WO2009136865A1

WO2009136865A1 - Synthetic rubber and/or thermoplastic elastomers containing additives and the products provided therewith and use thereof

Info

Publication number: WO2009136865A1
Application number: PCT/SG2008/000170
Authority: WO
Inventors: Poh Lai Benjamin Lee
Original assignee: Gewinnen Polymers Pte Ltd
Priority date: 2008-05-07
Filing date: 2008-05-07
Publication date: 2009-11-12

Abstract

A method of preparing synthetic rubber and/or thermoplastic elastomers that result in the clarification of the final physical appearance of synthetic rubber and/or thermoplastic elastomers products, making it clearer and more transparent, said method comprising the careful selection of a good grade silicon rubber or thermoplastic elastomers raw material, the blending of the desired colour pigment with the raw material using mills or blenders, the placing of the solution onto the processing machine to mold out to the final casing product, which is done either through the process of compression, transfer or injection molding with the use of a highly polished and hard chrome mold in order to achieve the high clarity and transparency effect.

Description

SYNTHETIC RUBBER AND/OR THERMOPLASTIC ELASTOMERS

CONTAINING ADDITIVES AND THE PRODUCTS PROVIDED

THEREWITH AND USE THEREOF

FIELD OF THE INVENTION

While synthetic rubber and/or thermoplastic elastomers (TPE) material produce end products that are essentially not clear nor transparent like that of plastic material, this invention seeks to formulate and produce synthetic rubber or thermoplastic elastomers containing preparation that clarifies the final physical appearance of synthetic rubber and/or thermoplastic elastomers products. The end products are therefore clearer and more transparent.

The invention also explores methods of manufacturing that can produce the same results and the use of such preparation in the manufacture of a variety of products, mostly casings and protective covers for electrical and electronic products. The invention further explores compounding the synthetic rubber and/or thermoplastic elastomers preparation with additives, including colours, 'glitters, florescence, and other appearance enhancing additives, disinfectants, germicides and fragrance to give a variety of benefits such as aesthetics and functionality to the end products derived from the rubber or thermoplastic elastomers material.

BACKGROUND OF THE INVENTION

An elastomer is a durable material with the mechanical (or material) property that can undergo much more elastic deformation when subject to stress than most materials. At the same time, it has the ability to return to its previous size and shape without permanent deformation nor tears. Synthetic rubber, such as silicon rubber, refers to a type of artificially made polymer material which acts as an elastomer. Synthetic rubber serves as a substitute for natural rubber in many cases, especially when improved appearance such as colour appearance and material properties are required.

Thermoplastic elastomers refer to a class of copolymers or a physical mix of polymers (usually a plastic and a rubber) which consist of materials with both thermoplastic and elastomeric properties. Thermoplastic elastomers materials have the potential to be recyclable since the said material can be molded, extruded and reused, unlike plastics. Added to having the hardness of plastics, they have typical elastic properties of rubbers, which are not recyclable owing to their thermosetting characteristics.

The availability of thermoplastic elastomers have indeed revolutionized our daily lives. Their low price, high processability, and the fact that they show both the advantages typical of rubbery materials and plastic materials have led to the use of thermoplastic elastomers in ever more sophisticated applications.

In the electrical and electronic field, for example, electrical and electronic gadgets are sometimes protected by plastic, which although transparent, is most likely to crack or to chip and does not provide a good form of protection against accidental damage, for example, through dropping of the electrical or electronic gadgets that it serves to protect. Enclosing the gadgets either in rubber casings, which can be synthetic in nature, or thermoplastic elastomer materials, particularly, has the advantage of increased stability against mechanical and electrical shock, radiation, vibration or simply to protect the gadget against accidental damage. Additionally, it also serves the purpose of providing a trendy and an aesthetic appeal to the end product. Silicone rubber, more scientifically known as polysiloxane, is one of the most useful polymers in the modern world, mostly because it is durable and offers excellent resistance to extreme temperatures, being able to operate normally from -55°C to +300⁰C. In such conditions the tensile strength, elongation, tear strength and compression set can be far superior as compared to conventional rubbers, making it a popular material for use as covers and casings for electrical and electronic gadgets and other products.

This invention sought to improve on the appearance of synthetic rubber and/or thermoplastic elastomers in the final product, which comprise, but not limited to, covers and casings for electrical and electronic gadgets. While the conventional use of synthetic rubber and/or thermoplastic elastomers essentially do not result in transparent product, this invention sought to explore the possibility and invent ways of making synthetic rubber and/or thermoplastic elastomers products to be clearer and more transparent, so that surface of the gadgets enclosed therein can be seen by the user.

