JP3548977B2 - Method of manufacturing lead sheet mat for shielding - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is intended to reduce radiation exposure by shielding facilities, equipment, pipes, and the like that serve as radiation sources in nuclear facilities and nuclear-related operations, etc., for shielding used to ensure the safety of workers in the vicinity. The present invention relates to a lead sheet mat and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, as this type of shielding lead sheet mat, a pipe shielding lead mat described in Japanese Utility Model Laid-Open No. 6-56797 and a shielding lead sheet laminated mat described in JP-A-7-229999 have been proposed. I have.
[0003]
The former mat is made by stacking multiple lead thin plates and storing them in a bag, and the latter mat is made by stacking a spring plate on the lead thin plate in addition to this stacked lead thin plate to restore the lead thin plate. It is.
[0004]
These mats can be wrapped around piping using belts or fasteners, or can be locked to any support member using eyelets provided on the bag that stores the lead thin plate to provide facilities and equipment. It is arranged on a predetermined surface.
[0005]
[Problems to be solved by the invention]
However, since the former mat is formed by laminating a plurality of lead thin plates as they are, when this mat is bent, the bent state remains on the lead thin plate due to its properties (work hardening characteristics). It was extremely difficult to return to the state.
[0006]
Further, in the latter mat, a spring plate is laminated on this lead thin plate in order to restore the bent lead thin plate, but it is difficult to restore the lead thin plate even if the spring plate is restored from the bent state. Met. In particular, in a portion where the lead thin plates are laminated, the frictional resistance of the lead plate is high. Therefore, when the mat is bent, the entire laminated lead thin plate is bent in an integrated state. Therefore, the force for restoring the bent state becomes large, and only the spring plate may be separated from the lead sheet and restored while the lead sheet remains bent. Also, since the lead thin plate is restored by using the elastic force of the spring plate, when the mat is bent, the elastic force of the spring plate itself becomes a resistance, and the work of bending the mat or bending the mat is performed. Is difficult to maintain for a long time.
[0007]
In addition, it is known that the lead thin plate is liable to accumulate metal fatigue. Therefore, it is known that when the bending operation is repeated, the strength of the bent portion is deteriorated and the lead thin plate is easily broken. As described above, the conventional lead sheet mat for shielding has left a great problem in durability performance.
[0008]
Therefore, the present invention has been created to solve the above-described problems, and the bending and restoring work of the laminated lead thin plate is extremely easy, and furthermore, the durability capable of repeating the bending and restoring work many times is provided. It is an object of the present invention to provide an excellent shielding lead sheet mat and a method for manufacturing the same.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention relates to a method for manufacturing a shielding lead sheet mat in which a plurality of lead sheets 1 are stacked and stored in a bag body 2, wherein each lead sheet 1 is heated at an appropriate temperature. A synthetic resin film 1A composed mainly of polyethylene partially or entirely graft-modified with an unsaturated carboxylic acid or a derivative thereof is provided with a synthetic resin film 1A having a thickness of 75 to 100 μm on both sides of the heated lead thin plate 1. Then, the lead thin plate 1 to which the synthetic resin film 1A is temporarily bonded is heated at an appropriate temperature by a heating device, and the synthetic resin film is melted and bonded to the surface of the lead thin plate 1. Is laminated with a synthetic resin film 1A , one longitudinal end of the laminated lead thin plate 1 is connected with a fastener 3, and a plurality of lead thin plates 1 laminated with the synthetic resin film 1A are coated glass. cross Storing in a bag 2 made of steel is a means for solving the problem.
[0010]
According to the present invention, the synthetic resin film 1A firmly adhered to each lead thin plate 1 by laminating processing increases the bending strength of each lead thin plate 1 while acting as a lubricating material, and is laminated at the time of bending and restoring. It has the effect of promoting sliding between the lead thin plates. Further, the bag body 2 provided with a coated glass cloth has heat resistance and flame retardant properties, and is suitable for storing the lead thin plate 1 obtained by laminating the synthetic resin film 1A. Further, since the synthetic resin film 1A is strongly bonded, the work hardening characteristics of the lead thin plate 1 are changed, and the bending performance and the durability are enhanced.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
Reference numeral 1 shown in the figure is a lead thin plate 1 for shielding radiation, which is used by laminating a plurality of sheets (see FIG. 2). These lead thin plates 1 are laminated so as to be bent by their own weight. Then, a lubricating material for reducing the frictional resistance between the lead thin plates is interposed on the laminated surface of the lead thin plates 1. The lead thin plate 1 of the illustrated example has a synthetic resin film 1A adhered to the surface thereof as a lubricant. In the embodiment, five to six lead thin plates 1 having a thickness of 0.8 mm are used, and a synthetic resin film 1A having a thickness of 75 to 100 μm is adhered to both sides of each lead thin plate 1 so that sufficient radiation of the mat of the present invention can be obtained. A shielding effect and an extremely free bending / restoring effect have been confirmed (see FIG. 4). One of the longitudinal ends of the stacked lead thin plates 1 is connected by a fastener 3. By this connection, in the bending / restoring operation, the displacement of each lead thin plate 1 can be prevented, and the stacked lead thin plates 1 can always be kept in the same position (see FIG. 2). In addition, the thickness of the lead thin plate 1, the number of laminations, the thickness of the synthetic resin film 1A, and the like are appropriately changed according to the size of the mat of the present invention, the place of use, and the like.
