JP7583548B2 - Method for producing long fiber reinforced foam molding - Google Patents

Description

The present invention relates to a method for producing long fiber reinforced foam moldings.

2. Description of the Related Art Long fiber reinforced foamed molded articles, which contain a large number of long fibers aligned in one direction, are lightweight yet have excellent mechanical strength, and are therefore widely used as building materials and the like, as structural materials to replace wood.
Long fiber reinforced foam molded articles are mainly produced by impregnating a bundle of many long fibers (such as a bundle of glass rovings) aligned in one direction with a foamable resin composition (such as a foamable curable polyurethane resin composition), passing the impregnated bundle through a molding passage (inside a mold), and foaming and curing the foamable resin composition (Patent Document 1).

Patent No. 3670721

Since holes formed on the surface of a long fiber reinforced foamed molded product due to foaming can impair its appearance, it is necessary to prevent the formation of holes as much as possible.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a long fiber reinforced foamed molded article that is capable of suppressing the occurrence of holes on the surface.

In order to achieve the above object, the present invention employs the following configuration.
[1] A method for producing a long-fiber-reinforced foam molded product, comprising the steps of: moving a fiber bundle formed by aligning a plurality of long fiber reinforcing materials in one direction continuously in one direction while supplying a foamable resin composition to the moving fiber bundle; impregnating the fiber bundle with the supplied foamable resin composition to obtain a resin-impregnated fiber bundle; arranging a porous sheet on a surface of the resin-impregnated fiber bundle; and passing the resin-impregnated fiber bundle together with the porous sheet through a molding passage to foam and cure the foamable resin composition.
[2] The method for producing a long fiber reinforced foamed molded article according to [1], wherein the foamable resin composition contains at least a polyol compound, a polyisocyanate compound, and a foaming agent.
[3] The method for producing a long fiber reinforced foam molded product according to [1] or [2], wherein the porous sheet has an air permeability of 1.4 to 25.0 seconds as measured by the Gurley tester method defined in JIS P 8117 (2009).
[4] The method for producing a long fiber reinforced foam molding according to any one of [1] to [3], wherein the porous sheet has a thickness of 20 to 86 μm.

The manufacturing method of the long fiber reinforced foam molded product of the present invention can suppress the occurrence of holes on the product surface and produce a long fiber reinforced foam molded product with excellent appearance.

1 is an example of a production system for carrying out the method for producing a long fiber reinforced foam molded article of the present invention. FIG. 4 is an explanatory diagram showing the state of a resin-impregnated fiber bundle in a molding passage.

The fiber bundle used in the manufacturing method of the present invention is formed by aligning multiple long fiber reinforcing materials in one direction. There are no particular limitations on the long fiber reinforcing materials used to form the fiber bundle, but for example, roving or yarn, which are strands lightly attached with a binder to form a string-like material, are preferably used. Among these, roving is preferably used because it is easy to impregnate with the foamable resin composition, easy to mold, and the molded body has excellent mechanical properties.

The filaments constituting the strands may be monofilaments or fibrillated fibers (fibers protruding in whisker-like shapes).
The material of the long fiber reinforcing material is not particularly limited, and examples thereof include inorganic long fibers such as glass fibers and carbon fibers, and organic long fibers such as aramid fibers, polyester fibers, polyamide fibers, etc. In particular, long glass fibers are preferred.
The thickness of the monofilaments constituting these long fibers is generally preferably 10 to 20 μm in diameter.

The foamable resin composition used in the manufacturing method of the present invention is a thermosetting resin that is liquid before curing.
As the thermosetting resin, a thermosetting resin that is liquid before reaction is used, and a foamed resin is produced by curing and foaming a foamable resin composition containing a thermosetting resin, a curing agent, and a foaming agent. Examples of the thermosetting resin include urethane resin, unsaturated polyester resin, epoxy resin, diallyl phthalate resin, and phenol resin.

The foamable resin composition used in the production method of the present invention is preferably a foamable curable polyurethane resin composition in which the curable resin is a urethane-based resin.
When the foamable resin composition is a foam-curable polyurethane resin composition, the foamable resin composition contains at least a polyol compound, a polyisocyanate compound, and a foaming agent, and preferably further contains a foam stabilizer and a catalyst.
The polyol may preferably have a functional group number of 3 to 4. The polyisocyanate may be diphenylmethane diisocyanate (MDI) or modified MDI. The foaming agent may be water or fluorocarbon gas.

The porous sheet used in the production method of the present invention includes paper, plastic filters, and porous metal sheets.
Among these, paper is preferred since it is easily removed from the product when the product is processed.
As the paper, neutral paper, kraft paper, etc. can be used. Among them, neutral paper is preferable because it has high air permeability and allows air to pass through easily.

The air permeability of the porous sheet as measured by the Gurley tester method defined in JIS P 8117 (2009) is preferably 1.4 to 25.0 seconds.
When the air permeability of the porous sheet is equal to or lower than the preferred upper limit, the high air permeability effectively suppresses the generation of holes on the surface.
When the air permeability of the porous sheet is equal to or greater than the preferred lower limit, the strength of the sheet is easily maintained.

