JPH06335974A - Production of hollow pultrusion object - Google Patents

Abstract

PURPOSE:To enhance the quality of a hollow pultrusion object made or a thermosetting fiber reinforced resin (FRP) by increasing the strength of the hollow pultrusion molded object while increasing the pulling-out speed (molding speed) of the hollow pultrusion object to enhance the productivity. CONSTITUTION:In the production of a long fiber reinforced resin hollow pultrusion object due to a pultrusion method, the size of the cross section of the mandrel 3 in an outer mold 2 is changed at the part X corresponding to a position where the resin compound of the resin compound impregnated fiber base material drawn in from one end part of the outer mold 2 starts gelling. The cross section of the outer shape of the front part 3a of the mandrel 3 from the part A of the mandrel corresponding to one end part of the outer mold 2 to the part X corresponding to the gelling start position is set to the definite size almost equal to the cross section of the inner shape of a formed pultrusion molded object 11 and the cross section of the residual part 3b of the mandrel 3 from the part X corresponding to the gelling start position to the leading end of the mandrel is gradually reduced toward the drawing-out direction of the hollow pultrusion object 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber-reinforced resin hollow pultrusion molding by a pultrusion molding method.

[0002]

2. Description of the Related Art Conventionally, a hollow body made of fiber reinforced resin (FRP) has been widely used because it is lightweight and has a large bending strength. The production of such a hollow body by a pultrusion molding method, which is excellent for forming a long body, is disclosed in, for example, JP-A-4-105924 and is already known. According to this conventional method, a fibrous base material impregnated with a thermosetting resin composition is drawn into the gap between the outer mold and the mandrel from one end of the outer mold of the pultrusion molding machine to form the resin composition. It is heat-cured, and the fiber-reinforced resin hollow body is pulled out from the other end of the outer mold to produce a fiber-reinforced resin hollow pultruded body, but in the conventional method, the size of the cross section of the mandrel is the whole length of the mandrel. The cross section of the hollow pultruded molded article was substantially equal to the inner cross section of the hollow pultruded molded article.

[0003]

However, when the thermosetting resin is cured by heating in the pultrusion molding,
Since heat-curing shrinkage occurs in the resin, a mandrel having a substantially constant cross section over the entire length is used as in the conventional method, and when the drawing speed of the thermosetting resin-impregnated fiber base material is stopped, the mandrel and resin-impregnated fiber base material are removed. There was a problem that a very large pull-out force was required due to the contact resistance with. In addition, if molding is performed for a long time with the drawing speed of the resin-impregnated fiber base material stopped, the surface temperature of the mandrel will gradually increase, which will cause the heat-curing shrinkage of the resin to proceed further, and the thermosetting resin-impregnated fiber. There is a problem that it becomes more difficult to pull out the base material.

In general, when a solid body is manufactured by pultrusion, the drawing speed is about 1 m / min for a die having a length of 1 m. There was a problem that productivity could be poor because it could only be pulled out at about half the speed.

The object of the present invention is to solve the above-mentioned problems of the prior art, to significantly increase the molding speed, to improve the productivity, and to improve the quality of the hollow fiber-reinforced resin. It is an object to provide a method for producing a pultruded body.

[0006]

In order to achieve the above object, the present invention provides a fiber base material impregnated with a thermosetting resin composition from one end of an outer die of a die of a pultrusion molding machine. It is drawn into the gap between the outer mold and the mandrel, the thermosetting resin composition is cured while maintaining the mold inside at a predetermined temperature, and the hollow thermosetting resin-impregnated fiber base material is applied from the other end of the outer mold. Pull it out,
A method for continuously producing a long fiber-reinforced resin hollow pultrusion molding body, wherein the cross-sectional size of the mandrel in the outer die is
Resin compound impregnated from one end of the outer mold The resin mixture of the fibrous base material is changed from the mandrel corresponding to one end of the outer mold to gelation by changing the part corresponding to the position where gelation starts. The cross section of the outer shape of the mandrel front portion up to the start position corresponding portion is set to a constant size substantially equal to the cross section of the inner shape of the hollow pultruded body to be formed, and the outer shape of the mandrel remaining portion from the gel start position corresponding portion to the tip is formed. The gist is a method for producing a fiber-reinforced resin hollow pultruded article, which is characterized in that the cross section is gradually reduced in the drawing direction of the hollow pultruded article.