The invention further sought to improve the synthetic rubber and/or thermoplastic elastomers preparation according to the desired colour, hardness, mechanical strength, glitters and luminance, fragrance, particularly of fruits and flowers for practical and aesthetic appeal, with the intention of drawing attention of the young, in particular, to the products. For those who are conscious about health, disinfectants and germicide can also be added.

Several methods of processing the synthetic rubber and thermoplastic elastomers casings have been explored. It can essentially be through the process of compression, transfer or injection molding using a highly gloss polished and hard chrome mold. Other suitable processes can also be used as alternatives. Known conventional methods of production are explored and used in a novel and different context. BACKGROUND ART

WO/1998/004645 relates to a silicone rubber-containing, after glowing preparation, which is characterized in that said silicone rubber is a curable silicone rubber and that the composition includes 0.1 - 10 per cent by weight of an after glowing pigment, herein is understood to mean a fluorescent and/or a phosphorescent pigment.

According to the said prior art, the silicone rubber is preferably cured by means of moisture or by means of a peroxide compound of a peroxide- free compound. Advantageously the silicone rubber according to the invention is transparent after curing. The advantage of this is that less after glowing pigment needs to be included in the silicone rubber- containing after glowing preparation in order to provide sufficient afterglow.

The preparation according to the invention may include one or more usual colorants and/or other (fluorescent and/or phosphorescent) pigments and or plasticizers.

The present invention sought further improvements by covering not only silicon rubber but also thermoplastic elastomers and the addition of other additives as well. Known conventional methods of production are explored and used in a novel and different context.

US Patent No 20040039145 pertains to method of preparing transparent silicone-containing copolycarbonates.

The invention relates to a method for the preparation of silicone- containing copolycarbonates. More particularly the method relates to a method for obtaining silicone-containing copolycarbonates which are transparent. Silicone copolycarbonates are typically prepared by reaction of a mixture of a siloxane-containing bisphenol and a bisphenol such as bisphenol A under interfacial reaction conditions with phosgene and an aqueous acid acceptor such as sodium hydroxide in water. Alternatively, siloxane-containing copolycarbonates may be prepared by reaction of a chloroformate-terminated polycarbonate oligomer with a siloxane- containing bisphenol.

PCT/US2001/046502 relates to clear, autoclavable thermoplastic formulation for medical liquid containers. A clear, flexible, thermoplastic material capable of being processed into hollow shapes by conventional thermoplastic processing methods and subsequently autoclaved, comprises three components; from about 40 to 70 % by weight of a polyolefin consisting essentially of polypropylene, admixed with from about 5 to 40 % by weight of a polymer selected from the group consisting of ethylene loweralkyl acrylate; and from about 5 to 40 % by weight of a thermoplastic elastomer composition selected from the group consisting of a block copolymer consisting essentially of ethylene butylene and having terminal polystyrene units, a block copolymer consisting essentially of butadiene styrene and having terminal polystyrene units, an olefin elastomer of the ethylene propylene type, and butyl rubber (polybutadiene isoprene).

The above material is particularly desirable for manufacturing medical liquid containers such as autoclavable, flexible, collapsible, intravenous solution containers.

As compared to the Prior Art, the present inventive process is not geared towards producing different medical products, which in most cases, require clean room facility. SUMMARY OF INVENTION

It is the objective of the invention to offer the consumers with options and choices of products which offers good protection as well as having good aesthetic appearance. This invention therefore relates to the appearance and method of manufacture of rubber and/or thermoplastic elastomers casings and covers for but not limited to electronic, electrical and other gadgets.

Synthetic rubber and/or thermoplastic elastomers are rarely useful in themselves and are mostly often modified or compounded with additives, including colour pigments and glittering materials, in the manufacturing of the end products.

While synthetic rubber/or and thermoplastic elastomers end products are conventionally mostly opaque in nature, that is they do not produce clear and transparent end products, this invention seeks to explore the possibility and invent ways of making it to be clearer and transparent or semi-transparent.

The appearance of the end products can be further enhanced with touches of glittering and fluorescent materials added to the preparation for visual aesthetic appeal.

Fragrances, such as of fruits and flowers, may also be added to the synthetic rubber and/or thermoplastic elastomers preparations to add further appeal to the consumers for the end products.

Addition of disinfectant or germicide during the manufacturing process is another possibility that is explored. This will keep the end product to be almost germ free.

In order to make the synthetic rubber and/or the thermoplastic elastomers clear and transparent, one of the processes that can be done is to get their mold polished to mirror finish. This is subsequently followed by application of bright hard chrome on the polished surface to make it more lasting during processing procedure.

The selection of the raw materials for the synthetic rubber and/or thermoplastic elastomers material also make significant contribution to the final product being clear and transparent.

