JP3271510B2 - Method for producing release silicone composition and release substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release substrate which can easily release an adhesive substance and is used as a back surface treatment agent for tapes or a release liner for labels. The present invention relates to a water-soluble silicone composition and a method for producing a peelable substrate using the same.

[0002]

2. Description of the Related Art Conventionally, a silicone composition has been applied to the surface of a base material, such as paper, processed paper, plastic film, etc., for the purpose of preventing adhesion and sticking of the base material to an adhesive substance. 2. Description of the Related Art Forming a film to impart releasability has been performed. In this case, as a method of forming a silicone film on the substrate surface, a platinum compound is used as a catalyst, and an organopolysiloxane containing an aliphatic unsaturated group and an organohydrogenpolysiloxane are subjected to a hydrosilylation reaction to release the mold. There are known a method of forming a film, a method of forming a releasable film by subjecting an organopolysiloxane to a condensation reaction using an organic acid metal salt catalyst such as an organic tin compound, and the like. The silicone compositions used in these methods are all referred to as thermosetting types in which a film is formed by heating, and depending on their properties, silicone is dissolved in an organic solvent such as toluene, and a solvent type is dispersed in water. Emulsion type and solventless type consisting only of silicone. Regarding the above addition reaction by hydrosilylation, an alkynyl group-containing organic compound having a C≡C bond in the molecule has been proposed as a reaction control agent (JP-B-44-31476). , Practical bath life is now possible, and it is now widely used industrially. However, in this alkynyl group-containing organic compound, the alkaline substance used in the synthesis tends to remain, and the alkaline substance causes a dehydrogenation reaction with the SiH of the organohydrogenpolysiloxane, and there is a risk that the container may burst during storage. At the same time, there is a problem that the curability due to the addition reaction is significantly reduced.

For this reason, as a conventional supply form of the addition type silicone, a polysiloxane having an alkenyl group, a so-called base polymer, an addition reaction controlling agent, and a platinum catalyst are packaged in one package, and the organohydrogenpolysiloxane is packaged in another package. Although a two-liquid supply system is known, a method of providing a base polymer, an organohydrogenpolysiloxane, a catalyst, a reaction control agent, and the like as a separate package in order to allow an end user to adjust the amounts of the respective components. Was proposed (Japanese Patent Publication No. 1-36871). However, this method is cumbersome to use, since the end user needs to measure and mix all the components separately, especially the crosslinking agent,
Since the amount of the control agent is very small and the characteristics greatly change depending on the ratio, it has to be measured accurately and the mixing requires a great deal of labor.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a peelable silicone composition which has excellent storage stability and is easy to be used by an end user, and a method for producing a peelable substrate using the same. And

[0005]

Means for Solving the Problems and Actions The present inventors have made intensive studies to achieve the above object, and as a result, have found that a composition comprising three packages in which a releasable composition is blended at a specific ratio. The present invention was found to be excellent in storage stability and easy to be used by an end user, and led to the present invention.

Accordingly, the present invention provides (i) a releasable silicone composition comprising the following packages (1) to (3): (1) 25% or more alkenyl groups per molecule; ° C
(2) a mixture of the following a) to c): a) an organopolysiloxane having at least three hydrogen atoms in one molecule and having a viscosity of 10 to 100 centipoise at 25 ° C. 5% to 60% by weight of the total mixture of hydrogen polysiloxanes a) to c) b) An organic compound having one or more alkynyl groups in one molecule, and its extraction water PH (at 25 ° C.) is 5.0 to 5.0. Hydrosilylation reaction control agent purified to be in the range of 7.0 0.5 to 30% by weight of the total mixture of a) to c) c) Two or more alkenyl groups in one molecule, and 25 ° C 10 to 94.5% by weight of the total mixture of organopolysiloxanes a) to c) having a viscosity of 100 to 500 centipoise. (3) having at least two alkenyl groups in one molecule, at 25 ° C.
(Ii) 5 to 15 parts by weight of package (2) and 1 part of package (3) based on 100 parts by weight of package (1), dispersed in an organopolysiloxane having a viscosity of 100 to 500 centipoise.
A release layer composed of a cured product of the above-mentioned releasable silicone composition formed on the substrate by heating and curing the mixture after coating on the substrate. And a method for producing the same.

