Method for manufacturing an expanded cellular plastic product and use of pentane in the manufacture of a cellular plastic product

Abstract

Method for manufacturing an expanded cellular plastic product, in which method cellular plastic beads are expanded and sintered in a mould into a cellular plastic product by means of steam, and pentane is added to the steam to be introduced into the mould. Pentane improves sintering of the product.

Description

[0001] METHOD FOR MANUFACTURING AN EXPANDED CELLULAR PLASTIC PRODUCT AND USE OF PENTANE IN THE MANUFACTURE OF A CELLULAR PLASTIC PRODUCT

[0002] Field of the invention

[0003] The invention relates to a method for manufacturing an expanded cellular plastic product and to a use of pentane in the mould casting according to the appended independent claims.

[0004] Background of the invention

[0005] Expanded cellular plastic products, such as products manufactured from expanded polystyrene (EPS), are manufactured by expanding cellular plastic beads, which are impregnated with a blowing agent, In a mould by means of steam. Pentane, which has been impregnated to the cellular plastic beads used as raw material, for example polystyrene beads, is generally used as a blowing agent. The cellular plastic beads are first dosed into a pre-expanding reactor where they are expanded by means of steam and pressure. These expanded beads are led from the pre-expanding reactor to storage silos, where they are allowed to obtain the required strength properties. From the storage silos, the cellular plastic beads are introduced into a mould, where they are manufactured by means of steam into a product with a desired form and size. The combination of heat, pressure and moisture further expands the beads in the mould and makes them adhere tightly to each other. A large block of cellular plastic product can be manufactured in the mould, or the product can be formed into a desired form in the mould. Especially in thermal insulation plate production, a large block is commonly manufactured in a mould, out of which thermal insulation plates of desired thickness are sawed.

[0006] Sintering of the cellular plastic product in the mould is important, as it effects waterproofness, permeability of the steam and mechanical strength properties of the product. Objectaanndddescription oftheinvention

[0007] An object of the present invention is to introduce a new method for manufacturing expanded cellular plastic products, by which method sintering of the final product can be improved.

[0008] In order to attain this object, the method according to the invention is primarily characterised in what is presented in the characterising part of the independent claim. The use according to the invention is characterized in what is presented in the independent claim.

[0009] The other, dependent claims present some preferred embodiments of the invention.

[0010] In a typical method according to the invention for manufacturing an expanded cellular plastic product, the cellular plastic beads, to which blowing agent is impregnated, are expanded in a mould into a cellular plastic product by means of steam, and pentane is added to the steam to be introduced into the mould, and / or steam which comprises pentane and has been recovered from the manufacturing process of the expanded cellular plastic product is introduced into the mould.

[0011] According to the invention, pentane is used in a mould casting of a cellular plastic product, wherein pentane is added to the steam to be introduced into the mould.

[0012] The invention is based on the fact that pentane is found to improve sintering and expanding of the cellular plastic product in the mould casting or mould foaming process of the product, when pentane is added to the steam to be introduced into the mould. In an embodiment of the invention, steam which comprises pentane and has been recovered from the manufacturing process of the cellular plastic product can be introduced into the mould. Thus, the method and use according to the invention enables an easy and simple way of improving the quality of cellular plastic products. The method according to the invention affects the waterproofness, steam permeability and mechanical strength properties of a cellular plastic product.

[0013] Short description of the drawings The invention is described in more detail in the following figures, in which

[0014] Figure 1 shows a manufacturing process of a cellular plastic product according to an embodiment of the invention, wherein pentane is added to the steam to be introduced into a mould

[0015] Figures 2a and 2b show plates manufactured from expanded polystyrene (EPS). The plate in Figure 2a is manufactured conventionally without adding pentane to the steam to be introduced into a mould, and the EPS plate in Figure 2b is manufactured according to the invention by adding 0,6% pentane to the steam introduced into the mould, calculated from the amount of steam.

[0016] Detailed description of the invention

[0017] Expanded cellular plastic products, such as products made of expanded polystyrene, expanded polyethylene, expanded polypropylene or expanded polylactide, are typically manufactured by expanding the cellular plastic beads used as raw material in a mould by means of steam. This can be called mould casting or mould foaming. In a typical manufacturing method, cellular plastic beads which have been impregnated with a blowing agent, are introduced into a mould where they are further expanded by means of steam and sintered into a final product. Typically, the cellular plastic beads are pre-expanded already before the mould casting phase. In the method according to the invention, pentane is added to the steam to be introduced into the mould, and / or the steam which comprises pentane and has been recovered from the manufacturing process of the expanded cellular plastic product is introduced into the mould. Pentane improves sintering of the product.

[0018] Figure 1 shows a manufacturing process of a cellular plastic product according to an embodiment of the invention, wherein pentane is added to the steam to be introduced into a mould. In the manufacturing method shown in Figure 1 , for example in the manufacturing method of expanded polystyrene (EPS) product, polymer beads or cellular plastic beads, which have been impregnated with a blowing agent, are first introduced into a pre-expansion phase, where beads are expanded by means of steam and pressure. From the pre-expansion phase, the cellular plastic beads are introduced to storage silos, where they are allowed to obtain the required strength properties. From the storage silos, the pre-expanded cellular plastic beads are introduced into a mould, where they are expanded and sintered by means of steam into a cellular plastic product with a desired form and size. In the mould, the cellular plastic products can be formed into a large block product, such as in thermal insulation plate production, whereby thermal insulation plates with desired thickness are cut out of a larger block. In a method according to the invention, pentane is added to the steam to be introduced into the mould, in another embodiment of the invention, steam which comprises pentane and has been recovered from the manufacturing process of the expanded cellular plastic product is introduced into the mould. Steam can be recovered for example from the mould casting phase and circulated back to the mould. Waste steam to be recovered from the mould casting machine and / or pre-expansion phase may comprise pentane, which is used in the manufacturing process as a blowing agent and is impregnated to EPE, EPP and EPS beads prior to the pre-expansion. In the method according to the invention, also pentane in the waste steam can be circulated in the process, and it can enhance sintering of the products in the mould casting phase. This way the method according to the invention also reduces pentane emissions.

