JP3149306B2 - UV curable composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet-curable organopolysiloxane composition capable of forming a cured cured film.

[0002]

2. Description of the Related Art For the purpose of preventing adhesion and sticking between a substrate such as paper, processed paper and plastic film and a pressure-sensitive adhesive substance, it is necessary to form a peelable cured film on the surface of the substrate. Is being done. The substrate on which such a cured film having releasability is formed is generally called release paper.

As a composition for forming a releasable cured film, a curable organopolysiloxane composition which is cured by heat or ultraviolet rays is used. However, from the viewpoint of improving productivity and energy saving, Since some of the substrates on which the cured film is formed have poor heat resistance, a substrate capable of forming the cured film in a low temperature and in a short time is required. In particular, in order to prevent thermal deformation of the substrate, a curable composition that can be cured by ultraviolet irradiation is advantageous.

[0004] As an ultraviolet-curable organopolysiloxane composition, a composition comprising an organopolysiloxane having an epoxy group and an onium salt-based photoinitiator is known (JP-A-56-38350).

[0005]

The above-mentioned ultraviolet-curable organopolysiloxane composition is said to be capable of forming a cured film having excellent releasability from an adhesive substance. However, there is a problem that the peelability of the pressure-sensitive adhesive is unsatisfactory, or the peelability decreases with time. In addition, there is a problem that the releasability is poor because the surface of the cured film has no slipperiness.

[0006] Accordingly, an object of the present invention is to provide a cured film formed by a conventionally known composition which exhibits good releasability even for an adhesive which does not exhibit satisfactory releasability, and which has a problem that the releasability decreases with time. It is an object of the present invention to provide an ultraviolet-curable organopolysiloxane composition capable of forming a cured film free from defects. Another object of the present invention is to provide an ultraviolet-curable organopolysiloxane composition having a cured film surface having good slipperiness and having excellent releasability.

[0007]

According to the present invention, there is provided (A) an organopolysiloxane having an epoxy-containing organic group.
(B) a photoinitiator, (C) non-reactive with the components (A) and (B)And
The following general formula: R ^Two _Three SiO- (R ¹ _Two SiO) _n -SiR ^Two _Three Where R ¹ May be the same or different,
Is unsubstituted al Selected from the group consisting of a kill group and an aryl group
Is the chosen group, R ^Two May be the same or different
, Hydroxyl, alkoxy, aryl Roxy group, substitution
Or a group consisting of unsubstituted alkyl and aryl groups R
Group selected n is a positive integer, represented by
With a viscosity at 25 ° C in the range of 50 to 1,000,000 cP
 Organopolysiloxane[However, both ends are (OH) R ^Two _Two
SiO _1/2 Unit (where R ^Two Are the same or different
Often an unsubstituted alkyl or unsubstituted aryl group
is there. ) With a viscosity of 30,000 cP or less at 25 ° C
The lower organopolysiloxane, and the OH group-containing
Kill group, OH group-containing cycloalkyl group or OH group-containing
At 25 ° C with at least two aryl groups per molecule
Alcohol modified with a viscosity of 30,000 cP or less
Excludes phenol-modified organopolysiloxane. ],
Is provided.

Component (A) In the present invention, the component (A) is a base component, and an organopolysiloxane having an epoxy group-containing organic group is used. The epoxy group-containing organic group exhibits photocurability, and typical examples thereof include those represented by the following formulas (1a) to (1d).

[0009]

Embedded image In the above formula, Q ¹ is a linear or branched divalent hydrocarbon group, and Q ² is a hydrogen atom or a lower alkyl group.

Among the above formulas (1a) to (1c), the following epoxy group-containing organic groups are particularly preferred.

Embedded image

[0011] Epoxy group-containing organic groups described above are those present bonded to a silicon atom, for example, the following formula (2): in _{R a E b SiO (4-} ab) / 2 (2) formulas, R An unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, E is the aforementioned epoxy group-containing organic group, a
Is an integer of 0 to 2, b is an integer of 1 to 3,
a + b ≦ 3, which is present in the organopolysiloxane as a structural unit represented by the formula:

In the above formula (2), the monovalent hydrocarbon group R
Examples of the group include an alkyl group such as a methyl group, an ethyl group, a propyl group, and a butyl group; a cycloalkyl group such as a cyclohexyl group; an aryl group such as a phenyl group and a tolyl group; Examples thereof include a group substituted with a group, a cyano group, and a halogen atom, such as a hydroxypropyl group, a cyanoethyl group, a 3-chloropropyl group, and a 3,3,3-trifluoropropyl group.