[0007]

Hereinafter, the present invention will be described in detail. The package (1) is a so-called base polymer composed of an organopolysiloxane having an alkenyl group bonded to at least two silicon atoms in one molecule. Alkenyl groups include vinyl, allyl, hexenyl,
A dodecenyl group is exemplified, and a preferred alkenyl group is a vinyl group. This alkenyl group is used in an amount of 0.05 to 5 based on all organic groups in the organopolysiloxane.
It is preferably contained in an amount of 0 mol%, particularly 0.2 to 10 mol%. If the amount of the alkenyl group is less than 0.05 mol%, a substantial curing rate may not be obtained,
If it exceeds mol%, the synthesis becomes difficult and the peeling force becomes heavy. Examples of the organic group other than the alkenyl group bonded to the silicon atom include, for example, an alkyl group such as a methyl group, an ethyl group and a propyl group, an aryl group such as a phenyl group and a tolyl group, and hydrogen bonded to these carbon atoms. Same or different substituted or unsubstituted monovalent hydrocarbon groups in which some or all of the atoms have been substituted with halogen atoms, cyano groups, and the like can be mentioned. The organic group other than the alkenyl group bonded to the silicon atom is desirably 50% by mole of the total organic group.

The organopolysiloxane is preferably linear, but may be branched. The substituent bonded to the terminal silicon atom may be, for example, any of an alkenyl group, an alkyl group, a hydroxyl group and an alkoxy group, but preferably has at least one alkenyl group.

Further, since the above-mentioned organopolysiloxane is coated on a substrate as a thin film of about 1 μm without being diluted with a solvent, and a film is formed by heating, the viscosity at 25 ° C. is 100 to 500 centipoise. desirable.
Less than 100 centipoise easily penetrates the paper substrate.
If it is more than 00 centipoise, the leveling property when coated at high speed is inferior, and it is difficult to obtain a uniform cured film.

Next, among the components constituting the package (2), the organohydrogenpolysiloxane which is the component a) has a hydrogen atom bonded to at least three or more silicon atoms in one molecule. It is a crosslinking agent that reacts with an organopolysiloxane having an alkenyl group in the presence of a catalyst. The other organic groups of the organohydrogenpolysiloxane are not particularly limited, and may be various organic groups. It is preferable that 90 mol% or more of all the organic groups are methyl groups. Specific examples of such an organohydrogenpolysiloxane include (CH ₃ ) H
SiO unit, HSiO _3/2 unit, (CH ₃ ) ₂ SiO
Examples thereof include a homopolymer or a copolymer composed of a unit and (CH ₃ ) ₃ SiO _1/2 unit, and these may be any of linear, branched, and cyclic. The organohydrogenpolysiloxane preferably has a viscosity at 25 ° C. of 10 to 500 centipoise, particularly 15 to 100 centipoise, in view of dispersibility and coatability.

Next, as the hydrosilylation reaction controlling agent which is the component b) of the package (2), a coordination agent for a platinum catalyst is generally used. At ambient temperature, the hydrosilylation reaction is suppressed, and a thin film is formed on the substrate. When heated after coating, the hydrosilylation reaction needs to proceed promptly. For this purpose, an organic compound containing at least one alkynyl group in the molecule is suitable. Specifically, the following are exemplified.

[0013]

The hydrosilylation reaction controlling agent having one or more alkynyl groups depends on the amount of the platinum catalyst in the package (3), and at least C≡C / Pt needs to be at least twice (molar ratio).

Further, according to the present invention, b) of the package (2)
The pH of the extraction water of the hydrosilylation reaction control agent is 5.0 to 5.0.
It was found that the use of a substance purified so as to fall within the range of 7.0 enables the organohydrogenpolysiloxane and the hydrosilylation reaction control agent to come into contact with each other at a higher concentration than the concentration conventionally compounded. Invented the invention. 6. Extraction water PH of the hydrosilylation reaction control agent is 7.
If it is 0 or more, the SiH of the organohydrogenpolysiloxane undergoes a dehydrogenation reaction, and the pressure may cause the container to rupture. At the same time, the role as a crosslinking agent may be significantly reduced, and the curability of the silicone composition may be reduced. Will be damaged. When the pH of the extracted water is 5.0 or less, when stored for a long period of time, the siloxane bond of the cross-linking agent cracks and changes into a volatile cyclic substance, so that it does not function effectively as a cross-linking agent. .

The extraction water PH of the hydrosilylation reaction control agent is defined as 10 g of the control agent and 30 g of ion-exchanged water.
This is the pH (25 ° C.) of the aqueous layer in the case where the mixture was shaken at 25 ° C. for 1 hour, then left to stand and separated.

The component c) of the package (2) is the same as the polysiloxane of the package (1).

The proportion of each of the components a), b) and c) in the package (2) is from 5/60 / 0.5 to 30/10 to 94.5.
By mixing them in advance and providing them to the end user, the number of times of weighing at the time of use is reduced and the complexity of minute weighing is alleviated. This amount must be further within the above range and adjusted by the total amount of the alkenyl group-containing organopolysiloxane of c) of the package (1) and the package (2). That is, the compounding amount of the component a) depends on the package (1).
And 0.3 parts by weight based on a total of 100 parts by weight of the alkenyl group-containing organopolysiloxane of the component c) of the package (2).
The range is from 10 to 10 parts by weight. If the amount is less than 0.3 parts by weight, the releasable film-forming property is impaired. The amount of the component (b) is 0.03 to 5 parts by weight, and preferably 0.03 to 5 parts by weight, based on 100 parts by weight of the alkenyl group-containing organopolysiloxane of the component (c) of the package (1) and the package (2). 3 to 3 parts by weight. When the amount is less than 0.03 parts by weight, it is difficult to obtain a control effect, and when the amount is more than 5 parts by weight, the curability is impaired.

