JP2007099800A - Hot-melt sealing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot-melt sealing material excellent in adhesion to an adherend, applicability, heat resistance and flame retardance, which solves the problems accompanying conventional hot-melt sealing materials wherein a tackifier, a wax, a filler, etc., are compounded with a base polymer, which results in poor flame retardance and unsatisfactory heat resistance. <P>SOLUTION: The hot-melt sealing material contains a synthetic rubber, a tackifier, a liquid resin, flame retardants, etc., has a melt viscosity at 200°C of 150 Pa s or smaller and meets the V-0 or V-1 criteria of the UL94 standard by comprising a phosphate and melamine or a melamine derivative as the flame retardants. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hot-melt sealing material that is excellent in adhesion to an adherend, coatability, heat resistance, flame retardancy, and the like.

  As a hot-melt type sealing agent, tackifying is applied to base polymers such as ethylene vinyl acetate copolymer resin, ethylene-acrylic acid ester copolymer resin, styrene block polymer, styrene-ethylene-propylene-styrene block copolymer resin, and butyl rubber. A blend of resin, wax, filler, etc. was used. Of course, since it is flammable, it is poor in flame retardancy and is not always satisfactory in terms of heat resistance.

An inorganic flame retardant generally used as a flame retardant has a poor flame retardant effect when added in a small amount, and increasing the amount added to obtain a sufficient effect greatly affects the physical properties. Also, there is a problem that the gear pump of the hot melt applicator is worn out because of its high hardness.
On the other hand, the use of halogen-based flame retardants is prohibited by recent regulations from the viewpoint of environmental protection. Phosphoric ester flame retardants have a strong plasticizing effect, resulting in a decrease in physical properties of the hot melt, and melamine flame retardants alone have problems such as insufficient effects.

  On the other hand, if high molecular weight butyl rubber or styrene block polymer is used for the base polymer in order to ensure heat resistance, the melt viscosity becomes high, and the coating property and the discharge property are remarkably lowered, which is not practical. There is a problem.

In order to seal a hot-melt sealing material, it is usually necessary to apply or discharge while hot-melting it with an applicator having a heating device. However, since heating of the hot melt composition starts when the temperature exceeds 200 ° C., heating at 200 ° C. or less is required. Therefore, although a melt viscosity at a temperature of 200 ° C. or lower is appropriate for coating and discharging and a heat-resistant blend is required, a blending material and prescription satisfying both conditions have not been developed.
JP 2002-322455 A

  The problem to be solved by the present invention relates to a hot-melt sealing material that is excellent in adhesion to an adherend, coatability, heat resistance and flame retardancy.

  It contains at least a synthetic rubber, a tackifying resin, a liquid resin, a flame retardant, and an anti-aging agent, and has a melt viscosity at 200 ° C. of 150 Pa · s or less, and as the flame retardant, a phosphate ester and melamine Alternatively, it was possible to pass UL94 standard V-0 or V-1 by using a melamine derivative.

  The hot-melt sealing material according to the present invention is excellent in adhesion to an adherend, coating property, heat resistance, etc., and has a melt viscosity at 200 ° C. of 150 Pa · s or less and is easy to use, as a flame retardant. By adding a phosphate ester and melamine or a melamine derivative, flame retardancy that passes V94 or V-1 of UL94 standard can be realized. For this reason, it can be safely used for applications such as electronic equipment, vehicles, and architecture.

  The present invention is intended to provide a hot-melt sealing material that is excellent in adhesion to an adherend, coatability, heat resistance, flame retardancy, and the like and finished to an appropriate melt viscosity.

Examples of the synthetic rubber employed in the present invention include SBR, NBR, butadiene rubber, ethylene / propylene rubber, butyl rubber, and styrene block polymer.
Among them, in the hot melt type sealing material of the present invention, it has been proved that butyl rubber or a mixture of butyl rubber and a styrene block polymer is excellent in terms of the balance between fluidity and heat resistance during melting.

