KR20180093393A - Core for snadwich panel and sandwich panel including the same - Google Patents

Abstract

The present invention provides a core for a sandwich panel and a sandwich panel including the same. The core for a sandwich panel comprises: a sheath-core type polyester fiber; and a non-woven fiber including inorganic fiber.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a core material for a sandwich panel,

To a core material for a sandwich panel and a sandwich panel comprising the same.

In general, it is widely used in the fields of construction, automobile interior and exterior materials, etc., and is also used as a predetermined part such as a back cover of a display device.

Such sandwich panels are usually manufactured in consideration of the two properties of light weight and mechanical strength. For example, foamed resin, balsa wood, fiber reinforced plastic and the like are used as the core of the sandwich panel.

In the case of using the foamed resin among the above materials, the mechanical strength is weak, the stretching is hardly possible in the case of using the throwing wood, and the weight is excessively increased in the case of using the fiber reinforced plastic.

In one embodiment of the present invention, a core for a sandwich panel which is lightweight and excellent in mechanical strength is provided.

In another embodiment of the present invention, a sandwich panel having a light weight and excellent mechanical strength is provided.

However, the technical problem to be solved by the present invention is not limited to the above-mentioned problems, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.

In one embodiment of the invention, sheath-core type polyester fibers; And a nonwoven fabric containing inorganic fibers.

Further, in another embodiment of the present invention, there is provided a sandwich panel comprising the core for the sandwich panel.

The core material for the sandwich panel and the sandwich panel are lightweight and excellent in mechanical strength.

FIG. 1 is a photograph of a cross section of a core material for a sandwich panel according to an embodiment of the present invention taken by a scanning electron microscope (SEM).
2 is a schematic view schematically showing a cross section of a sandwich panel according to another embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

In the drawings, the thicknesses are enlarged to clearly indicate layers and regions. In the drawings, for the convenience of explanation, the thicknesses of some layers and regions are exaggerated.

Hereinafter, formation of an arbitrary structure in the upper part (or lower part) or the upper part (or lower part) of the substrate means not only that an arbitrary constitution is formed in contact with the upper surface (or lower surface) of the substrate, And any configuration formed on (or under) the substrate.

One embodiment of the present invention is a sheath-core type polyester-based fiber; And a nonwoven fabric containing inorganic fibers.

In general, sandwich panels are manufactured in consideration of two properties of light weight and mechanical strength, and as their core materials, for example, foamed resin, balsa wood, fiber reinforced plastic, honeycomb and the like are used.

Among the above materials, when foamed plastic is used, it is light in weight, but its mechanical strength is weak. In case of using blown wood, stretching is hardly possible, so it is difficult to make it as a molded product, and fiber reinforced plastic or honeycomb is used There is a problem that the mechanical strength is improved but the weight is excessively increased.

In addition, when the nonwoven fabric containing polypropylene fibers is used as a core material, its mechanical strength is also low.

Accordingly, in one embodiment of the present invention, the core material for a sandwich panel is formed of a nonwoven fabric to realize weight reduction, while the nonwoven fabric is a sheath-core type polyester fiber; And inorganic fibers, it is possible to effectively improve the mechanical strength and realize two properties of light weight and mechanical strength at the same time.

In one embodiment, the sheath-core type polyester-based fiber comprises a core part and a sheath part surrounding the core part, wherein the core part has a melting point of from about 180 캜 to about 300 캜 Based polyester fiber, and the sheath portion may include a low-melting-point polyester fiber having a melting point of from about 100 ° C to about 180 ° C. The sheath-core type polyester-based fiber may be referred to as a core-sheath type polyester-based fiber.

As described above, the core portion and the sheath portion include polyester fibers having different melting points, so that heat corresponding to the temperature range of the melting point of the sheath portion is applied so that the core portion is selectively melted .

Thereby, the sheath part of the polyester-based fiber can be selectively melted to bind the fibers without a separate adhesive, whereby the bonding force between the fibers can also be increased and the mechanical strength can be further improved.

Specifically, the high melting point polyester fiber may be a high melting point polyethylene terephthalate (PET) fiber, and the low melting point polyether fiber may be a low melting point polyethylene terephthalate (PET) fiber. have.

The inorganic fibers may include at least one selected from the group consisting of glass fibers, carbon fibers, metal fibers, natural fibers, and combinations thereof, for example. The natural fibers may comprise, for example, kenaf fibers.

FIG. 1 is a photograph of a cross section of a core material for a sandwich panel according to an embodiment of the present invention taken by a scanning electron microscope (SEM).

