JPS62256618A - Manufacture of fiber reinforced synthetic resin molded product - Google Patents

Abstract

PURPOSE:To prevent a molded product from getting such deformations as surface distortion, external waviness and the like by injecting from a gate provided in the mold into a cavity a liquid synthetic resin material containing reinforcing fiber and flat particles carrying a specific ratio against said reinforcing fiber. CONSTITUTION:Inorganic fibers or metal fibers such as milled glass fiber and the like are used for reinforcing fiber, while flake glass, mica and the like are used as flat particles. The ratio of flat particles is 20-50wt% against reinforcing fiber. As the ratio is larger than said %, the absolute quantity of reinforcing fiber should be lessened in order to prevent an increasing viscosity to make it difficult to get a desired strength or impact resistance, while a small % makes it difficult to get sufficient effect to minimize anisotropy. Both the raw liquids mixed with a mixing head 4 is further mixed in a static mixer 7, and injected into a cavity 10 through a runner 8 and a following gate 9.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing fiber-reinforced synthetic resin molded articles.

(Prior Art) In order to obtain a reinforced synthetic resin molded article, injection molding is generally performed using a liquid synthetic resin material mixed with glass fibers.

For example, in the case of polyurethane molding using R-RIM (reinforced reaction injection molding), if a mixture of isocyanate-based liquid A, polyol-based liquid B, and milled glass fiber is injected into the cavity through a gate provided in the mold. A foamed polyurethane molded product reinforced with the above-mentioned milled glass fibers is obtained and can be used for molding automobile bumpers and the like. In this case, the fibers tend to be oriented in the flow direction at the gate or cavity of the molding material, and the linear expansion coefficient of the molded product is kept low by the fibers in this flow direction, increasing the reinforcing effect in that direction. Generally, an anisotropy occurs in which the reinforcing effect is small in the direction orthogonal to the direction.

(Objective of the invention) In the conventional method of simply mixing fibers, the above anisotropy also appears in the molding yield MJ behavior after injection, and while the shrinkage in the machine direction is small, the shrinkage in the direction perpendicular to the machine direction is small. becomes large, causing deformation and warping of the molded product. This phenomenon is noticeable near the gate where the molding material flows quickly and tends to become complicated. In other words, large shrinkage in the gate width direction also affects the product parts in the vicinity, and especially when molding thin-walled products, the surface may be distorted or There is a problem in that the waviness is visible to the naked eye, and the present invention aims to provide a method for manufacturing a fiber-reinforced synthetic resin molded article that solves this problem.

(Structure of the Invention) The method for producing a fiber-reinforced synthetic resin molded article of the present invention includes introducing reinforcing fibers and flat particles having a proportion of 20 to 50% by weight relative to the reinforcing fibers into a cavity through a gate provided in a mold. It is characterized in that the liquid synthetic resin material contained therein is injected.

In this case, the main component of the synthetic resin material is a urethane material made of the above-mentioned incyanate solution and a polyol solution, a nylon material, a melted thermoplastic synthetic resin BFi, etc. by reaction or by heating. It is possible to use a material that is hardened by.

As the reinforcing fibers, inorganic fibers such as the above-mentioned milled glass fibers, metal fibers, etc. can be used.

As the flat particles, flake glass, mica, etc. can be used. In addition, the flat particles have an average thickness of 5 to 10 μm and an average particle size of 172 μm, which is the average length of the reinforcing fibers.
Below, for example, it is preferable that the maximum value of the average particle size is 50 to 300μ, and the minimum particle size of one particle is 1/2 or more of the maximum particle size, and furthermore, it is more difficult to break than mica, that is, in terms of impact resistance. Flake glass is preferred. That is, the flat particles have the effect of reducing the above-mentioned anisotropy, and if they are too large, the thickening effect becomes large, and this is also undesirable in terms of impact resistance.

Furthermore, if the difference between the minimum grain size and the maximum grain size is large, the anisotropy reduction effect described above will be reduced.

Next, the proportion of flat particles is 20 to 50% by weight of the reinforcing fibers.
This is because if the ratio is larger than that, the absolute amount of reinforcing fibers will need to be reduced in order to suppress thickening, making it difficult to obtain the desired strength or impact resistance. This is because if the above ratio is small, it becomes difficult to sufficiently obtain the effect of reducing anisotropy.

(Effects of the Invention) Therefore, according to the present invention, since flat particles are mixed with reinforcing fibers and injection molding is performed, anisotropy during molding shrinkage can be suppressed, and the desired strength or strength can be achieved. While ensuring impact resistance, it is possible to prevent deformations such as distortion and waviness from occurring in the molded product.

(Example) The present invention will be explained in detail below.

FIG. 1 shows the overall structure of a reaction injection molding apparatus 1. As shown in FIG. In the figure, 2 is a liquid A tank that stores an isocyanate stock solution, and 3 is a B liquid tank that stores a polyol stock solution, and the stock solutions are circulated between them and the mixing head 4. The mixing head 4 is connected to an upper mold 5 and a lower mold 6 (both mold temperatures are 70° C.).

