JP3176010B2 - Radiation-curable organopolysiloxane composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a radiation-curable organopolysiloxane composition, and more particularly to a radiation-curable organopolysiloxane composition which is easily cured by radiation and adheres well to a substrate such as a plastic film. The present invention relates to a radiation-curable organopolysiloxane composition that can be easily peeled off.

[0002]

2. Description of the Related Art A radiation-curable organopolysiloxane composition comprising an organopolysiloxane containing a (meth) acryloxy group in the molecule is known. The production method includes ring-opening addition of an epoxy group. A method of introducing a (meth) acryloxy group into a siloxane using a reaction (see JP-A-63-135426 and JP-A-2-45533), and introducing a (meth) acryloxy group into a siloxane using a hydrosilylation reaction. Method (Japanese Unexamined Patent Publication No.
-48000, see JP-A-2-163166).

However, this kind of radiation-curable organopolysiloxane composition is mainly used as a coating agent for surface treatment, and since the cured film has a property of easily releasing an adhesive substance, in particular, In addition, it is used as a back surface treatment agent for adhesive tapes and a coating agent for release paper for adhesive labels.

[0004]

On the other hand, in recent years, pressure-sensitive adhesive tapes and pressure-sensitive labels have been mechanically bonded, and the mechanical bonding is performed at a high speed, so that the force required for peeling increases. For this reason, a large force is applied to the release paper, and the release paper is likely to vibrate, and this vibration generates a sound (peeling sound). Since the peeling noise is noise, the working environment is adversely affected. In addition, generating this peeling sound means that the width of the peeling force increases, and the mechanical bonding device is designed so that tapes and labels can be stuck at fixed positions with a certain peeling force. In addition, there is a problem that the machine does not function properly when the deflection width of the peeling force becomes large, and since this peeling sound is not generated so much when the peeling force is small, it is generated when the peeling force is increased to some extent. There is a need to provide a release agent that does not generate release noise even when the release force is large.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a radiation-curable organopolysiloxane composition which solves such disadvantages and problems. The radiation-curable organopolysiloxane composition has the general formula (I)

Embedded image [Where R ¹ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms or a phenyl group, R ² is the same group as R ¹ or a compound represented by the general formula (I
I)

Embedded image (Where R ³ is a hydrogen atom or a methyl group, n is 1 to 3), and 0.5 to 3.0 mol% of the total organic groups bonded to the silicon atom in one molecule is generally A group represented by the formula (II), wherein c is 0 to 3, a + b × c + d = 500
~ 1000] organopolysiloxane (A)
And the general formula (III)

Embedded image (R ¹ is the same as above, R ² is the same group as R ¹ or a compound of the general formula (II)
In the group represented by the formula, 5 to 20 mol% of the total organic groups bonded to the silicon atom in one molecule is a group represented by the general formula (II), g is 0 to 3, and e + f × g + h = 50-200)
And an organopolysiloxane (B) as a main component,
The mixing ratio (weight ratio) is organopolysiloxane (A) / organopolysiloxane (B) = 10 / 90-40 /
It is characterized by being 60.

That is, the present inventors have conducted various studies to develop an organopolysiloxane composition which is easily cured by irradiation with ultraviolet rays or electron beams and does not generate a peeling sound even when the peeling force is large. A high polymerization degree and a low acryl content silicone are blended in a specific ratio to the acryl content silicone base. Specifically, the organopolysiloxane (A) represented by the general formula (I) and the organopolysiloxane (A) represented by the general formula (III) are used. When the organopolysiloxane (B) is mixed with the organopolysiloxane (B) in a specific range, the organopolysiloxane is easily cured by irradiation with radiation, and when this is applied to a plastic film and cured by irradiation with radiation, the cured film is formed. It has been found that it shows excellent peeling properties to adhesive substances, and that it does not generate peeling noise even when the peeling force is large. Check the Ukoto has led to the completion of the present invention. This will be described in more detail below.

[0007]

The present invention relates to a radiation-curable organopolysiloxane composition. The radiation-curable organopolysiloxane is represented by the general formula (I) and the general formula (III). The organopolysiloxane (B) shown is combined with the organopolysiloxane (A) / organopolysiloxane (B) = 10 / 90-40.
/ 60 is characterized by being mixed at a weight ratio, the coating obtained by applying the organopolysiloxane composition to a substrate such as a plastic film is easily cured by irradiation with radiation, and the cured coating is It exhibits excellent peelability to adhesive substances, and has the advantage of not generating a peeling sound even when the peeling force is large.

