckling strength was 11.8 tons, indicating that there is a correspondence between impact strength and static load strength. Furthermore, in order to examine the degree to which the strength due to the unidirectional fiber arrangement was reduced by the forming flow, tensile test pieces were cut from the center and both sides of the bumper beam and their strengths were measured. According to this, the degree of material deterioration was 16%, indicating that the strength deterioration in one direction was probably due to molding flow. In Examples 2 to 6, the weight ratio of composition (A) and composition (B) was changed as shown in Table 1 and molded, and the impact performance and mechanical strength at each of the above parts were measured. did. As a result, it was found that the change in tensile strength was small and the degree of decrease in tensile strength was small due to unidirectional alignment or molding due to flow.

The resin used here has a MFR of 80 g/10 minutes
It is a composition consisting of 82% by weight of a polypropylene homopolymer (30°C) and 18% by weight of an ethylene-propylene random copolymer (96% by weight). The copolymerization ratio of propylene in this copolymer is 40% by weight. The VFR of the composition was 40 g/10 min/230°C).

[Comparative Example 1 In Example 1, the material composition was (A)/(B) -o,
It was blended and molded to give a weight of 1. In crash tests at that time, impact failure occurred when speeds exceeded 3.8 miles/hr. In addition, in the buckling test under static load at that time, 810
0kg f, which does not meet the empirical standard value. Furthermore, when each part of the product was cut out and subjected to a tensile test, it was found that either there was little variation in the tensile strength of each part, or that the strength of the product itself was too low to withstand impact.

[Comparative Example 2] If the long fiber long pellet (a) was molded alone in Example 1, the molded product would be twisted and the intended product could not be achieved. However, if the molded product is attached to a jig and a crash test is performed, it can withstand the impact of a crash at speeds of up to 7.6 miles/hr. In addition, when a buckling test using a static load is carried out, it shows a high strength of 13 tons, or it is meaningless as the product loses its commercial value due to the large amount of warpage.

[Comparative Example 3 A stampable sheet made from co-glass mat (core oriented in one direction) has a glass content of 40% by weight, and has a tensile strength of 1300 kg/cd in the direction of glass fiber orientation.
The sheet temperature was heated to 215° C. by infrared heating using a sheet with a power of 430 kg f/cJ in the right angle direction. The heated sheet was put into a mold attached to a press and compression molded. The molding pressure was 500 tons and the molding pressure per unit area was 133 kg/cd. In a crash test using the product, it was found that it could withstand a frontal collision at a speed of 5 miles per hour, but a side collision withstand a speed of 2 miles per hour.
．． It was found that it could only withstand speeds of 5 miles/hr. In addition, when the buckling strength was measured in a static load test, it was 13.9.
It was a ton.

When a tensile test piece was cut out from the product and its strength was measured, the strength reduction rate at the tip was 66.7% compared to the center.
It was found that the orientation in one direction was weakened due to molding flow, and the strength of the product was significantly reduced.

Depending on the shape of the product, properties that have been strengthened in one direction tend to deteriorate significantly in areas where the flow path is large.

Furthermore, the molding pressure is approximately twice as high as that of long fiber composite materials, and the moldability is poor. Furthermore, when the tensile strength of the rib portion of the product was measured, it was 230 kg/cd, which was a significant decrease in strength due to welding. Observing the cross section, it was found that because the glass mat prevented the glass fibers from flowing into the ribs, only the resin was filled and a weld was formed.

〔Effect of the invention〕 1) Impact strength is extremely high.

2) The tensile strength in the direction in which the glass fibers are oriented is more than twice that of a glass mat.

3) There is little variation in characteristics in each part of the molded product. This indicates that there is little disturbance in fiber orientation due to molding flow.

4) Since a predetermined amount of the short glass fiber resin composition is blended, fluidity (moldability) is good, and the molded product does not warp.

Claims (3)

[Claims] (1) A composition (A) of long glass fibers and thermoplastic resin arranged in one direction that requires strength of the molded product, and
The randomly oriented short glass fibers of 25 mm and the thermoplastic resin composition (B) were mixed at a weight ratio of (A)/(B) of 1.
1. A method for producing a glass fiber reinforced resin molded product, which comprises stamping molding at a temperature of 0 to 4.5. (2) Manufacturing a glass fiber reinforced resin molded article according to claim 1, wherein the length of the long glass fibers is 60% or more of the length of the molded article in the direction where strength is required. Law. (3) The amount of long glass fibers in (A) is 20 to 60% by weight
A method for manufacturing a glass fiber reinforced resin molded article according to claim 1 or 2.