JP4620260B2 - Injection molding method - Google Patents

Description

【００９３】
実施例８〜１０
結晶化度約34％のＤｏｗ ＡｆｆｉｎｉｔｙプラストマーをＳｕｒｌｙｎ9970（ＤｕＰｏｎｔ）と下記表２記載の量で配合した。そのブレンドを射出成形して、前記成形物から６つの断片を切断し、ＥＳＣＲ試験を行った。その結果を以下の表２に示す。
【００９４】
【表２】

【００９５】
実施例１１
80％Ｄｏｗ Ａｆｆｉｎｉｔｙ（34％）、19％ナイロンＢ３（ＢＡＳＦ）、および1.2％Ｓｕｒｌｙｎ9970のポリマーブレンドをブレンドした。このポリマーブレンドを射出成形し、ＥＳＣＲ試験を行った。このポリマーブレンドは360＋時間のＥＳＣＲ試験結果を有する。
【００９６】
実施例１２および１３
結晶化度約34％の79％Ｄｏｗ Ａｆｆｉｎｉｔｙと30％Ｓｕｒｌｙｎ9970とのポリマーブレンドをブレンドし、射出成形して、薄壁チューブを形成した。76％Ｄｏｗ Ａｆｆｉｎｉｔｙ（結晶化度24％）、20％ナイロンＢ３（ＢＡＳＦ）、および４％Ｓｕｒｌｙｎの第２のポリマーブレンドをブレンドし、射出成形して、薄壁容器を形成した。この薄壁容器にペトロールを満たし、封止した。20％ナイロンおよび４％Ｓｕｒｌｙｎｌ配合した前記ポリマーブレンドはペトロールに対して、プラストマーとＳｕｒｌｙｎのみ含む前記ブレンドのものより約20倍少ない透過性を有する。
【００９７】
実施例１４
結晶化度約34％のＤｏｗ Ａｆｆｉｎｉｔｙプラストマーを、以下の表３記載の量でＴｉＯ_２と配合した。このブレンドを射出成形し、前記成形物から６つの断片を切断し、ＥＳＣＲ試験を行った。その結果を以下の表３に示す。
【００９８】
【表３】

【００９９】
当業者には特に記載されたこと以外の本発明の変形が容易に理解できる。本発明はこのような全ての変形を含み、これらは本発明の範囲に入ると解されるべきである。また、本発明はここに挙げられた全ての工程、特徴、組成物、化合物を含み、または、前記工程や特徴の２つまたはそれより多いいずれかの組み合わせを個々にまたは集合的に含む。
【図面の簡単な説明】
【図１】 本発明のポリマーブレンド製の薄壁容器の図である。
【図２】 本発明のポリマーブレンド製の薄壁容器の図である。
【図３】 本発明のポリマーブレンド製の薄壁容器の図である。
【図４】 本発明のポリマーブレンド製の薄壁容器の図である。
【図５】 本発明のポリマーブレンド製の、フックを一体的に結合した薄壁容器の図である。このフックはスプレッダーまたは他の望ましい便利な道具で適宜置換できる。
【図６】 本発明のポリマーブレンド製の薄壁容器の図であり、前記容器には孔を有するフランジが設けられており、前記孔は販売時にフックまたはハンガーから前記容器を吊るすのに適応される。
【図７】 本発明のポリマーブレンド製の薄壁容器の図であり、前記容器にはフックが設けられており、前記フックは販売時にフックまたはハンガーから前記容器を吊るすのに適応される。
【図８】 本発明のポリマーブレンド製の薄壁容器の破断図であり、前記容器の内側にはバリヤーコーティングを有する。
【図９】 単一のチューブ／クロージャーの図である。
【図１０】 （ａ）および（ｂ）は、サイドポーチを有するチューブの図であり、前記サイドポーチは製品サンプル、歯ブラシ、櫛等のアイテムを入れるためのものである。
【図１１】 単一のチューブ／付属品、特に単一のチューブ／クロージャーに対する支持機構の詳細を示す。
【図１２】 単一のチューブ／付属品、特に単一のチューブ／クロージャーに対する支持機構の詳細を示す。
【図１３】 単一のチューブ／付属品、特に単一のチューブ／クロージャーに対する支持機構の詳細を示す。
【図１４】 単一のチューブ／付属品、特に単一のチューブ／クロージャーに対する支持機構の詳細を示す。
【符合の説明】
１ 溶融ポリマー用のランナー
２ 「フリップトップ」ヒンジ蓋
３ 「ポップ」マッシュルームバルブ
４ コア
５ 「ポップ」バルブ（３）用のステム
６ チューブ側壁
７ 一体蝶番
８ チューブ側壁へ付勢されて向かうポリマー流れ用のチャンネル／グルーブ
９ チューブの側壁を付勢されて下るポリマー流れ用のグルーブ
１０（ａ） マッシュルームバルブ（３）上に位置する支持体
１０（ｂ） 引っ込めた位置に示された支持体
１１ マッシュルームバルブ（３）上の支持体位置
１２（ａ） コア（４）およびマッシュルームバルブ（３）の両方の上に位置する支持体
１２（ｂ） コアサイド上に位置する支持体
１３ 延長部に示される延長可能なコア支持体
１４ 型の凹部上の支持体位置
１５ 非延長部に示される延長可能なコア支持体[0001]
The present invention relates to an injection molding method, and more particularly to a method for an injection molded product having a thin-walled portion such as a thin-walled tubular container used for a lotion, a moisturizer, etc. in the cosmetic industry.
[0002]
Such thin-walled tubular containers used in the cosmetics industry are manufactured today by combining extrusion, injection molding and welding methods (generally referred to herein as extrusion methods). The tube body is extruded in a continuous cylinder shape, which is then cut to the desired length to form the container body. In the separate injection molding method, the “head and shoulder” of the tube is manufactured. This injection-molded “head and shoulder” is then welded to the extruded tube to form the container. After filling the container with the product, the tail of the container is further welded and sealed. This tube manufacturing method has many limitations, and the main ones are that the cost of the device is high, the tube shapes that can be manufactured using the device are not diverse, and that the manufacturing process is integrated. The inability to perform various pattern embossing surface finishes and grain embossing, and the inability to incorporate accessories / components such as closures and hooks during the manufacturing process. Low MFI polyethylene (generally MFI is less than 2) is the preferred polymer for tube manufacture. The reason is that such polyethylene generally imparts the good feeling and flexibility characteristics desired by customers and is suitable for extrusion. In addition, low MFI polyethylene retains sufficient product resistance and barrier properties, making it a suitable tube for most products that are recently filled into tubes. When the barrier properties of polyethylene are unsuitable for a particular application, medium density polyethylene (MDPE), high density polyethylene (HDPE), polypropylene (PP) and multilayer polymer films are commonly used.
[0003]
Injection molded products such as thin-walled containers have been proposed, but it is not possible to injection mold such molded products that have relatively long thin sections and are not excessively damaged for commercial or actual use. It was impossible until today. The main problem is related to the polymers used in injection molded tubes. Here, in the method of forming a tube having a cylindrical shape or other shape, the polymer can flow down through a long and narrow curved passage defined by the tube mold without applying excessive injection pressure. However, it is required that the polymer simultaneously retain sufficiently good mechanical properties that can withstand use and can withstand the stress cracking effects of many products filled therein. In order to injection mold a tube, the prior art provides the flow characteristics that allow the polymer to form a molded part with a radius and length / thickness ratio of 100, or often greater than 100. Required to have. To energize a “standard” polymer flowing in a mold with such dimensions, strong stresses are applied to the polymer, these stresses being frozen in the part, and then these stresses Before it can be removed, it is rapidly cooled below the crystallization temperature to produce a molded article. Due to these stresses, the tubes are surprisingly different in properties and deteriorated compared to other products molded with the same polymer under less severe molding conditions.
[0004]
The tube is further stressed as it is filled with product and then crimped and sealed. Sealing is often done by heat sealing or ultrasonic welding. This process involves folding the “open” end of the tube back at an angle of up to 180 ° on the tube to form a fold at the sealed end. This is folded in the direction of polymer flow, which is demonstrated to be the weakest direction of the molded part. This “folded and sealed” region is an injection molded tube region that requires deformation of the tube to obtain a sealing effect and is particularly susceptible to stress and flex cracks.
[0005]
The following example illustrates a particular problem in the injection molding of such a tube. The tube was injection molded using DuPont2020T polymer. The polymer DuPont is described as “particularly suitable for injection molded closures and extruded tubes that require maximum flexibility and resistance to environmental stress cracking”. These tubes were molded with high difficulty, requiring very high injection pressures and temperatures simply by filling the 2020T into a mold. It is noted that a very high degree of core variability / flexibility is required for each molding because of the unquestionably required very high injection pressure. In addition, it was noted that the tube was virtually insensitive to bending in the flow direction of the material and that severe cracking was caused by hand squeezing the tube less than five times. The same tube was tested for environmental stress cracking. Despite the requirement of “maximum resistance” to environmental stress cracking, it has been found that it is generally unsuitable for molding thin wall tubes by injection molding.
