JPH11106703A - Coating composition for release paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition for release paper whose releasing ability is adjustable with ease from low to high ability. SOLUTION: This releasing coating composition comprises (1) a butadiene polymer having at least two alkenyl groups and/or a modified polybutadiene comprising a butadiene polymer main chain having at least two alkenyl groups and an organosilicon group bonded to the main chain via C-Si bonding, (2) an organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to a silicon atom in an amount such that a (SiH/alkenyl) molar ratio is in a range of 0.5 to 50 and (3) an addition reaction catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition for release paper, and more particularly, to a coating composition for release paper formed by forming a cured film of a thermosetting organopolysiloxane composition on a substrate surface.

[0002]

2. Description of the Related Art Conventionally, a cured film of a thermosetting organopolysiloxane composition is formed on the surface of a base material such as paper or plastic film, thereby facilitating the separation of the base material from the adhesive substance, Prevention of adhesion between materials has been performed. The organopolysiloxane composition used in this case is classified into, for example, an addition reaction type and a condensation reaction type according to the curing reaction mechanism.

[0003] A cured silicone film originally has a property of easily releasing an adhesive substance, and these are suitable for those having a relatively small release force such as an adhesive label, tape, wallpaper, copy paper and the like. is there. However, in a field such as process paper that requires controlled release properties (the release force is not too small), its use is severely restricted, and practical use is difficult. Furthermore, it may not be suitable for applications requiring heavy peeling.

In order to solve the above-mentioned problems, condensation-reactive organopolysiloxanes are prepared by adding a siloxane-soluble resinous substance (Japanese Patent Application Laid-Open No. 49-1979).
8527), those obtained by modifying silicone with an alkyd resin or a melamine resin (Japanese Patent Publication No. 61-13507).
Although these compositions are known, these compositions are inferior in curability and have a disadvantage that the resulting film is inferior in residual adhesion and blocking resistance.

[0005] Further, as a method of heavy release in an addition reaction type organopolysiloxane composition, there are (1) H / V
increase i (ratio of hydrogen atom to vinyl group), (2)
There are methods such as using a release control agent. However, in the case of the above method (1), there is a problem that the temporal change of the peeling force is large, and in the case of the method (2), S
iO ₂ unit and (CH ₃ ) SiO _1/2 unit
86985) or CH ₂ ＣＨCH (CH ₃ ) SiO
Method using resin with _1/2 unit (Japanese Patent Publication 5-5)
3183) and a method using a long-chain alkyl ester siloxane (Japanese Patent Publication No. 6-72207) have also been proposed, but as the amount of addition increases, the curability decreases, the migration property increases, and the adhesive strength decreases. There was a problem of letting it.

[0006]

The inventors of the present invention have conducted intensive studies to improve the above-mentioned drawbacks, and as a result, by incorporating a butadiene-based polymer, a known peelable composition cannot be obtained. Thus, a coating composition for release that can easily have heavy release properties has been completed. Accordingly, a first object of the present invention is to provide a coating composition for release which can easily adjust the release force from a light release force to a heavy release force. A second object of the present invention is to provide a release coating composition having heavy release properties and non-slip properties, and having both high residual adhesive strength and non-migration properties.

[0007]

The above objects of the present invention are achieved by (1) a butadiene-based polymer having at least two alkenyl groups and / or a butadiene-based polymer having at least two alkenyl groups. In the main chain of C-Si
(2) a polybutadiene derivative having an organosilicon group bonded through a bond, (2) an organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms in one molecule, and having a molar ratio (SiH / alkenyl group) of Achieved by a coating composition for release paper, characterized in that it comprises an amount in the range of 0.5-50 and (3) an addition reaction catalyst.

