JP5122137B2 - Graft copolymer, coating agent, and method for forming coating film - Google Patents

Description

  The present invention relates to a graft copolymer, a coating agent, and a method for forming a coating film.

In the field of coating agents and the like, various organic resins such as urethane resins and acrylic resins are used (see Patent Document 1).
JP 2001-226437 A

However, since most of these resins are soluble in a flammable solvent, when these resins are used, it is necessary to provide a large-scale safety device such as a draft device in the factory. In addition, these resins have low water repellency and water absorption, so the base material is protected from applications that require water repellency and moisture resistance, such as moisture-proof coating agents for electronic substrates, salt water and electrolytes, etc. It is not well suited for chemical resistant protective coatings. In addition, since these resins have water absorption, there is a problem that the resin itself absorbs water and deteriorates with long-term use.
In addition, since these resins have low oil repellency, they are not suitable for applications utilizing the oil repellency of the resins (for example, oil barrier agents that prevent the diffusion of lubricating oil). Of course, fluororesin is known to be soluble in non-flammable solvents and to have water and oil repellency, but this resin is brittle and has the property of being susceptible to cracking due to thermal expansion and contraction and impact. , Its field of use was limited.

  This invention is completed based on the above situations, Comprising: It aims at providing the novel polymer which can be used for a wide use and is soluble in a nonflammable solvent.

The present inventors have intensively studied to develop a novel polymer that can be used in a wide range of applications and is soluble in a non-flammable solvent. As a result, a trunk polymer obtained by copolymerizing a (meth) acrylic acid ester represented by the following general formula (1) and an acrylic acid ester represented by the following general formula (2) is represented by the following general formula (3). The graft copolymer obtained by graft polymerization of the fluorine-containing monomer is dissolved in a non-flammable solvent, is excellent in water and oil repellency, and has flexibility and resistance to cracking, and can be used in a wide range of applications. I found that it can be used.
Here, the presumed mechanism in which the graft copolymer of the present invention has excellent properties will be described. Since the backbone polymer of the graft copolymer of the present invention is a copolymer of (meth) acrylic acid ester and acrylic acid ester, a structural unit derived from a fluorine-containing monomer is contained in the main chain like a conventional fluororesin. Does not hold and is difficult to crack. Furthermore, since a graft chain composed of a polymer of a fluorine-containing monomer is formed, it is considered that the graft chain improves the solubility in a nonflammable solvent and improves the water repellency and oil repellency. The present invention has been made based on this finding.

That is, the polymer of the present invention is represented by the following general formula (1), the (meth) acrylic acid ester represented by the following general formula (1) and the acrylic acid ester represented by the following general formula (2). (Meth) acrylic acid ester: acrylic acid ester represented by the following general formula (2) = 85: 15 to 35:65 in a weight ratio, and a backbone polymer obtained by copolymerization by a solution polymerization method , It is a graft copolymer having a number average molecular weight of 20,000 to 100,000 obtained by graft polymerization of a fluorine-containing monomer represented by the general formula (3) by a solution polymerization method .

（式中、Ｒ_１は、メチル基であり、Ｒ_２は炭素数１〜８の直鎖状または分岐状アルキル基である。）

(In the formula, R ₁ is a methyl group, and R ₂ is a linear or branched alkyl group having 1 to 8 carbon atoms.)

（式中、Ｒ_３は、炭素数６〜１８の直鎖状または分岐状アルキル基である。）

(In the formula, R ₃ is a linear or branched alkyl group having 6 to 18 carbon atoms.)

（式中、Ｒ_４は、水素又はメチル基であり、ｎは、１〜１２の整数を示す。）

(In the formula, R ₄ represents hydrogen or a methyl group, and n represents an integer of 1 to 12.)

Here, as R < ₂ > of the (meth) acrylic acid ester of the general formula (1), for example, methyl, ethyl, propyl, and butyl may be mentioned, and as the (meth) acrylic acid ester of the general formula (1), methyl Examples thereof include methacrylate (methyl methacrylate), ethyl methacrylate, propyl methacrylate, n-, t-, and iso-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, and cyclohexyl acrylate.

Examples of R ₃ of the acrylate ester represented by the general formula (2) include 2-ethylhexyl group, lauryl group, and stearyl group. As the acrylate ester, 2-ethylhexyl acrylate (2-ethylhexyl) is exemplified. Acrylate), lauryl acrylate, stearyl acrylate.

Then, the monomers of the general formulas (1) and (2) can be polymerized by a known polymerization method to obtain a trunk polymer. For example, a solution polymerization method can be used. For example, in the case of the solution polymerization method, each monomer is dissolved in a solvent with a desired monomer composition, a radical polymerization initiator is added and stirred under heating in a nitrogen atmosphere, and the trunk polymer (random copolymer) is obtained. Can be obtained.

  As the solvent used in the polymerization, any solvent that can dissolve or suspend the monomer can be used. For example, water or an organic solvent such as toluene, xylene, heptane, cyclohexane, and tetrahydrofuran can be used. Yes, it can be used alone or in combination of two or more.

