JPH0726063B2 - Coating resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a resin composition for coating, and particularly to a resin composition suitable for coating paper or film.

<< Conventional Technology >> Conventionally, there has been known a technology of applying a silicone composition to the surface of paper or film to impart heat resistance, releasability, lubricity and the like. However, silicone generally has poor adhesion to a film substrate, and since the curing of the silicone is due to an addition reaction or a condensation reaction, the curability tends to be insufficient unless a high processing temperature is maintained. However, there is still no known silicone composition for coating which is excellent in application to a film.

Regarding the above-mentioned improvement of adhesion, although primer treatment to the material and addition of adhesion improver have been taken as countermeasures, for the curability side, an ultra-thin film of 10 μm or less has been recently used. An effective means has not yet been found in consideration of the problem of shrinkage when used as a base material. Therefore, there has been a demand for the development of a coating composition capable of rapidly forming a film without impairing the characteristics such as mold release property and heat resistance of silicone.

<< Problems to be Solved by the Invention >> As such a coating composition, for example, a copolymer of polysiloxane / styrene / (meth) acrylic acid ester is known (JP-A-63-210160). Certainly, the above-mentioned copolymer has characteristics that it is excellent in quick-drying property and adhesiveness, and also has writability. However, the manufacturing method thereof is styrene / (meth) acrylic acid ester in siloxane having a certain degree of polymerization. However, it is difficult to control the viscosity because of the method of copolymerizing the above, and there is a drawback that the coatability is difficult.

As a result of intensive investigations by the present inventors to solve the above-mentioned drawbacks,
When the styrene / (meth) acrylic acid ester copolymer and the siloxane are heat-treated in the presence of a solvent, the ratio of the two can be arbitrarily selected, so that the viscosity of the product can be easily controlled. The inventors have found that the above can be achieved and reached the present invention.

Therefore, an object of the present invention is to provide a resin composition for coating which is particularly excellent in adhesiveness and quick-drying property to a plastic film.

<< Means for Solving the Problems >> The above object of the present invention is to provide a styrene / (meth) acrylic acid ester copolymer,
And 100 parts by weight of a product obtained by mixing and reacting a reactive orisiloxane represented by the following formula: At least one selected from silane and siloxane compounds having at least three alkoxy groups in one molecule and organohydrogenpolysiloxane having at least three hydrogen atoms bonded to silicon atoms in one molecule.
Achieved by a coating resin composition comprising 1 to 100 parts by weight of a compound of the invention and 0.5 to 50 parts by weight of a curing catalyst.

The styrene / (meth) acrylic acid ester copolymer used as the first component constituting the composition of the present invention is benzoyl peroxide, t-butyl perbenzoate, di-t.
-Butyl peroxide or azoisobutyronitrile is used as an initiator for copolymerization by a known method, and the ratio of styrene / (meth) acrylic acid ester becomes harder as the amount of styrene increases.

(Meth) acrylic acid ester is methyl methacrylate,
It can be appropriately selected from ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and the like.

In the above formula of reactive polysiloxane, R ¹ represents a monovalent hydrocarbon group having 1 to 8 carbon atoms, and R ² represents OH or an alkenyl group such as vinyl or allyl. here,
a is an integer of 1 to 10, n + m is an integer of 70 or more, and m is an integer of 0 or more.

In the present invention, the copolymer and the reactive polysiloxane are mixed in the presence of a solvent, and an organic peroxide is added if necessary, and then 100 to 200 ° C.
The first component can be obtained by heat treatment at the temperature of 1 hour or more. In this case, the composition ratio of each component is preferably 40 to 80 parts by weight of the copolymer of styrene / (meth) acrylic acid ester with respect to 20 to 60 parts by weight of the reactive polysiloxane.

If the reactive polysiloxane component is less than 20 parts by weight, heat resistance and releasability are unsatisfactory, while if it is more than 60 parts by weight, the film forming property is impaired.