[0006]
To explain another difficulty with injection molded tubes, the Dow “Dowlex” LLDPE brochure explains that LLDPE has substantially better ESCR properties than equivalent high pressure LDPE. To illustrate the difference, according to the brochure, in one comparative test, high flow Dowlex LLDPE has an ESCR in oil about 80 times better than that achieved by high pressure LDPE with similar density and MFI ( 5700 hours vs. 70 hours). Furthermore, according to the brochure, LLDPE has an ESCR about 10 times better than LDPE when immersed in a 10% tric solution at 50 ° C. (225 hours vs. 26 hours). However, contrary to these observations, we found that these polymers were molded in the form of thin-walled tubes and then used a test method specifically designed to evaluate tube ESCR. When tested for ESCR, both Dow's “Dowlex” LLDPE 2517 and Kemcor's LD8153 (high pressure LDPE with similar MFI and density) were incomplete when run at 50 ° C. with 10% TericN9. Both failed within 20 minutes. This indicates that it is inappropriate to manufacture the tube by injection molding. This bad result shows that it has very unusual and difficult properties to produce a commercially accepted injection molded thin wall tube.
[0007]
What we now know has a relatively long thin-walled part by selecting the polymer used in the injection molding process so that it has a damage time longer than 10 hours when tested in the following manner: This means that an injection molded flexible thin wall article can be formed.
i) Use of multiple (preferably 6 or more) strips of a polymer blend incorporating some post-molding process intended for a final article having a cross-sectional dimension of 0.65 mm thick and 10 mm wide in the manufacture of flexible thin-walled articles. Injection molding under high shear stress, long channel conditions, similar to what was intended;
ii) bend the strip backwards on the strip and staple it at 3 mm from the bend;
iii) The bent strip is immersed in a solution of a stress cracking agent such as a 10% solution of ethoxylated nonylphenol, eg, Teric N9 (nonylphenol ethoxylated with 9 moles of ethylene oxide—Orica Australia Pty Ltd), and the temperature is set to 50 ° C. Hold on;
iv) observing the strip for signs of cracks, considering any signs of cracks as broken; and
v) The time to failure is when 50% of the strips show signs of cracking.
[0008]
Thus, now we provide a method of manufacturing a thin wall article that includes the following steps.
1) selecting a polymer blend having an ESCR of greater than 10 hours as described above;
2) dissolving the polymer blend;
3) Pushing the molten polymer blend into a mold, the mold has a cavity that produces a thin walled article having a thin wall thickness less than 1 mm, the thin wall portion of the molten polymer blend in the mold Substantially continuous in the flow direction for more than 50 mm, and
4) Taking out the thin-walled article molded from the polymer blend from the mold.
[0009]
“Substantially continuous” is understood by those skilled in the art as follows. That is, some variations of adding embossing, texture, relief finish, etc. to an article may increase the thickness, but generally keep the cross-sectional thickness below 1 mm. Thickness refers to the layer thickness of the polymer blend and excludes any additional layers combined in multiple stacks and the like. If the blend contains bubbles, we shall refer to the abstract thickness of the non-foamed material that can be easily determined from the density of the polymer blend.
[0010]
Throughout this specification and claims, the term “polymer blend” is understood to refer to a composition comprising at least one polymer and any optional additional components described herein.
[0011]
Throughout this specification and claims, the term “copolymer” is understood to refer to a polymer comprising two or more monomer units.
In general, in order to select a polymer blend suitable for the manufacture of thin-walled articles, it is necessary for the polymer blend to have an ESCR as defined above for more than 10 hours. Preferably, the ESCR of the polymer blend is greater than 100 hours, more preferably greater than 200 hours, and even more preferably greater than 360 hours. If the thin-walled article is a tube or other container used to package a composition such as a moisturizer, shampoo or the like that can attack the thin-walled article and degrade its properties over time, formed from the blend The thin wall article is formed by a polymer blend that allows the thin wall article to withstand rigorous use despite any deterioration in properties resulting from the aggressive nature of the material contained in the thin wall article. Thus, it is preferred to select a polymer blend having a sufficiently high ESCR. If thin-walled articles are used for packaging relatively inert materials, a lower ESCR may be used.
[0012]
The ESCR test defined above can be performed using various stress cracking agents. A preferred stress cracking agent is Teric N9 (9 moles of nonylphenol ex ethoxylate from Orica Australia Pty Ltd), and other nonylphenol ethoxylations can be used advantageously. Other stress cracking agents can be used and are selected according to the intended use. Other stress cracking agents include mineral oil, cationic surfactants, solvents, and other agents apparent to those skilled in the art.
[0013]
The ESCR test as defined above is preferably performed under molding conditions similar to those used in the manufacture of thin wall articles. For example, when it is desired to manufacture a thin wall article using a mold combined with the melt flow vibration method, it is preferable to perform an ESCR test on a panel manufactured from a mold manufactured using the melt flow vibration method.
[0014]
The ESCR test defined above can use a variety of polymer blends selected so that they can be injection molded to form thin wall articles. A second aspect of the present invention is to provide a thin wall article injection molding method including the following steps. That means
1) dissolving a polymer blend, said polymer blend comprising at least one polymer and at least one compatibility agent and / or at least one nucleating agent;
2) Pushing the molten polymer blend into a mold, the mold has a cavity for producing a thin wall article having a thin wall portion having a thickness of 1 mm or less, the thin wall portion being a flow of the molten polymer blend in the mold Substantially continuous longer than 50 mm in the direction, and
3) Taking out the thin wall article molded from the polymer blend from the mold.
[0015]
A wide variety of polymers can be used as the basis for blends that meet the ESCR test defined above or act as at least one polymer in the second aspect of the invention. These polymers include olefin homopolymers and copolymers, preferably from a very low density range to a very high density range (0.85 to 0.97 g / cm ³ And ethylene or polypropylene homopolymers and copolymers having a C 3-20 α or β olefin and / or a polyene (preferably a C 3-8 α or β olefin). Also suitable for use in the present invention are ethylene, propylene, and butene copolymers having terminal vinyl groups, ethylene, propylene and butene copolymers containing more than 50% ethylene, propylene or butene, these being methyl acrylate , Ethyl acrylate, acrylic acid, and methacrylic acid, as well as ionomers and styrene-ethylene / butene-styrene ABA copolymers. These polymers can be produced by a wide variety of methods, including high pressure and low pressure methods, using a wide variety of catalysts such as Ziegler-Natta and metallocene, and have a linear to highly branched molecular structure. And includes LDPE, MDPE and HDPE. Particularly suitable for use in the present invention include plastomers, “substantially linear” and branched polyethylenes, or polypropylene, propylene and ethylene or copolymers of one or more alpha olefins, ethylene, propylene and 1 Terpolymers of one or more alpha olefins (one example being Montell's Catalyst polymer), and propylene polymers and copolymers made using metallocene catalysts. Other polymers suitable for use in the present invention include polylactic acid polymers.
[0016]
We have found that plastomers, “substantially linear polyethylene”, metallocene branched polyethylene copolymers, propylene alpha olefin interpolymers, and the use of metallocene propylene polymers and interpolymers in the present invention to produce thin wall products. Particularly suitable for the production of flexible tubes. An important property of plastomers, “substantially linear polyethylene”, metallocene branched polyethylene copolymers, propylene alpha olefin interpolymers, and metallocene propylene polymers and interpolymers is their compositional distribution, ie, intrapolymer and polymer molecules The uniformity of the distribution of the copolymer in between. Plastomers, “substantially linear polyethylene”, metallocene branched polyethylene copolymers, propylene alpha olefin interpolymers, and metallocene propylene polymers and interpolymers are generally produced using a metallocene catalyst, which is between the polymers produced by the catalyst. And it is known to incorporate the copolymer very uniformly along the polymer. Thus, in particular, most molecules of plastomers, “substantially linear polyethylene”, metallocene branched polyethylene copolymers, propylene alpha olefin interpolymers, and metallocene propylene polymers and interpolymers have roughly the same comonomer content. And within each molecule the comonomers will be superrandomly distributed. Ziegler-Natta catalysts generally result in copolymers having a fairly broad composition distribution, especially the copolymer distribution in the polymers thus produced will vary widely between polymer molecules and the randomness within a particular molecule will be low.