1, at least two or more fibers selected from the total fibers including the cis-core type polyester fiber 10 and the inorganic fibers 20 in the nonwoven fabric are bonded to each other, Thereby forming a portion 30. Accordingly, the nonwoven fabric including the nonwoven fabric may be lightweight due to the porous structure, while achieving high mechanical strength.

In addition, the nonwoven fabric may not include a separate matrix resin and a separate adhesive.

Specifically, at the time of formation of the nonwoven fabric, the sheath portion is melted by heat treatment so that at least two or more fibers selected from the whole fibers including the sheath-core type polyester fiber and the inorganic fibers in the non- Can be bonded.

That is, as described above, the sheath can be selectively melted by applying heat at a temperature falling within a temperature range of its melting point, whereby the shape of the core portion is maintained, More than one fiber may be connected to each other, and then the molten sheath may be cooled or dried to form a bonding portion between the two or more fibers to bond them together.

Thus, the melted sheath can serve as a kind of adhesive, so that the entire fibers contained in the nonwoven fabric can be selectively melted and cooled by the sheath portion without further comprising a separate matrix resin and a separate adhesive. They can be bonded to each other, thereby realizing more excellent environment friendliness.

For example, the heat treatment may be performed at a temperature of about 110 캜 to about 170 캜 for about 5 seconds to about 10 minutes, but is not limited thereto.

In one embodiment, the weight ratio of said cis-core type polyester fibers to said inorganic fibers may be from about 1: 0.8 to about 1: 1.2. By including them at the weight ratio within the above range, the mechanical strength can be effectively improved.

If the inorganic fibers are contained in an excessively small amount beyond the above-mentioned range, sufficient reinforcement may not be performed and the mechanical strength may be lowered. When the polyester fibers are contained in a small amount, The mechanical strength may be lowered.

The cis-core type polyester fibers and the inorganic fibers may each have an average diameter of from about 10 탆 to about 50 탆, for example, from about 8 탆 to about 20 탆. In addition, the sheath-core type polyester fibers and the inorganic fibers may each have an average fiber length of from about 3 mm to about 50 mm, for example, from about 6 mm to about 50 mm. The average diameter means the diameter of the cross section perpendicular to the longitudinal direction of the fiber.

When the average diameter and the average length of the cis-core type polyester fibers and the inorganic fibers satisfy the above range, appropriate physical connectivity can be ensured, and the porous structure of the nonwoven fabric can be easily formed.

The nonwoven fabric may be formed by a method known in the art without the use of a predetermined adhesive, and may be formed, for example, by thermal bonding, needle punching, spun bond, But are not limited to, at least one method selected from the group consisting of stitch bonds and combinations thereof.

The thermal bonding is a method of mixing fibers having a low melting point plasticity and then melting or melting the fibers with heat or pressure. The needle punching is a method of physically joining a web using a predetermined needle , The spunbond is a method of forming a web by spun plastic such as PP or PET and self-adhered by heat, and the stitch bond may mean a method of forming the fibers by spinning.

The nonwoven fabric may have a porosity of about 10% to about 70%. The porosity is a percentage of the volume occupied by the voids in the total volume of the nonwoven fabric. By having the porosity within the above range, it is possible to realize a sufficient level of mechanical strength required as a core material for a sandwich panel, while achieving sufficient weight reduction of the sandwich panel core material.

The nonwoven fabric may be a density of about 0.3g / cm ³ to about 1.0g / cm ^3. By having the density within the above range, the predetermined mechanical strength required as the core material for the sandwich panel can be easily satisfied without excessively increasing the weight of the core material for the sandwich panel.

The thickness of the nonwoven fabric can be from about 0.2 mm to about 5.0 mm, thereby achieving sufficient mechanical strength without excessively increasing the thickness of the core material for the sandwich panel.

2 is a schematic view schematically showing a cross section of a sandwich panel according to another embodiment of the present invention.

In another embodiment of the present invention, there is provided a sandwich panel comprising the core for the sandwich panel. The core for the sandwich panel is as described above in one embodiment.

As described above, the sandwich panel core material includes a nonwoven fabric suitably adjusted in porosity and density so that it can be suitably used in a sandwich panel, and the sandwich panel including the sandwich panel is lightweight and lightweight, Core type polyester fibers and inorganic fibers and has an advantage that the mechanical strength can be realized at a superior level.

The sandwich panel may further include a skin layer laminated on at least one side of the core material for the sandwich panel, and more specifically, a skin layer laminated on both sides of the core material for the sandwich panel.

The skin layer may include, for example, one selected from the group consisting of iron, stainless steel (SUS), aluminum, magnesium, copper, and combinations thereof. Specifically, the iron is included in the form of a steel sheet, (EGI), cold rolled steel (CR), galvanized steel (GI), and combinations thereof.

