JP2010201355A - Method for removing contamination from plastic surface - Google Patents

Abstract

【Task】
For plastic products whose transparency and luster have been damaged by contaminants such as scale and dust adhering to the plastic surface, chemical substances in the atmosphere, and plastic degradation products, remove the contaminants without damaging the plastic. Provide a method to restore transparency and gloss.
[Solution]
Using a friction material, which is a rubber-like elastic material composed of a flexible composition containing a polymer and a plasticizer, the surface of the plastic is rubbed to remove contaminants, and then the plastic is washed with a detergent containing a surfactant. Or the remaining deposits are removed by rubbing with a cloth.
[Selection figure] None

Description

  The present invention relates to a method for removing contaminants adhering to a plastic surface. More specifically, for plastic products whose transparency and luster have been lost due to dirt and dust adhering to the plastic surface, chemical substances in the atmosphere, and substances caused by deterioration of the plastic. The present invention relates to a method for removing these contaminants from the plastic surface without damaging the plastic and restoring the original transparency and gloss.

  Plastic products used in automobile headlamps, etc., are exposed to wind and rain after many years of use, and water and dirt, chemical substances in the atmosphere, substances generated by plastic deterioration, etc. adhere to the surface. Transparency and gloss may be impaired. In order to restore transparency and gloss, it is common to wipe with a sponge or cloth, or wash with a cleaning agent, but it is extremely difficult to remove scales adhered to the plastic surface.

  There are also methods using cleaning agents containing abrasives, soil removing clay, etc., but these methods often damage the plastic surface or scrape the hard coat layer on the surface. As a result, there is a problem that the weather resistance of the plastic is lost and deterioration is promoted, discoloration and haze increase, and transparency and gloss are easily impaired.

  Therefore, it is desirable to develop a method that removes contaminants such as water and dust attached to the plastic surface, chemical substances in the atmosphere, and deteriorated plastic materials without damaging the plastic surface, and restores the original transparency and gloss. ing. The present invention seeks to provide means for satisfying such a need.

  The present inventors have found that the above-mentioned contaminants on the plastic surface are removed from the plastic surface when rubbed with a soft friction material composed of a polymer and a plasticizer, and the plastic recovers its transparency and gloss. . This is considered to be due to the abrasion pieces detached from the friction material being removed from the plastic surface including contaminants, as in the case of the eraser.

However, even with this method, the transparency and gloss restored can sometimes be less than the original transparency and gloss of plastic. It has also been found that plastics that have been restored to their transparency and gloss by this method lose their transparency and gloss again in a short time. As a result of searching for these causes, the present inventor has found that the wear piece and the plasticizer of the friction material remain on the plastic surface. These not only impair transparency and gloss, but also react with plastic to deteriorate transparency and gloss in a short time. After removing the contaminants with the friction material, cleaning with a cleaning agent, or wiping with a cloth to remove the wear pieces and plasticizer, the plastic will recover its original transparency and gloss, and it will remain for a long time. Can be maintained.

Since the present invention is achieved based on such knowledge, according to the present invention, a friction material made of a flexible composition composed of a polymer and a plasticizer is used to rub a plastic having contaminants on its surface. , A part of the friction material is detached as a wear piece, and the contaminant is included in the wear piece to be detached from the plastic, and then the plasticizer is transferred from the wear piece and the friction material remaining on the surface from the plastic. Etc. can be easily removed by washing with a cleaning agent or rubbing with a cloth to remove contaminants adhering to the plastic surface.

  According to the method of the present invention, contaminants such as scale on the plastic surface can be removed without damaging the plastic, and the original transparency and gloss can be easily recovered.

Plastic products to be subjected to contaminant removal The present invention can be widely applied to ordinary plastic products. Specifically, thermoplastic resins such as vinyl chloride resin, acrylic resin, styrene resin, polyethylene, polypropylene, polyamide resin, polycarbonate resin, acetal resin, polyester resin, polyphenylene ether resin, phenol resin, urea resin, melamine resin, alkyd Examples include products made of thermosetting resins such as resins, unsaturated polyester resins, silicon resins, polyurethane resins, and epoxy resins. Moreover, the product which consists of what is called a plastic alloy which consists of these plastics is also mentioned. Furthermore, the present invention can also be applied to products whose surfaces are subjected to surface treatment such as hard coat, painting, coating, top coat and the like.

Among these, it is preferable to apply to products made of a thermoplastic resin, particularly products that require transparency and gloss. For example, a polycarbonate automobile headlamp that has been exposed to wind and rain to which contaminants have adhered and its transparency has been lowered can easily recover its original transparency by the method of the present invention.