In the above, as the fiber base material, all continuous fibers usable for reinforcing the thermosetting resin can be used. Specific examples thereof include inorganic fibers such as glass fibers, carbon fibers and alumina fibers, and organic fibers such as aramid fibers and nylon fibers. As the continuous reinforcing fibers, roving-shaped and strand-shaped fibers made of continuous filaments having a diameter of 1 to several tens μm, or cloth-shaped or mat-shaped fibers are used. Further, the continuous reinforcing fibers may contain short reinforcing fibers.

The thermosetting resin is not particularly limited, and those which can be used in pultrusion molding can be adopted. Specifically, a thermosetting resin such as an unsaturated polyester resin, a vinyl ester (epoxy acrylate) resin, an epoxy resin, or a phenol resin is used, but the method of the present invention is an unsaturated that cures in a fast reaction system by a radical reaction. By applying to polyester resin and vinyl ester resin, the most excellent effect is exhibited. The thermosetting resin may be a lubricant, an antioxidant, an ultraviolet absorber, an additive such as a pigment, an inorganic filler, a processing aid, or a modifier for improving the adhesiveness with continuous reinforcing fibers. Agents and the like may be incorporated into the formulation.

The fiber base material may be impregnated with the thermosetting resin composition before it is drawn into the mold of the pultrusion molding machine, or may be impregnated in the mold. .

The die of the pultrusion molding machine comprises an outer die and a mandrel inserted therein, and the inner cross section of the opening end on the inlet side of the outer die has a size equal to the outer cross section of the hollow pultruded body. The cross section of the outer shape of the mandrel end portion on the inlet side has the same size as the cross section of the inner shape of the hollow pultrusion molding.

The outer mold has a length of 200 to 2000 mm, preferably 600 to 1500 mm, and the mandrel has a length of
The length is the same as or slightly shorter than the length of the outer mold. Here, if the length of the outer mold is less than 200 mm, the curing of the resin becomes insufficient, and if it exceeds 2000 mm, a very large drawing force is required even by the method of the present invention, which is not preferable.

In the present invention, the size of the cross section of the mandrel in the outer mold is set so that the resin compound impregnated with the resin compound impregnated from one end of the outer mold is gelled. The part corresponding to the start position is changed as a boundary.

That is, the cross section of the outer shape of the front portion of the mandrel from the mandrel portion corresponding to one end of the outer die to the portion corresponding to the gelation start position is substantially equal to the cross section of the inner shape of the hollow pultruded body to be formed. The size of the outer shape of the mandrel remaining portion from the portion corresponding to the gelation start position to the tip is gradually reduced in the drawing direction of the hollow pultrusion molding.

The rate of change in the cross-sectional shape of the outer shape of the remaining mandrel after the portion corresponding to the gelation start position depends on the expansion rate and shrinkage rate of the thermosetting resin used, but is usually 1 /
It is preferable to change the cross-section of the outer shape of the remaining mandrel so that it becomes gradually smaller in the drawing direction of the hollow pultruded body, so to speak, so that it is tapered so that it is about 1000 to 5/1000.

If the rate of change of the cross-sectional shape of the outer shape of the remaining mandrel is less than 1/1000, the effect of increasing the pultrusion molding rate cannot be expected, and the rate of change is 5/1.
If it exceeds 000, so-called voids are generated due to expansion during curing of the thermosetting resin, resulting in a decrease in strength of the hollow pultruded molded article or a decrease in inner dimensional accuracy of the hollow portion of the molded article. , Not preferable.

The inside of the mold is kept at a predetermined temperature in order to cure the resin compound. In this case, the mold temperature varies depending on the type of thermosetting resin, but normally,
The temperature is set to 100 ° C or higher, preferably 110 to 180 ° C. Here, if the temperature inside the mold is less than 100 ° C., the resin cannot be sufficiently cured, and if the temperature inside the mold exceeds 180 ° C., the curing shrinkage of the resin becomes too large and pull-out resistance increases. However, this is not preferable because the drawing speed is reduced.

Further, it is desirable to provide a cooling means and a heating means inside the mandrel in order to keep the mandrel at a predetermined temperature. In this case, specifically, when the mandrel temperature exceeds 140 ° C., the curing shrinkage of the resin increases, so it is desirable to keep the mandrel at a temperature of 140 ° C. or less. Here, for example, a heater is used as the heating means, and water or oil is used as the cooling means.

