CN1322047C - Rare earth modified leadless X-ray shielding plastic - Google Patents

Abstract

The invention relates to a rare earth modified all-lead-free X-ray shielding plastic. Part of the inorganic rare earth is subjected to surface modification treatment, and the other part is subjected to organic reaction treatment to prepare organic rare earth salt, and the two are added to the plastic in a certain proportion to obtain a modified lead-free X-ray shielding plastic. The shielding performance and mechanical properties all achieve ideal results. It can be widely used in medical diagnostic X-ray machines, X-ray diffractometers, emitters of electron microscopes and the protection of workers in other occasions accompanied by X-ray generation.

Description

A kind of rare earth modified lead-free X-ray shielding plastic

Technical field:

The invention relates to a rare earth modified all-lead-free X-ray shielding plastic.

Background technique:

The present invention is to prepare high-shielding performance, lead-free, light and soft thin-layer X-ray shielding polymer composite materials, which are used for medical diagnostic X-ray light machines, X-ray diffractometers, electron microscope emitters and other transmitters with X-ray Protection of workers in places where radiation is generated.

The development, production and popularization of radiation protection materials is one of the key points of civil health protection work, and it is also an important part of radiation protection in the field of nuclear energy development and military use. Domestic polymer radiation protection materials are mainly lead rubber products. Europe, America, Japan and other countries have successfully developed new thermoplastic elastomer composite materials. Under the same specific lead equivalent conditions, this composite material has high physical and mechanical properties, good surface properties, aging resistance, and stable dimensions. Clothes can also be thermally synthesized. Under the condition of the same weight, if polyurethane is used as the base material, the service life and radiation protection performance of the material can be improved to a certain extent. Relevant production technologies have been developed abroad, and very thin sheets (minimum thickness up to 0.3mm) have been prepared. Personal protective clothing made of single-layer or multi-layer composites is quite flexible. This type of sheet is mainly used to make radiation-proof clothing such as protective jackets, vests, and overall protective clothing. The disadvantage is that the dispersed phase material is still mainly lead, and the price is expensive.

Usually, most of the photons of medical diagnostic X-rays produced by the tube voltage below 120KVp have energy lower than 88.0KeV. At present, the dispersed phase materials of medical X-ray shielding materials at home and abroad are still mainly lead, barium and their oxides. However, because lead has weak absorption in the ray range of 40-88keV, and lead and barium materials are harmful to the human body, people try to replace lead with other elements whose K-layer absorption edge is between 40-88keV to make composite materials.

Foreign researchers have tried to use Cu, Sn, Sb, I, Ba and other elements. The K-layer absorption energies of elements Cu, Sn, Sb and I are 9.0, 29.2, 30.5 and 33.1keV, respectively, which are far from the lower limit of the weak absorption region, and none of them can well compensate for the weak absorption region of Pb. The element Ba is chemically active and cannot be used in the form of a single substance, but can only be used in the form of a compound. Among the Ba compounds, BaO has the highest percentage by weight of Ba element, but BaO is very alkaline, chemically toxic, and expensive, which reduces its use value. If BaSO ₄ is selected, although the chemical toxicity of Ba can be overcome and its chemical stability can be enhanced, the shielding effect is deteriorated because the weight percentage of Ba in the compound is too low (59%). Therefore, until now, lead is generally the main material.

Russian patents RU2054439 and RU2028331 all disclose rubber X-ray-resistant composite materials modified with inorganic rare earth oxide fillers, but due to the poor compatibility of inorganic rare earth (rare earth oxides) with the rubber matrix, the polymer matrix Voids are easy to appear at the interface, and these gaps will be easily penetrated when irradiated by high-energy rays, and even the leakage of rays will occur. It is difficult to guarantee the uniformity of shielding performance of the material, so the performance stability of the material is also difficult to control.

In terms of matrix polymers, developed countries such as the United States and Japan have begun to use plastic (including thermoplastic elastomer) materials for ray shielding of X-ray machines, mainly for the production of protective jackets, vests, overall protective clothing and other clothing. Compared with traditional rubber materials, this material has very prominent features, the most important being light weight, good protection performance, long service life, soft and comfortable, and can be processed in the same way as plastic, so it can be recycled, thus effectively It greatly improves the repeated use efficiency of rare earth/plastic materials, and fully saves the rare earth resources in our country.

Invention content:

The purpose of the present invention is to provide a kind of rare earth modified lead-free X-ray shielding plastics. Part of the inorganic rare earth is subjected to surface modification treatment, and the other part is subjected to organic reaction treatment to prepare organic rare earth salt, and the two are combined in a certain proportion. Adding it to the plastic, so as to obtain a modified all-lead-free X-ray shielding plastic, so that the shielding performance and mechanical properties of the material can achieve ideal effects.

