JP4344896B2 - Car body steel sheet reinforcement sheet - Google Patents

Description

【００４２】
〔比較例８〕
下記組成で各成分をオープンニーダー中で混練して、押出機で厚み１ｍｍのシート状に成形し、樹脂含浸ガラスクロスを拘束層として積層した。
なお、充填剤と発泡剤は実施例２と同様のものを使用した。
【００４３】
成分 重量部
エポキシ樹脂 ４０
ゴム（イソプレンゴム） ６
硬化剤（ジシアンジアミド） ４
充填剤 ４０
発泡剤 １０
【００４４】
積層前のシート及び拘束層との積層体について、実施例２と同様の試験・評価を行ったところ、以下の結果が得られた。
混練性 ○
架橋前の密着性 ○
耐衝撃性 ○
架橋後の接着性 ○
剛性 ○
発泡状態 ○
貯蔵安定性 ×
【図面の簡単な説明】
【図１】接着性の試験方法の説明図である。
【図２】剛性の試験方法の説明図である。
【符号の説明】
１ 未加硫シート
２ 鋼板
３ 鋼板とシートとの積層体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reinforcing sheet for increasing the rigidity of a steel plate for automobile bodies.
[0002]
[Prior art]
Steel plates used for automobile bodies tend to be thin steel plates to reduce the weight of automobile bodies, and generally about 0.6 to 0.8 mm. For this reason, the larger the size of a single steel plate, the easier it is to deform against external stress, and depending on the body part, the steel plate may be distorted and the appearance may be deteriorated. Since there is a possibility of impairing safety, it is necessary to further increase the rigidity of the steel plate in such a part.
[0003]
Conventionally, a method of reinforcing rigidity by attaching a reinforcing sheet to the inside of a steel plate has been performed at a location requiring such rigidity. As this rigid reinforcing material, a alkyd resin, an epoxy resin, an acrylic resin, a urethane resin, a urea resin, and the like are mixed with a curing agent, a filler, and various additives into a sheet shape, processed into a predetermined shape, or Mainly a mixture of liquid rubber and solid rubber as disclosed in JP-A-5-339429, or a mixture of liquid rubber and thermoplastic elastomer disclosed in JP-A-7-68695. For example, cross-linking agents, fillers, tackifiers, and various additives are blended into products and processed into prescribed shapes, which are attached to steel plates and fired and cross-linked to reinforce the steel plates. Have been proposed.
[0004]
However, those containing a thermosetting resin such as an epoxy resin as a main ingredient have the disadvantages that the storage stability before baking is poor, and the steel sheet is distorted by the residual resin stress after curing and the appearance is impaired.
[0005]
In addition, liquid rubbers such as JP-A-5-339429 and JP-A-7-68695 mixed with solid rubber or thermoplastic elastomer are blended especially when pasted on a tight part of a curved surface of a vehicle body. Because the cohesive force of the object is strong, the central part of the steel plate floats and the smoothness of the pasting surface is lost, or the treatment sheet enters the pretreatment process in the automobile manufacturing process and the reinforcing sheet falls off Adhesion to the steel sheet is not sufficiently performed, and there is a problem that rust occurs during long-term storage after baking.
[0006]
Furthermore, steel sheets for automobile bodies may have been surface-treated with rust-preventing oil or the like in advance. In such surface-treated steel sheets, not only the adhesion with the reinforcing sheet before cross-linking is significantly reduced, but also firing / cross-linking. Adhesion with the later reinforcing sheet is inferior, and there is a drawback that the film floats on the curved surface.
[0007]
[Problems to be solved by the invention]
The present invention solves the above problems, and as a reinforcing sheet for steel sheets for automobile bodies, it improves storage stability before curing, significantly reduces distortion after curing, reduces cohesion, and maintains smoothness. An object of the present invention is to provide a reinforcing sheet for an automobile body steel plate that does not generate a float at the center of the steel plate even when pasted on a curved surface.
