JP2009185266A - Flame-retardant adhesive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that it is difficult to allow a flame-retardant hot melt to simultaneously have both of original flame retardancy and adhesion because the adhesion is reduced although the flame retardancy is enhanced when the blending ratio of a flame retardant to a base resin is increased, and on the other hand, the flame retardancy is reduced although the adhesion is enhanced when the blending ratio of the flame retardant to the base resin is reduced. <P>SOLUTION: A flame-retardant adhesive material comprises a couple of compositions composed of a flame retardant composition containing a thermoplastic resin as a base material and a non-halogen flame retardant and an adhesive composition containing a thermoplastic resin as a base material, wherein the couple of compositions form a multilayer coating film in which the flame-retardant composition is used as an undercoat (first) layer and the adhesive composition is used as a topcoat (second) layer by utilizing the blending ratio of the flame retardant to the base resin and coating film properties. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention, as a material to be applied to various electromagnetic shielding materials for shielding electromagnetic waves generated from electronic devices, etc., particularly high flame retardant performance without the generation of toxic dioxins during combustion like halogen compounds. The present invention relates to a flame retardant adhesive material having adhesive performance at the same time.

  Measures against the effects of electromagnetic waves generated in various directions such as industrial equipment, medical equipment, household appliances, etc., that is, various cases represented by electromagnetic shielding gaskets in casings and their opening / closing mechanisms as EMI countermeasures Shield material is attached. In general, electronic devices are further miniaturized, and are often stored in a semi-sealed state in a housing or the like. Therefore, heat storage is easy, and in order to prevent fire and improve safety, all parts related to the device body Therefore, flame retardancy is required, and it is necessary to satisfy UL94, V-0 in the UL standard as an index.

  As a material for making a shielding material such as an electromagnetic shielding gasket flame-retardant, a halogen-based flame retardant having particularly high flame retardancy has been often used until recently. However, since halogen-based flame retardants generate toxic dioxins at 300 to 600 ° C. during combustion and cause environmental pollution, their use is greatly limited. Currently, halogen-free flame retardants are used at a high diffusion rate.

As flame retardant materials replacing halogen compounds, phosphorus-based compounds, aluminum compounds, magnesium compounds, expandable graphite, antimony compounds, and other non-halogen flame retardant materials have been put into practical use. However, antimony compounds are no longer used because they are toxic to the human body. In addition, in order to increase the flame retardancy, it is difficult to obtain a flame retardance comparable to that of halogen compounds even if a combination of multiple flame retardant materials is combined to achieve a synergistic effect, unless the amount is significantly increased. The expected flame retardant effect cannot be obtained, and in that case, it is necessary to add a large amount to the base material (base) resin.
JP 2007-203726 A

  Patent Document 1 is based on the proposal of the present applicant, and improves the flame retardancy and does not contain expansive graphite in the composition. Therefore, each flame retardant is well dispersed in the resin medium. Efficiency can be improved, and in addition, even when the coating thickness is increased, a high-quality conductive fabric can be obtained without generating coating stripes.

  As an electromagnetic shielding material, for example, an electromagnetic shielding gasket is formed by winding a conductive cloth around the outer periphery of a resin foam. An adhesive layer such as hot melt is often formed on one side of the core side of the conductive fabric. In order to impart flame resistance to the electromagnetic shielding gasket, it is necessary to make the conductive fabric flame retardant, and a flame retardant hot melt layer is coated on one side of the core material of the flame retardant conductive fabric. It is crafted.

  As the performance to be provided by the hot melt, the above-mentioned flame retardancy as well as the original adhesiveness is extremely important. As hot melt, for example, an organic solvent is added to a base resin such as polyurethane as a base to adjust the viscosity, and a non-halogen flame retardant such as expansive graphite, metal hydroxide, or a phosphorus-containing compound is added. A kneaded product is used. However, when non-halogen flame retardants are used to impart flame retardancy to hot melts, a combination of multiple types of flame retardants and a combination of these flame retardants in a large amount with respect to the base resin, It is difficult to impart flame resistance comparable to that of a series flame retardant.

  As the function of the hot melt, the inherent adhesion as well as the above-mentioned flame retardancy is extremely important, and it must be provided without impairing these performances. However, when a non-halogen flame retardant is used as a flame retardant for hot melt, it requires about twice the amount of the flame retardant compared to the halogen flame retardant. The property (heat-adhesion performance of hot melt) is greatly impaired. In addition, the moldability, heat resistance, moisture resistance, or flexibility and resilience inherent in the base resin itself are impaired, the physical properties required for the electromagnetic shielding gasket are impaired, and the original use as a hot melt It may not be suitable for use, or durability may be reduced.

  The flame retardant composition described in Patent Document 1 proposed by the applicant of the present application has high flame retardancy when the proportion of the flame retardant solids in the composition is increased, but the adhesiveness is low. When the amount is decreased, the adhesiveness is increased, but the flame retardancy is lowered, and one of the characteristics is lost, and it has been found difficult to simultaneously combine the original flame retardancy and the adhesiveness.

  The present invention is intended to solve the above-described problems of the prior art, and provides a flame retardant adhesive material having both high flame retardant performance and adhesive performance.

(First feature of the present invention)
Composed of a flame retardant composition containing a non-halogen flame retardant material based on a thermoplastic resin, and an adhesive composition based on a thermoplastic resin, the flame retardant composition as an undercoat layer, and the adhesiveness It is characterized by comprising a pair of these compositions that form a multilayer film with the composition as an overcoat layer.

(Second feature of the present invention)
The adhesive composition based on the thermoplastic resin contains a non-halogen flame retardant substance, and the flame retardant substance is the same material as the flame retardant substance contained in the flame retardant composition. And the blending ratio of the flame retardant is not more than the blending ratio included in the flame retardant composition.

(Third feature of the present invention)
Each thermoplastic base resin constituting the flame retardant adhesive material is a polyurethane resin, and the flame retardant substance is a mixed flame retardant containing a plurality of polyphosphoric acid compounds, metal hydroxides, and red phosphorus. In addition, a material containing 300 parts by weight or more of the mixed flame retardant with respect to 100 parts by weight of the non-volatile content is used as the flame retardant composition, and a material containing 150 parts by weight or less is used as the adhesive composition. It is characterized by.

(Fourth feature of the present invention)
The flame-retardant adhesive material is a hot melt adhesive for an electromagnetic shielding gasket.

  The non-halogen flame retardant substance in the adhesive composition based on the thermoplastic resin constituting the flame retardant adhesive material is the same kind as the flame retardant substance contained in the flame retardant composition and in a smaller proportion thereof. It is characterized by containing.

  The flame retardant adhesive material is a hot melt adhesive for electromagnetic shielding gaskets. These thermoplastic base resins are made of polyurethane resin, and the flame retardant is a mixture containing polyphosphoric acid compound, metal hydroxide and red phosphorus. The flame retardant composition is a mixture of 300 parts by weight or more of the mixed flame retardant with respect to 100 parts by weight of the base resin, and the adhesive composition is a mixture of 150 parts by weight or less. The flame-retardant adhesive material according to claim 1.

  The present invention relates to a resin for an undercoat (first layer) applied to the surface of an electroconductive cloth in an electromagnetic wave shielding gasket in which an electroconductive cloth is wound around and adhered to an outer periphery of an electromagnetic shielding material, mainly a core material such as a resin foam. By combining the flame retardancy of the composition and the adhesiveness of the resin composition for the top coat (second layer) and sharing the respective performances, the halogen-based compound does not deteriorate either the flame retardancy or the adhesiveness. It is possible to obtain a high degree of flame retardancy that is not inferior to a flame retardant and the original adhesiveness of the base resin. In addition, a highly safe electromagnetic shielding gasket can be obtained without generating toxic substances during combustion, such as halogen compounds.

  In the flame-retardant adhesive material of the present invention, the ratio of the flame retardant added to the resin composition as a whole is minimal, and the amount of phosphate ester only needs to act as a plasticizer. A stable state can be maintained over a long period of time without causing bleeding (peeling) or blocking (sticking) on the surface layer when applied.

  The best mode of the present invention will be described. The flame-retardant adhesive material of the present invention is applied to an adhesive for hot melt (thermal fusion) when a conductive cloth is wound around and joined to the outer periphery of a synthetic resin foam, particularly in an electromagnetic shielding gasket. Examples of the thermoplastic polymer resin compound used as a base material include urethane resins using polyether type polyols and isocyanates, or polyester type polyols and isocyanates, polyacrylic ester acrylic resins, polyethylene terephthalate, polybutylene terephthalate, etc. Polyester resin and the like. Among them, urethane resin or acrylic resin is preferable because of excellent compatibility and dispersibility with each flame retardant targeted in the present invention, and good workability when applied as a resin composition, and urethane resin is particularly preferable. Can be used.

  The flame-retardant adhesive material of the present invention is composed of a pair of a flame-retardant composition for the undercoat (first) layer and an adhesive composition for the topcoat (second) layer, and the resin used for these May be the same or different. However, since sufficient adhesion is required between the undercoat (first) layer and the overcoat (second) layer, it is preferable to select from the same type because it increases the affinity. .

  In blending a flame retardant described later, a resin material such as a urethane resin is required to be in a liquid state that is easy to apply. For example, as an organic solvent solution having a resin solid content of 35 to 40%, toluene, xylene, acetone, Commercially available products whose viscosity is adjusted to about 3000 mPa · s with an organic solvent such as methyl ethyl ketone, diethyl ketone, and dimethylformamide can be used. Since the viscosity of the resin solution is increased by blending a flame retardant and spontaneous evaporation, the viscosity is adjusted by appropriately diluting the resin solution using the organic solvent.

  Typical examples of the polyphosphate compound used as a flame retardant material include ammonium polyphosphate, melamine polyphosphate, cyanurate polyphosphate, and the like. Among them, ammonium polyphosphate has a high content of phosphorus (P) as an element. It can be preferably used because it is inexpensive. When the blending amount decreases, the flame retardancy decreases, and when it increases, the original physical properties of the resin tend to decrease and become brittle.

  As a metal hydroxide used as a flame retardant substance, it can select from 1 or more types of metal elements, such as calcium, magnesium, aluminum, and zinc, and the hydroxide. Of these, aluminum hydroxide and magnesium hydroxide are effective as flame retardant materials and can be suitably used because they are relatively inexpensive. When the blending amount decreases, the flame retardancy decreases, and when it increases, the original physical properties of the resin tend to decrease and become brittle.

In addition to these flame retardant materials, it is preferable to use red phosphorus and aluminum hydroxide in combination.
In particular, red phosphorus is preferable because it promotes carbonization and promotes the oxygen-blocking effect, and when used in combination with aluminum hydroxide, it exhibits effective flame retardancy in synergy with its anti-dripping action. Also, it is more preferable to use red phosphorus whose periphery is coated with commercially available aluminum hydroxide, since the same effect can be brought about and the amount of the flame retardant as a whole can be reduced. In that case, the toxic phosphine gas generated by the combustion of phosphorus can be suppressed.

  A plasticizer for increasing the adhesiveness is blended with the flame retardant material as necessary. Among these, phosphate esters having both plasticity and flame retardancy are very suitable materials for blending the flame retardant adhesive material of the present invention.

  As phosphate esters, known compounds such as triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, xylenyl diphosphate can be used. It is preferable to use a condensed phosphate ester. In addition, since the condensed phosphate ester has a large molecular weight, it is less likely to bleed (bleed out) when applied to fibers such as fabrics, and has the effect of delaying the change over time, as compared with a low molecular weight phosphate ester. Typical examples of these include a reaction product of phosphorus oxychloride and a divalent phenol compound, a reaction product of phosphorus oxychloride and an alkylphenol, and the like. When the blending amount is large, the polymer resin compound tends to be extremely softened, and it is not preferable because it causes bleeding and blocking (sticking of overlapping portions of fabrics).

  The flame-retardant adhesive material of the present invention is composed of a pair of a flame-retardant composition for a primer layer (first layer) having a high flame retardancy and an adhesive composition for a primer layer (second layer) having a high adhesive property. To do. In other words, by sharing the functions of the flame retardant composition for the undercoat and the adhesive composition for the top coat, the flame retardant composition is added to the flame retardant composition for the undercoat despite the addition of a large amount of flame retardant. High flame resistance comparable to that of halogen-based flame retardants, despite the fact that the adhesiveness of the adhesive material itself is not impaired and the amount of flame retardants in the adhesive composition for top coating is kept low. It has the property and adhesiveness.

  In the flame retardant adhesive material of the present invention, the blending ratio of the flame retardant substance can be reduced, and even if a phosphate ester is supplementarily added as a plasticizer, the amount becomes extremely small. For this reason, it is possible to maintain a stable state over a long period of time without causing bleeding (bleeding) or blocking (sticking) on the surface layer applied to the fabric.

  When manufacturing flame-retardant metal-coated fabrics or metal-coated sheets, these fabrics are spread on a flat surface, and a flame-retardant composition for undercoating is applied onto the fabric while coating to a predetermined thickness. A fabric coated with a flame retardant composition by adjusting the height of the coating thickness adjusting device, running the device along the upper surface of the fabric, and then drying by heating. Is obtained. When the adhesive composition for topcoat is applied, the coating is performed according to the case of applying the flame retardant composition for undercoat. A well-known thing can be used for a coating machine. The thickness of the resin composition applied to the conductive fabric for the electromagnetic shielding gasket is 30 to 300 μm as a non-volatile component in the case of the flame retardant composition for the undercoat (first) layer, and for the overcoat (second) layer. In the case of this adhesive composition, the nonvolatile content is preferably about 5 to 50 μm.

  When coating on a fibrous fabric, since there are many flame retardants contained in the composition for the undercoat (first) layer, it is used as a sealant when applying the composition for the top coat (second) layer. Is more preferable since the coating thickness becomes uniform. A coating machine such as a comma roll may be used for coating in this case.

Evaluation test of adhesion and flame retardancy of flame retardant adhesive material Adhesion and verification of flame retardance were performed as follows. That is, when the blending ratio of the flame retardant with respect to the base resin is decreased, the flame retardance is lowered although the adhesion is increased, and when it is increased, the flame retardancy tends to be increased although the adhesion is low. Experiments were carried out to verify the blending area appropriate to the physical properties and purpose of the product.

1. Mixing ratio of flame retardant adhesive composition and verification of effects on flame retardancy and adhesiveness (1) Blending of flame retardant composition MEK (methyl ethyl ketone) solution of polyurethane resin (Sakai Kogyo Co., Ltd., U-826) (Non-volatile content 35% by weight). Then, the viscosity was adjusted to 4000 mPa · s (unit: millipascal) by MEK.
Note that the flame retardant is a mixture of three types of flame retardants, and was adopted from the following composition having the most flame retardant effect in the preliminary test results by the present inventors.
Flame retardant and mixing ratio Ammonium polyphosphate: manufactured by Clariant Japan Co. Magnesium hydroxide: manufactured by Kamishima Chemical Industry Co., Ltd. Red phosphorus flame retardant: manufactured by Nippon Chemical Industry Co., Ltd. And this ammonium polyphosphate: magnesium hydroxide: red phosphorus system flame retardant It was mixed at a ratio of 4: 3: 3 (weight ratio).

(2) Formation of a flame retardant simulated adhesive layer on a conductive fabric A conductive fabric obtained by applying two layers of copper and nickel to a fabric obtained by plain weaving polyester fiber yarn as a fabric material (SUI-13, manufactured by Seiren Co., Ltd.) -315M, thickness 80 μm). Next, after coating on one side of this conductive fabric using a coating machine, it was dried at a temperature of 110 ° C. to form a flame-retardant simulated adhesive layer having a thickness of about 60 μm.

(3) Production of EMI (for electromagnetic wave shielding) gasket Polyurethane resin foam (manufactured by Achilles Co., Ltd., NZH) was sliced with a slicer into a long string-like foam piece (width 13 mm, height 3.5 mm). The conductive fabric on which the flame-retardant simulated adhesive layer was formed was joined by heat molding (production machine) to produce an EMI gasket.

(4) Flame Retardancy Test of Flame Retardant Simulated Adhesive Layer Table 1 shows the results of a flame retardant test performed on the EMI gasket based on the UL standard. Experiment No. 5 and no. No. 6 was excluded from the flame retardant test because the adhesive performance between the flame retardant simulated adhesive layer coated on the surface of the conductive fabric and the foam piece was low and it was difficult to maintain the shape as an EMI gasket.
For this reason, Experiment No. 5 and no. For No. 6, a flame retardant test based on the UL standard was performed on a sheet obtained by sequentially coating a flame retardant composition for undercoating and an adhesive composition for top coating on a conductive fabric before forming an EMI gasket.

（注）
（１）接着性および難燃性の評価：
○ 良好 △ 十分ではない × 不良
（○） 各組成物塗工後の生地（シート状）について難燃性試験の結果良好
（２）難燃性試験
前記したとおり、実験Ｎｏ．５、およびＮｏ．６の組成物は発泡体に対して接着性 が低く、ＥＭＩガスケットとしての形状維持が困難であるため除外した。(5) Adhesion Test of Flame Retardant Simulated Adhesive Layer With respect to the EMI gasket, the adhesion test between the flame retardant simulated adhesive layer on the surface of the conductive fabric and the foam piece was conducted in each experiment No. After applying the flame retardant simulated adhesive shown in Fig. 5 on the conductive fabric and allowing it to stand naturally for 48 hours after forming the film, the temperature setting for the thermoforming of the production machine is set to 150 ° C and 200 ° C, The state of adhesion / peeling was verified. The results are shown in Table 1.

(note)
(1) Evaluation of adhesion and flame retardancy:
○ Good △ Not enough × Poor (○) Good result of flame retardant test for fabric (sheet-like) after coating each composition (2) Flame retardant test As described above, Experiment No. 5 and no. The composition of No. 6 was excluded because of its low adhesion to the foam and it was difficult to maintain its shape as an EMI gasket.

  From the above test results, it was found that in order to satisfy the UL standard V-0, it is necessary to blend 300 parts by weight or more of the flame retardant with respect to 100 parts by weight of the base resin. In addition, those blended with 300 parts by weight or more of the flame retardant with respect to 100 parts by weight of the base resin, particularly 400 parts by weight, were easily peeled off from the test at each temperature and had low adhesion. On the other hand, it became clear that what mix | blended 300 parts or less of flame retardants with respect to 100 weight part of base resin has favorable adhesiveness also in the test in each temperature.

（注）
（１）接着性および難燃性の評価：
○ 良好 △ 十分ではない × 不良2. Formation of a flame retardant adhesive layer comprising a multilayer coating As a result of verifying the blending ratio of flame retardant adhesive composition and the effect on flame retardancy and adhesiveness, by changing the blending ratio of flame retardant to base resin, each characteristic of flame retardancy and adhesiveness can be changed. It turns out that it can be pulled out. For this reason, in the composition shown in Table 1, it was found that the range in which the flame retardance effectively appeared was layered as the flame retardant layer, and the range in which the adhesive property was effectively manifested as the adhesive layer. Therefore, from each experimental result shown in Table 1, the experiment No. 5 and no. No. 6 was applied to the undercoat (first) layer applied to the conductive fabric, and the test No. 1 had high adhesion. 1 and no. A test was conducted to verify that 2 was combined as an overcoat (second) layer and formed as a multi-layer to simultaneously have flame retardancy and adhesiveness. Table 2 summarizes the blending ratio and performance test results.

(note)
(1) Evaluation of adhesion and flame retardancy:
○ Good △ Not enough × Bad

  From the above test results, by forming a multilayer with the flame retardant layer and the adhesive layer, it was possible to draw out the characteristics possessed in the respective blending ratios, and the adhesiveness and flame retardancy were satisfactory.

Claims (4)

  Composed of a flame retardant composition containing a non-halogen flame retardant substance based on a thermoplastic resin, and an adhesive composition based on a thermoplastic resin, the adhesive composition comprising the flame retardant composition as an undercoat layer A flame-retardant adhesive material comprising a pair of these compositions that form an overcoat layer with an article as an overcoat layer.   The adhesive composition contains a non-halogen flame retardant substance in an adhesive composition based on a thermoplastic resin, and the flame retardant substance is contained in the flame retardant composition. The flame-retardant adhesive material according to claim 1, wherein the flame-retardant adhesive material is made of the same kind of material as that of the substance, and the blending ratio of the flame-retardant substance is not more than the blending ratio contained in the flame-retardant composition.   Each thermoplastic base resin constituting the flame retardant adhesive material is a polyurethane resin, and the flame retardant substance is a mixed flame retardant containing a plurality of polyphosphoric acid compounds, metal hydroxides, and red phosphorus. In addition, a material containing 300 parts by weight or more of a mixed flame retardant with respect to 100 parts by weight of the non-volatile content is defined as a flame retardant composition, and a material containing 150 parts by weight or less is defined as an adhesive composition. Claim | item 1 and claim | item 2 flame retardant adhesive material.   The flame retardant adhesive material according to claim 1, wherein the flame retardant adhesive material is a hot melt adhesive for an electromagnetic shielding gasket.