TWI694119B - Silicone release coating composition and article having cured release coating - Google Patents

Abstract

This invention relates to a silicone release coating composition comprising: (A) an organopolysiloxane having at least two alkenyl groups in a molecule, (B) an organopolysiloxane having at least two silicon-bonded hydrogen atoms in a molecule, (C) organic modified functional silica particles having an average particle size of 5 μm to 15 μm and a BET specific surface area of 600 m²/g to 800 m²/g, and (D) a hydrosilylation reaction catalyst. The composition can form a coating with a lower release force to sticky adhesive.

Description

Silicone release coating composition and article with cured release coating

The invention relates to a silicone release coating composition. In addition, the present invention relates to articles having a release coating produced by curing the composition.

The silicone release coating composition generally contains an organic polysiloxane having at least two alkenyl groups in the molecule, an organic polysiloxane having at least two silicon-bonded hydrogen atoms in the molecule, a fixing additive, and a hydrosilylation reaction catalyst.

For example, Patent Document 1 discloses a silicone release coating composition comprising: 100 parts by weight of organic polysiloxane, which has at least two alkenyl groups in the molecule; 0.2 to 50 parts by weight of organic polysiloxane, which Has at least three silicon-bonded hydrogen atoms in the molecule; 0.1 to 10 parts by weight of hydrophobic spherical silica powder with an average diameter of 0.1 to 5 μm; and a catalytic amount of platinum group compound, the silicone release coating composition can be formed Silicone release coating exhibiting anti-sticking properties.

However, due to the high curing density, silicone release coating does not possess low release force.

Therefore, there is still a need in this technology to obtain a silicone release coating composition that can form a release coating with the following properties: a lower release force for a viscous adhesive at the same coating weight (CW), Stable release force and good adhesion to the substrate.

Prior technical literature Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. H07-331078

The present invention is to solve the problems cited above, and the objective is to introduce a low-release silicone release coating application. The release coating composition is coated to coat the layer on a film or paper substrate, and cured under heating to form a coated substrate. Another object of the present invention is to provide an article with a silicone release coating that has a low release force for tape peeling, adhesive adhesive or label peeling applications.

The silicone release coating composition of the present invention comprises: (A) an organic polysiloxane with at least two alkenyl groups in the molecule; (B) an organic polysiloxane with at least two silicon bonds in the molecule Hydrogen-bonding atoms, the content of which is sufficient to provide 0.8 to 5 moles of silicon-bonded hydrogen atoms in this component relative to 1 molelinyl group in component (A); (C) Organic modified functional silica particles, an average particle size of 5μm to 15 m, and a BET specific surface area of 600m ² / g to 800m ² / g, an amount of from 0.1 to 5% by weight of the composition, and (D) a catalytic amount of a hydrogenation reaction catalyst of silicon.

Component (A) may be linear organic polysiloxane, branched organic polysiloxane or a mixture thereof. And the branched chain organic polysiloxane may have at least one SiO _4/2 unit in the molecule.

The silicone release coating composition of the present invention may further comprise (E) a hydrosilation reaction inhibitor in an amount of 0.05 to 2 parts by weight of 100 parts by weight of component (A).

The silicone release coating composition of the present invention may further contain (F) a fixing additive in an amount of 0.01 to 10 parts by weight per 100 parts by weight of component (A).

The article of the invention has a release coating produced by curing the silicone release coating composition.

The sheet substrate with cured release coating of the present invention is characterized by a silicone release coating composition in the form of a thin film on the cured sheet substrate. Sheet substrate can be cellophane, coated with adhesive Soil paper, polyolefin-laminated paper, thermoplastic resin film or metal foil.

Component (A) is the basic component of the silicone release coating composition of the present invention, and is an organic polysiloxane having at least two alkenyl groups in the molecule. Examples of alkenyl are vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl and dodecenyl, And vinyl is preferred. In addition to alkenyl groups, examples of silicon-bonded groups are alkyl groups such as methyl, ethyl, propyl, butyl, octyl, etc.; aralkyl groups such as benzyl, phenethyl, etc.; such as phenyl, toluene Aryl groups such as alkyl and xylyl; and methyl is preferred.

Component (A) may be linear organic polysiloxane, branched organic polysiloxane or a mixture thereof. Component (A) is preferably a branched chain organic polysiloxane, and most preferably a branched chain organic polysiloxane having at least one SiO _4/2 in the molecule.