[0018]

In the above method for producing a fiber-reinforced resin hollow pultruded molded article, the size of the cross section of the mandrel in the outer die of the mold is set so that the resin compound-impregnated fiber base material drawn from one end of the outer die is used. The resin composition is changed with the part corresponding to the position where gelation starts as a boundary, and the cross section of the outer shape of the mandrel front part from the mandrel part corresponding to one end of the outer mold to the gelation start position corresponding part, The hollow pultruded body to be formed has a constant size substantially equal to the cross section of the inner shape, and the cross section of the outer shape of the remaining mandrel from the portion corresponding to the gelation start position to the tip is, for example, a rate of change of about 1/1000 to 5/1000. Thus, the hollow pultruded body is gradually made smaller (tapered) in the drawing direction.

This is because the resin composition with which the base material is impregnated starts to gel, and the hardening and swelling of the resin and the contraction of the cross section of the hollow part start, and the pull-out resistance of the hollow pultruded molded article is greatly increased. Is.

Therefore, the cross section of the outer shape of the front portion of the mandrel from the mandrel portion corresponding to one end of the outer mold to the portion corresponding to the gelation start position of the resin compound is constant because the pulling resistance does not increase before gelation. And the cross section of the outer shape of the remaining mandrel from the part corresponding to the gelation start position to the tip,
By making the hollow pultruded body gradually smaller in the drawing direction, the mandrel surface is allowed to escape from the internal shrinkage of the fiber base material containing the gelled resin mixture, and the contact resistance is made as small as possible. However, if the rate of change in the cross-sectional shape of the outer shape of the rest of the mandrel is too large, the dimensional accuracy of the hollow pultruded product will naturally decrease, or the inner surface will have irregularities, and the strength of the hollow pultruded product will decrease. To do.

Further, when the drawing speed of the hollow pultruded body is increased, the drawing resistance is increased and a large drawing force is required. This is because the clinging force (tightening force) to the mandrel of the resin-impregnated base material increases due to the curing shrinkage of the resin due to the gelation of the resin blend, and stress based on that increases, but when the drawing speed is stopped, Since the hugging interval (length) of the resin-impregnated base material on the mandrel becomes long, in other words, the surface area of the mandrel that receives the pressure ((tightening force)) generated by the curing shrinkage of the gelled resin increases, Withdrawal resistance increases and a large pulling force is required.

In this respect, according to the above method, the cross-section of the outer shape of the front portion of the mandrel from the mandrel portion corresponding to one end of the outer die to the portion corresponding to the gelation start position of the resin compound is pulled out before the gelation. Since there is no increase in the size of the gel, the cross section of the outer shape of the remaining mandrel from the portion corresponding to the gelation start position to the tip is gradually reduced in the drawing direction of the hollow pultruded body, and gelled. The mandrel surface is allowed to escape from the internal shrinkage of the fiber base material containing the resin mixture, and the contact resistance is made as small as possible. Therefore, the pressure ((tightening force) due to the hardening shrinkage of the gelled resin is relaxed, and as a result, the normal With the pulling force, it is possible to increase the drawing speed and perform high-speed molding.

[0023]

Embodiments of the present invention will now be described with reference to the drawings.

First, FIG. 2 shows a production line of a fiber-reinforced resin hollow pultrusion molding.

In the figure, glass fiber made of glass roving (# 4450) and continuous mat (# 450) was used as the fiber base material (10).

These glass fiber base materials (10) are placed in upper and lower three parts respectively.
Impregnation rollers (19) (1
Two upper and lower resin compound impregnating vats (9) having (9)
In each case as a three-layer laminate. Each bat (13)
In it, raw material 1 of unsaturated polyester resin based on isophthalic acid
A thermosetting resin composition consisting of 00 parts by weight and 1.0 part by weight of a curing agent, t-butylperoxybenzoate, was put in advance, and the resin composition was impregnated into the fiber base material (10).

Then, the fiber base material (1
0) through the guide (14) in the middle, and the die (1) of the pultrusion molding machine.
The outer mold (2) was drawn into the gap between the outer mold (2) and the mandrel (3) from the left end, and was wound around the mandrel (3) by the resin compound-impregnated fiber base material (10). Then, while maintaining the inside of the mold (1) at a predetermined temperature, the resin mixture is cured, and the thermosetting resin-impregnated fiber base material is pulled out from the right end of the outer mold (2) by a take-up machine (15), A long fiber-reinforced resin hollow pultrusion molding (11) was continuously manufactured.

