JPH083070B2 - Marking ink composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a marking ink composition, and in particular, a marking useful for marking a silicone rubber surface without gloss and without surface tackiness. Ing composition.

(Prior Art) Recently, it has been required to perform marking treatment of patterns, characters and the like on the surfaces of tubes made of silicone rubber material, covered electric wires, swimming caps, key tops of OA equipment, rubber contacts and the like. As a composition for performing such marking treatment, for example, a composition in which an organopolysiloxane and an organohydrogenpolysiloxane are blended at a predetermined ratio is known (Japanese Patent Publication No. 52-52).
-14642).

However, recently, including rubber contacts,
There is an increasing demand for molded products with a matt finish on the marking surface. The marking ink composition using silicone oil, resin, etc. as a base material, when cured,
Its surface has a luster (gloss) and is not suitable for the production of moldings with a matte surface. Also in the marking ink composition disclosed in Japanese Patent Publication No. 52-14642,
The marking surface (cured material surface) becomes glossy.

(Problems to be solved by the invention) At present, in order to eliminate the gloss of the marking surface, methods such as addition of inorganic fillers such as silica, diatomaceous earth and calcium carbonate, use of a large amount of solvent, polishing of the surface of the cured product, etc. are performed. It is being appreciated.

However, for example, the addition of the inorganic filler has a problem that the abrasion resistance of the marking ink is remarkably reduced and the coloring is inhibited by the added powder. When a larger amount of solvent is used, there is a problem of environmental pollution for removing the solvent, and when polishing the surface of the cured product, there is a problem of restriction due to the shape of the molded product.

Therefore, an object of the present invention is to provide a marking ink composition in which the above-mentioned problems are effectively solved, and particularly, a marking having excellent wear resistance and capable of effectively forming a dull marking on the surface of a molded article. .

(Means for Achieving the Object) The marking ink composition of the present invention comprises (1) (a) the following average composition [I], In the formula, R is a monovalent hydrocarbon group, a is a number of 1.98 to 2.01, and has at least two alkenyl groups in one molecule, and the viscosity at 25 ° C. is 300 cSt. 100 parts by weight of the above organopolysiloxane, (b) SiO ₂ unit, (R ¹ ) ₃ SiO _{1 ] 2} unit and (R ¹ ) ₂ (R ² ) SiO _{1 ] 2} unit (wherein R ¹ is alkyl And R ² is an alkenyl group), and (R ¹ ) ₃ SiO
_{1 ] 2} units and (R ¹ ) ₂ (R ² ) SiO _{1 ] 2} units are in the range of 0.6 to 1.2 mol per 1 mol of SiO ₂ units, and the alkenyl group content is 1 to ₂ mol. 10 to 20 parts by weight of organopolysiloxane which is 3% by weight, (c) the following average composition formula [II], In the formula, R ³ is a monovalent hydrocarbon group, b is a number of 10 to 2.1, c is a number of 0.5 to 1.0, and b + c = 1.5 to 2.6. An organohydrogenpolyether containing at least 3 SiH bonds in one molecule and having an amount of 3 mol or more of the above SiH bonds per 1 mol of the total amount of alkenyl groups in the components (a) and (b). Siloxane, (d) 50-150 parts by weight of spherical powder of polymethylsilsesquioxane having an average particle size of 50 μm or less, (e) a pigment, and (f) a catalytic amount of platinum or a platinum-based compound. It is a thing.

Component (a) The organopolysiloxane of component (a) is used as a base polymer in the present invention, and it has the above-mentioned average composition formula [I], that is, (In the formula, R and a are as described above).

In this average composition formula [I], a is a number of 1.98 to 2.01, and the monovalent hydrocarbon group R is, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a phenyl group, a tolyl group or the like. Aryl group, vinyl group, alkenyl group such as allyl group, cycloalkyl group such as cyclohexyl group, and a group in which a part or all of hydrogen atoms bonded to carbon atoms of these groups are substituted with a halogen atom, a cyano group, or the like, For example, chloromethyl group, trifluoropropyl group,
A cyanoethyl group etc. can be illustrated. Among these groups, those having 1 to 10 carbon atoms are preferable.

