JPH0365789B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a lightweight and high-performance base material for honeycomb cores that has excellent corrosion resistance, water resistance, and moisture resistance. The base material for honeycomb core obtained by the present invention has water resistance,
Not only moisture resistance but also mechanical strength, heat resistance,
It has excellent properties to prevent adhesives and other resins from bleeding out, and is lightweight and inexpensive, so it can be used for structural materials such as aircraft parts, train parts, building materials, ship parts, drafting board parts, ski parts, and rectification of open show cases. It is ideal for honeycomb cores used in non-structural materials such as plates, straightening plates for spinning tubes, Luhr materials for lighting, and cushioning materials for press machines. <Conventional technology> Conventional honeycomb cores include aluminum foil,
Materials based on kraft paper and the like have been used. For example, honeycomb cores made of aluminum foil have a high level of strength and are used in aircraft components. However, there has been a demand for a higher degree of weight reduction and strength and reliability in the components of such aircraft, etc., and there has been a desire for the development of even lighter and stronger honeycomb cores. On the other hand, honeycomb cores based on kraft paper are also lightweight and inexpensive, but lack mechanical strength and undergo large dimensional changes due to humidity. It also has drawbacks such as low corrosion resistance. Honeycomb cores using so-called Nomex paper (trade name) as a base material have come to be used as a lightweight and thermally more stable base material. That is, the base material is synthetic paper made into a sheet by mixing polymethaphenylene isophthalamide fiber and polymetaphenylene isophthalamide pulp, but because the material itself is expensive, it is not suitable for special fields such as aircraft. It is only used in a limited number of areas and has not been used in a wider range of fields. <Object of the invention> The object of the invention is to overcome these drawbacks. In other words, it is lightweight, highly strong, and heat resistant.
An object of the present invention is to provide a base material for a honeycomb core that is excellent in moisture resistance, water resistance, and corrosion resistance and is inexpensive. <Structure of the invention> That is, the present invention has a porosity of 60% or less and an air permeability of 60% or less.
A honeycomb core base material made of polyester paper of 100sec/100ml or more, containing 80 to 20% by weight of one or more short polyester fibers selected from the group consisting of stretched polyester staple fibers, unstretched polyester staple fibers, and low melting point polyester staple fibers. The present invention relates to a method for manufacturing a base material for a honeycomb core, which comprises mixing 20 to 80% by weight of fibers, wet paper-making, and then hot-pressing processing. In the present invention, the porosity is a value calculated from the following formula by measuring the thickness (cm) of polyester paper using a Pico stock thickness meter based on JIS P-8118. Porosity (%) = {1-Weight (g/cm ² )/10 ⁴ × Thickness (
cm) x (true density of polyester paper (g/cm ³ ))} x 100
Furthermore, air permeability is a value indicating the average number of seconds required for 100 ml of air to pass through a 78.54 mm ² area of polyester paper based on JIS P-8117. When manufacturing a honeycomb core, it is necessary to laminate the above-mentioned polyester papers and then stretch them. That is, adhesive is coated in stripes on polyester paper so as to have a predetermined cell size.
(Japanese Patent Laid-Open No. 53-134075, etc.), the coated sheets are stacked one on top of the other with a half-pitch shift, and then hot pressed to obtain an unrolled material. Then, the core is cut to a predetermined thickness and expanded (for example, JP-A-53
129267), a fixed honeycomb core can be obtained by coating or impregnating a curable resin at the honeycomb-shaped portion and then subjecting it to heat treatment. The honeycomb core base material of the present invention has a porosity of 60% or less, preferably 50% or less, and an air permeability of 100 sec/100 ml or more, preferably 600 sec/100 ml or more. Porosity exceeds 60% and air permeability is 100sec/
If it is less than 100ml, there will be many holes in the paper structure, and many of these holes will connect the front and back sides of the paper, and the adhesive applied when creating the honeycomb core will get stuck on the back side of the paper. When removing and hot press bonding, parts that should not be bonded will be bonded. As the adhesive to be applied when creating the honeycomb core, resins such as epoxy, phenol, polyimide, and polyamideimide can be used. Furthermore, as the curable resin used to fix the honeycomb core, epoxy-based, phenol-based, polyimide-based, polyamide-imide-based, and other resins can be used.
In addition, various stabilizers, flame retardants, etc. may be added to the base material of the third component to the extent that the purpose of the present invention is not impaired.