[0017]
US Pat. No. 5,451,450 (the disclosure of which is incorporated herein by reference) describes plastomers as ethylene alpha olefins having a molecular weight distribution with a Mw / Mn ratio of 1.5-30, preferably 1.8-10, more preferably 2-4. It is described as a copolymer (including ethylene / alpha olefin / polyene copolymer). In general, the plastomer polymer comprises an ethylene homopolymer and an interpolymer of ethylene, and particularly preferably has at least one α-olefin copolymer having 3 to 20 carbon atoms. The term “interpolymer” is used herein to indicate a copolymer or terpolymer or the like. That is, at least one other comonomer is copolymerized with ethylene to form an interpolymer. In general, alpha olefins suitable for copolymerization with ethylene to form plastomers contain about 2 to about 20, preferably about 3 to 16, more preferably 3 to 8 carbon atoms. Non-limiting examples of such alpha olefins are propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octane, 1-dodecene, and the like. Polyene comonomers suitable for copolymerization with ethylene to form plastomers suitable for the present invention mainly have about 3-20, preferably about 4-20, more preferably about 4-15 carbon atoms. . In one example, the polyene is a diene having from about 3 to 20 carbon atoms and may be a linear, branched, or cyclic hydrocarbon diene. Preferably the diene is a non-conjugated diene. Non-limiting examples of ethylene / alpha olefin plastomers suitable for the present invention include ethylene / butene-1, ethylene / hexene-1, ethylene / octene-1, and ethylene / propylene copolymers. Non-limiting examples of terpolymer plastomers suitable for the present invention include ethylene / propylene / 1,4 hexadiene and ethylene / octene-1 / 1,4-hexadiene.
[0018]
Plastomers and “substantially linear polyethylene” are mainly produced using metallocene catalysts. US Pat. No. 5,281,679 (incorporated herein with reference to this disclosure) discloses a process for producing metallocene homo- and copolymers having a broad molecular weight distribution (generally in the range of 3-30), and a Ziegler-type polymer. Compared to, improved tensile and impact strength. They are also characterized by a fairly narrow and short chain branching distribution and a low extractability of hexane.
[0019]
In terms of density, preferred plastomers for use in the process of the present invention are comparable to VLDPE or ULDPE and are also copolymers of alpha olefins such as butene, hexene or octene with ethylene. These are generally defined as ethylene alpha olefin copolymers having a density of 0.86 to about 0.915. The process for producing VLDPE is generally described in EP 120,503. Plastomers, even those with the same density as VLDPE, have very different physical properties, mainly due to differences in production processes using metallocene catalysts. In general, VLDPE has a much higher melting point and softening point, a molecular weight / size distribution higher than 3, and higher crystallinity when compared to plastomers of similar density.
[0020]
Elastic, substantially linear olefin polymers are described in numerous patents including U.S. Pat.No. 5,272,236, U.S. Pat.No. 5,278,272, U.S. Pat.No. 5,380,810, U.S. Pat.No. 5,525,695, U.S. Pat. All of which are incorporated herein by reference. As an example of a substantially linear olefin polymer having elasticity, US Pat. No. 5,578,272 describes the same I ₂ One type having a critical shear rate at the start of surface melt fracture of at least 50% greater than the critical shear rate at the start of surface melt fracture of an olefin polymer having Mw / Mn. These polymers also have the same I ₂ And a processing index (PI) equal to or lower than that of a relatively linear olefin polymer at Mw / Mn. Particularly preferred are substantially linear polymers having elasticity including ethylene homopolymers and interpolymers of at least one C3-20 alpha olefin copolymer and ethylene. As used herein, the term “interpolymer” means a copolymer or a terpolymer. That is, at least one other comonomer is copolymerized with ethylene to form an interpolymer.
[0021]
By “substantially linear” polymer is meant a polymer backbone that is substituted with long chain branches of about 0.01 to about 3, preferably 0.03-1, per 1,000 carbon atoms. “Linear olefin polymer” means that the polymer does not have long chain branching, eg using traditional linear low density polyethylene or Ziegler polymerization methods (eg US Pat. Nos. 4,076,698 and 3,645,992). The linear high density polyethylene polymer produced by the present disclosure, the disclosure of which is incorporated herein by reference.
[0022]
The short chain distribution index (SCBDI) (short chain branching distribution index) is defined as the weight percent of molecules having a comonomer content within 15% of the median total molar comonomer content. The substantially linear polymer SCBDI suitable for the present invention is preferably greater than about 30%, more preferably greater than about 50%.
[0023]
The unique feature of the substantially linear polymer of the present invention is totally unexpected flow properties, I ₁₀ / I ₂ The value is essentially independent of the polydispersity index (ie Mw / Mn). This is the polydispersity index I ₁₀ / I ₂ Contrast with conventional polyethylene resins having increased rheological properties. The density of the ethylene or ethylene / alpha olefin substantially linear olefin polymer of the present invention is generally about 0.85 g / cm. ³ ~ 0.97g / cm ³ , Preferably about 0.85 to 0.92 g / cm ³ It is.
[0024]
Substantially linear polymers preferably used in the method of the present invention have processability substantially similar to that of high pressure LDPE, but with special adhesion promoters such as processing additions such as Viton fluoroelastomer from Du Pont. Without the benefits of the agent), it has strength and other physical properties similar to those of conventional LLDPE.
[0025]
US Pat. No. 5,525,695 (the disclosure of which is incorporated herein by reference) discloses a process for making “substantially linear polyethylene” and has the following characteristics. In other words, A about 0.85g / cm ³ ~ 0.97g / cm ³ Density of;
B MI from 0.01 g / 10 min to 1000 g / 10 min;
C preferably about 7-20 I ₁₀ / I ₂ Melt flow ratio of
D preferably a molecular weight distribution Mw / Mn of less than 5, more preferably less than 3.5, more preferably about 1.5 to 2.5
[0026]
Elastic, substantially linear olefin polymers can be produced with a broader molecular weight distribution by appropriate selection of catalysts for the polymerization process described in US Pat. No. 5,278,272. Wider MWD materials exhibit higher shear rate or shear stress dependence. In other words, generally, as the MWD is wide, the effective MFI at the time of high shear increases. Thereby, better processing characteristics can be obtained. Wide molecular weight distribution "substantially linear olefin polymers", plastomers and metallocene branched polyethylenes are particularly suitable for the manufacture of tubes using the process of the present invention.
[0027]
Furthermore, we have found that several types of polymers, preferably unsaturated polymers such as polyvinyl chloride and polystyrene, more preferably polyolefins, more preferably plastomers, “substantially linear polyethylene”, metallocene branches Polyethylene and polypropylene copolymers and most preferably plastomers and “substantially linear polyethylene” polymers and polypropylene copolymers and have a density of 0.87 to 0.92 and greater than 10, preferably greater than 20, more preferably What has an MFI greater than 30 is that, as a means of improving the ESCR of the tube, the addition of a nucleating agent alone can produce a tube suitable for the packaging of some products with less aggressiveness. However, not only the addition of the nucleating agent, but also the addition of a compatible polymer such as polypropylene and polypropylene copolymer to the above-mentioned polymer makes the overall ESCR resistance better and is preferable overall.
[0028]
What has been established is that polymers, especially higher I than normal, which are essentially independent of the polydispersity index (ie Mw / Mn). ₁₀ / I ₂ Valued plastomers and substantially linear olefins, and metallocene polypropylene homopolymers and copolymers are particularly suitable for the manufacture of injection molded tubes and other thin-walled articles having excellent ESCR and other physical / chemical properties. Yes. As described in US Pat. No. 5,281,679, the disclosure of which is incorporated by reference, broadening the molecular weight distribution of polymers, particularly polyethylene and its copolymers, increases the tensile and impact strength of products made therefrom. increase. Polymer I ₁₀ / I ₂ The main reason for the high is that there are both high and low Mw molecules in the polymer. It is conceivable that the fraction of molecules with high Mw greatly improves the ESCR properties of the polymer, while the fraction of molecules with low Mw improves the processability by increasing the shear sensitivity of the polymer. , So that clearly lower MFI (usually I ₂ The polymer can be molded into a tube.
[0029]
I suitable for the present invention ₁₀ / I ₂ High polymer can be produced by various methods. The method includes the following steps. That means
1) Thoroughly blend two or more polymers having different molecular weights using a suitable mixing device;
2) High I ₁₀ / I ₂ Producing a bi- or polymorphic polymer having a tandem using a "tandem"reactor;
3) High I ₁₀ / I ₂ Producing a bi- or polymorphic polymer with a single catalyst using a suitable catalyst.
[0030]
High I ₁₀ / I ₂ The catalyst used to produce the bi- or polymorphic polymer having is selected to produce: That means
1) a broad molecular weight distribution polymer (which has a molecular weight distribution of 3-30, as described, for example, in US Pat. No. 5,281,679, the disclosure of which is incorporated herein by reference);
2) Two or more effective polymers, each having a narrow or broad molecular weight distribution, as described. US Pat. No. 5,539,076 (the disclosure of which is incorporated herein by reference) discloses a method for producing bi- or polymorphic polyethylene polymers having a density of 0.89 to 0.97 using a single reactor.