Further, this organopolysiloxane needs to have at least two alkenyl groups in one molecule, which makes it possible to crosslink to form a cured product. A vinyl group is particularly preferable as the alkenyl group. Further, the alkenyl group may be present at the terminal of the molecular chain or in the middle thereof.

Further, this organopolysiloxane has a viscosity at 25 ° C of 300 cSt or more, particularly 300 to 10 from the viewpoint of workability.
It is in the range of 10,000 cSt.

In the present invention, specific examples of such an organopolysiloxane of the component (a) are not limited to these, but the following can be exemplified.

(In the formula, m, n, and p are positive integers and are numbers such that the viscosity is within the above range.) These organopolysiloxanes are of two types as long as the viscosity is within the above range. A combination of the above can also be used.

Component (b) In the present invention, the organopolysiloxane of component (b) is used to improve the adhesiveness and strength of the marking coating obtained from the composition of the present invention.

As described above, this organopolysiloxane has SiO ₂
Units, (R ¹ ) ₃ SiO _{1 ] 2} units and (R ¹ ) ₂ (R ² ) SiO _{1
] 2} units (in the formula, R ¹ is an alkyl group and R ² is an alkenyl group). Examples of the alkyl group R ¹ include a lower alkyl group having 10 or less carbon atoms such as a methyl group, an ethyl group and a propyl group, and a methyl group is preferable. Further, as the alkenyl group, a vinyl group,
An allyl group, a propenyl group, etc. can be mentioned, and a vinyl group is particularly preferable.

In the organopolysiloxane of the component (b), from the viewpoint of the adhesiveness and strength of the marking film,
The total amount of the (R ¹ ) ₃ SiO _{1 ] 2} unit and the (R ¹ ) ₂ (R ² ) SiO _{1 ] 2} unit is in the range of 0.6 to 1.2 mol with respect to 1 mol of the SiO ₂ unit, and is alkenyl. Group (the above R ¹ ) content is 1 to 3
It is necessary to be wt%.

The organopolysiloxane of component (b) is 10 parts by weight per 100 parts by weight of organopolysiloxane of component (a).
-20 parts by weight, especially 10-15 parts by weight. When the blending amount is 10 parts by weight or less, the adhesiveness and strength of the marking coating obtained from the composition of the present invention decrease, and
If it exceeds 20 parts by weight, the marking coating becomes inferior in flexibility and peeling easily occurs.

The above-mentioned organopolysiloxane of component (b) can be produced by a method known per se, for example, a method of cohydrolyzing silicon tetrachloride, trimethylchlorosilane and dimethylvinylchlorosilane, silica hydrosol and hexamethyldisiloxane. Alternatively, it can be easily produced by a method of mixing trimethylchlorosilane and dimethylvinylchlorosilane and performing cohydrolysis-cocondensation-equilibrium.

Component (c) In the present invention, the organohydrogenpolysiloxane used as the component (c) acts as a cross-linking agent, and the SiH group in the molecule is the component (a).
And (b) by addition reaction with the alkenyl group contained in the organopolysiloxane to form a rubber-elastic cured product.

This organohydrogenpolysiloxane has the above average composition formula [II], that is, In the formula, R ³ is a monovalent hydrocarbon group, b is a number of 1.0 to 2.1, c is a number of 0.5 to 1.0, and b + c = 1.5 to 2.6. To be done. Here, as the monovalent hydrocarbon group R ³ ,
Among the examples of R in the average composition formula [I], groups excluding alkenyl groups can be mentioned. Also
It is necessary that at least three SiH groups be present in the molecule in order to form a good crosslinked structure with the organopolysiloxane of the components (a) and (b).