Hereinafter, the coating composition for release paper of the present invention will be described in detail. First, the butadiene polymer having at least two alkenyl groups, which is the first component used in the present invention, has a number average molecular weight of 500.
-1,000,000 butadiene-based polymer or copolymer, with polybutadiene being particularly preferred as the butadiene-based polymer. As monomers other than butadiene, styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, Glycidyl methacrylate, α-chloroacrylonitrile, acrylamide,
Vinyl isobutyl ether, vinyl acetate, vinyl chloride,
Examples thereof include vinylidene chloride, methyl vinyl ketone, 2-vinyl pyridine, 9-vinyl carbazole, ethylene, and propylene, and two or more of these may be used simultaneously.

The polybutadiene derivative having an organosilicon group bonded via a C-Si bond to the main chain of the butadiene polymer having at least two alkenyl groups used in the present invention has at least three alkenyl groups. It is easily obtained by reacting a butadiene polymer with an organosilicon compound having at least one hydrogen atom directly bonded to a silicon atom in one molecule.

As the above-mentioned organosilicon group, those represented by the following chemical formulas 4 to 6 are preferable.

Embedded image However, n in Chemical formula 4 represents 0 or a positive integer, and R ¹ ,
R ² , R ³ , R ⁴ and R ⁵ represent the same or different organic groups having no aliphatic unsaturated group.

Embedded image However, p and q in Chemical formula 5 represent 0 or a positive integer, and do not become 0 at the same time. R ¹ , R ² , R ³ , R ⁴ , R
⁵ , R ⁶ and R ⁷ represent the same or different organic groups having no aliphatic unsaturated group.

Embedded image However, r in Chemical formula 6 represents a positive integer of 2 or more, and R ¹ , R
² , R ³ represent the same or different organic groups having no aliphatic unsaturated group.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , which are the same or different unsubstituted hydrocarbon groups,
R ⁷ is an aryl group such as a methyl group, an ethyl group, a propyl group, a butyl group, and an octyl group; and a part of a hydrogen atom bonded to a carbon atom of the alkyl group or the aryl group is a halogen atom, Examples thereof include a group substituted with a cyano group or the like. Among these organopolysiloxanes, those having a relatively low degree of polymerization, for example, those having 20 or less silicon atoms are preferred because of their easy synthesis.

The alkenyl group to be contained may be any one capable of hydrosilylation, and specific examples thereof include a vinyl group, an allyl group and an isopropenyl group. The content of the alkenyl group is from 0.2 mol% to 100 mol%, preferably 2 mol%, in the butadiene polymer.
To 30 mol%.

Suitable butadiene copolymers that can be used in the present invention include, for example, 1,2-polybutadiene, butadiene having 1,2- and 1,4-bonds,
1,2-polybutadiene / polyisoprene copolymer,
1,2-polybutadiene / methyl acrylate copolymer,
Examples include 1,4-polybutadiene / 1,2-polyisoprene copolymer. These butadiene copolymers may be used alone or in combination.

The polymerization at the time of the production of the butadiene copolymer can be carried out by a known anionic polymerization method or anion living polymerization method. These butadiene-based polymers having an alkenyl group are commercially available, and examples of polybutadiene include R-15HT,
R-45HT (all trade names made by Idemitsu Petrochemical Co., Ltd.), Nisso PB (trade name made by Nippon Soda Co., Ltd.), Polyoil (trade name made by Nippon Zeon Co., Ltd.)
And the like. Examples of polyisoprene include Poly
ip (trade name of Idemitsu Petrochemical Co., Ltd.) is exemplified.

