JPH11329678A - Flat heater and its molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding method, keeping heaters embedded in composite layers and the respective layers in a strong state without peeling off from each other over a long period of time and enabling a good quality flat heater to be obtained by a simple process. SOLUTION: In this molding method, heaters 7, fiber sheets 4, separation layers 3, and foaming resin particles as well as a liquid mold resin, are placed in a mold, then the resin particles are caused to foam by heating them, volume expansion due to the foaming presses the heaters 7 and the fiber sheets 4 against inner surfaces of the mold and simultaneously the liquid resin infiltrates into the fiber sheets 4 via the separation layers 3 and oozes out from the fiber sheets 4, and a surface layer and a skin layer covering the surface layer are molded by curing the liquid resin while a core part is molded by foaming.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar heater mainly used for floor heating, indoor wall or partition wall heating, and a molding method thereof.

[0002]

2. Description of the Related Art In general, a planar heater used for floor heating or wall heating is provided with a soaking sheet, which is formed by lining a reinforcing material to maintain rigidity. As a backing material, put an outer shell with a foamed resin core wrapped in a woven cloth in a mold, place a soaking sheet and heater on the outer shell, then inject liquid resin and cure What you did. Alternatively, a foamed reinforcing material is formed by injecting a foamed resin into the center of an outer shell that has been hardened by impregnating a woven fabric with a liquid resin, and a foamed reinforcing material is formed, and a soaking sheet and a heater are bonded to the reinforcing material. Have been.

[0003]

In the above-mentioned reinforcing material, the molding process is diversified and the operation is complicated. In particular, when the liquid resin is poured into the mold, the pressure is required to permeate the resin into the woven fabric. However, it is necessary to take time to completely infiltrate, the production efficiency is low and the cost is high.In particular, during the step of injecting the liquid resin after placing the heat equalizing sheet and the heater, the heater is required. However, there are drawbacks such as that the pressure and the like are shifted from a predetermined position by pressure and wrinkles are generated.

[0004] The present invention has been made in view of the above-mentioned conventional problems, and it is easy to form the heater, the heater can be installed at a predetermined position, and the surface is formed with a smooth surface without wrinkles. An object of the present invention is to provide a heater and a molding method thereof.

[0005]

Means for Solving the Problems A solution according to the present invention is that a core portion is formed of expandable resin particles in a mixed resin containing expandable resin particles and a liquid molding resin, and at least the core portion is formed. On one side, a separation layer capable of passing only the liquid molding resin is interposed, and a surface layer portion including a heater and a fiber sheet is polymerized on the separation layer, and the liquid molding resin penetrates the surface layer portion through the separation layer. And a skin layer that covers at least the surface layer portion by curing the liquid molding resin that has oozed out from the surface layer portion.

It is preferable that a fibrous reinforcing material is mixed in the skin layer, and that a fibrous reinforcing material is mixed in the core.

The heater may be provided on the outer surface of the surface layer, in the case where the heater is provided in the surface layer, or between the separation layer and the surface layer. Most preferably, the heater is provided with a soaking sheet through which the liquid molding resin can pass.

The fiber sheet for forming the surface layer is preferably made of high-strength modulus fiber such as glass fiber, silicon carbide fiber, aramid fiber, polyaralate fiber, or polyolefin fiber alone or a mixed fiber thereof. In addition to the fibers of polyester fiber, polyamide fiber, viscose fiber, natural fiber,
Alternatively, asbestos or the like can be used. Each of the above fibers may be a short fiber or a long fiber, and may be a whisker, but a long fiber, particularly a continuous fiber, is most preferable.

The above-mentioned fiber is used as its structure, and is preferably a woven fabric such as a plain weave, a Sudare weave, a twill weave, a knitted fabric, a nonwoven fabric, a UD yarn (unidirectionally arranged filament), or a web. In addition, these forms are not limited to flat ones, and may be three-dimensional woven fabrics or three-dimensional knits. Short fibers or whiskers, such as silicon carbide whiskers, carbon whiskers, silicon oxide whiskers, etc., can be used as part of the web or nonwoven fabric, rather than as such.

