JPS6392368A - Production of core material for surfboard or saleboard and material of core material used therein - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of manufacturing a core material for surfboards or sailboards made of synthetic resin foam, and a core material suitable for the manufacturing method.

[Prior Art] Conventionally, the following core materials for surfboards or sailboards made of synthetic resin foam are known.

(1) Hard polyurethane is injected and foamed into a hollow synthetic resin molded product in the shape of a surfboard or sailboard.

(2) A hard polyurethane foam molded product slightly larger than the product, cut with an electric plane, etc.

(3) A mold formed by foaming polystyrene beads in a core mold.

On the other hand, extruded foams are known as polystyrene foams in addition to bead foams such as (3). This extruded polystyrene foam is widely used as a heat insulating material for buildings, etc., but core materials for surfboards and sailboards made of extruded polystyrene foam have not hitherto existed.

[Problems to be Solved by the Invention] Incidentally, in surfboards and sailboards, it is important to reduce the weight of the core material because the lighter the board, the better the riding speed and controllability. However, synthetic resin foam has the property that its strength decreases when its weight is reduced, and its heavy sleeves increase when its strength is increased. It is insufficient to meet the requirements for strength.

In addition, the core material needs to not absorb water and become heavy even if the surface coating layer is scratched or damaged, but the core materials in (1) to (3) above are It is also insufficient to meet the demands of the government.

Furthermore, each of the core materials (1) to (3) described above also has the following problems.

In the case of the core material (1) above, there is a problem in the uniformity of physical properties because injection foaming tends to cause non-uniformity in the foaming state.

In the case of the core material (2) above, there is a problem that it is particularly heavy compared to other core materials.

In the case of the core material (3) above, since it is made of bead foam, it is not only inferior to the core materials (1) and (2) above in terms of strength, but also due to the cutting process after molding. When the bead fused portion is exposed, water easily enters and the water absorbency increases, and there is also a problem in that unevenness is likely to occur due to the infiltration of paint, and the design quality after surface painting is deteriorated.

On the other hand, extruded polystyrene foams have uniform cell diameters and an excellent balance between lightness and compressive strength, not only compared to polystyrene bead foams but also compared to rigid polyurethane foams. It has the advantage that it is easy to obtain and has almost no water absorption. Therefore, it is possible to manufacture the core material using this extruded polystyrene foam.

However, due to the manufacturing process, extruded polystyrene foams are all plate-shaped molded products, and it is impossible to manufacture irregular-shaped products by molding.

Therefore, the extruded polystyrene foam board is cut into a core material, but this has the following problems.

First, it is difficult to obtain an extruded polystyrene foam board with a thickness large enough to remove all the warpage from the front and back of the core material. Furthermore, even if such a thickness could be obtained, cutting out all the warpage at the front and back of the core material would be time consuming and wasteful of material, as in (2) above. It becomes.

Therefore, it is considered that the extruded polystyrene foam board is curved to form a warp in the front and back of the core material.

However, extruded polystyrene foam boards have strong rebound resilience against bending, and it is difficult to simply bend them. Even if this bending process were applied, it would take 70~2 to make a surfboard or sailboard.
A thickness of 0.00 mm is required, and materials with a thickness of about 20 to 50 mm, which are used as insulation materials for general construction, cannot be used as they are. In addition, as the thickness increases, hangnails are more likely to occur when cutting with an electric plane, etc., which is essential for forming the core material from extruded polystyrene foam, which cannot be molded. There is a problem that it becomes impossible to delete the file.

[Means for Solving the Problems] To explain the means for solving the problem in item 1, in the first invention, an extruded polystyrene foam board is bent and heated while being held. After that, the curvature is fixed by cooling it, and then it is cut into the shape of the core material.In the second invention, an extruded polystyrene foam board is cut into a flat core material, and this is The method is to fix the curvature by heating and cooling the curvature while holding it. Also,"
- Regarding the extruded polystyrene foam board used in the first and second inventions, in the second invention, the compressive strengths Cν and CHlC in each direction of thickness, width, and length, but the compressive strength in all directions CSt, 1M, has a relationship that satisfies the following formulas 1 to 2, and has an average cell diameter of 1.0 mm or more, a density of 20 to 40 kg/m'', and a thickness of 70 mm or more, 10
In the fourth invention, the extruded polystyrene foam board has a thickness of 100 mm or more and 200 m.
Measures have been taken to keep it below m.

