JPH03229772A - Coating composition for polyolefin resin - Google Patents

Abstract

PURPOSE:To improve the solubility in a solvent and other resins by reacting a propylene/alpha-olefin copolymer with an alpha,beta-unsaturated carboxylic acid, a specified reactive unsaturated compound, and a radical-polymerizable unsaturated compound in consecutive order. CONSTITUTION:At least 50mol% propylene is copolymerized with an alpha-olefin to give a propylene/alpha-olefin copolymer preferably comprising a random copolymer. The copolymer is grafted with 0.1-20wt.% alpha,beta-unsaturated carboxylic acid (anhydride) (e.g. maleic anhydride) in the presence of a radical generator at 100-180 deg.C, and the product is combined with a reactive unsaturated compound having at least one functional group selected from among hydroxy, glycidyl and amino groups (e.g. 2-hydroxymethyl acrylate), and then grafted with 5-70wt.% radical-polymerizable unsaturated compound (e.g. methyl methacrylate).

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to polyolefin resins used to improve adhesion when painting the surface of polyolefin or in-based resins or bonding other base materials. The present invention relates to a coating composition for

[Conventional technology]

Polyolefin resins have excellent properties and are inexpensive, so the demand for them in home appliances and automobile parts has been increasing year by year. However, polyolefin resins have the disadvantage that their surfaces are nonpolar and highly crystalline, making them difficult to paint and adhere to, and difficult to blend with other resins. Conventionally, in order to solve these drawbacks, it has been known to improve adhesion by subjecting the surface of polyolefin resins to chromic acid treatment, flame treatment, corona treatment, etc. in advance. However, these methods are gradually becoming less popular due to their complicated processing and the risk of fire.

Therefore, in order to perform painting and adhesion without performing such surface treatment, various primer compositions that are adhesive to polyolefins have been proposed. For example, the Special Public Interest Publication Act 1986-210
No. 27 discloses a surface treatment agent of a propylene-α-olefin copolymer modified with maleic acid. However, primer compositions in which polar groups are simply introduced into polyolefins have adhesion and solvent resistance, but have the disadvantage of poor sprayability, solubility, and compatibility. Furthermore, in order to solve these drawbacks, a method of radically graft copolymerizing the third component is also disclosed. for example,
JP-A-62-283134 discloses a method of graft copolymerizing a maleic acid-modified propylene-α-olefin copolymer with an unsaturated substance such as methyl methacrylate as a third component. However, the efficiency of graft copolymerization to polyolefin is extremely low, and unless a process such as purification is performed, the third component or polymer is incompatible with the main polymer, causing two-layer separation, and cannot be used as is.

In addition, Japanese Patent Publication No. 63-503111 discloses a chlorinated isotactic propylene modified with maleic acid.Those containing chlorine have the drawback of being somewhat inferior in UV resistance and solvent resistance. ing. In addition, JP-A-58-185655 discloses a method of introducing alcohol by esterification in order to improve the solubility of a propylene-α-olefin copolymer modified with maleic acid, but this method is fundamental. No solution has been reached.

[Problem to be solved by the invention]

When painting polyolefin resin molded products or adhering them to other substrates, it is practical to apply a primer treatment, but there are also issues with adhesion, weather resistance, solvent resistance, liquid stability, and spraying. At present, there is no primer composition that satisfies all of the suitability requirements. As a result of extensive studies to solve the conventional drawbacks, the present inventors have discovered that after graft copolymerizing 011 to 20% by weight of α, β-unsaturated carboxylic acid or its acid anhydride to propylene-α olefin copolymer. , at least one hydroxyl group.

The object is achieved by a coating composition for a polyolefin resin, which contains a resin obtained by graft copolymerizing a radically polymerizable unsaturated substance after bonding a reactive unsaturated substance having a glycidyl group or an amino group. did. Therefore, the first object of the present invention is to improve the solubility in a solvent by introducing a third component into a propylene-α-olefin copolymer by the above method.

The second purpose was to avoid the drawback that coating agents that simply introduced polar groups into propylene-α-olefin copolymers could not be used as inks or paints because they were not compatible with other resins. In order to achieve compatibility, the third component is selected depending on the purpose and graft copolymerized, thereby making it compatible with resins that were previously incompatible.

