JPH07258606A - Silicone composition for releasing paper - Google Patents

Abstract

PURPOSE:To provide a silicone composition composed of a specific composition and giving a cured coating film having excellent slipperiness and mechanical properties, containing little bleeding substance and exhibiting excellent releasability. CONSTITUTION:This silicone composition free from organic solvent and having a viscosity of 50-10,000cps at 25 deg.C is composed of (A) a mixture of (a) a straight or branched-chain organopolysiloxane having >=2 Si-bonded vinyl groups on the side chain, a vinyl content of 0.5-10 mol% based on the total organic group and a viscosity of 50-10,000cps at 25 deg.C and blocked at both terminals with trialkylsilyl groups and (b) a straight or branched-chain organopolysil-oxane having >=2 Si-bonded vinyl groups and a vinyl content and a viscosity equal to those of the component (a) and blocked at both terminals with triorganosilyl groups, (B) a methyl hydrogen polysiloxane having >=2 Si-bonded H atoms and expressed by formula ((a) is 0-3; (b) is 0 or l; a+b is 1-3) and (C) a catalytic amount of a platinum compound.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention can be applied to the surface of a silicone composition for release paper, especially paper, laminated paper, plastic film, metal foil, etc. without containing an organic solvent. While making it sticky,
The present invention relates to a silicone composition for release paper, which can impart excellent releasability and slipperiness.

[0002]

2. Description of the Related Art In order to prevent sticking or sticking between a substrate such as paper and plastic film and an adhesive substance, or between paper and paper, between paper and plastic film, between plastic films, paper or plastic film and human beings. As for the releasable silicone composition used for imparting slipperiness to the hand, various organic solvent solutions of organopolysiloxane and those having an aqueous emulsion as a main component have been proposed (Japanese Patent Publication No. 35- No. 13,709, Japanese Patent Sho 36
-1,397, Japanese Patent Publication No. 46-26,798).

However, in this organic solvent type,
Although various proposals have been made regarding the siloxane composition, additives, co-catalyst, etc. in order to obtain excellent mold releasability, slipperiness, abrasion resistance, curing characteristics, etc. Since siloxane is a rubber-like high molecular weight compound, it requires a large amount of organic solvent for its use, and thus has a disadvantage of causing air pollution, and this solvent recovery requires a large amount of money. There is a problem that

Further, although the above-mentioned problems due to the use of an organic solvent do not occur in this aqueous emulsion type, the use of an emulsifier may cause a problem of secondary pollution and heating at a high temperature for a long time due to film formation. Since it is necessary and it is difficult to use a high molecular weight organopolysiloxane as a main component, it has excellent physical properties and has a drawback that a film having slipperiness cannot be formed.

[0005]

Therefore, a solventless type composition containing no organic solvent or water has been proposed as the release paper silicone composition (Japanese Examined Patent Publication No. 52-
However, since the polyvinyl siloxane used as the main component has a low molecular weight, the film obtained from this composition has inferior physical properties such as mechanical strength, and has a slip property. The disadvantage is that it becomes scarce and its use is limited.

Regarding this solvent-free silicone release agent, it has been attempted to add a polyether-modified oil, a surfactant, a wax, a slipperiness-imparting agent such as metal soap to dimethylsiloxane oil. The majority of them have poor compatibility with silicone and have the disadvantage that they tend to separate or cause poor curing, and because they bleed out onto the silicone cured film, they are created using them. Then, when an adhesive processed product is manufactured by using a release paper, there is a problem that the adhesive migrates to the surface of the adhesive and reduces its adhesive strength.

Regarding this solventless silicone release agent, a method of adding a high molecular weight organopolysiloxane having a hydroxyl group bonded to a silicon atom to the end of its molecular chain is also known (Japanese Patent Publication No. 3-19,268). However, although it has improved slipperiness and other properties, it has a problem that it is difficult to use it for high-speed coating because of its limited viscosity.

[0008]

The present invention relates to a silicone composition for release paper which solves the above disadvantages, drawbacks and problems. It is 1) bonded to at least 2 silicon atoms in a molecule. It has a vinyl group in its side chain, has a vinyl group content of 0.5-10.0 mol% and a viscosity at 25 ° C of 50
~ 10,000 cps, 100 to 50 parts by weight of a linear or branched organopolysiloxane in which both ends of the molecular chain are blocked with a trialkylsilyl group, and at least two silicon atoms are bound in the molecule. It has a vinyl group, the vinyl group content is 0.5-10.0 mol% and the viscosity at 25 ℃ is 50-100,000.
00 cps, a mixture of 0 to 50 parts by weight of a linear or branched organopolysiloxane in which both ends of the molecular chain are blocked with a triorganosilyl group 100 parts by weight, 2) At least silicon atom in one molecule Having a hydrogen atom bonded to, and a structural unit of (CH ₃ ) _a H _b SiO _{(4-ab) / 2} (where a is an integer of 0 to 3, b is 0 or 1, 1 ≦ a + b ≦ 3) 0.5 to 40 parts by weight of methyl hydrogen polysiloxane represented by 3)
It is characterized in that it comprises a catalytic amount of a platinum compound, contains substantially no organic solvent, and has a viscosity at 25 ° C. of 50 to 10,000 cps.

