JPH04320474A - Adhesive composition for polyolefin - Google Patents

Abstract

PURPOSE:To obtain the title composition which is excellent in adhesiveness, is improved in durability at high temperature and can perform pressure-sensitive bonding between a difficulty bonded polypropylene and a material of a different kind without the necessity for mechanically or physically treating the surface of the polypropylene or priming it. CONSTITUTION:The title adhesive is prepared by mixing 100 pts.wt. (in terms of the solid matter) tackifying resin having a softening point of 30-180 deg.C and a high degree of hydrogenation with 5-100 pts.wt. (in terms of the solid matter) transparent toluene solution (solid matter content of 15-65%) of chlorinated polypropylene of a degree of chlorination of 15-45wt.% and 100-300 pts.wt. (in terms of the solid matter) acrylic emulsion having a glass transition temperature (Tg) of -5 to -60 deg.C and a gel content of 60-90wt.%.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to, for example, weak electrical parts,
This invention relates to a water-based emulsion type pressure-sensitive adhesive used for adhering polypropylene and dissimilar materials, particularly among polyolefin materials that are difficult to adhere to and are used as automobile interior parts. More specifically, the present invention relates to an aqueous emulsion type pressure-sensitive adhesive used in an adhesive method in which the adhesive is applied to polyolefin, and after a solvent is scattered, different materials are pressed together using a press or the like.

0002

[Prior Art] Conventionally, adhesion of polyolefin-based materials, which are difficult to bond, has been achieved by physically treating the surface of the polyolefin itself with corona discharge, plasma treatment, etc., degreasing with alcohol, and then using urethane. The mainstream method was to perform a primer treatment using a rubber-based or chloroprene rubber-based adhesive, and then adhere using a solvent-based adhesive of the same type. In addition, research has been conducted on water-based emulsion type adhesives due to the need for non-polluting types. For example, in Japanese Patent Application Laid-Open No. 1-174579, chlorinated modified polypropylene is dissolved in toluene,
In JP-A No. 1-107869, a surfactant is added, water is added, the mixture is made into an aqueous emulsion, the solvent is removed, and the mixture is blended into an acrylic emulsion.
0/W type, a combination of emulsified and dispersed chlorinated polypropylene and acrylic emulsion has been proposed as an adhesive for electrostatic flocking, but in all of these adhesives, the dry coating film is not pressure sensitive. Therefore, it was not suitable for bonding with non-porous dissimilar materials such as plastic films.

0003

Problems to be Solved by the Invention In the above-mentioned conventional bonding methods, the surface treatment of the polyolefin was required in advance, and primer treatment was also indispensable. On the other hand, as for adhesives, solvent-based adhesives are the mainstream, and organic solvents have a high risk of adverse effects on the human body, environmental pollution, fire, etc.
Already proposed aqueous emulsion types lack adhesion to polyolefins and peel off from the polyolefin interface, resulting in low adhesive strength and poor durability. In addition, pressure sensitivity is insufficient, and the types of different materials that can be bonded are limited to porous materials.

0004

[Means for Solving the Problems] The present inventors have developed an approach to improve the adhesion and adhesion of polyolefin materials, especially polypropylene, to different materials without performing surface treatment or primer treatment on the polypropylene. As a result of extensive research aimed at imparting strength and durability, we found that it is extremely effective to blend an acrylic emulsion with a low glass transition temperature and high gel content into a mixture of tackifying resin and chlorinated polypropylene. They discovered this and completed the present invention.

That is, the present invention provides a) a chlorinated polypropylene solution with a solid content of 5 to 100 parts by weight, and an acrylic emulsion with a solid content of 100 to 30 parts by weight, based on 100 parts by weight of the solid content of the tackifying resin.
An adhesive composition for polyolefin comprising 0 parts by weight. b) Item a) above, characterized by using a transparent solution in which the chlorination rate of the chlorinated polypropylene is 15 to 45% by weight and the solid content of the toluene solution of the chlorinated polypropylene is 15 to 65% by weight. Adhesive composition for polyolefins as described. c) Glass transition temperature (Tg (℃) of acrylic emulsion
)) is -5 to -60°C, the adhesive composition for polyolefin as described in item a) above. d) The adhesive composition for polyolefin as described in item a) above, wherein the gel content of the acrylic emulsion (toluene-insoluble portion of the acrylic polymer) is 60 to 90% by weight.