The static mixer 7 is also shown in FIG.
Branch passages 7a, 7a branched into the runners 8 through a plurality of narrow passages 7b, and both liquids mixed in the mixing head 4 are further mixed in the static mixer 7 to form a liquid synthetic resin. The molding material is injected into a cavity 10 via a runner 8 and a gate 9 following it.

Next, specific examples of the liquid synthetic resin molding material will be described.

Example 1- The RIM raw materials of the second example are as follows.

Blowing agent (Freon-11) 2 Catalyst 1 (dibutyltin dilaurate) 0.1 Catalyst 2 (triethylene diamine) 2 The type and amount (% by weight of the molded product) of the filler added to the above RIM raw material are as follows. .

The surface distortion (height difference in undulations) near the gate 9 of the molded product obtained in this example is as shown in FIG.

That is, the maximum amount of waviness was 90μ, and no abnormality was detected on the surface of the molded product by visual inspection.

Example 2- The RTMg charge for this example is as follows.

Blowing agent (Freon-11) 3 Ethylene glycol 10 Catalyst 1 (Dibutyltin dilaurate) 0.15 Catalyst 2 (Triethylenediamine) 1
．． 5 The type and amount (% by weight of the molded product) of the filler added to the above RIM raw material are as follows.

(Average fiber length 180μ) The maximum amount of surface distortion near the gate 9 of the molded product obtained in this example is 100μ, and as in Example 1, no abnormality on the surface of the molded product can be detected by visual inspection. -Example 3- The RIM raw materials of this example are as follows.

29%) (molecular weight 5000) Ethylene glycol 10 tbw (dibutyl tin dilaurate > 0.2 blowing agent (fluorocarbon)
11) 3 The type and amount (weight % in the molded product) of the filler added to the above RIMM material are as follows.

Regarding the surface distortion near the gate 9 of the molded product obtained in this example, the maximum amount of waviness was 70μ, and as in Example 1, no abnormality on the surface of the molded product was detected by visual inspection.

Therefore, the molded product obtained in Example 1 has a
To obtain the g-expansion coefficient using the conventional method, milled glass fiber (
It is necessary to add fibers having an average fiber length of 240 μm to the RIM raw material so that the amount in the molded product is 10% by weight. In this case, the surface strain near the gate of the molded product is as shown in FIG. Namely.

The maximum amount of waviness was 250μ, and abnormalities on the surface of the molded product were clearly felt even by visual inspection. Incidentally, the surface distortion in the vicinity of the gate of a molded product made of RIM raw materials without the addition of fillers such as glass fibers is as shown in FIG.

The maximum amount of undulation was 30μ.

Therefore, from the results shown in FIGS. 3 to 5, it can be seen that the addition of the flake glass of Example 1 has a great effect on suppressing waviness on the surface of the molded product.

Further, in this Example 1, the addition of glass flakes did not particularly impede the flow and molding of the RIM raw material, and furthermore, the impact resistance of the molded product was comparable to that of the conventional example in which glass fiber was mixed.

On the other hand, in order to obtain a linear expansion coefficient similar to that of the molded product obtained in Example 2 using the conventional method, milled glass fibers (average fiber length 180μ) are added to the RIM raw material so that it accounts for 25% by weight in the molded product. However, in this case, the surface distortion near the gate of the molded product was 300μ at the maximum amount of waviness, and abnormality on the surface of the molded product was felt even by visual inspection.

Furthermore, in order to obtain a coefficient of linear expansion comparable to that of the molded product obtained in Example 3 using the conventional method, milled glass fibers (average fiber length 120μ) were added to the molded product by RIM so that the amount was 12% by weight. It is necessary to add it to the raw material, but in that case the distortion near the gate of the molded product is 150μ at the maximum amount of waviness.
An abnormality was felt on the surface of the molded product even by visual inspection.

[Brief explanation of drawings]

Figure 1 is an overall configuration diagram of the reaction injection molding apparatus, Figure 2 is a diagram showing the flow path of the synthetic resin material from the mixing head to the cavity, and Figures 3 to 5 are examples, in which flat particles are not mixed. FIG. 6 is a scanning line diagram showing undulations on the surface of a molded product near a gate in a conventional example and a conventional example in which no filler is mixed. 1... Reaction injection molding device, 2... Liquid A tank, 3... Liquid B tank, 5... Upper mold, 6...・Lower mold, 9...Gate, IO
······cavity. Grass 1 Figure 2

Claims (2)

[Claims] (1) In a method for obtaining a fiber-reinforced synthetic resin molded product by injecting a liquid synthetic resin material mixed with reinforcing fibers into a cavity from a gate provided in a mold, 20 to 50% by weight of the above-mentioned reinforcing fibers is used. 1. A method for producing a fiber-reinforced synthetic resin molded article, which comprises injection molding a synthetic resin material containing flat particles. (2) The method for producing a fiber-reinforced synthetic resin molded article according to claim 1, wherein the flat particles are glass flakes.