The thickness of the skin layer may be about 0.1 mm to about 1.0 mm. By having the thickness within the above range, the overall thickness of the sandwich panel can be reduced while maintaining the structural rigidity and strength at an excellent level without excessively increasing the total thickness of the sandwich panel.

In addition, the sandwich panel may further include an adhesive layer between the core and the skin layer. The core material and the skin layer can be attached via the adhesive layer.

The adhesive layer may be formed, for example, by applying an adhesive to one side of the core or the skin layer and drying it, but may be formed by any method known in the art, and is not particularly limited.

The adhesive layer may include, but is not limited to, at least one selected from the group consisting of, for example, a polyurethane-based adhesive, a (meth) acrylic adhesive, a silicone adhesive, an epoxy adhesive, a phenol adhesive, and combinations thereof.

The thickness of the adhesive layer may be from about 20 탆 to about 100 탆. By having a thickness within the above range, an excellent adhesive force can be realized without excessively increasing the total thickness of the sandwich panel, thereby effectively preventing desorption, peeling, and the like.

In other embodiments, the flexural strength of the sandwich panel may be from about 100 MPa to about 500 MPa. By having the strength within the above range, when an external load is applied to the sandwich panel, it can sufficiently withstand it, and the occurrence of deformation can be prevented.

The flexural rigidity of the sandwich panel may be about 160 GPa to about 200 GPa. By having the stiffness within the above range, when an external load is applied to the sandwich panel, it can sufficiently withstand it, and the occurrence of deformation can be effectively prevented.

The flexural strength and flexural rigidity can be measured according to the measurement conditions of ASTM C393.

Also, the sandwich panel may have a tensile strength of about 100 MPa to about 300 MPa as measured according to ASTM E8 measurement conditions. By having the tensile strength within the above range, the sandwich panel can be easily formed and the shape of the formed product can be firmly maintained.

Also, the sandwich panel may have a tensile elongation of from about 5% to about 30% as measured according to ASTM E8 measurement conditions. By having a tensile elongation in the above-mentioned range, excellent moldability can be realized, and a mold having a curved shape can be easily formed.

Hereinafter, specific embodiments of the present invention will be described. However, the embodiments described below are only intended to illustrate or explain the present invention, and the present invention should not be limited thereto.

Example  And Comparative Example

Example  One

A fiber-dispersed aqueous solution containing a cis-core type polyester fiber to glass fiber in a weight ratio of 1: 1 was prepared. Water was removed from the fiber-dispersed aqueous solution and dried at 150 캜 to produce a nonwoven fabric. The nonwoven fabric was cut into a size of 300 mm x 300 mm x 1 mm to prepare a core for a sandwich panel.

Specifically, the sheath-core type polyester fiber includes a core part and a sheath part which surrounds the core part, and the core part is made of a high-melting-point PET fiber having a melting point of 230 ° C. to 260 ° C. And the sheath portion includes low melting point PET fibers having a melting point of 150 캜 to 170 캜.

The non-woven fabric may further include a step of performing heat treatment at a temperature of 200 ° C for 10 minutes during the formation of the nonwoven fabric to selectively melt the sheath portion to form the sheath-core type polyester fiber and the inorganic fiber At least two or more fibers selected from the entire fibers were bonded to each other without a separate matrix resin and a separate adhesive.

Subsequently, a skin layer made of stainless steel (SUS) having a thickness of 0.4 mm was laminated on both sides of the sandwich panel core material through an adhesive layer including an epoxy adhesive to manufacture a sandwich panel.

Comparative Example  One

A nonwoven fabric was formed from the whole fibers containing polypropylene fiber to glass fiber in a weight ratio of 1: 1 by a wet process method, and the nonwoven fabric was cut into a size of 300 mm x 300 mm x 1 mm to prepare a core for a sandwich panel.

Specifically, an epoxy adhesive was used to bond at least two or more fibers selected from among all fibers including polypropylene fibers and glass fibers at the time of forming the nonwoven fabric.

Subsequently, a sandwich panel was produced under the same conditions and in the same manner as in Example 1, except that the core material for the sandwich panel was used.

Comparative Example  2

A sandwich panel was produced under the same conditions and in the same manner as in Example 1 except that a core material made of expanded polyethylene was used.

Experimental Example

The properties of the cores for each sandwich panel according to Example 1 and Comparative Examples 1 and 2 were evaluated and shown in the following Table 1, and the properties of each sandwich panel containing the cores were evaluated.