A preferable derivative of the above-mentioned butadiene copolymer is polybutadiene or a copolymer mainly composed of butadiene to which an organosilane or an organopolysiloxane represented by R ₃ SiH is added. No. 13377, Derivatives described in Columns 3 to 6 (where R is the same or different, substituted or unsubstituted, monovalent hydrocarbon group having no aliphatic unsaturated bond),

A derivative obtained by further adding an isocyanate compound having two isocyanate groups in one molecule to a hydroxyl group of the above derivative or a hydroxyl group regenerated by a hydrolysis reaction of the above derivative (Japanese Patent Publication No. Sho.
No. 5-19250, columns 3 to 7), a hydroxyl group bonded to both ends of the molecular chain of a polybutadiene or a copolymer mainly composed of butadiene, or a hydroxyl group introduced by copolymerization or the like, in one molecule. Is reacted with an isocyanate compound having two isocyanate groups, followed by an addition reaction of the aforementioned organosilane or organopolysiloxane represented by R ₃ SiH (Japanese Patent Publication No.
No. 19250, columns 3 to 7),

A polybutadiene derivative having at least two hydroxyl groups in a molecule of a polybutadiene or a copolymer mainly composed of butadiene and an organopolysiloxy group bonded to a carbon atom in the molecule by a C-Si bond (Japanese Patent Publication No.
No. 5-23579, columns 3 to 6) and the like.

The organohydrogenpolysiloxane as the second component in the coating composition for release paper of the present invention must contain at least two hydrogen atoms directly bonded to silicon atoms in the molecule. This may be linear, branched or cyclic. Specifically, α, ω-bis (dimethylhydrogensiloxy) polydimethylsiloxane, α, ω-bis (trimethylsiloxy) polymethylhydrogenpolysiloxane, α, ω-bis (trimethylsiloxy) poly (methylhydrogen) A (dimethyl) siloxane copolymer is exemplified. The amount of addition was (SiH / alkenyl group) (the amount of hydrogen atoms directly connected to silicon atoms / the amount of alkenyl groups) in a molar ratio of 0.1 to the first component and a fourth component described later.
And the amount is preferably 1.5-4.
The amount is such that it becomes zero.

As the addition reaction catalyst, which is the third component of the coating composition for release paper of the present invention, a noble metal catalyst is suitable. Examples of such a catalyst include platinum black, chloroplatinic acid, chloroplatinic acid-olefin complex, and rhodium complex. These are the first
The amount of platinum or rhodium is usually 5 to 1,000 ppm (weight ratio) based on the total amount of the component and the second component. The amount used can be increased or decreased as appropriate.

In the present invention, from the viewpoint of controlling the peeling force, it is possible to include, as a fourth component, polydimethylsiloxane having two or more alkenyl groups directly bonded to siloxane in one molecule. An alkenyl group directly bonded to siloxane in one molecule as the fourth component is 2
The polydimethylsiloxane having at least two polydimethylsiloxanes must contain at least two alkenyl groups directly bonded to silicon atoms in the molecule, which may be linear, branched, or cyclic. Is also good.

Specific examples of the organovinylsiloxane that can be used as the fourth component include α, ω-
Bis (dimethylvinyl) polydimethylsiloxane, α,
ω-bis (trimethylsiloxy) polymethylvinylpolysiloxane, α, ω-bis (trivinylsiloxy) polymethylvinylpolysiloxane, α, ω-bis (dimethylvinylsiloxy) poly (methylvinyl) (dimethyl) siloxane Coalescence and the like.

The composition of the present invention can be obtained by mixing a predetermined amount of the first to third or first to fourth components. If necessary, for example, a reaction control agent, a photopolymerization initiator, , Silica, colloidal silica, and other inorganic fillers or pigments. In actual use of the composition of the present invention, for example, the composition prepared as described above, as it is or after diluting it uniformly with an appropriate organic solvent, roll coating, reverse coating or gravure coating The substrate is coated with 0.05 to 5 g / m ² by using a coating method such as
By heating at 0 ° C. for 5 to 60 seconds and / or irradiating with ultraviolet rays (for example, 80 w / cm × 2 lamps) for 0.1 to 2 seconds, a cured film having an arbitrary peeling force can be obtained.

