JP2006232954A - Flame-retardant resin composition and metal pipe coated with resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flame-retardant resin composition capable of being used as a protective resin, by being coated on a surface of a metal pipe which is used for transporting a fluid, such as a gas, and having excellent resistance to oils at a high temperature and flame retardancy. <P>SOLUTION: This flame-retardant resin composition is given by adding magnesium hydroxide used as a flame retarder in an amount of 20-50 pts.mass to 100 pts.mass of a base resin which comprises 40-60 pts.mass of a thermoplastic crosslinked resin and 60-40 pts.mass of at least one of resin selected from an ethylene-ethyl acrylate copolymer and an ethylene-vinyl acetate copolymer. Thus, the resin composition attains good characteristics. Especially, the composition attains high resistance to warm oils, suitable flexibility (pliability), excellent flame retardancy, high resistance to scuffing, excellent sheath-cutting properties and sheath-drawing properties, etc., when the composition is used as a resin coating material for a gas pipe, etc. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flame retardant resin composition for coating a surface of a metal tube for carrying a gas such as a gas or a fluid such as a liquid as a protective resin, and a resin-coated metal tube.

  Conventionally, in a metal pipe such as a gas pipe, a vinyl chloride resin (PVC) or a polyolefin resin is used as a protective resin coating.

  However, in the case of PVC, there is a problem that toxic gas is discharged in the event of a fire or the like due to chlorine atoms contained in the resin. Of course, there was a problem that toxic gas was discharged even during the incineration of metal pipes due to the disposal of equipment. In addition, since PVC often uses lead-based stabilizers, even when landfilling is performed, there is a risk that lead will be eluted into the ground and cause soil contamination.

  In this regard, polyolefin resin materials do not have chlorine atoms in the resin, so there is no risk of generating toxic gases during a fire or incineration process, but there is a problem of damage when exposed to high-temperature oil. It was.

Therefore, the present applicant pays attention to a polyolefin resin, in particular, a highly flexible ethylene-ethyl acrylate copolymer (EEA) and an ethylene-vinyl acetate copolymer (EVA), and these resin materials are used as a base resin. Appropriate amount of flame retardant magnesium hydroxide or calcium carbonate is added, while high-temperature oil resistance such as gas pipes (oil resistance performance that soaks in 155 ° C cooking oil for 10 seconds and does not cause defects such as cracking and tearing in the sheath) In order to cope with this, a relatively small amount of silane grafter (polyethylene or polypropylene grafted with silanol groups, 3 to 10 parts by mass) or thermoplastic cross-linked resin (ionomer or RC resin) with respect to 100 parts by mass of the base resin Etc.) to which 5 to 20 parts by mass) are added (Patent Document 1).
JP 2004-137462 A

  However, according to subsequent studies by the present inventors, even if more thermoplastic cross-linked resin (60-20 parts by mass) is added to EEA or EVA (40-80 parts by mass), good high temperature Oil resistance is obtained, moderate flexibility (softness) and excellent flame retardancy are obtained. In addition, it has trauma resistance, sheath cutability that allows easy and clean cutting of the sheath, and cut It has been found that excellent results can be obtained also in the sheath pull-out property that allows the sheath to be pulled out easily. In particular, for damage resistance, in the case of resin-coated metal pipes, such as resin-coated gas pipes, when the gas pipes are drawn indoors, they often rub against building materials such as concrete and wood in the facility. Are more likely to be damaged and stronger (higher) trauma resistance is desired.

  The present invention has been made in view of this point. Basically, an appropriate amount of EEA or EVA and a thermoplastic cross-linked resin are mixed to form a base resin, and flame retardant magnesium hydroxide or calcium carbonate is added to them. The present invention provides a flame retardant resin composition for protecting the surface of a metal tube added in an appropriate amount, and a resin-coated metal tube coated therewith.