The branched-chain organic polysiloxane can be represented by the following average unit chemical formula: [(R ^a R ^b ₂ SiO _1/2 ) _n (R ^c R ^b ₂ SiO _1/2 ) _1-n ] ₄ (R ^a R ^b SiO _{2 /2} ) _m1 (R ^b ₂ SiO _2/2 ) _m2 (SiO _4/2 )

In the chemical formula, each R ^a is an alkenyl group having 2 to 8 carbon atoms; each R ^b is an alkyl group or phenyl group having 1 to 8 carbon atoms; each R ^c is selected from the group consisting of group of the group: alkyl having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, and a hydroxyl group; R ^a in the presence of at least three molecules; molecule of R ^a, R ^b And at least 50% of the total number of R ^c is an alkyl group having 1 to 8 carbon atoms; n is 0 or 1; when n is 0, m1 is a number with a value of at least 1, when n is 1, m1 is The value is at least 0; m2 is the number with at least 0; and m1+m2=15 to 995.

In the preferred organo siloxane of silicon, R ^a is a vinyl or hexenyl group, m1 range of 0 to 20, and the total number of silicon siloxane units (= m1 + m2 + 4) range from 50 to 400. The preferred viscosity range of the branched chain organic polysiloxane is from 50 to 1,000 mPa. s. The vinyl content is preferably in the range of 0.10 to 3.0 wt%.

Typical examples of this alkyl group having 1 to 8 carbon atoms are methyl, ethyl, propyl and the like, with methyl being preferred. Typical examples of the alkenyl group having 2 to 8 carbon atoms are vinyl, allyl, hexenyl and the like, among which vinyl is preferred. The alkoxy group having 1 to 8 carbon atoms may be methoxy, ethoxy, and the like.

R ^a R ^b ₂ SiO _1/2 units can be exemplified by ViMe ₂ SiO _1/2 units, HexMe ₂ SiO _1/2 units, ViMePhSiO _1/2 units and HexMePhSiO _1/2 units (where Vi represents vinyl and Hex represents hex Alkenyl, Me represents methyl, and Ph represents phenyl; this also applies below). R ^c R ^b ₂ SiO _1/2 units can be exemplified by Me ₃ SiO _1/2 units, (HO)Me ₂ SiO _1/2 units, (MeO)Me ₂ SiO _1/2 units, and Me ₂ PhSiO _1/2 units. The combination of these units (for example, ViMe ₂ SiO _1/2 units and Me ₃ SiO _1/2 units) may be in the same molecule.

R ^a R ^b SiO _2/2 cells can be exemplified by ViMeSiO _2/2 cells and HexMeSiO _2/2 cells. The R ^b ₂ SiO _2/2 unit can be exemplified by the Me ₂ SiO _2/2 unit and the MePhSiO _2/2 unit. The combination of these units (eg, Me ₂ SiO _2/2 units and ViMeSiO _2/2 units) may be in the same molecule.

Component (A) may include linear organic polysiloxane. Straight-chain organic polysiloxane consists of polydimethylsiloxane having an alkenyl group only in its molecular terminal, polydimethylsiloxane having an alkenyl group only in its side chain position, and its molecular terminal An example of polydimethylsiloxane having an alkenyl group in its side chain position. When the composition is cured, the linear organic polysiloxane gradually rises to the formed coating layer, thereby imparting excellent slipperiness to the surface of the cured coating layer. Straight-chain organic polysiloxanes have pendant alkenyl groups. The pendant alkenyl groups can form covalent bonds by hydrosilation and curing systems. In addition, the trialkylsiloxy end does not cure with the system, which can help to transfer part of the molecular chain to the surface of the cured release coating. This property can provide a smooth touch and low release force to the cured release coating. Siloxane with moderate viscosity can provide the applicable viscosity of the final release coating bath used for multi-roll coating machine processing, and also has appropriate reactivity during vulcanization.