It may be added in an amount of 15% by weight or more. When the porosity is 60% or less and the air permeability is less than 100sec/100ml,
Although there are not so many holes in the paper structure, there is a high probability that these holes communicate between the front and back sides of the paper. Therefore, the adhesive applied when creating the honeycomb core often oozes out to the back side of the paper, and when it is hot press bonded, it adheres to areas that should not be bonded. Furthermore, the thermosetting resin that fixes the honeycomb core tends to penetrate into the inside of the paper, and as a result, the impact energy absorption effect of the obtained honeycomb core is likely to be impaired. Porosity exceeds 60% and air permeability is 100 seconds/100ml
In this case, although there are many holes in the paper structure, many of these holes do not connect the front and back sides of the paper, but are isolated inside the paper, on the front surface, or on the back surface of the paper. Therefore, the adhesive applied when creating the honeycomb core does not seep out to the back side of the paper, and furthermore, the thermosetting resin that fixes the honeycomb core does not penetrate into the paper. However, since the voids are high, the paper strength decreases and the compressive strength as a honeycomb core becomes insufficient. In the present invention, polyesters include aromatic dicarboxylic acids such as isophthalic acid, terephthalic acid, diphenyldicarboxylic acid, and naphthalene dicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, and decanedicarboxylic acid, or hexahydroterephthalic acid. The dibasic acid component is an aliphatic dicarboxylic acid such as ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, decamethylene glycol,
These are polyesters whose glycol components are aliphatic, alicyclic or aromatic glycols such as diethylene glycol, 2,2-dimethylpropanediol, hexahydroxylylene glycol and xylylene glycol, or polyoxyalkylene glycols such as polyethylene glycol.
It may be a copolymerized polyester containing one type or a combination of two or more of these dibasic acid components or glycol components. Particularly preferred examples include polyethylene terephthalate, poitetramethylene terephthalate, polytrimethylene terephthalate, and US Pat. Nos. 3,763,109 and 3,023,192.
Polyester elastomers described in Japanese Patent Application Publication No. 3651014 or Japanese Publication No. 3766146 may also be used. Furthermore, plasticizers, thickeners, and the like may be added to the polymer to increase plasticity and melt viscosity.
Furthermore, light stabilizers, pigments, heat stabilizers, flame retardants, aggregates, matting agents, etc., which are usually used as additives for fibers, may be added. In the present invention, drawn polyester short fibers have birefringence (Δn) exceeding 0.03. on the other hand,
Undrawn polyester staple fibers refer to fibers with a birefringence of 0.03 or less, and refer to fibers that have undergone a spinning process but have not undergone a stretching process. If the birefringence is 0.03 or less, undrawn oriented yarn obtained by high-speed spinning may be used. Here, birefringence uses a sodium light source,
It is determined by inserting a Berek compensator into the optical path of a polarizing microscope and measuring in α-bromnaphthalene. In the present invention, low melting point polyester short fibers are fibers that are drawn polyester short fibers, or drawn polyester short fibers and undrawn polyester short fibers are thermally fused at a temperature that is at least 20°C lower than the melting temperature of undrawn polyester short fibers. . As such a low melting point polyester fiber, a copolymerized polyester containing one or a combination of two or more of the dibasic acid component or glycol component described above can be used. Further, its form may be any of the all-melting type, core-sheath type, side-by-side type, etc. The honeycomb core base material of the present invention has different physical properties depending on the blending ratio of the stretched polyester staple fibers, the unstretched polyester staple fibers, and the low melting point polyester staple fibers that constitute the polyester paper.
If the drawn polyester short fibers exceed 80% by weight, the ratio of undrawn polyester short fibers and/or low melting point polyester short fibers as a binder component will be less than 20% by weight, resulting in a fabric that does not develop strength and has a lot of fluff on the surface. It is extremely difficult to create a paper structure with a porosity of 60% or less and an air permeability of 100 sec/100 ml or more. On the other hand, if the drawn polyester short fibers are less than 20% by weight, the ratio of undrawn polyester short fibers and/or low melting point polyester short fibers as a binder component will be 80% by weight or more, which will also result in poor strength and heat-resistant dimensional stability. This results in poor properties and the heat resistance of polyester cannot be fully utilized. Therefore, a good range of stretched polyester staple fibers is 80 to 20% by weight. The weight ratio of the undrawn polyester short fibers and the low melting point polyester short fibers, which are binder components, is determined by the weight ratio of the drawn polyester short fibers. In this case, the binder component may be either undrawn short polyester fibers alone, low melting point polyester short fibers alone, or a combination of undrawn polyester short fibers and low melting point polyester short fibers.