  The present invention according to claim 1 comprises 40 to 60 parts by mass of a thermoplastic crosslinked resin and 60 to 40 parts by mass of at least one resin selected from an ethylene-ethyl acrylate copolymer or an ethylene-vinyl acetate copolymer. It exists in the flame-retardant resin composition characterized by adding 20-50 mass parts of magnesium hydroxide of a flame retardant with respect to 100 mass parts of base resin.

  The present invention according to claim 2 comprises 40 to 60 parts by mass of a thermoplastic crosslinked resin and 60 to 40 parts by mass of at least one resin selected from an ethylene-ethyl acrylate copolymer or an ethylene-vinyl acetate copolymer. It exists in the flame-retardant resin composition characterized by adding 16-48 mass parts of calcium carbonate of a flame retardant with respect to 100 mass parts of base resins.

  A third aspect of the present invention is a flame retardant resin comprising 0.5 to 3 parts by weight of a lubricant having a surface slipping action added to the flame retardant resin composition of the first or second aspect. In the composition.

  According to a fourth aspect of the present invention, there is provided a resin-coated metal tube, wherein the flame retardant resin composition according to the first, second or third aspect is coated on the outer periphery of a metal tube such as a gas tube.

  The present invention according to claim 5 resides in the resin-coated metal tube according to claim 4, wherein the metal tube is a flexible metal tube.

  According to the flame retardant resin composition of the present invention, a considerable amount (40 to 60 parts by mass) of the thermoplastic cross-linked resin is largely biased with respect to EEA and EVA (60 to 40 parts by mass) which are highly flexible resins. Without being mixed, the base resin material (100 parts by mass) has moderate flexibility, and the addition of the thermoplastic cross-linked resin increases the softening temperature of the entire base resin. can get. In other words, it has good high temperature oil resistance and moderate flexibility. Furthermore, it has a trauma resistance, a sheath cutability that can easily and cleanly cut the sheath of the sheath, and a sheath that can be easily pulled out. Good results are also obtained in pullability. Of course, the desired flame retardancy can be obtained by adding appropriate amounts of magnesium hydroxide and calcium carbonate, which are flame retardants.

  According to the resin-coated metal tube of the present invention, the resin coating layer (sheath) made of the flame retardant resin composition provides excellent high temperature oil resistance, trauma resistance, desired flame resistance, and moderate flexibility. In addition, excellent sheath cutability and sheath drawability can be obtained. In particular, in the case of a gas pipe, even when it is rubbed against a building member such as concrete or wood when it is drawn indoors, it can withstand damage due to its high resistance to trauma. In addition, when working on piping, the sheath can be easily cut with a sheath cutter due to excellent sheath cutability, and the covering of the cut portion can also be easily removed by hand due to excellent sheath pullability. it can. That is, it is possible to obtain a gas pipe that is easy to perform terminal construction and intermediate connection work. Of course, due to the non-halogen flame retardancy, no corrosive gas or dioxin gas is generated during combustion.

  FIG. 1 shows a resin-coated metal tube according to the present invention which is a normal pipe-shaped tube. In the figure, 1 is a metal tube made of stainless steel or the like, and 2 is a metal tube 1 coated on the outer periphery of the metal tube 1. It is the resin coating layer (sheath) which consists of a flame-retardant resin composition. 2 to 3 are flexible resin-coated metal tubes according to the present invention comprising corrugated tubes, in which 11 is a corrugated metal tube made of stainless steel, and 12 is this metal. 2 is a resin coating layer (sheath) made of the flame retardant resin composition of the present invention coated on the outer periphery of a tube 11. In the case of this flexible resin-coated metal tube, as shown in FIG. 3, the inner surface is corrugated in a direction (circumferential direction) perpendicular to the corrugated direction of the metal tube 11. A corrugated gap is formed between the resin coating layer 12 and the resin coating layer 12.

