JP2743739B2 - Curable organopolysiloxane composition for release paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable organopolysiloxane composition for release paper which gives a film having excellent curability and good release characteristics.

[0002]

2. Description of the Related Art
For the purpose of preventing adhesion or sticking between a pressure-sensitive adhesive sheet and a substrate such as paper or a plastic film, a silicone composition film is formed on the surface of the substrate to impart releasability. ing.

[0003] A method of forming a silicone film on the surface of a substrate is as follows: a platinum compound is used as a catalyst, and an organopolysiloxane containing an aliphatic unsaturated group is subjected to an addition reaction with an organohydrogenpolysiloxane to form a release film. And a method of forming a release film by subjecting an organopolysiloxane to a condensation reaction using an organometallic salt catalyst such as an organotin compound.

[0004] The siloxane composition used in these methods is called a thermal cure type because it forms a film by heating, and depending on its properties, a solvent type dissolved in an organic solvent such as toluene or an emulsion obtained by emulsifying it. Type and solventless type consisting of silicone only.

[0005] From the viewpoint of productivity, the first method, which has a higher curing rate than the second method, is widely used. In this case, the addition type siloxane composition used in the first method is used. As the crosslinking agent, methyl hydrogen polysiloxane represented by the following general formula is widely used as an organohydrogen polysiloxane.

[0006]

Embedded image (Where m and n are positive numbers, respectively)

However, a composition which is faster in curing than an organopolysiloxane composition for release paper using such a methyl hydrogen polysiloxane as a crosslinking agent is desired from the viewpoint of energy saving and high productivity.

[0008] The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a curable organopolysiloxane composition for release paper which has excellent curability and gives a film having good release characteristics.

[0009]

The present inventors have conducted intensive studies to achieve the above object, and as a result, have at least two vinyl groups directly connected to silicon atoms in one molecule,
And an organopolysiloxane having a viscosity of 50 centipoise or more at 25 ° C. and a crosslinking agent represented by the following general formula (I):
A conventional organopolysiloxane composition using methylhydrogenpolysiloxane as a crosslinking agent by blending a silalkylene compound having three HSi≡ groups at both ends of the molecular chain represented by It has a faster curing speed than products, has excellent curability, can be cured at low temperatures or cures at high speeds, and gives a film with excellent release properties such as release force, residual adhesion rate, and silicone transferability, and is effective for release paper. It has been found that a curable organopolysiloxane composition can be obtained.

[0010]

Embedded image (Where n is an integer of 2 ≦ n ≦ 8)

That is, the silalkylene compound of the above formula (I) effectively acts as a crosslinking agent for the above-mentioned vinyl group-containing organopolysiloxane, cures at a high rate in the presence of a platinum group metal-based catalyst, and saves energy. In addition to satisfying the demand for high productivity, the silalkylene compound of the formula (I) does not impair the release force, residual adhesive force, and silicone transferability required for a release paper film, and can be used as an organopolysiloxane for release paper. The inventors have found that the composition has excellent performance as a crosslinking agent, and have accomplished the present invention.

Accordingly, the present invention provides: (1) an organopolysiloxane having at least two vinyl groups directly bonded to silicon atoms in one molecule and having a viscosity at 25 ° C. of 50 centipoise or more; A curable organopolysiloxane composition for release paper, comprising a silalkylene compound represented by the formula (I) having three HSi≡ groups at both ends of the molecular chain, and (3) a platinum group metal catalyst. Offer things.

Hereinafter, the present invention will be described in further detail. The organopolysiloxane composition for release paper according to the present invention, which is the first component, has at least two vinyl groups directly bonded to silicon atoms in one molecule. , A main component in the composition of the present invention.

Here, in the organopolysiloxane, the vinyl group is preferably contained in an amount of 0.05 to 50 mol%, more preferably 0.2 to 10 mol%, based on all organic groups.
It is preferable to be contained.

