JPS6239189B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel flame-retardant sealing material using a specific liquid chloroprene polymer having a carboxyl group, especially for metals, glass, plastics, etc.
The present invention relates to a high-performance flame-retardant shaped sealing material that has excellent adhesion to rubber, concrete, etc., is easily foamable at fire temperatures, and is curable and has improved field workability. Flame-retardant sealants and fire-resistant paints that use liquid chloroprene-based polymers have been known for some time, and these are extremely effective in preventing the spread of fire from around electric wires and cables to structures in the event of a fire. . However, these sealants and paints that use existing liquid chloroprene polymers all contain compounding agents such as flame retardant liquid chloroprene polymers, nonflammable inorganic fillers, inorganic fibers, blowing agents, and flame retardants. It is a blend containing either alone or in combination,
No reaction between the liquid chloroprene polymer and these ingredients was essentially required. Therefore, the liquid chloroprene polymer only plays the role of a binder for the inorganic compound, and these sealants are either hard or relatively soft sticky putty-like materials depending on the amount of the inorganic compound. hand,
The reality is that the method used in the field is to create small blocks of this material and coat them around the cable.
In order to improve workability in on-site construction, a method has been proposed in which a putty-like sealing material is shaped into a tape or sheet and wrapped on-site. The material is too weak to be molded into tape or sheet form and easily breaks during molding.To improve this, there is a method of blending solid chloroprene rubber, but in this case, the viscosity during kneading becomes high and processing is difficult. There were disadvantages in that not only the properties were significantly reduced, but also the storage stability of the resulting molded product was poor. In view of these problems, the inventors of the present invention have conducted intensive studies and found that a composition in which a carboxylated liquid chloroprene polymer and zinc hydroxide or a blend of zinc hydroxide and magnesium hydroxide is blended can be used in combination with conventional liquid polymers. Not only does it provide a molded product that exhibits excellent workability equivalent to that of the conventional product, but also has good on-site workability, the performance of the molded product is also generally superior to that of conventional products. Heading This is what led to the completion of the present invention. An object of the present invention is to provide a flame-retardant shaped sealing material which is significantly superior in on-site workability compared to putty-like flame-retardant sealing materials using conventional liquid chloroprene-based polymers. Metal, glass,
To provide a high-performance flame-retardant sealing material that is a fire spread prevention material with excellent adhesion to plastics, rubber, etc., and can be easily foamed and hardened at fire temperatures. This purpose is made by blending a specific liquid chloroprene polymer having a carboxyl group with zinc hydroxide or zinc hydroxide and magnesium hydroxide, which act as chelating agents and curing accelerators for the polymer, as essential components. This is achieved by the composition.
That is, the metal hydroxide mentioned above can react with the carboxyl group of the liquid polymer even at room temperature to form a chelate and give an elastic cured product, so the resulting composition is different from a simple blend. Since it has properties similar to those of a crosslinked product, it has the advantage of being strong and easy to mold into a tape or sheet-like product. In addition, the metal hydroxide easily decomposes into metal oxides and generates water vapor at high temperatures such as fire temperatures, so the former is useful as a high-temperature curing agent for the polymer, and the latter as a nonflammable gas blowing agent. It also has an effect. Therefore, the flame-retardant sealing material according to the present invention prevents the spread of fire of combustible materials by forming a heat insulating layer through foaming, prevents the temperature rise of the coating film due to the heat of dissociation and vaporization caused by the generation of water vapor, and prevents cracks by strengthening the mechanical performance of the coating film by curing. It is not only an extremely high-performance flame-retardant sealing material that can simultaneously achieve the effects of preventing cracking and fire spread, but also has superior adhesion to metals, glass, etc. due to the action of the carboxyl group of the polymer, compared to ordinary liquid chloroprene-based polymers. It is a sealing material that is even better than conventional sealants, and because it comes in a fixed shape such as a string, tape, or sheet, it is extremely easy to construct on-site, and can satisfy almost all of the performance requirements for practical use. It is no exaggeration to say that it is a revolutionary flame-retardant sealing material. The liquid chloroprene polymer used in the present invention has a number average molecular weight in the range of 1000 to 10000,
It is a low molecular weight chloroprene homopolymer or chloroprene copolymer having substantially one or more carboxyl groups in its molecule. The chloroprene copolymer includes chloroprene and copolymerizable monomers such as vinyl compounds such as styrene, methyl methacrylate, and acrylonitrile, 1,3-butadiene, isoprene, and 2,3-butadiene.