[0013]
The lead thin plate 1 laminated in this way via the lubricating material is stored in the bag body 2. The bag 2 is preferably made of a material having heat resistance and flame retardancy. By using a coated glass cloth, the strength of the bag 2 is increased, and dust and radioactivity attached to the bag 2 are easily removed. can do. In addition, in order to facilitate carrying and handling of the mat of the present invention, in the embodiment, the length of the bag 2 is set to 860 mm and 270 mm in width, and the laminated lead thin plate 1 having a length of 760 mm and a width of 230 mm and a weight of 10 kg is used. It is housed and the periphery of the lead thin plate 1 is sewn (see FIG. 1). Further, the sewing means of the bag 2 may be changed together with the change of the material of the bag 2. Furthermore, the sizes of the lead thin plate 1 and the bag 2 can be arbitrarily set according to the place of use or the like.
[0014]
An eyelet 2A for facilitating the mounting of the mat of the present invention is provided at the end of the bag 2 (see FIG. 3). The eyelet hole 2A is to be engaged with a support member (not shown) installed near a facility or equipment to be shielded. In the illustrated example, a plurality of eyelets 2 </ b> A are provided at both longitudinal ends of the bag 2. Further, instead of the eyelet hole 2A, or together with the eyelet hole 2A, a belt or a fastener may be attached.
[0015]
In order to firmly adhere the synthetic resin film 1A to the surface of the lead thin plate 1, a special laminating method is required. Then, this laminate manufacturing method will be described in detail below.
[0016]
First, each lead thin plate 1 is heated at an appropriate temperature, and one or both surfaces of the heated lead thin plate 1 are synthesized mainly with polyethylene partially or entirely graft-modified with an unsaturated carboxylic acid or a derivative thereof. The resin film 1A is arranged and pressure-bonded by a pressure-bonding device to temporarily adhere. Next, the lead thin plate 1 to which the synthetic resin film 1A has been temporarily bonded is heated and fused at an appropriate temperature by a heating device to bond the synthetic resin film 1A to the surface of the lead thin plate 1.
[0017]
The synthetic resin film 1A mainly composed of polyethylene partially or wholly graft-modified with an unsaturated carboxylic acid or a derivative thereof used in the laminating method generally has a density of 0.900 to 0.975 g / cm3, preferably 0.910 to 0.960. g / cm @ 3 and an ethylene homopolymer having a melt flow index (ASTM D1238 190 DEG C.) of 0.01 to 30, preferably 0.1 to 10, or ethylene and other .alpha.-olefins such as propylene, 1-butene and 4-methylpentene. Part or all of the copolymer such as 1 is made of polyethylene which is graft-modified with an unsaturated carboxylic acid or a derivative thereof.
[0018]
In addition, known elastomer components such as natural rubber, ethylene-propylene random copolymer (EPR), EPDM, polyisobutylene, butyl rubber, isoprene rubber, and styrene-based thermoplastic elastomer may be added to the polyethylene.
[0019]
Examples of the unsaturated carboxylic acid or a derivative thereof include methacrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, and endocis-bicyclo [2. 2.1] Hept-5-ene-2,3-dicarboxylic acid (nadic acid) and the like, and derivatives thereof such as acid halide, amide, imide, acid anhydride and ester. Of these, unsaturated dicarboxylic acids or acid anhydrides thereof are preferred, and maleic acid, nadic acid or acid anhydrides thereof are particularly preferred.
[0020]
As a method for grafting an unsaturated carboxylic acid or a derivative thereof to polyethylene having a density of 0.900 to 0.975 g / cm @ 3, various known methods can be adopted. For example, it is carried out by heating the ethylene-based polymer and the graft monomer to a high temperature in the presence or absence of a solvent, with or without the addition of a radical initiator. In the reaction, another vinyl monomer such as styrene may coexist.
[0021]
The amount (graft ratio) of the graft monomer to be grafted onto polyethylene is preferably adjusted so as to be in the range of 0.001 to 10% by weight, particularly 0.01 to 1% by weight. The polyethylene of this laminate production method may be partially grafted or the whole may be grafted, but from an industrial point of view, a modified polyethylene having a graft ratio of about 0.1 to 10% by weight is produced in advance. Beforehand, it is preferable to mix the modified polyethylene with the unmodified polyethylene in order to adjust the concentration of the graft monomer in the polyethylene.