The organopolysiloxane may have a linear, branched, or cyclic structure as long as it has an epoxy group-containing organic group.
Is from 0.01 to 0.3 with respect to all siloxane units.
(Molar ratio) is preferable in that a cured film exhibiting excellent releasability from the adhesive substance is formed.

In the present invention, typical examples of the above-mentioned organopolysiloxane of the component (A) are not limited thereto, but those represented by the following formulas can be exemplified. They can be used alone or in combination of two or more. In the following formula, Me is a methyl group, Ph is a phenyl group, E is the epoxy group-containing organic group described above, and w, x, y, and z each represent a positive integer.

[0015]

Embedded image

Component (B): As the component (B), which is a photoinitiator, those known per se can be used, and onium salt-based photoinitiators can be particularly preferably used. As the onium salt photoinitiator, for _{^{example, R 3 2 I + X -}} , R 3 3 S + X -, R 3 3 Se + X
_{^{-, R 3 4 P + X}} -, R 3 N 2 + X - (R 3 is an aryl group, X ^- is SbF ₆ ^-, AsF ₆ ^{-,
_{PF 6 -, BF 4 -,}} HSO 4 -, ClO 4 - diaryliodonium salts ,, triarylsulfonium salt represented by the formula of the anion is a) or the like such as, triarylselenonium salt, tetraarylphosphonium salt, aryl Examples include diazonium salts.

The photoinitiator of the component (B) is generally used in an amount of 0.01 to 20 parts by weight, preferably 0.5 to 20 parts by weight, per 100 parts by weight of the component (A).
Used in an amount of 10 parts by weight. If the amount is too small, the ultraviolet curability will be insufficient, and if it is too large, the surface state of the cured film will be adversely affected and the releasability will tend to decrease.

The component (C); in the present invention, in addition to the aforementioned components (A) and (B), using these components and non-reactive to the following organopolysiloxane as the component (C). The non-reactive organopolysiloxane gives the cured film a lubricating property and also improves the releasability of various adhesive substances.

[0019] The non-reactive organopolysiloxane down is,
Under following general formula (3): in ^{_{R 2 3 SiO- (R 1 2}} SiO) n -SiR 2 3 (3) formula, R ¹ is may be the same or different, substituted or unsubstituted alkyl group and A group selected from the group consisting of aryl groups, wherein R ² may be the same or different and is selected from the group consisting of a hydroxyl group, an alkoxy group, an aryloxy group, a substituted or unsubstituted alkyl group and an aryl group. Wherein n is a positive integer, and has a viscosity at 25 ° C. in the range of 50 to 1,000,000 cP.
Organopolysiloxane was prepared in which both ends (OH) R ^{₂ 2}
SiO _1/2 units (where R ² is the same or different
Often an unsubstituted alkyl or unsubstituted aryl group
is there. ) With a viscosity of 30,000 cP or less at 25 ° C
The lower organopolysiloxane, and the OH group-containing
Kill group, OH group-containing cycloalkyl group or OH group-containing
At 25 ° C with at least two aryl groups per molecule
Alcohol modified with a viscosity of 30,000 cP or less
Excludes phenol-modified organopolysiloxane. 〕so
There is .

In the general formula (3), R ¹ represents a linear alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group; a cycloalkyl group such as a cyclohexyl group; an aryl group such as a phenyl group or a tolyl group. Groups, and at least some of the hydrogen atoms in these groups are hydroxy groups,
A group substituted with a cyano group, a phenyl group, a halogen atom or the like, for example, a hydroxypropyl group, a cyanoethyl group, a 2-phenylethyl group, a 2-phenyl-2-methylethyl group, a 3-chloropropyl group, Examples thereof include a 3-trifluoropropyl group. Among them, those having 1 to 12 carbon atoms are preferable. Also R
It is preferable that 0.5 to 30 mol% of ^one group is an aryl group. When the content of the aryl group is out of this range, when the pressure-sensitive adhesive layer is provided to face the cured film, the properties of the pressure-sensitive adhesive may be adversely affected.