Component (B) is a crosslinking agent used in the silicone release coating composition of the present invention, and is an organic polysiloxane having at least two silicon-bonded hydrogen atoms in the molecule. Silicon-bonded hydrogen atom The bonding position is not particularly limited, and (for example), it may be bonded at a molecular chain terminal position, a side chain position, or at both positions. Silicon-bonded organic groups cover phenyl and alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, propyl, butyl, octyl, etc., and preferably at least the total number of such organic groups 50% is an alkyl group having 1 to 8 carbon atoms. From the viewpoint of the nature of the cured coating and the ease of production, methyl is preferred among these alkyl groups. The molecular structure of component (B) is exemplified by straight chain, branched chain, branched and cyclic.

Component (B) may have 1 to 1,000 mPa at 25°C. s viscosity, and preferably 5 to 500mPg. s. The basis is as follows: when the viscosity is less than 1mPa at 25℃. At s, component (B) is easily volatilized from the organic polysiloxane composition; above 1,000 mPa. At s, the organic polysiloxane composition will take a long curing time.

Component (B) can be trimethylsiloxy-terminated methylhydrogen polysiloxane, trimethylsiloxy-terminated dimethylsiloxane. Methylhydrogen siloxane copolymer, dimethylhydrogen alkoxy terminated dimethyl siloxane. Methylhydrogensiloxane copolymer, cyclic methylhydrogenpolysiloxane, cyclic methylhydrogensiloxane. Examples of dimethylsiloxane copolymer, ginseng (dimethylhydrosiloxy) methylsilane and tetrakis (dimethylhydrosiloxy) silane.

An amount sufficient to provide a molar ratio of silicon-bonded hydrogen atoms in this component to the alkenyl group in component (A) of 0.8:1 to 5:1, and preferably sufficient to provide a value of 0.9: The amount of this molar ratio of 1 to 3:1 is incorporated into component (B), that is, in each case, 1.5 to 10 parts by weight are incorporated per 100 parts by weight of component (A). When the molar ratio is less than the lower limit cited above, the curability decreases, and when the cited upper limit is exceeded, a large peel resistance value is generated, and practical releasability cannot be obtained.

Component (C) can provide a release coating having a low release force produced by curing the silicone release coating composition of the present invention, and has an average particle size of 5 μm to 15 μm and a BET specific surface area of 600 m ² /g to 800m ² /g organic modified functional silica particles. Component (C) may be high-porosity silica particles with a porosity greater than 90%. The component (C) has organic functional groups on its surface, such as trimethylsilyl, triethylsilyl, dimethylvinylsilyl, dimethylphenylsilyl. Therefore, it is completely hydrophobic.

The method for manufacturing component (C) is not limited. For example, US 7,470,725 describes a method comprising the steps of: a) modifying the surface of a silica aerogel by a silanizing agent; and b) drying the surface-modified gel obtained in step a).

The silanizing agent can in principle be in any state of aggregation, but is preferably liquid and/or gas or vapor. If gas and/or vapor silanizing agents are used, the temperature of the hydrous silica aerogel is preferably between 20°C and 100°C, and particularly preferably between 40°C and 100°C, and in particular, in Between 60°C and 100°C. Under pressure, in order to avoid boiling of water in the gel capillary, higher temperatures are also possible. If a liquid silanizing agent is used, the temperature of the hydrous silica aerogel is preferably between 20°C and 100°C. Under pressure, in order to avoid boiling of water in the gel capillary, higher temperatures are also possible. If a gas and/or vapor silanizing agent is used, it can be present in the gas stream or in a static gas atmosphere during the reaction. The temperature of the silanizing agent in the gas phase can also be increased by means of pressure or by additional gas flow.

Such organically modified functional silica particles can be purchased from Dow Corning as "Dow Corning ^® VM-2270 Aerogel Fine Particles".

Component (D) is a hydrosilation reaction catalyst that promotes the hydrosilylation reaction between the silicon-bonded hydrogen atom in component (B) and the alkenyl group in component (A). Except that component (D) is a catalyst for hydrosilation reaction, there is no specific limitation on it, and component (D) can be modified by platinum type catalyst (such as chloroplatinic acid, alcohol modified chloroplatinic acid, chlorine Platinum acid/olefin complex, chloroplatinic acid/ketone complex, platinum/alkenylsiloxane complex, platinum tetrachloride, platinum fine powder, supported on a carrier (such as alumina powder or silica powder ) On the solid platinum, platinum black, platinum olefin complexes, platinum carbonyl complexes) and powdered thermoplastic resins (e.g., methyl methacrylate resins) incorporating platinum catalysts as listed previously , Polycarbonate resin, polystyrene resin, silicone resin, etc.) specific examples.

