JPS5964669A - Peelable cured film - Google Patents

Abstract

PURPOSE:To provide a peelable cured silicone film having excellent peelability and residual adhesion rate, by mixing an organopolysiloxane contg. a functional group with a linear diorganopolysiloxane and irradiating the mixture with electron beams to introduce a crosslinked structure thereinto. CONSTITUTION:A peelable cured film is composed of a mixture consisting of 50-95pts.wt. organopolysiloxane (A) contg. at least one functional group of formula I (wherein R<1> is H, CH3; R<2> is a 1-10C bivalent hydrocarbon group) attached to an Si atom per molecule and 50-5pts.wt. diorganopolysiloxane (B) having a substantially linear structure and an MW of 50,000-300,000 and composed of a polymer unit chain of formula II (wherein R, R' are each methyl, ethyl, propyl, trifluoropropyl; n is a positive number), and has a crosslinked structure introduced thereinto by the irradiation of electron beams. Since this film contains the high-molecular component B, it has excellent peelability and the crosslinking reaction by the irradiation with electron beams takes place between the molecules of component B contg. no functional group so that there is no possibility that the performance of adhesive is reduced by the transfer of part of the cured film to the adhesive in contact with the surface to be peeled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a silicone-based releasable cured coating having excellent releasability and residual adhesion.

Conventionally, as silicone constituting a peelable cured film formed by heat curing or ultraviolet curing, polysiloxane containing two dialkylsiloxy units such as dimethylsiloxy units has been used to improve peelability. Polysiloxanes containing silicon-bonded vinyl groups or σ-acrylic groups are also used in order to improve curability.Polysiloxanes containing dialkylsiloxy units are used. , the greater the degree of favoritism of the dialkylsiloxy unit, the <
/dj All properties are improved, and in a polysiloxane containing a siloxy unit having a vinyl group or an acryloxy group-substituted alkyl group, the more tjk containing the vinyl group or an acryloxy group-substituted alkyl group, the more the curability improves. However, if the vinyl group- or acryloxy-substituted alkyl group content is increased for the purpose of improving curability as described above, the important release properties will deteriorate. This is because the functional group itself has strong polarity.

This is thought to be due to the fact that the interfacial tension in the peelable cured coating itself improves as the content of functional groups increases.

Maintains high curing properties and obtains sufficient peeling properties.
R-needle is a high-molecular resin silicone rubber that does not contain functional groups such as vinyl groups or acryloxy-substituted alkyl groups.
Although it is effective to apply dialkylorganoborisiloxane to IJU, it has the disadvantage that the silicone rubber itself bleeds over time, as the silicone rubber itself does not crosslink in conventional heat-curing or UV-curing peelable cured coatings. For example, when a release paper having such a releasable cured coating is brought into contact with an adhesive, the silicone rubber is transferred to the adhesive, resulting in a decrease in the residual adhesion rate.

The inventors of this 19th item have conducted intensive research to solve the problems of the conventional sword 1, and as a result, they have succeeded in maintaining high curing properties and obtaining sufficient peeling properties. That is, in the present invention, (a) the general formula C bonded to a silicon atom in one molecule is a hydrogen atom or a methyl group, and I is a carbon number of 1-1.
Organopolysilochitin having at least one functional dance represented by (representing 0 divalent hydrocarbon groups)
50-95 parts by weight) For molecules consisting of a polymerized unit chain represented by the general formula (R, RM in the formula methyl group, ethyl group, propyl group or trifluoropropyl group, n is a positive number) 50,000- 300,000 and has a substantially linear structure (50 to 5 parts by weight), and has a crosslinked structure introduced by electron beam irradiation. According to this, since the crosslinking reaction due to electron beam irradiation also occurs on the (original) component, the disadvantageous phenomenon that (original) components that do not have functional groups bleed over time occurs.
It has the advantage of being a removable cured film with high releasability and a high residual adhesion rate. Furthermore, according to the present invention, the degree of cross-linking reaction can be easily controlled by adjusting the amount of electron beam irradiation, so the elasticity of the cured film can be adjusted.