Examples of the reactive polysiloxane include those having an unsaturated group such as a vinyl group or an allyl group or a silanol group, and the viscosity thereof is 100 cs at 25 ° C.
As described above, the range is preferably 500 to 100,000 cs. Among these reactive polysiloxanes, dimethylpolysiloxane or vinylmethylpolysiloxane whose both ends are blocked with hydroxy groups is particularly preferable.

In addition, even if the styrene / (meth) acrylic acid copolymer and the reactive siloxane are simply mixed, the performance intended in the present invention cannot be obtained.

CH ₃ Si (OCH ₃ ) ₃ and CH ₃ Si (OC ₂ H ₅ ) ₃ are silanes and siloxanes having three alkoxy groups in one molecule, which can be the second component constituting the composition of the present invention. _{, C 2 H 5 Si (OCH} 3) 3, n-C 3 H 7 Si (OCH 3) 3, iso-C 3 H 7 Si (OCH 3) 3, cyclo-C 6 H 11 Si (OCH 3) 3 , C ₆ H ₅ Si (OCH ₃ ) ₃ , In addition to the above, a condensate obtained by condensing one or several of these as the main component, and having a viscosity at 25 ° C in the range of 1 to 20 cs is preferable, and a part thereof is (CH ₃ ) ₂ Si ( It can also be a dialkyl dialkoxy silane such as OCH ₃ ) ₂ .

On the other hand, as the organohydrogenpolysiloxane that can be the second component, it is necessary to have at least three hydrogen atoms (≡SiH groups) bonded to silicon atoms in one molecule. 90 mol% or more is preferably a methyl group. This type of polysiloxane includes (CH ₃ ) HSiO units, HSiO _1.5 units, (CH 3
₃ ) ₂ SiO units, CH ₃ SiO _1.5 units, (CH ₃ ) ₂ HSiO _0.5 units, or (CH ₃ ) ₃ SiO _0.5 units are exemplified as homopolymers or copolymers. These may be linear, branched or cyclic and preferably have a viscosity at 25 ° C in the range of 10 to 500 cs.

From the viewpoint of cured film forming ability and peeling performance, it is preferable that the blending amount of these second components is in the range of 0.1 to 50 parts by weight with respect to 100 parts by weight of the first component.

When the first component is a reactive siloxane having an unsaturated group, it is necessary to select the organohydrogenpolysiloxane as the second component, but the second component when the terminal hydroxypolysiloxane is used as the first component. Is 1
Any of silane having at least 3 alkoxy groups in the molecule, siloxane having at least 3 alkoxy groups in the molecule, and organohydrogenpolysiloxane having at least 3 hydrogen atoms bonded to silicon atoms in the molecule. Can also be combined.

The third component in the composition of the present invention is a catalyst for promoting the curing reaction of the above-mentioned first and second components, and when a siloxane having an unsaturated group is used as the reactive siloxane, for example, chloride is used. Platinum acid, platinum-olefin complex or vinyl siloxane complex, particulate platinum adsorbed on a carrier such as alumina silica, a platinum catalyst such as a palladium catalyst or a rhodium catalyst can be used, and among these, platinum is particularly preferable. Compounds are preferred.

The catalyst may be used in an amount sufficient to cure the composition of the present invention, but in the range of 1 to 1,000 ppm with respect to the weight of the first component from the viewpoint of obtaining a good film from an economical viewpoint. Preferably.

On the other hand, when a terminal hydroxypolysiloxane is used as the reactive siloxane in the first component, the catalyst known as a so-called condensation reaction accelerator, for example, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctate, oleic acid is used. It can be used by appropriately selecting from tin, tin stearate, zinc palmitate, zinc octylate and the like. Although the amount of the catalyst used in this case varies depending on the curing conditions and the type of the treated substrate, it is generally the first
And, based on the total weight of the second component, 0.1 to 10%, preferably 1
Use ~ 5%.

The composition of the present invention can be diluted with a commonly used general-purpose solvent such as toluene, hexane, heptane, ethyl acetate, and methyl ethyl ketone. In this case, the dilution rate may be set appropriately depending on the coating conditions.

To the composition of the present invention, ordinary polysiloxane, antistatic agent and the like can be added for the purpose of improving the physical properties of the cured film.

