KR100186715B1 - Thermal insulator composition containing rice husk and rice straw - Google Patents

Abstract

The present invention can be used in the manufacture of insulation, sound insulation, building interiors, shock buffers such as cargo trays and cargo packaging, cargo laboratory coke substitutes, bulletin boards, containers such as fruit boxes, filters, etc., containing chaff or rice straw It provides a biodegradable composition. The composition of the present invention consists of 35 to 80% by weight chaff, rice straw or mixtures thereof and 20 to 65% by weight binder.

Description

Composition for the manufacture of insulation containing chaff or rice straw

The present invention relates to biodegradable compositions containing chaff and rice straw and moldings made therefrom.

The composition of the present invention can be used in the manufacture of insulation, sound insulation, building interiors, impact buffers such as cargo trays, cargo packaging, laboratory coke substitutes, bulletin boards, fruit boxes, filters, etc. It can replace plastic and styropol materials.

In construction, the use of insulation is essential for the thermal insulation of buildings. By using efficient insulation, the building's warming or cooling effect can be enhanced, providing an optimal environment and reducing energy losses.

Asbestos is widely used as an insulating material due to its excellent insulation effect, but asbestos breaks down during construction and after construction, the powder is blown, and when such asbestos powder accumulates in the human body through breathing, it causes fatal damage such as lung cancer. Therefore, asbestos is being banned as a serious pollutant.

Cellulose insulation material, which is developed and used as an alternative to asbestos, has excellent insulation performance, absorbency, insect repellency, and antiseptic properties, and is harmless to humans and is easy to construct. Therefore, cellulose insulation materials using old newspapers have been developed. However, there have been no reports of manufacturing cellulose insulation using rice straw or rice husk as main ingredients.

Rice straw and rice husk, which occur a lot in farmhouses, have been used mainly for firewood in the past, but due to industrial development and improvement of living environment, only a part of rice straw and rice husk are used as manure as the fuel source is replaced by gas kitchen equipment. It is left in paddy fields without any countermeasures. Although rice hulls and rice straws have been secured by their suppliers, no new uses have yet been developed.

The present invention can be used in the manufacture of insulation, sound insulation, building interiors, shock buffers such as cargo trays and cargo packaging, cargo laboratory coke substitutes, bulletin boards, containers such as fruit boxes, filters, etc., containing chaff or rice straw It provides a biodegradable composition.

The composition according to the invention consists of 35 to 80% by weight of rice hull, rice straw or mixtures thereof and 20 to 65% by weight of the binder.

Since the composition of the present invention is lightweight and has excellent strength and thermal insulation, it is possible to replace the existing vinyl, plastic, styropol insulation, packaging or impact buffer.

In addition, rice husk and rice straw is absolutely biodegradable in terms of environmental protection because its components are biodegradable materials having the same cellulose structure as the pulp.

Chaff or rice straw used in the present invention can be used as it is collected without a special pretreatment from the farm. Rice straw can be cut or crushed to a suitable size for use, and chaff can be used as it is or crushed. The smaller the grains of rice straw or rice husk, the more molded articles can be obtained.

Rice husk or rice straw is used in an amount of 35 to 80% by weight based on the total composition, and when used less than 35% by weight, the heat insulating or shock-absorbing effect of the composition is worsened, and when used more than 80% by weight, the amount of binder used is less. Molding is difficult

The total usage of rice husk or rice straw and the ratio of rice husk / rice straw may vary depending on the use of the final molding, and may also vary depending on the type of rice chaff or rice straw used, for example, length or degree of grinding.

In the present invention, as the binder, a conventional binder conventionally used in the cellulose insulation composition may be used, and a polymer resin binder is particularly suitable. Examples of such polymer binders include polyvinyl chloride (PVC), polyvinylacetate (PVA), polyacrylamide (PAA), polyethylacetate (PEA), diphenylmethane diisocyanate (MDI), polypriylene glycol (PPG) And derivatives thereof.