Peelability: A film with excellent residual adhesion can be formed. Furthermore, since the functional groups of the acrylic thread, which is a polymerization reaction system, are cured using electron beams, the reaction efficiency is significantly improved, and the number of functional groups that have a negative effect on releasability can be significantly reduced. , and since a sensitizer having a polar group is not required, the interfacial tension of the cured film can be lowered, and the releasability is improved.

The present invention will be explained in detail below.

The organopolysiloxane as component (a) used in the present invention must have at least one functional group represented by the general formula fIl in its molecule. This functional group exhibits electron beam polymerizability, and in this case, an acryloxy group where R1 is a hydrogen atom and a metalyloxy group where R2 is a methyl group are divalent hydrocarbon groups. (R2) VC bonded.

This divalent hydrocarbon M (R2) has 1 to 10 carbon atoms.
For example, alkylene groups such as methylene, propylene, tetrabutylene, and arylene groups such as phenylene.

Further examples include those in which the above-mentioned basic halogen atoms are substituted.

(a) The organopolysiloxane as a component has no particular restrictions on its molecular structure as long as it has the above-mentioned functional groups, so it has a linear structure, a branched structure - a cyclic structure,
Alternatively, it may have a three-dimensional structure (reticular structure), and it also has an oil-like appearance.

It may be either rubber-like or resin-like. In addition, the organic group bonded to the silicon atom of this organopolysiloxane (
Functional groups other than the functional groups shown in the general formula CI) are generally mainly methyl groups, but various organic groups may be introduced in addition to the methyl group, and the main Basically, ethyl group, propyl group, butyl group,
Bonded to carbon atoms of alkyl groups such as ogtyl threads, alkenyl groups such as vinyl groups and allyl groups, aryl groups such as phenyl groups and tolyl groups, schizoloalkyl groups such as schizolohexyl groups, and these-valent hydrocarbon groups and methyl groups. A group in which a hydrogen atom is substituted with a /10 hydrogen atom on the moiety y9, such as a halogen-substituted-valent hydrocarbon group such as a trizorolloethyl group, a perfluorovinyl group, a trifluoropropyl group, a parazololotryl group, and a zorollomethyl group, as well as various alkoxy Examples include groups. Further, this organopolysiloxane VC may have a hydroxyl group directly bonded to a silicon atom introduced therein. When the organopolysiloxane has a substantially linear structure, it may have a nitrimethylsilyl group at the end of its molecular chain, a triethylsilyl group, a triphenylsilyl group, a dimethylphenylsilyl group, or the like.

Firstly, (b) the diorganopolysiloxane having a substantially linear structure as one component is represented by the general formula (II) and is composed of the polymerized unit chain strength 1; As mentioned above in the organic group R=R' bonded to an elementary atom, methyl group, ethyl group, and propyl 1-ti are trifluoropropyl groups, but generally at least 60 molar proportions of all organic groups are methyl groups. It is preferable. There is no particular restriction on the structure of both ends of the molecular chain, and for example, it may be any of a hydroxydimethylsilyl group, a vinyldimethylsilyl group-trimethylminolyl group, and the like. Note that this diorganopolysilochitin has a substantially linear structure, but if the amount is small, there is no problem even if the molecular structure has a branched structure, or the above-mentioned organic group (R A certain amount of 81 groups other than -R5 may be bonded.

The diorganopolysiloxane as component (b) must have a molecular weight of 50,000 to 300,000. Molecular weight is 50.00
If the molecular weight exceeds 300,000, the silicone comb will easily bleed out even if a crosslinked structure is introduced by electron beam irradiation, and if the molecular weight exceeds 300,000, the viscosity of the mixture will increase significantly and coating will be difficult.

The physical properties of the desired hardening speed coating are determined by the ratio of the (a) component and the (ol component), but the optimal value is determined individually depending on the ratio of the (a) component to the (ol component); however, if the amount of the component (b) is too small, the release properties On the other hand, if the amount is too large, the curability will be poor. Therefore, the amount of component (B) should be 50 to 5 parts by weight per 50 to 95 parts by weight of component (A). is required.

