JPH0524181B2 - - Google Patents

Description

[Detailed description of the invention]

<<Industrial Application Field>> The present invention relates to a silicone composition for release paper.
More specifically, the present invention has excellent storage stability at room temperature after adding the catalyst and before coating;
The present invention relates to a silicone composition for release paper that cures at low temperatures and in a short time after being applied to various types of paper, plastic film, and other substrates. <<Conventional technology>> Conventionally, organopolysiloxanes containing aliphatic unsaturated groups bonded to silicon atoms and organohydrodiene polysiloxanes containing hydrogen atoms bonded to silicon atoms (≡SiH bonds) are combined in the presence of a noble metal catalyst. So-called addition reaction type silicone compositions, which are reacted in the following manner, are widely used for various purposes and are also used for release paper. However, in order to use this addition reaction type silicone composition for release paper, it is necessary to form a cured film in a short period of time, usually at 100°C to 150°C for 10 to 30 seconds.
Therefore, there were problems in that the pot life was short and it was difficult to balance it with hardenability. A method to solve this problem is to add CCl ₄ as an addition reaction control agent (Japanese Patent Publication No. 47-6111).
(Japanese Patent Publication No. 44-31476), acrylonitrile added (Japanese Patent Publication No. 45-22018), 1,3
- Added dichloropropene (Unexamined Japanese Patent Publication No. 1983-
238851), those containing maleates (U.S. Patent Publications No. 4256807, U.S. Patent Publication No. 4530989,
4562096) etc. have been proposed. However, when CCl ₄ is added as a control agent, it has no effect of suppressing the addition reaction unless it is used in large quantities. Therefore, the difference between the effect as a solvent in solvent dilution and the effect as a solvent is not clear, and it is impossible to obtain a substantially solvent-free coating liquid. Furthermore, when acetylene alcohols are added, since they are reactive with hydrogen-silicon bonds, the hydrogen-silicon bonds as curing functional groups contained in the composition are consumed over time, resulting in hardening. Not only does it have the disadvantage of reduced properties, but it is also volatile and has a low flash point, so if it is used as a solvent-free coating solution, there is a limit to the amount it can be added due to safety concerns. Furthermore, in the case of acrylonitrile, the addition reaction inhibitory effect is weak and adding a small amount is ineffective, so if a large amount is added to exert the inhibitory effect, a composition containing a large amount of acrylonitrile will not cure properly, and acrylonitrile Environmental problems also arise because they emit a peculiar odor. The above disadvantage is that diallyl-
This can be improved by using maleate esters, maleimides, hydrocarboxymalates, etc., but since they all have low solubility in organopolysiloxane, the amount of addition is limited when uniformly curing the composition into a thin film. had its limitations and was not satisfactory. The inventors of the present invention have made intensive studies to solve the conventional drawbacks, and have found that the silylated maleic ester compound has an excellent effect of suppressing the addition reaction, has good compatibility with organopolysiloxane, and has a low boiling point.
The present invention was completed by discovering that the temperature is higher than 200°C and does not generate any peculiar odor. Accordingly, a first object of the present invention is to provide a silicone composition for release paper that has a longer pot life before application without impairing the curability of the silicone composition after application. A second object of the present invention is to provide a silicone composition for release paper that is not flammable, does not generate any particular odor, and has good workability. A third object of the present invention is to provide an addition reaction inhibitor that can relatively extend the pot life of an addition reaction-curing silicone composition after addition of a platinum catalyst. <Means for Solving the Problems> The above objects of the present invention are (1) having at least two vinyl group-silicon bonds in one molecule, with both ends of the molecular chain being vinyldimethylsilyl groups or trimethylsilyl groups; 100 parts by weight of a certain substantially linear organopolysiloxane, (2) at least 2 parts per molecule;
2 to 30 parts by weight of methylhydrodiene polysiloxane having hydrogen-silicon bonds, (3) general formula ^A silylated ^{maleic acid ester compound} represented ^by
At least one of them is an olefinic unsaturated group. ): 0.1 to 10 parts by weight, (4) The amount of platinum is 2 to 500 ppm based on the component (1) above, and the number of vinyl groups in one molecule of the component (1) and the component ( 2) was achieved by a silicone composition for release paper characterized in that the total number of hydrogen-silicon bonds in one molecule is at least 5. Each component used in the present invention will be explained in detail below. Component (1) is a substantially linear diorganopolysiloxane having vinyldimethylsilyl or trimethylsilyl groups at both ends of its molecular chain, and is represented by the following formula, for example. In the above formula, R, R' and R'' represent an organic group,
at least 50 mol% of them are methyl groups,
The remaining organic groups are organic groups excluding aliphatic unsaturated bonds. Examples of such organic groups excluding aliphatic unsaturated bonds include alkyl groups such as ethyl, propyl, and butyl groups, aryl groups such as phenyl, and halogen-substituted products thereof. In the case of diorganopolysiloxane in which both ends of the molecular chain are vinyldimethylsilyl groups, n is 0.
Alternatively, n is a positive integer, and in the case of a diorganopolysiloxane in which both ends of the molecular chain are trimethylsilyl groups, n is an integer of 2 or more. These organopolysiloxanes may be used alone or in combination as long as they have at least two vinyl-silicon bonds in one molecule. In addition, the viscosity range is 50 cs or more at 25°C up to a gum-like viscosity. Note that "substantially linear" means a linear structure having a linear structure or a partially branched portion. The methylhydrodiene polysiloxane as component (2) contains at least two hydrogen atoms in one molecule.
It is a methylhydrodiene polysiloxane with silicon bonds. However, it is necessary that the total number of vinyl groups in one molecule of component (1) and the number of hydrogen-silicon bonds in one molecule of component (2) be at least five. Examples of methylhydrodiene polysiloxane include CH ₃ HSiO units, HSiO _1.5 units,
(CH ₃ ) ₂ SiO units, CH ₃ SiO _1.5 units,
A homopolymer or copolymer consisting of _0.5 units of (CH ₃ ) ₂ HSiO or _0.5 units of (CH ₃ ) ₃ SiO is exemplified. This polymer may be a linear polymer, a cyclic polymer, or a branched polymer, and is heated at 25°C.
Methylhydrodiene polysiloxane and dimethyl-methylhydrodiene polysiloxane having a viscosity of 10 to 500 cs are preferred. The amount of component (2) added is usually 2 to 30 parts by weight per 100 parts by weight of component (1), considering the formation of a cured film and the peeling performance.
Parts by weight. Component (3) is a general formula It is a silylated maleic acid ester compound represented by It is a reaction control agent that enables curing in a short time at low temperatures of 100° C. or lower, and is an important component in the composition of the present invention. In the above general formula, R ¹ , R ² , R ³ are methyl groups,
It is an aliphatic hydrocarbon group having 1 to 10 carbon atoms such as an alkyl group such as an ethyl group, a propyl group, a butyl group, an alkenyl group such as a vinyl group or an allyl group, and R ¹ ,
At least one of R ² and R ³ is an alkenyl group. When none of R ¹ , R ² and R ³ contains an alkenyl group, the reaction suppression effect is poor.