CV/CSUM≧0.16 ・・−−■C++/
C5us≧0.16・・・・■CF/C5LI−≧0
．． 16 ・−・−■ The present invention will be further explained in detail.

To explain the first invention, the extruded polystyrene foam board used in the first invention has a shape that extends the warp of the core material to be manufactured, as well as one that is simply cut into an appropriate length after extrusion foaming. This includes rough-hewn shapes that define the outline of the shape.

The extruded polystyrene foam board as used in the present invention refers to a board made by continuously extruding and foaming a polystyrene synthetic resin containing a foaming agent, and cutting the foam into a board shape. Here, the polystyrene-based synthetic resin is, for example, a homopolymer of styrene derivatives such as styrene, α-methylstyrene, chlorostyrene, dichlorostyrene, dimethylstyrene, t-butylstyrene, vinyltoluene, or two types thereof. It refers to a copolymer consisting of a combination of the above, or a copolymer of these styrene derivatives and a small amount of a compound that can be easily polymerized with another such as divinylbenzene, methyl methacrylate, acrylonitrile, or butadiene.

In the first invention, the extruded polystyrene foam board is held in curve by a pair of jigs 1a whose opposing surfaces are curved surfaces, as shown in FIG. 1, for example.

This can be done by sandwiching an extruded polystyrene foam board 2 between the lbs. Between both jigs la and lb, spacers 3 having a height approximately equal to the thickness of the extruded polystyrene foam board 2 are interposed at the four corners, so that excessive compressive force does not act on the extruded polystyrene foam board 2. It looks like this.

As shown in FIG. 2, if a large number of curved plate-shaped jig ICs are stacked and an extruded polystyrene foam board 2 is sandwiched between each jig IC along with a spacer 3, -
A large number of extruded polystyrene foam boards 2 can be curved and held at the same time.

- The curvature of the marking jigs 1a, lb, and lc is preferably one that can shape the extruded polymethylene foam board 2 into a curvature that approximately corresponds to the front-to-back curvature required for the core material to be manufactured. Also,
The amount of warpage δ1 of the jigs 1a, lb, and lc (see Figure 1) and the amount of warpage δ2 (see Figure 3) formed on the extruded polystyrene foam board 2 by heating and cooling (described later) are δ
62 tends to be slightly smaller than 1, so taking this into consideration, the amount of warpage δ1 of jigs 1a, lb, and lc is slightly larger than the amount of warpage from the front and back required for the core material to be manufactured. It is preferable to keep it.

In the first invention, the extruded polystyrene foam board 2 held in a curved manner as described above is heated to soften it while maintaining the curve, and then cooled to form the extruded polystyrene foam board 2. Shape the warp. If the curvature retention is canceled before the curvature is fixed by heating, the curvature will normally occur within the bending elasticity range of the extruded polystyrene foam board 2, so the extruded polystyrene foam board 2 will return to its elastic state. This makes it impossible to form the necessary warp. Furthermore, if the curvature retention is canceled after heating and before cooling, part of the warp of the extruded polystyrene foam board 2 will return, making it difficult to form the desired warp.

1. It is preferable to heat the extruded polystyrene foam board 2 which is kept curved at a temperature lower than the glass transition point of the polystyrene synthetic resin constituting the extruded polystyrene foam. If the heating temperature is low, the extruded polystyrene foam board 2 will not be sufficiently softened, and the warp will tend to return elastically when the curvature retention is released after cooling. In addition, foams made of non-grade polymers, such as extruded polystyrene foams, exhibit a clear glass transition point, and when heated above the glass transition point, their thermodynamic and physical properties change rapidly. However, the basic characteristics of the extruded polystyrene foam board 2 may be impaired due to shrinkage of the cells and a decrease in the volume of the foam.

