MXPA04008451A - Improved process for the manufacture of a low-density plastic sand, plastic sand and compositions thereof. - Google Patents

Abstract

The present invention refers to a low-density plastic sand made of a low-density polyethylene, which can be virgin or recycled, as well as the process for obtaining and manufacturing same and compositions thereof. The plastic sand obtained by the manufacturing process can be acquired upon using a low-density polyethylene regardless of its type, such as: straws, glasses and disposable plastics, bags, bottles, etc, which is recovered from rubbish dumps as solid wastes or other industrial sources.

Description

IMPROVED PROCEDURE FOR MANUFACTURING A LOW-DENSITY PLASTIC SAND, PLASTIC SAND AND COMPOSITIONS.

BACKGROUND OF THE INVENCIÓ. The present invention relates to a low density plastic sand based on recycled low density polyethylene and to the compositions formed by it, the use of plastics in the world has flooded the vital spaces contaminating the soils and the aquifer mantles with a wide range of waste, which due to its slow biodegradation has bordered on finding alternatives for use for these materials by recycling them and removing them from dumps in the open air, where due to environmental effects (sun, air, etc) they give off gases and toxic fumes that aggravate the deterioration of aquiferous soils and mantles, as well as the creation, accumulation and proliferation of parasitic bacteria and animals, on the other hand conventional sand as a basic material for mortar (sand, cement and water) is used throughout construction for the union of block, brick and partition in the construction of walls, and its process of elaboration this process, also damages and it pollutes the environment in addition to the high transportation costs which significantly increase housing and building costs.

There are different methods of recycling low density polyethylene but none like the one of the present invention, this fine sand is obtained or manufactured from all kinds of recycled low density polyethylene plastics, which by means of fusion are transformed into fine sand that is 53% lighter than conventional sand and can be used as a mortar or in partitions and in concrete pieces.

DESCRIPTION OF THE INVENTION The present invention refers to a plastic sand of low density based on recycled or virgin low density polyethylene, to the process of obtaining and manufacturing and to the compositions formed by this, the plastic sand obtained by the manufacturing process, It is obtained by using low density polyethylene of any kind, such as straws, cups and disposable plates, bags, bottles, etc., which is recovered from garbage dumps as solid waste or from any other industrial source where it is located. The raw material of this sand of the present invention consists of all types of low density polyethylene found in garbage dumps as solid or industrial waste, when the polyethylene is heated to its melting point or more. this is transformed surprisingly occurring a change, that is to say it becomes less branched and less dense and therefore more flexible, this rearrangement or reorientation of polymer chains in the low density polyethylene is carried out with this procedure to produce the plastic sand, once assembled the plastic that is low density polyethylene is placed in a closed container which is heated when direct fire is applied, the container has an outlet conduit through which the gases of the fusion and part of combustion produced during this stage come out directly to the nozzles of the burner resulting in the elimination of said gases by combustion avoiding the contamination of the environment, this container also has means of feeding and temperature regulator, the temperature range recommended to carry out the fusion process and part of combustion of the plastic is approximately between 65 ° C to 90 ° C preferred At 70 ° C and 80 ° C for a period of time of 3 to 20 minutes, preferably 3 to 5 minutes, it is important not to exceed this range and not reach beyond 100 ° C, this is because if this temperature is exceeded, it is lost the raw material, that is to say, begins to burn, forming coal and losing the reorientation and molecular rearrangement of the low density polyethylene polymer, which greatly affects the properties of this, that is to say, Transforms into ashes in the form of gas which are completely eliminated upon reaching the burner, when carrying out this step the polyethylene is able to break the highly branched chains that make up the polymer causing its reorientation and rearrangement forming new unbranched chains with new properties, such as flexibility, ie the plastic becomes less dense and more flexible, This plastic material with new chains is added a predetermined amount of oil in solid form known as curved waste chapopote, this amount varies from approximately 0.1% up to 30% preferably 2% in proportion to the weight of the polyethylene raw material fused, leaving the Binding of these materials at the same temperature for a period of time of 10 to 35 minutes. The chapopote surprisingly favors the formation of a larger polymer molecule and with greater flexibility. Once the plastic is perfectly mixed, the chapopote is removed from the container for emptying on a clean surface or in containers until it crystallizes at room temperature, once crystallized, the formed substrate which is brittle and consequently forms different grain sizes. , it rises from the surface or containers and is sifted by passing it throsieves of Different diameter, which allows to obtain a control in the diameter in the grain according to the requirements or needs of use. The size of the glass or grain can be from very fine to an inch, the grains that are left in the upper sieves are collected to later pass them through a mill and reduce their diameter for later sieving. If you want to move the plastic sand thus obtained from one place to another, it is recommended to provide a little moisture to prevent it from being lost due to its great lightness. Next, the manufacturing process or manufacture of the plastic sand of the present invention is described, which comprises the following steps; A) Collect raw material consisting of all types of low density polyethylene found in gge dumps as solid or industrial waste; B) once assembled the plastic that is low density polyethylene is placed in a closed container which is heated when direct fire is applied, the container has an outlet conduit through which the gases of the fusion and part of combustion produced during this stage they go directly to the burner nozzles resulting in the elimination of said gases by combustion avoiding the contamination of the environment, this vessel also has feeding means and temperature regulator, the recommended temperature range to carry out the melting process and part of combustion of the plastic is approximately between 65 ° C to 90 ° C preferably 70 ° C and 80 ° C during a period of time of 3 to 20 minutes, preferably 3 to 5 minutes, it is important not to exceed this range and not reach beyond 100 ° C, this is because if this temperature is exceeded, the raw material is lost, that is, it starts burn coal forming and losing the reorientation and molecular rearrangement of the polymer of low density polyethylene, which greatly affects the properties of this, ie it is transformed into ash in the form of gas which are completely eliminated upon arrival at the burner; C) adds a predetermined quantity of oil in solid form known as curved waste chapopote, this amount varies from approximately 0.1% up to 30% preferably 2% in proportion of the weight of the merged polyethylene raw material and, let the union of these materials at the same temperature for a period of time of 10 to 35 minutes; D) once the plastic is thoroughly mixed and the tar is removed from the container for emptying on a clean surface or in containers until it crystallizes at room temperature; F) once the formed substrate has crystallized which is brittle and therefore forms different grain sizes, it rises from the surface or containers and is sifted by passing it through sieves of different diameter, which allows to obtain a control in the diameter in the grain according to the requirements or needs of use; G) the size of the glass or grain can be from very fine to an inch, the grains that are left in the upper sieves are collected to later pass them through a mill and reduce their diameter for later sieving of step F) above. The properties and characteristics of the plastic sand obtained by this manufacturing or manufacturing process are obtained in the laboratory and the results and the different tests are mentioned below. "Granulometry of the sand" The plastic sand was subjected to the granulometric test to determine its modulus of fineness (M.F.); also to know the following elements: 1. Volumetric Weight 2. Density 3. Absorption 4. Lost by Washing 5. Colorimetry First granulometry test For the granulometry of the plastic sand, a 500 g sample was taken. It was passed through meshes number 8, 14, 38, 48 and 100, the dust was collected giving the following results.