[0031]
Other polymers suitable for injection molded tubes are silane grafts or copolymer polymers. Such polymers can be cross-linked by post-processing, resulting in a cross-linked polymer work with formability / workability. This compound facilitates the processability of relatively low viscosity polymers and provides design / method flexibility, while providing the strength and other benefits of higher viscosity crosslinked polymers and copolymers. These polymers also do not require long cycle times and high temperatures to achieve in-mold crosslinking. Many patents describe various aspects of the method of preparing and crosslinking various silane-based compositions that can be used in the present invention. These include US Pat. Nos. 5,055,249, 4,117,063, 4,117,195, 4,413,066, 4,975,488, and 3,646,155, the disclosures of which are incorporated herein by reference.
[0032]
Another concept of the present invention provides a compound that can be mixed in a single step and injection molded immediately thereafter. This compound consists of one or more polymer types such as acrylate or branched metallocene catalyzed ethylene alpha olefin plastomer, and in the presence of a peroxide such as dicumyl peroxide and an organic silane compound such as vinyltrimethoxysilane Reacts to produce a single graft polymer that occurs in the barrel of the injection mold. Thereafter, immediately before injecting the silane graft polymer into the mold, a catalyst such as dibutyltin dilaurate is put into the silane graft polymer in the barrel of the mold, and the mixture of the catalyst and the graft polymer is thoroughly mixed. Post molding crosslinking of the silane component on the polymer backbone is facilitated by condensing hydrolyzable silane groups on different polymer backbones in the presence of moisture. The final properties of the new polymers are by changing the proportions of the various polymers, by changing the properties of either or both polymers (for example, by using additional functional groups and polymers such as vinyl acetate, and And / or by changing the properties of the silane-containing polymer, for example by changing the polyethylene type and / or the silane type chemically bonded to the polymer. The final properties can be further altered by adding additives such as other compounds / fillers, plasticizers, and anti-aging agents well known to those skilled in polymer formulation.
[0033]
Another method of producing a silane graft polymer suitable for use in the present invention is to graft silane onto the polymer, which is a separate step in the presence of a peroxide or in a suitable reactor such as an extruder. It is carried out in the presence of other free radical generators. The resulting graft polymer is then packaged in water resistant packaging for subsequent use. If desired, the graft polymer can be introduced into an injection mold with an appropriate amount of condensation catalyst, and the two components are thoroughly blended in the mold and then injection molded and subjected to cross-linked post processing. .
[0034]
Silane-containing polymers typically contain 0.1-15% hydrolyzable silane. Most common hydrolyzable silanes used in the production of silane-containing polymers are vinyltrimethoxysilane, vinyltriethoxysilane, but any that can be bonded to another polymer to form a silane-containing polymer. It may be a hydrolyzable silane.
[0035]
The at least one compatibility agent is preferably a polymer, and when blended with the at least one polymer, in the case of a blend used to form a thin wall article such as a flexible injection molded tube, The blend has properties superior to the pure polymer. The at least one compatibilizer includes: ethylene vinyl acetate; ethylene vinyl alcohol; plasticized polyvinyl acetate and polyvinyl alcohol; alkyl carboxyl-substituted polyolefins; copolymers of anhydrides of organic acids; epoxy group-containing copolymers; Copolymers such as ethylene-propylene-butylene; ultra low density, very low density, low density, medium density and high density polyethylene; polypropylene, polybutylene and copolymers thereof; polyester ether; polyether ester (sHytrel range from DuPont) ); Acrylonitrile-methacrylate copolymer; block copolymer with styrene end block: half ester; amino and alkoxysilane grafted poly Tylene; Vinyl addition polymer; Styrene-butadiene block copolymer; Acid graft polyolefin; Vinyl pyrrolidine graft polyolefin; Block copolymer of divalent monomer; Propylene graft unsaturated ester; Amide group, epoxy group, hydroxy group, or C2-6 acyloxy Selected from the group consisting of modified polyolefins containing other polymerizable compatibilizers suitable for use in combination with polyolefins; particles coated with any of the above; and mixtures thereof. In the compatibilizers described above, the functional groups are generally bonded to the modified polyolefin as unsaturated monomers that are copolymerized with olefin monomers or grafted to the polyolefin to form the modified polyolefin.
[0036]
The alkyl carboxyl substituted polyolefin may comprise a substituted polyolefin. Here, the carboxyl groups are derived from acids, esters, their anhydrides and salts. Carboxyl salts contain neutralized carboxylic acids and are often referred to as ionomers (eg Surlyn). Typically, acids, anhydrides, and esters include methacrylic acid, acrylic acid, ethacrylic acid, glycidyl maleate, 2-hydroxyacrylate, diethyl maleate, maleic anhydride, maleic acid, esters of dicarboxylic acid, and the like. Preferred examples include ethylenically unsaturated carboxylic acids such as polyethylene methacrylic acid and polyethylene acrylic acid, and salts thereof.
[0037]
Organic acid anhydride copolymers include maleic anhydride copolymers and cyclic anhydride copolymers.
[0038]
Poly-2-oxazoline compounds and fluoroelastomers are also suitable for use as compatibility agents. The binding of 1 to 40% of the poly-2-oxazoline compound is preferable, and more preferably 2 to 20%. These compatibilizers improve the adhesion of the PE blend to various substrates and are useful for printing or labeling. The compatibilizer comprises an alpha olefin copolymer substrate grafted with a monovinylidene aromatic polymer. Preferably, the alpha olefin copolymer substrate is a terpolymer of ethylene, propylene and non-conjugated diolefin.
[0039]
Many copolymers of ethylene also serve as compatibilizers for the process of the present invention. For example, single site catalytic polymers such as metallocene catalyzed polyethylene can be used as the compatibilizer of the present invention.
[0040]
Polypropylenes suitable as compatibilizers for use in the method of the present invention include various MFI, density, crystalline isotactic, syndiotactic and atactic polypropylene and syndiotactic polypropylene, the method of the present invention The desired properties are imparted to the product formed by the above method. In particular, when blending low molecular weight plastomers, various polypropylene polymers having a very wide range of MFI (1-200 +), density, and crystallinity provide blends suitable for use in the method of the present invention.
[0041]
Polyethylenes suitable as compatibilizers for use in the method of the present invention include polyethylenes having various MFI, density, and crystallinity, and impart desired properties to the product molded by the method of the present invention. . Includes very low, low, medium and high density polyethylene. In particular, this includes blending low molecular weight plastomers, substantially linear polyethylenes and metallocene branched polyethylene polymers. A variety of polyethylene polymers having a very wide range of MFI (1-200 +), density, and crystallinity provide blends suitable for use in the method of the present invention.
[0042]
Many monomers are copolymerized with propylene to form copolymers of propylene. Many of these copolymers are suitable as compatibilizers for use in the present invention. Examples of ethylene-propylene copolymers include Montell's SMD6100P, XMA6170P. Further examples of polypropylene copolymers are Montell's Catalloy KS-084P and KS-357P. These products are believed to be terpolymers of propylene, ethylene, and butene. Other such copolymers and / or terpolymers can be used.
[0043]
Ionomers are particularly advantageous as compatibility agents when combined with plastomers, substantially linear polyethylenes and branched polyethylenes as at least one polymer. The ionomer is typically a copolymer of ethylene and acrylic or methacrylic acid and is neutralized with a metal ion such as sodium, lithium, or zinc. One group of ethylene copolymers, called ionomers, is exemplified by the commercial product Surlyn (from DuPont). Ionomer is rigid, tough and behaves like a crosslinked polymer at ambient temperature. However, these can be processed at high temperatures. Particularly preferred are blends of plastomers and ionomers. Such blends impart high barrier properties to the polymer.
[0044]
Block copolymers of divalent monomers include block copolymers of dihydric phenol monomers, carbamate precursors, and polypropylene oxide resins.
[0045]
The compatibility agent is used in an amount at least sufficient to improve the environmental stress crack resistance of the polymer blend. Standard tests for environmental stress crack resistance are of little value in determining the specific polymer blends used in the manufacture of thin wall articles such as tubes. While not wishing to be bound by theory, it is possible that injection molding of thin wall articles such as tubes introduces a unique stress into the molded article and freezes it. It becomes susceptible to environmental stress cracks depending on the degree and direction of stress in products such as injection molded tubes. Therefore, the above test was developed to show the improvement in environmental stress crack resistance obtained from the present invention.
[0046]
In some formulations, up to 2% of the compatibilizer is sufficient to improve the environmental stress crack resistance of the polymer blend as compared to the environmental stress crack resistance of the plastomer.