That is, the present inventors have conducted various studies to develop a solvent-free silicone composition for release paper, which is capable of imparting excellent release properties and slip properties to papers, plastic films and the like. A vinyl group-containing polysiloxane and a methyl hydrogen polysiloxane are addition reaction type catalysts using a platinum compound as a catalyst, and this vinyl group-containing polysiloxane is one having a low degree of polymerization in which a vinyl group does not exist at the end of the molecular chain. Then, the comb-shaped polysiloxy group rises in the network formed by the reaction between the vinyl group-containing polysiloxane and the methylhydrogenpolysiloxane, and it has excellent slipperiness and mechanical properties, and has a small amount of bleed-out substance and releasability. It was found that an excellent film can be obtained even for Advanced has led to the completion of the present invention. This will be described in more detail below.

[0010]

The present invention relates to a silicone composition for release paper, which cures a vinyl group-containing polysiloxane and a methylhydrogenpolysiloxane by an addition reaction in the presence of a platinum compound catalyst. Assuming that this vinyl group-containing polysiloxane has a viscosity of 50 to 10,000 cps at 25 ° C and contains essentially no organic solvent containing vinyl groups at the ends of the molecular chain as its main component, The addition reaction between the vinyl group-containing polysiloxane and the methylhydrogenpolysiloxane gives the advantage of providing a film having excellent slip properties and mechanical properties, less bleed-out substance, and excellent releasability.

The organopolysiloxane as the first component constituting the silicone composition for release paper of the present invention is supposed to have at least two vinyl groups bonded to silicon atoms in one molecule. It is necessary to use, as a main component, a polymer in which a vinyl group does not exist at the terminal of the molecular chain, and this may be one in which an organopolysiloxane having at least one vinyl group at the terminal of the molecular chain is added as a subcomponent.

The vinyl group-containing polysiloxane as the main component is a linear or branched one having at least two vinyl groups bonded to at least silicon atoms in the molecule, which is represented by the following general formula (1) )

[Chemical 1] And R ¹ is an alkyl group such as a methyl group, an ethyl group, a propyl group, and a butyl group, R ² is the same alkyl group as R ¹ , or an aryl group such as a phenyl group and a tolyl group, and a cycloalkyl group such as a cyclohexyl group. A group, or the same or different species selected from a chloromethyl group, a trifluoropropyl group, a cyanoethyl group, etc., in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups are substituted with halogen atoms, cyano groups, etc. Unsubstituted or substituted 1
A valent hydrocarbon group, and

[Chemical 2] (Where L is an integer), for practical purposes, R ¹ and R ² are 80 mol% of which are methyl groups, and m and n are integers of m ≧ 8 and n ≧ 2. The end of the molecular chain is blocked with a trialkylsilyl group.

The vinyl group-containing polysiloxane as the accessory component is also a linear or branched one having at least two vinyl groups bound to at least silicon atoms in the molecule. (2)

[Chemical 3] , R ¹ and R ² are the same as above, a is an integer of 1 to 3, p and q are integers of p ≧ 10 and q ≧ 0, which are shown in the formula. As described above, the end of the molecular chain may be blocked with a dimethylvinylsilyl group, for example.

The vinyl group-containing polysiloxane as the main component or the accessory component has a vinyl group content of all organic groups.
If it is less than 0.5 mol%, the curability will be poor and this will be 10.0
If it exceeds mol%, the peeling resistance of the cured film obtained from this composition becomes large, and the adhesiveness with the pressure-sensitive adhesive becomes unstable in practical use. Therefore, it should be in the range of 0.5 to 10.0 mol% or more. Necessary, preferably 1.0 to 8.0 mol%
It is better to use In addition, since it is necessary for these to have a low degree of polymerization from the viewpoint of coatability, this is necessarily a low viscosity, but 10,000 cps or more is not practically preferable. Therefore, it is necessary that the viscosity at 25 ° C. be in the range of 50 to 10,000 cps, and the preferable range is 100 to 5,000 cps.

The mixing ratio of the main component and the accessory component is
Since the characteristics of the silicone composition of the present invention due to the use of the main component decrease as the mixing ratio of the sub-components increases, the proportion of the sub-component is 0 to 50 parts by weight based on 100 to 50 parts by weight of the main component.
A range of 50 parts by weight is required.