Butylcomb is effective in imparting sealing properties, heat resistance, shock absorption, weather resistance, etc., and has a Mooney viscosity of 20 to 90 and an unsaturation degree of about 0.5 to 5.0 Is suitable for use. By having an unsaturated portion, it is possible to adjust the viscosity due to a decrease in molecular weight during heating and kneading.
Commercially available products include # 065 from Nippon Butyl Co., Ltd.

Specific examples of styrenic block copolymers include styrene-isoprene-styrene (SIS) block copolymers, styrene-butadiene-styrene (SBS) block copolymers, styrene-ethylene-1 butene-styrene (SEBS) block copolymers. Polymer, styrene-ethylene-propylene-styrene (SEPS) block copolymer, poly (α-methylstyrene) -polybutadiene-poly (α-methylstyrene), poly (α-methylstyrene) -polyisoprene-poly (α -Methylstyrene), as well as their hydrogenated modifications, such as poly (α-methylstyrene) -poly (ethylene-1butene) -poly (α-methylstyrene), poly (α-methylstyrene) -poly (ethylene- Propylene) -poly (α-methylstyrene). Commercially available products include Clayton G1650 manufactured by Shell Chemical Co., and Septon 2043 manufactured by Kuraray Co., Ltd.
In order to secure fluidity at the time of melting, a number average molecular weight Mn of 100,000 or less is preferable.

When the butyl rubber and the styrene block polymer are mixed and used, the blending ratio of the butyl rubber and the styrene block polymer is preferably 5 to 50 parts by weight with respect to the former 100 parts by weight. If it is less than 5 parts by weight, a sufficient melt viscosity lowering effect cannot be seen, so that it is not suitable.
Further, the blending ratio of the synthetic rubber with respect to the entire hot-melt sealing material is preferably 12 to 60% by weight in order to ensure a predetermined melt viscosity, heat resistance, adhesive strength and the like.

The tackifying resin is blended for the purpose of ensuring adhesion to an adherend, ensuring adhesion, lowering melt viscosity and extending open time.
Specific examples include rosin, hydrogenated rosin, polymerized rosin, rosin derivatives such as rosin ester, terpene resins such as α-pinene, β-pinene, limonene, terpene phenol resin, coumarone-indene resin, styrene resin, xylene resin. Phenolic resins, petroleum resins, hydrogenated petroleum resins, and the like.
As for the compounding ratio with respect to the whole hot-melt-type sealing material of tackifying resin, 10 to 50 weight% is preferable. If it is less than 10% by weight, adhesion to the adherend and adhesion cannot be obtained. On the other hand, if it exceeds 50% by weight, the heat resistance is lowered, which is not suitable.

The liquid resin is blended to impart fluidity, coating property, dischargeability, adhesiveness, etc. to the hot melt sealant. Specific examples include polybutene, polybutadiene, polyisobutylene, isobutylene / isoprene-based co-polymers. Polymer, and the like.
These number average molecular weights of 500 to 5000 are preferably selected from the viewpoints of heat resistance, fluidity, coatability and the like.
The blending ratio of the liquid resin with respect to the entire hot-melt sealant is preferably 5 to 30% by weight. If it is less than 5% by weight, adhesion to the adherend and adhesion cannot be obtained, and fluidity at the time of melting also decreases. On the other hand, if it exceeds 30% by weight, the heat resistance is lowered, which is not suitable.

  Examples of flame retardants include phosphorus-based flame retardants, melamine or melamine derivatives, and metal hydroxides. In the present invention, it has been confirmed that the combined use of phosphate ester and melamine or melamine derivatives is effective. ing.

Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, dimethyl Examples include ethyl phosphate, methyl dibutyl phosphate, ethyl dipropyl phosphate, hydroxyphenyl diphenyl phosphate, and the like.
Among these, it has been found that the flame retardant effect of phosphate esters such as triphenyl phosphate, tricresyl phosphate, and various aromatic condensed phosphates having a phosphorus content of 7 to 30% by weight is remarkable. Yes.