Other examples are such as [Rh(O ₂ CCH ₃ ) ₂ ] ₂ , Rh(O ₂ CCH ₃ ) ₃ , Rh ₂ (C ₈ H ₁₅ O ₂ ) ₄ , Rh(C ₅ H ₇ O ₂ ) ₃ , Rh( C ₅ H ₇ O ₂ )(CO) ₂ , Rh(CO)[Ph ₃ P](C ₅ H ₇ O ₂ ), RhX ₃ (R ^d ₂ S) ₃ , (R ^e ₃ P) ₂ Rh(CO )x, (R ^e ₃ P) ₂ Rh(CO)H, Rh ₂ X ₂ Y ₄ , H _a Rh _b (E) _c Cl _d and Rh[O(CO)R ^e ] _3-n (OH) _n (wherein, X is a hydrogen atom, a chlorine atom, a bromine atom or an iodine atom; Y is alkyl, CO, or C ₈ H _14; R ^d is alkyl, cycloalkyl or aryl group; R ^e is an alkyl group, an aryl group , Alkoxy or aryloxy; E is olefin; a is 0 or 1; b is 1 or 2; c is an integer from 1 to 4; d is 2, 3 or 4; and n is 0 or 1) rhodium Catalysts such as Ir(OOCCH ₃ ) ₃ , Ir(C ₅ H ₇ O ₂ ) ₃ , [Ir(Z)(E) ₂ ] ₂ and [Ir(Z)(Dien)] ₂ (where Z is chlorine Atom, bromine atom, iodine atom or alkoxy group, E is olefin; and Dien is cyclooctadiene) iridium catalyst.

From the perspective of the ability to accelerate the reaction, chloroplatinic acid, platinum/vinylsiloxane complex and platinum olefin complex are preferred, and chloroplatinic acid/divinyltetramethyldisilazane complex Compound, chloroplatinic acid/tetramethyltetravinylcyclotetrasiloxane complex and platinum/alkenylsiloxane complex (for example, platinum. divinyltetramethyldisilaxane complex) , Platinum/tetramethyltetravinylcyclotetrasiloxane complex, etc.) are particularly preferred.

Incorporating the component (D) in a catalytic amount, and usually incorporating the component (D) at 10 to 600 ppm, and preferably at 5 to 500 ppm (in each case, refer to the silicone release coating of the present invention The total weight of the composition is the amount of metal in component (D)).

In addition to the components previously described, the silicone release coating composition of the present invention also contains a hydrosilation reaction inhibitor (E) in order to make it thermosetting while improving storage stability by suppressing gelation and curing at ambient temperature . This hydrosilation reaction inhibitor can be exemplified by alkynyl alcohols, enyne compounds, organic nitrogen compounds, organic phosphorus compounds, and oxime compounds, and can be exemplified by 3-methyl-1-butyn-3-ol, 3,5-dimethyl Alkynyl alcohols such as 3-yl-1-hexyn-3-ol, 3-methyl-1-pentyn-3-ol, 3-phenyl-1-butyn-3-ol; Enpentyne compounds of 3-pentene-1-yne, 3,5-dimethyl-1-hexyne-3-ene; and consist of benzotriazole, 1-ethynyl-1-cyclohexanol and methyl Specific examples of vinylcyclosiloxanes.

The amount of component (E) is not limited, but it is usually in the range of 0.05 to 2 parts by weight, and preferably in the range of 0.01 to 2 parts by weight (in each case, at 100 parts by weight of component (A )meter), And according to need, the type of hydrosilation inhibitor, the nature and incorporation of hydrosilation catalyst, the amount of alkenyl groups in component (A) and the amount of silicon-bonded hydrogen atoms in component (B) And choose.

In addition to the components previously described, the silicone release coating composition of the present invention also contains a fixing agent (F) in order to enhance the adhesion of the cured release coating to the substrate. Component (F) is exemplified by the reaction product of a fluid polyorganosiloxane having at least one alkenyl group and at least one silanol group in the molecule and a hydrolyzable silane having at least one epoxy group.

