JP2005022339A - Sheet steel reinforcing sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet steel reinforcing sheet which can improve both adhesive properties and reinforcing properties. <P>SOLUTION: In the sheet steel reinforcing sheet having a restriction layer 1 and a reinforcement layer 2, the reinforcement layer 2 is formed from an expandable composition containing a polystyrenic synthetic rubber, an aromatic epoxy resin, and a blowing agent. In this way, adhesive strength and reinforcing properties which have been incompatible so far can be made compatible so that the adhesive strength and the reinforcing properties in relation to the sheet steel can sufficiently be secured. By sticking the reinforcing sheet surely to the sheet steel 4 of various industrial machines, the sheet steel 4 can be reinforced effectively. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

なお、表１中の詳細を以下に示す。
【００７８】
ＳＢＲ１：スチレン・ブタジエンランダム共重合体、数平均分子量２４００００、スチレン含有量２５重量％、ムーニー粘度３５（ＭＬ１＋４、ａｔ１００℃）
ＳＢＲ２：スチレン・ブタジエンランダム共重合体、数平均分子量１１００００、スチレン含有量４６重量％、ムーニー粘度４５（ＭＬ１＋４、ａｔ１００℃）
ＢＲ：シンジオタクティック１，２ポリブタジエン、ＭＦＲ（ｇ／１０分、ａｔ１５０℃）３、融点９５℃
エポキシ樹脂：半固形ビスフェノールＡ型エポキシ樹脂、エポキシ当量２５０ｇ／ｅｑｉｖ．
エポキシ変性ＳＢＳ：エポキシ変性スチレン・ブタジエン・スチレンブロック共重合体、スチレン含有量４０重量％、エポキシ当量１０６７ｇ／ｅｑｉｖ．（ダイセル化学工業社製、エポフレンドＡＴ５０１）
発泡剤：４，４’−オキシビス（ベンゼンスルホニルヒドラジド）
エポキシ樹脂硬化剤：ジシアンジアミド
架橋促進剤：ジベンゾチアジルジスルフィド
表１より、エポキシ樹脂のみの比較例３は、補強性は良好であるが低温接着性が不良であることがわかる。また、ＳＢＲ１のみの比較例２は、低温接着性は良好であるが補強性が不良であることがわかる。また、ＢＲおよびエポキシ樹脂からなる比較例１は、ＢＲとエポキシ樹脂相溶性との相溶性が不良であり、そのため、エポキシ樹脂のブリードが確認された。また、補強性および低温接着性ともに不良であることがわかる。
【００７９】
一方、実施例１〜３は、補強性および低温接着性のいずれも良好であり、エポキシ変性ＳＢＳが配合されている実施例１は、特に良好な結果が得られていることがわかる。
【００８０】
【発明の効果】
以上述べたように、本発明の鋼板補強シートによれば、これまで二律背反していた接着力および補強性を両立させることができ、鋼板に対する十分な接着力および補強性を、ともに確保することができる。そのため、各種産業機械の鋼板に確実に貼着して発泡させることにより、その鋼板を効果的に補強することができる。
【図面の簡単な説明】
【図１】本発明の鋼板補強シートを用いて鋼板を補強する方法の一実施形態を示す工程図であって、
（ａ）は、鋼板補強シートを用意して、離型紙を剥がす工程、
（ｂ）は、鋼板補強シートを鋼板に貼着する工程、
（ｃ）は、鋼板補強シートを加熱して発泡させる工程を示す。
【符号の説明】
１ 拘束層
２ 補強層
４ 鋼板[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a steel plate reinforcing sheet, and more particularly to a steel plate reinforcing sheet used by being stuck to a steel plate of various industrial machines such as transportation machines.
[0002]
[Prior art]
Conventionally, in order to reduce the weight of a vehicle body, an automobile body steel plate is generally processed into a thin plate of 0.6 to 0.8 mm. Therefore, it is known to reinforce by sticking a steel plate reinforcing sheet inside the steel plate.