[0010] The separating layer substantially blocks the function of passing through the foamable resin particles, which are thermally expanded by heating, of the mixed resin of the foamable resin particles and the liquid molding resin. The part having the function is constituted as a whole or a part, and in the case of a part, the remaining part is for blocking the passage of the liquid molding resin. Fiber sheets or porous sheets having a small particle size include woven fabrics, knitted fabrics, braids, nonwoven fabrics, and papers of various natural fibers, synthetic fibers, inorganic fibers, and the like. Further, as the porous sheet, a sheet or film having continuous pores, such as polyurethane, polystyrene or polypropylene foam sheet or a polyethylene film produced by stretching or extraction or coagulation method, or a porous membrane such as polysulfone is used. The aperture is selected in a range in which these do not pass according to the type and expandability of the expandable resin particles.

Further, as a material of the separation layer, a sheet having a small aperture such as glass fiber or aramid fiber having a function as a reinforcing material can be used. In this case, the separation layer itself can also be used as the fiber sheet constituting the surface layer. Further, a material having elasticity can be selected so as to easily conform to the shape of the molded article as the separation layer.

The separating layer may be composed of a part of a material that does not allow the liquid molding resin to pass therethrough. For example, a part made of a material having a separating function and a part having no separating function, that is, a liquid molding resin may be used. Can be bonded to a material that does not pass through, or a fiber sheet having a separating function or a part of a porous sheet in which openings are previously sealed with a resin, or a heat treatment such as a fiber sheet made of polypropylene fibers. If the material is made of a material, a material in which a part of the openings is sealed by a fusion treatment, and a material in which a film that does not pass through the liquid molding resin is pasted in a part may be used.

It is also possible to previously treat both the separation layer and the surface layer, or one of them, with a resin in the form of a prepreg.

Next, the soaking sheet may be any sheet having good heat conductivity, such as silver, aluminum, gold, copper, iron, or the like.
A group of metals, such as chromium, nickel, and titanium, which are formed in a foil or plate shape and have an open hole or are formed in a net shape are used.

[0015] The heater is preferably in a form having a small thickness, for example, a cord type, a ribbon type, a film type,
The heater is selected from a board-type or net-type heater, and these heaters are placed on the above-mentioned soaking sheet, for example, in the form of a sandwich, so that molding time is reduced and molding time is shortened. Can be planned.

The method of forming the above-mentioned sheet heater is as follows.
After laying a heater, a fiber sheet and a separation layer in the molding die, a mixed resin containing expandable resin particles and a liquid molding resin is injected onto the separation layer, and then heated to expand the expandable resin particles, Due to the volume expansion during the foaming, the heater and the fiber sheet are pressed against the inner surface of the molding die, and at the same time, the liquid molding resin penetrates into the fiber sheet through the separation layer and further exudes from the fiber sheet. It is characterized in that the surface layer and the skin layer are formed, and the core is formed by the foaming.

In the method for forming a sheet heater, it is preferable that a soaking sheet is additionally provided in addition to the heater.

It is preferable that a fibrous reinforcing material is provided in a portion of the mold where the core is formed, and then a mixed resin containing expandable resin particles and a liquid molding resin is injected.

Further, in a portion of the molding die where the core portion is molded,
In some cases, a mixed resin containing foamable resin particles impregnated with a fibrous reinforcing material and a liquid molding resin is injected.

The fibrous reinforcing material to be mixed into the skin layer and the core may be a fiber such as glass fiber, aramid fiber, polyester fiber, rayon or cotton. After processing into a bulky sheet that allows the expandable resin particles to move freely,
A continuous mat, a chopped strand mat, a punched cloth, or the like having a bulkiness of about 0.01 to 0.15 cm is advantageous. In addition, the bulkiness is a value obtained by fiber weight / density / thickness of the fiber structure.