Examples of the melamine derivative include melamine cyanurate, melamine isocyanurate, melamine phosphate, melamine sulfate, benzoguanamine, acetoguanamine, homoguanamine and the like.
Among them, it has been proved that the flame retardant effect is remarkable when the nitrogen content such as melamine is 20 to 70% by weight.

  Further, the phosphoric acid ester alone cannot realize a hot melt sealant that passes the UL94 standard V-0 or V-1, which is the object of the present invention, and has a phosphorous content of 7 to 30% by weight. Has been confirmed to pass UL94 standard V-0 or V-1 with a melamine or melamine derivative having a nitrogen content of 20 to 70% by weight or more and 5% by weight or more. If the phosphate ester is added in excess of 40% by weight or more, the plastic effect against hot melt becomes strong, adversely affects the physical properties such as heat resistance, and increases the cost. Moreover, about melamine and a melamine derivative, when the addition amount exceeds 30% by weight, the increase in powder viscosity and the hardness become too high due to an increase in powdery components, such being undesirable.

The anti-aging agent is blended in order to prevent thermal deterioration during the preparation of the hot-melt sealant and during operations such as coating or sealing. Specific examples thereof include phosphites, naphthylamines, P-phenylenediamines, quinolines, hydroquinones, bis-tris-polyphenols, thiobisphenols, hindered phenols, and the like. These anti-aging agents can be used alone or in combination. Among these, phosphites and phenols are suitable for preventing aging of the hot-melt sealing material of the present invention.
The blending ratio of the antioxidant to the synthetic rubber is preferably 0.1 to 5% by weight. If it is less than 0.1% by weight, the hot melt sealant is undesirably deteriorated by heat.

  As the wax, those having a softening point of 150 ° C. or higher are used as appropriate. Specific examples include synthetic waxes such as polyethylene wax, polypropylene wax, Fuchsia Tropsch wax, paraffin wax, microcrystalline wax, carnauba natural wax, beeswax, whale wax. And natural wax.

  In addition, fillers and the like can be appropriately blended as necessary. As the filler, general fillers used for paints and adhesives such as talc, clay, silica, calcium carbonate, and titanium oxide are used.

  The hot-melt sealing material according to the present invention is prepared by heating and kneading each compounding material with a Banbury mixer, a heating kneader, a biaxial extruder, etc., and cast into a mold to form various shapes, or extrusion molding Can be formed into a string or the like.

Specific examples of applying the hot-melt sealing material of the present invention include, for example, a case where filling and sealing are performed in gaps and grooves between connecting portions between members, gaps between laminated surfaces between members, and the like.
If the melt viscosity is too high at the time of such a filling seal, the coating property and the discharge property are lowered and the workability is deteriorated. Also, heating to 200 ° C. or higher in order to lower the melt viscosity is not preferable because the thermal deterioration becomes severe. For this reason, it is preferable that the melt viscosity at 200 ° C. is 150 Pa · s or less.

  Hand gun type, block melt type, bulk type and foam type can be used as the application equipment for hot melt type sealant, and commercially available products such as Nordson's bulk melter BM-505 and the company's foam melt applicator FM-151, etc. There is.

  In addition, when mass-manufacturing workpieces at a factory, if the head part of a hot melt application device is attached to an industrial robot, etc., even complex shapes can be applied quickly, resulting in significant production efficiency. Improvement can be expected.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