Examples of such an organohydrogenpolysiloxane include siloxane units having a Si—H bond such as HSiO _{3 ] 2} , (CH ₃ ) SSiO, (CH ₃ ) ₂ HSiO _{1 ] 2} , and SiO ₂ , CH ₃ SiO _{3 ].
2} , (CH ₃ ) ₂ SiO, (CH ₃ ) (C ₆ H ₅ ) SiO, (CH ₃ ) ₃ SiO _{1 ] 2}
Examples of siloxane units include, but are not limited to, copolymers of methylhydrogenpolysiloxane and dimethylhydrogenpolysiloxane, methylhydrogenpolysiloxane and methyl. Copolymer with phenyl polysiloxane,
Copolymers of methylhydrogenpolysiloxane, dimethylpolysiloxane and methylphenylpolysiloxane are preferably used.

These organohydrogenpolysiloxanes are
They can be used alone or in combination of two or more, and the amount thereof is 3 SiH groups per 1 mol of the total amount of alkenyl groups in the components (a) and (b).
The amount is at least mol, preferably 3 to 20 mol. Thereby, a cured product having flexibility is formed.

Component (d) In the present invention, the cured product obtained from the composition of the present invention eliminates the gloss (gloss) of the surface and, at the same time, reduces the tackiness (tackiness) of the surface, and the cured product has abrasion resistance. In order to improve the adhesiveness with silicone rubber moldings, the average particle size is 50 μm or less, preferably 20 μm or less.
Spherical powders of polymethylsilsesquioxane having a size of μm or less are used. If the average particle size of the powder exceeds 50 μm, the mechanical strength of the marking coating (cured coating) obtained is impaired and, for example, the coating becomes inferior in abrasion resistance. Furthermore, powders with an extremely fine average particle diameter are difficult to manufacture, and no further effect can be obtained.
The average particle size of the powder is preferably 0.1 μm or more, particularly 0.2 μm or more. Further, the particle shape is preferably substantially spherical.

Most preferably used in the present invention is polymethylsilsesquioxane having a softening temperature of 150 ° C. or higher.
Thereby, the gloss of the cured film of the marking ink composition can be effectively erased, the stickiness of the surface can be reduced, the abrasion resistance can be significantly improved, and the adhesiveness with the silicone rubber molded product can be significantly improved. It becomes possible.

The above polymethylsilsesquioxane is, for example, methyltrialkoxysilane, orthoalkyl silicate or a partial hydrolyzate thereof hydrolyzed in an aqueous solution containing an alkaline earth metal hydroxide or an alkali metal carbonate, It is obtained by condensation or by hydrolysis and condensation in an aqueous solution of amine or ammonia (see JP-A-63-77940, JP-A-63-103812, and JP-A-63-295637). Further, the polymethylsilsesquioxane may contain an organic group such as a vinyl group, for example, JP-A-63-101857 and JP-A-02-1631.
The surface-modified polymethylsilsesquioxane disclosed in Japanese Patent No. 27, etc. can also be used.

Here, the spherical powder refers to spherical or substantially spherical particles each having an independent shape, and as a guide, particles having a difference between the lateral diameter and the longitudinal diameter of the particles within ± 40%.

In the present invention, the above-mentioned powder is blended in an amount of 50 to 150 parts by weight, particularly 50 to 100 parts by weight, per 100 parts by weight of the component (a) organopolysiloxane. If it is less than 50 parts by weight, the desired effect is not exhibited, and if it is blended in an amount of more than 150 parts by weight, the composition becomes hard and the workability deteriorates, and the mechanical properties of the obtained cured film are reduced. Strength is impaired, and the adhesive strength with the silicone rubber molded product is also reduced.

Component (e) Since the composition of the present invention is used for marking a molded article such as a silicone rubber, a pigment is an essential component, and the composition is colored variously. . The blending amount of this pigment is determined according to the desired coloring degree, hiding degree, and the like. Suitably 0 to 100 parts is desirable in terms of physical properties.