  The polymerization initiator is not particularly limited as long as it has the ability to initiate radical polymerization. For example, peroxides such as benzoyl peroxide, azobisisobutyronitrile, 2,2′-azobis (isobutyric acid) ) In addition to azo compounds such as dimethyl, persulfuric acid polymerization initiators such as potassium persulfate and ammonium persulfate may be mentioned.

  The polymerization time is not particularly limited, but is usually 2 to 24 hours. When it is desired to obtain a relatively high molecular weight polymer, it is desirable to react for about one day. If the reaction time is too short, unreacted monomers may remain and the molecular weight may be relatively small. The average molecular weight (Mn) of the trunk polymer of the present invention is preferably about 10,000 to 50,000 in terms of polystyrene. When the degree of polymerization is small, the film strength when the graft copolymer is used as a film is lowered, and when the degree of polymerization is too large, the solubility of the graft copolymer in a nonflammable solvent tends to be lowered. is there.

  In addition to the monomers represented by the general formulas (1) and (2), other monomers may be copolymerized as long as the effects of the present invention are not impaired.

  The trunk polymer is polymerized as described above. The weight ratio of the (meth) acrylic acid ester represented by the general formula (1) to the acrylic acid ester represented by the general formula (2) (Meth) acrylic acid ester represented by (1): acrylic acid ester represented by general formula (2) = 85: 15 to 35:65 It is preferable to copolymerize in a ratio of 85:15 to 50. Is preferably copolymerized at a ratio of 50, and particularly preferably at a ratio of 85:15 to 55:45. The (meth) acrylic acid ester represented by the general formula (1) has a role of suppressing the stickiness of the graft copolymer and adjusting the properties of the graft copolymer film. Therefore, if the (meth) acrylic acid ester represented by the general formula (1) is less than this range, the graft copolymer tends to be too soft (tends to be sticky), and is used for coating agents and the like. It is not very suitable.

On the other hand, the acrylic ester represented by the general formula (2) has a function of improving the flexibility of the graft copolymer. Therefore, when the (meth) acrylic acid ester represented by the general formula (1) is more than the above range, the graft copolymer tends to be brittle, and cracks are easily generated due to expansion / contraction due to heat or impact. Therefore, it is not very suitable for uses such as coating agents.
In addition, the glass transition temperature of the trunk polymer is about 0 to 40 ° C. at the above mixing ratio.

In the present invention, the fluorine-containing monomer represented by the general formula (3) is further graft polymerized to the trunk polymer.
R _{4 of the} fluorine-containing monomer represented by the general formula (3) is hydrogen or a methyl group. Further, n is 1 to 12, and n = 8 is particularly preferable from the viewpoint of high water and oil repellency.

  Examples of the fluorine-containing monomer represented by the general formula (3) include perfluorooctylethyl (meth) acrylate, trifluoromethylethyl (meth) acrylate, and perfluorodecylethyl (meth) acrylate. In addition to these monomers alone, mixtures thereof can also be used.

The graft copolymer can be prepared by graft polymerization of the trunk polymer and the monomer of the general formula (3) by a known polymerization method. For example, it is possible to use a solution polymerization method, since it can be done in a relatively simple apparatus, a solution polymerization method is preferable.

  This graft polymerization is carried out by putting the monomer of the general formula (3) and the initiator into the reaction solvent in which the monomer of the general formula (1) and the monomer of the general formula (2) are reacted to synthesize the trunk polymer. Also good. Alternatively, the trunk polymer may be once taken out from the reaction solvent, and the trunk polymer is dissolved again in the solvent to form a solution, and the monomer of general formula (3) and the initiator may be put into this solution.

  As the solvent used in the polymerization, any solvent can be used as long as it can dissolve or suspend the monomer of the general formula (3). For example, water, toluene, xylene, heptane, cyclohexane, There are organic solvents such as tetrahydrofuran, and they can be used alone or in combination of two or more.

  The graft polymerization initiator is not particularly limited as long as it is a peroxide, and examples thereof include t-butyl hydroperoxide, cumene hydroperoxide, t-butyl cumer peroxide, di-t-butyl peroxide, and benzoyl peroxide. A wide variety of known materials such as oxide, diisobutyl peroxide, bis (4-t-butylcyclohexyl) peroxydicarbonate, diisopropanol peroxydicarbonate and the like can be used. These peroxides may be used alone or in combination of two or more.

  By using a peroxide for graft polymerization, hydrogen in the trunk polymer is extracted, radicals are generated in the trunk polymer, and a grafting origin is generated. By using a peroxide, a graft copolymer can be obtained with easy operation and low cost. The polymerization time is not particularly limited.