Next, the methylhydrogenpolysiloxane as the second component constituting the silicone composition for release paper may be a known one used in this kind of addition reaction type silicone composition, and one molecule thereof is used. At least two hydrogen atoms bonded to a silicon atom are contained therein, preferably two or more. Examples of this type of polysiloxane include (CH ₃ ) HSiO units, HSiO _3/2 units, (CH ₃ ) ₂ SiO units, and (C
Examples thereof include polymers or copolymers composed of H ₃ ) ₂ HSiO _1/2 units, CH ₃ SiO _3/2 units, and (CH ₃ ) ₃ SiO _1/2 units, which may be linear or cyclic. The viscosity at 25 ° C. may be 10 to 500 cps, but this blending amount may be determined according to the amount of vinyl groups contained in the first component, and usually, a cured film forming and From the viewpoint of peeling performance, it may be in the range of 0.5 to 40 parts by weight with respect to 100 parts by weight of the first component.

The platinum compound as the third component constituting the silicone composition for release paper of the present invention is used as a catalyst for the addition reaction of the above-mentioned first and second components. This may be a known reaction catalyst of this type, and examples thereof include chloroplatinic acid, alcoholic solutions of chloroplatinic acid, aldehyde solutions, chloroplatinic acid and olefins, and vinylsiloxane complex salts. It It should be noted that the addition amount may be a catalytic amount, but in order to obtain a good cured film and from the economical viewpoint, the platinum amount may be in the range of 1 to 1,000 ppm with respect to 100 parts by weight of the first component.

The silicone composition for release paper of the present invention can be obtained by blending the above-mentioned predetermined amounts of the first to third components, which are prepared by uniformly mixing the first and second components in advance. It is preferred to add a third component. In addition,
In order to suppress the activity of the platinum catalyst as the third component, various organic nitrogen compounds, organic phosphorus compounds, acetylene compounds, oxime compounds, organic chloro compounds, and other activity inhibitors may be added as necessary. Good.

Although the silicone composition for release paper of the present invention thus obtained does not contain an organic solvent,
From the viewpoint of coatability, the viscosity at 25 ° C. is preferably in the range of 50 to 10,000 cps, and the specific viscosity value may be determined depending on the type of coating substrate used here.
For example, this coated substrate is polyethylene laminated paper, OP
P film was like aluminum foil, which in a roll coater, a gravure coater, air coaters, curtain flow coater, by known techniques, such as offset transfer rotor, which when applied at a coverage of from 0.3 to 3 g / m ^2, this Should be of low viscosity, such as 50 to 10,000 cps, and higher viscosity for highly permeable substrates such as glassine paper, kraft paper and clay coated paper. Is good.

The substrate treated with the silicone composition for release paper of the present invention is heated at a temperature of 80 to 200 ° C. for 5 to 6 seconds, or is irradiated with ultraviolet rays from an ultraviolet irradiator such as 80 w / cm. When exposed to 0.2 seconds or more, a cured film is formed on the surface, and this cured film has the advantage of exhibiting slipperiness and excellent releasability.

[0021]

EXAMPLES Examples and comparative examples of the present invention will be given below.
Parts in the examples are parts by weight, viscosity is a measured value at 25 ° C., and each physical property in the examples is a measured value by the following methods. (Curable) After applying a predetermined amount of the composition to the surface of a thin film or sheet-shaped substrate, heated in a hot air circulation dryer at a predetermined temperature for a predetermined time, rub the resulting cured film with a finger, Determine the film for shedding and fog.

(Peeling resistance) A predetermined amount of the composition is applied to the surface of a thin film or sheet substrate and heated in a hot air circulation dryer at a predetermined temperature for a predetermined time to give a cured film surface. , Acrylic solvent type adhesive / Olivine BPS-
5127 [trade name of Toyo Ink Mfg. Co., Ltd.] or acrylic emulsion type adhesive / Olivine BPW-3110H
[Product name of the same company] is applied and heat-treated at 100 ° C for 3 minutes, and then high-quality paper with a basis weight of 64g / cm ² is attached to this treated surface.
One round trip with a 2 kg roller, pressure bonding, aging at 25 ° C for a predetermined time, and then cutting into 5 cm width to make a test piece, and using a tensile tester, peeling speed 0.3 m / min at an angle of 180 °, 60
The laminated paper is pulled at m / min, and the force (g) required for peeling is measured.