The fibrous reinforcing material is a fibrous sheet such as a bulky woven fabric, a knitted fabric, a mat or a nonwoven fabric, which is basically composed of continuous filaments as described above, or is formed by shaping them. It is preferable that the short fibers are processed into a sheet or a shaped article by bonding short fibers with a small amount of an adhesive. As specific examples of this fibrous reinforcing material, in addition to so-called continuous strand mats in which continuous fibers are arranged, cutting cloths, and chopped strands cut to a length of several centimeters, processed into sheets using a small amount of binder Chopped strand mats, nonwoven fabrics of polyester fibers, and the like have the same function as the continuous fiber structure, and can be used in the same manner. The fibrous reinforcing material may be the same as the fibrous sheet constituting the surface layer.

When air bubbles are contained in the mixed resin containing the expandable resin particles and the liquid molding resin used in the present invention, voids and the like are generated in the skin portion, the surface layer portion, and the inside of the separation layer of the molded product. To prevent this, non-condensable gas such as air or nitrogen should not be included when mixing the expandable resin particles and the liquid molding resin. It is effective to remove and remove non-condensable gas such as gas.

The expandable resin particles in the mixed resin are those which expand when heated, have the function of expanding during the reaction curing of the liquid molding resin, and do not dissolve in the liquid molding resin. is there. In addition, foams are used in which foams are included in foamed particles, and foaming ratio when foamable resin particles are heated at normal pressure is increased by about 10% to 6 times. It is six times, but is not limited to this. Incidentally, as currently available expandable resin particles, the expandable resin particles usually expand about 20 to 70 times.

The average particle size of the expandable resin particles may be about 1 μm to 5 mm, but is preferably about 10 μm to 1 mm. Resin, polyurea, melamine resin, curable foams such as polyimide and its precursors, polyvinyl chloride, polyvinylidene chloride copolymer,
Polyacrylonitrile or its copolymer, polystyrene or polystyrene copolymer, polyethylene, polyolefin such as polypropylene, polyphenylene oxide or its copolymer or a mixture of polyphenylene oxide and polystyrene, polyamide, polycarbonate, polybutylene terephthalate or a copolymer thereof It is molded with a thermoplastic resin such as a united resin. For foaming of the expandable resin particles, any method such as a foaming agent decomposition method, a solvent diffusion method, a chemical reaction method, and a gas mixing method can be applied. Of these, a foaming agent decomposition method and a solvent air diffusion method are preferred.

Furthermore, polyacrylonitrile-based polymer particles containing low-boiling hydrocarbons that expand in volume as a gas by heating, particularly as foamable resin particles (expands several to several tens times in air). It is desirable to use Specific examples of the expandable resin particles as described above include “Expancel” manufactured by Nobel Corporation and “Matsumoto Microsphere” manufactured by Matsumoto Yushi Seiyaku Co., Ltd., and these can be used as they are. However, beads such as polyolefin and polystyrene can also be used as the expandable resin particles. The particle amount of the expandable resin particles is 0.5 to the total amount of the expandable resin particles and the liquid molding resin.
It is suitable to use in the range of １５15% by weight.

It is to be noted that non-expandable foaming resin particles which do not substantially expand in volume due to heating or the like can be mixed and used in the foaming resin particles used for the core portion. The non-expandable expandable resin particles must also not substantially pass through the separation layer.

Next, as long as the liquid molding resin shows fluidity at the time of molding, it may be any resin that is generally used as a molding resin. As the liquid molding resin, as a result of molding, the resin is cured by a polymerization reaction or a crosslinking reaction to become a solid resin. Specific examples of the liquid molding resin include an epoxy resin, a polyurethane resin, an unsaturated polyester resin, a polyvinyl ester resin, a polyimide resin, and a polyamide resin. Among these, epoxy resin, polyurethane resin, unsaturated polyester resin, and polyvinyl resin Ester resins are preferred. These liquid molding resins are usually used by combining a curing agent or a curing accelerator in a resin or a precursor thereof (for example, a raw material monomer), and the present invention similarly uses these in combination. Can be used.