The hot-melt sealants of Examples and Comparative Examples of the present invention were prepared as follows.
Butyl rubber # 065 (manufactured by Nippon Butyl Co., Ltd.) having a degree of unsaturation of 0.8%, Mooney viscosity of 32 (ML1 + 8, 125 ° C.), Septon 2063 (manufactured by Kuraray Co., Ltd.) as a SEBS block copolymer, and water as a tackifying resin Petroleum resin Escoretz ECR227E (manufactured by Tonex Co., Ltd.), polybutene HV300 (manufactured by Nippon Oil Co., Ltd., average molecular weight 1400) as a liquid resin, polyolefin wax Biscol 550P as a wax, softening point 152 ° C., and phenolic antioxidant as an antioxidant Sumilizer GA80 (manufactured by Sumitomo Chemical Co., Ltd. CAS-NO90498-1), PX-200 (produced by Daihachi Chemical Co., Ltd., aromatic condensed phosphate ester) with a phosphorus content of 9% by weight as a phosphate ester flame retardant, nitrogen-containing 67% by weight of melamine (Nissan Chemical Industries Formula company), PHOSMEL-200 (manufactured by Nissan Chemical Industries, Ltd.), which is a melamine polyphosphate having a phosphorus content of 14% by weight and a nitrogen content of 38% by weight as a melamine derivative, and heated and mixed with a sigmalide type kneader. The hot-melt sealants of Examples and Comparative Examples shown in Table 1 were prepared. Table 1 shows the performance of the hot-melt sealants of Examples and Comparative Examples.

Note Cf: cohesive failure, Af: interface failure

４．引張試験
幅１０ｍｍ、長さ５０ｍｍ、厚み４ｍｍに成形したホットメルトを所定温度において３０分間養生したのち、長さ方向に５００ｍｍ／分で引張り、抗張力（ＭＰａ）、破断伸び（％）、弾性率（ＭＰａ）を求める。
５．耐熱性 垂直に支持したアルミ板に各辺が１０ｍｍとなる正六面体に成形したホットメルト系シーリング材を１００℃に加熱した状態で密着させ、１００℃にて２４時間静置したのち、ずり落ち距離をクリープとして評価する。
６．接着力 厚み１ｍｍ、溝幅５ｍｍ×溝高さ５ｍｍ×長さ５０ｍｍの略Ｕ型のアルミ製フレームに２００℃で溶融したホットメルト系シーリング材を充填し、冷却・固化後に１００℃で１０分間再加熱し、３０秒以内に厚み３ｍｍ×幅２５ｍｍ×高さ５０ｍｍのガラス片を厚み方向に溝内に３ｍｍまで挿入し、冷却して試験片とする。２３℃雰囲気下で３日間養生したのち引張速度５０ｍｍ／分にて強制破壊して破壊状態を観察、測定する。 Measuring method 1. Melt viscosity Melt viscosity According to JISK6862 (1984 version), melt viscosity (Pa · s) at 200 ° C. is measured using a DV-I type rotational viscometer manufactured by BROOKFIELD and a thermocell system. The rotor used was No. 29, the rotation speed was 5 rpm. The measurement procedure is to insert a standard amount of hot melt recommended by the manufacturer into a plug dedicated to hot melt, and then insert the plug into a thermocell that has been temperature-controlled at 200 ° C in advance. After 20 minutes, insert the rotor and then 20 minutes. After the lapse of time, the value after 20 minutes from starting to rotate the rotor was used.