Assessment Methods

Experimental Example  1: density and porosity

For each sandwich panel core material according to Example 1 and Comparative Examples 1 and 2, a specimen having a size of 15 mm x 15 mm x 1 mm was prepared and then density was measured using an electronic specific gravity meter (VIBRA, DME-220E) . Then, porosity was derived from the density of each specimen by the following formula.

[General formula]

Porosity (%) = {1- (specimen density / raw material density)} x 100

Experimental Example  2: flexural strength and bending stiffness

The bending strength and flexural rigidity of each sandwich panel core material according to Example 1 and Comparative Examples 1 and 2 were measured according to ASTM C393 measurement conditions using a universal testing machine (INSTRON 5569A).

Density (g / cm3) Porosity (%) Example 1 0.67 52 Comparative Example 1 0.77 45 Comparative Example 2 0.15 89

Total thickness (mm) Flexural Test (ASTM C393) Flexural Strength (MPa) Flexural Stiffness (GPa) Example 1 1.8 270 167 Comparative Example 1 1.8 75 46 Comparative Example 2 1.8 211 154

  As shown in Table 1, the sandwich panel according to Example 1 exhibited excellent bending strength and bending rigidity due to improved bonding force between the fibers due to the sheath-core type core material.

On the other hand, in the sandwich panel according to Comparative Example 1, the bonding force between the fibers was relatively weak, the dispersion of the epoxy binder was not uniform, and the flexural strength and flexural rigidity were low. In addition, the sandwich panel according to Comparative Example 2 had a high porosity and a low density using a foamed foam as a core material, but the flexural strength and flexural rigidity were significantly low.

100: Sandwich panel
110: core material
120: skin layer
10: Sheath-core type polyester fiber
20: inorganic fiber
30:

Claims (17)

Sheath-core type polyester fibers; And a nonwoven fabric containing inorganic fibers.
The method according to claim 1,
Wherein the weight ratio of the sheath-core type polyester fiber to the inorganic fiber is 1: 0.8 to 1: 1.2.
The method according to claim 1,
And a binder portion formed by bonding at least two or more fibers selected from among the whole fibers including the cis-core type polyester fiber and the inorganic fibers in the nonwoven fabric to each other
Core for sandwich panels.
The method according to claim 1,
The nonwoven fabric may further comprise a matrix resin and a separate adhesive,
Core for sandwich panels.
The method according to claim 1,
Wherein the sheath-core type polyester-based fiber includes a core part and a sheath part surrounding the core part,
Wherein the core portion comprises a high-melting-point polyester fiber having a melting point of 180 ° C to 300 ° C, and the sheath portion includes a low-melting-point polyester fiber having a melting point of 100 ° C to 180 ° C
Core for sandwich panels.
6. The method of claim 5,
Wherein the sheath is melted by heat treatment in the process of forming the nonwoven fabric so that at least two or more fibers selected from the whole fibers including the cis-core type polyester fiber and the inorganic fiber in the nonwoven fabric are bonded to each other, Forming part
Core for sandwich panels.
6. The method of claim 5,
The heat treatment is carried out at 110 ° C to 170 ° C for 5 seconds to 10 minutes
Core for sandwich panels.
The method according to claim 1,
The nonwoven fabric may have a porosity of 10% to 70%
Core for sandwich panels.
The method according to claim 1,
The non-woven fabric is a density of 0.3g / cm ³ to 1.0g / cm ³
Core for sandwich panels.
The method according to claim 1,
Wherein the nonwoven fabric has a thickness of 0.2 mm to 5.0 mm
Core for sandwich panels.
The method according to claim 1,
Wherein the sheath-core type polyester fibers and the inorganic fibers each have an average cross-sectional diameter of 10 to 50 탆 and an average fiber length of 3 to 50 mm
Core for sandwich panels.
The method according to claim 1,
The nonwoven fabric may be formed by at least one method selected from the group including thermal bonding, needle punching, spun bond, stitch bond, and combinations thereof.
Core for sandwich panels.
A sandwich panel comprising a core for a sandwich panel according to any one of claims 1 to 12.
14. The method of claim 13,
A flexural strength of 100 MPa to 500 MPa and a flexural rigidity of 160 GPa to 200 GPa
Sandwich panels.
14. The method of claim 13,
Tensile elongation of 5% to 30%
Sandwich panels.
14. The method of claim 13,
And a skin layer laminated on at least one side of the core material for the sandwich panel.
17. The method of claim 16,
Wherein the skin layer comprises one selected from the group consisting of iron, stainless steel (SUS), aluminum, magnesium, copper, and combinations thereof
Sandwich panels.

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