The tackifying resin used in the present invention includes, for example, natural or polymerized rosin, modified rosin, and hydrogenated rosin glycerin ester, triethylene glycol ester,
Rosin-based tackifying resins represented by pentaerythritol ester, terpene-based resins represented by α-pinene, β-pinene, diterpene, and terpene phenol, aliphatic petroleum resins, aromatic petroleum resins, and resins. Examples include resins having a softening point of 30 to 180°C, such as cyclic hydrocarbon resins, alkylphenol resins, coumaron indene resins, and xylene resins. The purpose of using this tackifying resin is to impart pressure sensitivity and improve adhesion to polyolefins, with a softening point of 5.
Rosin or a hydrogenated alicyclic hydrocarbon resin having a temperature in the range of 0 to 130°C is preferred. When the softening point is below 30°C, the adhesive strength is low, and when it is above 180°C, a stable adhesive formulation cannot be obtained. When a resin with a low degree of hydrogenation is used, problems arise in terms of durability such as discoloration and a decrease in adhesive strength over time, which is a practical problem.

The chlorinated polypropylene (hereinafter abbreviated as chlorinated PP) solution used in the present invention refers to polypropylene monomer or 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene. , 3-methyl-1-pentene, etc. are crushed, heated to 70 to 80°C as an aqueous suspension, and brought into contact with molecular chlorine, or dissolved in a chlorine-based solvent that is stable against chlorine. However, it refers to a chlorinated PP polymer obtained by contacting with molecular chlorine, the solvent removed, and redissolved in toluene. The purpose of using this chlorinated PP solution is to impart adhesion to polyolefin and to dissolve the tackifying resin. The blending ratio of this chlorinated PP solution is:
5 parts by solid content per 100 parts by weight of solid content of tackifying resin
-100 parts by weight, preferably 10-50 parts by weight. If it is less than 5 parts by weight, it will lack adhesiveness to polypropylene and pressure sensitivity, and if it is more than 100 parts by weight, the stability of the adhesive formulation will decrease and it will lack practicality. The chlorination rate of the present chlorinated PP is in the range of 15 to 45% by weight, preferably in the range of 20 to 35% by weight. If it is less than 15% by weight, it lacks solubility in toluene, becomes a gel-like, cloudy, and highly viscous product that lacks stability, and does not improve adhesion to polypropylene. If the amount is more than 45% by weight, the adhesion to polypropylene decreases and at the same time the stability of the adhesive composition becomes defective, which poses a practical problem. The solvent of this chlorinated PP solution is toluene, and the solid content is 15 to 65% by weight. Preferably, the range is 20 to 45% by weight. When it is less than 15% by weight, the adhesive formulation lacks stability and furthermore, it leads to a decrease in concentration, which is a practical problem, and when it is more than 65% by weight, it is difficult to dissolve and mix the tackifying resin, and at the same time it is difficult to formulate the adhesive. Lack of stability of things. In addition, the present chlorinated PP solution is a transparent solution, and opaque or gel-like substances are a practical problem because they significantly impair the stability of the adhesive formulation.