Fineness module By specification the fineness module of the plastic sand is inside the meshes numbers 8, 14, 28, 48 and 100. Mesh # 100 Mesh # 100 M.F. = 1 / ??? S per cent cumulative referrals Mesh # 4 M.F. = 218/100 M.F. = 2.18 (fine plastic sand). This plastic sand can already be classified by its fineness module, based on the designation 4 of the A.S.T.M. according to the following chart.

Ciase Module of fineness Weight of the sample in grams. Aiena thick 2.50 to 3.50 400 to 800 Fine sand 1.50 to 2.50 200 to 400 Very fine sand 0.50 to 1.50 100 to 200 As the result of the fineness module gave 2.18 it falls within the classification range of 1.50 to 2.50 giving a class of fine plastic sand.

Second granulometric test and determination of the fineness module Fineness module By specification the fineness module of the plastic sand is inside the meshes numbers 8, 14, 28, 48 and 100. Mesh # 100 agreement module As the result of the fineness module gave 0.81 it falls within the classification range of 0.50 to 1.50 giving a class of very fine sand.

Volumetric weight of plastic sand The volumetric weight of a material varies according to the state of compaction of the sample, as well as the humidity it has. In accordance with the regulatory requirements of the subject, except for special cases, always use the material in the state of saturation and superficially dry for the determination of the volumetric weight, without tamping, In this case a cubic deposit of thick non-deformable wood with a capacity of 5 liters was used. This deposit of known weight (tare), was filled with a ladle, hovered gently inside the bucket with a spatula at a height not more than 2 inches from the upper edge, then it is leveled and weighed, obtaining the following result for plastic sand: PV = (Total weight-tare) / volume P.V. (4,566 kg. - 2,320 kg.) / 5 Its. P.V. 49 kg./m Density of plastic sand To determine the density of plastic sand, the bottle of Lechatellier or Chapman was used, in which water was kept up to the mark of O C.C., then 50gr of sand was taken. plastic saturated and superficially dry and are deposited in the bottle while stirring gently, giving it rotating movement, to dislodge the air bubbles. The bottle was left to stand until it rose and the bubbles disappeared to be able to make the new reading, which directly gave the volume evicted by the 50 gr placed of the plastic sand giving the following result: provide corrective data to achieve quality control in the manufacture of the concrete.