  The graft copolymer is polymerized as described above. The total amount of the (meth) acrylic acid ester represented by the general formula (1) and the acrylic acid ester represented by the general formula (2), and the general formula The weight ratio of the monomer amount represented by (3) is preferably in the range of the total amount: the monomer amount represented by the general formula (3) = 95: 5 to 20:80, and more preferably 80:20 to A range of 40:60 is preferable, and a range of 70:30 to 50:50 is particularly preferable. The graft chain (branch chain) contains fluorine, and this fluorine improves the solubility in nonflammable solvents such as perfluorocarbon. Therefore, when there is too little monomer represented by General formula (3), it exists in the tendency for the solubility to a nonflammable solvent to fall.

  On the other hand, when the amount of the monomer represented by the general formula (3) is too large, the graft copolymer becomes brittle and tends to be cracked by expansion and contraction due to heat or impact. Moreover, when there are too many monomers represented by General formula (3), it exists in the tendency for the adhesiveness to the to-be-coated thing of the film | membrane which consists of a graft copolymer to fall.

  In the above range, when the trunk polymer and the monomer of the general formula (3) are graft-polymerized, the molecular weight (Mn) of the graft chain is about 1000 to 50000, and the average molecular weight (Mn) of the graft copolymer is in terms of polystyrene. Therefore, it becomes about 20000-100,000, and the glass transition temperature becomes about 0-50 degreeC.

  In addition to the monomers of the general formulas (1) to (3), other monomers can be copolymerized as long as the effects of the present invention are not impaired. For example, a functional group-containing monomer having a polar functional group such as a carboxyl group, a hydroxyl group, a glycidyl group, an amide group, or an alkoxysilyl group can be copolymerized in order to impart functionality. Specific examples include silane coupling agents such as γ-methacryloxypropyltrimethoxysilane containing an alkoxysilyl group, methacrylic acid containing a carboxyl group, acrylic acid, glycidyl (meth) acrylate containing a glycidyl group, and a hydroxyl group. Hydroxy (meth) acrylate etc. can be illustrated. Only one type of functional group-containing monomer may be used, or two or more types may be copolymerized.

  In order to obtain a graft copolymer obtained by further copolymerizing a functional group-containing monomer, a trunk polymer is prepared by copolymerizing the monomer of the general formula (1), the monomer of the general formula (2), and the functional group-containing monomer. In addition, the monomer of the general formula (3) may be graft polymerized. Alternatively, the monomer of the general formula (1) and the monomer of the general formula (2) are copolymerized to prepare a trunk polymer, and the monomer of the general formula (3) is copolymerized with the functional group-containing monomer. It may be polymerized. Alternatively, a monomer of the general formula (1), a monomer of the general formula (2), and a functional group-containing monomer are copolymerized to prepare a trunk polymer, which is functionalized during graft polymerization of the monomer of the general formula (3) A group-containing monomer may be copolymerized.

  The graft copolymer thus obtained can be used in a wide range of applications, such as moisture-proof coatings for electronic substrates, chemical-resistant protective coatings that protect substrates from salt water, electrolytes, corrosive gases, etc. Oil barrier agent that prevents the diffusion of lubricating oil used for bearings, oil barrier agent that prevents the diffusion of lubricating oil used for fluid bearings of HDD motors, leakage preventing agents that prevent leakage of ink such as sign pens and ballpoint pens, connectors and electronics Antifouling agent for parts, anti-creeping agent for insulation resin, anti-adhesion agent for lead sealing resin of MF capacitor, anti-rust agent for metal parts, dry lubricant for guide rails such as DVD / CD, anti-reflection on surface Can be used for coating agents and waterproof spray stock solutions.

  When used as a coating agent, the graft copolymer is dissolved in a fluorinated solvent. As such a solvent, a partially fluorinated solvent such as hydrofluorocarbon and hydrofluoropolyether is suitable. Further, a mixture of two or more solvents as described above may be used. Moreover, you may use what mixed 2 or more types of the solution which melt | dissolved the graft copolymer. And as a coating method, well-known methods, such as a dipping method, a brush coating method, a spray method, and a roll coating method, are employable, and it can select suitably according to a production method and the form of parts. In addition, it is also possible to add various additives, such as antioxidant, a ultraviolet stabilizer, and a filler, to a coating solution in order to improve practicality.

  Moreover, at the time of forming the coating film, after applying the coating agent, it may be only dried at room temperature, or may be heat-treated. The graft copolymer of the present invention has flexibility when dried at room temperature and imparts hardness and rust resistance when heated. Therefore, depending on the presence or absence of heating, it can be properly used in two ways: use requiring flexibility, hardness or use requiring rust prevention. In particular, when a functional group-containing monomer is copolymerized, the effect of improving hardness and rust prevention by heating is remarkable.

  Since the graft copolymer of the present invention is dissolved in a non-flammable solvent, has high water and oil repellency, and has flexibility, it can be used in a wide range of applications such as a coating agent.

  Hereinafter, the present invention will be described in detail with reference to examples. In addition, this invention is not limited to a following example.