Further, in order to increase the strength of the molded product, it is preferable to add short fibers such as carbon fibers, aramid fibers, silicon carbide, potassium titanate, and boron, and fibers shorter than 6 mm such as whiskers to the above-mentioned mixed resin. And a pigment or the like can be added as needed.

The amount of the mixed resin to be fed into the mold should be appropriately selected in consideration of the mixing ratio of the expandable resin particles and the volume expansion rate during heating. %
It is preferable to adjust so as to fall within the range.

When molding, the mold is preheated or
Alternatively, at room temperature, a fibrous reinforcing material is laid on the skin layer (bottom of the mold), then a soaking sheet and heater are installed, and then a fiber sheet as the surface layer is laid and separated. Laying the fiber sheet constituting the layer, then pouring the mixed resin, sealing and further heating the mold, the expandable resin particles expand and expand, and the expansion force causes the liquid molding resin to pass through the separation layer. It penetrates into the surface layer part, further oozes out, passes through the heat equalizing sheet and the heater, penetrates into the fibrous reinforcing material of the skin layer, and furthermore, by the expansion force due to foaming, the separation part, the surface layer part, the heat equalizing sheet and the heater When the entire surface of the skin layer is uniformly pressed against the inner surface of the molding die and the liquid molding resin is cured, the core, the separating portion, the surface layer, the soaking sheet and the heater, and the skin layer are integrally formed. , Yet it is those formed with uniform thickness layers. In general, the soaking sheet and the heater are molded so as to occupy about 80% or less of the total surface area of the molded article. It is preferable to impregnate the sheet with the liquid molding resin.

The soaking sheet and the heater may be provided on both sides. In this case, a separating part, a surface layer, a soaking sheet and a heater, and a skin layer are formed on both sides of the core. Thus, an upper mold and a lower mold may be used. However, when providing a soaking sheet and heater only on one side,
On the side where it is provided, it is incorporated in the same manner as described above, and on the side where it is not provided, the separation part, the surface layer part, and the skin layer are stacked and installed, the mixed resin is put in the lower mold, and the upper mold is covered. .

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to an embodiment.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A planar heater having the structure shown in FIG. 1 is formed. A core 2 formed of expandable resin particles and non-expandable expanded particles of a mixed resin is formed at the center of the planar heater 1. The upper and lower surfaces are covered with separating layers 3 and 3, and the outer surfaces of both separating layers 3 and 3 are provided with surface layers 5 and 5 made of a fiber sheet 4.
And skin layers 9 and 9 having fibrous reinforcing material 8 are provided on the outer surface and on the surface layer portion 5 where the heat equalizing sheet 6 and the heater 7 on the other surface are not provided. The liquid molding resin of the mixed resin permeates into each surface layer portion 5 and each separation layer 3 and is cured.

The following materials were used for the members applied to the examples. (1) Fiber reinforcing material 7 provided in skin layer 9 Filament mat (Surface mat) MF30 manufactured by Nitto Boss Co., Ltd. Weight = about 30 g / m2 (2) Heater 7 Silicon rubber-coated ryal heater φ2.0 ~ 2.
4mm Nissei Electric Fluorocarbon resin-coated hyflon heater About 1.0mm in diameter Nissei Electric (3) Heat equalizing sheet 6 Commercially available aluminum foil with many small holes or many slits . t = 0.05-0.06
mm (4) Fiber sheet 4 of surface layer 5 Glass mat CM6 manufactured by Asahi Fiberglass Co., Ltd.
05 Weight = approximately 600 g / m2 (5) Separation layer 3 Nonwoven fabric mainly composed of polyester RT manufactured by Unicell Corporation
(6) Expandable resin particles of mixed resin Matsumoto Microsphere T manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.
EM-8 Foaming temperature = 125 ° C (7) Non-expandable foam particles of the mixed resin Glass bubbles K-25 manufactured by Sumitomo 3M Limited (8) Liquid molding resin of the mixed resin Epoxy resin Dai Nippon Ink Co., Ltd. Made by Epicron 8
50 (9) Curing agent meta-xylene diamine manufactured by Mitsubishi Gas Chemical Co., Ltd. (10) Curing accelerator BF3 / MEA manufactured by Hashimoto Chemical Co., Ltd.