It is sufficient that the heating is carried out for a time that allows the entire extruded polystyrene foam board 2 to be heated and softened almost uniformly.

This time varies somewhat depending on the thickness and heating temperature of the extruded polystyrene foam board 2, the material and thickness of the jigs 1a, lb, lc, etc., but usually 2 hours or more is sufficient.

Cooling after heating is sufficient as long as the extruded polystyrene foam board 2 is solidified to the extent that it is not easily deformed, but it is preferable to cool the entire board to about room temperature.

Further, this cooling may be performed by natural heat radiation or forced cooling such as by blowing cold air.

The cutting after cooling is usually performed using an electric planer or the like.

By this cutting, the necessary shape of the core material is formed, and any warping errors formed in the extruded polystyrene plate 2 can be corrected at this time.

In the second invention, whereas in the first invention, the extruded polystyrene foam board 2 is warped and then shaved, the flat core material is shaved and then warped. Shape.

Here, the term "flat core material" refers to a material having the same shape as the shape of the core material to be manufactured by extending the warp. In the second invention, the curvature retention and heating/cooling performed to shape the flat core material into a warp shape are performed in the same manner as in the first invention.

Next, the third and fourth inventions will be explained.

The orientation ratio of the compressive properties of the extruded polystyrene foam board defined in the third and fourth inventions provides an excellent machine for enabling the abrasion essential for manufacturing the core material from the extrusion polystyrene foam board. This is the only way to obtain the desired machinability. That is, the compressive strength in the thickness, width, and length directions CV, CH
lC[ is the sum of compressive strengths in all directions C5LIH, C
V/CSUM≧0.16, CHlCSUM≧0.16,
CF/CSUM≧0.16 (7) all satisfied, preferably Cu/CSUM≧0.20, CHlCsu-≧0.2
0, and CF/CsuM≧0.20.

The compressive strength here refers to the compressive strength at the yield point measured by the test method of JIS-A-9511. In addition, for foams that do not have a yield point, it refers to the compressive strength at 5% strain.

-F The third and fourth inventions specifying the orientation ratio of compression characteristics are based on the present inventors' understanding that 1. Mechanical machinability is influenced by the orientation ratio of the cells in the foam, and the orientation ratio of the cells is determined by the compression property. This was made based on the discovery that there is a close relationship between the characteristics and the orientation ratio.

According to the findings of the present inventors, in order to improve the mechanical machinability in three-dimensional directions, the orientation ratio of the bubbles should be set to 1:1:1 in each direction of thickness, width, and length, that is, isotropically. Ideally, it should be sexual. In addition, the orientation ratio of the bubbles has a close relationship with the orientation ratio of the compression characteristics, and when the orientation ratio of the compression characteristics is approximately uniform, the orientation ratio of the bubbles is also approximately uniform, and the orientation ratio of the compression characteristics is anisotropic. As the property increases, the anisotropy of the bubble orientation ratio also increases.

If any of the anisotropy ranges Cυ/C9IIM, CHlCSUM, or CF/C3lI11 is smaller than 0.16, hangnails are likely to occur during mechanical cutting using an electric planer, etc., and sagging with sandpaper, etc. This results in an increase in the amount of time and effort involved in the polishing process, an accompanying increase in costs, and an increase in the amount of paint applied during surface painting.

By the way, foam boards manufactured by extrusion differ from foam boards manufactured by in-mold foaming in that the foaming speed of the molten gel in three directions (thickness, width, and length directions) after leaving the gas orifice is limited. Generally, the vectors are not equal, resulting in anisotropy in the bubble orientation ratio. This tendency is shown in Figure 4(a).
As shown in the figure, when the foam board is relatively thin (approximately 20 to 50 mm), it is not very noticeable and has an almost isotropic structure. However, as shown in FIG. 4(b), as the thickness of the foam plate increases, the foaming speed vector intersection of the molten gel in the length direction decreases, and conversely, the foaming speed vector t in the thickness direction increases. Therefore, the bubbles become large ellipses in the thickness direction, and the anisotropy becomes strong.