[Example Group 1]
A fluorine-containing monomer represented by the general formula (3) is added to the trunk polymer obtained by copolymerizing the (meth) acrylic acid ester represented by the general formula (1) and the acrylate ester represented by the general formula (2). A graft polymerized copolymer was prepared and tested.

1.1 Preparation of graft copolymer (graft copolymer 1)
100 g of cyclohexane, 61.9 g of methyl methacrylate, 0.6 g of 2-ethylhexyl acrylate, and 250 mg of azobisisobutylnitrile as a polymerization initiator were placed in a glass flask having an internal volume of 500 ml (methyl methacrylate and 2-ethylhexyl acrylate and The weight ratio of methyl methacrylate: 2-ethylhexyl acrylate = 99: 1). After setting the stirring blade, the lid, the condenser, and the thermometer in the flask, the system (inside the flask) was replaced with nitrogen. And it superposed | polymerized at 80 degreeC for 5 hours, stirring.

Subsequently, 250 mg of bis (4-t-butylcyclohexyl) peroxydicarbonate as an initiator was dissolved in 1 g of toluene, and this solution was added to the polymerization solution in the flask. Thereafter, 37.5 g of perfluorooctylethyl (meth) acrylate was added dropwise to the polymerization solution in the flask over 1 hour. Incidentally, perfluorooctyl ethyl (meth) acrylate, the above general formula (3), R ₄ is a methyl group, a compound of n = 8.

  After completion of the dropwise addition of perfluorooctylethyl (meth) acrylate, polymerization was continued for another 2 hours. Thereafter, the polymerization solution was heated under reduced pressure to remove the solvent. Thus, graft copolymer 1 was obtained. In the graft copolymer 1, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 62.5: 37.5 (weight ratio).

  In preparing the graft copolymer 1, the polymerization solution was separated into a supernatant and a precipitate by the reaction. And two types of polymers, a polymer derived from the supernatant and a polymer derived from the precipitate, were obtained.

(Graft copolymer 2)
It was prepared in the same manner as graft copolymer 1 except that 60.6 g of methyl methacrylate, 1.9 g of 2-ethylhexyl acrylate, and 37.5 g of perfluorooctylethyl (meth) acrylate were used. Therefore, methyl methacrylate: 2-ethylhexyl acrylate = 97: 3 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 62.5: 37.5 (weight ratio).

(Graft copolymer 3)
It was prepared in the same manner as graft copolymer 1 except that 53.1 g of methyl methacrylate, 9.4 g of 2-ethylhexyl acrylate, and 37.5 g of perfluorooctylethyl (meth) acrylate were used. Accordingly, methyl methacrylate: 2-ethylhexyl acrylate = 85: 15 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 62.5: 37.5 (weight ratio).

(Graft copolymer 4)
It was prepared in the same manner as Graft copolymer 1 except that 46.9 g of methyl methacrylate, 15.6 g of 2-ethylhexyl acrylate, and 37.5 g of perfluorooctylethyl (meth) acrylate were used. Accordingly, methyl methacrylate: 2-ethylhexyl acrylate = 75: 25 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 62.5: 37.5 (weight ratio).

(Graft copolymer 5)
It was prepared in the same manner as Graft Copolymer 1 except that 35.0 g of methyl methacrylate, 27.5 g of 2-ethylhexyl acrylate, and 37.5 g of perfluorooctylethyl (meth) acrylate were used. Therefore, methyl methacrylate: 2-ethylhexyl acrylate = 56: 44 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 62.5: 37.5 (weight ratio).

(Graft copolymer 6)
It was prepared in the same manner as Graft copolymer 1 except that 21.9 g of methyl methacrylate, 40.6 g of 2-ethylhexyl acrylate, and 37.5 g of perfluorooctylethyl (meth) acrylate were used. Therefore, methyl methacrylate: 2-ethylhexyl acrylate = 35: 65 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 62.5: 37.5 (weight ratio).

(Graft copolymer 7)
It was prepared in the same manner as graft copolymer 1 except that 18.7 g of methyl methacrylate, 43.8 g of 2-ethylhexyl acrylate, and 37.5 g of perfluorooctylethyl (meth) acrylate were used. Accordingly, methyl methacrylate: 2-ethylhexyl acrylate = 30: 70 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 62.5: 37.5 (weight ratio).

(Graft Copolymer 8)
A graft copolymer 1 was prepared in the same manner except that 72.7 g of methyl methacrylate, 24.3 g of 2-ethylhexyl acrylate, and 3.0 g of perfluorooctylethyl (meth) acrylate were used. Accordingly, methyl methacrylate: 2-ethylhexyl acrylate = 75: 25 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 97: 3 (weight ratio).

(Graft copolymer 9)
It was prepared in the same manner as Graft copolymer 1 except that 71.2 g of methyl methacrylate, 23.8 g of 2-ethylhexyl acrylate, and 5.0 g of perfluorooctylethyl (meth) acrylate were used. Accordingly, methyl methacrylate: 2-ethylhexyl acrylate = 75: 25 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 95: 5 (weight ratio).