[0047]
The compatibility agent may be used to improve the viscosity characteristics of the polymer blend in order to optimize the molding properties of the polymer blend and / or general properties such as softness and flexibility of the molded article. It may be used in excess of the amount required to compatibilize. Typically, the compatibility agent is used in an amount of about 2 to about 98% by weight of the polymer blend. However, some polymer blends may be used in smaller amounts. The optimum amount for a particular formulation depends on the required properties and can be determined by experimentation. In addition, it has been found that by incorporating a higher proportion of compatibilizer than needed to increase the environmental stress crack resistance of the polymer blend, tear and impact strength, barrier properties, chemical resistance, processability And polymer blend properties such as product feeling can be improved. For example, to improve the environmental stress crack resistance of the polyethylene blend to the desired level, including the minimum amount of polypropylene required to improve only the environmental stress crack resistance by blending more than the proportion of polypropylene needed. Compared to polymer blends, it can improve chemical resistance and reduce the water vapor and water permeability of the polymer blend. Furthermore, it has been found that by blending the proportion of the compatible agent beyond the required amount, other polymers can be blended beyond the amount consistent with the present invention. Thus, by using a compatible agent in such an amount, other polymers such as essentially incompatible nylon and EVOH can be incorporated in higher but possible amounts, tear and impact strength. It is possible to improve the properties such as barrier properties, chemical resistance and product feeling.
[0048]
A barrier resin may be incorporated into the polymer blend of the present invention. Barrier resins compatible with at least one polymer include polyamides, polycarbonates and condensation polymers such as various esters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN); polyvinyl Polyvinylidene chloride (PVDC); ethylene vinyl alcohol (EVOH); polyvinyl alcohol (PVOH); ethylene vinyl acetate (EVA); EMA, EMAA, EEA; ionomers; monovinylidine aromatic polymers and copolymers; Propylene and butylene copolymers; polyethylene chlorosulfate, polyisoprene and polychloroprene, polyalkalenephenylene esters and ester ethers; Including polyurethane and acetyl; methacrylate copolymers - acrylonitrile; nitrile copolymers; polyacrylonitrile Le formaldehyde; polyacrylate; polyester ether. It will be appreciated that some barrier polymers are more or less compatible with at least one polymer than others. For example, EVOH with a sufficiently high ethylene content is compatible with the at least one polymer, especially when the polymer is an ethylene copolymer such as plastomer, while EVOH with a relatively low ethylene content is essentially Incompatible. The barrier properties of the polymer blends of the present invention are further enhanced by adding additives that may be reactive or absorbable to harmful chemicals such as oxygen and other gases.
[0049]
The polymer blend can also contain various other additives. Examples of additional additives include additional polymers, pigments, dyes, fillers, antioxidants, plasticizers, UV protection, viscosity modifiers, capable of reacting or absorbing to harmful chemicals such as oxygen Compatible additives, and other mold release agents, and melt strength modifiers among others. In order to modify the properties of the polymer blend in order to adapt it to a specific application or to achieve a specific effect in the final product, these additives may be added to one or more of the polymer blends prior to molding. It can be added to the polymer blend as a component or as a whole.
[0050]
In order to obtain the desired barrier properties without using polymer pre-orientation prior to injection molding using an essentially incompatible polymer, preferably the melt flow index of the dispersed phase is the same shear rate. And should be somewhat greater than the melt flow index of the continuous phase. In particular, the melt flow index of the barrier resin (usually dispersed phase) is preferably 1.1 to 3.5 times larger than the melt flow index of the continuous phase. For optimal barrier properties, it is believed that the dispersed phase droplets need to twist to form a sheet (lamellar structure) when subjected to stress inherent in the injection process. However, if the melt flow index of the dispersed phase is much lower than that of the continuous phase, the dispersed phase droplets will resist torsion and will not form the lamellar structure required for optimal barrier properties. On the other hand, if the melt flow index of the dispersed phase is greater than that of the continuous phase, it is more prone to failure under shear stress due to mixing, thereby being finely dispersed and thus making the barrier material smaller, resulting in this , Barrier properties are reduced. Also preferably, the polymer blend, including the barrier polymer, is not further mixed than is necessary to obtain a uniform mixing prior to molding. When subjected to excessive shear, the barrier properties decrease. One skilled in the art can determine the desired amount of mixing necessary to obtain an optimal balance of properties. A further advantage of the formation of such lamellar structures of the polymer blends of the present invention is that the mold can be designed so that the polymer to be molded not only flows straight down the core but also flows easily across the mold. It is conceivable that such a mold design facilitates biaxial stretching of the barrier material to form a lamellar structure, thereby further improving the barrier properties of the molded article.
[0051]
In another method, the lamellar / multilayer structure of the polymer is facilitated by the use of the present invention, in which the polymer of the blend is rearranged into a composite stream and the stream is injected into the mold and clearly A separated, generally planar, parallel layer is formed. This can be accomplished in a number of ways, including the coextrusion of separate, generally planar, parallel layer composite streams of the various polymer components of the blends of the present invention, and adjusting this composite stream if necessary. Forming a second composite stream having an increased number of layers of approximately uniform thickness and then directly injection molding the final stream to form a multilayer plastic article.
[0052]
In a particularly preferred embodiment of the invention, the polymer blend comprises at least one plastomer and at least one ionomer. These polymer blends are preferably formulated with additional polymers and can impart barrier properties to the blend. For example, nylon is blended into such blends and appropriate blending and molding conditions are selected to reduce the hydrocarbon and gas permeability of the plastomer. The high degree of orientation caused by the molding process is believed to provide the strongly desired barrier properties brought about by the addition of nylon and other essentially incompatible polymers. In order to optimize the barrier properties, the nylon itself needs to be stretched and oriented. By blending nylon into a plastomer and ionomer blend, the blend can be injection molded to form parts having barrier properties believed to be provided by nylon while retaining resistance to environmental stress cracking.
[0053]
While not wishing to be bound by theory, we have found that it is clear that at least one polymer has the property of interacting with at least one compatibilizer, thereby at least one polymer and at least Both properties of one compatibilizer are severely and unexpectedly changed and the polymer blends thus produced can be suitable for the production of thin wall articles.
[0054]
It is also conceivable that the interaction between the at least one polymer and the at least one compatibility agent forms a region in the molded article that can be considered a “joint”. It is clear that these “joins” absorb or dissipate stress in articles formed from polymer blends. It is clear that the presence of these “joints” interspersed in the article absorbs or dissipates stresses that result in reduced physical properties. These so-called “joints” are believed to result from one or more of the following mechanisms.
(i) interaction between the polymer and the compatibility agent, thereby increasing the amorphous area in the polymer;
(ii) due to the interaction between the polymer and the compatibility agent, the crystallinity is greatly reduced locally, ie, a relatively amorphous region at the interface between the polymer and the compatibility agent; and
(iii) the ability to greatly absorb or dissipate stress due to the interaction between the polymer and the compatibility agent, even though the crystallinity does not decrease and thereby does not increase the amorphous region. A region is formed between the polymer and the compatibility agent.
[0055]
It has been found that when at least one polymer is an ethylene homopolymer or copolymer, and preferably when it is a plastomer or a substantially linear polyethylene, the polymer can interact with many of propylene and its copolymers; This interaction reduces the crystallinity of the polymer. It is conceivable that the propylene polymer acts as a crystallization agent for the at least one polymer, and such action increases the number of amorphous regions in the at least one polymer. DSC analysis shows that they act to greatly reduce the overall crystallinity of ethylene polymers, particularly plastomers and substantially linear polyethylene polymers. It is further conceivable that, together with the interfacial effect between the at least one polymer and the propylene polymer, these amorphous regions act to reduce and disperse molded-in stresses in the molded part. This increases the ESCR. At the same time, the at least one polymer interacts with at least one plastomer or substantially linear polyethylene, and such interaction greatly reduces the crystallinity of the at least one plastomer.
[0056]
It is contemplated that many of the polymer blends form a co-continuous lamellar structure, and the interface between the at least one polymer and the at least one compatibility agent is compatible with the at least one polymer and the at least one compatibility. Characterized by thorough mixing of agents at the microscopic level. In other words, the at least one compatibility agent is believed to act as an interactive filler. Thorough mixing between the at least one polymer and the at least one compatibility agent improves the overall properties of the polymer blend. In particular, when low molecular weight plastomers and substantially linear polyethylene are the at least one polymer, other polymers previously considered to be substantially incompatible with polyethylene are now compatible. And the blend has a wide range of properties, making it commercially acceptable to produce articles that were previously not commercially viable.