R ² is a hydroxyl group, an alkoxy group, an aryloxy group, an unsubstituted or substituted alkyl group and / or
Or an aryl group, preferably a hydroxyl group, an alkoxy group, or an unsubstituted or substituted alkyl group exemplified for R ¹ .

The organopolysiloxane is 25
Because the viscosity at ℃ is in the range of 50-1,000,000 cP,
n is a positive integer that provides such a viscosity. If the viscosity is smaller than the above range, there is a tendency that good releasability from the pressure-sensitive adhesive is not exhibited. If the viscosity is larger than the above range, the compatibility with the component (A) becomes poor,
The components (A) and (C) tend to separate.

The non-reactive organopolysiloxane of the component (C) is used in an amount of 0.5 to 50 per 100 parts by weight of the component (A).
It is preferably used in an amount of parts by weight, more preferably in an amount of 1 to 20 parts by weight. If the amount is too small, the desired peeling effect cannot be obtained. If the amount is too large, the component may migrate to the adhesive substance and deteriorate its properties.

Preparation of the curable composition; The composition of the present invention comprises
It is obtained by uniformly mixing predetermined amounts of the above-mentioned components (A) to (C), but as long as the object of the present invention is not impaired, a polyol-based reaction accelerator, an epoxy-based diluent, a vinyl ether-based diluent, Known additives such as an adhesion improver to a substrate, a leveling agent, an antistatic agent, an antifoaming agent, and a pigment can be blended as necessary.

Curable composition: The composition of the present invention is easily cured by short-time ultraviolet irradiation. As the ultraviolet light source, a mercury arc lamp, a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, or the like can be used.

The formed cured product has good releasability from various pressure-sensitive adhesives, and the releasability is extremely small with time. Therefore, the ultraviolet-curable composition of the present invention is used by applying it to various substrates as a release agent for a so-called release paper for an adhesive. The substrate of the release paper to which the composition is applied is not particularly limited, for example,
Paper substrate such as glassine paper, kraft paper, clay coated paper, etc., laminated paper such as polyethylene laminated high quality paper, polyethylene laminated kraft paper, polyester,
The present invention can be applied to a plastic film or sheet obtained from a synthetic resin such as polypropylene, polyethylene, polyvinyl chloride, polytetrafluoroethylene, and polyimide, and a metal foil such as aluminum.

In order to apply the composition of the present invention to the above-mentioned substrate, known methods such as roll application, gravure application, wire doctor application, air knife application, dipping application, etc. can be used. In consideration of the above, it is of course possible to appropriately dilute and apply the solvent. Usually, the coating amount is suitably in the range of 0.1 to 200 g / m ² . The coating may be cured by irradiating from a distance of 8 cm for 0.01 to 10 seconds, for example, using a high-pressure mercury lamp (80 W / cm).

The curable composition of the present invention may be used as a release agent as described above, for example, a protective coating agent for various metals and plastics; a base for paints; a release agent for rubber and plastics; Can be effectively applied to applications such as water repellency and oil repellent.

[0029]

EXAMPLES In the following specific examples, "parts" means "parts by weight" and viscosities represent values measured at 25 ° C.

Example 1 The following average composition formula:

Embedded image E: epoxy group-containing organopolysiloxane represented by β- (3,4-epoxycyclohexyl) ethyl group
00 copies,

[0031]

Embedded image Ph: 5 parts of a non-reactive organopolysiloxane represented by a phenyl group (viscosity: 6000 cP) and 2 parts of an iodonium salt photoinitiator were mixed to prepare a curable composition. The peeling force, residual adhesion rate, and dynamic friction coefficient of a cured film formed using this curable composition were measured by the following methods. Table 1 shows the results
Shown in

Peeling force: The curable composition was applied to the surface of a high-quality polyethylene-laminated paper using an offset transfer machine at a solid content of 0.8 g / m ² using a high-pressure mercury lamp of 80 W / cm for a distance of 8 cm. To form a cured film.
On the surface of this cured film, a natural rubber-based solvent-type adhesive BPS-2411
(Manufactured by Toyo Ink Manufacturing Co., Ltd.) and heat-treated at 100 ° C. for 3 minutes. Next, a high-quality paper with a basis weight of 64 g / cm ² is stuck on the treated surface, the sample is cut into 50 mm widths, and left to stand at 20 ° C. for 24 hours or 70 ° C. for 48 hours to age. The paper was peeled at a peeling speed of 0.3 m / min at an angle of 180 ° using a tensile tester, and the force required for peeling (g / g)
50 mm).