  The EEA used in the present invention has an ethyl acrylate content of 5 to 30% by mass and a melt flow rate (MFR, temperature 190 ° C., load 2.2 kg, time 10 minutes) of 0.1 to 5.0. Is preferred. Further, as EVA, it is preferable to use a material having a vinyl acetate content of 5 to 40% by mass and a melt flow rate (MFR, temperature 190 ° C., load 2.2 kg, time 10 minutes) of 0.1 to 5.0. .

  These EEA and EVA may be used independently or in combination. When mixing, the mixing ratio is not particularly limited and is arbitrary. These impart flexibility to the obtained flame-retardant resin composition.

  These thermoplastic cross-linked resins added to EEA and EVA are polymers that are pseudo-cross-linked using ionic bonds and the like and are thermoplastic. This pseudo-crosslinking can have a self-shape maintaining function even at a temperature of about 150 ° C. Examples of such a thermoplastic cross-linked resin include ionomers and RC resins (proposed by Nippon Polyethylene).

  The RC resin includes an ethylene copolymer (a) having ethylene and a radical polymerizable acid anhydride as essential components, a polyhydric alcohol compound (b) having two or more hydroxyl groups in the molecule, and a reaction accelerator. The ratio of the unit derived from the radically polymerizable acid anhydride in the ethylene copolymer (a) is 0.1 to 20% by mass, and the acid in the ethylene copolymer (a) The molar ratio of the hydroxyl group derived from the polyhydric alcohol compound (b) to the anhydrous group is in the range of 0.1 to 10, and the reaction accelerator (c) is 100 parts by mass of the ethylene copolymer (a). The resin composition which is the range of 0.001-20 mass parts is pointed out.

  As the radical polymerizable acid anhydride in the ethylene copolymer (a), one or more of maleic anhydride, ticonic anhydride, citraconic anhydride and the like are used. In addition, as the third monomer, acrylic acid esters such as methyl (meth) acrylate and ethyl (meth) acrylate, and fumaric acid esters such as methyl fumarate and ethyl fumarate may be copolymerized.

  Examples of the polyhydric alcohol compound (b) include ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolethane, and ethylene-hydroxy having two or more hydroxyl groups in the molecule. One or more types such as ethyl (meth) acrylate copolymer are used.

  As the reaction accelerator (c), a metal salt of a carboxylic acid or a metal salt of a polymer having a carboxyl group is used. Examples of metal salts of carboxylic acids include acetic acid, butyric acid, octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, succinic acid, benzoic acid, terephthalic acid, and other carboxylic acids, Metal salts with sodium, magnesium, calcium, zinc, aluminum and the like can be mentioned.

  In addition, as a metal salt of a polymer having a carboxyl group, a part or all of the carboxyl group of the ethylene- (meth) acrylic acid copolymer and lithium, sodium, potassium, magnesium, calcium, zinc, aluminum, etc. Examples thereof include a metal salt or a copolymer of ethylene and an ethylene- (meth) acrylic acid metal salt. Other examples of the reaction accelerator (c) include triethylamine, trimethylamine, tetramethylammonium tetrafluoroporate and the like.

  Specific examples of this thermoplastic crosslinked resin include “Lex Pearl RC801” (trade name, manufactured by Nippon Polyethylene Co., Ltd.), “TRC Polymer-GFA900” (trade name, manufactured by Mitsubishi Chemical Corporation), and the like. This thermoplastic crosslinked resin imparts heat resistance and the like to the obtained flame-retardant resin composition.

  This thermoplastic crosslinked resin is blended with EEA and EVA. First, EEA and EVA may be blended individually or in combination with the thermoplastic crosslinked resin, and the total blended part of both is 100 parts by mass. To do. That is, 60-40 parts by mass of at least one resin selected from EEA or EVA with respect to 40-60 parts by mass of the thermoplastic crosslinked resin.