[0023]

The release coating composition of the present invention comprises:
Compared with a conventionally known coating agent for release paper, it has the following features. 1. By adjusting the content of the butadiene-based polymer, the release level can be easily controlled. 2. In a pressure-sensitive adhesive tape, when the package is actually packed and the package is stacked, the silicone resin layers for the release paper of the present invention come into contact with each other, but since the butadiene-based polymer is contained, the friction coefficient is increased. There is no slippage and there is no risk of cargo collapse.

[0024]

The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited by these examples. In addition, all parts in each example are parts by weight, and the viscosity is a value at 25 ° C. In addition, the curability, peeling force, transferability, and residual adhesion of the silicone composition were measured by the following methods.

The silicone composition is applied to a curable polyethylene laminated paper at a solid content of about 0.6 g / m ² and heated in a hot air dryer at 140 ° C. for a predetermined time, and the formed cured film is applied several times with a finger. I checked it.

[0026] The peel strength silicone composition by a predetermined amount applied to a polyethylene laminated paper, after forming a cured coating by heating in 140 ° C. hot air dryer for 30 seconds, subjected to 1 day aging under conditions of 25 ° C. Then, a polyester tape (trade name: No. 31B, manufactured by Nitto Denko Corporation) and a PVC tape (trade name: TESA7475 tape, manufactured by BDF) were bonded to the cured coating, respectively, at 25 ° C. for 24 hours at 20 g / cm ² . The force required for pulling the tape bonded together at an angle of 180 ° and a peeling speed of 0.3 m / min was measured, and the force required for peeling was measured.

Residual adhesion ratio In the same manner as in the case of measuring the peeling force, a polyester tape (trade name 31B, manufactured by Nitto Denko Corporation) is adhered to the surface of the cured film of the silicone composition formed on the surface of the polyethylene laminated paper, and 20 g After heating and aging at 70 ° C. for 20 hours under a load of / cm ² , the tape was peeled off and attached to a stainless steel plate. Next, this tape was removed from a stainless steel plate at an angle of 180 ° and a peeling speed of 0.3 m.
The force required to peel and peel was measured at / min, and these ratios were taken and expressed as a percentage.

After a cured film of the composition was formed on the surface of the polyethylene-laminated paper in the same manner as in the slipperiness peel test, 200 μm was formed on the surface.
g of a styrene-butadiene rubber loaded with a load of 0.3 g, and the force (g) required when the rubber was pulled in parallel with the silicone surface at 0.3 m / min was measured.
200 was calculated as the dynamic friction coefficient (ASTM-D-1).
894-63).

Embodiments 1-4. Idemitsu Petrochemical Co., Ltd., which has methyl hydrogen polysiloxane (hereinafter referred to as siloxane A) represented by the following chemical formula 7 and has hydroxyl groups at both ends and an average of 52 butadiene units, of which 10 units are 1.2 vinyl units. ) R-45HT (trade name) 1/9, 3
/ 7, 5/5, and 7/3, respectively, and 0.02 part of 2-methyl-2-trimethylsiloxy-3-butyne (MTMSB) as a control agent and 19 parts of hexane were added to R-
45 HT and 1 part of siloxane A in total, and a complex of platinum and vinyl siloxane was added to the solid content (siloxane A + R-45HT) at 333 pp in terms of platinum.
m and uniformly mixed to prepare treatment baths A, B, C and D shown in Table 1.

Embedded image

[Table 1]

The results of coating the composition in each treatment bath on polyethylene laminated paper with a # 14 wire bar were as shown in Table 2.

[Table 2]

Examples 5 to 8, Comparative Example 1 The viscosity in a 30% toluene solution was 10,000 cp.
30% solution of α, ω-bis (trivinylsiloxy) polysiloxane in toluene containing 0.5 mol% of vinyl (Vi) groups and capped with trivinyl units
Part, methylhydrogenpolysiloxane having a molecular weight of 6446 (hereinafter referred to as siloxane B)
65 parts, and 0.80 part of 2-methyl-2-trimethylsiloxy-3-butyne as a control agent, were added to toluene 68.
The silicone composition 1 was obtained by uniformly dissolving in 55 parts (H / Vi = 3.0).