Friction material The friction material used in the present invention comprises a rubber-like elastic body which is a flexible composition in which a plasticizer is kneaded with a polymer. A typical example is a so-called eraser in which a polyvinyl chloride resin is blended with a phthalate ester plasticizer. In addition, rubbers such as raw rubber and styrene-butadiene copolymer may be blended with a softener or a plasticizer. Some erasers contain an abrasive or the like. However, the friction material used in the present invention does not usually contain an abrasive or the like because the surface is easily damaged when the plastic is rubbed with such an eraser.

The hardness of the friction material is preferably 10 to 80 according to JIS K-6253. If the hardness is too high, the plastic surface may be damaged when rubbed. Moreover, since it is difficult to produce wear pieces, removal of contaminants does not easily proceed. On the other hand, if the hardness is too low, the generation of the wear pieces is easy, but the wear pieces tend to adhere to the plastic surface, which is not preferable. The hardness of the friction material is more preferably 15 to 35 according to JIS K-6253.

  When the friction material is rubbed against the plastic surface, dirt and other contaminants are removed. The friction material absorbs these contaminants and separates them from the surface. This is thought to be due to the wear pieces becoming detached from the friction material. That is, on the one hand, the contaminants on the plastic surface are included in the wear pieces and removed from the surface, and on the other hand, the wear pieces are detached from the surface of the friction material, so that a new surface is always exposed and adsorbs the contaminants. . When the plastic on which the contaminant is adhered is rubbed with the friction material, this adsorption-desorption is repeated, and the contaminant is removed.

  The pressure (pressing force) when rubbing the plastic surface with the friction material to remove the contaminants on the surface may damage the plastic if it is too strong, and if it is too weak, the wear pieces will not be generated well and the contaminant will be removed. Since it does not proceed well, it may be set as appropriate depending on the state of adhesion of the friction material and contaminants to be used. Usually, it may be rubbed at a pressure of about 0.05 to 7.5 MPa. It is preferable to rub at a pressure of about 0.1 to 2.5 MPa, particularly about 0.25 to 0.75 MPa. The friction may be manual or a mechanical device may be used.

The measuring method of the pressing force is that the molded product is placed on the weighing scale, the weight change when the friction material is pressed is read, and the value obtained by dividing the weight change amount by the contact area of the friction material is defined as the pressing force. .

The plastic surface that has been rubbed with a cleaning agent friction material to remove contaminants is attached with plasticizer that has migrated from the friction material, and wear pieces remain, so it is necessary to remove them. . If these deposits remain, the plastic that has recovered its transparency and gloss will lose its transparency and gloss again in a short time. One method for removing these deposits is to wash the plastic with a cleaning solution containing a surfactant. As a result, the deposits are wrapped in the surfactant from the plastic surface and migrate into the cleaning liquid.

As the surfactant, any surfactant that has an affinity for the polymer or plasticizer that is a component of the friction material may be used. Usually, a detergent for household washing or kitchen may be used. When these surfactants are dissolved in water to an appropriate concentration and impregnated into a sponge or fabric and the plastic is rubbed, the plastic material and other deposits on the plastic surface are easily removed, and the plastic has an original transparency. And restore gloss. Wash with water after using the cleaning agent to completely remove the cleaning agent.

As another simple method for removing the fabric deposits, there is a method of removing the deposits by wiping the plastic surface with a fabric. As the fabric, it is preferable to use a fabric made of fine fibers so that the adhered matter can be removed well. For example, a cloth made of polyester fiber having a diameter of 1 to 5 μm, preferably 1 to 3 μm is used. When a fabric made of such fine fibers is used, plasticizers and other deposits on the plastic surface enter the gaps between the fibers due to capillary force or the like, and are thus removed from the plastic surface.

  In addition, when washing | cleaning with a washing | cleaning agent or wiping with a cloth does not fully remove deposits, both methods may be used in combination. For example, after washing with a cleaning agent, the deposits can be removed more completely by wiping with a cloth.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.
<Preparation of test piece>
50 mm x 90 mm x 2.0 mm resin by injection molding from polycarbonate resin (Mitsubishi Engineering Plastics Co., Ltd./trade name Iupilon (registered trademark) ML-300 blue transparent color, red transparent color, yellow transparent color) A plate was formed.
This resin plate was subjected to a weather resistance acceleration test using a sunshine weatherometer, and was treated for 2000 hours under the conditions of a black panel temperature of 63 ° C. and intermittent spray (ion-exchanged water sprayed for 12 minutes / 60 minutes). As a result of the accelerated weather resistance test, scales and surface degradation products adhered to the surface of the test piece, and the appearance, haze change rate, and color difference changed as follows.
Appearance Haze change rate (%) Color difference blue type transparent color test piece; Surface is cloudy 23.7 15.8
Red transparent color test piece; surface is cloudy 27.3 14.9
Yellowish transparent color test piece; surface is cloudy 35.2 17.3

In the present specification, the appearance, haze change rate, and color difference are as follows.
Appearance: Visually.
Rate of change in haze; haze of a molded product is measured by a measurement method in accordance with JIS K-7136 “How to determine haze of a plastic-transparent material”, and an untreated molded product and each washed treated product after a weather resistance acceleration test The amount of change in haze was defined as the haze change rate.
Color difference: The color difference was measured by a measuring method in accordance with JIS K-7105 “Testing method for optical properties of plastic”, and the color difference between the untreated molded product and each washed-treated molded product after the weather resistance acceleration test was determined.