[0003]
Such a steel sheet reinforcing sheet is, for example, affixed in the assembly process of a car body steel sheet, and exhibits a reinforcing property by heating and foaming using heat at the time of electrodeposition coating. A steel plate reinforcing sheet has been proposed comprising a constraining layer comprising a rubber, a thermoplastic elastomer, an inorganic filler, a tackifier, a softener, a cross-linking agent and a foaming resin layer (for example, , See Patent Document 1). In addition, an uncured adhesive layer made of an epoxy resin composition having a tackiness at normal temperature and containing a thermally decomposable foaming agent is laminated and disposed on the surface of the uncured epoxy resin composition substrate layer. A heat-curable thin steel sheet reinforcing adhesive sheet has been proposed (see, for example, Patent Document 2).
[0004]
[Patent Document 1]
JP 7-68695 A
[Patent Document 2]
JP 2002-283526 A
[Problems to be solved by the invention]
However, since car body steel plates and the like have many curved surface designs, it is necessary to stick a steel plate reinforcing sheet on an uneven surface such as a quadratic curved surface or a cubic curved surface. In winter, it may be necessary to apply the paste at a low temperature of around 5 ° C. Therefore, if the adhesive strength of the steel sheet reinforcing sheet is not sufficient, in such a case, after sticking to the steel sheet and before heating and foaming, the steel sheet is peeled off from the steel sheet, resulting in a problem that the working efficiency is lowered.
[0005]
On the other hand, when it is going to ensure sufficient adhesive force of a steel plate reinforcement sheet, it is necessary to reduce the viscosity of the sticking surface in a steel plate reinforcement sheet. However, when the viscosity is lowered in such a manner, there is a problem that the reinforcing property is not sufficiently exhibited after the heat foaming.
[0006]
This invention is made | formed in view of such a malfunction, The place made into the objective is to provide the steel plate reinforcement sheet which can improve both adhesiveness and reinforcement.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a steel plate reinforcing sheet of the present invention is a steel plate reinforcing sheet comprising a constraining layer and a reinforcing layer, and the reinforcing layer comprises a styrene synthetic rubber, an aromatic epoxy resin, and a foaming agent. It is characterized by comprising a foamable composition.
[0008]
In the steel sheet reinforcing sheet of the present invention, it is preferable that the foamable composition further contains an epoxy-modified styrene synthetic rubber.
[0009]
In the steel sheet reinforcing sheet of the present invention, it is preferable that the number average molecular weight of the styrene synthetic rubber is 30000 or more.
[0010]
In the steel sheet reinforcing sheet of the present invention, it is preferable that the foamable composition further contains a rubber crosslinking agent and / or an epoxy resin curing agent.
[0011]
In the steel sheet reinforcing sheet of the present invention, it is preferable that the constraining layer is at least one selected from the group consisting of glass cloth, resin-impregnated glass cloth, synthetic resin nonwoven fabric, and metal foil.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The steel plate reinforcing sheet of the present invention includes a constraining layer and a reinforcing layer.
[0013]
The constraining layer imparts toughness to the reinforcing layer after foaming (hereinafter referred to as a foam layer), is formed into a sheet shape, and is made of a material that is light and thin and can be closely integrated with the foam layer. Preferably formed, such materials include glass cloth, resin-impregnated glass cloth, synthetic resin nonwoven fabric, metal foil, carbon fiber, and the like.
[0014]
The glass cloth is made of glass fiber and a known glass cloth is used. The resin-impregnated glass cloth is obtained by impregnating the above glass cloth with a synthetic resin such as a thermosetting resin or a thermoplastic resin, and a known one is used. In addition, as a thermosetting resin, an epoxy resin, a urethane resin, a melamine resin, a phenol resin etc. are used, for example. Examples of the thermoplastic resin include vinyl acetate resin, ethylene-vinyl acetate copolymer (EVA), vinyl chloride resin, EVA-vinyl chloride resin copolymer, and the like. In addition, the above-described thermosetting resin and the above-described thermoplastic resin (for example, melamine resin and vinyl acetate resin) can be mixed and used.
[0015]
As metal foil, well-known metal foil, such as aluminum foil and steel foil, is used, for example.
[0016]
Of these, glass cloth and resin-impregnated glass cloth are preferably used in consideration of weight, adhesion, strength and cost.
[0017]
The thickness of such a constraining layer is, for example, 0.05 to 0.40 mm, preferably 0.10 to 0.30 mm.