The viscosity when using the composition of the present invention thus obtained, the coating amount, the coating method, and the target coating material, such as polyethylene laminated paper, glassine paper and the like, polyester, polypropylene and the like. It may be appropriately determined depending on the type of plastic film, etc., but from the viewpoint of workability, it is preferable that the viscosity at 25 ° C. be approximately 10,000 cs or less.

The coating for forming the film can be easily performed by a known means such as a roll coater. Further, the film thickness after curing is preferably about 0.05 to 2 μm.

The substrate treated with the composition of the present invention is 60 ° C or higher, preferably 80 ° C or higher.
A film having releasability can be formed on the surface of the substrate by heating at a temperature of not less than 0 ° C for 10 seconds or more. This cured film not only has excellent adhesion to plastic films and the like, but also has excellent abrasion resistance and good release properties, so the composition of the present invention is particularly useful for release films. .

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

In the examples, "parts" are parts by weight, and "viscosity" is a value measured at 25 ° C.

In the glass reactor of Example 1.1, 180 g of styrene and n-acrylic acid were added.
150 g of butyl and 250 g of toluene were added, and the mixture was heated with stirring under a nitrogen stream. After adding 1.7 g of t-butyl perbenzoate at 100 ° C., the mixture was kept at 110 to 130 ° C. for 6 hours to carry out polymerization.

After the polymerization reaction, toluene and unpolymerized monomers were distilled off to obtain a polymer (referred to as polymer A) 63 g, 25 ° C
42 g of terminal hydroxydimethylpolysiloxane having a viscosity of 700 cs and 245 g of toluene were held in a 500 ml glass reactor under toluene reflux for 2 hours. The viscosity of the obtained product was 65 cs at 25 ° C.

After cooling the product, 17.5 g of polymethylmethoxysiloxane having a viscosity of 4.5cs at 25 ° C was added and mixed to obtain 10 g of the mixture. To this 10 g was added 50 g of toluene / ethyl methyl ketone (50/50). The diluted solution was used as a processing liquid I.

Add 25 g of dibutyltin diacetate to Treatment Solution I
It was applied to a m-thick polyester film using a # 8 wire doctor, and the curability, adhesion, peeling resistance, etc. were examined. The results are as shown in Table 1.

In addition, the measuring method of each physical property is as follows.

[Curability]

After applying a predetermined amount of the treatment liquid to the surface of the thin film or sheet-shaped substrate, heating in a hot air circulation dryer at a predetermined temperature for a predetermined time was measured to measure the time until a complete cured film was formed. .

Incidentally, it was judged that the completely cured film was formed when the coated surface was not rubbed off and the coated surface became cloudy when the coated surface was lightly rubbed with a finger.

(Peeling resistance)

After applying a predetermined amount of the treatment liquid to the surface of the thin film or sheet-like substrate, after heating for a predetermined time in a hot air circulation dryer held at a predetermined temperature to form a complete cured film,
Sekisui Chemical Co., Ltd. craft tape was attached to the cured film surface, aged at 70 ° C for a predetermined time under a load of 20 g / cm ² , and then a test piece was prepared using a tensile tester.
The laminated paper was pulled at a peeling speed of 0.3 m / min at an angle of 180 °, and the force (g) required for peeling was measured.

[Adhesion]

A predetermined amount of the treatment liquid is applied to the surface of the thin film or sheet-shaped substrate, and after a heat treatment is performed at a predetermined temperature for a predetermined time using a hot air circulation type dryer to form a complete cured film, 50 ° C.,
It was placed in a thermo-hygrostat set to 90% RH, and the coated surface was rubbed with a finger every predetermined time, and it was judged whether or not the coated surface fell off.

[Slip properties]

A predetermined amount of the treatment liquid is applied to the surface of a thin film or sheet-shaped substrate, and a hot air circulation dryer is used to heat-treat at a predetermined temperature for a predetermined time to form a completely cured film, and then the surface is formed. After placing a urethane rubber with a load of 200 g, measure the force (g) required when pulling this urethane rubber in the direction parallel to the treated surface at 0.3 m / min, divide this by 200 g Was defined as the dynamic friction coefficient (according to ASTM D1894-63).

[Writability]

A predetermined amount of the treatment liquid is applied to the surface of a thin film or sheet-like base material, and heat treatment is performed at a predetermined temperature for a predetermined time using a hot air circulation dryer to form a completely cured film, and then with an oil-based marker. Regarding the result of observing the presence or absence of cissing
A graded evaluation was performed.

○ ・ ・ ・ ・ No repelling △ ・ ・ ・ ・ Slight repelling × ・ ・ ・ ・ Repelling [Silicone transferability] A predetermined amount of the treatment liquid is applied to the surface of the thin film or sheet substrate, and hot air circulation drying is performed. Using a machine, heat at a given temperature for a given time to form a completely cured film, then 25 μm
A thick polyester film was superposed on the treated surface, pressure-bonded and left for 1 day, and then an oil-based marker was applied to the polyester film side, and the degree of cissing was observed.

◎ ・ ・ ・ No cissing ○ ・ ・ ・ ・ Most cissing △ ・ ・ ・ ・ Slight cissing × ・ ・ ・ ・ Scissor repellence Comparative Example 1. Polymer A6g used in Example 1 for comparison, 25 ° C
After adding terminal hydroxydimethylpolysiloxane having a viscosity of 700 cs in Example 1, a mixed solvent of toluene / ethyl methyl ketone (50/50) was added so that the concentration of the solid content of the treatment liquid I prepared in Example 1 was the same. Addition to the dissolved solution at 25 ° C
Then, 1.7 g of 4.5 methyl polymethylmethoxypolysiloxane was added to prepare a treatment liquid II.

0.5 g of dibutyltin diacetate was added to 60 g of this treatment liquid II, and then it was applied to a 25 μm thick polyester film using a # 8 wire doctor to form a film.

The film had no strength and had poor adhesion to the polyester film so that it could be easily removed with a finger.

Example 2. Instead of the terminal hydroxydimethylpolysiloxane used in Example 1, a dimethylpolysiloxane having a viscosity of 30,000 cp and both ends blocked with vinyldimethylsilyl groups and a vinyl value of 0.026 mol / 100 g was used. Heat treatment was carried out as in Example 1 to give a product with a viscosity of 90 cs at 25 ° C.

Methylhydrogenpolysiloxane with a viscosity of 20cs in which both ends are blocked with trimethylsilyl groups in the above product 1.
Add 5 g and mix well, and collect 10 g from the mixture,
Treatment liquid III was prepared by diluting 0 g of a mixed solution of toluene / ethyl methyl ketone (50/50).

Next, platinum vinyl siloxane complex was added to treatment liquid III so that the platinum amount was 100 ppm (based on the solid content in the treatment liquid), and 25 μm was obtained using a # 8 wire doctor.
Table 1 shows the results of coating a thick polyester film and examining curability, film adhesion, peeling resistance, and the like.

As is clear from the results of the above Examples and Comparative Examples, the desired performance cannot be obtained by simply mixing the styrene / (meth) acrylic acid copolymer and the reactive siloxane, while heating both It was demonstrated that the effects of the present invention can be obtained by reacting the above.

Claims (1)

[Claims] 1. A product obtained by mixing a styrene / (meth) acrylic acid ester copolymer and a reactive polysiloxane represented by the following formula and heat-treating them: 100 parts by weight; However, in the formula, R ¹ represents a monovalent hydrocarbon group having 1 to 8 carbon atoms, and R ² represents an OH or alkenyl group. Where a is 1
An integer of -10, n + m is an integer of 70 or more, and m is an integer of 0 or more. Silane and siloxane compounds having at least 3 alkoxy groups in one molecule, and one molecule of a hydrogen atom bonded to a silicon atom. At least 1 selected from organohydrogenpolysiloxanes having at least 3
A coating resin composition comprising 1 to 100 parts by weight of the seed compound; and 0.5 to 50 parts by weight of a curing catalyst.