The acrylic emulsion used in the present invention includes, for example, ethyl acrylate, butyl acrylate,
The main component is 2-ethylhexyl acrylate, etc., and the glass transition temperature (hereinafter abbreviated as Tg) is -5 to -60.
℃ range and a gel content in the range of 60 to 90% by weight. The purpose of using such an acrylic emulsion is to impart adhesion, pressure sensitivity, adhesive strength, and durability to polyolefins. The blending ratio of the tackifier resin in the emulsion to 100 parts by weight of solid content is in the range of 100 to 300 parts by weight as solid content. If it is less than 100 parts by weight, the adhesive formulation will lack stability and adhesive strength will be low;
If the amount is more than 0.00 parts by weight, the adhesion to polypropylene will be poor and the object of the present invention will not be achieved. The emulsion preferably has a Tg in the range of -30 to -55°C and a gel content in the range of 70 to 85%. If the Tg is higher than -5°C, not only does it lack compatibility with the tackifying resin and the stability of the adhesive formulation is impaired, but it also lacks adhesion to polypropylene, and pressure sensitivity cannot be obtained. . Also, T
When g is -60° C. or less, the adhesion to polypropylene and pressure sensitivity are significantly improved, but the adhesive strength is reduced and it is impractical. Furthermore, when the gel content of the acrylic emulsion is higher than 90% by weight, that is, when the solubility of the polymer in toluene after water scattering of the acrylic emulsion is low, the compatibility with the tackifying resin and the chlorinated PP solution may be affected. Chipping, failure to obtain stable adhesive formulations, lack of pressure sensitivity, 6
If it is less than 0% by weight, the cohesive force, that is, the adhesive strength, decreases significantly, which causes a practical problem.

The present acrylic emulsion can be obtained by a conventional emulsion polymerization method. That is, distilled water and some surfactant are placed in a flask, and the temperature is raised to 60 to 70°C under stirring and a nitrogen seal. Next, a polymerization initiator and previously prepared ethyl acrylate, butyl acrylate, 2-
One of the emulsifying monomers obtained by adding a mixed monomer containing ethylhexyl acrylate as a main component and some functional group monomers into distilled water and a surfactant mixture with stirring. After emulsion polymerization for 20 to 30 minutes to form emulsion seeds, the remaining emulsifying monomer
was continuously administered over a period of 3 to 4 hours, and the remaining monomer was further treated at the same temperature for 3 to 4 hours, followed by cooling to room temperature. The acrylic emulsion is obtained by adjusting the pH to 7 to 9 with aqueous ammonia or the like and filtering it through a 100 mesh filter cloth. More specifically, preferred composition examples of the monomers include 2-ethylhexyl acrylate 30-60
Main components are 30 to 50 parts by weight of butyl acrylate, 5 to 30 parts by weight of vinyl acetate, and 1 to 5 parts by weight each of acrylic acid, hydroxyethyl methacrylate, and acrylamide as functional group monomers. Alternatively, the main component monomer is 2-ethylhexyl acrylate 30-6
The composition of the functional group monomer is 0 parts by weight, 30 to 50 parts by weight of ethyl acrylate, 5 to 30 parts by weight of methyl acrylate. The adhesive composition for polyolefin of the present invention is formed by blending each of the above compositions, and if necessary,
Thickeners, wetting aids, colorants, antifoaming agents, crosslinking agents or hardening agents, antiaging agents, drying retardants, fillers, etc. may be used in combination as long as they do not affect adhesive performance. The adhesive for polyolefins of the present invention has excellent adhesion properties, particularly when adhering polypropylene in polyolefins to different materials, without requiring mechanical or physical treatment on the surface of polypropylene, and without the need for treatment with primers or the like. It has adhesive strength, and its adhesive performance is durable enough to not cause any noticeable deterioration of physical properties even when exposed to high temperature conditions for a long period of time. It is of great significance in the field of pressure-sensitive adhesive bonding of dissimilar materials using polypropylene as a material. In addition, since the water-based emulsion is the adhesive for the skeleton, the risk of adverse effects on the human body, environmental pollution, fire, etc. is extremely low, and its practical value is extremely high.

0010

[Example] In order to explain the present invention more specifically,
Although the present invention will be described with reference to production examples, working examples, and comparative examples, the present invention is not limited to these examples. In the following, parts and percentages are based on weight unless otherwise specified.