Examples of such pigments include inorganic pigments such as ultramarine, red iron oxide, titanium white, titanium yellow, carbon black, iron oxide, zinc white, chrome green, anthraquinone violet, anthraquinone blue, phthalocyanine blue, indanthrene blue, aliza. Examples thereof include organic pigments such as nin green, phthalocyanine green, and perison red, metal powder pigments such as aluminum powder, bronze powder, copper powder, tin powder, and phosphorescent pigments containing a zinc sulfide compound as a main component. These pigments are appropriately selected and used in consideration of the color tone, saturation and the like of the object.

Component (f) In the present invention, it is included in the above-mentioned component (c).
A curing catalyst is used to accelerate the addition curing reaction between the SiH group and the alkenyl group contained in the components (a) and (b). As this curing catalyst, platinum or a platinum compound known per se as this type of curing catalyst is used. Specific examples include platinum black, chloroplatinic acid, complexes of chloroplatinic acid with ethylene, olefins such as propylene, alcohol modified chloroplatinic acid disclosed in US Pat. No. 3,220,972, and the like. .

The amount of these catalysts used may be a so-called catalytic amount, and for example, in terms of platinum, it is used in an amount of about 10 ⁻³ to 10 ⁻⁶ mol per mol of the alkenyl group.

Other compounding agents In the composition of the present invention, a catalyst activator can be compounded, if necessary, within a range that does not impair the purpose such as matting of the cured film. Examples of the catalyst activator include benzotriazole, an alcohol derivative having a triple bond, and triphenyl phosphite.

Marking Ink Composition The marking ink composition of the present invention can be easily obtained by uniformly mixing the above-mentioned components using a kneader such as a mixer or a roll, in which case the components are blended. There is no particular restriction on the order of, but in general,
It is preferable to mix the organohydrogenpolysiloxane of component (c) or the curing catalyst of component (f) immediately before use.

In the actual use of this composition, for example, it is appropriately diluted with an organic solvent such as toluene, normal hexane, or methanol, if necessary, and the required amount of the curing catalyst (component (f)) is added. Then, the surface of the target tube, covered electric wire, key top of OA equipment, etc. may be marked in the form of a desired design, letters, etc., and then heat curing may be carried out. Heat curing is usually performed at a temperature of 100 to 250 ° C. for 30
It is performed for about 2 seconds to 2 hours.

(Examples) The present invention will be described in the following examples. In each example, "parts" means "parts by weight", and the viscosity is a value measured at 25 ° C.

Example 1 The following formula Dimethylpolysiloxane whose molecule ends are blocked with dimethylsilyl groups (viscosity: 5,000 cSt) 500 parts Dimethylsiloxane raw rubber with both ends blocked with dimethylsilyl groups and a vinyl group content of 0.15 mol% of the total number of organic groups (Viscosity: 5 million cSt) 10 parts SiO ₂ unit, (CH ₃ ) ₂ SiO _{1 ] 2} unit and (CH ₃ ) ₂ (C
H ₂ = CH) SiO _{1 ] 2} units, and (CH ₃ ) ₂ SiO _{1 ] 2} units and (CH ₃ ) ₂ (CH ₂ = CH) SiO ₁ per 1 mol of SiO ₂ units.
_] The total amount of ₂ units is 1 mol, and the vinyl group content is 2
% By weight polysiloxane 10 parts Spherical powder consisting of methylsilsesquisiloxane with a particle size of 0.3 μm 70 parts Bengal (black) 30 parts 2% by weight chloroplatinic acid (Pt conversion) 2-ethylhexanol solution 1 part Ethynylcyclohexanol 1.4 The mixture of parts is evenly blended using a triple roll,
Then, this was diluted with toluene to obtain a marking ink composition (Example 1).

Further, a marking ink composition was obtained in the same manner as described above except that the amount of the spherical powder compounded was 35 parts (Example 2).

Then, after the compositions obtained above were stored for the periods shown in Table 1, respectively, the following formula per 100 parts of these compositions: After evenly mixing 10 parts of the organohydrogenpolysiloxane shown in, vulcanized and cured silicone rubber plate
It was applied so as to have a thickness of 30 to 50 μm, and cured by heating at 200 ° C. for 300 seconds.

