JPH0352983A - Coating composition for polyolefinic resin - Google Patents

Abstract

PURPOSE:To provide the subject composition having an improved adhesive force and solubility in organic solvents by using a resin prepared by graft- copolymerizing an alpha,beta-unsaturated dicarboxylic acid (anhydride) to a propylene-alpha-olefinic copolymer and subsequently esterifying the grafted copolymer. CONSTITUTION:A propylene-alpha-olefinic copolymer preferably containing >=50mol% of the propylene component is graft-copolymerized with 0.1-20wt.% of an alpha,beta-unsaturated dicarboxylic acid (anhydride) such as maleic acid, itaconic acid or mesaconic acid. A part of the carboxyl groups or acid anhydride groups of the prepared graft copolymer are esterified with a compound such as a >=5C higher alcohol having one or more hydroxyl groups, an oligomer or polymer thereof. The prepared resin is used to provide the objective coating composition.

Description

[Detailed Description of the Invention] <<Industrial Application Field>> The present invention is used for coating the surface of a polyolefin resin or shaped article, or for adhesion when adhering another base material to a polyolefin resin or shaped article. Concerning a coating used to improve strength.

(Prior Art) Since polyolefin resins have excellent properties and are inexpensive, their use in home appliances, automobile parts, etc. has been increasing recently. However, since polyolefin resins are nonpolar or highly crystalline, they have the disadvantage that they are difficult to paint or adhere to other substrates. In order to solve these drawbacks, conventionally, when painting or bonding polyolefin-based resin products to other base materials, treatments such as flame treatment and corona discharge treatment have been applied to the surface to improve adhesion. However, such processing has the disadvantage that the processing operations are complicated, and in the case of crystals with complex shapes, it cannot be processed uniformly, making it impractical.

Therefore, in order to improve painting and adhesion without performing such surface treatment, various primer compositions that are adhesive to polyolefin resins have been proposed. For example, in Japanese Patent Publication No. 62-21027, propylene
Brymer &l1 Kaimono, which is a graft copolymer of maleic acid or its anhydride on an ethylene copolymer, has been disclosed.
However, although the above-mentioned brimer has excellent adhesion, weather resistance, and solvent resistance, it has poor solubility in solvents, so granular undissolved substances grow during storage, which causes problems in the coating film. There are disadvantages in that granular irregularities occur on the surface, which significantly impairs the appearance or deteriorates spray applicability, and the resulting coating film becomes non-uniform, resulting in variations in adhesion.

Moreover, in Japanese Patent Publication No. 11250/1983, α
-Olefin copolymers have been disclosed, but monoolefin dicarboxylic acid monoalkyl esters have poor grafting efficiency in grafting reactions and lack practicality. Furthermore, when esterified with a lower alkyl alcohol such as methanol, the solubility is improved to some extent, but there is still no product that solves the above-mentioned drawbacks such as poor storage stability and poor sprayability. is the actual situation. Furthermore, JP-A No. 62-283134 discloses a composition in which an unsaturated heptanomer containing a functional group is graft-polymerized to an ethylene-propylene copolymer graft-polymerized with maleic acid, but the grafting efficiency is low. Due to the low molecular weight, the obtained copolymers have the disadvantage of poor solubility in solvents and sprayability, similar to the above-mentioned ones. For a series of graft copolymerizations as described above, methods of using a chlorinated modified polypropylene containing a carboxyl group are known, for example, in Japanese Patent Publication Nos. 10916-1982, 36128-1983, and 63-198. It is disclosed in No. 36624 and the like.

However, brimers made of these chlorinated compounds have a common drawback of good adhesion to polyolefins but poor weather resistance and solvent resistance, and are suitable for outdoor applications that require weather resistance and automobiles that require gasoline resistance. It has the disadvantage that it cannot be used for any purpose and its uses are extremely limited.

《Problems to be solved by the invention〉 As mentioned above, it is practical to apply a brimer treatment when painting polyolefin resin shaped products or bonding other base materials, but the adhesion and Weather resistance, solvent resistance,
Currently, there is no brimer assembly or material that satisfies all of the requirements such as liquid stability and sprayability, and further improvements have been desired.