[0019] According to an embodiment of the invention, 0.01 - 2% pentane, preferably 0.1 - 1 %, is added to the steam to be introduced into the mould, calculated from the amount of steam. According to an advantageous embodiment, 0.1 - 2% pentane, preferably 0.1 - 1 %, is added to the steam to be introduced into the mould, calculated from the amount of steam.

[0020] In the method according to the invention, pentane is added into the steam to be introduced into the mould, which means that pentane is added to the steam or pentane is introduced into the mould, whereby it mixes with the steam. According to an embodiment of the invention, pentane is added to the steam before introducing the steam into the mould, and / or pentane is introduced into the mould where it mixes with the steam. For adding pentane to the steam, any equipment suitable for the purpose can be used.

[0021] The pentane to be added to the steam can comprise n-pentane, isopentane, cyclopentane, or mixture thereof. In this application, cellular plastic refers to plastics of which foamy materials have been made. According to an embodiment of the invention, the cellular plastic beads used in the manufacture of cellular plastic products comprise polystyrene, polyethylene, polypropylene, or polylactide. Thus, the cellular plastic product according to the invention is manufactured from expanded polystyrene (EPS), expanded polyethylene (EPE), expanded polypropylene (EPP), or expanded polylactide (EPLA). The cellular plastic product manufactured by the method according to the invention thus comprises polystyrene, polyethylene, polypropylene, or polylactide.

[0022] The method according to the invention enables also use of cellular plastic beads originating from recycled cellular plastic material as raw material in the manufacturing method. This is possible due to the addition of pentane to the steam to be introduced into the mould, and / or steam which comprises pentane and has been recovered from the manufacturing process of the expanded cellular plastic product is introduced into the mould, thus improving gluing of the cellular plastic beads to each other, even though the cellular plastic beads originating from the recycled cellular plastic material do not themselves comprise blowing agent enabling expansion of the beads. In the method according to the invention, at least part of the cellular plastic beads to be introduced into the mould may comprise cellular plastic beads originating from a recycled cellular plastic material. Thus, pentane can be used in the mould casting of a cellular plastic product which comprises cellular plastic beads originating from a recycled cellular plastic material.

[0023] The method according to the invention can be used for manufacturing all kinds of expanded cellular plastic products. Typically, the method according to the invention is used for manufacturing products manufactured from expanded polystyrene, expanded polyethylene, expanded polypropylene, or expanded polylactide. The product to be manufactured can be any product. The mould casting enables manufacturing of products with different sizes and forms. According to an embodiment of the invention, the cellular plastic product is a thermal insulation material, preferably a thermal insulation plate.

[0024] Example A thermal insulation plate was manufactured conventionally from expanded polystyrene by expanding pre-expanded polystyrene beads in a mould by means of steam. The obtained EPS-plate is shown in Figure 2a.

[0025] Respectively, a thermal insulation plate was manufactured from pre-expanded polystyrene beads by expanding the pre-expanded polystyrene beads by means of steam by adding 0,6% pentane to the steam to be introduced into the mould, calculated from the amount of steam. The obtained EPS-plate is shown in Figure 2b.

[0026] As can be seen by comparing Figures 2a and 2b, the plate in Figure 2b is better sintered. Thus, it can be noted, that adding pentane to the steam in the mould casting phase improves sintering.

Claims

Claims1. Method for manufacturing an expanded cellular plastic product in which method cellular plastic beads, to which a blowing agent is impregnated, are expanded in a mould into a cellular plastic product by means of steam, characterised in that pentane is added to the steam to be introduced into the mould, and / or steam which comprises pentane and has been recovered from the manufacturing process of the expanded cellular plastic product is introduced into the mould.

2. Method according to claim 1 , characterised in that 0.01 - 2% pentane, preferably 0.01 - 1 %, is added to the steam, calculated from the amount of steam.

3. Method according to claim 1 or 2, characterised in that pentane is added to the steam before introducing the steam into the mould, and / or pentane is introduced into the mould where it mixes with the steam.

4. Method according to any of the preceding claims, characterized in that pentane comprises n-pentane, isopentane, cyclopentane, or a mixture thereof.

5. Method according to any of the preceding claims, characterised in that the cellular plastic beads comprise polystyrene, polyethylene, polypropylene, or pclylactide.

6. Method according to any of the preceding claims, characterized in that the cellular plastic beads comprise cellular plastic beads originating from a recycled cellular plastic material.

7. Method according to any of the preceding claims, characterized in that the cellular plastic product to be manufactured is a thermal insulation material, preferably a thermal insulation plate.

8. Use of pentane in a mould casting of a cellular plastic product, wherein pentane is added to the steam to be introduced into the mould.

9. Use according to claim 8, characterised in that 0.01 - 2% pentane, preferably 0.01 - 1%, is added to the steam, calculated from the amount of steam.

10. Use according to claim 8 or 9, characterised in that the cellular plastic product comprises polystyrene, polyethylene, polypropylene, or polylactide.11 . Use according to any of the preceding claims 8-10, characterized in that the cellular plastic product comprises cellular plastic beads originating from a recycled cellular plastic material.

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