(Graft Copolymer 10)
A graft copolymer 1 was prepared in the same manner except that 37.5 g of methyl methacrylate, 12.5 g of 2-ethylhexyl acrylate, and 50.0 g of perfluorooctylethyl (meth) acrylate were used. Accordingly, methyl methacrylate: 2-ethylhexyl acrylate = 75: 25 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 50: 50 (weight ratio).

(Graft copolymer 11)
A graft copolymer 1 was prepared in the same manner except that 15.0 g of methyl methacrylate, 5 g of 2-ethylhexyl acrylate, and 80 g of perfluorooctylethyl (meth) acrylate were used. Accordingly, methyl methacrylate: 2-ethylhexyl acrylate = 75: 25 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 20: 80 (weight ratio).

1.2 Evaluation Test of Solubility 10 g of each graft copolymer was put into 90 g of hydrofluorocarbon (manufactured by Mitsui DuPont Fluorochemical Co., Model No. V-XF) and stirred, and the solubility in a nonflammable solvent was examined.

1.3 Evaluation of Physical Properties of Graft Copolymer Film 1.3.1 Evaluation of Contact Angle The solution prepared in the solubility evaluation test was applied on a slide glass and then dried to form a graft polymer film. Contact angle CA-DT type manufactured by Kyowa Interface Science was used to measure the contact angle of each film (note that water and hexadecane were used for the measurement. The contact angle against water indicates the degree of water repellency, The contact angle of hexadecane indicates the degree of oil repellency).

1.3.2 Measurement of mechanical strength A film having a thickness of about 100 μm was prepared from each graft copolymer by a casting method, and the mechanical strength of strength, Young's modulus, and elongation was determined according to JIS K7127 / 2/50. Was measured.

1.3.3 Evaluation of adhesion A film was formed on a slide glass in the same manner as in the case of contact angle measurement. The slide glass with the film attached was immersed in water for 12 hours, and the state of the film was observed. Even after 12 hours, when the film adhered on the slide glass without peeling off, the film was rubbed with tissue paper, and the degree of adhesion was examined. The results were evaluated in five stages as follows.

A evaluation: Even after 12 hours, the film adheres to the slide glass without peeling off, and even if the film is rubbed with tissue paper, it does not peel off and does not deform.
B Evaluation: Although the film did not peel off and adhered to the slide glass even after 12 hours, it was deformed when the film was rubbed with tissue paper.
C evaluation: Even after 12 hours, the film adheres to the slide glass without peeling off, but peels off when the film is rubbed strongly with tissue paper.
D evaluation: Even after 12 hours, the film adheres to the slide glass without peeling off, but peels off when the film is gently rubbed with tissue paper.
E evaluation: The film has already peeled off the slide glass after 12 hours.

Moreover, in order to compare with the graft copolymers 1-11, also about the fluorine resin synthesize | combined by the following method, a film is produced similarly to the graft copolymers 1-11, a solubility evaluation test, the measurement of mechanical strength, The adhesion was evaluated. The method for synthesizing this fluororesin is as follows.
100 g of toluene, 80 g of perfluorooctylethyl metallate, 20 g of benzyl methacrylate, and 250 mg of azobisisobutylnitrile as a polymerization initiator were placed in a glass flask having an internal volume of 500 ml. After setting a stirring blade and a lid, and setting a cooling tube and a thermometer, the inside of the system was replaced with nitrogen, and polymerization was carried out at 80 ° C. for 5 hours. Thereafter, the solvent was removed by heating under reduced pressure.
In addition, a commercially available urethane resin (manufactured by Air Brown, model number 1A27) is prepared in the same manner as the graft copolymers 1 to 11, and a solubility evaluation test, a mechanical strength measurement, and an adhesion evaluation are performed. It was.
Moreover, also about a commercially available acrylic resin (the air brown company make, model number 1B66), a film is produced similarly to the graft copolymers 1-11, and a solubility evaluation test, a mechanical strength measurement, and adhesiveness evaluation are performed. It was.

1.3.4 Measurement of molecular weight Molecular weight was determined by GPC measurement (Shodex System 11, column; KF806, RI-8020, flow rate 1 ml / min, column temperature 40 ° C.). For the measurement, tetrahydrofuran was used as a solvent, and polystyrene standard was used as a reference.

1.4 Results The results are shown in Tables 1 and 2. In the table and the following description, methyl methacrylate is represented as “A”, 2-ethylhexyl acrylate is represented as “B”, and the weight ratio (methyl methacrylate: 2-ethylhexyl acrylate) is represented as A: B. Perfluorooctylethyl (meth) acrylate is represented as “C”, and the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount (weight ratio) of perfluorooctylethyl (meth) acrylate is (A + B): C It expresses.