  The reason is as follows. Since EEA and EVA are resin materials rich in flexibility, the greater the ratio, the greater the flexibility, while the lower the softening temperature, the lower the softening temperature of the base resin as a whole. It becomes a factor to decrease. On the other hand, the higher the proportion of the thermoplastic crosslinked resin due to its crosslinked structure, the higher the softening temperature of the entire base resin, and it can be expected to improve the resistance to external damage and heat.

  From this viewpoint, when the thermoplastic cross-linked resin is less than 40 parts by mass and EEA or / and EVA exceeds 60 parts by mass, the flexibility of the entire base resin is too large and the softening temperature is too low. This is because heat resistance, particularly high temperature oil resistance cannot be obtained. On the other hand, when the thermoplastic cross-linking resin exceeds 60 parts by mass and the EEA or / and EVA is less than 40 parts by mass, the softening temperature of the entire base resin increases, but the processability decreases.

  That is, when it is within the above blending range, the balance of characteristics is good, and appropriate flexibility is obtained together with heat resistance, particularly good high temperature oil resistance. Furthermore, as will be described later, it was cut even when it was in the external resistance (about 20 ° C.) or at a low temperature (about −5 ° C.), as well as being resistant to trauma, sheath-cutting ability to cut the sheath of the sheath easily and cleanly. Good results can also be obtained in the sheath pullability that allows the sheath to be pulled out easily.

  In order to make this base resin flame retardant, magnesium hydroxide or calcium carbonate, which has a high flame retardant effect and is a non-halogen flame retardant, is added. These flame retardants may be added as they are, but it is preferable to use those which have been subjected to a surface treatment in order to improve the flame retardancy, the sheath cutability and the sheath drawability. Examples of the surface treatment include silane coupling agents such as polyorganosiloxane, epoxy silane, vinyl silane, amino silane, and mercapto silane, fatty acids such as stearic acid and oleic acid, and titanium coupling agents such as isopropyl isostearoyl titanate. Is mentioned. The addition amount is desirably about 3 to 10% by mass with respect to 100 parts by mass of the base resin.

  The addition amount of magnesium hydroxide as a flame retardant with respect to 100 parts by mass of the base resin is 20 to 50 parts by mass. The reason is that if it is less than 20 parts by mass, sufficient flame retardancy of the resin composition cannot be obtained, and conversely if it exceeds 50 parts by mass, the mechanical properties of the resin composition will deteriorate. is there. On the other hand, the addition amount of calcium carbonate as a flame retardant with respect to 100 parts by mass of the base resin is 16 to 48 parts by mass. The reason is that if it is less than 16 parts by mass, sufficient flame retardancy of the resin composition cannot be obtained, and conversely if it exceeds 48 parts by mass, the mechanical properties of the resin composition will deteriorate. is there. Moreover, when the addition amount of a flame retardant shall be these ranges, the specific gravity of a resin composition can be made into the range of 1.02-1.18. When the specific gravity is within this range, it is possible to separate the specific gravity from the vinyl chloride resin composition or the polyethylene resin composition.

  In addition to these flame retardants, a flame retardant aid may be added. By adding the flame retardant aid, the amount of the flame retardant added can be reduced to lower the specific gravity of the resin composition and to suppress the deterioration of the mechanical properties. Examples of such flame retardant aids include silicone compounds such as silicone powder and silicone rubber, phosphorus compounds such as tricresyl phosphate, triphenyl phosphate, and ammonium polyphosphate, zinc borate, hydroxytin zinc, and zinc stannate. And zinc compounds such as melamine cyanurate, melamine, melam, and other nitrogen-containing organic compounds, red phosphorus, carbon black, and maleimide compounds such as N, N′-m-phenylene dimaleimide. And the addition amount should just add about 10 mass parts with respect to 100 mass parts of base resin as an upper limit.

  The flame retardant resin composition of the present invention thus obtained may be added with a lubricant having a surface slipping function, if necessary. Examples of the lubricant include stearic acid, stearic acid amide, oleic acid amide, erucic acid amide, silicone oil, polyethylene wax, EVA wax, metal soap, paraffin oil and the like. And the addition amount is good to set it as about 0.5-3 mass parts with respect to 100 mass parts of base resins.