Here, the length of the outer die (2) was 1200 mm, and the length of the mandrel (3) in the outer die (2) was 1000 mm.

Further, three plate heaters (16) are attached to the outer surface of the outer die (2) of the die (1) so that the temperature inside the die (1) is 110 ° C. in the front part and 155 ° C. in the middle part. , And the rear part 15
The mandrel (3) was kept at 140 ° C. by setting it to 0 ° C. and equipping the mandrel (3) with a cooling water pipe (17) and a heater (18) (see FIG. 1).

Fiber-reinforced resin hollow pultruded article after production (11)
Was sequentially cut into a length of 2000 mm by a cutter (not shown).

As shown in FIG. 3, the hollow pultruded body (11) has an outer diameter of 60 mm × 60 mm and a wall thickness of 6 mm, and the thermosetting property of the take-up machine (15) shown in FIG. The take-up capacity of the resin-impregnated fiber base material was 4 tons.

The mandrels (3) having the shapes shown in the following Examples 1 and 2 and Comparative Examples 1 to 4 were prepared, and the fiber-reinforced resin hollow pultrusion molding was performed using the respective mandrels (3). A body (11) was produced.

Example 1 As shown in FIG. 1, in this example, the cross-sectional size of the mandrel (3) in the outer mold (2) was adjusted by gelling the raw material mixture of the isophthalic acid-based unsaturated polyester resin. Outer mold to start
300 from the mandrel (A) corresponding to one end of (2)
The mandrel front part (3a) from the mandrel part (A) corresponding to one end of the outer mold (2) to the part corresponding to the gelation start position (X) is changed by changing the part (X) corresponding to the mm position as a boundary. The cross section of the outer shape of the hollow drawing molded body (11) is approximately equal to the internal cross section of 48 mm x 48 mm, and the mandrel residue (3b) from the gelation start position corresponding portion (X) to the tip is The cross section of the outer shape was gradually reduced in the drawing direction of the hollow pultrusion molded body (11) at a change rate of 2/1000.

Further, the drawing speed (molding speed) of the hollow pultruded molding (11) is 1500 mm / min, and the pulling force is 3.
It was 5 tons. In order to confirm the gel point, a thermocouple (not shown) was run together with the fiber base material (10) impregnated with the resin raw material mixture, and the curing reaction process of the resin raw material mixture was traced. The part (X) that shows the inflection point at a position 305 mm from the mandrel (A) corresponding to one end of the mold (2), and the position where the cross-sectional size of the mandrel (3) changes.
It was possible to confirm that gelation had occurred in the vicinity.

The glass fiber reinforced isophthalic acid-based unsaturated polyester resin hollow pultrusion molding (11) thus obtained had a product total length of 400 mm, which was measured according to JIS K7055.
In accordance with the point bending test method, span between fulcrums on both sides 1500
When the bending strength was measured by conducting a three-point bending test under conditions of mm, crosshead speed 10 mm / min, the glass fiber reinforced resin hollow pultrusion molding (11) had a bending strength of 450 MPa. The obtained results are shown in Table 1.

Example 2 This example is similar to Example 1 above, except that the outer mold is
300 from the mandrel (A) corresponding to one end of (2)
mm isophthalic acid-based unsaturated polyester resin compound is the boundary (X) corresponding to the position where gelation starts
The cross section of the outer shape of the remaining mandrel (3b) from the gelation start position corresponding portion (X) to the tip gradually decreases in the drawing direction of the hollow pultruded body (11) at a rate of 4/1000. I chose

Further, the drawing speed (molding speed) of the hollow pultruded molding (11) is 1500 mm / min, and the pulling force is 3.
It was 3 tons. Further, the glass fiber reinforced resin hollow pultrusion molded article (11) was subjected to the same bending test and the bending strength was measured.
(11) had a bending strength of 435 MPa.

Comparative Examples 1 to 4 For comparison, a mandrel (3) having the following shape different from the shape of the mandrel (3) of the present invention was used, and a fiber base material (10) and a thermosetting resin composition were used. Using the same material as that used in Example 1, a hollow pultruded body (11) was manufactured.