Embedded image

Separately, both terminals are hydroxyl groups and contain an average of 52 butadiene units, of which 10 are vinyl 1.2
The above-mentioned RT-45H manufactured by Idemitsu Petrochemical Co., Ltd.
Composition 2 was obtained by dissolving 17.7 parts of T and 12.3 parts of siloxane A in 70 parts of hexane.
Vi = 3.0).

Composition 1 and composition 2 were 100 / 8.5, 1
00 / 16.9, 100 / 50.7, 100 / 84.9
And hexane is added so that the concentration of the solid matter becomes 5%. Further, the complex of platinum and vinyl siloxane is adjusted to 333 ppm in terms of platinum with respect to the solid content (siloxane + R-45HT). And the treatment baths E, F, G, and H shown in Table 3 were adjusted.

[Table 3] Further, as a comparative example, a treatment bath I having a solid content of 5% was prepared by adding a platinum catalyst in the same manner using only composition 1.

Table 4 shows the results of coating each of these compositions on polyethylene laminated paper using a # 14 wire bar.

[Table 4]

Embodiments 9-11. Comparative Examples 2-5. Viscosity in a 30% solution of toluene is 10,000 cp
30 parts of a 30% solution of a polysiloxane containing 1.5 mol% of vinyl groups and having terminals capped with vinyldimethylsiloxy units, 30 parts of toluene, 0.62 part of siloxane A, and
2-Methyl-2-trimethylsiloxy- as control agent
Silicone composition 3 was obtained by uniformly dissolving 0.80 part of 3-butyne in 68.58 parts of toluene (S
iH / Vi = 1.57).

Separately, both terminals are hydroxyl groups and contain 36.8 isoprene units, of which 7.
Pol with four vinyl groups manufactured by Idemitsu Petrochemical Co., Ltd.
yip (trade name) 23.3 parts and siloxane A 6.7
Part and 2-methyl-2-trimethylsiloxy-3-
Composition 4 was obtained by dissolving 0.77 part of butyne in 70 parts of toluene (SiH / Vi = 1.57).

For comparison, M units / Q units (molar ratio) =
A 30% toluene solution of a toluene-soluble polysiloxane consisting of 1.15 / 1 M units and Q units was prepared. This is designated as composition 5. 9 / composition 3 and composition 4
1, 8/2 and 6/4 are mixed at a solid concentration of 5
% Of hexane, and the complex of platinum and vinyl siloxane was added to the solid content in 333 p.
pm, and the treatment baths J, K, and L were adjusted.

Further, as a comparative example, only the composition 3 was used, and a platinum catalyst was similarly added to the treatment bath M having a solid content of 5%.
Was adjusted. Further, the composition 3 and the composition 5 were mixed at 9/1, 8 /
Hexane was added at a ratio of 2, 6/4, and hexane was added so that the solid concentration became 5%. Further, a complex of platinum and vinylsiloxane was added so that the solid content was 333 ppm in terms of platinum. , Treatment baths N, O and P were adjusted.

The compositions of the treatment baths J to P are as shown in Table 5.

[Table 5]

The results of coating these compositions with polyethylene wire paper using a # 14 wire bar are shown in Table 6.

[Table 6]

Examples 12, 13 and Comparative Example 6. In a 1000 ml flask equipped with a stirring blade, a reflux tube, and a thermometer, 56 g (0.020 mol) of R45HT and 51.5 g of an organohydrogenpolysiloxane represented by the following formula 9 were added.
g (0.060 mol), 294.7 g of toluene, and 3.8 g of a 0.5% toluene solution of a vinylsiloxane complex of chloroplatinic acid were charged and reacted in a toluene reflux tube for 8 hours. Thereafter, toluene was removed under reduced pressure to quantitatively obtain a brown transparent liquid.