[0008]
Means for Solving the Problem and Embodiment of the Invention
As a result of earnest research to solve the above problems, the present inventor is excellent in adhesion and adhesiveness with a steel sheet by using a two-layer laminate in which an unvulcanized sheet having a specific composition and a constrained layer are laminated, In this case, the storage stability of the composition is remarkably improved by using maleic acid-modified polybutadiene having a viscosity of less than 500,000 poise (25 ° C.) alone as a base resin as a modified liquid rubber. In addition, 5 to 1500 parts by weight of an inorganic filler, 1 to 200 parts by weight of a tackifier, and 1 to 100 parts by weight of insoluble sulfur as a sulfur-based crosslinking agent are added to 100 parts by weight of the modified liquid rubber. When a vulcanized sheet is formed and this and a constrained layer are laminated and used, all properties such as kneadability, adhesion before curing, adhesion after curing, rigidity, and storage stability are well balanced Found that to obtain, the present invention has been accomplished.
[0009]
Therefore, the present invention
(1) (A) 5 to 1500 parts by weight of inorganic filler, (C) tackifier 1 with respect to 100 parts by weight of maleic acid-modified polybutadiene having a viscosity of less than 500,000 poise (25 ° C.) as a modified liquid rubber -200 parts by weight, (D) an unvulcanized sheet obtained by blending 1 to 100 parts by weight of insoluble sulfur , and laminating a constraining layer;
(2) (A) 5 to 1500 parts by weight of inorganic filler, (C) tackifier 1 with respect to 100 parts by weight of maleic acid-modified polybutadiene having a viscosity of less than 500,000 poise (25 ° C.) as a modified liquid rubber -200 parts by weight, (D) 1-100 parts by weight of insoluble sulfur , (E) unvulcanized sheet obtained by blending 1-100 parts by weight of foaming agent, and laminating a constraining layer, Reinforcement sheet for automobile body steel plate,
( 3 ) The reinforcing sheet for automobile body steel plate according to (1) or (2) , wherein the constraining layer is glass cloth, paper, glass cloth resin, carbon fiber, nonwoven fabric or metal foil.
[0010]
Hereinafter, the present invention will be described in more detail.
The reinforcing sheet for automobile body steel plate according to the present invention is composed of a two-layer laminate of an unvulcanized sheet having the above composition and a constraining layer, and is laminated and pasted so that the unvulcanized sheet side is in contact with the automobile body steel plate. After that, it is heated and fired by a method such as passing through an oven in an automobile production line, and is crosslinked and hardened to firmly adhere to the steel plate to form a laminate.
[0011]
Maleic acid-modified polybutadiene rubber is used as the (A) modified liquid rubber as the base resin for forming the unvulcanized sheet of the present invention because the object of the present invention can be achieved more effectively. In the present invention, other resin components can be added depending on the application, but only the (A) modified liquid rubber is used as the base resin, and no other rubber components are blended.
[0012]
The preferred viscosity of the (A) modified liquid rubber of the present invention is less than 500,000 poise at 25 ° C., and if it exceeds this, the cohesive strength of the compound will be reduced when it is stuck and baked on the curved surface of the vehicle body. Due to the strength, floating occurs in the central portion of the steel sheet, the smoothness of the pasting surface is impaired, and the sheet may fall off due to the intrusion of the processing liquid in the pretreatment process.
[0013]
Examples of the inorganic filler (B) of the present invention include glass fibers, surface chemically treated glass fibers, carbon fibers, graphite, metal fibers, fibrous fillers such as titanium oxide, glass balloons, fly ash balloons, and silica balloons. In addition to hollow fillers, light calcium carbonate, heavy calcium carbonate, various surface-treated calcium carbonates that lower the specific gravity, talc, magnesium hydroxide, mica, clay, barium sulfate, natural silicon, synthetic silicon, and carbon Black can be used. These can be used alone or in admixture of two or more. In particular, heavy calcium carbonate is preferred from the viewpoint of cost and ease of handling.