<Friction with friction material>
The surface of the test piece was rubbed with a plastic eraser “MONO (trade name) PE-01A” made by dragonfly pencil.

<Cleaning with cleaning agent>
Mama Lemon (trade name) manufactured by Lion Co., Ltd. was soaked in a commercially available polyurethane sponge, and the surface of the test piece was cleaned using a foam which was sufficiently foamed with ion-exchanged water.

<Friction due to fabric>
The test piece was rubbed using “Toraysee (trade name)” of a cleaning cloth manufactured by Toray Industries, Inc.

Examples 1-3
The test piece was first rubbed with a friction material at a pressing force of 0.25 to 0.75 MPa, and then washed with a cleaning agent. The results are shown in Table 1.

Examples 4-6
The test piece was first rubbed with a friction material at a pressing force of 0.25 to 0.75 MPa, and then rubbed with a fabric after drying. The results are shown in Table 1.

Examples 7-9
The test piece was first rubbed with a friction material at a pressing force of 0.25 to 0.75 MPa, then washed with a cleaning agent, and further dried and rubbed with a fabric. The results are shown in Table 2.

Comparative Examples 1-3
The test piece was washed with a cleaning agent. The results are shown in Table 3.

Comparative Examples 4-6
The specimen was rubbed with a fabric. The results are shown in Table 3.

Reference Examples 7-9
The test piece was rubbed with a friction material at a pressing force of 12.5 MPa or more, and then washed with a cleaning agent. The results are shown in Table 4.

  As is clear from comparison with Tables 1 to 3, according to the method of the present invention, contaminants such as scale on the plastic surface can be almost completely removed.

Claims (9)

Using a friction material, which is a rubber-like elastic material composed of a flexible composition containing a polymer and a plasticizer, rubbing a plastic product with contaminants on the surface, and using a portion of the friction material as a wear piece A first step of removing and removing contaminants from the plastic product by removing them from the plastic product, and cleaning the plastic product that has undergone the process with a cleaning solution containing a surfactant. A method for removing contaminants from the surface of a plastic product, comprising a second step of removing the kimono. Using a friction material, which is a rubber-like elastic material composed of a flexible composition containing a polymer and a plasticizer, rubbing a plastic product with contaminants on the surface, and using a portion of the friction material as a wear piece A first step of removing the contaminants from the plastic product by removing them from the plastic product while removing the contaminants, and a second step of removing the remaining deposits by rubbing the plastic product after the step with a cloth. A method for removing contaminants from the surface of a plastic product, comprising the steps of: Using a friction material, which is a rubber-like elastic material composed of a flexible composition containing a polymer and a plasticizer, rubbing a plastic product with contaminants on the surface, and using a portion of the friction material as a wear piece The first step of removing and removing the contaminant from the plastic product by removing it from the plastic product, and the residual plastic product after the first step washed with a cleaning solution containing a surfactant. Contaminants from the surface of the plastic product comprising a second step of removing the kimono and a third step of rubbing the plastic product that has undergone the second step with a cloth to remove the remaining deposits. Removal method. 4. The method for removing contaminants from the surface of a plastic product according to claim 1, wherein the friction material is a rubber-like elastic body made of a polyvinyl chloride resin and a plasticizer. The friction material is a rubber-like elastic body made of a polyvinyl chloride resin and a plasticizer, and has a hardness of 10 to 80 according to JIS K-6253. A method for removing contaminants from the surface of plastic products. The method for removing contaminants from the surface of a plastic product according to any one of claims 2 to 5, wherein the fabric comprises fibers having a diameter of 1 to 5 µm. The method for removing contaminants from the surface of a plastic product according to any one of claims 1 to 6, wherein the pressing force of the rubber-like elastic body to the plastic product is 0.05 to 0.75 MPa. The method for removing contaminants from the surface of a plastic product according to any one of claims 1 to 7, wherein the plastic is a thermoplastic resin. The method for removing contaminants from the surface of a plastic product according to claim 8, wherein the thermoplastic resin is a polycarbonate resin.