In addition, in FIGS. 4(a) and (b), 4 is an extruder,
The flow of the molten gel is represented by a solid line.

In the present invention, in order to obtain the necessary strength, a fairly thick extruded polystyrene foam board is used.
It tends to have strong anisotropy. Therefore, in order to make the extruded polystyrene foam board used in the present invention as uniform as possible in the three directions, the foaming speed vector in the three directions is adjusted by increasing the amount of extrusion per unit time of the extruder. It is preferable to extrude and foam them as equally as possible.

In addition, extruded polystyrene foam board has a density of 20 to 40 kg/m3 in order to satisfy good buoyancy performance, compression resistance, and design when used as a core material. The average bubble diameter is 1.
It is necessary that it is 0 mm or less. Density is 40kg/
If the weight exceeds 20 m, there will be no advantage of weight reduction compared to existing hard polyurethane foam products, and the density will decrease to 20 m.
If it is less than kg/m3, it becomes difficult to obtain the compression resistance required as a core material.

The core material is usually reinforced on the surface with an FRP laminate and used in surfboards and sailboards to improve compression resistance against localized loads such as when the board is stepped on strongly or jumped during use. . However, the compression resistance of the core material and the F
The compression resistance of RP laminates has an approximately proportional relationship, and FRP
To prevent layer cracking, the compressive strength of the core material is approximately 1
．． It is necessary that it is 2 kg/cm2 or more.

By the way, the compressive strength and density of the foam are almost proportional to each other, and the above-mentioned condition that the density is 20 kg/m3 or more is also for obtaining the compressive strength indicated by L.

Furthermore, the average cell diameter of the extruded polystyrene foam board needs to be 1.0 mm or more F in order to prevent the weight from increasing due to an increase in the amount of surface coating paint and to improve the design.

[Function] According to the first and second inventions, the extruded polystyrene foam board or the flat core material cut from the foam board is heated and softened while maintaining the curve, thereby making it curve. The bending stress caused by this can be removed. Then, by cooling the extruded polystyrene foam board that has been heated and softened while maintaining its bending, the bending stress is removed, the bending is fixed, and the desired warp can be formed. be.

In the first invention, since the core material is shaved after shaping the warp, the warpage can be corrected later, and high precision is required to shape the warp into the extruded polystyrene foam board. There are advantages to not doing so.

The second invention has the advantage that it is easier to perform the work than cutting a flat core material or cutting a curved plate.

In the third and fourth inventions, during the mechanical cutting process essential for manufacturing the core material from the extruded polystyrene foam board,
Good machinability can be obtained.

[Example] Example 1 Using a jig as shown in FIG. 1, a warp was formed on an extruded polystyrene foam board having a thickness of 70 mm. The heating temperature after bending and holding with a jig is 506C ~
The temperature was changed every 10°C between 100°C, the amount of warpage δ2 after cooling was measured, and the ratio δ2/δ1 with the amount of warpage δ1 of the jig was calculated.

The results are shown in Figure 5. As is clear from Figure 5, 80
It can be seen that good warping is achieved between °C and 100 °C, and that residual stress is rapidly removed within this range.

Example 2. Comparative Example 1 Extruded polystyrene foam boards with different density, average cell diameter, CV, and CHlCF were used as samples, and mechanical cutting workability, lightness, compression resistance, and design were evaluated using the evaluation methods shown below. The results are shown in Table 1.

b) Mechanically cut the surface of the sample to a depth of about 1 mm using an electric planer.
The surface condition was examined when cutting at a cutting speed of about 20 cm/see. The judgment criteria are as follows.

× □Extreme hangnail condition, or one or more dents with a depth of 5 mm or more.

Δ □One or more depressions with a depth of 2mII+ or more and less than 5mm have occurred.

O□ One or more dents with a depth of less than 2 mm have occurred.