[0057]
It has been found that many compounds known to be able to nucleate for polymer crystallization, especially olefin polymers and copolymers, and more particularly ethylene polymers and copolymers, improve the ESCR properties of polymers for use in the present invention. To do. Depending on the nature of the individual polymer, the nucleating agent alone (without the addition of a compatibility agent) can increase the ESCR of the polymer to a level that the polymer can use to make injection molded tubes. What is considered is that the nucleating agent increases the ESCR of the polymer in tube manufacturing due to the formation of more smaller crystals in the above case. The more small crystals increase the number of amorphous areas in the polymer. Thereby, the stress introduced into the tube mold during injection molding can be absorbed or dispersed. This increases the ESCR and flex resistance of the product. Nucleating compounds that are preferably used in tube manufacture include various metal compounds such as talc, mica, oxides and silicates, and various organic compounds, as well as various dyes and pigments. However, for the most beneficial results in the case of injection molded tubes, preferably the nucleating agent is used with a compatible polymer.
[0058]
It has been found that compounds known to be able to reduce the glass transition temperature (Tg) of the at least one polymer of the invention, in particular olefin polymers and copolymers, and more particularly ethylene polymers and copolymers, Improve the ESCR properties of the polymer for the use of Depending on the nature of the individual polymer, the Tg reducing agent alone (ie, without the addition of a compatibility agent, nucleating agent, or “high temperature density agent”), the polymer ESCR is produced by the polymer to produce an injection molded tube. Can be increased to the level available to you. It is conceivable that the Tg reducing agent increases the ESCR of the polymer in tube manufacturing by effectively increasing the time it takes for the polymer to cool to its crystalline state, thus the polymer molecule Increasing the time available for rearrangement to reduce in-mold stress. As a result, a molded part having a lower molding internal stress than that obtained when Tg is not reduced can be obtained. Thus, the molded part having a good ESCR is obtained. What is a suitable Tg reducing agent? Polypropylene. However, for the most beneficial results in the case of injection molded tubes, it is preferably used with a compatible polymer if the Tg reducing agent itself is not a compatible agent.
[0059]
Poly-2-oxazoline compounds and fluoroelastomers are also suitable for use as compatible polymers. The incorporation of 1-40%, preferably 2-20% poly-2-oxazoline compound improves the ESCR of the polymer (see US Pat. No. 4,474,928). These compatible polymers also improve the adhesion of PE blends to various substrates. This helps to prepare the PE for printing or labeling.
[0060]
ESCR improvement effects of additives such as nucleating agents and Tg reducing agents are
Although not particularly noticeable in molded articles, in molded articles such as thin-walled tubes, the polymer is subjected to fast cooling rates, high injection speeds, high injection pressures, long narrow channels and roundness, so the effect is Even if the additive level is low, it is considered critical. Such additives can improve the ESCR of a polymer to such an extent that the at least one polymer and a sufficient amount of the additive alone are suitable for the production of injection molded articles.
[0061]
In yet another aspect of the invention, the at least one compatibility agent is combined with the at least one polymer. For example, a polymer having a monomer having a compatible group is copolymerized with another monomer to form a compatible polymer. For example, a monomer having a methacrylic acid group is added to the polymerization mixture of the at least one polymer to form a compatible plastomer. Optionally, compatible groups can be grafted onto the polymer. Preferably, the polymer grafted with compatible groups is a plastomer or a substantially linear polyethylene.
[0062]
The polymer blend can be prepared by extrusion of some or all of the components of the polymer blend, and the resulting chopped extrudate is used in the injection molding process of the present invention. Optionally, the polymer blend is provided in its component form and mixed in the process of the present invention before or during the melting of the polymer blend.
[0063]
The polymer blend can be melted by any convenient method. Of particular advantage, the polymer blend is melted in a conventional injection molding machine where both screwing the polymer blend and pressing the molten polymer blend into the mold is accomplished by screw rotation in a heated barrel. It is to be done. The product formed from the polymer blend can be easily removed from the mold by a convenient method.
[0064]
The injection molding method of the present invention enables the production of an injection molded product having a surprisingly thin cross-section while retaining the mechanical properties of the polymer blend. We have found that articles having a cross-section of 0.3 mm to 0.7 mm can be injection molded, and such thin walled articles can have a thin wall exceeding 50 mm in length. These products can be easily manufactured with almost no deterioration of the mechanical properties of the plastic material.
[0065]
The polymer blends of the present invention can injection mold thin cross-sectional products and provide many advantages that could not be achieved so far due to technical constraints. These technical constraints are best explained in the manufacture of thin-walled tubes. These tubes are commercially important and can be extruded, thus eliminating the use of wall thickness control and variation, and producing tubes with controlled and variable wall thickness. The present invention provides for the manufacture of thin section products whose thin walls can be controlled and varied in thickness. For example, in an injection molded tube embodiment, the wall thickness of the tube can be varied along its length. The wall thickness can be thicker at the neck of the tube, thereby increasing flexibility towards the tail. In the present invention, embossing can be performed on the thin wall of the tube. Embossing can be done in the form of a company logo, trademark, various texts, textures such as laser grain or ripple, or surface finish.
[0066]
Yet another advantage of the present invention that has not previously been achieved due to technical constraints is the ability to perform "in-mold" labeling to decorate thin wall tubes. Extruded tubes cannot be decorated by in-mold labeling, and therefore such tubes must be labeled as a separate and expensive manufacturing operation. Tubes made in accordance with the present invention can be in-mold labeled during a single stage manufacturing process. This avoids separate and expensive additional manufacturing operations. Placement of the label within the cavity can be accomplished by various means. This involves opening the mold and placing the label on the core by various means immediately prior to the injection of the polymer, closing the mold, moving the label from the core to the cavity, and forming an in-mold labeled tube. It is also included.
[0067]
A further advantage of the present invention is that the barrier sheath can be applied to all or a portion of the core prior to molding the barrier sheath. This barrier sheath moves into the molded part during the molding process and imparts a barrier or other advantageous property to the tube produced according to the present invention. A further advantage of the present invention is that a coating can be applied to either or both of the mold core and cavity prior to the molding process. The coating then moves to the relevant surface of the molded article during the molding process. By this method, a coating can be provided on the outside or the inside of the tube surface produced in the present invention. Such coatings have various functions such as decoration and barrier.
[0068]
The present invention enables injection molding of thin wall products, and the products can have various shapes and shapes. These have heretofore been constrained in the production of thin wall products due to technical difficulties. For the thin wall tube example, various closures, hooks, or flaps can be incorporated into the design. In the past, in order to join such additional parts, it was necessary to manufacture the parts separately and then attach them to the tube by welding or otherwise. This greatly added to the overall cost of the tube. In the present invention, a single tube having a closure, hooks, flaps or other accessories integrally formed from the same or different polymers by the appropriate use of a tool design and / or two injection molding devices. Can be manufactured in stages.
[0069]
Numerous variations can be made to standard tube tooling to easily make integral tube / attachment moldings, especially integral tube / collagen moldings. Such single tube / collagen moldings can be used in various mold-in hinges (including living hinges), preparatory spouts, and other convenient, if desired. Features can be included in the mold during the molding process. When the polymer is used to mold a single tube / collager, the toughness is insufficient to produce a conventional hinge with a “self-closing” or “flip” mechanism. The hinge may be configured to be rounded. If the polymer is sufficiently flexible, the roundness combined with the flexibility of the polymer provides self-flipping for the closure.
[0070]
An additional advantage of the method of the invention is characterized by the fact that it is possible to produce tubes with special contours for receiving accessories. Conventional features such as self-sealing valves can be easily attached at a relatively low cost. A typical tube / self-sealing closure combination consists of at least four and often five individual components. That is, a two-part tube (tube body and head / shoulder), closure body, self-sealing valve, holding device to secure the valve to the body, and often the valve particularly releases the components A protector to prevent during filling and delivery to retail outlets. The at least three parts of the self-sealing closure are assembled separately and then attached to the tube. The process of the present invention can produce a one-part tube / receptor / flip-top protector to which the valve and retention device can be easily attached. This can reduce the number of parts to be manufactured, the number of steps and complexity of the assembly process. This can greatly reduce the cost of such a tube / closure.
[0071]
In a further aspect, the at least one compatible polymer of the present invention can be used to protect directly on the inner and / or outer thin wall without the need for pretreatment such as corona discharge or flame treatment. Products such as tubes that can be coated with a barrier coating can be manufactured. For example, the incorporation of polyoxazoline compounds improves the adhesion of lacquers and varnishes to such an extent that the need for such pretreatment is reduced. This is an advantage for the containment of substances that require special coatings for food containers or for the contents.