Production Examples 1 to 7 (Production of allyl emulsion) In advance, a mixture of distilled water, sodium dodecylbenzenesulfonate and acrylamide in the proportions shown in Table 1 was added to an aqueous solution with stirring using a homogenizer. The monomers shown in -1 are gradually administered to create a monomer emulsion. Next, 500 parts of distilled water and 0.5 parts of sodium dodecylbenzenesulfonate were placed in a flask equipped with a stirrer, and the temperature was raised to 70°C while stirring under a nitrogen blanket, and 5 parts of potassium sulfate was added. Administer. Subsequently, 1/10 of the total amount of monomer emulsion in the ratio shown in Table 1
0 was administered all at once, and seed polymerization of the emulsion was carried out over 30 minutes. Thereafter, the remaining monomer emulsion was continuously administered over a period of 3 hours, and after the administration was completed, the remaining monomer was polymerized for an additional 3 hours at the same temperature to complete the emulsion polymerization. After cooling to room temperature, the pH was adjusted to 7 with aqueous ammonia and filtered through a 100-mesh wire mesh to obtain an acrylic emulsion with a solid content of 50% for use in the present invention.

0012

[Table 1] *Display of monomer 2-EHA 2-ethylhexyl acrylate
EA Ethyl acrylate B
A Butyl acrylate MA
Methyl acrylate VAc
vinyl acetate MMA
Methyl methacrylate HEMA Hydroxyethyl methacrylate AM
Acrylamide AA
Acrylic acid tDM tert Dodecyl mercaptan DBS Sodium dodecylbenzenesulfonate

Examples 1 to 13 In a flask, 100 parts of the tackifier resin shown in Table 2 and 3 parts of dialkyl sulfosuccinate soda salt (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a surfactant were added. Add 3 parts of polyoxyethylene nonylphenyl ether (product name: Neocol P) and 3 parts of polyoxyethylene nonylphenyl ether (manufactured by Kao Corporation, product name: Emulgen 920), and then add a chlorinated PP solution in the proportions shown in Table 2. Thereafter, the temperature was raised to 80° C. while stirring, and the mixture was stirred and mixed for 2 hours under the same temperature condition. After confirming uniform dissolution of tackifying resin 5
The temperature was lowered to 0°C, and 100 parts of distilled water was gradually added to obtain an emulsion in which the tackifier resin and chlorinated PP were mixed. The acrylic emulsions obtained in Production Examples 1 to 5 were further blended into the emulsion in the proportions shown in Table 2, and a 20% aqueous solution of polyvinyl alcohol (manufactured by Co., Ltd.) was added as a thickener.
An adhesive composition for polyolefin of the present invention having a solid content of 50% and a viscosity of 3000 cps was obtained using Kuraray Poval 205 (trade name, manufactured by Kuraray).

[0014]

[Table 2] Display of tackifier resin <manufactured by Arakawa Chemical Co., Ltd.> A Alcon M-90 (hydrogenated white alicyclic hydrocarbon resin, softening point 90°C) B Alcon P-125 (water) Attached white alicyclic hydrocarbon resin, softening point 125°C) C Super Ester A-100 (hydrogenated rosin glycerin ester, softening point 100°C) Indication of chlorinated PP solution <Sanyo Kokusaku Pulp Made by Co., Ltd.>a
Super Chron 803MW (solid content 20%, chlorination rate 30%) b Super Chron 832L (〃 30%
, 〃 27%) c Superchron 773H (〃 45%
, 〃 32%)