[0018]
Moreover, the foaming composition which foams by a heating layer is formed in the reinforcing layer in the sheet form. The foamable composition contains at least a styrene synthetic rubber, an aromatic epoxy resin, and a foaming agent.
[0019]
Styrenic synthetic rubber is a synthetic rubber in which styrene as a raw material is contained in a molecular chain as a structural unit, and is not particularly limited. For example, styrene / butadiene random copolymer, styrene / butadiene / styrene block copolymer is used. Styrene / butadiene rubber such as polymer, styrene / ethylene / butadiene copolymer, styrene / ethylene / butadiene / styrene block copolymer, and styrene / isoprene rubber such as styrene / isoprene / styrene block copolymer It is done. These may be used alone or in combination. Among these styrene-based synthetic rubbers, styrene-butadiene rubber is preferably used in consideration of reinforcement and adhesion to the oil surface.
[0020]
Such styrene synthetic rubbers have a number average molecular weight of 30,000 or more, preferably 50,000 to 1,000,000. If the number average molecular weight is less than 30,000, the adhesive strength, particularly the adhesiveness to the oil-surfaced steel plate, may be lowered.
[0021]
Further, such a styrene synthetic rubber has a styrene content of preferably 50% by weight or less, and more preferably 35% by weight or less. When there is more styrene content than this, the adhesiveness in low temperature may fall.
[0022]
Moreover, such a styrene synthetic rubber has a Mooney viscosity of, for example, 20 to 60 (ML1 + 4, at 100 ° C.), preferably 30 to 50 (ML 1 + 4, at 100 ° C.).
[0023]
The blending ratio of the styrene synthetic rubber is, for example, 30 to 70 parts by weight, preferably 40 to 60 parts by weight with respect to 100 parts by weight in total of the styrene synthetic rubber and the aromatic epoxy resin. If the blending ratio of the styrene synthetic rubber is less than this, the adhesiveness to the oil-surfaced steel sheet may be lowered. On the other hand, if it is more than this, the reinforcing property may be lowered.
[0024]
The aromatic epoxy resin is an epoxy resin in which a benzene ring is included in a molecular chain as a structural unit, and is not particularly limited. For example, bisphenol A type epoxy resin, dimer acid-modified bisphenol A type epoxy resin Bisphenol type epoxy resins such as bisphenol F type epoxy resin and bisphenol S type epoxy resin, for example, novolak type epoxy resins such as phenol novolak type epoxy resin and cresol novolak type epoxy resin, for example, naphthalene type epoxy resin and the like. These may be used alone or in combination. Among these aromatic epoxy resins, bisphenol type epoxy resins are preferably used in view of reinforcement.
[0025]
Further, such an aromatic epoxy resin has an epoxy equivalent of, for example, 150 to 350 g / eqiv. , Preferably, 200-300 g / eqiv. It is. The epoxy equivalent can be calculated from the oxirane oxygen concentration measured by titration with hydrogen bromide.
[0026]
The blending ratio of the aromatic epoxy resin is, for example, 30 to 70 parts by weight, preferably 40 to 60 parts by weight with respect to a total of 100 parts by weight of the styrene synthetic rubber and the aromatic epoxy resin. When the blending ratio of the aromatic epoxy resin is less than this, the reinforcing property may be lowered. On the other hand, when it is more than this, the adhesiveness to the oil surface steel plate may be lowered.
[0027]
Examples of the foaming agent include inorganic foaming agents and organic foaming agents.
[0028]
Examples of the inorganic foaming agent include ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, azides and the like.
[0029]
Examples of organic foaming agents include N-nitroso compounds (N, N′-dinitrosopentamethylenetetramine, N, N′-dimethyl-N, N′-dinitrosotephthalamide, etc.), azo compounds, and the like. (Eg, azobisisobutyronitrile, azodicarboxylic amide, barium azodicarboxylate, etc.), fluorinated alkanes (eg, trichloromonofluoromethane, dichloromonofluoromethane, etc.), hydrazine compounds (eg, p-toluenesulfonyl) Hydrazide, diphenylsulfone-3,3′-disulfonylhydrazide, 4,4′-oxybis (benzenesulfonylhydrazide), allylbis (sulfonylhydrazide) and the like, semicarbazide compounds (for example, p-toluylenesulfonyl semicarbazide, 4,4 '-Oxybis ( Emissions Zen semicarbazide), etc.), triazole compound (e.g., 5-morpholyl-1,2,3,4-thiatriazole, etc.) and the like.