[0072]
Alternatively, suitable barriers and other coatings can be applied by conventional methods such as dipping, spraying, printing, vapor deposition, or vacuum evaporation, the latter method being a metal or non-metal oxide / nitride (eg, silicon oxide) or It is particularly beneficial for the application of particularly high barrier materials such as fluorine and carbon and / or organic groups with useful properties. In addition, some coatings, such as those produced by reaction of the tube polymer with fluorine, further react with monomers containing various beneficial functional groups, further enhancing the properties of the coating. For example, a hydroxyl group-containing monomer reacts with a fluorinated polyethylene coating to produce a hydroxyl group-containing coating.
[0073]
Depending on their nature, the tubes are thin, soft and have a flexible wall. Due to the lack of hardness in the molded tube, the mold core is removed from the core of the mold by conventional mechanical methods such as stripper plates and injector pins, without any potential damage to the molding. It becomes difficult to take out the molded part. A further disadvantage is that the removal speed often required to minimize the chance of damage to the tube during removal is low.
[0074]
What we have found is that compressed gas is used to assist with removal and to minimize the possibility of damage to the tube upon removal. When the tube is formed in the molding cavity and is sufficiently set with respect to the tube to be recovered from the molding cavity, the convex part and concave part of the mold are slid in a nested manner from the concave part to the convex core part. Separate. Simultaneously or subsequently, the molded tube can be separated by injecting a compressed gas from within the convex core, and the compressed gas can communicate with the inner surface of the end of the molded tube. Most preferably, the core end is lifted from the main part of the core and air is injected to break the seal often present between the molded tube and the core, facilitating removal of the molded tube. The molded tube can be relatively slid and separated across the end portion of the convex core portion by raising the end portion and applying pressure under the end portion. To aid in separation, the convex core has a tampered outer surface, and the diameter of the convex core is larger at the end of the tube away from the end.
[0075]
Further, the outer surface of the convex core portion is formed so as to have a slight surface roughness sufficient to inhibit the formation of vacuum sealing between the molded portion and the convex core portion while introducing the pressurized gas. And processed. That is, due to the surface roughness, the pressurized gas flows along the outer surface of the convex core portion, and the molded tube can be expanded to slightly separate the tube from the core.
[0076]
A further improvement to help remove the mold from the cavity is to use pressurized gas so that the pressurized gas flows between the outer surface of the molded part and the inner surface of the cavity immediately before or during the separation of the core from the cavity. It can be injected into the mold, thus assisting the separation of the molded part from the cavity and subsequently removed from the cavity while remaining on the core of the mold.
[0077]
In order to help the polymer flow more easily through the cavity during the injection process and form the thin wall article, a vacuum is evacuated in the cavity immediately before or during the injection of the polymer. Filling the mold can be achieved by cutting longitudinal and / or lateral grooves on one or both sides of the core cavity to direct and / or promote the polymer flow to selected areas within the mold. Can be further helped by balancing.
[0078]
The present invention also allows the use of an expandable core within the mold, which allows the thin wall article to be easily detached from the mold, in a way that was not possible before. This makes it possible to produce a thin-walled container having a wide part next to the part.
[0079]
In the case of a single tube / accessory, if the core is not supported, the core will bend or move sideways (eg, for a large diameter tube made of high MFI material). In this case, FIG. 11 (a) shows a longitudinal section of a mold with an unsupported core from which a single tube / closure can be produced. 11B is a cross-sectional view as viewed from above along line XX in FIG. 11A, and FIG. 11C is a cross-sectional view taken along line XX to YY in FIG. Indicates. As a further reinforcement of the basic tool design, XX ₁ (Or XX ₂ In order to be able to separate the part of the tool defined by the line and the YY line from the part of the tool defined by ZZ from XX ₁ (Or XX ₂ ) Can have splits along the line. Another XX with different closure designs or types ₁ (Or XX ₂ ) A tube having a different closure can be produced by replacing the line and the YY line part [see FIG. 11 (c)]. The same principle can be applied to other types of accessories. This versatile mold can be easily changed with a “change part” for tube types with a variety of different accessories and, if desired, with an appropriate “charge part”, an unattached tube Or a “standard” tube with “head and shoulders”.
[0080]
In the case of a single tube / accessory, core bending occurs easily when the core is not supported. With a single tube / accessory, many designs can stabilize against lateral movement of the core (this can change the wall thickness).
[0081]
FIG. 12 shows a tool design where the core is stabilized using one or more supports against bending. This support protrudes from the top of the recess half of the mold and pushes down onto a “pop” valve on the convex core during the injection of the polymer forming the product. Before the polymer is injected to fill the mold and close the barrel valve, the support can be raised and the polymer can flow into the gap left by the support. Thereby, the formation of the molding is completed. 10 (a) shows a support located on the "pop" valve of the core. 10 (b) shows the lifted support, and the polymer can flow into the gap left by the lifted support. Where appropriate, the support may be located in the “support location region” (11). FIG. 12B is a cross-sectional view taken along the line XX, and shows a series of position regions with respect to the support on the pop valve.
[0082]
FIG. 13 shows a tool design where the core is stabilized against bending using one or more supports [12 (a) and 12 (b)]. The support protrudes from the cavity and supports the core from the side while injecting the polymer to form a product. The advantage of the support 12 (b) is that the support presses the mushroom valve (3) firmly onto the core (4). In this way, the chance of changing the injection pressure is minimized. Once the mold is filled and the barrel valve is closed, the support can be retracted and the polymer can flow into the gap left by the support. Thereby, the formation of the molding is completed.
[0083]
FIG. 14 shows the tool design, extending the extensible support in the core and securing it in the recess of the mold, fixing the core and prohibiting lateral movement of the core. Once the mold is filled and the barrel valve is closed, the support is retracted and the polymer can flow into the gap left by the retracted support. Thereby, the formation of the molding is completed. The deformation of the mechanism is to project the entire core upward and position the core in the recess of the mold. Before the polymer is injected into the mold and shows the barrel valve, the entire core is retracted and the polymer can flow into the new cavity left by the retracted core. Thereby, the formation of the molding is completed. Another advantage of that arrangement (ie, the core is not located through the center of the closure to be formed) is that the center of the closure is not limited by the arrangement of the device. This allows for the formation of fairly complex closures such as drug bottles (e.g. having a spout or membrane that can effectively interrupt the tube contents). In a further variation, the mold can be designed such that a very thin film can be formed across the tip of the closure hole for "tamper evidence" resistance.
[0084]
Among the main advantages of the stabilization mechanism as shown in FIGS. 12-14, the core support is located off-center so that the injection point can be unobstructed at the center position. is there. This allows the formation of “centered” accessories such as holes. It is necessary for the flow control mechanism to be off center. If the position of the hole and other attachments is acceptable or needs to be off-centered, it is possible to center the support through many mechanisms known to those skilled in the art .
[0085]
【Example】
Example 1
Polymer blends obtained from 50% Exact 4038, 20% Catalloy KS059P, and 30% Montell 6100P were injection molded to produce a tubular container. Its main body is a continuous cylinder with a diameter of 35 mm and a length of 150 mm, and the neck shoulder receives a screw cap. The thickness of the continuous cylindrical portion varies from 0.8 mm at the location adjacent to the neck shoulder to 0.5 mm at the end away from it. It has been found that the tubular container has characteristics suitable for use in, for example, the cosmetic industry.
[0086]
Example 2
A polymer blend obtained from 60% Exact 4038 and 40% Montell 6100P was injection molded to produce a tubular container. Its main body is a continuous cylinder with a diameter of 35 mm and a length of 150 mm, and the neck shoulder receives a screw cap. The thickness of the continuous cylindrical portion varies from 0.8 mm at the location adjacent to the neck shoulder to 0.5 mm at the end away from it. It has been found that the tubular container has characteristics suitable for use in, for example, the cosmetic industry.
[0087]
Example 3
Polymer blends obtained from 24% Exact 4038, 56% Affinity 1350, and 20% Surlyn 9970 were injection molded to make a tubular container. Its main body is a continuous cylinder with a diameter of 35 mm and a length of 150 mm, and the neck shoulder receives a screw cap. The thickness of the continuous cylindrical portion varies from 0.8 mm at the location adjacent to the neck shoulder to 0.5 mm at the end away from it. It has been found that the tubular container has characteristics suitable for use in, for example, the cosmetic industry.
[0088]
Example 4
Polymer blends obtained from 24% WSM168 (Orica Australia Pty Ltd), 56% Affinity 1350, and 20% Surlyn 9970 were injection molded to make a tubular container. Its main body is a continuous cylinder with a diameter of 35 mm and a length of 150 mm, and the neck shoulder receives a screw cap. The thickness of the continuous cylindrical portion varies from 0.8 mm at the location adjacent to the neck shoulder to 0.5 mm at the end away from it. It has been found that the tubular container has characteristics suitable for use in, for example, the cosmetic industry.