Residual adhesion ratio: A cured film of the silicone composition was formed on the surface of the substrate in the same manner as in the case of the peel force measurement. A polyester adhesive tape 31B (manufactured by Nitto Denko Corporation) was adhered to the surface, and aged at 70 ° C. for 20 hours under a load of 20 g / cm ² . After this aging, the adhesive tape was peeled off and affixed to a polyester film. Then
The pressure-sensitive adhesive tape was peeled from the polyester film at an angle of 180 ° at a peeling speed of 0.3 m / min, and the force F (g / 25 mm) required for peeling was measured. For the untreated pressure-sensitive adhesive tape not bonded to the cured film, the force F ₀ (g / 25 m
m) was measured. The residual adhesion rate (%) was calculated by the following equation. Residual adhesive strength = (F / F ₀ ) × 100

Coefficient of dynamic friction; A cured film of the silicone composition was formed on the surface of the substrate in the same manner as in the measurement of the peeling force. This was affixed to a glass plate and supported horizontally with the cured film surface facing up. On the other hand, the substrate on which the cured film was formed was also attached to the bottom surface of a 200 g weight so that the silicone surface was facing down. A weight was placed on a horizontally supported cured film, and the force required to pull in the horizontal direction at a speed of 0.3 m / min was measured to determine the dynamic friction coefficient.

Example 2 100 parts of the same epoxy group-containing organopolysiloxane used in Example 1, the following average composition formula:

[0036]

Embedded image A non-reactive organopolysiloxane (viscosity:
(60,000 cP) and 5 parts of an iodonium salt photoinitiator were mixed to prepare a curable composition. The peeling force, the residual adhesion rate, and the dynamic friction coefficient of the cured film formed using this curable composition were measured in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 A curable composition was prepared in exactly the same manner as in Example 1 except that no non-reactive organopolysiloxane was used. The peeling force, the residual adhesion rate, and the dynamic friction coefficient of the cured film formed using this curable composition were measured in the same manner as in Example 1. Table 1 shows the results.

[0038]

[Table 1] Peeling force (g / 50mm) Residual adhesion rate Dynamic friction coefficient 20 ° C / 24 hours 70 ° C / 48 hours (%) ───────────────────── ────────────── example 1 36 40 92 0.25 real施例2 12 13 82 0.21 Comparative example 1 117 188 96 0.42

[0039]

According to the ultraviolet curable composition of the present invention,
A cured film exhibiting good releasability to various pressure-sensitive adhesives and having a very small decrease in releasability due to aging can be formed. This composition is very effectively applied as a so-called release agent to applications such as release paper.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // C09J 7/02 C09J 7/02

Claims (1)

(57) [Claims] 1. An organopolysiloxane having an epoxy group-containing organic group (A).
Ganopolysiloxane, (B) photoinitiator, (C) non-reactive with components (A) and (B)And
The following general formula: R ^Two _Three SiO- (R ¹ _Two SiO) _n -SiR ^Two _Three Where R ¹ May be the same or different,
Is unsubstituted al Selected from the group consisting of a kill group and an aryl group
Is the chosen group, R ^Two May be the same or different, and a hydroxyl group, an alcohol
Xy group, Ally Roxy group, substituted or unsubstituted alkyl
A group consisting of aryl and aryl groups Group selected
And n is a positive integer; The viscosity at 25 ° C ranges from 50 to 1,000,000 cP.
It is in Organopolysiloxane[However, both ends are (O
H) R ^Two _Two SiO _1/2 Unit (where R ^Two Are the same but different
An unsubstituted alkyl group or unsubstituted
A group. ) With a viscosity of 30,0 at 25 ° C
An organopolysiloxane not exceeding 00 cP and an OH group
Containing alkyl group, cycloalkyl group containing OH group or O
Has at least two H group-containing aryl groups in one molecule
Alcohol conversion with a viscosity at 25 ° C of 30,000 cP or less
Excludes functional or phenol-modified organopolysiloxanes
Good. ]An ultraviolet-curable composition comprising: