JPH0637532B2 - Method for producing curable resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a curable resin. Particularly, the present invention relates to a method for producing a resin useful in the field of surface coating having excellent releasability and antifouling property by utilizing the properties of excellent weather resistance and low surface energy.

[Conventional technology and problems]

It is known to mix a curable silicone resin, mainly a rubber silicone resin, with a liquid having a releasing action such as silicone oil to form a coating having an antifouling effect particularly in seawater.

The same is said for thermoplastic type silicone resins. For example, JP-A No. 60-65076 discloses a reaction-curable silicone composition, JP-A No. 62-156172 discloses a polymer of vinyl silicon, and JP-A No. 62-275132 discloses a polysiloxane macromer. Copolymers with vinyl monomers are disclosed.

However, existing coatings based on these silicone resins are easily peeled off because of poor adhesion to the substrate under conditions of constant exposure to waves, such as when immersed in seawater. It is difficult to maintain the antifouling effect for a long period of time.

The present invention eliminates these conventional drawbacks, forms a low energy surface to exhibit an antifouling effect, has good adhesion to the substrate, and can withstand repeated stress such as waves sufficiently, and is practically used. The present invention relates to a method for producing a coating resin that is difficult to peel off.

[Means for Solving the Problems]

That is, according to the present invention, (A) at least a part of an unsaturated hydrogen is reacted with a silicone resin having at least one active hydrogen in one molecule and having a main chain of constituent molecules having a polysiloxane structure. A step of converting to a silicone resin having a saturated bond and then adding thereto a monomer having active hydrogen, a fluorine-containing (meth) acrylate and, if necessary, a copolymerizable monomer, and polymerizing it into a graft polymer; and ( B) introducing an unsaturated bond into the graft polymer by adding an unsaturated isocyanate to the graft polymer and reacting active hydrogen in the graft polymer with the isocyanate. It provides a method.

The resin produced by the method of the present invention is excellent in adhesion with metals such as iron and aluminum, concrete, inorganic building materials including slate, wood, etc., and by hardening this, it is tough and durable. It becomes possible to obtain a certain coating film.

In order to help understanding of the present invention, the procedure of the present invention is illustrated as follows.

The above formula shows an example in which 1,1,1,3,3,3-hexafluoroisopropylmethacrylate is used as the fluorine-containing monomer and 2-hydroxyethylmethacrylate is used as the monomer having active hydrogen.

When the polymer of the above formula is reacted with an unsaturated isocyanate, one of the graft polymers having an unsaturated bond of the present invention can be obtained.
The following equation is obtained as an example.

The unsaturated polymer according to the present invention includes (a) a ratio of a silicone resin, (b) an unsaturated degree of a silicone resin, and (c) a fluorine-containing (meth).
By changing factors such as the type and amount of acrylate, (d) the type of copolymerizable monomer, (e) the degree of unsaturation of the unsaturated graft polymer obtained by the final polymerization, a wide range of resin can be obtained. The physical properties can be changed, and it becomes possible to cope with a variety of uses.

For example, by using methyl methacrylate as a monomer, a coating film having excellent weather resistance can be obtained.

The raw materials used in the present invention are classified into the following types.

(A) active hydrogen-containing silicone resin, (b) unsaturated isocyanate, (c) monomer having active hydrogen, (d) fluorine-containing (meth) acrylate, and optionally (v) copolymerizable monomer.

The silicone resin (a) used in the present invention has a main chain of constituent molecules represented by the following formula: (Wherein R and R'are alkyl groups and phenyl groups) and has a polysiloxane structure, and at least one active hydrogen capable of reacting with an isocyanate, typically a hydroxyl group, should be possessed in one molecule. is necessary.

As such a silicone resin, dimethylpolysiloxane having a hydroxyl group at the terminal is suitable, and examples of commercially available products include the following types manufactured by Shin-Etsu Chemical Co., Ltd.