If the vinyl group content is less than 0.05 mol%, a substantially cured film may not be obtained, and if it exceeds 50 mol%, the synthesis becomes difficult and the effect on the physical properties becomes almost constant. Not good.

Examples of the organic group bonded to a silicon atom other than a vinyl group include 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 a carbon atom such as these. And the same or different unsubstituted or substituted monovalent hydrocarbon groups in which part or all of the hydrogen atoms bonded to are substituted with halogen atoms, cyano groups, and the like. Among these, a methyl group is particularly preferable, and an organopolysiloxane having at least 50 mol% of a methyl group is preferable. The terminal of the molecular chain may be any of a hydroxyl group, an alkyl group, a vinyl group and the like, but is preferably a vinyl group from the viewpoint of curability.

The organopolysiloxane must have a viscosity at 25 ° C. of at least 50 centipoise from the viewpoint of the performance of the film to be formed. It may be of the form.

Next, in the present invention, a silalkylene compound represented by the following general formula (I) is blended as the second component.

[0019]

Embedded image (Where n is an integer of 2 ≦ n ≦ 8)

The silalkylene compound of the formula (I) is
The HSi≡ group in the molecule undergoes a hydrosilylation reaction with the vinyl group in the organopolysiloxane of the first component to act as a crosslinking agent. In this case, the silalkylene compound has a high reaction activity because it contains three HSi≡ groups at both ends of the molecular chain, and the silalkylene compound has two or one HSi≡ groups at both ends of the molecular chain. Cannot obtain the effect of the present invention, that is, excellent curability.
On the other hand, if n exceeds 8, the adhesiveness to the substrate may decrease, which is not preferable.

The silalkylene compound of the formula (I) is
For example, an alkenyl trichlorosilane such as vinyltrichlorosilane and allyltrichlorosilane is subjected to an addition reaction with trichlorosilane in the presence of a platinum catalyst, or
Addition of 1,1,2,2-tetramethyldisiloxane to hydrochloric acid or the like to an intermediate obtained by performing an addition reaction of a diene such as 4-pentadiene or 1,5-hexadiene with trichlorosilane in the presence of a platinum catalyst. Then, by reacting under acidic conditions and hydrolyzing, it can be easily synthesized.

The amount of the silalkylene compound to be compounded is the ratio of the ≡SiH group in the silalkylene compound to the ≡SiCH ＝ CH ₂ group in the organopolysiloxane of the first component, that is, H / CH ＝ CH ₂ is 0. The amount is preferably in the range of 8 to 20, particularly 1 to 10. If the above ratio is less than 0.8, a substantially cured film may not be obtained.
If it exceeds 0, heavy peeling may occur in terms of peeling performance.

Further, in the present invention, in addition to the above silalkylene compound as a crosslinking agent, if necessary, methyl hydrogen polysiloxane represented by the following general formula may be used in combination as long as the effects of the present invention are not impaired.

[0024]

Embedded image (Where m and n are positive numbers, respectively)

In the composition of the present invention, a platinum group metal-based catalyst is used as the third component in order to effectively advance the addition reaction. Specific examples of the platinum group metal-based catalyst include platinum-based, palladium-based, and rhodium-based catalysts, and among these, a platinum-based catalyst is particularly preferable. Examples of such a platinum-based catalyst include chloroplatinic acid, alcohol solutions and aldehyde solutions of chloroplatinic acid, and complexes of chloroplatinic acid with various olefins or vinylsiloxanes.

The amount of the platinum group metal-based catalyst added is the amount of the catalyst, but from the viewpoint of obtaining a good cured film and saving economic waste, the amount of the platinum group metal based on 100 parts by weight of the first component is reduced. Is preferably in the range of 1 to 1,000 ppm.