[0014]
(B) The compounding quantity of an inorganic filler is 5-1500 weight part with respect to 100 weight part of (A) modified liquid rubber, Preferably it is 200-800 weight part. If it is less than 5 parts by weight, the kneadability of the composition is inferior, and the shape retention property of the finished composition is inferior. On the other hand, when it exceeds 1500 parts by weight, the adhesion before baking and the adhesiveness after baking are lowered, and the rigidity against bending is lowered.
[0015]
As the tackifier (C) of the present invention, rosin resins, terpene resins, terpene modified resins, aliphatic or aromatic petroleum resins, coumarone indene resins, and those obtained by hydrogenation thereof can be used. These can be used alone or in admixture of two or more.
[0016]
The amount of component (C) is 1 to 200 parts by weight, preferably 50 to 150 parts by weight, based on 100 parts by weight of (A) the modified liquid rubber. If it is less than 1 part by weight, the adhesion to the steel sheet and the adhesion to the constraining layer may be reduced. If it exceeds 200 parts by weight, the hardness after baking will increase excessively and may be peeled off when an impact is applied.
[0017]
As the crosslinking agent to be added to the unvulcanized sheet forming composition of the present invention, Ru with (D) insoluble sulfur.
[0018]
In particular, insoluble sulfur is excellent in long-term stability compared to other sulfur-based compounds in the composition for forming an unvulcanized sheet of the present invention, can maintain its performance as a crosslinking agent, and is remarkably stored. It is suitable because of its excellent stability.
[0019]
(D) The compounding quantity of a sulfur type crosslinking agent is 1-100 weight part with respect to 100 weight part of (A) modified liquid rubber, Preferably it is 30-70 weight part. When the amount is less than 1 part by weight, crosslinking is insufficient and sufficient strength cannot be ensured. Moreover, when it exceeds 100 weight part, the adhesiveness of the composition before bridge | crosslinking will fall.
[0020]
Examples of the vulcanization accelerator used in combination with the (D) sulfur-based crosslinking agent include tetramethylthiuram disulfide (TMTD), tetramethylthiuram monosulfide (TMTM), N-oxydiethylene-2-benzothiazolyl sulfenamide ( OBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), dipentamethylene thiuram tetrasulfide (DPTT), dibenzothiazyl sulfide (MBTS), 2-mercaptobenzothiazole (MBT), zinc di-n Butyl dithiocarbide (ZnBDC), zinc dimethyldithiocarbide (ZnMDC), and the like. These can be used alone or in combination of two or more in an appropriate amount.
[0021]
The unvulcanized sheet of this invention can also be made into a foam sheet using a foaming agent as needed. In this case, as the foaming agent (E), known pyrolytic organic and inorganic foaming agents can be used. Examples of the organic blowing agent include azodicarbonamide, dinitrosopentamethylenetetramine, sulfonyl hydrazide, dinitrosotephthalamide, barium azodicarboxylate, toluenesulfonyl hydrazide, azobisisobutyronitrile, and the inorganic blowing agent includes Examples include sodium bicarbonate, sodium carbonate, sodium bicarbonate, ammonium bicarbonate, and ammonium carbonate. These foaming agents may be used in combination with known foaming aids such as urea and urea derivatives.
[0022]
As the foaming agent (E), in addition to these foaming agents, thermal expansion type microcapsules obtained by microcapsulating low boiling point hydrocarbons with vinylidene or the like can also be used. These foaming agents can be used alone or in combination of two or more.
[0023]
(E) The compounding quantity of a foaming agent mix | blends 1-100 weight part with respect to 100 weight part of (A) modified liquid rubber, especially 5-100 weight part. When the amount exceeds 100 parts by weight, the foamed cell becomes too large, not only deteriorating the appearance, but also becomes brittle and sufficient strength cannot be obtained.