Embedded image

This compound was confirmed by NMR to have 2.8 of the ten terminal alkenyl groups in the R-45HT molecule reacted with Si-H as shown in the following structural formula. Was done. This is designated as PB-Si1.

Embedded image

Further, the same operation was repeated using 77.2 g (0.060 mol) of the organohydrogenpolysiloxane of the following formula 11 to obtain a brown liquid.

Embedded image This compound was confirmed by NMR to have a structure represented by the following chemical formula (12).

Embedded image This is designated as PB-Si2.

An organohydrogenpolysiloxane represented by the following structural formula (hereinafter referred to as siloxane C)
8.0 g, 5.1 g of the PB-Si 1, 0.050 g of ethynylcyclohexanol as a control agent, and 0.5% of a vinylsiloxane complex of chloroplatinic acid in terms of platinum
0.42 g of the toluene solution was mixed uniformly, and treated bath Q
(Example 12) was prepared. Further, a processing bath R (Example 13) was prepared in the same manner except that 11.21 g of the PB-Si 2 was used instead of PB-Si 1.

Embedded image

As a comparative example, 37.23 g of vinylsiloxane (siloxane D) represented by the following structural formula, 1.00 g of organohydrogenpolysiloxane (hereinafter referred to as siloxane D), ethynylcyclohexanol (ECH) as a control agent A treatment bath S was prepared by uniformly mixing 0.11 g and 0.96 g of a 0.5% toluene solution of a chloroplatinic acid vinylsiloxane complex in terms of platinum. This is referred to as Comparative Example 6.

Embedded image

The compositions of the treatment baths Q, R and S are as shown in Table 7.

[Table 7]

[0047] The Q, R, using the processing bath S, the result obtained by applying a polyethylene laminated paper by R ¹ tester are as shown in Table 8.

[Table 8] As shown in the above Examples and Comparative Examples, according to the present invention, it is possible to easily produce a coating film for release paper having good curability and having a large release force with an arbitrary release force.

The above results demonstrate that the composition of the present invention has good curability, easily adjusts the release force, and is effective as a coating film for heavy release paper with heavy release. Things. Further, the coating film formed by applying and curing the coating composition of the present invention has a large dynamic friction coefficient when the films come into contact with each other. It is effective for

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenichi Isobe 1-10 Hitomi, Matsuida-cho, Usui-gun, Gunma Prefecture Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Technology Laboratory

Claims (3)

[Claims] (1) A butadiene-based polymer having at least two alkenyl groups and / or a butadiene-based polymer having at least two alkenyl groups,
(2) a polybutadiene-based derivative having an organosilicon group bonded through a C-Si bond, (2) an organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms in one molecule, a (SiH / alkenyl group) An amount such that the molar ratio is in the range of 0.5-50, and
(3) A coating composition for release paper, comprising an addition reaction catalyst. 2. The method according to claim 1, wherein the butadiene polymer having at least two alkenyl groups in the component (1) has C-S
The coating composition for a release paper according to claim 1, wherein the organosilicon group of the polybutadiene-based derivative having an organosilicon group bonded through an i bond is a group represented by any of the following formulas (1) to (3). Stuff. Embedded image However, n in Chemical formula ¹ represents 0 or a positive integer, and R ¹ ,
R ² , R ³ , R ⁴ and R ⁵ represent the same or different organic groups having no aliphatic unsaturated group. Embedded image However, p and q in Chemical formula 2 represent 0 or a positive integer, and do not become 0 at the same time. R ¹ , R ² , R ³ , R ⁴ , R
⁵ , R ⁶ and R ⁷ represent the same or different organic groups having no aliphatic unsaturated group. Embedded image However, r in Chemical formula 3 represents a positive integer of 2 or more, and R ¹ , R
² , R ³ represent the same or different organic groups having no aliphatic unsaturated group. 3. The release paper coating according to claim 1, wherein the fourth component contains (4) polydimethylsiloxane having two or more alkenyl groups directly bonded to siloxane in one molecule. Composition.