The composition of the present invention can be obtained by mixing predetermined amounts of the above-mentioned first to third components. In addition to the above components, other optional components, for example, a platinum group metal-based catalyst For the purpose of suppressing the activity of the compound, an activity inhibitor such as various organic nitrogen compounds, organic phosphorus compounds, acetylene compounds, oxime compounds, and organic chloro compounds may be added as necessary.

In preparing the composition of the present invention, it is preferable to mix the components other than the third component beforehand, and then to add the third component.
More than one species may be used in combination. Moreover, you may dissolve in organic solvents, such as toluene, xylene, and n-hexane, as needed.

The organopolysiloxane composition prepared as described above is applied to a substrate such as paper or plastic film and then cured by heating in a conventional manner. The substrate on which the cured film of the composition of the present invention is thus formed is used as a release paper.

[0030]

The curable organopolysiloxane composition for release paper of the present invention is excellent in curability and gives a film having good release characteristics, and has excellent performance for use in release paper.

[0031]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Synthesis Examples, Examples and Comparative Examples, but the present invention is not limited thereto. In the following description, all parts mean parts by weight, and the viscosity is a value at 25 ° C.

The curing speed, peeling force, residual adhesiveness and silicone transferability of the organopolysiloxane composition were measured by the following methods.

<Effect Speed> A predetermined amount of the organopolysiloxane composition is applied to the surface of a thin film or sheet-like substrate and heated in a hot air drier at a predetermined temperature, and the formed cured film is finger-formed. It was rubbed several times, and the time until it became a state without clouding (smear) was measured.

<Peeling Force> A predetermined amount of the organopolysiloxane composition was applied to the surface of a thin film or sheet substrate, and heated in a hot air dryer at a predetermined temperature for a predetermined time to form a cured film. Next, an acrylic solvent-type pressure-sensitive adhesive: Oripine BPS-5127 (manufactured by Toyo Ink Mfg. Co., Ltd.) is applied to the surface of the cured film so as to have a solid content of 30 g / m ² and heated at 100 ° C. for 3 minutes. Processed.

A high quality paper having a basis weight of 64 g / m ² was bonded to the treated surface to prepare a sample, and the obtained sample was cut into a width of 5 cm. After the sample was aged at 25 ° C. for 20 hours, the bond was peeled off using a tensile tester under the conditions of an angle of 180 ° and a peeling speed of 0.3 m / min, and the force required for peeling [g]. Was measured.

<Residual Adhesion Ratio> A polyester tape (trade name: Lumirror 31B, manufactured by Nitto Denko Corporation) is applied to the surface of the cured film of the organopolysiloxane composition formed on the substrate surface in the same manner as in the case of the peel force measurement. Stuck together, 2
After heating and aging at 70 ° C. for 20 hours under a load of 0 g / cm ² , the tape was peeled off and attached to a stainless steel plate. Next, the above tape was removed from the stainless plate by 180 °
And the force [g] required for peeling was measured.

After aging the above tape bonded to a Teflon plate instead of the polyester tape under the same conditions, and then similarly bonding the tape to a stainless steel plate, the force [g] required for peeling was measured in the same manner. Then, the ratio of the two measured values was calculated and expressed as a percentage.

<Silicon transferability> After the organopolysiloxane composition formed on the substrate surface is cured in the same manner as in the measurement of the peeling force, 25 μm is applied to the cured film surface.
m of polyethylene terephthalate (PET) film was bonded and subjected to a pressure bonding treatment at 25 ° C. for 60 minutes under a load of 10 kg / cm ² . An oily magic was applied to the silicone pressure-bonded surface of the PET film after the pressure-bonding treatment, and the migration of the silicone was evaluated based on the presence or absence of cissing.

[Synthesis Example] Vinyltrichlorosilane 162
g of alcohol solution of chloroplatinic acid in 100 g
pm, stirred and heated to 65 ° C. To this, 150 g of trichlorosilane was added dropwise over 1 hour, aged at 120 ° C. for 2 hours, and distilled.
256 g of bistrichlorosilylethane was obtained (at this time, the degree of reduced pressure was 5 mmHg, and the temperature was 59 to 61 ° C.).