The thickness of the porous sheet is preferably 20 to 86 μm.
When the thickness of the porous sheet is equal to or less than the preferred upper limit, the air permeability is likely to be high, and the occurrence of holes on the surface is effectively suppressed.
When the thickness of the porous sheet is equal to or greater than the preferable lower limit, the strength of the sheet is easily maintained.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A manufacturing method according to an embodiment of the present invention will now be described with reference to the accompanying drawings. FIG 1 shows an example of a manufacturing system for carrying out the manufacturing method according to the present embodiment.
The production system in FIG. 1 includes a polyol liquid tank 11 , a hardener liquid tank 12 , a supply device 15 , an impregnation machine 16 , a pair of porous sheet supply rolls 18 , and a molding passage 19 .

It also includes a polyol liquid pump 21 for supplying the polyol liquid 1 stored in the polyol liquid tank 11 to the supply device 15, and a hardener liquid pump 22 for supplying the hardener liquid 2 stored in the hardener liquid tank 12 to the supply device 15.
Further, a fiber bundle 6 formed by aligning a plurality of long fiber reinforcing materials in one direction is continuously transported in one direction (to the right in the figure) by a transport means not shown.

The impregnation machine 16 may be, for example, one consisting of an impregnation plate 16a and multiple kneading plates 16b. An endless belt may be used instead of the impregnation plate 16a. It is also preferable to have a temperature regulator that adjusts the temperature of the impregnation plate 16a or the endless belt to a predetermined temperature.

The molding passage 19 may be, for example, a passage formed by surrounding the four sides with the surfaces of four metal belts 19a, as shown in FIG.
The metal belt 19a is heated to thermally harden and foam the resin-impregnated fiber bundle 7 passing through the molding passage 19.

The production of a long fiber reinforced foam molded article by the production system of FIG. 1 can be carried out, for example, as follows.
First, the polyol liquid 1 is supplied to the supply device 15 by the polyol liquid pump 21, and the hardener liquid 2 is supplied to the supply device 15 by the hardener liquid pump 22. The polyol liquid 1 and the hardener liquid 2 are mixed in the supply device 15 to form the foamable resin composition 5, which is supplied from the supply device 15 to the fiber bundle 6 in progress (step of supplying the foamable resin composition to the fiber bundle). For example, the foamable resin composition 5 may be sprayed onto the fiber bundle 6 using a spraying device.

Next, the fiber bundle 6 to which the foamable resin composition 5 has been supplied is treated by an impregnation machine 16. In the impregnation machine 16 shown in Fig. 1, the fiber bundle 6 is impregnated with the foamable resin composition 5 by being kneaded by a kneading plate 16b on an impregnation plate 16a, and becomes a resin-impregnated fiber bundle 7 (a process for obtaining a resin-impregnated fiber bundle).
Next, a porous sheet 8 is supplied from a pair of porous sheet supply rolls 18 to sandwich the resin-impregnated fiber bundle 7 from above and below, and placed on the surface of the resin-impregnated fiber bundle 7 (a step of placing a porous sheet).

The resin-impregnated fiber bundle 7 is then passed through the molding passage 19 together with the porous sheets 8 fed above and below it. While passing through the molding passage 19, the resin-impregnated fiber bundle 7 becomes a long fiber reinforced foamed molded article as the impregnated foamable resin composition 5 foams and hardens (foaming and hardening process). The obtained long fiber reinforced foamed molded article can be cut to an appropriate length for use.

According to the method for producing a long fiber reinforced foamed molded article of the present invention, the occurrence of holes on the surface of the product can be suppressed. The reasons for this are considered to be as follows.
That is, in the conventional method, when the foamable resin composition 5 impregnated in the resin-impregnated fiber bundle 7 foams and expands in the molding passage 19, the air bubbles generated in the portion where the foamable resin composition 5 is in close contact with the wall (metal belt 19a) of the molding passage 19 have no way to escape and remain as holes on the surface of the long fiber reinforced foamed molded body 9.

In contrast, according to the manufacturing method of the long fiber reinforced foamed molded body of the present invention, the porous sheet 8 arranged on the surface of the resin-impregnated fiber bundle 7 enters the molding passage 19 together with the resin-impregnated fiber bundle 7 in a state of adhering to the surface of the resin-impregnated fiber bundle 7. Therefore, as shown in FIG. 2, the porous sheet 8 is interposed between the resin-impregnated fiber bundle 7 and the wall (metal belt 19a) of the molding passage 19, and the foamable resin composition 5 can be prevented from directly adhering to the wall (metal belt 19a) of the molding passage 19. In addition, a gap is also formed between the porous sheet 8 and the wall (metal belt 19a) of the molding passage 19.