The cured film thus obtained was measured for glossiness, and evaluated for stickiness (tackiness) and abrasion resistance, and the results are shown in Table 1.

The glossiness was measured using a gloss meter IG-310 manufactured by Horiba, Ltd. under the conditions of an incident angle of 60 ° and a light receiving angle of 60 °. The abrasion was evaluated by repeatedly rubbing with a cotton cloth and the number of times of friction when the cured film was peeled off.

Comparative Examples 1 and 2 In Example 1, a cured film was formed in the same manner as in Example 1 without using the spherical methylsilsesquioxane powder, and the glossiness of the film was measured (comparison). Example 1).

Further, 70 parts of diatomaceous earth (average particle size 10 μm) was used in place of the spherical powder used in Example 1, a cured film was formed in the same manner as in Example 1, and the glossiness of the film was measured. (Comparative example 2).

 The results are shown in Table 1.

Examples 3 and 4 Instead of the spherical methylsilsesquioxane powder used in Example 1, methylvinylsilsesquioxane (average particle size 1.2 μm, vinyl group content 0.5 mol%) was added to 70%.
Parts (Example 3), and 35 parts (Example 4),
A cured film was formed in the same manner as in Example 1, and the glossiness of the film was measured.

 The results are shown in Table 2.

Comparative Example 3 Similar to Example 1 except that 70 parts by weight of iron oxide powder (average particle size 15 μm) having a normal surface shape was used in place of the spherical powder of methylsilsesquioxane in Example 1. A marking ink composition was obtained. Then, in the same manner as in Example 1, a cured film was formed, and the glossiness of the film was measured.

The results are shown in Table 4.

Comparative Example 4 Example 1 was repeated except that 70 parts by weight of aluminum silicate powder (average particle diameter 12 μm) having a normal surface shape was used in place of the spherical methylsilsesquioxane powder in Example 1. A marking ink composition was obtained in the same manner. Then, in the same manner as in Example 1, a cured film was formed, and the glossiness of the film was measured. The results are shown in Table 4.

(Results of the Invention) According to the present invention, there is provided a marking ink composition capable of forming a cured film having no gloss and tackiness and having excellent abrasion resistance.

Further, the composition of the present invention can form a cured film having excellent adhesiveness, particularly to a silicone rubber molded article.

Continuation of the front page (56) Reference JP-A-50-124712 (JP, A) JP-A-62-290773 (JP, A) JP-A-56-164891 (JP, A) JP-A-60-20975 (JP , A)

Claims (1)

[Claims] (A) The following average composition formula [I]: In the formula, R is a monovalent hydrocarbon group, a is a number of 1.98 to 2.01, and has at least two alkenyl groups in one molecule, and the viscosity at 25 ° C. is 300 cSt. 100 parts by weight of the above organopolysiloxane, (b) SiO ₂ unit, (R ¹ ) ₃ SiO _{1 ] 2} unit and (R ¹ ) ₂ (R ² ) SiO _{1 ] 2} unit (wherein R ¹ is alkyl And R ² is an alkenyl group), and the total amount of (R ¹ ) ₃ SiO _{1 ] 2} units and (R ¹ ) ₂ (R ² ) SiO _{1 ] 2} units is SiO ₂ units 1 10 to 20 parts by weight of an organopolysiloxane having a alkenyl group content of 1 to 3% by weight in the range of 0.6 to 1.2 moles relative to moles, (c) the following average composition formula [II], In the formula, R ³ is a monovalent hydrocarbon group, b is a number of 1.0 to 2.1, c is a number of 0.5 to 1.0, and b + c = 1.5 to 2.6. An organohydrogen having an amount of at least 3 SiH bonds in one molecule and having 3 mol or more of the above SiH bonds per 1 mol of the total amount of alkenyl groups in the components (a) and (b). Polysiloxane, (d) 50-150 parts by weight of spherical powder of polymethylsilsesquioxane having an average particle size of 50 μm or less, (e) a pigment, and (f) a catalytic amount of platinum or a platinum-based compound. Marking ink composition.