A rare earth modified all-lead-free X-ray shielding plastic, the composition and parts by weight are:

Plastic 50-100

Organic rare earth complex 20-200

Inorganic rare earth compound 20-500

Softener 2-30

Antioxidant 1-3

Silane coupling agent 0.5-3

The plastics used are polyolefins (polyethylene, ethylene-alpha olefin copolymers), thermoplastic elastomers, especially styrenic thermoplastic elastomers, such as: styrene-butadiene-styrene copolymer (SBS), hydrogenated Styrene-butadiene-styrene copolymer (SEBS), styrene-isoprene-styrene copolymer (SIS), polyurethane thermoplastic elastomer (polyester type or polyether type).

Inorganic rare earth compounds are rare earth oxides or rare earth carbonates other than promethium.

The antioxidant was tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol (antioxidant 1010).

The silane coupling agent is vinyltriethoxysilane (A151) or γ-aminopropyltriethoxysilane (KH550).

The softener is low molecular weight polyethylene wax, and the synthetic plasticizer is polytrimethylene adipate (PPA).

The rare earth organic complexes used are acrylate rare earth salts, methacrylic acid rare earth salts or their mixtures of 16 lanthanide elements except promethium. Its preparation method can be represented by the following reaction formula:

Re ₂ O ₃ +6HAA→2Re(AA) ₃ +3H ₂ O, wherein Re is a rare earth element, and HAA is acrylic acid or methacrylic acid.

Take a certain amount of rare earth oxide, add deionized water twice the weight of the rare earth oxide, add acrylic acid (or methacrylic acid) 1.5-2.5 times the molar amount (excess) of the rare earth oxide, heat the bath, and control the temperature at 60- Stir and react at 90°C for 1-3 hours, filter while hot, distill the filtrate under reduced pressure, remove most of the water and acrylic acid until crystals appear, add absolute ethanol to cool to obtain a precipitate, wash with absolute ethanol until neutral, Dry in an oven at about 40°C until constant weight to obtain the product.

The material of the present invention can be processed and prepared on common equipment such as hot roll mill, internal mixer, twin-screw extruder, etc., and the processing temperature is controlled within the range of 100-260°C. Melt the plastic at the processing temperature, add compounding agents such as antioxidants, softeners, silane coupling agents, and then add organic rare earth complexes and inorganic rare earth compounds. The required X-ray shielding composite material is molded by calendering, extrusion and injection.

The rare-earth modified all-lead-free X-ray shielding plastic of the present invention has a large content of mixed rare earths, and achieves high dispersion and good interface compatibility, so that the X-ray shielding performance and mechanical properties of the material can achieve ideal effects. It can be widely used in medical diagnostic X-ray machines, X-ray diffractometers, emitters of electron microscopes and the protection of workers in other occasions accompanied by X-ray generation. my country is rich in rare earth resources and has various varieties. Therefore, the rare earth modified all-lead-free X-ray shielding plastic of the present invention has a good application prospect.

The effects of the present invention will be further described below in conjunction with examples.

Detailed ways:

Example 1:

The composition and parts by weight of each component are:

Low-density polyethylene (LDPE) 100

Europium acrylate 20

Neodymium oxide 200

Gadolinium oxide 100

Europium oxide 200

KH550 3

Low molecular weight polyethylene wax 15

Antioxidant 1010 2

Preparation of shielding material: Heat the hot roll to 120°C, add 100 parts of LDPE and melt it to cover the roll, add 2 parts of antioxidant 1010, mix for 1 minute, then add 20 parts of europium acrylate, mix well and add in batches 200 parts of neodymium oxide, 100 parts of gadolinium oxide and 200 parts of europium oxide are mixed for 10-20 minutes, and then 15 parts of low-molecular wax are added and mixed for 1-2 minutes to obtain rare earth modified lead-free X-ray shielding plastics.

Example 2:

The composition and parts by weight of each component are:

LDPE 100

Europium acrylate 100

Neodymium Acrylate 50

Neodymium oxide 200

Europium oxide 200

KH550 2.5

Low molecular weight PE wax 10

Antioxidant 1010 1.5

Preparation of shielding material: Heat the hot roll to 120°C, add 100 parts of LDPE and melt it to cover the roll, add 2 parts of antioxidant 1010, mix for 1 minute, then add 100 parts of europium acrylate and 50 parts of neodymium acrylate, mix After uniformity, add 200 parts of neodymium oxide and 200 parts of europium oxide in batches, mix for 10-20 minutes, then add 10 parts of low-molecular wax, and mix for 1-2 minutes to obtain rare earth modified lead-free X-ray shielding plastics.

Example 3:

The composition and parts by weight of each component are:

Thermoplastic Polyurethane (TPU) 100

Cerium Carbonate 200

Europium acrylate 50

Europium oxide 200

Terbium oxide 200

Polyester plasticizer (PPA) 8

Antioxidant 1010 1

KH550 1

Preparation method: raise the temperature of the hot roll to 160°C, add 100 parts of TPU plasticized roll, then add 1 part of antioxidant 1010, add 100 parts of samarium acrylate in batches, mix for 5-8 minutes, add 200 parts of praseodymium carbonate, oxidize 100 parts of terbium and 50 parts of cerium oxide, 8 parts of PPA are added in batches at the same time, mixed for 10-20 minutes, and then 1 part of KH550 is added, mixed for 1-2 minutes to obtain rare earth modified lead-free X-ray shielding plastics.