[0024]
The unvulcanized sheet of the present invention is the above-mentioned components (A), (B), (C) and (D), or those further added with component (E) if necessary, Banbury mixer, pressure kneader, open kneader, After mixing and kneading with a kneader such as an open roll, it is obtained by forming a sheet having a predetermined shape using a calendar roll, an extruder or the like.
[0025]
The constraining layer laminated on the unvulcanized sheet is provided in order to maintain the shape of the unvulcanized sheet, and is lightweight and flexible, and has excellent toughness. Further, the unvulcanized sheet It is desirable to sufficiently adhere to the surface by light work such as crimping, specifically, glass cloth, paper, glass cloth resin, carbon fiber, non-woven fabric, metal foil, one or two of these A combination of the above can be used. Of these, a glass cloth excellent in strength and flexibility is particularly desirable.
[0026]
In addition, the thickness of the unvulcanized sheet is preferably 0.5 to 3 mm, particularly preferably 0.8 to 2 mm, and the thickness of the constraining layer is preferably 0.05 to 1 mm, particularly preferably 0.05 to 0.2 mm.
[0027]
The reinforcing sheet for automobile body steel plate according to the present invention is a two-layer laminated body obtained by laminating and bonding the unvulcanized sheet and the constraining layer by pressure bonding and / or heating, and this is a necessary part of the steel sheet constituting the automobile body. Pasted in the direction where the unvulcanized sheet side comes into contact with the steel plate, and then cured by being fired and cross-linked by passing through an oven or the like of an automobile production line. By doing so, a reinforcing sheet firmly fixed to the steel plate can be obtained. The crosslinking temperature is 120 to 250 ° C. which is a general range of an automobile production line, and the unvulcanized sheet of the present invention can obtain a sufficient crosslinked or foamed state in such a general temperature range. Further, the crosslinking proceeds satisfactorily under any conditions of atmospheric pressure and pressure.
[0028]
【The invention's effect】
The reinforcing sheet of the present invention has good adhesion before curing and adhesion after curing even when the steel sheet is surface-treated with rust-preventing oil, etc. Is small, the smoothness is maintained, and the strength is high.
[0029]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.
[0030]
Examples 1 and 2
In the composition shown in Table 1, maleic acid-modified polybutadiene (viscosity 600 poise (25 ° C.)) is used as a modified liquid rubber, an aliphatic petroleum resin is used as a tackifier, and calcium carbonate is used as a filler. After preliminarily kneading with an open kneader in an amount, insoluble sulfur as a crosslinking agent and azodicarbonamide as a foaming agent were added in the blending amounts shown in Table 1 and kneaded.
The kneadability at this time was evaluated by the following method. The results are shown in Table 1.
[0031]
Kneading property In the kneading of the open kneader, the kneading state was confirmed visually.
[Evaluation]
○: Dispersion is good △: Dispersion is slightly bad ×: Dispersion is poor
Thereafter, the kneaded dough was formed into a 1 mm thick sheet by an extruder.
The following evaluation was performed about the obtained unvulcanized sheet. The results are shown in Table 1.
[0033]
Adhesiveness As shown in FIG. 1, the unvulcanized sheet 1 is cut into 50 mm × 150 mm, sandwiched between 50 mm × 200 mm × 0.8 mm steel plate 2 and baked at 170 ° C. for 30 minutes to be vulcanized. Then, the temperature was returned to room temperature, and the peeled state after being pulled with a tensile tester was visually confirmed.
[Evaluation]
○: Good △: Slightly bad ×: Bad [0034]
Rigidity As shown in Fig. 2, unvulcanized sheet was cut into 50mm x 150mm, pasted on a 50mm x 200mm x 0.8mm steel plate, baked at 170C for 30 minutes and vulcanized 3 was returned to normal temperature, and the value at the time of 2 mm displacement when three-point bending (span 100 mm, bending speed 5 mm / min) was performed.
[Evaluation]
○: Good △: Slightly good ×: Bad
Foamed state An unvulcanized sheet was baked at 170C for 30 minutes, vulcanized and foamed, and the foamed state was visually confirmed.