[Means to solve the problem]

The object of the present invention is to add 0 α,β-unsaturated carboxylic acid or its acid anhydride to a propylene-α-olefin copolymer.
After 1 to 20% by weight graft copolymerization, a part of the carboxyl group or acid anhydride group is esterified or amidated with a reactive unsaturated substance having at least one hydroxyl group, glycidyl group, or amino group to form a backbone polymer with 2 This was achieved by a coating composition for a polyolefin resin characterized by containing a resin obtained by introducing a double bond and graft copolymerizing a third component onto the double bond.

Propylene, which is a raw material for the coating composition of the present invention
The α-olefin copolymer is mainly composed of propylene and copolymerized with an α-olefin, and is preferably a random copolymer rather than a block copolymer. Examples of the α-olefin component include ethylene and 1-butene.

1-heptene, 1-octene, 1-hexene.

Examples include 1-decene and 4-methyl-1-pentene.

In the present invention, there is no particular restriction on the ratio of the propylene component to the α-olefin component in the copolymer, but it is desirable that the propylene component is 50 mol % or more. Also, α is graft copolymerized to the propylene-α olefin copolymer.

Examples of the β-unsaturated carboxylic acid or its acid anhydride include maleic acid, fumaric acid, itaconic acid, mesaconic acid, aconitic acid, and anhydrides thereof.

In the present invention, the amount of α,β-unsaturated carboxylic acid or its acid anhydride introduced by graft copolymerization is 01 to
The amount is 20% by weight, preferably 1 to 10% by weight.

If it is less than 0.01% by weight, the resulting composition will have poor solubility and poor adhesion to primers such as top coats, while if it is more than 20% by weight, adhesion to polyolefins will be poor.

α to the propylene-α-olefin copolymer.

A method for graft copolymerizing a β-unsaturated carboxylic acid or its acid anhydride is a method in which a propylene-α-olefin copolymer is heated and melted to a temperature higher than its melting point in the presence of a Rancar generator (melting method); This can be carried out by a known method such as a method in which a propylene-α-olefin copolymer is dissolved in an organic solvent and then reacted by heating and stirring in the presence of a Rancal generator (solution method). In the case of the melting method, the reaction is carried out in a short period of time at a temperature above the melting point and below 300° C. using a Banbury mixer-2 two-fold extruder, so it has the advantage of being easy to operate. On the other hand, in the solution method, it is desirable to use an aromatic organic solvent such as toluene or xylene as the organic solvent. The reaction temperature is 1
The temperature is 00 to 180°C, and it is characterized by having few side reactions and being able to obtain a uniform graft copolymer. The radical generator used in the reaction can be appropriately selected from known ones, but organic peroxide compounds are particularly preferred.

Examples of the above-mentioned organic peroxide compounds include hensyl peroxide, dicumyl peroxide, lauroyl peroxide, di-t'e'1-peroxide, tell-peroxybenz'ate, and cumene hydroperoxide. It will be done.

In the present invention, the carboxyl group or acid anhydride group possessed by the propylene-α-olefin copolymer obtained by graft copolymerizing α,β-unsaturated carboxylic acid or its acid anhydride has at least one hydroxyl group. It is also possible to form a chemical bond with a compound containing an amino group or a glycidyl group. Specifically, the above-mentioned reactive unsaturated substances having at least one hydroxyl group, amino group or glycidyl group used in the present invention include 2-hydroxyethyl acrylate (hereinafter abbreviated as 2HEA), 2-hydroxymethyl methacrylate (hereinafter abbreviated as 2HEMA),
Examples include monomers such as glycidyl methacrylate (hereinafter abbreviated as GMA) and acrylamide.

The number of functional groups of such a reactive unsaturated substance may be any number as long as it is one or more, but one or two is preferable since a large number may cause gelation due to crosslinking.

The method of introducing reactive unsaturation is to use propylene grafted with α, β unsaturated carboxylic acid or its acid anhydride.
Either the method of heating and melting the α-olefin copolymer above its melting point and reacting it, or the method of dissolving it in an organic solvent and reacting it, can be used. Is it possible to carry out the reaction using the same method and equipment as in the case of copolymerization reaction?Since remaining radicals attack double bonds, the radicals are sufficiently extinguished after 10 times the half-life of the radical generator. It may be carried out subsequent to the grafting reaction.