X-22-160A Hydroxyl number 62 Molecular weight 1800 X-22-160B Hydroxyl number 35 Molecular weight 3200 X-22-160C Hydroxyl number 20 Molecular weight 5600 For introducing an unsaturated bond into these hydroxyl group-containing silicone resins. The unsaturated isocyanate (b) includes a) a compound that shares an unsaturated bond with an isocyanate group in one molecule, b) an adduct of diisocyanate with an unsaturated monoalcohol in an amount of 1 mol to 1 mol, etc. Can be given.

Examples of unsaturated isocyanates include, for example, isocyanate ethyl methacrylate, methacryloyl isocyanate, m-isopropenyl-α, α dimethylbenzyl isocyanate, generally isocyanate ethyl methacrylate (the following formula) Is preferable from the viewpoints of handleability and reactivity of isocyanate.

The reaction product of diisocyanate and unsaturated alcohol is, for example, an adduct of 2,4-tolylene diisocyanate and 2-hydroxyethyl methacrylate in an amount of 1 mol to 1 mol (the following formula).

In this case, diisocyanate includes 2,4-tolylene diisocyanate and isophorone diisocyanate.
Preference is given to different types of reactivity of the two isocyanate groups.

The reaction ratio between the active hydrogen of the silicone resin and the unsaturated isocyanate is 100 parts by weight of the silicone resin (weight part, the same applies hereinafter).
On the other hand, the unsaturated isocyanate is 0.01 part or more and 10 parts or less, preferably 0.1 part or more and 3 parts or less. In this case, it is not necessary to react all the active hydrogen present. The degree depends on the types of monomers used together and the ratio of the unsaturated silicone resin to the monomers.

Examples of the monomer (c) having active hydrogen include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate,
Examples thereof include 2-hydroxypropyl methacrylate and phenoxyethyl methacrylate.

The fluorine-containing (meth) acrylate used in the present invention is
Acrylic ester or methacrylic ester of alcohol having a fluorinated alkyl group and / or alkylene group, wherein part or all of hydrogen atoms in the alkyl group or alkylene group are replaced by fluorine, and 1
Acrylic ester or methacrylic acid ester of an alcohol in which the total number of carbon atoms of an alkyl group, an alkylene group, or both groups in the molecule is 1 to 30, which are compounds exemplified below: (However, m = 0 to 18, n = 0 to 18, R = H or C
H ₃ CO, X = H or CH ₃ , R ′ = H or CH ₃
(CH ₂ ) _n ).

The monomer used in combination as the copolymerizable monomer (e) is not particularly limited as long as it can be copolymerized with the monomer, and generally commercially available types are used. There are no particular restrictions on the type,
Examples thereof include styrene, vinyltoluene, acrylic acid esters, methacrylic acid esters, acrylonitrile, methacrylonitrile, vinyl acetate, ethylene and butadiene.

The ratio of the unsaturated bond-introduced silicone resin and the copolymerization monomer is 10 to 95% (wt%, the same applies hereinafter) of the unsaturated bond-introduced silicone resin, and preferably 20 to 90%.

The use ratio of the monomer (c) having active hydrogen, the fluorine-containing (meth) acrylate (d) and the copolymerizable monomer (e) is 1 to 3 when the monomer as a whole is 100.
It is preferably 0, 1 to 70 and 0 to 69 mol%.

As the unsaturated isocyanate for introducing an unsaturated group into the graft polymer having active hydrogen used in step (B) of the method of the present invention, the various unsaturated isocyanates described above can be used as they are. The amount of the unsaturated bond in the graft polymer is preferably in the range of 1 to 30 mol%.

A radical generating catalyst is required for curing the silicone resin graft unsaturated polymer according to the present invention, and a commonly used radical generating agent can be used for this.
In this case, it goes without saying that a reinforcing material, a filler, a coloring agent, a wax and the like can be used in combination, if necessary.

Next, the present invention will be further described with reference to examples.

Example 1 In a one-separable flask equipped with a stirrer, a reflux condenser, a thermometer, and a gas introduction tube, a silicone resin having a hydroxyl group (X-22-160B manufactured by Shin-Etsu Chemical Co., Ltd., hydroxyl number about 35, molecular weight 3200). 200 parts (parts by weight, the same applies hereinafter) and 1.0 part of isocyanate ethyl methacrylate
Part, dibutyltin dilaurate, 0.2 part was charged,
The reaction was carried out at 65 ° C for 4 hours. As a result of infrared analysis, it was confirmed that the free isocyanate group disappeared.