[Evaluation]
○: Good △: Somewhat bad ×: Bad
Storage stability 50mm x 100mm unvulcanized sheet was left in a temperature of 40 ° C and humidity of 95% for 168 hours, then attached to a steel plate coated with 200mm x 300mm x 0.8mm rust-preventive oil, and at 20 ° C atmosphere The impact test was performed below, and the judgment was made based on the state of adhesion.
[Evaluation]
○: Good △: Slightly bad ×: Bad [0037]
Next, a resin-impregnated glass cloth was laminated as a constraining layer on the unvulcanized sheet. The laminate was evaluated as follows. The results are also shown in Table 1.
[0038]
Adhesion Unvulcanized sheet with a constraining layer laminated is cut to 50 mm x 100 mm and attached to a 0.8 mm steel plate coated with 200 mm x 300 mm rust-preventive oil (no heat treatment), at 20 ° C atmosphere An impact test according to JIS G 3192 was performed below.
[Evaluation]
○: Good △: Somewhat bad ×: Bad
Impact resistance An unvulcanized sheet laminated with a constraining layer is cut to 50 mm x 100 mm, attached to a steel plate of 200 mm x 300 mm x 0.8 mm, baked at 170C for 30 minutes, vulcanized, and 20 An impact test according to JIS G 3192 was performed in an atmosphere of ° C.
[Evaluation]
○: Good △: Somewhat bad ×: Bad
[Comparative Examples 1-7]
In the composition shown in Table 1, a laminate of an unvulcanized sheet and a glass cloth was produced in the same manner as in Example 2, and the same test and evaluation as in Example 2 were performed. The results are shown in Table 1.
[0041]
[Table 1]

[0042]
[Comparative Example 8]
Each component was kneaded in an open kneader with the following composition, formed into a sheet having a thickness of 1 mm with an extruder, and laminated with a resin-impregnated glass cloth as a constraining layer.
Note that the same filler and foaming agent as in Example 2 were used.
[0043]
Ingredient Weight part Epoxy resin 40
Rubber (Isoprene rubber) 6
Curing agent (dicyandiamide) 4
Filler 40
Foaming agent 10
[0044]
About the laminated body with the sheet | seat before lamination | stacking and a constrained layer, when the same test and evaluation as Example 2 were performed, the following results were obtained.
Kneadability ○
Adhesion before crosslinking ○
Impact resistance ○
Adhesion after crosslinking ○
Rigidity ○
Foamed state ○
Storage stability ×
[Brief description of the drawings]
FIG. 1 is an explanatory view of an adhesion test method.
FIG. 2 is an explanatory diagram of a stiffness test method.
[Explanation of symbols]
1 Unvulcanized sheet 2 Steel plate 3 Laminate of steel plate and sheet

Claims (3)

As a modified liquid rubber , 5 to 1500 parts by weight of an inorganic filler, 1 to 200 parts by weight of a tackifier, and 1 to 100 parts by weight of insoluble sulfur with respect to 100 parts by weight of maleic acid-modified polybutadiene having a viscosity of less than 500,000 poise (25 ° C.) A reinforcing sheet for automobile body steel sheets, wherein a constrained layer is laminated on an unvulcanized sheet obtained by blending the above. As a modified liquid rubber , 5 to 1500 parts by weight of an inorganic filler, 1 to 200 parts by weight of a tackifier, and 1 to 100 parts by weight of insoluble sulfur with respect to 100 parts by weight of maleic acid-modified polybutadiene having a viscosity of less than 500,000 poise (25 ° C.) A reinforcing sheet for automobile body steel sheets, wherein a constraining layer is laminated on an unvulcanized sheet obtained by blending 1 to 100 parts by weight of a foaming agent. The reinforcing sheet for automobile body steel plate according to claim 1 or 2 , wherein the constraining layer is glass cloth, paper, glass cloth resin, carbon fiber, nonwoven fabric or metal foil.

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