[Formula] (silyl group) includes, for example, the following. Among these, especially

[Formula] is preferable, and among them, is most preferred. The above-mentioned reaction inhibitor dissolves well in the present organopolysiloxane composition for release paper, especially in the solvent-free organopolysiloxane composition, is colorless and transparent, has no odor, and is nonvolatile, so it is suitable for use in solvent-free organopolysiloxane compositions. It is safe and has good workability when applied as a polysiloxane composition to paper, plastic film, etc. As mentioned above, since the reaction inhibitor and the organopolysiloxane have good compatibility, the reaction control effect in this composition is stable and the reproducibility of the film curing characteristics is also good. The curability of this composition by heating after it is applied to the surface of a thin film base material such as paper or film varies depending on the amount of component (3), which is the reaction inhibitor, added, but component (1)
It is appropriate to use 0.1 to 10 parts by weight per 100 parts by weight. If it is less than 0.1 part by weight, the storage stability of the composition at room temperature is poor and the viscosity increases in a short period of time.
If the amount is 10 parts by weight or more, the storage stability at room temperature is very good, and the viscosity of the treatment bath will hardly change even after a long period of time, but the curing properties after application will be significantly reduced, so the curing time must be lengthened or the curing time must be increased. This is not preferred because the temperature must be increased and the characteristics of the composition will be lost. The platinum-based compound as component (4) used in the present invention can be appropriately selected from those known as catalysts for the addition reaction of components (1) and (2). Examples of these catalysts include chloroplatinic acids such as monochloroplatinic acid and dichloroplatinic acid, alcohol compounds of chloroplatinic acid, aldehyde compounds, and complex salts of chloroplatinic acid and various olefins. The amount of these catalysts added is preferably in the range of 1 to 1000 ppm, particularly 2 to 500 ppm of platinum based on component (1), in order to obtain a good cured film and from an economic standpoint. The composition of the present invention can be obtained by blending predetermined amounts of the above components (1) to (4), but the blending method is to uniformly mix components (1) to (3) in advance, and then ,
It is desirable to add component (4). Depending on the use and purpose, this composition may also include foamed silica,
Wet silica, dyes, pigments, etc. may be added,
The addition of silica has effects such as improving film strength, controlling slipperiness, improving adhesion, and controlling printability. The composition of the present invention obtained in this way has a viscosity of 50 to 25°C at 25°C from the viewpoint of workability during application.
It is preferable to use a solvent-free type in the range of 10,000 cs. The viscosity of the composition may be appropriately determined depending on the amount of coating, the coating method, and the type of substrate to be coated. 0.3 to 3 g/m ² using known techniques such as gravure coater, air coater, curtain flow coater, offset transfer roll coater, etc.
When applying at a coating rate of It is preferable to use a high value. The silicone composition for release paper of the present invention prepared as described above has good storage stability at room temperature, and can be applied to the surface of thin film substrates such as paper and plastic films under low temperature curing conditions of 100°C or less. A cured film can be formed in a short time and has no adverse effect on adhesive substances. In addition,
The composition of the present invention can also form a cured film by irradiation with ultraviolet rays. For example, by irradiating the film with an ultraviolet ray irradiator such as 80W/cm for 1.0 seconds or more, it is possible to provide the same properties as in the case of forming a cured film using heat. <Effects of the Invention> The composition of the present invention uses a silylated maleic ester compound that is highly compatible with organopolysiloxane and has a boiling point of 200°C or higher as a reaction control agent, thereby lowering the flash point of the composition. It is particularly advantageous when coating in the production of solvent-free release paper because it has no odor and is stable in pot life before coating, resulting in good workability. Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. In the examples, all "parts" represent parts by weight, and the viscosity represents the value measured at 25°C. Example 1 and Comparative Examples 1 to 3 Dimethylpolysiloxane with a viscosity of 1000 cs, in which both ends of the molecular chain are blocked with dimethylvinylsilyl groups.