Saturated and superficially dry plastic sand The plastic sand has a dark color and to obtain a saturated and superficially dry plastic sand, 50 g of this material was placed to saturate in water for 24 hours, after which the As much water as possible, by known methods, taking care not to drag dust. Then the material began to dry slowly in a burner. So that the process is not altered temperatures below 110 ° C are recommended, while stirring the plastic sand until all the free water disappears, and then drying is continued under the action of sun or wind until the plastic sand He stopped forming lumps by squeezing with his hand or pressing a handful with both palms. This behavior indicated that the material was very close to the state that was to be achieved and therefore, the test with a foil cone was used. The cone was completely filled with plastic sand and rammed 25 times on the free surface with a "tamper" with a circular section that has an area of one inch in diameter (2.54 cm) and weight 12 ounces. The mold was filled to capacity with plastic sand and carefully removed, resulting in the sand almost taking the shape of the mold. This indicated that it still had surface moisture that gave it an apparent cohesion.

The tests of the cone were continued twice more until the moment in which the material remained as desired, that is, where it took its angle of natural rest.

Loss per wash This test was carried out to know the amount of silt that the sand could have since sometimes the sand is not characterized in the trays and it is placed directly in the soil therefore it could influence in increasing the contractions of the concrete and in decreasing your resistance A sample of completely dry plastic sand with a weight of 600 grams was taken and placed in the # 200 mesh and the washing started until the water that is running, after having passed through the mesh, comes out completely clean. The washed plastic sand was collected and dried again in the stove, where it was always careful not to burn the organic particles it might contain. Once the plastic sand had dried, it was re-weighed and the difference with the original weight gives the weight of dust contained in the sand, which was expressed in percentage in relation to the original weight, giving the following data: Loss per wash = (500 gr of the sample - 487.5 / 500,) * 100 = 2.5% According to the standards, accepted sands should have a loss of less than 5%, in this case the result was 2.5%. This result is due to the fact that the material used is polyethylene (straws, disposable cups, disposable plates and plastic bags).

Test for the determination of moisture in the fine sand For the start of this test the porcelain capsule was first washed with the intention of removing impurities, once this was done it was placed in the oven for 10 minutes at 100 ° C, it was taken out and placed in a glass desiccator for approximately 15 minutes. The balance was calibrated and the empty capsule was weighed, immediately after the sample was placed on the porcelain weighed (34.3 grams of sample), placed in the oven at 60 ° C with an approximate time of 2 hours, the sample was taken out and placed in the desiccator for approximately 20 minutes. The final result was 69.9 grams, therefore, the moisture content was 0.1 grams.

Colorimetry The Colorimetry test provides an index of the content of organic matter or other elements in the plastic sand, which may be lower or higher than what represents a so-called "normal color". The test was carried out in a bottle of 250 ml capacity, in which approximately 5 125 ml of plastic sand per test was housed. A solution of caustic soda (NaOH) 3% (one liter of water with 30 g of caustic soda (NaOH)) was added up to the 200 ml mark, which level with additions of solution should be retained after vigorously shaking the flask . It was left to stand for 24 hours, after which the color of the solution in the bottle is compared with the normal colored glass. The data obtained from this test correspond to a minimum of organic matter, since the polyethylene used in the elaboration of plastic sand is a waste product. The analysis of the ash determination result at a temperature of 975 ° C shows a low percentage, because the sample had 25% impurity by weight, so the final percentage of the elements analyzed were the following: 5 CARBON 67% HIDROGEN 8% 0 ASHES 25% TOTAL 100% The plastic sand obtained is an alternative construction material, low cost, incombustible, insulating, thermal, easy to handle, lighter than conventional sand, compatible with conventional sand, also with a great resistance to compression efforts and can be use in walls and slabs, together with other materials without affecting their properties, as added when used in mortars and concretes, or supplying or complementing conventional sand, in addition to lightening the concrete by at least 30%, being more light, less dense and still retain its volume with that of normal sand, the plastic sand retains a minimum of moisture which gives consistency avoiding that its lightness is not so volatile avoiding complications when gathering the material and transporting it. Within the chemical properties the plastic sand contains a high resistance to fire, approximately 80 to 100 ° C, starting to melt a quarter of it at 200 ° C without changing its structure, a characteristic that it shares with that material with the That combine, either mortar or partitions giving greater resistance to fire, water, moisture and wear extending its useful life 10 times more than conventional materials. One of the main features of this product is that being very similar to normal sand has many uses in the area of construction, cheaper, due to its origin with recycled polyethylene, the cost of it in any construction or building. Here are some of its properties: 30% cheaper than conventional sand - No specialized material required for its production - No specialized labor required - Reduces structure cost up to 50% in inch size (1.9 to resistance change its in a fourth EXAMPLES EXAMPLE 1 The following plastic sand composition is prepared with the procedure described above, the plastic sand includes 2% waste cured tar, in proportion to the weight of the low density polyethylene plastic material of 5, 4, 12, 200, and 1000 grams, leaving the elements together at the same temperature for 10 minutes, when using plastic sand in mortars (usually water, sand, cement), the following specification must be taken: 50% natural sand and 50% plastic sand also of water and cement, if it is going to be used in parks and gardens, it is important to make a meticulous study with experts in the matter to be able to mix it in the following way 55% of normal sand and 45% of plastic sand.