As shown in Table 1, all of the graft copolymers 1 to 7 were soluble in hydrofluorocarbon. Thus, it turned out that the graft copolymer of this invention is soluble in a nonflammable solvent.
However, the polymer derived from the supernatant of the graft copolymer 1 was not completely dissolved, and insoluble matters remained. Therefore, it was found that from the viewpoint of solubility, it is desirable that B is larger than A: B = 97: 3. On the other hand, urethane resin and acrylic resin were insoluble in nonflammable solvents.
Moreover, it turned out that the graft copolymers 1-7 have the contact angle with respect to water and the contact angle with respect to hexadecane much higher than a urethane resin and an acrylic resin, and are excellent in water repellency and oil repellency.
In addition, as shown in Table 1, the film properties (mechanical properties) show that the strength and Young's modulus increase and the elongation tends to decrease as the proportion of methyl methacrylate (A) increases. However, any film of the graft copolymers 2 to 7 was not cracked even when sandwiched between chucks of a tensile tester. On the other hand, measurement of mechanical strength was attempted with the film obtained from the fluororesin, but when the film was brittle and a test piece for a tensile tester was prepared, a large number of cracks occurred in the test piece. The physical properties could not be measured.
Moreover, the film produced from the graft copolymer 1 was slightly brittle, and when the test piece of the tensile tester was produced, a few cracks were generated in the test piece, and physical properties could not be measured. . However, it was confirmed that the number of cracks in the test piece was less than that of the film obtained from the fluororesin, and the fragility was improved as compared with the film obtained from the fluororesin.
In addition, since the film produced from the graft copolymer 7 was too soft and stretched by its own weight in a state of being sandwiched between chucks of a tensile tester, the mechanical strength could not be measured. It could be used as an adhesive.
Therefore, from the above, it was confirmed that the graft copolymers 1 to 7 have improved brittleness as compared with the film obtained from the fluororesin.
Moreover, the film of the graft copolymer 3-6 copolymerized in the ratio of A: B = 85: 15-35: 65 has a Young's modulus of 1.1-250 MPa, and has a moderate softness | flexibility. Therefore, it was found that cracking is difficult to occur and it is not sticky, so that it is suitable for use as a coating agent. In addition, this ratio has good film adhesion in water, and the contact angle is 110 degrees or more with respect to water and 69 degrees or more with respect to hexadecane, and the water repellency and oil repellency are particularly excellent. I understood.

Next, the test results of the graft copolymers 8 to 11 in which (A + B): C are changed will be examined. As shown in Table 2, the graft copolymer 8 of (A + B): C = 97: 3 was not completely dissolved in an incombustible solvent, and insoluble matter remained. Therefore, from the viewpoint of solubility, it was found that graft polymers 9 to 11 having C of 5 (parts by weight) or more are desirable when (A + B + C) is 100 (parts by weight).
The graft copolymers 3 to 4 in Table 1 and the graft polymers 10 to 11 in Table 2 have a contact angle of 110 degrees or more with respect to water and 68 degrees or more with respect to hexadecane, and are water and oil repellency. Both are excellent. Therefore, it was found that in applications where water repellency or oil repellency is required, C is preferably 37.5 (parts by weight) or more when (A + B + C) is 100 (parts by weight).
In addition, the film produced from the graft copolymer 11 was a little brittle, and when the test piece of the tensile tester was produced, the test piece had some cracks, and physical properties could not be measured. . However, it was confirmed that the number of cracks in the test piece was less than that of the film obtained from the fluororesin, and the fragility was improved as compared with the film obtained from the fluororesin. Moreover, since the graft copolymer 11 was insoluble in tetrahydrofuran, the molecular weight could not be measured.

[Example group 2]
A copolymer obtained by further copolymerizing a functional group-containing monomer was prepared and tested.

2.1 Preparation of graft copolymer (graft copolymer 12)
100 g of cyclohexane, 53.1 g of methyl methacrylate, 9.4 g of 2-ethylhexyl acrylate, 0.625 g of 3-methacryloxypropyltrimethoxysilane (corresponding to a functional group-containing monomer), and 250 mg of azobisisobutylnitrile as a polymerization initiator, The flask was placed in a glass flask having an internal volume of 500 ml. Note that methyl methacrylate: 2-ethylhexyl acrylate = 85: 15 (weight ratio), and total amount of methyl methacrylate and 2-ethylhexyl acrylate: 3-methacryloxypropyltrimethoxysilane = 100: 1 (weight ratio). After setting the stirring blade, the lid, the condenser, and the thermometer in the flask, the system (inside the flask) was replaced with nitrogen. And it superposed | polymerized at 80 degreeC for 5 hours, stirring.

  Subsequently, 250 mg of bis (4-t-butylcyclohexyl) peroxydicarbonate as an initiator was dissolved in 1 g of toluene, and this solution was added to the polymerization solution in the flask. Thereafter, a mixed solution of 37.5 g of perfluorooctylethyl (meth) acrylate and 0.375 g of 3-methacryloxypropyltrimethoxysilane was added dropwise to the polymerization solution in the flask over 1 hour. Note that perfluorooctylethyl (meth) acrylate: 3-methacryloxypropyltrimethoxysilane = 100: 1 (weight ratio) in the mixed solution.