  Furthermore, in this invention, various additives, such as inorganic fillers, such as a ultraviolet absorber, anti-aging agent, a coloring agent, an antistatic agent, a fungicide, and a talc, can be added suitably as needed.

The flame retardant resin composition of the present invention having such a composition is extrusion-coated by a known extrusion coating method as the resin coating layers 2 and 12 on the metal tubes 1 and 11 of FIGS. .
Thereby, the metal tube of the present invention is obtained. The resin coating layers 2 and 12 may be coated with a tape made of a flame retardant resin composition and wound around the metal tubes 1 and 11. Or the tube which consists of a flame-retardant resin composition is created, this may be covered with the metal pipes 1 and 11, and it may coat | cover by heating. The surface hardness of the resin coating layer thus obtained is adjusted to be 50 or less, more preferably 30 to 50 in Shore D hardness (JIS-6760). By setting it within this range, it is possible to take a balance of characteristics that contradict each other between trauma resistance and flexibility. However, the metal pipe includes a bent pipe and a connecting joint. Furthermore, the shape is not limited to the case of FIGS.

<Examples and comparative examples>
Under the compounding conditions shown in Tables 1 to 8, resin-coated metal tubes (Examples 1 to 18) made of a resin composition satisfying the requirements of the present invention, and resin-coated metal tubes made of a resin composition lacking the requirements of the present invention (Examples 1 to 18) Comparative Examples 1-28) were produced as samples. Specifically, as shown in FIG. 2, a stainless steel (SUS304) flexible tube having a diameter of 20 mm was prototyped, and the resin coating layer of the resin composition having the above requirements was used as a protective layer (sheath) to obtain a thickness. Covered with 0.7 mm ± 0.1 mm. This coating was performed by pelletizing the resin composition and feeding it to an extruder.

  The EEA used here has an ethyl acrylate content of 15% by mass and a melt flow rate (MFR) of 0.5. EVA has a vinyl acetate content of 20% by mass and an MFR of 2.5. The thermoplastic cross-linked resin is RC resin (Cress Pearl RC801, manufactured by Nippon Polyethylene Co., Ltd.). Magnesium hydroxide is X-22-1894 (manufactured by Shin-Etsu Silicone). Calcium carbonate is NS1000 (manufactured by Nitto Flour Chemical Co., Ltd.). The lubricant is stearic acid. The ultraviolet absorber is Tinuvin 111FDL (manufactured by Ciba Specialty Chemicals). The anti-aging agent is Irganox 1010 (manufactured by Ciba Specialty Chemicals).

  Then, for each of these metal tubes, high temperature oil resistance, sheath cut property, sheath pullability (20 ° C. and −5 ° C.), flame retardancy, and trauma resistance were examined by the following methods. These are also shown in Tables 1 to 8. In addition, the numerical value of the compounding material in each table | surface shows a mass part number.

<High temperature oil resistance>
Each metal tube was bent 180 ° along a cylinder having a diameter of 40 mm, and immersed in soybean oil at 155 ° C. for 10 seconds in this state. This was tried 10 times, and the resin coating layer (sheath) with no tearing or cracking was accepted over the entire length, and a part with tearing or cracking was rejected.

<Sheath cut>
Using a commercially available sheet cutter, when the sheath is cut in the circumferential direction by rotating 10 cm from the end of the tube in a circumferential direction, the sheath is divided into two beautifully without being kinked (passed). Those in which the notch of the sheath was insufficiently connected or the cut surface of the sheath was kinked were regarded as defective (failed).

<Sheath pullability>
As described above, the case where the sheath cut by the sheet cutter was pulled out by hand at an ambient temperature of 20 ° C. and −5 ° C. and easily pulled out was regarded as acceptable, and the case where it was not easily pulled out was regarded as unacceptable.