As a prerequisite, a suitable grade of rubber with high clarity type must be selected as well so that it can couple with mirror finish polished and hard chrome mold during processing to make the final product, which is clear and transparent.

DISCLOSURE OF INVENTION

More often than not, synthetic rubber and/or thermoplastic elastomers do not produce end products which are relatively clear and transparent, in that it is opaque in nature and will make the features of the electrical and electronic gadgets harder to see. These can sometimes be not practical and not aesthetically appealing for the user of the gadgets, particularly the younger generation.

It is therefore the main object of this invention to produce and manufacture synthetic rubber and/or thermoplastic elastomers casings and covers to provide the clarity of plastic material, with the possibility of adding further additives to enhance the aesthetic appeal.

However, the invention is not in any way limited to the use of synthetic rubber and/or thermoplastic elastomers as a raw material used in the production. Among others, it also will take into consideration the use of Thermoplastic Polyurethane Elastomer material and Polyvinyl Chloride material in the production. Further while an embodiment of the inventions have been given herein, other embodiments are also possible.

BEST MODES FOR CARRYING OUT THE INVENTION

It is the main object of the invention to manufacture synthetic rubber and/or thermoplastic elastomers covers and casings for, but not limited to, electrical, electronic and other gadgets to be as clear and as transparent as end products that are made of plastic. Emphasis is also put on selection of the raw materials.

The selection of rubber as raw material, for example, is critical as some lower grade rubber material will degrade and deteriorate at a faster rate and turn yellowish or that the colour added therein will fade over a short span of time, and therefore not having a long lasting effect.

The clear rubber or thermoplastic elastomers products can also come in a wide range of colours. This can be achieved by the addition and compounding of the desired colour pigments. Hence, in addition to being clear and transparent, the end products are not only clear and transparent but also come in the form of a variety of attractive colours as desired.

In order to achieve the objective, firstly, the method of manufacture involves the careful selection of a good grade rubber or thermoplastic elastomers raw material to achieve the clarity and the transparency of the final product. Subsequently, the desired colour pigment is blended together with the raw material using mills or blender. This is dependent on the type of material used. Various colour pigments can also be blended together to form unique colour combination. After the silicone rubber and/or thermoplastic elastomers raw material is compounded to the desired colour selection, it is then placed onto the processing machine to mold out to the final casing product. This is done either through the process of compression, transfer or injection molding with the use of a highly polished and hard chrome mold in order to achieve the high clarity and transparency effect.

It has been observed that when colour pigments are added to silicone rubber, the clarity will, to a minor extent, be affected by the density of the colour pigment added. The final outlook, however, will still be almost transparent and glossy comparing it to a normal rubber product produced by using normal mold and normal raw materials.

It is to be noted however that the use of high clarity grade of silicone rubber compound with high polished and hard chrome mold may sometimes only achieve about 90% of clarity in comparison to clear plastic covers and casings.

In addition to being almost clear, transparent and colourful, the visual aesthetic appeal of the silicone rubber and/or thermoplastic elastomers covers and casings can be further enhanced by the addition of other additives such as the fluorescent and the glittering compounds.

After the rubber or thermoplastic elastomers material has been compounded to the desired colour and/or fluorescent or glittering effect, it is then placed onto the processing machine to mold out to the final casing product either by compression, transfer or injection molding with the use of a highly polished and hard chrome mold in order to achieve the highly clear effect with colour and fluorescent/glittering effect. In relation to glitters, it is noted that the same can actually come in two forms - scatter glitters and concentrates. Scatter glitters can come in many shapes, for example star and heart shapes. It can come in numerous sizes and colours as well and the base materials that used to make the glitters can be made of paper, polyester, polycarbonate. Most of the mentioned base material can be blended with rubber and/or thermoplastic materials in order to get the final glittering effect. Glitters in the form of concentrates are easier to blend in.

It is however noted that if the glitters are to be blended in high percentage in relation to other manufacturing compound such as silicone rubber and/or thermoplastic raw materials, the final product will not be completely transparent anymore because the transparency can be blocked off by the amount of glitters added. The end product, however, will exude a glossy result. It is recommended that for the best result, the proportion to use would be 2 gm - 4 gm of glitters to 200 gm of silicone.

It has been noted that while the glittering effect product can also be produced out of plastic injection or directly spraying the glitter onto the plastic surface, there are limitations to the process.

Mixing glitters directly into plastic pallet and then injected out as plastic part with glittering effect can be achieved but the concentration of glitter on the plastic part is limited and usually scattered quite a distance apart because the manufacturer cannot really add in too much glitter into the raw plastic by ratio as the base material which is the plastic has to be rather concentrated as well during the plastic injection process.