A platinum-based catalyst having two or more alkenyl groups in one molecule of the package (3) and dispersed in an organopolysiloxane having a viscosity at 25 ° C. of 100 to 500 centipoise is a catalyst for promoting the addition reaction. Any known addition reaction catalyst can be used. Examples thereof include chloroplatinic acid, alcohol solutions and aldehyde solutions of chloroplatinic acid, and complexes of chloroplatinic acid with various olefins and vinylsiloxane. In order to enhance the dispersibility with the components of the packages (1) and (2), it is necessary to previously disperse the platinum catalyst in an organopolysiloxane having an alkenyl group. Is desirable. An organopolysiloxane having two or more alkenyl groups in one molecule in which a platinum-based catalyst is dispersed and having a viscosity of 100 to 500 centipoise at 25 ° C. is a package (1).
And alkenyl group-containing organopolysiloxanes of (2).

The amount of the component (3) used is 1 to 5 parts by weight based on 100 parts by weight of the total of the alkenyl group-containing organopolysiloxanes of the packages (1) and (2). It is adjusted to 0.001-0.15 parts by weight. If the amount is less than 1 part by weight, an error tends to occur at the time of weighing. If the amount is more than 5 parts by weight, the ratio of the alkenyl group and the SiH of the crosslinking agent tends to be different from the designed value, so that it is difficult to use a common catalyst type. Become.

In the method for producing a peelable substrate according to the present invention, the package prepared as described above is prepared by using (1) :( 2) :( 3)
Are mixed at a weight ratio of 100: 5 to 15: 1 to 5, coated on a base, and then heated. This compounding ratio is a simple integer ratio (e.g.,
(100: 10: 2).

The procedure for mixing the above components is not particularly limited, but it is preferable to add the package (3) containing the platinum catalyst last. Each component may be a single compound or a mixture of two or more.
Further, the present composition may be used as it is, but it is also possible to dilute it with an organic solvent such as toluene, xylene, hexane or heptane before use.

As the base material, kraft paper, glassine paper,
Paper bases such as clay-coated paper, laminated paper such as polyethylene-laminated high-quality paper, polyethylene-laminated kraft paper, and plastic films obtained from synthetic resins such as polypropylene and polyester. Glassine paper and polyethylene-laminated paper are particularly preferred. is there. Coating and heating methods are conventionally known methods, for example, silicone is coated using a gravure offset coater, a multi-cut roll coater, etc., and heated in a hot air circulation type drying furnace to produce a peelable substrate. can do.

The release substrate thus obtained is useful for a release layer of an adhesive tape or an adhesive label.

[0025]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, all parts are parts by weight, and the viscosity is a value at 25 ° C. The storage stability, curability, peeling strength, and residual adhesion of the silicone composition were measured by the following methods.

The composition containing the storage-stable cross-linking agent or the cross-linking agent itself
400 g was placed in a 00 cc metal square can and left at 25 ° C. for 2 months, and the blister of the can was observed. In addition, 20c
1.0g into a glass sample bottle with rubber stopper
After heating at 0 ° C. for 5 days, the measurement was performed by comparing the generated hydrogen gas with a nitrogen gas (area ratio) using a headspace gas chromatograph.

[0027]Curability  About 1 g / m2 of the prepared silicone composition^ThreeTo be
On polyethylene laminated paper using offset printing machine
And heated at 100 ° C with a hot-air circulation dryer.
The time when smear and rub-off did not occur was measured.

[0028]Peeling force  About 1 g / m2 of the prepared silicone composition^ThreeTo be
On polyethylene laminated paper using offset printing machine
And heated at 140 ° C for 30 seconds using a hot air circulation dryer.
After heating to form a cured film, acrylic
Solvent solvent adhesive, Olivain BPS-5127 [Toyo Ai
Niki Manufacturing Co., Ltd.] and heat treatment at 100 ° C. for 3 minutes.
I understood. Next, weighing 64 g / m^ThreeHigh quality paper
After aging at 25 ° C for 20 hours,
The sample was cut into 5 cm widths and 180
At a peel rate of 0.3 m / min.
The force required to stretch and peel was measured.