[0030]
As the foaming agent, a heat-expandable substance (for example, isobutane, pentane, etc.) is contained in a microcapsule (for example, a microcapsule made of a thermoplastic resin such as vinylidene chloride, acrylonitrile, acrylic ester, methacrylic ester). Encapsulated thermally expandable fine particles may be used, and as such thermally expandable fine particles, for example, commercially available products such as microspheres (trade name, manufactured by Matsumoto Yushi Co., Ltd.) may be used.
[0031]
These may be used alone or in combination. Among these foaming agents, 4,4′-oxybis (benzenesulfonylhydrazide) is preferably used in consideration of stable foaming without being influenced by external factors.
[0032]
Moreover, the mixture ratio of a foaming agent is 0.5-10 weight part with respect to a total of 100 weight part of a styrene synthetic rubber and an aromatic epoxy resin, Preferably, it is 1-5 weight part. If the blending ratio of the foaming agent is less than this, foaming does not occur sufficiently, and the reinforcing property may be reduced due to insufficient thickness.
[0033]
Further, such a foamed composition preferably contains an epoxy-modified styrene synthetic rubber in addition to the above components. By containing the epoxy-modified styrene synthetic rubber, compatibility between the styrene synthetic rubber and the aromatic epoxy resin can be improved, and further improvement in adhesion and reinforcement can be achieved.
[0034]
As the epoxy-modified styrene synthetic rubber, for example, a synthetic rubber in which an epoxy group is modified at a molecular chain terminal or molecular chain such as the above-described styrene synthetic rubber, the epoxy equivalent of which is, for example, 100 to 100 10,000 g / eqiv. And 400 to 3000 g / eqiv. Are preferably used. In order to modify the styrene synthetic rubber with an epoxy group, a known method is used. For example, in an inert solvent, a double bond in the styrene synthetic rubber is bonded to a peracid or a hydroperoxide. What is necessary is just to make an epoxidizing agent react.
[0035]
Examples of such an epoxy-modified styrene synthetic rubber include an AB block copolymer and an ABA block copolymer (A represents a styrene polymer block, B represents a butadiene polymer block, A conjugated diene polymer block such as an isoprene polymer block is shown.) A polymer block having an epoxy group introduced therein is used.
[0036]
More specifically, for example, an epoxy-modified styrene / butadiene / styrene block copolymer, an epoxy-modified styrene / ethylene / butadiene / styrene block copolymer, and an epoxy-modified styrene / isoprene / styrene block copolymer are used. These may be used alone or in combination. Of these epoxy-modified styrene-based synthetic rubbers, an epoxy-modified styrene / butadiene / styrene block copolymer is preferably used in consideration of both reinforcement and adhesion.
[0037]
In addition, in the above-mentioned AB type block copolymer and ABA type block copolymer, the A block copolymer which is a styrene polymer block has a weight average molecular weight of about 1000 to 10,000. The glass transition temperature is preferably 7 ° C. or higher, and the B block copolymer which is a conjugated diene polymer block has a weight average molecular weight of about 10,000 to 500,000 and a glass transition temperature of − It is preferable that it is 20 degrees C or less. The weight ratio of the A block copolymer to the B block copolymer is 2/98 to 50/50, more preferably 15/85 to 30/70 as the A block copolymer / B block copolymer. It is preferable that
[0038]
Moreover, the compounding ratio of the epoxy-modified styrene synthetic rubber is, for example, 1 to 20 parts by weight, preferably 5 to 15 parts by weight with respect to 100 parts by weight of the total of the styrene synthetic rubber and the aromatic epoxy resin. . When the blending ratio of the epoxy-modified styrene synthetic rubber is less than this, the reinforcing property and the adhesiveness may be lowered. On the other hand, when it is more than this, the adhesiveness at a low temperature may be lowered.