■ □ Almost no surface roughness.

rl) Lightness criteria is based on the existing rigid polyurethane foam (density 40-50K), as this application requires lightness as a buoyancy material.
The density of the foam was determined based on the density (g/m3) as shown below.

×　□　Density 45kg/l113 or more”2.

△ □ Density 35 kg/m3 or more - less than 145 kg/m.

O□ Density 25 kg/m" or more, less than 35 kg/+n".

■　□　Density less than 25kg/m3.

c) Compression resistance The compressive strength in the thickness direction of the sample was measured according to the method of JIS-A-9511 and judged as follows. (ij, l,,
The samples used were those that had been left for one month or more after manufacture.

×　□Compressive strength less than 1.2 kg/cm2.

Δ □Compressive strength 1.2kg/cm2 or more, 2.5kg
less than /cm2.

○ □Compressive strength 2.5kg/cm2 or more, 4.0kg/
Less than cm2.

■ □Compressive strength: 4kg/cm2 or more''-0 2) Design For this purpose, the common method is to paint the surface of the core material with water-soluble paint, and then laminate it with a transparent epoxy resin reinforced with glass cloth. From the viewpoint of design, the core material is required to have a small cell diameter.

× □ Bubble diameter 1.0mm or more.

Δ　□　Bubble diameter of 0.6 mm or more and less than 1.0 mm.

O□ Bubble diameter north of 0.4 mm, less than 0.6 mm.

■　□Bubble diameter less than 0.4mm.

e) Overall evaluation × □ If there is one or more × or two or more Δ.

Δ □ If there is no × or ■ item and there is one or more △.

When there is one or more items in which there is no term 1 with O□ ×, and all other items are O1 or 0.

■　□　If all items are O4■.

[Effects of the Invention] As explained above, according to the present invention, a core for surfboards or sailboards is produced using an extruded polystyrene foam board that is excellent in lightness, strength, non-water absorbency, and design but is easy to obtain. This makes it possible to manufacture surfboards or sailboards with excellent functionality at low cost by easily manufacturing materials without wasting materials.

[Brief explanation of the drawing]

Fig. 1 is an explanatory drawing showing an example of a method for bending and holding an extruded polystyrene foam board, Fig. 2 is an explanatory drawing showing another example of the same, and Fig. 3 is an extruded polystyrene foam board with a warp shape. FIGS. 4(a) and 4(b) are illustrations of the causes of anisotropy, and FIG. 5 is a graph showing the results of Example 1.

Claims (1)

[Claims] 1) The extruded polystyrene foam board is curved, heated and cooled while being held to fix the curve, and then cut into the shape of the core material. A method for manufacturing core material for surfboards or sailboards. 2) A core material for surfboards or sailboards, which is characterized by cutting an extruded polystyrene foam board into a flat core material, holding it in a curved state, heating it, and then cooling it to fix the curve. manufacturing method. 3) Compressive strength in each direction of thickness, width, and length C_V, C_H
, C_E has a relationship satisfying the following formulas (1) to (3) with respect to the sum of compressive strengths in all directions C_S_U_M, and the average cell diameter is 1.0 mm or less and the density is 20 to 40 kg/
m^3, a surfboard core material characterized by being an extruded polystyrene foam board having a thickness of 70 mm or more and less than 100 mm. C_V/C_S_U_M≧0.16 (1) C_H/C_S_U_M≧0.16 (2) C_E/C_S_U_M≧0.16 (3) 4) Thickness, width , compressive strength in each direction of length C_V, C_H
, C_E has a relationship satisfying the following formulas (1) to (3) with respect to the sum of compressive strengths in all directions C_S_U_M, and the average cell diameter is 1.0 mm or less and the density is 20 to 40 kg/
m^3, a material for a core material for a sailboard, characterized by being an extruded polystyrene foam board having a thickness of 100 mm or more and 200 mm or less. C_V/C_S_U_M≧0.16 (1) C_H/C_S_U_M≧0.16 (2) C_E/C_S_U_M≧0.16 (3)