JP2962917B2 - How to repair scratches on transparent plastic windshield parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION The present invention is to shield the scratch windshield parts made of a transparent plastic such as goggles helmet recover good transparency to the repair method of scratching the transparency is maintained well .

[0002]

Technical background of the invention and its problems Transparent plastic parts such as windshield parts such as goggles and shields for helmets and ski goggles are required to have good transparency to ensure a safe field of view. Since it is made of plastic, scratches are likely to occur when used outdoors, and there is a problem that transparency is reduced and a good visual field is hardly obtained. For this reason, a method is known in which a protective coating is formed on the surface of a transparent plastic part to improve the surface hardness so that it is less likely to be scratched beforehand (JP-A-51-2736, JP-A-54-87736). JP-A-55-94971, JP-A-62-169832, JP-A-2-150431 and JP-A-3-192175). However, in the case of repairing already scratched transparent plastic parts,
Restoration of abrasion shielding property and transparency is more important than improvement of surface hardness. In addition, surface treatment for improving surface hardness before scratching is applied to plastic parts before being assembled into products, and coating such as dipping and treatment such as heat curing are possible, so this Although such a method can be applied, it is difficult to apply such a method in the case of repairing abrasion of a plastic part which has been commercialized in combination with another part having low heat resistance and solvent resistance. As described above, in the case of repairing a scratch on a transparent plastic part, it is necessary to recover the shielding property and the transparency of the scratch, and it is desirable that the scratch can be treated by a simple method at room temperature. Further, as a treating agent for improving the surface hardness, a treating agent containing a silicone resin as a main component is known. However, since these treating agents generally contain colloidal silica, storage stability is low, and there is a problem in handling. there were. Further, it is known that abrasions of glass bottles such as beer bottles are shielded by surface treatment to restore the surface gloss, and are repeatedly used (Japanese Patent Application Laid-Open Nos. 55-56040 and 56-23444; Kaisho
61-6152, JP-A-63-117932). In this case, the surface-treated glass bottle is used after the protective film is removed with a detergent such as an aqueous alkali solution after use, and the surface is treated again. Therefore, in this method, there is a problem that the plastic is generally corroded by a cleaning agent such as an aqueous alkali solution and the transparency is impaired, and it has not been applied to goggles, shields and the like which require transparency.

As described above, when abrasion of a transparent plastic part such as a shield is repaired by a protective coating,
The following characteristics are required. Good protection against abrasions, good transparency of the protective coating, easy to apply, can be processed at room temperature, high strength of the protective coating, good adhesion of the protective coating, and good water resistance. The surface of the coating has no stickiness.The repaired transparent plastic parts are hard to fogg.Here, the repaired plastic parts are required to be resistant to scratches under the condition of re-use. Is required. In addition, helmet goggles and shields are used outdoors and are exposed to the wind and rain, so it is necessary to have good adhesion and water resistance of the coating, and to improve handling feel and reduce the adhesion of dust etc. It is necessary that there is no stickiness on the surface. Further, helmet goggles and shields, ski goggles, and the like are liable to cause a decrease in the visual field due to fogging due to water vapor or the like. Therefore, it is preferable that the occurrence of fogging be suppressed by repair. A method of repairing a plastic part satisfying all of these requirements has not been known until now.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for repairing abrasion of a transparent plastic part, which has good shielding properties for abrasion, good transparency recovery, and can be easily repaired.

[0005]

The present inventors have conducted intensive studies on a method for repairing scratches on plastic parts. As a result, the present invention contains a curable polyorganosiloxane having a hydroxyl group or a hydrolyzable group and a volatile polydimethylsiloxane. The present inventors have found that abrasion can be satisfactorily repaired by applying the composition, and the present invention has been accomplished. That is, the present invention relates to (A) a compound represented by the general formula: R _a SiX _b O _{(4- (a + b)) / 2} (wherein R represents a monovalent organic group or a hydrogen atom ;
90% by mole or more of the methyl groups, and 0.1% of R 1.
5 to 5 mol% is a hydrophilic group. X represents a hydroxyl group or a hydrolyzable group, and a and b are numbers having the following relationship. 0.8 <a <2 0.3 ≤b <2) 100 parts by weight of a curable polyorganosiloxane represented by the following formula and (B) 100 to 1000 parts by weight of a volatile polydimethylsiloxane represented by the general formula (I) or (II).

[0006]

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Having a viscosity at 25 ° C. of 10 to 100,00
0 centistokes compositions, transparent plastic
This is a method of repairing the scratches by applying and curing the scratches on the windshield part .