As a molding die, a pair of upper and lower dies is used.
As shown in the figure, the lower mold 10 has a cubic cavity, the size of which is 20 mm thick, and one side is 31 mm.
It has a square shape of 0 mm and has a pipe through which a heat medium flows so as to keep each mold at a constant temperature. It becomes the lid of.

Accordingly, a mixed resin liquid is prepared by mixing 100 parts by weight of the liquid molding resin, 12.9 parts by weight of the expandable resin particles, and 16.3 parts by weight of glass bubbles. This is called liquid A. Further, 17.0 parts by weight of the above curing agent,
Liquid B is obtained by mixing and dissolving 0.5 parts by weight of a curing accelerator.

Next, as shown in FIG.
0, a fibrous reinforcing material 8, a soaking sheet 6 and a heater 7, a fiber sheet 4 serving as a surface layer portion 5, and a separation layer 3,
Each is molded according to the dimensions of the cavity in advance and laid one after another. Meanwhile, the solution A was heated to 65 ° C.
The solution B is heated to 35 ° C., the two solutions A and B are mixed with each other, stirred for 60 seconds, then quickly poured onto the separation layer 3 in the cavity, and then the separation layer 3 is formed thereon. After the nonwoven fabric and the fiber sheet 4 to be the surface layer portion 5 are laid one on top of the other, the upper die 11 is put thereon and pressurized at 5 kg / cm 2. After holding for 15 minutes thereafter, the upper mold 11 is opened, and the formed sheet heater 1 is taken out.

The sheet heater 1 formed by the above-mentioned forming method had a thickness of 20 mm and a specific gravity of 0.5.

When the foaming resin particles are molded in a molding die, the liquid molding resin passes through the separation layer 3 and the surface layer 5 under the pressure at which the expandable resin particles expand in volume.
In the case of a cord heater as described above, the liquid molding resin passes through the layer provided with the heater without any problem, but in the case of a ribbon heater, a film heater, and a board heater, the passage is hindered. Therefore, in the case of a ribbon heater, a film heater, and a board heater, a plurality of sheets may be arranged with an interval therebetween. However, when the amount of the liquid molding resin exuded is small, there is a possibility that sufficient resin may not reach the skin layer 9. It is preferable to impregnate the liquid molding resin before placing the fibrous reinforcing material 8 of the skin layer 9 in the molding die.

Further, the heat equalizing sheet 6 may be formed by forming small holes or slits in the aluminum foil as described above.
Although the effect of soaking is the best, a metal net may be used. However, if the opening is large, the generated heat becomes unevenly distributed. Therefore, it is desirable to open the heat equalizing sheet 6 with a uniform distribution over the entire surface.

Further, the heater 7 and the heat equalizing sheet 6 may be provided with the heater 7 overlapping only on one side of the heat equalizing sheet 6 or may be provided on both sides of the heater 7.

[0042]

According to the planar heater of the present invention, of the mixed resin of the expandable resin particles and the liquid molding resin, the core portion is formed by the expandable resin particles, and the liquid molding resin is heated to the surface layer and the heat is uniformly heated. Since it is formed by penetrating and curing the sheet, heater and skin layer, the layers of each part are molded integrally, and it is robust without peeling off each layer even for long-term use Provided as a product.

Further, since the heater is buried so as not to penetrate moisture, it is electrically safe and can be applied to housing equipment and environmental equipment. For example, floor heating, wall heating, auxiliary heating It can be used in a wide range of fields, such as snow melting equipment, freezing prevention and dew condensation prevention.