The composition of the present invention may include, in addition to rice hulls / straw straws and binders, other excipients well known in the art, which are necessary for preparing the final product.

The insulation prepared from the composition according to the present invention is similar to the existing foamed plastics in terms of density and thermal conductivity, and is particularly excellent in bending strength, compressive strength and workability.

The manufacturing method of the heat insulating material according to the present invention is not significantly different from the conventional cellulose heat insulating material manufacturing method, which will be described in more detail as follows.

Well-dried wild chaff and rice straw are used as insulation materials. Rice straw can be cut or crushed to a suitable length and chaff can be used as is or crushed.

Prepare the rice straw and / or chaff and resin. The mixed material is dispersed in a mold to a certain thickness, pressurized and molded by bringing the material and resin into close contact with each other. The molded product is dried to obtain the final product. In some cases, molding is performed by applying primary pressure to secondary pressure.

In the case of mass production, it is preferable to dilute the polymer resin used as a binder in water or a suitable organic solvent in order to facilitate mixing with the material, and in this case, remove the solvent from the oven after molding.

The polymer used as the binder may be selected appropriately depending on the use of the final molded product. For example, in the case of using PVA and PVC, when the viscosity of the resin is increased, the mixing between the rice hull and rice straw is difficult and the processing may be difficult, and when the solvent is used, the drying process becomes difficult. In comparison, MDI-PPG resin is more excellent in processability and easier to process. Also, by adjusting the concentration of the polymer resin, the tissue state of the product can be manufactured more densely or more loosely, and thus, for example, a heat insulating material requiring a more dense and rigid tissue, or a relatively poor tissue may be required. The polymer resin concentration can be adjusted to obtain a molded article suitable for the use of the final molded article such as a decorative product.

In molding, it can be heated to a suitable temperature depending on the type of resin used or the purpose of the final molding. In general, heating at the time of molding can give a harder and higher strength molded product.

On the other hand, by controlling the arrangement direction of the rice husk and rice straw during molding may affect the properties of the final molded product, for example, the density of the tissue, bending strength, compressive strength and the like. For example, if rice straw is used together or rice straw is used rather than chaff alone, it is possible to obtain a more dense and robust product, and as shown in the product number 10 shown in the examples below, the rice straw and rice hull layers alternate. When laminated to form a sandwich form can be obtained a product with more excellent bending strength. Unique characteristics are suggested depending on the arrangement of the excellent geometry.

The molding process is not essential and the final product may be manufactured by spraying the composition of the present invention as needed.

The characteristics of the molded product were tested in accordance with the measurement method of density, thermal conductivity, bending strength, and compressive strength of expanded polystyrene insulation based on the Korean Industrial Standard (KS).

① density

Cut the size of the molded sample into a size of 50 × 50mm, make three specimens, calculate the density by calculating the weight (W) and the volume (V) at room temperature, and take three average values as experimental values.

Density (kg / ㎡) = W / V

② thermal conductivity

The measurement of thermal conductivity is carried out using the flat plate heat flow method in the following configuration.

Cut the specimen into 50 × 50 × 30 mm and use the top and bottom polished well to facilitate contact with the heat source. Maintain the specimen at a constant temperature, mount the specimen when the heat source of the high heat source reaches a sufficient thermal equilibrium, measure the temperature of point A and B, and measure the value when it is no longer changed. The average of three sample measurements is used.

The calculation formula of the thermal conductivity is as follows.