In the case of coexistence, any weight ratio may be used. That is, the undrawn polyester short fibers or 1 and low melting point polyester short fibers are in the range of 20 to 80% by weight. Stretched polyester staple fibers and/or unstretched polyester staple fibers and/or
Alternatively, the low melting point polyester short fibers preferably have a fiber diameter of 1 to 25 μm and a fiber length of 1 to 20 mm. When the fiber diameter exceeds 25 μm, the strength of the paper obtained decreases. If the fiber diameter is less than 1 μm, the tear strength of the resulting paper will decrease. On the other hand, if the fiber length exceeds 20 mm, the resulting paper will have poor texture and the orientation of the fibers in the direction of the paper machine will become too high, resulting in a decrease in dimensional stability. When the fiber length is less than 1 mm, the resulting paper has extremely low tensile strength and tear strength. The paper of the present invention is made by using a conventional wet paper making method, that is, a cylinder method, a Fourdrinier method, or
It is obtained by making paper using a short screen paper machine or the like and then subjecting it to hot pressure processing. During papermaking, it is desirable to use a thickener, particularly an anionic thickener, in order to improve the dispersibility of raw material fibers and improve the texture of the resulting paper. Conventionally known methods may be used for hot-pressing processing, but for example, when using a hot-pressing roll, the roll surface temperature is 190 to 240°C, preferably 200 to 230°C, and the processing speed is 0.5 m/min or more, preferably 3 m/min. /min or more, and the linear pressure is preferably 10Kg/cm or more, preferably 50Kg/cm or more. The base material for the honeycomb core according to the present invention is 80 to 20% by weight of stretched polyester staple fibers and 20 to 80% by weight of one or more staple fibers selected from the group consisting of unstretched polyester staple fibers and low-melting point polyester staple fibers.
By mixing and wet paper-making, applying heat-pressing processing, and further applying resin processing, it is possible to obtain a paper structure with a porosity of 60% or less and an air permeability of 600 seconds/100ml or more. In this case, the resins include polyolefins such as polyethylene, polystyrene, and polybutene, acrylics such as polyacrylates and polymethacrylates, polyesters, nitrocellulose, cellulose acetate, rosin, rosin ester, and ketone. , alkyd-based, urea-based, phenol-based, melamine-based, urea-based, epoxy-based, terpene-based, and other resins can be used. Generally, it is preferable to select resins of the same type or a combination of resins with good adhesion. On the other hand, impregnation methods, spraying methods, coating methods, and the like can be used as methods for incorporating resin, but all of them require drying and curing steps. In the present invention, when wet paper-making is performed by mixing drawn polyester short fibers, undrawn polyester short fibers, and low-melting point polyester short fibers, wood pulp or other polymer pulp-like substances, mica, kaolin, talc, etc. , inorganic particles such as glass flakes can also be added internally.
These additives are effective as impregnating agents and fillers to strengthen the paper structure used as a base material for honeycomb cores. The base material for a honeycomb core of the present invention may be subjected to paper-making and hot-pressure processing after addition of these additives, or may be subjected to paper-making and hot-pressure processing after addition of the additives, and further resin-processed. Furthermore, the base material for the honeycomb core of the present invention may contain other short fibers as necessary, such as polypropylene fibers, polyethylene fibers, polytetrafluoroethylene fibers, polycarbonate fibers, poly(2,6-diphenyl-para-phenylene oxide). fiber,
Polyamide fibers (including aromatic polyamide fibers), polyacrylonitrile fibers, polyvinyl alcohol fibers, aromatic polyamideimide fibers, aromatic polyimide fibers, polyvinyl chloride fibers, glass fibers, mineral wool, asbestos, Metal fibers, inorganic fibers such as potassium titanate fibers, regenerated cellulose fibers (viscose rayon, Kyupura, etc.),
Protein-based regenerated fibers can be mixed into the paper. Generally aromatic polyamide fiber, aromatic polyamideimide fiber, aromatic polyimide fiber,
Aromatic polyester fibers, poly(2,6-diphenyl-para-phenylene oxide) fibers, and the like are particularly useful in manufacturing honeycomb cores that require heat resistance. Inorganic fibers such as glass fibers, carbon fibers, alumina fibers, mineral wool, and asbestos-kaolin fibers are useful in manufacturing honeycomb cores that require heat resistance, flame retardancy, and heat insulation properties. <Effects of the Invention> The honeycomb core using the base material of the present invention is lighter than the conventional honeycomb core using aluminum foil as the base material, and has high compressive elastic recovery properties, so when used as a current plate, etc. It has the advantage of being less deformed by impact. In addition, compared to honeycomb cores based on kraft paper, it has higher mechanical strength, especially moisture resistance, water resistance, dimensional stability,
It has the advantage of high corrosion resistance. Furthermore, since it is cheaper than a honeycomb core based on Nomex paper (trade name), it is expected to be used in a wide range of fields. Since the base material for the honeycomb core of the present invention is polyester paper, it is lightweight and has high strength, and is also heat resistant.