Peelable hardened coating rc according to the present invention - as described above (
It is produced by coating the surface of a suitable substrate with a mixture of component A) and component J, and irradiating this coating film with an electron beam to cause crosslinking. ((I)
General coating methods such as VCB, roll coating, and gravure coating can be used to coat a mixture of components and (AL) components without a solvent. -7JD A solvent-free lamination coater (Japanese Unexamined Patent Application Publication No. 1983-1983) which has heating metal rolls and rolls coated with rubber or brass tint alternately and a coating head made so that the middle heating metal roll swings. 71
It can be carried out by the fc'/X cloth method using the 662 publication.
Coating is possible up to 25°C.Needless to say, if the viscosity is set to 1,000 to 500 centimeters, it can be applied using a roll coater or a gravure coater.

It can be applied by a general method such as an air coater.

Glassine paper, clay coated paper, high quality paper, polyethylene laminate paper, brass tint film, gold leaf, etc. are used as the base material for the coating. The amount of coating to obtain a peelable cured film is approximately 0.
It may be 5 to 5 g/-.

The surface coated in this way is irradiated with a VC electron beam to cause a crosslinking reaction and a cured film is obtained. At this time, the atmosphere is preferably an inert gas atmosphere such as nitrogen gas.
As the box and the beam irradiation device, a low-energy electron accelerator such as Electrocurtain CB20d50/30 manufactured by Energy Science Industry Co., Ltd. or NP-ESH150 manufactured by Offto Decor Co., Ltd. is used. The amount of electron and electron beams irradiated by these devices is usually 0.5 to 30M.
rad, and the desired cross-linking reaction can sufficiently proceed with this level of irradiation dose.

The peelable cured film of the present invention obtained in this way has excellent peelability because it contains a high molecular weight diorganopolysiloxane, and the crosslinking reaction by electron beam irradiation has a functional group. (b) Since it is also distributed between the molecules of the component (b), it has the characteristic that a part of the cured film will not be transferred to the adhesive in contact with the peeling surface and the performance of the adhesive will not deteriorate. There is.

Next, specific examples will be given.
To 100 parts by weight of metalyl group-containing organoborilyloxane having a viscosity of about 2.000 cm at 5°C, a hydroxyl-terminated dimethylpolysiloxane (component (b)) having a molecular weight of 10,000 or 200,000 is added as a thirteenth component. The amounts shown were added to form a homogeneous mixture.

The above mixture was coated on polyethylene laminated paper to a thickness of 0.
8 to 1.0 g/m', and a low-energy electron accelerator (ElectroCurty CB 20 manufactured by Energy Science Industry Co., Ltd.) in a nitrogen gas atmosphere.
d 50 / 30 ) at a dose of 5 Mrad to form a cured film.

To apply an acrylic adhesive solution on the cured film formed as described above, use Toyo Ink Co., Ltd.'s Olipine BPS5.
After drying, the sample was laminated with polyester, and the sample was slit to a width of 5 Crn, and the peeling performance and residual adhesion rate were examined, and the results shown in Table 1 were obtained. However, the peeling performance was determined according to JIS Z 1523.

Table 1 Example 2 Consisting of 98 moles of dimethylsiloxane units and 2 moles of r-methacyloxypropylsiloxane units, both ends of the molecular chain are blocked with trimethylsilyl groups, and the viscosity at 25°C is about i, 320 parts by weight of a dimethylborisaxane component with a hydroxyl group endblocking molecular chain having a molecular weight of 20,000 molecule was added to 00 parts by weight of a methacrylic group-containing organopolysiloxane of Sensisto-Ges to form a homogeneous mixture.

Coating in the same manner as in the previous example, with an irradiation dose of 1.5 or 10M.
When cured films were formed as rad, their physical properties were as shown in Table 2.

Table 2 =52;

Claims (1)

[Scope of Claims] 1. (a) General formula (in the formula, R1 is a hydrogen atom or a methyl group, and 1A is a divalent group having 1 to 10 carbon atoms in one molecule) 50 to 95 parts by weight of an organopolysiloxane having at least one functional group represented by the following formula (representing a hydrocarbon group): Polymerization unit represented by trifluoropropyl group (ntz positive number), molecular weight 50.000 to 30
A releasable cured coating formed of a mixture of 50 to 5 parts by weight of diorganoborisiloxane having a linear structure having a molecular weight of 0,000 and having a crosslinked structure introduced by electron beam irradiation.