The curable polyorganosiloxane of the component (A) used in the present invention has a hydroxyl group or a hydrolyzable group, and has a general formula of _Ra SiX _b O _{(4- (a + b)) / 2} It is shown by. Here, R is a monovalent organic group (however, an aryl group
) Or a hydrogen atom. Examples of the monovalent organic group include an alkyl group such as methyl, ethyl, propyl, butyl, and hexyl; an alkenyl group such as vinyl and allyl; an aralkyl group such as phenethyl and β-phenylpropyl;
epoxy group-containing groups such as γ-glycidoxypropyl, 3,4-epoxycyclohexylethyl, (meth) acryl group-containing groups such as γ-methacryloxypropyl, γ-
Mercaptoalkyl groups such as mercaptopropyl, cyanoalkyl groups such as cyanoethyl, chloroalkyl groups such as β-chloroethyl and γ-chloropropyl, 3,
Examples thereof include a fluoroalkyl group such as 3,3-trifluoropropyl. Among these, an alkyl group is preferable, and a methyl group is particularly preferable, since the transparency of the plastic part after repair is good. In addition, it is necessary that 90 mol% or more of R is a methyl group because it has good compatibility with the volatile polymethylsiloxane of the component (B), can form a smooth protective film, and has excellent abrasion shielding properties. It is.
In addition, since the adhesion and water resistance of the protective coating are improved,
It may contain an epoxy group-containing group or a (meth) acryl group-containing group, and preferably contains 0.05 to 10 mol% of R 3. In addition, since the repaired plastic parts are less likely to fog, they contain a hydrophilic group as R.
It is necessary. As the hydrophilic group, R'O (C ₂ H ₄ O) d (C ₃ H ₆
O) e- (where R 'is the same group as R, d and e are integers), a polyoxyalkylene group, γ-aminopropyl group,
Aminoalkyl groups such as N- (β-aminoethyl) -γ-aminopropyl group, carboxyalkyl groups such as γ-carboxypropyl group, HOC ₃ H ₆ —, HOCH ₂ (CHOH) fC ₃
Examples thereof include a hydroxyalkyl group such as H _6- (where f is an integer). As the hydrophilic group, a polyoxyalkylene group and an aminoalkyl group are preferable, and a polyoxyalkylene group is particularly preferable. Hydrophilic group Chi sac R 0. 5 to 5
Preferably it is mol%. X of the component (A) represents a hydroxyl group or a hydrolyzable group. As the hydrolyzable group, an alkoxyl group, an acyloxy group, an aminoxy group,
Examples include a ketoxime group, an amide group, an alkenyloxy group, and a halogen atom. A hydroxyl group or an alkoxyl group is preferable, and a hydroxyl group, a methoxy group, or an ethoxy group is particularly preferable, since a by-product generated during the curing reaction has a low odor and has good curability and film properties. Also, a and b must be numbers having the following relationship. If 0.8 <a <20.3 ≦ b <2a is 0.8 or less, the cured film becomes brittle, and if it is 2 or more, a good cured film cannot be obtained, and the film has slipperiness such that oil oozes out in the present invention. Not suitable for the purpose of
If b is less than 0.3, the curing speed is too slow to be practical.
Above, the cured film becomes brittle and is not suitable for the purpose of the present invention.
As the component (A), a liquid or a solid can be used as long as it can be dissolved and mixed with the component (B). The component (A) has a viscosity of preferably 10 centistokes or more, and a protective film to be formed is less sticky, has good penetration into abrasions, and has good shielding properties, since a good coating film with little repellency can be formed. For this reason, 100,000 centistokes or less is preferable. Such a polyorganosiloxane can be obtained by a known method, and is obtained by partially hydrolyzing a hydrolyzable organosilane such as an organoalkoxysilane or an organochlorosilane as a raw material.

The component (B) used in the present invention is a volatile polydimethylsiloxane represented by the general formula (I) or (II), and is an important component that characterizes the method of the present invention.

[0010]