The physical properties of the adhesive compositions of the present invention obtained in the Examples were evaluated by the methods shown below, and the results are shown in Table 3. 1) Stability of the formulation The mixture was left standing in a constant temperature bath at 40°C for one week, and the presence or absence of thickening, gelation, separation, etc. was checked and indicated as shown below. 〇 No abnormality △ Slight thickening × Separation or gelation 2) Adhesive property polypropylene plate (manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name SA)
-15NF) was coated with 100 g/m2 of the adhesive of the present invention, dried for 2 minutes in a hot air dryer at 100°C, and 2 kg of #40 cotton cloth was applied.
A sample for adhesion physical property testing was prepared by pressure bonding at a pressure of /cm2. 2-1) Adhesive strength The above sample was cut into 25 mm width, and the 180° peel strength was measured using a Tensilon tensile tester in a constant temperature and humidity room at 23°C and 65% humidity, and the adhesive strength was determined as kg/kg. In addition to displaying at 25 mm, the peeling state was also indicated as shown below. PS Peeling from polypropylene interface C
Cohesive failure CS of adhesive Peeling from the interface of cotton cloth 2-2) After leaving the sample for durability adhesive strength measurement in a 100°C hot air dryer for 400 hours, and then leaving it in a constant temperature and humidity room for 1 hour, Peel strength was measured using the method described above and displayed in the same manner.

Comparative Example 1 The emulsion obtained in Production Example 6 was blended in the same manner as in Example 1 and evaluated in the same manner as in Example. The results are shown in Table 3. Comparative Example 2 The emulsion obtained in Production Example 7 was blended in the same manner as in Example 1, and evaluated in the same manner as in Example. The results are shown in Table 3. Comparative Example 3 An adhesive in which chlorinated PP was removed from the formulation of Example 5 was blended in the same manner as in the example, and the same evaluation as in the example was carried out.
The results are shown in Table-3. Comparative Example 4 An adhesive obtained by omitting the tackifying resin from the formulation of Example 1 was formulated in the same manner as in the Example, and the same evaluation as in the Example was carried out, and the results are shown in Table 3. Comparative Example 5 Using only the emulsion obtained in Production Example 1, the same evaluation as in Example was carried out, and the results are shown in Table 3. Comparative Example 6 From the formulation of Example 1, the type of chlorinated PP was changed to one with a chlorination rate of 11.5% and a solid content of 20% (manufactured by Sanyo Kokusaku Pulp Co., Ltd., trade name: Superclone A). , the following formulation was carried out in the same manner as in the example, and the same evaluation as in the example was carried out, and the results are shown in Table 3.
It was shown to. Comparative Example 7 From the formulation of Example 1, the type of chlorinated PP was changed to a chlorination rate of 43% and a solid content of 60% (manufactured by Sanyo Kokusaku Pulp Co., Ltd., trade name Superclone 814H), and the following was prepared. Evaluations were made in the same manner as in Examples, and the results are shown in Table 3.

[0017]

[Table 3]

[0018]

Effects of the Invention The adhesive for polyolefin of the present invention does not require any mechanical or physical treatment of the surface of polypropylene, nor does it require any treatment with a primer, etc., especially when adhering polypropylene and different materials in polyolefin. It is clear from Table 3 that it has excellent adhesion and adhesive strength, and its adhesive performance is durable enough to not cause any noticeable deterioration of physical properties even when exposed to high temperature conditions for a long time. It is.

Claims (5)

[Claims] Claim 1: Based on 100 parts by weight of the solid content of the tackifier resin, a chlorinated polypropylene solution is added in an amount of 5 to 5 parts by weight as a solid content.
An adhesive composition for a polyolefin comprising 100 to 300 parts by weight of an acrylic emulsion as a solid content. 2. The adhesive composition for polyolefin according to claim 1, wherein the tackifying resin has a softening point of 30 to 180°C. [Claim 3] The chlorination rate of the chlorinated polypropylene is 1.
2. The adhesive composition for polyolefins according to claim 1, wherein a transparent solution is used in which the solid content of the chlorinated polypropylene dissolved in toluene is 15 to 65% by weight. 4. The adhesive composition for polyolefin according to claim 1, wherein the acrylic emulsion has a glass transition temperature (Tg) of -5 to -60°C. 5. The adhesive composition for polyolefin according to claim 1, wherein the gel content of the acrylic emulsion (toluene-insoluble portion of the acrylic polymer) is 60 to 90% by weight.