As a result, when the foamable resin composition 5 of the resin-impregnated fiber bundle 7 foams and expands in the molding passage 19, the air bubbles generated where the foamable resin composition 5 contacts the porous sheet 8 pass through the porous sheet 8 and further pass through the gap between the porous sheet 8 and the wall (metal belt 19a) of the molding passage 19, and can escape to the outside. Therefore, it is thought that the generated air bubbles can be prevented from remaining as holes on the surface of the long fiber reinforced foamed molded body 9, and the number of holes can be reduced.

[Measurement method]
The hole area of the long fiber reinforced foam molded product 9 obtained in each example was measured by a visual inspection machine on the production line. The measurement method was to irradiate the product with infrared light, read the area of the shadowed part with a camera, and process the image to calculate the hole area.
The air permeability of the porous sheet 8 used in the examples was measured by the Gurley tester method specified in JIS P 8117 (2009).
The thickness of the porous sheet 8 used in the examples was based on the values in the test report of the sales manufacturer measured based on the test method for paper and paperboard - thickness, density and specific volume specified in JIS P 8118 (2014).

[Comparative Example 1]
The fiber bundles 6 were made of long glass fibers.
Using the production system of FIG. 1, 100 parts by mass of propylene oxide-added polyether polyol as polyol liquid 1 and 150 parts by mass of diphenylmethane diisocyanate as hardener liquid 2 were supplied to supply device 15 to prepare foamable resin composition 5.
This foamable resin composition 5 was supplied in an amount of 100 parts by mass per 100 parts by mass of the fiber bundle 6 and then treated in an impregnation machine 16 to obtain a resin-impregnated fiber bundle 7 .
This resin-impregnated fiber bundle 7 was introduced as it was into the molding passage 19 and allowed to pass through without using the porous sheet 8. The hole area of the obtained long fiber reinforced foamed molded article 9 is shown in Table 1.

[Example 1]
A resin-impregnated fiber bundle 7 was obtained in the same manner as in Comparative Example 1. Kraft paper (air permeability 25 seconds, thickness 86 μm, width 280 cm) was supplied and arranged as a porous sheet 8 on the surface of this resin-impregnated fiber bundle 7 from above and below, and the bundle was then introduced into the molding passage 19, but the bundle was passed through the molding passage 19 in the same manner as in Comparative Example 1. The perforated area of the obtained long fiber reinforced foamed molded article 9 and the reduction rate of the perforated area (reduction rate of perforations) relative to Comparative Example 1 are shown in Table 1.

[Example 2]
A resin-impregnated fiber bundle 7 was obtained in the same manner as in Comparative Example 1. Neutral paper (air permeability 2 seconds, thickness 70 μm, width 280 cm) was supplied and arranged as porous sheets 8 on the top and bottom of the surface of this resin-impregnated fiber bundle 7 before being introduced into the molding passage 19, and the rest was passed through the molding passage 19 in the same manner as in Comparative Example 1. The perforated area of the obtained long fiber reinforced foamed molded article 9 and the reduction rate of the perforated area (reduction rate of perforations) compared to Comparative Example 1 are shown in Table 1.

As shown in Table 1, the area of holes was reduced by placing the porous sheet 8 on the surface of the resin-impregnated fiber bundle 7. The effect was particularly large in Example 2, which used a porous sheet 8 with a small air permeability value.

The long fiber reinforced foam molded products obtained by the manufacturing method of the long fiber reinforced foam molded products of the present invention have excellent appearance and can be widely used in applications such as buildings, vehicles and ships, railway facilities, and water treatment facilities.

Reference Signs List 1 Polyol liquid 2 Hardener liquid 5 Foamable resin composition 6 Fiber bundle 7 Resin-impregnated fiber bundle 8 Porous sheet 9 Long fiber reinforced foamed molded body 11 Polyol liquid tank 12 Hardener liquid tank 15 Supply device 16 Impregnation machine 18 Porous sheet supply roll 19 Molding passage

Claims (4)

A method for producing a long-fiber-reinforced foam molded product, comprising the steps of: continuously moving a fiber bundle formed by aligning a plurality of long fiber reinforcing materials in one direction in one direction while supplying a foamable resin composition to the moving fiber bundle; impregnating the fiber bundle with the supplied foamable resin composition to obtain a resin-impregnated fiber bundle; arranging porous sheets so as to sandwich the resin-impregnated fiber bundle at least above and below; and passing the resin-impregnated fiber bundle together with the porous sheets through a molding passage to foam and cure the foamable resin composition ,
The method for producing a long fiber reinforced foam molded product uses a porous sheet having an air permeability of 1.4 to 25.0 seconds as measured by the Gurley tester method defined in JIS P 8117 (2009) as the porous sheet. The method for producing a long fiber reinforced foamed molded article according to claim 1, wherein the foamable resin composition contains at least a polyol compound, a polyisocyanate compound, and a foaming agent. 3. The method for producing a long fiber reinforced foamed molded article according to claim 1, wherein the porous sheet has a thickness of 20 to 86 μm. The method for producing a long fiber reinforced foamed molding according to any one of claims 1 to 3, wherein the porous sheet is neutral paper or kraft paper.

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