Fluid polyorganosiloxanes used in the preparation of fixation additives usually contain at least one alkenyl group and at least one silanol group. The polyorganosiloxane generally contains a chain of at least 3 siloxane units, and is preferably a substantially linear polydiorganosiloxane. The degree of polymerization of the polyorganosiloxane is preferably at least 4 siloxane units, and preferably at least 6 siloxane units. The degree of polymerization of polyorganosiloxane is usually up to 30, 50 or 200 siloxane units. The polyorganosiloxane may, for example, have a viscosity in the range of 2 to 200 mm ² /s at 25°C. The alkenyl group may, for example, have 2 to 6 carbon atoms, such as vinyl or 5-hexenyl. The polyorganosiloxane generally also contains an alkyl group, especially an alkyl group having 1 to 4 carbon atoms (such as methyl or ethyl), and may contain an aryl group such as phenyl. The alkenyl group may exist as a pendant group, for example, the copolymer may be polymethylvinylsiloxane, or a copolymer of methylvinylsiloxane units and dimethylsiloxane units, or divinylsiloxane Copolymer of alkane units and dimethylsiloxane units. Alternatively or additionally, the alkenyl group may be present as an end group, for example, in the form of methyl vinyl silanol end units. The silanol group is preferably present in a terminal unit (such as a dimethylsilanol or methylvinylsilanol terminal unit). Preferably, the polyorganosiloxane is a polydiorganosiloxane having terminal silanol groups at both ends of the silicone chain, but part or all of the polyorganosiloxane may have a silanol end group and An Si-alkoxy end group, for example, a dimethylmethoxysilyl end unit. The polyorganosiloxane can be formed, for example, from the reaction of methylvinyldimethoxysilane and dimethyldimethoxysilane in the presence of a silane hydrolysis catalyst such as alkali or acid.

Hydrolyzable silanes that react with polyorganosiloxanes to form anchoring additives usually contain at least one epoxy group in the molecule. The epoxy group may, for example, exist as a glycidyl group or 3,4-epoxycyclohexyl group. Examples of suitable hydrolyzable silanes include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, methyl(3-glycidoxypropyl)dimethoxy Silane, methyl (3-glycidoxypropyl) diethoxysilane, 2-(3,4-epoxycyclohexyl) ethyl trimethoxysilane and 3-(3,4-epoxy ring Hexyl)propyltrimethoxysilane.

Fluid polyorganosiloxane and hydrolyzable silane can react at high temperature and/or in the presence of silanol condensation catalyst. The catalyst may be, for example, a base such as potassium hydroxide, sodium hydroxide, potassium silylate or phosphazene base, or may be an acid such as HCl, or may be an organic compound of titanate or tin. The reaction temperature is preferably in the range of 50 to 150°C. Therefore, the new fixation additive prepared usually contains at least one epoxy group, at least one alkenyl group and at least one alkoxy group in its molecule.

Such fixation additives are available from Dow Corning as " Syl-Off ^® 297 fixation additives", " Syl-Off ^® SL 9250 fixation additives" and " Syl-Off ^® SL 9176 fixation additives".

The amount of component (F) is not limited, but it is usually in the range of 0.01 to 10 parts by weight, and preferably in the range of 0.01 to 5 parts by weight (in each case, at 100 parts by weight of component (A )meter).

By uniformly coating the silicone release coating composition of the present invention as described above on various sheet-shaped substrates (eg, cellophane, cardboard, clay-coated paper, polyolefin-laminated paper (and especially laminated Polyethylene paper), thermoplastic resin film (for example, polyester film, polyethylene film, polypropylene film, polyamide film), natural fiber fabric, synthetic fiber fabric, metal foil (for example, aluminum foil), etc.) On either surface, and under conditions suitable for subjecting components (A) and (B) to cross-linking through the hydrosilylation reaction, it can be formed on the surface of the sheet-shaped substrate to exhibit better slipperiness and relative to A cured low-release silicone release coating with a suitable peel resistance value for viscous materials.