[0089]
ESCR test
Six thin pieces of injection molded polymer blend, 0.65 mm thickness, were used to quantify environmental stress crack resistance. A 10 mm wide piece is cut in the mold transverse to the main flow direction of the polymer blend and then subjected to some post-mold treatment. Each piece is folded back and stapled at 3 mm from the bend. The folded pieces are immersed in a 10% Teric N9 solution at 50 ° C. (Teric is a trademark of Orica Australia Pty Ltd). The sections were then examined periodically for signs of cracking. Any signs of cracking were considered breakage. The time at which 50% (3) of the pieces failed was considered the failure time for each polymer blend. The test concluded after 360 hours if the polymer was not yet broken.
[0090]
Comparative Example A
A Dow Affinity plastomer having a crystallinity of about 34% was injection molded, and six pieces were cut from the molded product, and an ESCR test was conducted. The results are shown in Table 1 below.
[0091]
Examples 5-7
Dow Affinity plastomer having a crystallinity of about 34% was blended with polypropylene ADP126 (Montell) in the amounts shown in Table 1 below. The blend was injection molded and 6 pieces were cut from the molding and subjected to an ESCR test. The results are shown in Table 1 below.
[0092]
[Table 1]

[0093]
Examples 8-10
Dow Affinity plastomer having a crystallinity of about 34% was blended with Surlyn 9970 (DuPont) in the amounts shown in Table 2 below. The blend was injection molded and 6 pieces were cut from the molding and subjected to an ESCR test. The results are shown in Table 2 below.
[0094]
[Table 2]

[0095]
Example 11
A polymer blend of 80% Dow Affinity (34%), 19% Nylon B3 (BASF), and 1.2% Surlyn 9970 was blended. This polymer blend was injection molded and subjected to an ESCR test. This polymer blend has an ESCR test result of 360+ hours.
[0096]
Examples 12 and 13
A polymer blend of 79% Dow Affinity with about 34% crystallinity and 30% Surlyn 9970 was blended and injection molded to form a thin wall tube. A second polymer blend of 76% Dow Affinity (24% crystallinity), 20% nylon B3 (BASF), and 4% Surlyn was blended and injection molded to form a thin walled container. This thin-walled container was filled with petrol and sealed. The polymer blend formulated with 20% nylon and 4% Surlynl has a permeability to petrol about 20 times less than that of the blend containing only plastomer and Surlyn.
[0097]
Example 14
Dow Affinity plastomers with a crystallinity of about 34% were added in the amount of TiO in the amounts listed in Table 3 below. ₂ And blended. This blend was injection molded, and six pieces were cut from the molding and subjected to an ESCR test. The results are shown in Table 3 below.
[0098]
[Table 3]

[0099]
Those skilled in the art will readily understand variations of the present invention other than those specifically described. The present invention includes all such variations and should be construed as falling within the scope of the invention. The invention also includes all the steps, features, compositions, compounds listed herein, or includes any combination of two or more of the steps or features, individually or collectively.
[Brief description of the drawings]
FIG. 1 is a diagram of a thin-walled container made of the polymer blend of the present invention.
FIG. 2 is a view of a thin wall container made of the polymer blend of the present invention.
FIG. 3 is a view of a thin wall container made of the polymer blend of the present invention.
FIG. 4 is a view of a thin wall container made of the polymer blend of the present invention.
FIG. 5 is a view of a thin-walled container made of the polymer blend of the present invention with hooks joined together. This hook can be replaced as appropriate with a spreader or other desired convenient tool.
FIG. 6 is a view of a thin wall container made of the polymer blend of the present invention, wherein the container is provided with a flange having a hole, the hole adapted to hang the container from a hook or hanger at the time of sale; The
FIG. 7 is an illustration of a polymer blend thin wall container of the present invention wherein the container is provided with a hook adapted to hang the container from a hook or hanger at the point of sale.
FIG. 8 is a cutaway view of a polymer blend thin wall container of the present invention with a barrier coating on the inside of the container.
FIG. 9 is a diagram of a single tube / closure.
FIGS. 10A and 10B are views of a tube having a side pouch, which is for containing items such as product samples, toothbrushes and combs.
FIG. 11 shows details of a support mechanism for a single tube / accessory, particularly a single tube / closure.
FIG. 12 shows details of a support mechanism for a single tube / accessory, particularly a single tube / closure.
FIG. 13 shows details of a support mechanism for a single tube / accessory, particularly a single tube / closure.
FIG. 14 shows details of a support mechanism for a single tube / accessory, particularly a single tube / closure.
[Explanation of sign]
1 Runner for molten polymer
2 “Flip top” hinge lid
3 “Pop” Mushroom Valve
4 cores
5 Stem for the “pop” valve (3)
6 Tube side wall
7 Integrated hinge
8 Channel / groove for polymer flow energized toward the tube side wall
9 Groove for polymer flow energized down the side wall of the tube
10 (a) Support located on mushroom valve (3)
10 (b) Support shown in retracted position
11 Support position on mushroom valve (3)
12 (a) Support located above both core (4) and mushroom valve (3)
12 (b) Support located on core side
13 Extendable core support shown in extension
14 position of support on recess of mold
15 Extendable core support shown in non-extension

Claims (11)

A method for producing a flexible, thin-walled article comprising the steps of: 1) selecting a polymer blend having an ESCR of greater than 10 hours when tested according to the following procedure:
i) Multiple strips of polymer blends having a cross-sectional dimension of 0.65 mm thickness and 10 mm width are injection molded under high shear stress, long channel conditions, which conditions are used in the manufacture of flexible thin wall articles. Equal to, and incorporates post-molding processing for production of the final product in those strips,
ii) Bend the strip back on itself, staple 3mm from the corner,
iii) immersing the bent strip in a solution of a stress cracking agent which is a 10% solution of nonylphenol ethoxylated with 9 molar ethylene oxide and keeping the temperature at 50 ° C.
iv) observing the strip for signs of cracking, considering the signs of cracking as failure, and v) what is taken as the time to failure when 50% of the strips show signs of cracking,
2) melting the polymer blend;
3) pressing the molten polymer blend into a mold, the mold having a cavity that produces a thin wall article having a thin wall thickness of 1 mm or less, and the thin wall portion of the molten polymer blend in the mold 4) a method comprising the step of removing a thin-walled article formed from a polymer blend from a mold, continuous for more than 50 mm in the direction of flow.   The method of claim 1, wherein the polymer blend has an ESCR of greater than 100 hours.   The method of claim 2, wherein the polymer blend has an ESCR of greater than 200 hours.   The method of claim 3, wherein the polymer blend has an ESCR of greater than 360 hours.   Polymer blends are characterized by a superrandom distribution of plastomers, polyethylene, copolymers of ethylene with one or more unsaturated olefins, substantially linear polyethylene, branched polyethylene, metallocene or comonomers within the polymer chain. Polymers and copolymers of ethylene, polypropylene, propylene and ethylene and / or copolymers of one or more unsaturated olefins, metallocenes or comonomers in the polymer chain made with other catalysts to produce the copolymer The group consisting of propylene polymers and copolymers, polylactic acid polymers, silane polymers, and mixtures thereof made with other catalysts that produce copolymers characterized by a superrandom distribution of Ri comprises one polymer selected, the process of claim 1.   The method of claim 1, wherein the polymer blend comprises at least one compatibility agent. At least one compatibilizer is ethylene vinyl acetate, ethylene vinyl alcohol, plasticized polyvinyl acetate and polyvinyl alcohol, alkyl carboxyl substituted polyolefins, copolymers of anhydrides of organic acids, copolymers containing epoxy groups, chlorinated polyethylene, Ethylene-propylene-butylene copolymer, polyethylene, very low density, very low density, low density, medium density and high density, polypropylene, polybutylene and their copolymers , polyester ether, polyether ester, acrylonitrile-methacrylate Copolymer of acrylate, block copolymer with styrene end block, half ester, grafted polyethylene of amino and alkoxysilane, vinyl addition polymer, styrene Tadiene block copolymer, acid grafted polyolefin, vinyl pyrrolidine grafted polyolefin, divalent monomer block copolymer, grafted unsaturated ester of propylene, modified polyolefin, amide group, epoxy group, hydroxy group, or C2-6 acyloxy 7. The method of claim 6, wherein the method is selected from the group consisting of groups, polyoxazolines, containing fluoroelastomers, particles coated with any of the above, and mixtures thereof.   The method of claim 1, wherein the polymer blend comprises at least one nucleating agent.   9. The method of claim 8, wherein the at least one nucleating agent is selected from the group consisting of talc, mica, various metal compounds and various organic compounds.   The polymer blend comprises at least one polymer, which is a substantially linear polyethylene or a copolymer characterized by a superrandom distribution of comonomers within the polymer chain, and the at least one compatibilizer is a polypropylene-based polymer. The method of claim 1 which is a polymer.   The method of claim 1, wherein the thin-walled article is a tube.

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