  After completion of the dropwise addition, polymerization was continued for another 2 hours. Thereafter, the polymerization solution was heated under reduced pressure to remove the solvent. In this way, a graft copolymer 12 was obtained. In the graft copolymer 12, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 62.5: 37.5 (weight ratio).

(Graft copolymer 13)
It was prepared in the same manner as graft copolymer 12 except that methacrylic acid (MAA) was used instead of 3-methacryloxypropyltrimethoxysilane.

(Graft copolymer 14)
It was prepared in the same manner as the graft copolymer 12, except that glycidyl methacrylate (GMA) was used instead of 3-methacryloxypropyltrimethoxysilane.

(Graft copolymer 15)
It was prepared in the same manner as graft copolymer 12 except that 46.9 g of methyl methacrylate, 15.6 g of 2-ethylhexyl acrylate, and 37.5 g of perfluorooctylethyl (meth) acrylate were used. Accordingly, methyl methacrylate: 2-ethylhexyl acrylate = 75: 25 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 62.5: 37.5 (weight ratio).

(Graft copolymer 16)
It was prepared in the same manner as the graft copolymer 15 except that methacrylic acid (MAA) was used instead of 3-methacryloxypropyltrimethoxysilane.

(Graft copolymer 17)
It was prepared in the same manner as the graft copolymer 15 except that glycidyl methacrylate (GMA) was used instead of 3-methacryloxypropyltrimethoxysilane.

(Graft copolymer 18)
A graft copolymer 12 was prepared in the same manner except that 31.25 g of methyl methacrylate, 31.25 g of 2-ethylhexyl acrylate, and 37.5 g of perfluorooctylethyl (meth) acrylate were used. Therefore, it is methyl methacrylate: 2-ethylhexyl acrylate = 50: 50 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 62.5: 37.5 (weight ratio).

(Graft copolymer 19)
Prepared in the same manner as graft copolymer 12 except that 21.9 g of methyl methacrylate, 40.6 g of 2-ethylhexyl acrylate, and 37.5 g of perfluorooctylethyl (meth) acrylate were used. Therefore, methyl methacrylate: 2-ethylhexyl acrylate = 35: 65 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 62.5: 37.5 (weight ratio).

(Graft Copolymer 20)
It was prepared in the same manner as Graft copolymer 1 except that 71.2 g of methyl methacrylate, 23.8 g of 2-ethylhexyl acrylate, and 5.0 g of perfluorooctylethyl (meth) acrylate were used. Accordingly, methyl methacrylate: 2-ethylhexyl acrylate = 75: 25 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 95: 5 (weight ratio).

(Graft Copolymer 21)
It was prepared in the same manner as graft copolymer 12 except that 33.75 g of methyl methacrylate, 11.25 g of 2-ethylhexyl acrylate, and 55.0 g of perfluorooctylethyl (meth) acrylate were used. Accordingly, methyl methacrylate: 2-ethylhexyl acrylate = 75: 25 (weight ratio). Further, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount of perfluorooctylethyl (meth) acrylate = 45: 55 (weight ratio).

(Graft Copolymer 22)
It was prepared in the same manner as graft copolymer 12 except that 3-methacryloxypropyltrimethoxysilane was not added.

(Graft Copolymer 23)
It was prepared in the same manner as the graft copolymer 15 except that 3-methacryloxypropyltrimethoxysilane was not added.

(Graft Copolymer 24)
It was prepared in the same manner as the graft copolymer 18 except that 3-methacryloxypropyltrimethoxysilane was not added.

(Graft copolymer 25)
It was prepared in the same manner as graft copolymer 20, except that 3-methacryloxypropyltrimethoxysilane was not added.

(Graft copolymer 26)
It was prepared in the same manner as graft copolymer 21 except that 3-methacryloxypropyltrimethoxysilane was not added.

(Random copolymer)
100 g of cyclohexane, 53.1 g of methyl methacrylate, 9.4 g of 2-ethylhexyl acrylate, 37.5 g of perfluorooctylethyl (meth) acrylate, 1.0 g of 3-methacryloxypropyltrimethoxysilane, and azobisisobutyl as a polymerization initiator 250 mg of nitrile was placed in a glass flask having an internal volume of 500 ml. After setting the stirring blade, the lid, the condenser, and the thermometer in the flask, the system (inside the flask) was replaced with nitrogen. And it superposed | polymerized at 80 degreeC for 5 hours, stirring.
Thereafter, the polymerization solution was heated under reduced pressure to remove the solvent. In this way, a random copolymer was obtained.

2.2 Evaluation of Physical Properties of Graft Copolymer Film 2.2.1 Pencil Hardness 10 g of each graft copolymer and random copolymer were placed in 90 g of hydrofluorocarbon and stirred to prepare a solution. This solution was applied on two glass slides, and one was dried at room temperature to form a film. The other was dried at room temperature and then heat treated at 120 ° C. for 1 hour to form a film.
About each sample, the pencil hardness test was done according to JISK5600-5-4.