Examples include copolymers with conjugated dienes such as dichloro-1,3-butadiene, and chloroprene-sulfur copolymers. Methods for introducing carboxyl groups into these polymers include known methods such as chloroprene monomers. Acrylic acid is one of the copolymerization components of
Any method can be used, such as a method of obtaining a copolymer using an unsaturated carboxylic acid such as methacrylic acid, or a method of polymerizing or copolymerizing a monomer containing chloroprene in the presence of a mercaptocarboxylic acid such as thioglycolic acid. In particular, the latter method allows carboxyl groups to be introduced at the ends of the resulting polymer, which can be effectively used to form chelates with metal hydroxides. The number average molecular weight of the liquid polymer used in the present invention is limited to a range of 1,000 to 10,000, but if it deviates from this range, the caking force may decrease when highly filled with inorganic fillers, inorganic fibers, etc. These tend to have problems such as high viscosity during blending and poor processing methods. In addition, if the number of carboxyl groups in the polymer is substantially less than one, the formation of a chelate between the polymer and the metal hydroxide will be incomplete, so that the number of carboxyl groups in the polymer will be insufficient to obtain a shaped sealing material. A firm composition cannot be obtained. Generally, the number of carboxyl groups in the polymer used in the present invention ranges from 1 to 2.5 on average, preferably about 1 to 1.5. The sealing material of the present invention contains 100 parts by weight of the above liquid polymer and at least 5 parts by weight of zinc hydroxide or zinc hydroxide and magnesium hydroxide as essential components. These metal hydroxides are liquid polymers.
If the content is less than 5 parts by weight per 100 parts by weight, chelation with the polymer will be slow and it will be difficult to obtain a strong molded product, and chlorination will occur due to decomposition of the polymer during heating. The hydrogen trapping effect also tends to be incomplete. The amount of the metal hydroxide used is usually 5 to 30 parts by weight per 100 parts by weight of the polymer. The sealing material of the present invention contains an inorganic filler to impart practical flame retardancy. Inorganic fillers include silica, clay, alumina hydrate, etc. In particular, those containing 100 to 300 parts by weight of alumina hydrate per 100 parts by weight of the polymer have an extremely high oxygen index of 60 to 100. Since it provides a non-combustible sealing material that has the following characteristics, it is advantageously used in practice. Furthermore, if necessary, a vulcanization accelerator or inorganic fibers for the polymer can be added to improve the mechanical strength and flame retardance of the sealing material. As the vulcanization accelerator, there can be used an accelerator for high-temperature vulcanization of solid chloroprene rubber, such as ethylenethiourea, diethylthiourea, diphenylthiourea, and di-0-tolylguanidine. In an embodiment of the flame-retardant sealing material according to the present invention, the raw materials containing the essential components are thoroughly kneaded using a conventional mixer, kneader, paint roll, etc. for mixing high viscosity materials, and the resulting compound is passed through an extruder. Generally, it is used to form a string or sheet, wrap it in release paper, and roll it up for on-site construction. The resulting molded product not only has extremely good adhesion to metals, glass, plastics, rubber, or concrete, but also has high self-bonding properties, so it can be used to wrap strings in areas that require sealing. Simply gluing the sheet-like materials together is enough to accomplish the purpose. Further, in the present invention, if necessary, it is also possible to adjust the hardness of the sealing material obtained by adding a flame-retardant softener such as trinonyl phosphate, tricresyl phosphate, or chlorinated paraffin. In some cases, it is also possible to mold the mixture by heating it to a medium temperature of about 50 to 100 DEG C. to promote partial crosslinking of the polymer at the same time as chelate formation. Examples and comparative examples are shown below to further specifically explain the present invention. All amounts used herein are expressed by weight. In these Examples and Comparative Examples, the oxygen index was measured in accordance with ASTMD-2863, and the vertical combustion test was conducted in accordance with U.S. UL-94.
Measured according to standards. The liquid chloroprene polymers used here are summarized below. Polymers C and D are control samples containing no carboxyl groups or a small amount of carboxyl groups. Further, the carboxyl group of the polymer was measured by neutralization titration of a benzene solution of the polymer with a caustic acid-methanol solution, and the number average molecular weight was measured by an everiometer. Polymer A: Polymerization of chloroprene in toluene solvent in the presence of thioglycolic acid.The average number of carboxyl end groups in the molecule is 1.1.
Chloroprene liquid polymer polymer B having a number average molecular weight of 4300: 92 parts of chloroprene, 3 parts of methacrylic acid, and 2.3 parts of methacrylic acid in the presence of thioglycolic acid.