According to the method of molding a planar heater according to the present invention, the liquid molding resin passes through the layers of each part due to the volume expansion action of the expandable resin particles, and the layers of each part are pressed against the inner surface of the mold. Therefore, no unevenness is generated in the layers of each part, and the heat equalizing sheet or the heater is formed with a uniform thickness without moving or shifting from a predetermined position and without generation of wrinkles. A planar heater having a smooth surface and a large area to a small area can be formed in a simple process with excellent quality.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing a part of a planar heater according to the present invention.

FIG. 2 is an enlarged sectional view of a part of the same showing a state during molding.

FIG. 3 is a perspective view showing an example of a heater to be used (a), (b), (c), (d), and (e).

FIG. 4 is a perspective view showing an example of a heat equalizing sheet to be used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Planar heater 2 Core part 3 Separation layer 4 Fiber sheet 5 Surface part 6 Heat equalizing sheet 7 Heater 8 Fiber reinforcement 9 Skin layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihiro Miyazawa 322-3 Futatsuka, Takaoka-shi, Toyama Prefecture Inside Takagi Seiko Co., Ltd.

Claims (14)

[Claims] 1. A core comprising foamable resin particles, a surface layer comprising a heater, a fiber sheet and a cured liquid molding resin on at least one surface of the core, and a separation layer interposed between the two parts. A sheet heater characterized by comprising: 2. The planar heater according to claim 1, wherein a surface portion is disposed on both sides of the core portion, and at least one of the surface portions includes a heater. 3. A mixed resin containing expandable resin particles and a liquid molding resin, wherein a core portion including the expandable resin particles is formed, and at least one surface of the core portion includes only the liquid molding resin. A separation layer that can pass through the liquid molding resin is provided, and the liquid molding resin penetrates through the separation layer into the surface layer portion including the heater and the fiber sheet and is cured, and the liquid molding resin that has further exuded from the surface layer portion is cured. A sheet heater, wherein a skin layer covering at least a surface layer portion is formed by the method. 4. The planar heater according to claim 3, wherein a fibrous reinforcing material is mixed in the skin layer. 5. The planar heater according to claim 3, wherein a fibrous reinforcing material is mixed in the core. 6. The surface according to claim 3, wherein the heater is provided on any one of an outer surface of the surface layer, an inside of the surface layer, and between the separation layer and the surface layer. heater. 7. The sheet heater according to claim 1, wherein a soaking sheet capable of passing a liquid molding resin is added to the heater. 8. A heater, a fiber sheet, a separation layer, expandable resin particles, and a liquid molding resin are placed in a molding die, and then heated to expand the expandable resin particles. Is pressed against the inner surface of the molding die, and at the same time, the liquid molding resin penetrates into the fiber sheet through the separation layer and further exudes from the fiber sheet to cover the surface layer portion and the surface layer portion by curing the liquid molding resin. A method for forming a sheet heater, comprising forming a skin layer and forming a core by foaming. 9. After laying a heater, a fiber sheet and a separation layer in a molding die, a mixed resin containing expandable resin particles and a liquid molding resin is injected into the separation layer and stored. A method for forming the sheet heater according to claim 8. 10. After laying a heater, a fiber sheet, and a separation layer in a molding die, a mixed resin containing expandable resin particles and a liquid molding resin is poured into the separation layer and stored therein. The method for forming a sheet heater according to claim 8 or 9, wherein a sheet is placed. 11. A fibrous reinforcing material is laid in a molding die before installing a heater.
The method for forming a sheet heater according to any one of claims 10 to 10. 12. The method for forming a sheet heater according to claim 8, wherein a soaking sheet is provided in addition to the heater. 13. A mixed resin containing expandable resin particles and a liquid molding resin after a fibrous reinforcing material is provided in a portion of the molding die where the core portion is molded. 13. The method for forming a sheet heater according to any one of claims 12 to 12. 14. A mixed resin containing foamable resin particles impregnated with a fibrous reinforcing material and a liquid molding resin is injected into a portion of the molding die where the core is molded. 14. The method for forming a planar heater according to any one of items 13 to 13.