JPS61241330A - Polyethylene molded article having improved adhesiveness - Google Patents

Abstract

PURPOSE:A composition having high strength, high elasticity, high surface tension and extremely improved adhesiveness, consisting of a specific polyethylene which is irradiated with ultraviolet rays or treated with a chemical reagent. CONSTITUTION:A molded article having >=180kg/mm<2> tensile strength, >=2,700kg/mm<2> modulus in tension and >=40erg/cm<2> surface free energy, comprising a polyethylene having at least 700,000 intrinsic-viscosity molecular weight. The molded article is fiber or film and has many channels on the surface. It is obtained by treating the polyethylene having preferably 1,000,000 viscosity- average molecular weight by ultraviolet-light irradiation, corona discharge or fluorine gas treatment. Preferably the physical treatment and/or chemical surface activating treatment is combined with steam treatment.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a polyethylene molded article with improved adhesive properties, and more specifically, to a polyethylene molded article with improved adhesive properties that has high strength, high elasticity, and high surface tension. This invention relates to polyethylene molded products.

(Prior Art and its Problems) It is known to impart improved adhesion to conventional plastic molded articles by plasma treatment or chemical treatment. Polyethylene molded products also have the disadvantage of having an inert surface, poor compatibility with most materials, and lack of adhesion. Adhesion has been improved by chemical treatment using alkali or alkali. However, regular polyethylene molded products originally have low strength and low elastic modulus, and if they are subjected to ultraviolet irradiation treatment, low-temperature plasma treatment, or chemical treatment to improve adhesive strength, the strength will decrease considerably, so other materials may be used. Even when composited with polyethylene, the polyethylene molded product itself may be destroyed if the contact force is less than the contact force of the composite, and for this reason, the development of polyethylene composite materials has been delayed, although research has been conducted.

Moldings such as polyethylene fibers and films with extremely high strength and tensile modulus are also known materials, P, Sm.
! th (Polymar Vol. 21, p. 1341, 198°) Raya, B., Kalb (Macromoleul
ar chem, y vol. 180, p. 2983, 1979)
have published in the literature. In addition, the present inventors have also discovered a method for stably producing high-strength, high-tensile modulus fibers made of flexible polymers such as polyethylene at a high production rate through Japanese Patent Applications No. 58-159990 and 58-198074. .

These molded products with high physical properties are inherently inert polyethylene polymers and have high crystallinity, so they have poor adhesion, but research has not been conducted to improve the adhesion of high-strength, high-modulus polyethylene molded products. do not have.

(Problems to be Solved by the Invention) In other words, the present invention solves the disadvantages of polyethylene itself, such as its low surface tension and its own low surface tension, which improve adhesion but are accompanied by a large decrease in strength, in improving the adhesion of polyethylene molded products. It is in.

(Problems to be Solved by the Invention) The present invention is made of polyethylene having a viscosity average molecular weight of at least 700.000, has a tensile strength of at least tsoKf/J, a tensile strength of at least 51 tensile strength of at least 51 zrooKt/j, and a six-plane free energy. This is a polyethylene molded product with improved adhesion of 40 kg/cI1 or more.

To be more specific, the viscosity average molecular weight is 700.
．． 000, preferably 1,000,000 polyethylene, having a tensile strength of 180 Kf/- or more, a tensile modulus of 700 Kf/- or more, and a surface free energy of 40 erg/- or more, preferably 50 erg/- or more. In the molded article, the polyethylene molded article is preferably a fiber or a film, more preferably the polyethylene molded article has an adhesive property, high tensile strength, high elasticity, and has multiple grooves in its lj. It is an ethylene molded product.

The multi-strip grooves referred to here are countless multi-strip grooves arranged in the stretching direction of the molded product, and on the surface, the multi-strip grooves have an average strain in the width direction of 2 or more, particularly 5 to 50 It is desirable that they be aligned. The multiple grooves can be provided by controlling the amount of solvent evaporated when stretching a polyethylene gel molded product containing an appropriate amount of solvent.