2-hydroxypropyl methacrylate 29
Part, a fluoroacrylate represented by the following formula 150 parts, styrene 40 parts, and azobisisobutyronitrile 1 part were added, and after polymerization at 65 to 70 ° C. for 3 hours, 0.1 part of hydroquinone was added to terminate the polymerization.

It was a cloudy, thixotropic liquid.

Then, 30 parts of isocyanate ethyl methacrylate,
Add 0.5 parts of dibutyltin dilaurate, 60 ~ 65 ℃
For 6 hours under dry air. An unsaturated polymer (I) grafted with a loose syrup-like fluoroacrylate was obtained. As a result of infrared analysis, it was confirmed that the free isocyanate group disappeared.

To 100 parts of the unsaturated graft polymer (I), 3 parts of "Darogua # 1173" manufactured by Merck Ltd. as a photo-curing initiator was added,
After being applied to a bonderite steel sheet so as to have a thickness of 100 μm, it was irradiated with 20 cm under a 250 kw sun lamp for 15 minutes.

The glossy reflectance of the cured coating film was 89%, the pencil hardness was 2B, and the cellophane tape adhesion test did not attach any cellophane tape, and the peel strength was 0.1 kg / in or less.

The gloss reflectance after irradiation with the Dew cycle weatherometer for 1000 hours was 87%, which was almost unchanged.

Example 2 In a one-separable flask equipped with a stirrer, a reflux condenser, a gas introduction tube, and a thermometer, 200 parts of a silicone resin (X-22-160A manufactured by Shin-Etsu Chemical Co., Ltd., hydroxyl value 62, molecular weight 1800), 1 mol to 1 mol of the adduct of isophorone diisocyanate and 2-hydroxyethylmethacrylate was added to 2
Part, 0.2 part of dibutyltin dilaurate is added to 65-70
The reaction was carried out at 0 ° C for 3 hours. As a result of infrared analysis, it was confirmed that the isocyanate group had disappeared. 1,1,1,3,3,3-hexafluoroisopropyl methacrylate (the following formula) 220 parts, 2-hydroxypropyl methacrylate 3
Add 0 part and 1 part of azobisisobutyronitrile,
After polymerizing at 70 ° C for 3 hours, 0.05 g of hydroquinone was added to terminate the polymerization, 31 parts of isocyanatoethylmethacrylate and 0.5 part of dibutyltin dilaurate were added, and after reacting for another 34 hours, a cloudy viscous liquid resin (II) was gotten. As a result of infrared analysis, it was confirmed that the free isocyanate group disappeared.

To 100 parts of this resin (II), 2 parts of Kayaku Nouri Co. 328E and 0.5 part of cobalt naphthenate were added as a curing agent,
It was painted on a bonderite steel plate to a thickness of 0.2 mm.

After about 3 hours at room temperature, the surface became non-adhesive, the coating film hardness after curing at 120 ° C. for 2 hours was B, and the cellophane tape did not adhere at all in the cellophane tape adhesion test, and the peel strength was 0.1 kg / in or less.

〔The invention's effect〕

Since the present invention is configured as described above, it is possible to produce a curable resin that has good adhesion to a substrate, low surface energy, weather resistance, and excellent antifouling coating film performance. it can.

Claims (1)

[Claims] (A) A silicon resin having at least one active hydrogen atom in one molecule and having a polysiloxane structure as a main chain of a constituent molecule is reacted with an unsaturated isocyanate to form at least a part of unsaturated. A step of converting to a silicone resin having a bond, and then adding a monomer having active hydrogen, a fluorine-containing (meth) acrylate and, if necessary, a copolymerizable monomer thereto, and polymerizing them into a graft polymer; and (B ) Adding an unsaturated isocyanate to the graft polymer and reacting active hydrogen in the graft polymer with the isocyanate to introduce an unsaturated bond into the graft polymer; .