It has excellent moisture resistance, water resistance, corrosion resistance, and is inexpensive. Furthermore, because the paper structure is dense and high density,
There is no trouble caused by the adhesive seeping out, and the resin for fixing the honeycomb does not penetrate into the paper, so it has a great impact energy absorption effect. <Example> In the following Examples and Comparative Examples, each characteristic was measured by the following method. Resin adhesion amount: This is the adhesion amount (weight %) of resin after curing on polyester paper after calendar processing. Porosity: Based on JIS P-8118, the thickness (cm) of polyester paper was measured using a Pico stock thickness meter and calculated from the following formula. Porosity (%) = {1-Weight (g/cm ² )/10 ⁴ × Thickness (
cm) x (true density of polyester paper (g/cm ³ ))} x 1
00 In this case, the true specific gravity of polyester paper was 1.38 when no resin was attached. In addition, when there was resin adhesion, the true specific gravity was determined from the specific gravity of the resin, 1.20, the specific gravity of the polyester, 1.38, and the weight ratio of each. Air permeability: Polyester paper based on JIS P-8117
It is expressed as the average number of seconds required for 100 ml of air to pass through an area of 78.54 mm ² . Strong: Based on JIS P-8113, sample length is 50 mm, sample width is 15 mm, and tensile speed using a constant speed extension type universal tensile tester.
Measured at 100%/min. Adhesive back-out prevention property: 10 ml of phenolic resin (No. 110 manufactured by Cemedine Co., Ltd., 50% by weight methyl ethyl ketone solution) was dropped onto the surface of polyester paper, and the back side of the polyester paper was brought into close contact with the paper (Toyo Paper Co., Ltd.). Evaluation was made based on the increase in paper weight caused by the penetration of the phenolic resin into No. 2) manufactured by ). If even a small amount of weight increase was observed, it was judged as defective. Examples 1 to 8, Comparative Examples 1 to 12 Polyethylene terephthalate drawn short fibers with a single yarn fineness of 1.5 denier and a fiber length of 5 mm, polyethylene terephthalate undrawn short fibers with a single yarn fineness of 1.1 denier and a fiber length of 5 mm, a single yarn fineness of 4.0 denier Low melting point polyethylene terephthalate short fibers (melting point 220°C) with a fiber length of 5 mm were mixed at various weight ratios shown in Table 1, paper was made using a cylinder paper machine, and after drying using a Yankee dryer at 120°C, it was weighed. A 65 g/m ² polyester paper was obtained. The surface temperature of the obtained paper was 220℃,
Hot pressure processing was performed using a nip-type calendar roll consisting of a pair of metal rolls with a cotton pressure of 100 kg/cm and a speed of 20 m/min. Furthermore, some of the obtained polyester papers were treated with acrylic ester emulsion (C
-72: After being immersed in a solution (manufactured by Rohm & Haas Co., Ltd.), excess resin was removed using a squeezing roll, and the resin was further dried and cured at 150° C. for 2 minutes. Detailed conditions and performance are shown in Table 1. As is clear from Table 1, if the amount of stretched polyester staple fibers is less than 20% by weight or more than 80% by weight, the paper strength will be insufficient (Comparative Example 1, Example 2,
Comparative Example 6, Comparative Example 9). When the insufficient paper strength is reinforced with resin, the paper strength increases (Example 3, Comparative Example 10).
However, the adhesive back-out prevention property is not good (Example 3,
Comparative example 10). On the other hand, stretched polyester staple fibers are 20
Even within the range of ~80% by weight, adhesive strike-through prevention properties may be poor (Comparative Examples 2 and 7). However, this can be improved by reinforcing it with resin (Example 2, Example 3, Example 7, Example 8). Therefore, the adhesive strike-through prevention property is determined by the porosity and air permeability of the paper structure, and a good range is when the porosity is 60% or less and the air permeability is 100 seconds/100 ml or more. The base material for honeycomb cores of the present invention has excellent strength and adhesive backing resistance, and is an extremely suitable material for manufacturing honeycomb cores. 【table】

Claims (1)

[Scope of Claims] 1. 80 to 20% by weight of one or more short fibers selected from the group consisting of drawn polyester short fibers, undrawn polyester short fibers, and low melting point polyester short fibers.
A base material for a honeycomb core, characterized in that it is made of polyester paper comprising 20 to 80% by weight, a porosity of 60% or less, and an air permeability of 100sec/100ml or more. 2 80 to 20% by weight of one or more short fibers selected from the group consisting of drawn polyester short fibers, undrawn polyester short fibers, and low melting point polyester short fibers
A method for producing a base material for a honeycomb core, which comprises mixing 20 to 80% by weight, wet paper-making, and then heat-pressing. 3 80 to 20% by weight of one or more short fibers selected from the group consisting of drawn polyester short fibers, undrawn polyester short fibers, and low melting point polyester short fibers
A method for manufacturing a base material for a honeycomb core, which comprises mixing 20 to 80% by weight, wet paper-making, heat-pressing processing, and further resin processing. 4. The method for producing a base material for a honeycomb core according to claim 2 or 3, wherein the polyester short fibers have a diameter of 1 to 25 μm and a fiber length of 1 to 20 mm.