<Flame retardance>
Stand each metal tube vertically, tilt the burner at an angle of 45 °, indirect flame for 5 seconds, then release it if it does not continue to burn for more than 15 seconds, pass, and continue to burn for more than 15 seconds The case was rejected.

<Trauma resistance>
With respect to each metal tube, drawing was performed using an apparatus as shown in FIG. In this apparatus, three control panels each having a thickness of 12 mm and a hole with an inner diameter of 36 mm were installed at an interval of 450 mm, and the sample was pulled through a metal tube. At this time, the height of the hole of the second panel is set 150 mm higher in the vertical direction than the holes of the left and right panel (the amount of eccentricity is 150 mm). The length of the metal tube was 3 m, the drawing speed was 1 m / sec, and three tests were performed per sample. And by this drawing, it was set as the pass if there was no damage, a crack, and a tear in a sheath, and it was set as the failure if there was a damage, a crack, and a tear.

  From the above Tables 1 to 3, in the metal pipes (Examples 1 to 18) provided with the sheath made of the resin composition that satisfies the conditions of the present invention, high-temperature oil resistance, sheath cut property, sheath pull-out property, flame resistance, It turns out that it is favorable (pass) in all the traumatic properties.

On the other hand, it can be seen from Tables 4 to 7 that the metal pipe (Comparative Examples 1 to 28) provided with the sheath made of the resin composition lacking the requirements of the present invention has a problem in any respect.
That is, in Comparative Examples 1 to 12, when the addition amounts of EEA and EVE of the base resin are large (70 parts by mass) and the addition amount of the thermoplastic crosslinked resin is small (30 parts by mass), Comparative Examples 13 to 24 are When the addition amount of EEA and EVE is small (30 parts by mass) and the addition amount of the thermoplastic crosslinked resin is large (70 parts by mass), Comparative Example 25 is a case where the flame retardant magnesium hydroxide is low (10 parts by mass). Example 26 has a high flame retardant magnesium hydroxide (60 parts by mass), Comparative Example 27 has a low flame retardant calcium carbonate (10 parts by mass), and Comparative Example 28 has a high flame retardant calcium carbonate (60 parts by mass). Part by mass).

It is the longitudinal cross-sectional view which showed an example of the resin-coated metal tube which concerns on this invention. It is the vertical side view which showed the other example of the resin-coated metal pipe which concerns on this invention. It is the II sectional view taken on the line longitudinal axis of FIG. It is a schematic explanatory drawing of the apparatus (narrow place through-pipe test apparatus) for determining damage resistance.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Metal pipe, 2 ... Resin coating layer, 11 ... Metal pipe, 12 ... Resin coating layer

Claims (5)

For 100 parts by mass of a base resin consisting of 40 to 60 parts by mass of a thermoplastic crosslinked resin and 60 to 40 parts by mass of at least one resin selected from ethylene-ethyl acrylate copolymer or ethylene-vinyl acetate copolymer, A flame retardant resin composition comprising 20 to 50 parts by mass of a flame retardant magnesium hydroxide. For 100 parts by mass of a base resin consisting of 40 to 60 parts by mass of a thermoplastic crosslinked resin and 60 to 40 parts by mass of at least one resin selected from ethylene-ethyl acrylate copolymer or ethylene-vinyl acetate copolymer, A flame retardant resin composition comprising 16 to 48 parts by mass of a flame retardant calcium carbonate. A flame retardant resin composition, wherein 0.5 to 3 parts by mass of a lubricant having a surface lubricity action is added to the flame retardant resin composition according to claim 1 or 2. A resin-coated metal tube, wherein the flame retardant resin composition according to claim 1, 2 or 3 is coated on the outer periphery of a metal tube such as a gas tube. The resin-coated metal tube according to claim 4, wherein the metal tube is a flexible metal tube.

Images