In Comparative Example 1, the mandrel inside the outer mold (2)
The size of the cross section of (3) is approximately equal to the cross section of the inner shape of the hollow pultruded body (11) over the entire length of the mandrel (3).
The size of mm × 48 mm was fixed.

As a result, the hollow pultruded molded article (11) had a drawing speed of 500 mm / min and a take-up force of 4.0 tons. Further, according to the result of the bending test, the glass fiber reinforced resin hollow pultrusion molding (11) had a bending strength of 445 MPa.

Next, in Comparative Example 2, as shown in FIG. 4, the size of the cross section of the mandrel (3) in the outer mold (2) was adjusted so that the above isophthalic acid-based unsaturated polyester resin mixture gelled. Corresponding to the one end of the outer mold (2) by changing the mandrel (A) corresponding to one end of the outer mold (2), which is farther than the starting part, from the mandrel (A) corresponding to a position of 500 mm, as a boundary. Hollow pultruded body to be formed with a cross section of the outer shape of the mandrel front portion (3a) from the mandrel portion (A) to the portion (Y)
The size is 48 mm × 48 mm, which is approximately equal to the cross section of the inner shape of (11), and the cross section of the outer shape of the mandrel remaining portion (3b) from the gelation start position corresponding portion (X) to the tip is at a rate of 2/1000. The hollow pultruded body (11) was made gradually smaller in the drawing direction.

As a result, the drawing speed of the hollow pultruded body (11) was not higher than 1000 mm / min, and when measured with a thermocouple, it was measured from the mandrel part (A) corresponding to one end of the outer mold (2). An inflection point was shown at a position of 200 mm, and it was confirmed that gelation had occurred.

In this case, the take-off force of the hollow pultruded body (11) was 4.0 ton. Further, according to the result of the bending test, the glass fiber reinforced resin hollow pultrusion molding (11) had a bending strength of 455 MPa.

In Comparative Example 3, as shown in FIG. 5, the size of the cross section of the mandrel (3) was changed from the mandrel portion (A) corresponding to one end of the outer mold (2) to the tip, A hollow pultruded molded article (1
It was set to gradually decrease in the drawing direction of 1).

As a result, the hollow pultruded molded article (11) had a drawing speed of 1500 mm / min and a take-up force as low as 3.0 tons, but the glass fiber-reinforced resin hollow pultruded molded article (11).
In the bending test of No. 3, only a bending strength of 300 MPa was obtained.

In Comparative Example 4, as shown in FIG. 6, in Comparative Example 1, the size of the cross section of the mandrel (3) was set to one end of the outer mold (2) as in the case of Example 1 above. It changes with the part (X) corresponding to the position of 300 mm from the corresponding mandrel part (A) as the boundary, but the part corresponding to the gelation start position (X)
The cross section of the outer shape of the remaining mandrel (3b) from the end to the tip is made gradually smaller in the drawing direction of the hollow pultrusion molded body (11) at a rate with a steep gradient of 1/100.

As a result, the drawing speed of the hollow pultruded molded article (11) was 1500 mm / min, and the pulling force was as low as 3.5 tons.
In the bending test of No. 3, only a bending strength of 350 MPa was obtained.

The results of Comparative Examples 1 to 4 are summarized in Table 1.

[0049]

[Table 1] As is clear from Table 1 above, according to the method of the present invention,
Set the size of the cross section of the mandrel (3) in the outer mold (2) to the mandrel part corresponding to one end of the outer mold (2) where the above isophthalic unsaturated polyester resin compound starts to gel.
Before the mandrel from the mandrel part (A) corresponding to one end of the outer mold (2) to the part corresponding to the gelation start position (X), the part (X) corresponding to the position (A) to 300 mm is changed. Hollow pultruded body to be formed with a cross section of the outer shape of the portion (3a)
The cross section of the inner shape of (11) is set to a constant size, and the remaining mandrel from the gelation start position corresponding part (X) to the tip (3
Change the cross section of b) to 2/1000 or 4/10
The pulling speed (molding speed) of the hollow pultruded molded body (11) is high and the pulling force is small by making the hollow pultruded molded body (11) gradually decrease in the ratio of 00. In addition, the obtained glass fiber-reinforced resin hollow pultrusion molding (11) had a sufficiently large bending strength.