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The volatile polydimethylsiloxane as described above is a linear polydimethylsiloxane having a degree of polymerization of 2 or more or a cyclic polydimethylsiloxane having a degree of polymerization of 3 or more, whose terminal is blocked with a trimethylsilyl group. Either linear or cyclic polymethylsiloxane or a mixture thereof is used in consideration of the solubility of the components. Among them, it is desirable to use a linear polydimethylsiloxane having a polymerization degree of 2 to 7 or a cyclic polydimethylsiloxane having a polymerization degree of 3 to 5;
It is preferred to use the cyclic polydimethylsiloxane. Here, "volatile" means having a vapor pressure that can be measured at room temperature, and the component (B) preferably has a boiling point of 99 to 260 ° C. The component (B) improves the coating properties of the composition of the present invention by diluting and dissolving the component (A). It penetrates well into the generating part and exhibits excellent smoothness, thereby enabling formation of a film having excellent shielding properties. The component (B) of the present invention does not corrode plastics such as ordinary organic solvents, does not undergo deformation due to swelling, etc., and enables a good recovery of transparency of transparent plastic parts. Another characteristic is that even after using a plastic part that has been repaired once, it can be repaired by directly applying it on it without removing the old protective coating, even if it is to be repaired again. It becomes possible. In general, when applying a treating agent using a normal organic solvent to a surface treated with silicone, a good coating film may not be obtained due to occurrence of repelling or swelling, but the component (B) of the present invention The use makes it possible to easily perform repeated repairs without removing old protective coatings. (B) The amount of component
(A) 100 to 1,000 parts by weight based on 100 parts by weight of the component. Less than 100 parts by weight is applied to plastic parts
(A) The amount of the component is increased, and the smoothness and hardening / drying property of the coating surface are deteriorated, which may cause the skin of the citron and the stickiness of the surface. On the other hand, when the amount exceeds 1,000 parts by weight, the amount of the component (A) applied to the plastic part is insufficient, and it is difficult to obtain a sufficient shielding effect.

[0012] In addition, 6 to
Mixing and using a hydrocarbon having 16 carbon atoms, alcohol, or the like may be used. In particular, it is effective to mix alcohol for improving the storage stability of the composition of the present invention. However, in consideration of the abrasion shielding property and the influence on the recovery of transparency, 5% by weight of the composition of the present invention is considered. % Is preferable. When the component (A) having a hydrophilic group is used, it is preferable to contain 1 to 5% by weight of alcohol in order to obtain good shielding properties.

The composition of the present invention comprises the above component (A) as component (B)
It is obtained by dissolving in components. The composition thus obtained has a viscosity at 25 ° C. in the range from 10 to 10,000 centistokes, particularly preferably in the range from 10 to 1,000 centistokes. If it is less than 10 centistokes, the amount of adhesion to plastic parts is small, so that a single treatment cannot provide a sufficient abrasion shielding effect.
If it exceeds 00 centistokes, the amount of adhesion increases and the film becomes thicker, which is not preferable because it causes inconveniences such as easy abrasion.

The compositions of the present invention generally incorporate a curing catalyst. Examples of the curing catalyst include organic amines such as triethanolamine; carboxylic acid metal salts such as iron octylate and zinc octylate; organic tin compounds such as tin dioctylate, dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin dioctoate; Examples thereof include titanates such as propyl titanate and tetrabutyl titanate, and quaternary ammonium salts such as organosilicon quaternary ammonium salts. From the viewpoint of curability and safety and health, dibutyltin dilaurate, dioctyltin dilaurate or tetrabutyl is preferred. Titanate is preferred. The amount of the curing catalyst is 0.01 to 7 parts by weight, preferably 0.02 to 5 parts by weight, based on 100 parts by weight of the component (A). 0.01 parts by weight or more is preferred from the viewpoint of the curing and drying speed of the coating, and 7 parts by weight or less is preferred from the storage stability of the composition. However, when R of the curable organopolysiloxane of the component (A) contains a substituent having a curing catalytic action such as an aminoalkyl group, it is not necessary to combine a curing catalyst.

As a method of applying to a plastic part having scratches, a commonly used method such as brush coating, spray coating, puff coating, dipping, flow coater, or transfer can be used. For example, a simple method of spray coating and then wiping off excess composition with gauze is also possible. A good coated surface is obtained by the self-smoothness of the composition of the present invention. In the repairing method of the present invention, heating is not particularly required, and a cured protective film can be obtained by leaving at room temperature for 0.5 to 5 hours. However, heating is performed within a range that does not cause deformation of parts due to shortening of the curing time. You can do it. In this case, the heating temperature is preferably set to 70 ° C. or less in order to obtain good shielding properties and transparency.

[0016]

The present invention will be described in more detail with reference to the following examples. All parts in the examples are parts by weight.