When the reactive unsaturated substance is introduced by a melting method, the reaction temperature is higher than the melting point of the polymer and lower than the boiling point of the reactive unsaturated substance, and the reaction time is 10 minutes to 3 hours.

When the reactive unsaturation is introduced by a solution method, the reaction temperature is 80 to 160°C and the reaction time is 1 to 20 hours.

When introducing reactive unsaturated substances by any method, it is desirable to use a catalyst such as an inorganic acid, an organic acid, or a tertiary amino acid. Of course, the reaction can also be carried out without using a catalyst.

By polymerizing the double bond introduced into the base polymer using the above method and a rancal polymerizable unsaturated substance that can be polymerized with the double bond in the presence of a radical generator, a third component such as methyl methacrylate or styrene can be made into a technical polymer. A homogeneous graft copolymer can be obtained.

The above-mentioned kraft copolymer may be polymerized by heating the propylene-α-olefin copolymer into which double bonds have been introduced above its melting point, or by dissolving it in an organic solvent and reacting it. The reaction can be carried out using the same method and apparatus as in the case of the graft copolymerization reaction of α,β-unsaturated carboxylic acid or its acid anhydride described above.

When the polymerization for grafting onto the double bonds introduced into the backbone polymer is carried out by a melting method, the reaction temperature is higher than the melting point of the polymer and lower than the boiling point of the polymerizable unsaturation, and the reaction time is 10 minutes to 3 hours. As a reaction device, a Banbury mixer, a kneader 1 extruder, etc. can be used. When graft polymerizing polymerizable unsaturated substances by a solution method, the reaction temperature is 0.
~160°C and reaction time is 1 to 20 hours. It is preferable to use an aromatic solvent such as toluene or quinoa for the solvent. The Rancar generator used in the reaction is an organic peroxide compound.

Azo compounds, sulfites, sulfines.

Diazo compounds, nitroso compounds, redox compounds, etc. can be used.

The unsaturated substance graft-copolymerized to the double bond introduced into the backbone polymer can be selected depending on the purpose of use as a coating composition, and specifically, styrene (hereinafter abbreviated as St).

Methyl methacrylate (hereinafter abbreviated as MMA).

Methyl acrylate (hereinafter abbreviated as MA), vinyl acetate (
(hereinafter abbreviated as VAc) etc. can be used.

By grafting these third components, solubility in organic solvents is improved and sprayability is also improved. For example, when styrene is used as the third component, the solubility in aromatic solvents is dramatically improved, and workability and sprayability are improved. In addition, when the third component is methyl methacrylate,
Improves compatibility with acrylic resin. The amount of mold to be kraft copolymerized in the present invention is 5 to 70% by weight, preferably 30 to 60% by weight. If the amount is less than 5% by weight, the effect of graft copolymerization will hardly appear, whereas if it exceeds 70% by weight, the adhesion to the polyolefin will be poor.

It goes without saying that the resin thus obtained can also be used in a solid state.

〔Example〕

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited thereto.

Example 1 A propylene-α-olefin copolymer (propylene component 75 mol%, ethylene component 20 mol%, 1-butene component 5 mol%, Number average molecular weight 17.00
0) After heating and dissolving 100 g in toluene +00 g, stirring while keeping the temperature of the system at 140°C, add maleic anhydride (Wako Pure Chemical's reagent grade 1) IOg and di-1ef1-butylper as a radical generator. 4 g of oxide (manufactured by NOF Corporation) was added dropwise over 2 hours, and then aged for 3 hours. After the reaction, the reaction product was cooled to room temperature and purified by pouring it into 201ml of acetone to obtain a maleic anhydride graft copolymer with a graft amount of 62% by weight. Next, 100 g of the obtained maleic anhydride graft copolymer was heated and dissolved in a 2-hydroxyl methyl acrylate (Wako Pure Chemical Industries, Ltd.) solution to form a 20% by weight toluene solution.
g and 0.5 g of para-toluenesulfonic acid as a catalyst.
After adding g, the mixture was reacted at 100°C for 5 hours. Analysis of the purified reaction product using an infrared spectrophotometer confirmed that it had been completely esterified.