[0039]
Further, such a foamed composition preferably contains a rubber cross-linking agent and / or an epoxy resin curing agent in addition to the above components. By including a rubber cross-linking agent and / or an epoxy resin curing agent, it is possible to improve the reinforcement.
[0040]
As the rubber cross-linking agent, a known rubber cross-linking agent (vulcanizing agent) capable of cross-linking styrene synthetic rubber or epoxy-modified styrene synthetic rubber by heating is used. Examples of such rubber cross-linking agents include sulfur, sulfur compounds, selenium, magnesium oxide, lead monoxide, organic peroxides (for example, dicumyl peroxide, 1,1-ditertiarybutylperoxy-3, 3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-ditertiarybutylperoxyhexane, 2,5-dimethyl-2,5-ditertiarybutylperoxyhexine, 1,3-bis (ter (Shari-butyl peroxyisopropyl) benzene, tertiary butyl peroxyketone, tertiary butyl peroxybenzoate), polyamines, oximes (for example, p-quinone dioxime, p, p′-dibenzoylquinone dioxime, etc.) Nitroso compounds (eg, p-dinitrosobenzidine), resins (eg, alkyl Phenol - formaldehyde resins, melamine - formaldehyde condensate, etc.), ammonium salts (e.g., ammonium benzoate), and the like.
[0041]
These may be used alone or in combination. Of these rubber cross-linking agents, sulfur is preferably used in consideration of curability and reinforcement.
[0042]
Moreover, the mixture ratio of a rubber crosslinking agent is 1-20 weight part with respect to a total of 100 weight part of a styrene synthetic rubber and an aromatic epoxy resin, for example, Preferably, it is 2-15 weight part. If the blending ratio of the rubber cross-linking agent is less than this, the reinforcing property may be lowered. On the other hand, if it is more than this, the adhesive property may be lowered, which may be disadvantageous in cost.
[0043]
As the epoxy resin curing agent, a known epoxy resin curing agent is used. For example, amine compounds, acid anhydride compounds, amide compounds, hydrazide compounds, imidazole compounds, imidazoline compounds. Examples thereof include compounds. Other examples include phenolic compounds, urea compounds, polysulfide compounds, and the like.
[0044]
Examples of the amine compounds include ethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine, amine adducts thereof, metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone.
[0045]
Examples of the acid anhydride compounds include phthalic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyl nadic acid anhydride, pyromellitic anhydride, dodecenyl succinic anhydride, dichloromethane. Succinic acid anhydride, benzophenone tetracarboxylic acid anhydride, chlorendic acid anhydride, etc. are mentioned.
[0046]
Examples of amide compounds include dicyandiamide and polyamide.
[0047]
Examples of hydrazide compounds include dihydrazide.
[0048]
Examples of imidazole compounds include methylimidazole, 2-ethyl-4-methylimidazole, ethylimidazole, isopropylimidazole, 2,4-dimethylimidazole, phenylimidazole, undecylimidazole, heptadecylimidazole, and 2-phenyl-4. -Methylimidazole etc. are mentioned.
[0049]
Examples of the imidazoline compounds include methyl imidazoline, 2-ethyl-4-methyl imidazoline, ethyl imidazoline, isopropyl imidazoline, 2,4-dimethyl imidazoline, phenyl imidazoline, undecyl imidazoline, heptadecyl imidazoline, 2-phenyl-4. -Methyl imidazoline etc. are mentioned.
[0050]
These may be used alone or in combination. Of these epoxy resin curing agents, dicyandiamide is preferably used in consideration of adhesiveness.
[0051]
Moreover, the compounding ratio of an epoxy resin hardening | curing agent is 0.5-15 weight part with respect to a total of 100 weight part of a styrene synthetic rubber and an aromatic epoxy resin, Preferably it is 1-10 weight part. . When the blending ratio of the epoxy resin curing agent is less than this, the reinforcing property may be lowered, whereas when it is more than this, the storage stability may be deteriorated.
[0052]
Further, in addition to the above components, such a foaming composition may include a foaming aid, a crosslinking accelerator, a curing accelerator, a filler, a tackifier, and, if necessary, a pigment (for example, carbon Black), thixotropic agents (for example, montmorillonite), lubricants (for example, stearic acid), scorch inhibitors, stabilizers, softeners, plasticizers, anti-aging agents, antioxidants, UV absorbers, colorants In addition, known additives such as fungicides and flame retardants may be appropriately contained.