In the present invention, treatments for obtaining polyethylene molded articles with improved adhesion include ultraviolet irradiation treatment, corona discharge treatment, low-temperature plasma treatment, oxidation treatment with chemicals, surface graft polymerization treatment, fluorine gas treatment, etc. It is better to do so.

Ultraviolet irradiation treatment, low-temperature plasma treatment, and corona discharge treatment use air, nitrogen, nitrogen, helium, argon, carbon dioxide,
Treatment may also be carried out in a gas medium such as ammonia. It may also be a treatment in which a compound having a polymerizable unsaturated bond, such as acrylic acid or methacrylic acid, is used in a gaseous body to form a polymer of these compounds on the surface of the molded article.

For oxidation treatment with chemicals, weights are 4 mm and 4 mm.
In-liquid treatments such as ff system, chromic anhydride/tetrachloroethane system, and chlorate/sulfur system are mentioned, but the most preferred is fluorine gas treatment.

In this case, the concentration of fluorine gas used is not particularly limited, but in consideration of treatment safety and treatment effect, it is preferably 1 to IO% and diluted with nitrogen gas or the like to this concentration.

The treatment temperature is also not particularly limited, but may be a room temperature of 20 to 30°C. Processing time varies from 1 minute to 60 minutes depending on the expected treatment effect.
minutes, preferably 3 minutes to 30 minutes.

In order to make the fluorine gas treatment effect more pronounced, prior to the fluorine gas treatment, rona discharge treatment, low temperature plasma treatment,
Surface activation treatments such as physical treatments such as ultraviolet irradiation and discharge treatment and chemical treatments such as concentrated acid/alkali treatments are preferably carried out, but steam treatment is preferred. A more preferable adhesion promoting effect can be obtained by combining the physical treatment and/or chemical surface activation treatment with water vapor treatment.

(Function) Because it uses a high-strength, high-elasticity polyethylene molded product, the polyethylene molecules are highly oriented. Therefore, during oxidation treatment with chemicals, there is less penetration of chemicals into the inside, and chemical changes occur only on the fiber surface. Stay,
Even during ultraviolet irradiation treatment in a gas medium, low-temperature plasma treatment, and corona discharge treatment, the gas does not penetrate into the interior of the fiber, so the erosion only occurs on the fiber surface, which is the main reason why the adhesion is improved without a significant decrease in strength. Seem. Furthermore, although the effects of steam pretreatment and fluorine treatment are not clear, since a very small amount of moisture is adsorbed on the surface of a polyethylene molded product, the reaction between this moisture and fluorine causes the formation of oxidizing substances, and this It seems that it acts on activation.

The surface free energy (erg/al) of the polyethylene molded article treated according to the present invention was determined by substituting the contact angles measured with water and methylene iodide solutions into the following equation.

The following formula (1) is the contact angle (Cos θ) measured with water and methylene iodide solution, and the γa, r of water and methylene iodide.
Entering the known l positive substitution of ydS7Wh, 7. d, γ, h
Create a two-dimensional simultaneous equation where are unknowns, r, and γ3h
is calculated and substituted into equation (2) to obtain the surface free energy of the solid.

's =' a + r! h
...(2) Regarding the effect of facilitating adhesion, if the molded product after treatment is a film, mix and apply a two-component epoxy resin between the treated surfaces, paste it together, heat it, or leave it at room temperature to form the epoxy resin. After the resin was cured, its cooking strength was measured. If the molded product is fibrous, twist the fiber bundle appropriately to make it into a thread, fix it with epoxy resin with a threshold of about 10α, and test the part fixed with epoxy resin with a Tensicon tensile tester. A 4-pull test was carried out by grasping the thread to measure the strength with which the thread could be handled from the resin. The tensile strength and tensile elasticity of the molded product were measured using a Tensian manufactured by Toyo Baldwin Co., Ltd., using the S-8 curve of a single fiber at a sample length (gauge length) of 30 mm and an elongation rate of 30 g/min. The tensile strength of the straw was calculated.