Subsequently, 100 g of toluene was added in the above reaction vessel, and while keeping the temperature at 100°C, a solution of 0.5 g of benzyl peroxide (manufactured by NOF Corporation) in 10 g of toluene and methylmethacryl-11-5 (2 I each) were added.
I let it drip over time. The obtained copolymer was a homogeneous pale yellow viscous liquid.

Examples 2 to 8 Coating compositions for polyolefin resins were obtained in the same manner as in Example 1 using the raw materials and reactive unsaturated substances listed in Table 1.

Comparative Examples 1-2 A coating composition for polyolefin resin was obtained in the same manner as in Example 1 except that no reactive unsaturated substance was used.

Comparative Example 3 Maleic anhydride was added to isotactic polypropylene for 5 minutes.
This is a coating composition for a polyolefin resin having a degree of chlorination of 20% by weight, which is obtained by graft copolymerizing by weight%, dissolving it in carbon tetrachloride, and chlorinating it by blowing chlorine gas.

Comparative Example 4 A coating composition for a polyolefin resin in which 46% by weight of maleic anhydride was graft copolymerized onto a propylene-α-olefin copolymer.

Examples 12 to 16 350 g of the resin obtained in Examples 1 to 5, 20% by weight toluene solution, and 30 g of titanium oxide were mixed, the pigment was dispersed in a sand mill for 1 hour, and then diluted with an aromatic solvent to an appropriate viscosity. It was then spray applied to a polypropylene plate whose surface had been cleaned with toluene.

After being left to dry at room temperature for about 10 minutes, a two-component urethane paint was spray applied and left to dry at room temperature for about 10 minutes. Next, it was force-dried at 80° C. for 30 minutes using a hot air dryer. The obtained coated plates were allowed to stand at room temperature for 7 days, and then the coating film was tested. The results are shown in Table 2.

The appearance, adhesion, gasoline resistance, and moisture resistance of the coating film were evaluated as follows.

Appearance of paint film The appearance of the coating film was visually observed.

Make cuts in the surface of the adhesive coating film with a cutter to reach the substrate at 1 mm intervals to make 100 base marks, then stick cellophane adhesive tape on top of it and peel it off in 1800 directions to cut out the remaining base marks. I counted.

A cut was made on the surface of the gasoline-resistant coating film to reach the substrate, and after immersion in Regular Kallin for 4 hours, the condition of the coating film was visually observed.

Moisture Resistance After immersing in 50°C warm water for 240 hours, the condition of the coating film was visually observed.

2 g/rr for the resin film that adheres to the film? After the coating was applied and left for one day and night, a cellophane adhesive tape was adhered thereto and peeled off in a 180° direction, and the surface condition was visually observed.

Low-temperature fluidity A 20% by weight toluene solution was prepared and allowed to stand at -5°C for one day and night, and then the fluidity was visually observed.

Compatibility A 20% by weight toluene solution was prepared and the same 20% by weight polymethyl methacrylate (number average molecular weight 12,000) was added.
After mixing with a toluene solution at a ratio of 1:1 and leaving it for one day and night, the liquid state was visually observed.

〔Effect of the invention〕

The coating composition for a polyolefin resin of the present invention is produced by graft copolymerizing a propylene-α-olefin copolymer with an α,β-unsaturated carboxylic acid or an acid anhydride thereof, and then at least one hydroxyl group, glycidyl group, or amino acid. Since the radical-polymerizable unsaturated substance is graft-copolymerized after bonding the reactive unsaturated substance having a group, it has good solubility in organic solvents and excellent sprayability and compatibility. Therefore, even when used in combination with other polymer compounds, stable performance can be obtained without separation into two layers.

Procedural amendment (self) from)

Claims (2)

[Claims] (1) In the propylene-α-olefin copolymer, α, β
- After graft copolymerizing an unsaturated carboxylic acid and/or its acid anhydride, and after bonding a reactive unsaturated substance having at least one hydroxyl group, glycidyl group, or amino group, a radically polymerizable unsaturated substance is grafted. A coating composition for a polyolefin resin, characterized by containing a resin obtained by copolymerization. (2) For propylene-α-olefin copolymer, 0
．． 1 to 20% by weight of α,β-unsaturated carboxylic acid and/or
2. The composition according to claim 1, which is obtained by graft copolymerizing or an acid anhydride thereof. (3) The composition according to claim 1 or 2, wherein 5 to 70% by weight of a radically polymerizable unsaturated substance is graft copolymerized.