Usually 100 to 200°C is suitable for the curing temperature of the silicone release coating composition of the present invention on a sheet substrate, but when the substrate has good heat resistance, a curing temperature higher than 200°C can be used. The heating method is not particularly limited, and may be, for example, heating in a hot air circulation furnace, passing through a long furnace, or radiant heating using an infrared lamp or a halogen lamp. Curing can also be achieved by using heating combined with exposure to ultraviolet radiation. When component (D) is a platinum/alkenyl siloxane complex catalyst, even when incorporated into this catalyst at 50 to 200 ppm (referring to the amount of platinum metal in the total composition), it can still be easily at 100 A cured coating exhibiting excellent adhesion to a sheet-shaped substrate and excellent release properties relative to an adhesive substance is obtained in a short period of time (ie, 40 to 1 second) at 150°C.

The silicone release coating composition of the present invention is particularly preferably applied on at least one side of the sheet substrate by a multi-roll coating machine. Regarding the adhesive substance that can be applied to the release sheet or film produced by applying the silicone release coating composition of the present invention to the surface of the sheet substrate and curing, the adhesive substance may be, for example, Various pressure-sensitive adhesives and any of various adhesives, and examples thereof are acrylic resin-based pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives and silicone-based pressure-sensitive adhesives, and acrylic resin-based adhesives, Synthetic rubber type adhesive, silicone type adhesive, epoxy resin type adhesive and polyurethane type adhesive. Other examples are pitch, sticky foods such as mochi (ie, rice cakes), gums and pastes, and sticky bird gums. The preferred application of the present invention is a multi-roll coater with on-site coating processing on both sides.

The composition of the present invention is suitable for forming a cured coating that exhibits better surface slip and excellent low-release performance relative to a viscous substance, and is particularly suitable as a process paper, asphalt packaging paper and Various plastic film curing release coating forming agent. In addition, a sheet-shaped substrate with a release coating formed by curing the composition of the present invention is extremely suitable for processing paper, coating or wrapping paper of adhesive substances, pressure-sensitive adhesive tape, pressure-sensitive labels, etc. .

Examples

Practical examples and comparative examples are given below in order to describe the invention in detail; however, the present invention The description is not limited to the following examples. "SiH/Vi" in the following Tables 2 to 4 indicates the ratio of the number of moles of silicon-bonded hydrogen atoms in component (B) per vinyl group in component (A). The raw materials of silicone release coating compositions of practical examples and comparative examples are shown in Table 1 below.

Evaluation procedure:

(1) Coating weight (CW before erasing): The Oxford lab-x 3500 instrument manufactured by Oxford Instruments PLC (Oxford Instruments Public Co., Ltd.) in Oxfordshire, UK uses X-rays to detect the coating weight of silicone. Use uncoated PET as a blank. Refer to FINAT Test Method No. 7 (FINAT Technical Manual 2005 7th Edition).

(2) Coating weight after wiping (CW after wiping): Use the Oxford lab-x 3500 instrument to test the coating weight of the applied release coating. Then use the wear tester (Elcometer 1720) to rub the sample 30 turns at a speed of 30 turns/minute. Finally, the coating weight is tested again to measure the relative fixation effectiveness.

(3) Fixation rate (RO%): The fixation rate (RO%) is recorded as (CW after erasing)/(CW before erasing)×100%.

(4) Release force (RF-RT): 180 degree peel test is used to measure the release force from the liner with Tesa 7475 standard tape, which is laminated on the coated release coating , Load a weight of 20 g/cm ² on the laminated sample and let stand at RT (room temperature) for 20 hours. After 20 hours, remove the load and wait 30 minutes. Next, the release force was tested by Chem Instruments AR-1500. Refer to FINAT Test Method No. 10 (FINAT Technical Manual 2005 7th Edition).

(5) Release force (RF-70℃ aging): 180 degree peel test is used to measure the release force from the liner with Tesa 7475 standard tape, which is laminated on the coated release coating On the layer, the laminated sample was loaded with a weight of 20 g/cm ² and allowed to stand at 70°C for 20 hours. After 20 hours, remove the load and wait 30 minutes. Next, the release force was tested by Chem Instruments AR-1500. Refer to FINAT Test Method No. 10 (FINAT Technical Manual 2005 7th Edition).

(6) SAS (follow-up adhesive strength, indicator of migration): The test tape is laminated on the coated release coating with Nitto Denko 31B tape, loaded with a weight of 20 g/cm ² and allowed to stand at 70°C for 20 hour. After 20 hours, remove the load and wait 30 minutes at room temperature. Then transfer the 31B tape on the PET substrate and wait another hour. The release force was tested by Chem Instruments AR-1500. In the SAS test, 31B tape was laminated on a PTFE substrate and the PTFE sample was processed in the same manner as the release coating sample. The SAS value is recorded as RF _release /RF _PTFE ×100%. Refer to FINAT Test Method No. 11 (FINAT Technical Manual 7th Edition 2005).