2.2 Evaluation of Physical Properties of Graft Copolymer Film 2.2.2 Rust Prevention Test 2 g of each graft copolymer and random copolymer were placed in 98 g of hydrofluorocarbon and stirred to prepare a 2% solution. This solution was applied to iron (Fe content 99% or more) having a width of 50 mm, a length of 50 mm, and a thickness of 5 mm, and one was dried at room temperature to form a film. The other was dried at room temperature and then heat treated at 120 ° C. for 1 hour to form a film.
Each test piece thus prepared was immersed in 5% saline for 1 hour at room temperature and normal pressure. After completion of the immersion, the test piece was taken out from the saline solution, cut off, and left in a constant temperature and humidity chamber at 85 ° C. and 85% humidity for 100 hours to observe the occurrence of rust.
The results were evaluated in five stages as follows.

A evaluation: almost no rust is generated B evaluation: rust is generated within 20% of the whole C evaluation: rust is generated 20 to 40% of the whole
D evaluation: Rust generation is 40 to 70% of the total
E Evaluation: Rust generation is 70% or more of the whole 2.1.4 Results Tables 3 and 4 show the results. In the tables and the following description, methyl methacrylate is represented as “A”, 2-ethylhexyl acrylate as “B”, perfluorooctylethyl (meth) acrylate as “C”, and functional group-containing monomer as “D”. The weight ratio of methyl methacrylate to 2-ethylhexyl acrylate (methyl methacrylate: 2-ethylhexyl acrylate) is the total amount of A: B and methyl methacrylate and 2-ethylhexyl acrylate: perfluorooctylethyl (meth) acrylate. The amount (weight ratio) of (A + B): C, the total amount of methyl methacrylate and 2-ethylhexyl acrylate: the amount (weight ratio) of functional group-containing monomer (A + B): D, and perfluorooctylethyl (meta) ) The weight ratio of acrylate to functional group-containing monomer is represented as C: D.

  From Table 3 and Table 4, when it heat-processed, the tendency for surface hardness and an antirust performance to improve was seen rather than the case of only normal temperature drying. In particular, comparison of graft copolymers having the same weight ratio of monomers other than the functional group-containing monomer (that is, comparison between the graft copolymers 12 to 14 and 22, comparison with the graft copolymers 15 to 17 and 23, Comparison of graft copolymers 18 and 24, comparison of graft copolymers 20 and 25, comparison of graft copolymers 21 and 26), and surface hardness by heat treatment in a copolymer of functional group-containing monomers The tendency to improve the rust prevention performance was remarkable.

For comparison, a random copolymer having the same monomer weight ratio as that of the graft copolymer 3 was prepared and tested. Both the pencil hardness test and the rust prevention test were inferior to the graft copolymer 3. As a result.
Thus, it was found that the graft copolymer of this embodiment can improve the surface hardness and rust prevention performance by polymerizing a functional group-containing monomer as the fourth monomer and further performing a heat treatment.

  In addition, in the graft copolymer of this embodiment, the surface temperature and the antirust performance of the heating temperature are about 80 to 120 ° C., that is, the heat treatment at a much lower temperature than baking of a normal fluororesin coating (about 200 ° C.). Improvement can be expected. Therefore, even if the substrate is made of a material having no heat resistance such as plastic, the surface hardness and rust prevention performance can be imparted by using the graft polymer of this embodiment as a coating agent.

Claims (5)

A (meth) acrylic acid ester represented by the following general formula (1) and an acrylic acid ester represented by the following general formula (2) are represented by the following general formula (1): A backbone polymer obtained by copolymerization by a solution polymerization method at a weight ratio of acrylic ester represented by the following general formula (2) = 85: 15 to 35:65 is represented by the following general formula (3). A graft copolymer having a number average molecular weight of 20,000 to 100,000 obtained by graft polymerization of a fluorine-containing monomer using a solution polymerization method .

(In the formula, R ₁ is a methyl group, and R ₂ is a linear or branched alkyl group having 1 to 8 carbon atoms.)

(In the formula, R ₃ is a linear or branched alkyl group having 6 to 18 carbon atoms.)

(In the formula, R ₄ represents hydrogen or a methyl group, and n represents an integer of 1 to 12.) The weight ratio of the total amount of the (meth) acrylic acid ester represented by the general formula (1) and the acrylic acid ester represented by the general formula (2) and the monomer amount represented by the general formula (3) is The graft copolymer according to claim 1, wherein the total amount: the monomer amount represented by the general formula (3) is in the range of 95: 5 to 20:80. The graft copolymer according to claim 1 or 2, wherein a functional group-containing monomer having a polar functional group is further copolymerized. The coating agent containing the graft copolymer as described in any one of Claims 1 thru | or 3. A method for forming a coating film using the coating agent according to claim 4,
An application step of applying the coating agent to the substrate;
And a heating step of subjecting the applied coating agent to a heat treatment.