Copolymerized with 5 parts of -dichlorobutadiene-1.3 The average number of carboxyl groups in the molecule is 2.0, and the number average molecular weight is 2850.
Polymer C: A liquid polymer of chloroprene having a number average molecular weight of 2500, which does not contain carboxyl groups, obtained by polymerizing chloroprene in a toluene solvent in the presence of η-dodecylmercaptan Polymer D: A liquid polymer of chloroprene in the presence of n-dodecylmercaptan 92 parts, 3 parts of methacrylic acid, and 2,3-dichlorobutadiene-1,3
Example 1, Comparative Examples 1 and 2 A liquid polymer having an average number of 0.36 carboxyl groups and a number average molecular weight of 2440 obtained by copolymerizing with 5 parts The compound obtained was extruded into a sheet through a die of 3 mm thick x 25 mm wide using a screw extruder at an extrusion temperature of 80 to 90°C, and immediately rolled up into a sandwich shape using release paper while cooling with water. I tried to obtain an obi-shaped sealant. When Polymer A according to the present invention was used, the extruded sheet was strong and could be continuously rolled up, but when Polymers C and D of Comparative Examples were used, the extruded sheet Since it is weak and easily breaks, it has been impossible to continuously wind it up as a shaped sealing material.

[Table] The obi-shaped sealing material obtained in Example 1 has excellent self-bonding properties and pressure-sensitive adhesive properties, and can be applied to metals, glass, porcelain, etc., as well as plastics, rubber, etc. by simply pressing it. It adhered well and had excellent workability. On the other hand, the compounds obtained from Comparative Examples 1 and 2 had higher surface adhesion, but
Adhesion to glass and porcelain was inferior to that of Example 1. Next, a flame retardancy test was conducted using a 2 mm thick sheet obtained by cold pressing the above three types of compounds in a mold, and the results are summarized in Table 1. These results show that in the comparative example using a liquid chloroprene polymer that does not contain carboxyl groups, there is no chelate formation with zinc hydroxide, or there is virtually no contribution to it, so the hardness of the sheet is low, which is the same as in Example 1. There was no significant improvement in flame retardancy.

[Table] Example 2, which means no ignition, Comparative Example 3 A compound obtained by kneading with a paint roll according to the following formulation was heated in a mold at 100°C for 1 hour to form a 2 mm thick sheet. However, in the case of Comparative Example 2, which did not contain zinc hydroxide, curing due to the formation of a polymer chelate was not observed, resulting in a highly adhesive paste-like form, and no shaped sheet could be obtained. on the other hand,
The cured sheet obtained in Example 2 had weak elasticity and excellent self-fusion and pressure-sensitive adhesive properties.
As a result of a vertical combustion test similar to the above, a heat insulating layer hardened in a foamed state was formed on the surface of the sample, indicating excellent flame retardancy. Mixing recipe Example 2 Comparative example 3 Polymer B 100 parts 100 parts Zinc hydroxide 30 - Soft clay 120 150 Example 3 A compound obtained by kneading with a paint roll was mixed in a mold according to the following recipe. A semi-vulcanized sheet with a thickness of 2 mm was obtained by heat treatment at 100°C for 2 hours. The tensile strength and elongation at break of this sheet are each 12
Kg/cm ² , 330%. This sheet was formed into a strip with a width of 25 mm, and was wrapped twice around the center of a 10 cm long polyvinyl chloride sheathed cable and crimped. Next, this cable was stood vertically and the lower end was exposed to the flame of a burner for several seconds, and when it was exposed to direct fire, it burned violently and the upper part of the cable was also thermally deformed due to the fire, but the surface of the part wrapped with the semi-vulcanized sheet was foamed and solidified. The cables inside were completely protected, with no cracks and non-combustibility. Mixing recipe Polymer A 100 parts Zinc hydroxide 10 Magnesium hydroxide 5 Hard clay 20 AI(OH) ₃・6H ₂ O 100 Ethylenethiourea 0.5

Claims (1)

[Scope of Claims] 1. 100 parts by weight of a liquid chloroprene polymer having substantially one or more carboxyl groups in the molecule and having a number average molecular weight of 1,000 to 10,000, and zinc hydroxide or zinc hydroxide. A flame-retardant shaped sealing material containing at least 5 parts by weight of magnesium hydroxide and an inorganic filler. 2. The liquid chloroprene-based polymer is a liquid polymer obtained by polymerizing a chloroprene monomer alone or together with a monomer that can be copolymerized therewith in the presence of mercaptocarboxylic acid. Flame retardant shaped sealing material.