Test / Evaluation Method Coating properties
Using a tank type applicator MX-4412 manufactured by Nordson, when the set temperature of the grid, reservoir tank, hose, and gun is all 200 ° C or less, it is evaluated as ○ when it can be stably applied, and when it is not possible as × did.
3. UL94
Perform a vertical combustion test.
The outline is described below.
The test specimen must not exceed a length of 125 ± 5 mm, a width of 13.0 ± 0.5 mm and a maximum thickness of 13 mm. If the test results of the minimum and maximum thickness test pieces do not agree, the test of the intermediate thickness test piece must also be performed. The intermediate thickness is specified not to be more than 3.2 mm thicker than the minimum thickness. The end face is smooth and the radius of the corner is 1.3 mm at maximum. One set of five test pieces is clamped at 6 mm from the top of the test piece as shown in FIG. 1 so that the long axis is vertical and the lower end of the test piece is 300 ± 10 mm above the absorbent cotton. Absorbent cotton has a maximum thickness of 6 mm and is expanded to 50 mm square and has a mass of 0.08 g or less. The upper end of the burner cylinder is 10 ± 1 mm from the lower end of the test piece, a flame is applied to the center of the lower end of the test piece, and the distance is maintained for 10 ± 0.5 seconds. If there is a change in the length or position of the specimen, move the burner as necessary. If there is a molten fallen or flammable fallen object in contact with the flame, in order to prevent the fallen object from entering the burner cylinder while maintaining the distance between the upper part of the burner and the test piece at 10 mm, Tilt the burner to 45 °. However, thread-like molten fallen objects are ignored. After 10 ± 0.5 seconds of indirect flame on the test piece, the burner is moved away from the test piece at a speed of about 300 mm / second at a location of 150 mm or more, and the afterflame time t1 is measured at the same time. When the after flame of the test piece disappears, even if the burner is not separated by 150 mm, immediately return the burner to the bottom of the test piece so that the upper end of the burner tube is at 10 ± 1 mm from the rest of the test piece. Indirect flame for 10 ± 0.5 seconds. After the flame contact, the burner is moved away from the test piece at least 150 mm in about 0.5 seconds, and after flame time after flame t2, and afterglow time t3 are measured. When checking the difference between flaming combustion (Flaming) and red-hot combustion (Glowing), apply 50mm square absorbent cotton to the problem area with tweezers, and ignite the absorbent cotton I reckon. The criteria for passing V-0, V-1, and V-2 are shown in Table 2.
Table 2 shows the evaluation criteria.
t1, t2: Afterflame time of each test piece (number of test pieces N5) (seconds)
(T1 + t2): Sum of total afterflame time of one set of test pieces for each conditioning condition (t2 + t3): Sum of afterflame time and residual time of each test piece after the second flame contact Reach: Whether the flame reaches the clamp without extinguishing The fallen object ignites the cotton: Whether the fallen object ignites when it touches the cotton laid on the bottom

4). Tensile test A hot melt molded to a width of 10 mm, a length of 50 mm, and a thickness of 4 mm is cured at a predetermined temperature for 30 minutes, and then stretched at 500 mm / min in the length direction, tensile strength (MPa), elongation at break (%), elastic modulus ( MPa).
5. Heat resistance A hot-melt sealing material molded into a regular hexahedron with sides of 10 mm is attached to a vertically supported aluminum plate in a state of being heated to 100 ° C., left at 100 ° C. for 24 hours, and then the sliding distance Is evaluated as creep.
6). Adhesive strength Filled with an approximately U-shaped aluminum frame with a thickness of 1 mm, groove width 5 mm x groove height 5 mm x length 50 mm, and a hot-melt sealing material melted at 200 ° C, cooled and solidified for 10 minutes at 100 ° C. A glass piece having a thickness of 3 mm, a width of 25 mm and a height of 50 mm is inserted into the groove in the thickness direction up to 3 mm within 30 seconds and cooled to obtain a test piece. After curing in a 23 ° C. atmosphere for 3 days, the fracture state is observed and measured by forcibly breaking at a tensile speed of 50 mm / min.

    The hot-melt sealing material according to the present invention is excellent in adhesion to an adherend, coating property, heat resistance, etc., and has a melt viscosity at 200 ° C. of 150 Pa · s or less and is easy to use, as a flame retardant. By adding phosphate ester and melamine or melamine derivative, it achieves flame retardancy that passes UL94 standard V-0 or V-1, and can be used safely in applications such as electronic equipment, vehicles, and architecture. .

Schematic diagram of vertical combustion test

Claims (3)

A hot-melt sealing material containing at least a synthetic rubber and having a melt viscosity at 200 ° C. of 150 Pa · s or less and containing a phosphate ester and melamine or a melamine derivative as a flame retardant. The hot-melt sealant according to claim 1, comprising 5% by weight or more of phosphate ester and 5% by weight or more of melamine or melamine derivative. 3. The hot melt sealing material according to claim 1, wherein the synthetic rubber is made of butyl rubber or styrene block polymer.

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