The radiation-curable organopolysiloxane composition of the present invention comprises a mixture of the above-mentioned organopolysiloxane (A) represented by the general formula (I) and the organopolysiloxane (B) represented by the general formula (III). Is done. This organopolysiloxane (A) has the general formula (I)

Embedded image Wherein R ¹ is a hydrogen atom or an atom or group selected from lower alkyl having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, and a butyl group, or a phenyl group. It is preferably a methyl group from the viewpoint of ease of removal and easy release of the adhesive substance.

Further, this R ² is the same atom or group as R ¹ ,
Or the general formula (II)

Embedded image R ³ is a hydrogen atom or a methyl group, and n is 1 to 3
When the group represented by the general formula (II) is less than 0.5% by mole of the organic group bonded to the silicon atom in one molecule, the curability by radiation is significantly reduced,
If this is more than 3.0 mol%, a peeling sound will be generated. Therefore, it is necessary to set this in the range of 0.5 to 3.0 mol%, and furthermore, the average number of silicon atoms in one molecule [a + c]
If (b + 2) + d + 2] is less than 500, a peeling sound is generated, and if it is more than 1,000, the viscosity becomes too high and it becomes difficult to apply this composition to a substrate or the like.
This must be 500 to 1,000, but if the value of c is 4 or more, the viscosity increases during the synthesis and the synthesis becomes difficult, so it should be 0 to 3, preferably 1 to 2. Is good.

The organopolysiloxane (B) used herein has the general formula (III)

Embedded image Wherein R ¹ and R ² are the same atoms or groups as those of the above-mentioned general formula (I), but in the organic group bonded to the silicon atom in one molecule, the general formula (II) When the group represented by the formula (1) is less than 5 mol%, the curability by radiation is remarkably reduced. When the amount is more than 20 mol%, the curability by radiation is improved, but the peeling force of the cured film is significantly increased. This is 5 ~
It is necessary to be within the range of 20 mol%, and furthermore, the average number of silicon atoms present in one molecule [e + g (f + 2) + h
If +2] is less than 50, the curability by radiation will be reduced, and if it is more than 200, the viscosity of the composition will be high, making it difficult to apply it to a substrate or the like, making it impractical. Should be in the range of 200, but this g
Is preferably set to 0 to 1.

The organopolysiloxane composition of the present invention is a mixture of the organopolysiloxane (A) and the organopolysiloxane (B). The organopolysiloxane (A) and the organopolysiloxane (B)
The mixing ratio (weight ratio) of the organopolysiloxane (A) / organopolysiloxane (B) is 10 /
When it is less than 90, the effect of reducing the peeling sound even at heavy peeling during high-speed peeling cannot be obtained, and when it is more than 40/60, the curability by radiation is reduced.
/ 60, but preferably 20
It is preferable to be in the range of / 80 to 30/70.

The above-mentioned organopolysiloxane (A),
The synthesis of the organopolysiloxane represented by the general formulas (I) and (III) constituting (B) is as follows:

Embedded image (Where R ³ is a hydrogen atom or a methyl group, R ⁴ is the same as R ¹ or a group represented by the general formula (II), and L is 0 to 3)
And an organopolysiloxane represented by the general formula:

Embedded image (R ³ is the same as above, m is 3 to 7); and (c) a general formula

Embedded image (R ³ is the same as above, R ⁵ is a group represented by the general formula (II), and P is 3 to 7) cyclic siloxane represented by the following formulas (A), (B), and (C). Using 0.1 to 2.0 parts by weight of CH ₃ SO ₃ H or CF ₃ SO ₃ H as a catalyst with respect to 100 parts by weight of the total amount of the acid, the acid equilibration reaction at a reaction temperature of 80 to 100 ° C. and a reaction time of 4 to 10 hours. Should be performed.

The radiation-curable organopolysiloxane of the present invention can be obtained by mixing the above-mentioned organopolysiloxane (A) and organopolysiloxane (B) within a predetermined range. If necessary, a photoinitiator such as acetophenone, benzophenone, 4-chlorobenzophenone, 4,4-dimethoxybenzophenone, 4-methylacetophenone, benzoin methyl ether, benzoin trialkylsilyl ether, diethylamine ethanol, piperidine, etc. An oxygen curing inhibition inhibitor, a reactive diluent, an organic solvent, a leveling agent, a filler, an antistatic agent, an antifoaming agent, a pigment, and an organopolysiloxane having no radical reactive group may be added.

The radiation-curable organopolysiloxane of the present invention thus obtained can be used as a back surface treatment agent for an adhesive, a protective coating agent for metals and plastics, and a base for paints. Using a bar coater, gravure coater, reverse coater, or spraying on paper, various plastic films, metal foil such as aluminum, or by spraying 0.01 to 200μ
After coating so as to have a thickness of about m, radiation may be applied to the coating to cure the coating.