Synthesis Example 1 CH ₃ (OC ₂ H ₄ ) ₁₀ OCH ₂ CH = CH ₂ 513 in a flask equipped with a stirrer, heating jacket, reflux condenser and dropping funnel.
(1 mol) and 0.5 part of a solution of chloroplatinic acid in isopropanol (the amount of platinum was 2% by weight), and 230 parts (2 mol) of methyldichlorosilane were gradually added dropwise with stirring. After stirring at room temperature for 3 hours and further at 50 ° C. for 1 hour, the unreacted material is distilled off by heating under atmospheric pressure and further reduced pressure, and chlorosilane having a polyoxyalkylene group (CH ₃ (OC ₂ H ₄ ) ₁₀ OC _Three
H ₆ Si (CH ₃₎ to give Cl ₂₎ 625 parts of (S-1). Preparation Examples 1 to 4 The amounts of alkoxysilane, S-1 and acetic acid shown in Table 1 were charged into a flask equipped with a stirrer, a heating jacket, a reflux condenser, a moisture meter, and a dropping funnel.
Heat slowly with stirring. When the liquid temperature reached 80 ° C., the amount of water shown in Table 1 was gradually added dropwise. The hydrolysis and condensation reaction were carried out while maintaining the temperature at which the alcohol generated by the reaction was refluxed (about 78 to 83 ° C) for 4 hours. Then, heating and stirring were continued while removing the alcohol distilled off by the moisture quantifier. When the distillation of the alcohol stopped and the temperature of the reaction solution showed an increase, the heating was stopped, and the temperature was returned to room temperature to return the curable polyorganosiloxane (R). -1 to R- 4 ) were obtained. R
Table 1 summarizes the viscosities, organic group contents and other properties of -1 to R- 4 . The organic group content, the methyl group content, and the X content are all values obtained by calculation based on the blended amounts. Examples 1-2 and Comparative Examples 1-3 Coating agents were prepared with the composition shown in Table 2 , and the shielding properties, re-shielding properties, water resistance and anti-fogging properties were evaluated as follows.
Table 2 shows the results. [Preparation of test piece] A polycarbonate plate (10 cm ×
10 cm × 0.5 cm 2) was prepared and lightly rubbed with sandpaper to make abrasion. The above-mentioned coating agent was applied thereto using gauze, and allowed to stand in an environment of 25 ° C. and 50% RH for 3 hours to prepare a test piece. [Shielding Property] The appearance of the test piece was visually observed and evaluated according to the following four grades. ：: The abrasion part was well shielded and the transparency of the test piece was good. ○: The trace of the abrasion part was slightly observed, but the transparency of the test piece was good. Transparency is slightly good. ×: Insufficient shielding effect and poor transparency of test specimen. [Re-shielding property] The test specimen prepared above is further allowed to stand still at room temperature for one day, and then gently rubbed again with sandpaper for scratches. I attached. The coating agent was applied thereto and allowed to stand as described above, and the shielding property was evaluated in four steps as described above. [Water Resistance] The test piece was immersed in water at 20 ° C., left for 3 days, taken out and observed, and evaluated according to the following three grades. ：: No change from the state before immersion. ：: Shielding property decreased from ◎ to ○ or from ○ to ×. ×: Shielding property decreased from ◎, △ or △ to ×. [Anti-fogging property] After putting in refrigerator for 30 minutes, 25 ℃ ・ 60% RH
, And the coated surface was observed and evaluated according to the following four grades. ：: Almost no fogging ○: Slightly fogging occurs, but disappears immediately △: Slightly fogging X: Significantly fogging As shown in Table 2 , the coating agents of the method of the present invention were all Good results were shown for each property such as shielding property, re-shielding property, water resistance and anti-fogging property . On the other hand, (B) of the present invention
In Comparative Example 1 in which the amounts of the components were small, satisfactory results were not obtained in both the shielding property and the re-shielding property. Also hydrophilic
Comparative Example 2 using a polyorganosiloxane containing no group
In the case of ~ 3, the shielding properties etc. are excellent, but transparent plus
The most important property for abrasion repair of Chick draft shield parts
The antifogging property was inferior.

[0018]

[Table 1]

[0019]

[Table 2]

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ identification symbol FI C09J 183/04 C09J 183/04 (58) Field surveyed (Int.Cl. ⁶ , DB name) C08J 7/04 B29C 73/02 B05D 7 / 02,7 / 24 C09J 83/04 C08L 83/04

Claims (1)

(57) [Claims] (A) A compound represented by the general formula: R _a SiX _b O _{(4- (a + b)) / 2} (wherein R represents a monovalent organic group or a hydrogen atom ;
90% by mole or more of the methyl groups, and 0.1% of R 1.
5 to 5 mol% is a hydrophilic group. X represents a hydroxyl group or a hydrolyzable group, and a and b are numbers having the following relationship. 0.8 <a <2 0.3 ≤b <2) 100 parts by weight of a curable polyorganosiloxane represented by the following formula: (B) 100 to 1000 parts by weight of a volatile polydimethylsiloxane represented by the general formula (I) or (II) Formula 1 A method of repairing abrasion by applying a composition comprising a composition having a viscosity of 10 to 100,000 centistokes at 25 ° C. to the abrasion of a transparent plastic windshield part and curing the composition.