Next, a mixture of 576 g of 1,1,2,2-tetramethyldisiloxane, 200 g of concentrated hydrochloric acid and 80 g of water was cooled and stirred at 5 ° C., and a mixture of 256 g of the above intermediate and 100 g of toluene was added for 4 hours. And slowly dropped. After further stirring at 5 to 15 ° C. for 1 hour, 500 g of water was added and stirred, and the organic layer was separated and washed with water four times for neutralization. This was distilled to obtain 406 g of a silalkylene compound represented by the following formula (II) (at this time, the degree of reduced pressure was 5 mm).
Hg, temperature 117-118 ° C., gas chromatographic purity 92%).

[0041]

Embedded image

Example 1 A compound of the formula (II) obtained in the synthesis example was used as a crosslinking agent in 100 parts of dimethylpolysiloxane having a viscosity of 400 centipoise whose molecular chain ends were blocked with a dimethylvinylsiloxy group. / ≡SiCH
= CH ₂ is 2 amount (3.19 parts) was added, further 1-
0.5 part of ethynyl-1-cyclohexanol was added, and the mixture was stirred to be uniform. To this was added a complex of platinum and vinyl siloxane so as to be 400 ppm in terms of platinum to prepare an organopolysiloxane composition A.

Example 2 The molecular chain end was blocked with a dimethylvinylsiloxy group, and the dissolution viscosity of 30% toluene containing 1.5 mol% of methylvinylsiloxane units was 500.
A compound of the above formula (II) is used as a crosslinking agent in 30 parts of dimethylpolysiloxane of 0 centipoise in ≡SiH / ≡Si.
CH = CH ₂ is added in an amount of 2 (1.03 parts), and 1.5 parts of a silicon compound having an acetylenically unsaturated group represented by the following formula is further mixed with toluene so that the active ingredient becomes 30%. And dissolved uniformly.

[0044]

Embedded image To this was added a complex of platinic acid and vinylsiloxane so as to be 200 ppm in terms of platinum to prepare an organopolysiloxane composition B.

Example 3 A crosslinking agent represented by the above formula (II)
1.60 parts and 1.2 parts of a methyl hydrogen polysiloxane represented by the following formula (III), respectively.
Organopolysiloxane composition C was prepared in the same manner as in Example 1 except that a mixture of 0 parts (in a molar ratio of 1/1) was used.

[0046]

Embedded image

Comparative Example 1 As a crosslinking agent, the compound of the above formula (II)
2.39) Methyl hydrogen polysiloxane
An organopolysiloxane composition D was prepared in the same manner as in Example 1 except that parts were used.

Comparative Example 2 The following formula (IV) was used as a crosslinking agent.
The methyl hydrogen polysiloxane represented by
Organopolysiloxane composition E was prepared in the same manner as in Example 2 except that 00 parts were used.

[0049]

Embedded image

The obtained silicone compositions A to E were coated on polyethylene laminated paper so that the coating amount was 0.6 g / m ^2, and the curing property was at a temperature of 100 ° C. The measurement was performed after curing at 140 ° C. for 30 seconds. Table 1 shows the results.

From the results shown in Table 1, it was confirmed that the curable organopolysiloxane composition of the present invention has excellent curability and gives a film having good peeling properties.

[0052]

[Table 1]

Claims (1)

(57) [Claims] (1) an organopolysiloxane having at least two vinyl groups directly bonded to silicon atoms in one molecule and having a viscosity at 25 ° C. of 50 centipoise or more; (2) the following general formula (I): A silalkylene compound having three HSi≡ groups at both ends of the molecular chain represented by (Wherein, n is an integer of 2 ≦ n ≦ 8) (3) A curable organopolysiloxane composition for release paper, comprising a platinum group metal-based catalyst.