Example 4:

The composition and parts by weight of each component are:

Thermoplastic Polyurethane (TPU) 50

Samarium Acrylate 50

Cerium methacrylate 50

Praseodymium methacrylate 50

Terbium acrylate 50

Samarium Oxide 20

Polyester plasticizer (PPA) 2

Antioxidant 1010 1

KH550 2

Preparation method: raise the temperature of the hot roll to 160°C, add 50 parts of TPU plasticized cover roll, then add 1 part of antioxidant 1010, add 50 parts of samarium acrylate, 50 parts of cerium methacrylate, and 50 parts of praseodymium methacrylate in batches , 50 parts of terbium acrylate, mixed for 5-8 minutes, added 20 parts of samarium oxide, and at the same time, added 2 parts of PPA in batches, mixed for 10-20 minutes, then added 2 parts of KH550, mixed for 1-2 minutes to obtain rare earth modified no Lead x-ray shielding plastic.

Example 5:

The composition and parts by weight of each component are:

SBS 100

Samarium acrylate 200

Cerium methacrylate 100

Samarium methacrylate 100

Terbium acrylate 200

Samarium Oxide 200

Cerium oxide 200

Polyester plasticizer (PPA) 30

Antioxidant 1010 1.5

A151 2

Preparation method: raise the temperature of the hot roll to 160°C, add 100 parts of SBS to plasticize the covered roll, then add 1.5 parts of antioxidant 1010, add 200 parts of samarium acrylate, 100 parts of cerium methacrylate, and 100 parts of praseodymium methacrylate in batches , 200 parts of terbium acrylate, mixed for 5-8 minutes, added 200 parts of samarium oxide and 200 parts of cerium oxide, and simultaneously added 30 parts of PPA in batches, mixed for 10-20 minutes, then added 1 part of A151, mixed for 1-2 minutes, and obtained Rare earth modified fully lead-free X-ray shielding plastic.

Embodiment 6:

The composition and parts by weight of each component are:

SEBS 100

Terbium methacrylate 200

Samarium Acrylate 200

Gadolinium oxide 100

Europium oxide 200

Polyester plasticizer (PPA) 10

Antioxidant 1010 2

A151 1

Preparation method: raise the temperature of the hot roll to 200°C, add 100 parts of SEBS plasticized cover roll, then add 2 parts of antioxidant 1010, add 200 parts of terbium methacrylate and 200 parts of samarium acrylate in batches, mix for 5-8 minutes, Add 100 parts of gadolinium oxide and 200 parts of europium oxide, and at the same time add 10 parts of PPA in batches, mix for 10-20 minutes, and then add 1 part of A151 to obtain a rare earth modified lead-free X-ray shielding plastic.

*The specific lead equivalent value in the table represents the thickness value of the composite material per unit thickness (mm) equivalent to the pure lead plate, and the higher the value, the better the shielding performance.

The data in the table shows that compared with the lead rubber material, the shielding composite material based on plastic has excellent X-ray shielding performance, and its mechanical properties are also good. In addition, the material also has thermoplastic properties and is easy to process , can be recycled and reused, so that the shielding material can be reprocessed to produce new products after use (even after long-term use), which is very beneficial to saving resources (especially rare earth resources).

Claims (4)

1. rare earth modified leadless X-ray shielding plastic, it is formed and parts by weight are:

Plastics 50-100

Organic rare-earth ligand 20-600

Inorganic rare earth compound 20-600

Tenderizer 2-30

Oxidation inhibitor 1-3

Silane coupling agent 0.5-3

Said rare earth organic complex is acrylic rare earth salt, methacrylic acid rare-earth salts or their miscellany of 16 kinds of lanthanon except the promethium; The inorganic rare earth compound is rare earth oxide or the rare earth carbonate except the promethium;

Said plastics are polyethylene, ethylene-alpha-olefin copolymer, styrene analog thermoplastic elastomer, polyester type or polyether(poly)urethane analog thermoplastic elastomer.

2. according to the said rare earth modified leadless X-ray shielding plastic of claim 1, it is characterized in that: said tenderizer is low molecular weight polyethylene wax or poly-adipic acid propylidene ester.

3. according to the said rare earth modified leadless X-ray shielding plastic of claim 1, it is characterized in that: silane coupling agent is vinyltriethoxysilane or γ-An Bingjisanyiyangjiguiwan.

4. according to the said rare earth modified leadless X-ray shielding plastic of claim 1, it is characterized in that: oxidation inhibitor is four [3-(3, the 5-di-tert-butyl-hydroxy phenyl) propionic acid] pentaerythritol ester.