Thermal Conductivity (kcal / m.hr. ° C) = 1 / Rc

Rc = T ₁ -T ₂ / q

Where 1: thickness of the test body (m)

Re: Thermal resistance of the test body (m.hr. ℃ / kcal)

T ₁ : temperature (℃) of the hot surface of the test body

T ₂ : Temperature of the low temperature surface of the test body (° C.)

q: heat flow rate per unit area (heat flow density, kcal / ㎡.hr)

(* Q value of the heat conduction device used in this experiment uses 320kcal / m.hr ℃)

③ bending strength

Bending strength is measured using a Zwiek (Material Prufung) Model No. 1445 Universal Testing Machine. The radius of the pressing wedge and the front diameter of the support is 10 6 0.2 mm and the distance between the points is 120 6 1 mm. Cut the specimen to 140 × 73.3 × 17.2mm and place it on the support, load it at the center load speed of 20mm / mim and measure the maximum load (W). At this time, the load precision is 0.1kg _f . The bending strength is measured three times by the following equation and the average value is taken.

Bending Strength (kg _f / ㎠) = 3Wl / 2bh ²

Where W: Maximum load (kg _f ): Measured value according to the specimen

l: Distance between points (cm): 12cm

b: width of test piece (cm): 7.33cm

h: Thickness of test piece (cm): 1.72cm

④ compressive strength

Compressive strength is measured by the compression test method for hard foamed plastics of KS M3831. The specimen is cut into 75 × 50 × 50 mm rectangular parallelepipeds and the cross-sectional area is within the allowable range (the minimum allowable cross-sectional area: 20.0 cm 2, the minimum cross-sectional area: 230.0 cm 2) (37.50 cm 2 in the present invention). Compressive strength is calculated using the following equation.

σ = F / A

Where σ = compressive strength (kgf / ㎠)

F: yield strain (kgf): measured value according to the specimen

A: cross-sectional area of the specimen (cm 2)

In the manufacturing method of the present invention, by stacking rice husk and straw in several layers and by arranging the chaff and rice straw of each layer differently, the density and strength of the prepared insulation can be appropriately adjusted according to the intended use, and the shape is also freely It can be modified.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited by the following Examples.

Example 1

Insulation manufacture

Well-dried wild rice husk and rice straw were used as insulation materials. Rice straw was cut to a length of about 4-20 cm, and chaff was used as it is.

Rice straw and rice hulls and resin were slowly added to the composition shown in Table 1 and mixed. The mixed materials are dispersed in a mold in a constant thickness, and are used for 5 minutes to 24 hours under a pressure of 1 kgf / cm 2 to 70 kgf / cm 2 using a fully-automatic hydraulic press (capacity 60 tons, stroke torque 400 m / m, motor 10HP). It was stuck to bring the material and the resin into close contact. The mold was removed from the mold and dried at room temperature to obtain the final product. In some cases, it was prepared by applying the first to second pressure and removing the solvent in the oven.

Example 2

Evaluation of Molding Properties

The density, thermal conductivity, bending strength and compressive strength of the finished molded product were measured.

1. Density Evaluation

The molded article prepared in Example 1 was cut to an appropriate size to measure the density, and the results are shown in Table 2. It can be seen that the density of the product is not proportional to the molding pressure applied. This is because the tissues of the rice hull and rice straw are composed of cellulose containing very much porosity, and are compressed by mixing with the resin in the pre-molding state and in the pressurized state, and in the relaxed state, the bulky expansion can be caused in a large number.

2. Thermal conductivity evaluation

The thermal conductivity was measured by the method described above and the results are shown in Table 2.

3. Bending Strength

The bending strength was measured by the method described above and the results are shown in Table 2.

4. Compressive strength

Compressive strength was measured by the method described above and the results are shown in Table 2.

As can be seen in Table 2, the molded article prepared from the composition according to the present invention is similar to the expanded polystyrene insulation in terms of density and thermal conductivity, and exhibits a much better value than the expanded polystyrene in bending strength and compressive strength.

Claims (2)

35 to 80% by weight of chaff, rice straw or mixtures thereof and 20 to 65% by weight of a binder selected from polyvinylchloride, polyvinylacetate, polyacrylamide, polyethylacetate, diphenylmethane diisocyanate and polypropylene glycol and derivatives thereof Composition for producing a heat insulating material. The composition of claim 1 wherein said composition is used as a substitute for expanded polystyrene.