(7) Extractable %: The curing characteristics of the coating are evaluated by measuring the percentage extractable after the coating is cured. By first using Oxford Instruments, Oxfordshire, UK The LabX 3000 X-ray fluorescence spectrometer manufactured by PLC performs X-ray fluorescence analysis to determine the coating weight of a standard-sized substrate sample with a cured coating to perform this operation. The coated sample is then placed in a glass bottle with a solution of methyl isobutyl ketone solvent to extract any unreacted silicone that has not been cross-linked into the coating matrix or adhered to the substrate. After shaking the bottle for a predetermined period of time (immersion in MIBK for 30 minutes), the sample was removed from the solvent, dried, and the coating weight was measured again. Calculate the percentage of coating weight loss due to solvent extraction.

Practical Examples 1 and 2, and Comparative Example 1

The formulation of the silicone release coating composition of practical examples 1 and 2 and comparative example 1 is shown in Table 2 below. The composition was coated on a PET substrate by a coater, and then cured at 140°C for 30 seconds. Table 2 also shows the efficacy of the composition.

Practical Examples 3 to 6, and Comparative Example 2

The formulations of the silicone release coating compositions of practical examples 3 to 6 and comparative example 2 are shown in Table 3 below. The composition was coated on a PET substrate by a coater, and then cured at 140°C for 30 seconds. Table 3 also shows the efficacy of the composition.

Practical Example 7 and Comparative Examples 3 and 4

The formulation of the silicone release coating composition of practical example 7 and comparative examples 3 and 4 is shown in Table 4 below. The composition was coated on a PET substrate by a coater, and then cured at 140°C for 30 seconds. Table 4 also shows the efficacy of the composition.

Industrial applicability

The silicone release coating composition of the present invention is suitable for forming a cured coating on the surface of a sheet-shaped substrate with a lower release force for adhesive adhesives, low migration, and good adhesion to the substrate. Sheet-shaped substrates with a cured coating from the aforementioned composition are suitable for processing paper/film, paper/film for coating or packaging adhesive substances, pressure-sensitive adhesive tapes, pressure-sensitive labels, etc.

Claims (9)

A silicone release coating composition comprising: (A) an organic polysiloxane having at least two alkenyl groups in the molecule; (B) an organic polysiloxane having at least two silicon bonds in the molecule Hydrogen-bonding atoms, the content of which is sufficient to provide 0.8 to 5 moles of silicon-bonded hydrogen atoms in this component relative to 1 mole of the alkenyl groups in component (A); (C) Organically modified functional silica particles having an average particle size of 5μm to 15 m, and a BET specific surface area of 600m ² / g to 800m ² / g, an amount of from 0.1 to 5% by weight of the composition, and a catalytic amount of (D) a hydrogenation reaction catalyst silicon . The silicone release coating composition according to claim 1, wherein component (A) is a linear organic polysiloxane, a branched organic polysiloxane or a mixture thereof. The silicone release coating composition according to claim 2, wherein the branched chain organic polysiloxane has at least one SiO _4/2 unit in the molecule. The silicone release coating composition according to any one of claims 1 to 3, further comprising (E) a hydrosilation reaction inhibitor in an amount of 0.05 to 2 parts by weight per 100 parts by weight of component (A). The silicone release coating composition according to any one of claims 1 to 3, further comprising (F) a fixing additive in a content of 0.01 to 10 parts by weight per 100 parts by weight of component (A). The silicone release coating composition according to claim 4, further comprising (F) a fixing additive in a content of 0.01 to 10 parts by weight per 100 parts by weight of component (A). An article having a release coating produced by curing the silicone release coating composition according to any one of claims 1 to 6. A sheet substrate with a cured release coating, which is obtained by curing the sheet substrate Produced in the form of a thin film silicone release coating composition according to any one of claims 1 to 6. The sheet substrate with a cured release coating according to claim 8, wherein the sheet substrate is cellophane, paper coated with clay, paper laminated with polyolefin, thermoplastic resin film or metal foil.