As a result of intensive studies to solve the conventional drawbacks, the present inventors have discovered that α,β
By graft copolymerizing a monounsaturated dicarboxylic acid or its acid anhydride, and further bonding a compound having 5 or more carbon atoms to the carboxyl group or acid anhydride group contained in this copolymer through an ester bond, it can be used in organic solvents. The present invention was achieved by discovering that the solubility was dramatically improved and the sprayability was further improved. Accordingly, a first object of the present invention is to provide a coating film or material suitable for coating the surface of a polyolefin resin or molded product.

A second object of the present invention is to provide a coating assembly suitable as a brammer for use in bonding other substrates to polyolefin resin shaped articles. <Means for solving problems> The above objects of the present invention are to graft 0.1 to 203 lil% of α,β monounsaturated dicarboxylic acid or its acid anhydride to a propylene-α-olefin copolymer. A polyolefin system characterized by containing a resin obtained by copolymerizing and then esterifying a part of the carboxyl group or acid anhydride group with a compound having at least one hydroxyl group and having 5 or more carbon atoms. The precepts were attained by the resin coating group precepts. The brobylene-α-olefin copolymer, which is the raw material for the coating composition of the present invention, is mainly composed of propylene and copolymerized with α-olefin, and in particular, a random copolymer is better than a block copolymer. preferable. α
- Examples of olefin compounds include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and 4-methyl-1-bentene. In the present invention, the ratio of the propylene component to the α-olefin component in the copolymer is not particularly limited, but it is preferable that the brobylene component is 50 mol % or more.

Further, examples of the α,β monounsaturated dicarboxylic acid or its acid anhydride to be graft copolymerized to the propylene-α-olefin copolymer include maleic acid, fumaric acid, itaconic acid,
Examples include citraconic acid, allylsuccinic acid, mesaconic acid, aconitic acid and anhydrides thereof. α, β one un##
Ester of dicarboxylic acid can also be grafted, but the grafting efficiency is poor and it is not practical.

In the present invention, the amount of α,β monounsaturated dicarboxylic acid or its acid anhydride introduced by graft copolymerization is 0.1
~20% by weight, preferably 1~10% by weight. If it is less than 0.1% by weight, the resulting compound will have poor solubility and the adhesion of the top coat to the primer will be poor, and if it is more than 20% by weight, the adhesion to polyolefin will be poor. Propylene-α-olefin copolymer has α. The method of graft copolymerizing β-unsaturated dicarboxylic acid or its acid anhydride is a method of reacting by heating and melting a propylene-α-olefin copolymer above its melting point in the presence of a radical generator (melt 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 heated and stirred in the presence of a radical generator to react (solution method). In the case of the melting method, the reaction is carried out at a temperature above the melting point and below 300°C using a Banbury ξ mixer, kneader, extruder, etc., so the operation is simple and the reaction can be completed in a short time. There are advantages. On the other hand, in the solution method, it is preferable to use an aromatic solvent such as toluene or xylene as the organic solvent. The reaction temperature is 100 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 radical generators, but organic peroxides are particularly preferred.

Examples of the organic peroxides include penzoyl peroxide, dicumyl peroxide, lauroyl peroxide, 2,5-dimethyl-2,5-di(t-7'tilveroxy)-hexyne-3-di-t-butylperoxide, oxide, t-butyl hydroperoxide, t-butyl peroxybenzoate, cumene hydroperoxide, and the like. The carboxyl group or acid anhydride group possessed by the brobylene-α-olefin copolymer obtained by graft copolymerizing α,β-monounsaturated dicarboxylic acid or its acid anhydride in the present invention is a compound containing at least one hydroxyl group. It is possible to form a bond with an ester.