[0029] After forming the cured film of the residual adhesiveness peel strength silicone composition to the substrate surface in the same manner as in the measurement, bonding a polyester tape knit -31B [Nitto Denko Co., Ltd.] to the surface After heating and aging at 70 ° C. for 20 hours under a load of 20 g / cm ³ , the tape was peeled off and attached to a stainless steel plate. Next, this treated paper was removed from the stainless steel plate by 1
Peel at an angle of 80 ° at a peeling speed of 0.3 m / min, measure the force (g) required for peeling, and the force (g) required for peeling an untreated standard tape from a stainless steel plate.
And these ratios were taken and expressed as percentages.

Example 1 Package (1): A dimethylpolysiloxane having a viscosity of 400 centipoise and a molecular chain terminal blocked with a dimethylvinylsilyl group Package (2-1); 2.37 parts of 30 centipoise methyl hydrogen polysiloxane, Surfynol 61
(Air Products and Chemica
once with an equal volume of 0.01 N aqueous hydrochloric acid.
After washing three times with twice the volume of ion-exchanged water, distill and extract PH
Is 6.0 (3,5-dimethyl-1-hexyne-
0.44 parts of 3-ol) and 7.19 parts of a dimethylpolysiloxane base having a viscosity of 400 centipoise and having a molecular chain terminal blocked with a dimethylvinylsilyl group were mixed. Package (3): A catalyst was prepared by dissolving olefin-platinum complex in dimethylpolysiloxane having a viscosity of 400 centipoise and having a molecular chain terminal blocked with a dimethylvinylsilyl group at a concentration of 0.5% of platinum as platinum. 100 parts of package (1) left for 2 months at room temperature,
10 parts of (2-1) and 2 parts of (3) were used as the release silicone composition, and the curability and the release characteristics were measured. Table 1 shows the results of the stability test of the package (2-1), and Table 2 shows the curability and the peeling properties. As a result, the package (2-1) has excellent stability, and the composition of the peelable composition is simple.
Because of its excellent curability and release characteristics, it was easy to manufacture a release substrate.

[0031]

[Comparative Example 1] 100 parts of dimethylpolysiloxane having a viscosity of 400 centipoise and having a molecular chain terminal capped with a dimethylvinylsilyl group, and the molecular chain terminal capped with a trimethylsilyl group, were stored in the same manner as in Example 1. 2.44 parts of methylhydrogenpolysiloxane having a viscosity of 30 centipoise, Surfynol 61 (Air Products and
Chemicals) was washed once with an equal volume of 0.01 N hydrochloric acid and three times with a three-fold amount of ion-exchanged water, and then distilled. 0.45 parts of -1-hexyn-3-ol) dissolved in dimethylpolysiloxane having a molecular chain end of 400 centipoise and capped with a dimethylvinylsilyl group so that the olefin-platinum complex becomes 0.5% in terms of platinum. Table 2 shows the results of measurement of the curability and the peeling properties when 1.87 parts of the resulting mixture was blended.

[0033]

[Table 1]

[0035]

[Table 2]

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08L 83/05 D21H 27/00 A D21H 27/00 C09J 7/02 // C09J 7/02 C08K 5/54 (56) References JP-A-6-256659 (JP, A) JP-A-6-128487 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 83/00-83/16 B32B 27/00 C08K 5/00-5/24 D21H 27/00 C09J 7/02

Claims (3)

(57) [Claims] 1. A releasable silicone composition comprising the following packages (1) to (3). (1) at least two alkenyl groups in one molecule at 25 ° C.
(2) a mixture of the following a) to c): a) an organopolysiloxane having at least three hydrogen atoms in one molecule and having a viscosity of 10 to 100 centipoise at 25 ° C. 5% to 60% by weight of the total mixture of hydrogen polysiloxanes a) to c) b) An organic compound having one or more alkynyl groups in one molecule, and its extraction water PH (at 25 ° C.) is 5.0 to 5.0. Hydrosilylation reaction control agent purified to be in the range of 7.0 0.5 to 30% by weight of the total mixture of a) to c) c) Two or more alkenyl groups in one molecule, and 25 ° C 10 to 94.5% by weight of the total mixture of organopolysiloxanes a) to c) having a viscosity of 100 to 500 centipoise. (3) having at least two alkenyl groups in one molecule, at 25 ° C.
Catalyst dispersed in organopolysiloxane having a viscosity of 100 to 500 centipoise 2. Package (1) and package (2)
Component a) 0.3 to 10 parts by weight of organohydrogenpolysiloxane of component a) and 100 to 100 parts by weight of total content of alkenyl group-containing organopolysiloxane of component c), and hydrosilylation reaction control agent of component b) 0.03 ~
The peelable silicone composition according to claim 1, which is contained in a proportion of 5 parts by weight. 3. A mixture of 5 to 15 parts by weight of the package (2) and 1 to 5 parts by weight of the package (3) with respect to 100 parts by weight of the package (1). A method for producing a releasable substrate, comprising forming a release layer comprising a cured product of the releasable silicone composition according to claim 1 on a substrate by heating and curing.