The radiation includes electron beam, α-ray, β-ray,
Examples include γ-rays or mercury arcs, ultraviolet rays generated from a medium-pressure mercury lamp, and a high-pressure mercury lamp, and the dose for curing the above coating film is 2 to 5 Mrad if it is an electron beam.
In the case of ultraviolet light, a photoinitiator is added to the organopolysiloxane composition and, for example, when a high-pressure mercury lamp of 2 kW (80 w / cm) is used, a distance of 0.1 cm from a distance of 8 cm is used.
Irradiation may be performed for up to 10 seconds.

The radiation-curable organopolysiloxane composition of the present invention has a thickness of about 0.01 to 2.0 μm on the surface of a plastic film such as a polypropylene film, a polyester film or a polyethylene film represented by an OPP film. When the coating is applied as described above and irradiated with the above-mentioned radiation to cure the coating film, the film is formed into a peelable film, and the cured film exhibits excellent peelability, and the peeling force is also high. However, there is an advantage that no peeling noise is generated even if the value is large.

[0017]

EXAMPLES Next, synthesis examples, examples and comparative examples of the organopolysiloxane constituting the organopolysiloxane composition of the present invention will be described. In the examples, parts are parts by weight, and viscosity and refractive index are at 25 ° C. The physical property values in the examples are those measured by the following test methods. (Curability) 1 g / of the organopolysiloxane composition of the present invention
After applying m ² to OPP films, the oxygen concentration is 50ppm
The amount of electron beam irradiation (Mr.) until a fully cured film is obtained when cured by electron beam irradiation under a nitrogen stream as shown below
As shown in ad), the curing was determined when the coated surface did not fall off even when the coated surface was rubbed with a finger and was not cloudy.

(Peeling Force and Peeling Sound) The organopolysiloxane composition of the present invention is cured by irradiating it with an electron beam at the lowest dose at the time of measuring curability, forming a cured film on an OPP film, Paste a hot-melt tape on the cured film surface and let it age at 70 ° C for 24 hours.
Thereafter, the OPP film coated with siloxane was pulled at an angle of 180 ° at a peeling speed of 8 m / min using a tensile tester, and the force (g / 5 cm) required for peeling was measured. Also, the peeling sound was determined by whether or not there was a peeling sound when measuring the peeling force in a quiet constant temperature chamber. This peeling sound was (maximum peeling force-minimum peeling force) / average peeling force = δ, It is represented by the magnitude of the value of δ.

(Residual Adhesion Rate) After forming a cured film of the organopolysiloxane composition on the OPP film in the same manner as in the case of the peel force measurement, a polyester tape Lumirror 31B [trade name of Nitto Denko Corporation] is formed on the surface thereof. And heat-treated at 70 ° C. for 24 hours under a load of 20 g / cm ² , and then the tape was peeled off and attached to a stainless steel plate. Next, the tape was peeled off from the stainless steel plate at an angle of 180 ° at a peeling speed of 300 mm / min, and the force required for peeling (g / 2.5
cm) as well as the force (g / 2.5 cm) required to peel the untreated standard tape from the stainless steel plate, and the force (g / 2.5 cm) required to peel the untreated standard tape. 2.5c
m) as a percentage (%).

(Synthesis example) In a 1-liter four-necked flask equipped with a stirrer, a thermometer, and a Dimroth, the formula was added.

Embedded image (A) 31 parts of an organopolysiloxane represented by the formula:

Embedded image (B) 592 parts of a cyclic dimethylpolysiloxane represented by
And expressions

Embedded image And 310 parts of the cyclic polysiloxane (c) represented by the formula:

Embedded image , And stirred for 5 minutes at room temperature. Thereafter, CH ₃ SO ₃ H as a catalyst was added to the total amount of siloxane.
1.0% by weight, and allowed to undergo an acid equilibrium reaction at a temperature of 90 to 100 ° C. for 6 to 10 hours. After the completion of the reaction, NaHCO ₃ was added in an amount 3 times the amount of CH ₃ SO ₃ H. After performing a neutralization reaction for a period of time, followed by filtration and stripping, the average composition formula shows that each siloxane unit of the organopolysiloxane is

Embedded image D = C18

Embedded image D ^A = Formula 19

Embedded image ^A siloxane (1) represented by M ₃ D ₈₀ DA ₁₈ T when abbreviated as T = CH ₃ SiO _3/2 was obtained in a yield of 90%.