[0053]
Examples of foaming aids include zinc stearate, urea compounds, salicylic acid compounds, benzoic acid compounds, and the like. These foaming auxiliaries may be used alone or in combination. The blending ratio is, for example, 0.5 to 10 parts by weight, preferably 100 parts by weight relative to the total of 100 parts by weight of the styrene synthetic rubber and the aromatic epoxy resin. Is 1 to 5 parts by weight.
[0054]
Examples of the crosslinking accelerator include zinc oxide, dithiocarbamic acids, thiazoles, guanidines, sulfenamides, thiurams, xanthogenic acids, aldehyde ammonias, aldehyde amines, and thioureas. These crosslinking accelerators may be used alone or in combination, and the blending ratio thereof is, for example, 1 to 20 parts by weight, preferably 100 parts by weight with respect to the total of 100 parts by weight of the styrene synthetic rubber and the aromatic epoxy resin, 3 to 15 parts by weight.
[0055]
Examples of the curing accelerator include imidazoles, tertiary amines, phosphorus compounds, quaternary ammonium salts, and organometallic salts. These curing accelerators may be used alone or in combination, and the blending ratio thereof is, for example, 0.5 to 20 parts by weight, preferably 100 parts by weight relative to the total of 100 parts by weight of the styrene synthetic rubber and the aromatic epoxy resin. Is 1 to 10 parts by weight.
[0056]
Examples of the filler include calcium carbonate (for example, heavy calcium carbonate, light calcium carbonate, white luster), talc, mica, clay, mica powder, bentonite, silica, alumina, aluminum silicate, titanium oxide, acetylene black, aluminum Examples include powder. These fillers may be used alone or in combination, and the blending ratio thereof is, for example, 50 to 150 parts by weight, preferably 75 with respect to 100 parts by weight in total of the styrene synthetic rubber and the aromatic epoxy resin. ~ 125 parts by weight.
[0057]
Examples of the tackifier include rosin resins, terpene resins (for example, terpene-aromatic liquid resins), coumarone indene resins, petroleum resins (for example, C5 / C9 petroleum resins), and the like. Can be mentioned. These tackifiers may be used alone or in combination, and the blending ratio thereof is, for example, 10 to 200 parts by weight, preferably 100 parts by weight with respect to a total of 100 parts by weight of the styrene synthetic rubber and the aromatic epoxy resin. 20 to 150 parts by weight.
[0058]
The foamable composition is prepared as a kneaded product by blending the above-described components in the above-described blending ratio, and is not particularly limited. For example, the foamable composition is kneaded by a mixing roll, a pressure kneader, an extruder, or the like. Can do.
[0059]
In addition, it is preferable to prepare so that the flow tester viscosity (60 degreeC, 24 kg load) of the kneaded material obtained in this way may be 1000-5000 Pa.s, for example, Furthermore, 1500-4000 Pa.s.
[0060]
Thereafter, the kneaded product obtained is not particularly limited, and a reinforcing layer is formed by rolling, for example, by calender molding, extrusion molding or press molding under a temperature condition where the foaming agent is not substantially decomposed. A steel plate reinforcing sheet is obtained by bonding the reinforcing layer to the constraining layer.
[0061]
The thickness of the reinforcing layer thus formed is, for example, 0.2 to 3.0 mm, preferably 0.5 to 1.3 mm.
[0062]
Moreover, the sum total of the thickness of a constrained layer and a reinforcement layer is 0.3-3.4 mm, for example, Preferably, it is 0.6-1.6 mm.
[0063]
In addition, you may stick a release paper on the surface of a reinforcement layer as needed to the obtained steel plate reinforcement sheet.