In the present invention, as the above-mentioned compound having at least one hydroxyl group, a compound having 5 or more carbon atoms is used. When the number of carbon atoms is 4 or less, the effect of improving solubility in a solvent is small. Any substance having 5 or more carbon atoms is effective, and alcohols, diols, oligomers or polymers with hydroxyl groups, etc. can be used. Specifically, amyl alcohol, hexyl alcohol, hebutyl alcohol, octyl alcohol, Aliphatic alcohols such as nonyl alcohol and decyl alcohol; alicyclic or aromatic alcohols such as cyclohexanol and benzyl alcohol; diols such as pentanediol, hexanediol, heptanediol, octanediol, cyclohexanediol, and cresol; Examples include oligomers with hydroxyl groups or macromers with hydroxyl groups at the ends, liquid polybutadienes with hydroxyl groups at the ends, polyolefins with hydroxyl groups at the ends, and higher alcohols, oligomers, or polymers are particularly effective and preferred. The number of hydroxyl groups in such a compound may be any number as long as it is one or more, but
If the number is large, gelation may occur due to crosslinking during esterification, so it is preferable that the number is one or two. α. The amount of esterification of propylene-α-olefin copolymer obtained by graft copolymerizing β-monounsaturated dicarboxylic acid or its acid anhydride with a compound having a hydroxyl group is not particularly limited; substance base 2
The content is preferably 5 mol% or more. The esterification method is a method in which a propylene-α-olefin copolymer obtained by graft copolymerizing α, β-unsaturated dicarboxylic acid or its acid anhydride is heated and melted above the melting point to react, or a method is carried out by dissolving it in an organic solvent. It can be carried out using the same method and apparatus as in the case of the graft copolymerization reaction of α,β monounsaturated dicarboxylic acid or its acid anhydride, and following the graft reaction, You can go. When esterification 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 compound having a hydroxyl group, and the reaction time is 10 minutes to 3 hours.

The reaction temperature when esterification is carried out by a solution method is 80
˜160° C. and reaction time is 1 to 20 hours.

When carrying out the esterification reaction by either method, it is preferable to use a catalyst such as an inorganic acid, an organic acid, or a tertiary amine. Of course, it is also possible to carry out the reaction without using a catalyst. Furthermore, since water is produced when a compound with a hydroxyl group is esterified with a carboxyl group, it is desirable to remove the produced water from the system in order to accelerate the reaction. In addition, α. The technique of graft copolymerizing a β-unsaturated dicarboxylic acid and then grafting a polymer by an intermolecular reaction has been known in the field of resin modifiers, for example, as disclosed in JP-A-60-233131. However, this technology belongs to a completely different technical field from the present invention. That is, in the use of these modifying materials,
If the propylene-α-olefin copolymer used in the present invention is used as a raw material, its strength will be weakened, so it is not used, and the compounds to be reacted during esterification are also low-molecular compounds such as those used in the present invention. It is mainly composed of high molecular weight polymers. Therefore, the graft copolymer used as a modifier is different from the one used in the present invention, and has a decisive difference in that it shows no solubility in organic solvents.

The resin obtained in the present invention has good solubility in organic solvents. Although the reason for the improved solubility is not necessarily clear, it is presumed that the side chains formed by esterification prevent crystallization of the polymer main chain.

By using such a resin with good solubility as a coating material, there will be no granular undissolved substances during storage of the coating material, so when it is used as a paint, it will be smooth and smooth. Not only can it form a coating film, but when used as a brimer, it has good suitability for spray application, so it can be applied evenly, resulting in stable performance with no variation in adhesion.
The coating of the present invention, I-Kyomono, is used in a state dissolved in an organic solvent, and the concentration of the resin of the present invention is 1 to 40% by weight.
It is. 40! Exceeding this amount is undesirable because particulate undissolved substances may be produced at low temperatures. As the organic solvent, it is preferable to use an aromatic solvent. In addition, other resins such as olefin resins, acrylic resins, epoxy resins, urethane resins, and alkyd resins may be added, and further,
Additives such as ultraviolet absorbers and antioxidants may be added as necessary.

Furthermore, pigments can be dispersed in the coating composition of the present invention by known methods. Coating can be done by brushing or spraying to create a smooth coating on the surface of the polyolefin resin.

In addition, the polyolefin resin in the present invention includes polyethylene, polypropylene, ethylene propylene copolymer,
Although the coating composition of the present invention has an ester structure,
It is also possible to apply it to plastics other than polyolefin resins, and it is particularly suitable for use with polyester resins because of its strong adhesion.