This is a pale yellow transparent liquid having a viscosity of 210 cp, a refractive index of 1.427, and an acryloxy group content of IR,
¹ H-NMR confirmed that the content was 8.7 mol%, which was described in (A), (B) and (C) above.
Except that the ratio of the components was changed, the same treatment was carried out to synthesize the following organopolysiloxanes (2) to (7). Their compositions, degree of polymerization, acrylic group content, viscosity and refractive index are shown in Table 1. It was as shown.

[0022]

[Table 1]

Examples 1 to 5 A radiation-curable organopolysiloxane composition of the present invention is prepared by adding 30 parts of siloxane (3) to 70 parts of siloxane (1) obtained in the above synthesis examples and mixing well. Along with (Example 1), siloxanes (4) to (7) were added to the siloxane (1) obtained in the above Synthesis Example in the amounts shown in Table 2 and mixed, and the radiation-curable organopolysiloxane composition of the present invention was obtained. Products (Examples 2 to 5) were prepared, and their curability, peeling force, residual adhesiveness, and peeling sound were measured. The results were as shown in Table 2 below.

Comparative Examples 1 and 2 The siloxane (1) obtained in the above synthesis example was used alone (Comparative Example 1), and 70 parts of the siloxane (1) and 30 parts of the siloxane (2) were mixed well. Using an organosiloxane composition, curability, peeling force,
When the residual adhesion ratio and the peeling sound were measured, the following Table 2 was obtained.
The result as shown in was obtained.

[0025]

[Table 2]

Example 6, Comparative Examples 3 and 4 To 90 parts of the siloxane (1) obtained in the above synthesis example, 10 parts of the siloxane (5) was added and mixed well, and the radiation-curable organopolysiloxane of the present invention was mixed. Make a siloxane composition,
When the curability, the peeling force, the residual adhesion rate and the peeling sound were measured, the results as shown in Table 3 were obtained. However, for comparison, the mixing amount of the siloxane (1) and the siloxane (5) was 5 parts of the siloxane (5) with respect to 95 parts of the siloxane (1) (Comparative Example 3). ) 50 parts of siloxane (5)
When the same measurement was performed for the part (Comparative Example 4), the results shown in Table 3 were obtained.

[0027]

[Table 3]

Example 7 A radiation-curable organopolysiloxane composition of the present invention comprising 70 parts of siloxane (1) and 30 parts of siloxane (3) prepared in Example 1 has the formula

Embedded image 3 parts of Darocur 1173 (manufactured by Merck) was added to a plastic film of OPP having a thickness of 38 .mu.m using an offset printing machine. And apply N
₂ was under aeration This high pressure mercury lamp ultraviolet from distance 8cm using (80 w / cm) was irradiated for 0.5 seconds to cure it, but peelable film is obtained, examined the physical properties of this product As a result, this had a peeling force of 35 g / 5 cm, and no peeling sound was generated.

[0029]

The present invention relates to a radiation-curable organopolysiloxane composition, as described above, which is represented by the general formula (I) and the general formula (III). The organopolysiloxane (B) is mixed with the organopolysiloxane (A) / organopolysiloxane (B) at a weight ratio of 10/90 to 40/60. The composition is easily cured by irradiation and adheres well to substrates such as plastics.The cured film obtained by curing this composition can easily release the adhesive substance, and the peeling force during high-speed release is high. This has the advantage of exhibiting an effect that no peeling noise is generated even when the size becomes large.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-239526 (JP, A) JP-A-4-36353 (JP, A) JP-A-3-33159 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C08L 83/04 C08F 299/08

Claims (1)

(57) [Claims] 1. A compound of the general formula (I) [Where R ¹ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms or a phenyl group, R ² is the same group as R ¹ or a compound represented by the general formula (I
I) (Where R ³ is a hydrogen atom or a methyl group, n is 1 to 3), and 0.5 to 3.0 mol% of the total organic groups bonded to the silicon atom in one molecule is generally A group represented by the formula (II), wherein c is 0 to 3, a + b × c + d = 500
~ 1000] organopolysiloxane (A)
And the general formula (III) (R ¹ is the same as above, R ² is the same group as R ¹ , or a compound of the general formula (II)
In the group represented by the formula, 5 to 20 mol% of the total organic groups bonded to the silicon atom in one molecule is a group represented by the general formula (II), g is 0 to 3, and e + f × g + h = 50-200)
And an organopolysiloxane (B) as a main component,
The mixing ratio (weight ratio) is organopolysiloxane (A) / organopolysiloxane (B) = 10 / 90-40 /
A radiation-curable organopolysiloxane composition, wherein the composition is 60.