(Sliding property) After forming a cured film of the composition on the surface of the sheet-shaped substrate by the same method as in the peel resistance test,
Place 200g of urethane rubber or styrene butadiene rubber on the surface, and pull it at 0.3m / min in the direction parallel to the surface of the cured silicone film. Measure the force (g) required here and pull it. Calculate the required force / 200 as the coefficient of dynamic friction (according to ASTM D1894-63). Regarding this slipperiness, relative slipperiness was determined by moving a hand on the surface of the above-mentioned cured film, and this was determined according to the following criteria. ◎… Slip very well ○… Slip well ×
No slipping XX ... No slipping at all

(Residual Adhesion Rate) A cured film of the composition was formed on the surface of the sheet-shaped substrate by the same method as the peel resistance test, and then polyester tape / Lumirror 31B [trade name of Nitto Denko Corporation] was formed on the surface. , Heat treatment at 70 ° C for 20 hours with a load of 20g / cm ² , peel off the tape and attach it to a stainless steel plate, then attach this tape at an angle of 180 ° and a peeling speed of 0.3m / min. And the force (g) required for peeling the tape is measured and expressed as a percentage of the force (g) required for peeling the untreated standard tape.

Examples 1-2, Comparative Examples 1-2 Both ends of the molecular chain are blocked with trimethylsilyl groups,
4 side chains of polysiloxane have 4 vinyl groups bonded, vinyl group content is 1.2 mol% and viscosity is 600 cps
100 parts of a copolymer of dimethyl siloxane and methyl vinyl siloxane is blocked at both ends of the molecular chain with trimethylsilyl groups, contains 70 mol% of methyl hydrogen siloxy units in the molecule, and has a viscosity of 50 cps. Methyl hydrogen polysiloxane 3 parts and formula

[Chemical 4] After adding 1 part of 3-methyl-1-butyn-3-ol represented by 1 and stirring and mixing uniformly, 2 parts of a complex salt of chloroplatinic acid and vinyl siloxane (200 ppm in terms of platinum) is added to the silicone. Composition A was made.

Further, instead of the above-mentioned copolymer of dimethyl siloxane and vinyl siloxane for comparison, both ends of the molecular chain are blocked with dimethyl vinyl silyl groups, and two vinyl chains are provided on the side chains of polysiloxane. The group is bonded, the vinyl group content is 1.2 mol% and the viscosity is 600 cps.
A silicone composition B was prepared in the same manner as in Example 1 except that the copolymer of dimethyl siloxane and methyl vinyl siloxane was used.

Then, the silicone compositions A and B were
The silicone composition C was mixed at 60:40, and 5 parts of dimethyl silicone oil having a viscosity of 1,000 cps was added to the silicone composition B to prepare a silicone composition D. The curability of the silicone compositions A to D When the peel resistance, slipperiness, and residual adhesiveness of the cured film prepared from this were examined, the results shown in Tables 1 and 2 were obtained. In addition, the curability is the measurement result of the composition coated on polyethylene laminated paper at 0.7 g / m ² and treated at 140 ° C. for 20 seconds. No. 2 had satisfactory curability, peeling resistance, slipperiness, and residual adhesiveness, but Comparative Example 1
The sample of Comparative Example 2 had poor slipperiness, and the sample of Comparative Example 2 had
Although the touch was good, it was confirmed that the residual adhesion rate was poor.

[0028]

[Table 1]

[Table 2]

[0029]

INDUSTRIAL APPLICABILITY The present invention relates to a silicone composition for release paper, which has the general formula (1) in which the vinyl group-containing polysiloxane represented by the general formula (2) is added as necessary as described above. The vinyl group-containing polysiloxane shown does not contain an organic solvent consisting of methyl hydrogen polysiloxane and a platinum compound catalyst, and has a viscosity of 50.
~ 10,000 cps, which is represented by general formula (1)
Since the polysiloxane represented by does not have a vinyl group at the end of the molecular chain, this cured film has excellent slipperiness and mechanical properties, less bleed-out substances, and excellent releasability. Gives the advantage of becoming one.

Claims (1)

[Claims] 1. A polymer having a vinyl group bonded to at least two silicon atoms in its side chain in the molecule, the vinyl group content being 0.5 to 10.0 mol% of the total organic groups, and the viscosity at 25 ° C. Is 50
~ 10,000 cps, 100 to 50 parts by weight of a linear or branched organopolysiloxane in which both ends of the molecular chain are blocked with a trialkylsilyl group, and at least two silicon atoms are bound in the molecule. It has a vinyl group, the vinyl group content is 0.5-10.0 mol% of the total organic groups, the viscosity at 25 ° C is 50-10,000 cps, and both ends of the molecular chain are blocked with triorganosilyl groups. 100 parts by weight of a mixture with 0 to 50 parts by weight of a branched or branched organopolysiloxane, 2) having at least two hydrogen atoms bonded to silicon atoms in one molecule and having a structural unit of (CH ₃ ). _a H _b SiO _{(4-ab) / 2} (where a is an integer of 0 to 3, b is 0 or 1 and 1 ≦ a + b ≦
3) Methyl hydrogen polysiloxane represented by
0.5 to 40 parts by weight, 3) a catalytic amount of a platinum compound, which does not substantially contain an organic solvent and has a viscosity at 25 ° C. of 50 to 10,000 cps, and a silicone composition for release paper. object.