EXAMPLE 2 The same procedure as in the previous example but using a plastic sand composition including polyethylene that can vary from 55, 10, 30, 200 or 500 kilograms, with 2% of cured waste chapopote, with this plastic sand obtained is They prepare several types of partition that include several typical components for this elaboration.

Below is shown in Table 1 comparative examples of stress to the compression of different types of partition made with plastic sand of the present invention.

TABLE 1 Note: Efforts were obtained through compression tests.

A report is attached with a description of the materials used for the preparation of partitions (samples). Some of these materials correspond to patent applications that are being filed simultaneously with the present. SAMPLE (No) MATERIALS USED IN THE TABIQUE. 1. - Wood chip, granulated styrene, clay, sand and cement type I. 2. - Plastic, granulated styrene, clay, sand and cement type I. 3. - Plastic sand, granulated styrene, wood chip and cement type I 4. - Silica, granulated styrene and sawdust. 5. - Newspaper, cardboard, clay, sand, wood shavings and type I cement. 6. - Styrene, gasoline, clay and sand. 7. - Granulated styrene, clay, wood shavings and type I cement. 8. - Newspaper. 9. - Black smoke, clay, sand, plastic sand, cement type I. 10. - Molasses from sugar cane, plastic sand, clay, sand and cement type I. 11. - Sawdust, beach shell and white cement.

The present invention should not be considered as limited to the particular examples described above, but should be understood to cover all aspects of the invention clearly as seen in the appended claims. Various modifications, equivalent processes, as well as numerous compositions and methods to which the present invention may be applicable and will be readily apparent to those skilled in the art to which the present invention is directed upon the instant revision of the specification. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (1)

1. CLAIMS Having described the invention as above, the following claims are claimed as property. A method of manufacturing or manufacturing plastic sand based on recycled low density polyethylene plastic, characterized in that it comprises the steps of: A) collecting the raw material consisting of all types of low density polyethylene found in garbage dumps as solid or industrial waste; B) once assembled the plastic that is low density polyethylene is placed in a closed container which is heated when direct fire is applied, the container has an outlet conduit through which the gases of the fusion and part of combustion produced during this stage they go directly to the nozzles of the burner resulting in the elimination of said gases by combustion avoiding the contamination of the environment, this vessel also has means of feeding and temperature regulator, the temperature range recommended to carry out the fusion process and part of combustion of the plastic is between approximately 65 ° C to 90 ° C, preferably 70 ° C and 80 ° C for a period of time of 3 to 20 minutes, preferably 3 to 5 minutes; C) add a predetermined quantity of oil in solid form known as curved waste pellet, the amount varies from approximately 0.1% to 30% preferably 2% in proportion to the weight of the fused polyethylene raw material and, let the union of these materials to the same temperature for a period of time of 10 to 35 minutes; D) once the plastic and the chapopote are thoroughly mixed, the mixture is removed from the container to be emptied on a clean surface or into containers until it crystallizes at room temperature; F) once the formed substrate has crystallized which is brittle and consequently forms different grain sizes, it is lifted from the surface or containers and sieved by passing it through sieves of different diameter; G) the grains that are left in the upper sieves are collected to subsequently pass them through a mill and reduce their diameter for later sieving of step F) above. 2. The method according to claim 1, characterized in that the low density polyethylene used is selected from any class such as, for example, straws, cups and disposable plates, bags, bottles, etc., which is recovered from garbage dumps. as solid waste or from any other industrial source. 3. The method according to claim 1, characterized in that in step B) when heating the polyethylene it is possible to break the highly branched chains that constitute the polymer causing its reorientation and rearrangement forming new unbranched chains with new properties. The method according to claim 1, characterized in that in step C) the added tar contributes to the formation of a larger polymer molecule and with greater flexibility. 5. A plastic sand based on recycled plastic characterized in that it comprises recycled low density polyethylene and oil in solid form of 0.1% up to 30%, preferably 2%, all this must be adjusted up to 100%. 6. A plastic sand according to claim 5, characterized in that the oil in solid form is selected from curved scrap. 7. A plastic sand according to claim 5, characterized in that the low density polyethylene is selected from all types of low density polyethylene of any kind, such as, for example, straws, disposable cups and plates, bags, bottles, etc. which is recovered from garbage dumps as solid waste or from any other industrial source. 8. The use of a plastic sand of claim 5, obtained by the process of claim 1 to manufacture partition, mortar, concrete and in construction.