On the other hand, according to the comparative example, when the drawing speed (molding speed) of the hollow pultrusion molding (11) is fast and the pulling force is small, the obtained glass fiber reinforced resin hollow pultrusion molding ( When the bending strength of (11) is low and the bending strength of the fiber-reinforced resin hollow pultrusion (11) is large, the drawing speed (molding speed) of the hollow pultrusion (11) is slow and The power increased and the productivity was poor.

[0051]

As described above, according to the present invention, the fibrous base material impregnated with the thermosetting resin composition is introduced into the space between the outer mold and the mandrel from one end of the outer mold of the pultrusion molding machine. To cure the thermosetting resin mixture while keeping the mold at a predetermined temperature, and pull out the hollow thermosetting resin-impregnated fiber base material from the other end of the outer mold to strengthen the long fiber. A method for continuously producing a hollow resin pultruded body, wherein the cross-sectional size of the mandrel in the outer die is a resin blend impregnated with a resin blend impregnated from one end of the outer die. The hollow pultruded body is formed by changing the portion corresponding to the position where the gelation is started as a boundary, and changing the outer shape of the mandrel from the mandrel portion corresponding to one end of the outer mold to the portion corresponding to the gelation start position. The cross section of the internal shape of Since the cross section of the outer shape of the remaining portion of the mandrel from the corresponding portion to the tip is made gradually smaller in the drawing direction of the hollow pultrusion molded article, according to the method of the present invention, a fiber containing a gelled resin mixture is formed. The mandrel surface is released from the internal shrinkage of the base material, and the contact resistance is reduced, so the pressure (tightening force) due to the curing shrinkage of the gelling resin is relieved, and as a result, the normal take-up force. Thus, the drawing speed (molding speed) of the fiber-reinforced thermosetting resin hollow pultrusion molding can be significantly increased, the productivity can be improved, and the obtained fiber-reinforced resin hollow pultrusion molding is The bending strength is great and the quality is very good.

[Brief description of drawings]

FIG. 1 is an enlarged vertical sectional view showing an example of a die of a pultrusion molding machine for carrying out the method of the present invention.

FIG. 2 is a schematic side view of a hollow pultrusion molding production line for carrying out the method of the present invention.

FIG. 3 is a partially enlarged perspective view of a fiber-reinforced resin hollow pultrusion molded article manufactured by the method of the present invention.

FIG. 4 is an enlarged vertical sectional view showing an example of a die of a pultrusion molding machine for carrying out the method of Comparative Example 2.

5 is an enlarged vertical cross-sectional view showing an example of a die of a pultrusion molding machine for carrying out the method of Comparative Example 3. FIG.

FIG. 6 is an enlarged vertical sectional view showing an example of a die of a pultrusion molding machine for carrying out the method of Comparative Example 4.

[Explanation of symbols]

1 Mold 2 Outer Mold 3 Mandrel A Mandrel Part Corresponding to One End of Outer Mold X Mandrel Part Corresponding to Gelation Start Position of Resin Blend 3a Mandrel Front 3b Mandrel Remaining 10 Fiber Substrate (Glass Fiber) 11 Fiber Reinforced resin hollow pultrusion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Minoru Minoru Minoru 112 Mibugawa, Toyo City, Ehime Prefecture

Claims (1)

[Claims] 1. A fibrous base material impregnated with a thermosetting resin composition.
(10) is drawn into the gap between the outer die (2) and the mandrel (3) from one end of the outer die (2) of the die (1) of the pultrusion molding machine, and the inside of the die (1) is drawn. While maintaining the temperature, the thermosetting resin mixture is cured, and the hollow thermosetting resin-impregnated fiber base material (10) is pulled out from the other end of the outer mold (2) to form a long fiber-reinforced resin hollow A method for continuously producing a pultruded body (11), wherein the cross-sectional size of the mandrel (3) in the outer die (2) is set to the outer die (2).
Resin compound impregnated fiber base material drawn from one end of the (10)
The part corresponding to the position where the resin compound of starts gelation
Change from the mandrel (A) corresponding to one end of the outer mold (2) to the gelation start position corresponding to the gelation start position (X).
The cross section of the outer shape of the front part of the mandrel (3a) up to a constant size that is approximately equal to the cross section of the inner shape of the hollow pultruded body (11) to be formed, from the gelation start position corresponding portion (X) to the tip A method for producing a fiber-reinforced resin hollow pultruded body, characterized in that the cross section of the outer shape of the remaining mandrel (3b) is gradually reduced in the drawing direction of the hollow pultruded body (11).