The glittering effect can also be achieved by blending the glitters with paint or special grade of glue or epoxy. The ratio of glitter to be added can be relatively higher and the final result of the glitter can be appearing more concentrated as compared to the above mentioned method. However, the limitation of using such process in achieving the glittering effect will be not so lasting especially when the final product needs to undergo certain abrasion cycle during the actual application, the glitters can be dislodged easily as it is being coated on the plastic product by spraying process.

As another added feature, fragrance can also be added. To produce and manufacture silicon-rubber covers and casings that are clear, coloured and with fragrance, firstly, clear raw rubber or thermoplastic material are selected, Should a colour be required, the colour pigment is then blended together with the selected fragrance and the raw rubber or thermoplastic material using mills or blender depending on the type of rubber material or thermoplastic used and the parameter setting.

After the silicone rubber and/or thermoplastic material is compounded to the desired colour and fragrance, it is then place onto the processing machine to mold out to the final casing product either by compression, transfer or injection molding with the use of a highly polished and hard chrome mold in order to achieve the highly clarity effect with colour and fragrance.

One of the objects of the invention is not just the addition of fragrance, but how long it can hold the fragrance. This can be done either by blending the fragrance with the silicone rubber or thermoplastic raw materials in a form of powder or oil.

Alternatively, in order to add fragrance, the entire product can be dipped into the fragrance solution as well and leave it to dry on open air or using the heat of an oven. However, this process does not produce a lasting effect of the fragrance. The invention also explores the addition of disinfecting formulations or germicides to the silicone rubber and/or thermoplastic material.

There are other some suitable ways of achieving the intended objective, which is further described hereunder : -

Transfer or compression/injection rubber molding whereby the raw materials are compounded and cut into strip form and these materials are either placed onto the mold for processing or by auto feeding using the machine attached raw material feeding mechanism.

Liquid injection method whereby the raw material is a pre-compounded type and it takes the form of a paste or drum. This is a high end processing method.

TPE or TPU injection method, wherein the raw materials can be processed using a plastic injection machine and the raw materials are in pallet form and pre-formulated by the raw material suppliers.

Taking into consideration of silicone material as the main processing material, the operating temperature would range from 140 deg C to 190 deg C. Operating it above the temperature of 190 deg C will not have full impact as the colour will to go off, affecting the appearance of the final product. The curing time setting generally follows the curing cycle time of 1 to 5 minutes and usually the ratio between silicone and additives, for example catalyst, colour pigment, fragrances or glitters will very much depend on the size and mass of the final product.

As for catalyst, generally, it would be 1 kg of silicone with 3% of catalyst which is around 3Og.

The adjustment of curing temperature and cycle time is very much dependent on the size of the rubber composition, the amount of catalyst added and type of silicone used.

Claims

ClaimsWhat is claimed is:

1. A method of preparing synthetic rubber and/or thermoplastic elastomers that result in the clarification of the final physical appearance of synthetic rubber and/or thermoplastic elastomers products, making it clearer and more transparent, said method comprising:

the careful selection of a good grade silicon rubber or thermoplastic elastomers raw materials; the blending of the additives, if desired, with the raw material using mills or blenders; the placing of the mixture onto the processing machine to mold out to the final casing product, which is done either through the process of compression, transfer or injection molding with the use of a highly polished and hard chrome mold in order to achieve the high clarity and transparency effect; the curing of the mixture at an operating temperature ranging from 140 deg C to 190 deg C, wherein the curing time setting generally follows the curing cycle time of 1 to 5 minutes; the curing cycle of 1 to 5 minutes usually dependent on the ratio between the silicone and the additives;

2. A method of preparing synthetic rubber and/or thermoplastic elastomers in Claim 1 wherein the additives include catalysts, colour pigment, fragrances or glitters, disinfectants and germicides.

3. A method of preparing synthetic rubber and/or thermoplastic elastomers in Claim 2 wherein the catalyst used would be 2.5% - 5% of silicone used.

4. A method of preparing synthetic rubber and/or thermoplastic elastomers in Claim 2 wherein glitter, in the scatter form and/or concentrates can be added for the glittering effect.

5. A method of preparing synthetic rubber and/or thermoplastic elastomers in Claim 4 wherein the proportion of glitter added would be 2 gm - 4 gm of glitter to 200 gm of silicone.

6. A method of preparing synthetic rubber and/or thermoplastic elastomers in Claim 1 or 2 wherein fragrance to be added, is in the form of powder or oil mixture which are blended with the mixture.

7. A method of preparing synthetic rubber and/or thermoplastic elastomers in Claim 1 or 2 wherein disinfectant to be added, is in the form of powder or liquid which is blended with the solution.

8. A method of preparing synthetic rubber and/or thermoplastic elastomers in Claim 1 or 2 wherein a germicide to be added, is in the form of powder or liquid which is blended with the solution.