100g and the following formula where both ends of the molecular chain are blocked with trimethylsilyl groups A silicone composition was prepared by adding 5.0 x 10 ^-3 moles of various compounds shown in Table 1 to 102 g of a mixture with 2.0 g of methylhydrodiene polysiloxane having a viscosity of 40 cs, and the appearance, odor, and flammability were evaluated. Examined. Next, 1.0 g of platinum vinyl siloxane complex (platinum amount: 0.5%) was added to the above composition to prepare a silicone composition, and the pot life of these was investigated.
When the coating was applied to a thickness of g/m ² and its curability, peeling force, and residual adhesion rate were examined, the results shown in Table 1 were obtained. As is clear from the results in Table 1, Comparative Example 1 has a short pot life of less than 1/2 day, Comparative Example 2 has a low flash point of 120°C, and Comparative Example 3 is opaque and has insufficient uniformity. On the other hand, in the case of the present invention, it has been demonstrated that all of the problems of these comparative examples could be solved. In addition, the appearance was visually observed, the flash point was determined using the sealed method (JISK2265), and the curing performance was determined using a hot air circulation dryer.
Evaluation was made based on the state of the cured film after curing at 120°C for 30 seconds. The evaluation was 0 if it could be rubbed with fingers and there was no clouding or falling off. In addition, pot life refers to the time it takes to gel when left standing at 25℃, and the degree of peeling refers to the amount of time it takes to gel when left standing at 25℃. After applying the product (trade name) and heating it for 100℃ x 30 seconds, laminated the laminated paper with a basis weight of 40g/ ^m2 , and using a tensile tester, the peeling speed was 300m at an angle of 180℃. /min represents the force (g) when pulling the laminated paper. In addition, the residual adhesion rate can be determined by forming a cured film in the same way as in the case of peeling force, and applying Polyester Table Lumirror 31B (manufactured by Nitto Electric Industries, Ltd.) to the surface of the cured film.
were bonded together and aged at 70° C. for 20 hours under a load of 20 g/cm ² , the tape was peeled off, and the tape was attached to a stainless steel plate, and the peel force was measured in the same manner as in the case of the peel force described above. Values are percentages of the peel force of untreated standard tape.

[Table] ｜
_CH3
Example 2 Curing properties were obtained in the same manner as in Example 1, except that allyldimethylsilyl, trivinylsilyl, and trimethylsilylated products were used in place of the vinyldimethylsilyl group of the maleic acid silylated product used in Example 1. When the pot life was investigated, good results as shown in Table 2 were obtained.

[Table] The results in Table 2 demonstrate the effectiveness of the silicone composition for release paper of the present invention in all cases.

Claims (1)

[Scope of Claims] 1 (1) An organopolymer having a substantially linear structure having at least two vinyl-silicon bonds in one molecule and having vinyldimethylsilyl or trimethylsilyl groups at both ends of the molecular chain. Siloxane: 100
Parts by weight (2) Methylhydrodiene polysiloxane having at least two hydrogen-silicon bonds in one molecule: 2 to 30 parts by weight (3) General formula ^A silylated ^maleic acid ^ester compound ^{represented by}
At least one of R ³ is an olefinic unsaturated group. ): 0.1 to 10 parts by weight (4) The amount of platinum is 2 to 10 parts by weight based on the above component (1).
500 ppm of a platinum-based compound, characterized in that the total number of vinyl groups in one molecule of component (1) and the number of hydrogen-silicon bonds in one molecule of component (2) is at least 5. A silicone composition for release paper. 2. The silicone composition for release paper according to claim 1, which has a viscosity at 25°C of 50 to 10,000 cs. 3. The silicone composition for release paper according to claim 1 or 2, wherein at least one of ^R1 , ^R2 , and ^R3 is a vinyl group or an allyl group, and the remaining groups are methyl groups.