[0064]
Moreover, in the steel plate reinforcement sheet obtained in this way, the volume expansion ratio at the time of foaming of the foamable composition used as the reinforcing layer is 1.5 to 4.0 times, and further 2.0 to 3. It is preferably 5 times. The density of the foam in the foam layer (foam weight (g) / foam volume (g / cm ³ )), For example, 0.2-0.8 g / cm ³ Furthermore, 0.3 to 0.7 g / cm ³ It is preferable that
[0065]
And the steel plate reinforcement sheet | seat of this invention obtained by doing in this way is used in order to stick on the steel plate of various industrial machines, such as a transport machine, and to reinforce the steel plate. More specifically, in the steel sheet reinforcing sheet of the present invention, as shown in FIG. 1A, a reinforcing layer 2 is laminated on the constraining layer 1, and a release paper 3 is attached to the surface of the reinforcing layer 2 as necessary. In use, the release paper 3 is peeled off from the surface of the reinforcing layer 2 as shown by phantom lines, and the surface of the reinforcing layer 2 is adhered to the steel plate 4 as shown in FIG. Then, as shown in FIG. 1C, the foam layer 5 is formed by heating, foaming, crosslinking and curing by heating at a predetermined temperature (for example, 160 to 210 ° C.). It is done.
[0066]
Such a steel plate reinforcing sheet of the present invention can be suitably used for reinforcing a car body steel plate of an automobile that is required to be reduced in weight. In that case, the steel plate reinforcing sheet is, for example, an assembly of a car body steel plate first. After being stuck in the process, it is then used in such a manner that the foam layer is formed by heating, foaming, crosslinking and curing by utilizing the heat during electrodeposition coating.
[0067]
And the steel plate reinforcement sheet of this invention expresses sufficient adhesive force with respect to the steel plate also to the uneven surface which consists of curved designs, such as a quadratic curved surface and a cubic curved surface, and also under the low temperature of winter. be able to. And the steel plate reinforcement sheet of this invention can express sufficient reinforcement after heating foaming.
[0068]
Therefore, the steel plate reinforcing sheet of the present invention can achieve both the adhesive force and the reinforcing property which have been contradictory so far, and can ensure both the sufficient adhesive force and reinforcing property for the steel plate.
[0069]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these.
[0070]
Examples and comparative examples
In the formulation shown in Table 1, each component was blended and kneaded with a 10-inch mixing roll to prepare a kneaded product. In this kneading, first, a resin component (at least one component of SBR1, SBR2, BR, epoxy resin, epoxy-modified SBS), a filler component (at least one component of heavy calcium carbonate, talc), A tackifier component (terpene-aromatic liquid resin, at least one of C5 / C9 petroleum resin) is kneaded at 130 ° C., and then added to a foaming agent, sulfur, an epoxy resin curing agent, and an oxidation agent. Zinc and a crosslinking accelerator were blended and kneaded at 20 ° C.
[0071]
This kneaded product is rolled to a thickness of 0.6 mm with a calender roll to form a reinforcing layer, and a glass cloth having a thickness of 0.2 mm is bonded to the reinforcing layer as a constraining layer. A steel sheet reinforcing sheet was prepared by sticking a release paper on the opposite surface to which the sheets were bonded.
[0072]
Evaluation
About the obtained steel plate reinforcement sheet of each Example and each comparative example, reinforcement property and low temperature oil surface adhesiveness were evaluated as follows. The results are shown in Table 1.
[0073]
Reinforcing test
The release paper of the steel sheet reinforcement sheet of each Example and each Comparative Example was peeled off, and each steel sheet reinforcement sheet was oil-surface cold-rolled steel sheet (SPCC-SD) having a width of 25 mm × 150 mm length × 0.8 mm (Japan test) Panels) were each attached in an atmosphere of 20 ° C. and heated at 160 ° C. for 20 minutes to foam the reinforcing layer, thereby obtaining a test piece.
[0074]
Then, with the steel plate facing upward, each test piece was supported with a span of 100 mm, and at the center in the longitudinal direction, the test bar was lowered from above in the vertical direction at a compression rate of 1 mm / min, and then contacted with the steel plate. The bending strength (N) when the foam layer was displaced by 1 mm was evaluated as the reinforcing property.
[0075]
2) Low temperature oil surface adhesion test
Oil surface cold-rolled steel sheet (SPCC-SD) (manufactured by Nippon Test Panel Co., Ltd.) was prepared corresponding to each example and each comparative example, and a rust preventive (Idemitsu Kosan Co., Ltd., Daphne Oil Z-) was prepared on the surface. 5) was applied and stood vertically at 20 ° C. overnight.