This will be explained below using examples.

(Example) Example 1 Tensile strength 30014/lJ, tensile modulus 7oooK4
/-1 viscosity average molecular weight 3.5 x 10, thickness 150
Tsumugi high strength polyethylene film and tensile strength 78K
f/-1 A normal polyethylene film with a tensile modulus of 5soKq/d, a viscosity average molecular weight of 5, OX 10', and a thickness of 150 μm was subjected to the following treatments to obtain surface self-evident energy r, (erg/cIi), and epoxy The adhesive strength of the resin was measured. The results are shown in Table 1. O treatment A: Low temperature air plasma treatment 60 minutes B: Treatment with 60 volume % bromine saturated solution of sulfuric acid at 0°C x 6
0 minutes c: The 4-person film is further acrylic r! ! Low-temperature plasma treatment for 30 minutes in the presence of steam Table 1 The margins below The high-strength polyethylene film treated according to the present invention retains its strength and has improved wetting properties (
(surface free energy) and exhibits excellent adhesion. On the other hand, ordinary polyethylene film subjected to the same treatment shows improvement in wetting properties, but its initial (untreated) strength is low and the strength decreases significantly due to treatment, and F! It is almost impossible to improve I adhesion.

Example 2 Tensile strength 200~/-1 Tensile modulus 6000 Kq
/-1 High strength polyethylene film with a thickness of 150 μm (
After performing the treatment shown in Table 2 to obtain a viscosity average molecular weight of 3.5 x 10'), the epoxy adhesive was twisted to determine the peel strength. The results are shown in Table 2.

The high-strength polyethylene film processed according to the invention exhibits improved wetting properties (surface free energy) and excellent adhesion. On the other hand, the film shown as a comparative example which was not subjected to fluorine gas treatment showed no improvement in wetting characteristics and adhesion.

The effect of pretreatment with water vapor before fluorine gas treatment is clear from a comparison of Samples 1 and 2.

Example 3 Tensile strength 360 kf/-1 Tensile modulus 8000 Kf/
-1 After treating a multifilament of high-strength polyethylene fiber (viscosity average molecular fM 1.9 X IO') with a fineness of 500 denier with fluorine gas under the conditions shown in Table 3,
The yarn was twisted 100 times per meter to make the epoxy-reinforced molded product, and its drawing strength was measured. The results are shown in Table 3.

Comparison of Samp/%/6 and Sample 1 shown in Margin Table 3 below shows the effectiveness of the tefluorine gas treatment, Sample 7 and Sample 11, Sample 8 and Sample 2, and the effectiveness of the multi-groove between Sample L and Sample 2. A comparison of sample 2 shows the effectiveness of steam pretreatment.

(Effects) According to the present invention, as is clear from the above-mentioned examples, it is possible to provide a polyethylene molded article having excellent adhesive properties with reduced strength reduction and improved surface free energy (wetting properties). As a result, even when combined with other materials, the polyethylene molded product itself will not be destroyed if the adhesive strength is lower than that of the composite, and the application of polyethylene molded products to composite materials will be expanded.

Claims (1)

[Claims] 1. Made of polyethylene with a viscosity average molecular weight of at least 700,000 and a tensile strength of 180 Kg/mm^
2 or more, a tensile modulus of elasticity of 2700 Kg/mm^2 or more, and a surface free energy of 40 ergs/cm^2 or more. 2. A polyethylene molded article with improved adhesiveness according to claim 1, wherein the polyethylene molded article is a fiber or a film. 3. A polyethylene molded article with improved adhesiveness as claimed in claim 1 or 2, wherein the polyethylene molded article has multiple grooves on its surface.