Needless to say, the coating composition of the present invention can be used not only as a primer but also as a vehicle for printing ink for polyolefin films. <<Effects of the Invention>> The coating composition for polyolefin resin of the present invention has α. Since it has a structure in which a compound having 5 or more carbon atoms is bonded to the carboxyl group or acid anhydride group through an ester bond after graft copolymerizing β-unsaturated dicarboxylic acid or its acid anhydride, it is not susceptible to organic solvents. It has good solubility and excellent storage stability and spray suitability. Therefore, when applied as a coating for polyolefin resin molded products or as a brimer for adhering other base materials, stable performance can be obtained without variations in adhesion due to its excellent spray application suitability. <<Examples> The present invention will be specifically explained below using Examples, but the present invention is not limited thereto. Example 1. Propylene-α-olefin copolymer (propylene content 75 mol%, number average molecular weight 17,000) 100 in a three-necked flask equipped with a stirrer, condenser, and dropping funnel.
After heating and dissolving g in 400 g of toluene, log maleic anhydride and 2 g of dicumyl peroxide were added dropwise over 2 hours each while stirring while maintaining the temperature of the system at 140° C., and then allowed to react for 3 hours. After the reaction was cooled to room temperature, the reaction product was poured into a large amount of acetone for purification.
A maleic anhydride graft copolymer with a graft amount of 6.2% by weight was obtained. Next, the obtained maleic anhydride graft copolymer 100
Heat and dissolve g in a three-necked flask to make a 20% by weight toluene solution, and add 7 g of octyl alcohol to make a 120"
The reaction was carried out at C for 5 hours. Analysis of the reaction product using an infrared spectrophotometer confirmed that it was completely esterified. A 20% by weight toluene solution of the obtained copolymer was transparent, no undissolved matter was observed, and exhibited fluidity even when stored in an environment of -5°C.

Examples 2-8. The raw materials shown in Table 1, α. A coating resin was obtained in the same manner as in Example 1 using a β-unsaturated dicarboxylic acid and a compound having a hydroxyl group. The physical properties of the obtained resin are shown in Table 1. The hydroxyl group-terminated styrene oligomers used in Table 1 were obtained by known methods such as living polymerization or radical polymerization, and had a molecular weight of 1,200. Furthermore, the hydroxyl group-terminated polybutadiene used had a molecular weight of II,000. Comparative Examples 1 to 4 Using the raw materials shown in Table 1, an α,β monounsaturated dicarboxylic acid, and a compound having a hydroxyl group, the same operation as in Example 1 was performed to obtain a resin for coating compositions. ．． In addition, comparative example l
and 2, no esterification was performed. The physical properties of the obtained resin are shown in Table 1. The storage stability was evaluated by storing the resulting resin solution in a sealed container at room temperature for 3 months, and then examining the solution for any precipitates or suspended matter. Examples 1 to 8 are 20% by weight toluene solutions, and Comparative Examples 1 to 4 are 7% by weight toluene solutions.

Examples 9-16. 350 g of the resin obtained in Examples 1 to 8 (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. Then, it was spray-coated onto 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 stand at room temperature for 10 minutes. Next, it was force-dried at 80°C for 30 minutes using a hot air dryer. The obtained coated board was left at room temperature for 7 days, and then the coating film was tested. The results are shown in Table 2. Furthermore, V! The appearance, adhesion, gasoline resistance, moisture resistance, and water resistance of the film were evaluated as follows.

Appearance of paint film: W! ! The appearance of the film was visually observed.

Adhesion: Cut the coating surface with a cutter to make 100 goblets that reach the substrate at 1m intervals.Place cellophane adhesive tape on top of it and peel it off in a 180° direction to determine the number of remaining goblets. was measured. Gasoline resistance: A cut was made on the surface of the coating film to reach the substrate, and after soaking in regular gasoline for 4 hours, the condition of the coating film was visually observed.

Humidity resistance: After being left in an atmosphere of 50°C1 relative humidity of 95% or more for 240 hours, the condition of the coating film was visually observed. Water resistance: After being immersed in hot water at 50°C for 240 hours, the condition of the coating film was visually observed. Comparative Examples 5-8. Coated plates were prepared using the resins obtained in Comparative Examples 1 to 4 (7% by weight toluene solution) in the same manner as in Examples 9 to 16, and coating and film tests were conducted. The results are shown in Table 2. As shown. In the case of the resin of Comparative Example 8, the resin did not dissolve and a primer assembly could not be prepared.

Claims (1)

[Claims] After graft copolymerizing 0.1 to 20% by weight of α,β-unsaturated dicarboxylic acid or its acid anhydride to a propylene-α-olefin copolymer, at least a portion of the carboxyl group or acid anhydride group is A coating composition for a polyolefin resin, comprising a resin obtained by esterification with a compound having one hydroxyl group and a carbon number of 5 or more.