[0022]
The mat of the present invention is manufactured by accommodating a plurality of lead thin plates 1 laminated with the synthetic resin film 1A in such a manufacturing method in the bag body 2.
[0023]
【The invention's effect】
The original object has been achieved by the present invention.
[0024]
According to the production method of the present invention, each lead thin plate 1 is heated at an appropriate temperature, and a synthetic resin film 1A mainly containing polyethylene partially or entirely graft-modified with an unsaturated carboxylic acid or a derivative thereof is heated by this heating. The synthetic resin film 1A having a thickness of 75 to 100 μm is disposed on both sides of the lead thin plate 1 thus formed, and is crimped by a crimping device and temporarily bonded. By heating at an appropriate temperature with an apparatus and fusing the synthetic resin film to laminate the synthetic resin film 1A on the surface of the lead thin plate 1, the lead thin plate 1 in which the synthetic resin film 1A is firmly bonded can be manufactured. As a result, a sufficient radiation shielding effect of the mat of the present invention and an extremely free bending / restoring effect can be obtained. Further, even when the laminated lead thin plate 1 is repeatedly bent and restored, the synthetic resin film 1A bonded to the surface of the lead thin plate 1 is securely bonded without peeling. In addition, since the adhesive force of the synthetic resin film 1A is strong, it is possible to provide a shielding lead plate mat having excellent durability by changing the work hardening characteristics of the lead thin plate 1 and improving the bending performance.
[0025]
Further, the synthetic resin film 1A used as the lubricating material was firmly adhered to the surface of each lead thin plate 1 by laminating, so that the frictional resistance between the lead thin plates 1 was significantly reduced. Therefore, the mat of the present invention can be bent into a free shape, and can be easily arranged in a narrow place or along a position with a high radiation level. As a result, in a nuclear facility and a nuclear-related business, the shielding range of facilities, equipment, piping, and the like serving as a radiation source can be further expanded.
[0026]
In addition, since one longitudinal end of the laminated lead thin plates 1 is connected by the fastener 3, displacement of each lead thin plate 1 is prevented in bending / restoring work, and each laminated lead thin plate 1 is removed. You can always keep the same position.
[0027]
By storing a plurality of lead thin plates 1 laminated with the synthetic resin film 1A in a bag 2 made of coated glass cloth, heat resistance and flame retardancy are obtained, which is preferable. Further, the strength of the bag 2 can be increased, and dust, radioactivity, and the like attached to the bag 2 can be easily removed.
[0028]
Moreover, since the synthetic resin film 1A is firmly bonded to the surface of each lead thin plate 1 by laminating, the bending durability of each lead thin plate 1 is improved, and even if the bag body 2 is damaged, It became possible to use 1 continuously. As a result, the lead sheet 1 can be reused by replacing only the bag body 2, and the waste can be reduced as much as possible and the laminated lead sheet 1 can be effectively used.
[0029]
As described above, according to the present invention, the bending and restoring operation of the laminated lead thin plate is extremely easy, and the bending and restoring operation can be repeated many times. It has a flammable property and can also shield neutrons, which can be useful in nuclear facilities and nuclear-related operations, such as further expanding the shielding range of facilities, equipment, piping, etc. that become radiation sources. It produces various effects.
[Brief description of the drawings]
FIG. 1 is a front view showing one embodiment of the present invention.
FIG. 2 is an enlarged sectional view of a main part showing one embodiment of the present invention.
FIG. 3 is an enlarged front view of a main part showing one embodiment of the present invention.
FIG. 4 is a perspective view showing a bending example of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lead thin plate 1A Film made of synthetic resin 2 Bag 2A Eyelet hole 3 Fastener

Claims (1)

In a method of manufacturing a lead sheet mat for shielding in which a plurality of lead sheets are stacked and stored in a bag body, each lead sheet is heated at an appropriate temperature, and a part or the whole is graft-modified with an unsaturated carboxylic acid or a derivative thereof. The synthetic resin film containing polyethylene as the main component is bonded to both sides of a heated lead thin plate with a synthetic resin film with a thickness of 75 to 100 μm. The lead thin plate to which the resin film is temporarily adhered is heated at an appropriate temperature by a heating device, the synthetic resin film is fused, the synthetic resin film is laminated on the surface of the lead thin plate, and one longitudinal end of the laminated lead thin plate is formed. A method for manufacturing a lead mat for shielding, characterized in that the parts are connected with a fastener, and a plurality of thin lead sheets laminated with the synthetic resin film are accommodated in a bag made of coated glass cloth.

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