[0076]
Thereafter, the steel sheet reinforcing sheet of each example and each comparative example was cut out with a width of 25 mm, the release paper was peeled off, and the coated surface of each steel sheet coated with a rust preventive was pressure-bonded with a 2 kg roller in an atmosphere of 5 ° C. Then, 30 minutes later, the adhesive strength (N / 25 mm) was measured by a 90 ° peel test (tensile speed 300 mm / min), and this was evaluated as low temperature oil surface adhesion.
[0077]
[Table 1]

Details in Table 1 are shown below.
[0078]
SBR1: Styrene-butadiene random copolymer, number average molecular weight 240000, styrene content 25% by weight, Mooney viscosity 35 (ML1 + 4, at100 ° C.)
SBR2: Styrene-butadiene random copolymer, number average molecular weight 110,000, styrene content 46% by weight, Mooney viscosity 45 (ML1 + 4, at100 ° C.)
BR: Syndiotactic 1,2 polybutadiene, MFR (g / 10 min, at 150 ° C.) 3, melting point 95 ° C.
Epoxy resin: Semi-solid bisphenol A type epoxy resin, epoxy equivalent 250 g / eqiv.
Epoxy-modified SBS: epoxy-modified styrene / butadiene / styrene block copolymer, styrene content of 40% by weight, epoxy equivalent of 1067 g / eqiv. (Daicel Chemical Industries, Epofriend AT501)
Foaming agent: 4,4′-oxybis (benzenesulfonylhydrazide)
Epoxy resin curing agent: Dicyandiamide
Cross-linking accelerator: dibenzothiazyl disulfide
From Table 1, it can be seen that Comparative Example 3 containing only an epoxy resin has good reinforcing properties but poor low-temperature adhesiveness. Moreover, it turns out that the comparative example 2 only with SBR1 has low-temperature adhesiveness, but reinforcement property is bad. Moreover, the comparative example 1 which consists of BR and an epoxy resin has a bad compatibility with compatibility of BR and an epoxy resin, Therefore The bleeding of an epoxy resin was confirmed. Moreover, it turns out that both reinforcement and low temperature adhesiveness are unsatisfactory.
[0079]
On the other hand, both Examples 1 to 3 have good reinforcing properties and low-temperature adhesiveness, and Example 1 in which epoxy-modified SBS is blended shows particularly good results.
[0080]
【The invention's effect】
As described above, according to the steel sheet reinforcing sheet of the present invention, it is possible to achieve both the adhesive force and the reinforcing property which have been contradictory so far, and to ensure both sufficient adhesive force and reinforcing property for the steel plate. it can. Therefore, the steel plate can be effectively reinforced by sticking and foaming it securely on the steel plate of various industrial machines.
[Brief description of the drawings]
FIG. 1 is a process diagram showing an embodiment of a method for reinforcing a steel sheet using the steel sheet reinforcing sheet of the present invention,
(A) is a step of preparing a steel sheet reinforcing sheet and peeling the release paper;
(B) is a step of sticking the steel sheet reinforcing sheet to the steel sheet;
(C) shows the process of heating and foaming a steel plate reinforcement sheet.
[Explanation of symbols]
1 Constrained layer
2 Reinforcing layer
4 Steel plate

Claims (5)

A steel sheet reinforcing sheet comprising a constraining layer and a reinforcing layer,
The steel sheet reinforcing sheet, wherein the reinforcing layer is made of a foamable composition containing a styrene synthetic rubber, an aromatic epoxy resin and a foaming agent. The steel sheet reinforcing sheet according to claim 1, wherein the foamable composition further contains an epoxy-modified styrene synthetic rubber. The steel sheet reinforcing sheet according to claim 1 or 2, wherein the number average molecular weight of the styrene synthetic rubber is 30000 or more. The steel sheet reinforcing sheet according to any one of claims 1 to 3, wherein the foamable composition further contains a rubber crosslinking agent and / or an epoxy resin curing agent. The steel sheet reinforcing sheet according to any one of claims 1 to 4, wherein the constraining layer is at least one selected from the group consisting of glass cloth, resin-impregnated glass cloth, synthetic resin nonwoven fabric, and metal foil. .

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